2012 hydrologic, hydraulic and water quality …...* only at libbs, mooney and mother lakes **only...
TRANSCRIPT
2012
Hydrologic, Hydraulic and Water Quality
Technical Report
April 2012
2012
Hydrologic, Hydraulic and Water Quality
Technical Report
Prepared by
Minnehaha Creek Watershed District Hydrodata Program
Water Quality Specialists II
Yvette Christianson and Kelly Dooley
Water Quality Assistants Jack Barland, Rob Brown, Zak Granata
18202 Minnetonka Boulevard
Deephaven, MN 55391 952-471-0590
www.minnehahahcreek.org
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Table of Contents
1. Introduction ................................................................................................................................1
2. Contact Information ..................................................................................................................1 3. Lake and Stream Monitoring Regimes ....................................................................................2
3.1 MCWD Lakes ..........................................................................................................2 Lake Monitoring ..........................................................................................3 Lake Elevation Monitoring ..........................................................................4
3.2 MCWD Streams .......................................................................................................5 Stream Monitoring .......................................................................................6 E. coli Monitoring ........................................................................................6 Continuous Water Level Monitoring ...........................................................9 Stormwater Monitoring ................................................................................9 USGS Continuous Flow Gauging Station ...................................................9
Precipitation Monitoring ............................................................................11 3.3 Parameter Methods and Reporting Limits ............................................................13 3.4 Quality Assurance/Quality Control Summary ......................................................14
4. Water Quality Analyses ...........................................................................................................15
4.1 Lake Water Quality Analyses ................................................................................15 Lake Water Quality Grades .......................................................................15 Carlson’s Trophic State Index ...................................................................17 Ecoregion Guidelines and Water Quality Standards for Lakes .................18 Long term Trend Analysis .........................................................................19
4.2 Stream Water Quality Analyses .............................................................................19 Ecoregion Water Quality Standards for Streams .......................................19 Chloride Standard for Streams ...................................................................20 Dissolved Oxygen Data Analysis ..............................................................20 Minnehaha Creek Discharge Calculations .................................................20 Upper Watershed Streams Discharge Calculations ...................................20 E. coli Data Analysis..................................................................................20
5. Precipitation and Groundwater Levels ..................................................................................21
5.1 Precipitation Throughout MCWD .........................................................................21 5.2 Deep Well Aquifers ...............................................................................................25
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Figures
1 Locations of E. coli Sampling ..................................................................................8 2 Locations of Continuous Water Level Monitoring and Storm Water Sampling ...10 3 Precipitation Monitoring Locations for MCWD....................................................12 4 Comparison of Monthly 2012 precipitation and Long-term (1971-2000)
Average Precipitation Data for MSP Station .........................................................21 5 Comparison of Annual Precipitation for MSP and NOAA-NWS
(1960-2012)............................................................................................................22 6 Groundwater Well Elevation for MnDNR Wells: Mound (27043) and
St. Louis Park (27041) ...........................................................................................26 7 Groundwater Well Elevation for MnDNR Wells: Minneapolis (27036) and
St. Bonifacius (27044) ..........................................................................................27 8. Groundwater Well Elevation for MnDNR Well: Orono (27010) .........................28
Tables 1 MCWD Surface Water Monitoring Program Contacts ............................................1 2 Lake Minnetonka and Upper Watershed Sampling Schedule .................................2
3 MCWD Sampling Schedule for the Limited Access and CLMI Lakes Water Quality Parameters ........................................................................................3
4 Links to Other Organizations Water Quality Monitoring Websites .......................3 5 Water Quality Samples Profile Regime ...................................................................4 6 2012 MCWD Lakes Elevation Summary ................................................................5 7 MCWD Sampling Schedule for the Stream Water Quality Parameters .................6 8 Parameter Methods and Reporting Limits .............................................................13
9 Water Quality Parameters lake Grade Determination Ranges ...............................16 10 MCWD Overall Lake Grade Determination Ranges .............................................16 11 Lake Water Quality Grade Description ................................................................17 12 TSI Determination Table ......................................................................................17 13 Description of the Carlson’s Trophic State Index..................................................18
14 North Central Hardwood Forest Ecoregion Water Quality Guidelines and Water Quality Standards for Lakes for Shallow and Deep Lakes (MPCA, 2012) ...........19
15 2012 Monthly Precipitation from Stations Monitored by MCWD And Citizen Precipitation Recorders (CPR) ..........................................................23
16 2012 Monthly Precipitation DATA for NWS and MSP Stations and Long-term Average Precipitation for MSP Station ..............................................23
17 Annual Precipitation Data for MSP and NOAA-NWS (1960-2012).....................24 18 Long-term Groundwater Monitoring MnDNR wells in MCWD ...........................25
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6. Subwatersheds of Minnehaha Creek Watershed District ....................................................29
A. Lake Minnetonka Subwatershed .............................................................................30 B. Minnehaha Creek Subwatershed ...........................................................................170 C. Christmas Lake Subwatershed ..............................................................................272 D. Lake Virginia Subwatershed .................................................................................284 E. Schutz Lake Subwatershed ....................................................................................310 F. Six Mile Marsh Subwatershed ...............................................................................320 G. Langdon Lake Subwatershed ................................................................................412 H. Dutch Lake Subwatershed ....................................................................................429 I. Painter Creek Subwatershed ...................................................................................442 J. Long Lake Creek Subwatershed .............................................................................468 K. Gleason Lake Subwatershed .................................................................................500
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1. INTRODUCTION
The Hydrodata Program of Minnehaha Creek Watershed District (MCWD) is a cooperative
effort with Minneapolis Park and Recreation Board (MPRB), Three Rivers Park District (TRPD),
Lake Minnetonka Conservation District (LMCD), Metropolitan Council Environmental Services
(MCES), Minnesota Pollution Control Agency (MPCA), and Minnesota Department of Natural
Resources (MnDNR). The water quality data of the lakes and streams that was collected by the
Hydrodata Program and the partners in 2012 are presented in this Technical Appendix.
2. CONTACT INFORMATION
Table 1. MCWD Surface Water Monitoring Program Contacts Name Title/Affiliation Address† Phone/e–mail L. Eric Evenson District Administrator 18202 Minnetonka Blvd.
Deephaven, MN 55391 952–641–4521
David Mandt [email protected]
Director of Operations and Programs
18202 Minnetonka Blvd. Deephaven, MN 55391
952–641–4503;
Yvette Christianson
[email protected] Water Quality Specialist
18202 Minnetonka Blvd. Deephaven, MN 55391
952–641–4514;
Kelly Dooley [email protected]
Water Quality Specialist
18202 Minnetonka Blvd. Deephaven, MN 55391
952–641–4515;
†By June 2013, Minnehaha Creek Watershed District’s address will be 15320 Minnetonka Blvd, Minnetonka, MN 55345
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3. LAKE AND STREAM MONITORING SAMPLING REGIMES
3.1 MCWD Lakes
Lakes within the MCWD are classified by the MPCA as Class 2B lakes meaning they are
protected for aquatic life and recreation. MCWD water quality staff monitored 27 bays on Lake
Minnetonka, 11 upper watershed lakes, and 18 limited access lakes. MCWD’s Citizen Lake
Monitoring Initiative (CLMI), recruited and trained volunteers to monitor an additional 6 lakes
throughout the watershed. Sampling schedules were predetermined prior to the monitoring
season (Table 2 & 3).
Table 2. Lake Minnetonka and Upper Watershed Sampling Schedule
Parameter Winter* April May-Sept October
Chloride Once Once Once a Month Once
Chlorophyll-a Not
Sampled Once Twice a Month Once
Conductivity** Once Once Twice a Month Once
Dissolved Oxygen** Once Once Twice a Month Once
pH** Once Once Twice a Month Once
Secchi Depth Once Once Twice a Month Once
Silica Not
Sampled Once Twice a Month Once
Temperature** Once Once Twice a Month Once
TKN, NOx Not
Sampled Once Twice a Month Once
TSS Not
Sampled Once Twice a Month Once
TP, SRP, TN Not
Sampled Once Twice a Month Once
* Only lakes being monitored as part of MPCA chloride study – ends in November 2013 ** Lake Profile
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Table 3. MCWD Sampling Schedule for the Limited Access and CLMI Lakes Water Quality Parameters
Parameter May-Sept Chloride* Once a Month Chlorophyll-a Once a Month Secchi Depth Once a Month TP, SRP Once a Month TN** Once a Month TSS*** Once a Month Temperature** Once a Month Dissolved Oxygen** Once a Month pH** Once a Month Conductivity** Once a Month * Only at Libbs, Mooney and Mother lakes
**Only at the Six Mile Marsh Subwatershed limited access lakes *** Only at Lundsten N & S, Marsh, Mud and Carl Krey lakes
The Minneapolis Park and Recreation Board (MPRB) monitored 10 lakes within the city of
Minneapolis (note: Brownie Lake and Grass Lake area monitored on the even years). Three
Rivers Park District (TRPD) monitored four lakes within the District. The Metropolitan Council
Environmental Services (MCES) governs the Citizen-Assisted lake Monitoring Program
(CAMP). CAMP volunteers monitored five lakes within the watershed in 2012. Further
information about the lake monitoring conducted by MPRB, TRPD and MCES CAMP can be
found on their websites (Table 4).
Table 4. Links to Other Organizations Water Quality Monitoring Websites
Organization Link to Monitoring Report Webpage Minneapolis Park and Recreation Board http://www.minneapolisparks.org/default.asp?PageID=791
Three Rivers Park District http://www.threeriversparks.org/natural-resources/water-resources-management.aspx
Metropolitan Council Environmental Services
http://www.metrocouncil.org/environment/RiversLakes/Lakes/index.htm http://www.metrocouncil.org/Wastewater-Water/Services/Water-Quality-Management.aspx
Lake Monitoring: On Lake Minnetonka and the upper watershed lakes, a hand-held GPS unit
was used to locate the deepest point in each lake (monitoring site). Physical parameters for each
site were taken with a 6820-V2 YSI multi-parameter sonde. The sonde measured temperature
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(oC), dissolved oxygen (DO), pH, and specific conductivity (µS/cm) from the water surface to
the bottom of the site at one meter increments.
Water samples were collected within the first two meters of the surface with a 2-meter composite
sampling tube. A Van Dorn water sampler collected water one meter below the thermocline, if
deep enough, as well as one meter from the bottom of the lake at all locations (Table 5). Data
collected for each lake is presented in their respective subwatershed.
Table 5. Water Quality Samples Profile Regime
Surface TP, SRP, TN, TKN, NOx, TSS, Cl , Chlorophyll-a, Silica, Secchi depth
Thermocline TP, SRP
Bottom TP, SRP, Cl
Note: Thermocline samples are only collected at 7 sites on Lake Minnetonka and at 3 Upper Watershed Lakes
On the limited access lakes, a hand-held GPS unit was used to locate the deepest point on the
lake (monitoring site), and the canoe was then stationed with an anchor. For the citizen lake
monitoring initiative (CLMI) monitors, they located the deepest point on their lakes by using
three reference points. CLMI monitors measured the physical parameters at the surface of each
site with a Taylor digital hand-held thermometer. The physical parameters limited access lakes
were measured with 6820-V2 sonde. Grab water samples were collected within the first meter of
the surface at all the limited lake sites (Table 3). Data collected for each lake is presented in
their respective subwatershed.
Lake Elevation Monitoring: Lake elevation was monitored on Lake Minnetonka in Grays Bay,
just west of the Grays Bay Dam and at 19 additional lakes throughout MCWD (Table 6). The
lake elevation data is collected weekly and submitted to the MnDNR.
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Table 6. 2012 MCWD Lakes Elevation Summary
Lake OHW
(ft, NVGD)
Maximum Lake
Elevation (ft, NGVD 29)
Minimum Lake
Elevation (ft, NGVD 29)
Christmas 932.77 931.77 930.05 Church N/A 949.99 947.82 Dutch 939.20 939.67 938.16 Galpin 943.14 943.22 941.05 Gleason 944.10 944.63 942.70 Holy Name 993.70 993.75 992.16 Kelser's Pond 956.50 958.27 956.81 Langdon 932.10 931.93 930.41 Long 944.30 945.00 943.57 Lydiard 970.90 970.90 969.37 Minnewashta 944.50 945.15 943.48 Parley 930.60 929.74 927.64 Saunders 944.30 946.10 944.66 Snyder 972.30 970.68 968.18 St. Joe 945.20 946.88 945.33 Stone 947.10 948.05 946.74 Tamarack 965.50 967.54 965.61 Wassermann 944.30 945.72 943.36 Zumbra 943.30 941.82 939.88
OHW data available on MnDNR Lake Finder website (http://www.dnr.state.mn.us/lakefind/index.html)
3.2 MCWD Streams Stream flow was measured and water quality samples were collected at 10 sites along Minnehaha
Creek and at 31 sites on 12 tributaries to major streams in the upper watershed, draining to Lake
Minnetonka. Sampling schedules were predetermined prior to the monitoring season (Table 7).
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Table 7. MCWD Sampling Schedule for the Stream Water Quality Parameters Parameter Winter March - Nov
Chloride 2-3 Times Once a Month Conductivity 2-3 Times Weekly Dissolved Oxygen Not Sampled Weekly Escherichia Coli Not Sampled Weekly (April - Oct) pH Not Sampled Weekly Silica Not Sampled As Needed TSS Not Sampled Twice a Month Temperature 2-3 Times Weekly TN Not Sampled Once a Month TP, SRP Not Sampled Weekly
Stream Monitoring: Stream discharge rates were measured using a SonTek Flow Tracker ADV
(Acoustic Doppler Velocimeter). Water temperature, dissolved oxygen (DO), pH, and
conductivity were measured using an YSI 556 multi probe meter. The DO measurements are
discrete and do not take into account diurnal variation, and do not reflect the minimum daily DO
concentrations (Table 7). Data collected for each stream is presented in their respective
subwatershed. Located under the Browndale Avenue Bridge in Edina, the Browndale Dam
(CMH03) is roughly at the creek’s midpoint between Lake Minnetonka and the Mississippi
River. The small impoundment created by the dam is often referred to as the Mill Pond. The
dam is an ogee-crested weir, which offers a simple and reliable means for calculating stream
discharges based on measured water surface elevations upstream of the dam. Three weekly
manual elevation readings were recorded by the City of Edina.
E. coli Monitoring: E. coli concentrations are indicators of the potential for human illness
contracted through full body contact with surface water. A map of the E. coli monitoring sites is
presented in Figure 1. Water samples are located at specific locations and delivered to Three
Rivers Parks District Laboratory for analysis.
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Minnehaha Creek E. coli Monitoring Sites
Name Site
Grays Bay Outflow CMH07 I-494 Ramps CMH19 West 34th St. CMH02 Excelsior Blvd CMH11 Browndale Dam CMH03 West 56th St. CMH04 Xerxes Ave. CMH15 21st Ave CMH24 28th Ave. CMH18 Hiawatha Ave. CMH06
Upper Watershed E. coli Monitoring Sites
Name Site
Six Mile Ck Hwy 7 Highland CSI02 Painter Ck CR110 Jennings Bay CPA05 Painter Ck W Branch Rd CPA01 Painter Ck Painter Marsh Outlet CPA04
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Figure 1. Locations of E. coli Sampling
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Continuous Water Level Monitoring: Continuous water level monitoring measured at 15
minute intervals by pressure transducers was conducted at three sites on Minnehaha Creek
(CMH07, CMH19, and CMH03), two sites on Painter Creek (CPA01, CPA03), one site on Long
Lake Creek (CLO01), and one site on Six Mile Creek (CSI01). Telemetry (remote data access
up loaded to the MCWD office computer) instruments were used to access continuous water
level data from the 3 sites on Minnehaha Creek (Figure 2). The Browndale Dam site was not
accessible during the 2012 season due to technical difficulties with the phone line. The collection
began in early April 2012 and ended in October 2012.
Stormwater Monitoring: Stormwater monitoring equipment was operational at two sites on
Minnehaha Creek (Figure 2). The data will be used for defining loads, tracking trends, and
modeling for TMDLs for Minnehaha Creek and Mississippi River.
United States Geological Services (USGS) Continuous Flow Gauging Station: In 2005,
MCWD in partnership with the USGS initiated the gauging station project at the Hiawatha Ave
stream monitoring site (CMH06). In 2010, chloride and temperature probe were installed to
collect year around every fifteen minute data (real-time data) due to the creek’s chloride
impairment. In 2012, a stormwater sampler was installed to collect data that be used for
defining loads, tracking trends, and modeling for TMDLs for Minnehaha Creek and Mississippi
River.
Continuous Water Level Monitoring Sites
Name Site
Grays Bay Outflow CMH07 I-494 Ramps CMH19 Browndale Dam CMH03 Hiawatha Ave CMH06 Six Mile Ck Lunsten Lk Outlet CSI01 Painter Ck W Branch Rd CPA01 Painter Ck Deborah Dr CPA03 Long Lk Ck Outlet CLO01
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Figure 2. Locations of Continuous Water Level Monitoring and Storm Water Sampling
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Precipitation Monitoring: MCWD maintained and operated tipping bucket precipitation
gauging stations at 7 locations in and near the District (Figure 3). Water quality staff downloads
the precipitation data on monthly basis and performs the required maintenance of precipitation
gauges to ensure accurate data collection. There are currently 3 Citizen Precipitation Recorders
partnering with the MCWD (Figure 3). Precipitation is monitored daily and the data is submitted
to MCWD on a monthly basis. This data is also submitted to the Minnesota Climatology
Working Group.
Precipitation Monitoring Locations in MCWD
Name Location Site
Carver Park (MCWD) TRPD Maintenance Garage PCA01 Chanhassen (NOAA) NOAA PCN02 Deephaven (MCWD) MCWD Office PDH01 Long Lake (MCWD) Long Lk City Public Works Bld PLO01¹ Maple Plain (MCWD) Wenck Office PME02 MSP Airport MSP Airport PMP03 Minneapolis (MCWD) Burrough Elementary School PMP06 Minnetonka (MCWD) City of Minnetonka Public Works PMA01 Shorewood (MCWD) Former MCWD staff's Home PSW01 Shorewood (CPR) Shorewood PSW02 Hamel (CPR) Hamel PHM01 Minneapolis (CPR) Minneapolis PMP04
Note: (CPR) stands for Citizen Precipitation Recorder
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Figure 3. Precipitation Monitoring Locations for MCWD
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3.3 Parameter Methods and Reporting Limits
Table 8. Parameter Methods and Reporting Limits
Parameter Method Reporting Limit Chloride EPA 325.2 0.5 mg/L Chlorophyll-a STANDARD METHODS 10200 H 1 μg/L Conductivity YSI Multiparameter Sonde (Streams: 556, Lakes: 6820V2) 1 μS/cm Dissolved Oxygen YSI Multiparameter Sonde (Streams: 556, Lakes: 6820V2) 0.01 mg/L Escherichia Coli EPA 9223B Nitrate + Nitrite Nitrogen EPA 353.2 0.02 mg/L pH YSI Multiparameter Sonde (Streams: 556, Lakes: 6820V2) 0.01 units Soluble Reactive Phosphorus EPA 365.3 0.003 mg/L
Temperature YSI Multiparameter Sonde (Streams: 556, Lakes: 6820V2) 0.01 °C Total Coliform EPA 9223B Total Kjeldahl Nitrogen EPA 351.2 0.5 mg/L Total Nitrogen Calculation of TKN + NO3 0.32-0.52 mg/L Total Phosphorus EPA 365.3 0.003 mg/L Total Suspended Solids STANDARD METHODS 2540 D 1 mg/L Transparency Secchi disk depth measurement 0.1 m
Note: MCWD staff followed the sampling procedures, sample preservation, and the holding time procedures described in Standard Operation Procedures (MPCA, 2010), Standard Methods (2005), US Environmental Protection Agency (US EPA, 1979 (revised 1983)). All lake and stream water samples were placed on ice in a cooler and stored at approximately 4°C after collection. Samples are then shipped to the contract laboratory for analysis within 48 hours of collection. The contract laboratory that analyzed the water samples for chemical analysis in 2012 was RMB Environmental Laboratories, Inc. The laboratory that analyzed the phytoplankton and zooplankton samples was PhycoTech, Inc.
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3.4 Quality Assurance and Quality Control Summary Sample Type Description Function Frequency
Quality Assurance Equipment Blank
Reagent-grade deionized water subject to sample collection, processing, and analysis
Used in estimating background due to sampling collection, processing, and analysis
10% of sampling trips*
Bottle Blank Reagent-grade deionized water subject to sample processing and analysis
Used in estimating background due to sample processing and analysis
Every sampling trip
Field Duplicate Duplicate of lake samples Used in estimating overall within-batch precision
Every sampling trip or 1 per 10 samples)
Laboratory Audit
Synthetic sample of natural lake or stream
Used in estimating overall within-batch precision
Alternate sampling trips
Blind Standard Standard solution with fictitious site I.D.
Estimates batch precision Every sampling trip
Quality Control Calibration Blank
Reagent-grade deionized water
Used in identifying signal drift and contamination of samples
One/lab batch
Reagent Blank Reagent-grade deionized water plus reagents
Used in identifying contamination of reagents
One/lab batch (10% of samples)
Quality Control Standard solution from source other than calibration standard
Used in determining accuracy and consistency of instrument calibration
One/lab batch
Split Samples Split of lake sample Used in determining comparability
4 times per year for 10 samples
Laboratory Duplicate
Split of sample aliquot Used in determining analytical within-batch precision of analytical lab measurements
One/lab batch (10% of samples)
Matrix Spike/Matrix Spike Duplicate
Known spike of sample Used in determining percent recovery of parameter analyzed
One/lab batch (10% of samples)
*Sampling trip is defined as a sampling cycle, or one cycle of stream samples or lake samples, and not just one day's sampling
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4. WATER QUALITY ANALYSES
4.1 Lake Water Quality Analyses
Lake water quality is analyzed using four separate methods in this report. The more recent
method is based on a Metropolitan Council Lake water quality grading system created in 1989
for the Twin Cities metro area lakes (Osgood, 1989). The second method used is the Carlson’s
Trophic State Index (TSI) and is based on a numerical index created in 1977 to determine the
nutrient status of area lakes (Carlson, R.E., 1977). The third method compares each site to the
water quality standards as established by the Minnesota Pollution Control Agency (MPCA) in
compliance with the Federal Clean Water Act of 1972 (MPCA, 2012). The final method is long-
term trend analyses of the means of Secchi depth measurements, chlorophyll-a concentration and
total phosphorus concentration.
Lake Water Quality Grades: MCWD reports lake water quality grades using the Metropolitan
Council’s grading system (Osgood, 1989). MCWD staff has determined the water quality grades
from 2006 through 2012. For each lake, seasonal means are computed for each of the three
parameters (surface total phosphorus concentration (TP), surface chlorophyll-a concentration
(Chl-a), and Secchi depth measurements (SD) from data collected from five or more monitoring
events between May through September. MCWD then compares these averages to the ranges
created from the Metropolitan Council’s grading curves. Each water quality parameter for a lake
is assigned a letter grade (Table 9). MCWD then averages these three grades by converting each
of grades to a numerical equivalent of the following: A to 5, B to 4, C to 3, D to 2, and F to 1.
The numerical values for each parameter are then averaged to determine an overall letter grade
for a lake based on grade ranges in Table 10. For example a water body receives an A grade for
total phosphorus, a B grade for chlorophyll-a, and a B grade for Secchi depth. The numerical
total of these three grades would be (5 + 4 + 4) equaling 13. The average for the three grades
would be 4.333, which would translate into a B+ for the overall lake water quality grade for the
lake. The lake water quality grades are an indicator of the perceived condition of the open water
and are considered average for lakes in a seven-county metro area (Osgood, 1989). An
interpretation of the water quality for each letter grade is in Table 11.
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Table 9. Water Quality Parameters Lake Grade Determination Ranges (Osgood 1989)
Grade Total Phosphorus
(ug/L) Grade Chlorophyll-a
(ug/L) Grade Secchi Depth
(m) A < 23 A < 10 A > 3 B 23 - 32 B 10-20 B 3.0 - 2.2 C 32 - 68 C 20 - 48 C 2.2 - 1.2 D 68 - 152 D 48 - 77 D 1.2 - 0.7 F > 152 F > 77 F < 0.7
Table 10. MCWD Overall Lake Grade Determination Ranges
Overall Grade Numerical Ranges
A 4.667 - 5.000 A- 4.334 - 4.666 B+ 4.001 - 4.333 B 3.667 - 4.000 B- 3.334 - 3.666 C+ 3.001 - 3.333 C 2.667 - 3.000 C- 2.334 - 2.666 D+ 2.001 - 2.333 D 1.667 - 2.000 D- 1.334 - 1.666 F Below 1.333
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Table 11. Lake Water Quality Grade Description
Grade Relative Ranking Description
A 90% and up Crystal clear, beautiful. These lakes are exceptional and are enjoyed recreationally without question or hesitation.
B 70 - 90% These lakes generally have good water quality but algae may limit swimming, particularly toward the end of summer.
C 30 -70% Average quality. Swimming, boating and fishing may be undesirable relatively early in the season. Algae blooms occasionally.
D 10 - 30% These lakes have severe algae problems. People are generally not interested in recreation on these lakes.
F Lowest 10% Not enjoyable. Such a lake would have several limitations to recreational use.
Carlson’s Trophic State Index: Carlson’s Trophic State Index (TSI), which measures the
productivity level of a lake or trophic state, is calculated from seasonal averages of the same
three parameters as used by the Metropolitan Council’s grading system. The seasonal means for
the TSI are calculated from the data collected between June through September and then are used
to determine three component index numbers: TSIP (phosphorus), TSIC (chlorophyll-a), and
TSIS (Secchi depth). Each of the component index numbers range from 0 to 100, and are then
averaged to determine an overall TSI score (Table 12). (Carlson, R.E., 1977). Lakes to be
classified as swimmable in the seven-county metro area need to have a TSI score less than or
equal to 59. An explanation of the productivity level for a range of TSI scores is in Table 13.
Table 12. TSI Determination Table (Carlson 1977) Component Parameter Equation
TSIP Total Phosphorus (µg/L) (14.42*(LN(TP)))+4.15) TSIC Chlorophyll-a (µg/L) (9.81*(LN(Chl-a)))+30.6) TSIS Secchi Disc Depth (m) 60-(14.41*(LN(Secchi)))
Overall TSI Mean average of three individual parameters
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Table 13. Description of the Carlson’s Trophic State Index Trophic State TSI Description
Oligotrophic
< 30 Clear water, oxygen throughout the year in the hypolimnion. Salmonid fisheries in deep lakes.
30 - 40 Deeper lakes still exhibit oligotrophic characteristics, but some shallower lakes will become anoxic in the hypolimnion during the summer
Mesotrophic 40 - 50 Water moderately clear, but increasing probability of anoxia in hypolimnion
Eutrophic 50 - 60
Decreased transparency, anoxic hypolimnia during the summer, macrophyte problems evidence, warm-water fisheries only
60 - 70 Dominance of blue-green algae, algal scum probable, extensive macrophyte problems
Hypereutrophic 70 - 80
Heavy algal blooms possible throughout the summer, dense macrophyte beds, but extent limited by light penetration.
> 80 Algal scum, summer fish kills, few macrophytes, dominance of rough fish
Moore, L. and K. Thronton, Ed 1998. Lake and Reservoir Restoration Guidance Manual. USEPA: EPA 440/5-88-002
Ecoregion Guidelines and Water Quality Standards for Lakes: The Minnesota Pollution
Control Agency (MPCA) has determined that lakes have unique physical and chemical
properties depending on where they are located in the state. Lakes within the MCWD reside
within the North Central Hardwood Forest Ecoregion (NCHF). This is the transitional area in
central Minnesota where the southeastern agricultural area meets the northeastern forested area.
This ecoregion is comprised of upland wooded areas, as well as small plains that are used for
agriculture. There are many lakes in this ecoregion that have moderate water quality. Much of
this area has been developed for residential, recreational, urban and agricultural land use.
Nutrient and pollutant loading are mainly attributed to storm water runoff in urban and
residential areas, as well as agricultural areas where fertilizer use is high. The MPCA provides
guidelines based on median water quality data that is characteristic for the lakes within the
NCHF ecoregion (Table 14). Ecoregion water quality standards are used for assessing the
recreational use of lakes in Minnesota. The data used for determining impairment must be
collected from eight or more monitoring events over two consecutive years. A lake can be listed
by the MPCA as impaired for nutrient/eutrophication biological indicators if the lake fails to
meet two or more of the water quality standards. Different water quality standards have been
established for shallow lakes (maximum depth less than 15 ft) and deep lakes (maximum depth
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greater than 15 ft). The NCHF ecoregion water quality standards are based on phosphorus,
chlorophyll-a and Secchi disc depth observations between June through September (MPCA,
2012).
Table 14. North Central Hardwood Forest Ecoregion Water Quality Guidelines and Water Quality Standards for Lakes for Shallow and Deep Lakes (MPCA, 2012)
North Central Hardwood Forest Ecoregion
Water Quality Lake Guidelines (25th -75th percentile)
Water Quality State Standards
(June-Sept Mean)
Water Quality State Standards
(June-Sept Mean) Shallow Lakes Deep Lakes
Secchi Depth (m) 1.5 - 3.2 > 1.0 > 1.4 Chlorophyll-a (µg/L) 5 - 22 < 20 < 14 Total Phosphorus (µg/L) 23 - 50 < 60 < 40
Long-term Trend Analysis:
To perform long term trend analysis on the water quality data in any lake, eight to ten years of
consistent data is needed due to climate patterns impacts on the water quality in a lake. Within
one year of data, there needs to be four or more monitoring events. MCWD is interested in the
long term trends of Secchi depth (water clarity), chlorophyll-a concentrations (estimation of
algal abundance) and total phosphorus concentrations (nutrient that affects algal growth). Due to
the massive water quality database accumulated by MCWD and its partners, MCWD staff will
be contracting with a consultant in 2013 to analyze the water quality of the Watershed District’s
lakes.
4.2 Stream Water Quality Analyses
Ecoregion Water Quality Standards for Streams: The MPCA collected and summarized
water quality data from minimally impacted streams within Minnesota’s seven ecoregions
(McCollor and Heiskary, 1993). These data may be used to establish water quality guidelines on
ecoregion basis. NCHF ecoregion median data are compared to data collected in MCWD
streams. Stream data is also compared to water quality standards listed in Chapter 7050 of
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Minnesota State Rules for the MPCA, and criteria listed in the MPCA’s Guidance Manual for
Assessing the Quality of Minnesota Surface Waters for the Determination of Impairment.
Chloride Standard for Streams: For waters in the MCWD (Class 2B) the chloride standards
include a chronic standard of 230 mg/L based on the four-day average and an acute standard of
860 mg/L for one hour duration.
Dissolved Oxygen Data Analysis: Based on the criteria for inclusion on the MPCA’s 303 (d)
list of impaired waters, if more than 10% of the readings collected within the past 10 years do
not meet the standard for DO, the stream is included on the MPCA’s 303(d) list. The water body
is considered partially supporting if 10% to 25% of readings do not meet the standard, and fully
impaired if greater than 25% of samples are less than five mg/L. A minimum of 10 samples are
necessary to consider the stream assessment.
Minnehaha Creek Discharge Calculations: Discharge for Grays Bay Dam is calculated by
taking into account the month, the lake level, and the stream capacity and applying this
information to a discharge formula created by the United States Army Corp of Engineers
(USACE). Discharge at Browndale Dam was calculated using automated water surface
elevation data collected during the monitoring period and manual readings. Linear interpolation
was used to calculate flow between ice out and the first recorded water level of 2012.
Upper Watershed Streams Discharge Calculations: Discharge over the subwatersheds
tributary to Lake Minnetonka is calculated in two ways: flow records are developed from
continuous stage recorders and stage-discharge relationships, and flow records are developed
from weekly manual measurements and stage-discharge relationships. At sites along Painter
Creek, Long Lake Creek, and Six Mile Creek, both continuous and weekly measurements are
collected; generally, the continuous readings offer a more complete picture of the runoff from the
sub-watershed.
E. coli Data Analysis: For waters in the MCWD (Class 2B) the E. coli standards are 126 colony
forming units per 100 milliliters (cfu/100 ml) for the 30-day geometric mean and 1260 cfu/100
21
ml as a value which 10% of all values is not to exceed. Grab samples were analyzed for E. coli
at the Three Rivers Park District Laboratory.
5. PRECIPITATION AND GROUNDWATER LEVELS
5.1 Precipitation throughout MCWD
The MSP had an annual precipitation of 29.59 inches in 2012 which is one percent greater than
the long term (1971-2000) annual mean precipitation of 29.41 inches (Figure 4, Table 16).
Above normal levels of precipitation occurred during the months of February, April, May, July,
and December 2012 at the MSP station. Above normal levels of precipitation occurred February,
April, May, June and December 2012 at the NOAA-NWS station in Chanhassen, Minnesota. The
monthly precipitation for May was considerably higher for both MSP and NOAA-NWS (9.34
inches and 11.23 inches, respectively). Figure 5 and Table 17 show historical annual
precipitation data for MSP and NOAA-NWS.
Figure 4. Comparison of Monthly 2012 Precipitation and Long-term (1971-2000) Average
Precipitation Data for MSP Station
0 1 2 3 4 5 6 7 8 9
10
Prec
ipia
tion
(Inc
hes)
MSP Airport Station (Inches) Longterm Average (1971-2000) (Inches)
22
Figure 5. Comparison of Annual Precipitation for MSP and NOAA-NWS (1960-2012)
0
5
10
15
20
25
30
35
40
45 19
60
1964
1968
1972
1976
1980
1984
1988
1992
1996
2000
2004
2008
2012
Prec
ipita
tion
(Inch
es)
MSP (Inches) NOAA-NWS
23
Table 15. 2012 Monthly Precipitation (inches) from Stations Monitored by MCWD and Citizen Precipitation Recorders (CPR)
Month Deephaven Shorewood Carver Park Maple Plain Long Lake Mpls. Mntka. Shorewood*
Hamel* Mpls-
Nokomis* January 0.37 0.12 0.12 0.35 0.28 0.32 0.32 0.08 0.3 0.37
February 1.04 1.77 0.09 1.5 0.85 1.85 0.78 0.93 1.55 1.61
March 1.53 1.04 0.15 1.67 1.74 1.69 2.03 1.51 0.81 1.38
April 2.45 2.41 0.09 2.08 2.01 3.32 2.39 3.04 2.12 3.58
May 9.5 9.67 ** 10.58 9.33 ** 7.06 8.6 9.5 9.15
June 3.95 4.22 0.14** 5.42 4.3 ** ** 5.39 3.44
July 3.1 1.98 0.57** 4.22 4.04 2.68 2.39 2.77 4.3 3.04
August 1.38 0.54 ** 1.92 1.37 1.16 0.48** 1.69 1.08 1.09
September 0.44 0.05 0.01** 0.43 0.39 0.4 0.02** 0.34 0.64 0.14
October 1.32 0.02** ** 1.28 1.75 1.51 0.92 1.32 2.08 1.12
November 0.65 ** ** 0.55 0.57 0.77 0.61 0.81 0.68 0.71
December 0.78 0.1 0.96 0.85 0.68 1.11 1.05 0.46 1.14 0.02
Total 26.51 21.9 1.41** 30.85 27.31 14.81 17.55 26.94 24.2 25.65
*Data collected by Citizen Precipitation Recorder (blank space indicates no collection taken for the month) **Data not available due to instrumentation error
Table 16. 2012 Monthly Precipitation Data for NWS and MSP Stations, and Long-term (1971-2000) Average Precipitation for MSP Station
Month
MSP Airport Station (Inches)
NOAA-NWS Chanhassen
Station (Inches)
Long-term Average (1971-2000) (Inches)
January 0.36 0.34 1.04 February 1.71 2.42 0.79 March 1.4 1.22 1.86 April 3.04 3.2 2.31 May 9.34 11.23 3.24 June 3.59 4.73 4.34 July 4.9 3.34 4.04 August 1.38 2.3 4.05 September 0.3 0.44 2.69 October 1.3 1.16 2.11 November 0.63 0.77 1.94 December 1.64 1.65 1.0 Total (Inches) 29.59 32.8 29.41
24
Table 17. Annual Precipitation Data for MSP and NOAA-NWS (1960-2012)
Year MSP
(Inches) Chanhassen
(Inches) Year MSP
(Inches) Chanhassen
(Inches) 1960 21.46 1987 32.16 1961 25.74 1988 19.08 1962 28.83 1989 23.32 1963 19.57 1990 33.05 1964 25.97 1991 36.69 1965 39.94 1992 29.67 1966 24.34 1993 32.21 1967 25.44 1994 29.67 1968 37.93 1995 25.66 1969 19.29 1996 26.05 1970 30.53 1997 34.43 1971 29.44 1998 33.39 1972 23.77 1999 30.54 29.57 1973 21.13 2000 30.48 28.75 1974 19.11 2001 34.23 33.49 1975 35.15 2002 38.45 36.66 1976 16.5 2003 22.69 23.34 1977 34.88 2004 27.39 33.9 1978 30.26 2005 33.41 42.4 1979 31.07 2006 27.57 27.4 1980 21.77 2007 34.32 27.84 1981 27.97 2008 22.38 26.54 1982 30.43 2009 24.8 29.84 1983 39.07 2010 32.89 36.41 1984 36.95 2011 26.87 27.98 1985 31.66 2012 29.59 32.80 1986 36.62
25
5.2 Deep Aquifer Wells
Groundwater elevations are recorded at six deep wells within the watershed. The wells are
located in the following cities: Mound, St. Louis Park, Minneapolis, St. Bonifacius, and Orono
(Table 18). Data for these wells was recorded by the MnDNR (Figures 6-8). The Prairie du
Chien-Jordan formations serve as major sources of municipal water in the western suburbs and
as a major industrial water source in Minneapolis.
Table 18. Long-term Groundwater Monitoring MnDNR wells in MCWD
MnDNR Well
Number Location Years
Monitored*
27043 Mound 1985-2012 27041 St. Louis Park 1980-2012 27036 Minneapolis 1979-2012 27044 St. Bonifacius 1991-2012 27010 Orono 1945-2012
*Not always continuous
26
Figure 6. Groundwater Well Elevation for MnDNR Wells: Mound (27043) Ground Elevation: 957 ft AMSL and St. Louis Park
(27041) Ground Elevation: 917 ft AMSL; Both are Bedrock Aquifers.
865 870 875 880 885 890 895
Wel
l Ele
vatio
n (ft
)
Mound
770 775 780 785 790 795 800 805
Wel
l Ele
vatio
n (ft
)
St. Louis Park
27
Figure 7. Groundwater Well Elevation for MnDNR Wells: Minneapolis (27036) Ground Elevation: 830 ft AMSL and St. Bonifacius
(27044) Ground Elevation: 950 ft AMSL; Both are Bedrock Aquifers.
775 780 785 790 795 800 805
Wel
l Ele
vatio
n (ft
)
Minneapolis
855 860 865 870 875 880 885 890 895
Wel
l Ele
vatio
n (ft
)
St. Bonifacius
28
Figure 8. Groundwater Well Elevation for MnDNR Well: Orono (27010) Ground Elevation: 931 ft AMSL. Bedrock Aquifer.
870 875 880 885 890 895 900
Wel
l Ele
vatio
n (ft
)
Orono
29
6. SUBWATERSHEDS OF
MINNEHAHA CREEK WATERSHED DISTRICT