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Contra Costa County, California Hydrologic Analyses

FEMA Region IX

Hydrologic Analyses

Contra Costa County, California CONTRACT NUMBER: HSFEHQ‐09‐D‐0368

TASK ORDER HSFE09‐09‐J‐0001

October 2011


Document History

Document Location

Location

Z:\Risk MAP Production\REGION 9\CALIFORNIA\CONTRA COSTA COUNTY\09‐09‐3059S\Hydrology

Revision History

Version Number Version Date Summary of Changes Team/Author

01 04/11/2011 1st Draft K. Labuhn

02 10/1/2011

Client Distribution

Name Title/Organization Location

Eric Simmons FEMA MIP, see Appendix C. http://www.bakeraecom.com/index.php/california/contra-costa-county/

May 2011 i


Table of Contents

1. TASK SUMMARY ................................................................................................................................................... 1

1.1. INTRODUCTION ............................................................................................................................................. 1 1.2. SCOPE OF WORK ........................................................................................................................................... 1 1.3. UPDATES TO SCOPE OF WORK ...................................................................................................................... 1

2. WATERSHED LOCATIONS AND DESCRIPTIONS ................................................................................... 1

2.1. BRUSHY CREEK ............................................................................................................................................ 1 2.2. FRISK CREEK ................................................................................................................................................ 1 2.3. KELLOGG CREEK .......................................................................................................................................... 2 2.4. MT. DIABLO CREEK ...................................................................................................................................... 3 2.5. DEM PREPROCESSING .................................................................................................................................. 4 2.6. HEC-GEOHMS SUBBASIN DELINEATION ..................................................................................................... 5 2.7. HEC-HMS MODEL SETUP ............................................................................................................................ 5 2.7.1. SOIL MOISTURE ACCOUNTING LOSS METHOD ......................................................................................... 5 2.7.2. USER SPECIFIED S-CURVE TRANSFORM METHOD .................................................................................... 6 2.7.3. BASEFLOW METHOD ................................................................................................................................ 7 2.7.4. RESERVOIRS ............................................................................................................................................. 7 2.7.5. REACHES .................................................................................................................................................. 7 2.7.6. RAINFALL DATA AND DISTRIBUTION ....................................................................................................... 7 2.8. MARSH CREEK .............................................................................................................................................. 8

3. RESULTS ............................................................................................................................................................ 9

3.1. COMPARISON TO PREVIOUS FLOW CALCULATIONS .................................................................................... 10

Appendices Appendix A Hydrologic Analysis Appendices A‐1 – Landuse and Infiltration Rate Calculations A‐2 – Lag Time Calculations

A‐3 – Reservoir Information A‐4 – Reach Information Appendix B TSDN Documents B‐1 – Deliverables Checklist B‐2 – Contact Report List B‐3 – Hydrologic Analyses Index B‐4 – Certification of Compliance Appendix C C‐1 ‐ Hydrologic Analyses QA/QC Reviews Appendix D Digital Data on the MIP

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1. Task Summary

1.1. Introduction BakerAECOM has completed the Hydrologic Analyses activities in accordance with Task Order HSFE09‐09‐J‐0001 for Contra Costa County, California under Contract No. HSFEHQ‐09‐D‐0368. The project location and a detailed map of the county are shown in Figure 1.

1.2. Scope of Work

Scope: The primary tasks are to conduct detailed hydrologic analyses of four streams (Brushy, Frisk, Kellogg and Mt. Diablo Creeks), update previous model for Marsh Creek and to perform QC of the study currently being conducted by the county for Wildcat and San Pablo Creeks. Specific tasks will include:

Compare discharges calculated by the county against results of the HEC‐HMS model for Brushy, Frisk, Mt. Diablo and Kellogg Creeks

Update the HEC‐HMS model for Marsh Creek to reflect existing landuse conditions (based on the 2008 aerial photos provided by the county) and edit the storage data on Sand Creek to reflect existing conditions

Review the hydrologic analysis conducted by the county for Wildcat and San Pablo Creeks as part of the levee certification process

Standards: Hydrologic Data Development work shall be performed in accordance with the standards specified in Section 4 ‐ Standards. The DCS must be met for this deliverable to be acceptable.

Deliverables: BakerAECOM shall make the products available to FEMA and any other deliverables associated with this activity that are defined in the updated Appendix M (Data Capture Standards) by uploading the digital data to the MIP.

1.3. Updates to Scope of Work The hydrologic analysis submitted by Contra Costa County for Wildcat and San Pablo Creeks is not currently included in this document.

July 2011 1


Figure 1. Scoping Map

July 2011 1


2. Watershed Locations and Descriptions 2.1. Brushy Creek Figure 2 below shows the Brushy Creek watershed. The creek begins in the Canada de los Vaqueros hills near the border of Contra Costa and Alameda Counties and flows in a generally north to northeast direction until its confluence with Clifton Court Forebay. The watershed is approximately 16.4 square miles and is composed mostly of public lands/open space, agricultural lands and some low density residential development. The Byron Airport is partially located within the Brushy Creek watershed.

Figure 2. Brushy Creek Watershed

2.2. Frisk Creek Figure 3 below shows the Frisk Creek watershed. The creek begins in the Canada de los Vaqueros hills and flows in a generally north to northeast direction until it reach the east side of Byron Highway where it turns and flows due north to its confluence with Discovery Bay. The watershed is approximately 12.2 square miles and is composed mostly of public lands/open space, agricultural lands and some low density residential development. The community of Byron is located in the Frisk Creek watershed.

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Figure 3. Frisk Creek Watershed

2.3. Kellogg Creek Figure 4 below shows the Kellogg Creek watershed. The Los Vaqueros Reservoir is a drinking water storage reservoir that also captures the upstream flows from Kellogg Creek. Kellogg Creek flows in a generally northern direction until just south of Marsh Creek Road (Highway 4) where it turns to the south and then flows east through a manmade watercourse to its confluence with Discovery Bay. The watershed is approximately 32.2 square miles and is composed mostly of public lands/open space, agricultural lands and some low density residential development.

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Figure 4. Kellogg Creek Watershed

2.4. Mt. Diablo Creek

Mt. Diablo Creek starts in the Mount Diablo State Park and flows to the northwest to its confluence with Suisun Bay. The watershed is located in the City of Concord and Contra Costa County and encompasses land that was part of the former Concord Naval Weapons Base. That base has been decommissioned and will eventually become property of the City of Concord and the county. The watershed is 32.7 square miles and consists of residential and commercial lands in the headwaters and open space on the former Concord Naval Weapons Base lands. Mt. Diablo Creek was studied previously by FEMA but that study ended at Bailey Road and did not show any flood hazards on the Naval Weapons Base. This study is intended to determine the flood hazards downstream of Kirker Pass Road to Mt. Diablo Creek’s confluence with Suisun Bay.

July 2011 4


Figure 5. Mt. Diablo Creek Watershed

2.5. DEM Preprocessing

Since Brushy, Frisk and Kellogg Creeks are adjacent to one another the tile digital elevation models

(DEMs) provided by Contra Costa County were mosaiced together to create one DEM to use for the

analysis. There were some areas where the tiles did not meet each other and there were other small

areas of missing data. In order to “fill in” the missing elevation data from some grid cells the raster

calculator focalmean function was used. The focalmean function looks at the elevation data in the

cells surrounding the empty cell and calculates a mean value for that empty cell. In this case the

focalmean statement was written to look at a 3 cell by 3 cell rectangle surrounding the empty cell

and calculate the mean. This filled in the necessary missing data in the DEM and could then be used

for further analysis. A similar process was used to construct a DEM for the Mt. Diablo Creek

watershed.

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2.6. HEC-GeoHMS Subbasin Delineation

Once the DEMs were constructed the next step was to delineate the subbasins for each creek. In

order to do this the ArcGIS extension HEC‐GeoHMS was used. The standard process for HEC‐GeoHMS

was followed including performing a “fill” operation to fill in the sink in the DEMs and then the tools

were run to define the streams and determine the subbasins. Once the draft streams and subbasins

were determined a manual review of the stream locations and subbasins was completed and a

number of edits were made to correct the automated process. In particular, the DEMs did not always

locate the streams correctly as shown on the provided aerial photos so these were corrected and the

subbasins edited manual as needed. Some of the smaller subbasins were combined and a few were

split at points were flows were needed.

2.7. HEC-HMS Model Setup

A number of discussions were held with Contra Costa County to determine which loss and transform

methods would be most appropriate for use in the county. Typically FEMA will use the NRCS curve

number and unit hydrograph method but Contra Costa County has a large library of data concerning

the hydrology of the county. They have provided guidance regarding methods that have been used

previously in the county to calculate flows. A review of these methods (Reference 1) shows that they

are appropriate for in this project. The loss method used is the Soil Moisture Accounting method and

the transform method is the User Specific S‐curve. The necessary inputs for these methods are land

use and Manning’s n data.

The only exception to this methodology was for subbasin 1 in the Kellogg Creek watershed. Subbasin

1 is the direct drainage area to the Los Vaqueros Reservoir and for this subbasin the NRCS methods

were used. The curve number and lag time were obtained from the HEC‐1 model completed for a

previous LOMR submittal (case number 03‐09‐0909P).

Additionally, Mt. Diablo Creek was previously studied by FEMA and there are an effective discharge

values available, with the most downstream available discharge at Bailey Road. In order to determine

if this flow was still reasonable two models were created for Mt. Diablo Creek. The first followed the

methods described in this section and the section treated the flow upstream of Bailey Road as a

constant source input using the effective flow.

2.7.1. Soil Moisture Accounting Loss Method

The Soil Moisture Accounting loss method in HEC‐HMS allows for a number of inputs including

storage in different units such as canopy, surface, soil and groundwater storage. For flood events the

only inputs that would have an appreciable impact on flows are the infiltration rate and soil storage

amount (or initial infiltration loss). The County provided BakerAECOM with a conversion chart that

links landuse with minimum, average and maximum infiltration rates. For the Brushy, Frisk, Kellogg

and Mt. Diablo Creek watersheds the landuse shapefile was intersected with the subbasin shapefile

to find the landuse by subbasin. Then area weighted average infiltration rate was calculated based

on the average values provided by the County. Appendix A‐1 provides tables of this data. The initial

infiltration loss was set to a standard 0.25 inches which comes from the County’s standard.

July 2011 6


Contra Costa County provided BakerAECOM with a landuse shapefile names GPLU_Edited. As

discussed with the County, this is a shapefile of landuse designations that come from the Contra Costa

County general plan and also from information provided by the incorporated cities in the County.

This shapefile is of the zoned/planned landuse (i.e., future conditions), not necessarily how the land is

currently being used. Since FEMA models existing, not future conditions, the landuse categories were

reviewed against the aerial photos provided by the County to determine if the planned landuse

compared to the current landuse. In the Frisk and Kellogg Creek watersheds the planned landuse

seemed to correspond to the current landuse and no changes were made. The Brushy Creek

watershed extends into Alameda County to the south. A review of aerial photos in Alameda County

shows no appreciable differences from Contra Costa County so the landuse type associated with

subbasins in the Contra Costa County were extended into the subbasins in Alameda County. In the

Mt. Diablo Creek watershed the area downstream of Bailey Road was reviewed and it was found that

near the Mallard Reservoir there were some areas that are designated as commercial but currently

appear to be open space. Additionally, there were a few areas that appeared to be dense residential

but were planned as low density residential. Edits were made to the landuse as necessary. Appendix

A‐1 provides maps and tables showing the breakdown of landuse for each watershed.

2.7.2. User Specified S-Curve Transform Method

Contra Costa County uses an S‐curve that was developed in a 1971 study of Walnut Creek by the U.S.

Army Corps of Engineers. This is now the Contra Costa County Flood Control District standard. This

curve was reviewed by BakerAECOM and found to be appropriate for use in this study. The curve is

input as a percentage curve in HEC‐HMS as a table of paired data. The other parameter needed is the

lag time. The Flood Control District uses the following formula to calculate lag time:

24 .

.

Where: Tlag Elapsed time from the centroid (or 50‐percent of volume) of the effective rainfall to the

centroid (or 50‐percent of volume) of the resulting runoff (hours) N weighted watershed Manning’s n coefficient L Length of the longest watercourse (miles) Lca Length along that drainage path from a point opposite the centroid of the watershed to the

outlet point (miles) S Overall slope of the main watercourse (feet/mile)

The length of the stream reaches was calculated using ArcGIS. ArcGIS was also used to find the

centroid of each subbasin and a line was then drawn to intersect with the stream centerline. The

distance between that point to the outlet, also calculated using ArcGIS, is Lca. The slope was found

from creating a contour map of the DEMs and reading the upstream and downstream elevations.

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In addition to infiltration rates the County also provided a conversion table between landuse and

Manning’s n value. Similar to the infiltration rate calculations the area weighted average Manning’s

n value was calculated for each subbasin. Appendix A‐2 contains maps and tables of the data used

for these calculations.

2.7.3. Baseflow Method

Baseflow is typically not included in calculations of flood events so the baseflow method was set to

none for the Brushy, Frisk, Kellogg and Mt. Diablo Creek models.

2.7.4. Reservoirs

There are two reservoirs in the studied watersheds. The first is the Los Vaqueros water supply

reservoir in the headwaters of Kellogg Creek. The water in this reservoir is delivered and withdrawn

by the canal system. This reservoir was previously modeled as part of a Letter of Map Revision case

number 03‐09‐0909P. The storage‐elevation and outlet information was taken from the HEC‐1 model

and input into the HEC‐HMS model (see Appendix A‐3).

The other reservoir of interest is Mallard Reservoir in the Mt. Diablo Creek watershed. Discussions

with the water district (Reference 2) revealed that there are no outlet structures for this reservoir to

the creek so it is not included in the modeling effort for Mt. Diablo Creek.

2.7.5. Reaches

The Muskingum‐Cunge method was used to route the flood flows through the watershed. The length

and slope were calculated as described in Section 2.5.2. The Manning’s n used was based on aerial

photos of the area and guidance from Contra Costa County. The bottom width and side slopes were

estimated from the two foot topographic data. Appendix A‐4 contains tables of the input data.

2.7.6. Rainfall Data and Distribution

The SCS method is the rainfall method most commonly used by FEMA. The two parameters

necessary are the rainfall distribution curve type (I, IA, II or III) and the storm depth in inches.

According to the figures in Appendix B of the NRCS publication “Urban Hydrology for Small

Watersheds” the boundary between the Type I and IA distributions falls approximately through

Contra Costa County. The County has reviewed the distributions and compared them to historical

analyses done in the county. They have concluded that the Type I distribution is the most

appropriate for the County and BakerAECOM agree. The 24‐hour rainfall depths were estimated at a

midpoint in the watershed and assumed to be an average for the entire watershed. In April 2011 the

National Oceanic and Atmospheric Administration (NOAA) released a new analysis of rainfall depths

in the western United States that supersedes the data in their publication Atlas 2. Rainfall frequency

depths can now be obtained via latitude and longitude from NOAA’s website at

http://hdsc.nws.noaa.gov/hdsc/pfds/.

Table 1 below lists the locations and precipitation frequency estimates obtained from the NOAA

website and used in the analysis.

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Table 1. Rainfall Frequency Depth Estimates

Stream Location

Latitude/longitude

10% ‐ 24‐Hour

Storm Depth

(in)

2% ‐ 24‐Hour

Storm Depth

(in)

1% ‐ 24‐Hour

Storm Depth

(in)

0.2% ‐ 24‐Hour

Storm Depth

(in)

Brushy Creek At Vasco Road

37.819902

‐121.655488

2.53 3.58 4.07 5.31

Frisk Creek At Vasco Road

37.851772

‐121.648243

2.47 3.49 3.96 5.15

Kellogg Creek At Walnut

Boulevard

37.871930

‐121.699067

2.87 4.02 4.53 5.76

Mt. Diablo

Creek

At Bailey Road

37.971826

‐121.969951

3.33 4.65 5.25 6.70

Marsh Creek At Union Pacific

Railroad Crossing

37.942633

‐121.706373

2.58 3.67 4.18 5.51

2.8. Marsh Creek

Contra Costa County provided Baker/AECOM with a HEC‐HMS model of Marsh Creek but it was

completed using future landuse conditions (expected maximum build out) and expansions to the Sand

Creek retention basin (Reference 3).

Baker/AECOM compared the planned landuse shapefile discussed above in Section 2.5.1 to the aerial

photos provided and it was found that there were many locations where the residential development

currently built did not match the planned landuse density. For example, there were areas that were

planned to be low density residential but the aerial photos showed that high density residential

development had already occurred. Numerous changes were made to the land use so that it

conformed to the current conditions in the watershed, especially in the residential areas. This

resulted in changes to the infiltration rates and Manning’s n values as compared to the model

provided by the County. Appendices A‐1 and A‐2 provide further details regarding the changes to the

landuse, infiltration rates, and Manning’s n values.

Baker/AECOM worked closely with the County to modify the elevation‐storage relationship for the

Sand Creek retention basin using the submitted DEM data and GIS software. Additionally, the County

provided original construction drawings for the basin to determine the outlet structure geometry and

July 2011 9


elevation. Appendix A‐3 provides further details regarding the elevation‐storage calculations and the

data regarding the outlets to the basin.

Additionally, changes were made to the elevation‐storage, storage‐discharge curves for some of the

reservoirs in the model, specifically, the Vinyards North and South Reservoirs, Deer Creek Basin, the

Fairview Basin, the Freedom Basin, and the Laurel Basin. The changes were made based on a

spreadsheet of basin information provided by the county, the DEM data for the Marsh Creek area and

best engineering judgment to extrapolate data points from the submitted data. Appendix A‐3 has

further information regarding the changes made to each reservoir.

There is one area in the Marsh Creek watershed, noted as Drainage Area 52D that was included in

the submitted HEC‐HMS model but was ultimately not modeled with HEC‐HMS due to the

complexity of the retention pond hydraulics. This area was modeled using EPASWMM and the

County is working to submit the model to BakerAECOM so that that it can be run for the FEMA

storm events. Due to the size of the retention ponds it is not expected that these flows will be

significant portion of the flow to Marsh Creek but they should be included to document the worst

case scenario expected. As soon as the model is received this report will be updated to include

those flows.

3. Results The results of the HEC‐HMS modeling are listed below in Table 2 and Table 3.

Table 2. HEC‐HMS Peak Flows at Junctions for Brushy, Frisk, Kellogg and Mt. Diablo Creeks Flooding Source and Junction Number

Drainage Area

(square miles)

Peak Discharges (cfs)

10% Annual Chance Flood



0.2% Annual Chance Flood

Brushy Creek

1 7.027 908.8 1,933.5 2,404.2 3,588.7

2 8.380 1,051.6 2,268.6 2,830.3 4,247.3

3 8.853 1,063.4 2,299.0 2,870.0 4,311.1

4 10.258 1,228.1 2,691.2 3,370.5 5,088.8

5 14.747 1,421.3 3,162.1 3,981.2 6,097.9

Outlet 16.395 1,418.5 3,190.4 4,027.9 6,203.4

Frisk Creek

1 2.635 300.5 651.0 811.9 1,218.9

2 5.585 545.5 1,228.0 1,546.6 2,361.5

3 6.438 587.4 1,356.1 1,716.2 2,639.0

4 2.284 199.6 436.3 545.6 826.4

5 11.364 682.1 1,737.6 2,248.7 3,602.8

Outlet 12.161 498.5 1,430.2 1,899.5 3,175.9

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Flooding Source and Junction Number

Drainage Area

(square miles)






Kellogg Creek

1 20.359 417.3 793.5 954.5 1,339.3

2 21.829 676.2 1,315.3 1,591.1 2,250.2

3 25.782 1,090.8 2,235.0 2,739.7 3,963.5

4 27.427 1,164.0 2,465.2 3,051.0 4,485.9

5 28.426 1,137.6 2,466.5 3,070.1 4,592.5

6 30.703 1,142.9 2,560.3 3,210.5 4,882.8

7 31.975 1,163.6 2,644.9 3,333.3 5,108.4

Outlet 32.214 1,152.9 2,626.1 3,311.2 5,083.6

Mt. Diablo Creek

Effective Flow 21.832 3,670.0 5,670.0 6,350.0 7,760.0

2 23.080 4,294.3 6,709.7 7,566.8 9,380.6

3 24.210 4,895.2 7,759.3 8,799.9 11,028.4

4 25.209 5,816.2 9,498.2 10,909.4 13,974.6

5 28.058 6,298.8 10,376.9 11,963.1 15,432.5

6 29.918 6,495.9 10,787.5 12,488.7 16,232.8

Outlet 29.943 6,319.5 10,476.9 12,134.1 15,787.2

Table 3. Results of HEC‐HMS Modeling for Marsh Creek at Effective Locations and Road Crossings

Location Drainage

Area (square miles)






At Concord Boulevard

52.674 498.9 570.9 603.9 780.7

At Balfour Road 58.221 918.8 1,365.5 1,568.4 2,117.4

At Central Avenue 65.049 1,169.6 1,755.0 2,017.5 2,699.6

At Union Pacific Railroad

81.010 1,721.4 2,751.2 3,678.8 6,204.2

At Delta Road 85.735 2,202.6 3,703.6 4,398.1 6,610.9

At Santa Fe Railroad 88.984 2,476.2 4,215.0 5,029.1 7,209.4

3.1. Comparison to Previous Flow Calculations

The Contra Costa County Flood Control District provided Baker/AECOM with some flow estimates for Frisk, Brushy and Kellogg Creeks and there are flows published for Marsh Creek in the effective FIS. Table 4 below compares the new HEC-HMS flows to those previously calculated. The comparison locations were not exact for Brushy Creek because the Flood Control District calculated the flows to the Southern Pacific Railroad but the HEC-HMS model was not setup to report the flows at that point, instead the flows from the next upstream junction are reported below.

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In 2002, a Letter of Map Revision (LOMR) was submitted that included modeling of Kellogg Creek with and without the Los Vaqueros Reservoir in order to revise the floodplain at the downstream end of Kellogg Creek. That LOMR was approved and the modeling was obtained for review in this study. That LOMR only calculated the 1% annual chance flood discharge and that information is listed below.

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Table 4. Comparison of HEC-HMS Discharges to Previously Calculated Discharges

Flooding Source and Location

HEC‐HMS Peak Discharges (cfs)

Location Previously Calculated Peak Discharges (cfs)









Brushy Creek

Upstream of Byron Hot Springs

1,447 3,195 4,017 6,147 At the Southern Pacific Railway

1,480 2,580 2,950 N/A

Frisk Creek

At the Southern Pacific Railway

593 1,378 1,741 2,661 At the Southern Pacific Railway

660 1,170 1,310 N/A

Kellogg Creek

At the Southern Pacific Railway

1,097 2,474 3,108 4,736 At the Southern Pacific Railway

N/A N/A 1,609 N/A

Marsh Creek

At Balfour Road 919 1,366 1,568 2,117 At Balfour Road 890 1,900 2,500 5,100

At Union Pacific Railroad

1,721 2,751 3,679 6,204 At Union Pacific Railroad

2,100 4,200 5,200 8,300

At Santa Fe Railroad

2,476 4,215 5,029 7,209 At Santa Fe Railroad

2,300 4,000* 4,000* 4,000*

*the effective FIS notes that the 2, 1, and 0.2% annual chance flows are reduced due to overbank spills and non‐returning flows

July 2011 13


Since the 1% annual chance flows for Kellogg Creek have increased significantly from the values

calculated in the 2002 LOMR, the inputs for the LOMR HEC‐1 model were compared to the inputs to

the HEC‐HMS model to determine potential explanations. The first difference between the two

models was the precipitation values used. The HEC‐1 model used different precipitation values for

different subbasins, starting with 4.8 inches in the headwater subbasin and ending with 3.4 inches at

the outlet. The HEC‐HMS model used a constant precipitation value of 4.53 inches for all subbasins.

Additionally, the subbasins in the HEC‐1 model used the SCS’s curve number and unit hydrograph

methods while the HEC‐HMS model used the methods recommended by Contra Costa County (the

soil moisture accounting method and the County derived S‐Curve). This has resulted in large

differences in flows from subbasins of similar size. Table 5 below shows some comparisons between

subbasin size and calculated flow rate. These differences appear to explain the change in flows

between the LOMR HEC‐1 and HEC‐HMS models.

Table 5. Comparisons of 1% Annual Chance Flows at Kellogg Creek Subbasins

between HEC‐1 and HEC‐HMS

HEC‐1 HEC‐HMS

Subbasin

Number

Subbasin Size

(sq miles)

Flow (cfs) Subbasin

Number

Subbasin Size

(sq miles)

Flow (cfs)

2007 0.82 56 5 0.821 396.4

2005 1.32 107 7 1.427 361.1

2004 0.92 128 9 0.999 656.7

The currently effective FIS for Marsh Creek lists flows at 3 locations and those values are also listed in

Table 4. The effective flows were calculated using the unit hydrograph method where flood

hydrographs were developed for the upper reaches of Marsh Creek, routed through the Marsh Creek

flood‐control reservoir and then summed with hydrographs developed for lower reaches. For the

10% annual chance event the newly calculated flows are comparable to the effective flows. For the

2% annual chance event the flows at Balfour Road have been reduced by about 30%. This is likely

due to the five detention ponds and the Marsh Creek Reservoir that store approximately 1,893 acre‐

feet during the 2% annual chance event. Additionally, as discussed above for Kellogg Creek, the

rainfall data has been updated which could result in changes to the flow rates. Similarly, at the

Union Pacific Railroad the 2% annual chance flows have been reduced by about 35%. This is likely

due to additional detention ponds storing approximately 453 acre‐feet during the 2% annual chance

event. For the 1% annual chance event the flows have been reduced by 48 and 39%, respectively, at

Balfour Road and the Union Pacific Railroad. For the 0.2% annual chance event the flows have been

reduced by 59 and 25%, respectively, at Balfour Road and the Union Pacific Railroad due to detention

pond storage. At the Santa Fe Railroad the effective discharges have been reduced due to overbank

spills and non‐returning flows. Since the new modeling accounts for overbanks spills and non‐

returning flows have been removed, the new flows calculated cannot be compared to the effective

flows for the 2% annual chance event.

July 2011 14


References

1. Contra Costa County Flood Control and Water Conservation District. “Verification of the

District’s Standards”. Draft December 2010.

2. Personal Communication (phone call). Contra Costa Water District (Mark Seedall). April 19,

2011.

3. Contra Costa County Flood Control and Water Conservation District. “Marsh Creek Hydrology

Report GeoHMS and HEC‐HMS Analysis”. May 10, 2010. (and accompanying HEC‐HMS model)

July 2011 15


Appendix A‐1

Landuse and Infiltration Rate Calculations

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July 2011 17


Table A1‐1. Brushy Creek Landuse Area (square miles) by Subbasin

Subbasin Number

Agricultural Land Delta Recreation Open Space Parks and Recreation

Public/Semi‐Public Water Watershed*

1 1.30 ‐ ‐ ‐ ‐ ‐ 0.08

2 2.44 ‐ ‐ ‐ ‐ ‐ ‐

3 1.21 ‐ ‐ 0.57 ‐ ‐ ‐

4 1.42 ‐ ‐ ‐ ‐ ‐ ‐

5 2.07 ‐ ‐ 0.29 ‐ ‐ 0.28

6 0.57 ‐ ‐ 0.22 ‐ ‐ ‐

7 0.45 ‐ ‐ 0.11 ‐ ‐ ‐

8 1.48 ‐ ‐ ‐ ‐ ‐ ‐

9 0.15 ‐ ‐ ‐ ‐ ‐ ‐

10 0.99 ‐ 0.05 ‐ 0.23 ‐ 0.07

11 0.25 ‐ ‐ ‐ ‐ ‐ ‐

12 0.23 ‐ ‐ ‐ 0.27 ‐ ‐

13 1.46 ‐ 0.14 ‐ 0.04 ‐ ‐

* watershed is a landuse type, not the total for the subbasin Table A1‐2. Brushy Creek Landuse Fractions by Subbasin

Subbasin Number

Agricultural Land Delta Recreation Open Space Parks and Recreation

Public/Semi‐Public

Water Watershed

1 0.94 ‐ ‐ ‐ ‐ ‐ 0.06

2 1.00 ‐ ‐ ‐ ‐ ‐ ‐

3 0.68 ‐ ‐ 0.32 ‐ ‐ ‐

4 1.00 ‐ ‐ ‐ ‐ ‐ ‐

5 0.78 ‐ ‐ 0.11 ‐ ‐ 0.11

6 0.72 ‐ ‐ 0.28 ‐ ‐ ‐

7 0.80 ‐ ‐ 0.20 ‐ ‐ ‐

8 1.00 ‐ ‐ ‐ ‐ ‐ ‐

9 1.00 ‐ ‐ ‐ ‐ ‐ ‐

10 0.74 ‐ 0.04 ‐ 0.17 ‐ 0.05

11 1.00 ‐ ‐ ‐ ‐ ‐ ‐

12 0.45 ‐ 0.01 ‐ 0.54 ‐ ‐

13 0.89 ‐ 0.08 ‐ 0.02 ‐ ‐

July 2011 18


Table A1‐3. Brushy Creek Area‐Weighted Infiltration Rate by Subbasin/Landuse

Subbasin Number

Agricultural Land

Delta Recreation

Open Space

Parks and Recreation


Water Watershed Total

Average Infiltration

Rate (in/hr)

0.175 0.175 0.175 0.175 0.175 0.175 0.175

1 0.165 ‐ ‐ ‐ ‐ ‐ 0.010 0.175

2 0.119 ‐ ‐ 0.056 ‐ ‐ ‐ 0.175

3 0.175 ‐ ‐ ‐ ‐ ‐ ‐ 0.175

4 0.137 ‐ ‐ 0.019 ‐ ‐ 0.019 0.175

5 0.126 ‐ ‐ 0.049 ‐ ‐ ‐ 0.175

6 0.141 ‐ ‐ 0.034 ‐ ‐ ‐ 0.175

7 0.175 ‐ ‐ ‐ ‐ ‐ ‐ 0.175

8 0.175 ‐ ‐ ‐ ‐ ‐ ‐ 0.175

9 0.129 ‐ 0.006 ‐ 0.031 ‐ 0.009 0.175

10 0.175 ‐ ‐ ‐ ‐ ‐ ‐ 0.175

11 0.079 ‐ 0.002 ‐ 0.095 ‐ ‐ 0.175

12 0.156 ‐ 0.014 ‐ 0.004 ‐ ‐ 0.175

13 0.165 ‐ ‐ ‐ ‐ ‐ 0.010 0.175

Please note that the landuse coverage ends at the Alameda/Contra Costa County border. Aerial photos were reviewed to determine if the area of the watershed in Alameda County was being used differently than in Contra Costa County. There did not appear to be a difference in landuse between the two counties so the Contra Costa landuse was applied to the subbasins that fall either partly or entirely in Alameda County.

July 2011 19


July 2011 20


Table A1‐4. Frisk Creek Landuse Area (square miles) by Subbasin

Subbasin Number

Agricultural Core Land

Agricultural Land Commercial Light Industry Multiple Family Residential Low

Multiple Family Residential Medium

Open Space

1 ‐ 0.886 ‐ ‐ ‐ ‐ ‐2 ‐ 0.673 ‐ ‐ ‐ ‐ ‐3 ‐ 1.758 ‐ ‐ ‐ ‐ ‐4 ‐ 1.082 ‐ ‐ ‐ ‐ ‐5 0.149 1.475 ‐ ‐ ‐ ‐ ‐6 0.480 0.163 ‐ ‐ ‐ ‐ ‐7 0.035 0.875 0.013 0.006 ‐ 0.002 ‐8 ‐ 0.845 ‐ ‐ ‐ ‐ ‐9 ‐ 0.977 ‐ ‐ ‐ ‐ ‐10 0.106 0.295 0.010 0.005 0.015 ‐ ‐11 0.099 0.613 ‐ 0.002 ‐ ‐ 0.051

Subbasin Number Parks and Recreation

Public/Semi‐Public Single Family Residential High

Single Family Residential Medium

Single Family Residential Very

Low

Water Watershed

1 ‐ ‐ ‐ ‐ ‐ ‐ 0.9972 ‐ ‐ ‐ ‐ ‐ ‐ 0.0783 ‐ ‐ ‐ ‐ ‐ ‐ 0.0174 ‐ ‐ ‐ ‐ ‐ ‐ 0.0945 ‐ 0.001 ‐ 0.001 ‐ ‐ 0.0126 ‐ 0.004 ‐ ‐ ‐ ‐ ‐7 ‐ 0.012 0.050 0.070 0.045 ‐ ‐8 ‐ 0.008 ‐ ‐ ‐ ‐ ‐9 ‐ 0.035 0.021 ‐ ‐ ‐ ‐10 ‐ 0.013 0.049 0.008 ‐ ‐ ‐11 ‐ 0.030 0.002 0.001 ‐ ‐ ‐

July 2011 21


Table A1‐5. Brushy Creek Landuse Fractions by Subbasin

Subbasin Number


Agricultural Land Commercial Light Industry Multiple Family Residential Low


Open Space

1 ‐ 0.471 ‐ ‐ ‐ ‐ ‐2 ‐ 0.896 ‐ ‐ ‐ ‐ ‐3 ‐ 0.991 ‐ ‐ ‐ ‐ ‐4 ‐ 0.920 ‐ ‐ ‐ ‐ ‐5 0.091 0.900 ‐ ‐ ‐ ‐ ‐6 0.742 0.252 ‐ ‐ ‐ ‐ ‐7 0.032 0.790 0.012 0.006 ‐ 0.002 ‐8 ‐ 0.991 ‐ ‐ ‐ ‐ ‐9 ‐ 0.946 ‐ ‐ ‐ ‐ ‐10 0.212 0.590 0.020 0.009 0.030 ‐ ‐11 0.124 0.768 ‐ 0.002 ‐ ‐ 0.064

Subbasin Number Parks and

Recreation Public/Semi‐Public Single Family

Residential High Single Family Residential Medium


Low

Water Watershed

1 ‐ ‐ ‐ ‐ ‐ ‐ 0.5292 ‐ ‐ ‐ ‐ ‐ ‐ 0.1043 ‐ ‐ ‐ ‐ ‐ ‐ 0.0094 ‐ ‐ ‐ ‐ ‐ ‐ 0.0805 ‐ 0.001 ‐ 0.001 ‐ ‐ 0.0076 ‐ 0.006 ‐ ‐ ‐ ‐ ‐7 ‐ 0.011 0.045 0.063 0.040 ‐ ‐8 ‐ 0.009 ‐ ‐ ‐ ‐ ‐9 ‐ 0.034 0.021 ‐ ‐ ‐ ‐10 ‐ 0.026 0.097 0.016 ‐ ‐ ‐11 ‐ 0.037 0.003 0.002 ‐ ‐ ‐

July 2011 22


Table A1‐6. Frisk Creek Area‐Weighted Infiltration Rate by Subbasin/Landuse

Subbasin Number


Agricultural Land

Commercial Light Industry

Multiple Family

Residential Low

Multiple Family

Residential Medium

Open Space Parks and Recreation


Rate (in/hr)

0.175 0.175 0.025 0.035 0.058 0.055 0.175 0.175

1 ‐ 0.082 ‐ ‐ ‐ ‐ ‐ ‐

2 ‐ 0.157 ‐ ‐ ‐ ‐ ‐ ‐

3 ‐ 0.173 ‐ ‐ ‐ ‐ ‐ ‐

4 ‐ 0.161 ‐ ‐ ‐ ‐ ‐ ‐

5 0.016 0.157 ‐ ‐ ‐ ‐ ‐ ‐

6 0.130 0.044 ‐ ‐ ‐ ‐ ‐ ‐

7 0.006 0.138 ‐ ‐ ‐ ‐ ‐ ‐

8 ‐ 0.173 ‐ ‐ ‐ ‐ ‐ ‐

9 ‐ 0.165 ‐ ‐ ‐ ‐ ‐ ‐

10 0.037 0.103 0.001 ‐ 0.002 ‐ ‐ ‐

11 0.022 0.134 ‐ ‐ ‐ ‐ 0.011 ‐

July 2011 23


Table A1‐6. Frisk Creek Area‐Weighted Infiltration Rate by Subbasin/Landuse (cont.)

Subbasin Number


Single Family Residential

High


Single Family Residential Very Low



Rate (in/hr)

0.175 0.066 0.087 0.155 0.175 0.175

1 ‐ ‐ ‐ ‐ ‐ 0.093 0.175

2 ‐ ‐ ‐ ‐ ‐ 0.018 0.175

3 ‐ ‐ ‐ ‐ ‐ 0.002 0.175

4 ‐ ‐ ‐ ‐ ‐ 0.014 0.175

5 ‐ ‐ ‐ ‐ ‐ 0.001 0.175

6 0.001 ‐ ‐ ‐ ‐ ‐ 0.175

7 0.002 0.003 0.005 0.006 ‐ ‐ 0.161

8 0.002 ‐ ‐ ‐ ‐ ‐ 0.175

9 0.006 0.001 ‐ ‐ ‐ ‐ 0.173

10 0.004 0.006 0.001 ‐ ‐ ‐ 0.155

11 0.007 ‐ ‐ ‐ ‐ ‐ 0.174

July 2011 24


July 2011 25


Table A1‐7. Kellogg Creek Landuse Area (square miles) by Subbasin

Subbasin Number Agricultural Core

Land Agricultural Land Commercial Light Industry Multiple Family

Residential Low Office Park Open Space

2 ‐ ‐ ‐ ‐ ‐ ‐ ‐3 ‐ ‐ ‐ ‐ ‐ ‐ ‐4 ‐ 0.20 ‐ ‐ ‐ ‐ ‐5 ‐ ‐ ‐ ‐ ‐ ‐ ‐6 ‐ 7.01 ‐ ‐ ‐ ‐ ‐7 ‐ 382.63 ‐ ‐ ‐ ‐ ‐8 138.26 94.76 ‐ ‐ ‐ ‐ ‐9 448.35 466.18 ‐ ‐ ‐ ‐ ‐10 535.97 ‐ ‐ ‐ ‐ ‐ ‐11 420.02 0.03 ‐ ‐ ‐ ‐ ‐12 353.97 0.06 ‐ ‐ ‐ ‐ ‐13 10.82 98.34 8.87 2.40 1.88 0.04 19.6914 ‐ ‐ ‐ ‐ ‐ ‐ ‐

Subbasin Number Parks and Recreation Public/Semi‐Public Single Family

Residential High Single Family

Residential Medium Water Watershed

2 6.55 ‐ ‐ ‐ ‐ 683.113 ‐ ‐ ‐ ‐ 8.71 543.214 ‐ ‐ ‐ ‐ ‐ 415.275 ‐ ‐ ‐ ‐ ‐ 525.266 43.86 ‐ ‐ ‐ ‐ 1572.477 ‐ ‐ ‐ ‐ ‐ 906.068 529.51 27.58 ‐ ‐ ‐ 112.939 354.85 51.20 ‐ ‐ ‐ ‐10 ‐ 0.28 ‐ ‐ ‐ ‐11 ‐ 7.00 ‐ ‐ ‐ ‐12 ‐ 3.71 ‐ ‐ ‐ ‐13 ‐ 36.37 ‐ ‐ ‐ ‐14 ‐ ‐ 1.04 10.08 0.04 ‐

July 2011 26


Table A1‐8. Kellogg Creek Landuse Fractions by Subbasin

Subbasin Number Agricultural Core

Land Agricultural Land Commercial Light Industry Multiple Family

Residential Low Office Park Open Space

2 ‐ ‐ ‐ ‐ ‐ ‐ ‐

3 ‐ ‐ ‐ ‐ ‐ ‐ ‐

4 ‐ ‐ ‐ ‐ ‐ ‐ ‐

5 ‐ ‐ ‐ ‐ ‐ ‐ ‐

6 ‐ ‐ ‐ ‐ ‐ ‐ ‐

7 ‐ 0.008 ‐ ‐ ‐ ‐ ‐

8 ‐ 0.363 ‐ ‐ ‐ ‐ ‐

9 0.216 0.148 ‐ ‐ ‐ ‐ ‐

10 0.490 0.510 ‐ ‐ ‐ ‐ ‐

11 0.987 ‐ ‐ ‐ ‐ ‐ ‐

12 0.991 ‐ ‐ ‐ ‐ ‐ ‐

13 0.907 ‐ ‐ ‐ ‐ ‐ ‐

14 0.071 0.642 0.058 0.016 0.012 ‐ 0.129

Subbasin Number Parks and Recreation Public/Semi‐Public Single Family


Residential Medium Water Watershed

2 0.009 ‐ ‐ ‐ ‐ 0.991

3 ‐ ‐ ‐ ‐ 0.016 0.984

4 ‐ ‐ ‐ ‐ ‐ 1.000

5 ‐ ‐ ‐ ‐ ‐ 1.000

6 0.027 ‐ ‐ ‐ ‐ 0.973

7 ‐ ‐ ‐ ‐ ‐ 0.992

8 0.503 0.026 ‐ ‐ ‐ 0.107

9 0.555 0.080 ‐ ‐ ‐ ‐

10 ‐ ‐ ‐ ‐ ‐ ‐

11 ‐ 0.013 ‐ ‐ ‐ ‐

12 ‐ 0.009 ‐ ‐ ‐ ‐

13 ‐ 0.093 ‐ ‐ ‐ ‐

14 ‐ ‐ 0.007 0.066 ‐ ‐

July 2011 27


Table A1‐9. Kellogg Creek Area‐Weighted Infiltration Rate by Subbasin/Landuse

Subbasin Number


Agricultural Land


Multiple Family

Residential Low

Office Park Open Space Parks and Recreation


Rate (in/hr)

0.175 0.175 0.025 0.035 0.058 0.025 0.175 0.175

2 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 0.002

3 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

4 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

6 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 0.005

7 ‐ 0.001 ‐ ‐ ‐ ‐ ‐ ‐

8 ‐ 0.064 ‐ ‐ ‐ ‐ ‐ 0.088

9 0.038 0.026 ‐ ‐ ‐ ‐ ‐ 0.097

10 0.086 0.089 ‐ ‐ ‐ ‐ ‐ ‐

11 0.173 ‐ ‐ ‐ ‐ ‐ ‐ ‐

12 0.173 ‐ ‐ ‐ ‐ ‐ ‐ ‐

13 0.159 ‐ ‐ ‐ ‐ ‐ ‐ ‐

14 0.012 0.112 0.001 0.001 0.001 ‐ 0.022 ‐

July 2011 28


Table A1‐9. Kellogg Creek Area‐Weighted Infiltration Rate by Subbasin/Landuse (cont.)

Subbasin Number



High




Rate (in/hr)

0.175 0.066 0.087 0.175 0.175

2 ‐ ‐ ‐ ‐ 0.173 0.175

3 ‐ ‐ ‐ 0.003 0.172 0.175

4 ‐ ‐ ‐ ‐ 0.175 0.175

5 ‐ ‐ ‐ ‐ 0.175 0.175

6 ‐ ‐ ‐ ‐ 0.170 0.175

7 ‐ ‐ ‐ ‐ 0.174 0.175

8 0.005 ‐ ‐ ‐ 0.019 0.175

9 0.014 ‐ ‐ ‐ ‐ 0.175

10 ‐ ‐ ‐ ‐ ‐ 0.175

11 0.002 ‐ ‐ ‐ ‐ 0.175

12 0.002 ‐ ‐ ‐ ‐ 0.175

13 0.016 ‐ ‐ ‐ ‐ 0.175

14 ‐ ‐ 0.006 ‐ ‐ 0.156

July 2011 29


July 2011 30


Table A1‐10. Mt. Diablo Creek Landuse Area (square miles) by Subbasin

Subbasin Number

Agricultural Land Commercial Heavy Industry Landfill Light Industry Multiple Family Residential Low


Office Park

1 6.816 0.153 0.007 0.055 ‐ 0.166 0.131 0.0032 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐3 0.000 ‐ ‐ 0.112 ‐ ‐ ‐ ‐4 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐5 0.024 ‐ ‐ 0.094 ‐ ‐ ‐ ‐6 0.177 ‐ ‐ ‐ ‐ ‐ ‐ ‐7 ‐ ‐ ‐ ‐ 0.088 ‐ ‐ ‐8 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐9 0.594 ‐ ‐ ‐ 0.542 ‐ 0.002 ‐10 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐11 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐12 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

Subbasin Number Open Space Parks and



Residential Low Single Family Residential Medium


Low

1 1.949 7.962 0.603 3.625 0.053 ‐ 0.3102 ‐ ‐ 0.063 0.000 0.000 ‐ ‐3 ‐ ‐ 1.068 0.004 ‐ ‐ ‐4 ‐ ‐ 0.131 ‐ ‐ ‐ ‐5 ‐ ‐ 0.882 ‐ ‐ ‐ ‐6 0.003 ‐ 3.531 ‐ ‐ 0.002 ‐7 0.511 ‐ 0.075 ‐ ‐ ‐ ‐8 0.335 ‐ 0.028 ‐ ‐ ‐ ‐9 0.116 0.249 0.808 0.176 ‐ ‐ ‐10 0.003 ‐ 0.072 ‐ ‐ ‐ ‐11 0.000 ‐ 1.111 ‐ ‐ ‐ ‐12 0.024 ‐ 0.002 ‐ ‐ ‐ ‐

July 2011 31


Table A1‐11. Mt. Diablo Creek Landuse Fractions by Subbasin

Subbasin Number

Agricultural Land Commercial Heavy Industry Landfill Light Industry Multiple Family Residential Low


Office Park

1 0.312 0.007 ‐ 0.003 ‐ 0.008 0.006 ‐

2 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

3 ‐ ‐ ‐ 0.095 ‐ ‐ ‐ ‐

4 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

5 0.024 ‐ ‐ 0.094 ‐ ‐ ‐ ‐

6 0.048 ‐ ‐ ‐ ‐ ‐ ‐ ‐

7 ‐ ‐ ‐ ‐ 0.130 ‐ ‐ ‐

8 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

9 0.239 ‐ ‐ ‐ 0.218 ‐ 0.001 ‐

10 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

11 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

12 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

Subbasin Number Open Space Parks and



Residential Low Single Family Residential Medium


Low

1 0.089 0.365 0.028 0.166 0.002 ‐ 0.014

2 ‐ ‐ 0.991 0.007 0.002 ‐ ‐

3 ‐ ‐ 0.902 0.003 ‐ ‐ ‐

4 ‐ ‐ 1.000 ‐ ‐ ‐ ‐

5 ‐ ‐ 0.882 ‐ ‐ ‐ ‐

6 0.001 ‐ 0.951 ‐ ‐ 0.001 ‐

7 0.758 ‐ 0.112 ‐ ‐ ‐ ‐

8 0.924 ‐ 0.076 ‐ ‐ ‐ ‐

9 0.047 0.100 0.325 0.071 ‐ ‐ ‐

10 0.039 ‐ 0.961 ‐ ‐ ‐ ‐

11 ‐ ‐ 1.000 ‐ ‐ ‐ ‐

12 0.930 ‐ 0.070 ‐ ‐ ‐ ‐

July 2011 32


Table A1‐12. Mt. Diablo Creek Area‐Weighted Infiltration Rate by Subbasin/Landuse

Subbasin Number

Agricultural Land

Commercial Heavy Industry

Landfill Light Industry Multiple Family

Residential Low

Multiple Family

Residential Medium

Office Park


Rate (in/hr)

0.175 0.025 0.040 0.175 0.035 0.058 0.055 0.025

1 0.055 ‐ ‐ ‐ ‐ ‐ ‐ ‐

2 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

3 ‐ ‐ ‐ 0.017 ‐ ‐ ‐ ‐

4 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

5 0.004 ‐ ‐ 0.016 ‐ ‐ ‐ ‐

6 0.008 ‐ ‐ ‐ ‐ ‐ ‐ ‐

7 ‐ ‐ ‐ ‐ 0.005 ‐ ‐ ‐

8 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

9 0.042 ‐ ‐ ‐ 0.008 ‐ ‐ ‐

10 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

11 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

12 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

July 2011 33


Table A1‐12. Mt. Diablo Creek Area‐Weighted Infiltration Rate by Subbasin/Landuse (cont.)

Subbasin Number




High


Low



Total


Rate (in/hr)

0.175 0.175 0.175 0.066 0.123 0.087 0.155

1 0.016 0.064 0.005 0.011 ‐ ‐ 0.002 0.154

2 ‐ ‐ 0.173 ‐ ‐ ‐ ‐ 0.174

3 ‐ ‐ 0.158 ‐ ‐ ‐ ‐ 0.175

4 ‐ ‐ 0.175 ‐ ‐ ‐ ‐ 0.175

5 ‐ ‐ 0.154 ‐ ‐ ‐ ‐ 0.175

6 ‐ ‐ 0.166 ‐ ‐ ‐ ‐ 0.175

7 0.133 ‐ 0.020 ‐ ‐ ‐ ‐ 0.157

8 0.162 ‐ 0.013 ‐ ‐ ‐ ‐ 0.175

9 0.008 0.018 0.057 0.005 ‐ ‐ ‐ 0.137

10 0.007 ‐ 0.168 ‐ ‐ ‐ ‐ 0.175

11 ‐ ‐ 0.175 ‐ ‐ ‐ ‐ 0.175

12 0.163 ‐ 0.012 ‐ ‐ ‐ ‐ 0.175

July 2011 34


Table A1‐13 Marsh Creek Original and Revised Landuse Areas (square miles) by Subbasin

Subbasin

Original Landuse (sq miles) Revised Landuse (sq miles)Agricultural Core Land

Agricultural Land

Business Park

Commercial Agricultural Core Land

Agricultural Land

Business Park

Commercial

104‐3 ‐ 2.693 ‐ ‐ ‐ 2.693 ‐ ‐

104‐DSFairview ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

104‐DSSpaL ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

104‐LowBasin ‐ 0.922 ‐ 0.092 ‐ 1.237 ‐ 0.157

104‐SpaL ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

104‐UpBasin ‐ 1.162 ‐ ‐ ‐ 1.682 ‐ ‐

105‐BtwdLk12 ‐ 0.004 ‐ ‐ ‐ 0.004 ‐ ‐

105‐BtwdLk14 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐BtwdLk18 ‐ 0.014 ‐ 0.005 ‐ 0.014 ‐ 0.005

105‐BtwdLk5 ‐ ‐ ‐ ‐ ‐ 0.000 ‐ ‐

105‐DeeratMC ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DeerBasin ‐ ‐ ‐ ‐ ‐ ‐ ‐ 0.003

105‐DeerDam ‐ 3.014 ‐ ‐ ‐ ‐ ‐ ‐

105‐DSBtwdLk14 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DSBtwdLk18 ‐ ‐ ‐ 0.000 ‐ ‐ ‐ 0.000

105‐DSBtwdLk5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DSDeerBasin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DSDeerDam ‐ 0.360 ‐ 0.008 ‐ 0.360 ‐ 0.008

106‐DryBasin ‐ 0.005 0.049 ‐ ‐ 0.005 0.010 ‐

106‐DryDam ‐ 1.845 ‐ ‐ ‐ 1.845 ‐ ‐

107‐7940Basin ‐ 0.143 ‐ ‐ ‐ 0.025 ‐ ‐

107‐8085Basin ‐ 0.000 ‐ ‐ ‐ 0.000 ‐ ‐

107‐DS8085Basin 0.000 0.017 ‐ ‐ 0.000 0.010 ‐ ‐

107‐DSVYNorthSM 0.000 0.000 ‐ ‐ 0.000 ‐ ‐ ‐

107‐DSVYSouthSM ‐ 0.000 ‐ ‐ ‐ 0.000 ‐ ‐

107‐VYNorth ‐ 0.341 ‐ ‐ ‐ 0.299 ‐ ‐

107‐VYSouth ‐ 0.318 ‐ ‐ ‐ 0.318 ‐ ‐

108‐EofMCDam ‐ ‐ ‐ ‐ ‐ ‐ ‐

108‐MCDam ‐ 27.645 ‐ ‐ ‐ 27.645 ‐ ‐

30A‐2 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

30A‐BrownBas ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

30A‐LaurelBas ‐ ‐ ‐ 0.048 ‐ 0.100 ‐ ‐

30C‐DSFVBasin ‐ ‐ ‐ ‐ ‐ 0.138 ‐ ‐

30C‐DSLibertyBas ‐ ‐ ‐ 0.017 ‐ 0.077 ‐ 0.017

30C‐FairviewBas ‐ ‐ 0.147 0.181 ‐ 0.026 0.001 0.181

30C‐LibertyBas ‐ ‐ 0.094 0.015 ‐ ‐ 0.027 0.015

52A‐1 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 0.000

52A‐2 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

52B‐1 ‐ ‐ ‐ 0.118 ‐ ‐ ‐ 0.118

52C‐Basin1 0.003 ‐ ‐ 0.075 0.003 0.061 ‐ 0.086

52C‐Basin2 0.020 ‐ ‐ 0.003 0.007 ‐ 0.003

52C‐Basin3 0.003 ‐ ‐ 0.031 0.003 ‐ 0.026

52C‐Lowest 0.001 0.001 ‐ ‐ 0.001 0.001 ‐ 0.063

52D‐Outlet ‐ 0.142 ‐ ‐ ‐ 0.142 ‐ ‐

MC‐118.5 ‐ ‐ ‐ ‐ ‐ 0.043 ‐ ‐

MC‐137.0 ‐ ‐ ‐ 0.002 ‐ ‐ ‐ 0.002

MC‐139.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐160.0 ‐ 0.001 ‐ ‐ ‐ 0.001 ‐ ‐

MC‐184.0 ‐ 0.001 ‐ 0.036 ‐ 0.001 ‐ 0.036

MC‐198.0 ‐ 0.128 ‐ 0.011 ‐ 0.128 ‐ 0.011

MC‐217.5 ‐ 0.059 ‐ ‐ ‐ 0.059 ‐ ‐

MC‐236.5 ‐ 0.029 ‐ 0.036 ‐ 0.029 ‐ 0.036

MC‐252.0 ‐ 0.002 ‐ 0.014 ‐ 0.002 ‐ 0.014

MC‐254.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 0.002

MC‐259.0 ‐ ‐ ‐ 0.011 ‐ ‐ ‐ 0.011

July 2011 35


Subbasin

Original Landuse (sq miles) Revised Landuse (sq miles)Agricultural Core Land

Agricultural Land

Business Park

Commercial Agricultural Core Land

Agricultural Land

Business Park

Commercial

MC‐263.0 ‐ ‐ ‐ 0.008 ‐ ‐ ‐ 0.008

MC‐287.0 ‐ ‐ ‐ 0.000 ‐ ‐ ‐ 0.000

MC‐305.5 ‐ ‐ ‐ 0.064 ‐ ‐ ‐ 0.064

MC‐312.0 ‐ ‐ ‐ 0.000 ‐ ‐ ‐ 0.016

MC‐312.5 ‐ ‐ ‐ 0.077 ‐ ‐ ‐ 0.077

MC‐331.1 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐338.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐363.6 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐372.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐379.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐380.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐386.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐387.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐389.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐393.4 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐401.0 ‐ ‐ 0.011 0.003 ‐ 0.011 0.003

MC‐404.2 0.003 ‐ ‐ ‐ 0.003 ‐ ‐ ‐

MC‐404.7 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐at30ALaruelOut ‐ ‐ ‐ 0.040 ‐ 0.073 ‐ 0.040

MC‐at30Coutlet ‐ ‐ ‐ 0.012 ‐ 0.000 ‐ 0.012

MC‐at52C ‐ 0.000 ‐ ‐ ‐ 0.000 ‐ ‐

MC‐at52D‐Outlet ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐at52D‐OutletSM ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐at8085Basin 0.036 0.067 ‐ ‐ 0.036 0.065 ‐ ‐

MC‐atDS7940Basin 0.135 0.015 ‐ ‐ 0.135 ‐ ‐ ‐

MC‐atDS7940BasSM ‐ 0.001 ‐ ‐ ‐ ‐ ‐ ‐

MC‐atVYNorth 0.040 0.009 ‐ ‐ 0.040 0.009 ‐ ‐

MC‐atVYSouth ‐ 0.001 ‐ ‐ 0.001 ‐ ‐

MC‐DSECCID 0.000 0.000 ‐ ‐ 0.000 0.000 ‐ ‐

MC‐ECCID 0.418 0.012 ‐ ‐ 0.418 0.007 ‐ ‐

MC‐Outlet3 ‐ ‐ ‐ 0.011 ‐ ‐ ‐ 0.011

MC‐US30ALaruelOut ‐ ‐ ‐ 0.000 ‐ ‐ ‐ 0.000

Subbasin

Original Landuse (sq miles) Revised Landuse (sq miles)Light

Industry MultiFamily

Low MultiFamilyMedium

Mobile Homes

Light Industry

MultiFamily Low

MultiFamily Medium

Mobile Homes

104‐3 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

104‐DSFairview ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

104‐DSSpaL ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

104‐LowBasin ‐ 0.056 0.053 ‐ ‐ 0.001 ‐ ‐

104‐SpaL ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

104‐UpBasin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐BtwdLk12 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐BtwdLk14 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐BtwdLk18 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐BtwdLk5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DeeratMC ‐ 0.050 ‐ ‐ ‐ ‐ ‐

105‐DeerBasin ‐ 0.001 0.012 ‐ ‐ ‐ 0.022 ‐

105‐DeerDam ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DSBtwdLk14 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DSBtwdLk18 ‐ ‐ 0.004 ‐ ‐ ‐ 0.004 ‐

105‐DSBtwdLk5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DSDeerBasin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DSDeerDam ‐ 0.007 0.000 ‐ ‐ 0.006 0.000 ‐

106‐DryBasin ‐ 0.018 ‐ ‐ ‐ ‐ ‐ ‐

July 2011 36


Subbasin




Mobile Homes

Light Industry

MultiFamily Low

MultiFamily Medium

Mobile Homes

106‐DryDam ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐7940Basin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐8085Basin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐DS8085Basin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐DSVYNorthSM ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐DSVYSouthSM ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐VYNorth ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐VYSouth ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

108‐EofMCDam ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

108‐MCDam ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

30A‐2 ‐ 0.001 ‐ ‐ ‐ ‐ ‐ ‐

30A‐BrownBas ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

30A‐LaurelBas ‐ 0.010 ‐ ‐ ‐ ‐ ‐ ‐

30C‐DSFVBasin ‐ 0.000 ‐ ‐ ‐ ‐ ‐ ‐

30C‐DSLibertyBas ‐ 0.006 ‐ ‐ ‐ ‐ ‐ ‐

30C‐FairviewBas ‐ 0.099 0.003 ‐ ‐ ‐ 0.023 ‐

30C‐LibertyBas ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

52A‐1 0.078 0.024 0.000 0.009 0.078 0.024 ‐ 0.009

52A‐2 0.012 ‐ 0.005 ‐ 0.012 ‐ ‐ ‐

52B‐1 0.018 0.046 0.021 ‐ 0.018 ‐ 0.021 ‐

52C‐Basin1 0.131 0.014 0.014 0.046 0.131 0.003 0.014 0.046

52C‐Basin2 ‐ 0.000 0.038 ‐ ‐ ‐ 0.038 ‐

52C‐Basin3 ‐ 0.174 0.005 ‐ ‐ ‐ 0.005 ‐

52C‐Lowest ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

52D‐Outlet ‐ 0.213 ‐ ‐ ‐ ‐ ‐ ‐

MC‐118.5 ‐ 0.000 ‐ ‐ ‐ ‐ ‐ ‐

MC‐137.0 ‐ 0.000 ‐ ‐ ‐ ‐ ‐ ‐

MC‐139.0 ‐ 0.000 ‐ ‐ ‐ ‐ ‐ ‐

MC‐160.0 ‐ 0.000 ‐ ‐ ‐ ‐ ‐ ‐

MC‐184.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐198.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐217.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐236.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐252.0 ‐ 0.012 ‐ ‐ ‐ ‐ ‐ ‐

MC‐254.0 ‐ 0.020 ‐ ‐ ‐ ‐ ‐ ‐

MC‐259.0 ‐ 0.016 ‐ ‐ ‐ ‐ ‐ ‐

MC‐263.0 ‐ 0.002 ‐ ‐ ‐ ‐ ‐ ‐

MC‐287.0 ‐ 0.000 ‐ ‐ ‐ ‐ ‐ ‐

MC‐305.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐312.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐312.5 0.000 ‐ 0.000 ‐ 0.000 ‐ 0.000 ‐

MC‐331.1 0.000 ‐ ‐ ‐ 0.000 ‐ ‐ ‐

MC‐338.5 0.000 ‐ ‐ ‐ 0.000 ‐ ‐ ‐

MC‐363.6 ‐ 0.007 ‐ ‐ ‐ ‐ ‐ ‐

MC‐372.0 ‐ 0.002 ‐ ‐ ‐ ‐ ‐ ‐

MC‐379.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐380.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐386.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐387.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐389.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐393.4 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐401.0 ‐ 0.035 ‐ ‐ ‐ 0.000 ‐ ‐

MC‐404.2 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐404.7 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐at30ALaruelOut ‐ 0.095 ‐ ‐ ‐ ‐ ‐ ‐

MC‐at30Coutlet ‐ 0.024 ‐ ‐ ‐ ‐ ‐ ‐

MC‐at52C ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

July 2011 37


Subbasin




Mobile Homes

Light Industry

MultiFamily Low

MultiFamily Medium

Mobile Homes

MC‐at52D‐Outlet ‐ 0.000 ‐ ‐ ‐ ‐ ‐ ‐

MC‐at52D‐OutletSM ‐ 0.000 ‐ ‐ ‐ ‐ ‐ ‐

MC‐at8085Basin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐atDS7940Basin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐atDS7940BasSM ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐atVYNorth ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐atVYSouth ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐DSECCID ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐ECCID ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐Outlet3 0.000 0.004 ‐ ‐ 0.000 ‐ ‐ ‐

MC‐US30ALaruelOut ‐ 0.000 ‐ ‐ ‐ ‐ ‐ ‐

Subbasin

Original Landuse (sq miles) Revised Landuse (sq miles)MultiUse MultiFamily

Very High Office Open Space MultiUse MultiFamily

Very High Office Open Space

104‐3 ‐ ‐ ‐ 0.388 ‐ ‐ ‐ 0.565

104‐DSFairview ‐ ‐ ‐ 0.004 ‐ ‐ ‐ 0.077

104‐DSSpaL ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

104‐LowBasin ‐ ‐ ‐ 0.296 ‐ ‐ ‐ 0.909

104‐SpaL ‐ ‐ ‐ 0.003 ‐ ‐ ‐ 0.003

104‐UpBasin ‐ ‐ ‐ 0.849 ‐ ‐ ‐ 1.487

105‐BtwdLk12 ‐ ‐ ‐ 0.013 ‐ ‐ ‐ 0.013

105‐BtwdLk14 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐BtwdLk18 ‐ ‐ ‐ 0.025 ‐ ‐ ‐ 0.025

105‐BtwdLk5 ‐ ‐ ‐ 0.001 ‐ ‐ ‐ 0.001

105‐DeeratMC ‐ ‐ ‐ 0.002 ‐ ‐ ‐ 0.002

105‐DeerBasin ‐ ‐ ‐ 0.020 ‐ ‐ ‐ 0.020

105‐DeerDam ‐ ‐ ‐ 0.945 ‐ ‐ ‐ 0.945

105‐DSBtwdLk14 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DSBtwdLk18 ‐ ‐ ‐ 0.000 ‐ ‐ ‐ 0.000

105‐DSBtwdLk5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

105‐DSDeerBasin ‐ ‐ ‐ 0.012 ‐ ‐ ‐ 0.012

105‐DSDeerDam ‐ ‐ ‐ 0.022 ‐ ‐ ‐ 0.022

106‐DryBasin ‐ ‐ ‐ 0.044 ‐ ‐ ‐ 0.074

106‐DryDam ‐ ‐ ‐ 0.085 ‐ ‐ ‐ 0.085

107‐7940Basin ‐ ‐ ‐ 0.017 ‐ ‐ ‐ 0.017

107‐8085Basin ‐ ‐ ‐ 0.006 ‐ ‐ ‐ 0.006

107‐DS8085Basin ‐ ‐ ‐ 0.014 ‐ ‐ ‐ 0.014

107‐DSVYNorthSM ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐DSVYSouthSM ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐VYNorth ‐ ‐ ‐ 0.000 ‐ ‐ ‐ 0.000

107‐VYSouth ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

108‐EofMCDam ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

108‐MCDam ‐ ‐ ‐ 1.651 ‐ ‐ ‐ 1.651

30A‐2 ‐ ‐ ‐ 0.003 ‐ ‐ ‐ 0.003

30A‐BrownBas 0.034 ‐ ‐ ‐ 0.034 ‐ ‐ ‐

30A‐LaurelBas ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

30C‐DSFVBasin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

30C‐DSLibertyBas ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

30C‐FairviewBas ‐ ‐ 0.133 0.003 ‐ 0.138 0.003

30C‐LibertyBas ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

52A‐1 0.003 0.000 ‐ ‐ 0.003 ‐ ‐ 0.000

52A‐2 ‐ ‐ ‐ 0.000 ‐ ‐ ‐ 0.000

52B‐1 0.051 0.000 0.022 0.000 0.058 ‐ 0.022 0.000

52C‐Basin1 0.027 0.005 ‐ 0.053 0.027 ‐ ‐ 0.115

July 2011 38


Subbasin

Original Landuse (sq miles) Revised Landuse (sq miles)MultiUse MultiFamily

Very High Office Open Space MultiUse MultiFamily

Very High Office Open Space

52C‐Basin2 0.062 0.000 ‐ 0.001 0.062 ‐ ‐ 0.007

52C‐Basin3 ‐ 0.050 ‐ ‐ ‐ ‐ ‐ 0.398

52C‐Lowest ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

52D‐Outlet ‐ ‐ ‐ ‐ ‐ ‐ ‐ 0.009

MC‐118.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐137.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐139.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐160.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐184.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐198.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐217.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐236.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐252.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐254.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐259.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐263.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐287.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐305.5 ‐ ‐ 0.001 ‐ ‐ ‐ 0.001 ‐

MC‐312.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐312.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐331.1 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐338.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐363.6 ‐ ‐ ‐ 0.000 ‐ ‐ ‐ 0.000

MC‐372.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐379.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐380.5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐386.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐387.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐389.0 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐393.4 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐401.0 ‐ ‐ 0.034 0.015 ‐ ‐ 0.034 0.015

MC‐404.2 ‐ ‐ ‐ 0.000 ‐ ‐ ‐ 0.000

MC‐404.7 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐at30ALaruelOut ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐at30Coutlet ‐ ‐ ‐ 0.003 0.003

MC‐at52C ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐at52D‐Outlet ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐at52D‐OutletSM ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐at8085Basin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐atDS7940Basin ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐atDS7940BasSM ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐atVYNorth ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐atVYSouth ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐DSECCID ‐ ‐ ‐ 0.002 ‐ ‐ ‐ 0.002

MC‐ECCID ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐Outlet3 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

MC‐US30ALaruelOut ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

Subbasin

Original Landuse (sq miles) Revised Landuse (sq miles)Parks

Recreation Public Semi

Public Single

Family High Single

Family Low Parks


Public Single

Family High Single

Family Low

104‐3 2.129 ‐ 0.051 ‐ 2.129 ‐ ‐ ‐

104‐DSFairview 0.007 0.040 0.024 0.067 0.007 0.040 0.414 ‐

104‐DSSpaL ‐ 0.000 ‐ ‐ ‐ 0.000 0.000 ‐

July 2011 39


Subbasin



Public Single

Family High Single

Family Low Parks


Public Single

Family High Single

Family Low

104‐LowBasin 0.008 0.169 0.762 ‐ 0.141 0.169 0.385 ‐

104‐SpaL 0.017 0.005 ‐ 0.000 0.017 0.005 0.592 ‐

104‐UpBasin 0.741 0.259 1.304 0.039 1.323 0.268 0.865 ‐

105‐BtwdLk12 0.101 ‐ 0.144 ‐ 0.101 ‐ 0.144 ‐

105‐BtwdLk14 0.027 ‐ 0.022 ‐ 0.026 ‐ 0.024 ‐

105‐BtwdLk18 0.074 ‐ 0.030 ‐ 0.074 ‐ 0.030 ‐

105‐BtwdLk5 0.036 0.005 0.021 ‐ 0.036 0.005 0.022 ‐

105‐DeeratMC 0.001 0.014 0.008 ‐ 0.001 0.014 0.227 ‐

105‐DeerBasin 0.102 0.117 0.093 0.175 0.072 0.117 0.387 0.018

105‐DeerDam 0.021 0.018 ‐ ‐ 0.021 0.018 ‐

105‐DSBtwdLk14 0.076 0.000 0.040 ‐ 0.017 0.000 0.098 0.000

105‐DSBtwdLk18 0.008 ‐ 0.001 ‐ 0.008 ‐ 0.001 ‐

105‐DSBtwdLk5 0.014 ‐ 0.039 ‐ 0.014 ‐ 0.039 ‐

105‐DSDeerBasin 0.003 0.001 0.034 0.060 0.003 0.001 0.099 ‐

105‐DSDeerDam 0.087 0.180 0.131 ‐ 0.087 0.181 0.131 ‐

106‐DryBasin 0.139 0.124 0.062 0.010 0.139 0.122 0.314 ‐

106‐DryDam 0.716 0.036 0.146 ‐ 0.716 0.036 0.196 ‐

107‐7940Basin 0.028 0.062 ‐ 0.008 0.028 0.062 0.237 ‐

107‐8085Basin ‐ 0.016 ‐ 0.062 ‐ 0.016 0.063 ‐

107‐DS8085Basin ‐ 0.013 ‐ 0.034 ‐ 0.013 0.042 ‐

107‐DSVYNorthSM 0.001 ‐ ‐ ‐ 0.001 ‐ 0.000 ‐

107‐DSVYSouthSM ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

107‐VYNorth 0.340 0.058 ‐ ‐ 0.340 0.058 0.042 ‐

107‐VYSouth 0.060 0.000 ‐ ‐ 0.060 0.000 ‐ ‐

108‐EofMCDam 0.486 ‐ ‐ ‐ 0.486 ‐ ‐ ‐

108‐MCDam 20.013 0.247 ‐ ‐ 20.013 0.247 0.000 ‐

30A‐2 ‐ 0.002 0.000 ‐ ‐ 0.002 0.016 ‐

30A‐BrownBas ‐ 0.037 0.007 0.057 ‐ 0.038 0.219 0.055

30A‐LaurelBas 0.008 0.046 0.244 0.106 0.039 0.046 0.281 0.187

30C‐DSFVBasin ‐ 0.025 ‐ 0.000 ‐ 0.057 0.133 0.000

30C‐DSLibertyBas ‐ 0.000 ‐ 0.435 ‐ 0.011 0.265 0.283

30C‐FairviewBas ‐ 0.102 0.000 ‐ 0.252 0.107 0.147

30C‐LibertyBas ‐ 0.116 ‐ 0.350 ‐ 0.168 0.391 0.181

52A‐1 0.004 0.025 ‐ ‐ 0.073 0.025 0.282 ‐

52A‐2 ‐ 0.003 0.009 ‐ 0.034 0.003 0.122 ‐

52B‐1 0.007 0.030 ‐ 0.000 0.007 0.030 0.074 0.000

52C‐Basin1 0.001 0.073 ‐ ‐ 0.001 0.073 0.567 ‐

52C‐Basin2 0.004 0.096 0.083 ‐ 0.004 0.096 0.183 ‐

52C‐Basin3 0.000 0.009 0.266 ‐ 0.000 0.009 0.174 ‐

52C‐Lowest 0.046 0.110 0.063 ‐ 0.046 0.110 ‐ ‐

52D‐Outlet 0.003 0.014 ‐ ‐ 0.003 0.014 0.203 ‐

MC‐118.5 ‐ 0.001 0.158 ‐ ‐ 0.001 0.165 0.001

MC‐137.0 0.012 0.010 0.265 0.007 0.012 0.010 0.201 0.017

MC‐139.0 ‐ 0.008 0.022 ‐ ‐ 0.008 0.024 ‐

MC‐160.0 ‐ 0.010 0.084 ‐ ‐ 0.010 0.169 ‐

MC‐184.0 ‐ 0.005 0.163 0.172 ‐ 0.005 0.001 0.172

MC‐198.0 ‐ 0.009 0.024 0.034 ‐ 0.009 ‐ 0.128

MC‐217.5 ‐ 0.002 ‐ ‐ ‐ 0.002 ‐ ‐

MC‐236.5 ‐ 0.006 0.000 0.088 ‐ 0.006 0.019 0.098

MC‐252.0 ‐ 0.001 0.000 ‐ ‐ 0.001 0.012 ‐

MC‐254.0 ‐ 0.002 0.002 ‐ ‐ 0.002 0.020 ‐

MC‐259.0 ‐ 0.002 ‐ ‐ ‐ 0.002 0.016 ‐

MC‐263.0 ‐ 0.009 ‐ ‐ ‐ 0.009 0.002 ‐

MC‐287.0 ‐ 0.007 ‐ 0.106 ‐ 0.007 0.000 0.106

MC‐305.5 ‐ 0.003 ‐ 0.000 ‐ 0.003 0.000 0.000

MC‐312.0 ‐ 0.020 ‐ 0.233 ‐ 0.020 0.071 0.149

MC‐312.5 ‐ 0.016 ‐ 0.053 ‐ 0.016 0.011 0.044

MC‐331.1 ‐ 0.003 ‐ ‐ ‐ 0.003 0.000 ‐

July 2011 40


Subbasin



Public Single

Family High Single

Family Low Parks


Public Single

Family High Single

Family Low

MC‐338.5 ‐ 0.004 ‐ ‐ ‐ 0.004 0.000 ‐

MC‐363.6 ‐ 0.003 ‐ ‐ ‐ 0.003 0.007 ‐

MC‐372.0 ‐ 0.002 ‐ ‐ ‐ 0.002 0.162 ‐

MC‐379.5 ‐ 0.000 ‐ ‐ ‐ 0.000 0.016 ‐

MC‐380.5 ‐ 0.002 ‐ ‐ ‐ 0.002 0.009 ‐

MC‐386.0 ‐ 0.000 ‐ ‐ 0.000 0.000 0.019 ‐

MC‐387.0 ‐ 0.001 ‐ ‐ ‐ 0.001 0.023 ‐

MC‐389.0 ‐ 0.002 ‐ ‐ ‐ 0.002 0.007 ‐

MC‐393.4 ‐ 0.003 ‐ ‐ 0.000 0.003 0.045 ‐

MC‐401.0 0.097 0.094 0.079 0.023 0.097 0.129 0.239 ‐

MC‐404.2 ‐ 0.008 ‐ ‐ 0.000 0.008 0.143 ‐

MC‐404.7 ‐ 0.003 ‐ ‐ ‐ 0.003 0.065 ‐

MC‐at30ALaruelOut ‐ 0.006 0.008 ‐ 0.008 0.006 0.213 0.016

MC‐at30Coutlet ‐ 0.005 ‐ ‐ ‐ 0.005 0.024 ‐

MC‐at52C ‐ 0.007 ‐ ‐ ‐ 0.007 ‐ ‐

MC‐at52D‐Outlet ‐ 0.007 ‐ ‐ ‐ 0.007 0.000 ‐

MC‐at52D‐OutletSM ‐ 0.000 ‐ ‐ ‐ 0.000 0.000 ‐

MC‐at8085Basin ‐ 0.000 ‐ ‐ ‐ 0.000 0.002 ‐

MC‐atDS7940Basin 0.000 ‐ ‐ ‐ 0.000 ‐ 0.015 ‐

MC‐atDS7940BasSM ‐ ‐ ‐ ‐ ‐ 0.001 ‐

MC‐atVYNorth 0.007 0.022 ‐ ‐ 0.007 0.022 ‐ ‐

MC‐atVYSouth 0.051 ‐ ‐ ‐ 0.051 ‐ ‐ ‐

MC‐DSECCID 0.002 0.010 ‐ ‐ 0.002 0.010 0.001 ‐

MC‐ECCID ‐ 0.012 ‐ 0.011 ‐ 0.012 0.016 ‐

MC‐Outlet3 ‐ 0.009 ‐ ‐ ‐ 0.009 0.004 ‐

MC‐US30ALaruelOut ‐ 0.006 ‐ ‐ ‐ 0.006 0.000 ‐

Subbasin

Original Landuse (sq miles) Revised Landuse (sq miles)Single Family Medium

Single Family Very Low

Watershed Single Family Medium


Watershed

104‐3 0.125 ‐ ‐ ‐ ‐ ‐

104‐DSFairview 0.397 0.056 ‐ 0.056 ‐ ‐

104‐DSSpaL 0.000 ‐ ‐ ‐ ‐ ‐

104‐LowBasin 0.646 ‐ ‐ 0.006 ‐ ‐

104‐SpaL 0.592 0.000 ‐ 0.000 ‐ ‐

104‐UpBasin 1.270 ‐ ‐ ‐ ‐ ‐

105‐BtwdLk12 ‐ ‐ ‐ ‐ ‐ ‐

105‐BtwdLk14 0.000 ‐ ‐ ‐ ‐ ‐

105‐BtwdLk18 ‐ ‐ ‐ ‐ ‐ ‐

105‐BtwdLk5 0.000 ‐ ‐ ‐ ‐ ‐

105‐DeeratMC 0.169 0.002 ‐ 0.002 ‐ ‐

105‐DeerBasin 0.127 ‐ ‐ ‐ ‐ ‐

105‐DeerDam ‐ ‐ ‐ ‐ ‐ ‐

105‐DSBtwdLk14 0.000 ‐ ‐ ‐ ‐ ‐

105‐DSBtwdLk18 ‐ ‐ ‐ ‐ ‐ ‐

105‐DSBtwdLk5 ‐ ‐ ‐ ‐ ‐ ‐

105‐DSDeerBasin 0.005 0.000 ‐ 0.000 ‐ ‐

105‐DSDeerDam ‐ ‐ ‐ ‐ ‐ ‐

106‐DryBasin 0.214 ‐ ‐ ‐ ‐ ‐

106‐DryDam 0.050 ‐ ‐ ‐ ‐ ‐

107‐7940Basin 0.111 ‐ ‐ ‐ ‐ ‐

107‐8085Basin 0.000 ‐ ‐ ‐ ‐ ‐

107‐DS8085Basin 0.000 ‐ ‐ ‐ ‐ ‐

107‐DSVYNorthSM ‐ ‐ ‐ ‐ ‐ ‐

July 2011 41


Subbasin





Watershed

107‐DSVYSouthSM ‐ ‐ ‐ ‐ ‐ ‐

107‐VYNorth 0.000 ‐ ‐ ‐ ‐ ‐

107‐VYSouth ‐ ‐ ‐ ‐ ‐ ‐

108‐EofMCDam ‐ ‐ 0.028 ‐ ‐ 0.028

108‐MCDam ‐ 0.311 1.164 ‐ 0.311 1.164

30A‐2 0.015 ‐ ‐ ‐ ‐ ‐

30A‐BrownBas 0.286 ‐ ‐ 0.074 ‐ ‐

30A‐LaurelBas 0.351 ‐ ‐ 0.161 ‐ ‐

30C‐DSFVBasin 0.165 0.139 ‐ 0.000 ‐ ‐

30C‐DSLibertyBas 0.119 0.221 ‐ 0.072 0.075 ‐

30C‐FairviewBas 0.244 0.059 ‐ 0.079 0.015 ‐

30C‐LibertyBas 0.018 0.274 ‐ 0.018 0.067 ‐

52A‐1 0.351 ‐ ‐ ‐ ‐ ‐

52A‐2 0.142 ‐ ‐ ‐ ‐ ‐

52B‐1 0.035 ‐ ‐ 0.000 ‐ ‐

52C‐Basin1 0.685 ‐ ‐ ‐ ‐ ‐

52C‐Basin2 0.093 ‐ ‐ ‐ ‐ ‐

52C‐Basin3 0.077 ‐ ‐ ‐ ‐ ‐

52C‐Lowest ‐ ‐ ‐ ‐ ‐ ‐

52D‐Outlet ‐ ‐ ‐ ‐ ‐ ‐

MC‐118.5 0.051 0.061 ‐ 0.061 ‐ ‐

MC‐137.0 ‐ 0.003 ‐ 0.058 ‐ ‐

MC‐139.0 0.002 ‐ ‐ ‐ ‐ ‐

MC‐160.0 0.092 0.020 ‐ 0.027 ‐ ‐

MC‐184.0 0.000 0.064 ‐ 0.226 ‐ ‐

MC‐198.0 0.093 0.053 ‐ 0.078 ‐ ‐

MC‐217.5 ‐ ‐ ‐ ‐ ‐ ‐

MC‐236.5 0.057 0.001 ‐ 0.029 ‐ ‐

MC‐252.0 0.000 0.024 ‐ 0.024 ‐ ‐

MC‐254.0 ‐ ‐ ‐ ‐ ‐ ‐

MC‐259.0 ‐ ‐ ‐ ‐ ‐ ‐

MC‐263.0 ‐ ‐ ‐ ‐ ‐ ‐

MC‐287.0 0.015 ‐ ‐ 0.015 ‐ ‐

MC‐305.5 0.000 ‐ ‐ ‐ ‐

MC‐312.0 0.005 ‐ ‐ 0.002 ‐ ‐

MC‐312.5 0.002 ‐ ‐ ‐ ‐

MC‐331.1 0.000 0.005 ‐ 0.005 ‐ ‐

MC‐338.5 0.000 0.056 ‐ 0.056 ‐ ‐

MC‐363.6 0.000 ‐ ‐ ‐ ‐ ‐

MC‐372.0 0.159 ‐ ‐ ‐ ‐ ‐

MC‐379.5 0.016 ‐ ‐ ‐ ‐ ‐

MC‐380.5 0.009 ‐ ‐ ‐ ‐ ‐

MC‐386.0 0.019 ‐ ‐ ‐ ‐ ‐

MC‐387.0 0.023 ‐ ‐ ‐ ‐ ‐

MC‐389.0 0.007 ‐ ‐ ‐ ‐ ‐

MC‐393.4 0.045 ‐ ‐ ‐ ‐ ‐

MC‐401.0 0.138 ‐ ‐ ‐ ‐ ‐

MC‐404.2 0.144 ‐ ‐ ‐ ‐ ‐

MC‐404.7 0.065 ‐ ‐ ‐ ‐ ‐

MC‐at30ALaruelOut 0.207 ‐ ‐ ‐ ‐ ‐

MC‐at30Coutlet 0.000 ‐ ‐ 0.000 ‐ ‐

MC‐at52C ‐ ‐ ‐ ‐ ‐ ‐

MC‐at52D‐Outlet 0.000 0.000 ‐ 0.000 ‐ ‐

MC‐at52D‐OutletSM ‐ ‐ ‐ ‐ ‐ ‐

MC‐at8085Basin ‐ ‐ ‐ ‐ ‐ ‐

MC‐atDS7940Basin ‐ ‐ ‐ ‐ ‐ ‐

MC‐atDS7940BasSM ‐ ‐ ‐ ‐ ‐ ‐

MC‐atVYNorth ‐ ‐ ‐ ‐ ‐ ‐

July 2011 42


Subbasin





Watershed

MC‐atVYSouth ‐ ‐ ‐ ‐ ‐ ‐

MC‐DSECCID 0.001 ‐ ‐ ‐ ‐ ‐

MC‐ECCID ‐ ‐ ‐ ‐ ‐ ‐

MC‐Outlet3 ‐ ‐ ‐ ‐ ‐ ‐

MC‐US30ALaruelOut ‐ ‐ ‐ ‐ ‐ ‐

Table A1‐14. Marsh Creek Original versus Revised Infiltration Rates by Subbasin

Subbasin Original Infiltration Rate

(in/hr)

Revised Infiltration Rate

(in/hr)

Subbasin Original Infiltration Rate

(in/hr)

Revised Infiltration Rate

(in/hr)

104‐3 0.175 0.170 108‐MCDam 0.175 0.173

104‐DSFairview 0.091 0.089 30A‐2 0.093 0.096

104‐DSSpaL 0.155 0.066 30A‐BrownBas 0.084 0.084

104‐LowBasin 0.153 0.113 30A‐LaurelBas 0.108 0.081

104‐SpaL 0.070 0.090 30C‐DSFVBasin 0.131 0.114

104‐UpBasin 0.158 0.126 30C‐DSLibertyBas 0.107 0.124

105‐BtwdLk12 0.115 0.114 30C‐FairviewBas 0.095 0.056

105‐BtwdLk14 0.123 0.123 30C‐LibertyBas 0.105 0.123

105‐BtwdLk18 0.148 0.132 52A‐1 0.083 0.075

105‐BtwdLk5 0.138 0.126 52A‐2 0.087 0.080

105‐DeeratMC 0.073 0.083 52B‐1 0.052 0.040

105‐DeerBasin 0.104 0.110 52C‐Basin1 0.084 0.077

105‐DeerDam 0.175 0.176 52C‐Basin2 0.086 0.073

105‐DSBtwdLk14 0.082 0.134 52C‐Basin3 0.136 0.063

105‐DSBtwdLk18 0.130 0.128 52C‐Lowest 0.132 0.063

105‐DSBtwdLk5 0.095 0.095 52D‐Outlet 0.115 0.103

105‐DSDeerBasin 0.081 0.108 MC‐118.5 0.089 0.090

105‐DSDeerDam 0.155 0.146 MC‐137.0 0.081 0.075

106‐DryBasin 0.121 0.103 MC‐139.0 0.093 0.066

106‐DryDam 0.168 0.167 MC‐160.0 0.075 0.084

107‐7940Basin 0.105 0.075 MC‐184.0 0.097 0.097

107‐8085Basin 0.094 0.115 MC‐198.0 0.132 0.129

107‐DS8085Basin 0.116 0.105 MC‐217.5 0.175 0.172

107‐DSVYNorthSM 0.151 0.167 MC‐236.5 0.105 0.102

107‐DSVYSouthSM 0.175 0.040 MC‐252.0 0.072 0.098

107‐VYNorth 0.169 0.101 MC‐254.0 0.073 0.059

107‐VYSouth 0.175 0.061 MC‐259.0 0.059 0.044

108‐EofMCDam 0.175 0.171 MC‐263.0 0.103 0.043

July 2011 43


Table A1‐14. Marsh Creek Original versus Revised Infiltration Rates by Subbasin (cont).

Subbasin Original Infiltration Rate (in/hr)

Revised Infiltration Rate (in/hr)

MC‐287.0 0.122 0.115 MC‐305.5 0.031 0.022 MC‐312.0 0.105 0.117 MC‐312.5 0.074 0.062 MC‐331.1 0.118 0.121 MC‐338.5 0.092 0.149 MC‐363.6 0.096 0.059 MC‐372.0 0.067 0.086 MC‐379.5 0.067 0.087 MC‐380.5 0.082 0.083 MC‐386.0 0.067 0.087 MC‐387.0 0.070 0.086 MC‐389.0 0.086 0.082 MC‐393.4 0.073 0.085 MC‐401.0 0.112 0.089 MC‐404.2 0.071 0.087 MC‐404.7 0.071 0.086 MC‐at30ALaruelOut 0.091 0.071 MC‐at30Coutlet 0.074 0.056 MC‐at52C 0.175 0.061 MC‐at52D‐Outlet 0.171 0.063 MC‐at52D‐OutletSM 0.159 0.060 MC‐at8085Basin 0.112 0.087 MC‐atDS7940Basin 0.007 0.162 MC‐atDS7940BasSM 0.066 0.040 MC‐atVYNorth 0.085 0.140 MC‐atVYSouth 0.175 0.167 MC‐DSECCID 0.165 0.088 MC‐ECCID 0.010 0.167 MC‐Outlet3 0.088 0.043 MC‐US30ALaruelOut 0.170 0.058

July 2011 44


Appendix A‐2

Lag Time Calculations

July 2011 45


July 2011 46


Table A2-1. Brushy Creek Area-Weighted Manning’s N Calculations

Subbasin Number

Agricultural Land

Delta Recreation

Open Space

Parks and Recreation



Average Manning’s n

0.085 0.058 0.085 0.075 0.028 0.028 0.085

1 0.080 ‐ ‐ ‐ ‐ ‐ 0.007 0.087

2 0.085 ‐ ‐ ‐ ‐ ‐ ‐ 0.085

3 0.058 ‐ ‐ 0.043 ‐ ‐ ‐ 0.100

4 0.085 ‐ ‐ ‐ ‐ ‐ ‐ 0.085

5 0.067 ‐ ‐ 0.022 ‐ ‐ 0.024 0.112

6 0.061 ‐ ‐ 0.017 ‐ ‐ ‐ 0.078

7 0.068 ‐ ‐ 0.008 ‐ ‐ ‐ 0.077

8 0.085 ‐ ‐ ‐ ‐ ‐ ‐ 0.085

9 0.085 ‐ ‐ ‐ ‐ ‐ ‐ 0.085

10 0.063 ‐ 0.004 ‐ 0.007 ‐ 0.006 0.079

11 0.085 ‐ ‐ ‐ ‐ ‐ ‐ 0.085

12 0.038 ‐ ‐ ‐ 0.008 ‐ ‐ 0.046

13 0.076 ‐ 0.012 ‐ 0.001 ‐ ‐ 0.088

July 2011 47


Table A2-2. Brushy Creek Lag Time Calculations

Subbasin Number Stream Length

(miles) Lca Length (miles)

Upstream Elevation (feet)

Downstream Elevation (feet)

Slope (ft/mile)

Manning’s n Lag time (hours)

1 2.021 0.622 1356 820 265.155 0.087 0.789

2 3.500 1.342 1292 438 243.990 0.085 1.292

3 3.129 1.491 1214 336 280.623 0.100 1.477

4 2.740 0.914 1026 336 251.852 0.085 1.011

5 4.875 2.379 1198 152 214.552 0.112 2.460

6 2.156 1.163 990 214 360.006 0.078 0.868

7 1.766 0.868 814 214 339.671 0.077 0.718

8 2.604 1.410 792 102 264.958 0.085 1.158

9 0.762 0.375 368 168 262.505 0.085 0.440

10 3.067 1.459 320 44 89.978 0.079 1.425

11 1.158 0.740 168 102 57.000 0.085 0.892

12 3.028 1.980 236 44 63.417 0.046 0.991

13 4.976 3.401 216 4 42.605 0.088 3.033

July 2011 48


July 2011 49


Table A2‐3. Frisk Creek Area‐Weighted Manning’s N Calculations

Subbasin Number


Agricultural Land


Multiple Family

Residential Low

Multiple Family

Residential Medium


Average Manning’s N

0.075 0.085 0.028 0.053 0.028 0.028 0.085 0.075

1 ‐ 0.040 ‐ ‐ ‐ ‐ ‐ ‐

2 ‐ 0.076 ‐ ‐ ‐ ‐ ‐ ‐

3 ‐ 0.084 ‐ ‐ ‐ ‐ ‐ ‐

4 ‐ 0.078 ‐ ‐ ‐ ‐ ‐ ‐

5 0.007 0.076 ‐ ‐ ‐ ‐ ‐ ‐

6 0.056 0.021 ‐ ‐ ‐ ‐ ‐ ‐

7 0.002 0.067 ‐ ‐ ‐ ‐ ‐ ‐

8 ‐ 0.084 ‐ ‐ ‐ ‐ ‐ ‐

9 ‐ 0.080 ‐ ‐ ‐ ‐ ‐ ‐

10 0.016 0.050 0.001 0.001 0.001 ‐ ‐ ‐

11 0.009 0.065 ‐ ‐ ‐ ‐ 0.005 ‐

July 2011 50


Table A2‐3. Frisk Creek Area‐Weighted Manning’s N Calculations (cont.)

Subbasin Number



High





0.028 0.028 0.028 0.028 0.028 0.085

1 ‐ ‐ ‐ ‐ ‐ 0.045 0.085

2 ‐ ‐ ‐ ‐ ‐ 0.009 0.085

3 ‐ ‐ ‐ ‐ ‐ 0.001 0.085

4 ‐ ‐ ‐ ‐ ‐ 0.007 0.085

5 ‐ ‐ ‐ ‐ ‐ 0.001 0.084

6 ‐ ‐ ‐ ‐ ‐ ‐ 0.077

7 ‐ 0.001 0.002 0.001 ‐ ‐ 0.075

8 ‐ ‐ ‐ ‐ ‐ ‐ 0.084

9 0.001 0.001 ‐ ‐ ‐ ‐ 0.082

10 0.001 0.003 ‐ ‐ ‐ ‐ 0.072

11 0.001 ‐ ‐ ‐ ‐ ‐ 0.081

July 2011 51


Table A2-4. Frisk Creek Lag Time Calculations

Subbasin Number

Stream Length (miles)

Lca Length (miles)



Slope (ft/mile)


1 3.315 1.739 922 116 243.113 0.085 1.398

2 1.919 0.911 380 116 137.566 0.085 0.990

3 3.104 1.678 352 56 95.353 0.085 1.607

4 2.419 1.258 236 56 74.412 0.085 1.373

5 3.562 2.366 342 32 87.030 0.084 1.940

6 2.037 0.924 182 32 73.649 0.077 1.038

7 3.002 2.000 94 8 28.651 0.075 1.880

8 1.400 0.368 44 30 9.998 0.084 1.012

9 2.739 1.846 30 8 8.031 0.082 2.452

10 2.071 1.231 32 8 11.590 0.072 1.548

11 2.267 0.776 28 2 11.468 0.081 1.515

July 2011 52


July 2011 53


Table A2‐5. Kellogg Creek Area‐Weighted Manning’s N Calculations

Subbasin Number


Agricultural Land


Multiple Family

Residential Low

Office Park Open Space Parks and Recreation


0.075 0.085 0.028 0.053 0.028 0.028 0.085 0.075

2 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 0.001

3 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

4 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

5 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

6 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 0.002

7 ‐ 0.001 ‐ ‐ ‐ ‐ ‐ ‐

8 ‐ 0.031 ‐ ‐ ‐ ‐ ‐ 0.038

9 0.016 0.013 ‐ ‐ ‐ ‐ ‐ 0.042

10 0.037 0.043 ‐ ‐ ‐ ‐ ‐ ‐

11 0.074 ‐ ‐ ‐ ‐ ‐ ‐ ‐

12 0.074 ‐ ‐ ‐ ‐ ‐ ‐ ‐

13 0.068 ‐ ‐ ‐ ‐ ‐ ‐ ‐

14 0.005 0.055 0.002 0.001 ‐ ‐ 0.011 ‐

July 2011 54


Table A2‐5. Kellogg Creek Area‐Weighted Manning’s N Calculations (cont.)

Subbasin Number



High




0.028 0.028 0.028 0.028 0.085

2 ‐ ‐ ‐ ‐ 0.084 0.085

3 ‐ ‐ ‐ ‐ 0.084 0.084

4 ‐ ‐ ‐ ‐ 0.085 0.085

5 ‐ ‐ ‐ ‐ 0.085 0.085

6 ‐ ‐ ‐ ‐ 0.083 0.085

7 ‐ ‐ ‐ ‐ 0.084 0.085

8 0.001 ‐ ‐ ‐ 0.009 0.078

9 0.002 ‐ ‐ ‐ ‐ 0.073

10 ‐ ‐ ‐ ‐ ‐ 0.080

11 ‐ ‐ ‐ ‐ ‐ 0.074

12 ‐ ‐ ‐ ‐ ‐ 0.075

13 0.003 ‐ ‐ ‐ ‐ 0.071

14 ‐ ‐ 0.002 ‐ ‐ 0.076

July 2011 55


Table A2-6. Kellogg Creek Lag Time Calculations

Subbasin Number


Lca Length (miles)



Slope (ft/mile)


2 2.545 1.337 1178 202 383.508 0.085 1.049

3 1.923 0.797 1258 254 522.185 0.084 0.722

4 2.193 0.791 1171 202 441.851 0.085 0.791

5 2.286 1.344 961 205 330.722 0.085 1.038

6 3.238 1.657 921 136 242.423 0.085 1.361

7 3.642 2.099 693 136 152.957 0.085 1.699

8 2.802 1.011 397 3 140.612 0.078 1.087

9 2.654 1.424 359 3 134.116 0.073 1.145

10 4.161 1.624 181 3 42.781 0.080 1.944

11 2.460 1.347 77 3 30.080 0.074 1.467

12 2.032 1.000 51 3 23.616 0.075 1.292

13 2.051 1.253 45 3 20.473 0.071 1.374

14 1.430 0.832 23 3 13.989 0.076 1.180

July 2011 56


July 2011 57


Table A2‐7. Mt. Diablo Creek Area‐Weighted Manning’s N by Landuse

Subbasin Number

Agricultural Land

Commercial Heavy Industry

Landfill Light Industry Multiple Family

Residential Low

Multiple Family

Residential Medium

Office Park


0.085 0.028 0.038 0.035 0.053 0.028 0.028 0.028

1 0.027 ‐ ‐ ‐ ‐ ‐ ‐ ‐

2 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

3 ‐ ‐ ‐ 0.003 ‐ ‐ ‐ ‐

4 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

5 0.002 ‐ ‐ 0.003 ‐ ‐ ‐ ‐

6 0.004 ‐ ‐ ‐ ‐ ‐ ‐ ‐

7 ‐ ‐ ‐ ‐ 0.007 ‐ ‐ ‐

8 ‐ ‐ ‐ ‐ 0.002 ‐ ‐ ‐

9 0.020 ‐ ‐ ‐ 0.012 ‐ ‐ ‐

10 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

11 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

12 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

July 2011 58


Table A2‐7. Mt. Diablo Creek Area‐Weighted Manning’s N by Landuse (cont.)

Subbasin Number




High


Low



Total


0.085 0.075 0.028 0.028 0.028 0.028 0.028

1 0.008 0.027 0.001 0.005 ‐ ‐ ‐ 0.068

2 ‐ ‐ 0.028 ‐ ‐ ‐ ‐ 0.028

3 ‐ ‐ 0.025 ‐ ‐ ‐ ‐ 0.029

4 ‐ ‐ 0.028 ‐ ‐ ‐ ‐ 0.028

5 ‐ ‐ 0.025 ‐ ‐ ‐ ‐ 0.030

6 ‐ ‐ 0.027 ‐ ‐ ‐ ‐ 0.031

7 0.064 ‐ 0.003 ‐ ‐ ‐ ‐ 0.074

8 0.036 ‐ 0.005 ‐ ‐ ‐ ‐ 0.053

9 0.004 0.008 0.009 0.002 ‐ ‐ ‐ 0.054

10 0.003 ‐ 0.027 ‐ ‐ ‐ ‐ 0.030

11 ‐ ‐ 0.028 ‐ ‐ ‐ ‐ 0.028

12 0.079 ‐ 0.002 ‐ ‐ ‐ ‐ 0.081

July 2011 59


Table A2-8. Mt. Diablo Creek Lag Time Calculations

Subbasin Number


Lca Length (miles)



Slope (ft/mile)


1 11.653 5.872 3800 218 307.388 0.068 2.738

2 0.730 0.409 218 186 43.864 0.028 0.207

3 3.246 1.992 1438 186 385.701 0.029 0.456

4 0.735 0.474 318 168 204.140 0.028 0.164

5 1.966 0.688 1176 168 512.793 0.030 0.247

6 4.048 1.632 168 58 27.174 0.031 0.814

7 2.678 1.060 122 4 44.062 0.074 1.286

8 1.202 0.478 26 4 18.304 0.053 0.593

9 2.275 1.512 58 6 22.854 0.054 1.144

10 0.373 0.222 6 4 5.364 0.030 0.203

11 2.137 1.333 602 2 280.726 0.028 0.343

12 0.513 0.239 4 0 7.792 0.081 0.593

July 2011 60


Table A2‐9. Marsh Creek Original and Revised Manning’s n and Lag Time by Subbasin

Subbasin Original Manning’s n

Revised Manning’s n

Original lag time (hrs)

Revised lag time (hrs)

104‐3 0.0733 0.0810 2.004 2.216

104‐DSFairview 0.0253 0.0359 0.243 0.344

104‐DSSpaL 0.0240 0.0280 0.007 0.008

104‐LowBasin 0.0445 0.0709 1.048 1.672

104‐SpaL 0.0253 0.0295 0.519 0.605

104‐UpBasin 0.0613 0.0712 1.616 1.877

105‐BtwdLk12 0.0437 0.0499 0.395 0.451

105‐BtwdLk14 0.0361 0.0525 0.136 0.198

105‐BtwdLk18 0.0384 0.0667 0.327 0.568

105‐BtwdLk5 0.0574 0.0554 0.242 0.233

105‐DeeratMC 0.0250 0.0285 0.269 0.307

105‐DeerBasin 0.0265 0.0358 0.349 0.473

105‐DeerDam 0.0751 0.0847 2.008 2.264

105‐DSBtwdLk14 0.0445 0.0350 0.346 0.272

105‐DSBtwdLk18 0.0275 0.0575 0.077 0.161

105‐DSBtwdLk5 0.0322 0.0407 0.211 0.267

105‐DSDeerBasin 0.0264 0.0351 0.198 0.265

105‐DSDeerDam 0.0557 0.0605 0.961 1.045

106‐DryBasin 0.0328 0.0446 0.616 0.838

106‐DryDam 0.0720 0.0779 1.324 1.432

107‐7940Basin 0.0245 0.0380 0.260 0.403

107‐8085Basin 0.0268 0.0322 0.119 0.143

107‐DS8085Basin 0.0262 0.0453 0.174 0.301

107‐DSVYNorthSM 0.0581 0.0743 0.033 0.043

107‐DSVYSouthSM 0.0404 0.0850 0.019 0.039

107‐VYNorth 0.0624 0.0726 0.820 0.956

107‐VYSouth 0.0561 0.0834 0.433 0.643

108‐EofMCDam 0.0748 0.0755 0.955 0.964

108‐MCDam 0.0748 0.0805 6.160 6.624

30A‐2 0.0257 0.0360 0.095 0.133

30A‐BrownBas 0.0250 0.0280 0.295 0.330

30A‐LaurelBas 0.0249 0.0372 0.224 0.336

30C‐DSFVBasin 0.0267 0.0519 0.377 0.732

30C‐DSLibertyBas 0.0273 0.0335 0.489 0.601

30C‐FairviewBas 0.0235 0.0297 0.415 0.525

30C‐LibertyBas 0.0272 0.0280 0.411 0.423

52A‐1 0.0245 0.0389 0.497 0.789

52A‐2 0.0248 0.0391 0.263 0.414

52B‐1 0.0225 0.0303 0.349 0.469

52C‐Basin1 0.0246 0.0400 0.505 0.819

52C‐Basin2 0.0251 0.0305 0.307 0.373

July 2011 61


Table A2‐9. Marsh Creek Original and Revised Manning’s n and Lag Time by Subbasin (cont.)





52C‐Basin3 0.0239 0.0652 0.400 1.090

52C‐Lowest 0.0239 0.0384 0.296 0.476

52D‐Outlet 0.0318 0.0516 0.624 1.011

MC‐118.5 0.0253 0.0372 0.257 0.377

MC‐137.0 0.0245 0.0300 0.345 0.422

MC‐139.0 0.0240 0.0280 0.150 0.175

MC‐160.0 0.0251 0.0284 0.232 0.262

MC‐184.0 0.0258 0.0282 0.359 0.392

MC‐198.0 0.0329 0.0487 0.355 0.525

MC‐217.5 0.0445 0.0833 0.216 0.405

MC‐236.5 0.0280 0.0356 0.344 0.437

MC‐252.0 0.0265 0.0306 0.111 0.128

MC‐254.0 0.0236 0.0280 0.099 0.117

MC‐259.0 0.0228 0.0280 0.090 0.110

MC‐263.0 0.0227 0.0280 0.075 0.092

MC‐287.0 0.0268 0.0280 0.148 0.155

MC‐305.5 0.0215 0.0280 0.121 0.157

MC‐312.0 0.0269 0.0280 0.322 0.335

MC‐312.5 0.0238 0.0280 0.138 0.163

MC‐331.1 0.0271 0.0281 0.100 0.104

MC‐338.5 0.0287 0.0280 0.173 0.169

MC‐363.6 0.0236 0.0281 0.067 0.079

MC‐372.0 0.0252 0.0280 0.248 0.276

MC‐379.5 0.0252 0.0280 0.087 0.097

MC‐380.5 0.0250 0.0280 0.067 0.076

MC‐386.0 0.0252 0.0280 0.096 0.107

MC‐387.0 0.0251 0.0280 0.077 0.086

MC‐389.0 0.0249 0.0280 0.073 0.081

MC‐393.4 0.0251 0.0280 0.101 0.112

MC‐401.0 0.0253 0.0382 0.413 0.624

MC‐404.2 0.0255 0.0293 0.307 0.352

MC‐404.7 0.0251 0.0280 0.177 0.197

MC‐at30ALaruelOut 0.0243 0.0407 0.209 0.350

MC‐at30Coutlet 0.0234 0.0316 0.121 0.164

MC‐at52C 0.0538 0.0288 0.185 0.099

MC‐at52D‐Outlet 0.0464 0.0280 0.187 0.113

MC‐at52D‐OutletSM 0.0237 0.0280 0.005 0.006

MC‐at8085Basin 0.0304 0.0839 0.172 0.476

July 2011 62


Table A2‐9. Marsh Creek Original and Revised Manning’s n and Lag Time by Subbasin (cont.)





MC‐atDS7940Basin 0.0428 0.0794 0.379 0.702

MC‐atDS7940BasSM 0.0259 0.0280 0.020 0.021

MC‐atVYNorth 0.0465 0.0681 0.364 0.532

MC‐atVYSouth 0.0739 0.0752 0.399 0.406

MC‐DSECCID 0.0553 0.0399 0.325 0.235

MC‐ECCID 0.0435 0.0816 0.551 1.032

MC‐Outlet3 0.0227 0.0280 0.111 0.137

MC‐US30ALaruelOut 0.0236 0.0280 0.081 0.097

July 2011 63


Appendix A‐3

Reservoir Information

July 2011 64


EDITS TO RESERVOIR ELEMENTS IN THE MARSH CREEK MODEL Mark Boucher from the Contra Costa Flood Control and Water Conservation District provided a spreadsheet with the elevation‐storage‐discharge information for all of the reservoirs in the Marsh Creek model. Some of the reservoir curves had to be extended because the elevation computed with the HEC‐HMS model was above the elevation originally in the model. If data was available from the County then the curves were extended using that information. If there was no additional information then a combination of extrapolation and/or topographic information was used to extend the basin curves. The information below explains where the reservoir data came from and what changes were made. Basin Name in Model: 107‐VYSouth Name from County information: Vinyards South Basin Source Information: County reports source as November 2005 Report by Balance Hydrologics for “Vinyards at Marsh Creek” Notes: the information provided by Contra Costa County was extended using the topographic data. Figure A3‐1 below shows the 107‐VYSouth basin and from the contour data it appears that the elevation‐storage‐discharge data provided by the county can be extrapolated to about elevation 137.5. At 138 the basin will start to experience weir flow. The elevation‐storage relationship up to elevation 138 was maintained but at 138 the discharge would start to increase to account for the weir flow. At this point the discharge at 138 was calculated using the standard weir flow equation.

/ For this situation: C = 2.6 (average coefficient for a broad crested weir) L = 86 feet (measured in GIS) H = 0.5 feet Q = 79.0 cfs

July 2011 65


Figure A3‐1. 107‐VY Basin with contours and weir location Figures A3‐2 and A3‐3 below show the changes to the elevation‐storage and storage‐discharge curves. The values are listed in the table A3‐1.

Figure A3‐2. Reservoir 107‐VY South Storage‐Discharge Curve

0

10

20

30

40

50

60

70

80

90

0 5 10 15 20 25 30 35

Storage

(ac‐ft)

Discharge (cfs)

107‐VY South Storage‐Discharge

Modified Storage‐Discharge Curve Original Storage‐Discharge Curve

July 2011 66


Figure A3‐3 Reservoir 107‐VYSouth Elevation‐Storage Curve

Table A3‐1. Reservoir 107‐VYSouth Elevation‐Storage‐Discharge Data

Elevation (ft) Storage (ac‐ft) Discharge (cfs)

122 0 0

124 2.1 1.6

126 4.6 2.3

128 7.6 11.7

130 11.1 16.9

132 15 20.7

134 19.6 23.9

136 24.7 26.7

138 30.3 79.0

The last data point was added to the paired data tables in the model.

0

5

10

15

20

25

30

35

40

120 125 130 135 140 145

Storage

(ac‐ft)

Elevation (ft)

107‐VY South Elevation‐Storage

Modified Elevation‐Storage Curve Original Elevation‐Storage Curve

July 2011 67


Basin Name in Model: 107‐VYNorth Name from County information: Vinyards North Basin Source Information: County reports source as November 2005 Report by Balance Hydrologics for “Vinyards at Marsh Creek” Notes: A review of the aerial photo and topographic data shows an elevation of about 124 to 124.5 for most of the road that surrounds the basin. It was assumed that water will not overflow the basin at elevation 124 so the two curves were extended slightly to 124 and the corresponding data entered into the model. Figures A3‐4 and A3‐5 below show the changes to the elevation‐storage and storage‐discharge curves. The values are listed in the table A3‐2.

Figure A3‐4. Reservoir 107‐VYNorth Storage‐Discharge Curve

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80

Discharge

(cfs)

Storage (ac‐ft)

107‐VYNorth Storage‐Discharge


July 2011 68


Figure A3‐5. Reservoir 107‐VYNorth Elevation‐Discharge Curve

Table A3‐2. Reservoir 107‐VYNorth Elevation‐Storage‐Discharge Data


107 0 0

108 0.6 0.7

110 4.5 1.3

111 7.7 1.6

112 11.3 5.4

113.2 15.3 11.4

114 18.7 13.7

116 26.9 21.8 118 35.7 33.2 120 45.3 40.4 122 56 46.3

124 67.4 52.2


0

10

20

30

40

50

60

70

80

105 110 115 120 125

Storage

(ac‐ft)

Elevation (ft)

107‐VYNorth Elevation‐Storage


July 2011 69


Basin Name in Model: 105 Deer Crk Basin Name from County information: None Source Information: County reports source as HYDRO2 Model in the “Deer Creek Hydrology Report” dated November 10, 1997, File No. 3105‐04 Notes: the information from the County was extended by using ArcGIS to create 0.5 foot contours from the DEMs provided by the County. The area was calculated at the 95 and 98 contours and additional storage values were calculated. The equation in the County’s spreadsheet was used to calculate the corresponding discharge values. A review of the topography and a review of the area in Google StreetView seems to show that water will not start flooding over the roads until the elevation reaches about 99 feet so it was assumed that the discharge equation used by the County would still be accurate at 98 feet. Figures A3‐6 and A3‐7 below show the changes to the elevation‐storage and storage‐discharge curves. The values are listed in the table A3‐3.

Figure A3‐6. Reservoir Deer Crk Storage‐Discharge Curve

0

50

100

150

200

250

0 20 40 60 80 100 120 140 160 180

Discharge

(cfs)

Storage (ac‐ft)

Deer Crk Basin Storage‐Discharge


July 2011 70


Figure A3‐7. Reservoir Deer Crk Basin Elevation‐Storage Curve

Table A3‐3. Reservoir Deer Crk Elevation‐Storage‐Discharge Data


77 0 0

79 0 48.12

81 6.5 83.34

83 17.5 107.59

85 33.5 127.31

87 48.5 144.35

89 66 159.59

91 87 173.49 93 105.7 186.36

95 120.7 198.4 98 154.1 215.2

The last two data points were added to the paired data tables in the model.

020406080

100120140160180

70 75 80 85 90 95 100

Storage

(ac‐ft)

Elevation (ft)

Deer Crk Basin Elevation‐Storage


July 2011 71


Basin Name in Model: 30C Fairview Name from County information: None Source Information: County reports source as HYDRO2 Model of unknown date Notes: the information from the County was extended by using ArcGIS to create 0.5 foot contours from the DEMs. It appears the basin will not experience weir flow until the water reaches about 98.5so the elevation‐storage‐discharges curves were extended slightly up to 98.5 feet. At 99 the basin will start to experience weir flow with water overflowing to the east‐northeast toward the Union Pacific Railroad, see Figure A3‐8 below. The elevation‐storage relationship up to elevation 98.5 was maintained but at 99 the discharge would start to increase to account for the weir flow. At this point the discharge at 99 was calculated using the standard weir flow equation noted above assuming an effective weir length of 500 feet. Figures A3‐9 and A3‐10 below show the changes to the elevation‐storage and storage‐discharge curves. The values are listed in the table A3‐4.

Figure A3‐8. 30C‐Fairview Basin with contours and weir location

July 2011 72


Figure A3‐9. Reservoir 30C Fairview Storage‐Discharge

Figure A3‐10. Reservoir 30C Fairview Elevation‐Storage Curve

0

100

200

300

400

500

0 20 40 60 80 100 120 140

Discharge

(cfs)

Storage (ac‐ft)

30C‐Fairview Storage‐Discharge


0

20

40

60

80

100

120

82 84 86 88 90 92 94 96 98 100

Storage

(ac‐ft)

Elevation (ft)

30C‐Fairview Elevation‐Storage


July 2011 73


Table A3‐4. Reservoir 30C Fairview Elevation‐Storage‐Discharge Data


83.8 0 0

84 0.001 1.2

84.8 3.42 6

85.8 7.7 13.91

87.8 20 29.73

88.1 22.06 32.1

89.8 33.7 41.96

90.1 35.94 43.7 91.8 48.6 51.44 92.1 51.03 52.8 93.8 64.8 59.43 94.1 67.43 60.6 95.8 82.3 66.47 96.1 84.9 67.67 97.8 99.9 73.67

98.5 110 79.67 99 125 460

The last two data points were added to the paired data tables in the model.

July 2011 74


Basin Name in Model: 30C Freedom (basin shapefile names this as 30C LibertyBas) Name from County information: None Source Information: County reports source as HYDRO2 Model of unknown date Notes: the information from the County was extended by using ArcGIS to create 0.5 foot contours from the DEMs. It appears the basin will not experience weir flow until the water reaches about 80.5 so the original elevation‐storage‐discharges curves were maintained up to 80 feet. At 80.5 it was assumed that the basin will start to experience weir flow with water overflowing to the east toward O’Hara Street , see Figure A3‐11 below. The elevation‐storage relationship up to elevation 80.5 was maintained but at 80.5 the discharge would start to increase to account for the weir flow. At this point the discharge at 80.5 was calculated using the standard weir flow equation noted above assuming an effective weir length of 150 feet. Figures A3‐9 and A3‐10 below show the changes to the elevation‐storage and storage‐discharge curves. The values are listed in the table A3‐5.

Figure A3‐11. 30CFreedom Basin with contours and weir location

July 2011 75


Figure A3‐12. Reservoir 30C Freedom Storage‐Discharge Curve

Figure A3‐13. Reservoir 30C Freedom Elevation‐Storage Curve

050

100150200250300350400450

0 10 20 30 40 50 60 70 80 90

Discharge

(cfs)

Storage (ac‐ft)

30C Freedom Storage‐Discharge


0

20

40

60

80

100

66 68 70 72 74 76 78 80 82

Storage

(ac‐ft)

Elevation (ft)

30C Freedom Elevation‐Storage


July 2011 76


Table A3‐5. Reservoir 30C Freedom Elevation‐Storage‐Discharge Data


66 0 0

66.3 0.15 0

68 1 17.94

68.3 2.24 21.1

70 9.3 28.75

70.1 9.85 29.2

72 20.3 35.9

74 32.4 41.8 76 45.6 46.9 78 59.9 51.6 80 74.4 56.6

80.5 80 390


July 2011 77


Basin Name in Model: 30A Laurel Basin Name from County information: None Source Information: County reports source as HYDRO2 Model of unknown date Notes: the information from the County was extended by using ArcGIS to create 0.5 foot contours from the DEMs. Based on the topographic data it appears that the basin will be overflowing at 33 feet but due to the heavy vegetation to the northwest of the basin the LIDAR may be slightly off. It was assumed that the basin will not start overflowing until it reached 33.5 feet and then it will overflow to the northwest. Figure A3‐ 14 below shows the 33 contour location and the assumed direction of overflow. The elevation‐storage relationship up to elevation 33.5 was maintained but at 33.5 the discharge would start to increase to account for the weir flow. At this point the discharge at 33.5 was calculated using the standard weir flow equation noted above assuming an effective weir length of 235 feet, figure A3‐15 shows the location of the weir. Figures A3‐16 and A3‐17 below show the changes to the elevation‐storage and storage‐discharge curves. The values are listed in the table A3‐6.

Figure A3‐14. 30ALaurel Basin with contours and assumed direction of overflow

July 2011 78


Figure A3‐15. 30A Laurel Basin with contours and weir location

Figure A3‐16. Reservoir 30A Laurel Bas Storage‐Discharge Curve

0

50

100

150

200

250

0 20 40 60 80 100 120

Discharge

(cfs)

Storage (ac‐ft)

30A Laurel Storage‐Discharge


July 2011 79


Figure A3‐17. Reservoir 30A Laurel Bas Elevation‐Storage Curve

Table A3‐5. Reservoir 30A Laurel Bas Elevation‐Storage‐Discharge Data


20 0 0

21 0.1 4.6

22 0.3 8.5

23 1.9 10.5

24 6.9 12.2

25 14.2 13.6

26 22.4 15.1

27 31 16.4 28 40.3 17.7 29 50.3 18.8 30 61 19.8 31 72.4 20.8

32 84.3 21.7

33 96.2 22.6

33.5 108.2 216


0

20

40

60

80

100

120

20 22 24 26 28 30 32 34 36

Storage

(ac‐ft)

Elevation (ft)

30A Laurel Elevation‐Storage


July 2011 80


Basin Name in Model: 104‐UpSCBasin Source Information: topographic information and Sand Creek Storm Drain Improvements construction drawings dated July 1, 1994 Issue: The elevation‐storage‐discharge information in the model provided by the County reflected planned improvements to the Sand Creek basin. Since FEMA models existing conditions, the current elevation‐storage‐discharge relationships had to be calculated. To calculate the elevation‐storage relationships the submitted DEM was contoured at 0.5 feet intervals and the area of the basin at each 0.5 feet increment was totaled. To calculate the volume at each 0.5 foot increment the following formula was used:

6

Where: H = height between three successive 0.5 foot elevation increments B1 = surface area of the base elevation B2 = surface area of the middle elevation B3 = surface area of the top elevation Total the cumulative storage volume at each 0.5 foot elevation yields the following elevation‐storage relationship, see Figure A3‐17. The data used in the model is in Table A3‐6.

Figure A3‐17. Sand Creek Elevation‐Storage Curve

0

20

40

60

80

100

120

140

160

180

200

172 174 176 178 180 182 184 186 188 190

Elevation (ft)

Storage (acre‐ft)

Sand Creek Elevation‐Storage

July 2011 81


Table A3‐5. Sand Creek Reservoir Elevation‐Storage Data

Elevation (ft) Storage (ac‐ft)

172.5 0.000 173.0 0.000 174.0 0.040 175.0 0.556 176.0 2.169 177.0 5.326 178.0 10.808 179.0 19.347 180.0 31.388 181.0 46.312 182.0 63.183 183.0 81.540 184.0 101.300 185.0 121.774 186.0 142.722 186.5 153.235 187.0 163.763 187.5 174.305 188.0 184.854

To calculate the discharge from the basin the outlet structures option was used. Contra Costa County provided a set of drawings titled “Sand Creek Storm Drain Improvements” dated July 1, 1994 that included information regarding the outlet from the basin. The major outlet is 42.4 feet of corrugated metal pipe that measures 54”. The following information was used for this outlet, entrance and exit coefficients and Manning’s n were obtained from the HEC‐RAS hydraulic reference manual. The scale was based on aerial photos and the construction drawings of the outlet.

Table A3‐6. Outlet Structure Information

Shape Circular

Chart 2: corrugated metal pipe

Scale 2: mitered to conform to slope

Length (ft) 42.4

Diameter (ft) 4.5

Inlet Elevation (ft) 172.5

Entrance Coefficient 0.7

Outlet Elevation (ft) 171

Exit Coefficient 1

Mannings n 0.024

July 2011 82


The construction drawings and photos also show two risers that act as emergency outlets but according to the drawings the elevation of the tops of the risers is 188, which is above the overtopping elevation for the basin so these risers were not included in the model. Based on the topographic data is appears that the basin will start to overtop to the east at an elevation just above 186 feet, flowing directly to Marsh Creek. To account for this the dam over tops function was also used. Figure A3‐18 shows the basin with contours and the assumed weir location and length.

Figure A3‐18. Sand Creek basin with contours and weir location

It was assumed that weir flow would begin at 186 feet and the length of the weir was estimated at 530 feet with a typical broad crested weir coefficient of 2.6.

July 2011 83


LOS VAQUEROS RESERVOIR INFORMATION The Lost Vaqueros Reservoir in Kellogg Creek was modeled using the elevation‐storage data from the 2002 LOMR model. Below is an excerpt from that HEC‐1 model including the subbasin information of the contributing local drainage to the reservoir and the reservoir itself. KK 726 KO 0 21 0.25 KM RUNOFF FROM SUBBASIN 726 PB 4.8 IN 60 01NOV02 1200 PC 0 0.02 0.05 0.082 0.116 0.156 0.206 0.27 0.42 0.52 PC 0.58 0.62 0.66 0.70 0.74 0.77 0.80 0.83 0.86 0.89 PC 0.91 0.94 0.96 0.98 1.00 BA 18.8 LS 0 85.0 UD 1.07 * ****************************************************************************** * ** * ** * ** KK DAM KO 0 22 0.25 KM LOS VAQUEROS DAM AS BUILT RS 1 ELEV 472 SV 0 4710 11080 19860 31180 45100 55840 67640 80460 SV 87270 94360 101710 109330 117220 125380 133820 142540 SE 350 365 380 395 410 425 435 445 455 SE 460 465 470 475 480 485 490 495 SS 472 15 3.6 1.5 ST 487 2000 3.1 1.5

July 2011 84


Appendix A‐4

Reach Information

July 2011 85


Table A4-1. Brushy Creek Reach Information

Reach Length (ft) Slope (ft/ft) Manning’s n Shape Bottom Width (Ft)

Side Slope (xH:1V)

1 13,736 0.035 0.035 Trapezoid 15 2 2 6,544 0.015 0.035 Trapezoid 10 2 3 7,325 0.023 0.035 Trapezoid 15 2 4 2,852 0.023 0.035 Trapezoid 15 2 5 6,116 0.011 0.035 Trapezoid 10 2 6 14,651 0.004 0.035 Trapezoid 10 2 7 13,620 0.008 0.035 Trapezoid 10 2 8 15,513 0.0026 0.035 Trapezoid 10 2

Table A4-2. Frisk Creek Reach Information

Reach Length (ft) Slope (ft/ft) Manning’s n Shape Bottom

Width (Ft) Side Slope (xH:1V)

1 11,433 0.0054 0.035 Trapezoid 20 2 2 6,580 0.004 0.035 Trapezoid 20 2 3 14,788 0.0015 0.035 Trapezoid 20 2 4 6,979 0.0001 0.035 Trapezoid 20 2

Table A4-3. Kellogg Creek Reach Information



1 11,433 0.0054 0.035 Trapezoid 20 2 2 6,580 0.004 0.035 Trapezoid 20 2 3 14,788 0.0015 0.035 Trapezoid 20 2 4 6,979 0.0001 0.035 Trapezoid 20 2 5 3408 0.0012 0.035 Trapezoid 25 2 6 18,881 0.0023 0.04 Trapezoid 20 2 7 9,201 0.0033 0.04 Trapezoid 15 2 8 4,451 0.0018 0.035 Trapezoid 15 2

Table A4-4. Mt. Diablo Creek Reach Information



1 3,872 0.008 0.035 Trapezoid 25 2 2 3,073 0.006 0.035 Trapezoid 25 2 3 21,424 0.005 0.035 Trapezoid 25 2 4 12,064 0.004 0.035 Trapezoid 25 2 5 1,940 0.001 0.035 Trapezoid 25 1 6 2,840 0.001 0.035 Trapezoid 25 1

July 2011 86


TSDN CATEGORY DATA TYPE DATA SUBMITTED

Engineering Analyses (Hydrologic Analyses)

Hydrologic Analyses Index X

Summary Report of Hydrologic Analyses X Computer Models, Calculations and Execution

X

Summary Report for Independent QA/QC

July 2011 87


Appendix B‐2

Contact Report List

July 2011 88


CONTACT REPORT INDEX

Community Name and State:

Contra Costa County, California

Community ID No. 06013

Compiled By: Katherine Labuhn

Date TSDN Submitted:

Report Date Report Subject Firm/Agency

Contacted

December 21, 2010 Marsh Creek hydrology Contra Costa Flood Control District

April 18, 2011 Flows from Los Vaqueros and Mallard Reservoirs Contra Costa County Water Department

July 2011 89


Appendix B‐3

Hydrologic Analyses Index

July 2011 90


HYDROLOGIC ANALYSES INDEX Community Name:

Contra Costa County, California

Community ID No.

06013

Compiled By: BakerAECOM

Date TSDN Submitted:

Flooding Source/Stream

Name

Hydrologic Method/Model

Used Method/Model Analysis

Date

Exhibit No.

Paper Copy Electronic Media

Brushy Creek HEC-HMS May 6, 2011 X

Frisk Creek HEC-HMS May 6, 2011 X

Kellogg Creek HEC-HMS May 6, 2011 X

Marsh Creek HEC-HMS May 6, 2011 X

Mt. Diablo Creek

HEC-HMS May 6, 2011

X

July 2011 91


Appendix B‐4

Certification of Compliance

July 2011 92


CERTIFICATION OF COMPLIANCE

Project Name: Contra Costa County, California Hydrologic Analysis

Statement of Work No.: HSFEHQ-09-D-0368 Task Order HSFE09-09-J-0001

Interagency Agreement No.:

CTP Agreement No.:

Certification Date:

Tasks/Activities Covered by This Certification (Check All That Apply)

❏ Entire Project

❏ Topographic Data Development

❏ Hydrologic Analyses

❏ Hydraulic Analyses

❏ Coastal Flood Hazard Analyses

❏ Floodplain Mapping

This is to certify that the work summarized above was completed in accordance with the statement/agreement cited above and all amendments thereto, together with all such modifications, either written or oral, as the Regional Project Officer and/or Assistance Officer or their representative have directed, as such modifications affect the statement/agreement, and that all such work has been accomplished in accordance with the provisions contained in Guidelines and Specifications for Flood Hazard Mapping Partners cited in the contract document, and in accordance with sound and accepted engineering practices within the contract provisions for respective phases of the work.

Name: Katherine Labuhn, P.E.

Title: Civil Engineer I

Firm/Agency Represented: Michael Baker Jr., Inc.

Registration No.: Virginia P.E. 0402039567

Signature:

This form must be signed by a representative of the firm contracted to perform the work who is registered as a Professional Engineer or by the responsible official of a government agency.

X

July 2011 93


Appendix C‐1 Hydrologic Analyses QA/QC Reviews

July 2011 94


Appendix D Digital Data on the MIP

J:\ R09\CALIFORNIA\CONTRA COSTA COUNTY\09-09-3059S\Hydrology\1804003 and 18050001

Correspondence General Supplemental Information