l-8 reservoir pilot test technical document

L-8

L-8 RESERVOIR PILOT TEST Technical Document

January 2015 Revised July 2018

SOUTH FLORIDA WATER MANAGEMENT DISTRICT

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L-8 Reservoir Pilot Test Technical Document

i | Aknowledgements

Acknowledgements

The South Florida Water Management District (District) gratefully acknowledges the contributions of many District professionals, and stakeholder and agency partners who made the following pilot test and report possible. ACKNOWLEDGEMENT OF STAKEHOLDER AND AGENCY PARTNERS The District acknowledges all of our partners for their contributions, participation, and encouragement prior to and during the project. Without their involvement, the success of this project would not have been possible. The following is a list of agencies that provided feedback and input to the District prior to and during the project. Callery-Judge Grove City of West Palm Beach Cypress Grove Community Development District Florida Department of Environmental Protection Indian Trail Improvement District Loxahatchee River District Loxahatchee River Management Coordinating Council Martin County Palm Beach County Seminole Improvement District United States Army Corps of Engineers ACKNOWLEDGEMENT OF DISTRICT PROFESSIONALS The following managers who supported this effort are recognized: Blake Guillory, Executive Director Terrie Bates, Director, Water Resources Division Susan Gray, Applied Sciences Bureau Chief Dee Azeredo, Water Quality Bureau Chief In particular, the following contributors are acknowledged and appreciated: Technical Leads Don Medellin Scott Thourot


ii | Aknowledgements

Principal Authors Guang-Dou Hu Scott Huebner Jason Godin Laura Kuebler Don Medellin John Raymond David Swift Scott Thourot Yongshan Wan Supporting Contributors to the Document Joe Albers Michael Chimney Guy Germain Nenad Iricanin Beth Kacvinsky Wasantha Lal Bradley Robbins Robert Verrastro Toni Edwards Technical Editing Kim Chuirazzi


iii | Executive Summary

Executive Summary The L-8 Reservoir is a former 950-acre rock mine located in central Palm Beach County. Its deep configuration and watertight geology allows below-ground water storage, reduced water loss through seepage, and minimized levee safety concerns. With a 45,000 acre-foot (ac-ft) capacity, it is capable of capturing and storing 15 billion gallons of stormwater from the L-8 Basin that are currently discharged to the Lake Worth Lagoon. While originally developed for providing long-term increased flows to Grassy Waters Preserve and the Northwest Fork, the L-8 Reservoir is now intended to function primarily as a flow equalization basin for delivering controlled flows to the Everglades Stormwater Treatment Areas south of Lake Okeechobee.

The L-8 Reservoir Pilot Test was conducted in 2011 as part of the Comprehensive Everglades Restoration Plan (CERP) Loxahatchee River Watershed Restoration Project (previously known as the North Palm Beach County – Part 1 Project) (USACE and SFWMD, 2005). The purpose of this CERP project is to capture, store, and treat excess water currently discharged to the Lake Worth Lagoon and use that water to enhance the Loxahatchee River and Slough, and provide water supplies to the West Palm Beach Water Catchment Area known as the Grassy Waters Preserve. One of the goals of the project is to provide restorative flows to the Northwest Fork of the Loxahatchee River (Northwest Fork).

The purpose of the L-8 Reservoir Pilot Test was to evaluate operational capabilities of the CERP Project Flow-way 1 component (Figure 1) to provide supplemental water to the Northwest Fork during dry periods. The primary goal of the pilot test was to deliver surface water from the L-8 Reservoir, through Grassy Waters Preserve via Flow-way 1, to the Northwest Fork at Lainhart Dam. Another goal of the project was to perform operational testing of the existing facilities and gain an understanding of the constraints associated with making water deliveries.

During the pilot test, water was delivered to the Northwest Fork for a total of 50 days during an extremely dry period, from March 1 through April 19, 2011. Prior to, during and following the pilot test, water quality and hydrologic data were collected and evaluated. The minimum flow and level criteria (MFL) for the Northwest Fork, measured at the Lainhart Dam, were met for 47 days of the 50-day test. Approximately 3,005 acre-feet of water were delivered from Grassy Waters Preserve via the G-161 structure to the Northwest Fork. The successful implementation of the pilot test demonstrated that it is possible to deliver water from the L-8 Reservoir to the Northwest Fork during extremely dry periods.

While water was delivered successfully from the L-8 Reservoir to the Northwest Fork via Grassy Waters Preserve, it proved to be challenging, due in part to the presence of multiple control structures along a 28.8-mile conveyance route, and limitations of the existing pump facilities. In addition, there were complexities and constraints related to operations, water quality, wildlife concerns, availability of regional water, agricultural and public water supply needs, and water losses attributable to evapotranspiration and seepage.


iv | Executive Summary



v | Table of Contents

Table of Contents EXECUTIVE SUMMARY .................................................................................................... III

TABLE OF CONTENTS ...................................................................................................... V

LIST OF TABLES .......................................................................................................... VII

LIST OF FIGURES .......................................................................................................... IX

LIST OF ACRONYMS, ABBREVIATIONS AND UNITS OF MEASUREMENT ............................................ XI

INTRODUCTION ............................................................................................................. 1

Purpose ................................................................................................................. 1

Background ............................................................................................................ 1

Comprehensive Everglades Restoration Plan ............................................................... 1 Previous Water Deliveries ...................................................................................... 1

Project Description and Facilities ................................................................................. 3

Regional Water Conditions ..................................................................................... 4

COORDINATION WITH STAKEHOLDERS AND AGENCY PARTNERS ................................................... 5

Option 1A ......................................................................................................... 6 Option 1B ......................................................................................................... 6

PERMIT REQUIREMENTS ................................................................................................... 7

Permit History ......................................................................................................... 7

Compliance ....................................................................................................... 8

PILOT TESTING ............................................................................................................. 9

Hydrology .............................................................................................................. 9

L-8 Reservoir Pumping Data ................................................................................... 9 L-8 Canal Stages ............................................................................................... 10 Control 2 Pumping and Control 4 Discharges ............................................................. 10 Flows Delivered to Grassy Waters Preserve and the Northwest Fork ................................ 11 Stages Along the Conveyance Route ....................................................................... 11 Flow Differences Between Reaches of the Conveyance Route ........................................ 11 G-92 and Lainhart Dam Stream Gauge Results ........................................................... 16 M-Canal and Grassy Waters Preserve Water Budget .................................................... 17

WATER QUALITY MONITORING ........................................................................................ 21

Chlorides ............................................................................................................. 21

Chlorides at the Northwest Fork of the Loxahatchee River ................................................. 27

Total Phosphorus ................................................................................................... 28


vi | Table of Contents

POST-PROJECT MONITORING .......................................................................................... 31

Specific Conductance Measurements ........................................................................... 31

L-8 Canal and M-Canal ............................................................................................. 31

Grassy Waters Preserve ........................................................................................... 31

Lake Mangonia/Clear Lake ........................................................................................ 33

PROJECT IMPLEMENTATION AND COSTS ............................................................................. 35

CONCLUSIONS ............................................................................................................ 37

RECOMMENDATIONS ..................................................................................................... 39

REFERENCES .............................................................................................................. 41

APPENDIX A ............................................................................................................... 43

Water Quality Monitoring Sites................................................................................... 43

APPENDIX B ............................................................................................................... 53

Chloride Concentration Regression Equation Calculation ................................................... 53

APPENDIX C ............................................................................................................... 57

Flow Monitoring ..................................................................................................... 57

APPENDIX D ............................................................................................................... 67

Data Used in the Water Budget .................................................................................. 67

APPENDIX E ............................................................................................................... 71

Climate, Stage and Flow Data .................................................................................... 71

APPENDIX F ............................................................................................................... 79

Model Refinements ................................................................................................. 79

Pilot Test Relationship to Everglades Restoration ....................................................... 79 Hydrologic Modeling Approach .............................................................................. 81 Investigating Seepage Assumptions ........................................................................ 81 Applying a Seepage Assumption to Predictive Applications............................................ 85 Additional Tools for Seepage Calculations ................................................................ 87 Management Recommendation ............................................................................. 87 Conclusion ...................................................................................................... 88 References ...................................................................................................... 89

APPENDIX G ............................................................................................................... 91

Water Budget Model ............................................................................................... 91

Water Budget Model Formulation .......................................................................... 91 Water Budget Model Calibration ............................................................................ 92 References ...................................................................................................... 94


vii | List of Tables

List of Tables Table 1. Flow volumes at the G-161, G-160 and G-92 structures and the Lainhart Dam during the

pilot test. ............................................................................................. 11

Table 2. Mean flow by reach and discharge differences between upstream and downstream sections of the M-Canal flow path. ............................................................... 14

Table 3. Measured and computed flows at the G-92 structure and Lainhart Dam on March 14, 2011. ................................................................................................... 16

Table 4. M-Canal and Grassy Waters Preserve water budgets during the L-8 Pilot Test from March 1 through April 19, 2011. .......................................................................... 19

Table A-1. Project surface water quality monitoring sites and GPS coordinates.1 .................... 43

Table A-2. Project water quality monitoring sampling parameters and frequencies. ................ 45

Table A-3. Total phosphorus concentrations at 11 sites located within the L-8 Reservoir, L-8 Canal, M-Canal, Grassy Waters Preserve and Lake Mangonia/Clear Lake. ......................... 45

Table A-4. Total phosphorus concentrations at inflows and outflows of the L-8 Reservoir. ......... 46

Table A-5. Calculated chloride concentrations within the L-8 Reservoir, L-8 Canal and M-Canal for the L-8 Reservoir Pilot Test. ...................................................................... 48

Table A-6. Calculated chloride concentrations within Grassy Waters Preserve and Lake Mangonia/Clear Lake during the L-8 Reservoir Pilot Test. ................................... 50

Table D-1. Data used in the water budget. ................................................................... 68

Table E-1. Climate, stage, flow and chloride data for the L-8 Reservoir and along Flow-way 1. .. 73

Table F-1. Evaluation criteria for seepage assumption. ................................................... 88


viii | List of Tables



ix | List of Figures

List of Figures Figure 1. Flow-way 1 of the CERP Loxahatchee River Watershed Restoration Project for the

delivery of L-8 Reservoir water through Grassy Waters Preserve to the Northwest Fork of the Loxahatchee River at Lainhart Dam. ............................................................ 2

Figure 2. Daily L-8 Reservoir stages and pump discharges (mean daily flow in cfs) during the pilot test. ........................................................................................................ 9

Figure 3. Flow through the Control 2 pump station (pumped from L-8 Tieback Canal) and the Control 4 structure (downstream discharge) during the pilot test. ........................... 10

Figure 4. Schematic of M-Canal indicating the four sections and highlighting the five reaches where stage and flow measurements were taken as part of the pilot test. ......................... 12

Figure 5. Flow at G-161, G-160, G-92 and Lainhart Dam during the pilot test. ........................ 13 Figure 6. Stage at G-161, G-160, G-92 and Lainhart Dam during the pilot test. ....................... 13 Figure 7. Groundwater wells in the area around M-Canal with recommended wells highlighted with

red circles. .............................................................................................. 16 Figure 8. Conceptual model of the water budget for M-Canal and Grassy Waters Preserve. ........ 18 Figure 9. Water budget of M-Canal and Grassy Waters Preserve (ac-ft) during the pilot test. ...... 19 Figure 10. Water quality sampling stations monitored as part of the pilot test. ........................ 22 Figure 11. Calculated chloride concentrations in the L-8 Reservoir (L8RES), L-8 Canal mixing zone

(L8MZBN, L8MZBS), Control 2 pump station (L8MCNL), and L-8 Canal north of the L-8 Canal Tieback Levee (L8-04.3) for the period February 25, 2011 through May 6, 2011. .. 23

Figure 12. Calculated chloride concentrations in Grassy Waters Preserve station GW3, GW4, GW7, GW8, G-161 for the period February 25, 2011 through May 6, 2011. ........................ 24

Figure 13. Chloride lag time response between station GW4 and the Control 2 pump station before, during, and after the pilot test. .................................................................... 25

Figure 14. Calculated chloride concentrations at the Control 4 structure and the Lake Mangonia/Clear Lake monitoring site (LM 1) for the period February 25, 2011 through May 6, 2011. .................................................................................................. 27

Figure 15. Salinity in the Northwest Fork of the Loxahatchee River before, during and after the pilot test. ...................................................................................................... 28

Figure 16. TP concentrations in the L-8 Reservoir (L8RES), L-8 Canal mixing zone (L8MZBN, L8MZBS), Control 2 pump station (L8MCNL), and the L-8 Canal north of the L-8 Canal Tieback Levee (L8-04.3) before, during and after the pilot test. ............................................... 29

Figure 17. Total phosphorus concentrations in Grassy Waters Preserve at stations GW3, GW4, GW7, GW8, G-161 and Lake Mangonia/Clear Lake (LM 1) before, during and after the pilot test. ............................................................................................................ 30

Figure 18. Calculated chloride concentrations (mg/L) in the L-8 Reservoir, L-8 Canal, M-Canal, Grassy Waters Preserve and southern extent of Lake Mangonia on May 25, 2011. ........ 32

Figure 19. Calculated mean daily chloride concentrations at the Lake Mangonia/Clear Lake station (LM1), observed before, during and after the pilot test. ....................................... 34

Figure A-1. Water quality sampling stations monitored as part of the pilot test. ........................ 44 Figure B-1. Relationship between measured chloride and specific conductance data (L-8 Equation)

collected weekly at 121 reservoir stations and 997 canal stations (n = 1,118) from October 2005 to September 2006. .................................................................. 53

Figure B-2. New relationship between chloride and specific conductance (QUAD2). .................... 54


x | List of Figures

Figure B-3. Comparison of predicted chloride values (using QUAD2 and L8EQ) to the measured chloride values at the corresponding specific conductance used to predict chloride. .... 56

Figure C-1. Stream gauge measurements on March 7, 2011 at Reach 1. ................................... 58 Figure C-2. Stream gauge measurements on March 8, 2011 at Reaches 2, 4 and 5. ..................... 59 Figure C-3. Stream gauge measurements on March 17, 2011 at Reaches 2 and 3. ....................... 60 Figure C-4. Stream gauge measurements on March 22, 2011 at Reach 2. .................................. 61 Figure C-5. Stream gauge measurements on March 30, 2011 at Reach 1. .................................. 62 Figure C-6. Time series plots of discharges upstream and downstream of Reach 1. ..................... 63 Figure C-7. Time series plots of discharges upstream and downstream of Reach 2. ..................... 64 Figure C-8. Time series plots of discharges upstream and downstream of Reach 3. ..................... 65 Figure C-9. Time series plots of discharges upstream and downstream of Reach 4. ..................... 65 Figure C-10. Time series plots of discharges upstream and downstream of Reach 5. ..................... 66 Figure F-1. Flow path for the delivery of L-8 Reservoir water to Grassy Waters Preserve and the

Northwest Fork of the Loxahatchee River. ........................................................ 80 Figure F-2. Schematic of M-Canal indicting the four sections and highlighting the five reaches where

measurements were conducted. .................................................................... 82 Figure F-3. Average monthly modeled seepage for Reaches 1, 4 and 5 as simulated by the LECsR with

the MODFLOW river package applied. .............................................................. 83 Figure F-4. Sensitivity run comparison stage duration curve for the L-8 Reservoir. ..................... 84 Figure F-5. Sensitivity run comparison flow duration curve for the Lainhart Dam. ...................... 85 Figure G-1. Daily pumping rate of Control 2 and calculated flows at Control 3 compared with stream

gauge values. ........................................................................................... 93 Figure G-2. Grassy Waters Preserve stage simulated using the water budget model compared to stage

measured at G-161 with rainfall plotted to show its effect on stage. ....................... 94


xi | List of Acronyms, Abbreviations and Units of Measurement

List of Acronyms, Abbreviations and Units of Measurement

ac-ft acre-feet

ac-ft/d/ft acre-feet per day per foot

CERP Comprehensive Everglades Restoration Plan

CERPRA Comprehensive Everglades Restoration Plan Regulation Act

cfs cubic feet per second

CWPB2 City of West Palm Beach Control 2 pump station

CWPB3 City of West Palm Beach Control 3 structure

CWPB4 City of West Palm Beach Control 4 structure

District South Florida Water Management District

DS downstream

ET evapotranspiration

FAC Florida Administrative Code

FDEP Florida Department of Environmental Protection

FS Florida Statute

ft NAVD88 feet North American Vertical Datum of 1988

ft NGVD feet National Geodetic Vertical Datum

ft NGVD29 feet National Geodetic Vertical Datum of 1929

FY# fiscal Year followed by the last two digits of the year

GPS global positioning system

L8EQ name of regression equation used for predicting chloride concentrations

LECsR Lower East Coast Subregional Model

LECsR-NP Northern Palm Beach County version of the Lower East Coast Subregional Model

MFL minimum flows and levels criteria

mg/L milligrams per liter

MODFLOW Modular Three-dimensional Finite-difference Groundwater Flow Model

ppt parts per thousand


xii | List of Acronyms, Abbreviations and Units of Measurement

QUAD 2 refers to a relationship between chloride and specific conductance

Std. Error standard error

TP total phosphorus

US upstream

USACE United States Army Corps of Engineers

USGS United States Geological Survey

WPB West Palm Beach

μg/L micrograms per liter

μS/cm microsiemens per centimeter


1 | Section 1: Introduction

1 Introduction

PURPOSE The L-8 Reservoir Pilot Test was conducted in 2011 as part of the Comprehensive Everglades Restoration Plan (CERP) Loxahatchee River Watershed Restoration Project (previously known as the North Palm Beach County – Part 1 Project) (USACE and SFWMD, 2005). The purpose of this CERP project is to capture, store, and treat excess water currently discharged to the Lake Worth Lagoon and use that water to enhance the Loxahatchee River and Slough, and provide water supplies to the West Palm Beach Water Catchment Area known as the Grassy Waters Preserve. One of the goals of the project is to provide restorative flows to the Northwest Fork of the Loxahatchee River (Northwest Fork). The purpose of the L-8 Reservoir Pilot Test was to evaluate operational capabilities of the CERP Project Flow-way 1 component (Figure 1) to provide supplemental water to the Northwest Fork during dry periods. The primary goal of the pilot test was to deliver surface water from the L-8 Reservoir, through Grassy Waters Preserve via Flow-way 1, to the Northwest Fork at Lainhart Dam. Another goal of the project was to perform operational testing of the existing facilities and gain an understanding of the constraints associated with making water deliveries. The purpose of this report is to document the data collection, analysis, and results of the L-8 Reservoir Pilot Test and associated water quality analyses.

BACKGROUND Comprehensive Everglades Restoration Plan

Flow-way 1 is the most southerly and longest of three proposed flow-ways identified to provide restorative flows to the Loxahatchee River in the CERP Loxahatchee River Watershed Restoration Project. It extends 28.8 miles, from the L-8 Reservoir to Lainhart Dam on the Northwest Fork (Figure 1)Error! Reference source not found..

Previous Water Deliveries

Water deliveries from the regional system to the Northwest Fork were previously made using existing facilities during short-term non-drought condition tests conducted July 1–3, 2008 (SFWMD 2008). The source of water from the regional system for these tests came from Water Conservation Area 1. The 2008 project demonstrated that water deliveries to the Northwest Fork were possible using existing infrastructure. Daily average flows delivered from Grassy Waters Preserve through the G-161 structure (located at Northlake Boulevard) were 41, 91 and 50 cubic feet per second (cfs) on July 1, 2 and 3, 2008, respectively. The water deliveries through G-161 resulted in increased flows at Lainhart Dam. Several of the recommendations outlined in the 2008 report were taken into consideration during the planning of the pilot test described in this document.



Figure 1. Flow-way 1 of the CERP Loxahatchee River Watershed Restoration Project for the delivery of L-8 Reservoir water

through Grassy Waters Preserve to the Northwest Fork of the Loxahatchee River at Lainhart Dam.

Note: WPB - West Palm Beach.



PROJECT DESCRIPTION AND FACILITIES The L-8 Reservoir is a former 950-acre rock mine located in central Palm Beach County. Its deep configuration and watertight geology allows below-ground water storage, reduced water loss through seepage, and minimized levee safety concerns. With a 45,000 acre-foot (ac-ft) capacity, it is capable of capturing and storing 15 billion gallons of stormwater from the L-8 Basin that are currently discharged to the Lake Worth Lagoon. Initially approved in 2002, completion of the reservoir’s storage cells was expedited by the District along with several water control structures in the river’s watershed designed to reconnect historical flow paths. When construction of inflow works and the outflow pump station are complete, the reservoir will be able to accept up to 3,000 cubic feet per second (cfs) of stormwater inflows. The stored water can then be pumped to where it is needed for environmental enhancement, at a discharge rate of up to 450 cfs. The target reservoir project completion date is December 2016. Grassy Waters Preserve is a 12,800-acre natural area located in northern Palm Beach County owned and operated by the City of West Palm Beach. This natural area was established as a preserve to supplement the city’s public water supply needs. The M-Canal is an existing drainage canal that extends from west to wst through the preserve which routinely conveys surface water, from Lake Okeechobee to Lake Mangonia and Clear Lake, for water supply.

Grassy Waters Preserve is part of the historic headwaters of the Loxahatchee National Wild and Scenic River and contains a regionally significant wetland system that is contiguous to other natural areas, including the Loxahatchee Slough, Hungryland Slough and J. W. Corbett Wildlife Management Area. It also provides important habitat to several threatened and endangered (listed) species including, the Everglades snail kite (Rostrhamus sociabilis plumbeus), Florida sandhill crane (Grus canadensis pratensis), roseate spoonbill (Ajaia ajaja), wood stork (Mycteria americana), and an array of other listed and non-listed wading birds, amphibians, reptiles and mammals.

The L-8 Reservoir Pilot Test included the surface waters of Lake Okeechobee, Lake Mangonia, Clear Lake, and the Northwest Fork, and water storage and conveyance features currently owned by the District and the City of West Palm Beach. These publicly owned storage and conveyance features include, but are not limited to, the L-8 Reservoir, L-8 Canal, L-8 Tieback Canal, City of West Palm Beach Control 2 pump station and Control 4 water control structure, M-Canal, Grassy Waters Preserve, District G-161, G-160 and G-92 water control structures, and the Lainhart Dam (Figure 1Error! Reference source not found.).

During the pilot test, water was delivered to the Northwest Fork for a total of 50 days during an extremely dry period, from March 1 through April 19, 2011. An existing 75-cfs pump located at the L-8 Reservoir was used to deliver water north through the L-8 Canal into the L-8 Tieback Canal where it mixed with gravity outflows from Lake Okeechobee (via Culvert C-10A). The mixed water was pumped eastward by the City of West Palm Beach Control 2 pump station (permitted at 165 cfs), through the M-Canal for a distance of 9.4 miles, and into Grassy Waters Preserve. After entering the preserve, the water continued to flow east via the M-Canal to the Control 4 water control structure where it was released to Lake Mangonia and Clear Lake, which provide water supply for the City of West Palm



Beach. Water was also delivered north through the G-161, G-160 and G-92 structures to the Northwest Fork.

The pilot test’s objectives were to do the following:

• Obtain a broader understanding of the operational complexities involved in routing L-8 Reservoir water to the Northwest Fork during dry periods.

• Obtain data on water deliveries, and associated conveyance losses associated with making deliveries, to enable scientists and engineers working on the Loxahatchee River Watershed Restoration Project to determine the appropriate pumping capacity needed to make the L-8 Reservoir operational.

While originally developed for providing increased flows to Grassy Waters Preserve and the Northwest Fork, the L-8 Reservoir is now intended to function primarily as a flow equalization basin for delivering controlled flows to the Everglades Stormwater Treatment Areas south of Lake Okeechobee. It will support Loxahatchee River restoration as an interim measure. However, the former Mecca Farms property is now slated to capture excess water in the C-18 Canal to be conveyed through the CERP Loxahatchee River Watershed Restoration Project Flow-way 2 to the Northwest Fork as a long-term recovery strategy to support the minimum flow and level (MFL) for the Northwest Fork established in Rule 40E-8.221(4), Florida Administrative Code (FAC).

Regional Water Conditions

The stage elevation within Lake Okeechobee at the beginning of the pilot test, expressed as an average of lake stations L001, L005, L006 and L240, was 12.09 feet National Geodetic Vertical Datum of 1929 (NGVD29). Lake Okeechobee stage is important because this is the source of water delivered from the L-8 Canal to the City of West Palm Beach for public water supply. In contrast, the initial stage within Grassy Waters Preserve was 18.69 ft NGVD29 on March 1, 2011. The amount of water available from the regional system as a whole played an important role in the ability to provide sufficient mixing of water to comply with Florida water quality standards (Rule 62-302, FAC). The 2009–2010 dry season was one of the wettest dry seasons on record, which may explain why Grassy Waters Preserve was filled near capacity at the beginning of the pilot test. As the 2010–2011 dry season progressed, water conditions became increasingly dry. The period from October 2010 to May 2011 was the driest on record for Palm Beach County (rainfall deficit of 13.88 inches), which dates back to 1939, with a total of 12 inches of average rainfall recorded for this period. Furthermore, the 2010 rainfall deficit exceeded the record set during the 1970 to 1971 dry season. The 2010–2011 dry season was prolonged and extended into a portion of the 2011 wet season, resulting in a reduction of available regional water that could be delivered to Grassy Waters Preserve and the Loxahatchee River. To put the changing conditions into perspective, on August 29, 2010, the elevation of Lake Okeechobee was 14.07 ft NGVD29, very close to the historical average of 14.17 ft NGVD29. On August 29, 2011, Lake Okeechobee stage was 10.65 ft NGVD29.


5 | Coordination with Stakeholders and Agency Partners

2 Coordination with

Stakeholders and Agency Partners The L-8 Reservoir Pilot Test project was coordinated and implemented through a collaborative process between the District and a number of stakeholder and agency partners. The Florida Department of Environmental Protection (FDEP) authorized state approval of the pilot test prior to its implementation and provided helpful guidance on the permit application package during pre-application meetings. Without the cooperation and contributions by the City of West Palm Beach, this pilot test project would not have been possible. The Seminole Improvement District, Callery Judge Grove, and Cypress Groves Community Development District provided excellent feedback during the operation of the pumps. These existing legal users rely on surface water for irrigation of crops within the L-8 Basin. The following sequence of events demonstrates the coordination that occurred between the various contributors, from the project’s inception to completion.

• July 14, 2010 – The District received a letter from the Loxahatchee River Management Coordinating Council requesting District staff time to develop operational criteria to provide additional water to the Northwest Fork of the Loxahatchee River.

• August 3, 2010 - A District technical team convened to identify opportunities that could be implemented to provide additional water to the river during dry periods.

• October–December 2010 – A series of meetings were held with Palm Beach County, Loxahatchee River District, City of West Palm Beach, Indian Trail Improvement District, Martin County and District staff to discuss options for providing additional water to the Loxahatchee River.

• An interagency technical team was established to develop a plan for making deliveries to the river. As a result of the discussions, the technical team recommended that a short-term pilot test be conducted to deliver L-8 Reservoir water to the Northwest Fork during the 2011 and 2012 dry seasons (Options 1A and 1B).

• At the January 12, 2011 District Governing Board meeting, the board directed staff to develop operational protocols for delivering water from the L-8 Reservoir to the Northwest Fork. The board also directed staff to budget money to design the L-8 Reservoir pump station and to later request cost sharing from the United States Army Corps of Engineers (USACE).


6 | Coordination with Stakeholders and Agency Partners

• At the February 3, 2011 Water Resources Advisory Committee meeting, District staff presented six local water storage options for providing additional water to the Northwest Fork.

• At the March 17, 2011 Palm Beach County Water Resources Task Force meeting, District staff presented the same options referenced above to provide increased deliveries, and staff provided additional details about Option 1A (30-day pilot test). The information listed below provides additional insights regarding Options 1A and 1B that were presented to the Task Force on March 17, 2011.

• On July 11, 2011, District staff provided a presentation with the preliminary results of the L-8 Reservoir Pilot Test to the Loxahatchee River Management Coordinating Council. The presentation included results from the flow monitoring, updated water quality results and preliminary findings.

Options 1A and 1B, as presented to the Palm Beach County Water Resources Task Force on March 17, 2011, are discussed below.

Option 1A

Option 1A was a short-term approach initially envisioned as a 30-day pilot test to deliver water from the L-8 Reservoir to the Northwest Fork using existing infrastructure. The existing infrastructure included a 75-cfs pump located on the L-8 Reservoir. This pump would be used to deliver water from the reservoir to the Control 2 pump station via the L-8 Canal and L-8 Tieback Canal. Water would be moved into Grassy Waters Preserve and ultimately into the Northwest Fork and Lake Mangonia and Clear Lake using the Control 2 pump station, which is permitted at 165 cfs. A water quality monitoring plan was also developed to comply with FDEP permit requirements. The final element of the plan involved documentation of the pilot test and its results and findings in a technical report. The 2010–2011 dry season provided a unique opportunity to collect hydrologic data to assist staff in refining the model used to determine the most appropriate size pumps needed for the L-8 Reservoir station to provide restorative flow targets for the Northwest Fork. It also provided an opportunity to understand losses from seepage and evapotranspiration within the M-Canal and Grassy Waters Preserve.

Option 1B

Option 1B was a larger-scale approach envisioned for the 2011–2012 dry season with a longer implementation period. This approach involved the same elements of Option 1A with a longer duration of pumping (over 120–130 days) from the L-8 Reservoir to the L-8 Canal. It was anticipated that the Control 2 pump station would be replaced by the 2012 dry season to allow increased deliveries without interfering with City of West Palm Beach public water supply deliveries. When Option 1B was presented to the interagency technical team, it was still contingent upon getting final budget approval for the pilot test from the District Governing Board. Sufficient funding for Option 1B was not authorized by the Governing Board so this option was considered no longer viable.


7 | Permit Requirements

3 Permit Requirements

PERMIT HISTORY A Comprehensive Everglades Restoration Plan Regulation Act (CERPRA) permit (Number 0188365-005) was issued by FDEP on March 30, 2007 authorizing the interim operation of the L-8 Reservoir to provide increased storage within the L-8 Basin. The waters in the L-8 proximal to the L-8 Reservoir are Class III State waters (Fish Consumption; Recreation, Propagation and Maintenance of a Healthy, Well-Balanced Population of Fish and Wildlife). The waters of the M-Canal from its confluence with the L-8 Canal to Lake Mangonia are Class I State waters (Potable Water Supplies). Since the permit authorizes discharges from the L-8 Reservoir, and in anticipation of elevated specific conductance in the L-8 Canal proximal to the reservoir as the result of doing so, the permit included an 800-meter mixing zone for specific conductance in the L-8 Canal from the point of discharge from the L-8 Reservoir (permit Specific Condition 22). The 800-meter length would be Class III waters. Specific Condition 22 requires that specific conductance within the mixing zone and at the mixing zone boundary meet Class III specific conductance standards, and prohibits discharges from the L-8 Reservoir when these conditions are not met. The permit was modified several times since the approval of the original permit, to include the addition of new cells, cell connections, monitoring reductions, and renewals.

The pilot test project would be conducted utilizing the L-8 Reservoir as a source of water for water delivery to Grassy Waters Preserve and then north to the Northwest Fork during the 2010–2011 dry season (March–April 2011). In consideration of potential water quality issues that might be associated with the pilot test project, and pursuant to subsection 373.406(6), Florida Statutes (FS), the District submitted a request to FDEP on February 18, 2011 for a temporary exemption from Specific Condition 22 of the permit, which would allow flexibility in implementation of the pilot test project.

On February 28, 2011, FDEP authorized the exemption for a limited duration of time (30 consecutive or non-consecutive days). The exemption temporarily lifted the requirement to cease discharges from the L-8 Reservoir when specific conductance exceeded Class III standards within and at the mixing zone boundary, effectively providing a mixing zone with a specific conductance criterion in excess of Class III standards from the point of discharge at the L-8 Reservoir to Lake Mangonia. The exemption required that during the pilot test, the District provide water quality monitoring data, along with an analysis of the data, to the FDEP within 45 days of completion of the pilot test.


8 | Permit Requirements

Compliance

On March 29, 2011, the District provided the FDEP with initial water quality results from the pilot test and requested an extension of the exemption to collect additional information necessary for the design and planning aspects associated with the Loxahatchee River Watershed Restoration Project. On April 4, 2011, the FDEP granted an extension of the exemption for an additional 30 days (consecutive or non-consecutive days of pumping) to continue the pilot test. This extension was based on preliminary water quality data submitted that demonstrated compliance with the permitted specific conductance limit at the mixing zone boundary.


9 | Pilot Testing

4 Pilot Testing

HYDROLOGY

L-8 Reservoir Pumping Data

Pumping at the L-8 Reservoir was initiated on March 1, 2011 and ended on April 19, 2011. The 75-cfs pump located at the L-8 Reservoir was operated 24 hours a day during that period except for the first and last days of the test, and during required maintenance. During the pumping period, 8,163 ac-ft of water was pumped from the reservoir into the L-8 Canal. The stage in the reservoir decreased 6.76 feet from 6.28 ft NGVD29 to -0.48 ft NGVD29; an average of 0.14 feet per day. Figure 2 depicts daily stages and pump discharges for the reservoir. Appendix E of this report contains the data for Figure 2.

Figure 2. Daily L-8 Reservoir stages and pump discharges (mean daily flow in cfs) during the pilot test.


10 | Pilot Testing

L-8 Canal Stages

During the pilot test, L-8 Canal stages, measured at a point adjacent to the L-8 Reservoir (station L8GRC in the District’s hydrometeorological database DBHYDRO; L8GRRC in the operational control system OaSYS), varied from a minimum of 11.14 ft NGVD29 on April 19, 2011 to a maximum of 11.78 ft NGVD29 on March 11, 2011. At the start of the pilot test period (March 1, 2011), the mean daily stage in the L-8 Canal was 11.37 ft NGVD29.

Control 2 Pumping and Control 4 Discharges

During the pilot test, the City of West Palm Beach operated pumps at their Control 2 pump station on the L-8 Tieback Canal, providing approximately 12 hours of pumping for public water supply and 12 hours of pumping for environmental deliveries from the L-8 Reservoir. The Control 2 pump station ran continuously throughout the pilot test period except during periods of required maintenance. The water pumped by the Control 2 pump station was a mixture of water from the L-8 Reservoir, L-8 Canal water derived from Lake Okeechobee, and to a limited extent, L-8 Basin runoff. The total amount of water pumped from the Control 2 pump station into the M-Canal during the pilot test was 13,640 ac-ft. The Control 4 three-bay, adjustable weir water control structure (Control 4 structure), located downstream of the Control 2 pump station and Grassy Waters Preserve on the M-Canal, discharged 5,238 ac-ft of water during the test period. Discharges from the Control 4 structure provided water to Lake Mangonia and Clear Lake for public water supply. Figure 3 shows the daily flow rate through the Control 2 pump station and the Control 4 structure. Appendix E contains the data for Figure 3.

Figure 3. Flow through the Control 2 pump station (pumped from L-8 Tieback Canal)

and the Control 4 structure (downstream discharge) during the pilot test.


11 | Pilot Testing

Table 1. Flow volumes at the G-161, G-160 and G-92 structures and the Lainhart Dam during the pilot test.

Structure/Pump Pilot Test Volume (ac-ft)

L-8 Reservoir 8,163

Control 2 13,640

Control 4 5,238

G-161 3,005

G-160 3,566

G-92 4,168

Lainhart Dam 3,923

Flows Delivered to Grassy Waters Preserve and the Northwest Fork

The Grassy Waters Preserve is downstream of the City of West Palm Beach Control 2 pump station and upstream of the G-161 structure and the Control 4 structure (Figures 1 and 4). The preserve is the headwaters for the Loxahatchee River. G-161 controls northward discharges from the preserve into a constructed flow path that ultimately discharges under the Beeline Highway (State Road 710) to the C-18 Canal. The gates at G-161 were opened gradually during the first week of the pilot test to minimize suspension of sediments. Downstream of G-161, flows are constrained by a set of flashboards at the Beeline Highway culvert. The flashboards prevent over-drainage of the marsh and help improve water deliveries north of G-161 between Northlake Boulevard and the Beeline Highway. During the test, the flashboards were lowered to 15.5 ft NGVD29. At the end of the test, they were returned to 17.0 ft NGVD29. The G-160 structure is located downstream of G-161 on the C-18 Canal (Figure 1). The C-18 Canal eventually discharges to tide through the S-46 water control structure, but prior to discharging through S-46, flows are directed through the G-92 structure (Figure 1) as much as possible for flow augmentation to the Northwest Fork. Error! Not a valid bookmark self-reference. shows volumes of water discharged at key structures and pumps associated with the L-8 Reservoir Pilot Test. Figure 5 shows flows at G-161, G-160, G-92 and Lainhart Dam. Appendix E contains the data for Figure 5.

Stages Along the Conveyance Route

Figure 6 shows stages during the test period at the G-161, G-160, and G-92 structures, and the Lainhart Dam. Stages in the L-8 Reservoir are depicted in Figure 2. The G-161 headwater is a good indicator of stages in Grassy Waters Preserve. Appendix E contains the data for Figure 6.

Flow Differences Between Reaches of the Conveyance Route

The City of West Palm Beach public water supply is delivered by the M-Canal, which traverses Grassy Waters Preserve in an east–west direction. The M-Canal originates immediately upstream of the Control 2 pump station (Figures 1 and 4). Downstream of the Control 2 pump station, the M-Canal passes through the Control 3 four-culvert gated structure (Control 3 structure), and continues east through Grassy Waters Preserve and finally splits in three directions; south, north and east, which are represented in Figure 4 by Sections 2, 3 and 4, respectively.


12 | Pilot Testing

Figure 4. Schematic of M-Canal indicating the four sections and highlighting the five reaches where stage and flow measurements were taken as part of the pilot test.

Note: The Water Catchment Area is the Grassy Waters Preserve.


13 | Pilot Testing

Figure 5. Flow at G-161, G-160, G-92 and Lainhart Dam during the pilot test.

Figure 6. Stage at G-161, G-160, G-92 and Lainhart Dam during the pilot test.

The Section 2 looped canal has very little connectivity with the M-Canal and was not expected to have substantial flow. Section 3, the north section, flows into the G-161 culvert. Section 4, the east section, flows through a variable crest weir at the Control 4 structure and further downstream to Section 5 where it intersects Village Boulevard.


14 | Pilot Testing

For ease of analysis and data collection, five reaches of the M-Canal were designated. Reach 1 was located between the Control 2 pump station and the Control 3 structure. Reach 2 was between the Control 3 structure and the four-point section. Reach 3 was between the four-point section and G-161. Reach 4 was between the four-point section and the Control 4 structure. Reach 5 was between the Control 4 structure and Section 5 (Figure 4). Flow measurements were taken at the upstream and downstream locations of all five reaches. These data were compiled and analyzed to provide a characterization of the reach-wise differences in discharge in the M-Canal. Losses were estimated between the Control 2 pump station and the G-161 structure when the Control 4 structure was closed, and between the Control 2 pump station and Section 5 with the Control 4 structure open.

Table 2 summarizes the overall results from the stream gauging measurements, including the measurement dates, upstream and downstream mean flows, and difference in discharge values. See Appendix C of this report for the location of these measurements.

Table 2. Mean flow by reach and discharge differences between upstream and downstream sections of the M-Canal flow path.

Reach Measurement Date Station Mean Flow

(cfs)

Upstream to Downstream Flow Difference (cfs)

1

March 7, 2011 Control 2 (Upstream) 109.72

24.45 Control 3 (Downstream) 85.27





2


30.19 Section 1 (Downstream) 53.04

March 17, 2011 Control 3 (Upstream) 129.36 73.32

(CWPB4 closed) Section 1 (Downstream) 56.04


52.45 Section 1 (Downstream) 79.05

3 March 17, 2011 Section 3 (Upstream) 29.95

0.56 G-161 (Downstream) 29.39

4 March 08, 2011 Control 4 (Upstream) 63.67

-0.34 Control 4 (Downstream) 63.99

5 March 8, 2011 Control 4(Upstream) 68.66

-8.44 Section 5 (Downstream) 60.22

Few conclusions could be drawn from the results of the reach-wise flow measurements. The maximum loss/difference in flow occurred in Reach 2 between the Control 3 structure and Section 1. As for Reach 1, it is not clear if steady-state flow was achieved at the time the measurements were taken because the flow varied from 30 to 70 cfs depending on the day of the measurement. A negative upstream to downstream flow difference was observed in


15 | Pilot Testing

Reach 5, and negligible flow differences were observed in Reaches 3 and 4. A more detailed analysis of the stage time series at the Control 2 pump station, G-161 and the Control 4 structure, and/or groundwater levels could help to explain the differences in flow among the reaches.

Comparative time series plots of discharges at the upstream and downstream locations of all five reaches are presented in Appendix C. A test measurement was also conducted at the four-point section on March 17, 2011 to determine if any flow was moving toward either Section 2 (south) or Section 4 (east). Ideally, very little or negligible flow was expected in these two sections, since Section 2 is a closed recirculating channel and the Control 4 structure on Section 4 was also closed on that day. The flow moving toward the east from Section 1 matched the sum of the discharges in the three other sections (Sections 2, 3 and 4) thus verifying no loss in discharge at the intersection. It was interesting to note that some flow was observed in the closed branches (Sections 2 and 4) where no flow was expected. Details of the test measurements are presented in Appendix C.

Discharge differences observed between the upstream and downstream stations of each reach can be attributed to a combination of factors such as unsteady flow conditions, storage in Grassy Waters Preserve, recharge of ground water, and evapotranspiration. Four District and two United States Geological Survey (USGS) groundwater monitoring wells (Figure 7) could be monitored in the future to provide additional data and information for the evaluation of the potential influence of surrounding groundwater elevations on discharges. The data could also be used to evaluate seepages from the M-Canal and Grassy Waters Preserve. Time series data for the wells shown in Figure 7 can be obtained from the District’s DBHYDRO database (DBkeys W4196, W4190, WF812, TB042, LP681, and 02692).

The Control 3 structure is at an important location between the Control 2 pump station and the entrance of Grassy Waters Preserve. Currently no stage recorders are located at this structure. Temporary staff gauges were used during the test measurements to check if stages were steady. Because the Control 3 structure, which is a gated structure, is an important indicator of how much water is leaving Reach 1 and being delivered into Grassy Waters Preserve, it is recommended that stage recorders be installed upstream and downstream of the Control 3 structure to get accurate values of stages and gate operations to provide continuous estimates of flow.


16 | Pilot Testing

Figure 7. Groundwater wells in the area around M-Canal with

recommended wells highlighted with red circles.

G-92 and Lainhart Dam Stream Gauge Results

On March 14, 2011, District staff collected flow measurements at the G-92 structure and Lainhart Dam (Figure 1 and Error! Reference source not found.). Flows computed from stage readings were also obtained from the G-92 structure, and two other Lainhart Dam stations; the District’s real-time monitoring station LNHRT and the USGS flow monitoring station 02277600. Comparisons were made between measured flows and computed flows from these locations.

Table 3. Measured and computed flows at the G-92 structure and Lainhart Dam on March 14, 2011.

Location Measured Flow (cfs) Computed Flow (cfs)

G-92 40 41.46

Lainhart Dam 42.7

USGS 02277600 @ Lainhart Dam 41

LNHRT @ Lainhart Dam 23.84

At G-92, measured flow (40 cfs) varied by < 2 cfs from computed flow (41.46 cfs). Measured flow at Lainhart Dam (42.7 cfs) varied by < 2 cfs from computed flow at USGS 02277600 (41 cfs). However, measured flow at Lainhart Dam varied by almost 19 cfs from computed flow at LNHRT (23.84 cfs), and this large difference is likely due to an inaccuracy in the computation of flow at LNHRT. Flows at LNHRT are based on a flow-rating curve, which due to excessive cost, has not been recalibrated for structural and elevational changes to the Lainhart Dam weir structure that have occurred over time. The weir is constructed of wooden logs and has been subject to many years of recreational use, which has contributed


17 | Pilot Testing

to its degradation and perimeter leakage. Flow estimates at USGS 02277600 on the other hand are based on a stage–discharge relationship with a shifting control. This approach accounts for changes in the physical features of the weir, and requires continuous stream gauging to track the shifting of the rating.

As for G-92 versus Lainhart Dam flows, measured flow at G-92 (40 cfs) varied by 2.7 cfs from measured flow at Lainhart Dam (42.7 cfs), and computed flow at G-92 (41.46 cfs) varied by only 0.46 cfs from computer flow at USGS 02277600 at Lainhart Dam.

Minimum flow and level (MFL) criteria for the Northwest Fork of the Loxahatchee River are based on flow measurements at Lainhart Dam. Therefore, the most reliable source of Lainhart Dam flow data should be used in assessing the status (exceedances and violations) of the MFL. At the present time, that source is the USGS 02277600 station. While USGS 02277600 flow data are more accurate than data from LNHRT, the USGS data are not useful for real-time monitoring and operations because of a two-month lag in data availability. Currently, the G-92 station offers the best available real-time data for predicting possible Northwest Fork MFL exceedances. An estimated G-92 flow above 40 cfs correlates conservatively to a Lainhart Dam flow above 35 cfs.

M-Canal and Grassy Waters Preserve Water Budget

Two water budgets, one for the M-Canal and one for Grassy Waters Preserve, were developed for the pilot test period to give District and City of West Palm Beach staff and other stakeholders a better understanding of water inputs and losses within the M-Canal and Grassy Waters Preserve. In addition, the water budgets provide an understanding of how the Grassy Waters Preserve responds to water deliveries during extremely dry periods.

The Conceptual Model and Assumptions

The conceptual model of the water budget for the M-Canal and Grassy Waters Preserve is illustrated in Figure 8. In the model, L-8 Reservoir water was pumped into the L-8 Canal, through the Control 2 pump station, then discharged through the M-Canal for a distance of 9.4 miles before entering into the Grassy Waters Preserve through the Control 3 structure. Control 2 pump station discharges were the only inflows to the M-Canal taken into account. In addition to seepage loss from M-Canal and Control 3 structure flows, the only other outflow term considered for the M-Canal was a permitted withdrawal by Callery-Judge Grove. Some water may have been lost via a 48-inch culvert located downstream of the Control 2 pump station. This loss could not be quantified without knowing the hydraulic gradient through the culvert, so it was included in the seepage (and error) term. Note that Control 3 structure flow served as an outflow term for the M-Canal water budget and an inflow term for the Grassy Waters Preserve water budget. The Grassy Waters Preserve received water from the Control 3 structure and rainfall. Major outflows of the preserve included (1) releases to Lake Mangonia and Clear Lake through the Control 4 structure, (2) releases via G-161 to the C-18 Canal, and ultimately to the Northwest Fork; (3) evapotranspiration, and (4) seepage.


18 | Pilot Testing

Figure 8. Conceptual model of the water budget for M-Canal and Grassy Waters Preserve.

Assumptions associated with the model were (1) rainfall and evapotranspiration were negligible in the M-Canal water budget considering its small surface area and storage, (2) other losses along the M-Canal were lumped into the seepage (and error) term, and (3) inflows from the existing residential developments surrounding Grassy Waters Preserve were negligible during the dry season. Water budget model formulation and calibration are discussed in detail in Appendix G. Data used in the water budget are presented in Appendix D.

Water Budget Results

The pilot test water budgets for the M-Canal and Grassy Waters Preserve are summarized in Error! Reference source not found. and Figure 9. The total amount of water pumped at the Control 2 pump station during the pilot test was 13,640 ac-ft, of which 89 percent (12,074 ac-ft) entered into Grassy Waters Preserve through the Control 3 structure. Ten percent (1,403 ac-ft) was lost in seepage. Callery-Judge Grove withdrew only 163 ac-ft of water. During the pilot test, water entering Grassy Waters Preserve totaled 14,448 ac-ft, including 2,374 ac-ft from direct rainfall. G-161 discharged 3,005 ac-ft of water (15 percent of total outflows) to the C-18 Canal. The Control 4 structure discharged 5,238 ac-ft of water (25 percent) to Lake Mangonia and Clear Lake. Uncontrolled outflows including ET and seepage accounted for the largest loss, 12,393 ac-ft in total (60 percent). Total outflows exceeded total inflows by 6,188 ac-ft, resulting in a stage reduction of 0.7 feet observed at G-161. Based on measured stage, the calculated storage change using Equation G-2 (below and in Appendix G) was 6,689 ac-ft, giving 501 ac-ft error to close the water budget.

∆t [(ICS3 + R) – (ET + OG-161 + OCS4 + SGWP)] = ∆V where,

∆t = time step (day) ICS3 = inflow at Control 3 (ac-ft/d) R = rainfall (ac-ft/d) ET = evapotranspiration (ac-ft/d) OG-161 = outflow at G-161 (ac-ft/d) OCS4 = outflow at Control 4 (ac-ft/d) SGWP = seepage of Grassy Waters Preserve (ac-ft/d) ∆V = change of water volume stored in Grassy Waters Preserve (acre-feet [ac-ft])


19 | Pilot Testing

Table 4. M-Canal and Grassy Waters Preserve water budgets during the L-8 Pilot Test from March 1 through April 19, 2011.

Volume (ac-ft) Percentage of Inflow/Outflow

M-Canal Water Budget Control 2 pumpage 13,640 100%

Total M-Canal inflows 13,640 100%

Callery-Judge Grove withdrawals -163 -1%

Seepage -1,403 -10% Control 3 outflow -12,074 -89%

Total M-Canal outflows -13,640 -100%

Grassy Waters Preserve Water Budget Control 3 inflow 12,074 84% Rainfall 2,374 16%

Total Grassy Waters Preserve inflows 14,448 100%

Evapotranspiration -8,146 -39% Seepage -4,247 -21% G-161 outflow -3,005 -15%

Control 4 outflow -5,238 -25% Total Grassy Waters Preserve outflows -20,636 -100%

Change in Grassy Waters Preserve storage based on water budget -6,188

Change in Grassy Waters Preserve storage based on Equation G-2 -6,688

Water budget error/unaccounted volume (2.4% of total outflows) 501

Note: Shaded areas in table indicate negative numbers, or outflows.

Figure 9. Water budget of M-Canal and Grassy Waters Preserve (ac-ft) during the pilot test.


20 | Pilot Testing



21 | Water Quality Monitoring

5 Water Quality Monitoring

Water quality monitoring was conducted from February 25, 2011 through May 06, 2011 (before, during and after the pilot test) to comply with FDEP permit exemption requirements. Water samples were taken for total phosphorus analysis and multi-parametric meters were used to measure specific conductance levels. A second order polynomial regression equation, developed by the District and FDEP, was used to estimate chloride concentrations from continuous specific conductance data measured in the field.

Water quality monitoring was conducted at 11 sites (Figure 10 and Appendix A) during the above period, and also at the Control 4 structure beginning on April 25, 2011, a week after the pilot test ended. Even though pilot test pumping began on March 1, 2011 and ended on April 19, 2011, water quality monitoring was continued for 17 days after the test period to capture potential residual effects of the test and to determine the time it takes for the system to return to background levels.

Multi-parametric sondes were deployed at all stations to collect specific conductance data. The sondes were maintained on a weekly time interval with data retrieval, calibration and cleaning done prior to redeployment. All sondes had a recording frequency of 60 minutes with the exception of the permanently deployed sondes at stations SW06OUT, L8MZBN and L8MZBS, which collected data every 15 minutes. Grab samples for total phosphorus were collected weekly at all stations. All monitoring was conducted in accordance with quality assurance/quality control protocols in the FDEP Quality Assurance rule, Chapter 62-160, FAC, and the District’s Field Sampling Quality Manual (SFWMD 2011). Details of the monitoring effort, sample results and calculated chloride values are provided in Appendix A.

CHLORIDES The chloride ion contributes to salinity, which is a measure of the total ionic composition of water defined by four major cations (Ca++, Mg++, Na++, and K+) and four major anions (HCO3-, CO3=, SO4=, and Cl-). Specific conductance refers to how well a solution can conduct an electrical current. Conductivity increases with increasing amount and mobility of cations and anions, so higher salinity waters have a greater conductance of electrical flow. Therefore, specific conductance is an indirect measure of the presence of dissolved solids and of salinity, and correlates well with chloride concentration. Specific conductance can be quickly determined in the field as compared to measuring chloride concentration, which requires lab work.



Figure 10. Water quality sampling stations monitored as part of the pilot test.



Cost-effective and timely monitoring is achieved by estimating chloride concentrations from specific conductance data using the following regression equation: Predicted Chloride (mg/L) = 0.0000455 * (Specific Conductance)2 + 0.0845 * (Specific Conductance) + 6.634 The QUAD2 regression equation is limited to freshwater systems (i.e., lakes, reservoirs, canals, streams, marshes) with specific conductance levels at or below 3,000 µS/cm. The regression equation may be used to predict chloride levels beyond the 3,000 μS/cm; however, it is important to note the predicted value would be a rough conservative estimate and should be used as such. Detailed discussion of the QUAD2 regression equation is provided in Appendix B. Calculated chloride values are shown in Figures 11 and 12 and in Appendix A.

Figure 11. Calculated chloride concentrations in the L-8 Reservoir (L8RES), L-8 Canal mixing zone (L8MZBN, L8MZBS), Control 2 pump station (L8MCNL), and L-8 Canal north of the L-8 Canal Tieback

Levee (L8-04.3) for the period February 25, 2011 through May 6, 2011.



Figure 12. Calculated chloride concentrations in Grassy Waters Preserve station GW3,

GW4, GW7, GW8, G-161 for the period February 25, 2011 through May 6, 2011.

Prior to the pilot test, chloride concentrations in the L-8 Reservoir, measured at monitoring station L8RES, averaged 284 mg/L. During the test, chloride levels within the reservoir averaged 354 mg/L, peaking at 373 mg/L on April 14, 2011. Inflows from Lake Okeechobee via Culvert C-10A proved important in reducing elevated chloride concentrations in the L-8 Canal downstream of the L-8 Reservoir and in Grassy Waters Preserve. For example, chloride concentrations recorded at the L804.3 station (located north of the L-8 Tieback Canal) during the first four weeks of the test averaged 70 mg/L. The gradual increase in chloride concentrations at this station near the end of test (Figure 11) most likely can be attributed to reduced inflows from Lake Okeechobee via Culvert C-10A to the L-8 Canal at that time, as well as increased withdrawals from permitted users located within the L-8 Basin north of the L-8 Tieback Canal. Chloride values recorded at the Control 2 pump station (L8.MCNL) also illustrate the dilution effect that inflows from Lake Okeechobee via Culvert C10A have on elevated chloride concentrations measured within the L-8 Canal mixing zone (L8MZBN and L8MZBS) (Figure 11). Specifically, chloride concentrations were observed to fluctuate widely at the Control 2 pump station over the course of the pilot test largely in response to either pump operations or rainfall events. Chloride concentrations calculated for the Control 2 pump station ranged from 73 to 327 mg/L, averaging 228 mg/L over the course of the pilot test. These values are 2.7 times higher than inflow water from Lake Okeechobee via Culvert C-10A and 60 percent less than what was pumped from the L-8 Reservoir.

Of the five water quality stations sampled within Grassy Waters Preserve, the GW4 site was most affected by water pumped through the Control 2 pump station, as this station is located on the M-Canal directly downstream of the Control 2 pump station (the so-called “end-of-the-pipe” location). Prior to the test, chloride concentrations at GW4 averaged 69 mg/L. These values increased three fold during the test, averaging 220 mg/L and ranging between 80 and 323 mg/L (Figure 12).



Chloride concentrations at GW4 and the Control 2 pump station were highly correlated (R= 0.97) as shown in Figure 13. Using this information, as well as the mean flow rate at the Control 2 pump station during the 50 day test period (109 cfs), and the length of the M-Canal (9.4 miles), it was determined that there was a two-day lag in water moving from the Control 2 pump station to GW4. Chloride concentrations peaked at GW4 on April 22, 2011, reaching 372 mg/L roughly two days after pumping from the L-8 Reservoir was terminated (Figure 12). As shown in Figure 12, between April 16 and April 18, 2011, chloride concentrations observed after the test were reduced temporarily by a rainfall event. Previous to this rain-induced decline, chloride concentrations at GW4 steadily increased to levels nearly equivalent to those discharged from the L-8 Reservoir. Though the rainfall

Figure 13. Chloride lag time response between station GW4 and the Control 2

pump station before, during, and after the pilot test.

Note: Lag time response is about two days (R=0.97).

event may have temporarily reduced chloride concentrations at GW4, these inputs were not large enough to overcome the rising chloride trend. The elevated chloride concentrations observed at GW4 after completion of the test were largely the result of the two-day lag time in water moving downstream 9.4 miles, from the Control 2 pump station to GW4 (Figures 12 and 13). Appendix A contains the data for Figures 12 and 13.

In contrast, the GW3 station is located in a small slough immediately north of the M-Canal. Chloride concentrations at this station averaged 71 mg/L prior to the test and steadily increased during the test, reaching 247 mg/L on April 19, the last day of the test. Unlike GW4, this station did not display a response that could be attributed to the Control 2 pumping schedule. Instead, chloride concentrations at this station gradually increased beginning about one week after the pilot test was initiated. Chloride concentrations at GW3 continued to increase at a steady rate beyond the conclusion of the test, reaching a maximum daily mean of 271 mg/L on May 4, 2011 (Figure 12).

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The GW8 station is located within the interior of Grassy Waters Preserve and is thought to represent water quality conditions characteristic of a rainfall-driven system. Background chloride concentrations at GW8 averaged 59 mg/L prior to the test. The maximum chloride concentration observed at GW8 was 151 mg/L on April 15, 2011. Conditions at GW8 were much slower to respond than those at either GW4 or GW3 with no observed increase in chloride concentration occurring until about 10 days prior to termination of the test (Figure 12).

The lowest chloride concentrations observed in Grassy Waters Preserve during the pilot test occurred at GW7 and G-161. Prior to the test, chloride concentrations averaged 36 and 26 mg/L at GW7 and G-161, respectively. These values increased very gradually until near the end of the test period (Figure 12). The highest chloride concentrations recorded at these locations occurred after completion of the pilot test, when measured concentrations were 116 mg/L at GW7 on April 20, 2011, and 201 mg/L at G-161 on April 21, 2011.

From an operations standpoint, closure of the Control 4 structure on April 16, 2011 played an important role in increasing chloride concentrations at GW7 and G-161 during the test. Flow measurements conducted on April 17 confirmed that more than half of the M-Canal inflow water delivered to Grassy Waters Preserve was diverted north, either through the marsh or along the eastern perimeter canal, when the Control 4 structure was closed. As a result of this closure, some water with elevated chloride concentrations made its way to GW7 and G-161 (Figure 12), as flows routed through Grassy Waters Preserve’s eastern perimeter canal or as sheet flow through the interior of Grassy Waters Preserve. Reopening the Control 4 structure on April 19, coupled with the closure of G-161 on April 22, resulted in the redirection of water with elevated chloride from GW7 and G-161 to the eastern perimeter canal and to the Control 4 structure.

The permit exemption issued for the pilot test specified that if chloride concentrations at the Lake Mangonia/Clear Lake station (LM1) exceeded 250 mg/L, the pilot test would have to be terminated. The purpose of this requirement was to ensure protection of the City of West Palm Beach public water supply. Results presented in Figure 14 show that chloride concentrations at the LM1 station never exceeded 135 mg/L, well below the 250 mg/L limit. The highest measured chloride concentration of 134 mg/L at the LM1 site occurred 16 days after the pilot test was completed (Figure 14).

Previous chloride data collected in the field showed that there were high residual chlorides along the eastern perimeter of Grassy Waters Preserve. An additional water quality sampling station was added to the study after the pilot test was completed to assess the residual effects of the pilot test at the Control 4 structure located downstream of Grassy Waters Preserve. This assessment was important for understanding the fate of chlorides within the regional system. The Control 4 structure is located about 3.9 miles upstream of the LM1 station. Figure 14 provides the chloride monitoring results from this station. Appendix A contains the data for Figure 14.



Figure 14. Calculated chloride concentrations at the Control 4 structure and the Lake Mangonia/Clear

Lake monitoring site (LM 1) for the period February 25, 2011 through May 6, 2011.

CHLORIDES AT THE NORTHWEST FORK OF THE LOXAHATCHEE RIVER The objective of the preferred restoration flow scenario proposed by the Loxahatchee River Watershed Restoration Project was to keep salinity in the freshwater portion of the Northwest Fork below 2 parts per thousand (ppt). The preferred restoration flow scenario was partly based on the salinity tolerance of bald cypress trees (Taxodium distichum) and other freshwater vegetation (SFWMD 2006). Figure 15 shows that fresh water from the L-8 Reservoir during the pilot test helped keep the salinity in the Northwest Fork in the preferred range during extremely dry periods. It also shows that the flows delivered were adequate to meet the MFL flow criterion of 35 cfs at the Lainhart Dam.

0

50

100

150

200

250

300

350

400

450

Cal

cula

ted

Ch

lori

de

(m

g/L

)

CS4

LM1

Start End

250 mg/L (Class I criterion)



Figure 15. Salinity in the Northwest Fork of the Loxahatchee

River before, during and after the pilot test.

TOTAL PHOSPHORUS Total phosphorus (TP) data collected during the pilot test were consistent with results reported by the District for the past several years for the L-8 Reservoir and surrounding canals. As shown in Figure 16, TP concentrations within the L-8 Reservoir were low, compared to the other observed stations, with concentrations ranging from 14 to 29 micrograms per liter (μg/L) and a mean concentration of 18 μg/L. The routine mixing zone stations (L8MZBN and L8MZBS in Figure 10) located 800 meters north and south of the L-8 Reservoir discharge point also showed the dilution effect the L-8 Reservoir has on TP levels within the L-8 Canal (Figure 16). Appendix A contains the data for Figure 16.



Figure 16. TP concentrations in the L-8 Reservoir (L8RES), L-8 Canal mixing zone

(L8MZBN, L8MZBS), Control 2 pump station (L8MCNL), and the L-8 Canal north of the L-8 Canal Tieback Levee (L8-04.3) before, during and after the pilot test.

High TP concentrations have been documented in Lake Okeechobee (FDEP 2001, SFWMD 2002, SFWMD et al. 2011). The mean of the measured TP concentrations at the L8-04.3 station (95 μg/L), which is located north of the L-8 Tieback Canal, was the highest of all stations sampled during the pilot test, and this is reflective of the inflows into this canal from Lake Okeechobee via Culvert C10A.

Prior to the initiation of the pilot test, TP concentrations at the Control 2 pump station (L8MCNL) were typical of Lake Okeechobee waters (mean = 98 μg/L) and the water pumped through this structure originates from the L-8 Canal. However, during the pilot test, TP concentrations at the Control 2 pump station showed a marked reduction, ranging between 54 and 82 μg/L, with a mean of 61 μg/L over the 50-day test period (Figure 16). This further supports the dilution effect of L-8 Reservoir water on L-8 Canal water.

The TP results from Grassy Waters Preserve interior marsh water quality monitoring stations GW3, GW7, GW8 and G-161 (Figure 10) were much lower than those recorded within the L-8 Canal or at the Control 2 pump station, with the lowest mean TP concentration of 6 μg/L recorded at GW7 and GW8 (Figure 17 and Appendix A). The dilution effect that L-8 Reservoir water had on Grassy Waters Preserve was most noticeable at GW4.

0

50

100

150

Tota

l Pho

spho

rus

(µg/

L)

L8MZBS L8RES L8MZBN L8-04.3 L8.MCNL

Start End



Figure 17. Total phosphorus concentrations in Grassy Waters Preserve at stations GW3, GW4, GW7,

GW8, G-161 and Lake Mangonia/Clear Lake (LM 1) before, during and after the pilot test.

0

50

100

150GW4 GW3 GW8 GW7 G161 LM1

Start EndTo

tal P

hosp

horu

s (μg/

L/)


31 | Post-Project Monitoring

6 Post-project Monitoring

SPECIFIC CONDUCTANCE MEASUREMENTS On May 25, 2011 District staff performed specific conductance measurements at 33 sites located in the L-8 Canal, M-Canal, Grassy Waters Preserve and the southern extent of Lake Mangonia. This monitoring effort was conducted for 36 days following termination of the L-8 Reservoir Pilot Test for the purpose of obtaining additional information on the fate and location of chlorides in the system one month following termination of the test. Chloride concentration were calculated using the same regression equation noted in Chapter 5.

L-8 CANAL AND M-CANAL Calculated chloride levels in the L-8 Canal and M-Canal had returned to pre-pilot test levels, with concentrations ranging from 82 to 97 mg/L as shown in Figure 18. These concentrations are similar to those observed in the L-8 Canal and M-Canal prior to the pilot test and appear representative of chloride concentrations derived from Lake Okeechobee inflow via Culvert C10A.

GRASSY WATERS PRESERVE Specific conductance readings were collected from 19 stations in Grassy Waters Preserve. At the time of collection, stages in Grassy Waters Preserve were less than 17.0 ft NGVD29 as compared to stages observed at the end of the pilot test (18.04 ft NGVD29 on April 19, 2011). In general, the “floor” of Grassy Waters Preserve is set at about 17.5 ft NGVD29 (Patrick Painter, City of West Palm Beach, personal communication). During the May 25, 2011 monitoring effort, some areas of Grassy Waters Preserve were dry while other areas contained shallow pools of water. Chloride levels in the M-Canal, which traverses Grassy Waters Preserve, had declined to pre-pilot test levels, with concentrations ranging from 93 to 62 mg/L from west to east as shown in Figure 18. Again, these values appear representative of chloride concentrations derived from Lake Okeechobee inflow via Culvert C10A. However, some isolated pools in Grassy Waters Preserve had elevated chloride concentrations. At the GW3 and GW8 stations for instance, calculated chloride concentrations were 249 and 171 mg/L, respectively, which is two to three times higher than pre-pilot test chloride concentrations. Chloride concentrations were also elevated in the southeast section of Grassy Waters Preserve. These circumstance might be (1) indicative of water with elevated chloride that entered the interior marsh during the pilot test via large gaps or cuts that lead north from the M-Canal into the interior marsh; and/or (2) the result of declining stages and increased evapotranspiration at these interior marsh sites.



Figure 18. Calculated chloride concentrations (mg/L) in the L-8 Reservoir, L-8 Canal, M-Canal,

Grassy Waters Preserve and southern extent of Lake Mangonia on May 25, 2011.

M-Canal

WPB Control 2 Pump Station

GW 4GW 3

GW7

GW 8

G-161

LM 1

L-8

Rese

rvoi

r

Lake Mangonia

Clear Lake

Provisional Data

Legend:= Established Water quality station as per Exemption= Sample collected on 5/25/11, values in white = chloride

concentration (mg/L)

Northlake Blvd.

Southern Blvd.

Note: Class I Water Quality Standards (for drinking water), chloride levels shall not exceed 250 mg/L at the LM1 station

69

17197

6678

58

249 29

52

4040

93

8989

62

108

57

207

6465

939393

96

82

9586

86

7481

132386

79



The May 25, 2011 calculated chloride concentrations appear indicative that at least some of the water pumped into Grassy Waters Preserve during the pilot test moved across the marsh in a northeast direction rather than flowing eastward through the M-Canal and then northward via the eastern perimeter canal as previously predicted (Figure 18). This is also supported by chloride concentrations at the GW7 station located on the eastern perimeter of Grassy Waters Preserve versus concentrations at the G-161 structure on the eastern perimeter canal to the north. These results suggest flows containing elevated chloride concentrations made their way to G-161 as sheet flow across the marsh rather than by the eastern perimeter canal route.

Based on previous studies, these results should not have been entirely unexpected. Previous water quality modeling conducted for Grassy Waters Preserve as part of the Loxahatchee River Watershed Restoration Project demonstrated a preferred flow path toward the interior marsh through existing gaps or cuts in the M-Canal bank (CH2M HILL 2008). Model results indicated that closing these cuts or gaps would encourage a more direct route through the eastern perimeter canal toward the G-161 structure. Results from the pilot study suggest that for future testing, and for the larger Loxahatchee River Watershed Restoration Project, consideration should be given to closing off the larger gaps or cuts along the M-Canal with earthen berms or some other structural feature, which will help limit canal inflows that have elevated chloride concentrations to the Grassy Waters Preserve interior marsh. Results from this pilot test also indicate the need for a synoptic approach for the collection of specific conductance data for the purpose of calculated chloride concentrations within Grassy Waters Preserve before, during and after future conveyance tests or deliveries to provide enough data points to draw an accurate chloride distribution map using commonly available computer programs.

LAKE MANGONIA/CLEAR LAKE Under the terms of the FDEP permit exemption, pilot test operations were to be terminated if chloride concentrations at the Lake Mangonia/Clear Lake LM1 station exceeded 250 mg/L. At the beginning of the pilot test on March 1, 2011, mean daily calculated chloride concentration at LM1 was 59 mg/L (Figure 19). Three weeks into the test on March 21, 2011, the chloride concentration had increased to about 77 mg/L. By the end of the test on April 19, 2011, the chloride concentration at the LM1 station was 122 mg/L. These values continued to increase gradually reaching a maximum concentration of 134 mg/L on May 5, 2011, sixteen days after the pilot test terminated. After this date, chloride concentrations at LM1 continued to range between 130 and 133 mg/L until the last day of sampling on June 1, 2011, a period of 43 days after the pilot test terminated, when chloride concentration was 132 mg/L (Figure 19). These results show that during, and more than one month following the pilot test, chloride concentrations at the LM1 station never exceeded 135 mg/L, well below the 250 mg/L limit.



Figure 19. Calculated mean daily chloride concentrations at the Lake Mangonia/Clear

Lake station (LM1), observed before, during and after the pilot test.

0

50

100

150

200

250

300

Start of Test (3/01/11) End of Test (4/19/11)

LM1 Station

Mea

n D

aily

Cal

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ted

Chl

orid

e C

once

ntra

tion

(mg/

L)

Class I Water Quality Standard (250 mg/L)


35 | Project Implementation and Costs

7 Project Implementation and Costs

The L-8 Reservoir Pilot Test provided a means to “exercise” the L-8 Reservoir by pumping out water and then refilling the reservoir with fresh surface water derived from the L-8 Basin. Implementation of the project also afforded an opportunity to implement collection of specific data to increase the understanding of the water delivery system. This additional data collection included (1) flow measurements taken at different reaches along the conveyance route and (2) stage measurements at each control structure and within Grassy Waters Preserve. The maintenance and repair activities associated with the existing pump station on the L-8 Reservoir were not anticipated. Additional staff time was spent manually turning the L-8 Reservoir pump on an off during the project since the pump is not remotely controlled. Originally, the pilot test project was to be implemented over a 30-day period. However, it was extended an additional 30 days to continue project deliveries. Calculated chloride concentrations during the project never reached levels that were unacceptable for irrigation of crops or public water supplies. Staff time was used to collect and summarize field data, including measurements with multiparametric meters and grab sampling. The multiparametric meters provided additional data between water quality monitoring stations required as part of the permit exemption. The costs associated with water quality monitoring and laboratory analysis were estimated to be approximately $30,000. Weekly meetings were held with internal District staff and external parties (City of West Palm Beach, Seminole Improvement District, Cypress Grove Community District, Callery Judge Grove, and others) to communicate information collected through monitoring efforts. The weekly meetings were also important in coordinating when stage and flow measurements were taken in the various reaches along the conveyance route. Coordination with each entity along the conveyance route was critical to ensure surface water was not being used to meet irrigation demands (e.g. all structures outside of the M-Canal were closed) when measurements were being taken.

A total of 32 District staff assisted with pilot test project implementation. Six District staff assisted from the Office of Everglades Policy and Coordination for project management, permit authorization and coordination with internal staff and external stakeholders. Seven District staff from the Water Quality Bureau assisted with water quality data collection and analysis, and 19 staff from the Operations, Maintenance and Construction Division assisted with stage and flow measurements, and operation and maintenance of the District owned control structures. The City of West Palm Beach also contributed significant staff time for operation of their Control 2 pump station and Control 4 structure, and water quality collection and analysis to ensure their public water supply was not adversely affected.


36 | Project Implementation and Costs

Overall, the amount of staff time and effort needed to complete the pilot test and this technical document were much more extensive than originally anticipated.

Rental of two temporary pumps for two weeks was initially contemplated at an estimated cost of approximately $30,000, which included hoses, pipes, removal and fuel costs. Rental of these temporary pumps was dismissed prior to implementation of the project because the City of West Palm Beach had voluntarily reduced their pumping to 12 hours per day for public water supply. Water deliveries for the pilot test occurred during the other 12 hours using the Control 2 pump station.

Fuel costs associated with the existing 75-cfs electric pump on the L-8 Reservoir during the pilot test were $15,648. Additional fuel and electric costs not included in this report were incurred by the City of West Palm Beach for activities at the Control 2 pump station and Control 4 structure.

Overall, the pilot test project was more costly than originally envisioned. This was due, in part, to field measurements, water quality data collection and analysis, and operational activities


37 | Conclusions

8 Conclusions

Analysis of the hydraulic and water quality data gathered during the 50-day pilot test led to the following conclusions: • Water deliveries to the Northwest Fork of the Loxahatchee River via Grassy Waters

Preserve can be accomplished during extremely dry periods using the existing facilities. The period from October 2010 to May 2011 was the driest on record dating back to 1939. A total of 12 inches of average rainfall was recorded for this period. The rainfall deficit exceeded the old record of 13.88 inches set during the 1970–1971 dry season.

• The minimum flow and level criteria (MFL) for the Northwest Fork of the Loxahatchee

River was met for 47 out of the 50 days of the pilot test project.

• A water budget for Grassy Waters Preserve flows during the pilot test showed that evapotranspiration and seepage losses accounted for approximately 60% of the preserve total outflow volume. Water released through the G-161 structure to the Northwest Fork accounted for approximately 15% of the preserve outflows. The remaining preserve outflows (25%) were delivered to the City of West Palm Beach via the M-Canal for water supply.

• Stream gauge measurements revealed that there was a two-day lag in water moving 9.4

miles from the Control 2 pump station to GW4. This time lag was confirmed by examining the relationship between the Control 2 pump station and GW4 calculated chloride concentrations together. The movement of chlorides continued for two days following termination of the pilot test.

• The initial stage in Grassy Waters Preserve (18.69 ft NGVD29) at the start of the pilot test

had a major influence on the delivery of water to the preserve from Lake Okeechobee. Deliveries of water from Lake Okeechobee were critical to the project in order to allow sufficient mixing to comply with the downstream chloride target at Lake Mangonia. Ultimately, this initial stage translated to a longer duration of project implementation.

• Securing authorization to expand the mixing zone from the L-8 Reservoir to Lake Mangonia was critical for project implementation by allowing a longer pumping duration. Without the expanded mixing zone, water quality data indicates that pumping from the L-8 Reservoir would have been limited to eight days of water flowing in a northerly direction from the discharge point of the L-8 Reservoir. Pumping water in a southerly direction from this same discharge point would have been limited to only four days during the pilot test period.


38 | Conclusions

• The primary considerations for making successful water deliveries were (1) managing chloride concentrations in Grassy Waters Preserve and Lake Mangonia; and (2) maintaining stage elevations required to protect wildlife and the ecological conditions in Grassy Waters Preserve while still providing for the City of West Palm Beach’s water supply.

• During the test period, Lake Okeechobee water was mixed and diluted with water

pumped from the L-8 Reservoir (TP concentration of 17 µg/L) along the conveyance route and delivered to Grassy Waters Preserve. The average TP concentration in Lake Okeechobee (station L8-04.3) was 95 µg/L while the mean TP concentrations at stations L8_MCNL, GW4 and GW3 (see Figure 10 in Section 5.0) were 61, 69 and 13 µg/L, respectively, during the test period.

• As stages receded in Grassy Waters Preserve, the higher stages in the M-Canal in the

preserve facilitated seepage and flows into the preserve from the canal. This affected chloride concentrations in the marsh and resulted in a gradient from the M-Canal in a northeasterly direction toward the G-161 structure. This conclusion is based on the higher chloride concentrations observed at G-161 and GW7 following closure of the Control 4 structure on April 16, 2011. It should be noted that G-161 discharged water from Grassy Waters Preserve and the eastern perimeter canal. The proportion that came from each was based on the relative gradient toward G-161.

• Although chloride concentrations varied at different locations during and after the pilot test, the highest chloride concentration of 134 mg/L at the compliance point (LM1) occurred after pumping associated with the pilot test was terminated, well below the compliance target of 250 mg/L in Lake Mangonia. Residual chloride concentrations were observed in Grassy Waters Preserve 36 days following project termination. These circumstance might be (1) indicative of water with elevated chloride that entered the interior marsh during the pilot test via large gaps or cuts that lead north from the M-Canal into the interior marsh; and/or (2) the result of declining stages and increased evapotranspiration at these interior marsh sites.

• Data suggest that closure of the Control 4 structure on April 16, 2011 just prior to project

termination may be the reason for the observed increase in chloride levels in Grassy Waters Preserve, GW7 and the G-161 structure after the pilot test was complete.

• Limitations of the outflow pumps in place during the pilot test made it impossible to

pump water from the L-8 Reservoir when water levels dropped below -2.0 ft NGVD29.


39 | Recommendations

9 Recommendations

The following were the original key recommendations coming from this project. In reading these recommendations, consideration should be given to the fact that while originally developed for providing long-term increased flows to Grassy Waters Preserve and the Northwest Fork, the L-8 Reservoir is now intended to function primarily as a flow equalization basin for delivering controlled flows to the Everglades Stormwater Treatment Areas south of Lake Okeechobee. It will support Loxahatchee River restoration as an interim measure. However, the former Mecca Farms property is now slated to capture excess water in the C-18 Canal to be conveyed through the CERP Loxahatchee River Watershed Restoration Project Flow-way 2 to the Northwest Fork as a long-term recovery strategy to support the minimum flow and level (MFL) for the Northwest Fork established in Rule 40E-8.221(4), Florida Administrative Code (FAC). The refocusing of functions for the L-8 Reservoir to be a flow equalization basin may make some of all of the following recommendations obsolete.

• If this test is repeated, water quality should be monitored at the Control 4 and 6 structures to provide an understanding of the dilution effect caused by Grassy Waters Preserve. Water quality should also be monitored at the Control 6 structure for predicting chloride levels at the Lake Mangonia/Clear Lake LM1 station.

• Larger gaps or cuts that currently exist along the M-Canal should be plugged with

earthen berms or some other structural feature to limit canal inflows into the Grassy Waters Preserve interior. This measure will help limit canal inflows carrying elevated levels of chloride from entering the interior marsh. The feasibility of additional project costs and potential permitting delays should be considered before implementing this measure.

• Flows at Lainhart Dam used to determine MFL compliance for the Northwest Fork

should be measured using USGS flow data since it provides more accurate and reliable data. Coordination with the USGS should occur so real-time data are available for the USGS 02277600 station. In the meantime, G-92 flows are the most reliable real-time indicator of flows at the Northwest Fork.

• Additional flow monitoring data should be collected during average and wet season

conditions to gain a better understanding of the losses and gains in the system under a broad range of operating conditions. This will provide better assumptions for input into the model for design of the L-8 pump facility.

• Six groundwater wells located adjacent to the pilot test study area, including four

District and two USGS monitoring wells (DBKeys W4196, W4190, WF812, TB042,


40 | Recommendations

LP681 and 02692), should be monitored in the future to help determine whether surrounding groundwater elevations affect conveyance seepage losses.

• Stage recorders should be installed upstream and downstream of the Control 3

structure to obtain accurate values of stage, flow, and gate operations in the L-8 Canal and Grassy Waters Preserve.

• Stages in the M-Canal were shown in this study to be important with respect to

chloride transport into Grassy Waters Preserve. Therefore, head stages and gate position data at the Control 4 structure, which are monitored remotely by the City of West Palm Beach, should be shared in real-time with the District’s Operation and Control Center. The Control 4 structure data should be integrated into the District’s control system.

• Operation of the L-8 Reservoir pump station and control structures needs to be

automated and controlled remotely from the District’s Operation and Control Center to provide the operational flexibility needed to meet mixing zone requirements.


41 | References

10 References

CH2M HILL. 2008. North Palm Beach County - Part 1 Protect PIR/EIS Support Services: Water Catchment Area Hydrodynamic and Water Quality Model for Predicting Phosphorus Distribution. Prepared by CH2M HILL for the South Florida Water Management District, West Palm Beach, FL. September 2009.

FDEP. 2001. Total Maximum Daily Load for Total Phosphorus, Lake Okeechobee, Florida. Report submitted by the Florida Department of Environmental Protection, Tallahassee, FL to the United States Environmental Protection Agency, Region IV, Atlanta, GA. August 2001.

SFWMD. 2002. Surface Water Improvement and Management Plan for Lake Okeechobee. South Florida Water Management District, West Palm Beach, FL.

SFWMD. 2006. Restoration Plan for the Northwest Fork of the Loxahatchee River. South Florida Water Management District, West Palm Beach, FL. April 2006.

SFWMD. 2008. Water Delivery from the Regional System to the Northwest Fork of the Loxahatchee River using Flow-way #1. South Florida Water Management District, West Palm Beach, FL. September 2008.

SFWMD. 2011. Field Sampling Quality Manual. South Florida Water Management District, West Palm Beach, FL. SFWMD-FIELD-QM-001-07, effective June 21, 2011.

SFWMD, FDEP and FDACS. 2011. Lake Okeechobee Protection Program Update 2011, Lake Okeechobee Protection Plan Evaluation Report. South Florida Water Management District, West Palm Beach, FL; Florida Department of Environmental Protection, Tallahassee, FL; and Florida Department of Agriculture and Consumer Services, Tallahassee, FL.

USACE and SFWMD. 2005. Comprehensive Everglades Restoration Plan Project Management Plan North Palm Beach County – Part I. South Florida Water Management District, West Palm Beach, FL; and U.S. Army Corp of Engineers, Jacksonville, FL.


42 | References



43 | Appendix A

Appendix A WATER QUALITY MONITORING SITES

This appendix contains additional information on the water quality monitoring conducted during and after the L-8 Reservoir Pilot Test. Table A-1 provides a description of the water quality monitoring sites along Flow-way 1 including global positioning system (GPS) coordinates. These station locations are provided in Figure A-1. Table A-2 provides the sampling parameters collected and frequency of sampling at each station. Total phosphorus (TP) concentration data are presented in Tables A-3 and A-4. Calculated chloride concentrations are presented in Tables A-5 and A-6. Chloride and total phosphorus data are in milligrams per liter (mg/L).

Table A-1. Project surface water quality monitoring sites and GPS coordinates.1

Station Latitude Longitude Description L8RES 26.7276 80.3651 Located at the L-8 Reservoir pump (SW6OUT)

L8MZBN 26.7346 80.3631 L-8 Reservoir mixing zone B north

L8MZBS 26.7204 80.3635 L-8 Reservoir mixing zone B south

L8-0.43 26.7480 80.3689 Located in the L-8 Canal approximately 1,000 meters upstream of the M-Canal tieback

L8.MCNL 26.7553 80.3456 City of West Palm Beach Control 2 pump station located on M-Canal

GW3 26.7646 80.1759 Grassy Waters Preserve interior site

GW4 26.7657 80.1978 City of West Palm Beach Control 3 gated weir located on the M-Canal



Control 42 26.7510 80.1186 City of West Palm Beach Control 4 gated weir located on the M-Canal at Haverhill Road

G-161 26.8101 80.1565 Gated culvert located at Northlake Boulevard

LM1 26.7279 80.0774 Located between Lake Mangonia and Clear Lake approximately 300 meters north of Palm Beach Lakes Boulevard

1The standard positional goal for site coordinates is ± one meter as obtained with a professional grade differential GPS system. The coordinates are relative to North American Datum of 1983 High Accuracy Reference Network horizontal datum and reported in decimal degrees. 2Added on day 56 of the pilot test.


44 | Appendix A

Figure A-1. Water quality sampling stations monitored as part of the pilot test.


45 | Appendix A

Table A-2. Project water quality monitoring sampling parameters and frequencies.

Station Sample Type Frequency Parameters L8RES grab in-situ weekly 15 minutes TP and Specific Conductance

L8MZBN grab in-situ weekly 15 minutes TP and Specific Conductance L8MZBS grab in-situ weekly 15 minutes TP and Specific Conductance L8-0.43 grab in-situ weekly 60 minutes TP and Specific Conductance L8.MCNL grab in-situ weekly 60 minutes TP and Specific Conductance

GW3 grab in-situ weekly 60 minutes TP and Specific Conductance GW4 grab in-situ weekly 60 minutes TP and Specific Conductance GW7 grab in-situ weekly 60 minutes TP and Specific Conductance GW8 grab in-situ weekly 60 minutes TP and Specific Conductance

Control 4 grab in-situ weekly 60 minutes TP and Specific Conductance G-161 grab in-situ weekly 60 minutes TP and Specific Conductance LM1 grab in-situ weekly 60 minutes TP and Specific Conductance

Table A-3. Total phosphorus concentrations at 11 sites located within the L-8 Reservoir, L-8 Canal, M-Canal, Grassy Waters Preserve and Lake Mangonia/Clear Lake.

Date TP

(micrograms per liter) L8RES L8MZBS L8MZBN L8-04.3 L8.MCNL GW4 GW3 GW8 GW7 G-161 LM1

02/25/11 15 120 95 86 98 135 14 6 6 14 20 03/03/11 16 40 26 88 --- 89 12 5 7 --- 20 03/09/11 20 50 43 100 56 59 11 6 4 10 18 03/17/11 17 61 37 80 54 51 13 5 5 12 14 03/25/11 14 32 43 117 82 50 13 6 5 11 15

04/01/11 20 33 108 107 56 88 13 6 6 9 14 04/08/11 20 43 40 92 --- 88 13 6 8 --- 15 04/14/11 15 40 48 96 58 60 18 6 --- 11 15 04/22/11 17 93 107 107 73 63 14 5 8 18 15 04/29/11 29 89 76 72 79 68 18 8 9 16 18

Average 17 43 49 97 61 69 13 6 6 11 16

Minimum 14 32 26 72 54 50 11 5 4 9 14

Maximum 29 120 108 117 98 135 18 8 9 18 20


46 | Appendix A

Table A-4. Total phosphorus concentrations at inflows and outflows of the L-8 Reservoir.

Date

Total Phosphorus (mg/L)

SW6IN - Inflow SW6OUT - Outflow 06/03/08 0.035 0.011 06/11/08 0.021 0.017 07/21/08 0.041 not available 08/26/08 0.306 0.009 09/03/08 0.022 0.008 10/08/08 0.132 0.032 10/17/08 0.028 0.019 10/29/08 0.041 0.017 11/04/08 0.172 0.019 11/13/08 0.196 0.014 11/20/08 0.165 0.016 11/26/08 0.118 0.015 12/02/08 0.082 0.015 12/09/08 0.133 0.011 12/17/08 0.160 0.010 12/22/08 0.152 0.009 12/31/08 0.136 0.007 01/08/09 0.136 0.014 01/14/09 0.147 0.014 01/22/09 0.141 0.014 01/29/09 0.158 0.013 05/20/09 0.104 0.019 05/27/09 0.221 0.080 06/03/09 0.140 0.062 06/17/09 0.142 0.024 07/09/09 0.052 0.019 07/16/09 0.056 0.018 07/23/09 0.083 not available 07/30/09 0.083 0.014 08/10/09 0.072 0.012 08/13/09 0.073 not available 08/24/09 0.067 0.014 08/31/09 0.091 0.015 10/22/09 0.084 0.027 10/30/09 0.111 0.019 11/05/09 0.070 0.042 12/10/09 0.097 0.087 12/18/09 0.085 0.067


47 | Appendix A

Table A-4. continued.

Date

Total Phosphorus (mg/L)

SW6IN - Inflow SW6OUT - Outflow

12/24/09 0.105 0.089 12/31/09 0.094 0.096 01/07/10 0.093 0.093 01/14/10 0.080 0.060 02/22/10 0.037 0.025 03/04/10 0.150 0.043 03/11/10 0.054 0.031 04/02/10 0.046 0.017 04/08/10 0.132 0.019 04/15/10 0.063 0.021 05/06/10 0.149 0.016 05/13/10 0.181 0.018 05/24/10 0.132 0.013 06/03/10 0.091 0.012 06/10/10 0.106 0.013 06/17/10 0.092 0.009 06/23/10 0.098 0.011 06/30/10 0.112 0.015 07/15/10 0.063 0.011 07/28/10 0.055 0.013 08/05/10 0.059 0.013 08/12/10 0.083 0.012 08/19/10 0.052 0.014 09/17/10 0.045 0.016 10/07/10 0.043 0.019 02/25/11 not available 0.015 03/03/11 0.022 0.016 03/09/11 0.046 0.020 03/17/11 0.027 0.017 03/25/11 0.015 0.014 03/31/11 0.032 0.018 04/01/11 0.059 0.020 04/07/11 0.026 0.020


48 | Appendix A

Table A-5. Calculated chloride concentrations within the L-8 Reservoir, L-8 Canal and M-Canal for the L-8 Reservoir Pilot Test.

Date Calculated Chloride Concentrations

(milligram per liter)

L8MZBS L8RES L8MZBN L8-0.43 L8.MCNL 02/25/2011 157.7 274.5 125.0 66.9 74.5

02/26/2011 164.1 281.4 150.7 65.8 87.3

02/27/2011 156.8 289.0 158.6 65.9 97.8

02/28/2011 165.9 292.2 152.7 81.1 93.0

03/01/2011 174.5 295.7 85.8 65.3 72.9

03/02/2011 221.9 307.9 336.5 65.2 134.9

03/03/2011 213.4 321.9 350.3 67.6 232.9

03/04/2011 247.8 330.7 351.4 75.0 253.4

03/05/2011 272.4 350.4 350.3 69.3 237.1

03/06/2011 288.4 348.6 346.5 68.9 216.8

03/07/2011 300.2 348.8 261.4 65.3 112.1

03/08/2011 304.4 353.2 173.7 67.5 226.1

03/09/2011 312.3 345.0 137.2 74.1 267.5

03/10/2011 295.1 348.8 136.1 69.5 186.7

03/11/2011 285.3 347.1 183.1 64.7 108.5

03/12/2011 304.7 354.0 194.9 65.0 178.6

03/13/2011 305.9 363.1 163.3 67.0 205.3

03/14/2011 325.8 360.4 274.6 68.6 217.9

03/15/2011 336.7 352.5 349.1 67.9 231.4

03/16/2011 288.0 353.5 343.1 67.5 230.1

03/17/2011 224.1 357.1 329.1 68.9 245.6

03/18/2011 148.4 359.7 316.4 70.7 259.8

03/19/2011 52.8 366.7 291.6 71.4 246.1

03/20/2011 46.8 365.3 279.3 71.6 233.4

03/21/2011 110.2 334.4 263.9 74.8 237.1

03/22/2011 123.7 362.1 285.9 74.0 212.1

03/23/2011 118.0 359.1 300.7 73.1 244.0

03/24/2011 185.7 355.5 331.7 72.0 226.6

03/25/2011 368.8 353.3 356.3 68.7 153.2

03/26/2011 373.4 356.9 361.6 70.5 257.4

03/27/2011 358.4 358.4 361.3 73.1 311.9

03/28/2011 355.6 354.9 358.2 70.6 233.6

03/29/2011 371.2 357.6 358.9 68.1 223.8

03/30/2011 294.4 358.7 343.2 89.5 280.5

03/31/2011 355.6 356.5 352.5 68.2 186.4


49 | Appendix A



(milligram per liter) L8MZBS L8RES L8MZBN L8-0.43 L8.MCNL

04/01/2011 337.3 352.6 254.4 65.7 182.2

04/02/2011 340.3 356.5 346.5 65.8 202.5

04/03/2011 358.8 358.4 356.5 75.1 208.6

04/04/2011 352.6 355.0 355.4 125.6 294.6

04/05/2011 361.5 351.1 354.6 151.8 250.6

04/06/2011 364.5 353.4 362.7 150.0 238.8

04/07/2011 349.3 351.7 360.9 121.7 293.1

04/08/2011 330.7 353.0 360.0 108.1 288.0

04/09/2011 340.3 360.8 352.7 101.6 214.0

04/10/2011 348.0 370.0 359.1 148.8 211.1

04/11/2011 350.9 366.5 362.4 122.2 270.9

04/12/2011 370.8 366.4 356.0 101.6 241.5

04/13/2011 377.5 363.8 345.6 70.5 204.5

04/14/2011 382.5 373.1 372.5 74.5 315.5

04/15/2011 370.5 365.7 375.8 77.8 326.9

04/16/2011 377.4 357.8 370.0 64.0 225.7

04/17/2011 378.9 357.7 365.1 43.6 161.8

04/18/2011 378.6 368.6 365.4 105.5 316.5

04/19/2011 149.8 361.6 231.6 160.6 301.3

04/20/2011 89.3 362.7 87.9 163.7 179.6

04/21/2011 85.4 372.2 96.9 102.2 134.8

04/22/2011 77.7 373.7 92.7 80.3 83.0

04/23/2011 79.7 --- 83.6 69.8 79.7

04/24/2011 73.4 --- 75.1 64.4 80.4

04/25/2011 71.8 366.9 75.1 62.1 67.7

04/26/2011 71.7 366.2 74.5 62.3 69.9

04/27/2011 71.1 365.3 75.8 79.1 69.9

04/28/2011 71.4 365.1 77.0 127.1 77.4

04/29/2011 72.3 365.3 80.6 140.9 82.0

04/30/2011 74.5 368.2 79.7 74.5 78.4

05/01/2011 73.3 365.0 78.7 75.3 76.4

05/02/2011 73.1 364.4 78.5 78.1 78.1

05/03/2011 73.9 363.1 79.4 82.6 83.2

05/04/2011 71.5 364.3 77.7 90.0 81.1

05/05/2011 71.4 362.8 74.3 96.9 83.3

05/06/2011 72.6 362.7 73.3 101.7 80.3


50 | Appendix A

Table A-6. Calculated chloride concentrations within Grassy Waters Preserve and Lake Mangonia/Clear Lake during the L-8 Reservoir Pilot Test.


(milligrams per liter)

GW4 GW3 GW8 GW7 G-161 Control 4 LM1 02/25/2011 66.0 72.0 58.8 35.4 28.0 --- 58.8

02/26/2011 65.8 71.4 59.1 36.0 27.0 --- 58.9

02/27/2011 71.2 71.4 59.3 36.6 25.1 --- 59.1

02/28/2011 72.8 71.0 59.6 37.2 24.6 --- 59.1

03/01/2011 80.2 71.2 59.9 37.9 24.1 --- 59.2

03/02/2011 91.2 70.4 61.0 38.9 21.0 --- 59.4

03/03/2011 79.8 70.7 61.7 39.1 20.8 --- 59.5

03/04/2011 131.5 73.3 62.8 38.8 21.3 --- 59.5

03/05/2011 196.8 76.6 64.3 39.0 21.4 --- 59.5

03/06/2011 238.7 77.4 65.9 39.4 19.5 --- 59.8

03/07/2011 233.5 88.9 67.6 39.8 18.4 --- 60.5

03/08/2011 250.1 100.5 67.6 40.5 18.8 --- 60.7

03/09/2011 137.0 116.9 66.9 41.4 18.6 --- 60.8

03/10/2011 239.3 165.9 67.7 42.1 17.8 --- 62.0

03/11/2011 274.7 148.5 68.4 41.5 19.1 --- 63.5

03/12/2011 164.8 158.7 67.9 41.0 18.6 --- 64.9

03/13/2011 131.0 178.9 68.3 41.0 19.4 --- 66.0

03/14/2011 197.3 183.3 68.9 41.5 19.8 --- 66.3

03/15/2011 214.0 165.2 69.6 41.9 20.2 --- 67.1

03/16/2011 240.8 170.9 70.4 42.0 19.8 --- 69.4

03/17/2011 228.8 180.6 71.3 40.1 22.3 --- 74.3

03/18/2011 239.6 196.7 71.8 39.0 22.9 --- 75.2

03/19/2011 247.8 204.3 71.7 40.3 21.4 --- 75.5

03/20/2011 259.2 213.3 71.5 41.1 22.5 --- 76.5

03/21/2011 235.0 221.3 71.7 42.0 24.2 --- 76.8

03/22/2011 237.1 228.3 71.8 42.9 26.5 --- 77.0

03/23/2011 238.5 230.8 71.5 43.2 28.0 --- 78.8

03/24/2011 210.9 233.5 71.9 43.8 33.1 --- 83.6

03/25/2011 235.2 234.6 72.2 44.5 34.4 --- 88.4

03/26/2011 236.1 235.1 72.2 45.1 32.4 --- 89.1

03/27/2011 174.0 236.4 72.1 45.6 36.9 --- 90.9

03/28/2011 248.7 226.2 70.4 45.1 37.5 --- 94.2

03/29/2011 289.9 205.6 66.6 43.7 29.7 --- 95.2

03/30/2011 228.0 184.3 67.7 44.6 31.4 --- 95.7

03/31/2011 228.3 197.1 68.6 45.6 35.0 --- 99.1


51 | Appendix A



(milligrams per liter)

GW4 GW3 GW8 GW7 G-161 Control 4 LM1 04/01/2011 290.2 219.1 70.5 45.6 34.5 --- 101.2

04/02/2011 210.6 227.3 71.9 46.2 32.9 --- 100.6

04/03/2011 178.9 230.9 72.9 47.5 35.7 --- 102.0

04/04/2011 194.5 236.7 75.3 49.4 41.6 --- 103.0

04/05/2011 215.0 227.3 77.3 50.1 43.0 --- 103.8

04/06/2011 247.5 210.0 77.5 48.6 39.1 --- 106.0

04/07/2011 314.0 207.5 79.6 49.1 37.6 --- 107.7

04/08/2011 215.1 204.8 95.8 50.6 39.6 --- 108.6

04/09/2011 301.3 204.5 121.8 51.4 40.1 --- 110.3

04/10/2011 287.2 206.7 140.1 51.6 41.4 --- 111.4

04/11/2011 209.0 212.4 138.8 51.9 46.1 --- 113.6

04/12/2011 194.6 215.8 150.9 51.9 49.6 --- 118.2

04/13/2011 202.6 220.4 147.5 52.3 51.8 --- 119.5

04/14/2011 268.1 224.5 149.1 52.6 50.8 --- 119.9

04/15/2011 204.4 227.0 150.5 52.4 48.8 --- 119.0

04/16/2011 288.9 230.3 149.6 61.7 52.5 --- 118.9

04/17/2011 322.5 235.9 131.8 94.2 51.5 --- 121.3

04/18/2011 229.4 241.5 108.5 99.3 76.3 --- 121.9

04/19/2011 165.4 247.4 112.1 106.5 90.3 --- 122.1

04/20/2011 251.8 248.0 115.5 116.3 169.6 --- 122.7

04/21/2011 332.8 249.2 116.8 99.8 162.2 214.5 123.2

04/22/2011 372.4 249.7 113.7 89.5 201.1 195.0 123.4

04/23/2011 371.4 250.2 113.0 78.7 145.1 251.7 123.6

04/24/2011 366.7 251.6 114.5 63.8 47.2 291.4 124.1

04/25/2011 355.9 250.5 116.7 62.1 32.1 233.1 124.6

04/26/2011 357.4 250.6 120.6 64.6 36.7 186.6 125.5

04/27/2011 345.1 253.1 122.1 65.1 32.1 181.5 126.5

04/28/2011 341.9 253.7 127.2 64.6 29.3 167.7 128.0

04/29/2011 332.8 257.4 130.6 65.7 29.6 161.0 129.7

04/30/2011 291.1 259.8 131.2 65.8 30.2 188.0 130.3

05/01/2011 149.4 262.3 132.0 67.9 30.8 300.5 130.6

05/02/2011 117.4 265.0 133.4 65.0 31.2 188.2 130.8

05/03/2011 148.5 267.7 136.8 62.2 31.1 122.1 131.4

05/04/2011 98.5 270.6 144.6 59.7 31.6 129.5 133.1

05/05/2011 94.2 262.3 139.3 55.2 31.9 116.9 133.7

05/06/2011 89.8 255.8 130.1 53.8 31.3 97.3 133.3


52 | Appendix A



53 | Appendix B

Appendix B CHLORIDE CONCENTRATION REGRESSION EQUATION CALCULATION

In 2007, the South Florida Water Management District (SFWMD or District), working with the Florida Department of Environmental Protection (FDEP), derived a relationship between specific conductance and chloride for the L-8 Reservoir. The purpose of the equation was to estimate chloride levels in waters discharging from the reservoir into the L-8 Canal, and monitor changes in chloride levels in the established mixing zone in the canal. The original data used to derive the relationship was collected at stations located in the L-8 Canal and in the reservoir over 12 months. A total of 1,118 data pairs from nine monitoring locations were used in the derivation. This relationship for these two parameters fits a first order polynomial regression and is summarized in Figure B-1 below. The equation, referred to as L8EQ, was adopted by the FDEP in the L-8 Reservoir permit in August 2007 through a permit modification.

Figure B-1. Relationship between measured chloride and specific conductance

data (L-8 Equation) collected weekly at 121 reservoir stations and 997 canal stations (n = 1,118) from October 2005 to September 2006.

Note: mg/L – milligram per liter; μS/cm – microsiemens per centimeters; Std. Error – standard error.

Although the original relationship between chloride and specific conductance as defined by the L8EQ was acceptable for discharges from the reservoir when specific conductance levels ranged between 400 and 4,000 microsiemens per centimeter (µS/cm), it poorly predicted chlorides when specific conductance was less than 400 µS/cm.


54 | Appendix B

During the L-8 Reservoir Pilot Test continuous specific conductance measurements were collected at 11 monitoring locations at 15 to 60 minute intervals. An additional water quality sampling station was implemented after the pilot test was complete to monitor the chloride residual effects at the Control 4 structure. At six of the 12 monitoring locations, background specific conductance levels were less than 400 µS/cm. As a result, the L-8 Equation was found to be unsuitable to predict chloride levels at these low specific conductance levels. Therefore, a new relationship between chloride and specific conductance that would include data below the 400 µS/cm was derived.

The new derivation produced a second order polynomial regression and was limited to specific conductance levels of 3,000 µS/cm or less. The data used in the new relationship was taken from the L-8 Equation derivation with additional data retrieved from DBHYDRO, the District’s hydrologic and water quality database. The total number of data pairs used in the new derivation was 12,742. This new relationship, referred to as QUAD2, between chloride and specific conductance is summarized in Figure B-2.

Figure B-2. New relationship between chloride and specific conductance (QUAD2).

Data screening was performed to remove obvious data outliers. An example of a data outlier is when chloride levels were greater than 200 milligrams per liter (mg/L) and specific conductance was less than or equal to 100 µS/cm. Another example would be when chloride levels are less than 20 mg/L with specific conductance greater than 1,000 µS/cm.

After the QUAD2 equation was derived, a validation data set containing paired chloride and specific conductance values was assembled. L8EQ and QUAD2 were used to predict


55 | Appendix B

chloride values from measured specific conductance values. These predicted values were compared with corresponding measured values. Figure B-3 summarizes these comparisons.

When predicted values are equivalent to the measure chloride values, the data points when plotted should be aligned along a theoretical 1:1 line (blue dashed line in Figure B-3). Deviations from the theoretical 1:1 line indicate inaccuracies in the predictions. From the two plots in Figure B-3, it is evident that the QUAD2 regression equation predicts chloride values more accurately over the 0 to 3,000 µS/cm range than the original L8EQ. The regression line for the relationship of measured chloride and predicted chloride using QUAD2 does not appear to deviate from the 1:1 line (intercept is close to zero and slope is 1). Predicted chloride values using the L8EQ exhibit a positive deviation from the 1:1 line. This means that the L8EQ over predicts chloride values based on specific conductance levels.

Therefore, based on these analyses, it is recommended that QUAD2 be used for predicting chloride levels from measured specific conductance. The data suggests this equation can also be used to predict chloride levels for discharges from the L-8 Reservoir if the upper range in specific conductance does not exceed 3,000 µS/cm. The prediction equation is provided below:

Predicted Chloride = 0.0000455(SpCond)2 + 0.0845(Spcond) + 6.634 [B-1]

While QUAD2 appears to be more robust than L8EQ, its application is limited to freshwater systems (i.e., lakes, reservoirs, canals, streams, marshes) with specific conductance levels at or below 3,000 µS/cm. The regression equation may be used to predict chloride levels beyond the 3,000 μS/cm; however, it is important to note the predicted value would be a rough conservative estimate and should be used as such.


56 | Appendix B

Figure B-3. Comparison of predicted chloride values (using QUAD2 and L8EQ) to the measured chloride values at the corresponding specific conductance used to predict chloride.


57 | Appendix C

Appendix C FLOW MONITORING

This appendix provides maps showing stream gauging locations (Figures C-1 through C-5). It also contains comparative time series plots of discharge at the upstream and downstream locations of each reach. The location of the reaches is provided in Figure 4 in the main document and Figure F-2 in Appendix F. Figures C-6 through C-10 present time series for Reaches 1 through 5.


58 | Appendix C

Figure C-1. Stream gauge measurements on March 7, 2011 at Reach 1.

Note: DS – downstream.


59 | Appendix C

Figure C-2. Stream gauge measurements on March 8, 2011 at Reaches 2, 4 and 5.

Note: DS – downstream; US – upstream; WPB - West Palm Beach.


60 | Appendix C

Figure C-3. Stream gauge measurements on March 17, 2011 at Reaches 2 and 3.

Note: DS - downstream; WPB – West Palm Beach.


61 | Appendix C




62 | Appendix C




63 | Appendix C

Figure C-6. Time series plots of discharges upstream and downstream of Reach 1.

Note: cfs - cubic feet per second; CWPB2 - City of West Palm Beach Control 2 pump station; CWPB3 - City of West Palm Beach Control 3 structure.


64 | Appendix C


Note: cfs - cubic feet per second; CWPB3 - City of West Palm Beach Control 3 structure.


65 | Appendix C



Note: cfs - cubic feet per second; CWPB4 - City of West Palm Beach Control 4 structure.


66 | Appendix C


Note: cfs - cubic feet per second; CWPB4 – City of West Palm Beach Control 4 structure.


67 | Appendix D

Appendix D DATA USED IN THE WATER BUDGET

Table D-1 contains the data used in the water budget discussed in Section 4 of the main document and Appendix G.


68 | Appendix D

Table D-1. Data used in the water budget.

Date Rainfall (inches)

ET1 (inches)

M-Canal Stage

(ft NGVD29)2

PGA-W05 Groundwater

Well Stage (ft NGVD29)

Grassy Waters Preserve Stage

Measured at G-161 (feet)

G-161 Outflow to Loxahatchee River

via C-18 Canal (cfs)3

Control 2 Flow (cfs)


Callery Judge Withdrawal

(acre-feet per day)

3/1/2011 0.005 0.121 18.72 16.06 18.69 2.1 80.2 45.21 0

3/2/2011 0.000 0.141 18.69 16.04 18.68 19.77 78.35 58.59 0

3/3/2011 0.002 0.139 18.69 16.01 18.63 21.65 112.26 58.19 9.02

3/4/2011 0.000 0.173 18.67 15.97 18.61 21.61 122.72 56.84 0

3/5/2011 0.146 0.109 18.64 16.00 18.6 21.55 149.94 55.40 0

3/6/2011 0.169 0.112 18.68 16.11 18.58 21.69 150.22 58.22 0

3/7/2011 0.000 0.200 18.68 16.07 18.61 25.92 144.41 57.54 0

3/8/2011 0.000 0.193 18.66 16.01 18.6 21.91 145 56.06 11.59

3/9/2011 0.000 0.160 18.63 15.97 18.58 21.98 144.9 54.43 11.3

3/10/2011 0.126 0.060 18.63 16.02 18.57 22.34 143.51 54.54 12.05

3/11/2011 0.000 0.213 18.67 15.99 18.57 22.31 121.56 33.97 0

3/12/2011 0.000 0.211 18.63 15.92 18.56 22.23 145.66 80.99 0

3/13/2011 0.000 0.202 18.63 15.89 18.54 22.19 144.9 81.37 0

3/14/2011 0.000 0.196 18.61 15.86 18.54 27.67 144.85 39.71 9.21

3/15/2011 0.000 0.130 18.61 15.83 18.52 29.94 145.05 69.96 11.3

3/16/2011 0.000 0.152 18.58 15.81 18.5 29.89 145 67.83 11.3

3/17/2011 0.000 0.163 18.57 15.78 18.49 29.82 145.07 22.61 5.1

3/18/2011 0.000 0.188 18.54 15.73 18.48 29.74 139.69 68.74 5.1

3/19/2011 0.000 0.193 18.51 15.70 18.46 29.63 143.57 67.31 0

3/20/2011 0.035 0.152 18.51 15.69 18.45 29.52 144 65.40 0

1 ET - evapotranspiration 2 ft NGVD29 - feet National Geodetic Vertical Datum of 1929 3 cfs - cubic feet per second


69 | Appendix D

Table D-1. continued.


ET4 (inches)

M-Canal Stage

(ft NGVD29)5

PGA-W05 Groundwater









(acre-feet per day)

3/21/2011 0.003 0.183 18.49 15.69 18.44 29.28 143.48 64.59 11.34

3/22/2011 0.000 0.196 18.49 15.62 18.43 28.54 143.29 64.41 5.65

3/23/2011 0.000 0.189 18.47 15.58 18.42 28.46 135.74 63.45 0

3/24/2011 0.000 0.192 18.44 15.54 18.4 28.36 149.78 61.29 11.3

3/25/2011 0.000 0.196 18.41 15.49 18.38 28.2 136.61 69.15 6.82

3/26/2011 0.000 0.207 18.38 15.44 18.36 28.02 150.22 57.40 0

3/27/2011 0.000 0.200 18.37 15.39 18.33 27.89 150.1 56.46 0

3/28/2011 1.184 0.068 18.35 15.86 18.31 27.98 144.54 55.24 10.19

3/29/2011 0.033 0.188 18.46 16.09 18.34 35.92 142.25 63.10 0

3/30/2011 0.000 0.192 18.46 16.00 18.39 41.52 144.93 61.99 0

3/31/2011 0.001 0.149 18.4 15.89 18.38 41.37 135 61.05 0

4/1/2011 0.145 0.225 18.41 15.92 18.36 41.41 121.56 59.38 0

4/2/2011 0.000 0.228 18.38 15.76 18.35 41.05 144.67 57.19 9.17

4/3/2011 0.000 0.219 18.38 15.66 18.32 40.83 143.9 58.00 0

4/4/2011 0.000 0.213 18.37 15.58 18.3 40.7 132.27 56.53 0

4/5/2011 0.285 0.093 18.34 15.76 18.29 40.49 145.63 54.57 0

4/6/2011 0.000 0.222 18.35 15.79 18.28 40.46 138.79 55.31 0

4/7/2011 0.000 0.160 18.37 15.62 18.27 40.27 150.93 54.89 0

4/8/2011 0.000 0.142 18.33 15.51 18.25 40.08 150.07 29.97 4.85

4/9/2011 0.000 0.207 18.26 15.41 18.23 39.83 150.66 70.36 0



70 | Appendix D

Table D-1. continued.


ET7 (inches)

M-Canal Stage

(ft NGVD29)8

PGA-W05 Groundwater









(acre-feet per day)

4/10/2011 0.000 0.185 18.24 15.33 18.21 39.56 150.42 69.43 0

4/11/2011 0.000 0.179 18.21 15.24 18.18 35.63 78.04 66.53 0

4/12/2011 0.000 0.221 18.12 15.14 18.15 34.2 64.37 59.87 8.9

4/13/2011 0.000 0.232 18.13 15.06 18.11 33.78 151.14 60.25 0

4/14/2011 0.000 0.233 18.11 14.96 18.07 33.47 148 34.72 4.31

4/15/2011 0.001 0.142 18.08 14.90 18.04 33.18 139.26 22.59 0

4/16/2011 0.068 0.196 18.15 14.85 18.01 33.06 150.9 0.00 0

4/17/2011 0.292 0.203 18.18 14.80 17.99 33.02 150.76 0.00 0

4/18/2011 0.079 0.154 18.24 14.80 17.98 33.29 150.46 0.00 0

4/19/2011 0.000 0.209 18.22 14.73 18.01 21.53 148.04 0.00 4.45



71 | Appendix E

Appendix E CLIMATE, STAGE AND FLOW DATA

This appendix provides climate, stage and flow data collected before, during and after the L-8 Reservoir Pilot Test. Table E-1 contains climate, stage, and flow for the L-8 Reservoir and from monitoring stations along Flow-way 1. Climate data include rainfall and evapotranspiration (ET). Stage data in Table E-1 are in feet National Geodetic Vertical Datum of 1929 (ft NGVD1929). Flow data are in cubic feet per second (cfs). Sources of data in Table E-1 are provided at the end of the table.


72 | Appendix E



73 | Appendix E

Table E-1. Climate, stage, flow and chloride data for the L-8 Reservoir and along Flow-way 1.

Climate Data (inches)

Stage (ft NGVD29)

Flow (cfs)

Grassy1

Water Preserve Rainfall

L-82

Reservoir Rainfall

Grassy3

Waters Preserve

ET

L-8 Reservoir2

Evaporation

L-84

Reservoir Stage

L8GRC5 M-Canal

6 Control 4

6 Nature

6

Center

PGA-W057

Groundwater Well

G161_H8 G160_H

9 G92_H

10 LNHRT_H

11 LNHRT_T

12

L-813

Reservoir Pumping

Control 26 Callery

14 Judge

Withdrawal Control 46 G161_S

15 G160_S

16 G92_C

17 LNHRT_W

18 LNHRT

19

/1/11

Not used in report

0.00

Not used in report

0.09 5.47 11.64

Not used in report

0.00

Not used in report

1/02/11 0.00 0.09 5.49 11.95 0.00

03/11 0.00 0.09 5.51 12.09 0.00

1/04/11 0.00 0.10 5.53 11.77 0.00

1/05/11 0.00 0.04 5.54 11.8 0.00

1/06/11 0.00 0.11 5.59 11.97 0.00

1/07/11 0.48 0.03 5.63 12.83 0.00

1/08/11 0.00 0.08 5.61 12.36 0.00

1/09/11 0.00 0.08 5.62 12.15 0.00

1/10/11 0.00 0.08 5.64 12.02 0.00

1/11/11 0.00 0.07 5.65 11.98 0.00

1/12/11 0.00 0.11 5.66 11.8 0.00

1/13/11 0.00 0.17 5.65 11.65 0.00

1/14/11 0.00 0.07 5.66 11.74 0.00

1/15/11 0.00 0.06 5.67 11.61 0.00

1/16/11 0.00 0.06 5.68 11.46 0.00

1/17/11 0.00 0.06 5.71 11.59 0.00

1/18/11 0.16 0.06 5.73 12.08 0.00

1/19/11 0.43 0.05 5.76 12.5 0.00

1/20/11 0.00 0.05 5.77 12.01 0.00

1/21/11 0.01 0.08 5.81 11.82 0.00

1/22/11 0.03 0.05 5.84 12.13 0.00

1/23/11 0.00 0.10 5.84 12.15 0.00

1/24/11 0.00 0.10 5.85 12.18 0.00

1/25/11 0.00 0.04 5.87 12.18 0.00

1/26/11 0.83 0.10 5.94 12.56 0.00

1/27/11 0.00 0.09 5.94 12.47 0.00

1/28/11 0.00 0.11 5.95 12.58 0.00

1/29/11 0.00 0.07 5.95 12.5 0.00

1/30/11 0.00 0.07 5.96 12.46 0.00

1/31/11 0.00 0.07 5.98 12.18 0.00

2/01/11 0.00 0.08 5.99 11.74 0.00

2/02/11 0.00 0.09 6.01 11.54 0.00

2/03/11 0.00 0.09 6.02 11.67 0.00

2/04/11 0.00 0.13 6.04 11.65 0.00

2/05/11 0.01 0.10 6.05 11.61 0.00


74 | Appendix E

Table E-1. continued.

Date


Stage (ft NGVD29)

Flow (cfs)

Grassy1 Water

Preserve Rainfall

L-82 Reservoir Rainfall

Grassy3 Waters

Preserve ET

L-8 Reservoir2 Evaporation

L-84 Reservoir

Stage L8GRC5 M-Canal6 Control 46 Nature6

Center

PGA-W057 Groundwater

Well G161_H8 G160_H9 G92_H10 LNHRT_H11 LNHRT_T12

L-813

Reservoir Pumping

Control 26 Callery

14 Judge


15 G160_S

16 G92_C

17 LNHRT_W

18 LNHRT

19

2/06/11

Not used in report

0.00

Not used in report

0.10 6.06 11.69

Not used in report

0.00

Not used in report

2/07/11 0.00 0.10 6.08 11.82 0.00

2/08/11 0.00 0.18 6.08 12.04 0.00

2/09/11 0.00 0.12 6.08 11.87 0.00

2/10/11 0.00 0.07 6.11 11.95 0.00

2/11/11 0.37 0.10 6.15 12.47 0.00

2/12/11 0.27 0.11 6.16 12.19 0.00

2/13/11 0.05 0.11 6.15 11.85 0.00

2/14/11 0.00 0.11 6.16 11.65 0.00

2/15/11 0.00 0.11 6.16 11.55 0.00

2/16/11 0.00 0.11 6.17 11.27 0.00

2/17/11 0.05 0.09 6.19 11.32 0.00

2/18/11 0.00 0.01 6.20 11.5 0.00

2/19/11 0.01 0.14 6.21 11.44 0.00

2/20/11 0.00 0.14 6.22 11.34 0.00

2/21/11 0.00 0.14 6.24 11.15 0.00

2/22/11 0.00 0.14 6.25 11.18 0.00

2/23/11 0.00 0.15 6.26 11.44 0.00

2/24/11 0.00 0.14 6.27 11.71 0.00

2/25/11 0.00 0.11 6.28 11.84 0.00

2/26/11 0.00 0.16 6.28 11.88 0.00

2/27/11 0.00 0.16 6.29 11.66 0.00

2/28/11 0.00 0.16 6.31 11.5 0.00

3/1/11 0.01 0.00 0.12 0.19 6.29 11.37 18.72 18.72 18.78 16.06 18.68 12.38 12.09 10.47 8.61 42.46 80.20 0.00 45.21 2.10 13.85 26.13 14.20 20.00

3/02/11 0.00 0.00 0.14 0.15 6.14 11.44 18.69 18.69 18.76 16.04 18.63 12.61 12.17 10.57 8.75 90.40 78.35 0.00 58.59 19.77 30.06 32.46 16.40 25.00

3/03/11 0.00 0.00 0.14 0.16 5.98 11.41 18.69 18.69 18.75 16.01 18.61 12.55 12.27 10.69 9.04 84.62 112.26 4.55 58.19 21.65 29.28 40.12 21.86 34.00

3/04/11 0.00 0.01 0.17 0.16 5.81 11.49 18.67 18.67 18.74 15.97 18.60 12.49 12.23 10.76 9.21 90.11 122.72 0.00 56.84 21.61 34.67 45.89 26.30 41.00

3/05/11 0.15 0.00 0.11 0.12 5.65 11.52 18.64 18.64 18.72 16.00 18.58 12.38 12.18 10.76 9.21 89.97 149.94 0.00 55.40 21.55 33.19 42.89 25.93 41.00

3/06/11 0.17 0.27 0.11 0.12 5.51 11.66 18.68 18.68 18.73 16.11 18.61 12.44 12.24 10.74 9.16 89.84 150.22 0.00 58.22 21.69 35.02 41.22 24.82 41.00

3/07/11 0.00 0.00 0.20 0.12 5.35 11.71 18.68 18.68 18.73 16.07 18.60 12.47 12.27 10.74 9.17 89.69 144.41 0.00 57.54 25.92 35.11 41.84 25.03 41.00

3/08/11 0.00 0.00 0.19 0.15 5.18 11.72 18.66 18.66 18.71 16.01 18.58 12.47 12.28 10.74 9.16 89.54 145.00 5.84 56.06 21.91 33.96 42.19 24.89 42.00

3/09/11 0.00 0.00 0.16 0.13 5.03 11.35 18.63 18.63 18.70 15.97 18.57 12.45 12.26 10.74 9.15 88.22 144.90 5.70 54.43 21.98 33.80 42.21 24.73 42.00

3/10/11 0.13 0.00 0.06 0.13 4.89 11.54 18.63 18.63 18.70 16.02 18.57 12.46 12.26 10.74 9.15 89.27 143.51 6.08 54.54 22.34 33.90 42.40 24.72 42.00

3/11/11 0.00 0.27 0.21 0.19 4.73 11.78 18.67 18.67 18.70 15.99 18.56 12.44 12.26 10.74 9.15 89.13 121.56 0.00 33.97 22.31 34.68 42.28 24.61 42.00

3/12/11 0.00 0.00 0.21 0.13 4.56 11.56 18.63 18.63 18.70 15.92 18.54 12.42 12.23 10.73 9.13 88.96 145.66 0.00 80.99 22.23 34.31 41.82 24.25 42.00

3/13/11 0.00 0.00 0.20 0.13 4.40 11.39 18.63 18.63 18.68 15.89 18.54 12.39 12.20 10.73 9.12 88.82 144.90 0.00 81.37 22.19 34.60 41.57 24.12 41.00

3/14/11 0.00 0.00 0.20 0.13 4.25 11.40 18.61 18.61 18.66 15.86 18.52 12.38 12.19 10.73 9.10 88.67 144.85 4.64 39.71 27.67 35.47 41.46 23.84 41.00

3/15/11 0.00 0.00 0.13 0.18 4.09 11.44 18.61 18.61 18.65 15.83 18.50 12.41 12.21 10.72 9.09 88.52 145.05 5.70 69.96 29.94 36.40 41.89 23.71 41.00


75 | Appendix E


Date


Stage (ft NGVD29)

Flow (cfs)

Grassy1 Water

Preserve Rainfall


Grassy3 Waters

Preserve ET


L-84 Reservoir


Center



L-813

Reservoir Pumping

Control 26 Callery

14 Judge


15 G160_S

16 G92_C

17 LNHRT_W

18 LNHRT

19

3/16/11 0.00 0.00 0.15 0.12 3.94 11.42 18.58 18.58 18.65 15.81 18.49 12.42 12.23 10.73 9.09 88.38 145.00 5.70 67.83 29.89 35.60 42.23 23.80 41.00

3/17/11 0.00 0.00 0.16 0.13 3.79 11.47 18.57 18.57 18.64 15.78 18.48 12.43 12.23 10.73 9.09 87.86 145.07 2.57 22.61 29.82 35.72 42.26 23.77 41.00

3/18/11 0.00 0.00 0.19 0.17 3.63 11.41 18.54 18.54 18.62 15.73 18.46 12.43 12.24 10.72 9.08 88.08 139.69 2.57 68.74 29.74 35.86 42.36 23.67 41.00

3/19/11 0.00 0.00 0.19 0.16 3.48 11.33 18.51 18.51 18.60 15.70 18.45 12.43 12.23 10.72 9.07 87.93 143.57 0.00 67.31 29.63 35.77 42.26 23.42 41.00

3/20/11 0.04 0.00 0.15 0.16 3.33 11.44 18.51 18.51 18.58 15.69 18.44 12.42 12.22 10.71 9.06 87.79 144.00 0.00 65.40 29.52 35.50 42.30 23.07 40.00

3/21/11 0.00 0.00 0.18 0.16 3.18 11.33 18.49 18.49 18.58 15.69 18.43 12.41 12.21 10.71 9.05 87.64 143.48 5.72 64.59 29.28 35.69 42.18 22.91 40.00

3/22/11 0.00 0.00 0.20 0.18 3.04 11.27 18.49 18.49 18.58 15.62 18.42 12.39 12.20 10.71 9.04 84.89 143.29 2.85 64.41 28.54 35.58 41.98 22.53 40.00

3/23/11 0.00 0.00 0.19 0.17 2.89 11.33 18.47 18.47 18.55 15.58 18.40 12.37 12.19 10.70 9.03 87.36 135.74 0.00 63.45 28.46 35.02 41.84 22.46 40.00

3/24/11 0.00 0.00 0.19 0.15 2.74 11.43 18.44 18.44 18.53 15.54 18.38 12.36 12.16 10.70 9.02 87.20 149.78 5.70 61.29 28.36 35.99 41.43 22.24 39.00

3/25/11 0.00 0.00 0.20 0.19 2.59 11.34 18.41 18.41 18.49 15.49 18.36 12.34 12.15 10.69 9.00 87.05 136.61 3.44 69.15 28.20 35.56 41.19 21.92 38.00

3/26/11 0.00 0.00 0.21 0.19 2.44 11.40 18.38 18.38 18.47 15.44 18.33 12.32 12.12 10.69 8.98 86.90 150.22 0.00 57.40 28.02 35.67 40.88 21.71 38.00

3/27/11 0.00 0.00 0.20 0.19 2.30 11.34 18.37 18.37 18.45 15.39 18.31 12.28 12.10 10.68 8.97 86.76 150.10 0.00 56.46 27.89 34.53 40.79 20.97 37.00

3/28/11 1.18 0.00 0.07 0.19 2.19 11.43 18.35 18.35 18.47 15.86 18.34 12.32 12.14 10.70 9.05 86.65 144.54 5.14 55.24 27.98 34.35 40.82 22.24 39.00

3/29/11 0.03 1.00 0.19 0.08 2.11 11.63 18.46 18.46 18.51 16.09 18.39 12.43 12.23 10.72 9.11 85.85 142.25 0.00 63.10 35.92 37.24 41.91 23.51 41.00

3/30/11 0.00 0.05 0.19 0.08 1.98 11.47 18.46 18.46 18.51 16.00 18.38 12.53 12.30 10.72 9.11 86.44 144.93 0.00 61.99 41.52 39.34 42.97 23.67 40.00

3/31/11 0.00 0.00 0.15 0.08 1.85 11.45 18.40 18.40 18.50 15.89 18.36 12.59 12.35 10.73 9.11 76.41 135.00 0.00 61.05 41.37 39.74 43.76 23.79 41.00

4/01/11 0.15 0.05 0.23 0.20 1.72 11.63 18.41 18.41 18.49 15.92 18.35 12.65 12.39 10.73 9.13 86.17 121.56 0.00 59.38 41.41 40.45 44.17 24.07 41.00

4/02/11 0.00 0.00 0.23 0.18 1.57 11.42 18.38 18.38 18.46 15.76 18.32 12.66 12.40 10.73 9.11 86.01 144.67 4.62 57.19 41.05 40.91 44.63 23.81 41.00

4/03/11 0.00 0.00 0.22 0.18 1.43 11.27 18.38 18.38 18.44 15.66 18.30 12.66 12.41 10.72 9.10 85.87 143.90 0.00 58.00 40.83 40.74 44.68 23.64 41.00

4/04/11 0.00 0.00 0.21 0.18 1.29 11.15 18.37 18.37 18.43 15.58 18.29 12.67 12.42 10.75 9.19 85.72 132.27 0.00 56.53 40.70 40.53 44.05 25.74 44.00

4/05/11 0.29 0.00 0.09 0.23 1.18 11.18 18.34 18.34 18.41 15.76 18.28 12.69 12.44 10.73 9.16 39.80 145.63 0.00 54.57 40.49 39.84 45.00 23.99 42.00

4/06/11 0.00 0.27 0.22 0.15 1.16 11.27 18.35 18.35 18.43 15.79 18.27 12.71 12.45 10.73 9.14 61.24 138.79 0.00 55.31 40.46 40.30 45.21 23.81 42.00

4/07/11 0.00 0.00 0.16 0.15 1.02 11.40 18.37 18.34 18.39 15.62 18.25 12.70 12.44 10.73 9.16 85.44 150.93 0.00 54.89 40.27 40.12 44.86 24.18 42.00

4/08/11 0.00 0.00 0.14 0.16 0.88 11.43 18.33 18.33 18.38 15.51 18.23 12.70 12.44 10.73 9.15 85.18 150.07 2.45 29.97 40.08 39.63 44.94 24.25 42.00

4/09/11 0.00 0.00 0.21 0.16 0.74 11.47 18.26 18.26 18.36 15.41 18.21 12.68 12.43 10.73 9.13 71.88 150.66 0.00 70.36 39.83 39.26 44.83 23.95 42.00

4/10/11 0.00 0.00 0.19 0.16 0.68 11.38 18.24 18.24 18.33 15.33 18.18 12.66 12.42 10.72 9.10 55.67 150.42 0.00 69.43 39.56 39.06 44.67 23.64 41.00

4/11/11 0.00 0.00 0.18 0.16 0.55 11.43 18.21 18.21 18.32 15.24 18.15 12.63 12.39 10.72 9.07 84.94 78.04 0.00 66.53 35.63 38.53 44.33 23.68 42.00

4/12/11 0.00 0.00 0.22 0.24 0.41 11.44 18.12 18.12 18.27 15.14 18.11 12.57 12.35 10.71 9.05 78.26 64.37 4.49 59.87 34.20 37.60 43.84 22.76 41.00

4/13/11 0.00 0.00 0.23 0.20 0.27 11.30 18.13 18.13 18.22 15.06 18.07 12.52 12.30 10.70 9.02 84.64 151.14 0.00 60.25 33.78 36.96 43.16 22.10 40.00

4/14/11 0.00 0.00 0.23 0.19 0.12 11.20 18.11 18.11 18.19 14.96 18.04 12.66 12.17 10.68 8.97 83.02 148.00 2.17 34.72 33.47 30.73 41.43 21.22 38.00

4/15/11 0.00 0.00 0.14 0.20 -0.02 11.21 18.08 18.08 18.16 14.90 18.01 12.45 12.20 10.68 8.96 84.34 139.26 0.00 22.59 33.18 42.09 42.05 21.17 38.00

4/16/11 0.07 0.00 0.20 0.14 -0.16 11.26 18.15 18.15 18.15 14.85 17.99 12.37 12.18 10.68 8.96 84.19 150.90 0.00 0.00 33.06 36.86 41.83 21.10 37.00

4/17/11 0.29 0.00 0.20 0.14 -0.30 11.22 18.18 18.18 18.14 14.80 17.98 12.34 12.14 10.67 8.94 84.04 150.76 0.00 0.00 33.02 37.31 41.21 20.61 37.00

4/18/11 0.08 0.16 0.15 0.14 -0.40 11.23 18.24 18.24 18.14 14.80 18.01 12.32 12.12 10.68 8.94 83.43 150.46 0.00 0.00 33.29 38.02 40.60 20.83 37.00

4/19/11 0.00 0.10 0.21 0.16 -0.48 11.14 18.22 18.22 18.17 14.73 18.04 12.28 12.10 10.66 8.90 33.94 148.04 2.24 0.00 21.53 33.46 38.32 20.13 37.00

4/20/11

Not used in report

0.00

Not used in report

0.20 -0.49 10.72 18.21 18.21 18.18

Not used in report

0.00 3.87

4/21/11 0.00 0.20 -0.46 10.49 18.12 18.12 18.18 0.12 36.37

4/22/11 0.00 0.22 -0.44 10.35 18.09 18.09 18.15 0.00 34.90

4/23/11 0.00 0.18 -0.39 10.53 18.04 18.04 18.15 0.00 32.70


76 | Appendix E


Date


Stage (ft NGVD29)

Flow (cfs)

Grassy1 Water

Preserve Rainfall


Grassy3 Waters

Preserve ET)


L-84 Reservoir


Center



L-813

Reservoir Pumping

Control 26 Callery

14 Judge


15 G160_S

16 G92_C

17 LNHRT_W

18 LNHRT

19

4/24/11

Not used in report

0.00

Not used in report

0.18 -0.38 10.56 17.99 17.99 18.11

Not used in report

0.00

Not used in report

30.02

Not used in report

4/25/11 0.27 0.18 -0.35 10.5 17.95 17.95 18.08 0.00 27.95

4/26/11 0.00 0.18 -0.32 10.29 17.97 17.97 18.07 0.00 18.22

4/27/11 0.00 0.22 -0.30 10.48 17.78 17.78 18.04 0.00 54.68

4/28/11 0.00 0.22 -0.28 10.34 17.78 17.78 17.99 0.00 54.61

4/29/11 0.00 0.22 -0.26 10.39 17.72 17.72 17.95 0.00 51.15

4/30/11 0.00 0.24 -0.25 10.08 17.67 17.67 17.89 0.00 48.65

5/1/11 0.00 0.19 -0.23 10.07

Not used in report

0.00

Not used in report

5/2/11 0.01 0.19 -0.21 10.41 0.00

5/3/11 0.00 0.20 -0.20 10.34 0.00

5/4/11 0.00 0.22 -0.18 10.23 0.00

5/5/11 0.08 0.18 -0.15 10.14 0.00

5/6/11 0.43 0.06 -0.11 10.19 0.00

5/7/11 0.10 0.13 -0.09 10.23 0.00

5/8/11 0.00 0.20 -0.07 10.08 0.00

5/9/11 0.00 0.20 -0.06 10.34 0.00

5/10/11 0.00 0.20 -0.04 10.24 0.00

5/11/11 0.00 0.22 -0.02 9.97 0.00

5/12/11 0.00 0.22 -0.01 9.94 0.00

5/13/11 0.00 0.17 0.02 9.87 0.00

5/14/11 0.00 0.06 0.09 9.79 0.00

5/15/11 3.32 0.06 0.26 9.67 0.00

5/16/11 0.21 0.06 0.27 9.84 0.00

5/17/11 0.00 0.19 0.29 9.86 0.00

5/18/11 0.19 0.20 0.30 9.78 0.00

5/19/11 0.00 0.18 0.32 9.83 0.00

5/20/11 0.00 0.19 0.34 9.82 0.00

5/21/11 0.00 0.19 0.36 9.9 0.00

5/22/11 0.00 0.19 0.38 9.79 0.00

5/23/11 0.00 0.19 0.40 10.02 0.00

5/24/11 0.00 0.14 0.41 9.75 0.00

5/25/11 0.00 0.18 0.42 9.56 0.00

5/26/11 0.00 0.22 0.44 9.66 0.00

5/27/11 0.00 0.21 0.45 9.7 0.00

5/28/11 0.10 0.17 0.50 9.62 0.00

5/29/11 0.32 0.17 0.56 9.69 0.00

5/30/11 0.04 0.17 0.58 9.76 0.00

5/31/11 0.08 0.20 0.60 9.66 0.00

6/1/11 0.00 0.23 0.62 9.47 0.00

6/2/11 0.00 0.23 0.62 9.45 0.00


77 | Appendix E


Date


Stage (ft NGVD29)

Flow (cfs)

Grassy1 Water

Preserve Rainfall


Grassy3 Waters

Preserve ET

L-8 Reservoir2 Evaporation)

L-84 Reservoir


Center



L-813

Reservoir Pumping

Control 26 Callery

14 Judge


15 G160_S

16 G92_C

17 LNHRT_W

18 LNHRT

19

6/3/11 0.00 0.26 0.63 9.45 0.00

6/4/11 0.00 0.22 0.64 9.50 0.00

6/5/11 0.00 0.22 0.65 9.48 0.00

6/6/11 0.00 0.22 0.66 9.51 0.00

6/7/11 0.00 0.21 0.67 9.43 0.00

6/8/11 0.00 0.25 0.68 9.44 0.00

6/9/11 0.00 0.20 0.69 9.41 0.00

6/10/11 0.00 0.13 0.73 9.41 0.00

6/11/11 0.00 0.23 0.76 9.47 0.00

6/12/11 0.00 0.23 0.77 9.49 0.00

6/13/11 0.00 0.23 0.79 9.47 0.00

6/14/11 0.43 0.29 0.84 9.34 0.00

6/15/11 0.83 0.10 0.87 9.41 0.00

6/16/11 0.01 0.10 0.88 9.35 0.00

6/17/11 0.00 0.16 0.89 9.43 0.00

Superscript Legend:

1 NEXRAD 2 S-5A adjusted 3 Radiation method of ET estimation 4 DBKEY: W1969 5 DBKEY: OT897 6 City of West Palm Beach supplied data 7 DBKEY TB042 8 DBKEY VC277 9 DBKEY T0905 10 DBKEY 11681 11 DBKEY 16557 12 DBKEY VV423 13 DBKEY 87593 14 Callery Judge data 15 DBKEY VG102 16 DBKEY T0911 17 DBKEY WN411 18 DBKEY JL988 19 USGS 0227600


78 | Appendix E



79 | Appendix F

Appendix F MODEL REFINEMENTS

Pilot Test Relationship to Everglades Restoration

The Loxahatchee River Watershed Restoration Project is a Comprehensive Everglades Restoration Plan (CERP) project currently undergoing plan formulation to determine a tentatively selected plan. It was previously called North Palm Beach County - Part 1. The project area lies within northern Palm Beach County and southern Martin County with a focus on the Loxahatchee River watershed. The study area extends south to the C-51 Canal in Palm Beach County and north to approximately Bridge Road in Martin County and the C-44 Canal to allow the Loxahatchee River watershed to be connected with other features of the regional system in the future. The eastern boundary of the watershed is the Intracoastal Waterway and the western boundary is the L-8 Canal and Lake Okeechobee. For more information see www.evergladesplan.org/pm/projects/proj_17_lox_river.aspx.

Several flow-ways have been conceptualized to meet project objectives over an area of approximately 480,000 acres (753 square miles). The flow-way concepts all use the L-8 Reservoir as the upstream starting point. The downstream ending point for all is Lainhart Dam, which is the point at which restoration flows are measured. Each flow-way utilizes the existing infrastructure of several systems, as well as including proposed features (e.g., new structure, canal). Because the distance to Lainhart Dam is greater than 28 miles, flow-way designs must consider any constraints within the existing systems when diverting water from the L-8 Reservoir.

The 2011 L-8 Project Pilot Test utilized Flow-way 1 (Figure F-1) to test dry season operations and water deliveries to the Northwest Fork of the Loxahatchee River (Swift 2011). South Florida Water Management District (SFWMD or District) staff collected stream gauge measurements along the M-Canal during the pilot test to estimate flow losses (SFWMD 2011). Since the L-8 Reservoir is intended to capture, store and deliver L-8 basin runoff to meet downstream demands, understanding the water budget and especially conveyance and seepage losses is necessary for future operational testing and reservoir design requirements.

http://www.evergladesplan.org/pm/projects/proj_17_lox_river.aspx


80 | Appendix F

Figure F-1. Flow path for the delivery of L-8 Reservoir water to Grassy Waters Preserve and the Northwest Fork of the Loxahatchee River.

Note: WPB - West Palm Beach.


81 | Appendix F

The requirements (or performance measures) for ecosystem restoration are put forth in the project objectives provided in the Draft Alternatives Formulation Briefing (Ecology and Environment, Inc. 2010). Numerical models have been applied to help determine the extent to which these objectives can be expected to be met. One of the hydrologic models applied at this stage of the CERP planning process is the Northern Palm Beach County version of the Lower East Coast Subregional Model (LECsR-NP) (Montoya et al. 2010). This model has been applied to determine changes to the subregional hydrology in the project area by evaluating combinations of project alternatives (Kuebler and Montoya 2010, Mullen et al. 2010). These applications may be used to calculate project benefits and to help determine the tentatively selected plan. In addition, these applications were evaluated for the L-8 Pump conceptual design (Hall 2011, Panigrahi 2011). Frequency analyses of model output were generated to give some guidance to the design team as to the relative sizing options for the pump station and the inflow control structure capacity (Hall 2011, Panigrahi 2011).

Hydrologic Modeling Approach

Within the timeframe of the planning and execution of the pilot test, the United States Army Corps of Engineers (USACE) review of the Loxahatchee River Watershed Restoration Project determined additional plan formulation modeling was necessary. During the development of project and model assumptions, a request was made to investigate the possibility of including a seepage assumption for the M-Canal in the LECsR-NP to determine if seepage losses would affect achieving project benefits.

Currently, the model does not consider seepage along M-Canal Reaches 1, 4 and 5 (i.e., the model transfers water directly from the reservoir to the M-Canal). It does account for seepage losses within Grassy Waters Preserve, which includes Reaches 2 and 3 (Figure F-2). Since measureable losses were observed along Reaches 1 and 5 during the pilot test, the District and USACE investigated the possibility of including a seepage assumption for the reaches in the model.

Investigating Seepage Assumptions

Measurements collected during the pilot test, provided an opportunity to investigate and possibly include seepage into the model. The project team considered several options. They considered selecting the lowest seepage value from the stream gauge test (i.e., 4 cubic feet per second [cfs]) and applying this value to the model. This lower number could either be applied only during the dry season, or be applied year-round and adjusted based on seasonal driving head estimates. This lower number was suggested in order to be conservative and not overestimate seepage, but it was later contended that selecting a conservative value would depend on each individual’s definition of “conservative” in this context. For example, conservative could mean a value that is defensible, or a value that is more likely to guarantee benefits at target areas. It seemed difficult to justify simply picking one measured seepage value from the stream gauge test since such a limited number of data points were taken during such a limited time frame.


82 | Appendix F

Figure F-2. Schematic of M-Canal indicting the four sections and highlighting the five reaches where measurements were conducted.

Note: Water Catchment Area is the same as Grassy Waters Preserve.


83 | Appendix F

The team also considered collecting additional data. This option was later screened out because it requires more time and is labor intensive, as it would require measuring an expanded set of surrounding groundwater, stage and flow data. It was also uncertain whether a representative data set could be collected without multiple years of observations, which would further delay the project schedule.

Another option considered was finding the average monthly modeled seepage using a previous version of the Lower East Coast Subregional Model (LECsR) (Giddings et al. 2006) that applied the river package of the Modular Three-dimensional Finite-difference Groundwater Flow Model (referred to as MODFLOW) along the M-Canal. The river package calculates leakage. This method is independent of the pilot test and analyzed only model data. The leakage was post processed to calculate the average monthly leakage. Then sensitivity runs were executed to evaluate the effects of the losses on project benefits and reservoir storage. The average leakage by month for Reaches 1, 4 and 5 combined was 17 cfs in the dry season and 3 cfs in the wet season for the period of record (1986–2000) (Figure F-3).

Figure F-3. Average monthly modeled seepage for Reaches 1, 4 and 5 as simulated by the LECsR with the MODFLOW river package applied.


84 | Appendix F

Sensitivity runs were performed using three scenarios:

• No seepage loss applied (5B)

• A seepage loss of 17 cfs and 3 cfs were applied in the dry and wet season, respectively (5B_SENS1)

• Half the daily loss of 17 cfs and 3 cfs were applied in the dry and wet season, respectively (5B_SENS2)

If a seepage assumption were to be included in the “with project” runs, it should be moderated because the base runs (or “without project” runs) do not include seepage. Instead of attempting to moderate the seepage values on a “pre” versus “post” differential basis, it would be clearer and more defensible to include the seepage assumption in the bases as well as in the “with project” runs.

Stage duration curves indicated that both 5BSENS1 and 5BSENS2 had a measurable effect on stages observed within the L-8 Reservoir. Both sensitivity runs resulted in lower stages and additional reservoir dry outs (Figure F-4). The stage duration curves indicate that seepage could impact reservoir stages by about five feet, which equates to about 4,500 acre-feet of volume in the existing 46,000 acre-feet reservoir.

Figure F-4. Sensitivity run comparison stage duration curve for the L-8 Reservoir.

Note: ft NGVD – feet National Geodetic Vertical Datum.


85 | Appendix F

Flow duration curves for Lainhart Dam illustrate no difference for high or moderate flows, but show some difference in the low flow (target zone) between 5B and 5BSENS1 (Figure F-5). Since impacts were observed at Lainhart Dam, it is expected impacts will occur in other areas including Grassy Waters Preserve and Loxahatchee Slough, even though those graphics were not processed or evaluated.

Figure F-5. Sensitivity run comparison flow duration curve for the Lainhart Dam.

In the dry season, for 5B, Lainhart Dam targets were met 95 percent of the time with the target not being met for 10 monthly events. In the dry season, for 5BSENS1, Lainhart Dam targets were met 90 percent of the time with the target not being met for 21 monthly events. In the dry season, for 5BSENS2, Lainhart Dam targets were met 92 percent of the time with the target not being met for 17 monthly events.

At the S-5A complex, which is located at the confluence of the L-8 and C-51 Canals, flows were reduced to less than 250 cfs when comparing the sensitivity runs to 5B, which is expected and would also translate into a slight reduction in flows at S-155 as flow leaves the L-8 basin and heads east to tide.

Applying a Seepage Assumption to Predictive Applications

The project team had extensive discussions on how to account for the differing seepage assumptions when comparing the existing or future without project condition to the future with project alternatives if additional seepage losses/gains are applied to the alternatives. Again, they considered several options.

One option considered was the development of a net additional seepage estimate based on the difference in flow rates observed in the M-Canal between the base and future with


86 | Appendix F

project conditions. This proved to be more complex than first considered. The data collected during the pilot test were used to develop a relationship between flow and stage resulting in a seepage assumption that would be representative of the dry season conditions observed during the pilot test, such as little to no rainfall (W. Lal, District, personal communication, May 13, 2011).

Since the pilot test was conducted during a severe drought, seepage values are representative of dry season conditions when losses may be the highest (i.e., worst-case scenario losses). Most measurements were taken on days without rain. Rain events may reduce seepage losses and introduce gains into the canal as well. One to three measurements were taken for each M-Canal reach to determine seepage. Additional measurements would add confidence to dry season estimates.

The pilot test carried out in March–April 2011 shows that the seepage leaving the M-Canal in Reach 1 was between 4 and 25 cfs as measured on three different days in March. The discharge leaving Reach 2 was between 30 and 70 cfs on three similar days in March (SFWMD 2011). These results are significant for the proposed project for two main reasons. These numbers show the volume of water leaving the reaches can be relatively large, and the numbers vary for reasons not well understood or physically explainable (W. Lal, District, personal communication, May 13, 2011). For example, the Reach 1 value of 4 cfs may have been influenced by a prior rainfall event, whereas the other two measurements may not have been influenced by rainfall.

The objective of a subsequent pilot test is to try to understand the seepage values. The difference/loss in discharge along the M-Canal could be attributed to several factors, such as unsteady flow conditions, storage in Grassy Waters Preserve, recharging of groundwater, evaporation or a combination of all these factors (SFWMD 2011). In addition, it was recommended that a further study of the groundwater levels and stages in nearby adjacent areas could be useful in understanding the differences in discharges (SFWMD 2011).

Another option considered was to rerun the 2000 existing conditions base and 2050 future without project base with updated seepage assumptions derived from MODFLOW river package leakage. After further discussion, it seemed that adding the same seepage assumption across the board for all model scenarios would likely have very little effect when comparing one scenario to another. The amount of effort necessary to revise and recalibrate the model, rerun the base models, and reprocess results seemed exorbitant compared to the minimal difference in outcome expected. It was also noted that during certain times throughout the period of record, seepage into, rather than out of, the system was occurring, further complicating seepage assumption development, quality control and model calibration.

Application of the seepage estimate based on the MODFLOW river package leakage to the future with project runs only and with no seepage assumption being included in the future without project runs was also considered. This option was not recommended because of the basic premise that the model runs should use similar assumptions.


87 | Appendix F

Finally, relating seepage to efficiency where seepage is based on some percent of flow was considered. No long-term trends or values were determined to substantiate the use of such a percentage value.

Additional Tools for Seepage Calculations

A number of additional tools or procedures are needed to calculate canal seepage in greater detail. A single model is unable to represent a fully integrated canal–aquifer system when the hydraulic specific conductance is relatively large. In order to represent the integration correctly the following needs to be done: (1) the canal system has to be simulated by solving the one-dimensional Saint Venant equations, (2) no discharge and head discontinuity conditions should exist at the canal–aquifer interface (Lal 2001), (3) the necessary spatial and temporal discretizations should be present for both groundwater and surface water models, and (4) enough field data must be available to calibrate such a model for the physical parameters (Lal 2006). Since such a coupled model does not exist for the project area, seepage calculations have to be based on simplified conditions.

Management Recommendation

Each seepage assumption methodology had inherent problems. Since the pilot test was conducted during a severe drought and was not representative of year-round conditions, no hard data were available to establish an assumption for wet season conditions where a seepage gain into the system would be expected. This may be viewed as testing the most extreme part of the design versus the general range of conditions, which is typically used for plan formulation modeling. At present, the draft CERP guidance memorandums do not give specifics on considering a worst-case scenario when formulating alternatives. The aforementioned options all had drawbacks that made it difficult to justify calculating the seepage off-line and including the assumption in the plan formulation modeling. Table F-1 shows the evaluation criteria involved in developing and applying a seepage assumption.

The USACE deferred to the District to make the initial recommendation regarding inclusion of a seepage assumption in the upcoming plan formulation modeling. The District recommended moving forward without incorporating seepage due to a lack of sufficient data to support a year-round seepage assumption. The USACE supported the recommendation. Both the District and USACE advised the project team to develop documentation to include in the project implementation report’s risk and uncertainty section and to memorialize the process and outcome. Additionally, the District emphasized that the seepage assumption shall be revisited for modeling purposes when more data are available and the range in seepage is better understood for year-round conditions. Since the plan formulation modeling is expected to be completed prior to the execution of a subsequent pilot test, a seepage assumption for the M-Canal will not be included in this phase of the CERP planning process. Other opportunities will arise during the planning process in the next one to two years where additional data, if available at that time, could be used for additional operational modeling.


88 | Appendix F

Table F-1. Evaluation criteria for seepage assumption.

Developing a Relationship Using Pilot Test Data

Applying Average Seepage Loss Based on

Model Output

Applying No Seepage Losses/Gains to the

M-Canal

Dry season correction of daily pumping

Dry season average to correct pumping

Dry and wet season average from modeled leakage

No application of additional seepage

introduced into model

Most risk-adverse (worst case scenario)

Moderately risk-adverse (averaging)

Minimally risk-adverse (averaging) No risk

Highest level of effort Moderate level of effort Minimal level of effort Lowest level of effort

Correction is applied on a daily basis

Correction is applied daily but the same

constant is applied to all runs; assumes all dry seasons are similar

Correction is applied daily but consists of a monthly pattern; assumes all dry

seasons are similar

No corrections are made to represent pumping

inefficiencies as a result of seepage

Captures variability in the dry season

Does not capture variability

Captures average seasonal variability, but not

extremes

Does not incorporate more uncertainty into

model by using an assumption

Tied to field test measurements

Loosely tied to field test measurements

Not tied to field test measurements; based on simulated results where

M-Canal has a fixed elevation

Losses and gains to system may be underestimated

Tests risky part of the design

Long-term averaging may not capture all

inefficiencies due to variability in the plan

Long-term averaging may not capture all

inefficiencies due to variability in the plan

Losses during extreme drought conditions

Without rain included as a variable,

overestimations are likely

Without rain included as a variable,

overestimations are likely

Rain was included as a variable and may moderate

seepage losses

Not including seepage loss/gains may

impact effective reservoir utilization

More time intensive Moderately time intensive Moderately time intensive Minimally time intensive

Requires executing each model

prediction twice

Does not require executing each model

prediction twice

Does not require executing each model

prediction twice

Extra modeling is not required

Applies only to the dry season; not applicable

to the wet season

Applies only to the dry season; not applicable to

the wet season

Monthly average is applied to dry and wet seasons Not applicable

Applies only to Reach 1 Applies only to Reach 1 Applies to Reaches 1,4 and 5 Not applicable

Requires re-executing base conditions



Does not require re-executing base

conditions; minimizes impact to the project

schedule

Conclusion

There is not sufficient information available to determine an estimate for seepage that the District and USACE both considered representative of year-round conditions and scientifically defensible for inclusion in the forthcoming modeling effort. The understanding of the physics at both local and regional scales of the current project is a challenge. Computer models developed for the regional scale are not intended to fully capture local effects (e.g., due to pumping) with the accuracy of required local-scale assessments. In finding a solution to this problem, it is necessary to obtain both stage and discharge measurements throughout the system during a field test involving critical operations. It is


89 | Appendix F

necessary to develop tools that can explain seepage at the necessary scale required for the project.

The amount of effort and time needed to determine a scientifically defensible seepage assumption exceeded the project schedule, with minimal anticipated effects to the relative comparisons of model output. The selection of the tentatively selected plan would not likely be affected by the seepage assumption, since the assumption would be applied equally to all options. However, it is recognized that during the selection of the tentatively selected plan, the project team should take into consideration the impact seepage will have on effective reservoir utilization, approximately in the order of magnitude of 4,500 acre-feet.

References

Ecology and Environment, Inc. 2010. Central and Southern Florida Project, Comprehensive Everglades Restoration Plan, North Palm Beach County - Part 1 Project, Draft Alternatives Formulation Briefing. Prepared for the United States Army Corps of Engineers, Jacksonville, FL, and South Florida Water Management District, West Palm Beach, FL. August 2010.

Giddings, J.B., L.L. Kuebler, J.I. Restrepo, K.A. Rodberg, A.M. Montoya and H.A. Radin. 2006. Draft Lower East Coast Subregional MODFLOW Model Documentation. South Florida Water Management District, West Palm Beach, FL.

Hall, A. 2011. Memorandum: Modeling of L-8 Reservoir for Pump and Structure Design. Submitted to the South Florida Water Management District, West Palm Beach, FL. May 16, 2011

Kuebler, L.L. and A.M. Montoya. 2010. Model Documentation for the Application of the Northern Palm Beach County Version of the Lower East Coast Subregional Model (LECsR-NP). South Florida Water Management District, West Palm Beach, FL.

Lal, A.M.W. 2001 Modification of canal flow due to stream-aquifer interaction. ASCE Journal of Hydraulic Engineering 127(7):567–567.

Lal, A.M.W. 2006. Determination of multiple aquifer parameters using generated water level disturbances. Water Resources Research 42:1–13.

Montoya, A.M., L.L. Kuebler, H.A. Radin and V. Mullen. 2010. Model Implementation of the Northern Palm Beach County Version of the Lower East Coast Subregional Model (LECsR-NP). South Florida Water Management District, West Palm Beach, FL.

Mullen, V.M., L.L. Kuebler, H.A. Radin and A.M. Montoya. 2010. Model Documentation for the Application of the Northern Palm Beach County Version of the Lower East Coast Subregional Model (LECsR-NP), South Florida Water Management District, West Palm Beach, FL.

Panigrahi, B. 2011. Draft Technical Memorandum: North Palm Beach Pump Station Design, Frequency Analyses of Flow and Stage at L-8 Reservoir. South Florida Water Management District, West Palm Beach, FL. May 11, 2011.


90 | Appendix F

SFWMD. 2011. Draft: Assessment of Reachwise Differences in Discharge in M-Canal. South Florida Water Management District, West Palm Beach, FL.

Swift, D. 2011. Update on Loxahatchee River Watershed Restoration Project - Operational Testing. Governing Board Workshop, April 13, 2011. South Florida Water Management District, West Palm Beach, FL.


91 | Appendix G

Appendix G WATER BUDGET MODEL

Water Budget Model Formulation

Since flow to Grassy Waters Preserve is not measured directly, the water budget was developed in two steps: (1) calculation of the water budget for the M-Canal to simulate flow at the Control 3 structure, and (2) the water budget for Grassy Waters Preserve using the estimated Control 3 flow. In mathematical terms, the water budget for M-Canal can be written as Equation G-1.

∆t [I CS2 – (OCS3+WCJ +SM)]= 0 [G-1]

where,

∆t = time step (day) I CS2 = inflow at Control 2 (acre-feet per day [ac-ft/d]) OCS3 = outflow at Control 3 (ac-ft/d) WCJ = Callery Judge Grove withdrawals (ac-ft/d) SM = seepage of M-Canal (ac-ft/d)

Similarly, the water budget for Grassy Waters Preserve can be written as Equation G-2.

∆t [(ICS3 + R) – (ET + OG-161 + OCS4 + SGWP)] = ∆V [G-2]

where,

∆t = time step (day) ICS3 = inflow at Control 3 (ac-ft/d) R = rainfall (ac-ft/d) ET = evapotranspiration (ac-ft/d) OG-161 = outflow at G-161 (ac-ft/d) OCS4 = outflow at Control 4 (ac-ft/d) SGWP = seepage of Grassy Waters Preserve (ac-ft/d) ∆V = change of water volume stored in Grassy Waters Preserve (acre-feet [ac-ft])

Seepage was estimated using Equation G-3.

S = k (h – h’) [G-3]

where,

S = seepage rate (ac-ft/d) h = stages in M-Canal or Grassy Waters Preserve (feet National Geodetic Vertical

Datum of 1929 [ft NGVD29]) h’ = stages of the surrounding area (ft NGVD29) k = leakance factor (acre-feet per day per foot [ac-ft/d/ft]).

The leakance factor (k) is a composite factor of the hydraulic specific conductance of the soil and the size and shape of the M-Canal or Grassy Waters Preserve. This is the only


92 | Appendix G

calibration parameter that was adjusted to close the water budget. Note that k values for the M-Canal and Grassy Waters Preserve were different due to their unique geometry and soil characteristics.

To estimate water storage in Grassy Waters Preserve, a stage storage relationship was developed based on information reported in the West Palm Beach Water Catchment Area Water Conservation Study: Technical Memorandum 2 (CH2MHILL et al. 1995). A surface area of 11,067 acres was used for Grassy Waters Preserve. Total water storage was partitioned into ponded surface water and drainable water in the soil column. A 30 percent drainable porosity was assumed for Grassy Waters Preserve soils to compute groundwater storage. This was based on soil types in this region, which are a mixture of fine sand and muck. The stage storage relationship was obtained using regression analyses, taking a similar form of that developed by CH2MHILL et al. (1995). The analysis used Equation G-4.

V = 1110.3 ∆H2 + 3797.2∆H [G-4]

where,

V = total available storage (ac-ft) ∆H = water depth above reference elevation (feet)

The reference elevation was set at 15.7 ft NGVD29 at which the available storage becomes zero (CH2MHILL et al. 1995). The coefficient of regression (R2) of Equation G-4 is 0.99.

Data Sources The City of West Palm Beach operated Controls 2 and 4 during the pilot test. Daily flows at Controls 2 and 4, and stages in the M-Canal were obtained from daily reports provided by the City of West Palm Beach. Daily withdrawals by Callery Judge Grove were obtained from the Seminole Improvement District Supplemental Report to the South Florida Water Management District (SFWMD or District) regarding water use during 2011 Phase 2 water restrictions. Headwater stage, representing stages in Grassy Waters Preserve, and flows through G-161 were retrieved from DBHYDRO. Stage data of groundwater wells in the surrounding area were also retrieved from DBHYDRO, compared and evaluated. Stage in Well PGA-W05 was used as the h’ term in Equation G-3 to estimate seepage. The District NEXRAD rainfall data for Grassy Waters Preserve (as an ArcHydro basin) were compared with rainfall collected by the City of West Palm Beach’s rain gauge at the Grassy Waters Preserve nature center. The NEXRAD rainfall was slightly less than that collected by the rain gauge during the pilot test, possibly due to the spatial viability of rainfall. The NEXRAD data were used for the Grassy Waters Preserve water budget calculation for its spatial coverage. Evapotranspiration was estimated using the radiation method developed for South Florida’s marsh and open water conditions (Abtew 1996). All of the source data used in the water budget are provided in Appendix D.

Water Budget Model Calibration

Based on the available data, a time step, spreadsheet based water budget model was developed using the March 1 to May 13, 2011 time period. Extension of the calculation to May 13 was used for model verification. The period of simulation was limited by the lack of daily withdrawal data for Callery Judge Grove.


93 | Appendix G

For the M-Canal water budget, the model was calibrated so that flows at Control 3 matched with stream gauge values obtained during the pilot test. This was accomplished by adjusting the leakance factor (k) in Equation G-3 to close the water budget of Equation G-1. The final adjusted seepage rate for M-Canal averaged about 15 cubic feet per second (cfs; equivalent to 30 ac-ft/d) during the pilot test, and varied depending upon the head difference between the M-Canal and the nearby groundwater well. Similar seepage values were noted in previous modeling efforts (Laura Kuebler, District, personal communication). Figure G-2 shows the daily pumping rate of Control 2 and calculated flows at Control 3 in comparison to stream gauge values. The calculated flows at Control 3 agreed well with stream gauge values on March 17, 22 and 30. However, flow gauging values on March 7 and 8 were about 40 cfs lower than the calculated flow at Control 3. A discrepancy of similar magnitude existed for Control 2 pump flows on March 7, suggesting that an error associated with the tailwater stage of Control 2 might have resulted in the discrepancy.

Figure G-2. Daily pumping rate of Control 2 and calculated flows at Control 3 compared with stream gauge values.

Calculated flows at Control 3 were used to develop the Grassy Waters Preserve water budget. To validate the water budget, daily water storage volume calculated using Equations G-2 and G-4 were compared and contrasted. The leakance factor (k) in Equation G-3 was adjusted so the difference between Grassy Waters Preserve water storage calculated using Equations G-2 and G-4 was minimal. The calibrated value of the leakance factor was 31 ac-ft/d/ft, very close to the 30 ac-ft/d/ft reported by CH2MHILL et al. (1995). To illustrate the calibration result, the daily storage calculated with Equation G-2 was used to back calculate the daily stage using Equation G-4. The simulated stage data were


94 | Appendix G

compared with the measured stage data (G-161 headwater stage) as shown in Figure G-3. The simulated stage matched well with the measured stage (R2 = 0.97). Slight discrepancies between the simulated and measured stage existed after the pilot test partly because the G-161 stage recorder, located in the downstream area of Grassy Waters Preserve, did not detect the immediate impact of the fluctuation in Control 3 inflow, whereas the water budget model always responded to changes in inflows or outflows on the same day. This was readily apparent on days with significant rainfall (Figure G-3).

Figure G-3. Grassy Waters Preserve stage simulated using the water budget model compared to

stage measured at G-161 with rainfall plotted to show its effect on stage.

References

Abtew, W. 1996. Evapotranspiration measurements and modeling for three wetland systems in South Florida. Journal of the American Water Resources Association 32:465-473.

CH2MHILL, Mock Roos, and LBFH. 1995. West Palm Beach Water Catchment Area Water Conservation Study: Technical Memorandum 2. Provided by CH2MHILL, Mock Roos and LBFH under contract C-6113 to the South Florida Water Management District. West Palm Beach, FL.

l-8 reservoir pilot test technical document

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