Minnehaha Creek Watershed District 2005 Hydrologic Data Report
February 2006
Prepared by:
Sarah Roley MCWD Water Quality Assistant
And
Lorin K. Hatch, PhD MCWD Water Quality Specialist
2005 HYDRODATA REPORT TABLE OF CONTENTS
A. Executive Summary…………………………………………………………………… vi
B. Introduction and District-Wide Summary……………………………………...…… 1
C. Subwatershed Summaries…………………………………………………………..… 41 1. Minnehaha Creek…………………………………………………………………41 2. Lake Minnetonka…………………………………………………………………86 3. Christmas Lake………………………………………………………………….151 4. Lake Minnewashta………………………………………………………………157 5. Schutz Lake……………………………………………………………………...169 6. Six Mile Marsh…………………………………………………………………..173 7. Langdon Lake……………………………………………………………………201 8. Dutch Lake………………………………………………………………………208 9. Painter Creek…………………………………………………………………….214 10. Long Lake……………………………………………………………………....228 11. Gleason Lake…………………………………………………………………...239
D. Initiatives……………………………………………………………………………….247 Expanded monitoring; alum effectiveness index; diatom-inferred pre-development lake TP concentrations; Minnehaha Creek E. coli study; use of remote sensing to assess water quality; Stubbs Bay algal management; New USGS gauge on Minnehaha Creek at Hiawatha Avenue; STORET data transfer; Analysis of long- term Minnehaha Creek water quality data; Restoration of the Painter Creek Wetland south of County Road 26; Real-time monitoring of water quantity; Lake- wide Lake Minnetonka phosphorus model; Lake Minnetonka bathymetric and macrophyte survey
Appendix………………………………………………………………………………….262 A. Hydrologic data monitoring plan B. Lake and stream characteristics C. Data summaries: precipitation, groundwater, flows, loads, E. coli D. Acronyms, glossary of water quality terms, references, and index of lake and stream report cards
i LIST OF TABLES
Table 1.1 Lake report card grades for Lake Minnetonka bays, 1998-2005 Table 1.2 Mean 2005 summer surface Secchi disk transparency, chlorophyll a concentration, total phosphorus concentration, and trophic state index means for Lake Minnetonka bays Table 1.3 Lake report card grades for upper watershed lakes, 1998-2005 Table 1.4 Mean 2005 summer surface Secchi disk transparency, chlorophyll a concentration, total phosphorus concentration, and trophic state index means for upper watershed lakes Table 1.5 Lake report card grades for lower watershed lakes, 1998-2005 Table 1.6 Mean 2005 summer surface Secchi disk transparency, chlorophyll a concentration, total phosphorus concentration, and trophic state index means for lower watershed lakes Table 1.7 Northern Central Hardwood Forest Ecoregion vs. Minnehaha Creek 2005: median, mean, and maximum concentrations (summer) Table 1.8 2005 late-summer dry-weather DO profiles in Minnehaha Creek Table 1.9 Aerial export of nutrients and sediments to Minnehaha Creek Table 1.10 Northern Central Hardwood Forest Ecoregion vs. upper watershed streams 2005: median, mean, and maximum concentrations (summer) Table 1.11 Upper watershed areal loads Table 1.12 Upper watershed stream samples below 5mg/L DO (part 1 and 2) Table A1 2005 upper watershed lakes sampling conducted by MCWD Table A2 2005 upper watershed lakes sampling conducted by Three Rivers Park District and Metropolitan Council Table A3 Minneapolis lake sampling conducted by the MPRB Table A4 Lake level monitoring sites Table A5 Minnehaha Creek monitoring conducted by MCWD Table A6 Upper watershed stream monitoring conducted by MCWD Table A7 Precipitation gauge network Table A8 MCWD monitoring program quality assurance/quality control summary Table B1 Lake characteristics in the MCWD Table B2 Lake Minnetonka bay characteristics Table B3 Creek sampling locations in the MCWD Table B4 Precipitation gauge locations in the MCWD Table B5 Subwatershed characteristics in the MCWD Table C1 Minneapolis-St. Paul International Airport precipitation Table C2 Groundwater monitoring well elevations (above mean sea level) Table C3 Lake elevation gauge readings (feet above mean sea level) Table C4 2005 discharges and loads Table C5 E. coli (CFU/100 mL) in 2005
ii LIST OF FIGURES
Figure 1 Minnehaha Creek Watershed District Figure 2 Long-term and 2005 precipitation at the Minneapolis-St. Paul International Airport monitoring site Figure 3 Lake Minnetonka elevation (above mean sea level) and Grays Bay Dam discharge during 2005 open-water conditions Figure 4 Upper watershed runoff calculated from Grays Bay dam discharge setting, 1991 to 2005 Figure 5 Stream monitoring locations on Minnehaha Creek Figure 6 Average annual flow at the Browndale Dam (site CMH03) Figure 7 E. coli grab samples in Minnehaha Creek, 2005 Figure 8 E. coli 30-Day geometric means in Minnehaha Creek, 2005 Figure 9 2005 TP and SRP loading profile for Minnehaha Creek Figure 10 2005 TN and TSS loading profile for Minnehaha Creek Figure 11 Stream monitoring stations in the upper watershed Figure 12 Average annual discharge in Painter Creek at West Branch Road Figure 13 In-stream TP and SRP loading for upper watershed streams Figure 14 In-stream TN and TSS loading for upper watershed streams Figure 15 1997-2005 TP load to lake Minnetonka from gauged subwatersheds Figure 16 E. coli grab samples in Six Mile and Painter Creeks, 2005 Figure 17 Geometric mean E. coli data in upper watershed streams, 2005
Figure 1.1a Minnehaha Creek subwatershed Figure 1.1b Sampling sites on Minnehaha Creek Figure 1.2 Lake Calhoun Figure 1.3 Cedar Lake Figure 1.4 Diamond Lake Figure 1.5 Lake Harriet Figure 1.6 Lake Hiawatha Figure 1.7 Lake of the Isles Figure 1.8 Lake Nokomis Figure 1.9 Powderhorn Lake Figure 1.10 Minnehaha Creek at Grays Bay Dam Figure 1.11 Minnehaha Creek at I-494 Figure 1.12 Minnehaha Creek at W. 34th Streeet Figure 1.13 Minnehaha Creek at Excelsior Boulevard Figure 1.14 Minnehaha Creek at Browndale Dam Figure 1.15 Minnehaha Creek at W. 56th Street Figure 1.16 Minnehaha Creek at Upton Avenue Figure 1.17 Minnehaha Creek at Chicago Avenue Figure 1.18 Minnehaha Creek at 32nd Avenue Figure 1.19 Minnehaha Creek at Hiawatha Train Bridge Figure 2.1 Lake Minnetonka subwatershed Figure 2.2 Carsons Bay Figure 2.3 Cooks Bay
iii Figure 2.4 Crystal Bay Figure 2.5 East Upper Figure 2.6 Forest Lake Figure 2.7 Grays Bay Figure 2.8 Halsted Bay Figure 2.9 Harrison Bay Figure 2.10 Jennings Bay Figure 2.11 Lafayette Bay Figure 2.12 Lower Lake North Figure 2.13 Lower Lake South Figure 2.14 Maxwell Bay Figure 2.15 North Arm Figure 2.16 Peavey lake Figure 2.17 Priests Bay Figure 2.18 Shavers Lake Figure 2.19 Smithtown Bay Figure 2.20 Spring Park Bay Figure 2.21 St. Albans Bay Figure 2.22 Stubbs Bay Figure 2.23 Wayzata Bay Figure 2.24 West Arm Figure 2.25 West Upper Figure 2.26 Classen Creek Figure 2.27 Forest Lake Creek Figure 2.28 Halsted Bay Inlet North Figure 2.29 Halsted Bay Inlet South Figure 2.30 Peavey Lake Creek Figure 2.31 Stubbs Creek Figure 3.1 Christmas Creek subwatershed Figure 3.2 Christmas Lake Figure 3.3 Christmas Creek Figure 4.1 Lake Virginia subwatershed Figure 4.2 Tamarack Lake Figure 4.3 Lake St. Joe Figure 4.4 Lake Minnewashta Figure 4.5 Virginia Lake Figure 4.6 Minnewashta Creek Figure 5.1 Schutz Lake subwatershed Figure 5.2 Schutz Lake Figure 6.1 Six Mile Marsh subwatershed Figure 6.2 Pierson Lake Figure 6.3 Wasserman Lake Figure 6.4 West Auburn Lake Figure 6.5 Parley Lake Figure 6.6 Lake Zumbra Figure 6.7 Steiger Lake
iv Figure 6.8 Six Mile Creek at Highway 5 Figure 6.9 Steiger Lake Creek Figure 6.10 Sunny Lake Creek Figure 6.11 Six Mile Creek at Lunsten Lake Outlet Figure 6.12 Six Mile Creek at Highland Road Figure 7.1 Langdon Lake subwatershed Figure 7.2 Langdon Lake Figure 7.3 Langdon Creek Figure 8.1 Dutch Lake subwatershed Figure 8.2 Dutch Lake Figure 8.3 Dutch Creek Figure 9.1 Painter Creek subwatershed Figure 9.2 Painter Creek at Deborah Drive Figure 9.3 Painter Creek at CR 6 Figure 9.4 Painter Creek at CR 26 Figure 9.5 Painter Creek at Painter Drive Figure 9.6 Painter Creek at West Branch Road Figure 9.7 Painter Creek at CR 110 Figure 10.1 Long Lake subwatershed Figure 10.2 Long Lake Figure 10.3 Long Lake Inlet Figure 10.4 Long Lake Outlet Figure 10.5 Long Lake Creek at Brown Road Figure 11.1 Gleason Lake subwatershed Figure 11.2 Gleason Lake Figure 11.3 Gleason Lake Inlet Figure 11.4 Gleason Lake Outlet
Figure D.1 A tipping-bucket precipitation gauge Figure D.2 Potential volunteer monitoring sites Figure D.3 Title slide for the 2005 NALMS Conference presentation Figure D.4 Drs. Hatch and Edlund with extracted bottom core taken from Carsons Bay in April 2005 Figure D.5 Cage for containment of dye-free fabric; placement of mesh bag into storm drain; recovery of fabric after exposure in the stream Figure D.6 Water clarity in the MCWD as assessed by satellite in 2000 (from UMN) Figure D.7 A Solarbee recirculation unit Figure D.8 Secchi depth and chlorophyll-a concentration over time in Stubbs Bay, Lake Minnetonka Figure D.9 USGS gauge on Minnehaha Creek at Hiawatha Avenue in Minneapolis Figure D.10 Data posted on the USGS website (late Dec. 2005 - early Jan. 2006) Figure D.11 Painter Creek Improvement Project Figure D.12 ELCOM-CAEDYM model representations (Univ. Western Australia)
v Executive Summary
The Minnehaha Creek Watershed District’s (MCWD) annual Hydrologic Data Program is designed for the collection of background water quality and quantity data. The program is a collaboration between the Three Rivers park District (TRPD), the Minneapolis Park and Recreation Board (MPRB), the Metropolitan Council (Met Council), the Minnesota Pollution Control Agency (MPCA), the Lake Minnetonka Conservation District (LMCD), and the Minnesota Department of Natural Resources (MN DNR). Data collected is entered into a database, which is used to identify water quality trends, track progress, and analyze water related problems. The program began in 1968. The District undertook an expanded monitoring program in 1997 to provide a comprehensive view of water quality and to focus improvement projects in the areas with the most need. Findings based on the 2005 monitoring results are presented in this report and summarized below.
Precipitation Precipitation was monitored at several locations in and near the MCWD. The MCWD maintains five automated stations in cooperation with the Cities of St. Louis Park, Long Lake, and the Carver Park Reserve. Precipitation over the watershed was generally near normal during the first half of 2005, but a very wet August through October occurred. Precipitation during 2005 at the Minneapolis-St. Paul Airport was 33.4 inches, 4.0 inches above the 30-year average of 29.4 inches.
Lake Minnetonka The discharge at Grays Bay Dam averaged 38 cfs during 2005, or 4.2 inches of runoff from the 123-square mile upper watershed. Lake elevation fluctuated 1.22 feet over the year, which is typical for Lake Minnetonka.
Each year, water quality in principal lakes is graded based on parameters that indicate the lake’s suitability for recreational use. These parameters include water clarity, chlorophyll a (which estimates algal abundance), and phosphorus (the algal limiting nutrient). The grades do not consider the presence or abundance of non-native aquatic plants such as Eurasian water milfoil.
vi Water quality grades ranged from A’s in several bays to a DC- on several bays. Sixteen of the 23 bays monitored in 2005 had average summer TP concentrations below 40 ppb, indicating full compliance for lakes in the North Central Hardwood Forest ecoregion. Bays not in compliance include Peavey Lake, Forest Lake, West Arm, Stubbs Bay, Harrisons Bay, Jennings Bay, and Halsted Bay. These systems are located near major polluting stream outlets (Classen Creek, Six Mile Creek, Painter Creek, and Peavey Creek).
Water quality in Lake Minnetonka is far better today than it was in the 1970s: 1970s TP concentrations were generally more than 3 times the concentrations measured today. Many bays that were impaired for recreational use based on their TP concentrations in the 1970s, today are classified as full use. This improvement in water quality is due mainly to the 50,780-pound reduction in TP load to the lake that resulted from the diversion of wastewater from seven surrounding municipalities to treatment facilities outside the watershed. By comparison, the annual TP load from gauged sub-watersheds (73% of the upper watershed is gauged) between 1997 and 2005 ranged from 684 pounds in 2000 to 18,482 pounds in 2001. The total phosphorus (TP) load to Lake Minnetonka from gauged tributaries was 9,774 pounds in 2005.
While water quality has improved significantly in the long-term, data collected under the District’s expanded monitoring program (1997-2005) is in need of a thorough statistical analysis to determine whether our lake’s water quality is improving, declining, or remaining the same. Such an analysis will also provide insight as to the necessary frequency of sampling required to statistically detect changes in water quality. Any short-term changes in water quality (1997- 2005) may be the result of precipitation and runoff fluctuations. During seven of the past eight years, annual watershed precipitation has exceeded the 30-year average. Increased precipitation causes increased runoff, and increased phosphorus loads from the sub-watersheds to Lake Minnetonka.
Lower Watershed Lakes Water quality grades in lower watershed lakes generally remained the same from 2004 to 2005. Water quality grades ranged from A’s in Lake Calhoun and Lake Harriet to an F in Diamond Lake. Only 4 of the 8 lower watershed lakes monitored in 2005 had average summer TP
vii concentrations below 40 ppb, indicating full compliance for lakes in the North Central Hardwood Forest ecoregion. Lakes not in compliance include Lake Hiawatha, Lake Nokomis, Powderhorn Lake, and Diamond Lake.
Upper Watershed Lakes Water quality grades in upper watershed lakes showed no clear trend from 2004 to 2005: 8 lakes improved, 2 lakes declined, and 9 lakes were not monitored the previous year. Water quality grades ranged from an A in Christmas Lake and St. Joes Lake to a D in Langdon Lake and Lake Wasserman. Relatively high upper watershed loads measured during the past five years (2001- 2005) are caused in part by above normal precipitation in 8 of the past 9 years. Only 8 of the 18 upper watershed lakes monitored in 2005 had average summer TP concentrations below 40 ppb, indicating full compliance for lakes in the North Central Hardwood Forest ecoregion. Lakes not in compliance include Gleason Lake, Long Lake, Dutch Lake, Lake Wasserman, Langdon Lake, Parley Lake, Windsor Lake, Shavers Lake, Lake Virginia, and Pierson Lake.
Minnehaha Creek Flow and water quality were measured weekly at ten locations on Minnehaha Creek (March through November 2005). Average flow at Browndale Dam in Edina was 30 cubic feet per second (cfs) over the year. The maximum 2005 flow recorded at Browndale Dam was 85 cfs (July 11th). Water quality in Minnehaha Creek is generally good when compared to MPCA’s Ecoregion guidelines for the North Central Hardwood Forest Ecoregion (in which Minnehaha Creek is located). Dissolved oxygen (DO) concentrations in Minnehaha Creek were generally above the Minnesota State Standards (MN 7050) of 5mg/L. The I-494 station saw low DO levels on July 25th (4.7), September 5th (4.9), and September 12th (4.8), but values returned above 5 mg/L by the next week. The Excelsior Blvd. station had one violation (June 22nd, 4.6 ppm), but recovered by the following week. Bacteria are a problem in Minnehaha Creek during the entire summer and early fall; several monitoring sites violated the MPCA 30-day geometric mean standard during this period.
Sediment and nutrient loading generally increases downstream in Minnehaha Creek, although the reservoirs of Browndale Dam and Lake Hiawatha tend to reduce these loads. The contributing
viii subwatersheds between the Browndale Dam and the Upton Avenue station, and between the 32nd Ave and Hiawatha Ave. stations, were the greatest contributors of sediment and nutrient areal loads in 2005.
Uppe r Watershed Streams Flow and water quality were measured weekly at 26 locations on 13 major tributaries in the upper watershed that drain about 73% of sub-watersheds tributary to Lake Minnetonka. Runoff over the upper-watershed (123 square miles) was 4.2 inches as measured at Grays Bay, 5.3 inches from the Painter Creek sub-watershed (14.2 square miles), and 5.4 inches from the Long Lake sub-watershed (12.5 square miles).
The TP loading to Lake Minnetonka from gauged tributary watersheds was 9,774 lbs in 2005; Painter Creek comprised 37% of the load but is only 21% of the subwatershed area. From year to year, it generally exports the largest external TP, SRP, TN, and TSS loads to Lake Minnetonka of any of the gauged subwatersheds draining to the lake.
In-stream DO concentrations in upper watershed streams were consistently below the MN 7050 Standard (5mg/L) during 2005. Low DO in the upper watershed is likely due to a combination of natural and anthropogenic influences.
The Painter Creek outlet station had a bacteria problem from late summer through early fall, violating the MPCA 30-day geometric mean standard during this period.
The MPCA 303d listing criteria for DO states that if 10% or more of DO measurements during the past 10 years are less than 5 mg/L, and there are more than 10 measurements, the water body is included on the MPCA’s 303d List of Impaired Waters. Based on the above criteria, and the most recent 10 years of DO data, most upper watershed streams could be included on the MCPA’s 303d List of Impaired Waters. The exceptions in 2005 were Christmas Creek and Classen Creek.
ix Recommendations for 2006 • Continue the monitoring program as in 2005, minor changes are recommended which are discussed in the sections of this report. • Intensive workup of dissolved oxygen and phosphorus data to assess the spatial and temporal variation of internal P loading in Lake Minnetonka. • Focus watershed monitoring and rehabilitation efforts in areas that contribute to poor Lake Minnetonka water quality: Six Mile Creek, Painter Creek, Classen Creek, Long Lake Creek, and Gleason Lake Creek. • Conduct a more intensive study of bacterial sources in Minnehaha Creek. Use of tracers such as optical brighteners will help us further refine bacterial spatial and temporal variation. • Install additional pressure transducers along the creek to better assess discharge dynamics. • Focus BMP efforts in the Upton Ave. and Hiawatha Ave. subwatersheds to address high loading in Minnehaha Creek. • Assess spatial and temporal extent of DO violations in upper watershed streams through continuous monitoring. Priority should be given to Painter Creek. • Address the high nutrient loading to Lake Minnetonka from Painter Creek. Add a station above Painter Creek Drive, including an auto-sampler, to assess the Painter Creek Improvement Project. • Add stations at the inlets for Christmas Lake, Dutch Lake, Langdon Lake, and Schutz Lake to develop a comprehensive nutrient budget for these waterbodies. • Encourage volunteer monitoring efforts of upper watershed lakes.
x 1. Introduction and District-Wide Analysis
The Minnehaha Creek Watershed District (MCWD) was established in 1967 to protect the drainage basin’s water resources, which include Lake Minnetonka, the Minneapolis Chain of
Lakes, and Minnehaha Creek (Figure 1).
Figure 1 Minnehaha Creek Watershed District
The District seeks to conserve the natural resources of Minnehaha Creek watershed through public information and education, regulation of land use, regulation of the use of water bodies and their beds, and capital improvement projects. The MCWD encompasses approximately 181 square miles and includes all or part of 27 cities and three townships in two counties.
The watershed of Minnehaha Creek includes approximately 151 square miles in Hennepin
County and 30 square miles in Carver County. The upper watershed, with a total area of 123
1 square miles, includes Lake Minnetonka and the 100 square miles of land that drains into the lake. The lower watershed includes Minnehaha Creek and the 59 square miles of land that drain into the creek below Lake Minnetonka. The Lake Minnetonka outlet is located at Gray’s Bay
Dam, the headwaters of Minnehaha Creek.
The major hydrologic features of the watershed include Lake Minnetonka, Minnehaha Creek, the
Minneapolis Chain of Lakes, and Minnehaha Falls. Each watershed feature provides unique recreational opportunities and aesthetic resources. Through monitoring and analysis of its streams and lakes, the District has identified areas of water quality degradation and flooding. The
District has then used this knowledge to develop and implement solutions that improve or maintain the water quality in the watershed.
Since 1968, the district has collected hydrologic data, generally publishing the results annually.
Beginning in 1997, the District undertook an expanded monitoring program to provide a comprehensive view of water quality throughout the watershed and to focus improvement projects in areas with the most need. This report presents hydrologic data collected and compiled during 2005.
The present report represents a change in format compared to reports from previous years, although the content remains similar. The MCWD is currently developing its 10-year watershed management plan (a.k.a. the 509 Plan), which divides the District into a dozen subwatersheds.
The selection of these subwatersheds is based on those from the 2003 HHPLS Study; this study modeled future development in the District and projected how water quality loads (particularly
2 total phosphorus) would be altered. Given this information, water quality goals have been set for each of the subwatersheds.
Rather than place the lake and water quality report cards in an appendix, as has been done in the past, now these report cards are embedded in the appropriate subwatershed sections of the report.
This approach will place all the pertinent information relative to a specific subwatershed in the same place, which will allow the reader to assess the state of water quality in that subwatershed.
The data collected by the MCWD can be categorized into four main types: precipitation, lakes, streams, and groundwater:
Precipitation: The District maintains tipping bucket precipitation stations at five locations in the watershed. Precipitation data from five locations in and near the watershed are compiled from the State Climatologist’s web site. Six Citizen Precipitation Recorders at locations in and near the watershed, record precipitation data and submit it to the MCWD. This data provides an account of the varying precipitation amounts over the watershed.
The District has recently added three more tipping bucket precipitation stations in the watershed, based on discussions with the US Army Corps of Engineers. These stations are located at
Burroughs Elementary School (Minneapolis, located on Minnehaha Creek due south of Lake
Harriet), the Minnetonka Public Works office (Minnetonka, off Minnetonka Blvd. due east of
Hopkins Crossroads), and on the property of Renae Clark (Mound, near SW corner of Dutch
Lake). MCWD is working with the City of Shorewood to locate a fourth gauge in that locale. In
3 addition, a new USGS precipitation gauge has been installed next to Minnehaha Creek next to
Hwy 55.
For brevity, only the data from the Minneapolis-St. Paul International Airport is presented in this report; it does, however, give the reader an excellent overview of how precipitation varied over the course of 2005.
Lakes: Lake water quality samples and elevations are collected from Lake Minnetonka, the
Minneapolis Chain of Lakes, and 19 other lakes throughout the watershed provide data for the annual lake report cards. Sampling takes place primarily from mid-April (ice-out) through early
October. Most sampling occurs on a bi-weekly basis.
Streams: Stream discharge was measured and water quality samples were collected at 10 locations along Minnehaha Creek and at 26 sites along major tributaries to Lake Minnetonka.
Data collected for each stream is presented in the annual stream report cards. Sampling takes place primarily from mid-March through early November. Sampling occurs on a weekly basis.
Continuous water level monitoring (using pressure transducers) was conducted on Minnehaha
Creek at Grays Bay Dam (Lake Minnetonka Outlet) in Minnetonka, at the I-494 crossing, at the
Browndale Dam in Edina, and at Longfellow Lagoon in Minneapolis.
The Metropolitan Council conducts continuous water level monitoring and flow-weighted sampling at one location near the mouth of Minnehaha Creek.
4
Continuous water level monitoring was conducted on Painter Creek, Six Mile Creek, and Long
Lake Creek in the upper watershed.
Groundwater: Groundwater elevations in the bedrock aquifers recorded by the DNR at six wells with long-term records are compiled for this report. The wells are located in Minneapolis,
Mound, St. Bonifacius, St. Louis Park, Orono, and Golden Valley.
The 2005 Hydrologic Data Monitoring Program work plan is presented in the Appendix (part A).
Also included is a description of quality assurance/quality control procedures to help ensure data quality. Lake and stream characteristics such as depths and areas are included in part B. Data summaries on precipitation, groundwater, flows, loads and E. coli can be found in part C. Part D contains a list of acronyms, a water quality glossary, references, and an index of lake and stream report cards.
Lake Water Quality Analysis
Water quality grades are based on standards established by the Metropolitan Council. The standards give a range to each letter grade for the May through September averages of surface total phosphorus (TP) concentration, surface chlorophyll-a concentration, and Secchi depth. The overall lake water quality grade is the average of the grades for each parameter. Note that the range of grades reflects the typical water quality in a given lake region (e.g., the Twin Cities area). Hence a grade of "A" in the District will not be comparable to an "A" in northern
Minnesota.
5
Other indicators of lake condition such as aquatic plant growth or invasive species are not factored into these grades. The Trophic State Index (TSI), which measures the productivity level of a lake or degree of eutrophication, is also calculated. High TSI values correspond with poorer water quality.
Lakes are additionally classified as in or out of compliance based on Minnesota Pollution
Control Agency (MPCA) eutrophication standards. In 2005 the MPCA enacted an amendment to
Minnesota Rules Chapter 7050. The MPCA created numeric standards for P and two indicators that measure the response of lakes to excess P. The two indicators are chlorophyll a and Secchi disk transparency. Proposed lake standards will be different for the four major ecoregions in the state. The MCWD lies entirely in the North Central Hardwood Forest ecoregion. The MPCA developed separate standards for trout lakes and lakes less than 15 feet deep (“shallow lakes”). A shallow lake is defined as “a lake with a maximum depth of 15 feet or less, or with 80 percent or more of the lake area shallow enough to support emergent and submerged rooted aquatic plants
(the littoral zone). Shallow lakes typically do not thermally stratify during the summer. The quality of shallow lakes will permit the propagation and maintenance of a healthy indigenous plant community, and they will be suitable for boating and other forms of aquatic recreation for which they may be usable. Shallow lakes are generally not wetlands, which are defined in part
7050.0186. Shallow lakes will be differentiated from lakes and reservoirs for purposes of this chapter on a case-by-case basis”.
6 All lakes in the MCWD are classified as Class 2B waterbodies in the North Central Hardwood
Forest ecoregion, so there are two sets of standards we need to address: shallow lakes and deeper lakes. Mean summer values are to be calculated using data collected between June 1st and
September 30th each year. A lake is considered out of compliance when the following occurs: 1) the TP standard is exceeded and 2) either the chlorophyll a or the Secchi disk transparency standards are exceeded. The "lakes" nutrient criteria values in the MCWD are: TP 40 ppb, chlorophyll-a 13 ppb, and Secchi transparency 1.5 m. The "shallow lakes" nutrient criteria values in the MCWD are: TP 60 ppb, chlorophyll 20 ppb, and Secchi transparency 1.0 m. Most monitored lakes in the MCWD are in the "Lakes" category, although there are several shallow lakes (e.g., Libbs, Gleason).
Additionally, some lakes within MCWD are included on the MPCA’s 303 (d) List of Impaired
Waters. Not all lakes that are considered out of compliance are on the MPCA’s 303 (d) List of
Impaired Waters. This is primarily because only a portion of the MCWD’s database has been uploaded to the EPA’s national data warehouse, STORET (short for STOrage and RETrieval).
This situation will change now that all MCWD historical data through 2004 has been uploaded to
STORET.
Stream Water Quality Analysis
The MPCA (McCollor and Heiskary, 1993) collected and summarized water quality data from minimally impacted streams within Minnesota’s seven ecoregions. These data may be used to establish water quality guidelines on ecoregion basis. North Central Hardwood Forest Ecoregion median data are compared to data collected in MCWD streams.
7
Stream data is also compared to water quality standards listed in Chapter 7050 of Minnesota
State Rules for the MPCA (MN 7050), and criteria listed in the MPCA’s Guidance Manual for
Assessing the Quality of Minnesota Surface Waters for the Determination of Impairment 305(b)
Report and 303(d) List are also used.
Minnesota rule changes have also occurred with respect to bacteria sampling. Water contaminated with bacteria from human or animal fecal material can cause illness in humans if ingested. Bacteriological standards are designed to protect swimmers who might ingest small quantities of water from getting sick. The EPA is urging all states to update their bacteriological standards. In 2005 the MPCA replaced the current fecal coliform standard with an E. coli standard, based on an EPA criterion.
For waters in the MCWD (Class 2B) the E. coli standards are i) 126 cfu/100 ml for the 30-day geometric mean and ii) 1260 cfu/100 ml as a value which 10% of all values is not to exceed. The
MCWD switched from the fecal coliform technique to the E. coli technique in summer 2003 at the urging of the MPCA. The Three Rivers Parks District and the Minneapolis Park and
Recreation Board currently monitor their major public beaches for E. coli, while the MCWD currently monitor several stream sites for E. coli.
8 Precipitation
The MCWD and other monitoring entities have continuous precipitation monitoring equipment located in or near the MCWD. The MCWD also has several citizen monitors, who record daily information on data sheets for submittal. All of this data is used to help determine long-term trends and to provide information for calibration of the HHPLS computer model.
The annual mean (1971-2000) for the Minneapolis-St. Paul International Airport is 29.4 inches, which is lower (12%) that precipitation seen in 2005 (33.4 inches). In 2005 the Minneapolis-St.
Paul International Airport received close to an average amount of precipitation for the first half of the year (Figure 2). However, this station received significantly higher amount of precipitation from August through October compared with the long-term average. This increase in rainfall had a large impact on stream discharge in the MCWD, discussed later in this report.
Figure 2 Long-term and 2005 precipitation at the Minneapolis-St. Paul International Airport monitoring site
6 MSP Airport 5 MSP Airport 2005 Long-Term Average 4 (1971-2000) 3 2 1 Precipitation (inches) 0
April May June July January March August February October September NovemberDecember 2005 Month
9 Lake Minnetonka Elevation
The lake elevation at ice-out (April 20th) was 929.35 feet (Figure 3), which was slightly over the
30-year ice-out average (929.1 feet; 1971-2000). Following a spike in lake level on May 20th
(929.91), the gates of the Grays Bay Dam were opened further. Discharge increased steadily
Figure 3 Lake Minnetonka elevation (above mean sea level) and Grays Bay Dam discharge during 2005 open-water conditions. Note: runout elevation is 929.75 feet; 100-year flood elevation: 931.5 feet
350 930.2 930 300 929.8 250 929.6 929.4 200 929.2 150 929 928.8
Discharge (cfs) 100 928.6
50 928.4 Lake Elevation (feet) 928.2 0 928
5/2 6/8 7/5 8/8 9/6 4/20 5/16 5/25 6/16 6/24 7/18 7/29 8/19 9/21 10/6 10/25 11/10 11/19 12/7 2005 Date
from this point until June 13th when discharge exceeded 300 cfs. Note that at this time the level over-topped the gauge, so discharges were likely higher than 300 cfs. This flow lasted until June
20th when discharge and lake levels gradually dropped.
Rain events in August and September caused lake levels to rise again until mid-October (peak elevation 929.59) when lake levels dropped again. During this period the dam discharge began to increase. However, the dam was closed on October 5th and 6th due to the presence of downstream flooding. Upon reopening of the dam on October 7th the discharge increased rapidly
10 to 250 cfs until early November. The dam was closed on December 7th.
The calculated discharge averaged 38 cfs over the entire year, which is equivalent to 4.2 inches of runoff from the 123-square mile watershed (15-year average = 4.9 inches; Figure 4). The lake
Figure 4 Upper watershed runoff calculated from Grays Bay dam discharge setting, 1991 to 2005 (average = 4.9 inches).
14
12
10
8
6
4 Runoff (inches)
2
0 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
elevation surpassed the normal ordinary high water level (NOHW) of 929.4 feet for approximately 2 months during early summer and over 3 weeks in mid-October. During the 2005 period of record, the average lake elevation was 929.31 feet with an overall fluctuation of 1.22 feet. Annual lake evaporation in the vicinity is normally about 31 inches.
Lake Minnetonka Water Quality
Lake report card grades in Lake Minnetonka improved in East Upper Lake, Priests Bay,
Smithtown Bay, and West Upper Lake compared to 2004 values (Table 1). Water quality grades decreased in Carsons Bay, Crystal Bay, Forest Lake, Harrisons Bay, Jennings Bay, Lower Lake
11 South, Maxwell Bay, North Arm, Stubbs Bay, and Wayzata Bay. Water quality grades ranged
from A’s in Grays Bay and St. Albans Bay to a D for Jennings Bay. Average summer surface TP
concentrations in 16 out of 23 bays monitored are less than 40 µg/L, indicating full compliance
for lakes within the North Central Hardwood Forest Ecoregion. The remaining 7 are classified as
Table 1 Lake report card grades for Lake Minnetonka bays, 1998-2005. See Subwatershed Summaries for lake report cards.
Waterbody 1998 1999 2000 2001 2002 2003 2004 2005 Black ------C+ --- Browns A- B+ ------Carman ------B+ --- Carsons ------A A- Cooks B B- B+ B+ C+ B B- B- Crystal B+ C+ A- B+ C+ A- B+ B East Upper ------B+ A- Forest Lake C- C- C- D+ D+ D C C- Gideons ------A --- Grays ------A A Halsted D+ C- D+ C- C- D+ C- C- Harrisons C- C- C+ C- C D+ C C- Jennings D+ D+ C- D+ C- D+ C- D Lafayette A- A------B+ Libbs ------B- B+ --- Lower Lake North A A------B+ Lower Lake South A A- A- A A A A A- Maxwell B- C+ B C+ C+ C+ B C+ North Arm B+ C+ B C+ B- B- B B- Peavey Lake ------C+ C+ C+ C C C Priests ------C- B- Smithtown ------B+ A- Spring Park A- A- B+ A- B+ A A- B+ St. Albans A B+ A- B+ A- A A A Stubbs C C- C- C C- C- C C- Tanager Lake ------D- D+ C- D D- --- Wayzata A A- A- A A- A A A- West Arm C- C C+ D+ C- D+ C C West Upper B+ B B+ B+ B+ B+ B A-
out of compliance (Table 2).
Water quality in Lake Minnetonka is better now than it was in the 1970s. Many Lake
Minnetonka Bays that were classified as restricted-use in the 1970s based on their average
summer surface TP concentrations are now considered in compliance (Table 2). Average
12 summer surface TP concentrations in the 1970s were between 1.5 and 3.5 times higher than they are today. Long-term average summer surface TP, chlorophyll-a, Secchi depth, and TSI graphs for Lake Minnetonka lake report cards in the Subwatershed Summaries section of this report.
Table 2 Mean 2005 summer surface Secchi disk transparency, chlorophyll a concentration, total phosphorus concentration, and trophic state index means for Lake Minnetonka bays. Red: out of compliance.
Secchi Total Disk Chlorophyll Phosphorus Waterbody (m) (ppb) (ppb) TSI East Upper 4.0 3 17 42 Smithtown 2.5 10 21 50 St. Albans 3.1 7 22 47 Carsons 2.9 6 24 48 Grays 3.1 8 24 48 Lower Lake South 3.2 7 25 48 Spring Park 2.6 9 25 50 Lower Lake North 3.0 7 26 47 Wayzata 3.1 9 27 49 West Upper 2.5 11 27 51 Crystal 2.1 14 29 53 Lafayette 3.0 10 30 50 Cooks 2.1 15 33 54 North Arm 1.8 17 35 55 Maxwell 1.6 21 36 56 Priests 1.8 19 37 56 Harrisons 1.1 40 63 63 West Arm 1.1 44 68 64 Forest Lake 0.9 45 72 65 Stubbs 0.9 44 74 65 Peavey Lake 2.0 28 77 60 Halsted 1.1 46 91 65 Jennings 1.0 60 110 68
The primary reason for the improvement was the gradual elimination of wastewater discharges to
13 Lake Minnetonka and its tributaries from seven surrounding municipalities. This resulted in an annual TP load reduction of 50,780 lbs (MCWD 1997). By comparison, TP loads to Lake
Minnetonka from gauged watersheds ranged from 700 to 18,500 lbs in 2000 and 2001 respectively (these numbers represent about 73% of the sub-watershed area tributary to Lake
Minnetonka which have been monitored annually since 1997).
Data quality and quantity have been excellent since 1997 when the MCWD began its intensive monitoring program. Caution in data interpretation is also warranted here because annual variation in external drivers such as precipitation quantities can have a significant impact on water quality. Hence it would be inappropriate to apply simple statistical procedures (e.g., linear regression) to suggest whether water quality is changing in Lake Minnetonka since 1997. Such an in-depth statistical analysis will be undertaken by the MCWD water quality specialist in the near future.
Caution must be taken when examining these long-term trends. Data in the 1970s and 1980s for
Lake Minnetonka bays often had insufficient numbers of samples taken in a given year. For example, only one sampling for Secchi disk transparency may have been taken in a given bay for the entire year. In addition, the time of year that such data may have been collected is also of crucial importance. For example, a very low Secchi disk transparency reading may have been taken in a bay during an unusual algal bloom event. It might have been the case that the remainder of the year produced great transparency conditions; hence, that single data point would bias our conclusions.
14 Upper Watershed Lake Water Quality
Seven of the 19 lakes monitored in the upper watershed received improved lake report card
grades compared to 2004 values; these include Christmas Lake, Dutch Lake, Langdon Lake,
Long Lake, Lake Minnewashta, Steiger Lake, Tamarack Lake, and Windsor Lake (Table 3).
Table 3 Lake report card grades for upper watershed lakes, 1998-2005.
Waterbody 1998 1999 2000 2001 2002 2003 2004 2005 Christmas A A A A A A A- A Dutch ------C+ D+ C D D+ C- Gleason C- C- C- D+ C- D C- C- Langdon D- D F D- D+ F F D Long C+ C C- D+ C C- C- C Minnewashta A- A- B+ B+ B+ A B+ A- Parley ------D D+ D+ D --- D+ Pierson ------B A- --- B- Schutz ------B C+ C C Shavers ------B- St. Joes ------A Steiger ------C+ --- C+ C C+ B- Stone ------C+ --- C --- C+ --- Tamarack ------C+ C- C Virginia ------C C --- C+ Wasserman ------D D C C- D+ D West Auburn ------B+ --- B- C- B- B- Windsor ------D- D+ Zumbra ------A- --- B+ B B+ B
Water quality grades decreased in Wasserman Lake and Lake Zumbra. Water quality grades
ranged from an A in Christmas Lake St. Joes Lake to a D for Langdon Lake and Wasserman
Lake. Changes in grades most likely reflect year-to-year variation in precipitation.
Average summer surface TP concentrations in 8 out of 19 lakes monitored are less than 40 µg/L,
indicating full compliance for lakes within the North Central Hardwood Forest Ecoregion. The
remaining 10 are not in compliance (Table 4). Water quality in upper watershed lakes is
generally better now than it was in the 1970s. Some lakes (e.g., Langdon Lake) received
waterwater effluent for many years, but there appears to be evidence that the cessation of these
15 activities is in large part responsible for improvements in water quality. Long-term average summer surface TP, chlorophyll-a, Secchi depth, and TSI graphs for the Upper Watershed lakes are presented in the Subwatershed Summaries section of this report.
Table 4 Mean 2005 summer surface Secchi disk transparency, chlorophyll a concentration, total phosphorus concentration, and trophic state index means for upper watershed lakes. Red: out of compliance.
Secchi Total Disk Chlorophyll Phosphorus Waterbody (m) (ppb) (ppb) TSI St. Joes 3.1 6 17 47 Christmas 6.3 0.5 18 34 Minnewashta 2.5 3 26 46 Zumbra 2.6 11 27 51 West Auburn 1.6 18 33 55 Tamarack 1.9 24 34 56 Steiger 2.1 20 39 55 Schutz 1.9 34 40 58 Pierson 2.0 14 44 55 Virginia 1.0 22 44 60 Shavers 1.2 6 55 56 Long 0.8 44 63 65 Dutch 1.2 44 64 63 Wasserman 0.7 61 84 68 Windsor 0.7 27 105 66 Gleason 1.1 70 116 68 Langdon 0.7 60 122 70 Parley 0.7 69 147 71
Caution must be taken when examining these long-term trends. As was noted for Lake
Minnetonka bays and lower watershed lakes in the 1970s and 1980s, there were instances of insufficient numbers of samples taken in a given year. For example, only one sampling for
Secchi disk transparency may have been taken in a given bay for the entire year. In addition, the
16 time of year that such data may have been collected is also of crucial importance.
Lower Watershed Lake Water Quality
The 8 lakes monitored in 2005 are in the city of Minneapolis. Lake report card grades in the
lower watershed improved in Lake Hiawatha, Lake of the Isles, Lake Nokomis, and Powderhorn
Lake compared to 2004 values (Table 5). Water quality grades decreased in Cedar Lake and
Table 5 Lake report card grades for lower watershed lakes, 1998-2005.
Waterbody 1998 1999 2000 2001 2002 2003 2004 2005 Brownie C+ B- B ------C+ --- Calhoun B+ A A B+ A A A A Cedar A A A- B+ B+ B+ A- B+ Diamond ------C- D F Grass ------F C+ --- Harriet A- B+ B+ A A A A A Hiawatha C+ C C- C+ C+ C+ C+ B- Isles C+ C+ B- C C C- C B- Nokomis C C C C C C+ D+ C+ Powderhorn ------D+ C Twin (SLP) ------D+ D D ---
Diamond Lake. Water quality grades ranged from A’s in Lake Calhoun and Lake Harriet to an F
for Diamond Lake.
Average summer surface TP concentrations in 4 out of 8 lakes monitored are less than 40 µg/L,
indicating full use for lakes within the North Central Hardwood Forest Ecoregion. The remaining
4 are classified as out of compliance (Table 6).
17 Table 6 Mean 2005 summer surface Secchi disk transparency, chlorophyll a concentration, total phosphorus concentration, and trophic state index means for lower watershed lakes. Red: out of compliance.
Secchi Total Disk Chlorophyll Phosphorus Waterbody (m) (ppb) (ppb) TSI Calhoun 5.6 2 14 38 Harriet 4.7 2 17 40 Cedar 2.2 8 25 50 Isles 2.0 20 37 56 Nokomis 1.4 19 56 59 Hiawatha 1.9 8 66 55 Powderhorn 1.3 14 95 61 Diamond 0.4 80 300 78
Water quality in lower watershed lakes is generally better now than it was in the 1970s. Many lower watershed lakes that were classified as out of compliance in the 1970s based on their average summer surface TP concentrations are now considered full use (Table 6). As seen in
Lake Minnetonka bays, average summer surface TP concentrations in lower watershed lakes in the 1970s were between 1.5 and 3.5 times higher than they are today. Long-term average summer surface TP, chlorophyll-a, Secchi depth, and TSI graphs for the lower watershed lakes can be found in the Subwatershed Summaries section of this report.
Caution must be taken when examining these long-term trends. As was noted for Lake
Minnetonka bays in the 1970s and 1980s, there were instances of insufficient numbers of samples taken in a given year.
The primary influx of nutrients into these lakes comes from stormwater runoff; an effort to reduce this type of pollution is the most likely reason that we have seen improvements in water
18 quality. However, intensive in-lake management has also taken place (e.g., rough fish removal, alum treatments) in some of these lakes to help improve water quality.
Minnehaha Creek
Water quality grab samples are collected weekly at ten sites along Minnehaha Creek in 2005.
Stream flow at the time of sampling was gauged using a velocity meter and using the area- velocity method. Stream report cards are presented in the Subwatershed Summaries section of this report. Flow-weighted mean nutrient and sediment concentrations and stream loading values are included in the Appendix.
Water quality and flow were measured at Grays Bay Dam (CMH07), I-494 (CMH19), W 34th
St. (CMH02), Excelsior Blvd. (CMH11), Browndale Dam (CMH03), W 56th (CMH04), Upton
Ave. (CMH12), Chicago Ave. (CMH05), 32nd Ave. (CMH17), and Hiawatha Ave. (CMH06).
Monitoring locations are shown in Figure 5.
Figure 5 Stream Monitoring Locations on Minnehaha Creek
Located under the Browndale Avenue Bridge in Edina, the Browndale Avenue Dam (CMH03) is
19 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. In addition to the three weekly manual readings recorded by the City of Edina, the water elevation at this location is recorded automatically every 15 minutes by a pressure transducer operated by MCWD.
Automated monitoring was conducted between March 25, 2005 and November 11, 2005. Total discharge was calculated using automated water surface elevation data collected during the monitoring period and manual readings collected by the City of Edina. Linear interpolation was used to calculate flow between ice out and the first recorded water level of 2005.
Flow in Minnehaha Creek averaged 38 cfs over the year at the headwaters structure, Grays Bay
Dam. Comparatively, average flow at Browndale Dam in Edina 11 miles downstream from
Grays Bay Dam averaged 30 cfs. Figure 6 depicts the average annual flow at the Browndale
Dam from 1997 to 2005.
Water quality grab samples were collected weekly at 10 sites along Minnehaha Creek March through November. New sites for 2005 included W 56th in Edina and Hiawatha Ave. in
Minneapolis. Flow is measured concurrent with the grab sample by the area-velocity methods.
Samples were analyzed for TP, SRP, TN, and TSS, as well as the in-situ parameters: DO, temperature, conductivity, and pH. A similar annual monitoring program has been in place since
1997. Flow-weighted mean concentrations and in-stream loads for Minnehaha Creek are
20 Figure 6 Average annual flow at the Browndale Dam (site CMH03)
120 100 80 60 40 20 Average Flow (cfs) 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
presented in the Appendix.
The 2005 median TP and TSS concentrations in Minnehaha Creek are low when compared with data (1986-1992) collected from minimally impacted streams in the North Central Hardwood
Forest ecoregion (Table 7). Mean values for these parameters are similar to the ecoregion means.
These findings are similar to findings in other years, indicating that Minnehaha Creek has good water quality when compared to streams without anthropogenic impacts. This is due in part to the large influx of clean water discharged from Lake Minnetonka.
Table 7 Northern Central Hardwood Forest Ecoregion vs. Minnehaha Creek 2005: median, mean, and maximum concentrations (summer)
Minnehaha Ecoregion Creek Median Mean Maximum Median Mean Maximum Conductivity (µmhos) 310 301 840 431 414 653 pH (S.U.) 8.1 8.2 8.9 8.21 8.24 9.03 Total Suspended Solids (mg/L) 10 9.1 29 7 9 59 Total Phosphorus (µg/L) 170 80 430 64 64 140
21 E. coli concentrations are indicators of the potential for human illness contracted through full body contact with surface water. Twenty-two E. coli bacteria sampling events took place in
Minnehaha Creek from June 3rd to November 2nd in 2005. Grab samples were analyzed for E. coli at the City of Minneapolis Labs. Samples were collected at ten sites along Minnehaha Creek.
The MPCA has an acute standard of 1,260 CFU/100 mL for E. coli; this standard applies to individual grab samples. A violation occurs when greater than 10% of the samples exceed the standard. Grab sample data collected in 2005 indicates that this acute standard was violated in
Minnehaha Creek for the three most downstream stations: Chicago Avenue, 32nd Avenue, and
Hiawatha Avenue (Figure 7). These violations occurred due to rainfall runoff events in late
August, late September, and early October.
Figure 7 E. coli grab samples in Minnehaha Creek, 2005
Grays W 34th Excelsior Browndale Upton Chicago 32nd Ave W 56th Hiawatha 100000
10000
1000
100
10 E. coli (CFU/100 mL) 1 5/24 6/5 6/17 6/29 7/11 7/23 8/4 8/16 8/28 9/9 9/21 10/3 10/15 10/27 11/8 11/20 2005 Date
The MPCA also has a 30-day geometric mean standard of 126 CFU/100 mL. This approach helps to dampen the statistical effect of major runoff events (like the ones discussed above),
22 giving us a better overall picture of the health of the system over the summer. Application of this technique is portrayed in Figure 8. The data from 2005 indicates that the 30-day standard was violated numerous times on most sites on Minnehaha Creek. Only the Grays Bay Dam site was always in compliance over this time period. The lower values for Grays Bay Dam are due to the relatively clean water draining from Lake Minnetonka.
Figure 8 E. coli 30-Day geometric means in Minnehaha Creek, 2005
Grays W 34th Excelsior Browndale Upton Chicago 32nd Ave W 56th Hiawatha 10000
1000
100
(CFU/100 mL) 10 30-Day Geometric Mean 1 5/28 6/17 7/7 7/27 8/16 9/5 9/25 10/15 11/4 2005 Mid-Point Date
There were 18 geometric mean values calculated for each station; the Upton and Chicago stations were in violation all 18 periods. The Excelsior and Hiawatha stations were in violation for 17 periods; the W 56th station was in violation 15 times. The 32nd Ave. station was in violation 13 times, the Browndale station 9 times, and the W 34th station 8 times. These E. coli violations indicate that there is a significant health threat to recreational users in Minnehaha
Creek.
23 Dissolved oxygen (DO) measurements are collected weekly at ten locations along Minnehaha
Creek. The measurements are discrete and do not take into account diurnal variation, and do not reflect the minimum daily DO concentrations. During the 2005 sampling season, DO concentrations measured in Minnehaha Creek were generally above the MN 7050 standard of 5 mg/L. Measurements dipped below the standard a few times during 2005 (Table 8). The violations at the I-494 station is most likely due to the large wetland complex just below Grays
Table 8 2005 Late-summer dry-weather DO profiles in Minnehaha Creek W W 32nd Date Grays I-494 34th Excelsior Browndale 56th Upton Chicago Ave Hiawatha 6/6/05 10.46 9.30 8.29 5.93 8.52 8.67 8.51 8.80 9.43 9.45 6/13/05 10.60 6.27 6.50 6.85 7.90 8.00 7.98 7.70 7.10 7.80 6/22/05 9.12 5.51 5.78 4.62 6.72 7.13 7.06 7.23 5.79 7.79 6/27/05 7.70 6.00 5.30 6.60 6.90 7.00 7.00 5.70 7.07 7/5/05 8.60 7.70 6.35 5.80 7.15 7.40 7.70 7.80 6.65 7.92 7/11/05 9.80 7.50 7.44 6.30 9.60 7.60 7.60 7.80 7.33 8.11 7/20/05 7.05 5.39 5.66 5.30 7.04 7.22 7.09 6.59 8.24 7.85 7/25/05 6.63 4.65 7.98 7.88 8.95 9.57 9.44 9.36 8.91 10.14 8/1/05 10.40 8.08 12.65 10.53 13.08 15.29 14.45 11.28 10.63 7.49 8/8/05 9.67 7.01 7.29 7.39 9.07 9.33 8.67 9.02 9.95 10.05 8/15/05 11.47 8.13 8.17 10.31 9.91 10.40 11.24 11.52 10.34 10.85 8/23/05 11.09 8.48 8.28 10.70 10.34 11.64 11.50 11.90 11.12 11.59 8/29/05 11.14 6.62 7.22 9.18 9.79 11.45 10.95 10.53 12.92 11.20 9/5/05 10.62 4.98 7.19 7.94 9.75 10.13 10.05 10.32 9.66 10.54 9/12/05 11.15 4.78 7.00 7.50 9.31 8.87 9.15 11.85 10.64 9/20/05 10.47 7.98 9.04 8.81 9.89 9.05 9.85 9.63 9.53 10.29
Bay Dam: decomposing plant matter can result in significant oxygen demands, lowering the ambient oxygen concentrations downstream.
In-stream nutrient and sediment loads to the Mississippi River from Minnehaha Creek in 2005 were calculated as TP: 7497 pounds; SRP: 1394 lbs; TN: 100,606 lbs; and TSS: 312 tons. In general, nutrient loads in Minnehaha Creek increase with distance downstream. From the Grays
24 Bay site to the Excelsior Ave. site one can see a gradual increase in TP and SRP loads (Figure 9).
The Browndale site is situated immediately downstream of the Browndale Dam; what we see is that nutrients are being lost in the impoundment. Phosphorus loads increase again between the Browndale and Chicago Ave. sites. Loads are relatively high beyond this point, compared to sites further upstream (Figure 9).
Figure 9 2005 TP and SRP nutrient loading profile for Minnehaha Creek
TP SRP
8000 7000 6000 5000 4000 3000 2000
Phosphorus Load (lbs) 1000 0
Grays I-494 Upton W. 34th W 56th Chicago Hwy 55 Excelsior 32nd Ave Browndale
From the Grays Bay site to the Excelsior Ave. site one can see a gradual increase in TN and TSS loads (Figure 10). The Browndale site is situated immediately downstream of the Browndale
Dam; what we see is that nitrogen and sediments are being lost in the impoundment. Loads increase again between the Browndale and Chicago Ave. sites. Loads are relatively high beyond this point, compared to sites further upstream, but do gradually fall off towards the 32nd Ave. site
(Figure 10).
25 Figure 10 2005 TN and TSS loading profile for Minnehaha Creek
60 600
50 500
40 400
30 300
TN Load (tons) 20 200 TSS Load (tons)
10 100
0 0
Grays I-494 Upton W. 34th W 56th Chicago Hwy 55 Excelsior 32nd Ave Browndale
The reservoirs of the Mill Pond (Browndale Dam) and Lake Hiawatha increase the residence time for Creek water. Hence one can see sediment and nutrient loads drop as Minnehaha Creek water passes through these waterbodies (Figure 10). For example, the TSS load decreases from
555 to 256 tons between the Chicago Ave. and 32nd Ave. stations.
In-stream areal loads calculated for 2005 indicate that the highest areal loads to Minnehaha
Creek come from the two smallest subwatersheds: the subwatershed between Browndale Dam and W 56th; and the subwatershed between 32nd Ave. and Hwy 55 (Table 9). Negative values indicated that there was a net loss through a given stream reach. For example, the Browndale and
32nd Ave. subwatersheds show a consistent loss: this is due to sediments and nutrients dropping out into the Browndale reservoir and Lake Hiawatha, respectively.
26 Table 9 Areal export of nutrients and sediments to Minnehaha Creek
TP SRP TN TSS lbs/sq lbs/sq lbs/sq tons/sq Subwatershed Area (sq. mi.) mi mi mi mi I-494 5.46 214 25 1216 15 W. 34th 8.01 203 72 1299 18 Excelsior 3.12 505 95 1732 87 Browndale 2.23 -1387 -319 -16030 -171 W 56th 0.80 2096 816 34328 114 Upton 1.41 1357 199 7055 131 Chicago 18.38 34 14 233 8 32nd Ave 7.50 -139 -78 -1457 -40 Hwy 55 0.35 3654 1234 83063 158
Upper Watershed Streams
Water quality grab samples were collected weekly at 26 locations on 13 major tributaries to Lake
Minnetonka from March through November (Figure 11). Water quality and flow were measured at the following sites: Christmas Lake Creek (CCH01), Classen Lake Creek (CCL01), Dutch
Lake Creek (CDU01), Forest Lake Creek (CFO01), Gleason Lake Creek (Outlet: CGL01, Inlet:
CGL03), Halsted Bay Inlet (North: CHI01, South: CHI02), Langdon Lake Creek (CLA01), Long
Lake Creek (Brown Road: CLO02, Lake Outlet: CLO01, Lake Inlet: CLO02), Painter Creek
(Deborah Drive: CPA03, CR6: CPA02, CR26: CPA04, Painter Drive: CPA06, West Branch
Road: CPA01, Hwy 110: CPA05), Peavey Creek (CPE01), Six Mile Creek (Hwy 5: CSI05,
Steiger: CSI04, Sunny: CSI03, Lunsten: CSI01, Hwy 7: CSI03), Stubbs Bay Inlet (CST01), and
Minnewashta Lake Creek (CMW01).
27 Figure 11 Stream monitoring stations in the upper watershed
Flow is measured concurrent with the grab sample either by gauging with the area-velocity method. Samples were analyzed for TP, SRP, TN, and TSS, as well as the in-situ parameters:
DO, temperature, conductivity and pH. Since 1997, a similar monitoring program has been implemented, though the number of sites monitored has doubled since 2000. Automated flow records were collected at three locations along Painter Creek, Long Lake Creek at the lake outlet and Brown Road, and Six Mile Creek at Lunsten Lake Outlet during 2005.
Upper Watershed Discharge
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.
28
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 subwatershed. When compared, the calculations based on weekly measurements do not differ significantly from those based on continuous measurements.
Discharge from the contributing subwatersheds during 2005 calculated from manual readings ranged from a time-weighted flow of 0.11 cfs at the Halsted Inlet North site to 6.33 cfs at the
West Branch Road site in the Painter Creek subwatershed. Comparatively, the discharge calculated for the entire 123-square mile upper watershed based on measurements at Grays Bay
Dam was 38 cfs. The average flow in Painter Creek at West Branch Road was 6.33 cfs over the year, which is lower that the 8.4 cfs long-term average for that station (Figure 12).
Figure 12 Average annual discharge in Painter Creek at West Branch Road
20
15
10
5 Average Flow (cfs) 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
Upper Watershed Water Quality
Water quality grab samples were collected weekly at all locations. In general the 2005 median, mean and maximum values seen in upper watershed sites were higher than data (1986-1992)
29 collected from minimally impacted streams in the North Central Hardwood Forest ecoregion
(Table 10). Maximums for conductivity, pH, TP, and TSS were significantly higher. One possible reason for this discrepancy is that many very small streams were included in the 2005 sampling program. These streams tend to be highly flashy, giving us very high water quality values after rain events. In addition, the region experienced several rain events in the late summer and early fall; these high-runoff events likely contributed to excessively high levels of sediments and nutrients to the streams. Flow-weighted mean concentrations and annual loading for upper watershed streams is presented in the Appendix.
Table 10 Northern Central Hardwood Forest Ecoregion vs. upper watershed streams 2005: median, mean, and maximum concentrations (summer)
Upper Watershed Ecoregion Streams Median Mean Maximum Median Mean Maximum Conductivity (µmhos) 310 301 840 457 481 916 pH (S.U.) 8.1 8.2 8.9 8.04 8.16 9.98 Total Suspended Solids (mg/L) 10 9.1 29 10 14 84 Total Phosphorus (µg/L) 170 80 430 247 255 784
Comparison of upper watershed streams to Minnehaha Creek (Table 7) yields interesting differences. In general, Minnehaha Creek and the upper watershed streams had comparable conductivity, pH, and TSS values. However, phosphorus values are higher for the upper watershed streams. There may be several reasons for this; possible factors include the residual impact of the old wastewater treatment plants and new construction in the upper watershed.
In-stream TP and SRP loading for upper watershed streams is depicted in Figure 13. The highest
TP loads to Lake Minnetonka are from the Painter Creek subwatershed.
30 Figure 13 In-stream TP and SRP loading for upper watershed streams
5000 2000 4500 1800 4000 1600 3500 1400 3000 1200 2500 1000 2000 800 1500 600 TP Load (lbs) 1000 400 SRP Load (lbs) 500 200 0 0 Dutch Forest Classen Peavey Cr Long Inlet Christmas Long Brown Stubbs Inlet Long Outlet Gleason Inlet Painter, CR 6 Painter, W Br Painter, CR 26 Halsted Inlet S Halsted Inlet N Gleason Outlet Painter, Deb Dr Six Mile, Hwy 5 Six Mile, Hwy 7 Virginia Outlet Langdon Outlet Six Mile, Sunny Six Mile, Steiger Painter, Hwy 110 Six Mile, Lunsten Painter, Painter Dr Station
The addition of several new water quality sampling stations in 2005 produced several interesting results. Loads in the Gleason Creek subwatershed indicate that Gleason Lake is behaving as a large P sink (Figure 13). The TP load at the Gleason Lake Inlet was 463 pounds, compared to
118 pounds at the Gleason Lake Outlet: 345 pounds of P was retained by the lake.
In contrast, Long Lake TP inputs (612 pounds) were exceeded by Long lake TP outputs (910 pounds). Hence Long Lake serves as a source of P to lower Long Creek. However, one must also consider that runoff from downtown Long Lake enters the lake between the two sampling sites: it could be the situation that this runoff is contributing to the P load, but no empirical measurements have been made to back this assertion.
In the Painter Creek system, TP loads increase downstream until the CR 6 location where the load levels off (Figure 13). This suggests that the wetland-stream system between CR 6 and CR
31 26 are in some sort of balance, with equal TP inputs and outputs. However, TP loads drop significantly between CR 26 and Painter Drive (from 1945 to 1410 pounds TP), suggesting that the wetland-stream system there is serving as a P sink. TP loads increase greatly between the
Painter Drive and West Branch Road sites, suggesting a strong input of P from this subwatershed. Possible sources of P from this region include steep stream banks and horse farms.
Between West Branch Road and Highway 110 the TP load drops, suggesting retention of P in this stretch of the stream.
The additional monitoring sites on Six Mile Creek indicate that relatively small TP loads are coming from the upper portion of this subwatershed (Figure 13). The Highway 5, Steiger Creek, and Sunny Creek stations empty into East Lake Auburn; the majority of the TP loads from Six
Mile Creek into Lake Minnetonka are generated between East Lake Auburn and Highway 7.
In-stream TN and TSS loading for upper watershed streams is depicted in Figure 14. The highest
TN and TSS loads to Lake Minnetonka are from the Painter Creek subwatershed. Loading patterns for TN and TSS are very similar to those seen for TP and SRP (Figure 13).
The TN data, however, suggests that the Long Lake, Painter Creek, and Six Mile Creek systems are strongly influenced by the presence of wetlands. Sources of nitrogen are not typically found in soil particles, implying that organic matter is the primary source. Vegetation and/or animal wastes are primary sources, and the three stream systems have had past and present influences from these sources.
32 Figure 14 In-stream TN and TSS loading for upper watershed streams
25000 400000 350000 20000 300000 15000 250000 200000 10000 150000 TN Load (lbs) 100000 TSS Load (lbs) 5000 50000 0 0 Dutch Forest Classen Peavey Cr Long Inlet Christmas Long Brown Stubbs Inlet Long Outlet Gleason Inlet Painter, CR 6 Painter, W Br Painter, CR 26 Halsted Inlet S Halsted Inlet N Gleason Outlet Painter, Deb Dr Six Mile, Hwy 5 Six Mile, Hwy 7 Virginia Outlet Langdon Outlet Six Mile, Sunny Six Mile, Steiger Painter, Hwy 110 Six Mile, Lunsten Painter, Painter Dr Station
In-stream areal loads calculated for 2005 indicate that the highest areal loads to Minnehaha
Creek come from the Classen Creek and Stubbs Inlet subwatersheds, the lower region of the
Long Creek subwatershed, and the lower reaches of the Painter Creek subwatershed (Table 11).
Negative values indicated that there was a net loss through a given stream reach. As was seen for total loads (Figures 13 and 14), several areas of the upper watershed are serving as nutrient sinks.
These include Gleason Lake, the Painter Creek CR 26 wetland, and the reach of Painter Creek between West Branch Road and Highway 110 (Table 11).
Through the Hydrodata monitoring program, watershed loads from nearly four-fifths of the subwatersheds tributary to Lake Minnetonka are measured. Measured TP loads to Lake
Minnetonka from upper watershed streams have ranged from 684 lbs in 2000 to 18,482 lbs in
33 Table 11 Upper watershed areal loads
TP SRP TN TSS lbs/sq lbs/sq lbs/sq tons/sq Subwatershed Area (sq. mi.) mi mi mi mi Christmas 1.17 10 1 214 0.6 Classen 1.55 565 175 2960 75.5 Dutch 2.95 68 25 789 4.4 Forest 1.00 334 155 1165 8.8 Gleason Outlet 1.50 -230 -66 -485 -11.4 Gleason Inlet 2.56 181 44 1098 8.0 Halsted Inlet N 0.82 43 7 521 0.1 Halsted Inlet S 0.57 196 109 842 0.5 Langdon Outlet 1.65 81 2 1153 4.6 Long Brown 1.56 985 304 1758 -19.7 Long Inlet 6.06 101 38 708 2.8 Long Outlet 4.65 64 -39 1859 14.1 Painter, Deb Dr 4.99 260 124 1693 3.5 Painter, CR 6 2.20 293 101 1827 7.8 Painter, CR 26 5.21 1 -5 -154 -1.9 Painter, Painter Dr 0.35 3,786 1580 22697 64.1 Painter, W Br 0.27 11,978 4400 54552 406.1 Painter, Hwy 110 0.49 -2,161 -1027 -10918 73.0 Peavey Cr 0.88 293 106 1973 2.8 Six Mile, Hwy 5 6.29 40 8 366 1.0 Six Mile, Steiger 1.52 34 10 474 0.2 Six Mile, Sunny 3.26 26 6 269 0.7 Six Mile, Lunsten 4.45 92 15 1580 3.6 Six Mile, Hwy 7 8.40 31 -11 140 5.0 Stubbs Inlet 0.79 680 329 2711 26.4 Virginia Outlet 6.24 11 0 231 0.4
2002 (Figure 15). During 2004 the measured TP load to Lake Minnetonka was 9774 pounds.
Painter Creek comprised 37% of the load, but only 21% of the sub-watershed area. In past years,
Painter Creek has comprised between 38 and 65% of the load to Lake Minnetonka. Six Mile
Creek, which has comprised a major portion of the load in previous years, has comprised up to
34 Figure 15 1997-2005 TP load to Lake Minnetonka from gauged subwatersheds
20000 17500 15000 12500 10000 7500 5000 TP Load (lbs) 2500 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
34% of the load to Lake Minnetonka, accounted for only 11% of the load during 2005. The data show that the Painter Creek subwatershed delivers the highest areal TP load; the Long Lake
Creek subwatershed delivers the second highest areal TP load (Table 11).
E. coli concentrations are indicators of the potential for human illness contracted through full body contact with surface water. Twenty-two E. coli bacteria sampling events took place at the
Painter Creek at West Branch Road and Six Mile Creek at Highway 7 stations in upper watershed streams from June 3rd to November 2nd in 2005. Grab samples were analyzed for E. coli at the City of Minneapolis Labs.
The MPCA has an acute standard of 1,260 CFU/100 mL for E. coli; this standard applies to individual grab samples. A violation occurs when greater than 10% of the samples exceed the standard. Six Mile Creek values ranged from 2 to 640 CFU/100 mL over the summer of 2005
(Figure 16). Painter Creek values ranged from 62 to 18000 CFU/100 mL over the summer of
35 Figure 16 E. coli grab samples in Six Mile and Painter Creeks, 2005
Six Mile Painter
5000 4000 3000
(CFU/100 mL) 2000
1000 E. coli 0 6/3 6/10 6/17 6/24 7/1 7/8 7/15 7/22 7/29 8/5 8/12 8/19 2005 Date
2005. However, values only exceeded 350 CFU/100 mL twice at this site, on August 18th and
October 5th. High concentrations were also seen in Minnehaha Creek on these dates due to a significant runoff event in the region (Figure 7).
The MPCA also has a 30-day geometric mean standard of 126 CFU/100 mL. Application of this technique is portrayed in Figure 17. The data from 2005 indicates that the 30-day standard was violated twice in Six Mile Creek, on September 22nd (127 CFU/100 mL) and
September 29th (133 CFU/100 mL). These relatively minor exceedances are most likely due to a fall flushing of the wetlands in lower Six Mile Creek. However, Painter Creek had numerous violations. The creek was above the standard from July 28th through the end of sampling on
October 20th. These E. coli violations indicate that there is a significant health threat to recreational users in Painter Creek
36 Figure 17 Geometric mean E. coli data in upper watershed streams, 2005
Six Mile Painter
600 500 400 300 200 (CFU/100 mL) 100
30-Day Geometric Mean 0 6/17 7/7 7/27 8/16 9/5 9/25 10/15
Dissolved oxygen concentrations in the upper watershed are generally lower than those observed in Minnehaha Creek (Tables 12 and 13). Mid to late summer DO measurements in upper watershed streams most frequently violate the MN 7050 Standard for DO of 5mg/L (no violations occurred in 2005 at the Long Lake Outlet and Classen Creek.
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 5mg/L. A minimum of 10 samples is necessary to consider the stream assessed.
37 Table 12 Upper watershed stream samples below 5mg/L DO (part 1).
Dutch Sunny Forest Steiger Peavey Langdon Christmas Minnewashta Halsted North Halsted South Six Mile Hwy 5 Six Mile Lunsten Date Six Mile Highland 6/7/05 5.67 5.53 5.03 5.48 2.34 3.55 4.77 3.20 2.50 5.83 7.28 6.44 5.53 6/15/05 6.56 12.24 6.40 5.60 4.15 2.51 3.76 2.84 2.40 4.78 7.49 12.24 6/20/05 5.13 9.41 6.00 6.50 3.10 1.79 0.97 1.07 7.04 8.02 5.30 3.50 6/30/05 4.68 3.67 4.46 8.00 4.30 1.06 4.30 1.10 1.15 7.09 8.10 5.50 3.67 7/6/05 5.53 7.76 6.30 6.72 3.05 1.47 2.09 1.03 1.29 7.50 7.66 5.70 7.76 7/13/05 4.28 4.00 4.46 4.90 0.95 1.40 1.70 1.90 1.17 5.30 3.80 5.30 7/20/05 4.88 7.20 1.60 4.36 1.04 1.19 1.14 1.32 1.39 6.50 4.36 2.96 7/25/05 7.03 8.40 7.31 3.76 2.38 2.57 4.43 5.72 2.51 10.80 7.86 6.16 4.10 8/2/05 7.01 8.80 1.58 6.49 1.17 0.98 1.19 1.22 3.53 6.35 6.55 2.73 8/10/05 7.72 8.19 1.57 1.66 1.56 1.99 2.69 2.52 2.73 4.60 2.61 6.84 8/15/05 10.56 2.39 2.14 2.09 2.39 2.02 5.86 5.41 3.59 9.36 8/24/05 10.10 5.62 3.53 1.91 3.87 1.88 5.55 7.17 5.91 8.57 8/30/05 9.28 10.81 2.58 4.27 2.19 4.47 8.50 7.74 6.05 5.86 3.77 8.55 11.63 9/7/05 7.08 12.49 3.60 3.31 2.45 1.69 6.23 3.35 3.35 8.14 9.36 8.32 6.33 9/13/05 6.60 10.36 6.75 3.08 1.55 1.47 5.89 2.63 2.45 8.00 7.66 12.62 5.18
Low DO is widespread in upper watershed streams. The occurrence of low DO in upper watershed streams is not surprising based on several factors including hydrology, riparian wetlands, topography, and historic anthropogenic affects. Measured DO concentrations in these streams make it possible for the MPCA to include them on their 303(d) list. Given the magnitude of this problem, the MCWD water quality specialist will undertake a thorough evaluation of the factors contributing to these low levels in the near future.
38
Table 13 Upper watershed stream samples below 5mg/L DO (part 2).
Classen Long inlet Long outlet Stubbs Bay Painter CR 6 Long (Brown) Painter CR 26 Painter CR110 Painter Deb Dr Painter Painter W Branch Date
6/15/05 5.30 8.79 10.32 5.95 2.58 5.72 3.84 5.78 5.70 4.32 9.89 6/21/05 4.73 7.39 10.60 4.75 1.23 4.27 2.20 3.72 2.74 2.86 9.12 6/29/05 2.98 5.14 9.42 4.01 0.79 2.57 1.75 3.09 2.04 1.45 8.00 7/7/05 3.25 6.17 10.24 4.76 0.84 3.13 1.90 4.08 3.31 1.63 7.91 7/13/05 4.40 3.92 9.64 5.11 2.09 2.57 1.30 4.70 6.16 3.16 7.04 7/21/05 1.43 4.76 7.98 4.29 1.85 3.49 1.21 3.63 1.09 7/26/05 5.22 12.16 11.37 6.98 3.97 5.35 2.69 5.86 4.24 2.62 10.90 8/3/05 2.74 8.71 12.17 4.55 1.86 3.95 0.86 3.94 1.14 2.24 12.10 8/10/05 2.68 9.26 7.05 4.87 5.20 1.94 5.76 2.31 0.76 8.99 8/17/05 1.26 6 1.99 2.01 1.84 6.61 1.52 2.40 8/24/05 1.66 8.71 3.51 7.07 3.06 7.18 4.00 2.81 8/31/05 6.05 11.72 7.92 4.66 8.44 4.12 1.98 2.16 12.00 9/7/05 7.78 12.16 12.71 7.02 2.54 6.94 4.69 5.46 2.80 3.06 12.19
9/14/05 9.11 11.83 11.22 7.46 2.06 7.12 4.03 5.57 2.88 3.93 11.70
39
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40 1. Minnehaha Creek Subwatershed The Minnehaha Creek sub-watershed encompasses the eastern half of the District, including everything east of Grays Bay dam. Water bodies monitored in the subwatershed include Minnehaha Creek, several lakes in Minneapolis (Calhoun, Cedar, Diamond, Harriet, Hiawatha, Isles, Nokomis, and Powderhorn), and Windsor Lake in Minnetonka. The 509 Plan goals for the sub-watershed include reducing in-lake TP concentrations to levels identified in the HHPLS plan, reducing chlorophyll-a concentrations to <14 µg/L, and increasing Secchi depth to >1.4 m. In addition, the 509 Plan calls for maintaining TP concentrations in Minnehaha Creek at < 80 µg/L and other nutrients at or below the ecoregion average.
Figure 1.1a Minnehaha Creek subwatershed
Lake Calhoun Lake Calhoun is part of the Minneapolis Chain of Lakes, receiving inflow from Lake of the Isles and flowing to Lake Harriet. Its water quality goals are to maintain a TP concentration of <25 µg/L (HHPLS plan), reduce chlorophyll-a concentrations to <14 µg/L, and increase Secchi depths to 1.4 m or greater. The lake’s TSI has been steadily decreasing since the 1970s, and continued to
41 decrease this year (Fig. 1.2h). Water quality in Lake Calhoun in 2005 was excellent – it met its water quality goals and received an A.
Secchi depth has increased in the lake in recent years (Fig. 1.2e). This year, Secchi depth ranged from 4 m to 8.5 m and averaged 5.6 m, one of the deepest average depths recorded (Fig. 1.2a).
Chlorophyll-a concentrations have been variable since monitoring began, but have averaged 5 µg/L or less for the last 5 years (Fig. 1.2f). This year, chlorophyll-a concentrations ranged from 0.9 µg/L to 5.8 µg/L and averaged 1.7µg/L, the lowest average value since monitoring began (Fig. 1.2b).
TP concentrations in the lake have been steadily declining since the mid-1990s (Fig. 1.2g). This year, average surface TP concentration was 14 µg/L, which meets both its water quality goals and the MPCA standards.
Cedar Lake Cedar Lake is located in the Minneapolis Chain of Lakes, receiving inflow from Brownie Lake and flowing to Lake of the Isles. Its water quality goals include maintaining TP concentrations below 25 µg/L, chlorophyll-a concentrations below 14 µg/L and a Secchi depth of >1.4 m. TSI in the lake has been around 50 for the past decade, which it maintained this year. This year, Cedar Lake’s water quality was good – it is in MPCA compliance, and nearly met its water quality goals. It was better than most lakes, receiving a B+.
Secchi depth ranged from 0.9 m to 5 m and averaged 2.2 m (Fig. 1.3a). Average Secchi depth was shallower than in 2004, but within the typical range for the lake (Fig. 1.3e). It meets the MPCA guidelines and its water quality goal for Secchi depth.
Average summer chlorophyll-a concentrations were very high in the 1980s and early 1990s. They dropped dramatically, but have been gradually increasing for the last several years (Fig. 1.3f). This year, concentrations ranged from 1 µg/L to 19 µg/L. Concentrations spiked in early spring and late summer, but most of the year were at or below 5 µg/L (Fig. 1.3b). The average concentration was 8 µg/L, which meets MPCA guidelines and the lake’s water quality goals.
42 Diamond Lake Diamond Lake is a shallow, hypereutrophic lake located in south Minneapolis. Its water quality goals include decreasing the TP concentration to <90 µg/L, chlorophyll-a concentration to <20 µg/L and increasing Secchi depth to >1 m. TSI has been variable, and this year it increased to 78 µg/L (Fig. 1.4g). Diamond Lake is out of compliance with the MPCA and is on its list of impaired waters. It does not meet its water quality goals and has some of the worst water quality in the area, receiving an F.
Secchi depth was below 1 m on all sampling dates, ranging from 0.3 m to 0.8 m (Fig. 1.4a). Its average Secchi depth was 0.4 m, the lowest average value recorded in the lake, and well below its water quality goal (Fig. 1.4d).
Chlorophyll-a concentrations ranged from 5 µg/L to 225 µg/L (Fig. 1.4b), and averaged 80 µg/L (Fig. 1.4e). This is one of the highest average values recorded in the lake, and is well above the MPCA standard.
Average surface TP concentration was the highest recorded on the lake (300 µg/L, Fig. 1.4f). It was above the MPCA standard on all sampling dates, ranging from 80 µg/L to 725 µg/L (Fig. 1.4c). It was also well above its water quality goal of 90 µg/L.
Lake Harriet Lake Harriet is the final lake on the Minneapolis Chain of Lakes, receiving input from Lake Calhoun and outletting to Minnehaha Creek. Its water quality goals include reducing average TP concentration to <20 µg/L, chlorophyll-a concentration to <14 µg/L, and increasing Secchi depth to >1.4 m. Lake Harriet improved on all counts from 2004 and had one of the lowest TSIs recorded on the lake (Fig. 1.5h). It is in compliance with the MPCA and met all of its water quality goals. Compared to area lakes, its water quality is excellent – it received an A.
Secchi depth was deeper than 2 m on every sampling date, ranging from 2.8 m to 8 m (Fig. 1.5a). Its average Secchi depth (4.7 m) was one of the better values recorded on the lake, and well above its goal and the MPCA standard (Fig. 1.5e).
43 Chlorophyll-a concentrations were below 8 µg/L on every sampling date, ranging from 1 µg/L to 7.9 µg/L (Fig. 1.5b). Its average summer concentration of 2 µg/L was the lowest average value recorded on the lake (Fig. 1.5f), and well below its goal and the MPCA standard.
Surface TP concentration spiked in early spring and late fall, but was below 20 µg/L for the entire summer (Fig. 1.5c). The average summer value (17 µg/L) is the lowest recorded on the lake, and appears to be part of a decreasing trend (Fig. 1.5g).
Lake Hiawatha Lake Hiawatha is located in south Minneapolis, adjacent to the Hiawatha Golf Course. Its inlet and outlet is Minnehaha Creek. Lake Hiawatha’s water quality goals include reducing the TP concentration to < 50 µg/L, chlorophyll-a concentration to <14 µg/L and increasing Secchi depth to >1.4 m. This year, Lake Hiawatha’s TSI improved slightly, but remained within the typical range for the lake (Fig. 1.6h). It is on the MPCA’s list of impaired waters for excess nutrients, but this year it met the MPCA’s standards. It nearly met its HHPLS water quality goals, and had better than average water quality, receiving a grade of B-.
Secchi depth ranged from 0.9 m to 2.6 m and averaged 1.9 m (Fig. 1.6a). This is one of the best average Secchi depths, and meets the MPCA standard and its water quality goal (Fig. 1.6e).
Chlorophyll-a concentrations spiked in the spring, but were below 10 µg/L for most of the year (Fig. 1.6b). The summer average concentration was 8 µg/L, which is one of the lowest values recorded on the lake and within the MPCA’s standard and its water quality goal.
Surface TP concentrations were above 60 µg/L for most of the year, and averaged 66 µg/L (Figs. 1.6c, g). This is a slight increase from 2004, and above its water quality goal. It does not meet the MPCA standard of 40 µg/L, but because it meets the standards for Secchi depth and chlorophyll-a, it is in compliance.
Lake of the Isles Lake of the Isles is part of the Minneapolis Chain of Lakes, located between Cedar Lake and Lake Calhoun. Its 509 goals include decreasing the average TP concentration to <40 µg/L, chlorophyll-a
44 concentration to <14 µg/L, and increasing Secchi depth to >1.4 m. It is on the MPCA’s list of impaired waters for excess nutrients, but this year it met the standards. It met most of its water quality goals, and had above average water quality, receiving a grade of B-.
Secchi depth was > 5 m for part of the spring and early summer, but decreased to < 1 m during a late summer algal bloom (Fig. 1.7a). The average Secchi depth was 2.0 m, which is one of the better average values on the lake (Fig. 1.7e). It meets the MPCA standards and its water quality goals.
Chlorophyll-a concentrations were high for most of the summer, reaching a maximum of 53 µg/L (Fig. 1.7b). Its average value was 20 µg/L, which is a decrease from the last two years, but within the typical range for the lake (Fig. 1.7f). It does not meet the MPCA standards or its water quality goals. However, since the lake met the standards for Secchi depth and TP concentration, it is in compliance.
The average surface TP concentration was 37 µg/L, which is a slight decrease to 2004 and close to the level maintained for the past decade (Fig. 1.7g). It meets the MPCA standard and water quality goals.
Lake Nokomis Lake Nokomis is located in south Minneapolis and outlets to Minnehaha Creek. Its 509 goals include reducing the TP concentration to <50 µg/L, chlorophyll-a concentration to <14 µg/L, and increasing the Secchi depth to >1.4 m. It is on the MPCA’s list of impaired waters for excess nutrients and does not meet its water quality goals.
Secchi depth ranged from 0.6 m to 3.5 m and averaged 1.4 m (Fig. 1.8a). This is a slight improvement from 2004, but within the typical range for the lake (Fig 1.8e). It does not meet the MPCA standard or its water quality goal.
Chlorophyll-a concentration spiked in spring and late summer, but was below 10 µg/L for most of the summer (Fig. 1.8b). It averaged 19 µg/L, which is slightly lower than average (Fig 1.8f), but does not meet the water quality goal or the MPCA standard.
45 Surface TP concentration gradually increased over the summer, reaching a maximum of 85 µg/L in the fall (Fig. 1.8c). This was accompanied by a gradual increase in TP at 7 m, perhaps indicating that the lake sediments are a source of TP (Fig. 1.8d). Average TP concentration was 56 µg/L, a decrease from 2004, but within the typical range for the lake (Fig. 1.8g). It exceeds the MPCA standard and its water quality goal.
Powderhorn Lake Powderhorn Lake is directly east of Lake Calhoun, in Powderhorn Park, Minneapolis. Its water quality goals include reducing the TP concentration to <120 µg/L, chlorophyll-a concentration to <14 µg/L, and increasing Secchi depth to >1.4 m. It is on the MPCA’s list of impaired waters for excess nutrients, but it meets some of its water quality goals. TSI on the lake has improved since monitoring began in 1996, and it continued to improve this year (Fig. 1.9h). Powderhorn Lake’s water quality is average, receiving a grade of C.
Secchi depth ranged from 0.7 m to 1.9 m (Fig. 1.9a) and averaged 1.3 m. This is an improvement from 2004, and part of an improving trend, but it still does not meet its water quality goals or the MPCA standard (Fig. 1.9e).
Chlorophyll-a concentrations varied over the summer, and averaged 14 µg/L (Figs. 1.9b, f). This is a dramatic decrease from 2004, and a large improvement since monitoring began. It didn’t quite meet its water quality goal and the MPCA’s standards, however.
Surface TP concentrations were above 50 µg/L for the entire summer and reached a maximum of 150 µg/L in early summer (Fig. 1.9c). The average concentration was 95 µg/L, which is a large decrease since monitoring began, but still is more than twice the MPCA standard (Fig. 1.9g). It meets its HHPLS goal, however.
Windsor Lake Windsor Lake is located in the north-eastern portion of Minnetonka. It has been monitored since 2004, so there are no long-term data or specified water quality goals for Windsor Lake. It does not meet the MPCA’s standards for any of the parameters, and has below average water quality, receiving a grade of D+.
46
Secchi depth ranged from 0.5 m to 1.1 m (Fig. 1.10a) and averaged 0.7 m. This is a decrease from 2004 and does not meet the MPCA standard.
Chlorophyll-a concentrations met the MPCA standard on only 3 sampling dates (Fig. 1.10b) and averaged 27 µg/L (Fig. 1.10e). This is a large decrease from 2004, but it is impossible to determine if this is a trend with only 2 years of data.
Surface TP concentrations were above 100 µg/L for most of the year (Fig. 1.10c), and the summer average was 105 µg/L. This is half the summer value of 2004 (Fig. 1.10f), but is still more than 5 times the MPCA standard.
Minnehaha Creek Minnehaha Creek flows from Grays Bay Dam to the Mississippi River. MCWD monitors ten sites on the creek: at Grays Bay Dam (CMH07), beneath the I-494 overpass (CMH19), at West 34th Street in Minnetonka (CMH02), at Excelsior Boulevard (in Meadowbrook Golf Course) in St. Louis Park (CMH11), at Browndale Dam in Edina (CMH03), at West 56th Street in Edina (CMH04), at Upton Avenue in Minneapolis (CMH12), at Chicago Avenue in Minneapolis (CMH05), at 32nd Avenue in Minneapolis (CMH17), and at the Hiawatha Train Bridge in Minneapolis (CMH06). The 509 Plan goals for Minnehaha Creek include maintaining TP concentrations at <80 µg/L in the creek, and keeping other nutrient concentrations at or below the ecoregion average (80 µg/L TP, 9.1 mg/L TSS).
47
Figure 1.1b Sampling sites on Minnehaha Creek
Flow in Minnehaha Creek increased slightly from 2005 at most sites, but was within the typical range for the creek. Flows were highest in early June at most sites, then decreased throughout the summer, and nearly stopped flowing in late August. High flows returned after the fall rains, and at some sites, peak flow occurred in October (Figs 1.10b-1.19b).
With a few exceptions, DO stayed above 5 mg/L throughout the year.
Conductivity was higher than average for the ecoregion in the spring, probably due to road salt running into the creek during the spring melt. For most of the year, it was close to the ecoregion average, except on 8/1/05, when conductivity was over 1,000 umhos/cm at most sites (Figs 1.10f- 1.19f). It reached a maximum of 10,308 umhos/cm at Chicago Avenue. The following week, conductivity measurements were back to more typical values. The anomalous values are probably due to equipment malfunction.
48 E. coli concentrations exceeded the MPCA’s standard (1,260 colony-forming units (CFU) per 100 mL) six times this year, usually following a storm. E. coli concentrations were highest on 10/5/05, when all sites except Grays Bay Dam exceeded the standard (Figs 1.10c-1.19c). This was the day after a storm, when some sites had the highest flows of the year. The highest concentrations of E. coli occurred at 32nd Avenue in Minneapolis, which exceeded the standard 4 times, reaching a maximum concentration of 38,000 CFU/100 mL on 10/5/05.
TSS concentrations were maintained throughout the creek, except at Browndale Dam, where they decreased. This probably occurred because solids dropped out of the water column in the dammed reach. At most sites, loads and concentrations were similar to 2004, and within the typical range for the creek (Figs. 1.10g-1.19g). The average TSS concentration for the ecoregion is 9.1 mg/L, and all sites were below that except Excelsior Boulevard, which averaged 11.24 mg/L. Minnehaha Creek exported 623,354 lbs of TSS.
TP loads and concentrations increased downstream. They were slightly lower than in 2004, but within the typical range for the creek (Figs. 1.10h-1.19h). At all sites, the average TP concentration was below 80 µg/L, and so met MCWD’s water quality goal and the ecoregion average. Minnehaha Creek exported 7,497 lbs of TP.
SRP loads and concentrations were maintained through out most of the channel, but dropped at Browndale Dam. TP did not decrease at the dam, so SRP was probably taken up by organisms in the dammed reach, resulting in a change in phosphorus form, but not in TP. SRP loads and concentrations returned to more typical values in 2005, after a sharp increase in 2004 (Figs. 1.10i - 1.19i). Minnehaha Creek exported 1,222 lbs of SRP in 2005.
TN loads and concentrations increased moving downstream. There was a slight decrease from 2004, but the loads and concentrations remained in the usual range for the creek (Figs. 1.10j-1.19j). Minnehaha Creek exported 96,039 lbs of TN in 2005.
49 Figure 1.2 Lake Calhoun 2005 Grade: A
2005 Date 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 0 1 2 3 4 5 6 7 Secchi Depth (m) 8 9 10 a.
6 5 4 3 2 1 Chlorophyll a (ppb) 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 22 m
) 20 40 µg/L
10 20
Phosphorus ( 0 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date 2005 Date c. d.
50 Fig 1.2 Lake Calhoun Summer Mean Values
6 2005 Mean = 5.6 m 5 TSIS = 35 4
3
2 Secchi Depth (m)
1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
30 2005 Mean = 1.7 ppb 25 TSIC = 36
20
15
10 Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
90 2005 Mean = 14 ppb 80 TSIP = 36 70
60
50
40
30
20 Total Phosphorus (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 38 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
51 Figure 1.3 Cedar Lake 2005 Grade: B+
2005 Date 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 0 1 2 3 4 5 Secchi Depth (m) 6 a.
25 20 15 10 5
Chlorophyll a (ppb) 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date b.
14 m
Surface TP Surface SRP Deep TP Deep SRP ) 60 300
µg/L 250 40 200 150 20 100
Phosphorus ( 50 0 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date 2005 Date c. d.
52 Fig. 1.3 Cedar Lake Summer Mean Values
6 2005 Mean = 2.2 m 5 TSIS = 48 4
3
2 Secchi Depth (m) 1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
35 2005 Mean = 8 ppb 30 TSIC = 50 25
20
15
10 Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
160 2005 Mean = 25 ppb 140 TSIP = 51 120
100
80
60
40 Total Phosphorus (ppb) 20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 50 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
53 Figure 1.4 Diamond Lake 2005 Grade: F
2005 Date 4/1 4/29 5/27 6/24 7/22 8/19 9/16 10/14 11/11 0.0 0.2 0.4 0.6 0.8 Secchi Depth (m) 1.0 a.
250 200 150 100 50 Chlorophyll a (ppb) 0 4/1 4/29 5/27 6/24 7/22 8/19 9/16 10/14 11/11 2005 Date b.
Surface TP Surface SRP
800 ) 700
µg/L 600 500 400 300 200
Phosphorus ( 100 0 4/1 4/29 5/27 6/24 7/22 8/19 9/16 10/14 11/11 2005 Date c.
54 Fig. 1.4 Diamond Lake Summer Mean Values
3.5 2005 Mean = 0.4 m 3.0 TSIS = 75 2.5
2.0
1.5
1.0 Secchi Depth (m)
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 d.
160
140 2005 Mean = 80 ppb TSIC = 74 120
100
80
60
40 Chlorophyll a (ppb)
20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
350 2005 Mean = 300 ppb 300 TSIP = 86 250
200
150
100
Total Phosphorus (ppb) 50
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 TSI = 78 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year g.
55 Figure 1.5 Lake Harriet 2005 Grade: A
2005 Date 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 0 1 2 3 4 5 6 7
Secchi Depth (m) 8 9 a.
9 8 7 6 5 4 3
Chlorophyll a (ppb) 2 1 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date b.
20 m Surface TP Surface SRP Deep TP Deep SRP 60 300
) 250
µg/L 40 200
150
20 100
50 Phosphorus ( 0 0 2/1 3/1 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 10/11 2005 Date 2005 Date c. d.
56 Fig. 1.5 Lake Harriet Summer Mean Values
7 2005 Mean = 4.7 m 6 TSIS = 38 5
4
3
Secchi Depth (m) 2
1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
14 2005 Mean = 2 ppb 12 TSIC = 39 10
8
6
Chlorophyll a (ppb) 4
2
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
60 2005 Mean = 17 ppb 50 TSIP = 45
40
30
20 Total Phosphorus (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80
70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
57 Figure 1.6 Lake Hiawatha 2005 Grade: B-
2005 Date 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 0.0 0.5 1.0 1.5 2.0
Secchi Depth (m) 2.5 3.0 a.
70 60 50 40 30 20 10 Chlorophyll a (ppb) 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date b.
4 m Surface TP Surface SRP Deep TP Deep SRP
120 140 ) 100 120 µg/L 80 100 80 60 60 40 40 20 Phosphorus ( 20 0 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date 2005 Date c. d.
58 Fig. 1.6 Lake Hiawatha Summer Mean Values
2.5 2005 Mean = 1.9 m TSIS = 51 2.0
1.5
1.0 Secchi Depth (m)
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
60
50 2005 Mean = 8 ppb TSIC = 50 40
30
20 Chlorophyll a (ppb)
10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
200 2005 Mean = 66 ppb 180 TSIP = 65 160 140 120 100 80 60 Total Phosphorus (ppb) 40 20 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 55 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
59 Figure 1.7 Lake of the Isles 2005 Grade: B-
2005 Date 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 0 1 2 3 4
Secchi Depth (m) 5 6 a.
60 50 40 30 20 10 Chlorophyll a (ppb) 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date b.
8 m Surface TP Surface SRP Deep TP Deep SRP
60 250 ) 200 µg/L 40 150 100 20 50 Phosphorus ( 0 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date 2005 Date c. d.
60 Fig. 1.7 Lake of the Isles Summer Mean Values
2.5 2005 Mean = 2.0 m
2.0 TSIS = 50
1.5
1.0 Secchi Depth (m)
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
160 2005 Mean = 20 ppb 140 TSIC = 60 120
100
80
60
Chlorophyll a (ppb) 40
20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
250 2005 Mean = 37 ppb TSIP = 56 200
150
100 Total Phosphorus (ppb) 50
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 56 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
61 Figure 1.8 Lake Nokomis 2005 Grade: C+
2005 Date 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 0
1
2
3 Secchi Depth (m) 4 a.
50 40 30 20 10
Chlorophyll a (ppb) 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 7 m
100 250 ) 80 200 µg/L 60 150 40 100 20 50 Phosphorus ( 0 0 2/14 3/14 4/11 5/9 6/6 7/4 8/1 8/29 9/26 10/24 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date 2005 Date c. d.
62 Fig. 1.8 Lake Nokomis Summer Mean Values
2.5 2005 Mean = 1.4 m TSIS = 55 2.0
1.5
1.0 Secchi Depth (m)
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
70 2005 Mean = 19 ppb 60 TSIC = 59 50
40
30
Chlorophyll a (ppb) 20
10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
120
100 2005 Mean = 56 ppb TSIP = 62 80
60
40 Total Phosphorus (ppb) 20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 59 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
63 Figure 1.9 Powderhorn Lake 2005 Grade: C
2005 Date 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 0.0 0.5 1.0 1.5 2.0 Secchi Depth (m) 2.5 a.
40
20
Chlorophyll a (ppb) 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date b.
7 m Surface TP Surface SRP Deep TP Deep SRP
200 600 ) 500
µg/L 150 400 100 300
sphorus ( 200 50 100 Pho 0 0 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2/1 3/1 3/29 4/26 5/24 6/21 7/19 8/16 9/13 10/11 2005 Date 2005 Date c. d.
64 Fig. 1.9 Powderhorn Lake Summer Mean Values
1.4 2005 Mean = 1.3 m 1.2 TSIS = 56 1
0.8
0.6
Secchi Depth (m) 0.4
0.2
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
100 90 2005 Mean = 14 ppb 80 TSIC = 57 70 60 50 40 30 Chlorophyll a (ppb) 20 10 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
200 2005 Mean = 95 ppb 180 TSIP = 70 160 140 120 100 80 60 Total Phosphorus (ppb) 40 20 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 61 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
65 Figure 1.10 Minnehaha Creek, CMH07 – Grays Bay Dam, City of Minnetonka Drainage Area: 123.23 sq. mi.
350 25 30 300 25 20 250 20 15 200 15 150 10 10
Discharge (cfs) 100 Temperature (C) 5 5 50 Dissolved Oxygen (mg/L) 0 0 0 3/1 4/20 6/9 7/29 9/17 11/6 4/20 6/9 7/29 9/17 11/6 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
200 140 175 120 150 100 125 80 100 60 (per 100 mL) 75 40 50 E.coli Average Flow (cfs) 20 25 0 0 2001 2002 2003 2004 2005 6/3 7/3 8/2 9/1 10/1 10/31 2005 Date Year c. E. coli concentration by date d. Average flow by year
12 450
10 400
350 8 pH 300 6 250 Conductivity (umho/cm) 4 200 3/1 4/20 6/9 7/29 9/17 11/6 3/1 4/20 6/9 7/29 9/17 11/6 2005 Date 2005 Date e. pH by date f. Conductivity by date
66 Fig. 1.10 Minnehaha Creek (CMH07) 2005 Flow-Weighted Concentrations and Loads 4 700 600 3 500 400 2 300 1 200
Mean TSS (ppm) 100 TSS Load (1000*lbs) 0 0 2001 2002 2003 2004 2005 Year g. 40 6000 5000 30 4000 20 3000 2000 10 TP Load (lbs)
Mean TP (ppb) 1000 0 0 2001 2002 2003 2004 2005 Year h.
20 1200 1000 15 800 10 600 400 5
200 SRP Load (lbs) Mean SRP (ppb) 0 0 2001 2002 2003 2004 2005 Year i. 1.5 200000
150000 1 100000 0.5 50000 TN Load (lbs) Mean TN (ppm) 0 0 2001 2002 2003 2004 2005 Year j.
67 Figure 1.11 Minnehaha Creek, CMH19 – I 494, City of Minnetonka Drainage Area: 128.69 sq. mi.
200 18 30
15 25 150 12 20 100 9 15 Flow (cfs) 6 10 50 Temperature (C) 3 5 Dissolved Oxygen (mg/L) 0 0 0 3/1 4/10 5/20 6/29 8/8 9/17 10/27 3/1 4/10 5/20 6/29 8/8 9/17 10/27 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
90 80 70 60 No E. coli 50 sampling 40 30 20 Average Flow (cfs) 10 0
1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
c. Average flow by year
12 1400 1200 10 1000 8 800
pH 600 6 400 4 200 Conductivity (umho/cm) 0 2 3/1 4/20 6/9 7/29 9/17 11/6 3/1 4/15 5/30 7/14 8/28 10/12 2005 Date 2005 Date d. pH by date e. Conductivity by date
68 Fig. 1.11 Minnehaha Creek (CMH19) 2005 Flow-Weighted Concentrations and Loads
20 1200 1000 15 800 10 600 400 5 200 Mean TSS (ppm)
0 0 TSS Load (1000*lbs) 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year f. 150 7000 6000 100 5000 4000 3000 50 2000 TP Load (lbs) Mean TP (ppb) 1000 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g. 70 1000 60 800 50 40 600 30 400 20
200 SRP Load (lbs) Mean SRP (ppb) 10 0 0 2000 2001 2002 2003 2004 2005 Year h. 1.5 200000
150000 1 100000 0.5 50000 TN Load (lbs) Mean TN (ppm) 0 0 2000 2001 2002 2003 2004 2005 Year i.
69 Figure 1.12 Minnehaha Creek, CMH02 – West 34th Street, City of Minnetonka Drainage Area: 136.7 sq. mi.
25 30 150
20 25 125 20 100 15 15 75 10
10 Flow (cfs) 50 5 Temperature (C) 5 25 Dissolved Oxygen (mg/L) 0 0 0 3/1 4/10 5/20 6/29 8/8 9/17 10/27 3/1 5/1 7/1 9/1 11/1 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
1250 120 10/5: 9800/100 mL 100 1000 80 750 60
(per 100 mL) 500 40 E. coli Average Flow (cfs) 20 250 0
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 6/3 7/23 9/11 10/31 2005 Date Year c. E. coli by date d. Average flow by year
12 7500
10 6000 8 4500 6 pH 3000 4 2 1500
0 Conductivity (umho/cm) 0 3/1 5/1 7/1 9/1 11/1 3/1 5/1 7/1 9/1 11/1 2005 Date 2005 Date e. pH by date f. Conductivity by date
70 Fig. 1.12 Minnehaha Creek (CMH02) 2005 Flow-Weighted Concentrations and Load
12 1200 10 1000 8 800 6 600 4 400
Mean TSS (ppm) 2 200 TSS Load (1000*lbs) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g.
120 12000 100 10000 80 8000 60 6000 40 4000 TP Load (lbs) Mean TP (ppb) 20 2000 0 0 199719981999200020012002200320042005 Year h. 50 3000
40 2500 2000 30 1500 20 1000 SRP Load (lbs) Mean SRP (ppb) 10 500 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i. 1.4 200000 1.2 1 150000 0.8 100000 0.6 0.4 50000 TN Load (lbs) Mean TN (ppm) 0.2 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year j.
71 Figure 1.13 Minnehaha Creek, CMH11 – Excelsior Boulevard, St. Louis Park Drainage Area: 139.82 sq. mi.
25 35 140 30 120 20 25 100 20 15 80 15 60 10 10 Flow (cfs)
Temperature (C) 40 5 5 0 20 Dissolved Oxygen (mg/L) 0 -5 0 3/1 4/10 5/20 6/29 8/8 9/17 10/27 3/1 4/20 6/9 7/29 9/17 11/6 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
2500 100 10/5: 13,000/100 mL 2000 80
1500 60
(per 100 mL) 1000 40
20 Average Flow (cfs) E. coli 500 0 0 1999 2000 2001 2002 2003 2004 2005 4/8 5/28 7/17 9/5 10/25 12/14 2005 Date Year c. E. coli concentration by date d. Average flow by year 1500
11 1250 8/1: 7505.5 umho/cm 1000 9 750 pH
500 7 250 Conductivity (umho/cm)
5 0 3/1 4/10 5/20 6/29 8/8 9/17 10/27 3/1 4/20 6/9 7/29 9/17 11/6 2005 Date 2005 Date e. pH by date f. Conductivity by date
72 Fig. 1.13 Minnehaha Creek (CMH11) 2005 Flow-Weighted Concentrations and Loads
30 1200 25 1000 20 800 15 600 10 400
Mean TSS (ppm) 5 200
0 0 TSS Load (1000*lbs) 1999 2000 2001 2002 2003 2004 2005 Year g.
200 14000 12000 150 10000 8000 100 6000 4000 50 TP Load (lbs) Mean TP (ppb) 2000 0 0 1999 2000 2001 2002 2003 2004 2005 Year h.
60 4000 50 3000 40 30 2000 20 1000 SRP Load (lbs) Mean SRP (ppb) 10 0 0 1999 2000 2001 2002 2003 2004 2005 Year i.
1.2 200000 1 150000 0.8 0.6 100000 0.4
50000 TN Load (lbs) Mean TN (ppm) 0.2 0 0 1999 2000 2001 2002 2003 2004 2005 Year j.
73 Figure 1.14 Minnehaha Creek, CMH03 – Browndale Dam, City of Edina Drainage Area: 142.05 sq. mi
25 35 100
30 20 80 25 60 15 20
15 10 Flow (cfs) 40
10 Temperature (C) 5 20 Dissolved Oxygen (mg/L) 5
0 0 0 3/1 4/20 6/9 7/29 9/17 11/6 3/1 4/20 6/9 7/29 9/17 11/6 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
2500 120 10/5: 12,000/100 mL 2000 100 80 1500 60
(per 100 mL) 1000 40
E. coli 500 Average Flow (cfs) 20
0 0 1997 1998 19992000 2001 2002 2003 2004 2005 6/3 7/3 8/2 9/1 10/1 10/31 2005 Date Year c. E. coli concentration by date d. Average flow by year
12 1200
1000 10 8/1: 8458.2 umho/cm 800
8 600 pH
400 6
Conductivity (umho/cm) 200
4 0 3/1 4/20 6/9 7/29 9/17 11/6 3/1 4/20 6/9 7/29 9/17 11/6 2005 Date 2005 Date e. pH by date f. Conductivity by date
74 Fig. 1.14 Minnehaha Creek (CMH03) 2005 Flow-Weighted Concentrations and Loads 15 8000
6000 10 4000 5
Mean TSS (ppm) 2000 TSS Load (1000*lbs) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g. 140 14000 120 12000 100 10000 80 8000 60 6000 40 4000 TP Load (lbs) Mean TP (ppb) 20 2000 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h. 35 3500 30 3000 25 2500 20 2000 15 1500 10 1000 SRP Load (lbs) Mean SRP (ppb) 5 500 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i. 1.5 200000
150000 1 100000 0.5 50000 TN Load (lbs) Mean TN (ppm) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year j.
75 Figure 1.15 Minnehaha Creek, CMH04 – West 56th Street, City of Edina Drainage Area: 142.85 sq. mi.
24 35 200
20 30 150 25 16 20 12 100 15 8 Flow (cfs) 10 Temperature (C) 50
Dissolved Oxygen (mg/L) 4 5 0 0 0 4/5 5/15 6/24 8/3 9/12 10/22 4/5 5/15 6/24 8/3 9/12 10/22 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
1400 8/18: 4000/100 mL 1200 10/5: 11,000/100 mL 1000 Flow data from previous 800 years not available – 2005
(per 100 mL) 600 average flow = 41.89 cfs 400 E. coli 200
0 6/3 7/18 9/1 10/16 2005 Date c. E. coli concentration by date
11 1250 8/1: 8713.2 umho/cm 10 1000
9 750 8 pH 500 7 250 6 Conductivity (umho/cm) 5 0 4/5 4/30 5/25 6/19 7/14 8/8 9/2 9/27 10/22 4/5 4/30 5/25 6/19 7/14 8/8 9/2 9/27 10/22 2005 Date 2005 Date d. pH by date d. Conductivity by date
76 Figure 1.15 Minnehaha Creek (CMH04) 2005 Nutrient Concentrations by Date
15
12
9
6 TSS (ppm) 3
0 4/5 4/25 5/15 6/4 6/24 7/14 8/3 8/23 9/12 10/2 10/22 11/11 2005 Date a.
250
200
150
100 TP (ppb)
50
0 4/5 4/30 5/25 6/19 7/14 8/8 9/2 9/27 10/22 2005 Date b. 30
25
20
15
SRP (ppb) 10
5
0 4/5 4/30 5/25 6/19 7/14 8/8 9/2 9/27 10/22 2005 Date c.
2.0
1.5
1.0 TN (ppm) 0.5
0.0 4/5 4/30 5/25 6/19 7/14 8/8 9/2 9/27 10/22 2005 Date d.
77 Figure 1.16 Minnehaha Creek, CMH12 – Upton Avenue, City of Minneapolis Drainage Area: 144.26 sq. mi.
25 35 175
30 150 20 25 125
15 20 100 75
15 Flow (cfs) 10 50 10 Temperature (C) 5 Dissolved Oxygen (mg/L) 5 25
0 0 0 3/1 5/1 7/1 9/1 11/1 3/1 5/1 7/1 9/1 11/1 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
1200 120
1000 100 8/18: 7600/100 mL 10/5: 11,000/100 mL 800 80
600 60
(per 100 mL) 40 400 Average Flow (cfs) 20 E.coli 200 0 0 1999 2000 2001 2002 2003 2004 2005 6/3 7/3 8/2 9/1 10/1 10/31 2005 Date Year c. E. coli concentration by date d. Average flow by year
1200 10
1000 9 8/1: 9452.5 umho/cm 800 8 600 pH 7 400 6 Conductivity (umho/cm) 200
5 0 3/1 5/1 7/1 9/1 11/1 3/1 5/1 7/1 9/1 11/1 2005 Date 2005 Date e. pH by date f. Conductivity by date
78 Fig. 1.16 Minnehaha Creek (CMH12) 2005 Flow-Weighted Concentrations and Loads
80 3000 2500 60 2000 40 1500 1000 20 500 Mean TSS (ppm) 0 0 TSS Load (1000*lbs) 1999 2000 2001 2002 2003 2004 2005 Year g.
300 15000 250 200 10000 150 100 5000 TP Load (lbs)
Mean TP (ppb) 50 0 0 1999 2000 2001 2002 2003 2004 2005 Year h.
70 7000 60 6000 50 5000 40 4000 30 3000 20 2000 SRP Load (lbs)
Mean SRP (ppb) 10 1000 0 0 1999 2000 2001 2002 2003 2004 2005 Year i. 2 250000
1.5 200000 150000 1 100000 0.5 TN Load (lbs)
Mean TN (ppm) 50000 0 0 1999 2000 2001 2002 2003 2004 2005 Year j.
79 Figure 1.17 Minnehaha Creek, CMH05 – Chicago Avenue, City of Minneapolis Drainage Area: 162.64 sq. mi.
25 35 250 30 20 200 25 15 20 150
10 15 100 Flow (cfs) 10 5 Temperature (C) 50 5 Dissolved Oxygen (mg/L) 0 0 0 3/1 4/20 6/9 7/29 9/17 11/6 3/1 5/1 7/1 9/1 11/1 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
1750 120
1500 100 8/18: 6200/100 mL 1250 10/5: 9500/100 mL 80
1000 60
(per 100 mL) 750 40 Average Flow (cfs) 500 20 E. coli
250 0
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 6/3 7/3 8/2 9/1 10/1 10/31 2005 Date Year c. E. coli concentration by date d. Average flow by year
12 1000
800 10 8/1: 10307.6 umho/cm 600
pH 8 400
6 200 Conductivity (umho/cm)
4 0 3/1 4/20 6/9 7/29 9/17 11/6 3/1 4/20 6/9 7/29 9/17 11/6 2005 Date 2005 Date e. pH by date f. Conductivity by date
80 Fig. 1.17 Minnehaha Creek (CMH05) 2005 Flow-Weighted Concentrations and Loads
50 3000
40 2500 2000 30 1500 20 1000 10 Mean TSS (ppm) 500 TSS Load (1000*lbs) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g. 200 16000 14000 150 12000 10000 100 8000 6000 TP Load (lbs)
Mean TP (ppb) 50 4000 2000 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h. 60 5000
50 4000 40 3000 30 2000 20 SRP Load (lbs) Mean SRP (ppb) 10 1000 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i. 1.8 200000 1.6 1.4 150000 1.2 1 100000 0.8 0.6
50000 TN Load (lbs) Mean TN (ppm) 0.4 0.2 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year j.
81 Figure 1.18 Minnehaha Creek, CMH17 – 32nd Avenue, City of Minneapolis Drainage Area: 170.15 sq. mi.
25 35 250 30 20 200 25 15 20 150 15 10 100 10 Flow (cfs) 5 Temperature (C) 50 5 Dissolved Oxygen (mg/L) 0 0 0 3/1 4/20 6/9 7/29 9/17 11/6 3/1 4/20 6/9 7/29 9/17 11/6 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
2000 120 9/15: 38,000/100 mL 10/5: 28,000/100 mL 100 1500 80
1000 60
(per 100 mL) 40 500
Average Flow (cfs) 20 E. coli 0 0 6/3 7/3 8/2 9/1 10/1 10/31 1999 2000 2001 2002 2003 2004 2005 2005 Date Year c. E. coli concentration by date d. Average flow by year 12 1000
800 10 600 8 pH 400
6 200 Conductivity (umho/cm)
4 0 3/1 4/20 6/9 7/29 9/17 11/6 3/1 4/20 6/9 7/29 9/17 11/6 2005 Date 2005 Date e. pH by date f. Conductivity by date
82 Fig. 1.18 Minnehaha Creek (CMH17) 2005 Flow-Weighted Concentrations and Loads 20 2000
15 1500
10 1000
5 500 Mean TSS (ppm)
0 0 TSS Load (1000*lbs) 1999 2000 2001 2002 2003 2004 2005 Year g. 150 15000
100 10000
50 5000 TP Load (lbs) Mean TP (ppb) 0 0 1999 2000 2001 2002 2003 2004 2005 Year h. 35 8000 30 25 6000 20 4000 15 10 2000 SRP Load (lbs)
Mean SRP (ppb) 5 0 0 1999 2000 2001 2002 2003 2004 2005 Year i. 2 250000
1.5 200000 150000 1 100000 0.5 50000 TN Load (lbs) Mean TN (ppm) 0 0 1999 2000 2001 2002 2003 2004 2005 Year j.
83 Figure 1.19 Minnehaha Creek, CMH06 – Hiawatha Train Bridge, Minneapolis Drainage Area: 170.49 sq. mi.
28 35 200 24 30
20 25 150
16 20 100 12 15 Flow (cfs) 8 10 50 Temperature (C) 4 5 Dissolved Oxygen (mg/L) 0 0 0
3/1 6/9 7/4 3/1 6/9 7/4 3/26 4/20 5/15 7/29 8/23 9/17 10/12 11/6 3/26 4/20 5/15 7/29 8/23 9/17 10/12 11/6 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
8000
6000 Flow data from previous
4000 years not available – 2005
(per 100 mL) average flow = 55.4 cfs
2000 E.coli
0 6/3 7/23 9/11 10/31 2005 Date c. E. coli concentration by date
11 1250
10 1000 9 750 8 pH 500 7 250 6
5 Conductivity (umho/cm) 0
3/1 6/9 7/4 3/1 3/26 4/20 5/15 6/9 7/4 7/29 8/23 9/17 11/6 3/26 4/20 5/15 7/29 8/23 9/17 11/6 10/12 2005 Date 10/12 2005 Date
d. pH by date e. Conductivity by date
84 Fig. 1.19 Minnehaha Creek (CMH06) 2005 Nutrient Concentrations by Date
15
12
9
6 TSS (ppm) 3
0 3/1 3/21 4/10 4/30 5/20 6/9 6/29 7/19 8/8 8/28 9/17 10/7 10/27 2005 Date f.
250
200
150
100 TP (ppb) 50
0 3/1 3/26 4/20 5/15 6/9 7/4 7/29 8/23 9/17 10/12 11/6 2005 Date g. 50
40
30
20 SRP (ppb) 10
0 3/1 3/26 4/20 5/15 6/9 7/4 7/29 8/23 9/17 10/12 11/6 2005 Date h.
3.0
2.5
2.0
1.5
TN (ppm) 1.0
0.5
0.0 3/1 3/26 4/20 5/15 6/9 7/4 7/29 8/23 9/17 10/12 11/6 2005 Date i.
85 2. Lake Minnetonka Subwatershed The Lake Minnetonka sub-watershed is located in the central part of the district, and includes the cities of Orono, Minnetrista, Mound, Spring Park, Shorewood, Tonka Bay, Minnetonka Beach, Wayzata, Woodland, Deephaven, Minnetonka, Greenwood, Excelsior, Victoria, and Chanhassen. In addition to Lake Minnetonka, MCWD monitors Peavey and Shavers lakes. The 509 Plan goals include maintaining TP concentrations specific to each bay, preventing degradation of Marion, Shavers, Louise, and Lost lakes, maintaining MPCA standards for Secchi depth and chlorophyll-a concentrations, and minimizing pollutant loading from upstream sub-watersheds.
Figure 2.1 Lake Minnetonka subwatershed
Carsons Bay Carsons Bay is one of the eastern bays of Lake Minnetonka, located in the city of Deephaven. The water quality goals for this bay include a TP concentration of <50 µg/L, chlorophyll-a concentration of <14 µg/L, and a Secchi depth of >1.4 m. Carsons Bay has been monitored since 2004, so there is no long-term data available. Compared to other lakes in the region, it is above average, receiving a grade of B+.
86 Secchi depth was above 2 m for all sampling dates (Fig. 2.2a), and averaged 2.9 m. This is slightly shallower than 2004, but easily meets its water quality goal and the MPCA standards (Fig. 2.2d).
Chlorophyll-a concentrations ranged from 2 µg/L to 8.2 µg/L, and averaged 6 µg/L (Figs. 2.2b, e). Although this is higher than in 2004, it still easily meets its water quality goals and the MPCA standards.
TP concentrations were below 30 µg/L for all sampling dates, and averaged 24 µg/L (Fig. 2.2c). This is the same average concentration recorded in 2004, and well below its water quality goals and the MPCA standard (Fig. 2.2f).
Cooks Bay Cooks Bay is located in the western portion of Lake Minnetonka, in the city of Mound. Its water quality goals are a TP concentration of < 30 µg/L, chlorophyll-a concentration of <14 µg/L, and a Secchi depth of >1.4 m. TSI has been consistent since monitoring began in the lake. This year, it was 54, a typical value (Fig. 2.3h). Compared to other lakes in the region, Cooks Bay is average, receiving a grade of B-.
Secchi depth decreased over the course of the summer, concurrent with an increase in chlorophyll-a (Fig. 2.3a). The average Secchi depth was 2.1 m, which is deeper than in 2004, and within the range seen in the bay (Fig. 2.3e). It meets its water quality goals and the MPCA standard.
Chlorophyll-a gradually increased over the summer, reaching a peak of 22 µg/L in August (Fig. 2.3b). It averaged 15 µg/L, which is lower than 2004, but one of the highest average concentrations recorded in Cooks Bay (Fig. 2.3f). Average chlorophyll-a concentrations appear to be gradually increasing, although it is difficult to tell with only 9 years of data.
Surface TP concentrations were generally between 20 and 40 µg/L, with a few exceptions (Fig. 2.3c). The average concentration was 33 µg/L, as it was in 2004 (Fig. 2.3g). This value is within the range recorded in the bay, and meets the MPCA standard, but not its water quality goal.
87 Crystal Bay Crystal Bay is located in the north-central part of Lake Minnetonka, in the cities of Orono, Minnetonka Beach, and Spring Park. Its water quality goals include maintaining a TP concentration of 25-30 µg/L, chlorophyll-a concentration of <14 µg/L, and a Secchi depth of >1.4 m. Crystal Bay has maintained a TSI around 50 since monitoring began, and this year falls in that range (TSI = 53; Fig. 2.4h).
Secchi depth decreased over the summer, probably in response to increased algal growth (Fig. 2.4a). The summer average was 2.1 m, which is a decline from the last two years, but still within the range recorded in the bay (Fig. 2.4e). It meets its water quality goal and the MPCA standard.
Chlorophyll-a concentration increased over the summer, reaching a maximum of 24 µg/L in August before declining (Fig. 2.4b). The average concentration was 14 µg/L, which is the highest concentration recorded in the bay (in 2002, it also averaged 14µg/L; Fig. 2.4f). It just missed its water quality goal and the MPCA standard.
Surface TP concentrations ranged from 8 µg/L to 45 µg/L and averaged 29 µg/L (Figs. 2.4c, g). TP at 24 m increased steadily over the summer, possibly indicating release of TP from the lake sediments (Fig. 2.4d). The surface mean increased from 2004, but is still within the range recorded in the bay. It is within its water quality goal and meets the MPCA standard.
East Upper Lake East Upper Lake is located in the central part of Lake Minnetonka and includes the cities of Orono, Shorewood, and Tonka Bay. No specific water quality goals have been established for this bay, and since monitoring has only occurred since 2004, there are no long-term data available. Compared to other lakes, it has excellent water quality, receiving an A-.
Secchi depth ranged from 2 m to 5.8 m, with the lowest values occurring in the summer, concurrent with an increase in chlorophyll-a (Fig. 2.5a). The average Secchi depth was 4.0 m, an increase from 2004, and well above the MPCA standard (Fig. 2.5e).
88 Chlorophyll-a concentrations were below the MPCA standard on all sample dates and reached a maximum of 11 µg/L. The average concentration was 3 µg/L, below the 2004 average and the MPCA standard (Fig. 2.5f).
TP surface concentration ranged from 18 µg/L to 35 µg/L and averaged 17 µg/L (Figs. 2.5c, g). This is a decrease from 2004, and well below the MPCA standard.
Forest Lake Forest Lake is north of Lake Minnetonka, in the city of Orono. It drains into the West Arm of Lake Minnetonka. No specific water quality goals have been established for Forest Lake. Water quality has been consistent, but does not meet the MPCA standards. Compared to other lakes, Forest Lake is more eutrophic than average, receiving a grade of C -.
Secchi depth was below 1 m for most of the year, and averaged 0.9 m (Fig. 2.6a). This is shallower than 2004, but within the range recorded in the lake. It does not meet the MPCA standards.
Chlorophyll-a ranged from 1 µg/L to 73 µg/L and averaged 45 µg/L (Figs. 2.6b). This is higher than 2004, and slightly higher than average, but within the range recorded on Forest Lake (Fig. 2.6f). It is more than three times the MPCA standard.
Surface TP concentration spiked in the fall, reaching a concentration of more than 1200 µg/L in October (Fig. 2.6c). The rest of the year, it was below 100 µg/L and averaged 72 µg/L (Fig 2.6g). This is the second-highest concentration recorded in the lake, and exceeds the MPCA standard.
Grays Bay Grays Bay is the easternmost bay of Lake Minnetonka, located in the cities of Wayzata and Woodland. Its outlet is Minnehaha Creek. The water quality goals for Grays Bay include maintaining TP concentrations of <20 µg/L, chlorophyll-a concentrations of <14 µg/L, and a Secchi depth of >1.4 m. Long-term data is not available on Grays Bay, but when samples have been taken, TSI has been below 50. This year, Grays Bay was in excellent condition compared to other lakes, receiving a grade of A.
89 Secchi depth was deeper than 2 m on all sampling dates, and averaged 3.1 m (Fig. 2.7a). This is reduced slightly from 2004, but still well above its water quality goals and the MPCA standard.
Chlorophyll-a ranged from 2.5 µg/L to 9 µg/L and averaged 8 µg/L (Fig. 2.7b). This is a large increase from 2004, but it still meets its water quality goal and the MPCA standard (Fig. 2.7f).
TP fluctuated over the summer, and averaged 24 µg/L (Fig. 2.7c). This meets the MPCA standard, but not its water quality goal.
Halsted Bay Halsted Bay is the westernmost bay of Lake Minnetonka, located in the cities of Mound and Minnetrista. It is fed by Six Mile Creek and has some of the worst water quality in Lake Minnetonka, although it is average compared to other lakes in the area (receiving a grade of C-). Its 509 goals include reducing TP concentrations to 50-60 µg/L, chlorophyll-a concentrations to <14 µg/L, and increasing Secchi depth to >1.4 m.
After reaching a maximum depth of 3.2 m, Secchi depth was below 1 m for much of the summer, and averaged 1.1 m (Fig. 2.8a). Low Secchi depths were due to algal blooms and occurred concurrently with high chlorophyll-a concentrations (Figs. 2.8a, b). This is consistent with previous years, and does not meet its water quality goals (Fig. 2.8e).
Chlorophyll-a concentrations spiked in mid-summer and increased through September, before declining in the fall (Fig. 2.8b). The average concentration was 46 µg/L, a typical value for the bay (Fig. 2.8f). It does not meet its water quality goals.
Surface TP concentration increased steadily over the sampling season, reaching a maximum of 130 µg/L(Figs. 2.8c) in October. The average concentration was 91 µg/L, which is lower than average, but still exceeds its water quality goal and the MPCA standard.
Harrison Bay Harrison Bay is located in the western part of Lake Minnetonka, south of Jennings Bay, in the city of Mound. Its 509 goals include maintaining a TP concentration of <50 µg/L, chlorophyll-a
90 concentration of <14 µg/L, and a Secchi depth of >1.4 m. Harrison Bay has some of the worst water quality in the lake, but is average for the region, receiving a grade of C-.
After peaking at 2.8 m, Secchi depth dropped steadily, and remained below 1 m from mid-summer until the end of the sampling season (Fig. 2.9a). The reduction in Secchi depth was due to an extended algal bloom – it corresponded to an increase in chlorophyll-a (Fig. 2.9b). Average Secchi depth was 1.1m, which is higher than average for the bay, but not in compliance with MPCA standards or its water quality goals.
Chlorophyll-a concentration peaked at 79 µg/L in late summer, and averaged 40 µg/L (Fig. 2.9b). This is an increase from 2004, but still within the typical range for the bay. It does not meet its water quality goal or the MPCA standard.
Surface TP concentration also increased steadily over the sampling season, peaking at 85 µg/L in October (Fig. 2.9c). The average concentration was 63 µg/L, an average value for the bay. It does not meet its water quality goal or the MPCA standard.
Jennings Bay Jennings Bay is in the northwestern part of Lake Minnetonka, in the city of Mound. Painter Creek and Dutch Creek drain to the bay, and both are consistently high in TP. Jennings Bay has the worst quality water in the lake, and is one of the worst in the region, receiving a grade of D. Its 509 plan goals are to reduce the TP concentration to 50-70 µg/L, the chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to >1.4 m.
Secchi depth reached a maximum of 2.9 m before an algal bloom reduced it to less than 1 m. This low-clarity condition remained until the end of sampling season (Fig 2.10a). The average Secchi depth was 1 m, which is the same as 2004 and one of the higher average values. However, the lake still does not meet the MPCA standard or its water quality goals.
Chlorophyll-a concentrations steadily increased over the summer, peaking at 99 µg/L in late August, before declining in the fall (Fig. 2.10b). The average concentration was 60 µg/L, a typical value for the bay, but more than 3 times the MPCA standard and its water quality goal.
91 Surface TP concentration increased steadily over the sampling season, peaking at 164 µg/L in October (Fig. 2.10c). The average concentration was 110 µg/L, a slight decrease from 2004 and a typical value for the bay (Fig. 2.10g). This well exceeds its water quality goal and the MPCA standard.
Lafayette Bay Lafayette Bay is in the central part of Lake Minnetonka, in the cities of Minnetonka Beach, Tonka Bay, and Orono. The 509 plan goals for the bay are to reduce TP to <20 µg/L, chlorophyll-a to <14 µg/L, and increase the Secchi depth to >1.4 m. Data on Lafayette Bay is only available for recent years, but in that time, it has always met the MPCA standards. TSI has been increasing in the bay since monitoring began, but there is not enough data to determine if this is a trend. Lafayette Bay has better than average water quality for the region, receiving a grade of B+.
Secchi depth was deeper than 2 m for the entire year, and averaged 3 m (Fig. 2.11a). This is within the typical range for the lake, and meets its water quality goal and the MPCA standard (Fig. 2.11e).
Chlorophyll-a concentrations gradually increased over the summer, but never exceeded the MPCA standard (Fig. 2.11b). The average concentration was 10 µg/L, twice the average value recorded in 2004. Chlorophyll-a concentrations have increased every year since monitoring began, but Lafayette Bay still meets its water quality goal and the MPCA standard.
Surface TP concentrations ranged from 18 µg/L to 44 µg/L, and averaged 30 µg/L (Fig. 2.11c). This is an increase from 2004, and the highest average value recorded, but it still meets the MPCA standard (Fig. 2.11g). It exceeds its water quality goal.
Lower Lake North Lower Lake North is the main part of the eastern half of the Lake Minnetonka, and is surrounded by the cities of Woodland, Deephaven, Wayzata, and Orono. There are no specific goals for the lake, and long-term data are not available. Since monitoring began, TSI has increased, but because of the lack of data, it is not possible to determine if this is part of the trend. Lower Lake North meets the MPCA standards for Secchi depth, chlorophyll-a, and TP and it received a B+ for water quality (Fig. 2.12).
92 Lower Lake South Lower Lake South is the main part of the southeastern part of Lake Minnetonka, and is surrounded by the cities of Greenwood, Deephaven, Tonka Bay, and Excelsior. Its 509 water quality goals are to reduce TP concentration to <20 µg/L, chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to 1.4 m. Compared to other area lakes, it has excellent water quality, receiving a grade of A-.
Secchi depth was above 2 m for the entire sampling season, and averaged 3.2 m (Fig. 2.13a). This is the same average value as 2004, and is part of a steady increase in Secchi depth that has occurred since the 1970s (Fig. 2.13e). It meets the MPCA standard and its water quality goal.
Chlorophyll-a concentrations were highest in late summer, peaking at 10 µg/L (Fig. 2.13b). The average concentration was 7 µg/L. Chlorophyll-a concentration has increased every year for the last 5 years, but remains within the historical range and meets the MPCA standard and its water quality goal.
Surface TP concentration was below the MPCA standard (40 µg/L) on all sampling dates except one (Fig. 2.13c). The average concentration was 25 µg/L, which is consistent with average values from the past decade (Fig. 2.13g). It meets the MPCA standard, but not its water quality goal.
Maxwell Bay Maxwell Bay is in the northern part of Lake Minnetonka, between Stubbs Bay and Crystal Bay, in the city of Orono. Its 509 plan goals are to reduce TP concentrations to <40 µg/L, chlorophyll-a concentrations to <14 µg/L, and increase Secchi depth to 1.4 m. Maxwell Bay’s water quality is average for the region, receiving a grade of C+.
Secchi depth was above 1.5 m on most sampling dates and averaged 1.6 m (Fig. 2.14a). This is down slightly from 2004, but within the typical range for the lake (Fig. 2.14e). It met the MPCA standard and its water quality goal.
Chlorophyll-a concentrations reached a maximum of 30 µg/L in late August after increasing all summer (Fig. 2.14b). The average concentration was 21 µg/L, which is the highest recorded in the
93 lake. There appears to be an increasing trend in chlorophyll-a concentrations, but it has not been accompanied by increasing TP or decreasing Secchi depth (Figs. 2.14 e, f, g). It does not meet the MPCA standard or its water quality goal.
TP concentrations spiked in October, but were below 50 µg/L for the rest of the year, and averaged 36 µg/L (Fig. 2.14c). This is slightly higher than average, but within the range recorded in the bay. It meets its water quality goal and the MPCA standard.
North Arm North Arm is one of the western bays, located in the cities of Spring park, Mound, and Orono. Its water quality goals are to reduce TP concentration to <30 µg/L, chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to >1.4 m. Despite being adjacent to two of the worst bays in the lake (Jennings and Harrison), North Arm has above average water quality for the region, receiving a grade of B-.
Secchi depth ranged from 1 m to 4.1 m and averaged 1.8 m (Fig. 2.15a). This is slightly lower than average, but within the range recorded in the lake (Fig. 2.15e). It meets its water quality goal and the MPCA standard.
Chlorophyll-a concentrations increased steadily over the summer, peaking at 41 µg/L in August, and averaging 17 µg/L (Fig. 2.15b). This is the highest average value recorded in the lake and does not meet the water quality goal or MPCA standard (Fig. 2.15f). Additional monitoring is necessary to determine if this is part of a trend.
Surface TP concentrations were below 40 µg/L on most sampling dates and averaged 35 µg/L (Fig. 2.15c). This is one of the higher average values recorded in the lake and additional monitoring is necessary to determine if this is part of an increasing trend. It does not meet its water quality goal, but it does meet MPCA standards.
94 Peavey Lake Peavey Lake is north of Lake Minnetonka in the city of Wayzata which drains into Browns Bay. It has no specific water quality goals. Compared to other lakes in the region, Peavey is average, receiving a C.
Secchi depth was at or below 1.5 m for almost all the sampling dates, and averaged 2.0 m (Fig. 2.16a). This is the same average value recorded for the last four years (Fig. 2.16e), and meets MPCA standards.
Chlorophyll-a concentrations varied, and peaked at 50 µg/L in early August (Fig. 2.16b). The average concentration was 28 µg/L, which is the highest value recorded since MCWD’s monitoring program began in 1997 (Fig 2.16f). Additional monitoring is necessary to determine if this increase is part of a trend. It does not meet the MPCA standard.
Surface TP concentrations ranged from 61 µg/L to 118 µg/L and averaged 77 µg/L (Fig. 2.16c). This is the same as in 2004, and within the typical range for the lake. It does not meet the MPCA standard.
Priests Bay Priests Bay is located in the western part of Lake Minnetonka. It is adjacent to Halsted Bay and Cooks Bay, in the cities of Mound and Victoria. Its water quality goals are to reduce the TP concentration to <30 µg/L, chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to 1.4 m. Despite its proximity to Halsted Bay (one of the worst quality bays in the lake), Priests Bay is in compliance with the MPCA and has better than average water quality (it received a B-).
No long-term data is available for Priests Bay, but the bay improved all parameters from 2004. It meets the MPCA standards for Secchi depth and TP, but not chlorophyll-a, which puts it in compliance. It meets its water quality goals for Secchi depth, but not chlorophyll-a and TP (Fig. 2.17).
95 Shavers Lake Shavers Lake is a shallow lake south of Wayzata Bay, in the city of Minnetonka. This is the first year sampling was done on Shavers Lake, and baseline data will need to be established before water quality goals are formed. Compared to other lakes, Shavers is above average, receiving a grade of B- (Fig. 2.18).
Shavers Lake meets the MPCA standard for chlorophyll-a, Secchi depth, and TP with summer averages of 5.8 µg/L, 1.2 m, and 55 µg/L, respectively. Because there are no other data available on the lake, it is impossible to tell if these are typical values.
Smithtown Bay Smithtown Bay is located in the southern part of the lake, in the city of Victoria. It receives input from Minnewashta Creek. It has no specific water quality goals and no long-term data is available. Compared to other lakes in the area, its water quality is excellent, receiving a grade of A-.
It is in MPCA compliance, meeting the standard for chlorophyll-a, Secchi depth, and TP with summer averages of 10 µg/L, 2.5 m, and 21 µg/L, respectively (Fig. 2.19). These values changed little from 2004, and because of the lack of data, it is impossible to determine if these values are typical for the bay.
Spring Park Bay Spring Park Bay is located in the west-central part of Lake Minnetonka, in the city of Spring Park. Its water quality goals are to reduce the TP concentration to <20 µg/L, chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to 1.4 m. Compared to other lakes in the region, its water quality is above average, receiving a grade of B+.
Secchi depth was above 1.5 m on all sampling dates, and averaged 2.6 m (Fig. 2.20a). This is slightly lower than 2004, but within the range recorded in the lake (Fig 2.20e). It meets the MPCA standard and its water quality goal.
96 Chlorophyll-a concentrations were below 14 µg/L on nearly all dates, and averaged 9 µg/L (Fig. 2.20b). This is the highest average value recorded in Spring Park Bay, but it meets the MPCA standard and its water quality goal.
Surface TP concentrations were below 40 µg/L on nearly all dates, and averaged 25 µg/L (Fig. 2.20c). This is a slight increase from 2004, but within the range recorded in the lake (Fig. 2.20g). It meets the MPCA standard, but not its water quality goal.
St. Albans Bay St. Albans Bay is adjacent to Excelsior Bay, in the city of Greenwood. Its water quality goals are to reduce the TP concentration to <20 µg/L, chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to 1.4 m. Compared to other lakes in the region, its water quality is excellent, receiving a grade of A.
Secchi depth was above 2 m on all sampling dates, and averaged 3.1 m (Fig. 2.21a). This is lower than in 2004, but within the range recorded on the lake (Fig. 2.21e). It meets the MPCA standard and its water quality goal.
Chlorophyll-a spiked in late July with a concentration of 12.3 µg/L, after which it declined (Fig. 2.21b). The average value of 7 µg/L is one of the highest values recorded on the lake, but still easily meets the MPCA standard and its water quality goal (Fig. 2.21f).
Surface TP concentrations were below 30 µg/L on most sampling dates, and averaged 22 µg/L (Fig. 2.21c). This is higher than in 2004, but within the range recorded on the lake (Fig. 2.21g). It meets the MPCA standard, but doesn’t meet its water quality goal. Stubbs Bay Stubbs Bay is the northern-most bay of Lake Minnetonka. It receives inputs from Classen Creek (also known as Stubbs Creek), and is adjacent to Maxwell Bay. Its water quality goals are to reduce the TP concentration to 50-55 µg/L, chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to 1.4 m. It is one of the worst quality bays in the lake, and average for the region (receiving a grade of C-).
97 Secchi depth reached a maximum of 4.2 m in the spring, but most of the year, it was below 1.5 m (Fig. 2.22a). It averaged 0.9 m, which is a typical value for the bay, but does not meet the MPCA standard or its water quality goal (Fig. 2.22e).
Chlorophyll-a concentrations ranged from 2.5 µg/L to 62.3 µg/L and averaged 44 µg/L (Fig. 2.22b). This is the highest average value recorded on the bay, and does not meet the MPCA standard or its water quality goal (Fig. 2.22f). It may be part of an increasing trend, but more monitoring is necessary to determine if that is the case.
Surface TP concentrations were between 60 and 80 µg/L for most of the year (Fig. 2.22c). The average concentration was 74 µg/L, the highest average value recorded on the bay (Fig. 2.22g). It does not meet the MPCA standard or its water quality goal.
Wayzata Bay Wayzata Bay is in the eastern part of the lake, between Grays Bay and Lower Lake North, in the cities of Wayzata and Woodland. Its water quality goals are to reduce the TP concentration to 20 µg/L, chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to 1.4 m.
Secchi depth was deeper than 2 m for all sampling dates, and averaged 3.1 m (Fig. 2.23a). This is average for the lake and meets the MPCA standard and its water quality goal (Fig. 2.23e).
Chlorophyll-a concentrations peaked at 28.3 µg/L in mid-summer, but were below 10 µg/L for most of the year (Fig. 2.23b). This is the highest average value recorded in a decade, but still within the historical range (Fig 2.23f). It meets the MPCA standard and its water quality goal.
Surface TP concentrations were under 40 µg/L for most sampling dates, and averaged 27 µg/L (Fig. 2.23c). This value is higher than most recent years, but within the typical range (Fig. 2.23g). It meets the MPCA standard, but not its water quality goal.
West Arm The West Arm of Lake Minnetonka is located between Jennings Bay and Harrison Bay, in the cities of Mound, Orono, and Spring Park. Its water quality is comparable to these bays, making it one of
98 the worst in the lake. Compared to other lakes in the region, it is average (it received a C). Its water quality goals are to reduce the TP concentration to 50 µg/L, chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to 1.4 m.
Secchi depth was below 1.5 m for most of the year, and averaged 1.1 m (Fig. 2.24a). This is a typical value for the lake and does not meet the MPCA standard or its water quality goal (Fig. 2.24e).
Chlorophyll-a concentrations steadily increased during the summer, peaking at 88 µg/L in late summer (Fig. 2.24b). The average concentration was 44 µg/L, one of the higher average values for the bay, but within the typical range (Fig. 2.24f). It does not meet the MPCA standard or its water quality goal.
Surface TP concentrations increased steadily all year, peaking at 119 µg/L in October (Fig. 2.24c). The average concentration was 68 µg/L, a typical value for the bay (Fig. 2.24g). It does not meet the MPCA standard or its water quality goal.
West Upper Lake West Upper Lake is in the city of Victoria and adjacent to Cooks Bay and Priests Bay. Its water quality goals are to reduce the TP concentration to 25 µg/L, chlorophyll-a concentration to <14 µg/L, and increase Secchi depth to 1.4 m. Its water quality is excellent compared to other lakes in the region, receiving an A-.
Secchi depth decreased in the summer, concurrent with an increase in chlorophyll-a, but it never dipped below 1.5 m (Fig. 2.25a). The average Secchi depth was 2.5 m, a typical value for the lake (Fig. 2.25e). It meets the MPCA standard and its water quality goal.
Chlorophyll-a steadily increased throughout the summer, but remained below 14 µg/L the entire year (Fig. 2.25b). The average concentration was 11 µg/L, which is consistent with previous years’ averages (Fig. 2.25f). It meets the MPCA standard and its water quality goal.
99 Surface TP concentrations were below 40 µg/L for most of the year, and averaged 27 µg/L (Fig. 2.25c). This value is very close to previous years, and meets the MPCA standard (Fig. 2.25g). It does not quite meet its water quality goal.
Classen Creek Classen Creek flows from Classen Lake into Stubbs Bay. MCWD monitors Classen Creek near the lake inlet.
Average flow in Classen Creek was 1.37 cfs in 2005, which is slightly higher than flow in 2004, but within the range recorded in the creek (Fig. 2.26c). Most of the flow was the result of extremely high flows following storm events – for most of the year, flow was close to zero (Fig. 2.26b).
Conductivity was higher than a typical stream for this ecoregion. Most of the year it was around 800 µmhos/cm (Fig 2.26e).
TSS concentrations averaged 87 mg/L, and the total load was 234,000 lbs (Fig. 2.26f). This is a decrease from 2004, but one of the higher loads and concentrations recorded in Classen Creek. The average concentration is well above the MPCA guideline of 10 mg/L.
TP concentration averaged 320 µg/L, and the load was 875 lbs (Fig. 2.26g). This is a slight decrease from 2004, but well above the MPCA guideline of 170 µg/L. TP concentrations and loads in the creek have been increasing since 1998, indicating a possible increase in TP inputs.
SRP concentration and load in Classen Creek decreased this year (Fig. 2.26h). The decrease in concentration is probably due to a shift in the form of phosphorus in the creek, since TP increased.
TN concentrations have been maintained since monitoring began (Fig. 2.26i). This year, TN concentration and load decreased slightly.
Forest Lake Creek Forest Lake Creek flows into Forest Lake, which drains into the North Arm of Lake Minnetonka. Flow in the creek was generally low, averaging 0.42 cfs (Fig. 2.27b). Concentrations of TP and
100 TSS were well above the MPCA guidelines (400 µg/L and 21 mg/L, respectively), but because of the low flows, Forest Lake Creek exported relatively little (334 lbs and 17,558 lbs, respectively).
Halsted Lake Inlets MCWD monitored an inlet to Halsted Bay at two sites (CHI01 and CHI02). The inlet is in a cattail marsh, and both sites flowed only in the spring (Figs. 2.28b, 2.29b). TP and TSS were high in the inlet, in part because the water became stagnant in the summer. Because of the low flows, however, most of these nutrients were not exported to the Bay.
Peavey Lake Creek Peavey Creek flows into Peavey Lake, which drains into Lower Lake North of Lake Minnetonka. It maintained a low flow most of the year, and averaged 0.56 cfs (Fig. 2.30b). TP concentration was 233 µg/L , well above the MPCA guidelines, but TSS was below (4.47 mg/L) (Fig. 2.30e,f). It exported 258 lbs of TP and 4,994 lbs of TSS, and so does not appear to be a significant contributor of nutrients to Peavey Lake.
Stubbs Bay Inlet Stubbs Bay Inlet flowed only in the spring and in response to rain events (Fig. 2.31b), and averaged 0.41 cfs. It was well above the MPCA guidelines for TP and TSS concentrations (671 µg/L and 52 mg/L, respectively; Figs 2.31e,f). Because of the low flows in the creek, it exported a relatively small amount to Stubbs Bay.
101 Figure 2.2 Carsons Bay (Lake Minnetonka) 2005 Grade: B+
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0 1.0 2.0 3.0 4.0 Secchi Depth (m) 5.0 a. 10 8 6
4 2 Chlorophyll a (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP
40 )
µg/L 30
20
Phosphorus ( 10
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date c.
102 Fig. 2.2 Carsons Bay (Lake Minnetonka) Summer Mean Values
4.0 2005 Mean = 2.9 m
3.0 TSIS = 45
2.0
Secchi Depth (m) 1.0
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 d.
7 2005 Mean = 6 ppb 6 TSIC = 48 5
4
3
2 Chlorophyll a (ppb) 1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
30 2005 Mean = 24 ppb 25 TSIP = 50
20
15
10
Total Phosphorus (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 TSI = 48 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year g.
103 Figure 2.3 Cooks Bay (Lake Minnetonka) 2005 Grade: B-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
1.0
2.0
3.0
4.0 Secchi Depth (m) 5.0
6.0 a.
25
20
15
10
Chlorophyll a (ppb) 5
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b. 9 m Surface TP Surface SRP Deep TP Deep SRP 240
) 100 210
µg/L 80 180 150 60 120 40 90 60
Phosphorus ( 20 30 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
104 Fig. 2.3 Cooks Bay (Lake Minnetonka) Summer Mean Values
3.0 2005 Mean = 2.1 m 2.5 TSIS = 49 2.0
1.5
1.0
Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
18 16 2005 Mean = 15 ppb TSIC = 57 14 12 10 8 6 4
Chlorophyll a (ppb) 2 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
50 45 2005 Mean = 33 ppb 40 TSIP = 55 35 30 25 20 15 10 5 Total Phosphorus (ppb) 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 54 70
60
50
40
Trophic State Index 30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
105 Fig. 2.4 Crystal Bay (Lake Minnetonka) 2005 Grade: B
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
1.0
2.0
3.0
4.0
Secchi Depth (m) 5.0
6.0 a.
25
20
15
10
Chlorophyll a (ppb) 5
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
24 m Surface TP Surface SRP Deep TP Deep SRP 60 300
)
µg/L 40 200
20 100 Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
106 Fig. 2.4 Crystal Bay (Lake Minnetonka) Summer Mean Values
3.0 2005 Mean = 2.1 m 2.5 TSIS = 49
2.0
1.5
1.0 Secchi Depth (m)
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
16
14 2005 Mean = 14 ppb TSIC = 57 12
10
8
6
Chlorophyll a (ppb) 4
2
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
40 2005 Mean = 29 ppb 35 TSIP = 53 30
25
20
15
10 Total Phosphorus (ppb)
5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 53 70
60
50
40
Trophic State Index 30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
107 Figure 2.5 East Upper (Lake Minnetonka) 2005 Grade: A-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0 1.0 2.0 3.0 4.0 5.0 Secchi Depth (m) 6.0 a. 12 10 8 6 4 2 Chlorophyll a (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 12 m 40 250
) 200 30 µg/L 150 20 100 10 50 Phosphorus (
0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
108 Fig. 2.5 East Upper (Lake Minnetonka) Summer Mean Values
4.5
4.0 2005 Mean = 4.0 m
3.5 TSIS = 42
3.0
2.5
2.0
1.5
Secchi Depth (m) 1.0
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
4.5 2005 Mean = 3 ppb 4 TSIC = 42 3.5
3
2.5
2
1.5
Chlorophyll a (ppb) 1
0.5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
30 2005 Mean = 17 ppb 25 TSIP = 45 20
15
10
5 Total Phosphorus (ppb)
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 42 70
60
50
40 Trophic State Index 30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
109 Figure 2.6 Forest Lake 2005 Grade: C-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
1.0
2.0
3.0
Secchi Depth (m) 4.0
5.0 a.
80
70
60
50
40
30
20 Chlorophyll a (ppb) 10
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 12 m 1250 2500
) 1000 2000 µg/L 750 1500
500 1000
250 500 Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
110 Fig. 2.6 Forest Lake Summer Mean Values
2.0 1.8 2005 Mean = 0.9 m
1.6 TSIS = 62 1.4 1.2 1.0
0.8 0.6 Secchi Depth (m) 0.4 0.2
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
70 2005 Mean = 45 ppb 60 TSIC = 68 50
40
30
20 Chlorophyll a (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
100 2005 Mean = 72 ppb 90 TSIP = 66 80 70 60 50 40 30 20 Total Phosphorus (ppb) 10 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 65 70
60
50
40 Trophic State Index 30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
111 Figure 2.7 Grays Bay (Lake Minnetonka) 2005 Grade: A
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0 1.0 2.0 3.0 4.0 Secchi Depth (m) 5.0 a.
10.0 8.0 6.0 4.0 2.0 Chlorophyll a (ppb) 0.0 4/1 4/29 5/27 6/24 7/22 8/19 9/16 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 8 m
40 ) 100 80 µg/L 60 20 40 20 Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
112 Fig. 2.7 Grays Bay (Lake Minnetonka) Summer Mean Values
3.5 2005 Mean = 3.1 m 3.0 TSIS = 44 2.5
2.0
1.5
1.0 Secchi Depth (m)
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
8
7 2005 Mean = 8 ppb TSIC = 50 6
5
4
3
2 Chlorophyll a (ppb) 1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
30
25 2005 Mean = 24 ppb TSIP = 50 20
15
10
5 Total Phosphorus (ppb)
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 48 70
60
50
40 Trophic State Index 30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
113 Figure 2.8 Halsted Bay (Lake Minnetonka) 2005 Grade: C-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0 0.5 1.0 1.5 2.0 2.5 Secchi Depth (m) 3.0 3.5 a.
80 70 60 50 40 30 20 Chlorophyll a (ppb) 10 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 9 m
) 150 1500
µg/L 1250 100 1000 750 50 500
Phosphorus ( 250 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
114 Fig. 2.8 Halsted Bay (Lake Minnetonka) Summer Mean Values
3.5 2005 Mean = 1.1 m 3.0 TSIS = 59 2.5
2.0
1.5
1.0 Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
90 80 2005 Mean = 46 ppb 70 TSIC = 68 60 50 40 30
Chlorophyll a (ppb) 20 10 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
160 2005 Mean = 91 140 TSIP = 69 120
100
80
60
40
Total Phosphorus (ppb) 20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 65 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
115 Figure 2.9 Harrison Bay (Lake Minnetonka) 2005 Grade: C-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
0.5 1.0
1.5 2.0 2.5
Secchi Depth (m) 3.0
3.5 a.
100
80
60
40 Chlorophyll a (ppb) 20
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 6 m 100 600
) 80 500
µg/L 400 60 300 40 200 20 Phosphorus ( 100
0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
116 Fig. 2.9 Harrison Bay (Lake Minnetonka) Summer Mean Values
1.2 2005 Mean = 1.1 m 1.0 TSIS = 59 0.8
0.6
0.4 Secchi Depth (m) 0.2
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
70 2005 Mean = 40 ppb 60 TSIC = 67 50
40
30
20 Chlorophyll a (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 Mean = 63 ppb 70 TSIP = 64 60
50
40
30
20
Total Phosphorus (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 63 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
117 Figure 2.10 Jennings Bay (Lake Minnetonka) 2005 Grade: D
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
0.5
1.0
1.5
2.0
Secchi Depth (m) 2.5
3.0 a.
120
100
80
60
40
Chlorophyll a (ppb) 20
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 6 m 200 500
) 150 400 µg/L 300 100 200 50 100
Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
118 Fig. 2.10 Jennings Bay (Lake Minnetonka) Summer Mean Values
1.4
1.2
1
0.8
0.6
0.4 Secchi Depth (m)
0.2
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
180 160 140 120 100 80 60 40 Chlorophyll a (ppb) 20 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
400
350
300
250
200
150
100
Total Phosphorus (ppb) 50
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80
70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
119 Figure 2.11 Lafayette Bay (Lake Minnetonka) 2005 Grade: B+
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0 1.0 2.0 3.0 4.0 5.0 Secchi Depth (m) 6.0 a. 14 12 10 8 6 4 2 Chlorophyll a (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b. 17 m Surface TP Surface SRP Deep TP Deep SRP 50 600
) 40 500
µg/L 400 30 300 20 200
10 100 Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
120 Fig. 2.11 Lafayette Bay (Lake Minnetonka) Summer Mean Values
3.5 2005 Mean = 3.0 m 3.0 TSIS = 45 2.5
2.0
1.5
1.0 Secchi Depth (m)
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
12 2005 Mean = 10 ppb 10 TSIC = 53 8
6
4
Chlorophyll a (ppb) 2
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
35 2005 Mean = 30 ppb 30 TSIP = 53 25
20
15
10
Total Phosphorus (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 50 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
121 Figure 2.12 Lower Lake North (Lake Minnetonka) 2005 Grade: A-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0 1.0 2.0 3.0 4.0 5.0
Secchi Depth (m) 6.0 7.0 a. 10 8 6 4 2
Chlorophyll a (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 24 m 50 500
) 40 400 µg/L 30 300
20 200
10 100 Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
122 Fig. 2.12 Lower Lake North (Lake Minnetonka) Summer Mean Values
4.0 2005 Mean = 3.0 m 3.5 TSIS = 42 3.0
2.5
2.0
1.5
Secchi Depth (m) 1.0
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
8 2005 Mean = 7 ppb 7 TSIC = 49 6
5
4
3
2 Chlorophyll a (ppb) 1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
30 2005 Mean = 26 ppb 25 TSIP = 51 20
15
10
5 Total Phosphorus (ppb)
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 47 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
123 Figure 2.13 Lower Lake South (Lake Minnetonka) 2005 Grade: A-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
1.0
2.0
3.0
4.0
Secchi Depth (m) 5.0
6.0 a.
12
10
8
6
4
Chlorophyll a (ppb) 2
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
21 m Surface TP Surface SRP Deep TP Deep SRP 50 500
)
40 400 µg/L 30 300
20 200 10 100 Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
124 Fig. 2.13 Lower Lake South (Lake Minnetonka) Summer Mean Values
4.5 4 2005 Mean = 3.2 m TSIS = 43 3.5 3 2.5 2 1.5
Secchi Depth (m) 1 0.5 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
30 2005 Mean = 7 ppb 25 TSIC = 50 20
15
10
Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
120 2005 Mean = 25 ppb 100 TSIP = 51 80
60
40
20 Total Phosphorus (ppb)
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 48 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
125 Figure 2.14 Maxwell Bay (Lake Minnetonka) 2005 Grade: C+
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
0.5
1.0
1.5
2.0
2.5
3.0 Secchi Depth (m)
3.5
4.0 a.
40
30
20
10 Chlorophyll a (ppb)
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b. 12 m Surface TP Surface SRP Deep TP Deep SRP 100 800
) 600 µg/L
50 400
200 Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
126 Fig. 2.14 Maxwell Bay (Lake Minnetonka) Summer Mean Values
2.5 2005 Mean = 1.6 m 2 TSIS = 53
1.5
1 Secchi Depth (m) 0.5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
25 2005 Mean = 21 ppb 20 TSIC = 60
15
10
Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
45 2005 Mean = 36 ppb 40 TSIP = 56 35 30 25 20 15 10 Total Phosphorus (ppb) 5 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 56 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
127 Figure 2.15 North Arm (Lake Minnetonka) 2005 Grade: B-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
1.0
2.0
3.0
Secchi Depth (m) 4.0
5.0 a.
30
20
10 Chlorophyll a (ppb)
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 14 m 800
60 )
µg/L 600 40 400 20 200 Phosphorus (
0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
128 Fig. 2.15 North Arm (Lake Minnetonka) Summer Mean Values
2.5 2005 Mean = 1.8 m 2.0 TSIS = 52
1.5
1.0 Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
18 16 2005 Mean = 17 ppb TSIC = 58 14 12 10 8 6 4 Chlorophyll a (ppb) 2 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
40 2005 Mean = 35 ppb 35 TSIP = 55 30
25
20
15
10
Total Phosphorus (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 55 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
129 Figure 2.16 Peavey Lake 2005 Grade: C
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
0.5
1.0
1.5
2.0
2.5
Secchi Depth (m) 3.0
3.5 a.
60
50
40
30
20
10 Chlorophyll a (ppb)
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 15 m
) 140 10000 120 µg/L 8000 100 80 6000
60 4000 40
Phosphorus ( 2000 20 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
130 Fig. 2.16 Peavey Lake Summer Mean Values
3.0 2005 Mean = 2.0 m 2.5 TSIS = 50
2.0
1.5
1.0 Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
80
70 2005 Mean = 28 ppb TSIC = 63 60
50
40
30
20 Chlorophyll a (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
500 2005 Mean = 77 ppb 450 400 TSIP = 67 350 300 250 200 150 100 Total Phosphorus (ppb) 50 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 60 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
131 Figure 2.17 Priests Bay (Lake Minnetonka) 2005 Grade: B-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
1.0
2.0
3.0
4.0 Secchi Depth (m) 5.0 a.
30 25 20 15 10 5 Chlorophyll a (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 9 m
100 400 ) 80 µg/L 60 200 40 20
Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
132 Fig. 2.17 Priests Bay (Lake Minnetonka) Summer Mean Values
2.0 2005 Mean = 1.8 m 1.8 TSIS = 51 1.6 1.4 1.2 1.0 0.8 0.6 Secchi Depth (m) 0.4 0.2 0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
30 2005 Mean = 19 ppb 25 TSIC = 60 20
15
10 Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
60 2005 Mean = 37 ppb 50 TSIP = 56 40
30
20
10 Total Phosphorus (ppb)
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 56 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
133 Figure 2.18 Shavers Lake 2005 Grade: B-
2005 Date
4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
0.5
1.0 Secchi Depth (m) 1.5 a.
20 18 16 14 12 10 8 6 4 Chlorophyll a (ppb) 2 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP
) 80
µg/L 60
40
20 Phosphorus ( 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date c.
134 Figure 2.19 Smithtown Bay (Lake Minnetonka) 2005 Grade: A-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0 1 2 3 4 5 Secchi Depth (m) 6 a.
14 12 10 8 6 4 Chlorophyll a (ppb) 2 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 21 m 1000 40 ) 800 µg/L 600 20 400
200 Phosphorus (
0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
135 Fig. 2.19 Smithtown Bay (Lake Minnetonka) Summer Mean Values
2.6 2005 Mean = 2.5 m 2.5 TSIS = 47 2.5
2.4
2.4 Secchi Depth (m) 2.3
2.3 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
12 2005 Mean = 10 ppb 10 TSIC = 54 8
6
4
Chlorophyll a (ppb) 2
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
23.5 2005 Mean = 21 ppb 23 TSIP = 48 22.5
22
21.5
21 Total Phosphorus (ppb)
20.5 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 50 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
136 Figure 2.20 Spring Park Bay (Lake Minnetonka) 2005 Grade: A-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0
1
2
3
4 Secchi Depth (m) 5
6 a.
20
15
10 Chlorophyll a (ppb) 5
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
9 m Surface TP Surface SRP Deep TP Deep SRP 60 200
) 180 160 µg/L 40 140 120 100 20 80 60 40 Phosphorus ( 20 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
137 Fig. 2.20 Spring Park Bay (Lake Minnetonka) Summer Mean Values
4 2005 Mean = 2.6 m TSIS = 46 3
2
Secchi Depth (m) 1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
10 9 2005 Mean = 9 ppb 8 TSIC = 52 7 6 5 4 3
Chlorophyll a (ppb) 2 1 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
35 2005 Mean = 25 ppb 30 TSIP = 50 25
20
15
10
Total Phosphorus (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 50 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
138 Figure 2.21 St. Albans Bay (Lake Minnetonka) 2005 Grade: A
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0 1 2 3 4 5
6 Secchi Depth (m) 7 8 a.
14
12
10
8
6
4 Chlorophyll a (ppb) 2
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
10 m Surface TP Surface SRP Deep TP Deep SRP 50 250
) 40 200 µg/L 30 150
20 100
10 50 Phosphorus (
0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
139 Fig. 2.21 St. Albans Bay (Lake Minnetonka) Summer Mean Values
4 2005 Mean = 3.1 m TSIS = 44 3
2
Secchi Depth (m) 1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
8 2005 Mean = 7 ppb 7 TSIC = 50 6
5
4
3
2 Chlorophyll a (ppb) 1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
30 2005 Mean = 22 ppb 25 TSIP = 49 20
15
10
Total Phosphorus (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 47 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
140 Figure 2.22 Stubbs Bay (Lake Minnetonka) 2005 Grade: C-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0
1
2
3
Secchi Depth (m) 4
5 a.
80
70
60
50
40
30
20 Chlorophyll a (ppb) 10
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 10 m
200 1500 ) 180 160 µg/L 140 1000 120 100 80 60 500
Phosphorus ( 40 20 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
141 Fig. 2.22 Stubbs Bay (Lake Minnetonka) Summer Mean Values
1.4 2005 Mean = 0.9 m 1.2 TSIS = 61 1
0.8
0.6
0.4 Secchi Depth (m)
0.2
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
50 2005 Mean = 44 45 40 TSIC = 68 35 30 25 20 15
Chlorophyll a (ppb) 10 5 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 Mean = 74 ppb 70 TSIP = 66 60
50
40
30
20
Total Phosphorus (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 65 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
142 Figure 2.23 Wayzata Bay (Lake Minnetonka) 2005 Grade: A-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0
1
2
3
4
Secchi Depth (m) 5
6 a.
30
25
20
15
10 Chlorophyll a (ppb) 5
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
13 m Surface TP Surface SRP Deep TP Deep SRP 400
60 ) 50 300 µg/L 40 30 200 20 100
Phosphorus ( 10 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
143 Fig. 2.23 Wayzata Bay (Lake Minnetonka) Summer Mean Values
5 2005 Mean = 3.1 m TSIS = 44 4
3
2 Secchi Depth (m) 1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
25 2005 Mean = 9 ppb TSIC = 52 20
15
10
Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
90 2005 Mean = 27 ppb 80 TSIP = 51 70 60 50 40 30 20 Total Phosphorus (ppb) 10 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 49 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
144 Figure 2.24 West Arm (Lake Minnetonka) 2005 Grade: C
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0 0.5
1.0 1.5
2.0 2.5
Secchi Depth (m) 3.0
3.5 a.
100 90 80 70 60 50 40 30
Chlorophyll a (ppb) 20 10 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP
600
) 140 120 500 µg/L 100 400 80 300 60 200 40
Phosphorus ( 20 100 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
145 Fig. 2.24 West Arm (Lake Minnetonka) Summer Mean Values
1.4 2005 Mean = 1.1 m 1.2 TSIS = 58 1.0
0.8
0.6
0.4 Secchi Depth (m)
0.2
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
80 2005 Mean = 44 ppb 70 TSIC = 68 60
50
40
30
20 Chlorophyll a (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
120 2005 Mean = 68 ppb 100 TSIP = 65 80
60
40
20 Total Phosphorus (ppb)
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 64 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
146 Figure 2.25 West Upper (Lake Minnetonka) 2005 Grade: A-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0 1.0
2.0
3.0 4.0 5.0
Secchi Depth (m) 6.0 7.0 a.
16
14
12
10
8
6
4 Chlorophyll a (ppb) 2
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
22 m Surface TP Surface SRP Deep TP Deep SRP 60 1200
) 1000
µg/L 40 800 600
20 400 200 Phosphorus ( 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date 2005 Date c. d.
147 Fig. 2.25 West Upper (Lake Minnetonka) Summer Mean Values
3.0 2005 Mean = 2.5 m 2.5 TSIS = 47 2.0
1.5
1.0 Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
35 2005 Mean = 11 ppb 30 TSIC = 54 25
20
15
10 Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
160 2005 Mean = 27 ppb 140 TSIP = 52 120
100
80
60
40
Total Phosphorus (ppb) 20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 51 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
148 Figure 2.26 Classen Creek, CCL01 – Classen Creek, City of Orono Drainage Area: 1.55 sq. mi.
25 25 10
20 20 8
15 15 6
10 10 4 Flow (cfs)
5 5 Temperature (C) 2 Dissolved Oxygen (mg/L) 0 0 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
2.5 2 No E. coli 1.5 sampling 1 0.5 Average flow (cfs) 0 1997 1998 1999 20002001 2002 2003 2004 2005 Year
c. Average flow by year
12 1000 10 800 8 600 6 pH 400 4 2 200
0 Conductivity (umho/cm) 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date d. pH by date e. Conductivity by date
149 Fig. 2.26 Classen Creek (CCL01) 2005 Flow-Weighted Concentrations and Loads 140 350 120 300 100 250 80 200 60 150 40 100 Mean TSS (ppm)
20 50 TSS Load (1000*lbs) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year f.
500 1200 400 1000 800 300 600 200 400 TP Load (lbs) Mean TP (ppb) 100 200 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 g. 250 600
200 500 400 150 300 100 200
50 SRP Load (lbs) Mean SRP (ppb) 100 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h. 2.5 8000 2 6000 1.5 4000 1
2000 TN Load (lbs)
Mean TN (ppm) 0.5 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i.
150 3. Christmas Lake Subwatershed The Christmas Lake sub-watershed is located on the southern boundary of the MCWD, in the cities of Chanhassen and Excelsior. It drains into St. Albans Bay of Lake Minnetonka via Christmas Creek. The 509 Plan water quality goals for the Christmas Creek sub-watershed include managing storm water volumes to prevent erosion and to limit inputs to Christmas Lake. MCWD monitors two sites in the sub-watershed: Christmas Lake and Christmas Creek (CCH01, Fig. 3.1). The subwatershed drains 3.33 square miles, which produced 2 inches of runoff (123 acre-feet) in 2005.
Figure 3.1 Christmas Creek subwatershed Christmas Lake Christmas Lake is a 257 acre lake located in the city of Excelsior. It is a mesotrophic lake that is well within the MPCA standards and has maintained this water quality for several years. It is one of the best quality lakes in the area, receiving a grade of A.
TP concentrations at the surface ranged from 35 µg/L to 30 µg/L and averaged 38 µg/L (Fig. 3.2c). This is slightly higher than past years, but still well below the MPCA-recommended level of 40 µg/L (Fig. 3.2g).
151 The highest chlorophyll-a level was 7 µg/L , but for most of the summer, concentrations were between 0 and 3 (Fig. 3.2b). Average concentration was 0.5 µg/L , well below the MPCA standard of 33 µg/L . This is consistent with recent years: with a few exceptions, average chlorophyll-a concentrations have been between 0 and 5 µg/L since the 1970s (Fig. 3.2f).
Christmas Lake is one of the clearest lakes in the area. This year, Secchi depth ranged from 5 to 9.5 m and averaged 6.3 m (Fig. 3.2a). Christmas Lake has maintained a deep Secchi depth since the 1970s (Fig 3.2e).
Christmas Creek Christmas Creek connects Christmas Lake to St. Albans Bay. In 2005, mean flow in the creek was 0.16 cfs, which is the lowest discharge since stream monitoring began in 1997 (Fig 3.3c). Flow spiked following storm events, but the creek did not flow for extended periods of time, and nearly dried up in the spring and summer (Fig 3.3b).
Conductivity was highest in the spring, with a maximum of 3204 µmhos/cm, probably due to salt washing off roads during the spring melt (Fig. 3.3e) For most of the year, it remained around 400 µmhos/cm, which is slightly higher than average for this ecoregion.
The creek had a flow-weighted average concentration of 40 µg/L , a typical value for the creek and well within the MPCA guidelines. The total load was 12 lbs, the smallest load recorded in the creek (Fig. 3.3g). This is due to the low flow this year – even though the TP concentration was average, the total exported from the subwatershed was lower than normal.
Because of the low flow, TSS, SRP, and TN loads were also the lowest recorded in the creek (Figs. 3.3f, h, i). TSS and TN concentrations were average, and the SRP concentration was the lowest recorded. The low SRP concentration is probably due to a change in phosphorus form, since TP concentration was average.
152 Figure 3.2 Christmas Lake 2005 Grade: A
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 0.0 2.0 4.0 6.0 8.0
Secchi Depth (m) 10.0 a.
10
8
6
4
2 Chlorophyll a (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date b.
25 m Surface TP Surface SRP Deep TP Deep SRP
40 250 200 150 20 100 50 Phosphorus (ppb) 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date 2005 Date c. d.
153 Fig. 3.2 Christmas Lake Summer Mean Values
8 2005 mean = 6.3 m 7 TSIS = 33 6
5
4
3 Secchi Depth (m) 2
1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
50 45 40 2005 mean = 0.5 ppb 35 TSIC = 23 30 25 20 15 Chlorophyll a (ppb) 10 5 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
90
80 2005 mean = 18 ppb 70 TSIP = 46 60 50
40 30
Total Phosphorus (ppb) 20
10 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 34 70
60
50 Trophic State Index 40
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
154 Figure 3.3 Christmas Creek, CCH01 – Christmas Lake Outlet, City of Excelsior Drainage Area: 1.17 sq. mi.
30 20 2.0 25 15 1.5 20
15 10 1.0
10 Flow (cfs) 5 0.5 5 Temperature (C) Dissolved Oxygen (mg/L)
0 0 0.0 3/29 4/28 5/28 6/27 7/27 8/26 9/25 10/25 3/29 4/28 5/28 6/27 7/27 8/26 9/25 10/25 2005 Date 2005 Date a. DO and temperature by date b. Flow by date 1
0.8
0.6 No E. coli sampling 0.4
0.2 Average Flow (cfs)
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
c. Average flow by year 12 1400 10 1200 8 1000 800 6 pH 600 4 400 2 200 Conductivity (umho/cm) 0 0 3/29 4/28 5/28 6/27 7/27 8/26 9/25 10/25 3/29 4/28 5/28 6/27 7/27 8/26 9/25 10/25 2005 Date 2005 Date d. pH by date e. Conductivity by date
155 Fig. 3.3 Christmas Creek 2005 Flow-Weighted Concentrations and Loads 30 35 25 30 20 25 20 15 15 10 (1000*lbs) 10 TSS Load 5 Mean TSS (ppm) 5 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year f.
100 100
80 80 60 60
40 40 TP Load (lbs)
Mean TP (ppb) 20 c 20 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g. 15 20
15 10 10 (lbs) 5 5 SRP Load Mean SRP (ppb) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h.
1.2 1500 1 0.8 1000 0.6 0.4 500 Mean TN (ppm) 0.2 TN Load (lbs) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i.
156 4. Lake Virginia Subwatershed The Lake Virginia sub-watershed is located in the southern portion of MCWD. It includes Lakes Virginia, Minnewashta, St. Joe, and Tamarack, in the cities of Shorewood, Chanhassen, and Victoria. The 509 water quality goals for this sub-watershed include reducing TP concentrations to 20 µg/L in Lake Minnewashta and 40 µg/L in Lake Virginia, and maintaining TP levels in Tamarack Lake and St. Joe’s Lake. For all lakes, the water quality goal includes maintaining a Secchi depth of at least 1.4 m, chlorophyll-a concentrations of less than 14 µg/L , and a TSI of less than 57. In addition, the district seeks to reduce pollutant loading to Smithtown Bay. MCWD monitors the four lakes in the subwatershed and Minnewashta Creek (CMW01), which flows from Lake Minnewashta to Lake Virginia and into Smithtown Bay (Fig. 4.1).
Figure 4.1 Lake Virginia subwatershed
Tamarack Lake Tamarack Lake is a 24 acre lake located in the city of Victoria. It has been monitored since 2002, so little is known about long-term trends in the lake. Compared to other lakes in the area, Tamarack Lake was average in 2005, receiving a grade of C. Although it does not meet the MPCA standard
157 for chlorophyll-a, it meets the standard for TP and Secchi depth, which puts the lake in compliance (Fig. 4.2.
Lake St. Joe Lake St. Joe is an 18 acre lake located in the city of Chanhassen. Its monitoring program began in 2005, so there are no data on long-term trends. Compared to other lakes in the area, it is one of the best, receiving a grade of A. It meets the MPCA standards for TP, chlorophyll-a, and Secchi depth (Fig. 4.3).
Lake Minnewashta Lake Minnewashta is a 738 acre lake located in the city of Chanhassen. TP and chlorophyll-a concentrations and Secchi depth have varied in the lake, but almost always met the MPCA standards. Compared to other lakes in the area, Lake Minnewashta has excellent water quality, receiving a grade of A-.
Secchi depth ranged from 3 m to 5.7 m and averaged 2.5 m (Fig. 4.4a). This is a typical value for the lake and meets both its water quality goal and the MPCA standard (Fig. 4.4e). TSI in the lake was 46, which meets its water quality goal of 57.
Chlorophyll-a concentrations ranged from 0 µg/L to 11 µg/L and averaged 3 µg/L (Fig. 4.4b). This is one of the lower values in recent years, and meets both the MPCA standards and its water quality goal (Fig. 4.4f).
This year, surface TP concentrations ranged from 15 µg/L to 40 µg/L and averaged 26 µg/L (Fig. 4.4c) . These are typical values for the lake (Fig. 4.4g), and meet the MPCA standard, but not its water quality goal (20 µg/L).
Lake Virginia Lake Virginia is a 110 acre lake located in the cities of Victoria and Shorewood. This year’s water quality values were average for the lake and for other lakes in the region (it received a C+). It doesn’t quite meet its water quality goals or the MPCA’s standards for TP, chlorophyll-a, Secchi depth, or TSI.
158 Secchi depth was below 2 m for all sampling dates, and averaged 1 m (Fig. 4.5a). This is an average value for the lake, but doesn’t meet the MPCA standards or its water quality goal (Fig. 4.5d)
Chlorophyll-a concentrations ranged from 3 µg/L to 44 µg/L , and averaged 22 µg/L (Fig. 4.5b). This is a typical value for the lake, but exceeds the MPCA’s standard and the lake’s water quality goal (Fig. 4.5e).
Surface TP concentrations ranged from 30 µg/L to 95 µg/L and averaged 44 µg/L (Fig. 4.5c). This is a typical value for the lake and just above the MPCA’s standard and the lake’s water quality goal (Fig. 4.5f).
Minnewashta Creek Minnewashta Creek flows from Lake Minnewashta to Lake Virginia, and drains into Smithtown Bay of Lake Minnetonka. The creek is monitored at the Lake Virginia outlet, where average flow was 0.86 cfs (Fig. 4.6b). This is the first year Minnewashta Creek has been monitored, so it is unknown if this year’s values are typical for the creek (TP: 41 µg/L , TSS: 2.9 µg/L , SRP: 0.0001µg/L , TN: 0.845 mg/L). It does meet the MPCA standards for nutrient and sediment concentrations and has lower concentrations than most area streams.
159 Figure 4.2 Tamarack Lake 2005 Grade: C
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
1.0
2.0
Secchi Depth (m) 3.0
4.0 a.
80
60
40
20 Chlorophyll a (ppb)
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP
150
100
50 Phosphorus (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date c.
160 Fig. 4.2 Tamarack Lake Summer Mean Values
2.0 2005 Mean = 1.9 m TSIS = 51 1.5
1.0
Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 d.
40 2005 Mean = 24 ppb 35 TSIC = 62 30
25
20
15
10 Chlorophyll a (ppb)
5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
80 2005 Mean = 34 ppb 70 TSIP = 55 60
50
40
30
Total Phosphorus (ppb) 20
10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 TSI = 56 70
60
50
Trophic State Index 40
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year g.
161 Figure 4.3 Lake St. Joe 2005 Grade: A
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0
1
2
3 Secchi Depth (m) 4
5 a.
18 16 14 12 10 8 6 4 Chlorophyll a (ppb) 2 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP
40
20 Phosphorus (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date c.
162 Figure 4.4 Lake Minnewashta 2005 Grade: A-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Secchi Depth (m) 7.0 a.
12
10
8
6
4
2 Chlorophyll a (ppb)
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date b.
18 m Surface TP Surface SRP Deep TP Deep SRP 60 600
500
40 400
300
20 200
Phosphorus (ppb) 100
0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date 2005 Date c. d.
163 Fig. 4.4 Lake Minnewashta Summer Mean Values
5.0
2005 Mean = 2.5 m 4.0 TSIS = 47
3.0
2.0 Secchi Depth (m) 1.0
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
14 2005 Mean = 3 ppb 12 TSIC = 40 10
8
6
4 Chlorophyll a (ppb) 2
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
60 2005 Mean = 26 ppb 50 TSIP = 51 40
30
20
Total Phosphorus (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 46 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
164 Figure 4.5 Virginia Lake 2005 Grade: C+
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0
1 Secchi Depth (m)
2 a.
50 40 30 20 10
Chlorophyll a (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date
b.
Surface TP
100 80 60 40
Phosphorus (ppb) 20 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date c.
165 Fig. 4.5 Virginia Lake Summer Mean Values
3.0 2005 Mean = 1.0 m TSIS = 61
2.0
1.0 Secchi Depth (m)
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 d.
45 2005 Mean = 22 ppb 40 TSIC = 61 35
30
25
20
15
Chlorophyll a (ppb) 10
5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
100 2005 Mean = 44 ppb 90 TSIP = 59 80 70 60 50 40 30 20 Total Phosphorus (ppb) 10 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 TSI = 60 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year g.
166 Figure 4.6 Minnewashta Creek, CMW01 – Lake Virginia Outlet, City of Victoria Drainage Area: 6.24 sq. mi.
25 35
30 20 25
15 20
10 15
10 Temperature (C) 5
Dissolved Oxygen (mg/L) 5
0 0 3/22 4/21 5/21 6/20 7/20 8/19 9/18 10/18 2005 Date a. DO and temperature by date
10
8
6
4 Flow (cfs)
2
0 3/22 4/21 5/21 6/20 7/20 8/19 9/18 10/18 2005 Date
b. Flow by date
12
10
8
pH 6
4
2
0 3/22 4/21 5/21 6/20 7/20 8/19 9/18 10/18 2005 Date
c. pH by date
800 700 600 500 400 300 200
Conductivity (umho/cm) 100 0 3/22 4/21 5/21 6/20 7/20 8/19 9/18 10/18 2005 Date
d. Conductivity by date
167 Fig. 4.6 Minnewashta Creek (CMW01) 2005 Nutrient Concentrations by Date
90
75
60
45
TSS (ppm) 30
15
0 3/22 4/21 5/21 6/20 7/20 8/19 9/18 10/18 2005 Date e.
200 175 150 125 100
TP (ppb) 75 50 25 0 3/22 4/21 5/21 6/20 7/20 8/19 9/18 10/18 2005 Date f.
30
25
20
15
SRP (ppb) 10
5
0 3/22 4/21 5/21 6/20 7/20 8/19 9/18 10/18 2005 Date g.
1.5
1.3
1.1 TN (ppm)
0.9
0.7 3/22 4/21 5/21 6/20 7/20 8/19 9/18 10/18 2005 Date h.
168 5. Schutz Lake Subwatershed The Schutz Lake subwatershed is located in the southern portion of the MCWD, in the city of Victoria. It contains one water body, Schutz Lake, which drains into Smithtown Bay of Lake Minnetonka. The 509 plan goals for this subwatershed are to achieve TP concentrations of less than 40 µg/L, a Secchi depth of greater than 1.4 m and chlorophyll-a concentrations of 1.4 µg/L in Schutz Lake. In addition, MCWD aims to minimize nutrient loading from Schutz Lake into Smithtown Bay.
Figure 5.1 Schutz Lake subwatershed
Schutz Lake Schutz Lake is a 105 acre lake located in the city of Victoria. It has been monitored since 2004, and so long-term trends cannot be discerned. It is not in MPCA compliance, but has nearly met its water quality goals. Compared to other lakes in the area, Schutz Lake is average, receiving a grade of C.
169 Secchi depth ranged from 1.3 m to 2.7 m and averaged 1.9 m (5.2a). It thus meets both the MPCA standard of 1.5 m and the MCWD goal of 1.4 m. This is an improvement from last year’s average of 1.3 m (Fig. 5.2d).
Chlorophyll-a concentrations ranged from 9 µg/L to 52 µg/L , and averaged 34 µg/L (Fig. 5.2b). This level is higher than last year, and above both the MPCA’s standard of 13 µg/L and MCWD’s goal of 14 µg/L .
TP surface concentrations ranged from 21 µg/L to 75 µg/L (Fig. 5.2c), and averaged 40 µg/L . Schutz Lake has thus nearly met MCWD’s TP goal, but since the MPCA requires lakes to have less than 40 µg/L , it is out of compliance. Average TP was lower than last year. Two years of data is not sufficient to determine if a trend is occurring, but if TP decreases even slightly next year, Schutz Lake will have met its TP goal and be in MPCA compliance.
170 Figure 5.2 Schutz Lake 2005 Grade: C
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0.0
0.5
1.0
1.5
2.0 Secchi Depth (m) 2.5
3.0 a.
60
50
40
30
20
10 Chlorophyll a (ppb)
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP
80
60
40
20 Phosphorus (ppb)
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date c.
171 Fig. 5.2 Schutz Lake Summer Mean Values
2.0 2005 Mean = 1.9 m TSIS = 51 1.5
1.0
Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 d.
40 2005 Mean = 34 ppb 35 TSIC = 65 30
25
20
15
10 Chlorophyll a (ppb)
5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
60 2005 Mean = 40 ppb 50 TSIP = 57
40
30
20
Total Phosphorus (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 TSI = 58 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year g.
172 6. Six Mile Marsh Subwatershed Six Mile Marsh subwatershed is located on the western boundary of MCWD in the cities of St. Bonifacius and Victoria and in Laketown and Watertown townships. Six Mile Creek flows from Pierson Lake through several lakes and wetlands to Halsted Bay, and Steiger Lake Creek and Sunny Creek flow from the eastern subwatershed into Lake Auburn, which outlets as Six Mile Creek. In 2005, MCWD monitored lakes Pierson, Wasserman, West Auburn, Parley, Zumbra, and Steiger, as well as Steiger Lake Creek, Sunny Creek, and 3 sites on Six Mile Creek (Fig. 6.1). The 509 Plan goals for this subwatershed include minimizing pollutant loads to Halsted Bay, reaching MPCA standards in lakes and streams, and improving lake TP concentrations as identified in the HHPLS report.
Figure 6.1 Six Mile Marsh subwatershed
173 Pierson Lake Pierson Lake is a 235 acre lake located in Laketown Township. TSI in Pierson Lake is typically between 45 and 60 (Fig. 6.2h). This year, TSI was slightly higher than average, but within its typical range. Compared to other lakes in the area, it is slightly above average, receiving a grade of B-.
Surface TP concentrations ranged from 20 µg/L to 138 µg/L and averaged 44 µg/L . This is higher than average, and more than twice the average concentration in 2003. It no longer meets its HHPLS goal (27 µg/L ) or the MPCA standard (40 µg/L ). Part of the high average concentration can be attributed to a spike that occurred in June (Fig. 6.2c); most of the year, TP was less than 40 µg/L .
Despite the increase in TP, the chlorophyll-a concentration was nearly unchanged from the last few years (Fig. 6.2f). Specifically, it ranged from 3 µg/L to 21 µg/L and averaged 14 µg/L (Fig. 6.2b). This is consistent with previous years and meets its water quality goal (14 µg/L ), but not the MPCA standard (13 µg/L ).
Secchi depth was also consistent with previous years, ranging from 1.1 m to 4.9 m, with an average value of 2.0 m (Fig. 6.2a, e). The lake thus meets its water quality goal and the MPCA standard (> 1.5 m).
Wasserman Lake Wasserman Lake is a 153 acre lake located in Laketown Township. It is on the MPCA’s list of impaired waters for excess nutrients. Its TSI is consistently between 60 and 70 and is in that range this year, as well. Compared to other lakes in the region, its water quality is poor, receiving a grade of D.
Surface TP in the lake ranged from 60 µg/L to 125 µg/L and averaged 84 µg/L . This is a slight decrease from 2004, but average for the lake. It does not meet its water quality goal (50 µg/L ) or the MPCA standard (40 µg/L ).
174 Chlorophyll-a concentrations in the lake ranged from 19 µg/L to 94 µg/L and averaged 61 µg/L. This is an increase from the last 3 years, but still within the range typical for Wasserman Lake. It does not meet the MPCA standard or its water quality goals.
Secchi depth ranged from 0.5 m to 1.3 m and averaged 0.7 m (Fig. 6.3a). This value is lower than the last two years, but average for Wasserman Lake (Fig. 6.3e). It does not meet the MPCA standard and hasn’t met it since monitoring began.
West Auburn Lake West Auburn Lake is a 143 acre lake located in Carver Park Reserve. It is fed by Six Mile Creek, Sunny Creek, and Steiger Lake Creek. The lake’s TSI has been consistent since the 1970s (usually falling between 50 and 60). This year, TSI was 55, an average value for the lake. Compared to other lakes in the area, it is slightly above average, receiving a grade of B-.
Surface TP concentration in the lake ranged from 21 µg/L to 48 µg/L and averaged 33 µg/L (Fig 6.4c). This value is typical for the lake, and nearly unchanged from the last two years. It meets the MPCA standard, but not its HHPLS goal of 27 µg/L .
Chlorophyll-a concentrations ranged from 6 µg/L to 25 µg/L , and averaged 18 µg/L . This is a slight increase from last year and higher than average for the lake, but within the typical range. It does not meet the MPCA’s standard or its water quality goal.
Secchi depth ranged from 1 m to 5.3 m and averaged 1.6 m. This a decrease from last year, and is likely due to the increase in chlorophyll-a. It is a typical value for West Auburn Lake, and meets the MPCA standard and the water quality goal. Because West Auburn Lake meets the MPCA standards for TP and Secchi depth, it is considered to be in compliance for trophic state.
Parley Lake Parley Lake is a 242 acre lake located in Carver Park Reserve and Laketown Township. It is a shallow, eutrophic lake that is on the MPCA’s list of impaired waters for excess nutrients. This year, its TSI was slightly higher than the last few years, but within the typical range for the lake
175 (Fig. 6.5h). It does not meet its HHPLS water quality goals and is of poor quality compared to other lakes in the region, receiving a grade of D+.
Surface TP concentrations were higher than last year, averaging 147 µg/L . The high average concentration is due in part to a mid-summer TP spike in which surface concentrations reached nearly 200 µg/L (Fig. 6.5c). One possible source of TP in the lake is the sediments: just prior to the surface TP spike, TP concentrations at 5 m reached 900 µg/L (Fig. 6.5d).
Chlorophyll-a concentrations were average for the lake, decreasing slightly from 2004. Concentrations in the lake were below 40 µg/L for most of the summer, but reached a maximum of 140 µg/L following the mid-summer spike in surface TP concentrations (Fig. 6.5b). The average value of 69 µg/L is well above the MPCA standard for shallow lakes (20 µg/L ) and just above Parley Lake’s HHPLS goal of 60 µg/L .
Secchi depth was average for the lake, ranging from 0.4 m to 5 m, with a summer average value of 0.7 m. It is below the MPCA standard and its water quality goal (1 m).
Lake Zumbra Lake Zumbra is a 162 acre lake located in Carver Park Reserve and the city of Victoria. It is the source of Sunny Creek, which flows into Six Mile Creek. Compared to other lakes in the area, Zumbra is better than average, receiving a grade of B.
Surface TP concentrations averaged 27 µg/L , which is nearly unchanged since MCWD’s monitoring program began (1997). It meets the MPCA standard and nearly meets its HHPLS water quality goal of 25 µg/L .
Chlorophyll-a concentrations averaged 11 µg/L and ranged from 4 µg/L to 22 µg/L (Fig. 6.6b). This is one of the higher values, but within the typical range for the lake (Fig 6.6e). It meets the MPCA standard and its water quality goal.
Secchi depth averaged 2.6 m, one of the higher average values in the lake (Fig. 6.6d). It meets its water quality goals and MPCA standards.
176 Steiger Lake Steiger Lake is a 158 acre lake located in the eastern portion of Carver Park Reserve. It is the source of Steiger Lake Creek, which flows into Six Mile Creek. Steiger Lake has maintained a TSI of between 50-60 since monitoring began, and this year’s TSI was 55. It has slightly better water quality than most lakes in the area, receiving a grade of B-.
Surface TP concentrations ranged from 22-63 µg/L and averaged 39 µg/L , a typical value for Steiger Lake (Fig. 6.7c, f). It meets the MPCA’s standard, and nearly meets its HHPLS goal of 30 µg/L . Secchi depth averaged 2.1 m, one of the highest average values since monitoring began. It meets both the MPCA standard and its water quality goal.
Six Mile Creek MCWD monitors three sites on Six Mile Creek: between Lake Wasserman and Lake Auburn, near the Auburn inlet (CSI05), at the Lunsten Lake outlet (CSI01), and between Mud Lake and Halsted Bay (CSI02). MCWD also monitors Steiger Creek and Sunny Creek just upstream of Lake Auburn (CSI04 and CSI03, respectively).
Flow in Six Mile Creek was lower than in 2004. All the sites stopped flowing at the end of the summer, and resumed flow after the fall rains. Steiger Creek flowed only after rains, and dried up completely in late August. Nutrient loads decreased from 2004 at all sites, probably because of the lower flows. DO was below 5 mg/L at all sites at some time during the summer.
TP concentrations were comparable among sites and met the MPCA guidelines, except at Highland Road. There, the TP concentration increased from 125 µg/L at Lunsten Lake outlet to 179 µg/L. This downstream increase in TP concentrations has occurred in previous years, indicating a source of TP between Lunsten Lake and Highland Road. Between the two sites, Six Mile Creek flows through Mud Lake and a series of wetlands. Steiger Creek and Sunny Creek contributions were minimal (52 lbs and 86 lbs, respectively), in part because of their low flows (0.31 cfs and 0.32 cfs, respectively). Steiger Creek had a relatively low TP concentration (86 µg/L ), while Sunny Creek had a concentration comparable to the rest of the sites (138 µg/L ).
177 TSS concentrations increased moving downstream, with the biggest increase occurring between Lunsten Lake and Highland Road, where it increased from 7.79 mg/L to 22.5 mg/L. All sites except Highland Road met the MPCA guideline of 10 mg/L. TSS contributions from Steiger Creek were minimal (617 lbs), but more substantial from Sunny Creek (4,615 lbs). Much of this load can be attributed to an exceptionally high TSS concentration (59 mg/L) that occurred on 11/1/05. The average concentration in Sunny Creek was 7.43 mg/L; when the 11/1/05 data point is removed, the average concentration drops to 4.23 mg/L.
SRP concentrations decreased moving downstream (from 27 µg/L at Auburn inlet to 10 µg/L at Highland Road). Because TP concentrations increased moving downstream, this indicates that the form of phosphorus changes as the creek flows – SRP may be taken up by organisms in lakes and wetlands as the creek flows downstream.
TN concentrations increased moving downstream (from 1.22 mg/L at Lake Auburn inlet to 2.05 mg/L at Highland Road. Compared to 2004, concentrations of TN increased, but loads decreased, due to lower flows.
Weekly E. coli samples were taken at Highland Road. At this site, concentrations did not exceed the MPCA standard (1,260 CFU/100 mL); on most sampling dates, it was below 200 CFU/100 mL. The maximum concentration was 640 CFU/100 mL, which occurred the day after a storm (Fig. 6.12c).
178 Figure 6.2 Pierson Lake 2005 Grade: B-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 0.0 1.0 2.0 3.0 4.0 5.0 Secchi Depth (m) 6.0 a.
25
20
15
10
5 Chlorophyll a (ppb)
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date b.
11 m Surface TP Surface SRP Deep TP Deep SRP 160 600
140 500 120 400 100 80 300 60 200 40 Phosphorus (ppb) 100 20 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date 2005 Date c. d.
179 Fig. 6.2 Pierson Lake Summer Mean Values
4.0 2005 Mean = 2.0 m TSIS = 50 3.0
2.0
Secchi Depth (m) 1.0
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
120 2005 Mean = 14 ppb 100 TSIC = 56 80
60
40 Chlorophyll a (ppb) 20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
60 2005 Mean = 44 ppb 50 TSIP = 59 40
30
20
Total Phosphorus (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 55 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
180 Figure 6.3 Wasserman Lake 2005 Grade: D
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 0.0 0.2 0.4 0.6 0.8 1.0
Secchi Depth (m) 1.2 1.4 a.
100 80 60 40 20
Chlorophyll a (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date
b.
11 m Surface TP Surface SRP Deep TP Deep SRP 140 2500
120 2000 100
80 1500
60 1000
Phosphorus (ppb) 40 500 20
0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date 2005 Date c. d.
181 Fig. 6.3 Wasserman Lake Summer Mean Values
1.5 2005 Mean = 0.7 m TSIS = 66
1.0
0.5 Secchi Depth (m)
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
80 2005 Mean = 61 ppb 70 TSIC = 71 60
50
40
30
20 Chlorophyll a (ppb)
10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
120 2005 Mean = 84 ppb 100 TSIP = 68
80
60
40
Total Phosphorus (ppb) 20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 68 70
60
50
Trophic State Index 40
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
182 Figure 6.4 West Auburn Lake 2005 Grade: B-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0
1
2
3
4
Secchi Depth (m) 5
6 a.
30
25
20
15
10
Chlorophyll a (ppb) 5
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP
60
40
20 Phosphorus (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date c.
183 Fig. 6.4 West Auburn Lake Summer Mean Values
3.5 2005 Mean = 1.6 m 3.0 TSIS = 53 2.5
2.0
1.5
1.0 Secchi Depth (m)
0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 d.
40 2005 Mean = 18 ppb 35 TSIC = 59 30
25
20
15
10 Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
90 2005 Mean = 33 ppb 80 TSIP = 54 70 60 50 40 30 20
Total Phosphorus (ppb) 10 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 TSI = 55 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year g.
184 Figure 6.5 Parley Lake 2005 Grade: D+
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 0.0 1.0 2.0 3.0 4.0 5.0 Secchi Depth (m) 6.0 a.
160 140 120 100 80 60 40
Chlorophyll a (ppb) 20 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date b.
5 m Deep TP Deep SRP Surface TP Surface SRP 1000
220 200 900 180 800 160 700 140 600 120 500 100 400 80 300 60 Phosphorus (ppb) 40 200 20 100 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date 2005 Date c. d.
185 Fig. 6.5 Parley Lake Summer Mean Values
3.0 2005 Mean = 0.7 m TSIS = 65
2.0
1.0 Secchi Depth (m)
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
300
2005 Mean = 69 ppb 250 TSIC = 72
200
150
100 Chlorophyll a (ppb)
50
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
350 2005 Mean = 147 ppb 300 TSIP = 76
250
200
150
100 Total Phosphorus (ppb)
50
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 71 70
60
50
Trophic State Index 40
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
186 Figure 6.6 Lake Zumbra 2005 Grade: B
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0
1
2
3
4
Secchi Depth (m) 5
6 a.
25
20
15
10
5 Chlorophyll a (ppb)
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date b.
Surface TP Surface SRP 80
60
40
sphorus (ppb) 20 Pho
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date c.
187 Fig. 6.6 Lake Zumbra Summer Mean Values
5
2005 Mean = 2.6 m 4 TSIS = 46
3
2 Secchi Depth (m) 1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 d.
40 2005 Mean = 11 ppb 35 TSIC = 54 30
25
20
15
10 Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
80
70 2005 Mean = 27 ppb TSIP = 51 60
50
40
30
20
Total Phosphorus (ppb) 10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 TSI = 51 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year g.
188 Figure 6.7 Steiger Lake 2005 Grade: B-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 0
1
2
3
4
Secchi Depth (m) 5
6 a.
30.0 25.0 20.0 15.0 10.0 5.0 Chlorophyll a (ppb) 0.0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date
b.
Surface TP
80
60
40
Phosphorus (ppb) 20
0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 10/28 2005 Date c.
189 Fig. 6.7 Steiger Lake Summer Mean Values
2.5 2005 Mean = 2.1 m TSIS = 49 2.0
1.5
1.0 Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 d.
25
2005 Mean = 20 ppb 20 TSIC = 60
15
10
Chlorophyll a (ppb) 5
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
50 2005 Mean = 39 ppb
40 TSIP = 57
30
20
10 Total Phosphorus (ppb)
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
80 2005 TSI = 55 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year g.
190 Figure 6.8 Six Mile Creek, CSI05 – Highway 5, City of Victoria Drainage Area: 6.29
24 30
20 25
16 20
12 15
8 10 Temperature (C) 4 5 Dissolved Oxygen (mg/L) 0 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
a. DO and temperature by date
8 7 6 5 4 3 Flow (cfs) 2 1 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
b. Flow by date
11 10
9 8 pH 7 6
5 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
c. pH by date
600
500
400
300
200
Conductivity (umho/cm) 100 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
d. Conductivity by date
191 Fig. 6.8 Six Mile Creek (CSI05) 2005 Nutrient Concentration by Date
4000 8/24: 9,750 ppm 3000
2000 TSS (ppm) 1000
0 3/22 4/11 5/1 5/21 6/10 6/30 7/20 8/9 8/29 9/18 10/8 10/28 2005 Date e.
6000 8/2: 19,130 ppb 8/24: 14,181 ppb 5000
4000
3000
TP (ppb) 2000
1000
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date f.
100
75
50 SRP (ppb) 25
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date g.
60
50
40
30
TN (ppm) 20
10
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date h.
192 Figure 6.9 Six Mile Creek, CSI04 – Steiger Lake Outlet, City of Victoria Drainage Area: 1.52 sq. mi. 24 25 20 20 16 15 12
(mg/L) 10 8 Temperature (C) Dissolved Oxygen 4 5 0 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
a. DO and temperature by date
4
3
2 Flow (cfs) 1
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
b. Flow by date
11
10 9 8 pH 7 6 5 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
c. pH by date
1250
1000 dry 750 ?
500
250
Conductivity (umho/cm) 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
d. Conductivity by date
193 Fig. 6.9 Six Mile Creek (CSI04) 2005 Nutrient Concentrations by Date
500
400 dry ? 300
200 TSS (ppm) 100
0 3/22 4/11 5/1 5/21 6/10 6/30 7/20 8/9 8/29 9/18 10/8 10/28 2005 Date e. 2000
dry 1500 ? 1000 TP (ppb) 500
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date f. 125 dry 100 ? 75
50 SRP (ppb) 25
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date g. 6
5 dry 4 ? 3
TN (ppm) 2
1
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date h.
194 Figure 6.10 Six Mile Creek, CSI03 – Sunny Lake Creek, Carver Park Reserve Drainage Area: 3.26 sq. mi 24 30
20 25
16 20
12 15 (mg/L) 8 10 Temperature (C) Dissolved Oxygen 4 5 0 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
a. DO and temperature by date
2.5
2.0
1.5
1.0 Flow (cfs)
0.5
0.0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
b. Flow by date
11
10 9 8 pH 7 6 5 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
c. pH by date
1250
1000
750
500
250
Conductivity (umho/cm) 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
d.. Conductivity by date
195 Fig. 6.10 Six Mile Creek (CSI03) 2005 Nutrient Concentrations by Date
60 50 40 30 20 TSS (ppm) 10 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date e.
600
500
400
300
TP (ppb) 200
100
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date f.
125
100
75
50 SRP (ppb) 25
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date g.
3.0
2.5
2.0
1.5
TN (ppm) 1.0
0.5
0.0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date h.
196 Figure 6.11 Six Mile Creek, CSI01 – Lunsten Lake Outlet, Carver Park Reserve Drainage Area: 15.53 sq. mi.
25 30 30 25 20 25 20 20 15 15 15 10 10 Flow (cfs) 10 Temperature (C) 5 5 5 Dissolved Oxygen (mg/L)
0 0 0 3/3 4/12 5/22 7/1 8/10 9/19 10/29 3/3 4/12 5/22 7/1 8/10 9/19 10/29 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
18
15
12
No E. coli 9 sampling 6
Average flow (cfs) 3
0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
c. Average flow by year
12 600 500 10 400 8
pH 300 6 200 4 Conductivity (umho/cm) 100
2 0 3/3 4/12 5/22 7/1 8/10 9/19 10/29 3/3 4/12 5/22 7/1 8/10 9/19 10/29 2005 Date 2005 Date d. pH by date e. Conductivity by date
197 Fig. 6.11 Six Mile Creek (CSI01) 2005 Flow-Weighted Concentrations and Loads 14 400 12 10 300 8 963 200 6 4 100
Mean TSS (ppm) 2 0 0 TSS Load (1000*lbs) 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year f.
140 3500 120 3000 100 2500 80 2000 60 1500 40 1000 TP Load (lbs) Mean TP (ppb) 20 500 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g. 30 400 25 300 20 15 200 10
100 SRP Load (lbs) Mean SRP (ppb) 5 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h.
2.0 60000 50000 1.5 40000 1.0 30000 20000 0.5 TN Load (lbs) Mean TN (ppm) 10000 0.0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i.
198 Figure 6.12 Six Mile Creek, CSI02 – Six Mile Creek at Highland Road, St. Bonifacius Drainage Area: 23.93 sq. mi.
35 35 30 30 30
25 25 20 20 20 15 15 Flow (cfs) 10 10 10 Temperature (C) 5 5 Dissolved Oxygen (mg/L) 0 0 0 3/3 5/3 7/3 9/3 3/3 5/3 7/3 9/3 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
700 18 600 16 14 500 12 400 10
(per 100 mL) 300 8 6 200
Average Flow (cfs) 4 E. coli 100 2
0 0 1997 19981999 2000 20012002 20032004 2005 6/3 7/23 9/11 10/31 2005 Date Year c. E. coli concentrations by date d. Average flow by year
12 600
11 500
10 400 9 300 pH 8 200 7 100 6 Conductivity (umho/cm) 5 0 3/3 5/3 7/3 9/3 3/3 5/3 7/3 9/3 2005 Date 2005 Date e. pH by date f. Conductivity by date
199 Fig. 6.12 Six Mile Creek (CSI02) 2005 Flow-Weighted Concentrations and Loads 25 600 20 500 400 15 300 10 200 5 TSS Load (1000*lbs)
Mean TSS (ppm) 100 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g. 200 8000
150 6000
100 4000 TP Load (lbs) Mean TP (ppb) 50 2000
0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h. 40 800
30 600
20 400 Mean SRP (ppb) 10 200 SRP Load (lbs)
0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i. 2.2 80000 2.1 60000 2 1.9 40000 1.8 TN Load (lbs) Mean TN (ppm) 20000 1.7 1.6 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year j.
200 7. Langdon Lake Subwatershed The Langdon Lake subwatershed is located in the western portion of the MCWD, in the cities of Minnetrista and Mound. MCWD monitors two sites in the sub-watershed: Langdon Lake and its outlet, Langdon Creek (CLA01, Fig. 7.1). The 509 Plan water quality goals for this sub-watershed include reducing Langdon Lake TP concentrations to 55-70 mg/L, increasing Secchi depth to >1.4 m, and reducing chlorophyll-a concentrations to 14 mg/L. The sub-watershed drains 1.65 square miles, which produced 4.4 inches of runoff (838.8 acre-feet) in 2005.
Figure 7.1 Langdon Lake subwatershed
Langdon Lake Langdon Lake is a 144 acre lake located in the city of Mound. Trophic state has improved in the lake since the 1970s, but has remained consistent for the past several years (Fig. 7.2). In the 1970s, wastewater effluent flowed directly into Langdon Lake. That practice has stopped, which explains the improvement in TSI, but the lake remains out of MPCA compliance. Compared to other lakes in the area, Langdon Lake has some of the worst water quality, receiving a grade of D.
201 TP concentrations at the surface ranged from 75-160 mg/L, and averaged 122 mg/L. This is more than twice the MPCA standard of 40 mg/L. After several years of dramatic decreases, TP levels have remained consistent in Langdon Lake since 1997 (Fig. 7.3)
The chlorophyll-a summer mean was 60 mg/L, which is well above the MPCA standard of 13 mg/L. This is consistent with the previous several years, and an improvement from early 1990s. Chlorophyll-a averages from prior years may be affected by incomplete data, but there does appear to be a general improvement in chlorophyll-a levels.
Average Secchi depth in 2005 was 0.7 m. Secchi depth has remained consistent for the last several years – it also averaged 0.7 m in 1999 and 2002. Even though 0.7 m is the deepest average value recorded on Langdon Lake (Fig 7.5), it is still less than half the MPCA standard of 1.5 m. Average Secchi depth has been quite variable, but appears to have stabilized after several years of gradual improvement.
Langdon Creek Langdon Creek is the outlet for Langdon Lake subwatershed. In 2005, mean flow in the creek was 0.53 cfs, which is lower than it was in 2004, but typical for Langdon Creek (Fig 7.5). The creek stopped flowing for an extended period during the summer, and resumed flow after the fall rains (Fig. 7.6).
Conductivity spiked in the spring, reaching a maximum of 1245 µmho/cm. It remained below 400 µmho/cm for most of the year (Fig. 7.7), however, which is close to average for this ecoregion (301 µmho/cm). The high levels early in the season were probably due to salt that washed off roads after the spring melt.
In 2005, concentrations of TP, TSS, SRP, and TN were consistent with most previous years. TP concentrations averaged 130 mg/L (Fig 7.8), which exceeds MPCA guidelines for the ecoregion, but within the typical range of 60-150 mg/L. Since Langdon Creek drains a lake with above average phosphorus levels, the creek will also likely continue to be high in phosphorus.
202 The TSS load was 15,300 lbs and concentration of TSS averaged 14.6 mg/L (Fig. 7.9). This is above the MPCA guideline for this ecoregion. SRP concentrations averaged 3 mg/L and the 2005 load was 3 lbs. TN concentrations averaged 1.82 mg/L and the load was 1903 lbs.
203 Figure 7.2 Langdon Lake 2005 Grade: D
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 0.0
0.5
1.0
1.5
2.0 Secchi Depth (m)
2.5 a.
120 100 80 60 40 20
Chlorophyll a (ppb) 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date b.
Surface TP Surface SRP Deep TP Deep SRP 7 m 200
1000
150
100 500
50 Phosphorus (ppb)
0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date 2005Date c. d.
204 Fig. 7.2 Langdon Lake Summer Mean Values
0.8
0.7 2005 Mean = 0.7 TSIS = 66 0.6
0.5
0.4
0.3
Secchi Depth (m) 0.2
0.1
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
350 2005 Mean = 60 ppb 300 TSIC = 71 250
200
150
100 Chlorophyll a (ppb) 50
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
1800 2005 Mean = 122 ppb 1600 TSIP = 73 1400 1200 1000 800 600 400 Total Phosphorus (ppb) 200 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
100 2005 TSI = 70 90
80
70
60
50
Trophic State Index 40
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
205 Figure 7.3 Langdon Creek, CLA01 – Langdon Lake Outlet, City of Mound Drainage Area: 1.65 sq. mi.
20 35 5
30 16 4 25 3 12 20
8 15 2 Flow (cfs) 10 4 Temperature (C) 1 5 Dissolved Oxygen (mg/L)
0 0 0 3/29 5/8 6/17 7/27 9/5 10/15 3/29 5/8 6/17 7/27 9/5 10/15 2005 Date 2005 Date a. DO and temperature by date b. Flow by date 1.4 1.2 1.0 0.8 0.6 No E. coli 0.4 sampling 0.2 Average Flow (cfs) 0.0
1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
c. Average flow by year 12 1400 1200 10 1000 800 8 pH 600 400 6 200 Conductivity (umho/cm) 4 0 3/29 5/8 6/17 7/27 9/5 10/15 3/29 5/8 6/17 7/27 9/5 10/15 2005 Date 2005 Date d. pH by date e. Conductivity by date
206 Fig. 7.3 Langdon Creek (CLA01) 2005 Flow-Weighted Concentrations and Loads
600 50
500 40 400 30 300 20 200 Mean TSS (ppm) 100 10 TSS Load (1000*lbs) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year a. 800 300 700 250 600 500 200 400 150 300 100 200 Mean TP (ppb) 100 50 TP Load (lbs) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year b. 50 60
40 50 40 30 30 20 20 SRP Load (lbs) Mean SRP (ppb) 10 10 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year c. 5 6000
4 5000 4000 3 3000 2 2000 TN Load (lbs) Mean TN (ppm) 1 1000 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year d.
207 8. Dutch Lake Subwatershed The Dutch Lake sub-watershed is located in the western portion of the MCWD, in the cities of Minnetrista and Mound. The sub-watershed drains to Jennings Bay of Lake Minnetonka via Dutch Creek. The sub-watershed drains 2.89 square miles, and in 2005, it produced 4.2 inches of runoff (651.7 acre-feet). MCWD monitors two sites in the sub-watershed: Dutch Lake and Dutch Creek (CDU01, Fig. 8.1). The 509 plan goals for the subwatershed include reducing TP to 40 µg/L and chlorophyll-a to 14 µg/L , and increasing the Secchi depth to greater than 1.4 m. In addition, MCWD aims to reduce pollutant loads to Jennings Bay.
Figure 8.1 Dutch Creek subwatershed Dutch Lake Dutch Lake is a 159.5 acre lake located in the city of Mound. Since monitoring began in 1997, TSI has increased slightly in the lake (Fig. 8.2h), although it is lower than last year. Compared to other lakes in the area, Dutch Lake is average, receiving a grade of C-.
208 Surface TP concentration ranged from 45 to 140 µg/L and averaged 64 µg/L . This is a decrease from the last two years, but consistent with prior years (Fig 8.2c). Dutch Lake is out of compliance with the MPCA and its water quality goals for TP.
Chlorophyll-a concentrations ranged from 0 µg/L to 115 µg/L over the summer and averaged 44 µg/L (Fig. 8.2b). This is a decrease from last year, but appears to be part of an increasing trend (Fig. 8.2f). Dutch Lake is out of compliance with the MPCA and its water quality goals for chlorophyll-a.
Secchi depth ranged from 0.4 m to 5.8 m and averaged 1.2 m (Fig. 8.2a). After declining for several years, Secchi depth has increased for the last three (Fig. 8.2e). It is still out of compliance with the MPCA and its water quality goals, however.
Dutch Creek Dutch Creek is the outlet for the Dutch Lake subwatershed. In 2005, mean flow in the creek was 0.9 cfs, which is lower than most previous years, but still typical for Dutch Creek (Fig. 8.3c). The creek stopped flowing for several weeks in the summer and resumed flow after the fall rains (Fig. 8.3b).
Average TP concentration in the stream was 110 µg/L , and the total load was 202 lbs. This is less than 2004, but within the typical range for Dutch Creek (Fig. 8.3g). It is below the MPCA guideline of 170 µg/L .
Average TSS concentration was 14.79 ppm and the total load was 26,200 lbs (Fig. 8.3f). These numbers are typical for Dutch Creek, but above the MPCA guideline of 10 ppm.
The average SRP and TN concentrations and total loads were lower than in 2004 (Fig. 8.3h). Calculations of concentrations and loads prior to 2004 may contain errors, and so were not compared to 2005 data. The errors from previous years are still being traced.
209 Figure 8.2 Dutch Lake 2005 Grade: C-
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 0.0 1.0 2.0 3.0 4.0 5.0 Secchi Depth (m) 6.0 a.
120 100 (ppb)
a 80 60 40 20
Chlorophyll 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date b.
12 m Surface TP Surface SRP Deep TP Deep SRP
150 2500 2000 100 1500 50 1000 500 Phosphorus (ppb) 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date 2005 Date c. d.
210 Fig. 8.2 Dutch Lake Summer Mean Values
2.5
2.0 2005 Mean = 1.2 m TSIS = 58
1.5
1.0 Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
60
50 2005 Mean = 44 ppb TSIC = 68
40
30
20 Chlorophyll a (ppb)
10
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
120
100 2005 Mean = 64 ppb TSIP = 64 80
60
40
Total Phosphorus (ppb) 20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80
70 2005 TSI = 63 60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
211 Figure 8.3 Dutch Creek, CDU01 – Dutch Lake Outlet, City of Mound Drainage Area: 2.95 sq. mi.
30 30 7 6 25 25 20 5 20 15 4 15 10 3 10 Flow (cfs) 5 2 Temperature (C) 5 0 1 Dissolved Oxygen (mg/L) 0 -5 0 3/3 4/12 5/22 7/1 8/10 9/19 10/29 3/3 4/12 5/22 7/1 8/10 9/19 10/29 2005 Date 2005 Date
a. DO and temperature by date b. Flow by date
2.5 2.0 1.5 No E. coli sampling 1.0 0.5 Average Flow (cfs) 0.0
1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
c. Average flow by year
12 600
10 500 8 400 6 300 pH 4 200 2 100
0 Conductivity (umho/cm) 0 3/3 4/12 5/22 7/1 8/10 9/19 10/29 3/3 4/12 5/22 7/1 8/10 9/19 10/29 2005 Date 2005 Date d. pH by date e. Conductivity by date
212 Fig. 8.3 Dutch Creek (CDU01) 2005 Flow-Weighted Concentrations and Loads 70 300 60 250 50 200 40 150 30 20 100
Mean TSS (ppm) 10 50 0 0 TSS Load (1000*lbs) 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year f. 250 1000 200 800
150 600
100 400 TP Load (lbs) Mean TP (ppb) 50 200 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g. 100 10000 1997-2003 80 8000 calculations 60 suspect; error 6000 40 not yet traced 4000 SRP Load (lbs) Mean SRP (ppb) 20 2000
0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h. 100 5000 80 1997-2003 4000 calculations suspect; 60 error not yet traced 3000 40 2000
20 1000 TN Load (lbs) Mean TN (ppm) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i.
213 9. Painter Creek Subwatershed The Painter Creek subwatershed is located in the northwestern portion of the district and includes the cities of Medina, Orono, Maple Plain, Independence, and Minnetrista. Painter Creek flows from Lake Katrina through several wetlands to Jennings Bay of Lake Minnetonka. The 509 water quality goals for the sub-watershed focus on reducing nutrient loading to Jennings Bay by improving TP and TSS concentrations in Painter Creek. In addition, MCWD would like to increase DO levels in the creek. MCWD monitors 6 sites on Painter Creek: at CR 110 near Jennings Bay (CPA05), on West Branch Road (CPA01), on Painter Creek Drive (CPA06), on CR 26 (CPA04), and two sites on CR 6 (CPA02, west of CR19 and CPA03, west of Deborah Drive, Fig 9.1).
Figure 9.1 Painter Creek subwatershed
Painter Creek Flows in Painter Creek were down from 2004, but within the typical range for the creek. At all sites, the creek stopped flowing for a few weeks in the summer, but resumed after the fall rains. DO levels were below 5 mg/L for much of the summer at many sites, but increased in the fall.
214 TP concentrations and loads were lower than 2004 at most sites, but within the range typical for the creek. TP concentrations were more than twice the MPCA standards at all sites. A total of 3,585 lbs of TP was exported to Jennings Bay.
TSS concentrations were similar to 2004 and typical for the creek. The creek met the MPCA standard except at West Branch Road and CR 110, the sites farthest downstream. These sites averaged 21.2 mg/L and 32.4 mg/L, respectively. However, these high values can be attributed to an exceptionally high concentration on 3/30/05. The rest of the year, TSS concentrations were similar to the rest of the creek (10.6 mg/L at West Branch and 10.3 mg/L at CR 110). The TSS load exported to Jennings Bay was 3,585 lbs, most of which occurred in the spring.
SRP and TN concentrations and loads were slightly lower than 2004, but within the typical range for the creek. A total of 1,323 lbs of SRP and 17,408 lbs of TN were exported to Jennings Bay.
E. coli concentrations were sampled weekly at the site on West Branch Road. Concentrations exceeded the MPCA standard twice, on 8/18/05 and 10/5/05. The rest of the year, concentrations were below 400 CFU/100 mL (Fig. 9.6c).
215 Figure 9.2 Painter Creek, CPA03 – County Road 6 at Deborah Drive, Minnetrista Drainage Area: 4.99 sq. mi.
25 30 15
25 20 12
20 15 9 15 6 10 Flow (cfs) 10 Temperature (C) 3 5
Dissolved Oxygen (mg/L) 5 0 0 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/30 7/30 9/30 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
8 7 6 5 No E. coli 4 sampling 3
Average Flow (cfs) 2 1 0 2001 2002 2003 2004 2005 Year
c. Average flow by year
10 600
9 500
8 400
pH 7 300
6 200
5 100 Conductivity (umho/cm) 4 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date d. pH by date e. Conductivity by date
216 Fig 9.2 Painter Creek (CPA03) 2005 Flow-Weighted Concentrations and Loads 8 100 80 6 60 4 40 2 20 Mean TSS (ppm) TSS Load (1000*lbs) 0 0 2001 2002 2003 2004 2005 Year f. 350 3000 300 2500 250 2000 200 1500 150 100 1000
Mean TP (ppb) 50 500 TP Load (lbs) 0 0 2001 2002 2003 2004 2005 Year g. 250 1500 200 1000 150 100 500
50 SRP Load (lbs) Mean SRP (ppb) 0 0 2001 2002 2003 2004 2005 Year h. 2 30000 25000 2 20000 1 15000 10000
1 TN Load (lbs) Mean TN (ppm) 5000 0 0 2001 2002 2003 2004 2005 Year i.
217 Figure 9.3 Painter Creek, CPA02 – County Road 6, City of Maple Plain Drainage Area: 4.99 sq. mi. 18 30 15
15 25 12 12 20 9 9 15 6
6 10 Flow (cfs)
Temperature (C) 3 3 5 Dissolved Oxygen (mg/L) 0 0 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
6 5 4 No E. coli sampling 3 2
Average Flow (cfs) 1 0 2002 2003 2004 2005 Year
c. Average flow by year
12 750 10
8 500
pH 6 250 4
2 Conductivity (umho/cm) 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date d. pH by date e. Conductivity by date
218 Fig. 9.3 Painter Creek (CPA02) 2005 Flow-Weighted Concentrations and Loads
15 120 100 10 80 60 5 40 TSS Load (1000*lbs) 20
Mean TSS (ppm) 0 0 2002 2003 2004 2005 Year f. 400 2500
300 2000 1500 200 1000
100 TP Load (lbs)
Mean TP (ppb) 500 0 0 2002 2003 2004 2005 Year g. 250 1500 200 1000 150 100 500
50 SRP Load (lbs) Mean SRP (ppb) 0 0 2002 2003 2004 2005 Year h. 3 20000
15000 2 10000 1
5000 TN Load (lbs) Mean TN (ppm) 0 0 2002 2003 2004 2005 Year i.
219 Figure 9.4 Painter Creek, CPA04 – County Road 26, City of Minnetrista Drainage Area: 12.4 sq. mi.
16 30 14 14 25 12 12 10 20 10 8 8 15 6
6 Flow (cfs) 10 4
4 Temperature (C)
Dissolved Oxygen (mg/L) 5 2 2 0 0 0 3/3 4/3 5/3 6/3 7/3 8/3 9/3 3/30 4/30 5/30 6/30 7/30 8/30 9/30 10/30 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
21
18
15
12 No E. coli sampling 9 6 Average Flow (cfs) 3
0 2002 2003 2004 2005 Year
c. Average flow by year
12 750
10 600
450 8 pH
300 6
Conductivity (umho/cm) 150
4 0 3/3 4/3 5/3 6/3 7/3 8/3 9/3 10/3 3/3 4/3 5/3 6/3 7/3 8/3 9/3 10/3 2005 Date 2005 Date d. pH by date e. Conductivity by date
220 Fig. 9.4 Painter Creek (CPA04) 2005 Flow-Weighted Concentrations and Loads 10 300 8 250 200 6 150 4 100 TSS Load (1000*lbs) 2 50 Mean TSS (ppm) 0 0 2002 2003 2004 2005 Year f. 400 10000
300 8000 6000 200 4000
100 TP Load (lbs) Mean TP (ppb) 2000 0 0 2002 2003 2004 2005 Year g. 300 5000 250 4000 200 3000 150 2000 100
50 1000 SRP Load (lbs) Mean SRP (ppb) 0 0 2002 2003 2004 2005 Year h. 1.8 60000 1.7 50000 40000 1.6 30000 1.5 20000
1.4 TN Load (lbs)
Mean TN (ppm) 10000 1.3 0 2002 2003 2004 2005 Year i.
221 Figure 9.5 Painter Creek, CPA06 – Painter Drive, City of Minnetrista Drainage Area: 12.75 sq. mi. 15 35 30 12 25 9 20 15
(mg/L) 6 10 5 Temperature (C) Dissolved Oxygen 3 0 0 -5 3/3 4/3 5/3 6/3 7/3 8/3 9/3 10/3 2005 Date
a. DO and temperature by date
15 12 9 6 Flow (cfs) 3 0 3/3 4/22 6/11 7/31 9/19 2005 Date
b. Flow by date 12
10
8
pH 6
4
2 3/3 4/22 6/11 7/31 9/19 2005 Date
c. pH by date
750
500
250
Conductivity (umho/cm) 0 3/3 4/22 6/11 7/31 9/19 2005 Date
d. Conductivity by date
222 Fig. 9.5 Painter Creek (CPA06) 2005 Nutrient Concentrations by Date
180 150 120 90 60 TSS (mg/L) 30 0 3/3 4/22 6/11 7/31 9/19 2005 Date e.
1200 1000 800 600
TP (ug/L) 400 200 0 3/3 4/22 6/11 7/31 9/19 2005 Date f.
300 250 200 150 100 SRP (ug/L) 50 0 3/3 4/22 6/11 7/31 9/19 2005 Date g.
5
4
3
2 TN (mg/L) 1
0 3/3 4/22 6/11 7/31 9/19 2005 Date h.
223 Figure 9.6 Painter Creek, CPA01 – West Branch Road, City of Minnetrista Drainage Area: 13.03 sq. mi.
18 30 25
15 25 20 12 20 15 9 15
Flow (cfs) 10 6 10 Temperature (C) 5 Dissolved Oxygen (mg/L) 3 5
0 0 0 3/30 4/27 5/25 6/22 7/20 8/17 9/1410/12 3/30 4/27 5/25 6/22 7/20 8/17 9/14 10/12 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
400 20 350 8/18: 4,100/100 mL 10/5: 18,000/100 mL 300 15 250
200 10 (per 100 mL) 150
100 5 Average Flow (cfs) E. coli 50 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 6/3 7/23 9/11 10/31 2005 Date Year c. E. coli concentrations by date d. Average flow by year
12 700 600 10 500 8 400
pH 6 300 4 200 2 100 0 Conductivity (umho/cm) 3/30 4/27 5/25 6/22 7/20 8/17 9/14 10/12 0 2005 Date 3/30 5/19 7/8 8/27 10/16 2005 Date e. pH by date f. Conductivity by date
224 Fig. 9.6 Painter Creek 2005 Flow-Weighted Concentrations and Loads 25 400
20 300 15 200 10 5 100 Mean TSS (ppm) 0 0 TSS Load (1000*lbs) 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g. 500 10000 400 8000 300 6000 200 4000 100 2000 TP Load (lbs) Mean TP (ppb) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h. 300 6000 250 5000 200 4000 150 3000 100 2000 SRP Load (lbs)
Mean SRP (ppb) 50 1000 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i. 3 100000 3 80000 2 60000 2 40000 1
20000 TN Load (lbs) Mean TN (ppm) 1 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year j.
225 Figure 9.7 Painter Creek, CPA05 – CR 110, City of Minnetrista Drainage Area: 13.52 sq. mi.
20 30 25 16 20
12 15
8 10 5 Temperature (C) 4 0 Dissolved Oxygen (mg/L) 0 -5 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
a. DO and temperature by date
30
25
20
15
Flow (cfs) 10
5
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
b. Flow by date
11 10
9 8 pH 7 6 5 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
c. pH by date
700 600 500 400 300 200 100
Conductivity (umho/cm) 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
d. Conductivity by date
226 Fig. 9.7 Painter Creek (CPA05) 2005 Nutrient Concentrations by Date
175
150
125
100
75
TSS (ppm) 50
25
0 3/22 4/11 5/1 5/21 6/10 6/30 7/20 8/9 8/29 9/18 10/8 10/28 2005 Date e. 800
700
600 500 400 TP (ppb) 300
200 100 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date f.
300
225
150 SRP (ppb) 75
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date g.
3.5 3.0
2.5 2.0 1.5 TN (ppm) 1.0 0.5 0.0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date h.
227 10. Long Lake Subwatershed The Long Lake subwatershed is located in the northwestern portion of the district. It includes the cities of Orono and Long Lake. MCWD monitors five locations: Long Lake, three sites on Long Lake Creek, and Tanager Lake. The 509 water quality goals for this sub-watershed include lowering TP to 50 µg/L in Long Lake and 70 µg/L in Tanager Lake, increasing Secchi depth to >1.4 m and decreasing chlorophyll-a to 14 µg/L in both lakes.
Figure 10.1 Long Lake subwatershed
Long Lake Long Lake is a 261 acre lake located in the city of Long Lake. It has maintained its Secchi depth and chlorophyll-a and TP concentrations for the last several years, but is out of compliance with the MPCA and has not met its water quality goals. Compared to other lakes in the area, Long Lake is average, receiving a grade of C.
228 Surface TP concentrations ranged from 50 µg/L to 90 µg/L and averaged 63 µg/L (Fig. 10.2c). This is slightly lower than in 2004, but within the range of the last 20 years (Fig. 10.2g). Long Lake does not meet the MPCA standard (40 µg/L) and exceeds its water quality goal.
Chlorophyll-a concentrations ranged from 0 µg/L to 80 µg/L and averaged 44 µg/L (Fig. 10.2b). This is consistent with previous years (Fig. 10.2f), but well above the MPCA standard and its water quality goal (14 µg/L).
Secchi depth ranged from 0.6 m to 3.4 m and averaged 0.8 m (Fig 10.2a). This is consistent with previous years (Fig. 10.2e), but is below its water quality goal (1.4 m) and the MPCA standard (1.5 m).
Long Lake Creek Long Lake Creek flows into Long Lake from the north, outlets on the south, then winds its way south to Tanager Lake. MCWD monitors three sites on the creek: the inlet and outlet to Long Lake (CLO03 and CLO01, Fig. 10.1), and a downstream site between Long Lake and Tanager Lake (at Brown Road, CLO02). Mean flows in the creek increase from the lake inlet (1.27 cfs) to the outlet (3.72 cfs), and are highest downstream (4.9 cfs). At all sites, the creek stopped flowing for several weeks in the summer, but spiked quickly after rainfall. At the outlet, flows were higher than average, but within the typical range. At Brown Road, flows were the highest since monitoring began.
TP concentrations in Long Lake Creek are 240 µg/L at the inlet, 124 µg/L at the outlet, and 253 µg/L at Brown Road. Some of the TP exported to the lake is taken up by the lake, (TP concentrations at the outlet are lower than at the inlet), but additional inputs occur downstream of Long Lake. The creek exceeds the TP MPCA’s guideline of 170 µg/L, except at the outlet. Because of the increasing flows, the TP load increases from the inlet (612 lbs) to the outlet (910 lbs), and is highest at Brown Road (253 lbs). TP concentrations were higher than average, but loads were not.
TSS concentrations follow a different pattern: the highest concentration occurs at the lake outlet and the lowest concentration at Brown Road. The lake is thus a source of TSS, but some of it settles out
229 of the creek between the lake and Brown Road. TSS values at all sites were in the range typical for Long Lake Creek, but do not meet the MPCA guideline.
The mean SRP concentration at the lake inlet was 90 µg/L, but it decreased to 6 µg/L at the lake outlet. Much of the SRP was likely taken up by lake organisms – the TP output did not decrease, just the phosphorus in soluble reactive form. At Brown Road, SRP was 54 µg/L, probably partially due to SRP inputs and partially due to a change in the form of phosphorus. SRP concentration was lower than average at the outlet and higher than average at Brown Road.
TN concentrations increased from the inlet (1.71 mg/L) to the outlet (1.77 mg/L), and were highest at Brown road (1.62 mg/L). Sources of TN thus occur along the length of the creek.
230 Figure 10.2 Long Lake 2005 Grade: C
2005 Date 4/15 5/13 6/10 7/8 8/5 9/2 9/30 0.0
1.0
2.0
3.0 Secchi Depth (m) 4.0 a.
90 80 70 60 50 40 30 20
Chlorophyll a (ppb) 10 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date b.
8 m Surface TP Surface SRP Deep TP Deep SRP 100 2500
80 2000
60 1500
40 1000 Phosphorus (ppb) 20 500
0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date 2005Date c. d.
231 Fig. 10.2 Long Lake Summer Mean Values
3.0 2005 Mean = 0.8 m 2.5 TSIS = 63
2.0
1.5
1.0 Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
160 2005 Mean = 44 ppb 140 TSIC = 68 120
100
80
60
40 Chlorophyll a (ppb) 20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
140
120 2005 Mean = 63 ppb TSIP = 64 100
80
60
40
Total Phosphorus (ppb) 20
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
80 2005 TSI = 65 70
60
50
40 Trophic State Index
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
232 Figure 10.3 Long Lake Creek, CLO03, Long Lake Inlet, Orono Drainage Area: 6.06 sq. mi.
24 30
20 25
16 20
12 15
8 10 Temperature (C) 4 5 Dissolved Oxygen (mg/L) 0 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
a. DO and temperature by date
12
9
6 Flow (cfs) 3
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
b. Flow by date
11
10 9
8 pH 7 6
5 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
c. pH by date
500
400
300
200
100
Conductivity (umho/cm) 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
d. Conductivity by date
233 Fig. 10.3 Long Lake Creek (CLO03) 2005 Nutrient Concentrations by Date
75
60
45
30 TSS (ppm)
15
0 3/22 4/11 5/1 5/21 6/10 6/30 7/20 8/9 8/29 9/18 10/8 10/28 2005 Date e. 750
600
450
300 TP (ppb)
150
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date f.
175 150 125 100 75
SRP (ppb) 50 25
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date g.
10
8
6
4 TN (ppm)
2
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date h.
234 Figure 10.4 Long Lake Creek, CLO01 – Long Lake Outlet, City of Long Lake Drainage Area: 10.7 sq. mi.
30 35 35
25 30 30 25 25 20 20 20 15 15 15
10 Flow (cfs) 10 10
5 Temperature (C) 5 Dissolved Oxygen (mg/L) 5 0 0 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date a. DO and temperature by date b. Flow by date
14
12
10
8 No E. coli sampling 6 4
2 Average Flow (cfs) 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
c. Average flow by year
11 600
9 400 pH
7 200 Conductivity (umho/cm) 5 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date d. pH by date e. Conductivity by year
235 Fig. 10.4 Long Lake Creek (CL001) 2005 Flow-Weighted Concentrations and Loads
25 200
20 150 15 100 10 5 50 Mean TSS (ppm) TSS Load (1000*lbs) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year f. 140 2500 120 2000 100 80 1500 60 1000 40 TP Load (lbs) Mean TP (ppb) 20 500 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g. 30 500 25 400 20 300 15 200 10 100 5 SRP Load (lbs) Mean SRP (ppb) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h.
2.5 40000 35000 2 30000 1.5 25000 20000 1 15000
10000 TN Load (lbs)
Mean TN (ppm) 0.5 5000 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i.
236 Figure 10.5 Long Lake Creek, CLO02 – Long Lake Creek at Brown Road, Orono Drainage Area: 12.26 sq. mi.
25 30 50
25 20 40 20 15 30 15 10 20
10 Flow (cfs) Temperature (C) 5 5 10 Dissolved Oxygen (mg/L) 0 0 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date a. DO and temperature by date b. Flow by date 12
10
8
No E. coli 6 sampling 4
Average Flow (cfs) 2
0 1997 1998 1999 2000 20012002 2003 2004 2005 Year
c. Average flow by year 12 600 10 500
8 400
6 300 pH
4 200
2 100 Conductivity (umho/cm) 0 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date d. pH by date e. Conductivity by date
237 Fig. 10.5 Long Lake Creek (CLO02) 2005 Flow-Weighted Concentrations and Loads 20 500
15 400 300 10 200 5 100 Mean TSS (ppm) TSS Load (1000*lbs) 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year f. 300 3000 250 2500 200 2000 150 1500 100 1000 TP Load (lbs) Mean TP (ppb) 50 500 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g.
55 700 54 600 53 500 52 400 51 300 50 200 SRP Load lbs
Mean SRP (ppb) 49 100 48 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h. 1.75 20000 1.70 1.65 15000 1.60 10000 1.55
1.50 5000 TN Load lbs Mean TN (ppm) 1.45 1.40 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year i.
238 11. Gleason Lake Subwatershed Gleason Lake subwatershed is located in the northern part of the district, in the cities of Plymouth and Wayzata. MCWD monitors Gleason Lake and its inlet and outlet (CGL03, CGL01, Fig. 11.1). The 509 plan goals for the sub-watershed include reducing TP to 80 µg/L and chlorophyll-a to 20 µg/L, and increasing Secchi depth to greater than 1 m in Gleason Lake. The sub-watershed drains 3.85 square miles, which produced 10.9 inches of runoff (2244.9 acre-feet).
Figure 11.1 Gleason Lake subwatershed Gleason Lake Gleason Lake is a 142 acre lake located in the cities of Plymouth and Wayzata. Because 99% of the lake is in the littoral zone, it is considered a shallow lake. Compared to other lakes in the area, it is of average water quality, receiving a grade of C-.
TP concentrations at the lake surface ranged from 25 µg/L to 140 µg/L and averaged 116 µg/L (Fig 12.2c). TP concentrations have varied widely, but this year’s concentration is roughly average (Fig. 12.2g). It is still nearly twice the MPCA standard for shallow lakes (60 µg/L), and is well above its water quality goal of 80 µg/L.
239
Chlorophyll-a was non-existent in the lake until June (Fig 12.2b). Despite this, chlorophyll-a concentrations averaged 70 µg/L (Fig. 12.2f). Chlorophyll-a concentrations have varied widely, but this year’s level is one of the highest. It is over three times the MPCA-recommended level and the district’s water quality goal.
Secchi depth ranged from 0.5 m to 4.2 m and averaged 1.1 m (Fig 12.2a). Secchi depth has been gradually improving since the 1970s (Fig. 12.2e). Gleason Lake thus meets its water quality goal and the MPCA standard for Secchi depth.
Gleason Creek Gleason Creek flows into Gleason Lake from the north, and flows out on the southwestern side, eventually winding its way to Wayzata Bay of Lake Minnetonka.
The lake inlet did not flow for much of the year (Fig. 12.3b). The creek responded vigorously to rain events, flowing up to 11 cfs after a rain. The outlet also stopped flowing for a period in the summer, but flowed more often than the inlet (Fig. 12.4b). Flow at the outlet was 1.1 cfs, which is typical for Gleason Creek.
Conductivity at the inlet and the outlet was consistently higher than average for the ecoregion (Fig 12.3d, Fig 12.4e).
The lake outlet is within the MPCA guidelines for TP, but the inlet is not. The inlet had an average concentration of 273 µg/L, and exported 463 lbs of TP to Gleason Lake (Fig. 11.3f) The outlet had an average concentration of 54 µg/L and exported 118 lbs of TP (11.4g). In order to reduce TP in the lake, improvements must be made upstream, in the area drained by Gleason Creek. The same is true of the other nutrients: more TSS, SRP, and TN enter Gleason Lake than leave it. To reduce loading to Gleason Lake, conditions in the upper subwatershed must be addressed.
240 Figure 11.2 Gleason Lake 2005 Grade: C-
2005 Date
4/15 5/13 6/10 7/8 8/5 9/2 9/30 0.0 1.0 2.0
3.0 4.0 Secchi Depth (m) 5.0 a.
140 120 100 80 60 40 20 0 Chlorophyll a (ppb)
Phosphorus (ppb) 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date
b.
Surface TP Surface SRP Deep TP Deep SRP 4 m
200 450 400 150 350 300 100 250 200 150 Phosphorus (ppb) 50 100 50 0 0 4/15 5/13 6/10 7/8 8/5 9/2 9/30 4/15 5/13 6/10 7/8 8/5 9/2 9/30 2005 Date 2005 Date c. d.
241 Fig. 11.2 Gleason Lake Summer Mean Values
2.5
2005 Mean = 1.1 m 2.0 TSIS = 59
1.5
1.0 Secchi Depth (m) 0.5
0.0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 e.
180 2005 Mean = 70 ppb 160 TSIC = 72 140 120
100
80 60
Chlorophyll a (ppb) 40
20 0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 f.
350 2005 Mean = 116 ppb 300 TSIS = 73 250
200
150
100
Total Phosphorus (ppb) 50
0 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 g.
90 2005 TSI = 68 80
70
60
50
Trophic State Index 40
30 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Year h.
242 Figure 11.3 Gleason Lake Creek, CGL03 – Gleason Lake Inlet, City of Plymouth Drainage Area: 2.56 sq. mi.
24 30
20 25
16 20
12 15
8 10 Temperature (C) 4 5 Dissolved Oxygen (mg/L) 0 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
a. DO and temperature by date
10
8
6
4 Flow (cfs)
2
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
b. Flow by date
11
10
9 8 pH 7
6
5 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
c. pH by date
1000
750
500
250
Conductivity (umho/cm) 0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date
d. Conductivity by date
243 Fig. 11.3 Gleason Lake Creek (CGL03) 2005 Nutrient Concentrations by Date
150
100
TSS (ppm) 50
0 3/22 4/11 5/1 5/21 6/10 6/30 7/20 8/9 8/29 9/18 10/8 2005 Date e. 750
600
450
300 TP (ppb)
150
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date f.
250
200
150
100 SRP (ppb)
50
0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date g.
2.5
2.0
1.5
1.0 TN (ppm)
0.5
0.0 3/22 4/16 5/11 6/5 6/30 7/25 8/19 9/13 10/8 2005 Date h.
244 Figure 11.4 Gleason Creek, CGL01 – Gleason Lake Outlet, City of Wayzata Drainage Area: 4.07 sq. mi.
12 30 30 25 25 10 20 20 8 15 15 6
10 10 Flow (cfs) 4 Temperature (C)
Dissolved Oxygen (mg/L) 5 5 2 0 0 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date a. DO and temperature by date b. Flow by date 5.0
4.0
3.0 No E. coli sampling 2.0 1.0 Average Flow (cfs) 0.0
1997 1998 1999 2000 2001 2002 2003 2004 2005 Year
c. Average flow by year
12 1000
10 800
8 600
pH 6 400
4 200
2 Conductivity (umho/cm) 0 3/30 5/9 6/18 7/28 9/6 10/16 3/30 5/9 6/18 7/28 9/6 10/16 2005 Date 2005 Date d. pH by date e. Conductivity by date
245 Fig. 11.4 Gleason Creek 2005 Flow-Weighted Concentrations and Loads 35 150 30 25 100 20 15 10 50
Mean TSS (ppm) 5 0 0 TSS Load (1000*lbs) 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year f. 140 1500 120 100 1000 80 60 40 500 TP Load (lbs) Mean TP (ppb) 20 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year g.
50 3500 40 3000 1997-2003 2500 30 calculations suspect; error not yet traced 2000 20 1500 1000
10 TN Load (lbs) Mean TN (ppm) 500 0 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year h. 12 30000 10 1997-2003 25000 calculations suspect; 8 20000 error not yet traced 6 15000 4 10000 SRP Load (lbs)
Mean SRP (ppb) 2 5000 0 0 1997 1998 1999 2000 20012002 2003 2004 2005 Year i.
246 D. Hydrodata Program Initiatives
Expanded Monitoring In 2005 the number of stream monitoring sites was expanded to target areas of the MCWD that were underrepresented. In the Six Mile Creek subwatershed 3 new sites were sampled; these sites were streams that entered East Lake Auburn. This strategy allows us to assess the upper reaches of Six Mile Creek. Additional sites around Lake Minnetonka included 2 inlets to Halstead Bay, Painter Creek at Painter Drive, Forest Lake Creek at West Branch Road, Long Lake Creek at CR 6, Gleason Lake inlet, and Peavey Creek at Shoreline Drive. Two sites were added on Minnehaha Creek in 2005: West 56th (Edina) and Hiawatha Ave. in Minneapolis.
In 2006 monitoring will be targeted to enable us to assess lake inflows and outflows (where possible) on the new subwatershed basis. New lake inflow stations include Christmas Creek, Virginia Creek, Schutz Creek, Langdon Creek, and Dutch Creek. Sampling of lakes by MCWD personnel will continue, but will be expanded to include Lake Minnetonka (which has been handled by Three Rivers Parks District in the past). Additional monitoring locations are described later as they pertain to special projects. Four new tipping bucket precipitation gauges (Figure D.1) are being installed in locations with poor data coverage. These include Dutch Lake (Mound), Shorewood City Hall, Minnetonka Public Works, and Burroughs Elementary (Minneapolis, S of Lake Harriet on 50th St.).
Figure D.1 A tipping-bucket precipitation gauge. Note heater on side of bucket.
247 Increased emphasis will also be placed on volunteer monitoring. There are several lakes listed in the District's new 509 plan that have minimal or no monitoring data, lakes which have no public boat access (Figure D.2). Efforts will be made to contact potential volunteers whole live on these waterbodies and increase involvement in the Met Council's CAMP lake volunteer monitoring program. In addition, potential volunteers will be recruited to monitor stream macroinvertebrates in several of the 509 plan subwatersheds through the Met Council's RiverWatch program. MCWD currently funds the monitoring of several sites through this program (Figure D.2).
Figure D.2 Potential volunteer monitoring sites. Stars: lakes; diamonds: macroinvertebrate monitoring sites currently under the Met Council RiverWatch program.
Alum Effectiveness Index Since the 1970s, aluminum sulfate (a.k.a. alum) has been used around the United States as a lake management tool to improve lake water quality. It has been demonstrated that the application of alum can inactivate phosphate anions in lake sediments. Because of this action, phosphorus (P) release from lake sediments can be curtailed with the resulting potential for lake water clarity to be improved. Use of alum can be used to improve water quality in a lake has been used in Minnesota since the 1980s and used in MCWD lakes since the mid 1990s. Several lakes within the MCWD have responded in a positive way with Lake Calhoun being a good example. However, other lakes treated with alum have had minimal or short-term improvements with Long Lake being an example. What are the root factors for these results?
248
The MCWD has contracted with Blue Water Science (St. Paul, MN) to develop an alum effectiveness index. A list of factors that influence the effectiveness of an alum treatment were compiled and reviewed and ranked. Based on these findings we prepared an alum effectiveness index that will aid in determining the potential success of an alum treatment. Additional details of the project can be found in the 2004 Hydrodata Report. The final alum index report is expected in early 2006; a peer-reviewed publication in a lake management journal is anticipated in the near future. Dr. Hatch presented preliminary results for the alum index at the 2005 North American Lake Management Society conference in Madison, WI (Figure D.3). The presentation was well-received, and watershed management organizations were eager to learn more about the project.
Figure D.3 Title slide for the 2005 NALMS Conference presentation.
An Alum Effectiveness Index for Upper Midwestern Lakes
Lorin Hatch, Minnehaha Creek Watershed District Steve McComas, BlueBlue WaterWater ScienceScience
Diatom-Inferred Pre-Development Lake TP Concentrations Using diatoms collected from lake-bottom sediment cores, researchers have been able to estimate pre-European in-lake historical total phosphorus (TP) concentrations in Minnesota. This technique has been employed by the MPCA, and was pioneered by researchers at the St. Croix Watershed Research Station (SCWRS). Greater detail is given in the 2004 Hydrodata Report.
The MCWD contracted with Drs. Mark Edlund (Figure D.4) and Daniel Engstrom of the SCWRS to reconstruct the historical TP concentrations in selected MCWD systems. MCWD staff has chosen the 10 lakes for this study based on two comparisons: unimpaired (St. Albans,
249 Figure D.4 Drs. Hatch and Edlund with extracted bottom core taken from Carsons Bay in April 2005.
Spring Park, Carsons) vs. impaired (Stubbs, Jennings, Halstead) Lake Minnetonka bays and shallow (Parley, Gleason) vs. deep (Wasserman, Langdon) upper watershed lakes.
Cores were collected in April 2005 and MCWD staff collected summer water quality samples. At present, all field collections, magnetics, core processing, subsampling, and diatom preparation has been completed. Diatom analysis, data analysis, and reconstructions should be completed by March 2006, and an annual project report completed by April 2006. A strong education component will also be developed as part of this project.
Minnehaha Creek E. coli Study Weekly monitoring of seven sites along Minnehaha Creek has indicated a large increase of E. coli bacterial concentrations from Lake Minnetonka to Minnehaha Falls. There is also evidence of these concentrations decreasing due to dilution in both Meadowbrook Lake and Lake Hiawatha. E. coli concentrations begin to rise again after passing through these lakes. Additional detail is given in the 2004 Hydrodata Report. Possible sources of E. coli include i) improper sanitary sewer connections with the stormwater sewer, ii) sanitary sewer leaks, iii) surface sources of human/animal fecal matter draining into the stormwater sewer system.
250
The first step to determine sources of this problem is to narrow down the three source possibilities. Optical brighteners (OBs) have been used as a tracer to determine the source of sewer inputs in several studies across the nation. OBs are dyes added to detergents to enhance the "brightness" of fabrics. When help under a UV light, OBs fluoresce.
In our study, dye-free cloth is placed into a mesh cage and placed either in a stream or suspended into a storm drain using fishing line (Figure D.5). After a week the sample is retrieved, dried, and examined under UV light for fluorescence. If a sample is positive (i.e., it glows), we re-test the location to confirm.
Figure D.5 Cage for containment of dye-free fabric; placement of mesh bag into storm drain; recovery of fabric after exposure in the stream.
In fall 2005, District staff began to deploy sampling equipment at several locations along Minnehaha Creek. Initial results showed no evidence of OBs. We then proceeded to hang equipment into several storm drains in the Minneapolis stretch of Minnehaha Creek; winter set in before we were able to resolve logistical problems. We will continue the project in spring 2006.
Use of Remote Sensing to Assess Water Quality Many of the lakes and ponds in the District presently lack water quality goals because regular water quality monitoring is cost-prohibitive. A promising approach to address this need is the use of remote sensing (satellite or airplane) data. Such data may consist of photography and/or sensing of various radiation wavelengths. Models are developed using this information in conjunction with data collected on the Earth surface (a process known as ground truthing).
251 The University of Minnesota and the MPCA have developed techniques to estimate water transparency in all Minnesota lakes that are greater than 20 acres in size (Figure D.6). Following a MCWD Board of Managers workshop presented by Dr. Leif Olmanson of the University of Minnesota on satellite technologies in 2005, the District contracted with the UMN to apply this technique to waterbodies in the MCWD that are in the 5 to 20 acre size range, essentially tripling the number of waterbodies assessed by the satellite technique. Ten images from 1973 to 2004 have been examined to date, and the final report arrived in early 2006. This approach will allow us to see how our smaller waterbodies have changed since the middle 1970s, as well as provide us a baseline for further changes from 2004 into the future.
Figure D.6 Water clarity in the MCWD as assessed by satellite in 2000 (from UMN).
Stubbs Bay Algal Management In April 2005 the MCWD installed five Solarbee lake water circulators (Figure D.7) to assess whether they could control nuisance algal growth in Stubbs Bay. The Solarbee is solar-powered and draws water up from a set depth, spreading out the water over the lake surface. The units are efficient enough to utilize energy collected during daylight hours to operate all night. The theory behind their use is that they take away the advantage blue-green algae have with regards to buoyancy regulation: they may not be able to out-compete other algae, hence algal levels may be
252 Figure D.7 A Solarbee recirculation unit. Note the three floats, solar panels, and uplifted water beneath the unit.
reduced.
In 2005 the MCWD and Three Rivers Parks District monitored water quality in Stubbs Bay to determine whether the Solarbee units perform effectively enough to justify purchase and/or use elsewhere in the MCWD. Initial results were not promising; water quality was essentially unchanged in 2005 from the previous years' data (Figure D.8). While Stubbs Bay displays good water quality during the month of May (a.k.a. the clean water phase), poor water quality occurs during the summer months.
The MCWD has stored the 5 Solarbee units at a Maxwell Bay marina for the winter; they will be re-deployed in spring 2006. Pump Systems, which owns Solarbee, has agreed to operate them for the MCWD at no cost in 2006. The placement of these Solarbees (and perhaps additional units) has yet to be determined.
Note that significant reduction of external nutrient loads (from the watershed) is of crucial importance with respect to lake rehabilitation. Then internal loading should be addressed. The Solarbees may create short-term conditions in which algal nuisance blooms are diminished, allowing recreational users of Stubbs Bay to enjoy better water quality conditions right away. It remains to be seen whether this is possible.
253 Figure D.8 Secchi depth and chlorophyll a concentration over time in Stubbs Bay, Lake Minnetonka. Mean summer values (May-Sept) indicated above bars.
6.0 1.0 1.0 0.8 0.6 0.9 1.2 0.9 0.9 1.1 0.9 5.0
4.0
3.0
2.0 Secchi Depth (m) 1.0
0.0 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Jun-96 Jun-97 Jun-98 Jun-99 Jun-00 Jun-01 Jun-02 Jun-03 Jun-04 Jun-05
Date
80 37 21 29 35 26 26 35 42 32 44 70 60 50 40 30 20 Chlorophyll a (mg/L) 10 0 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Jun-96 Jun-97 Jun-98 Jun-99 Jun-00 Jun-01 Jun-02 Jun-03 Jun-04 Jun-05
Date
New USGS Gauge on Minnehaha Creek at Hiawatha Avenue In fall 2005 the MCWD entered into a cooperative agreement with the United States Geological Survey (USGS) to purchase, install, and maintain a stream gauging station on Minnehaha Creek near Hiawatha Avenue (Figure D.9). The station will be operated by the USGS for precipitation,
254 Figure D.9 USGS gauge on Minnehaha Creek at Hiawatha Avenue in Minneapolis.
stream stage, and stream discharge. Precipitation and stage information is presently available; it will take several months to create a stage-discharge curve. The real-time data can be viewed online at http://waterdata.usgs.gov/mn/nwis/uv?05289800 (Figure D.10). The MCWD will maintain and operate a water quality auto-sampler at the site, in addition to sampling water quality on a weekly basis during open-water conditions.
Figure D.10 Data posted on the USGS website (late Dec. 2005 - early Jan. 2006).
255 STORET Data Transfer STORET (short for STOrage and RETrieval) is EPA’s repository for water quality, biological, and physical data and is used by state environmental agencies, EPA and other federal agencies, universities, private citizens, and many others. The U.S. Environmental Protection Agency (EPA) maintains two data management systems containing water quality information for the nation's waters: the Legacy Data Center (LDC), and STORET. The LDC is a static, archived database and STORET is an operational system actively being populated with water quality data.
The LDC contains historical water quality data dating back to the early part of the 20th century and collected up to the end of 1998. STORET contains data collected beginning in 1999, along with older data that has been properly documented and migrated from the LDC. Both systems contain raw biological, chemical, and physical data on surface and ground water collected by federal, state and local agencies, Indian Tribes, volunteer groups, academics, and others. All 50 States, territories, and jurisdictions of the U.S. are represented in these systems.
In 2005 MCWD staff began the process of uploading our water quality data to the STORET system. It has involved project establishment, station establishment, laboratory establishment, and data review. The process is continuing, and the upload should be complete in early 2006. Beginning in 2005, MCWD staff entered water quality data into a STORET data template for each established station, allowing quick uploading of the data into the STORET system every year.
Analysis of Long-Term Minnehaha Creek Water Quality Data Collection of water quality data on Minnehaha Creek has yielded a significantly-sized data set in the past several years, yet an analysis of this data with respect to long-term trends has not been formalized. Dr. Hatch is now advising a UMN graduate student with respect to this task, focusing primarily on the 2000 to 2004 dataset. Primary goals of this research include getting a better understanding of the flow dynamics of the Creek, along with an assessment the impact of precipitation and hydrological events on discharge and water quality. Completion of this work is expected by mid-2006.
256 Restoration of the Painter Creek Wetland South of County Road 26 High phosphorus (P) levels in Jennings Bay (Lake Minnetonka) have existed for several years, leading to major algal blooms and poor water clarity. A large portion of the P load (predominantly soluble) to Jennings Bay comes from Painter Creek, which has been significantly-disturbed in the past century. Extensive ditching is present in Painter Creek, the remnants of clearing wetlands for unsuccessful row-crop farming and also to carry away effluent from the Maple Plain wastewater treatment plant (went offline in 1986).
Work by Curt Richards (Duke University) determined that soils in certain Painter Creek wetlands had a large capacity to sorb stream soluble P for many years. One such wetland is the County Road 26 (CR26) wetland (Figure D.11). A project is currently underway to return the creek flowpath to its original trajectory (indicated by the green line) in order for the wetland soils to remove P from the system. The MCWD will install a new water quality monitoring station at mouth of wetland (lower right, where blue and green lines meet); additional work includes installation and monitoring of groundwater piezometers to assess changes in water levels, as well as vegetation surveys to determine how the restored wetland hydrology impacts the plant community.
Real-Time Monitoring of Water Quantity Stormwater sampling is a crucial component of the District's H&H modeling efforts; event mean concentrations (EMC) of phosphorus (collected with ISCO stormwater samplers) are needed to model MCWD watersheds, streams, and lakes effectively. In the recent past the District has monitored stream stage with both pressure transducers (aka TROLLs) and ISCO flow monitors. The TROLL data is used to calibrate the District's H&H model, but the ISCO flow monitors have been used to trigger operation of the ISCO stormwater samplers (aka ISCOs) during runoff events. This duplicity not only involves a significant amount of additional labor, but the ISCO flow monitors are often not in sync with the TROLL data. Rather than continuing with this outdated protocol, installation of electronics that allow the TROLLs to "talk" to the ISCO stormwater samplers will save time and effort at minimal cost.
Access to real-time discharge data will allow MCWD Staff to better operate the Gray's Bay Dam
257 Figure D.11 Painter Creek Improvement Project. Blue line: current ditch flowing from top to bottom of figure.
settings and to better inform the public (i.e., canoeists) about discharge and safety along Minnehaha Creek. In addition to the aforementioned communication equipment, installation of telemetry equipment in the form of cellular phone equipment is proposed at Gray's Bay Dam, I- 494, and Browndale Dam. This telemetry will allow MCWD Staff instant computer access to continuous monitoring of 1) Lake Minnetonka elevation, 2) discharge at I-494, and 3) discharge at Browndale Dam. Combining this information with real-time discharge data from the USGS gauge at Hiawatha Avenue, MCWD will be better able to regulate discharge along Minnehaha Creek. In addition, discharge information at I-494 (the first location along the Creek where discharge can be effectively measured) can be corroborated with Gray's Bay Dam gate settings to more accurately reflect the true quantity of water coming out of Lake Minnetonka.
258 Lake-Wide Lake Minnetonka Phosphorus Model Understanding the sources, sinks, and cycling rates of phosphorus in lakes is crucial to understanding where our management efforts should take place. Our regular water quality monitoring of lakes and streams in the District provides us with important data, but internal loading (most lakes) and intra-lake circulation (for Lake Minnetonka) data needs have not been adequately addressed.
The complex morphometry and circulation patterns in Lake Minnetonka have made modeling results for this system less than satisfactory. Simplistic models like BATHTUB cannot represent the hydrodynamic processes in this system, so MCWD staff looked for better models. Dr. Hatch contacted Dr. Miki Hondzo at the Saint Anthony Falls Laboratory (University of Minnesota), a respected researcher in the field of lake processes, and a PhD student was selected to carry out the project. Dr. Hondzo has received permission from the University of Western Australia to use the ELCOM-CAEDYM model (Figure D.12) for this research, which is the state-of-the-art model present today.
The ELCOM (Estuary and Lake Computer Model) is a three-dimensional hydrodynamics model used for predicting the velocity, temperature and salinity distribution in natural water bodies subjected to external environmental forcing such as wind stress, surface heating or cooling. ELCOM is designed to facilitate modeling studies of aquatic systems over time scales extending
Figure D.12 ELCOM-CAEDYM model representations (Univ. Western Australia).
259 to a few weeks, though the limit of computational feasibility depends on the size and resolution requirements of an application and computational resources. ELCOM is suited for comparative studies of the summer and winter circulation patterns, spring versus neap tidal cycles, or dispersal conditions under different flow regimes. ELCOM can be run either in isolation for hydrodynamic studies, or coupled with CAEDYM for simulation of biological and chemical processes.
The Computational Aquatic Ecosystem Dynamics Model (CAEDYM) is an aquatic ecological model that may be run independently or coupled with hydrodynamic models DYRESM or ELCOM. CAEDYM consists of a series of mathematical equations representing the major biogeochemical processes influencing water quality. At its most basic, CAEDYM is a set of library subroutines that contain process descriptions for primary production, secondary production, nutrient and metal cycling, and oxygen dynamics and the movement of sediment. CAEDYM configuration is flexible so that the user can focus on the processes of interest. For example, the model can be configured for a simple set of nutrients-phytoplankton-zooplankton. By simulating several state variables at the species level, CAEDYM can be used to support the understanding and management of a system. In addition, the model can be coupled to the one- dimensional hydrodynamic model (DYRESM) for studies of the seasonal, annual or decadal variation in water quality. For more detailed spatial information, CAEDYM can be run with the three-dimensional hydrodynamic model ELCOM. To maximize speed and memory requirements CAEDYM shares a common internal data structure with both DYRESM and ELCOM. They also use common output data storage formats, and share common Graphical User Interface (GUI) and visualization routines for configuring the model and displaying the results.
In 2006 and beyond, MCWD will amend its Lake Minnetonka sampling procedures to provide additional data to the ELCOM-CAEDYM model. Future work may also include lake-bottom coring to determine internal P release potentials, as well as measurement of in-lake circulation with acoustic Doppler velocimeters.
Lake Minnetonka Bathymetry and Macrophyte Survey The last publicly-available map made of Lake Minnetonka was completed in 1957; significant changes in the lake contours have undoubtedly taken place in the past 50 years. Updating this
260 map would be beneficial with regard to public safety, useful for modeling the Lake (see above), and for monitoring aquatic vegetation changes.
The technology to map Lake Minnetonka is relatively inexpensive, but requires a significant amount of training, fieldwork, and data processing. Mapping equipment can also readily display vegetation coverage, allowing lake managers the ability to track changes in plant distributions.
Ray Valley (MN DNR research scientist) has utilized this technology on Christmas Lake in the District, and has recently published his techniques in peer-reviewed journals. MCWD staff is working with him to determine how the District could best obtain a new map of Lake Minnetonka, whether through a cooperative project with the MN DNR or by training of MCWD staff to conduct the lake survey.
261 Appendix
A – Hydrologic Data Monitoring Plan
The MCWD has an extensive hydrologic data program through which it collects and analyzes precipitation, water level, discharge, water quality, stream flow, and groundwater level data. The District publishes the information in annual hydrologic data reports. In addition, historical hydrologic data that the MCWD has collected since 1968 are maintained in databases and available at the District office.
The program is a cooperative effort by the MCWD, Minneapolis Park and Recreation Board (MPRB), Three Rivers Park District (TRPD, formerly Suburban Hennepin Regional Park District), Lake Minnetonka Conservation District (LMCD), Metropolitan Council (MC), Minnesota Pollution Control Agency (MPCA), and Minnesota Department of Natural Resources (MDNR).
The sampling and analysis program was expanded in 1997 to provide an intensive look at background water quality throughout the watershed, and to better define annual water and nutrient budgets within the watershed. The monitoring program was again expanded in 2003, to provide calibration and validation data for the Hydrologic and Hydraulic Pollutant Loading Study (HHPLS, and in 2004 with the arrival of the MCWD water quality specialist.
The program is presented in the work plan summarized in the tables of this Appendix. The plan lays out the monitoring responsibilities of the various partners and details monitoring locations, frequencies, parameters, and quality assurance measures. Under the expanded program, water quality data from all monitoring partners are combined in a single Microsoft Excel database available from the District. The 2005 monitoring data is available on CD from the District.
The hydrologic data collected by the District and its partners during 2005 can be categorized into four main types: precipitation, lakes, streams, and groundwater monitoring. The monitoring plan is summarized in Tables A1 through A8. Monitoring station locations are shown in Figures A1 through A5.
262 Appendix
Table A1 2005 Upper Watershed Lakes Sampling Conducted by MCWD (refer to Figure A1 for locations)
Lake Sampling Frequency
Biweekly 5X/year Name Site Name Site Gleason LGL01 Carsons Bay LCS01 Long LLO01 (surface only) Dutch LDU01 Langdon LLA01 Pierson LPI01 Wasserman LWS01 Minnewashta LMW01 Parley LPR01 Christmas LCH01
Parameters (all lakes)
Lake Mid-Depth or One meter Every Surface Thermocline above bottom meter TP TP TP TEMP SRP SRP SRP DO TN COND CHLA PH SECC
Biweekly sampling from April through October TP: total phosphorus; SRP: soluble reactive phosphorus; TN: total nitrogen; CHLA: chlorophyll a; SECC: Secchi disk depth; TEMP: temperature; DO: dissolved oxygen; COND: field conductivity; PH: field pH
263 Appendix
2005 Upper Watershed Lakes Sampling Conducted by Three Rivers Table A2 Park District and Metropolitan Council (refer to Figure A1 for locations)
Biweekly Lake Sampling Frequency Parameters (all lakes/bays)
Three Rivers Met Council Lake Every Name Site Name Site Surface Meter W. Auburn* LAU01 Schutz* LSC01 TP TEMP Zumbra* LZUO1 Tamarack* LTA01 TN DO Steiger* LST03 Virginia* LVI01 CHLA COND St. Joes* LSJ01 SECC pH L.Minnetonka** SRP Cooks LCO01 Crystal LCR01 Forest Lake LFO01 Halstead LHL01 Stubbs LSU01 Harrisons LHR01 Wayzata LWA01 Jennings LJE01 West Arm LWE01 LL South LGI01 W. Upper LCI01 Maxwell LMA01 E. Upper*** LEU01 North Arm LNR01 Grays*** LGB01 Peavey Pond LPE01 Lafayette*** LLF01 Spring Park LSP01 LL North*** LMU01 St. Albans LAL01 Priests*** LPT01
Biweekly sampling from April through October TP: total phosphorus; SRP: soluble reactive phosphorus; TN: total nitrogen; CHLA: chlorophyll a; SECC: Secchi disk depth; TEMP: temperature; DO: dissolved oxygen; COND: field conductivity; PH: field pH *Surface only **Samples also taken for TP and SRP at i) thermocline and ii) 1 m off bottom ***Monthly
264 Appendix
Table A3 Minneapolis Lake Sampling Conducted by the MPRB (refer to Figure A1 for locations)
Location Parameters
Lake All Other Every Name Site Depths Sampled (m) Surface Depths meter Brownie LBR01 0, 5, 7, 12 TP TP TEMP Cedar* LCE01 0, 3, 5, 7, 10, 14 TDP*** TDP*** DO Isles* LIS01 0, 3, 5, 7 SRP SRP COND Calhoun* LCA01 0, 3, 6, 9, 12, 18, 22 TN PH Harriet* LHA01 0, 3, 6, 9, 12, 15, 20 CHLA Nokomis** LNK01 0, 4, 6 PHYTO Hiawatha** LHI03 0, 4 ZOOPL Powderhorn** LPO01 0, 4, 6 SECC Diamond** LDI01 Grab Sample
*Biweekly sampling from April through October **Once during January, April, and October, biweekly during summer ***TDP analysis not done for Brownie Lake, Lake Hiawatha, or Diamond Lake
TP: total phosphorus (3 ppb DL); TDP: total dissolved phosphorus (3 ppb DL); SRP: soluble eactive phosphorus (2 ppb DL); TN: total nitrogen (46 ppb DL); CHLA: chlorophyll a (0.2 ppb DL); PHYTO: phytoplankton surface sample (twice annually); ZOOPL: zooplankton vertical column sample (twice annually); SECC: Secchi disk depth; TEMP: temperature; DO: dissolved oxygen; COND: field conductivity; PH: field pH. Surface samples taken quarterly for silica (50 ppb DL), alkalinity (370 ppb DL), chloride (144 ppb DL), and hardness (1 ppm DL) Note: DL = Minimum Detection Limit
265 Appendix
Table A4 Lake Level Monitoring Site (refer to Figure A3 for locations)
Name Site Monitor Lake Auburn, West LAU04 TRPD Calhoun, Upper Lakes LCA03 MPRB Christmas Lake LCH03 MCWD Church Lake LCU01 MCWD Dutch Lake LDU02 MCWD Galpin Lake LGA02 MCWD Gleason Lake LGL02 Don Patterson Grass Lake LGR02 Mark McHugh Lake Harriet LHA03 MPRB Lake Hiawatha LHI04 MPRB Holy Name Lake LHN01 MCWD Katrina Lake LKA01 TRPD Long Lake LLO02 Wenck Associates Kelser's Pond LKE01 MCWD Langdon Lake LLA02 Mark Fellegy Long Lake LL002 DNR Lunsten Lake LLU01 TRPD Lydiard Lake LLY01 MCWD Mooney Lake LMO01 Karl Pokorney Lake Minnetonka LMT01 MCWD Lake Minnewashta LMW03 MCWD Parley Lake LPR02 MCWD Piersons Lake LPI02 MCWD St. Joe Lake LSJ01 MCWD Schutz Lake LSC01 Lance Fisher Snyder Lake LSN01 MCWD Stieger Lake LST03 TRPD Stone Lake LSO01 MCWD Tamarack Lake LTA01 MCWD Turbid Lake LTU01 Chuck Johnson Lake Virginia LVI02 Renay Leone Wasserman Lake LWS02 MCWD Zumbra Lake LZU03 MCWD
266 Appendix
Table A5 Minnehaha Creek Monitoring Conducted by MCWD (refer to Figure A2 for locations)
Water Flow Stage Quality Name Site Automated Gauging Read Automated Manual Grays Bay Outflow CMH07 Troll Yes Yes Yes I-494 Ramps CMH19 Troll Yes Yes ISCO Yes West 34th St. CMH02 Yes Yes Yes Excelsior Blvd. CMH11 Yes Yes Yes Browndale Dam* CMH03 Troll Yes Yes ISCO Yes Upton Ave. CMH12 Yes Yes Yes W. 56th Ave. CMH04 Yes Yes Yes Chicago Ave. CMH05 Yes Yes Yes 32nd Ave. CMH17 WOMP Yes Yes ISCO Yes Hiawatha Ave. CMH06 Troll Yes Yes Yes
Automated sampling occurs during and after rainfall events Manual weekly water quality sampling occurs between March and October *Water quality samples collected downstream of dam at 50th Street; continuous flow records are maintained both upstream and downstream of dam WOMP: automated flow and water quality data collected by MPRB and Met Council Troll: pressure transducers that measure water stage (height above stream bottom) ISCO: automated samplers, equipped with area velocity meters Field parameters sampled: discharge, temperature, dissolved oxygen, pH, conductivity Lab parameters sampled: total phosphorus, soluble reactive phosphorus, total nitrogen, total suspended solids, conductivity Note: E. coli sampled for all sites (May to September only)
267 Appendix
Table A6 Upper Watershed Stream Monitoring Conducted by MCWD (refer to Figure A2 for locations)
Water Flow Stage Quality Name Site Automated Gauging Read Automated Manual Six Mile, Lunsten Lk. Outlet CSI01 Troll Yes Yes Yes Six Mile, Sunny Lk Ck @ CR11 CSI02 Yes Yes Yes Six Mile, Hwy 7* CSI03 Doppler Yes Yes ISCO Yes Six Mile, Steiger Lk Ck @ CR11 CSI04 Yes Yes Yes Six Mile, Hwy 5 CSI05 Yes Yes Yes Painter, W. Branch Rd.* CPA01 Troll Yes Yes ISCO Yes Painter, Hwy 6 & 110 CPA02 Yes Yes Yes Painter, Hwy 6 & Deborah Dr.* CPA03 Troll Yes Yes ISCO Yes Painter, Painter Marsh Outlet* CPA04 Troll Yes Yes ISCO Yes Painter, Hwy 110 @ Jennings Bay CPA05 Yes Yes Yes Painter, Painter Ck Drive CPA06 Yes Yes Yes Halstead Inlet, Halstead Dr (North) CHI01 Yes Yes Yes Halstead Inlet, Halstead Dr (South) CHI02 Yes Yes Yes Langdon, Hwy 110 CLA01 Yes Yes Yes Dutch, Hwy 110 CDU01 Yes Yes Yes Forest, W. Branch Rd. CFO01 Yes Yes Yes Stubbs Inlet, Stubbs Bay CST01 Yes Yes Yes Classen, Bayside Rd. CCL01 Yes Yes Yes Long, Long Lake Outlet CLO01 Troll Yes Yes Yes Long, Long Lake Inlet (CR6) CLO02 Yes Yes Yes Long, Brown Rd.* CLO03 Doppler Yes Yes Yes Gleason, Gleason Lake Inlet CGL03 Yes Yes Yes Gleason, Gleason Lake Outlet CGL01 Yes Yes Yes Peavey, Peavey Ck, Shoreline Dr. CPE01 Yes Yes Yes Minnewashta, Lake Virginia Outlet CMW01 Yes Yes Yes Christmas, Christmas Lake Outlet CCH01 Yes Yes Yes
*Automated sampling occurs during and after rainfall events Manual weekly water quality sampling occurs at all sites for March through October Troll: pressure transducers that measure water stage (height above stream bottom) Doppler: doppler devices that can assess discharge in areas where backflow can occur; manual flow gauging occurs at 20% and 80% of stream depth ISCO: automated samplers, equipped with area velocity meters Field parameters sampled: discharge, temperature, dissolved oxygen, pH, conductivity Lab parameters sampled: total phosphorus, soluble reactive phosphorus, total nitrogen, total suspended solids Note: E. coli sampled for sites CSI03 and CPA01 (May to September only)
268 Appendix
Table A7 Precipitation Gauge Network (refer to Figure A4 for locations)
Location Site Monitor Chanhassen PCN02 NOAA(1) Chanhassen PCN03 CPR: Unknown Delano PDL01 NOAA CPR (2): David H. Greenwood PGE01 Cochran Hamel PHM01 CPR: Robert Mealman Mound PMD01 NOAA Minneapolis PMP01 CPR: Unknown Minneapolis PMP02 CPR: John Bullough Minneapolis-St. Paul Int'l Airport PMP03 National Weather Service Minneapolis- Lower St. Anthony Falls PMP04 NOAA Minneapolis PMP05 MCWD New Hope PNW01 NOAA Plymouth PPL01 CPR: Paul D. Josephson Plymouth PPL02 CPR: Don Patterson Richfield PRI02 City Gauge at Wood Lake
NOAA: National Oceanic and Atmospheric Administration; CPR: Citizen Precipitation Recorder
269 Appendix
Table A8 MCWD Monitoring Program Quality Assurance/Quality Control Summary
Sample Type Description Function Frequency Quality Assurance Used in estimating Equipment Reagent-grade deionized background 10% of sampling Blank water subject to sample due to sampling collection, trips* collection, processing, and processing, and analysis analysis Every sampling Bottle Reagent-grade deionized Used in estimating trip Blank water subject to sample background due to sample processing and analysis processing and analysis Duplicate of lake Every sampling Field samples Used in estimating overall trip or 1 per 10 Duplicate within -batch precision samples) Alternate Laboratory Synthetic sample of Used in estimating overall sampling among-batch precision and Audit natural lake lab trips bias Every sampling Blind Standard solution with Estimates batch precision trip Standard ficticious site I.D.
Quality Control Used in identifying signal Calibration Reagent-grade drift One/lab batch Blank deionized water and contamination of samples
One/lab batch Reagent Reagent-grade deionized Used in identifying (10% Blank water plus reagents contamination of reagents of samples) Quality Standard solution from Used in determining accuracy One/lab batch Control source other than and consistency of instrument calibration standard calibration 4 times per year Split Split of lake sample Used in determining for Samples comparability 10 samples Used in determining One/lab batch Laboratory Split of sample aliquot analytical (10% Duplicate within -batch precision of of samples) analytical lab measurements Matrix One/lab batch Spike/ Known spike of sample Used in determining percent (10% Matrix recovery of parameter Spike analyzed of samples) Duplicate *Sampling trip is defined as a sampling cycle, or one cycle of stream samples or lake samples, and not justone day's sampling
270 Appendix
B - Lake and Stream Characteristics
Table B1 Lake Characteristics in the MCWD
Area Maximum Mean Depth Lake Site (ac) Depth (ft) (ft) Latitude Longitude Brownie LBR01 18 49 22 44.9667 -93.3250 Calhoun LCA01 421 90 35 44.9399 -93.3105 Cedar LCE01 170 51 20 44.9620 -93.3179 Christmas LCH01 276 87 33 44.8948 -93.5444 Diamond LDI01 41 6 3 44.9009 -93.2701 Dutch LDU01 160 45 15 44.9430 -93.6854 Galpin LGA01 48 13 6 44.8963 -93.5652 Gleason LGL01 156 16 8 44.9784 -93.4926 Grass LGR01 27 5 2 44.8931 -93.2984 Harriet LHA01 353 82 29 44.9205 -93.3063 Hiawatha LHI01 54 23 13 44.9208 -93.2363 Isles LIS01 103 31 9 44.9545 -93.3099 Langdon LLA01 144 38 8 44.9325 -93.6727 Long LLO01 144 38 8 44.9881 -93.5617 Minnewashta LMW01 656 70 15 44.8783 -93.6101 Mud LMD01 74 5 44.8945 -93.7424 Mooney LMO02 111 10 44.9994 -93.5207 Nokomis LNK01 204 33 14 44.9076 -93.2408 Parley LPR01 254 20 7 44.8802 -93.7267 Pierson LPI01 340 40 44.8321 -93.6975 Powderhorn LPO01 11 20 4 44.9411 -93.2565 Schutz LSC01 105 49 44.8753 -93.6456 St. Joes LSJ01 14 52 44.9595 -93.3388 Steiger LST01 164 37 11 44.8681 -93.6589 Stone LSN01 100 30 7 44.8892 -93.6780 Tamarack LTA01 24 82 44.8732 -93.6348 Twin LTW01 24 44.9588 -93.3374 Virginia LVI01 116 34 44.8859 -93.6333 Wasserman LWS01 153 41 7 44.8410 -93.6736 West Auburn LAU01 140 84 17 44.8674 -93.6941 Zumbra LZU01 162 58 14 44.8891 -93.6631
271 Appendix
Table B2 Lake Minnetonka Bay Characteristics
Area Maximum Mean Bay Site (ac) Depth (ft) Depth (ft) Latitude Longitude Big Island LBI01 46 44.9397 -93.5599 Black LBL01 25 25 44.9306 -93.6362 Browns LBB01 88 44.9553 -93.5477 Carman LCM01 20 44.9288 -93.6111 Carsons LCS01 29 44.9253 -93.5323 Cooks LCO01 362 43 44.9256 -93.6637 Crystal LCR01 900 113 28 44.9488 -93.5934 East Upper LEU01 1956 48 44.9152 -93.6060 Excelsior LEB01 30 44.9093 -93.5641 Forest Lake LFO01 84 42 44.9575 -93.6329 Gideons LGD01 57 44.9100 -93.5853 Grays LGB01 207 28 44.9530 -93.4937 Halstead LHL01 544 36 13 44.9149 -93.6882 Harrisons LHR01 211 46 9 44.9409 -93.6526 Jennings LJE01 290 26 11 44.9543 -93.6524 Lafayette LLF01 60 44.9337 -93.5905 Libbs LLB01 17 8 44.9461 -93.4874 LL North LMU01 90 44.9469 -93.5438 LL South LGI01 1069 77 44.9181 -93.5668 Maxwell LMA01 300 44 14 44.9575 -93.6079 N. Arm LNR01 307 64 14 44.9530 -93.6206 Peavey Lake LPE01 8 52 44.9647 -93.5360 Priests LPT01 46 44.9195 -93.6799 Smithtown LSM01 80 44.8883 -93.6402 Spring Park LSP02 408 36 44.9264 -93.6281 St. Albans LAL01 164 44 14 44.9087 -93.5493 Stubbs LSU03 195 37 13 44.9700 -93.6156 Tanager Lake LTG01 74 44.9613 -93.5607 Wayzata LWA01 751 63 44.9581 -93.5073 W. Arm LWE01 580 44 11 44.9435 -93.6342 W. Upper LCI01 879 84 44.9055 -93.6636
272 Appendix
Table B3 Creek Sampling Locations in the MCWD
Name Location Site Latitude Longitude Christmas Lake Cr. Lake Outlet CCH01 44.9008 -93.5509 Classen Lake Creek Bayside Road CCL01 44.9716 -93.6081 Dutch Lake Creek Highway 110 CDU01 44.9502 -93.6657 Forest Lake Creek Lake Inlet CFO01 44.9637 -93.6363 Gleason Lake Creek Lake Outlet CGL01 44.9782 -93.4961 Gleason Lake Creek Lake Inlet CGL03 44.9921 -93.4905 Halstead Inlet North Halstead Drive CHI01 44.9170 -93.7090 Halstead Inlet South Halstead Drive CHI02 44.9165 -93.7115 Langdon Lake Creek Highway 110 CLA01 44.9318 -93.6693 Long Lake Creek Lake Outlet CLO01 44.9850 -93.5606 Long Lake Creek Lake Inlet at CR 6 CLO03 44.9958 -93.5612 Long Lake Creek Brown Rd CLO03 44.9670 -93.5734 Minnehaha Creek West 34th, St. Louis Park CMH02 44.9427 -93.3935 Minnehaha Creek Browndale Dam CMH03 44.9119 -93.3423 Minnehaha Creek West 56th St., Edina CMH04 44.8990 -93.3318 Minnehaha Creek Chicago Ave. CMH05 44.9112 -93.2625 Minnehaha Creek Hiawatha Ave. CMH06 44.9147 -93.2134 Minnehaha Creek Grays Bay Tailwater CMH07 44.9529 -93.4871 Minnehaha Creek Excelsior Blvd., St. L. Pk CMH11 44.9269 -93.3625 Minnehaha Creek Upton Ave. S., MPLS CMH12 44.9055 -93.3147 Minnehaha Creek 32nd Ave, Mpls CMH17 44.9186 -93.2256 Minnehaha Creek I- 494 CMH19 44.9412 -93.4551 Minnewashta Creek Lake Virginia Outlet CMW01 44.8834 -93.6388 Painter Creek West Branch Road CPA01 44.9640 -93.6724 Painter Creek Hwy 6 & 110 CPA02 44.9931 -93.6604 Painter Creek Hwy 6 & Deborah Dr. CPA03 44.9918 -93.6436 Painter Creek Painter Marsh Outlet CPA04 44.9749 -93.6870 Painter Creek CR 110 in Minnetrista CPA05 44.9619 -93.6644 Painter Creek Painter Creek Drive CPA06 44.9674 -93.6811 Peavey Creek Shoreline Drive CPE01 44.9704 -93.5369 Six Mile Creek Lunsten Lake Outlet CSI01 44.8733 -93.7207 Six Mile Creek Hwy 7 CSI03 44.9010 -93.7343 Six Mile Creek Steiger Lake Creek, CR11 CSI04 44.8639 -93.6718 Six Mile Creek Hwy 5 (from Wasserman) CSI05 44.8613 -93.6745 Six Mile Creek Sunny Lake Creek, CR11 CSI06 44.8692 -93.6783 Stubbs Bay Inlet Wetland Outlet CST01 44.9739 -93.6207
273 Appendix
Table B4 Precipitation Gauge Locations in the MCWD
Name Location Site Latitude Longitude Carver Park (MCWD) TRPD Maint. Garage PCA01 44.8721 -93.6928 Chanhassen (NOAA) NOAA PCN02 44.8541 -93.5741 Deephaven (MCWD) MCWD Office PDH01 44.9422 -93.5146 Long Lake (MCWD) City of Long Lake Office PLO01 44.9873 -93.5755 Maple Plain (MCWD) Wenck Office PME02 45.0113 -93.6690 MSP Airport MSP Airport PMP03 44.0740 -93.2141 St. Louis Park (MCWD) St. Louis Park Fire Station PSL01 44.9319 -93.3713
274
Table B5 Subwatershed Characteristics in the MCWD
Single Multi- Highway/ Family Family Right of Retail/ Area Subwatershed (ac) Resid. Water Vacant Park/Open Resid. Indust. Agricult. Institutional Commercial Way Office Christmas Lake 743 336 6 14 25 12 13 Schutz Lake 969 137 110 267 173 0.03 222 49 12 Langdon Lake 1056 231 235 418 25 3 12 103 27 2 Dutch Lake 1888 267 181 1167 100 0.1 94 79 0.1 0.1 Gleason Lake 3766 2438 301 377 158 64 47 8 199 101 73 Lake Virginia 3991 916 874 627 1229 3 222 43 60 18 Painter Creek 8218 1090 396 3916 1618 9 38 1510 51 18 25 Long Lake 8218 2296 791 3394 698 14 64 738 113 81 30 Six Mile Creek 17033 1211 2404 4267 3727 17 58 5019 173 51 105 Minnehaha Creek 30301 16680 1674 1661 3878 1133 939 1470 1444 1423 Lake Minnetonka 32516 9408 14645 5064 1610 139 69 649 381 429 121
Data from Metropolitan Council 2000 Land Use
275 Appendix
Table C1 Minneapolis-St. Paul International Airport Precipitation
Snowfall Precipitation Month 2005 Longterm 2005 Longterm January 8.6 13.7 1.21 1.04 February 8 8.2 0.96 0.79 March 6.6 10.5 1.37 1.86 April trace 3.1 2.3 2.31 May trace 0.1 2.78 3.24 June 0 0 4.24 4.34 July 0 0 2.94 4.04 August 0 0 5.22 4.05 September 0 0 4.44 2.69 October trace 0.6 5.45 2.11 November 5.1 10 1.53 1.94 December 14.5 10.1 0.97 1 TOTAL 42.8 56.3 33.41 29.41
Longterm: 1971-2000 mean
276 Appendix
Table C2 Groundwater Monitoring Well Elevations (above mean sea level)
#27043 #27012 #27041 #27036 #27044 #27010 Golden St. Louis St. Date Mound Valley Park Minneapolis Bonifacius Orono 3/20/02 888.40 853.00 794.47 793.32 889.61 895.69 4/17/02 888.59 852.53 795.41 792.05 889.71 895.70 5/14/02 888.81 853.05 794.97 792.12 888.72 894.54 6/18/02 888.38 792.75 789.41 887.19 892.21 6/19/02 851.96 7/15/02 887.48 851.99 790.02 787.24 886.15 889.71 8/15/02 884.28 852.20 787.17 886.99 888.49 9/16/02 882.52 853.02 785.61 789.85 886.98 892.59 10/18/02 885.73 785.40 794.29 889.59 895.24 10/21/02 854.65 11/18/02 887.86 854.63 788.73 793.40 889.88 896.54
12/23/02 888.99 890.62 896.60 12/26/02 854.47 791.82 793.56 3/17/03 889.77 795.42 793.53 890.70 897.10 3/18/03 853.74 4/17/03 889.90 853.44 795.90 792.89 891.20 895.60 5/15/03 888.79 890.02 895.02 8/27/03 851.40 9/2/03 785.32 784.95 9/11/03 881.65 881.62 10/10/03 884.50 852.46 782.55 789.94 884.54 888.30 11/28/03 793.11 11/29/03 887.30 853.91 786.91 888.45 895.99 3/19/04 888.12 849.22 794.94 793.54 870.06 895.02
5/8/04 887.03 852.48 795.47 790.07 887.07 889.05 6/11/04 887.70 853.99 794.17 791.65 887.99 893.71 7/17/04 885.34 853.24 791.63 790.50 885.74 7/19/04 889.92 8/19/04 883.22 852.30 788.02 789.74 884.85 886.28 9/2/04 786.80 9/18/04 883.54 855.30 790.41 886.28 889.11 10/17/04 885.27 854.81 792.47 887.71 893.00 10/28/04 786.45 11/14/04 886.85 853.93 793.47 888.25 894.14 11/16/04 788.89 12/17/04 887.56 853.93 790.98 793.60 888.76 894.41 1/13/05 889.27
3/17/05 888.11 795.28 793.61 894.69 3/18/05 853.11 930.80 4/28/05 892.94 4/30/05 887.43 852.71 796.31 793.09 5/21/05 887.50 853.10 796.32 794.23 894.38 6/14/05 887.55 852.72 795.87 790.51 894.69
277 Table C3 Lake Elevation Gauge Readings (feet above mean sea level) Kelzers/ St. Date Minnewashta Joe Tamarack Zumbra Church Trillium Wasserman Parley Saunders Stone Galpin Christmas 5/6/05 944.70 945.44 966.52 942.05 948.20 956.48 943.99 929.39 947.19 942.66 931.56 5/11/05 944.75 945.62 966.46 942.06 948.26 956.50 943.97 929.56 947.21 942.72 931.66 5/20/05 944.96 945.84 966.69 942.20 948.49 956.66 945.15 929.71 946.55 947.33 943.08 931.84 5/26/05 944.92 945.78 966.74 942.20 948.40 956.64 944.11 929.75 946.56 947.29 943.08 931.85 6/2/05 944.82 945.72 966.74 942.16 948.30 956.60 944.02 929.67 946.49 947.23 942.28 931.80 6/10/05 945.00 945.90 966.66 942.30 948.62 956.80 945.29 929.91 946.78 947.39 943.51 932.02 6/17/05 945.00 945.79 966.56 942.36 948.42 956.81 944.31 929.93 946.82 947.33 943.44 932.02 6/21/05 945.04 945.86 966.56 942.44 948.56 956.90 944.33 929.93 946.86 947.35 943.50 932.04 7/8/05 944.74 945.58 966.10 942.33 948.18 956.73 944.01 929.49 946.74 947.19 943.22 931.84 7/15/05 944.60 945.42 965.82 942.19 948.12 956.60 943.97 929.21 946.62 947.07 943.08 931.74 7/22/05 944.44 945.28 965.72 942.04 948.04 956.46 943.79 929.13 946.52 946.96 942.97 931.66 7/29/05 944.45 945.38 965.77 942.06 948.12 956.46 943.69 929.11 945.08 946.99 942.98 931.64 8/4/05 944.40 945.34 965.70 941.91 948.12 956.45 943.69 929.09 946.57 946.85 942.06 931.64 8/12/05 944.38 945.36 965.60 941.81 948.10 956.38 943.59 929.05 946.56 946.87 942.84 931.62 8/18/05 944.26 945.12 965.50 941.74 948.06 956.30 943.49 928.87 946.47 946.69 942.72 931.44 8/26/05 944.34 945.44 965.62 941.74 948.12 956.38 943.57 928.91 946.64 946.89 942.80 931.54 9/2/05 944.36 945.38 965.58 941.60 948.06 956.28 943.41 928.71 946.52 946.81 942.66 931.40 9/9/05 945.22 945.90 966.40 942.02 948.58 956.62 943.89 929.21 947.18 947.25 943.64 932.02 9/16/05 945.12 945.76 966.32 942.00 948.50 956.68 943.89 929.21 947.32 947.25 943.38 931.92 9/22/05 945.08 945.70 966.30 942.04 948.48 956.72 943.81 928.41 947.36 947.23 943.38 931.94 9/30/05 945.06 945.78 966.44 941.94 948.42 956.74 943.91 929.29 947.38 947.25 943.42 931.90 10/7/05 945.68 946.20 966.74 942.34 948.76 957.32 945.01 929.99 walk flooded 947.83 under h2o 932.30 10/14/05 945.45 945.70 966.52 942.42 948.24 957.28 no gauge 929.85 947.68 947.55 943.52 931.98 10/21/05 945.18 945.72 966.22 942.36 948.34 957.22 no gauge 929.69 947.42 947.59 943.32 931.90 10/26/05 945.06 945.70 966.22 942.34 948.30 957.18 no gauge 929.57 947.36 947.41 943.26 931.82
278 Table C4 2005 Discharges and Loads Flow-Weighted Mean Load Concentration (pounds)
Contributing Average Watershed Flow Station Creek Area (sq. mi.) (cfs) TP (ppb) SRP (ppb) TN (ppm) TSS (ppm) TP SRP TN TSS
CCH01 Christmas Creek 1.17 0.16 39 2 0.8 4.4 12 1 250 1376 CCL01 Classen Creek 1.55 1.37 324 101 1.7 87 875 272 4588 234010 CDU01 Dutch Creek 2.95 0.90 114 42 1.3 15 202 74 2327 26222 CFO01 Forest Creek 1.00 0.42 400 185 1.4 21 334 155 1165 17558 CGL01 Gleason Outlet 1.50 1.10 54 6 1.0 3 118 13 2083 6538 CGL03 Gleason Inlet 2.56 0.86 273 66 1.7 24 463 112 2810 40740 CHI01 Halsted Inlet N 0.82 0.11 155 28 1.9 1 35 6 427 224 CHI02 Halsted Inlet S 0.57 0.19 298 163 1.3 2 112 62 480 602 CLA01 Langdon Creek 1.65 0.53 128 3 1.8 15 134 3 1903 15280 CLO03 Long Creek, Brown Rd 1.56 4.90 253 54 1.6 11 2446 520 15676 103728 CLO03 Long Inlet 6.06 1.27 244 91 1.7 14 612 228 4289 34001 CLO01 Long Outlet 4.65 3.72 124 6 1.8 23 910 46 12934 165055 CPA03 Painter, Deb Dr 4.99 2.51 262 125 1.7 7 1296 618 8448 34555 CPA02 Painter, CR 6 2.20 2.86 344 149 2.2 12 1940 840 12467 68756 CPA04 Painter, CR 26 5.21 3.72 265 111 1.6 7 1945 813 11664 48774 CPA06 Painter, Painter Dr. 0.35 2.32 308 139 1.8 10 1410 638 8029 44963 CPA01 Painter, W Br 0.27 6.33 372 146 1.8 21 4644 1826 22758 264237 CPA05 Painter, 110 0.49 5.26 346 128 1.7 32 3585 1323 17408 335802 CPE01 Peavey Cr. 0.88 0.56 233 84 1.6 4 258 93 1736 4944 CSI05 Six Mile, Hwy 5 6.29 0.96 132 27 1.2 7 250 51 2303 12388 CSI04 Six Mile, Steiger 1.52 0.31 86 24 1.2 1 52 15 720 617 CSI03 Six Mile, Sunny 3.26 0.32 138 33 1.4 7 86 21 876 4615 CSI01 Six Mile, Lunsten 4.45 3.25 125 24 1.7 8 799 153 10930 49769 CSI03 Six Mile, Hwy 7 8.40 3.01 179 59 2.1 23 1057 59 12107 133278 CST01 Stubbs Inlet 0.79 0.41 671 325 2.7 52 537 260 2142 41635 CMW01 Minnewashta Cr. 6.24 0.86 41 0 0.8 3 69 0 1439 5007
279
Table C4 Continued
Flow-Weighted Mean Concentration Load (pounds) Contributing Watershed Area Average Flow Station Minnehaha Creek Site (sq. mi.) (cfs) TP (ppb) SRP (ppb) TN (ppm) TSS (ppm) TP SRP TN TSS
CMH07 Grays Bay Dam 123.23 37.89 24 1 0.7 0.2 1759 59 54064 12595 CMH19 I-494 5.46 42.58 35 2 0.7 2 2930 197 60705 181588 CMH02 W 34th St 8.01 45.36 51 9 0.8 5 4556 776 71107 469119 CMH11 Excelsior Blvd 3.12 45.64 68 12 0.9 11 6131 1073 76512 1009968 CMH03 Browndale Dam 2.23 25.11 61 7 0.8 5 3038 361 40764 249333 CMH04 56th 0.80 41.89 57 12 0.8 5 4715 1014 68226 431509 CMH12 Upton Ave 1.41 47.04 72 14 0.8 9 6628 1295 78173 800709 CMH05 Chicago Ave 18.38 46.57 79 17 0.9 12 7258 1546 82464 1109559 CMH17 32nd Ave 7.50 40.29 78 12 0.9 6 6218 962 71534 512613 CHM06 Hwy 55 0.35 55.42 69 13 0.9 6 7497 1394 100606 623354
280 Table C5 E. coli (CFU/100 mL) in 2005
Date CSI02 CPA01 CMH07 CMH02 CMH11 CMH03 CMH04 CMH12 CMH05 CMH17 CMH06 3-Jun 52 62 22 80, 80 148 106 64 116 260 66 170 9-Jun 118 350 7 72 300 560 1000 1000 1100 600 600 17-Jun 48 68 7 48 88 84 86 120 130 66, 92 92 23-Jun 118 112 3 66 110 98 122 122 220 153, 130 165 8-Jul 100 72 <2 62 150 58 100 88 170 82, 68 84 14-Jul 42 88 28, 44 94 118 94 43 198 210 50 116 22-Jul 15 200 3 86 108 148 190 160 480 116, 126 130 28-Jul 72 160, 170 <2 100 170 220 240 240 310 78 170 4-Aug 130 368 13 110 570 2300 510 500 1500 1900 1300, 1500 11-Aug 12 240 <2 150 430 150 180 360, 370 640 220 460 18-Aug 160 4100 7, 20 540 1100 110 4000 7600 6200 970 500 25-Aug 86 230 15, 23 270 570 40 380 310 480 180 460 1-Sep 54 140 22 1100, 1200 560 98 370 350 510 350 300 8-Sep 73, 10 270 64 460 940 410 460 530 800 480 510 15-Sep 55 260 <2 280, 300 450 370 490 340 310 38000 400 22-Sep 150 150 27 920 2000 1200, 1200 1200 1000 710 1200 2000 29-Sep 73 120 9, 9 170 300 310 280 350 260 230 390 5-Oct 640, 640 18000 180 9800 13000 12000 11000 11000 9500 28000 7900 12-Oct 190 230 <9 73 150 210, 170 220 190 170 91 220 20-Oct 9 340 150 73 120 9 170 480 120 100 180, 200 26-Oct 100 82 <9 27 100 <9 45 100 45 36 38 2-Nov 2 92 22 32, 22 48 66 74 84 86 226 180
281 Appendix
D – Acronyms & Glossary of Water Quality Terms
303 (d) List Minnesota Pollution Control Agencies List of Impaired Waters under the Clean Water Act BMPs best management practices CFU/100 mL colony forming units per 100 milliliters DO dissolved oxygen lbs pounds MCWD Minnehaha Creek Watershed District mg/L milligrams per liter, parts per million µg/L micrograms per liter, parts per billion
MN 7050 Minnesota State Statutes MPCA Minnesota Pollution Control Agency MPRB Minneapolis Park and Recreation Board NCHF North Central Hardwood Forest (Ecoregion) NGVD National Geodesic Vertical Datum NOHW normal ordinary high water (level) NWS National Weather Service SRP soluble reactive phosphorus STORET short for STOrage and RETrieval, a repository for water quality, biological, and physical data TN total nitrogen TP total phosphorus TRPD Three Rivers Park District (formerly SHRPD, Suburban Hennepin Park District) TSI Trophic Status Index TSS total suspended solids
Water quality parameters commonly monitored by the District, either routinely or for special studies, are briefly described in this section. The parameters provide various indicators of water quality at the locations where samples were collected.
Calcium, Magnesium, and Total Hardness Hardness in water is produced by calcium (Ca) and magnesium (Mg) ions. It is primarily of concern in water supplies because excessive levels (greater than 200-300 milligrams per liter) cause high soap consumption and objectionable scale in pipes. Hardness of 60-120 milligrams per liter is considered moderate. Hardness in lakes is also a very broad indicator of algal and fish productivity. "Hard-water lakes" are usually more productive than "soft-water lakes." Hardness values are conventionally reported as CaCO3 concentrations. Total hardness equals the sum of Ca plus Mg hardness.
Chloride Chloride (Cl-) measurements are performed to detect the influx of road salts from winter deicing procedures. Typically, lakes and streams with heavy groundwater inflow would have low chloride concentrations.
Chlorophyll a Chlorophyll a concentration is a proxy for phytoplankton (algae) biomass in the water. All algae contain chlorophyll a, usually at levels that are a few percent of their cellular biomass. Hence high chlorophyll a concentrations indicate high levels of algal biomass. This
282 Appendix analysis is much less tedious and costly than algal identification and enumeration methods. The chlorophyll a concentrations can be used to classify the trophic status of a lake. Concentrations less than 7 micrograms per liter (parts per billion) are generally desirable in lakes.
Dissolved Oxygen Dissolved oxygen (DO) is the uncombined molecular oxygen (O2) that is in solution in water. DO concentrations are increased due to algal/macrophyte photosynthesis and exchange with atmospheric oxygen (which is enhanced in the presence of wave action and/or turbulence). DO concentrations can decrease due to biological respiration (both plants and animals) and nitrification (a bacterial process). DO concentrations provide insight on the oxygen demand exerted on the water column, indicate available habitat for fish populations, and indicate what conditions may exist for, as well as what processes are involved in the breakdown of organic material. DO concentrations greater than 5 to 6 milligrams per liter are generally desirable in surface waters. However, nutrient-rich lakes may become DO-depleted in their bottom waters during summer stratification.
Ecoregion Natural differences in lake water quality occur across Minnesota’s widely varied geographical and environmental regions. The geomorphic and chemical properties of lakes vary across these regions. These differences are accounted for by dividing the regions into seven different ecoregions. Each ecoregion contains a geographically distinct collection of plants, animals, natural communities and environmental conditions. The District is located entirely in the North Central Hardwood Forest ecoregion.
Escherichia coli (E. coli) E. coli is a member of the fecal coliform group of bacteria. For Class 2B waters (Fisheries and Direct Contact Recreation), the Minnesota Pollution Control Agency allowable standard for E. coli is 1260 organisms (acute standard) and 126 organisms (30-day standard, geometric mean) per 100 milliliters.
Eutrophication This process represents an increase in biological productivity over time. A lake will naturally fill in due to sedimentation of decaying organic matter (plants, animals) and incoming stream sediments. This can take hundreds of years. However, cultural eutrophication can create conditions in which water bodies receive excess nutrients that stimulate excessive algae blooms, attached algae, and nuisance plants on the order of decades. After the plants die, their decay consumes oxygen in the lake causing a lack of oxygen which can impair other in-lake biota. Fertilizers, erosion of soil-containing nutrients; and sewage treatment plant discharges can all add to eutrophication.
Internal Loading Release of phosphorus from lake sediments during oxygen-depleted conditions. Depending on the overall nutrient budget for a lake, internal loading can be a major source of in-lake phosphorus annually and can contribute to eutrophication.
Iron Iron (Fe) is a minor nutrient for algae and other plants, but its major importance in lake waters is in relation to phosphorus and oxygen. In lake sediments, iron combines with phosphorus and tends to prevent the release of phosphorus into the overlying water. However, the release of both iron and phosphorus occurs readily when dissolved oxygen is depleted in the lake bottom water. Therefore, elevated iron concentrations in lakes often signal an "internal source" of phosphorus -- i.e., release from the sediments.
283 Appendix
Macrophyte A relatively large aquatic plant. Examples include floating-leaved (e.g., water lilies), submerged (e.g., coontail), and emergent (e.g., cattail).
Nitrogen Nitrogen (N) is a chemical element occurring in several forms. Primary inorganic forms are ammonia and nitrate. Ammonia-N is the total of all N in the form of either dissolved + - gas (NH3) or ammonium ion (NH4 ). Nitrate-N is nitrogen dissolved as nitrate ion (NO3 ). A less - abundant inorganic form is the nitrite ion (NO2 ), which occurs in reducing environments (low DO). Elevated nitrate levels usually indicate bacterial nitrification, which is typical of sewage- contaminated waters. Total Kjeldahl-N (TKN) measures the total of all N in the form of either organic-N or ammonia-N. Organic-N includes particulate forms (such as cell matter from algae or bacteria, and sewage solids) and dissolved forms (such as proteins and peptides). Algae and other plants require N as a primary nutrient. Ammonia and nitrate N are the chief forms susceptible to algal and plant uptake, but certain dissolved organic forms can also be assimilated. Measurement of N provides insight into the total potential for algal and plant growth. pH and Alkalinity pH measures the concentration of hydrogen ion (H+) in water. The negative of the pH value is the common logarithm of the molar concentration of hydrogen ion. Hydrogen ions, always present in water, impart acidity. When the pH value is 7.0, the condition is called neutrality and the concentrations of hydrogen ion and hydroxide ion (OH-) are equal. When the pH value is less than 7.0, the concentration of hydrogen ion exceeds that of hydroxide, and the water is acidic. When the pH is greater than 7.0, the concentration of hydroxide is greater, and the water is basic or alkaline. Surface waters in the metropolitan area are usually basic (pH greater than 7.0), due to plant and algal photosynthesis and geologic characteristics. Alkalinity indirectly measures the concentration of chemicals able to combine with hydrogen ions, called - bases or alkalis. In natural waters, virtually all alkalinity is due to bicarbonate ion (HCO3 ), -2 carbonate ion (CO3 ), and hydroxide ion. Total alkalinity measures all forms and is reported as CaCO3 is typical for surface waters in the metropolitan area.
Phosphorus Phosphorus (P) is a chemical element found in waters most commonly in one of several forms of phosphate (PO4). The inorganic dissolved form is orthophosphate ion. Orthophosphate (estimated analytically as soluble reactive P or SRP) is an essential nutrient for photosynthesis; not only do plants convert this form into organic cell matter, but P is also a crucial component of the energy-transfer molecule ATP. Organic P includes particulate forms such as living or dead cell matter and sewage solids, and several forms derived from them. Mineralization of organic matter by bacteria and fungi converts organic P into orthophosphate. Total P (TP) measures the sum of all forms. Settling of solids and of algal and bacterial cell matter, as well as uptake by rooted plants, removes P from the water. Sediment P can re-enter the water column as a result of chemical, biological, and physical processes. TP measurements show the maximum potential for algal growth and can be used to classify the trophic status of a lake. Orthophosphorus measurements show the amount of P immediately available for plant life. Concentrations of TP less than 0.02 milligram per liter (part per million) are generally desirable in lakes.
284 Appendix
Secchi Disk Transparency The Secchi disc provides a physical measurement of water clarity by observation of the disc at the maximum visual depth in the water column. Secchi transparency is an indicator of algal population density and turbidity, and can be utilized to classify the trophic status of the lake. Secchi disc depths greater than three meters (10 feet) are generally desirable in lakes.
Specific Conductance Specific conductance is a measure of the water's ability to act as a conductor. High conductivity is an indicator of low water quality and implies high concentrations of chlorides or other dissolved solids.
Sulfate Sulfate is a minor nutrient required by algae and other plants. Its concentration in lakes varies geographically and correlates with the distribution of rooted aquatic plant species in Minnesota. Sulfate concentrations below 10 milligrams per liter are typical in the metropolitan area.
Temperature Profile In lakes, the temperature profile with depth determines the extent to which surface and bottom waters are mixed. A large difference (stratification) indicates little mixing, while a small difference or no difference generally shows thorough mixing throughout all depths. Water temperature also determines the DO saturation level, the concentration that would occur in the absence of all biological activity.
Trophic State The trophic state of a lake is a qualitative description of biological productivity. Common terms include eutrophic (high productivity, low water clarity, high chlorophyll a and P concentrations), mesotrophic (intermediate productivity, water clarity, chlorophyll a, and P concentrations), and oligotrophic (low productivity, high water clarity, low chlorophyll a and P concentrations). Most lakes in the District fall into the first two categories.
Trophic State Index (TSI) The trophic state index (TSI) is a numerical measure of the trophic status, or productivity level, of a lake. Higher concentrations of nutrients in a lake allow increased plant and algae growth, which then decreases the lake transparency. Therefore, Secchi depth, phosphorus concentration, and chlorophyll a concentration are used to categorize lakes for TSI. The TSI scale ranges from 1 to 100, with lower values corresponding to higher lake water quality.
Water Quality Grades (Lake Report Card Grades) Water quality grades are based on standards established by the Metropolitan Council. The standards give a range to each letter grade for the May through September averages of surface total phosphorus concentration, surface chlorophyll a concentration, and Secchi depth. The overall lake water quality grade is the average of the grades for each parameter. Other indicators of lake condition such as aquatic plant growth or invasive species are not factored into these grades. The TSI, which measures the productivity level of a lake or degree of eutrophication, is also calculated. High TSI values correspond with poorer water quality.
285 Appendix
References
Heiskary, S.A., and C. B. Wilson, 1990. Minnesota Lake Water Quality Assessment Report, 2nd edition. Minnesota Pollution Control Agency.
McCollor and Heiskary. 1993. Selected Water Quality Characteristics of Minimally Impacted Streams from Minnesota’s Seven Ecoregions. Minnesota Pollution Control Agency Water Quality Division.
Minnehaha Creek Watershed District, 2004. Minnehaha Creek Stream Assessment.
Minnehaha Creek Watershed District, December 2003. Fluvial Geomorphic Assessment Report Prepared by Wenck Associates, Inc. and Interfluv.
Minnehaha Creek Watershed District, July 2003. MCWD Pathogen Report Prepared by Wenck Associates, Inc.
Minnehaha Creek Watershed District, March 2005. 2004Hydrological Data Report. Prepared by Lorin Hatch, MCWD Water Quality Specialist.
Minnehaha Creek Watershed District, 1999. Headwaters Control Structure Management Policy and Operating Procedures, March 1, 2000 - March 1, 2001.
Minnehaha Creek Watershed District, 1997. Water Resources Management Plan Prepared by Wenck Associates, Inc.
Minnesota Pollution Control Agency, January 2004. Guidance Manual for Assessing the Quality of Minnesota Surface Waters for the Determination of Impairment, Prepared by the Minnesota Pollution Control Agency.
Minnesota Pollution Control Agency, December 2003. Draft MPCA 2004 303(d) List of Impaired Waters, Prepared by the Minnesota Pollution Control Agency.
United States Department of Agriculture, Soil Conservation Service. Hydrology Guide for Minnesota.
286 Appendix
Index of Lake and Stream Report Cards
Lake Site Page MTKA Bay Site Page Creek Site Page Calhoun LCA01 50 Carsons LCS01 102 Christmas Lake Cr. CCH01 155 Cedar LCE01 52 Cooks LCO01 104 Classen Lake Creek CCL01 149 Christmas LCH01 153 Crystal LCR01 106 Dutch Lake Creek CDU01 212 Diamond LDI01 54 East Upper LEU01 108 Forest Lake Creek CFO01 150a Dutch LDU01 210 Forest Lake LFO01 110 Gleason Lake Creek CGL01 245 Gleason LGL01 241 Grays LGB01 112 Gleason Lake Creek CGL03 243 Harriet LHA01 56 Halstead LHL01 114 Halstead Inlet North CHI01 150c Hiawatha LHI01 58 Harrisons LHR01 116 Halstead Inlet South CHI02 150e Isles LIS01 60 Jennings LJE01 118 Langdon Lake Cr. CLA01 207 Langdon LLA01 204 Lafayette LLF01 120 Long Lake Creek CLO01 207 Long LLO01 231 LL North LMU01 122 Long Lake Creek CLO02 237 Minnewashta LMW01 163 LL South LGI01 124 Long Lake Creek CLO03 233 Nokomis LNK01 62 Maxwell LMA01 126 Minnehaha Creek CMH02 70 Parley LPR01 185 N. Arm LNR01 128 Minnehaha Creek CMH03 74 Pierson LPI01 179 Peavey Lk. LPE01 130 Minnehaha Creek CMH04 76 Powderhorn LPO01 64 Priests LPT01 132 Minnehaha Creek CMH05 80 Schutz LSC01 171 Shavers LSH01 134 Minnehaha Creek CMH06 84 St. Joes LSJ01 162 Smithtown LSM01 135 Minnehaha Creek CMH07 66 Steiger LST01 189 Spring Park LSP02 137 Minnehaha Creek CMH11 72 Tamarack LTA01 160 St. Albans LAL01 139 Minnehaha Creek CMH12 78 Virginia LVI01 165 Stubbs LSU03 141 Minnehaha Creek CMH17 82 Wasserman LWS01 181 Wayzata LWA01 143 Minnehaha Creek CMH19 68 West Auburn LAU01 183 W. Arm LWE01 145 Minnewashta Creek CMW01 167 Zumbra LZU01 187 W. Upper LCI01 147 Painter Creek CPA01 224 Painter Creek CPA02 218 Painter Creek CPA03 216 Painter Creek CPA04 220 Painter Creek CPA05 226 Painter Creek CPA06 222 Peavey Creek CPE01 150g Six Mile Creek CSI01 197 Six Mile Creek CSI02 199 Six Mile Creek CSI03 195 Six Mile Creek CSI04 193 Six Mile Creek CSI05 191 Stubbs Bay Inlet CST01 150i
287