Minneapolis Park & Recreation Board
WATER RESOURCES REPORT 2017
Environmental Management
2017 WATER RESOURCES REPORT
Prepared by:
Minneapolis Park & Recreation Board Environmental Management 3800 Bryant Avenue South Minneapolis, MN 55409-1029 612.230.6400 www.minneapolisparks.org
December 2018
Funding provided by:
Minneapolis Park & Recreation Board City of Minneapolis Public Works
Copyright © 2018 by the Minneapolis Park & Recreation Board Material may be quoted with attribution. TABLE OF CONTENTS Page
Abbreviations ...... i Executive Summary ...... iv 1. Monitoring Program Overview ...... 1-1 2. Birch Pond ...... 2-1 3. Brownie Lake ...... 3-1 4. Calhoun / Bde Maka Ska ...... 4-1 5. Cedar Lake ...... 5-1 6. Diamond Lake ...... 6-1 7. Grass Lake ...... 7-1 8. Lake Harriet ...... 8-1 9. Lake Hiawatha ...... 9-1 10. Lake of the Isles ...... 10-1 11. Loring Pond ...... 11-1 12. Lake Nokomis ...... 12-1 13. Powderhorn Lake ...... 13-1 14. Ryan Lake ...... 14-1 15. Spring Lake ...... 15-1 16. Wirth Lake ...... 16-1 17. Comparisons Among Lakes ...... 17-1 18. Public Beach Monitoring ...... 18-1 19. Webber NSP ...... 19-1 20. Aquatic Plant Management ...... 20-1 21. Wetland Health Evaluation Program (WHEP) ...... 21-1 22. National Pollutant Discharge Elimination System (NPDES) Monitoring ...... 22-1 23. Lowry Sand Filter ...... 23-1 24. Winter Infiltration Basin ...... 24-1 25. 24th & Elm Infiltration Chamber ...... 25-1 26. Golf Course Wetland Monitoring ...... 26-1 27. Climatological Summary ...... 27-1 28. Water Quality Education ...... 28-1 29. Quality Assurance Assessment Report ...... 29-1 30. Additional Sources of Water Quality Information ...... 30-1 31. References ...... 31-1 Appendix A – Box and Whisker Plot Record ...... A-1 Appendix B – Lake Monitoring Data 2017 ...... B-1
2017 Water Resources Report – Minneapolis Park & Recreation Board LIST OF ABBREVIATIONS
% DO Percent Dissolved Oxygen µg Microgram µm Micrometer µmhos Micromhos µS Micro Siemens ACSP Audubon Cooperative Sanctuary Program Al Aluminum Alk Alkalinity alum Aluminum sulfate As Arsenic BCWMC Bassett's Creek Watershed Management Commission BMP Best Management Practices C Celsius CAMP Citizen Assisted Monitoring Program cBOD 5 day Carbonaceous Biochemical Oxygen Demand Cd Cadmium CDS Continuous Deflective Separation cf Cubic foot cfs Cubic foot per second cfu Colony forming unit chl-a Chlorophyll-a Cl Chloride cm Centimeter COD Chemical Oxygen Demand Cond Conductivity Cu Copper CV Coefficient of Variance CWP Center for Watershed Protection DO Dissolved Oxygen E. coli Escherichia coli ERA Environmental Resource Associates EWM Eurasian watermilfoil F Fahrenheit F. coli Fecal Coliform Fe Iron FIN Fishing in the Neighborhood Program ft Foot GIS Geographical Information System GPS Global Positioning System Hard Hardness, Total as CaCO3 HPLC High Pressure Liquid Chromatography IBI Index of Biological Integrity
2017 Water Resources Report – Minneapolis Park & Recreation Board Page i ID Insufficient Data in/hr Inches per hour IRI Instrumental Research, Inc. IWMI Interagency Water Monitoring Initiative kg Kilogram L Liter LAURI Lake Aesthetic and User Recreation Index m Meter MAX Maximum MCES Metropolitan Council Environmental Services MCWD Minnehaha Creek Watershed District MDL Minimum Detection Limit MDNR Minnesota Department of Natural Resources mg Milligram MIN Minimum mL Milliliter Mn Manganese MnDOT Minnesota Department of Transportation MPCA Minnesota Pollution Control Agency Mpls Minneapolis MPN Most probable number MPRB Minneapolis Park and Recreation Board MPW Minneapolis Public Works msl Mean sea level MRL Minimum Reporting Limit N/A Not Applicable n/c Not Collected NA No Data Available NB No Swimming Beach NCHF North Central Hardwood Forests ND Not Detected NDC National Data Center NH3 Ammonia, Un-ionized as N Ni Nickel NO3/NO2 Nitrate+Nitrite NOAA National Oceanic and Atmospheric Administration NOx Nitrite+Nitrate, Total as N NPDES National Pollutant Discharge Elimination Systems NS Not Sampled NTU Nephelometric Turbidity Unit NURP Nationwide Urban Runoff Program NWS National Weather Service OHW Ordinary High Water Level OTP Ortho Phosphorus P Phosphorus
2017 Water Resources Report – Minneapolis Park & Recreation Board Page ii Pb Lead PE Performance Evaluation PFC Perflorinated Chemical PFOA Perflurorooctanoic Acid PFOS Perfluorooctane Sulfonate QA Quality Assurance QAPP Quality Assurance Project Plan QC Quality Control RL Reporting Limit RPD Relative Percent Difference s Second Si Reactive Silica Sp. Cond. Specific Conductivity SRP Soluble Reactive Phosphorus STDEV Standard Deviation TCMA Twin Cities Metropolitan Area TDP Total Dissolved Phosphorus TDS Total Dissolved Solids TKN Total Kjeldahl Nitrogen TMDL Total Maximum Daily Load TN Total Nitrogen TOC Total Organic Carbon TP Total Phosphorus TRPD Three Rivers Park District TSI Trophic State Index TSS Total Suspended Solids US EPA US Environmental Protection Agency USGS US Geological Survey VSS Volatile Suspended Solids WHEP Wetland Health Evaluation Program WOMP Watershed Outlet Monitoring Program WPA Works Progress Administration Zn Zinc
2017 Water Resources Report – Minneapolis Park & Recreation Board Page iii EXECUTIVE SUMMARY
As part of its stewardship of the lakes and other water bodies within the City of Minneapolis, the Minneapolis Park and Recreation Board (MPRB) monitors lakes, streams, and stormwater flows for contaminants and other water quality indicators. This report presents the results for the 2017 monitoring season. The report is primarily based on data collected by the MPRB Environmental Management Section.
In 2017, MPRB water resources scientists monitored 11 of the city’s most heavily used lakes: Bde Maka Ska, Cedar, Diamond, Harriet, Hiawatha, Isles, Loring, Nokomis, Powderhorn, Spring, and Wirth Lakes. Historical data from 1991-2017 are used to calculate trophic state index (TSI) trends and estimate the trophic status for each lake. Diamond and Grass Lakes were not included in this analysis since TSI scores are only appropriate for deeper lake systems and there are no water clarity measurements available for these lakes. Based on the trophic state report for 2017 the following observations are made:
Lakes with Improving Water Quality • Bde Maka Ska Indicators • Lake Harriet • Lake Nokomis • Wirth Lake Lakes with Stable Trends • Brownie Lake • Cedar Lake • Lake Hiawatha • Lake of the Isles • Loring Pond • Powderhorn Lake • Spring Lake Lakes with Declining Water Quality • No lakes with declining trend Indicators
WATER QUALITY HIGHLIGHTS
MPRB and the Friends of Lake Nokomis worked in partnership on early detection monitoring for invasive zebra mussels in Minneapolis lakes. A single zebra mussel was found by a MPRB Water Quality staff member in Lake Harriet in September 2017. The Minnesota Department of Natural Resources (DNR) confirmed the find and has added Lake Harriet to the Infested Waters List for zebra mussels. Following the discovery, MPRB staff worked with the DNR, the Minnehaha Creek Watershed District (MCWD), and contractors to conduct 67 hours of shoreline, snorkel, and scuba surveys around the lake. The search focused from the shoreline to approximately the 15-foot depth contour near the boat launch, the sailboat buoy field, and other areas with suitable habitat around the lake. No additional zebra mussels were found during the search effort. Additionally, two tows for veligers, planktonic larvae of zebra mussels, were conducted, one near the boat launch and one near the outlet. Veligers were not found in either tow. Continued searching will take place at Lake Harriet in the future to track the population of the invasive mussel in the lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page iv Zebra mussel sampling plates were deployed at Bde Maka Ska, Harriet, Hiawatha, Nokomis, and Wirth. Additional shoreline assessments were completed at Bde Maka Ska, Cedar, Isles, Nokomis, and Wirth. The only zebra mussels found on a sampling plate in 2017 was at Lake Hiawatha. No zebra mussels were found in Bde Maka Ska, Cedar, Isles, Nokomis, or Wirth in 2017.
The natural swimming pool at Webber Park, the first of its kind in North America, was open for the second full year in 2017. Since the water quality in the pool depends on the ecological conditions in the system, MPRB Environmental Management and Maintenance staff monitors the physical, chemical and biological parameters. A total of 95% of bacteria (Escherichia coli, Enterococci, and Pseudomonas aeruginosa) samples met water quality standards for natural swimming pools set by the German FLL, with the pool only closing due to elevated bacteria levels for one week in mid-August.
The MPRB monitored 12 public beaches for Escherichia coli (E. coli, as recommended by the US Environmental Protection Agency). These bacteria are used as indicators of pathogens in water. Most beaches had low season-long geometric means except Lake Hiawatha. Lake Hiawatha Beach closed due to exceeding the 30-day geometric mean standard of 126 MPN/100 mL in late-August 2017. Migrating waterfowl are thought to have contributed to the high bacteria concentrations at the beach. The MPCA single sample limit of 1,260 E. coli per 100 mL of water was exceeded twice at Hiawatha and once at Wirth Lake Beach during the 2017 beach season.
The water quality in Bde Maka Ska, Lake Harriet, and Wirth Lake remain above average for lakes in urban settings. Indicators show better water quality in 2017 than the early 1990s. All three lakes currently meet Minnesota Pollution Control Agency (MPCA) guidelines for phosphorus, chlorophyll- a, and Secchi depth. Continued monitoring is assisting in developing the next generation plans for Bde Maka Ska and Lake Harriet.
Lake Nokomis experienced higher algal concentrations for the second straight year in 2017, especially in the fall, but has seen an improvement in water quality in the past few years following a MCWD-led biomanipulation project. The MPRB was awarded funding for a project to study Lake Nokomis’ carp population and to develop long-term carp management practices that improve water quality. 2017 work focused on assessing carp population movement and planning removal techniques.
Powderhorn Lake received its fourteenth barley straw treatment in 2017; however, a blue green algal bloom in the summer impacted the aesthetics and clarity of the lake for the fourth straight year.
The TSI value for Cedar Lake showed improvement following restoration efforts through the late- 1990s, had a slow decline in the 2000s, and has remained stable since. An increase in chlorophyll-a and a decrease in water clarity in 2017 led to the lowest TSI score in Cedar Lake since the mid-1990s.
In 2017, Lake Hiawatha met the site specific standards set by the MPCA for Secchi depth, chlorophyll-a, and total phosphorus. The water quality in Lake Hiawatha is controlled by the large inflow from Minnehaha Creek, with drought years leading to poorer water quality. Above average spring and summer precipitation the last few years has led to the lowest TSI scores observed in the lake since monitoring began in the early-1990s.
AES continued the control of cattails in Loring Pond by pulling, cutting, and select spot herbicide treatments in 2017. Additional maintenance of the 2016 and 2013 native aquatic emergent plantings in the South Bay was also performed. In August, MPRB staff amended the contract with AES to remove the upland buffer planting from the contract due to public concerns over herbicide treatments in parks. The amendment to the contract included an additional herbicide treatment of the North Bay floating cattail mat, which was done in September 2017. The amendment also included removal of the
2017 Water Resources Report – Minneapolis Park & Recreation Board Page v floating cattail mat stems when ice was on the lake in the winter of 2017-2018. Remaining contract funds will be used to control cattails and maintain the emergent plantings until the contract end in December 2018.
Eurasian water milfoil harvesting was carried out on Bde Maka Ska, Cedar, Harriet, Nokomis, Lake of the Isles, and Wirth Lakes in 2017 to allow for improved recreational access. SCUBA divers were contracted to hand-harvest aquatic plants at Lake Nokomis and Wirth Lake in the beach areas.
The 2017 annual mean temperature was 48.5° F, which was 2.4° F above normal. Three months had below normal temperature and nine months had above normal temperatures. The warmest month of the year was July and the coolest month of the year was December. It should be noted that February had the largest temperature deviation from normal at 10.4°F. The average monthly January and February temperatures were above normal with the remaining months near normal.
The 2017 annual recorded precipitation total was 32.36 inches, which was 0.14 inches above normal. Seven months had below normal precipitation and five months had above normal precipitation. The wettest month of the year was August and the driest month of the year was November. The average monthly precipitation shows some significant monthly deviations from normal: April, May, August, and October were wet; and March, September, and November were dry.
The MPRB monitors storm sewers within Minneapolis to comply with the federal National Pollutant Discharge Elimination System (NPDES) permit. The purpose of this monitoring is to characterize the impacts of different land use stormwater discharges and to review the effectiveness of treatment best management practices (BMPs). BMPs include procedures and structures designed to help reduce and capture pollutants in stormwater runoff. The results of the 2017 land use and BMP stormwater data were typical for stormwater.
In 2017, monitoring was continued with multiple BMP projects. These included:
1) 24th & Elm Infiltration Chamber. 2) Winter Infiltration Basin. 3) Lowry Sand Filter.
Monitoring partners for 2017 included: The Friends of Lake Nokomis, Minneapolis Public Works, the Minnehaha Creek Watershed District, Minnesota Pollution Control Agency, and Minnesota Department of Natural Resources.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page vi 1. MONITORING PROGRAM OVERVIEW:1991-2017
LAKE MONITORING
Background
The Environmental Management Section of the Minneapolis Park and Recreation Board (MPRB) implemented a lake water quality monitoring program in 1991 as part of a diagnostic study for the Chain of Lakes Clean Water Partnership. The Chain of Lakes includes Brownie, Cedar, Isles, Bde Maka Ska, and Harriet. The monitoring program was expanded in 1992 to include Hiawatha, Nokomis, Diamond, Powderhorn, Loring, and Wirth Lakes. Monitoring at Spring Lake was added on a limited basis in 1993 and Grass Lake was added in 2002. Currently, only ice conditions are monitored at Birch and Ryan Lakes. Ryan Lake is occasionally monitored by the Met Council’s CAMP program. Figure 1-1 shows the location of waterbodies in Minneapolis. For purposes of this overview, these 15 lakes will be collectively referred to as the Minneapolis lakes.
The objectives of the MPRB lake monitoring program are to:
1. Protect public health. 2. Establish a database for tracking water quality trends. 3. Quantify and interpret both immediate and long-term changes in water quality. 4. Provide water quality information to develop responsible water quality goals. 5. Provide a basis for water quality improvement projects. 6. Evaluate the effectiveness of implemented best management practices such as ponds and grit chambers.
The intent of this overview is to provide a description of the MPRB lakes monitoring program schedule and methods.
The watersheds of the 15 Minneapolis lakes span the cities of Minneapolis, St. Louis Park, Richfield, Golden Valley, Robbinsdale, Brooklyn Center, and Edina. Residential housing is the predominant land use within all the watersheds although industrial and commercial land uses are significant in several areas. The Loring Pond watershed is predominantly parkland. All the Minneapolis lakes’ watersheds are considered fully developed and little change in land use is projected.
The geology of the lakes and watersheds consist of Paleozoic bedrock that has been altered by fluvial processes and covered with glacial till. Area bedrock is generally concealed under 200–400 feet of unconsolidated deposits. The bedrock surface is composed of plateaus of limestone and dolomite penetrated by a system of dendritic preglacial river valleys. These river valleys were filled by a combination of fluvial sediment and late Wisconsin glacial drift. Each subsequent glacial advance stripped the landscape of overburden and filled the preglacial and interglacial valleys with drift. The last glacial episode resulted in the formation of most of the lakes in Minneapolis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-1
Figure 1-1. Location of waterbodies in Minneapolis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-2 The glacial ice sheet deposited large ice blocks at its margin as it retreated. Ice blocks that were deposited in a north-south tending pre-glacial (or interglacial) valley led to the formation of the Chain of Lakes. Lake Nokomis, Lake Hiawatha, and Powderhorn Lake formed as a result of a similar series of events in another preglacial valley (Zumberge, 1952; Balaban, 1989).
Nearly all the Minneapolis lakes were physically altered by dredging in the early 1900s (Pulscher, 1997). The Minneapolis lakes currently represent a wide range of morphometric characteristics (see Table 1-1) including deep dimictic lakes (Bde Maka Ska, Cedar, Harriet, and Wirth), polymictic lakes (Hiawatha and Nokomis), protected meromictic lakes (Brownie and Spring), shallow lakes (Isles, Loring, and Powderhorn), and shallow wetland systems (Diamond and Grass).
Table 1-1. Minneapolis lakes morphometric data.
Surface Mean Max Watershed Residence Area Depth Depth % Volume Area Watershed:Lake Time Lake (acres) (m) (m) Littoral* (m3) (acres) Area (ratio) (years) Brownie 18 6.8 15.2 67% 4.98x105 369 20.5 2.0 Bde Maka Ska 421 10.6 27.4 31% 1.80x107 2,992 7.1 4.2 Cedar 170 6.1 15.5 37% 4.26x106 1,956 11.5 2.7 Diamond 41 0.9† 2.1† 100% 7.15x104 669‡ 16.3 NA Grass 27 0.6 1.5 NA NA 386 14.3 NA Harriet 353 8.7 25.0 25% 1.25x107 1,139 3.2 3.4 Hiawatha 54 4.1 7.0 26% 8.95x105 115,840 2145 0.003 Isles 103 2.7 9.4 89% 1.11x106 735 7.1 0.6 Loring 8 1.5 5.3 NA 4.88x104 24 3.0 NA Nokomis 204 4.3 10.1 51% 3.54x106 869 4.3 4.0‡ Powderhorn 11 1.2 6.1 99% 9.04x104 286 26.0 0.2‡ Ryan 18 NA 10.7 50% NA 5,510 306 NA Spring 3 3.0 8.5 NA 3.65x104 45 15.0 NA Wirth 39 4.3 7.9 61% 6.70x105 348 9.4 NA *Littoral area defined as less than 15 feet deep † Based on long term average data. ‡Recent projects have altered these statistics. NA= Information not available.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-3 Methods
The 2017 lake monitoring schedule of physical and chemical parameters is shown in Table 1-2. Most lakes followed this schedule and were sampled once in winter, March-April, and October-November and twice per month during the period of May through September. Spring Lake was only sampled once per month.
Table 1-2. Schedule of sampled parameters for most lakes in 2017.
Parameters Sampling frequency Chloride, Chlorophyll-a, Conductivity, Dissolved oxygen, Once Winter pH, Phytoplankton, Secchi Transparency, Temperature, Total Once March – April Phosphorus, Soluble Reactive Phosphorus, Total Nitrogen, Twice per month May – September Turbidity Once October – November Silica Once Winter Once March – April Once per month May – September Once October – November Zooplankton Once March – April Once per month May – September Once October – November Alkalinity, Ammonia, Hardness, Sulfate, Total Kjeldahl Once Winter Nitrogen, Nitrate/Nitrite, Once March – April Once May – September Once October – November Escherichia coli Once May – September
All physical measurements and water samples for chemical analyses were obtained from a point directly over the deepest point in each lake (sampling station). The sampling stations were determined from bathymetric maps and located using handheld GPS or shoreline landmarks and an electronic depth finder.
A Hydrolab Minisonde 5 Multiprobe was used to record temperature, pH, specific conductivity, dissolved oxygen, and turbidity profiles. These parameters were measured at 1-meter intervals from the surface to the lake bottom. The multiprobe was calibrated according to the manufacturer’s guidelines prior to each sampling trip. Secchi disk transparency was determined with a black and white 20-cm diameter disk on the shady side of the boat.
Two composite surface water samples were collected using a stoppered 2 m long, 2 inch diameter white PVC tube and combined in a white plastic bucket. Water from this mixed sample was decanted into appropriate bottles for analysis. Subsurface samples were collected with a 2 liter Wildco Kemmerer water sampler. Chlorophyll-a samples were stored in opaque bottles for analysis. All other samples were collected in new clear plastic bottles. Each lake sample collection regime was determined based upon maximum depth, stratification characteristics, and the results of previous studies (Table 1-3).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-4 Table 1-3. Sampling depth profiles for the 2017 MPRB lakes monitoring program.
Lake Sample Depth (m) Bde Maka Ska 0-2 composite, 6, 12, 18, 22 Cedar Lake 0-2 composite, 5, 10, 14 Diamond Lake Grab (surface) Lake Harriet 0-2 composite, 6, 12, 15, 20 Lake Hiawatha 0-2 composite, 4 Lake of the Isles 0-2 composite, 5, 8 Loring Pond 0-2 composite, 4 Lake Nokomis 0-2 composite, 4, 6 Powderhorn Lake 0-2 composite, 4, 6 Spring Lake 0-2 composite, 4, 6 Wirth Lake 0-2 composite, 4, 7
Phytoplankton samples were collected during each sampling trip from April through October for all lakes (Table 1-2). Phytoplankton were collected from the 0-2 m surface composite sample and stored in an opaque plastic container with a 25% glutaraldehyde preservative solution. Vertical zooplankton tow samples were taken at the sampling station for each lake once per month during the growing season (except at Brownie Lake, Diamond Lake, Grass Lake, and Spring Lake). Zooplankton were collected using an 80 µm mesh Wisconsin vertical tow net with an 11.7 cm diameter opening retrieved at a rate of 1 m/s from approximately 1 m off the bottom through the full water column to the surface. The 80 µm mesh Wisconsin bucket was rinsed with distilled water or ethanol from the outside. The sample was preserved 90% denatured histological ethanol to a mix of approximately 50% sample 50% ethanol.
Immediately following collection all samples were placed on ice in a cooler and stored at approximately 4°C. Samples were transported to the contract laboratory for analysis within 8 hours of collection. Sampling procedures, sample preservation and holding times followed procedures described in Standard Methods (2005) or US Environmental Protection Agency (US EPA, 1979 (revised 1983)). The 2017 contract laboratory for chemical analyses was Instrumental Research, Inc. (IRI). PhycoTech, Inc. analyzed all phytoplankton and zooplankton samples. The methods and reporting limits for parameters are listed in Table 1-4.
More information and results for the physical and chemical parameters can be found in individual lake sections and Appendix B.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-5 Table 1-4. Methods and reporting limits used for parameter analysis in the 2017 Minneapolis lakes monitoring program.
Parameter Method Reporting Limit Alkalinity Standard Methods 2320 B 2.00 mg/L Ammonia USGS I-3520-85 0.250 mg/L Chloride Standard Methods 4500-Cl- B 2.00 mg/L Chlorophyll-a Acetone extraction/spectrophotometric 0.500 µg/L determination (pheophytin corrected) SM 10200 H Conductivity Hydrolab Minisonde 5a Multiprobe (field) 0.1 µS/cm Dissolved oxygen Hydrolab Minisonde 5a Multiprobe (field) 0.01 mg/L Escherichia coli Colilert Quanti-Try, IRI 1 MPN/100 mL Hardness Standard Methods 2340 C 2.00 mg/L Nitrate/Nitrate Standard Methods 4500-NO3 E 0.030 mg/L Nitrogen Silica Standard Methods 4500-SiO2 C 0.500 mg/L Soluble Reactive Standard Methods 4500-P E 0.003 mg/L Phosphorus Sulfate ASTM D516-90 5 mg/L Temperature Hydrolab Minisonde 5a Multiprobe (field) 0.01 °C Total Kjeldahl ASTM D3590 A-02 0.500 mg/L Nitrogen Total Nitrogen Standard Methods 4500 N C Alkaline persulfate 0.500 mg/L oxidation/automated cadmium reduction method. Total Phosphorus Standard Methods 4500-P E 0.010 mg/L Turbidity Hydrolab Minisonde 5a Multiprobe (field) 1 NTU Transparency Secchi disk 0.01 m
WELLS
Background
Groundwater levels are monitored by the MPRB staff at seven piezometric wells. Piezometric wells are drilled to specific depths in order to monitor hydraulic head, the groundwater pressure above a known datum. Irrigation wells use groundwater for golf course turf and greens area maintenance. Augmentation wells are used to maintain water levels at lakes and ponds and, if permitted, are occasionally used for winter ice rinks. Figure 1-2 is a map of the piezometric, irrigation, and augmentation well locations in Minneapolis.
The Minnesota Department of Natural Resources (MDNR) issues the permits and determines pumping limits for irrigation and augmentation wells. The MPRB is not allowed to exceed these limits. Annual fees and reports are sent to the MDNR. The MPRB staff also records groundwater levels from piezometric wells throughout Minneapolis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-6 Methods
Piezometric well readings are taken with a Herron Instrument Water Level Meter. This water tape is read at the top of the well casing to +/- 0.01 feet and its accuracy complies with US GGG-T-106E EEC Class III protocols. Piezometric wells A, B, and C are monitored once a month January, February, March, and December and twice a month April through November. Wells D, E, F, and G are monitored quarterly.
Results & Discussion
The piezometric well readings are taken throughout the year and data is archived in a MSExcel spreadsheet.
Results from the 2017 lake augmentation well readings and annual usage can be found in the Powderhorn Lake and Loring Pond sections. All the irrigation and augmentation wells used were below their MDNR allotted groundwater pumping volumes.
Figure 1-2. Map of piezometric and irrigation/augmentation well locations monitored by MPRB Environmental Management.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-7 WATER QUALITY TRENDS (TSI)
Scientists have analyzed water quality parameters in Minneapolis lakes sporadically since 1927 and consistent bi-weekly monitoring began in 1991. In 2017, the MPRB monitored 11 city lakes according to the current schedule and protocols (Table 1-2). The data collected was used to determine nutrient related water quality (trophic status) and general usability.
Trophic status is used to estimate water quality and is based on Carlson’s Trophic State Index (TSI; Carlson, 1977). Trophic state is calculated using three nutrient related water quality parameters collected from surface water: water transparency (Secchi depth), chlorophyll-a (chl-a), and total phosphorus (TP).
Water transparency is measured using a 20 cm black and white Secchi disk. The Secchi disk is lowered into the water until it cannot be seen. Then it is lowered a short distance further and raised until it is seen again. The average of these two numbers represents the Secchi depth. The Secchi depth is dependent on algal biomass or other factors that may limit light penetration (e.g. suspended solids, dissolved organic material).
Chlorophyll-a (chl-a) is a pigment algae use to capture sunlight and is a measure of how much algal biomass is in the lake.
Phosphorus is often the limiting nutrient in most freshwater lakes and therefore controls the growth of algae. By measuring TP in lake water, it is possible to estimate algal growth and the potential for algal blooms (high algal growth).
Individual Secchi, chl-a, and TP TSI scores are calculated for the growing season (May-September) for each lake. The annual lake TSI score is the average of the individual (Secchi, chl-a, and TP) TSI scores. It should be noted that some annual lake TSI scores are an average of only two parameters (chl-a TSI and TP TSI) if a Secchi is not or cannot be taken on a particular lake. The individual TSI formulas are below.
푆푒푐푐ℎ𝑖 푇푆퐼 = (60 − 14.41) × ln(퐴푣푒푟푎𝑔푒 𝑔푟표푤𝑖푛𝑔 푠푒푎푠표푛 푆푒푐푐ℎ𝑖 𝑖푛 푚푒푡푒푟푠) 푚𝑔 푇푃 푇푆퐼 = 14.42 × ln( 퐴푣푒푟푎𝑔푒 𝑔푟표푤푛𝑖푛𝑔 푠푒푎푠표푛 푇푃 𝑖푛 ⁄퐿 × 1000) + 4.15 휇𝑔 퐶ℎ푙표푟표푝ℎ푦푙푙-푎 푇푆퐼 = 9.81 × ln(퐴푣푒푟푎𝑔푒 𝑔푟표푤𝑖푛𝑔 푠푒푎푠표푛 푐ℎ푙표푟표푝ℎ푦푙푙-푎 𝑖푛 ⁄퐿) (푆푒푐푐ℎ𝑖 푇푆퐼 + 퐶ℎ푙표푟표푝ℎ푦푙푙-푎 푇푆퐼 + 푇푃 푇푆퐼) 퐴푛푛푢푎푙 푇푆퐼 = 3
TSI scoring is based on a 0-100 scale, although theoretically the scale has no upper or lower bounds, with higher numbers relating to higher trophic status and lower water quality. Three TSI scores are possible using the parameters described above and can be reported separately or as an average. The TSI score based on chl-a is thought to be the best measure of trophic state because it is the most accurate at predicting algal biomass (Carlson, 1977). TSI scores reported by the MPRB are an average of the three parameters.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-8 It is important to consider soil type and land use in the surrounding watershed when using the TSI to determine lake water quality. The State of Minnesota has seven ecoregions determined by land use, soil type, and natural vegetation. Minneapolis lies within the North Central Hardwood Forests (NCHF) ecoregion, an area with fertile soils and agriculture as a dominant land use in rural areas. Lakes in this ecoregion generally have higher concentrations of nutrients and 90% of the TSI scores are between 41 and 77. In the Twin Cities metro area it is recommended that a TSI score of 59 or lower be maintained in lakes used for swimming. This recommendation is based upon the aesthetic appeal of the water body.
One of the methods used to classify lakes involves using categories based on the TSI score. Lakes generally fall into one of four categories based on trophic status that include:
Oligotrophic (30 > TSI < 40) lakes are characterized by low nutrients and contains oxygen throughout the water column, and clear water. Salmonid fisheries may dominate.
Mesotrophic (40 > TSI < 50) lakes generally are moderately clear and have an increased probability of experiencing hypolimnetic anoxia during the summer months.
Eutrophic (50 > TSI < 70) lakes are considered fertile and characterized by high algal biomass and may have macrophyte problems in some systems. Hypolimnetic anoxia occurs in stratified lakes and only warm water fisheries can be sustained.
Hypereutrophic (TSI > 70) lakes are characterized by high nutrient concentrations, leading to frequent severe algal blooms and low macrophyte densities due to light limitation by algae.
Most lakes in the NCHF ecoregion fall into the eutrophic category and the lowest trophic status lakes typically fall into the mesotrophic category. All the sampled lakes in Minneapolis are either eutrophic or mesotrophic. Detailed information on TSI scores and nutrient related water quality parameters can be found in the individual lake sections and Appendix A.
Changes in lake water quality can be tracked by analyzing long-term trends in TSI scores. The MPRB uses TSI scores to assess changes in water quality and evaluate the effectiveness of restoration and management activities on the trophic state of the lakes. Linear regression analysis is a common method used for determining trends in average TSI over time. A graph was made of average annual TSI scores for each lake (found in each individual lake’s section). A trend line was fit through the data points. The linear regression line is defined as y = mX + b, where m is the slope of the line. The slope indicates the general trend of the data. The p-value indicates the probability of the observed trend even if there isn’t one. The use of a p-value of <0.05, meaning there is a 5% chance there isn’t a trend even if one is observed, is frequently used to determine if a trend is statistically significant. The R2 value indicates how well the trend fits the data with 1.00 being a perfect fit. Based upon these results it is possible to describe the direction of the trend (a negative or positive slope) and the degree of confidence one can place upon the trend. Better water quality and decreasing productivity in surface water is generally indicated by a decreasing TSI score and negative slope of the regression equation (as shown in the TSI figures in each individual lake’s section). Conversely, a positive slope and increasing TSI scores generally indicates increasing productivity and a decrease in water clarity.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-9 BOX AND WHISKER PLOTS
Box and whisker plots for the three trophic state parameters (transparency, surface chlorophyll-a levels, and surface total phosphorus levels) were created for each lake and presented in individual lake sections. The box and whisker plots are another way to detect trends and are valuable for assessing variability over the years. Box and whisker plots can be used to look at short-term (annual) and long-term variation at the same time.
For each plot, the box represents the middle 50 percent of the data from the 25th percentile to the 75th percentile. The horizontal line that cuts across the box represents the median value. The whiskers (the vertical lines extending off the boxes) represent the data from the 25th to the 5th percentile and the 75th to the 95th percentiles. Any data falling above the 95th percentile or below the 5th percentile is marked as outliers. In this report, all outliers in the box and whisker plots are represented by a circle.
Generally, more compact box plots with short whiskers and few outliers indicate low annual variability for the lakes. Long-term trends can be seen by the box plots trending in an up or down direction.
Outlier
95th Percentile
75th Percentile
Median
25th Percentile
5th Percentile
LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
Many lake monitoring programs use Carlson’s TSI to track the environmental health of a lake. The TSI index is not intuitive or readily understandable to the general public. Additionally, TSI does not measure recreational access issues.
In 2004, the MPRB worked with Barr Engineering Company with funding from Minneapolis Public Works to develop a new index. The original Lake Aesthetic and User Recreation Index (LAURI) was the result of this development. It was designed to give recreational users a source of information about conditions affecting their use of city lakes. The goal was to have an easily understandable recreational indicator. The two major constraints in developing the indices were that they were to be collected by existing water quality staff and within the existing budget.
In 2009, the LAURI was further refined to give a more accurate, and science based indicator for the public. The scoring for the aesthetic consideration portion of the LAURI was further refined in 2017 to better reflect the experience at a lake. The revised LAURI has five indices:
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-10 1. Public Health (E. coli measured at public swimming beaches) 2. Water Quality (water clarity/Secchi depth) 3. Habitat Quality (aquatic plant and fish diversity) 4. Recreational Access (availability and ease of public access) 5. Aesthetic Considerations (color of the water, odor of the water, and garbage/debris)
Data for the LAURI analysis is collected during regular lake monitoring activities and once a month during beach monitoring trips during the growing season from May to September.
The LAURI has proven to be useful to users of the Minneapolis park system. Someone interested in walking or biking around a lake may use only the aesthetic score. A swimmer may compare lakes based on the public health, aesthetic, and water quality scores. A sailor or kayak user may be primarily concerned with the recreational access score.
Public Health Index
To determine whether a lake meets guidelines for full-body recreational contact for people the existing beach monitoring program data were used. E. coli, the indicator recommended by the Environmental Protection Agency (EPA), was measured at every public beach in the park system. Beaches exist on Bde Maka Ska, Cedar, Harriet, Hiawatha, Nokomis, and Wirth Lakes. The scoring used the season long geometric mean from the beach monitoring program for each lake (Table 1-5). At lakes with more than one beach, beaches were averaged together. This metric was chosen because US EPA and Minnesota guidelines state that beaches should not exceed a geometric mean of 126 organisms per 100 mL during a 30 day time period. Lower numbers of organisms indicate less risk of illnesses for lake users.
Table 1-5. Scoring for the public health portion of LAURI. The geometric mean of E. coli concentrations for the year is used to determine the score. If more than one beach is present at a lake, the average of the geometric means is used.
E. coli bacteria (MPN/100 mL) Score <2 (Not Detected) 10 2 – 10 9 11 – 20 8 21 – 35 7 36 – 50 6 51 – 65 5 66 – 80 4 81 – 100 3 101 – 125 2 >126 1
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-11 Water Quality Index
Water clarity is easy to measure and understand. This simple measure is a good integrator of various parameters affecting the eutrophication status of a lake. The lakes are separated into deep lakes and shallow lakes using criteria developed by the Minnesota Pollution Control Agency (MPCA). A shallow lake is defined as 80% littoral (< 15 feet deep). Bde Maka Ska, Cedar, Harriet, and Wirth are considered deep lakes. Loring, Isles, Hiawatha, Nokomis, and Powderhorn are considered shallow lakes. Higher numbers indicate clearer water. LAURI scoring uses the average Secchi transparency reading from all the data collected during the growing season (May-September; Table 1-6).
Table 1-6. Scoring for the water quality portion of LAURI.
Secchi Depth (m) Deep Lake Score Shallow Lake Score 0 – 0.5 1 2 0.6 – 1 2 4 1.1 – 1.5 3 6 1.6 – 2.0 4 8 2.1 – 2.5 5 10 2.6 – 3 6 10 3.1 – 3.5 7 10 3.6 – 4.0 8 10 4.1 – 4.5 9 10 >4.6 10 10
Habitat Quality Index
LAURI assessments of habitat quality are determined by the most recent survey information. Macrophyte surveys were conducted by MPRB staff and scoring is based on presence of aquatic plants (macrophytes), density of plants, and amount of coverage (Table 1-7). The more aquatic plants are observed, the higher the habitat quality index was scored. Fish surveys were conducted by MNDNR and points are awarded for diverse fish populations. The score from the aquatic plant and fish surveys are averaged for the LAURI.
Table 1-7. Scoring for the habitat portion of LAURI.
Macrophyte Score Density Score Coverage > Score # Fish Score Species 15 ft species 0 0 Low 0 0 – 25% 2 ≤6 2 1 – 2 3 Low-Medium 3 25 – 50% 4 7 – 8 4 2 – 4 6 Medium 6 50 – 75% 7 9 – 11 6 5 – 6 8 Medium-High 8 75 – 100% 10 12 – 14 8 >6 10 High 10 ≥15 10
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-12 Recreational Access Index
The lakes are also scored for the quantity of recreational access to the water. The recreational score considers the number of fishing docks or stones, beaches, boat launches, intra lake connections, canoe racks, boat rentals, picnic areas, boardwalks, and concessions at a lake (Table 1-8). While aquatic plants are a necessary part of a healthy lake ecosystem, they can also interfere with recreational uses of the lake; therefore, lakes also receive points for invasive plant growth management.
Table 1-8. Scoring for the recreational access portion of LAURI. The number of fishing docks or stones, beaches, boat launches, intra lake connections, canoe racks, boat rentals, picnic areas, boardwalks, and concessions at a lake are added up. An additional four is added to determine the score if the lake has an aquatic plant management program.
Total number of recreational opportunities Score + aquatic plant management 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 – 8 8 9 – 10 9 >10 10
Aesthetic Considerations Index
The lakes are scored for water color, odor, and debris based on an assessment done from shore, dock, or boat (Table 1-9). Lower numbers indicate worse aesthetics. Individual color, odor, and debris scores are averaged over the season. The final aesthetic score is an average of the three individual scores. Aesthetics can be difficult to evaluate as they are strongly qualitative and dependent on individual experience. The scoring for the aesthetic index was refined in 2017 to use the lowest of the three scores, rather than an average of the three which was how it was previously calculated.
Table 1-9. Scoring for the aesthetic portion of LAURI.
Color Score Odor Score Debris Score Clear 10 None/Natural 10 None 10 Light brown or Musty – faint 8 Natural 9 green 8 Musty – strong 6 Foam 8 Bright green 5 Sewage, fishy, or Piles of milfoil (>3) 7 Milky white 4 garbage – faint 5 Fixed trash (>3) 4 Brown, reddish, Sewage, fishy, or Floating trash (>3) 3 or purple 2 garbage – strong 2 Dead fish (>5) 2 Gray or black 0 Anaerobic or Green scum 2 septic 0 Oil film 1 Sewage solids 0
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-13 WINTER ICE COVER
An interesting climatological statistic to track over time is the date that a lake freezes in the fall and the date it thaws in the spring. Ice phenology affects migration and breeding patterns of birds, food supply of fish and animals, and water chemistry. Length of ice cover in our region is affected by local weather patterns as well as changes in regional and global cycles. Magnuson, et al (2001) found that northern hemisphere temperate climate ice records reflected changes in the strength of a low- pressure zone that builds over the Aleutian Islands (the Aleutian Low) and El Nino cycles (cycles of warming the surface waters of the tropical Pacific Ocean). Ice-out and -on dates are given in the individual lake sections and a comparison among lakes can be found in Section 18 in Tables 18-7 and 18-8. Ice-off and ice-on dates are reported to the MPCA and MDNR to include in their statewide long-term ice record.
However, some caution must be used when interpreting the historical data. Over the years many different people have been responsible for writing down the dates and ice dates can be somewhat subjective with people using different observation techniques. Since 2000, the MPRB has been using the definition of ice-on as occurring when the lake is 100% covered with ice, preferably in the afternoon (when ice may break up on a sunny day). Ice-off occurs when the lake is essentially ice free (<10% covered with ice).
AQUATIC PLANTS
Aquatic plants (macrophytes) form the foundation of a healthy lake ecosystem. They provide important habitat for insect larvae, snails, and other invertebrates which are food sources for fish, frogs, turtles, and birds. Aquatic plants also provide shelter for fish and food for waterfowl. Therefore, the health of a lake depends upon having a healthy plant community. MPRB assesses macrophyte communities in the Minneapolis lakes on a rotating basis. All lakes were visually assessed in June and a point intercept survey of Wirth Lake was conducted in August 2017.
Lakes with macrophytes are usually clearer than lakes without macrophytes. Plant roots stabilize sediments and shorelines and prevent the suspension of sediments (from wind or fish) that would otherwise result in turbid or murky waters. Aquatic plant growth produces oxygen and uses nutrients from the water column and from the sediments which would otherwise be used by algae. Macrophytes add an enormous amount of surface area to lakes providing habitat for microscopic plants and animals to grow and utilize nutrients otherwise available to planktonic algae. Large zooplankton use aquatic plants as a refuge against fish. Lakes with a vegetation-dominated clear state typically have more diverse fish communities and larger numbers and diversity of waterfowl.
Eurasian Watermilfoil Control Program
Overgrowth of Eurasian watermilfoil (Myriophyllum spicatum) is a recreational access problem in several Minneapolis lakes. From a recreational perspective, milfoil is problematic in that it forms dense floating mats that interfere with boating and swimming. From an ecological standpoint, milfoil can provide vertical structure and habitat for fish; however, it can also be too dense to provide good fish habitat. Eurasian watermilfoil also out-competes native species and may reduce the available habitat for other species.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-14 Currently, no method has been proven to rid lakes of milfoil without significant non-target effects, but several management methods exist to treat the symptoms of infestation. The MPRB primarily uses mechanical harvesting to control the growth of milfoil in city lakes. Harvesting milfoil is analogous to mowing a lawn. Only the top two meters of the milfoil plants are removed but this temporarily allows for problem-free boating and swimming. Harvesting was completed on Bde Maka Ska, Cedar, Harriet, and Lake of the Isles. SCUBA divers hand pulled milfoil out of heavily used recreational areas in Lake Nokomis and Wirth Lake. For acreage see individual lake sections. MPRB Staff removed 80 flatbed truck loads of milfoil in 2017 which is approximately 440 cubic yards of aquatic plant material.
PHYTOPLANKTON AND ZOOPLANKTON MONITORING
Background
Biological parameters are routinely measured as part of a lake’s assessment. Phytoplankton (algae) and zooplankton are two of the common biological parameters collected because they are essential to the aquatic food web and influence other aspects of the lake including color and clarity of the water and fish production.
Phytoplankton are microscopic plants that are an integral part of the lake community. Phytoplankton use nutrients in the water and sunlight to grow and are the base of the aquatic food web. Chlorophyll- a is the primary photosynthetic pigment contained in algae. Chlorophyll-a concentration can be easily measured in a water sample and is a common way to estimate the phytoplankton biomass in the water (Paerl, 1998).
Zooplankton are tiny animals that feed on phytoplankton and other zooplankton. They are vital to the lake community and form the second level in the food web. Rotifers and arthropods are the two most commonly found zooplankton in Minneapolis lakes. Rotifers are smaller in size but are of great importance in the aquatic food web because of their abundance, distribution, and wide range of feeding habits. Copepods and cladocerans are larger arthropods and members of the class Crustacea. Copepods are the most diverse group of crustaceans. A cladoceran genus, Daphnia, is known as the common water flea and is a very well known zooplankton.
Methods
Phytoplankton
Phytoplankton samples were collected twice a month from most of the monitored lakes (Bde Maka Ska, Cedar, Harriet, Hiawatha, Isles, Loring, Nokomis, Powderhorn, and Wirth) except for February, April, and October which were sampled once per month. Samples were collected once a month at Brownie, Diamond, Grass, and Spring Lakes. Surface water composite samples were collected for phytoplankton using a 2-m long, stoppered 2-inch diameter PVC tube. Two such samples were mixed in a clean white plastic bucket. Water from this mixed sample was decanted for analysis into amber bottles, preserved with 25% glutaraldehyde (a preservative) back at the lab and sent to PhycoTech Incorporated (St. Joseph, MI) laboratory for analysis. Analysis was completed using the phytoplankton rapid assessment count developed by Edward Swain and Carolyn Dindorf of the MPCA. This method involves a sub-sample being placed in a counting chamber and analyzed using an inverted microscope. The algal division, taxa, genus, and species are identified and the percent abundance by volume is estimated. Identification protocol is according to Phycotech’s comprehensive library of keys and taxonomic references
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-15 (http://www.phycotech.com/All_Keys_10272016.pdf). The results are presented by division (phylum) in the individual lake sections. Common phytoplankton divisions and a common description are given in Table 1-10. Chlorophyll-a concentrations were used to estimate phytoplankton biomass in the lakes. Each lake section shows chlorophyll-a concentrations and the distribution of phytoplankton divisions throughout the sampling season.
Table 1-10. Phytoplankton divisions and brief descriptions.
Division Description Bacillariophyta Diatoms Chlorophyta Green algae Chrysophyta Chrysophytes or Golden algae Cryptophyta Cryptomonads Cyanophyta Cyanobacteria or Blue-green algae Euglenophyta Euglenoids Haptophyta Haptophytes Pyrrhophyta Dinoflagellates Xanthophyta Yellow-brown algae
Zooplankton
Zooplankton samples were collected monthly from most Minneapolis lakes (Table 1-2). Diamond and Grass Lakes were not sampled because of their shallow depths. Brownie and Spring Lakes were not sampled due to lack of zooplankton in most years. Samples were collected using an 80-µm plankton net with an 11.7 cm diameter opening and a Wisconsin-type bucket. The net was raised from approximately one meter above the bottom to the surface at a rate of one meter per second. The captured zooplankton were rinsed into a bottle using 90% denatured histological ethanol to a final concentration of 50% sample and 50% preservative. The distance the net was pulled through the water column (tow depth) was recorded on field sheets and on the bottle label. Zooplankton were identified at PhycoTech Inc. as completely as possible by: class, subclass, order, suborder, family, genus, species, and subspecies. Zooplankton were identified according to standard protocols and Phycotech’s comprehensive library of keys and taxonomic references (http://www.phycotech.com/All_Keys_10272016.pdf). The zooplankton results were divided into groups for presentation as shown in Table 1-11. Results are presented in the individual lake sections.
Table 1-11. Major zooplankton groups and brief descriptions.
Major Groups Description Calanoid Phylum Arthropoda. Type of copepod. Generally herbivorous. Cladoceran Phylum Arthropoda. Eats algae. Commonly called the water flea. Cyclopoid Phylum Arthropoda. Type of copepod. Many are carnivorous. Protozoan Single celled organisms. Many are shelled amoeba. Rotifer Known as the wheel animals. Eat particles up to 10 μm.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-16 FISH STOCKING
Many of the lakes in Minneapolis are stocked with fish by the MDNR. This information is on the MDNR LakeFinder website (http://www.dnr.state.mn.us/lakefind/index.html).
Stocking Fish Sizes:
• Fry - Newly hatched fish. Walleye fry are 1/3 of an inch or around 8 mm. • Fingerling - Fingerlings are one to six months old and range in size from one to twelve inches. • Yearling - Yearling fish are at least one year old and can range from three to twenty inches. • Adult - Adult fish that have reached maturity age.
FISH KILLS
Many of the summer fish kills in Minneapolis lakes are attributed to columnaris disease. The naturally occurring Flexibacter columnaris bacteria cause the disease. This disease is usually associated with a stress condition such as high water temperature, low dissolved oxygen concentration, crowding, or handling. Symptoms in fish include: grayish-white lesions on parts of the head, fins, gills, or body usually surrounded by an area with a reddish tinge. On crappies, the lesions are generally confined to the fins and gills and rarely extend to the body.
Columnaris is known to only infect fish species and is not a health risk to humans. The bacteria are most prevalent in lakes when water temperatures approach 65-70 degrees F from late May to late June. Columnaris levels can increase after a major rainfall and runoff which supply additional nutrients to area lakes. Bluegill, crappie, yellow perch, and bullhead fish species are most affected by the disease. The columnaris disease causes erosion of the fishes’ skin causing a leakage of the bodily fluids and an influx of lake water into the fishes’ body. There is little that the MDNR or the public can do to prevent this naturally occurring phenomenon.
Winter fish kills on lakes are often due to thick ice and snow cover leading to low dissolved oxygen conditions in the water below. Usually small lakes and ponds are most affected by winter fish kills. The MPRB reports all fish kills to the MDNR to aid in determining the cause.
QUALITY ASSURANCE/QUALITY CONTROL
The contract laboratory analyzed blanks and appropriate standards with each set of field samples. Equipment blanks were analyzed to detect any equipment contamination. In addition, field duplicate samples were analyzed each lake sampling trip (weekly) and blind laboratory performance standards were analyzed every month sampling occurred. Field blanks were done every sampling trip. Ideally, laboratory split samples are analyzed twice a year between a minimum of three labs.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-17 Calibration blanks, reagent blanks, quality control samples, laboratory duplicate samples, and matrix spike/duplicate samples were analyzed at a 10% frequency by the contract laboratory. The quality control samples analyzed by the laboratory consisted of two sets:
• samples of known concentration (control standards) that served as an independent verification of the calibration standards and as a quality control check for the analytical run and
• Blind samples (of unknown concentration) provided by the MPRB Environmental Operations staff.
For more details and QA/QC results for 2017, see the Quality Assurance Assessment Report in Section 29.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 1-18 2. BIRCH POND
HISTORY
Birch Pond is a 6-acre water body on the east side of Theodore Wirth Parkway in Theodore Wirth Regional Park near the Eloise Butler Wildflower Garden and Bird Sanctuary, Figure 2-1. The pond lies within the original Glenwood Park parcel. In 1910, the pond was named for the white birch trees which grew along its shores and hillsides. It has no public boat access or fishing docks. Birch Pond is protected from winds by large hills and mature trees that surround it. Aesthetics and bird watching opportunities are Birch Pond’s main recreational values.
Buckthorn (Rhamnus cathartica and Rhamnus frangula) is an invasive species that threatens native woodlands. Buckthorn was removed from the understory of the Birch Pond basin in 2006 as a part of vegetation restoration efforts in preparation for the centennial anniversary of the Eloise Butler Wildflower Garden and Bird Sanctuary. Buckthorn was removed again in 2015 as part of the Wirth Vegetation Management project funded by the Outdoor Heritage Fund.
The Minneapolis Park & Recreation Board (MPRB) currently does not include Birch Pond in its regular lake sampling program and only monitors ice-off and -on dates.
Figure 2-1. Birch Pond in the fall of 2016.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 2-1 LAKE LEVEL
Lake level records for Birch Pond were measured by the City of Minneapolis and the MPRB from 1928-1970. More recently, the MDNR created an accurate bench mark and has set an Ordinary High Water Level (OHW) of 846.3 msl for Birch Pond. Lake levels in Birch pond varied over time due to changes in climate and rainfall patterns as well as periodic augmentation through pumping. Birch Pond was once part of a water conveyance system which carried water from the Mississippi River to the Chain of Lakes. A remnant of the old conveyance system remains on the east side of the pond. There is currently not a surveyed lake level gauge on Birch Pond.
WINTER ICE COVER
Ice came off Birch Pond on March 29, 2017, which was 6 days earlier than average. Ice came back to the pond December 7, 2017, 11 days later than the average date for ice-on. See Section 17 for additional ice monitoring data.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 2-2 3. BROWNIE LAKE
HISTORY
Human activities drastically changed the shape and size of Brownie Lake over the past 150 years. Construction of a railroad embankment in 1883 caused a decrease in lake surface area of 34%, transforming the lake formerly known as Hillside Harbor. In 1916, the connection between Cedar and Brownie Lakes was completed further decreasing the surface area of the lake by another 56% by dropping the water level 3 m (~10 ft) and creating the lake that we see today (Wirth, 1945; Trembley, 2012). Figure 3-1 shows a picture of Brownie Lake.
Figure 3-1. View from the walking path on the southwest corner of Brownie Lake in the fall of 2016.
Structural changes to the lake have had implications to its water chemistry. Brownie Lake is permanently stratified due to a strong density difference that exists between water near the surface and a deeper layer of water containing high levels of dissolved minerals. Lakes that are stratified due to differences in density due to water chemistry are called meromictic lakes. The sharp density difference between the surface waters and deeper water in meromictic lakes is called a chemocline. Meromictic lakes do not mix due to the stability of the chemocline, and this quality makes them difficult to compare with dimictic or polymictic lakes. Swain (1984) first theorized that the structural changes made to Brownie Lake caused its state of permanent stratification. Swain’s 1984
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 3-1 study of a 117-cm lake sediment core found changes in the ratios of iron to manganese (Fe:Mn) and iron to phosphorus (Fe:P) at a layer in the sediment corresponding to approximately 1925. The change in the chemistry of the sediments indicates the onset of permanently anoxic bottom-water signifying to Swain that Brownie Lake had become meromictic. In the past, stormwater inputs from Interstate 394 (old U.S. Highway 12) added pollutants to Brownie Lake and has contributed to the stability of the chemocline. Currently, Brownie Lake receives runoff from both Minneapolis and St. Louis Park.
Swain’s lake-core analysis found further evidence of the influence that human activities had on Brownie Lake. Ragweed pollen first appeared at sediment core at depths that corresponding to 1850- 1860, an indication of European-American settlement (Swain, 1984). Later, changes in the watershed led to increases in primary productivity, algal biomass, and sediment accumulation indicating eutrophication. As water clarity decreased over time benthic diatoms were replaced by planktonic forms and the zooplankton community shifted from large bodied Daphnia to the smaller Bosmina species (Swain, 1984).
Water levels in Brownie Lake have been manipulated at various times in its history. Groundwater was first used to augment lake levels in the Chain of Lakes (Brownie, Cedar, Isles, and Bde Maka Ska) in 1933 and continued through 1938. During the 1950s, the Prudential Insurance Building began discharging 50 thousand gallons of cooling water per day into Brownie Lake. During this time-period, a link was created between Brownie Lake and Bassett Creek that provided water to the Chain of Lakes during times of low water levels. In 1966, a pumping station was constructed at the Mississippi River to augment flow in Bassett Creek. Water levels in the Chain of Lakes were regulated by pumping from the Mississippi River into Brownie Lake until 1990.
The MPRB and other surrounding landowners have completed several projects improving the Brownie Lake basin. In 2007, the Target Corporation rehabilitated a stormwater pipe and restored disturbed hillside vegetation on the west side of the lake. City of Minneapolis Public Works and the MPRB worked together to solve an erosion problem on the east side of Brownie Lake in 2008. The two organizations restored an eroded area and replaced an exposed and eroding stormwater outlet with a buried drop-structure and pipe.
In March 2012, the MPRB Board of Commissioners approved an Area Plan for Brownie Lake to improve the land and park amenities surrounding the lake, including path and bike trail improvements and a new canoe launch. Trail improvements, a pedestrian bridge, a new canoe launch, tree planting and landscaping were completed in 2014.
Brownie Lake is on an every other year sampling schedule and was not sampled in 2017. All data presented is from 2016 and the lake will be monitored again in 2018. Figure 3-2 shows the bathymetric map and Table 3-1 shows the morphometric data for Brownie Lake.
Table 3-1. Brownie Lake morphometric data.
Surface Mean Watershed: Residence Max Littoral Volume Watershed Area Depth Lake Area Time Depth (m) Area* (m3) Area (acres) (acres) (m) (ratio) (years) 18 6.8 15.2 39% 4.98x105 369 20.5 2.0 * Littoral area defined as less than 15 feet deep.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 3-2
Figure 3-2. Bathymetric map of Brownie Lake.
LAKE LEVEL
The Ordinary High Water Level (OHW) for Brownie Lake, as determined by the MDNR, is 853 ft (msl). The OHW is defined as the elevation where high water levels can be maintained for a long enough period of time to leave evidence of the water level on the landscape.
See Section 4, Bde Maka Ska for more information on water levels in the Chain of Lakes.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 3-3 WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Figure 3-3 shows the Brownie Lake TSI scores and linear regression. The 2016 TSI score for Brownie Lake was 57, classifying the lake as eutrophic. There is no significant trend in TSI scores over the last 21 years (p > 0.05); however, Brownie is only sampled every other year. Brownie Lake falls near the 50th percentile category for lakes in this ecoregion, based on calculations from the Minnesota Lake Water Quality Assessment Data Base Summary (MPCA, 2004). A detailed explanation of TSI can be found in Section 1.
Figure 3-3. Brownie Lake TSI scores and linear regression from 1993-2016.
BOX AND WHISKER PLOTS
The box and whisker plots in Figure 3-4 show the distribution of data for Secchi depth, chlorophyll- a, and total phosphorus sampling from 2007 to 2016. The horizontal line crossing the graph represents the MPCA eutrophication standard for deep lakes. Data for the entire period of record presented in box and whisker plot format is available in Appendix A. Long-term lake monitoring is necessary to evaluate the seasonal and year-to-year variations seen in each lake and predict trends. A detailed explanation of box and whisker plots can be found in Section 1.
Water transparency in Brownie Lake in 2016 was similar to previous years with an average Secchi depth of 1.6 meters (Figure 3-4a). Algal biomass, as measured by chlorophyll-a concentration, was higher than 2014, but comparable to 2012 and 2010 with an average concentration of 21.87 µg/L (Figure 3-4b). Total phosphorus was similar to 2014 with an average concentration of 40 µg/L (Figure 3-4c). Brownie met the MPCA eutrophication standard for Secchi transparency and total phosphorus, but not chlorophyll-a. Due to Brownie Lake’s permanent stratification, it may not be reasonable to compare Brownie Lake to the deep lake standard. A better measure of the health of Brownie Lake may be to look at long-term trends, which show no significant change over the past 20 years (p > 0.1).
It is difficult to compare Brownie Lake to other Minneapolis Lakes since it is meromictic and is only sampled once per month rather than twice per month that is usual with most of the other lakes. The only other meromictic lake in Minneapolis is Spring Lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 3-4
Figure 3-4. Brownie Lake box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus(c) from 2007-2016. Horizontal lines represent MPCA eutrophication standard for deep lakes. Data from 1993-2016 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 3-5 WINTER ICE COVER
Ice came off Brownie Lake on March 16, 2016, which was 19 days earlier than average. Ice came on the lake December 8, 2016, which was nine days later than average and the latest recorded ice-on date. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other MPRB lakes.
PHYTOPLANKTON
Phytoplankton and zooplankton are the microscopic plant and animal life that form the foundation of the food web in lakes. Figure 3-5 shows the Secchi transparency, chlorophyll-a concentration, and relative abundance of phytoplankton divisions for the 2016 sampling season. No zooplankton samples were collected from Brownie in 2016 due to low zooplankton densities in the past. In 2008, zooplankton tows yielded low concentrations compared to other Minneapolis lakes.
Water transparency fluctuated between 0.8 meters to 3.2 meters, with the lowest transparency in early spring and greatest transparency in June (Figure 3-5a). The lowest Secchi depth in May was associated with low chlorophyll-a concentration and a large abundance of haptophytes and cryptophytes (Figures 3-5b, c). The highest chlorophyll-a values of the season occurred in July and September comprised of mainly dinoflagellates (Pyrrhophyta) and blue-green algae (Cyanophyta). Cryptomonads (Cryptophyta) were present throughout the year, but were at their greatest abundance in June, when transparency was the greatest.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 3-6
Figure 3-5. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Brownie Lake during 2016. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 3-7 4. LAKE CALHOUN / BDE MAKA SKA
HISTORY
Bde Maka Ska is the largest lake in the Minneapolis Chain of Lakes (Figure 4-1). It receives water from Lake of the Isles and discharges water through a weir and open channel to Lake Harriet. The lake has a multitude of recreational opportunities including personal watercraft, sail boat buoy rentals, three public beaches, fishing, and picnicking. The Minneapolis Chain of Lakes Regional Park is the most visited park in the State of Minnesota with nearly 5.7 million user visits a year (Met Council, 2017).
Figure 4-1. Bde Maka Ska in August of 2017.
The lake formerly known as Mde Medoza (Lake of the Loons) and Bde Maka Ska (White Earth Lake) was renamed after John Caldwell Calhoun after he established a military post at Fort Snelling while Secretary of War under President Monroe. In 2015, the Dakota name for the lake, Bde Maka Ska, was added to signs around the lake to honor the Dakota people and educate the public about the lake’s Dakota name. An effort is underway to formally change the currently accepted geographic name for this lake to Bde Maka Ska.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-1
The lake and adjacent property were acquired by the MPRB between 1883 and 1907 at a cost of $130,000. Similar to other lakes in the Minneapolis Chain of Lakes Lake, Bde Maka Ska was dredged and surrounding wetland areas were filled (~35 acres) in the early part of the 20th century. Nearly 1.5 million cubic yards of soil were placed on the shoreline between 1911 and 1924.
An effort was made to connect Lake of the Isles and Bde Maka Ska after wet years in the early 1900s increased interest in water related activities. A water connection between Isles and Bde Maka Ska was created in 1911 after the MRPB received numerous requests and petitions to join the lakes. A connection between Bde Maka Ska and Lake Harriet was pondered but was never implemented due to a five-foot elevation difference between the lakes. In 1967, a pipeline and pumping station were constructed between Bde Maka Ska and Lake Harriet to help regulate water elevations in the Chain of Lakes. Between 1999 and 2001, the outlet was partially daylighted and converted to a gravity-flow connection.
Studies have shown that water quality in Bde Maka Ska has degraded with human activity. In 1973, Shapiro and Pfannkuch found that phosphorus levels in the sediment were about 80% higher than they had been in the prior 80 to 90 years. Total phosphorus in the water column had also increased to 50 – 60 μg/L by the 1970s from pre-industrial levels of between 16 – 19 μg/L (Brugam and Speziale, 1983). The increases in sediment and water column phosphorus appear to be due to European settlement and land clearing for agriculture in the watershed. The construction and connection of storm sewers to Bde Maka Ska (1910 to 1940) is also thought to have had a negative impact on water quality. A study by Klak (1933) showed that cyanobacteria were dominant by the early 1930s in Bde Maka Ska, indicating possible nutrient enrichment.
Water quality restoration projects throughout the 1990s and early 2000s have improved water quality in Bde Maka Ska. A detailed Clean Water Partnership diagnostic study conducted in 1991 determined that phosphorus input to the Chain of Lakes should be reduced to increase water quality. Best management practices (BMPs) were then implemented for Bde Maka Ska and included: public education, increased street sweeping, improved storm-water treatment including constructed wetlands (1999), grit chambers (1995, 1998, 1999), and an aluminum sulfate (alum) treatment to limit internal loading of phosphorus in 2001. Current data analysis confirms that the BMPs are having a positive effect and that water quality in Bde Maka Ska is at, or even slightly better than historic conditions. For example, Bde Maka Ska’s observed TP is similar to the TP level from 1750 and 1800 based on diatom reconstruction from sediment cores (Heiskary et al., 2004).
Bde Maka Ska is a deep, dimictic, glacial kettle lake that typically remains stratified until late October. Table 4-1 contains the morphometric data for Bde Maka Ska. Figure 4-2 shows the bathymetric map of Bde Maka Ska.
Table 4-1. Bde Maka Ska morphometric data.
Surface Mean Watershed: Residence Max Littoral Volume Watershed Area Depth Lake Area Time Depth (m) Area* (m3) Area (acres) (acres) (m) (ratio) (years) 421 10.6 27.4 27% 1.80x107 2,992 7.1 4.2 * Littoral area was defined as less than 15 feet deep.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-2
Figure 4-2. Bathymetric map of Bde Maka Ska.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-3
LAKE LEVEL
The lake level for the Upper Chain of Lakes (Brownie, Cedar, Bde Maka Ska, and Isles) is measured at Bde Maka Ska. The four lakes are connected by channels and the gage at Bde Maka Ska represents the level at each of the four lakes. The designated Ordinary High Water Level (OHW) for Bde Maka Ska is 853 feet above mean sea level. The outlet elevation for Bde Maka Ska is 851.85 ft above mean sea level. Lake levels for the Upper Chain of Lakes are shown in Figure 4-3. Lake levels fluctuated around the OHW for most of the year with the lakes freezing below the OHW in 2017.
Figure 4-3. Lake levels for the Minneapolis Upper Chain of Lakes (Brownie, Cedar, Isles and Bde Maka Ska) from 1971 to 2017. Horizontal line represents the Ordinary High Water Level (853 ft msl) for Bde Maka Ska.
WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Figure 4-4 shows historical Bde Maka Ska TSI scores and trend line. There has been a significant decrease in TSI since 1991 (p < 0.001) with a TSI score of 45 in 2017. This decrease has followed multiple rehabilitation efforts since 1995. The lake is now mesotrophic with moderately clear water and some algae.
Recent lake conditions have remained relatively stable with a TSI score 10 to 15 units lower (better) than the early 1990s, before the lake and watershed improvement projects from the Clean Water Partnership. In comparison to other lakes in this ecoregion, Bde Maka Ska is in the top 10% of TSI scores based on calculations using the Minnesota Lake Water Quality Database Summary (MPCA, 2004). A detailed explanation of TSI can be found in Section 1.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-4
Figure 4-4. Bde Maka Ska TSI scores and linear regression from 1991-2017. The blue square highlights the 2001 alum treatment.
BOX AND WHISKER PLOTS
The box and whisker plots in Figure 4-5 show the data distribution for Secchi transparency, chlorophyll- a, and total phosphorus for the past 10 years. Red horizontal lines on the graphs indicate the MPCA deep lake standards. A detailed explanation of box and whisker plots can be found in Section 1. Box and whisker plots from the entire period of record, 1991-2017, can be found Appendix A.
Water transparency in 2017 was similar to the previous 10 years with an average Secchi depth of 4 meters. Chlorophyll-a was higher in 2017 compared to the previous few years with an average concentration of 4.67 µg/L. Total phosphorus (TP) concentrations were slightly higher in 2017 with an average of 26 µg/L. The higher concentrations occurred while the lake wasn’t thermally stratified in the winter, spring, and fall. The lake met MPCA eutrophication standards in all three parameters in 2017. When comparing the boxplots in Figure 4-5 to those in Appendix A, it becomes obvious that the 2001 alum treatment had a profound effect on parameters measured in Bde Maka Ska, indicating an overall water quality improvement.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-5
Figure 4-5. Bde Maka Ska box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) from 2008-2017. Horizontal lines represent MPCA eutrophication standard for deep lakes. Data from 1991-2017 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-6
BEACH MONITORING
In 2017, bacteria levels were monitored at Bde Maka Ska at three locations: Bde Maka Ska 32nd Street Beach on the east side, Bde Maka Ska Main Beach on the north side, and Bde Maka Ska Thomas Beach on the south side. As shown in Table 4-2 and Figure 4-6, Escherichia coli (E. coli) levels were variable at the beaches in 2017, but all E. coli concentrations at three beaches were below standards and the beaches remained open the entire season. See Section 18 for more information on beach monitoring.
Table 4-2. Summary of E. coli (MPN per 100 mL) data for Bde Maka Ska beaches in 2017.
Statistical Bde Maka Ska Bde Maka Ska Bde Maka Ska Calculations 32nd Beach Main Beach Thomas Beach Number of Samples 13 13 13 Minimum 10 3 1 Maximum 569 678 378 Median 45 41 26 Mean 143 154 98 Geometric Mean 57 51 30 Max 30-Day Geo Mean 101 75 120 Standard Deviation 200 230 121
Figure 4-7 illustrates the box and whisker plots of E. coli monitoring results for Bde Maka Ska beaches from 2008 to 2017. The box and whisker plots show the variability in the dataset over the past 10 years. The 2017 E. coli results were typical at 32nd Beach and were higher at Main Beach and Thomas Beach. Thomas Beach had higher E. coli concentrations for the fourth straight year.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-7
Figure 4-6. 2017 E. coli concentrations at the Bde Maka Ska beaches. Blue line is the running 30- day geometric mean. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y-axis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-8
Figure 4-7. Box and whisker plots of E. coli concentrations (MPN per 100 mL) for Bde Maka Ska beaches from 2008-2017. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y- axis. From 2008-2009 E. coli concentrations were determined as colony forming units (CFU/100ml).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-9
LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
Figure 4-8 shows the 2017 LAURI for Bde Maka Ska. Bde Maka Ska was rated excellent in aesthetics, habitat quality, clarity, and recreational access. Slightly higher bacteria results at Main Beach and Thomas Beach led to a good rating in public health. Details on LAURI can be found in Section 1 and comparisons with other lakes can be found in Section 17.
Bde Maka Ska 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
Habitat Quality
Rec. Access
Figure 4-8. The 2017 LAURI for Bde Maka Ska.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-10
WINTER ICE COVER
Ice came off Bde Maka Ska on March 20, 2017, which was 20 days earlier than average. Lake ice did not fully cover the lake until December 18, 2017, which was only 5 days later than the average. (See Figures 4-9 and 4-10 below).
While there is a lot of fluctuation in the data, there is a significant trend towards an earlier ice-off (p < 0.05) since 1946 (Figure 4-9). The running average ice-off date has shifted to earlier dates, floating around April 13th in the 1970s to April 4th for the past 10 years. The histogram in Figure 4-9 shows the majority of ice-off dates occurring in early to mid-April over the past 70 years, with a few years with early ice-off dates in March.
Figure 4-9. Bde Maka Ska ice-off dates and frequency of the occurrence of ice-off on particular dates for all the years of record. 68 recorded ice-off dates exist since 1946.
Fewer observations for ice-on dates exist for Bde Maka Ska. While there is no significant trend in ice-on date (p > 0.05) since 1962, the five latest ice-on dates have occurred since 2001 (Figure 4-10). The histogram in Figure 4-10 shows Bde Maka Ska is typically frozen in early to mid-December over the past 53 years of observation, with a few ice-on dates in January. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
Figure 4-10. Bde Maka Ska ice-on dates and frequency of the occurrence of ice-on on particular dates for all the years of record. 48 ice-on records exist. 2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-11
EXOTIC AQUATIC PLANT MANAGEMENT
The Minnesota Department of Natural Resources (MDNR) requires a permit to remove or control Eurasian watermilfoil. These permits limit the area from which milfoil can be harvested in order to protect fish habitat. The permits issued to the MPRB allow for harvesting primarily in swimming areas, boat launches, and in areas where public recreational access is needed. In 2017, the permitted area on Bde Maka Ska was 53 acres, which is about 47% of the littoral zone (area 15 feet or shallower). For more information on aquatic plants see Section 1 and Section 20.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton and zooplankton are the microscopic plant and animal life that form the basic food web of lake ecology. Figures 4-11 shows the Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton divisions during 2017.
Water clarity was greater than 2.3 meters for the entire sampling season in 2017, with the greatest transparency in the spring and fall (Figure 4-11a). Secchi transparency closely followed chlorophyll-a concentrations throughout the season (Figure 4-11a, b). Chlorophyll-a concentrations were low throughout the year. The highest algal biomass occurred in late-August (7.5 µg/L) and was characterized by mostly blue-green algae (Cyanophyta; Figure 4-11b, c). The phytoplankton community in Bde Maka Ska was largely a mix of chrysophytes (Chrysophyta), green algae (Chlorophyta), diatoms (Bacillariophyta), cryptomonads (Cryptophyta), and blue green algae (Figure 4-11c). There were more haptophytes in most of the summer samples but were only in high abundance in early-July. Dinoflagellates (Pyrrhophyta) were only present in low numbers during the year.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-12 d
Figure 4-11. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Bde Maka Ska during 2017. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-13
Figure 4-12 shows the zooplankton distribution in Bde Maka Ska sampled throughout 2017. Rotifers were present throughout the year, but they were the most abundant in the spring and fall. Nauplii and juvenile copepods were very abundant in the spring (April-June). Cladocerans were abundant in April, May, September, and November. Similar to the previous three years, there were a increased number of protozoa in mid-summer. Cyclopoids and calanoids were present in low numbers throughout the year.
Figure 4-12. Zooplankton density in Bde Maka Ska during 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-14
FISH STOCKING
Additional information and a definition of fry, fingerling, yearling and adult fish can be found in Section 1.
Table 4-3. Fish stocked into Bde Maka Ska over the past 10 years. Data are from the Minnesota Department of Natural Resources. Asterisk (*) indicates fish purchased and stocked by private citizens and sporting groups. Year Species Number and Size Amount 2017 Walleye 98 yearlings 55 pounds 2017 Walleye 20 adults 32 pounds 2017 Walleye 26 fingerlings 5.2 pounds 2016 Muskellunge 123 fingerlings 21.4 pounds 2015 Walleye 40 fingerlings 2.0 pounds 2015 Walleye 1,613 yearlings 721.4 pounds 2012 Muskellunge 123 fingerlings 24.6 pounds 2012 Walleye 12,684 yearlings 604.0 pounds 2010 Muskellunge 127 fingerlings 21.2 pounds 2009 Tiger Muskellunge* 480 fingerlings 141.2 pounds 2009 Walleye 9991 fingerlings 469.7 pounds 2009 Walleye 248 yearlings 90.0 pounds
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 4-15
5. CEDAR LAKE
HISTORY
Like the other lakes in the Chain of Lakes, Cedar Lake was altered from its natural state when it was dredged between 1911 and 1917. Channels connecting Cedar Lake to Lake of the Isles and to Brownie Lake were created in 1913 and 1916. The Lake of the Isles connection caused the water level in Cedar Lake to drop six feet. The new water elevation changed the shape of the lake most noticeably turning Louis Island on the west side of the lake into a peninsula. Figure 5-1 shows one of Cedar Lake’s three beaches.
A detailed Clean Water Partnership diagnostic study conducted in 1991 determined that phosphorus input to the Chain of Lakes should be reduced to increase water quality. The best management practices (BMPs) were then implemented for Cedar Lake and included constructed wetlands in 1995 and an aluminum sulfate (alum) treatment in 1996. The alum treatment improved phosphorus levels at the surface and the hypolimnion and was predicted to have a treatment life span of at least seven years (Huser, 2005).
Cedar Lake is a kettle lake and is typically dimictic; however, there is evidence that in some years the lake may mix during the late summer and then re-stratify (Lee and Jontz, 1997). Figure 5-2 shows a bathymetric map of Cedar Lake. Table 5-1 shows the Cedar Lake morphometric data.
Figure 5-1. View of Cedar Lake from Main Beach in October 2016.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-1 Table 5-1. Cedar Lake morphometric data.
Surface Mean Watershed: Residence Max Depth Littoral Volume Watershed Area Depth Lake Area Time (m) Area* (m3) Area (acres) (acres) (m) (ratio) (years) 170 6.1 15.5 37% 4.26x106 1,956 11.5 2.7 * Littoral area defined as less than 15 feet deep.
Figure 5-2. Bathymetric map of Cedar Lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-2 LAKE LEVEL
The designated Ordinary High Water Level (OHW) for Cedar Lake is 853 feet above msl. Section 4, Bde Maka Ska includes more information on historic Chain of Lakes water level information.
WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Figure 5-3 shows historical Cedar Lake TSI scores with a linear regression. The 2017 TSI score for Cedar Lake was 57, which was the highest score since 1995 due to higher chlorophyll-a levels, especially in August and September. Restoration efforts begun in 1994 have helped improve water quality in the lake. Although there was an initial decrease in TSI after the completion of the restoration projects, there has been no significant trend in TSI from 1991-2017 (p > 0.1). A detailed explanation of TSI can be found in Section 1.
Figure 5-3. Cedar Lake TSI scores and linear regression from 1991-2017.
BOX AND WHISKER PLOTS
The box and whisker plots in Figure 5-4 show the data distribution for Secchi transparency, chlorophyll-a, and total phosphorus for Cedar Lake for the past decade. Horizontal lines on the graphs indicate the MPCA deep lake standards. A detailed explanation of box and whisker plots can be found in Section 1. Box and whisker plots for the entire period of record, 1991-2017, can be found in Appendix A.
Water transparency in 2017 was similar to the previous 4 years with an average Secchi depth of 1.4 meters. There was greater variability in Secchi transparency in the past and can be seen in Appendix A. Chlorophyll-a was higher in 2017 compared to the previous few years with an average concentration of 16 µg/L. Total phosphorus (TP) concentrations were also higher in 2017 with an average of 41 µg/L. The highest concentrations occurred while the lake wasn’t thermally stratified in the winter and fall. The lake met MPCA eutrophication standard for TP, but exceeded the standard for Secchi transparency and chlorophyll-a in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-3
Figure 5-4. Cedar Lake box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) from 2008-2017. Horizontal lines represent MPCA eutrophication standard for deep lakes. Data from 1991-2017 can be found in Appendix A.
BEACH MONITORING
Escherichia coli (E. coli) levels were monitored at three different locations around Cedar Lake: Cedar Main Beach, Cedar Point Beach, and East Cedar Beach (Hidden) in 2017. All Cedar Lake beaches remained open for the entire 2017 swimming season. As shown in Table 5-2 and Figure 5-5, the season-long geometric means for E. coli were low at all the Cedar Lake beaches. East Cedar Beach was opened as a supervised public beach for the first time in 2007 and has typically had some of the lowest E. coli count values for all MPRB beaches.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-4 Table 5-2. Summary of E. coli (MPN per 100 mL) data for Cedar Lake beaches in 2017.
East Cedar Cedar Statistical Calculations Cedar Main Point Number of Samples 13 13 13 Minimum 1 1 5 Maximum 281 1212 139 Median 16 9 24 Mean 37 105 35 Geometric Mean 15 11 19 Max 30-Day Geo Mean 28 20 28 Standard Deviation 74 333 43
Figure 5-5. 2017 E. coli concentrations at the Cedar Lake beaches. Blue line is the running 30- day geometric mean. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y-axis.
Figure 5-6 shows box and whisker plots of E. coli monitoring results for 2008 to 2017. The box and whisker plots show the variability in bacteria levels over the past 10 years. All three Cedar Lake beaches had comparable levels to previous years in 2017. Additional information on beach monitoring can be found in Section 18.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-5
Figure 5-6. Box and whisker plots of E. coli concentrations (MPN/100 mL) for Cedar Lake beaches from 2008-2017. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scales on each y-axis. From 2008-2009 E. coli concentrations were determined as colony forming units (CFU/100ml).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-6 LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
The 2017 LAURI for Cedar Lake is presented in Figure 5-7. Cedar Lake scored excellent in aesthetics, habitat quality, public health, and recreational access and poor in water clarity. See Section 1 for details on the LAURI index.
CEDAR LAKE 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
Habitat Quality
Rec. Access
Figure 5-7. The 2017 LAURI for Cedar Lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-7 WINTER ICE COVER
Ice came off Cedar Lake on March 24, 2017, which was 13 days earlier than average. Ice was back on the lake by December 8, 2017, which was 4 days later than the average ice-on date. See Section 1 for details on winter ice-cover records and Section 17 for a comparison with other lakes.
EXOTIC AQUATIC PLANT MANAGEMENT
The MDNR requires a permit to remove or control Eurasian watermilfoil. The permit limits the area from which milfoil can be harvested to protect fish habitat. The permits issued to the MPRB allowed for harvesting primarily in swimming areas, boat launches, and shallow areas where recreational access was necessary. In 2017, the permitted area on Cedar Lake was 19 acres, which is approximately 28% of the littoral zone of the lake (area shallower than 15 feet). See Section 1 for details on aquatic plants.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton and zooplankton are microscopic plant and animal life that form the foundation of the food web in lakes. Figure 5-8 shows the Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton divisions during the 2017 sampling season. Figure 5-9 shows the zooplankton distribution over 2017.
Water clarity was between 1 and 2 meters until August, decreased to less than 1 meter for August and early-September, and increased to 2.8 meters after fall turnover (Figure 5-8a). Secchi transparency closely followed Chlorophyll-a concentrations throughout the season (Figure 5-8a, b). Chlorophyll- a concentrations were between 5 and 20 µg/L until August, increased to a maximum concentration of 34.6 µg/L in late-August, and decreased to 6.5 µg/L in the fall. Blue-green algae (Cyanophyta) were the most abundant division throughout 2017 (Figure 5-8c). The remainder of the phytoplankton community in Cedar Lake was largely a mix of cryptomonads (Cryptophyta), chrysophytes (Chrysophyta), diatoms (Bacillariophyta), green algae (Chlorophyta), haptophytes, and dinoflagellates (Pyrrhophyta).
The zooplankton distribution in Cedar Lake throughout 2017 is shown in Figure 5-9. Rotifers, a group of small zooplankton, were in high abundances in April and May. Nauplii and juvenile copepods were also very abundant in the spring samples and their numbers decreased as the year went on. Cladocerans were present in all samples but were at their highest densities in May and September. Calanoids, cyclopoids, and protozoa were present in low numbers in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-8
Figure 5-8. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Cedar Lake during 2017. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-9
Figure 5-9. Zooplankton density in Cedar Lake during 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-10 FISH STOCKING
Additional information and a definition of fry, fingerling, yearling, and adult fish sizes can be found in Section 1.
Table 5-3. Fish stocked into Cedar Lake over the past 10 years. Data are from the Minnesota Department of Natural Resources. Asterisk (*) indicates fish purchased and stocked by private citizens and sporting groups. Year Species Number and Size Amount 2016 Muskellunge 63 fingerlings 10.9 pounds 2015 Walleye 167 yearlings 136.1 pounds 2013 Walleye 3,640 fingerlings 146.0 pounds 2012 Muskellunge 63 fingerlings 12.6 pounds 2011 Walleye 3,828 fingerlings 136.7 pounds 2010 Muskellunge 67 fingerlings 11.2 pounds 2009 Walleye 2,835 fingerlings 92.7 pounds 2009 Walleye 115 yearlings 23.0 pounds
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 5-11 6. DIAMOND LAKE
HISTORY
Diamond Lake is a small shallow water body predominantly surrounded by residential neighborhoods and parkland (Figure 6-1). The National Wetlands Inventory classifies Diamond Lake as a permanently flooded lacustrine/limnetic system with an unconsolidated bed (L1UBH). The fringe of Diamond Lake is classified as palustrine semipermanently flooded wetland with emergent vegetation (PEMF) (USFWS, 2012).
Figure 6-1. Diamond Lake in August 2017.
Diamond Lake and surrounding park areas were donated to the Minneapolis Park and Recreation Board (MPRB) between 1926 and 1936. In 1937, a project was proposed to dredge Diamond Lake, generating fill to deposit in Pearl Lake to create Pearl Park. However, the Board voted against the project and decided to use fill from airport properties instead. A drain from Pearl Park was installed to divert water to Diamond Lake and prevent flooding in the park.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 6-1 Water levels in Diamond Lake have fluctuated due to land use changes in the surrounding watershed. In 1940, the City of Minneapolis installed storm sewers and by 1941, 800 acres of developed land was draining into Diamond Lake causing drastic water elevation fluctuations. In 1942, the Works Progress Administration (WPA) constructed an overflow to control water elevation and an outflow pipe that carried water from the northeast shore to Minnehaha Creek. Construction of Interstate 35W during the 1960s added several miles of highway runoff to Diamond Lake. In 1991, the MPRB placed a weir at 822.0 ft msl allowing for higher water than the previous outlet, which was 820.1 ft msl. The increase in water elevation was made to encourage establishment of aquatic plants and to restore wildlife habitat in Diamond Lake.
In 1953, the Minnesota Department of Natural Resources (MDNR) completed a water quality survey and determined that the lake could not be considered a fish supporting lake due to the lack of oxygen during the winter months (MDNR, 1953). MPRB sampling has confirmed that Diamond Lake freezes to the bed during some winters. In 2007, construction began on the 35W/HWY62 improvement project that changed the drainage areas in the Diamond Lake watershed. Figure 6-2 shows a map for Diamond Lake. Table 6-1 shows morphometric data for Diamond Lake.
Table 6-1. Diamond Lake morphometric data.
Surface Mean Watershed: Max Littoral Volume Watershed Area Depth Lake Area Depth (m) Area* (m3) Area (acres) (acres) (m) (ratio) 41 0.9 2.1 100% 7.15x104 669 16.3
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 6-2
Figure 6-2. Diamond Lake map.
LAKE LEVEL
The lake level for Diamond Lake is measured at a gage near the Diamond Lake Lutheran Church and results are shown in in Figure 6-3. The designated Ordinary High Water Level (OHW) for Diamond Lake is 822 feet above mean sea level. Lake levels were below than the OHW for much of 2017. Only one measurement in early-October showed the water level to be above the OHW. This reading followed heavy rain during the previous two days. Lake levels quickly dropped and the lake froze slightly below its ordinary high water level in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 6-3
Figure 6-3. Diamond Lake levels from 2000-2017. Horizontal line represents the Diamond Lake ordinary high water elevation (822 ft msl).
WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Figure 6-4 shows the TSI scores and linear regression from 1992–2017 at Diamond Lake. A detailed explanation of TSI can be found in Section 1. Carlson’s TSI Index would classify Diamond Lake as eutrophic; however, the index was developed for lakes without non-algal turbidity and with low macrophyte populations. Diamond Lake does not meet these criteria. It is a fertile, very shallow water body with high non-algal turbidity and thick aquatic plant beds. Secchi depth was not used in TSI calculations of Diamond Lake, since the lake is often either clear to the bottom or the Secchi disk is obscured by dense aquatic plant growth. The 2017 TSI score calculated using chlorophyll-a and total phosphorus concentrations for Diamond Lake was 61.
In 2004, the sampling location changed from a grab sample off a dock on the northeast side of the lake to a grab sample over the deep spot in the southern part of the lake from a canoe. There is no significant trend in the TSI score for Diamond Lake from 1992-2017 (p > 0.1); however, there is a significant decrease in TSI score from 2004-2017 (p < 0.001) indicated by the red line in Figure 6-4. This phenomenon could be due to the change in sampling location or to improvements due to water quality infrastructure constructed for the 35W/HWY62 project.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 6-4
Figure 6-4. Diamond Lake TSI scores and linear regression from 1992 to 2017. The linear regression line for the entire record is colored blue, while the linear regression line since 2004 is colored red.
BOX AND WHISKER PLOTS
The box and whisker plots in Figure 6-5 show the data distribution for chlorophyll-a and total phosphorus levels in Diamond Lake over the past ten years. Box and whisker plots for the entire period of record, 1992-2017, can be found in Appendix A. A detailed explanation of box and whisker plots can be found in Section 1.
Diamond Lake has limited Secchi transparency data due to its shallowness and high macrophyte density. No Secchi disk readings were taken in 2017 due to either the water being clear to the bottom or the Secchi disk was obscured by thick aquatic plant growth. Chlorophyll-a concentrations were lower in 2017 for the second consecutive year, with an average of 16.4 µg/L. Similarly, total phosphorus (TP) concentrations also lower in 2016 and 2017 compared to previous years. Thick macrophyte growth, especially coontail and lily pads, and filamentous algae were noted during most sampling trips in 2017.
Generally, data from Diamond Lake is more variable and contains more variability than deeper lakes. Increased variability in the Diamond Lake data could be influenced by seasonal water level changes and stormwater influx.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 6-5
Figure 6-5. Box and whisker plots of Diamond Lake Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) from 2008-2017. Data from 1992-2017 can be found in Appendix A.
WINTER ICE COVER
Ice came off Diamond Lake on March 20, 2017, 12 days earlier than average. Ice came back on to Diamond Lake on December 12, 2017, 12 days after the average ice-on date. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
PHYTOPLANKTON
Phytoplankton are microscopic plant life that form the foundation of the food web in lakes. In Figure 6-6 shows the chlorophyll-a concentrations and relative abundance of phytoplankton divisions during 2017 in Diamond Lake. Zooplankton are not sampled at Diamond Lake.
Chlorophyll-a concentrations varied in 2017, ranging from 3.2 µg/L in the winter to 43 µg/L in late- July (Figure 6-6a). The phytoplankton community was diverse and experienced a lot of turnover in 2017 (Figure 6-6b). Blue-green algae (Cyanophyta) comprised the majority of the winter sample. Cryptomonads (Cryptophyta), euglenoids, green algae (Chlorophyta), chrysophytes, and diatoms (Bacillariophyta) made up much the spring samples. The phytoplankton community switched to mostly green algae, cryptomonads, blue-green algae, and euglenoids in July-September. The fall
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 6-6 sample was predominantly chrysophytes. Dinoflagellates (Pyrrhophyta) and haptophytes were present in some samples, but never comprised more than 10% of the phytoplankton community. Unlike most of the other MPRB lakes, euglenoids were present at high levels in the late summer. Euglenoids are commonly found in waters rich in nutrients and organic matter around sediments and macrophytes. Also, unlike most other Minneapolis lakes, blue-green algae were only present at low levels throughout the summer. Diamond Lake contains high levels of dense plant growth and the phytoplankton collected may partially reflect the community of organisms living attached to plants as well as the free-floating algae community found in most of the other sampled lakes.
Figure 6-6. Chlorophyll-a concentration (a) and relative abundance of phytoplankton (b) in Diamond Lake during 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 6-7 WETLAND HEALTH EVALUATION PROJECT (WHEP)
The wetland fringe of Diamond Lake was evaluated by the Wetland Health Evaluation Project (WHEP) led by Hennepin County and a group of citizen volunteers. Results of the wetland evaluation are presented in Section 21. 2017 was the twelfth year that Diamond Lake was evaluated in the WHEP program.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 6-8 7. GRASS LAKE
HISTORY
Grass Lake was created during the construction of State Highway 62. The highway separated one waterbody into two new lakes: Grass Lake to the north and Richfield Lake to the south. The National Wetlands Inventory classifies Grass Lake as a permanently flooded lacustrine/littoral system with an unconsolidated bed (L2UBH; Figure 7-1).
Grass Lake was added to the Minneapolis Park & Recreation Board (MPRB) lake sampling program in 2002. It is typically sampled every other year and was not sampled in 2017. All data presented in this chapter is from 2016 and the lake is scheduled to be monitored again in 2018. Morphometric data for the lake is presented in Table 7-1. Figure 7-2 shows a map of Grass Lake.
Figure 7-1. Photograph of geese at Grass Lake in August 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 7-1 Table 7-1. Grass Lake morphometric data. OHW= Ordinary High Water Level.
Surface Area Mean Depth Maximum Watershed Watershed: Lake OHW(msl) (acres) (m) Depth (m) Area (acres) Area (ratio) 27 0.6 1.5 386 14.3 830.9
Figure 7-2. Grass Lake map.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 7-2 WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
The TSI Index is meant to examine lakes without non-algal turbidity and with low macrophyte populations. Grass Lake is a predominantly a permanently flooded lacustrine/littoral system with an unconsolidated bed (L2UBH) wetland. The lake contains extensive macrophytes and is too shallow to measure the Secchi depth; therefore, Secchi depth was not used in TSI calculations for Grass Lake. A detailed explanation of TSI can be found in Section 1.
The 2016 Grass Lake TSI score was 58 and Figure 7-3 shows the Grass Lake TSI scores for 2002- 2016. This data includes samples from three different locations, potentially biasing the results. The original sample location has been inaccessible since 2008 due to a construction project. There is not significant trend in TSI scores over the last 15 years (p > 0.1); however, Grass is only sampled every- other year. It appears as though 2003 was an outlier, as subsequent years have clustered between a TSI score of 55 to 65. Additional years of monitoring will be needed to discern a trend from natural variation seen in Grass Lake.
Figure 7-3. Grass Lake TSI scores and linear regression for monitored years from 2002 to 2016. Note: the sampling location changed in 2008 and again in 2016.
BOX AND WHISKER PLOTS
Figure 7-4 shows box and whisker plots of the Grass Lake data from 2005 to 2016. A detailed explanation of box and whisker plots can be found in Section 1. Data from the entire period of record in box and whisker format can be found in Appendix A.
Secchi readings are not taken due to the shallowness of the wetland. Grass Lake can freeze to the bed in some years, making it impossible to collect a winter sample. Variations in the Grass Lake data may be due to climatic differences, the monthly sampling regime, or the variability of the wetland. Chlorophyll-a, total phosphorus, and total nitrogen are all similar to previous years. The 2016 chlorophyll-a concentrations were low the entire season, with a maximum value of 11.6 µg/L in October. Total phosphorus was relatively high, with concentrations ranging from 45 to 133 µg/L.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 7-3
Figure 7-4. Grass Lake box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus(c) from 2007-2016. Data from 2002-2016 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 7-4 WINTER ICE COVER
Ice came off Grass Lake on March 20, 2017, 11 days earlier than average for the lake since records began in 2005. Ice was back on Grass Lake on December 8, 2017, 7 days later than average. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
PHYTOPLANKTON
Phytoplankton are microscopic plant life that forms the foundation of the food web in lakes. Figure 7-5 shows the concentration of chlorophyll-a and the relative abundance of phytoplankton divisions in Grass Lake for the 2016 sampling season. Chlorophyll-a levels were low (< 12.6 µg/L) throughout the open water season (Figure 7-5a). Cryptomonads (Cryptophyta) were the most abundant division throughout the summer. Euglenoids and diatoms (Bacillariophyta) were abundant in the spring, but only present in low numbers the rest of the year. Blue-green algae were at low abundance throughout the season (Figure 7-5b). The Grass Lake phytoplankton community is similar to the community at Diamond Lake (Section 6).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 7-5
Figure 7-5. Chlorophyll-a concentration (a) and relative abundance of phytoplankton (b) in Grass Lake during 2016.
WETLAND HEALTH EVALUATION PROJECT (WHEP)
The wetland fringe of Grass Lake was evaluated by the Wetland Health Evaluation Project (WHEP) led by Hennepin County and a group of citizen volunteers in 2017. Results of the wetland evaluation are presented in Section 21. 2017 was the third year that Grass Lake was evaluated in the WHEP program and the first since 2004.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 7-6 8. Lake Harriet
HISTORY
Lake Harriet is named after Harriet Lovejoy Leavenworth, the wife of Colonel Leavenworth. Colonel W.S. King donated a majority of the lake (360 acres) and surrounding areas (55 acres) to the Minneapolis Park & Recreation Board (MPRB) in 1885. The MPRB acquired the remainder of the surrounding land between 1883-1898 and 1921.
Lake Harriet is a deep kettle lake that generally remains strongly stratified from May through October. The lake offers many recreational activities including sailing, swimming, and fishing. Park patrons enjoy concerts at the bandshell and the many gardens surrounding the lake. In 2006, both of the MDNR-funded floating docks in Lake Harriet were extended. The lake is shown below in Figure 8-1. Figure 8-2 shows a bathymetric map and Table 8-1 shows the morphometric data for Lake Harriet.
Figure 8-1. Lake Harriet in August 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-7 There was less dredging and filling at Lake Harriet compared to the other MPRB lakes. A marshland on the northeast corner of the lake was filled to make room for the parkway. The wetland at the north end of the lake that is now Robert’s Bird Sanctuary was deemed too expensive to fill. A proposed channel connecting Lake Harriet with Lake Calhoun was never constructed due to the 5- foot elevation difference between the upper Chain of Lakes and Harriet. Today, after several modifications to the inlet and outlet, there is a 4-foot difference between the two lakes.
Figure 8-2. Bathymetric map of Lake Harriet.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-8 Table 8-1. Lake Harriet morphometric data.
Surface Mean Watershed: Max Depth Littoral Volume Watershed Residence Area Depth Lake Area (m) Area* (m3) Area (acres) Time (years) (acres) (m) (ratio) 353 8.7 25.0 25% 1.25x107 1,139 3.2 3.4 * Littoral area defined as less than 15 feet deep.
In 1967, a pumping station and pipeline were constructed between Lakes Harriet and Calhoun in order to control water levels in the upper Chain. In 1999, it was replaced with a gravity outlet, open channel, and pipe connection. The inlet into Lake Harriet consists of a pipe under the water near the boat launch on the northeast corner of the lake. Lake Harriet discharges to Minnehaha Creek through a submerged pipe located at the southern edge of the lake.
Brugam and Speziale (1983) analyzed sediment cores and determined that European-American settlement in the 1850s led to increased sedimentation rate due to land clearing and agriculture. Diatom reconstruction of total phosphorus suggests that pre-European phosphorus levels were around 20 µg/L. However, increases in stormsewer discharge since the 1920s led to increased phosphorus levels that peaked in the 1970s. Recent observed data have shown a decline in phosphorus levels since the 1990s and suggest concentrations in Lake Harriet have returned to levels similar to pre- European settlement (Heiskary et al., 2004).
Restoration techniques and best management practices (BMPs) have improved water quality in Lake Harriet. A detailed Clean Water Partnership diagnostic study conducted in 1991 determined that phosphorus input to the Chain of Lakes should be reduced to improve water quality. BMPs implemented included: public education, increased street sweeping, constructed wetlands (1998), and grit chambers (1994-1996). In 2001, an alum treatment was also carried out on areas of the lake shallower than 25 feet to control filamentous algae growth in the littoral zone by limiting the available phosphorus. Not originally intended to do so, the alum had an unexpected benefit of limiting internal phosphorus loading in the lake (Huser, 2005). Current trophic state index (TSI) scores confirm that the BMPs have positively affected water quality in Lake Harriet.
In 2010, the MPRB and the City of Minneapolis received a Clean Water Partnership Grant to complete a diagnostic study of Lake Harriet to update and intensify existing studies at the lake and provide planning toward implementing a second-phase of improvements for water quality.
LAKE LEVEL
The lake level for Lake Harriet is recorded weekly and is shown in Figure 8-3. The ordinary high water level (OHW) determined by the MDNR for Lake Harriet is 848 ft msl. The designated OHW is the highest regularly sustained water level that has made a physical imprint on the land, marked by either a transition in vegetation or a physical characteristic. The lake was above the OHW briefly in the spring, but remained below 848 ft msl for the rest of 2017.
See Section 17 for a comparison between other MPRB lake levels.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-9
Figure 8-3. Lake levels for Lake Harriet from 1971 to 2017. Horizontal line represents the Lake Harriet ordinary high water elevation (848 ft msl).
WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Figure 8-4 shows historical Lake Harriet TSI scores and linear regression. Lake Harriet experienced a few years with lower TSI scores following a littoral alum treatment in the mid-2000s, but has remained fairly stable the last 10 years. Lake Harriet’s 2017 TSI score was 45, which classifies the lake as mesotrophic with moderately clear water and some algae. There has been a decrease in TSI scores from 1991-2017. The lake remains in the top 25% of TSI scores in this ecoregion (based on calculations from the Minnesota Pollution Control Agency, using the Minnesota Lake Water Quality Data Base Summary, 2004). A detailed explanation of TSI can be found in Section 1.
Figure 8-4. Lake Harriet TSI scores and linear regression from 1991-2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-10 BOX AND WHISKER PLOTS
The box and whisker plots in Figure 8-5 show the data distribution for Secchi, chlorophyll-a, and total phosphorus sampling for the past ten years. MPCA deep lake standards are indicated by a horizontal line across the box plot graphs. A further detailed explanation of box and whisker plots can be found in Section 1. Appendix A contains box plots of data for all the years of record, 1991- 2017.
Water transparency in 2017 was similar to 2009-2013 and 2016 with an average Secchi depth of 4 meters. Chlorophyll-a was low throughout the year with an average concentration of 4.55 µg/L. Total phosphorus (TP) concentrations were similar to previous years with an average of 37 µg/L. The higher concentrations occurred while the lake wasn’t thermally stratified in the winter, spring, and fall. Lake Harriet met MPCA eutrophication standards in all three parameters in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-11
Figure 8-5. Lake Harriet box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus(c) from 2008-2017. Horizontal lines represent MPCA eutrophication standard for deep lakes. Data from 1991-2017 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-12 BEACH MONITORING
Escherichia coli (E. coli) levels were sampled at two different locations on Lake Harriet: Harriet Main Beach and Harriet Southeast Beach. As shown in Table 8-2 and Figure 8-6, E. coli counts were low for the most of beach season. Neither Lake Harriet beach closed in 2017 due to high bacteria levels.
Table 8-2. Summary of E. coli (MPN per 100 mL) data for Lake Harriet beaches in 2017.
Statistical Harriet Harriet Calculations Main SE Number of Samples 13 13 Minimum 3 3 Maximum 76 91 Median 11 11 Mean 19 21 Geometric Mean 12 12 Max 30-Day Geo Mean 19 16 Standard Deviation 20 26
Figure 8-6. 2017 E. coli concentrations at the Lake Harriet beaches. Blue line is the running 30-day geometric mean. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y-axis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-13 Figure 8-7 illustrates the box and whisker plots of E. coli sampling results for Lake Harriet beaches for the past ten years. The E. coli results from 2017 at both Harriet Main Beach and Harriet Southeast Beach were typical compared to previous years. Harriet Southeast Beach tends to have more variable E. coli concentrations than Harriet Main Beach. Further details on MPRB beach monitoring can be found in Section 18.
Figure 8-7. Box and whisker plots of E. coli concentrations (MPN/100 mL) for Lake Harriet beaches from 2008-2017. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y-axis. From 2008-2009 E. coli concentrations were determined as colony forming units (CFU/100ml).
LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
Figure 8-8 shows the 2017 LAURI for Lake Harriet. Lake Harriet ranked excellent in aesthetics, water clarity, habitat quality, public health, and recreational access. Details on the LAURI can be found in Section 1.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-14 LAKE HARRIET 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
Habitat Quality
Rec. Access
Figure 8-8. The 2017 LAURI for Lake Harriet.
WINTER ICE COVER
Ice went out on Lake Harriet on March 20, 2017, which was 17 days earlier than average. Ice did not completely cover Lake Harriet for the season again until December 18, 2017, which was 5 days later than the average ice-on date. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-15 EXOTIC AQUATIC PLANT MANAGEMENT
The MDNR requires a permit to remove or control Eurasian watermilfoil. These permits limit the area milfoil can be harvested in order to protect fish habitat. The permits issued to the MPRB allowed for harvesting primarily in swimming areas, boat launches and in shallow areas where recreational access was necessary. The permitted area for Eurasian water milfoil harvest on Lake Harriet was 40 acres, which is 45% of the littoral zone of the lake (area shallower than 15 feet). More information on aquatic plants can be found in Section 1 and Section 20.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton and zooplankton are the microscopic plants and animals that form the foundation of the food web in lakes. Figure 8-9 shows the Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton division during the 2017 sampling season.
Water clarity was greater than 2.5 meters for the entire sampling season in 2017, with the greatest transparency in the spring (8 meters; Figure 4-11a). Chlorophyll-a concentrations were low throughout the season. The highest algal biomass occurred in late-June (9.2 µg/L) and was characterized by mostly blue-green algae (Cyanophyta; Figure 4-11b, c). The phytoplankton community in Lake Harriet was largely a mix of cryptomonads (Cryptophyta), green algae (Chlorophyta), chrysophytes (Chrysophyta), and diatoms (Bacillariophyta) in the spring. From late- May through September, blue-green algae were the most abundant division with a mix of cryptomonads, green algae, and dinoflagellates (Pyrrhophyta). There were a small number of haptophytes in some of the summer samples. After fall turnover, diatoms comprised over half of the phytoplankton community along with cryptomonads, blue-greens, and green algae (Figure 4-11c).
Zooplankton abundance in Lake Harriet throughout 2017 is shown in Figure 8-10. In general, zooplankton numbers were low for much of the year. Rotifers were present in all samples and were at the highest density in April. Nauplii and juvenile copepods were also present in all the samples and were the most abundant in April. Cladocerans were abundant in April and May and remained a large proportion of the zooplankton community for the rest of the year. Protozoa were abundant in both the July sample. Calanoids and cyclopoids were only present in low numbers.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-16
Figure 8-9. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Lake Harriet during 2017. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-17
Figure 8-10. Zooplankton density in Lake Harriet during 2017.
EVENTS REPORT
On September 8, 2017, a single zebra mussel was found by a MPRB Water Quality staff member in Lake Harriet. The Minnesota Department of Natural Resources (DNR) confirmed the find and has added Lake Harriet to the Infested Waters List for zebra mussels. The listing includes the provision that Lake Harriet may be removed from the list if future surveys continue to show no zebra mussels in the lake.
The adult zebra mussel was discovered on a boat cover recovered from the bottom of Lake Harriet. Following the discovery, MPRB staff worked with the DNR, the Minnehaha Creek Watershed District (MCWD), and contractors to conduct 67 hours of shoreline, snorkel, and scuba surveys around the lake (Figure 8-11). The search focused from the shoreline to approximately the 15-foot depth contour near the boat launch, the sailboat buoy field, and other areas with suitable habitat around the lake. No additional zebra mussels were found during the search effort.
Additionally, two tows for veligers, planktonic larvae of zebra mussels, were conducted, one near the boat launch and one near the outlet. Veligers were not found in either tow. Continued searching will take place at Lake Harriet in the future to track the population of the invasive mussel in the lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-18
Figure 8-11. Map highlighting the areas searched for zebra mussels in Lake Harriet following the discovery of a single zebra mussel in September 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-19 FISH STOCKING
Additional information and a definition of fry, fingerling, yearling and adult size fish can be found in Section 1.
Table 8-3. Fish stocked into Lake Harriet over the past 10 years. Data are from the Minnesota Department of Natural Resources. Asterisk (*) indicates fish purchased and stocked by private citizens and sporting groups. Year Species Number and Size Amount 2016 Muskellunge 85 fingerlings 14.8 pounds 2016 Walleye 916 fingerlings 79.0 pounds 2015 Walleye 165 yearlings 114.0 pounds 2014 Walleye 2,545 fingerlings 114.9 pounds 2013 Walleye 2,890 fingerlings 115.6 pounds 2012 Muskellunge 175 fingerlings 35.0 pounds 2012 Walleye 2,520 yearlings 120.0 pounds 2011 Walleye 3,244 fingerlings 115.9 pounds 2010 Muskellunge 179 fingerlings 29.8 pounds 2010 Walleye 2,862 fingerlings 106.0 pounds 2009 Walleye 2,482 fingerlings 82.6 pounds 2009 Walleye 110 yearlings 22.0 pounds 2008 Muskellunge* 175 fingerlings 38.9 pounds 2008 Walleye 39 adults 117.0 pounds 2008 Walleye 3,234 fingerlings 64.0 pounds
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 8-20 9. LAKE HIAWATHA
HISTORY
Lake Hiawatha was acquired by the Minneapolis Park & Recreation Board (MPRB) in 1923 at a cost of $555,000. At that time, the lake was a shallow wetland named Rice Lake for the stands of wild rice that grew in its shallow waters. Lake Hiawatha was renamed after Henry Wadsworth Longfellow’s poem “Song of Hiawatha” in 1925. Major changes were made to the shape and depth of Lake Hiawatha in the early part of the 20th century in an attempt to improve health and to make it more desirable to build and live near the lake. Beginning in 1929, over 1.25 million cubic yards of material were dredged and relocated to construct Hiawatha Golf Course. Today Lake Hiawatha is part of the Lake Nokomis–Lake Hiawatha Regional Park.
Figure 9-1. Log cribbage board at Lake Hiawatha beach in August 2017.
Figure 9-2 shows the bathymetric map of Lake Hiawatha. Lake Hiawatha has an extremely large watershed due its connection with Minnehaha Creek. The watershed of the lake includes 115,840 acres and the large volume of runoff associated with this area (~97% of the water and ~88% of the phosphorus input to the lake) reduces the residence time of the water in the lake to an average of 11 days or less. The residence time of water in Lake Hiawatha is very short (several days to weeks)compared to most other lakes in Minneapolis that have residence times up to four years (Table 17-1). The limited amount of time the water spends in the lake affects the biology of the system. The most obvious effect is a generally less than expected level of algae in the water based
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-1 on the amount of phosphorus present. The converse of this occurs during seasons with low creek flow (for example 2002, 2007 and 2009) which increased the residence time in the lake and allows excess algae to build up. Table 9-1 shows the morphometric data for Lake Hiawatha.
Flow contributed from the creek and from storm sewer connections have other physical repercussions for Lake Hiawatha. A delta has formed at the point where Minnehaha Creek meets the lake. The water level in Lake Hiawatha varies widely due to fluctuations in the flow of Minnehaha Creek. Additionally, the creek and stormwater inflow can have a destabilizing effect on the thermal stratification of the lake during the summer months.
In 2013, zebra mussels (Dreissena polymorpha) were discovered on a sampling plate in the lake. Zebra mussels had been expected to arrive in Lake Hiawatha within a few years after their discovery in Lake Minnetonka, due to its direct connection with Minnehaha Creek. Future surveys and lake monitoring will indicate whether zebra mussels are altering the ecology of the lake.
Figure 9-2. Bathymetric map of Lake Hiawatha based on data from MCWD.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-2 Table 9-1. Lake Hiawatha morphometric data.
Surface Watershed: Mean Max Littoral Volume Watershed Residence Area Lake Area Depth (m) Depth (m) Area* (m3) Area (acres) Time (years) (acres) (ratio) 54 4.1 7.0 49% 8.95x105 115,840 2145 0.03 *Littoral area defined as less than 15 feet deep.
LAKE LEVEL
Lake levels for Lake Hiawatha are recorded weekly during the open water season. The lake levels for Lake Hiawatha from 1995 to the present are shown in Figure 9-3. Up to four feet of water level bounce can be seen in Lake Hiawatha due to the influence of Minnehaha Creek and the dam at Gray’s Bay in Lake Minnetonka. The Ordinary High Water Level (OHW), as determined by the MDNR, is 812.8 ft msl. Lake levels in 2017 were below the OHW in the early spring but remained above the OHW for much of the year until a dry fall dropped lake levels in November. The lake froze below the OHW.
Figure 9-3. Lake levels for Lake Hiawatha from 1995-2017. Horizontal line represents the Lake Hiawatha ordinary high water elevation (812.8 ft msl).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-3 WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Figure 9-4 shows the Lake Hiawatha linear regression of TSI scores over time. A detailed explanation of TSI can be found in Section 1. The TSI score of Lake Hiawatha mainly reflects the water it receives from Minnehaha Creek. Abnormally high TSI scores seen in the years 2000, 2007, 2009, and 2012 coincide with drought years where Minnehaha Creek was dry for at least a portion of the summer. With all years taken into consideration, Lake Hiawatha has no significant trend in TSI score from 1992 to 2017 (p > 0.1) shown in Figure 9-4. The 2017 TSI score for Lake Hiawatha was
56, which is near the average for lakes in the Central Hardwood Forest ecoregion (MPCA, 2004).
Figure 9-4. Lake Hiawatha TSI scores and liner regression from 1992-2017.
BOX AND WHISKER PLOTS
The box and whisker plots in Figure 9-5 show the variation between years for the Secchi, chlorophyll-a, and total phosphorus data for the past ten years. Lake Hiawatha site specific standards are indicated by a horizontal line on the box plot graphs. The US EPA approved a new 50 µg/L TP standard for Lake Hiawatha in 2013 (US EPA, 2013). A detailed explanation of box and whisker plots can be found in Section 1. Box and whisker plots for data collected since 1992 are available Appendix A.
Water transparency in 2017 was similar to the previous seven years with an average depth of 1.7 meters. Chlorophyll-a was relatively low for the lake in 2017 with an average concentration of 12.27 µg/L. This is typical for a year with a lot of precipitation as Minnehaha Creek flushes the lake. Similarly, total phosphorus levels were low in 2017 with an average concentration of 48 µg/L. The highest phosphorus level occurred in the winter sample. Hiawatha met the site specific standards set by the MPCA for Secchi depth, chlorophyll-a, and total phosphorus.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-4
Figure 9-5. Lake Hiawatha box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) from 2008-2017. Horizontal lines represent Lake Hiawatha site specific eutrophication standards. Data from 1992-2017 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-5 BEACH MONITORING
Bacteria levels were monitored weekly from June through August at Hiawatha Beach in 2017. Escherichia coli (E. coli) levels at the beach fluctuated for much of the swimming season until August, when there were consistently elevated E. coli concentrations (Table 9-2 and Figure 9-6). The beach closed on June 12th due to a single sample exceedance (>1260 MPN/100 mL) and reopened on June 14th when E. coli levels dropped below the single sample threshold. High water was noted at the time of monitoring on June 12th, indicating higher flow in Minnehaha Creek. The beach closed again on August 14th due to another single sample exceedance and reopened on August 16th after tested E. coli concentrations were below standard. Continued elevated E. coli concentrations closed the beach on August 21st due to the 30-day geomean (126 MPN/100 mL) standard being exceeded. The beach continued to exceed the 30-day geomean standard on August 28th and remained closed for the last week of the swimming season. An increase in bird activity at the beach was noted in August, with more bird tracks, feathers, and some poop at the beach, most likely contributed to the high bacteria levels observed at the end of the season. Further details on MPRB beach monitoring can be found in Section 18.
Table 9-2. Summary of E. coli (MPN per 100 mL) data for the Lake Hiawatha beach in 2017.
Statistical Calculations Hiawatha
Number of Samples 13 Minimum 15 Maximum 2420 Median 66 Mean 444 Geometric Mean 99 Max 30-Day Geo Mean 424 Standard Deviation 815
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-6
Figure 9-6. 2017 E. coli concentrations at Hiawatha Beach. Blue line is the running 30-day geometric mean. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y-axis.
Figure 9-7 shows box and whisker plots of E. coli concentrations for the past ten years. The 2017 season had similar E. coli counts compared to previous years and has some of the highest bacteria levels at any of the Minneapolis beaches (Section 18). The highest bacteria levels occurred in late August. The range of results at Lake Hiawatha is larger than at the other lakes in Minneapolis due to the large influence Minnehaha Creek has on the lake’s water quality.
Figure 9-7. Box and whisker plots of E. coli concentrations (MPN/100 mL) for the Lake Hiawatha Beach from 2008 to 2017. Note the log scale on the Y-axis. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). From 2008-2009 E. coli concentrations were determined as colony forming units (CFU/100ml).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-7 LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
The LAURI for Lake Hiawatha is shown in Figure 9-8. In 2017, Lake Hiawatha scored excellent in water clarity, good in aesthetics, habitat quality, and recreational access, and poor in public health. Lake Hiawatha scored good in aesthetics due to low water odor and light brown/green water color. Unfortunately, the lake collects trash flowing down Minnehaha Creek and from stormsewers, especially after large rainstorms. The trash gets deposited along the still shoreline of the lake where it usually remains for the rest of the summer. The current LAURI does not work well to assess the impact of trash on Hiawatha. Details on the LAURI index can be found in Section 1.
LAKE HIAWATHA 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
Habitat Quality
Rec. Access
Figure 9-8. The 2017 LAURI for Lake Hiawatha.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-8 WINTER ICE COVER
Ice came off Lake Hiawatha on March 23, 2017, 12 days earlier than average. Ice returned to the lake for the winter on December 11, 2017, 7 days later than the average ice-on date. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton and zooplankton are the microscopic plant and animal life that form the foundation of the food web. The Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton division during 2017 is shown in Figure 9-9. Water clarity was greater than 1 meter for the entire year, with the greatest transparency in the early-June (Figure 4-11a). Secchi transparency closely followed Chlorophyll-a concentrations throughout the season (Figure 4-11a, b). Chlorophyll-a concentrations fluctuated throughout the season. The highest algal biomass occurred in late-June and early-August (20.6 and 21.5 µg/L respectively) and were mostly characterized by diatoms (Bacillariophyta), chrysophytes (Chrysophyta), cryptomonads, and green algae (Chlorophyta; Figure 4-11b, c). The phytoplankton community in Lake Hiawatha was largely a mix of those divisions along with blue-green algae (Cyanophyta) in some months (Figure 4-11c). Haptophytes, dinoflagellates (Pyrrhophyta) and euglenoids were present in low numbers during the year.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-9
Figure 9-9. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Lake Hiawatha during 2017. Note that the Secchi depth axis is reversed.
Figure 9-10 shows the zooplankton distribution in Lake Hiawatha during 2017. Rotifers were present in all zooplankton tows, but they were in the highest abundance in the spring and fall. Nauplii and Juvenile copepods and cladocerans were also present in all the samples. There were a large number of cladocerans in June and August. Calanoids, cyclopoids, and protozoa were only present in low numbers for much of the year.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-10
Figure 9-10. Zooplankton density in Lake Hiawatha during 2017.
WATER QUALITY PROJECTS
Mitigating Trash Upstream of Lake Hiawatha - Manhole Pilot Project
In November 2017, Surface Water and Sewer Staff retrofitted three manholes upstream of Lake Hiawatha with trash screens as part of ongoing pilot efforts to improve the water quality in lake. The selection of the manholes was informed by a litter surveyed completed earlier in 2017 by staff from the Solid Waste and Recycling Division of Public Works. The three manholes are located in relative proximity to commercial and retail properties where higher volumes of litter have been observed. Consideration was also given to the configuration of the connected storm pipes to minimize the likelihood of street flooding if the pilot failed and caused an obstruction in the pipe.
The trash screens were fabricated by City staff and designed to capture floatable trash and debris that could wash through the city’s storm sewer system. City crews accessed and maintained the manholes by vactoring out all of the debris and trash before it enters Lake Hiawatha. Crews tracked debris removed to assess the success of the pilot project and to inform future water quality improvement efforts.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-11
Figure 9-11. Trash screens installed by City Surface Water and Sewer Staff upstream of Lake Hiawatha to capture trash floating through the stormsewers.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 9-12 10. LAKE OF THE ISLES
HISTORY
Lake of the Isles was named for the four islands that were present in the lake prior to alteration of the park. The original park property consisted of 100 acres of water, 67 acres of wetland, and 33 acres of land. The park was acquired by the Minneapolis Park and Recreation Board in 1886 through purchase, donation, and condemnation. One of the islands had already been eliminated in 1884 by the Chicago Milwaukee and Saint Paul Railway when tracks were laid on fill between Bde Maka Ska and Lake of the Isles. Half a million cubic yards of material were dredged between 1889 and 1911 eliminating a second island and increasing the lake area to 120 acres. The lake was further modified by filling 80 acres of marsh to create parkland, to deepen the North Arm to a uniform depth, and to replace the marshy east side of the lake with an upland shoreline. The connection of Isles to Bde Maka Ska was completed in 1911 and was celebrated by citywide festivities. Lake of the Isles is part of the Chain of Lakes Regional Park which receives nearly 5.7 million visitors year and is the most visited park in Minnesota (Metropolitan Council, 2017).
Figure 10-1. Lake of the Isles in August 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 10-1 The lake was part of the Clean Water Partnership project for the Chain of Lakes and was the focus of multiple restoration activities including grit chambers (1994, 1997, 1999) for stormwater sediment removal, constructed wetland detention ponds for further treatment of incoming stormwater, and a whole lake alum treatment (1997) to limit the internal loading of phosphorus.
Lake of the Isles is a shallow lake with dense stands of macrophytes in shallow areas. The lake is polymictic as it becomes thermally stratified and then periodically mixes due to wind throughout the summer. Figure 10-1 shows Lake of the Isles in fall. Table 10-1 shows the Lake of the Isles morphometric data. Figure 10-2 shows the Lake of the Isles bathymetry.
Figure 10-2. Bathymetric map of Lake of the Isles.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 10-2 Table 10-1. Lake of the Isles morphometric data.
Surface Mean Watershed: MaxDepth Littoral Volume Watershed Residence Area Depth Lake Area (m) Area* (m3) Area (acres) Time(years) (acres) (m) (ratio) 103 2.7 9.4 89% 1.11x106 735 7.1 0.6 *Littoral area defined as less than 15 feet deep.
LAKE LEVEL
The ordinary high water level (OHW) designated by the MDNR for Lake of the Isles is 853 ft msl. The designated OHW is an estimate of the highest regularly sustained water level that has made a physical imprint on the land. This mark may be a transition in vegetation or a physical characteristic. For additional lake level information see Bde Maka Ska in Section 4.
WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Figure 10-3 shows the Lake of the Isles linear regression of TSI scores from 1991 to the present. The Lake of the Isles 2017 TSI score is 59, average for this ecoregion (based on calculations from the Minnesota Pollution Control Agency using the Minnesota Lake Water Quality Data Base Summary, 2004). There has been no significant trend in TSI score since 1991 (p > 0.05). The alum treatment in 1997 coincided with the lowest TSI score for Lake of the Isles, but TSI scores have fluctuated between 52 and 62 since. A detailed explanation of TSI can be found in Section 1.
Figure 10-3. Lake of the Isles TSI scores and linear regression from 1991-2017. The blue square highlights the 1997 alum treatment.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 10-3 BOX AND WHISKER PLOTS
The box and whisker plots in Figure 10-4 show the data distribution for the Secchi, chlorophyll-a, and total phosphorus for the past ten years. MPCA standards are indicated by a horizontal line on the plots. A detailed explanation of box and whisker plots can be found in Section 1 and box and whisker plots from 1991-2017 can be found in Appendix A.
Water transparency in 2017 was typical for the lake. Secchi depths vary throughout the year, ranging from 0.4 meters to 3.6 meters in 2017, with better water clarity in May and June and lower clarity in July, August, and September. Chlorophyll-a concentrations were higher in 2017 compared to the previous three years with an average concentration of 24.33 µg/L. Total phosphorus levels were slightly higher than the previous few years with an average concentration of 47 µg/L. The lake met MPCA eutrophication standards for Secchi transparency and total phosphorus in 2017 but was slightly above the chlorophyll-a standard.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 10-4
Figure 10-4. Lake of the Isles box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) from 2008-2017. Horizontal lines represent MPCA eutrophication standard for shallow lakes. Data from 1991-2017 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 10-5 LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
The LAURI for Lake of the Isles is shown in Figure 10-5. In 2017, Lake of the Isles scored excellent in aesthetics, habitat quality, and recreational access. The lake scored good in water clarity. Since Lake of the Isles does not have a swimming beach, a score was not calculated for public health. For more details on LAURI see Section 1.
LAKE OF THE ISLES 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
NO BEACH
Habitat Quality
Rec. Access
Figure 10-5. The LAURI for Lake of the Isles in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 10-6 WINTER ICE COVER
Ice came off Lake of the Isles on March 22, 2017, 22 days earlier than average and the second earliest ice-off date recorded for the lake. Ice fully covered the lake on December 7, 2017, which was 5 days later than average for Lake of the Isles. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
EXOTIC AQUATIC PLANT MANAGEMENT
The MDNR requires a permit to remove or control Eurasian water milfoil. In order to protect fish habitat, the MDNR permits limit the area from which milfoil can be harvested. The permits issued to the MPRB allowed for harvesting primarily in swimming areas, boat launches, and in shallow areas where recreational access was necessary. The area permitted for milfoil harvesting in Lake of the Isles in 2017 was 38 acres which is just over 40% of the littoral zone (area shallower than 15 feet). See Section 1 and Section 20 for details on aquatic plants.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton and zooplankton are microscopic plant and animal life that form the foundation of the food web in lakes. Figure 10-6 shows the Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton division during 2017. Figure 10-7 shows the abundance of zooplankton groups in 2017.
Water clarity was initially average for the lake (1.4 meters), increased to a season maximum of 3.6 meters in early-June, and decreased to less than 1 meter for the rest of the summer in 2017 (Figure 4-11a). Secchi transparency initially did not follow chlorophyll-a concentrations in the spring, but water clarity decreased as chlorophyll-a increased in July (Figure 4-11a, b). Chlorophyll-a concentrations were low in the spring and through June, quickly increased in July, and decreased in the fall (Figure 4-11b). The highest algal biomass occurred in late-August (52.5 µg/L) and was characterized by mostly blue-green algae (Cyanophyta; Figure 4-11b, c). The phytoplankton community in Lake of the Isles was initially a mix of cryptomonads (Cryptophyta), diatoms (Bacillariophyta), chrysophytes, blue-green algae, haptophytes, haptophytes, and green algae (Chlorophyta). Blue-green algae was the most abundant division from May to September, with the other divisions decreasing in relative abundance. Dinoflagellates (Pyrrhophyta) were present most of the year and were in greater numbers in the summer. The fall sample was predominantly green algae.
The distribution of zooplankton for Lake of the Isles in 2017 is shown in Figure 10-7. Rotifers were present in every zooplankton tow, but they were the most abundant in spring and fall. Nauplii and juvenile copepods and cladocerans were also present in every zooplankton two throughout the year and were most abundant in the spring. Cyclopoids, calanoids, and protozoa were present in low levels in most samples.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 10-7
Figure 10-6. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Lake of the Isles during 2017. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 10-8
Figure 10-7. Zooplankton density in Lake of the Isles during 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 10-9 11. LORING POND
HISTORY
Loring Park was acquired in 1883 as the “Central Park” of Minneapolis. Loring Pond was named in 1890 in honor of Charles M. Loring the first president of the Board of Park Commissioners and is known as the “Father of the Minneapolis Park System.”
The pond’s current configuration was created by connecting two small bodies of water: Jewett Lake and Johnson’s Pond. The smaller north basin of the pond was originally a wetland. In the winter of 1883-1884, peat was sawn out of the frozen ground in order to create a basin that would hold open water. Stormwater diversion has reduced the watershed of Loring Pond to the surrounding 24.1 acres of parkland and has left the lake with a negative water balance; therefore, a groundwater augmentation well is used to maintain water levels.
Figure 11-1 is a photograph of Loring Pond and Figure 11-2 is a map of the pond showing estimated bathymetry. Table 11-1 shows the morphometric data for Loring Pond.
Figure 11-1. Ducks at Loring Pond in fall 2016.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-1
Figure 11-2. Map of Loring Pond showing approximate bathymetry contours.
Table 11-1. Loring Pond morphometric data.
Surface Area Mean Depth Maximum Volume Watershed Area Watershed: Lake (acres) (m) Depth (m) (m3) (acres) Area (ratio) 8 1.5 5.3 4.88x104 24.1 3.0
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-2 Several attempts were made in the 1970s to improve water quality in Loring Pond. An Olszewski tube was installed in an attempt to drain high-nutrient water from beneath the hypolimnion out of the lake. The tube never functioned properly and was abandoned. The pipe was capped in 2014 in an effort to limit water losses from the pond. Dredging of the north arm from 1976 to1977 also did not improve the water quality of the lake. Augmentation of the lake level with groundwater appears to have had a positive effect on water quality and continues today.
Further lake restoration and park improvement projects were initiated in 1997. The lake bottom was sealed, lined, and vented. An aerator was installed to help prevent oxygen depletion during the summer months. Multiple vegetation restoration projects were completed throughout the park. A fishing pier, bike and pedestrian trails, and horseshoe courts were also installed to increase park recreational opportunities. In 1999, the shoreline was planted with native vegetation in cooperation with the Minnesota Department of Natural Resources (MDNR) and the Friends of Loring Park. The native shoreline restoration provided a buffer strip for waterfowl management, protection against shoreline erosion, pollutant filtration, and improved lake aesthetics.
In 2007, the north basin was dredged again to remove accumulated sediment and restore original depths in the channel between the northern and southern basins. In order to accomplish this, the northern basin was dewatered and the water level in the southern basin was lowered. The project had the unintended consequence of stimulating cattail growth that led to a multi-year cattail removal project that the Minneapolis Park and Recreation Board (MPRB) began in 2013 and is ongoing. See Water Quality Projects for more details on the work associated with the latest cattail removal and vegetation restoration project.
LAKE LEVEL
Lake levels for Loring Pond are recorded weekly during ice free conditions and are shown in Figure 11-3 for 1994-2017. The water level in Loring Pond is influenced by an augmentation well that is used to pump groundwater into the lake periodically throughout the year to maintain a consistent level. As the water level was often below the bottom of the lake gauge on the outlet structure, a new auxiliary gauge was installed in 2013.
Dewatering for the North Bay dredging project lowered water levels in Loring significantly in 2007. Stormsewer backflow entered Loring several times in 2010 and 2011 during high-intensity rain events and the largest of these events can be seen as peaks in the level graph. Water pressure from stormsewer backflow caused the Loring Pond outlet to deteriorate. In 2011, MPRB staff repaired the cement at the base of the outlet and re-installed the outlet board. Water levels were manipulated throughout 2014, with water being allowed to drain down throughout the summer and then raised to the top of the outlet wall as part of a cattail removal project. Water levels were then kept near the top of the outlet from 2015 through 2017 by using the augmentation well. See Water Quality Projects for more details.
The ordinary high water level (OHW) designated by the MDNR for Loring Pond is 818.0 ft msl. The designated OHW is an estimate of the highest regularly sustained water level that has made a physical imprint on the land. See Section 17 for a comparison between other MPRB lake levels.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-3
Figure 11-3. Lake levels for Loring Pond from 1994-2017. Water levels frequently dropped below the gage in the 2000s and water levels couldn’t be accurately measured during that time. An auxiliary gage installed in 2013 is able be read at lower lake levels. Horizontal line represents Loring Pond OHW (818.0 ft msl).
AUGMENTATION WELLS
An augmentation well is used to maintain the water levels at Loring Pond. The Minnesota Department of Natural Resources (MDNR) issues the permits and determines pumping limits for augmentation wells. The MPRB staff records groundwater usage monthly. Table 11-2 shows annual usage for the past five years. In 2015 and 1016, an additional 12 million gallons were temporarily permitted for the cattail removal project. In 2017, 5,310,240 gallons out of the 12 million gallon annual permit was pumped into Loring Pond.
Table 11-2. Loring Pond annual pumping volume in gallons.
2013 Total 2014 Total 2015 Total 2016 Total 2017 Total (gal) (gal) (gal) (gal) (gal) 1,378,500 6,871,020 18,732,120 11,447,100 5,310,240
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-4 WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
The 2017 TSI score for Loring Pond was 63. Loring Pond has a TSI score that falls between the 50th and 25th percentile for lakes in the Northern Central Hardwood Forest ecoregion (MPCA, 2004). Figure 11-4 shows the TSI data for Loring Pond along with a linear regression. A detailed explanation of TSI can be found in Section 1.
There is no significant trend in TSI from 1992-2017 in Loring Pond (p > 0.05). Multiple disturbances have occurred at Loring Pond that had large influences on the water quality. Dredging projects that disturbed all or a large portion of the lake occurred in 1997-1998 and during the summer of 2007. Additionally, water levels have been manipulated from 2013-2016 and a large amount of groundwater was pumped into the lake in the summer of 2016 which may have exchanged cleaner groundwater for more nutrient rich lake water leading to a better score.
Figure 11-4. Loring Pond TSI data and linear regression from 1992 to 2017.
BOX AND WHISKER PLOTS
The box and whisker plots in Figure 11-5 show the distribution of data for the Secchi, chlorophyll-a, and total phosphorus measurements for the past ten years. MPCA shallow lake standards are shown as a horizontal line across the box plots. A detailed explanation of box and whisker plots can be found in Section 1. Data presented in box and whisker plot format for the entire period of record can be found Appendix A.
The 303(d) assessment for impaired waters is limited to lakes of ten acres or greater (MPCA, 2014); therefore, Loring Pond is too small (8 acres) to be listed on MPCA’s impaired waters list. However, it is still useful to compare Loring’s data to the shallow lake standards to determine lake water quality. Water transparency decreased for the second consecutive year in 2017 from the clearest water observed in Loring in 2014 and 2015. The average Secchi depth was still greater than 1 meter in 2017. Chlorophyll-a was higher in 2017 compared to the previous three years with an average concentration of 14.76 µg/L. Total phosphorus (TP) concentrations were still high in 2017 with an average of 136 µg/L. The lake was almost completely covered with duckweed on the surface from July through early-September.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-5
Figure 11-5. Loring Pond box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) data from 2008-2017. Horizontal lines represent MPCA eutrophication standard for shallow lakes. Data from 1992-2017 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-6 LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
The LAURI for Loring Pond is shown in Figure 11-6. In 2017, Loring Pond scored good in aesthetics and water clarity. Loring scored poor in habitat quality and recreational access. Loring Pond does not have a swimming beach and was therefore not scored for public health. Details on the LAURI index can be found in Section 1.
LORING POND 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
NO BEACH
Habitat Quality
Rec. Access
Figure 11-6. The 2017 LAURI for Loring Pond.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-7 WINTER ICE COVER
Ice came off Loring Pond on March 21, 2017, 12 days earlier than average ice-off date. Ice came on to the pond on December 7, 2017, 5 days later than the average ice-on date for Loring Pond. Loring Pond is a popular spot for geese, ducks and gulls, and some years waterfowl keep an open hole of water from freezing past normal ice-on. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton and zooplankton are microscopic plant and animal life that form the foundation of the food web in lakes. Figure 11-7 shows the Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton division and Figure 11-8 shows the zooplankton abundance in 2017.
Water clarity was similar for much of 2017 with Secchi depths ranging 0.75 and 1.94 meters. The greatest transparency occurred in late-August and early-September corresponding with some of the lowest Chlorophyll-a concentrations of the year (Figure 4-11a, b). Chlorophyll-a concentrations fluctuated throughout the year. The highest algal biomass occurred in the winter, early-July, and November around 24 µg/L (Figure 4-11b). There was a lot of turnover in the phytoplankton community in Loring Pond in 2017. The winter sample was mostly comprised of diatoms (Bacillariophyta) and cryptomonads. Cryptomonads were the most abundant division in April along with some chrysophytes, diatoms, green algae (Chlorophyta), and blue-green algae (Cyanophyta). May was a mix largely of diatoms and cryptomonads in the early part of the month and mostly chrysophytes later in the month. Dinoflagellates (Pyrrhophyta) were a large percentage of the phytoplankton community in early-June along with some diatoms and green algae. The rest of the year was largely a mix of green algae, diatoms, cryptomonads, and chrysophytes (Figure 4-11c).
Zooplankton density at Loring Pond in 2017 is shown in Figure 11-8. A high number of rotifers were present in April, May, June, and September. Rotifers made up the entire zooplankton sample in May. Nauplii and juvenile copepods were abundant in July and September. Cladocerans were present in every sample except for May and were the most abundant in September. Cyclopoids were present in April, July, August, and September.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-8
Figure 11-7. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Loring Pond during 2017. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-9
Figure 11-8. Zooplankton density in Loring Pond during 2017.
FISH STOCKING
Additional information and a definition of fry, fingerling, yearling, and adult fish sizes can be found in Section 1.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-10 Table 11-3. Fish stocked into Loring Pond over the past 10 years. Data are from the Minnesota Department of Natural Resources. Year Species Number and Size Amount 2017 Channel Catfish 100 adults 200.0 pounds 2016 Channel Catfish 108 adults 194.6 pounds 2014 Black Crappie 92 adults 51.1 pounds 2014 Bluegill 35 adults 10.3 pounds 2014 Channel Catfish 70 adults 107.7 pounds 2011 Black Crappie 79 adults 21.9 pounds 2011 Bluegill 329 adults 70.0 pounds 2011 Channel Catfish 28 adults 26.1 pounds 2010 Black Crappie 108 adults 20.0 pounds 2010 Bluegill 402 adults 67.0 pounds 2010 Channel Catfish 50 adults 147.0 pounds 2009 Black Crappie 102 adults 32.0 pounds 2009 Bluegill 403 adults 84.0 pounds 2008 Black Crappie 200 adults 44.0 pounds 2008 Bluegill 400 adults 81.0 pounds 2008 Channel Catfish 50 adults 231.0 pounds
WATER QUALITY PROJECTS
In the summer of 2012, MPRB contracted with Applied Ecological Services (AES) to begin a multi- year project to reduce the cattail monoculture in a select area on the South Bay of Loring Pond. Working under MnDNR Aquatic Plant Permits, the 2012-2014 project included removal of hybrid and narrow-leaf cattail in a 15-foot area in front of the outlet structure, an area 25 feet in either direction from the center point of the dock, and a 100-foot long restoration area on the south shore. The 100 foot restoration area had cattails removed and the area planted with native aquatic emergent vegetation.
In the fall of 2014, the AES contract was expanded to include cutting as many cattails as possible beneath the water surface. It was anticipated that cutting cattails during this timeframe would cause the cattails to suffocate and either completely kill or reduce the cattail population for the 2015 growing season. AES found, during the fall 2014 project, that the North Bay was predominantly a floating mat of cattails and there were floating cattail mats in the South Bay as well. The floating cattail mats will float higher in the water when cattails are cut; therefore, it was impossible to keep the floating cattail mats below the water. The fall 2014 project also discovered that there were many cattails growing in shallow water and into park land shoreline, neither of which could be cut beneath the surface of the water.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-11 Minnesota State Legislative action passed in 2014, “authorized [the MPRB] to remove all hybrid and narrow-leaved cattails by mechanical removal and chemical control at Loring Lake…and replant the shoreland with native species…” (2014 Minnesota Session Laws, Chapter 290, Sec. 60).
As a result of the Legislative action, the MPRB solicited Request for Proposals in early 2015 to implement a larger project to control cattails and replanting with native aquatic emergent vegetation into both the South and North Bays of the lake. The MPRB entered into a contract with AES for three years (2015-2018). Due to the complexity and high cost of removing the large cattail mat in the North Bay, the project scope was changed. AES work in the North Bay was only for cattail control during the 2015 growing season with removal of cattail stems from the floating mat during the winter of 2015-2016.
The fall 2014 below water cutting was found to be a very successful method to control cattails in open water areas. A second cutting was necessary in some areas, and this work was done by the contractor in August 2015 using brush saws, loppers, and hand pruners either from a boat or shore. Herbicide treatments were applied to the floating mats and to cattails that were growing in saturated shoreline soils in early September 2015. Work in the North Bay included below water cutting and herbicide treatment of the floating mat during the 2015 growing season.
A good amount of native emergent plants that were part of the 1999 shoreline planting project were found to have survived once the cattails were removed. Most notably, large patches of sweet flag on the north end of the South Bay remained intact.
In January 2016, AES cut dead cattail stems at ice level from the South and North Bay floating mats. The cattail debris was hauled to a composting facility. In early March 2016, Forestry staff and a MPRB contractor used large equipment to attempt to break up and pull the floating mat out of the North Bay. The equipment reach was approximately 20 feet and a very small amount of the North Bay floating mat was removed. AES continued work on cattail control in the South Bay during the 2016 growing season. Removing floating mats in late May 2016, pulling and cutting cattails and spot herbicide treatments were the cattail control activities on the South Bay.
In July 2016, AES planted 5,000 plugs of a variety of native aquatic emergent plants into the South Bay of the pond. AES and MPRB staff agreed that additional fencing should be placed around the plantings to protect them from Canada goose herbivory. This resulted in a double layer fence around the South Bay planting area, which will remain until it is determined the plants are well-established and no longer threatened by herbivory.
In 2017, AES continued the control of cattails by pulling, cutting, and select spot herbicide treatments. Additional maintenance of the 2016 and 2013 native aquatic emergent plantings in the South Bay was also performed. In August 2017, MPRB staff amended the contract with AES to remove the upland buffer planting from the contract due to public concerns over herbicide treatments in parks. The amendment to the contract included an additional herbicide treatment of the North Bay floating cattail mat, which was done in September 2017. The amendment also included removal of the floating cattail mat cattail stems when ice was on the lake in the winter of 2017-2018. Remaining contract funds will be used to control cattails and maintain the emergent plantings until the contract end in December 2018.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 11-12 12. LAKE NOKOMIS
HISTORY
In 1907, the Minneapolis Park and Recreation Board (MRPB) purchased an area of open water, wetland and a peat bog known as Lake Amelia, later renamed Lake Nokomis. At that time, wetlands were viewed as unsanitary, so Theodore Wirth developed a plan to make the area more desirable for development and to protect public health. Dredging began in 1914, moving nearly 2.5 million cubic yards of material to increase the park by 100 acres, create beaches, solid shoreline, and parkways around the lake. The new parkland ended up settling, as Wirth predicted, and was corrected by a 1934 Works Progress Administration project.
A photograph of Lake Nokomis is presented below in Figure 12-1. Figure 12-2 is a bathymetric map of Lake Nokomis and Table 12-1 contains morphometric data.
Figure 12-1. Main Beach at Lake Nokomis in August 2017.
Numerous restoration projects have been implemented to improve water quality in the lake. Many projects undertaken were those recommended by the Blue Water Commission: Report and Recommendations for the Management of Lake Nokomis and Hiawatha (BWC, 1998). Carp were seined from the lake during the winter of 2001-02 in order to limit internal phosphorus loading caused by the fish foraging in the sediment. Increased street sweeping, grit chambers, and wetland detention ponds were also implemented in 2001. An inflatable weir was installed in 2002 to prevent nutrients from Minnehaha Creek from entering the lake and was operational in 2003. In 2012, Minnehaha Creek Watershed District (MCWD) replaced it with a more durable fixed weir, which
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-1 allows the lake to overflow during periods of high water, yet still prevent the creek from flowing into the lake. A MCWD-led biomanipulation project began in 2010 at Lake Nokomis, which aimed to reduce sediment disturbance by burrowing fish. While there appears to be a change in the fish community away from burrowing species based on fish surveys, the project may now be having a positive effect on clarity, as there is a lower level of sediment phosphorus release (MCWD, 2013). Future monitoring will continue to show how effective this approach is on water quality in Lake Nokomis.
Lake Nokomis is a shallow polymictic lake, which mixes many times during the growing season. Mixing potential is increased when higher than normal wind speeds occur along the north-south fetch of the lake. This has the effect of destabilizing the water column and mixing hypolimnetic phosphorus into the surface water where it can be utilized by algae near the surface.
Figure 12-2. Bathymetric map of Lake Nokomis based on data collected by the Minnehaha Creek Watershed District.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-2 Table 12-1. Nokomis Lake morphometric data.
Surface Mean Watershed: Max Depth Littoral Volume Watershed Residence Area Depth Lake Area (m) Area* (m3) Area (acres) Time (years) (acres) (m) (ratio) 204 4.3 10.1 51% 3.54x106 869 4.3 4.0 * Littoral area defined as less than 15 feet deep.
LAKE LEVEL
Weekly lake levels at Lake Nokomis from 1999 through 2017 are shown in Figure 12-3. The ordinary high water level (OHW) designated by the Minnesota Department of Natural Resources (MDNR) for Lake Nokomis is 815.4 ft msl. The designated OHW is an estimate of the highest regularly sustained water level that has made a physical imprint on the land. See Section 17 for a comparison between other MPRB lake levels. Nokomis lake levels were very low for several years (2003-2011) due to a combination of factors including: several consecutive drought years, less discharge from the Mother Lake watershed, and the separation from Minnehaha Creek. Higher levels were recorded in 2011-2013 after large snowmelt events and spring rains. Heavy rains between April and June of 2014 resulted in the highest water levels ever recorded in Lake Nokomis. Flooding issues around the lake lasted until fall of 2014. Water levels have been high at Lake Nokomis since that time. The 2017 levels were above the OHW for much of the spring and early-summer and fluctuated around the OHW for the rest of the year. Large rainstorms led to higher lake levels in mid- August and early-October. The lake froze below the OHW in December.
Persistent high groundwater levels in the Lake Nokomis area led to the formation of a multiagency technical team that is attempting to understand:
• Are surface water and groundwater levels near Lake Nokomis, particularly south and west of the lake, increasing? • To what extent do groundwater levels interact with surface water levels in this area? • What are the potential impacts to public and private infrastructure? • If groundwater and/or surface water levels are rising, why and what can be done?
Members of the technical team include: The MPRB, The MDNR, The MCWD, The City of Minneapolis, and the Metropolitan Council Environmental Services (MCEDS). A City of Minneapolis website was created to disseminate information on the issue and the team’s work to the public: http://www.minneapolismn.gov/publicworks/stormwater/nokomisgroundwater.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-3
Figure 12-3. Lake levels for Lake Nokomis from 1999-2017. The horizontal line represents the ordinary high water level elevation (815.4 ft msl) for Lake Nokomis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-4 WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
The Lake Nokomis TSI scores over time are shown in Figure 12-4. Lake Nokomis’s 2017 TSI score was 58. Recent projects in the lake have lowered chlorophyll-a and total phosphorus levels and there has been a significant decrease in TSI scores from 1992 to 2017 (p < 0.05). Nokomis is currently between the 50th and top 25th percentile compared to other lakes in our ecoregion (based on calculations from the Minnesota Pollution Control Agency, using the Minnesota Lake Water Quality Data Base Summary, 2004). A detailed explanation of TSI can be found in Section 1.
Figure 12-4. Lake Nokomis TSI scores and linear regression from 1992-2017.
BOX AND WHISKER PLOTS
Figure 12-5 shows box and whisker plots of Secchi transparency, chlorophyll-a, and total phosphorus for the most recent 10 years of data in Lake Nokomis. Lake Nokomis site specific standards are indicated by a horizontal line on the box plot graphs. The US EPA approved a new 50 µg/L TP standard for Lake Nokomis in 2013 (MPCA, 2011). A detailed explanation of box and whisker plots can be found in Section 1. The box and whisker plots from 1991 to 2017 can be found in Appendix A.
Secchi transparency in 2017 was similar to the previous 10 years with an average Secchi depth of 1.3 meters. Chlorophyll-a concentrations in 2017 were similar to 2016 with an average concentration of 15.52 µg/L. Chlorophyll-a levels have varied over the past 10 years and it appears 2014 and 2015 were abnormally low. There was a wide range of total phosphorus concentrations in 2017 (20-85 µg/L) with the higher levels in the spring and fall (Figure 12-5). The lake met MPCA eutrophication standards for total phosphorus, but it barely exceeded the Secchi transparency and chlorophyll-a - standards in 2017.
A MCWD-led biomanipulation project began in 2010 at Lake Nokomis, which aimed to reduce sediment disturbance by burrowing fish. While there appears to be a change in the fish community away from burrowing species based on fish surveys, the project may now be having a positive effect on clarity as there is a lower level of sediment phosphorus release (MCWD, 2013). Future monitoring will continue to show how effective this approach is on water quality in Lake Nokomis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-5
Figure 12-5. Lake Nokomis box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) data from 2008-2017. Horizontal lines represent Lake Nokomis site specific eutrophication standards. Data from 1992-2017 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-6 BEACH MONITORING
Bacteria levels were monitored at Nokomis Main Beach and Nokomis 50th Street Beach during 2017. As shown in Table 12-2 and Figure 12-6, Escherichia coli (E. coli) levels were low for both beaches in 2017. There were no closures at either beach on Lake Nokomis during the 2017 beach season. Further details on MPRB beach monitoring can be found in Section 19.
Table 12-2. Summary of E. coli (MPN per 100 mL) data for Lake Nokomis beaches in 2017.
Nokomis Nokomis Statistical Calculations 50th Main Number of Samples 13 15 Minimum 2 2 Maximum 161 124 Median 19 29 Mean 34 45 Geometric Mean 19 27 Max 30-Day Geo Mean 28 42 Standard Deviation 45 41
Figure 12-6. 2017 E. coli concentrations at the Lake Nokomis beaches. Blue line is the running 30-day geometric mean. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y-axis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-7 Figure 12-7 shows the box and whisker plots of E. coli monitoring results for Lake Nokomis beaches from 2008 to 2017. The box and whisker plots show the variability in the dataset over the past 10 years. The 2017 E. coli results were typical at both Nokomis 50th Beach and Nokomis Main beach.
Figure 12-7. Box and whiskey plots of E. coli concentrations (MPN/100 mL) for Lake Nokomis beaches from 2008-2017. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y-axis. From 2008-2009 E. coli concentrations were determined as colony forming units (CFU/100ml).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-8 LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
Figure 12-8 shows the LAURI scores for Lake Nokomis. In 2017, the lake scored excellent in aesthetics, public health, and recreation access. Water clarity and habitat quality were scored as good. The typical low water clarity prevents light from penetrating into the water column and limits the amount of plant growth in the lake. See Section 1 for details on the LAURI index.
LAKE NOKOMIS 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
Habitat Quality
Rec. Access
Figure 12-8. The 2017 LAURI Index scores for Lake Nokomis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-9 WINTER ICE COVER
Ice came off Lake Nokomis on March 21, 2017, 14 days earlier than average ice-off. Ice came back on to the lake for the winter on December 11, 2017, which was 9 days later than average for the lake. See Section 1 for detailed winter ice records and Section 17 for comparison with other lakes.
EXOTIC AQUATIC PLANT MANAGEMENT
The MDNR requires a permit to remove or control Eurasian watermilfoil. Permits limit the area from which milfoil can be harvested in order to protect fish habitat. The permits issued to the MPRB allow for harvesting primarily in swimming areas, boat launches and in shallow areas where recreational access is necessary. The permitted area on Lake Nokomis was 15 acres, which is just under 15% of the littoral zone (area shallower than 15 feet). In 2017, approximately 200 pounds of aquatic plants was removed from the beach areas at Lake Nokomis using SCUBA divers. See Section 1 and Section 20 for details on aquatic plants.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton and zooplankton are microscopic plant and animal life that form the foundation of the food web in lakes. Figure 12-9 shows the Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton divisions and Figure 12-10 shows the zooplankton abundance during the 2017.
Water clarity was initially less than 1 meter in the spring, increased to 2.95 meters in late-May, and then decreased to around a meter from July through September (Figure 4-11a). Secchi transparency didn’t reflect chlorophyll-a concentrations throughout the season, suggesting non-algal turbidity has a large influence on water transparency (Figure 4-11a, b). Chlorophyll-a concentrations were below 17 µg/L until August, when chlorophyll-a levels exceeded 30 µg/L. Chlorophyll-a slightly decreased in the fall to around 20 µg/L (Figure 4-11b). Blue-green algae (Cyanophyta) comprised much of the phytoplankton community for most of the year. There was a greater abundance of diatoms (Bacillariophyta), cryptomonads, chrysophytes, and green algae (Chlorophyta) in the spring samples. Dinoflagellates (Pyrrhophyta), euglenoids, and haptophytes were all present in low numbers in 2017 (Figure 4-11c).
The 2017 zooplankton density in Lake Nokomis is shown in Figure 12-10. Rotifers were present the entire year, with high numbers in the spring and fall. Nauplii and juvenile copepod were also present the entire year and were most abundant the spring and September. Cladocerans, the primary grazers of phytoplankton, were present in relatively high numbers for much of the year. Cyclopoids and calanoids were present in small numbers during the year as well.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-10
Figure 12-9. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Lake Nokomis during 2017. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-11
Figure 12-10. Zooplankton density in Lake Nokomis during 2017.
FISH STOCKING
Additional information and a definition of fry, fingerling, yearling and adult fish can be found in Section 1.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-12 Table 12-3. Fish stocked into Lake Nokomis over the past 10 years. Data are from the Minnesota Department of Natural Resources. Asterisk (*) indicates fish purchased and stocked by private citizens and sporting groups. Double asterisk (**) indicates fish purchased by the DNR for stocking. Year Species Number and Size Amount 2017 Walleye 123 fingerlings 152.5 pounds 2016 Tiger Muskellunge 250 fingerlings 89.3 pounds 2015 Walleye 495 yearlings 390.0 pounds 2014 Tiger Muskellunge** 200 fingerlings 41.2 pounds 2013 Walleye 8,476 fingerlings 321.1 pounds 2012 Tiger Muskellunge** 200 fingerlings 61.4 pounds 2012 Walleye* 2,000 yearlings 285.7 pounds 2011 Walleye 9,376 fingerlings 334.9 pounds 2010 Tiger Muskellunge* 200 fingerlings 58.6 pounds 2009 Tiger Muskellunge* 458 fingerlings 104.5 pounds 2009 Walleye 7,718 fingerlings 299.9 pounds
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 12-13 13. POWDERHORN LAKE
HISTORY
Powderhorn Lake was acquired by the Minneapolis Park and Recreation Board (MPRB) in 1890 and was named because its original shape resembled a gun’s powderhorn. Dipper dredge operations were conducted shortly thereafter from 1894 to 1904. Between 1924 and 1925 the south end of the lake was deepened by hydraulic dredging with nearly 150,000 cubic yards of spoils used to fill the north half to create parkland. Powderhorn Lake has always been a very popular neighborhood lake. It has been stocked by the MDNR as a Fishing in the Neighborhood (FiN) lake since 1980. Powderhorn Park hosts several large community events including the May Day Festival and the Powderhorn Art Festival.
Figure 13-1. Blue-green algae in Powderhorn Lake in 2016.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-1 Powderhorn is a shallow lake with an island and one deeper hole at its southeastern end (Figures 13- 1 and 13-2, Table 13-1). Computer modeling indicates the lake was historically eutrophic (MPRB, 1999). Restoration activities were implemented as early as 1975 when a temporary summer aerator was installed to increase oxygen content in deeper water and to prevent fish kills. In 1995, a permanent winter aeration system was installed with the MDNR to provide a refuge for fish and prevent winter fish kills. Lake water levels are occasionally augmented with groundwater.
The MPRB and Minneapolis Public Works developed a major restoration plan for Powderhorn Lake in 1999. In 2001, five continuous deflective separation (CDS) grit chambers were installed to remove solids from stormwater inflow. In 2002, native shoreline plants were installed to improve aesthetics and habitat, and to filter overland flow from the park. Restoration also included repairing the Works Progress Administration (WPA) stone wall, removing concrete sluiceways, and installing a permanent summer aerator. An alum treatment was conducted in May 2003 to limit phosphorus availability.
The MPRB has treated Powderhorn Lake with barley straw every spring since 2004 in an attempt to control blue green algal growth. While it is difficult to ascertain which restoration activities have benefited the lake the most, the barley straw treatments seem to have been an important tipping point for improving water clarity in some years. Macrophyte beds were first noted in 2006 and led to improved clarity and lower nutrient levels in the lake. In 2010, extensive duckweed (Lemna spp.) beds covered the lake and shaded out macrophyte growth. Filamentous algae dominated large portions of the lake bed and water surface from 2011 to 2013. Since 2015, there have been summer blue-green algal blooms in the lake. The decomposition of thick plant and algae growth combined with a hot dry summer often creates low oxygen levels in the lake.
Restoration efforts shifted in 2007 when the invasive species Egeria densa (Brazilian waterweed) was discovered growing in several small stands in the lake. During the fall of 2007, the MDNR treated the invasive plant with the herbicide Diquat to target and eradicate the unwanted species. A total of 1.4 acres of the lake were treated across two treatment areas. One area had 28 ounces of Diquat applied and the other area had 2.54 gallons applied. At the request of the MDNR, the MPRB did not use the Powderhorn Lake winter aeration system during the winter of 2007. The invasive plant has not been identified in the lake since the herbicide treatment and was removed from the infested waters list for this species in 2014. The DNR based the decision to remove Powderhorn Lake from the infested waters list on 5 years of surveys indicating no presence of Egeria densa.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-2
Figure 13-2. Bathymetric map of Powderhorn Lake.
MPCA removed Powderhorn Lake from the US EPA 303(d) list of impaired waters in 2012 due to a strong trend towards improved water quality. However, the lake has not met standards for clarity or chlorophyll-a the past five years and if the trend continues it could be put back on the list. MPCA and MPRB will continue to evaluate the lake for potential improvement options. Improving oxygen levels, reducing trash accumulation, reducing phosphorus, and reducing algae growth are all areas where improvements could continue at the lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-3 Table 13-1. Powderhorn Lake morphometric data.
Surface Mean Watershed: Residence Maximum Littoral Volume Watershed Area Depth Lake Area Time Depth (m) Area* (m3) Area (acres) (acres) (m) (ratio) (years) 11 1.2 6.1 99% 5.43x104 286 26.0 0.2 * Littoral area was defined as less than 15 feet deep.
LAKE LEVEL
Powderhorn Lake levels are recorded weekly during the ice free season and are shown in Figure 13- 3 from 1999 through 2017. The lake level bounced with most rainstorms in 2017 and for the third straight year, the outlet pump was used to prevent flooding. In total, 19 million gallons were pumped out of the lake in 2017. The permit from the MDNR to pump water out of Powderhorn was amended in 2016 to allow up to 19 million gallons per year for level maintenance. During low water, lake levels are occasionally augmented with a groundwater well (Table 13-2). There is no MDNR designated ordinary high water level (OHW) for Powderhorn Lake. See Section 17 for comparison with other MPRB lake levels.
Figure 13-3. Powderhorn Lake levels from 1999-2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-4 AUGMENTATION WELL
A groundwater well is used to maintain the water level at Powderhorn. The MDNR issues permits and determines pumping limits for augmentation wells. In 2006, the permitted pumping volume decreased from 26 million gallons per year to 10 million gallons per year. MPRB staff records groundwater usage monthly. Table 13-2 shows the annual water usage since 2011. The groundwater pump was not used in 2017. See Section 1 for detailed information on MPRB augmentation wells.
Table 13-2. Powderhorn Lake yearly pumping volume in gallons.
2013 2014 2015 2016 2017 (gallons) (gallons) (gallons) (gallons) (gallons) 3,261,600 0 1,282,500 0 0
WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Powderhorn Lake has historically been eutrophic due to high nutrient levels. Figure 13-4 shows TSI scores and a regression line for Powderhorn Lake. Powderhorn Lake had a TSI score of 75 in 2017 and is below average for the Northern Central Hardwood Forest ecoregion falling near the 90th percentile for this ecoregion based on calculations from the Minnesota Pollution Control Agency, using the Minnesota Lake Water Quality Data Base Summary, 2004. There is no linear trend in TSI scores with water quality fluctuating over the past 25 years. The restoration efforts appeared to improve TSI scores from 2001-2009. CDS units decreased phosphorus, solids, and sediment inputs, annual barley straw treatments increased water clarity, and an alum treatment briefly decreased phosphorus and increased water clarity. However, the trend is changing towards higher TSI scores and lower water quality since 2009. A detailed explanation of TSI can be found in Section 1.
Figure 13-4. Powderhorn Lake TSI scores and linear regression from 1992-2017. The blue square highlights the 2003 alum treatment.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-5 BOX AND WHISKER PLOTS
Figure 13-5 shows box and whisker plots for the Powderhorn Lake Secchi transparency, chlorophyll- a, and total phosphorus for the past ten years. MPCA shallow lake standards are shown as a horizontal line across the graph. A further detailed explanation of box and whisker plots can be found in Section 1. Box and whisker plots for Powderhorn Lake from 1992 to 2017 can be found in Appendix A.
Water transparency in 2017 was similar to the previous 4 years with significantly less clear water than was seen in the late-2000s with an average Secchi depth of 0.5 meter in 2017. Chlorophyll-a was higher in 2017 compared to the previous years with an average concentration of 69.2 µg/L. Total phosphorus concentrations were significantly higher in 2017 as well with an average of 181 µg/L. The lake exceeded MPCA eutrophication standards for all three parameters in 2017. Marked improvements in the TSI parameters have been seen in Powderhorn Lake during the restoration projects but have gone back to pre-restoration levels in recent years. As shown in Appendix A, 2017 resembles data from the late 1990s more than the mid-2000s.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-6
Figure 13-5. Powderhorn Lake box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) from 2008 to 2017. Horizontal lines represent MPCA eutrophication standard for shallow lakes. Data from 1992-2017 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-7 Nitrogen levels remain lower than pre-2001 levels but have been slowly increasing the previous few years (Figure 13-6). It is unknown why nitrogen levels decreased, or why nitrogen levels appear to be increasing again. CDS units and grit chambers were installed in the watershed at this time, but the mechanism by which these BMPs would influence nitrogen is not known.
Figure 13-6. Powderhorn Lake box and whisker plot of total nitrogen from 1994-2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-8 LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
The LAURI for Powderhorn Lake is shown in Figure 13-7. In 2017, Powderhorn Lake scored good in habitat quality. Powderhorn received a score of poor in aesthetic, recreational access, and water clarity. Powderhorn Lake does not have a swimming beach and was not scored for public health. See Section 1 for details on the LAURI.
POWDERHORN LAKE 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
NO BEACH
Habitat Quality
Rec. Access
Figure 13-7. The 2017 LAURI for Powderhorn Lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-9 WINTER ICE COVER
Ice came off of Powderhorn Lake on March 21, 2017, 14 days earlier than average ice-off date. Ice came back onto the lake on December 7, 2017, which was 7 days later than the average ice-on date. Waterfowl keep Powderhorn Lake open later in some years. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton and zooplankton are microscopic plant and animal life that form the foundation of the food web in lakes. Figure 13-8 shows the Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton divisions and Figure 13-9 shows the zooplankton abundance during 2017.
The greatest water transparency was 1.05 meters in April and less than 1 meter for the rest of the year in 2017 (Figure 13-8a). Chlorophyll-a concentrations were high throughout the year, with some levels exceeding 100 µg/L in the summer months (Figure 13-8b). The winter phytoplankton community was a mix of green algae (Chlorophyta), chrysophytes, cryptomonads, diatoms (Bacillariophyta), blue-green algae (Cyanophyta), and a small number of dinoflagellates (Pyrrhophyta) and euglenoids. Blue-green algae and cryptomonads comprised much of the April phytoplankton community. Green algae and cryptomonads were the most common divisions in May and June, with more dinoflagellates in late-May. Blue-green algae were the most abundant the rest of the year, with a surface scum noted at the lake during each visit, even in November (Figure 13-8c).
An extremely high number of rotifers were present in in April and May, with higher numbers in June and September as well. Both cladocerans and Nauplii and juvenile copepods were abundant in June and September. Calanoids and cyclopoids were present in Powderhorn, but only at low numbers. Overall, there were low numbers of zooplankton in Powderhorn in July, August, and November (Figure 13-9). The zooplankton community in 2017 was very similar to the previous few years at Powderhorn.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-10
Figure 13-8. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Powderhorn Lake during 2017. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-11
Figure 13-9. Zooplankton density in Powderhorn Lake during 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-12 FISH STOCKING
Additional fish stocking information can be found in Section 1.
Table 13-3. Fish stocked into Powderhorn Lake over the past 10 years. Data are from the Minnesota Department of Natural Resources. Year Species Number and Size Amount 2017 Bluegill 200 adults 62.5 pounds 2016 Bluegill 353 adults 90.5 pounds 2016 Channel Catfish 206 adults 371.2 pounds 2016 Pumpkinseed Sunfish 40 adults 11.8 pounds 2015 Bluegill 300 adults 66.7 pounds 2015 Channel Catfish 251 adults 402.6 pounds 2014 Black Crappie 3 adults 1.0 pounds 2014 Bluegill 346 adults 97.5 pounds 2014 Channel Catfish 173 adults 240.0 pounds 2014 Hybrid Sunfish 4 adults 1.0 pounds 2014 Pumpkinseed Sunfish 4 adults 1.0 pounds 2012 Bluegill 711 adults 151.4 pounds 2012 Channel Catfish 35 adults 69.0 pounds 2011 Bluegill 277 adults 63.4 pounds 2011 Channel Catfish 116 adults 237.2 pounds 2011 Largemouth Bass 13 adults 13.7 pounds 2010 Bluegill 623 adults 103.8 pounds 2010 Channel Catfish 137 adults 403.0 pounds 2009 Bluegill 499 adults 113.0 pounds 2009 Channel Catfish 75 adults 241.0 pounds 2009 Largemouth Bass 20 adults 37.0 pounds 2008 Bluegill 500 adults 101.0 pounds 2008 Channel Catfish 117 adults 391.0 pounds 2008 Largemouth Bass 1 adults 2.0 pounds
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-13 WATER QUALITY PROJECTS
Water quality improvement projects have been implemented to improve the health of Powderhorn Lake and are detailed in the History section of this chapter. Barley straw was first used at Powderhorn Lake in 2004 when 250 pounds/acre were added. Barley straw is applied by staking loose bales below the surface of the water where it slowly decomposes. The first treatment appeared to have little effect. Application rates were increased to 364 lbs/ac or 4000 pounds for the lake and appear to have been more successful. 2017 was the 14th application of barley straw to Powderhorn Lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 13-14 14. RYAN LAKE
HISTORY
Ryan Lake is a small body of water that borders the cities of Robbinsdale, Brooklyn Center, and Minneapolis (Figure 14-1). The Canadian Pacific Railway owns a rail line corridor in the Humboldt Industrial Park that runs along the northern shore of the lake. MPRB maintains land on the east side of the lake. Private residents own the west and the south shores of Ryan Lake. The MPRB installed a new dock on the east side for use by the public in 2006. In the spring of 2006, a small rain garden was constructed. Figure 14-2 shows a bathymetric map of Ryan Lake and Table 14-1 shows the morphometric data on Ryan Lake.
Figure 14-1. View from the fishing pier at Ryan Lake in August 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 14-1
Figure 14-2. Bathymetric map of Ryan Lake.
Table 14-1. Ryan Lake morphometric data. OHW= designated ordinary high water level.
Surface Area Littoral Watershed Watershed:Lake Max Depth (m) OHW (ft msl) (acres) Area* Area (acres) Area (ratio) 19 10.7 50% 5,510 306 849.6 *Littoral area was defined as less than 15 feet deep.
Ryan Lake has been monitored periodically through the Metropolitan Council’s Citizen Assisted Monitoring Program (CAMP) since 1994, but was not monitored by CAMP 2015. Over the years, the Ryan Lake CAMP score has fluctuated between a “B” and “D”, with a most recent score of a “B” in 2012. Additional information on the CAMP monitoring at Ryan Lake can be found through the Metropolitan Council on their Lake Monitoring and Assessment or the Shingle Creek Watershed Management Commission webpages.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 14-2 Ryan Lake was listed on the Minnesota Pollution Control Agency’s list of impaired waters (303(d) list) for excess nutrients. A TMDL and an implementation plan were approved in 2007 along with the Twin Lake chain of lakes. In the five years following, multiple projects have focused on reducing phosphorus loading from the watershed, but more reduction is needed from both external and internal sources (Shingle Creek Watershed Management Commission, 2014). More information can be found on the MPCA webpage under the Twin and Ryan Lakes - Excess Nutrients TMDL Project.
WINTER ICE COVER
Ice was off of Ryan Lake on March 22, 2017, 12 days earlier than the average ice-off date recorded at the lake since records began in 2003. Ice came back to Ryan Lake on December 8, 2017, 2 days later than the average ice-on date. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
FISH STOCKING
Additional information on fish stocking can be found in Section 1.
Table 14-2. Fish stocked into Ryan Lake over the past 10 years. Data are from the Minnesota Department of Natural Resources. Year Species Number and Size Amount 2017 Northern Pike 16 adults 24.6 pounds 2014 Black Crappie 9 adults 4.0 pounds 2014 Bluegill 14 adults 1.8 pounds 2014 Largemouth Bass 3 adults 5.0 pounds 2014 Northern Pike 9 adults 3.0 pounds 2014 Pumpkinseed Sunfish 15 adults 2.7 pounds 2014 White Crappie 5 adults 4.0 pounds 2013 Yellow Perch 130 yearlings 5.0 pounds 2011 Black Crappie 20 adults 9.1 pounds 2011 Bluegill 20 adults 5.0 pounds 2011 Largemouth Bass 6 adults 6.3 pounds 2010 Black Crappie 20 adults 3.7 pounds 2010 Bluegill 20 adults 3.3 pounds 2010 Yellow Perch 20 adults 2.0 pounds 2009 Bluegill 20 adults 4.5 pounds 2009 Yellow Perch 21 adults 3.5 pounds 2008 Bluegill 31 adults 6.3 pounds 2008 Yellow Perch 100 adults 20.0 pounds
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 14-3 15. SPRING LAKE
HISTORY
Spring Lake is located to the west of Loring Pond adjacent to Kenwood Parkway and the Parade Stadium grounds in central Minneapolis. Spring Lake was acquired by the MPRB in 1893 through a special assessment requested by citizens. Today the lake appears secluded, but at the time of purchase, Spring Lake was the park’s focal point. In an unusual move for the time, a 2-acre area including the lake and surrounding land was designated as a bird sanctuary and kept undeveloped. Historic photos and documents show that the north side of the lake was once a lumberyard.
Despite being surrounded by parkland on three sides, Spring Lake receives runoff from the urbanized area around it Figure 15-1. Highway 394 borders the northwest portion of the riparian zone and contributes stormwater runoff to the lake. Spring Lake also receives water from a 195-acre subwatershed of the Bassett Creek watershed. These urban stormwater inputs contribute to meromixis in Spring Lake. Meromictic lakes do not mix completely so that the deeper layers of the lake remain continually stratified. It is difficult to compare meromictic lakes with dimictic or polymictic lakes, since their chemical, physical, and trophic structures are much different.
Figure 15-1. Spring Lake in October in fall 2016.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 15-1 Spring Lake is monitored on an every other year basis and was monitored in 2017. The lake was sampled each year from 2011-2015 to assess the water quality effects of artificial islands (see Water Quality Projects section below). Table 15-1 shows morphometric data for the lake and Figure 15-2 shows a map of Spring Lake.
Figure 15-2. Map showing the location of Spring Lake and the water quality sampling station.
Table 15-1. Spring Lake morphometric data. OHW=ordinary high water level.
Surface Watershed: Mean Maximum Volume Watershed Area Lake Area OHW(ft msl) Depth (m) Depth (m) (m3) Area (acres) (acres) (ratio) 3 3.0 8.5 3.65x104 45 15.0 820.46
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 15-2 WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Figure 15-3 shows the Spring Lake TSI scores and linear regression since 1995. The TSI score for Spring Lake in 2017 was 77, classifying the lake as hypereutrophic. There is no significant trend in TSI from 1995-2017 (p > 0.05). Spring Lake is sampled less frequently than other MPRB lakes. From 1999–2001, samples were collected quarterly and only one sample per year was collected during the growing season; therefore, a TSI score could not be calculated. Since 2002, Spring Lake was sampled monthly during the growing season. A detailed explanation of TSI can be found in Section 1.
Figure 15-3. Spring Lake TSI scores and linear regression from 1995-2017.
BOX AND WHISKER PLOTS
The box and whisker plots in Figure 15-4 show the data distribution for Secchi transparency, chlorophyll-a, and total phosphorus for the past 10 years. Red horizontal lines on the graphs indicate the MPCA shallow lake standards. The 303(d) assessment for impaired waters is limited to lakes of ten acres or greater (MPCA, 2014). Spring Lake is too small (3 acres) to be listed on MPCA’s impaired waters list; however, it is still useful to compare Spring’s data to the state standards to determine lake water quality. A detailed explanation of box and whisker plots can be found in Section 1. Box and whisker plots from the entire period of record, 1994-2017, can be found Appendix A.
As can be seen in the box and whisker plots in Figure 15-4, Spring Lake met the standard for Secchi transparency, but did not meet chl-a or phosphorus standards. Water transparency in 2018 was similar to the previous years with an average Secchi depth of 1.2 meters, meeting MPCA standards. There was a wide range of Chlorophyll-a concentrations in 2017 (5.9 to 259 µg/L), with higher concentrations April and in fall, which was typical when compared to previous years. Historically, total phosphorus concentrations have been high in Spring Lake. In 2017, phosphorus levels had an average of 586 µg/L, which was also similar to previous years and is significantly elevated above the MPCA standard. The highest concentrations occurred while the lake wasn’t thermally stratified in the winter, spring, and fall.
Since 2011, duckweed (Lemna spp.) has covered the lake for much of the summer. The thick layer of duckweed can shade photosynthetic algae and creating low dissolved oxygen levels as it decomposes.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 15-3 The fresh oxygenated layer that typically forms on the surface of Spring Lake was very thin to non- existent in 2017.
Figure 15-4. Spring Lake box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) from 2008-2017. Horizontal lines represent MPCA eutrophication standard for shallow lakes. Data from 1994-2017 can be found in Appendix A
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 15-4 WINTER ICE COVER
The ice came off Spring Lake on March 21, 2017, 10 days earlier than average ice-off date for the lake. Ice covered Spring Lake on December 6, 2017, 7 days later than the average ice-on date for the lake. See Section 1 for details on winter ice cover records and Section 17 for a comparison with other lakes.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton are microscopic plant life that form the foundation of the food web in lakes. Chlorophyll-a is the main pigment used by phytoplankton for photosynthesis and can be used as a proxy for the density of phytoplankton growth. Figure 15-5 shows the Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton divisions for Spring Lake in 2017. Although zooplankton weren’t sampled, observations of surface water noted bright red zooplankton on several occasions. Certain zooplankton can produce a substance similar to hemoglobin that they use to store oxygen when living in low-oxygen environments, making them appear red.
Water transparency increased each month until June and then decreased as chlorophyll-a concentrations increased the rest of the year (Figure 15-5a, b). Cryptomonads, specifically the species Cryptomonas erosa, comprised the majority of the phytoplankton community for much of 2017 with relative abundances greater than 90% from July through November (Figure 15-5c). Blue- green algae (Cyanophyta) and Green algae (Chlorophyta) were present in some months but were never more than 15% relative abundance. There were a lot of dinoflagellates (Pyrrhophyta) present in May, but they weren’t present in any of the other months. In past sampled years, Spring Lake has had a diverse phytoplankton community; however, the community has consisted of mostly C. erosa since 2011. Lemna cover in recent years may be affecting the phytoplankton community composition, since C. erosa can survive in low light conditions.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 15-5
Figure 15-5. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Spring Lake during 2017. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 15-6 16. WIRTH LAKE
HISTORY
Wirth Lake was acquired by the Minneapolis Park and Recreation Board (MPRB) in 1909, enlarging the adjacent park from its previous size of 64 acres that was purchased in 1889. It was originally known as Keegan’s Lake and renamed to Glenwood Lake in 1890. The lake was renamed yet again in 1938 after Theodore Wirth at the end of his tenure as Park Superintendent. A plant nursery was established on the west side of the lake in 1910 that provided the park system with plantings through 1980.
As with most other lakes in the MPRB, thousands of cubic yards of sediment from Wirth were dredged. The spoils were used to raise the parkland near Glenwood Avenue. Wirth Lake Beach was constructed with sand purchased from sources outside of the MPRB. The lake is shown below in Figure 16-1.
Figure 16-1. Wirth Lake in August 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-1 Wirth Lake is generally dimictic but can mix during extreme events if Bassett Creek backflows to the lake (Barr, 2010). Early restoration projects included Rotenone in 1977 to remove rough fish and subsequent stocking of channel catfish, largemouth bass, walleye, and bluegills. A summer aerator was installed and operated from the early 1980s until 1991. A portable winter aerator was used for a few years before a permanent aeration system was put in place in 2002. Figure 16-2 shows a bathymetric map of Wirth Lake and Table 16-1 shows the Wirth Lake morphometric data.
Figure 16-2. Bathymetric map of Wirth Lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-2 Table 16-1. Wirth Lake morphometric data.
Surface Watershed: Mean Maximum Littoral Volume Watershed Area Lake Area Depth (m) Depth (m) Area* (m3) Area (acres) (acres) (ratio) 39 4.3 7.9 59% 6.70x105 348 9.4 * Littoral area was defined as less than 15 feet deep.
LAKE LEVEL
Wirth Lake levels are recorded weekly during ice free conditions. The lake levels for Wirth Lake are shown in Figure 16-3 from 1971 through 2017. The ordinary high water level (OHW) designated by the MDNR for Wirth Lake is 818.9 ft msl. The effects of new outlets installed in 1978 and in 1996 on water level fluctuations can be seen in the graph below. Since the installation of the 1996 outlet fewer high flow events have backed up water from Bassett Creek into the lake. The outlet to Bassett Creek was renovated and a new staff gauge was installed in August 2013. Lake levels were stable for much of 2017 and were below the OHW the entire year. See Section 17 for a comparison between other MPRB lake levels.
Figure 16-3. Lake levels for Wirth Lake from 1971–2017. Horizontal line represents Wirth Lake OHW elevation (818.9 ft msl).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-3 WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
Figure 16-4 shows the Wirth Lake TSI scores over time. The 2017 TSI score for Wirth Lake was 50, classifying the lake as mesotrophic with moderately clear water and some algae. There has been a significant decrease in TSI score from 1992-2017 (p < 0.001), with TSI scores being on average 15 TSI units lower in the past few years than when monitoring began. Wirth Lake now has a TSI score that falls within the 25th percentile category for lakes in this ecoregion (based on calculations from the Minnesota Pollution Control Agency, using the Minnesota Lake Water Quality Data Base Summary, 2004). A detailed explanation of TSI can be found in Section 1.
Figure 16-4. Wirth Lake TSI scores and linear regression from 1992-2017.
BOX AND WHISKER PLOTS
The box and whisker plots in Figure 16-5 show the distribution of data for the Secchi, chlorophyll-a, and total phosphorus for Wirth Lake over the past ten years. The red horizontal lines indicate MPCA deep lake nutrient criteria. A detailed explanation of box and whisker plots can be found in Section 1. Box and whisker plots for the entire period of record, 1992 to 2017, can be found in Appendix A.
Water transparency in 2017 was similar to the previous 10 years with an average Secchi depth of 2.6 meters. Chlorophyll-a was higher in 2017 compared to the previous few years with an average concentration of 10.1 µg/L. Total phosphorus concentrations in 2017 were comparable to previous years with an average of 33 µg/L. The higher concentrations occurred while the lake wasn’t thermally stratified in the spring and fall. The lake met MPCA eutrophication standards in all three parameters in 2017. When comparing the boxplots in Figure 16-5 to those in Appendix A, it appears the separation of Bassett Creek from Wirth Lake and upstream water quality improvements in the lake’s watershed may be responsible for continued improvement in Wirth Lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-4
Figure 16-5. Wirth Lake box and whisker plots of Secchi transparency (a), chlorophyll-a (b), and total phosphorus (c) data from 2008-2017. Horizontal lines represent MPCA eutrophication standard for deep lakes. Data from 1992-2017 can be found in Appendix A.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-5 BEACH MONITORING
Escherichia coli (E. coli) levels were monitored weekly from late-May through August at Wirth Beach in 2017 (Table 16-2 and Figure 16-6). E. coli concentrations at Wirth Beach were low for much of the year until mid-August when bacteria levels increased. Wirth Beach closed on August 22nd due to an exceedance of the single sample E. coli standard of 1260 MPN/100 mL. The beach reopened on August 23rd when bacteria levels dropped below the standard. There was evidence of a lot of birds present at the beach, especially in August.
Table 16-2. Summary of E. coli (MPN per 100 mL) data for Wirth Beach in 2017.
Statistical Calculations Wirth
Number of Samples 15 Minimum 1 Maximum 1460 Median 15 Mean 131 Geometric Mean 17 Max 30-Day Geo Mean 109 Standard Deviation 372
Figure 16-6. 2017 E. coli concentrations at Wirth Lake Beach. Blue line is the running 30-day geometric mean. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y-axis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-6 Figure 16-7 illustrates the box and whisker plots of E. coli monitoring results for Wirth Lake Beach from 2008 to 2017. The box and whisker plots show the high variability in E. coli concentrations over years. The 2017 E. coli results were typical for Wirth Beach with a few high samples.
Figure 16-7. Box and whisker plot of E. coli concentrations (MPN/100 mL) for Wirth Beach from 2008–2017. The dashed horizontal line represents the E. coli standard for the 30-day geometric mean (126 MPN/100mL) and the solid horizontal line represents the single-sample maximum standard (1260 MPN/100mL). Note the log scale on the Y-axis. From 2008-2009 E. coli concentrations were determined as colony forming units (CFU/100ml).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-7 LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
The 2017 LAURI for Wirth Lake is shown in Figure 16-8. Wirth Lake scored excellent for aesthetics, habitat quality, public health, and recreational access opportunities and good for water clarity. Details on the updated LAURI can be found in Section 1.
WIRTH LAKE 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
Habitat Quality
Rec. Access
Figure 16-8. Wirth Lake LAURI for 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-8 WINTER ICE COVER
Ice came off Wirth Lake on March 22, 2017, 11 days earlier than the average date for the lake. Ice came on to the lake for the winter on December 7, 2017, which was 6 days later than the average ice- on date. Details on winter ice cover records can be found in Section 1 and a comparison with other lakes can be found in Section 17.
EXOTIC AQUATIC PLANT MANAGEMENT
The MDNR requires a permit to remove or control Eurasian water milfoil. Aquatic plant control permits limit the area from which milfoil can be harvested to protect fish habitat. The permits issued to the MPRB allow for harvesting at the beach and the boat launch. The permitted area on Wirth Lake was 5 acres which is 21% of the littoral zone of the lake (area shallower than 15 feet). A mechanical harvester could not be used inside of the beach boardwalk, so MPRB contracted SCUBA divers to remove vegetation from areas around the swimming beach, boardwalk, and boat launch. Approximately 3,860 pounds of aquatic plants were removed from Wirth Lake in 2017. See Section 1 and Section 20 for details on aquatic plants.
PHYTOPLANKTON AND ZOOPLANKTON
Phytoplankton and zooplankton are microscopic plant and animal life that form the foundation of the food web in lakes. Figure 16-9 displays the Secchi transparency, chlorophyll-a concentrations, and relative abundance of phytoplankton divisions and Figure 16-10 shows the distribution of zooplankton in 2017.
Water clarity initially started out poor in April with a Secchi depth of 1.4 meters, increased to 4.1 meters in May, slowly decreased until August to around 1.5 meters, and remained around 2.5 meters through November (Figure 16-9a). Secchi transparency closely followed chlorophyll-a concentrations throughout the season (Figure 16-9a, b). Chlorophyll-a concentration was the highest in April, decreased to the lowest level in early-May, and slowly increased the rest of the year (Figure 16-9b). The phytoplankton community had a lot of turnover over the course of the year. Cryptomonads comprised much of the winter and late-fall samples. The highest algal biomass occurred in April (21.1 µg/L) and was characterized by mostly haptophytes (Figure 16-9b, c). Cryptomonads, dinoflagellates (Pyrrhophyta), and diatoms (Bacillariophyta) were in greater abundance in the spring and blue-green (Cyanophyta), dinoflagellates, and green algae (Chlorophyta) were more abundant in the summer. Chrysophytes and euglenoids were only present in low numbers during the year (Figure 16-9c).
Zooplankton populations varied throughout 2017 in Wirth Lake, as shown in Figure 16-10. Nauplii and juvenile zooplankton were at their highest levels in April, but they were present throughout the season. Rotifers were also present throughout the season and were at their highest abundance in the August and September tows. Cladocerans, primary grazers of phytoplankton, were the most abundant in May. Cyclopoids and calanoids were only present in low concentrations in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-9
Figure 16-9. Secchi transparency (a), chlorophyll-a concentration (b), and relative abundance of phytoplankton (c) in Wirth Lake during 2017. Note that the Secchi depth axis is reversed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-10
Figure 16-10. Zooplankton density in Wirth Lake during 2017.
FISH STOCKING
Additional fish stocking information can be found in Section 1.
Table 16-3. Fish stocked into Wirth Lake over the past 10 years. Data are from the Minnesota Department of Natural Resources. Year Species Number and Size Amount 2017 Walleye 10,000 fry 0.1 pounds 2012 Walleye 23,000 fry 0.2 pounds 2011 Walleye 2,772 fingerlings 99.0 pounds 2008 Walleye 57 fingerlings 11.2 pounds 2008 Walleye 40 fingerlings 47.0 pounds
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-11 AQUATIC PLANT SURVEY
In August of 2017, a macrophyte survey was conducted at Wirth Lake using a modified point- intercept method (Madsen, 1999, Perleberg et al., 2016). The goal of the survey was to determine the extent of plant growth in the lake, to determine plant species diversity, and to compare with previous surveys. There is inherent inaccuracy in locating sample points due to error in GPS readings, error in locating the point on the lake bottom, and maintaining the boat in a fixed location. Therefore, sample points were placed 30 meters apart to avoid overlap of sampling locations. Based on summer Secchi depths and previous macrophyte surveys, most points were selected in less than 15 feet of water and 20 feet was chosen as the maximum sampling depth. Using a 30 meter systematic grid and the DNR bathymetry contours, 123 points were selected within the 15 foot contour (Figure 16-11).
Sample points were located using GPS coordinates and a Trimble GeoXT GPS. At each point, depth was determined using either a handheld sonar or a weighted tape if vegetation caused false readings on the sonar. Plants within a 1m2 area were sampled visually and with a rake sampler and identified to the species level when feasible. Plant taxonomy was based on Borman et al. (1997), Fassett (1957), and Fink (1994). Total plant abundance was described in categories ranging from 1-4, with 0 indicating no plants were retrieved or observed (Table 16-4). All data was later imported using Microsoft Excel and to ArcGIS for analysis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-12
Figure 16-11. Points sampling Wirth Lake were based on grid spacing and MDNR littoral zone contours
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-13 Table 16-4. Plant abundance rankings based on rake coverage and/or visual observation. A zero ranking indicates no plants were retrieved or observed (Figure from MDNR).
Sample points were categorize based on depth zones (Table 16-5). Near-shore, shallow water sites often contain the highest plant diversity; therefore, a higher number of sampling points in the 0-5 foot depth help ensure adequate assessment of the vegetation. The most abundance of plants were in the 0-5 foot and 5-10 foot zones, with little vegetation growing beyond 15 feet (Figure 16-2). The maximum depth vegetation was observed at was 18 feet.
Table 16-5. Number of samples, percent vegetated, and average abundance ranking for the four depth zones.
Depth Zones Number of Average Abundance % Vegetated (ft) Samples Ranking
0-5 62 100 3
5-10 20 95 3
10-15 22 86 2
15-20 19 42 1
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-14
Figure 16-12. Abundance ranking for each sample point in Wirth Lake in 2017.
The highest species richness in the lake occurred in the near-shore, shallow water sites (Figure 16- 13). Eight species of aquatic macrophytes were found in 2017, which is comparable to previous surveys conducted over the past 20 years (Table 16-7). A native plant, coontail (Ceratophyllum demersum), was the most commonly encountered species and was found at 84% of the sample points. Another native plant, white water lily (Nymphaea odorata), was the next most common plant found at 27% of the points. The invasive Eurasian water milfoil (Myriophyllum spicatum) was found at 21% of the points but was in low density. Other species found were rare and only found in low density. Aside from Eurasian water milfoil, all plant species found were native to Minnesota.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-15
Figure 16-13. Species richness at the sample points in Wirth Lake in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-16 Table 16-7. Plant species found in Wirth Lake, sorted from highest to lowest frequency of occurrence. 120 points were sampled in the 2017 survey. Percentages were rounded to the nearest whole percent.
Average Number of % abundance Species name Common name Occurrences Occurrence ranking Ceratophyllum demersum Coontail 103 84 3 Nymphaea odorata White water lily 33 27 2 Myriophyllum spicatum Eurasian Watermilfoil 21 17 1 Lemna spp. duckweed 6 5 2 Potomageton Natans Common Pondweed 5 4 1 Potomageton zosteriformis Flat stem Pondweed 3 2 1 Elodea canadensis Canada Waterweed 1 1 1 Potomageton pectinatus Sago Pondweed 1 1 1 Nuphar luteum Spatterdock 1 1 1 Typha latifolia Common Cattail 1 1 1 Potomageton diversifolius Water-thread pondweed 1 1 1
There were 5 previous plant surveys at Wirth Lake. The 1974, 1997, and 2000 surveys were transect surveys, while the 2005, 2012, and 2017 surveys were point-intercept. The maximum depth of plant growth and the percentage of the littoral zone (water shallower than 15 feet) were similar to the 2012 survey and greater than past findings. Species richness was the highest observed at the lake since 1997, when 9 species were observed (Table 16-6).
Table 16-6. Maximum depth of plant growth, percent of littoral area vegetated, and species richness from MPRB Wirth Lake surveys.
Year 1974 1997 2000 2005 2012 2017
Maximum Depth of 1m, 3ft 1.5m, 5ft 2m, 6ft 3m, 9ft 6.5m, 20ft 5.6m, 18.4 ft Plant Growth
% of Littoral Area 54 54 45 89 93 95 Vegetated
Species Richness 5 9 6 7 7 8
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 16-17 17. COMPARISON AMONG LAKES
PHYSICAL CHARACTERISTICS
Understanding the physical characteristics of a lake is important when interpreting data from an individual lake and when comparing groups of lakes. Shallow and deep lakes respond in distinct ways to environmental and watershed changes and may require entirely different approaches for rehabilitation. Lakes with large watershed to lake area ratios are typically more eutrophic and may be more complicated to manage if their watersheds cross political boundaries. A lake’s residence time can also influence its overall physical condition, with long residence times causing delayed effect of rehabilitation efforts. Table 17-1 presents the physical characteristics of the Minneapolis lakes.
Table 17-1. Minneapolis lakes physical characteristics.
Surface Mean Max Watershed Residence Area Depth Depth % Volume Area Watershed:Lake Time Lake (acres) (m) (m) Littoral* (m3) (acres) Area (ratio) (years) Brownie 18 6.8 15.2 67% 4.98x105 369 20.5 2.0 Bde Maka Ska 421 10.6 27.4 31% 1.80x107 2,992 7.1 4.2 Cedar 170 6.1 15.5 37% 4.26x106 1,956 11.5 2.7 Diamond 41 0.9† 2.1† 100% 7.15x104 669‡ 16.3 ND Grass 27 0.6 1.5 ND ND 386 14.3 ND Harriet 353 8.7 25.0 25% 1.25x107 1,139 3.2 3.4 Hiawatha 54 4.1 7.0 26% 8.95x105 115,840 2145 0.003 Isles 103 2.7 9.4 89% 1.11x106 735 7.1 0.6 Loring 8 1.5 5.3 NA 4.88x104 24 3.0 ND Nokomis 204 4.3 10.1 51% 3.54x106 869 4.3 4.0‡ Powderhorn 11 1.2 6.1 99% 9.04x104 286 26.0 0.2‡ Ryan 18 ND 10.7 50% ND 5,510 306 ND Spring 3 3.0 8.5 ND 3.65x104 45 15.0 ND Wirth 39 4.3 7.9 61% 6.70x105 348 9.4 ND * Littoral area defined as less than 15 feet deep. ND= No Data Available † Based on long-term data. ‡ Recent projects within the watersheds have altered these statistics.
Summary statistics of interest include:
• Largest Lake: Bde Maka Ska at 421 acres. • Smallest Lake: Spring Lake at 3 acres. • Deepest Lake: Bde Maka Ska at 89 feet 11 inches. • Largest Watershed: Lake Hiawatha at 115,340 acres. • Smallest Watershed: Loring Pond at 24 acres. • Longest Residence Time: Bde Maka Ska at 4.3 years. • Shortest Residence Time: Lake Hiawatha at 11 days.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-1 WATER QUALITY TRENDS – TROPHIC STATE INDEX (TSI)
The Minneapolis Park and Recreation Board (MPRB) calculates a trophic state index score (TSI) for each lake using chlorophyll-a, Secchi depth, and total phosphorus measurements. TSI scores can be used to evaluate changes in an individual lake or to compare lakes to each other. Detailed information on TSI scores can be found in Section 1.
In 2017, MPRB scientists monitored 11 of the city’s most heavily used lakes. The data collected were used to calculate a Trophic State Index (TSI) score for each of the lakes. Lower TSI scores indicate high water clarity, low levels of algae in the water column, and/or low phosphorus concentrations. All the lakes in Minneapolis fall into either the mesotrophic or eutrophic category which is the typical distribution for lakes in the North Central Hardwood Forest ecoregion (MPCA, 2004). Bde Maka Ska, Harriet, and Wirth are mesotrophic with moderately clear water and some algae. Cedar, Isles, Hiawatha, Loring, and Nokomis are eutrophic with higher amounts of algae. Powderhorn and Spring are hypereutrophic with high nutrient concentrations and the potential for severe algal blooms. Scores for Diamond Lake and Grass Lake are not included since these lakes are too shallow to calculate the Secchi portion of the TSI index (Figure 17-1).
Changes in lake water quality can be tracked by looking for trends in TSI scores over time. Trends were identified by using a linear regression of the TSI scores through time. Table 17-2 shows the trends in TSI scores since 1991, the year sampling began for most lakes. Since the record for some lakes is so long, and because many large water quality improvement projects took place in the late 1990s and early 2000s, the long term water quality trend and 10-year trends for the Minneapolis lakes can be different. Table 17-3 shows the TSI trends since 2008. For more detailed information on a particular lake’s trend in TSI scores and related water quality parameters, see the individual lake sections. Details on TSI scores and linear regression analysis can be found in Section 1.
TSI scores and linear regression for all the Minneapolis lakes since 1991 are shown in Figure 17-2. A negative slope in the linear regression indicates improving water quality, while a positive slope indicates declining water quality. These values are especially important for monitoring long-term trends (10+ years). Historical trends in TSI scores are used by lake managers to assess improvement or degradation in water quality.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-2 CARLSON'S TROPHIC STATE INDEX
WATER QUALITY TSI SCORE TROPHIC STATE 0 GOOD
10
20 OLIGOTROPHIC
Clear water, little algae
30
2017 40 MESOTROPHIC Lake Harriet Bde Maka Ska Wirth Lake 50 Moderately clear water, Lake Hiawatha some algae Cedar Lake Lake Nokomis EUTROPHIC Lake of the Isles 60 Loring Pond Bluegreen algae prevalent Swimming impaired Spring Lake 70 Powderhown Lake HYPEREUTROPHIC
80 Frequent noxious algae blooms
90
100 POOR
Figure 17-1. 2017 lake trophic state comparison. In general, the deeper lakes have lower TSI scores.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-3 Table 17-2. Water quality trends in Minneapolis lakes from 1991-2017.
Lakes with Improving Water Quality • Bde Maka Ska Indicators • Lake Harriet • Lake Nokomis • Wirth Lake Lakes with Stable Trends • Brownie Lake • Cedar Lake • Lake Hiawatha • Lake of the Isles • Loring Pond • Powderhorn Lake • Spring Lake Lakes with Declining Water Quality • No lakes with declining trend Indicators
Table 17-3. Water quality trends in Minneapolis lakes from 2007-2017.
Lakes with Improving Water Quality • Lake Hiawatha Indicators • Loring Pond Lakes with Stable Trends • Brownie Lake • Bde Maka Ska • Lake Harriet • Lake of the Isles • Lake Nokomis • Spring Lake • Wirth Lake Lakes with Declining Water Quality • Cedar Lake Indicators • Powderhorn Lake
There has been a significant improvement in water quality indicators in Bde Maka Ska since the early 1990s (linear regression, p < 0.001); however, TSI scores have stabilized since 2006. The TSI score at Bde Maka Ska in 2017 was higher than the last few years, but it was still below pre-2000 scores. The water quality indicators in Lake Harriet have been improving since 1991 (linear regression, p <0.1). Lake Harriet experienced a few years with lower TSI scores following a littoral alum treatment in the mid-2000s but has remained stable the last 10 years. Lake Nokomis experienced higher algal concentrations in 2016 and 2017, especially in the fall, but has seen a significant improvement in water quality following a biomanipulation project (linear regression, p <0.05). The water quality improvement at Wirth Lake has been occurring since 1992, going from a eutrophic system dominated by algal growth to a moderately clear mesotrophic system (linear regression, p < 0.001). The TSI score at Wirth Lake in 2017 was slightly above the last few years due to higher chlorophyll-a concentrations.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-4 Most of the Minneapolis lakes have no directional trend in water quality indicators since the early 1990s. The water quality in Brownie Lake has been relatively stable, with no significant trend since 1993. Brownie Lake is monitored every other year and was not monitored in 2017. The water quality in Cedar Lake showed improvement following restoration efforts through the late 1990s, had a slow decline in the 2000s, and have remained stable since. The 2017 Cedar Lake TSI score was the highest it’s been since the early 1990s due to higher chlorophyll-a concentrations. The TSI scores in Lake Hiawatha have remained stable over the past 24 years. Lake Hiawatha is heavily influenced by the inflow from Minnehaha Creek and the lake has poorer water quality during drought years. The last few years has experienced above average spring and summer precipitation and led to low TSI scores, with 2017 being the third lowest recorded at Lake Hiawatha. The water quality in Lake of the Isles varies from year to year, with a higher TSI score in 2017 compared to the previous few years, but there is no significant trend in any direction since 1991. Loring Pond experienced decreased water quality immediately following a dredging project in 1997; however, conditions have slowly returned to levels similar to pre-1997. Powderhorn Lake has experienced large swings in water quality, with the worst TSI scores in the late 1990s and the best scores in the late 2000s. Powderhorn has had poor water quality the past 5 years, with blue green algae blooms leading to low water clarity. The water quality in Spring Lake is variable, but there is no significant trend in any direction since 1994. Spring Lake is also monitored every other year and was monitored in 2017.
Diamond Lake and Grass Lake are not included in this analysis, since TSI scores are only appropriate for deeper lake systems and there are no water clarity measurements available in these lakes. There are no lakes in Minneapolis with significant decline in water quality indicators since the early 1990s.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-5
Figure 17-2. TSI scores and regression analysis for selected Minneapolis lakes 1991–2017. Lower TSI scores indicate high water clarity, low levels of algae in the water column, and/or low phosphorus concentrations. A negative slope indicates improving water quality, while a positive slope indicates declining water quality. Only Bde Maka Ska, Harriet, Nokomis, and Wirth have statistically significant trends (p <0.1).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-6 LAKE LEVELS
Lake levels are recorded weekly from ice-out to ice-on at Harriet, Hiawatha, Nokomis, Diamond, Loring, Powderhorn, Wirth, and Bde Maka Ska. Channels connect the Upper Chain of Lakes which makes the level at Bde Maka Ska representative of all four lakes in the Upper Chain (Brownie, Cedar, Isles, and Bde Maka Ska). Fixed staff gauges are used at all locations that are shown in Figure 17-3. Average annual lake levels and selected statistics for each lake with a staff gauge are shown in Tables 17-4 and 17-5. Water levels for Minneapolis lakes are illustrated in Figure 17-4.
Figure 17-3. Minneapolis lake level monitoring locations.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-7 Table 17-4. Average annual lake levels in feet above msl for 2008-2017.
Lake 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Chain§ 852.14 851.75 852.50 852.94 852.05 852.66 853.80 852.38 852.72 853.01 Harriet 847.13 846.89 847.28 847.63 847.14 847.48 847.84 847.36 847.60 847.73 Diamond NA 821.59 822.02 821.84 821.58 821.72 822.24 822.35 822.86 821.84 Hiawatha 812.14 811.64 812.79 813.36 811.83 813.05 814.14 812.53 813.27 813.26 Loring* 817.85 817.80 817.77 817.84 817.95 817.85 814.87 818.45 818.50 818.33 Nokomis 813.22 811.89 812.24 814.71 814.46 815.13 816.37 815.24 815.70 815.54 Powderhorn* 816.89 816.70 817.18 817.76 817.39 818.15 819.67 819.60 819.55 819.00 Wirth 817.96 817.95 818.03 818.07 818.00 818.10 818.47 818.27 818.33 818.12 § The Chain of lakes includes: Bde Maka Ska, Cedar, Isles, & Brownie. * In dry years the level can be below recordable stage and levels can be augmented with groundwater.
Table 17-5. Selected statistics for lakes with level data based on data from 2008-2017.
2017 comparison Standard deviation 10 year average 2017 average Lake to 10 year average around 10 year average (ft msl) (ft msl) (ft) (ft) Chain 852.60 853.01 0.41 0.55 Harriet 847.41 847.73 0.32 0.29 Hiawatha 812.80 813.26 0.46 0.73 Loring 817.72 818.33 0.61 0.99 Nokomis 814.45 815.54 1.09 1.43 Powderhorn 818.19 819.00 0.81 1.12 Wirth 818.11 818.12 0.01 0.16
Lake levels vary annually based on precipitation, stream flow, and stormwater inflow. There was above average precipitation in 2017 (Section 27). August was the wettest month, with 2.5 inches of rain above normal. The above average rain caused lake levels to rise throughout the city. All the lakes were above the 10-year average level as can be seen in Tables 17-4 and 17-5. Historical lake levels can be found in the individual lake chapters.
Groundwater continued to be pumped into Loring Pond throughout 2017 to keep water levels near the top of the outlet structure for a cattail removal project. Large storms have caused stormsewers to surcharge to the pond periodically in the last 10 years and can be seen in the lake level graph in Loring’s individual lake chapter.
Powderhorn Lake is another lake that can be augmented by a groundwater well; however, the augmentation well was not used in 2017. For the third straight year, the outlet pump was turned on and 19 million gallons were pumped out of the lake to prevent flooding and the lake was still 0.79 feet above its 10-year average in 2017 (Table 17-5). The lake is strongly influenced by stormwater. Large storms are often followed by peaks in Powderhorn’s level.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-8
Figure 17-4. Lake levels for the Minneapolis Lakes in 2017. Horizontal lines represent ordinary high water elevation (OHW). Note the MDNR has not designated an OHW for Powderhorn Lake.
Lake Hiawatha levels are influenced by the inflow of Minnehaha Creek which changes depending on the operation of the Lake Minnetonka outlet dam. The dam at Gray’s Bay opened near the end of March 2017 at 150 cfs and fluctuated between 30 cfs and 250 cfs through June. The dam was only open between 12 and 20 cfs in July and early-August. Heavy rains in August led to the dam being opened between 100 and 200 cfs through October. The dam closed in mid-November. The 2017 average lake level was 0.45 feet above the 10-year average for the lake.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-9 For the fourth straight year, the level of Lake Nokomis has been high. The 2017 levels were above the OHW for much of the spring and early-summer and fluctuated around the OHW for the rest of the year. The MPRB, in consultation with MCWD, operates a fixed crest weir at the outlet of Lake Nokomis to Minnehaha Creek which allows the lake to overflow during periods of high water, yet still prevent the creek from flowing into the lake. The weir was open for 121 days between March and December in 2017.
LAKE AESTHETIC AND USER RECREATION INDEX (LAURI)
The LAURI was developed to provide recreational users with an additional source of information about the health of MPRB lakes. The LAURI provides lake users with an easily understandable recreational suitability indicator for the MPRB lakes. Background information on the LAURI can be found in Section 1. The LAURI index was updated in 2009 to include measures of habitat quality and recreational access. The scoring for the aesthetic index was further refined in 2017 to use the lowest of the three scores, rather than an average of the three which was how it was previously calculated. The scores have been used by Minneapolis, the Minneapolis Greenprint, and Results Minneapolis as a Citywide Metric.
All scores in the LAURI are between 1 and 10 with 10 as the best possible score. Table 17-6 shows the LAURI scores of each lake for 2017. The LAURI parameters for all of the lakes together are presented in Figure 17-5. The citywide LAURI scored excellent for aesthetics, public health, and recreational access and good for water clarity and habitat quality.
Table 17-6. 2017 sub-scores and classifications for each LAURI category.
Water Public Health Habitat Recreation Lake Aesthetics Clarity Index Quality Access Bde Maka Ska 7.9 8.0 6.0 9.0 10.0 Cedar 8.0 3.0 8.0 8.3 10.0 Harriet 8.0 9.0 8.0 8.5 10.0 Hiawatha* 5.1 8.0 3.0 6.5 4.0 Isles* 7.7 6.0 N/A 7.5 10.0 Loring* 6.2 6.0 N/A 3.0 3.0 Nokomis* 7.7 6.0 7.0 4.8 10.0 Powderhorn* 2.4 2.0 N/A 5.3 3.0 Wirth 8.4 6.0 8.0 8.5 10.0 LEGEND Excellent Good Poor * Denotes shallow lake. N/A = no swimming beach.
In general, lakes with the best habitat quality also had the best clarity and aesthetics. Lakes with poor clarity, odor, or trash problems scored lower in aesthetics. Larger lakes had better recreational access scores due to more opportunities to access the water through boating.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-10 Citywide LAURI 2017 POOR GOOD EXCELLENT Aesthetics
Water Clarity
Public Health
Habitat Quality
Rec. Access
Figure 17-5. 2017 Average LAURI for Minneapolis. Includes: Bde Maka Ska, Cedar, Harriet, Hiawatha, Isles, Loring, Nokomis, Powderhorn, and Wirth Lakes.
WINTER ICE COVER
The Minneapolis lakes had a longer than average ice-free period in 2017. Ice came off the lakes around 2 weeks earlier than the average ice-off date and varied based on lake size, as shown in Table 17-7. Most lakes completely froze over around November 20th, but later thawed out due to warm weather. The lakes finally completely froze over in early- to mid-December, a week later than the average recorded ice-on date (Table 17-8). Lake size typically influences the date ice forms on the lakes, with the larger lakes freezing later than some of the smaller lakes in Minneapolis. For further information on winter ice cover records see Section 1 and individual lake sections.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-11 Table 17-7. Statistics related to ice-off dates.
Earliest Year Latest Year Years of Lake 2017 Ice-Off Occurred Ice-Off Occurred Mean Median Record Birch 3/29 3/8 2000 4/28 2013 4/3 4/4 32 Brownie 3/22 3/9 2000 4/28 2013 4/3 4/3 36 Bde Maka Ska 3/20 3/9 2000 4/28 1965, 2013 4/8 4/9 68 Cedar 3/24 3/9 2000 4/28 2013 4/6 4/6 44 Diamond 3/20 3/6 2000 4/24 2013 3/31 3/31 25 Grass 3/20 3/14 2016 4/18 2013 3/31 3/29 12 Harriet 3/20 3/9 2000 4/28 1965, 2013 4/6 4/6 50 Hiawatha 3/23 3/8 2000 4/26 2013 4/3 4/3 43 Isles 3/22 3/8 2000 4/28 2013 4/4 4/4 48 Loring 3/21 3/6 2000 4/25 2013 4/1 4/3 37 Nokomis 3/21 3/8 2000 4/27 2013 4/4 4/4 46 Powderhorn 3/21 3/8 2000 4/27 1965, 2013 4/3 4/3 38 Ryan 3/22 3/15 2016 4/27 2013 4/3 4/3 14 Spring 3/21 3/6 2000 4/24 2013 3/31 4/1 27 Wirth 3/22 3/7 2000 4/27 2013 4/1 4/3 41
Table 17-8. Statistics related to ice-on dates.
First Final ice-on ice-on date date Earliest Year Latest Year Years of Lake 2017 2017 Ice-On Occurred Ice-On Occurred Mean Median Record Birch 11/21 12/7 11/1 1991 12/16 1998 11/26 11/29 32 Brownie 11/22 12/7 11/5 1991 12/21 2015 11/29 12/2 36 Bde Maka Ska 12/18 11/25 1996 1/16 2006-07 12/12 12/11 48 1998, 1999, Cedar 12/8 12/8 11/18 1989 12/21 2001, 2015 12/4 12/4 36 Diamond 11/20 12/12 11/13 2014 12/20 2001 12/2 12/4 23 Grass 11/20 12/8 11/13 2014 12/13 2004 12/1 12/1 12 Harriet 12/18 12/18 11/25 1996 1/16 2006-7 12/13 12/11 45 Hiawatha 12/11 12/11 11/1 1991 1/31 2006-7 12/3 12/3 37 Isles 11/22 12/7 11/5 1991 1/2 2006-7 12/1 12/2 43 1999, 2001, Loring 11/20 12/7 11/1 1991 12/21 2015 12/1 12/4 33 Nokomis 12/11 12/11 11/1 1991 1/17 2011-12 12/2 12/2 38
Powderhorn 11/20 12/7 11/1 1991 12/21 2015 11/29 12/1 33 Ryan 11/22 12/8 11/17 2014 1/16 2006-7 12/6 12/2 11 Spring 11/22 12/6 11/10 1995 12/20 2001 11/29 11/30 27 Wirth 11/22 12/7 11/5 1991 12/21 2001, 2015 11/30 12/2 37
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-12 INVASIVE SPECIES MONITORING
MPRB has been actively monitoring invasive species since the late-1980s, when Eurasian watermilfoil (Myriophyllum spicatum) was first discovered in the Chain of Lakes. By 1992, MPRB and the Hennepin County Conservation District began managing milfoil in the Chain of Lakes with financial support from the MDNR. In the early 1990s, MPRB staff tracked areas of invasive Eurasian watermilfoil (EWM) versus native northern watermilfoil (Myriophyllum exalbescens). Later, MPRB partnered with Dr. Ray Newman of the University of Minnesota. Dr. Newman conducted some early studies in the Minneapolis lakes and the potential use of a native beetle, Euhrychiopsis lecontei, that prefers to feed on EWM and can be grow to high enough densities to diminish the growth of EWM in lakes in certain situations.
MPRB first began managing aquatic invasive species when Eurasian water milfoil was discovered; however, EWM was not the first invasive aquatic species to be introduced to the MPRB lakes. In 1910, curly-leaf pondweed (Potamogeton crispus) was the first documented aquatic invasive species in the state of Minnesota. Curly-leaf pondweed has an unusual life cycle in that it is an annual that begins growing under the ice and dies off in June. After mild winters, curly-leaf pondweed often produces thick mats of vegetation in the spring that is a nuisance for boating; however, this plant can be held to low levels of growth by harsh Minnesota winters. Macrophyte surveys by Shapiro (1974) documented curly-leaf pondweed in Lakes Bde Maka Ska, Harriet, Isles, and Nokomis. The surveys carried out by Shapiro were in late-July which was likely too late in the season to capture the full extent of curly-leaf pondweed in the Minneapolis Lakes.
The 1974 Shapiro surveys found that aquatic plants grew to only about 15 feet of depth in Lakes Bde Maka Ska and Harriet. Lake of the Isles and Lake Nokomis only had plants growing out to about 5 to 6 feet of water. Wirth Lake only had a shallow ring of aquatic plants growing out to a depth of 3 feet. Intact and robust native plant communities are better able to withstand invasive species. Therefore, the lack of plant growth throughout the littoral zones of the Minneapolis lakes may have left them vulnerable to invasion by EWM two decades later.
Most other aquatic invasive species only occur in a few lakes in the MPRB system as can be seen from Table 17-9 and Figure 17-6 (MDNR aquatic invasive species in Minnesota, 2015). Brazilian water weed (Egeria densa) was found in Powderhorn Lake in 2007 during a routine MPRB plant survey. The MDNR mapped areas where the invasive plant was growing and chemically treated those areas with diquat, an herbicide approved for aquatic use. Brazilian water weed has not been identified in the lake since treatment. This plant can grow to extremely high densities limiting growth for native plants. It is a common aquarium plant and likely found its way to Powderhorn Lake via an aquarium release. Powderhorn was delisted for Brazilian water weed in 2014 after five years of surveys not finding the plant.
Chinese mystery snails (Bellamya chinensis) have been identified by MDNR and MPRB in Loring Pond, Powderhorn Lake, and Grass Lake as shown in Figure 17-6 and Table 17-9. The Chinese mystery snail, which is native to Asia, was introduced to California in 1892 and was found on the East Coast by 1915 (MDNR, AIS website). The species is a popular aquarium snail and new populations are often a result of an aquarium release. This species has the capability of growing to high densities and tends to have boom and bust cycles. When the population reaches the bust portion of the cycle, large concentrations of dead snails can ring the shoreline and create odor and aesthetic issues as they decompose.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-13 Zebra mussels (Dreissena polymorpha) have been found in Lake Harriet and Lake Hiawatha. Lake Hiawatha was designated infested with zebra mussels in 2010 due to its connection with Minnehaha Creek and Lake Minnetonka. In August 2013, zebra mussels were confirmed as present in Lake Hiawatha and have been found around the entire lake in subsequent surveys. Similarly, Lake Nokomis has been declared infested with zebra mussels due to its connection with Minnehaha Creek; however, as of fall 2017, zebra mussels have not been confirmed to be present in Lake Nokomis. A single adult zebra mussel was discovered in Lake Harriet in 2017. No additional mussels were found after 67 hours of shoreline, snorkel, and scuba surveys around the lake. Continued searching will take place at Lake Harriet in the future to track the population of the invasive mussel in the lake. The Minnehaha Creek Watershed District (MCWD) and MPRB have performed shoreline assessments on MPRB lakes each fall since zebra mussels were confirmed in Lake Minnetonka in 2010. MPRB also deploys sampler plates in Bde Maka Ska, Harriet, and Hiawatha as an early detection method. Additionally, Friends of Lake Nokomis monitors sampler plates at two locations in Lake Nokomis. No zebra mussels were found in the other Minneapolis lakes via MPRB and MCWD’s early detection program in 2017.
Lakes containing European carp (Cyprinus carpio) and goldfish (Carassius auratus) are identified in Figure 17-6. The data shown were taken from MDNR Lake Finder and is based on MDNR fish surveys. Other Minneapolis lakes may have carp or goldfish but these species have not been identified specifically in fish surveys. Each of these species can reproduce to very high densities. At high densities, these bottom-feeding fish are capable of disturbing lake beds to the extent that water quality can be diminished. Lakes with an overgrowth of European carp typically have high phosphorus concentrations, low water clarity, and little to no aquatic plant growth. Carp eat vegetation and can alter or destroy the aquatic plant community in a lake. In 1977, MDNR chemically treated Wirth Lake with rotenone to remove rough fish and stocked the lake with largemouth bass, walleye, and channel catfish. In 2002, the MCWD sponsored a carp removal at Lake Nokomis.
Table 17-9. Aquatic invasive species established in MPRB lakes, the number of lakes where the species are found and the data source used.
Common Name Scientific Name # of Lakes Data Source
Curly leaf pondweed Potamogeton crispus 11 MPRB
Eurasian watermilfoil Myriophyllum spicatum 10 MDNR infested waters list
European carp Cyprinus carpio 8 MDNR fish survey
Chinese mystery snail Bellamya chinensis 3 MDNR
Zebra mussel* Dreissena polymorpha 3 MDNR infested waters list
Goldfish Carassius auratus 2 MDNR fish survey
Brazilian water weed** Egeria densa 0 MDNR infested waters list
*Lake Nokomis is considered infested with zebra mussels due to its connection with Minnehaha Creek and Lake Minnetonka. The species has not been confirmed present in Lake Nokomis as of fall 2014. **Treated successfully in 2007 by MDNR and delisted in 2014.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-14 Zebra Mussels European Carp Goldfish Brazilian Waterweed Chinese Mystery Snail Eurasian Watermilfoil Curly Leaf Pondweed 5
4
3
2
1
0
Figure 17-6. Aquatic invasive species found in MPRB Lakes. Birch Pond, Ryan, and Grass Lakes have not been fully surveyed for invasive species. Zebra mussels have not been confirmed present in Lake Nokomis. Brazilian water weed in Powderhorn was successfully treated with chemicals in 2007.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 17-15 18. PUBLIC BEACH MONITORING
BACKGROUND
The Minneapolis Park and Recreation Board (MPRB) has twelve official beaches located on six lakes (Figure 18-1). Prior to 2003 the City of Minneapolis Environmental Health Department monitored the beaches for fecal coliform bacteria. The MPRB began beach monitoring in 2003 and tested the beaches for Escherichia coli (E. coli) as well as fecal coliform bacteria. From 2004 to the present MPRB Environmental Management staff monitored the beaches for E. coli alone as recommended by the US Environmental Protection Agency (US EPA). US EPA guidelines for E. coli require that a single sample should not exceed 235 organisms per 100 mL of water and that the geometric mean of not less than 5 samples equally spaced over a 30-day period should not exceed 126 organisms per 100 mL of water (US EPA, 1986). MPRB followed this set of guidelines for the 2004 and 2005 beach seasons. Epidemiological testing allowed the Minnesota Pollution Control Agency to develop an inland lake standard of 1,260 organisms per 100 mL which MPRB has followed since 2006.
Figure 18-1. Map MPRB public beaches monitored in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 18-1 A great diversity of pathogenic microorganisms exists, and testing for a large array of microbes would be time consuming and expensive. Due to this difficulty, E. coli is used as an indicator organism for monitoring and regulation. E. coli is a proxy for the measure of fecal contamination in recreational waters (US EPA, 2005). Indicator organisms do not cause illness under normal conditions which makes them useful when determining if a potential health risk is present in the lake water. Bacteria can enter the aquatic environment from agricultural and stormwater runoff, direct discharge of waste from mammals and birds and from untreated human sewage. Elevated bacteria levels generally occur in aquatic environments after rain events when bacteria from various sources are washed into the lakes. Elevated bacteria levels in MPRB lakes usually return to normal levels within 24 to 48 hours of a rain event.
Potential sources of E. coli in lake water include:
• foreshore beach sand • organic debris • leaking diapers, bather defecation • polluted stormwater runoff • sewage spills near the beach • sewer line break discharges • stream inflows • wild and domestic animal waste (such as geese, gulls, raccoons, dogs, etc.).
Research originally used to develop E. coli as an indicator organism held that it does not survive well outside of the digestive systems of warm-blooded animals. Half-lives of approximately 1 day in water, 1.5 days in sediment, and 3 days in soil were once thought to be typical survival rates of E. coli outside of its host environment (Winfield and Groisman, 2003).
E. coli has been found to survive and grow outside of its host environment. New research shows that algae can be a potential source of E. coli. Whitman et al. (2003) found that Cladophora (green algae) mats in Lake Michigan are capable of supporting E. coli in significant numbers. Bacteria from the dried mats grew upon re-hydration even after 6 months. Shigella, Salmonella, Campylobacter, and a shiga toxin-producing strain of E. coli (STEC) have also been found to be associated with a common filamentous algae species, Cladophora (Byappanahalli et al, 2009).
Beach sand has also been identified as another potential growth medium for E. coli. Whitman and Nevers (2003) have shown that E. coli can sustain itself in wet beach sand that can then serve as a non-point source of bacterial contamination. Another study by Byappanahalli et al. (2003) found E. coli to be ubiquitous and persistent in a Midwestern stream. E. coli was common in stream banks and wetted sediments acting as a source of contamination to the stream. Genthner et al. (2005) found that after tidal events, the swash zone (area of beach where waves continuously wash up on the sand) harbored higher densities of microorganisms and indicator bacteria, which is partially attributable to entrapment. It has been shown that biological (e.g. nutrients and protection from predation) and physical (e.g. particulate matter, periodic wetting and drying, and protection from solar irradiation) factors enhance bacteria survival while providing a growth-promoting environmental niche. In studies in the Upper Midwest, Ishii et al. (2005) found significant populations of viable, naturalized E. coli in northern temperate soils in three Lake Superior watersheds. Ishii et al. (2007) found that the distribution of human and naturalized sources of E. coli at beaches can change over the course of a summer.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 18-2 METHODS
Samples were collected at Nokomis Main and Wirth beach beginning on 5/22/17 to allow for early season weekend swims. Samples were collected from all twelve MPRB beaches every Monday during the beach season (6/5/17 through 8/28/17). Beaches monitored in the 2017 MPRB program were:
• Bde Maka Ska 32nd Street • Bde Maka Ska Main (North) • Bde Maka Ska Thomas (South) • Cedar Main (South) • Cedar Point • East Cedar (Hidden) • Harriet Main • Harriet Southeast • Hiawatha • Nokomis 50th Street (East) • Nokomis Main • Wirth Main
Two E. coli samples were taken from each beach in knee deep water (1.8 feet) roughly six to twelve inches below the surface. The samples were then transported in an ice water bath to Instrumental Research Incorporated’s lab (IRI). IRI used a Colilert-Quanti Tray to determine the most probable number (MPN) of E. coli colonies in the samples. Field duplicates were also collected every sampling day on a rotating schedule. Water and air temperatures were measured using a digital thermometer. Rain data was collected at the MPRB South Side Service Center using a tipping bucket rain gage.
Other parameters collected in the field when samples were taken included:
• air temperature • current weather • LAURI parameters of beach (For additional information on the LAURI see Section 1) • number of adults, children, and children in diapers not in the water • number of geese, ducks, and gulls on the beach • number of swimmers in the water broken down by adults, children, and children in diapers • water quality parameters (when permitted) • water temperature • comments (anything unusual, visible fecal material).
Additional data compiled in the office were:
• amount of previous day’s rainfall • wind speed and direction • duration of rain event • hours since last rain event • intensity of rain event • lake level • beach attendance.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 18-3 RESULTS & DISCUSSION
Specific lake and beach results are discussed in each of the lake sections.
Table 18-1 shows the basic descriptive statistics of E. coli (MPN organisms per 100 mL of water) in the beach water sampled during the 2017 beach season. Most beaches had low season-long geometric means, but there were a couple of beach closures during the 2017 beach season. Lake Hiawatha Beach closed on 6/13/17 due to the single sample limit of 1,260 E. coli per 100 mL of water being exceeded. The beach reopened the next day on 6/14/17 once samples showed E. coli had returned to acceptable levels. There was a significant amount of bird tracks present on the beach during the closure and may have contributed to the observed high E. coli. Lake Hiawatha Beach closed again on 8/15/17 due to a single sample exceedance and reopened on 8/16/17. Once again bird tracks and feathers were noted on the beach at the time of sampling. Lake Hiawatha exceeded the 30-day geomean standard the following week, 8/22/17, and remained closed the final week of the swimming season. Wirth Beach closed on 8/22/17 due to a single sample exceedance and reopened on 8/23/17, when levels returned to acceptable limits. There was a substantial amount of goose poop noted at the time of sampling, which most likely contributed to the high E. coli levels in the water.
Table 18-1. Minimum, maximum, median, mean, geometric mean (entire season), and maximum 30-day geometric mean for E. coli values (MPN/100 mL) from the twelve beaches monitored by the MPRB in 2017.
Statistical Calhoun Calhoun Calhoun Cedar Cedar Cedar Harriet Harriet Hiawatha Nokomis Nokomis Wirth Calculations 32nd Main Thomas East Main Point Main SE 50th Main
Number of 13 13 13 13 13 13 13 13 13 13 15 15 Samples
Minimum 10 3 1 1 1 5 3 3 15 2 2 1
Maximum 569 678 378 281 1212 139 76 91 2420 161 124 1460
Median 45 41 26 16 9 24 11 11 66 19 29 15
Mean 143 154 98 37 105 35 19 21 444 34 45 131
Geometric 57 51 30 15 11 19 12 12 99 19 27 17 Mean
Max 30-Day 101 75 120 28 20 28 19 16 424 28 42 109 Geo Mean
Standard 200 230 121 74 333 43 20 26 815 45 41 372 Deviation
In general, rain and large amounts of birds near the beach are likely the single most influential cause of elevated E. coli levels in Minneapolis lakes. Rain washes the bacteria off hard surfaces and sends it through the storm sewer system to the lakes. Table 18-2 shows the number of storms during the beach season, the amount of rain received in the largest single rain event, the average amount of precipitation per rain event, and the total amount of rain received during the beach season. Rain data was collected at the MPRB South Side Service Center rain gauge.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 18-4 The relationship between rain and E coli at the beaches is complex. Differences in the timing and pattern of rainfall may be more influential on E. coli levels than rainfall amounts. The combination of rain intensity and duration may also influence bacteria at some of the beaches.
Table 18-2. Number of storms, largest storm (inches), average storm (inches), and total rain (inches), for the 2013–2017 beach seasons. A storm is defined as being greater than 0.10 inches and separated by 8 hours.
Year 2013 2014 2015 2016 2017 Number of storms 12 15 18 23 21 Max rain single event 3.0 3.0 2.52 2.60 3.32 Avg rain per event 0.8 0.66 0.69 0.64 0.62 Total Rain in inches 9.66 10.15 12.22 14.71 12.97
It is difficult to assess the quality of water the same day of sample collection since testing requires 24 hours. The lag time between sample collection and receipt of test results can result in unnecessary beach closures and/or exposure to poor water quality. A study by Ha Kim and Grant (2004) found that the public is incorrectly notified about current water quality status and beaches are incorrectly posted up to 40% of the time. An example of this occurring at MPRB beaches happened twice in 2017. The first time was when a sample was taken at Lake Hiawatha Beach on June 12th. The beach was closed around noon on the 13th when the results were found to exceed the single sample limit and the beach was re-sampled. The results from that sample came back on June 14th and were below the limit. The beach was open on June 12th when it should have been closed and closed unnecessarily on June 13th when it should have been open. The 24-hour delay caused posting errors on 2 days. A similar scenario occurred at Wirth Beach on August 21st.
Beach management decisions are made using the best available methods and data. MPRB Environmental Stewardship staff seeks out the latest E. coli and beach pathogen research as well as technology for a rapid E. coli test to eliminate unnecessary closures. In the past, staff members have also participated in a Metro-Wide Beach Regulators group to enhance consistency among the different organizations operating beaches in the Metro.
In the US EPA Environmental Health Perspective (2005), the number of illnesses attributable to recreational water exposures was reported to be increasing. In Minnesota, there were 8 reported outbreaks which were traced to recreational contact at lakes from 2007-2016. The outbreaks were associated with 6 different pathogens (Minnesota Department of Health, 2017). It should be noted that none of the waterborne illness outbreaks were at Minneapolis beaches.
Communicating the results of beach monitoring with the public is a very important aspect of the process and offers an opportunity for water and public health education. A phone and email tree is utilized to quickly notify staff and elected officials of beach closures and re-openings. A Beach Information Telephone Line (612.313.7713) is updated daily on beach closures due to bacteria testing. Results from testing are also put on the MPRB website the day results are received (https://www.minneapolisparks.org/park_care__improvements/water_resources/beach_water_resourc es/). The communication efforts were successful in 2017 and offered the public many opportunities to obtain information regarding beach water quality and closures.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 18-5 19. WEBBER NATURAL SWIMMING POOL
HISTORY
Webber Park was named in 1939 for Charles C. Webber, who donated the land in memory of his late son. Originally, a dam across Shingle Creek created a 2-acre pool known as Camden Pond. Overflow water was used to fill this swimming pool in summer and the pond was used for ice skating in winter. In the 1950s, a flood prevention project rerouted Shingle Creek to the north to increase the drop in the creek from 1.5 to 5 feet. The project removed the dam that impounded Webber Lagoon and created the configuration of Webber Pond that existed until 2013.
Figure 19-1. Upper Pool at Webber Natural Swimming Pool and pool house in fall 2016.
On August 14, 2013, Webber Park was redeveloped to make way for the Webber Natural Swimming Pool (NSP). Minneapolis Park and Recreation Board (MPRB) contracted BioNova Natural Pool and Landform companies to create the first public natural filtration swimming pool in the United States. The pool consists of two swimming basins (upper and lower pools) and a regeneration basin. Additionally, a stormwater pond was designed to treat runoff from the area surrounding the pool. The pool’s total swimming area covers more than 21,000 square feet and contains approximately 500,000 gallons of water. The upper pool is smaller and shallower (3’7” depth). The lower pool features an open swimming area (6’4” depth), jumping platform area (11’7” depth) and
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-1 lap swimming area (6’0” depth). The Webber NSP relies on a biological filtration system rather than chlorine disinfection to maintain water quality. Water flows from the swimming area through fine filters that remove particulate matter and then through a 16,500-square foot regeneration pond to remove nutrients before returning to the swimming area. The regeneration basin contains plants, gravel and other aggregates, but does not contain any soil. Therefore, the plant and microbial communities must rely on the nutrients in the water to grow, making nutrients unavailable to nuisance algae. All the water is drained out of the pool, circulated through the regeneration basin, and pumped back into the pool every 12 hours.
The pool opened in July 2015 and was only open for swimming on the weekends. 2017 was the second full year of operation, with the pool open Tuesday-Sunday from Memorial Day weekend to Labor Day.
BACKGROUND
Fecal contamination of water is a potential health risk to the users of recreational waters. Escherichia coli (E. coli) is an indicator for fecal contamination in recreational waters. While indicator organisms themselves do not cause illness under normal conditions, they may indicate the presence of other disease causing pathogens. According to Bionova Inc, the presence of elevated Enterococci indicates the presence of birds in the regeneration area and elevated Pseudomonas aeruginosa indicates the presence of excess sediment in the pool system, indicating that maintenance must be increased.
Potential sources of bacteria to the pool include: wild and domestic animal waste, leaking diapers, bather defecation, organic debris, swimmers’ bodies, and naturalized growth on the NSP surfaces.
From 2004 to the present, MPRB Environmental Management staff monitored the Minneapolis beaches for E. coli as an indicator of the presence of harmful bacteria as recommended by the US Environmental Protection Agency (USEPA). Knowledge gained from the E. coli monitoring program, along with EPA, World Health Organization (WHO), and FLL guidance has been used to create the Webber NSP standards and protocols.
The NSP at Webber Pond is held to a combination of current standards recommended by the German FLL (Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e.V.: Landscaping and Landscape Development Research Society), US EPA Beach Act STV standards (EPA, 2012), and WHO standards until US EPA or State of Minnesota approved standards are available for natural swimming pools. The FLL standards Scope of Validity (FLL, 2011) applies to “operation inspection, servicing, upkeep, and repair of outdoor pools with biological water purification used publicly, commercially, and not solely for private purposes.”
The FLL (2011) standards document notes that 95% of samples should meet the guidelines during 1 year of operation in order for sampling to be reduced to twice per week. MPRB has interpreted this statement to mean that it is expected, in a well-run NSP, that 5% of the samples in a year may exceed standards. As a certain number of periodic exceedances are likely, it is necessary to plan for pool management during times when FLL standards are not met. After consideration of several sets of standards, and consultation with Bionova engineers on European protocols, it was decided by MPRB that the EPA Statistical Threshold Values (EPA STV) would be used as a “not to exceed standard” for the Webber NSP (Table 19-1). EPA Beach Act Standards were not created for use in NSPs but are at similar, slightly more restrictive levels than the European Union Freshwater Standards (EU,
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-2 2006) that are used to regulate certain types of NSPs in Europe. EPA STV values are lower than current State of Minnesota Standards for E coli, and by using this more restrictive standard, it is expected that public health will be preserved. Because of the type of NSP built at Webber Pond, the FLL standard should be the primary standards used to measure the pool in order to be most protective of public health and the EPA STV values used secondarily as a “not to exceed” level. Since there is no EPA standard set for Pseudomonas aeruginosa, a WHO guideline from 2000 (WHO, 2000) will be used as a “not to exceed” for this organism.
Table 19-1. MPRB Standards for Webber NSP.
Not to exceed FLL EPA STV Indicator Organism (CFU/100 ml) (MPN/100 ml) Escherichia coli ≤100 ≤410 Enterococci ≤50 ≤130 Pseudomonas aeruginosa ≤10 ≤100 (WHO)
Testing available to MPRB produces results in units termed MPN or most probable number rather than CFU (colony forming units). It is MPRB’s intention to use State of Minnesota, EPA methods, and/or FLL equivalent tests, and receiving data in the MPN format meets these criteria.
When bacteria levels are at or below FLL standards, the pool will remain open and regular maintenance will continue. If FLL standards are exceeded once, the pool will be resampled after appropriate additional maintenance. If the FLL standard is still exceeded, the pool will close until the standard is met again. If the EPA STV or WHO value is exceeded, the pool will be closed. After appropriate maintenance, the pool will be retested and reopened when bacteria levels fall at or below FLL standards.
FLL (2011) standards note that Legionella bacteria testing is required in regular sampling if pool water is technologically heated. Since Webber NSP is not technologically heated, and is only heated by the sun, these bacteria will not be part of the regular sampling program at this time.
Excess algal growth can not only be a nuisance to swimmers, but also a safety concern if the blooms limit visibility to the bottom of the pool. Algal biomass is restricted by removing nutrients, most notably phosphorus, from the water and sequestering them in the plants and biofilms within the regeneration basin. Any fresh water used must first be run through a phosphate filter to limit the phosphorus concentration in the pool water in order to limit algae growth.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-3 METHODS
Environmental Management staff monitors water in the upper pool, lower pool and regeneration basin for E. coli, Enterococci and Pseudomonas aeruginosa bacteria throughout the season. The bacteria samples for the regeneration basin were taken from the pumps pumping water from the regeneration basin to the pool. Bacteria samples were collected every Monday from May through early-October. Additional sampling is performed on Wednesday and Thursday if the Monday results exceeded the FLL standard.
MPRB Maintenance staff records the water transparency by lowering a black and white 20-cm diameter Secchi disk into the deep diving well of the pool three times per day. Probes were installed in the pumphouse to monitor water temperature, pH, oxidative reduction potential (ORP), and conductivity.
Grab samples were taken from each basin (upper pool, lower pool, and regeneration basin) for total phosphorus, soluble reactive phosphorus, total nitrogen, nitrate/nitrate, ammonia, alkalinity, hardness, chlorophyll-a, and phytoplankton enumeration. Both chlorophyll-a and phytoplankton samples were stored in opaque bottles for analysis with the phytoplankton samples preserved with a 25% glutaraldehyde solution. Horizontal zooplankton tow samples were taken in each basin using a 80-µm mesh tow net retrieved at a rate of 1 m/s. The 80-µm mesh was rinsed with distilled water or ethanol from the outside of the net. The samples were preserved with 90% denatured histological ethanol to a mix of approximately 50% sample 50% ethanol.
Immediately following collection all samples were placed on ice in a cooler and stored at approximately 4°C. Samples were transported to the contract laboratory for analysis within 8 hours of collection. Sampling procedures, sample preservation, and holding times followed procedures described in Standard Methods (2005) or US Environmental Protection Agency (US EPA, 1979 (revised 1983) and can be found in Table 19-2. The contract laboratory for chemical analyses was Instrumental Research, Inc. (IRI). PhycoTech, Inc. analyzed all phytoplankton and zooplankton samples.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-4 Table 19-2. List of physical, chemical and biological parameters along with the method used in 2017.
Parameter Sampling location MPRB method Escherichia coli Upper pool, Lower pool, & Pumps SM 9223 Colilert
Enterococcus Upper pool, Lower pool, & Pumps Enterolert
Pseudomonas aeruginosa Upper pool, Lower pool, & Pumps Pseudolert
Water transparency Upper pool & Lower pool Secchi Disk Fine filter tank & Regeneration Water temperature Temperature probe basin Fine filter tank & Regeneration pH value pH probe basin Oxidative Reduction Fine filter tank & Regeneration ORP probe Potential (ORP) basin Fine filter tank & Regeneration Conductivity Conductivity probe basin Upper pool, Lower pool, & Luminescent dissolved Dissolved oxygen Regeneration basin oxygen probe Upper pool, Lower pool, & Alkalinity SM 2320 B. Regeneration basin Upper pool, Lower pool, & Total phosphorus SM 4500 P.E. Regeneration basin Soluble reactive Upper pool, Lower pool, & SM 4500 P E. phosphorus Regeneration basin Upper pool, Lower pool, & Total nitrogen SM 4500 N C. Regeneration basin Upper pool, Lower pool, & Nitrate/nitrate USGS I-3520-85 Regeneration basin Upper pool, Lower pool, & Ammonia SM 4500 NO3 E. Regeneration basin Upper pool, Lower pool, & Hardness SM 2350 C. Regeneration basin Upper pool, Lower pool, & Chlorophyll -a SM 10200 H Regeneration basin Phyto - rapid assessment and Upper pool, Lower pool, & Phytoplankton/zooplankton biomass estimate Regeneration basin Zoop - horizontal tow 80 µm
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-5 RESULTS & DISCUSSION
Bacteria
E. coli concentrations were low the entire year in 2017 with levels below 10 MPN per 100 mL for much of the year. No samples exceeded the FLL E. coli standard of 100 MPN per 100 mL in 2017 (Figure 19-2a). Enterococci concentrations were low for most of the year with a spike in levels in mid-August, with concentrations exceeding standards for a week. A total of 87% of the enterococci samples met the FLL standard of 50 MPN per 100 mL in 2017. Five of the samples exceeded the enterococci EPA STV threshold of 130 MPN per 100 mL (Figure 19-2b). The source of the elevated enterococci in August is unknown, but birds are possible source. Numerous anti-bird devices are used around Webber pool; however, the pool is located along a major flyway and it is difficult to deter every bird, especially at night. Only one Pseudomonas aeruginosa samples exceeded the FLL standard of 10 MPN per 100 mL and no samples exceeded the WHO standard of 100 MPN per 100 mL (Figure 19-2c). Pseudomonas is a common bacterium in soils and excess sediment in the pool is typically thought to be the cause of elevated concentrations. Extra cleaning around the pool followed elevated bacteria concentrations to eliminate any suspected source.
Water Chemistry
Temperature, pH, conductivity, and ORP were measured at two locations: water from the fine filter tank (System 1) and water leaving the regeneration basin (System 2). Water temperature was above the FLL recommendation of less than 25 °C (77 °F) for parts of July. However, temperatures did not exceed 28 °C (82.4°F), which the FLL states can only be tolerated for up to five days (Figure 19-3a). The pH was initially higher than 8.5 following filling the pool in late May but remained between 7 and 8 the rest of the season (Figure 19-3b). The FLL recommends the pH of the pool to be between 6 and 8.5 since people with sensitive skin may experience some skin irritation with pH values greater than 9. Specific conductivity was within the FLL recommended range (200-1000 µS cm-1) the entire season (Figure 19-3c). The conductivity probe for System 1 stopped working in May, but the conductivity in the two systems should be similar. There is no FLL recommended value for ORP, but Bionova engineers recommend values greater than 150 mV. ORP values were greater than 150 mV for the entire year with values typically fluctuating between 300 and 450 mV for much of the year (Figure 19-3d).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-6
Figure 19-2. Webber pool E. coli (a), Enterococci (b) and Pseudomonas aeruginosa (c) concentrations in 2017. The dashed horizontal lines represent the FLL standard and solid horizontal lines represent either the EPA STV threshold for E. coli and Enterococci or the WHO guideline for Pseudomonas. Note the log scales on each y-axis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-7
Figure 19-3. Webber pool temperature (a), pH (b), conductivity (c), and dissolved oxygen (d) in 2017. The horizontal lines represent the FLL recommended values and the dashed horizontal lines represent acceptable levels as an exception according to the FLL.
Similar to the previous years, Chlorophyll-a values initially were high following the pool being filled and then decreased to low (<2 µg/L) for the rest of the season (Figure 19-4a). Total phosphorus levels were initially above the FLL recommendation at over 0.010 mg/L due to the pool being filled using the city water supply which contains high levels of polyphosphate as an anti-corrosion agent. Phosphorus concentrations decreased throughout the year and fell within the FLL recommended value (< 0.010 mg/L) by the end of the season (Figure 19-4b). The excess phosphorus likely fueled the higher algal concentration in May. Nitrate/nitrite concentrations ranged from below reporting limit (< 0.030 mg/L) to 0.395 mg/L in 2017, well within the FLL recommendation of less than 30 mg/L (Figure 19-4c). Ammonia was also measured but only three samples, one in May and two in July, were above the reporting limit (< 0.250 mg/L), with a maximum concentration of 0.306 mg/L. Alkalinity in the pool increased throughout the year but was still below the FLL recommended value of greater than 200 mg/L every month (Figure 19-4d). Hardness was also below the FLL recommended value (100 mg/L) as levels fluctuated between 70 and 92 mg/L throughout the year (Figure 19-4e).
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-8
Figure 19-4. Webber pool chlorophyll-a (a), total phosphorus (b), nitrate/nitrite (c), alkalinity (d) and hardness (e) in 2017. The horizontal lines represent the FLL recommended values.
Phytoplankton
Phytoplankton biovolume by division is displayed in Figure 19-5. The May algal bloom is evident and consisted of mainly green algae (Chlorophyta), diatoms (Bacillariophyta), and chrysophytes. Algal biomass was higher in the upper pool in July and the regeneration basin in September but was extremely low the remainder of the year in the pools can was largely comprised of a mix of green algae, diatoms, and blue-green algae (Cyanophyta). Algal biomass was below the FLL recommended value of 1 mm3/L in all three basins the entire year.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-9
Figure 19-5. Webber pool phytoplankton biomass in 2016. The horizontal line represents the FLL recommended maximum value.
Zooplankton
Zooplankton was in low numbers in all three basins in 2017 (Figure 19-6). The zooplankton community is important for filtering bacteria in the pool water. Copepods have been found to have the greatest filtration capacity (64.8 ml/ind/day), followed by cladocerans (33.3 ml/ind/day) and rotifers (8.5 ml/ind/day) (Eydeler et al. 2010). The majority of the zooplankton in the pool basins were juvenile or nauplii copepods, rotifers, and cladocerans. There were some protozoa in the regeneration basin along with juvenile or nauplii copepods, rotifers, and cladocerans.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-10
Figure 19-6. Webber pool zooplankton abundance in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 19-11 20. AQUATIC PLANT MANAGEMENT
EURASIAN WATER MILFOIL (MYRIOPHYLLUM SPICATUM)
Eurasian watermilfoil (Myriophyllum spicatum) has been an ongoing concern in several Minneapolis lakes. From an ecological standpoint, it out-competes native species and changes the habitat for fish and other organisms. Milfoil often forms dense floating mats that interfere with boating and swimming.
The Minneapolis Park and Recreation Board (MPRB) primarily uses harvesting to maintain recreational access to city lakes. Only the top two meters of the aquatic plants are removed, and this temporarily allows for problem-free boating and swimming. The MDNR permits limit the area of aquatic plant harvest. Harvesting was completed on Bde Maka Ska, Cedar, Harriet, and Isles in 2017. MPRB Staff removed 80 flatbed truck loads of plants in 2017 which is comparable to 440 cubic yards of aquatic plant material. For harvested acreage see each individual lake section. Additionally, MPRB contracted out harvesting work on Wirth and Nokomis to Waterfront Restoration, LLC, who removed milfoil and other aquatic plants from high traffic recreational areas by hand via SCUBA.
In the early 2000s, the MPRB and the University of Minnesota released aquatic weevils that eat Eurasian water milfoil into Cedar Lake, Lake of the Isles, Lake Harriet, and Lake Hiawatha. The weevils were not successful controlling milfoil. The most likely explanation is that the high density of sunfish in the lakes fed on the weevils and limited their population. In 2017, researchers at the University of Minnesota studied to use of underwater cameras to measure macrophyte density in Cedar Lake.
BRAZILIAN WATERWEED (EGERIA DENSA)
In August of 2007, the aquatic invasive species Egeria densa (E. densa) was identified in Powderhorn Lake. The new invasive is native to South America and used extensively in aquariums and water gardens. It is likely that Egeria was introduced to Powderhorn Lake though an aquarium release. In October of 2007, the MDNR spot-treated stands of E. densa with diquat, an herbicide approved for aquatic use. A total of 1.4 acres of the lake were treated across two treatment areas. One area had 28 ounces of Diquat applied and the other area had 2.54 gallons applied. Following five years of MDNR and MPRB surveys not finding E. densa in Powderhorn, the lake was removed from the list of waterbodies infested with this plant in 2014
PURPLE LOOSESTRIFE (LYTHRUM SALICARIA)
In the late 1990s and early 2000s, the MPRB collaborated with the MDNR to introduce leaf-feeding beetles (Galerucella spp.) as a biocontrol for purple loosestrife (Lythrum salicaria). The biocontrol has now naturalized and beetles were found feeding at major purple loosestrife sites on MPRB properties in 2013. MDNR staff continues to monitor beetle release sites. Additionally, MPRB leads a volunteer effort to cut purple loosestrife inflorescence around Lake of the Isles in order to limit seed dispersal. In 2017, 96 hours were spent clipping purple loosestrife and was the fifth year of volunteer management efforts around the lake. MPRB has tracked the spread of purple loosestrife around Lake of the Isles to monitor its spread and efforts to limit seed dispersal.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 20-1 21. Wetland Health Evaluation Project (WHEP)
BACKGROUND
The Wetland Health Evaluation Project (WHEP) began in 1997 in Dakota County with Environmental Protection Agency (US EPA) funding. In 2001, Hennepin County began its own WHEP program as a pilot project. The pilot program was successful at both the county and local levels and has continued as a partnership between the two counties, cities, and other water management organizations. WHEP utilizes teams of trained volunteers to collect and analyze wetland data to characterize wetland health. Hennepin County Environmental Services staff then cross-check, synthesize, and report the collected data back to the partner organizations and to the public.
The Minneapolis Park and Recreation Board (MPRB) has sponsored citizen volunteer teams who monitor wetlands within the park system each year since 2002. Every summer, several wetlands are monitored within Minneapolis depending on the needs of the MPRB. The wetlands monitored during 2017 were: a portion of the wetland edge of Diamond Lake, Grass Lake, Wirth Beach Restored Wetland, Webber Regeneration Pond, and Webber Stormwater Pond. The Roberts Bird Sanctuary wetland is also monitored annually as a reference wetland site for the City of Minneapolis.
For more information see the Minnesota WHEP website at www.mnwhep.org or the Hennepin County WHEP website https://www.hennepin.us/your-government/get-involved/wetland-health- evaluation-program.
METHODS
Volunteers for the project are trained in three sessions by MPCA staff. Training sessions cover monitoring methods, macroinvertebrate identification, and vegetation identification. Spot checks and quality control checks are conducted by other citizen teams and by a technical expert for quality assurance purposes.
Sampling from the wetlands includes both vegetation and invertebrate data. All wetland evaluation and sampling protocols followed the Vegetation Method for Wetland Evaluation (Gernes, 2002). A vegetation survey was performed in a 100-square meter plot considered representative of the entire wetland for each site. Additionally, an invertebrate survey was completed with three full dipnet samples within the emergent vegetation zone and near the shoreline. In 2016, Hennepin County WHEP stopped using bottle traps, which were previously used in addition to two dipnet samples for invertebrate surveys, to align with MPCA protocols.
The information is used to evaluate the wetland’s biological health based on metrics developed by the Minnesota Pollution Control Agency (MPCA). An index of biotic integrity (IBI) has been developed by the MPCA to include both vegetation and invertebrate metrics. The IBI metrics are listed below.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 21-1 Vegetation IBI metrics (identification to genus level)
• Total number of forbs, woody species, and grass-like plants • Total number of mosses, lichens, liverworts, and macro-algae (Chara and Nitella) • Cover of sedge (Carex) • Presence of Bladderwort (Ultricularia) • Total number of “Aquatic Guild” plants • Cover of plants with persistent standing litter
Invertebrate IBI Metrics (identification to family level)
• Number and type of leeches in net and bottle trap samples • Proportion of Water Boatmen (Corixidae) in a bottle trap in relation to the total number of aquatic beetles and all bugs in the sample • Number of types of dragonflies and damselfly nymphs in dip-net samples • Total number of mayflies, plus the number and type of caddis flies, plus presence of fingernail clams and dragonflies • Number of types of snails • Number of taxa above, plus the number of crustaceans, plus the presence of Chaoborus
Ratings developed for the invertebrate and vegetation IBI are shown below in Table 21-1. The IBI assessment is useful to give a wetland a qualitative description that makes it easier to communicate results. Wetlands with poor ratings would have minimal species richness and diversity indicating disturbance and poor wetland health. A wetland with a rating of excellent would have high diversity and species richness indicating a healthy wetland and relatively minimal ecological disturbance. The scoring summary for invertebrates was adjusted in 2016 due to the elimination of bottle traps.
Table 21-1. Ratings for the invertebrate and vegetation IBIs.
Invertebrate Index of Biotic Integrity Vegetation Index of Biotic Integrity Sum of invertebrate Sum of vegetation Interpretation Interpretation metric scores metric scores 5-11 Poor 7-15 Poor 12-18 Moderate 16-25 Moderate 19-25 Excellent 26-35 Excellent
RESULTS AND DISCUSSION
During the summer of 2017, WHEP-trained volunteers monitored six wetlands within the MPRB system. Roberts Bird Sanctuary was monitored for the fifteenth time serving as a reference wetland for the Minneapolis WHEP program. IBI scores for other monitored wetlands can be compared to scores for the reference wetland to determine the effects of inter-annual variation or regional changes (drought, wet periods, plant diseases, etc.) on wetland heath.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 21-2 Roberts Bird Sanctuary (Reference Site) The Roberts Bird Sanctuary is located north of Lake Harriet. The Sanctuary is a natural area that has been preserved, and thus has been used as a reference wetland for the Minneapolis WHEP program. The wetland is estimated to be ten acres in size. The WHEP team accesses the monitoring location near a tamarack stand from the boardwalk. Table 21-2 shows the results for Roberts Bird Sanctuary. In 2017, the wetland scored 27/excellent for invertebrates and 21/moderate for vegetation.
Table 21-2. WHEP scores at the Roberts Bird Sanctuary Site.
Invertebrate Invertebrate Quality Vegetation Quality Year Vegetation Score Score Rating Rating 2003 20 Moderate 17 Moderate 2004 20 Moderate 17 Moderate 2005 22 Moderate 15 Poor 2006 22 Moderate 17 Moderate 2007 28 Excellent 13 Poor 2008 20/22 Moderate/Moderate 21/17 Moderate/Moderate 2009 26 Excellent 19 Moderate 2010 20/22 Moderate/Moderate 21/19 Moderate/Moderate 2011 22/23 Moderate/Moderate 21/23 Moderate/Moderate 2012 26 Excellent 11 Poor 2013 24 Excellent 15 Poor 2014 26 Excellent 15 Poor 2015 22 Moderate 21 Moderate 2016 17 Moderate 21 Moderate 2017 27 Excellent 21 Moderate
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 21-3 Diamond Lake Wetland Fringe Diamond Lake has been monitored thirteen times in the WHEP Program. The wetland fringe at Diamond Lake has typically scored poor in vegetation IBI and the invertebrate IBI has varied (Table 21-3). In 2017, the Diamond Lake Wetland Fringe scored 21/excellent for invertebrates and 19/moderate for vegetation quality. This site is located in an urban setting with a large urban watershed and provides valuable bird habitat.
Table 21-3. WHEP scores at Diamond Lake.
Invertebrate Invertebrate Quality Vegetation Quality Year Vegetation Score Score Rating Rating 2002 8 Poor 13 Poor 2005 14 Poor 7 Poor 2006 16 Moderate 13 Poor 2008 10 Poor 15 Poor 2009 18 Moderate 11 Poor 2010 24 Excellent 20 Moderate 2011 8 Poor 11 Poor 2012 24 Excellent 15 Poor 2013 26 Excellent 15 Poor 2014 19 Moderate 12 Poor 2015 18/16 Moderate/Moderate 19/15 Moderate/Poor 2016 17 Moderate 17 Moderate 2017 21 Excellent 19 Moderate
Grass Lake Wetland Grass Lake was created during the construction of State Highway 62. The highway separated one waterbody into two new lakes: Grass Lake to the north and Richfield Lake to the south. The area is known for bird-watching. The lake has typically been monitored every other year since 2002 as part of MPRB’s lake sampling program (Section 7). 2017 was the third year that Grass Lake was evaluated in the WHEP program and the first since 2004., as presented below in Table 21-4. In 2017, Grass Lake received an invertebrate score of 15/moderate and a vegetation quality score of 15/poor.
Table 21-4. WHEP scores at Grass Lake Wetland.
Invertebrate Invertebrate Quality Vegetation Quality Year Vegetation Score Score Rating Rating 2003 18 Moderate 19 Moderate 2004 16 Moderate 19 Moderate 2017 15 Moderate 15 Poor
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 21-4 Wirth Beach Restored Wetland Wirth Beach Restored Wetland is located near the southern tip of Wirth Lake just southeast of the swimming beach. The site has inlets from the Upper/Lower Wirth wetland complex and parkland and from the basins adjacent to the parking lot to the east of the wetland. The outlet is to Wirth Lake. Additionally, there are multiple groundwater springs at the north end of the wetland. The wetland was historically filled with debris from the old Wirth Beachhouse. Debris was removed and the wetland was replanted in 2011. The previous vegetation type of the wetland was a mix of cattail/purple loosestrife.
2017 was the fourth year of monitoring at the Wirth Beach Restored Wetland (Table 21-5). Wirth Beach Restored Wetland received a score of 17/moderate for the invertebrate IBI and a score of 27/excellent for vegetation.
Table 21-5. WHEP scores at Wirth Beach Restored Wetland.
Invertebrate Invertebrate Quality Vegetation Quality Year Vegetation Score Score Rating Rating 2014 18 Moderate 25 Moderate 2015 20 Moderate 27 Excellent 2016 15 Moderate 25 Moderate 2017 17 Moderate 27 Excellent
Webber Regeneration Basin The Webber Regeneration Basin is located in Webber Park and is part of the Webber Natural Swimming Pool. The 0.4 acre created wetland receives no runoff from the surrounding land. Rather, the pool water continuously circulates through the basin with the entire 500,000 gallons of pool water circulating through in 12 hours. The regeneration basin contains plants, gravel and other aggregates, but does not contain any soil. Therefore, the plants need to acquire all their nutrients from the water itself. The pool is filled with city water in the spring and the only other water added is run through a phosphate filter to limit phosphors in the system. 2017 was the second year the Webber Regeneration Basin was included in WHEP monitoring (Table 21-6). Webber Regeneration Basin received a score of 19/excellent for the invertebrate IBI and a score of 27/excellent for vegetation in 2017.
Table 21-6. WHEP scores at Webber Regeneration Basin.
Invertebrate Invertebrate Quality Vegetation Quality Year Vegetation Score Score Rating Rating 2016 9 Poor 21 Moderate 2017 19 Excellent 27 Excellent
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 21-5 Webber Stormwater Pond The Webber Stormwater Pond is located adjacent to the Webber Natural Swimming Pool in Webber Park. The 0.25 acre pond was created to treat runoff from the surrounding 3 acres before it enters into Shingle Creek. 2017 was the second year the Webber Stormwater Pond was included in WHEP monitoring (Table 21-7). Webber Stormwater Pond received a score of 21/excellent for the invertebrate IBI and a score of 29/excellent for vegetation in 2017.
Table 21-7. WHEP scores at Webber Stormwater Pond.
Invertebrate Invertebrate Quality Vegetation Quality Year Vegetation Score Score Rating Rating 2016 11 Poor 21 Moderate 2017 21 Excellent 29 Excellent
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 21-6 22. NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES) MONITORING
BACKGROUND
As part of the federal Clean Water Act, the Minneapolis Park and Recreation Board (MPRB) and the City of Minneapolis are co-signatories on the Environmental Protection Agency (EPA) issued National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit. As a Phase I City, the Minneapolis NPDES permit has a stormwater monitoring requirement. The MPRB has performed the NPDES MS4 stormwater monitoring requirement since 2001. Monitoring has included four different land uses (parkland, residential, mixed use, commercial/industrial) as well as Best Management Practice (BMP) devices. BMPs are devices (e.g. grit chambers, CDS units, ponds, etc.) or practices (e.g. street sweeping, public education) used to treat and clean stormwater. The purpose of the MPRB NPDES stormwater monitoring is to characterize the quantity and quality of runoff from small areas representing various types of land use under a no-BMP scenario. The results do not represent actual conditions for either runoff quantity or quality because there are numerous BMPs and, other structural controls, and management practices that reduce pollutants in stormwater runoff and/or temper stormwater runoff quantity in the larger watershed.
At the beginning of the first NPDES MS4 permit (2001-2004), the MPRB and City of Minneapolis partnered with the City of St. Paul to fulfill the NPDES monitoring requirements outlined in the permit. Five sites in Minneapolis and St. Paul were jointly monitored between 2001–2004. In 2005, the MPRB stopped monitoring stormwater in St. Paul, and four new sites in Minneapolis were selected for monitoring. In 2006, new sites were chosen in Minneapolis to comply with the NPDES permit and to assist with modeling and load allocation efforts. These four sites represent the major land uses in Minneapolis: residential, commercial/industrial, mixed use, and parkland.
In 2017, four representative Minneapolis land use sites: Site 6 (22nd/Aldrich, residential), Site 7 (14th/Park, mixed use), Site 8a (Pershing Park, parkland), and Site 9 (61st/Lyndale, commercial) were monitored for stormwater runoff quantity and quality. While, again, the results do not represent actual impacts of stormwater discharge to receiving waters because they do not reflect the positive effects of structural BMP controls and management practices. They are nevertheless useful for comparing land uses and to create baseline conditions for water quality modeling exercises. The BMP sites monitored (Winter Infiltration Basin, 24th & Elm Infiltration Basin, and Lowry Sand Filter) provide information as to their functioning and efficacy. The Minneapolis NPDES monitoring allows the City to characterize its stormwater for pollutants and judge how effective the BMP’s installed are at removing the pollutants.
METHODS
Site Installation
The ISCO equipment installed at each site included a 2150 datalogger, a low-profile area velocity (AV) probe, 2105 interface module, either a 2105ci or 2103ci cell phone modem, and a 3700 sampler. Site 9 (61st/Lyndale) had an additional 2160 laser probe installed on 4/25/17. The 3700-sampler 2017 Water Resources Report – Minneapolis Park and Recreation Board Page 22-1
collected stormwater through 3/8” inner-diameter vinyl intake tubing complete with a strainer. The dataloggers flow-paced the samplers to collect flow-weighted stormwater samples over the entire storm hydrograph. Each site automatically uploaded data, via cell phone modem, to the database server from Monday through Friday. Each site could also be communicated with remotely using Flowlink Pro software to adjust pacing, enable or disable samplers, and to see if a site had triggered.
Equipment installation began when freezing spring temperatures were no longer a concern to prevent AV probe damage. Freezing conditions can damage the pressure transducer in an area velocity probe. See Figure 22-1 for a map of site locations. Site 6 (22nd/Aldrich) and Site 7 (14th/Park) were installed on 4/24/17. Site 8a (Pershing Park) was installed on 4/20/17. Site 9 (61st/Lyndale) was installed on 4/17/17. All sites, except Site 9, were uninstalled on 11/2/17 or 11/3/17. At Site 9, the sampler was removed, but all other equipment was left installed for winter monitoring. See Table 22-1 for site characteristics.
Figure 22-1. Map of the 2017 Minneapolis NPDES monitoring sites.
2017 Water Resources Report – Minneapolis Park and Recreation Board Page 22-2
Table 22-1. 2017 NPDES stormwater monitoring sites in Minneapolis.
Site ID Site 6 Site 7 Site 8a Site 9 22nd St and Pershing Field east of 49th 335 ft. east of 61st St and Location E 14th St and Park Ave S Aldrich Ave S St and Chowen Ave Harriet Ave S
Multi–Family Commercial/Industrial/ Land Use Recreational/Parkland Commercial/Industrial Residential High Rise Residential Area 8.9 acres 13.1 acres 2.5 acres 34.9 acres
Pipe Diameter 18 inches 42 inches 12 inches 36 inches
Outfall ID# 10 – 430J 10 – 430D 57 – 100A/B 71 – 070
Sample Collection and Monitored Parameters
The MS4 permit target frequency for storm event sample collection was 10 samples per site, per year. Ideally, two snowmelt grab samples and two to three flow-paced composite storms were collected per month per site from May through November, for a total of ten composite samples annually. If a sample was missed for one month due to lack of precipitation events, then additional samples were taken the following month.
Table 22-2 shows the parameters tested as part of the MS4 permit for each sample collected. Table 22-3 shows approved methods, reporting limits, and holding times for each parameter as reported by the contract laboratory Instrumental Research, Inc. (IRI). Pace Laboratory analyzed all metals samples.
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Table 22-2. The list of monitored chemical parameters for the NPDES permit. BOD is biochemical oxygen demand. Parameter Abbreviation Units Sample Type BOD –carbonaceous, 5 Day cBOD mg/L Composite Chloride, Total Cl mg/L Composite Specific Conductivity Sp. Cond µmhos/cm Composite E. coli (Escherichia Coli) E. coli MPN/100mL Grab (4X year) Hardness Hard mg/L Composite Copper, Total Cu µg/L Composite Lead, Total Pb µg/L Composite Zinc, Total Zn µg/L Composite
Nitrite+Nitrate, Total as N NO3NO2 mg/L Composite Ammonia, Un-ionized as N NH3 mg/L Composite Kjeldahl Nitrogen, Total TKN mg/L Composite pH pH standard unit Grab/Comp (4X year) Phosphorus, Ortho-P Ortho-P mg/L Composite Phosphorus, Total Dissolved TDP mg/L Composite Phosphorus, Total TP mg/L Composite Solids, Total Dissolved TDS mg/L Composite Solids, Total Suspended TSS mg/L Composite Solids, Volatile Suspended VSS mg/L Composite
Sulfate SO4 mg/L Composite
Table 22-3. Analysis method, reporting limit, and holding times for parameters used by Instrumental Research, Inc and Pace Laboratories. *Sulfate samples were spiked with 10 mg/L, and the spike was later subtracted to lower the reporting limit to 5 mg/L. ǂMetals were analyzed by Pace Laboratories. Parameter Method Reporting Limit Holding Times cBOD, carbonaceous, 5 Day (20°C) SM 5210 B-01 1.0 mg/L 24 hours Chloride, Total SM 4500-Cl- B 2.0 mg/L 28 days Specific Conductivity SM 2510 B-97 10 µmhos/cm 28 days E. coli (Escherichia Coli) SM 9223 B 1 MPN per 100mL < 24hrs Hardness SM 2340 C 5.0 mg/L 6 months Copper, Totalǂ EPA 200.8 1 µg/L 6 months Lead, Totalǂ EPA 200.8 0.5 µg/L 6 months Zinc, Totalǂ EPA 200.7 20 µg/L 6 months Nitrite+Nitrate, Total as N SM 4500-NO3 E 0.030 mg/L 28 days Ammonia, Un-ionized as N USGS I-3520-85 0.250 mg/L 7 days Kjeldahl Nitrogen, Total ASTM D3590 A-02 0.500 mg/L 7 days pH SM 4500 H+ B 0.01 units 15 minutes Phosphorus, Ortho-P SM 4500-PE 0.003 mg/L 48 hours Phosphorus, Total Dissolved SM 4500-PE 0.010 mg/L 48 hours Phosphorus, Total SM 4500-PE 0.010 mg/L 48 hours Solids, Total Dissolved SM 2540 C 5.0 mg/L 7 days Solids, Total Suspended SM 2540 D 1.0 mg/L 7 days Solids, Volatile Suspended EPA 160.4 2.0 mg/L 7 days Sulfate* ASTM D516-90 5 mg/L 28 days
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FIELD QUALITY ASSURANCE SAMPLES
A variety of quality control quality assurance measures were taken to insure defensible data. Ten percent of the samples were laboratory quality assurance samples (e.g. duplicates, spikes). A field blank was also generated for each sampling trip and was analyzed for all NPDES parameters. Field blanks consisted of deionized water which accompanied samples from the field sites to the analytical laboratory. All field blank parameters were below the reporting limits in 2017. As part of the overall QA/QC program, blind monthly performance samples of known concentration were made for all monitored parameters and delivered to IRI.
One equipment blank was also collected in 2017. An equipment blank (~ 2 L sample) was collected at Site 8a (Pershing) on 11/03/17. This site has a standard NPDES stormwater monitoring equipment set up. To collect the equipment blank, a large bottle of deionized water was placed at the strainer end of the sampler tubing. The intake line was filled and flushed with deionized water, simulating the pre-sample flush. After the flush was pumped to waste, a sample of deionized water was collected through the equipment. The sample taken was of sufficient volume to allow analysis of all parameters. All analytes in the equipment blank came back from the laboratory below the reporting limits except Cu (3.1 µg/L) and Pb (0.13 µg/L). These metal samples were rerun and confirmed. Due to the extremely small numbers these values were not subtracted from the data set but were noted.
Field measurements were recorded on a Field Measurement Form in the 2017 Field Log Book. Electronic data from the laboratory were forwarded to the MPRB in preformatted spreadsheets via email. Electronic data from the laboratory were checked and passed laboratory quality assurance procedures. Protocols for data validity followed those defined in the Storm Water Monitoring Program Manual (MPRB, 2001). For data reported below the reporting limit, the reporting limit value was divided in half for use in statistical calculations.
Manual transcription of data was minimized to reduce error introduction. A minimum of 10% of the final data were checked by hand against the raw data sent by the laboratory to ensure there were no errors entering, manipulating, or transferring the data. See Section 29, Quality Assurance Assessment Report for details.
A Chain of Custody form accompanied each set of sample bottles delivered to the lab. Each ISCO sampler tray or container was iced and labeled indicating the date and time of collection, the site location, and the field personnel initials. The collection date and time assigned to the composite sample was the time when the last sample of the composite was collected. The time that each composite sample was collected was recorded from the ISCO sampler onto field sheets. A complete description of methods can be found in the Storm Water Monitoring Program Manual (MPRB, 2001). Common statistics were calculated using Microsoft Excel.
Computer Models used (P-8 and Flux)
The computer model P8 (v3.4) was calibrated and verified for each site, each using five different storms ranging from 0.10 inches to 1.47 inches. P8 was used to estimate daily cubic feet per second (cfs) snowmelt runoff from January through May. Daily temperature and hourly precipitation files used as P8 inputs were obtained from the National Oceanic and Atmospheric Administration (NOAA) National Data Center (NDC). Data from a heated rain gauge located at the Minneapolis/St. Paul International Airport was used for snowmelt water equivalent.
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A description of P8 as described in the software’s introduction: P8 is a model for predicting the generation and transport of stormwater runoff pollutants in small urban catchments. Simulations are driven by hourly rainfall and daily air-temperature time series.
A description of Flux32 as described in the help menu (US Army Corps, 2014): Flux32 is interactive software designed for use in estimating the transport (load) of nutrients or other water quality constituents past a tributary sampling station over a given period of time. The basic approach of Flux32 is to use several calculation techniques to map the flow/concentration relationship developed (modeled) from the sample record onto the entire flow record. This provides an estimate of total mass transport for the whole period of study with associated error statistics. Note that this approach does NOT focus on estimating changes in loads over time (i.e. time series).
An important option within Flux32 is the ability to stratify the data into groups based upon flow, date, and/or season. This is a key feature of the FLUX approach and one of its greatest strengths. In many (most) cases, stratifying the data increases the accuracy and precision of loading estimates.
The P8 model calculated daily average snowmelt runoff, the ISCO Flowlink software calculated daily average runoff. The water chemistry data were put into Flux32 (v3.10) to calculate flow-weighted mean concentrations. In Flux32, all the chemical parameters were run unstratified and, if possible, also run stratified by flow and month. A minimum of three data points are required to group the data for any stratification. Flux32 methods 2 and 6 were recorded for each parameter run (per Bruce Wilson, MPCA). The modeled concentration value with the lowest coefficient of variation was generally chosen and used for the final event mean concentration.
RESULTS AND DISCUSSION
The total volume sampled for each site and total recorded volumes in 2017 are given in Table 22-4 along with the percentage collected in each season. Although the 2017 fall percentage sampled was low, there were no large differences in comparing event mean concentrations to previous years. All snowmelt and E. coli samples were grab samples, all other samples were flow-weighted composites. Flow-weighted composites were either analyzed with the fully required NPDES chemical parameters or analyzed with partial chemical parameters. A limited number of chemical parameters were analyzed when either the sample had expired for some of the chemical holding times (e.g. TDP, cBOD) or when the sample aliquot was too small for a full chemical analysis.
Sampling events are shown in Table 22-5. In 2017, samples with limited parameters were collected 11 times.
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Table 22-4. NPDES site volume totals and seasonal percentages collected for the sampling period 4/25/17 – 10/31/17.
Volumes for 2017 (cf) and Seasonal Percentage Site 6 Site 7 Site 8a Site 9 Collected 22nd/Aldrich 14th/Park Pershing 61st/Lyndale Total volume recorded (with Flowlink) for 2017 (cf) 205,286 682,293 58,410 1,618,680 Total volume of sampled events (cf) 57,172 233,575 20,690 307,045 % sampled ANNUAL 28% 34% 35% 19% % sampled SPRING (May- June) 74% 65% 39% 22% % sampled SUMMER (July- September) 26% 41% 60% 78% % sampled FALL (October- November) 0% 4% 1% 0.1%
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Table 22-5. 2017 precipitation event data and samples collected for NDPES sites. A precipitation event is defined as being greater than 0.10 inches and separated by 8 hours. The rain gage is located at 3800 Bryant Ave. S., Minneapolis, MN. Grab = full chemistry, Full = full chemistry parameters, Partial = partial chemistry parameters (due to low volume or expired holding times), E. coli = grab, - = no data.
Hours Event Start Event End End Rain Duration Intensity since last Site 6 Site 7 Site 8a Site 9 Start Date Time Date Time (inches) (hours) (in/hr) Rain. 22nd/Aldrich 14th/Park Pershing 61st/Lyndale 1/17/2018 14:45 ------Grab, E. coli 1/18/2017 14:15 ------Grab, E. coli Grab, E. coli - Grab, E. coli 2/14/2018 13:25 ------Grab, E. coli - 4/25/2017 14:45 4/26/2017 8:30 0.89 17.75 0.05 128 Full, E. coli Full, E. coli Full E. coli 5/15/2017 12:15 5/15/2017 13:30 0.31 1.25 0.25 158 Full, E. coli Full, E. coli Full Full, E. coli 5/16/2017 3:30 5/16/2017 10:15 0.42 6.75 0.06 4 Full Full Full Full 5/17/2017 0:15 5/17/2017 5:00 0.85 4.75 0.18 14 Full Full Full - 5/17/2017 14:45 5/18/2017 4:15 1.59 13.50 0.12 10 Full Full Full - 6/11/2017 7:45 6/11/2017 9:45 0.90 2.00 0.45 501 Partial Partial - - 6/12/2017 13:45 6/12/2017 16:15 0.32 2.50 0.13 28 Full Full - Full 7/17/2017 21:30 7/18/2017 18:30 1.11 21.00 0.05 405 - - Full Full 7/19/2017 14:45 7/19/2017 21:45 0.27 7.00 0.04 20 Partial Full Full - 7/25/2017 17:00 7/26/2017 7:15 1.25 14.25 0.09 139 Full Full Full - 8/3/2017 5:45 8/3/2017 23:00 0.35 17.25 0.02 191 Full Full, E. coli Full E. coli 8/5/2017 16:45 8/5/2017 17:30 0.13 0.75 0.17 42 - - Partial - 8/6/2017 18:00 8/7/2017 4:45 0.09 10.75 0.01 25 - - Partial - 8/9/2017 10:45 8/10/2017 16:15 1.10 29.50 0.04 54 Full Full Full Full 8/16/2017 2:15 8/16/2017 6:15 0.52 4.00 0.13 50 - Full Full Full 8/16/2017 18:30 8/17/2017 5:15 1.44 10.75 0.13 12 - Full Full - 8/25/2017 5:00 8/25/2017 6:00 0.13 1.00 0.13 192 - - - Full 9/18/2017 3:15 9/18/2017 14:00 0.35 10.75 0.03 323 - - - Full 9/20/2017 1:30 9/20/2017 2:00 0.34 0.50 0.68 35 - - - Full 9/25/2017 1:45 9/25/2017 9:30 0.19 7.75 0.02 120 - - - Full 9/25/2017 19:15 9/26/2017 5:15 0.19 10.00 0.02 10 Partial Partial - Partial 10/21/2017 6:15 10/21/2017 20:15 0.43 14.00 0.03 147 - Partial Partial Partial
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Surcharge events happen during high precipitation or high intensity storm events that exceed the drainage capacity of the pipes. Surcharges occur when water backs up in pipes and creates a hydrostatic pressure head, beyond the diameter of the pipe, which can result in inaccurate daily flow calculations and must be considered when evaluating flow-weighted mean concentrations. If surcharged water inundates the ISCO sampler, the samples are considered contaminated and not analyzed.
Table 22-6 shows the 2017 surcharge event dates at each site. Except for Site 8a, most of the events that caused pipes to surcharge were storms with greater than 1 inch of precipitation.
Table 22-6. Surcharge events in 2017 at the NPDES sites.
Site Surcharge Dates Site 6 (22nd and Aldrich) 5/18, 6/11, 8/14, 8/17, 10/3 18” pipe Site 7 (14th and Park) None 42” pipe Site 8a (Pershing) 5/1, 5/8, 5/16, 5/17, 6/11, 6/14, 6/29, 7/17, 7/19, 7/25, 7/26, 12” pipe 8/9, 8/13, 8/15, 8/26, 9/20, 10/1, 10/2 Site 9 (61st and Lyndale) None 42” pipe
Site 8a (Pershing) had 18 surcharges in 2017. At this site, storms as small as 0.28 inches or as large as 3.32 inches caused pipe surcharging. At this site, two pipes and overland flow enter the manhole basin/vault and exit the outlet, a 12 inch PVC pipe. The Site 8a (Pershing) watershed/area of Minneapolis is lower in elevation than the surrounding areas, causing a regular back up of many stormsewers in the system. Minneapolis Public Works is aware of this problem. Surcharges at this site do not appear to have caused any flooding problems. Site 8a (Pershing) samples appear to not be significantly affected by surcharging because the sampler is secured in an above ground enclosure. Site 6 (22nd and Aldrich) had five surcharges that were not of significant concern.
As required by the MS4 permit, Escherichia Coli (E. coli) grab and pH samples were attempted to be collected quarterly. A total of 13 E. coli grab samples were collected in 2017. At Site 7 (14th and Park) and Site 9 (61st and Lyndale), E. coli grab samples were collected four times. At Site 6 (22nd and Aldrich), E. coli grab samples were collected three times, and at Site 8a (Pershing), E. coli grab samples were collected once. The pH of a stormwater sample from each site was measured at least quarterly by the IRI laboratory.
Required 2017 quarterly E. coli grab and pH sampling was not accomplished at all sites. The fall E. coli samples at all sites were unable to be collected due to low or no flow. Grab samples were not collected at Site 8a after snowmelt. Site 8a was inaccessible for grab sampling after installation due to the sites shallowness requiring monitoring equipment to be installed on top of the manhole.
Seasonal statistics (snowmelt, spring, summer, and fall) of the data for all NPDES sites were calculated and are listed in Table 22-7. The geometric mean was chosen for comparison 2017 Water Resources Report – Minneapolis Park and Recreation Board Page 22-9
purposes because it best handles data with outlier’s present. Seasonal patterns are evident in the data. Snowmelt had the highest geometric mean concentrations for seventeen of the parameters: TP, TDP, Ortho-P, TKN, NH3, NO3NO2, Cl, Hardness, TSS, VSS, TDS, cBOD, Sulfate, Sp. Cond., and pH. Snowmelt had the lowest geometric mean for one parameter, E. coli. The E. coli concentrations are temperature dependent, because bacteria do not survive well in cold conditions. Spring stormwater had the highest geometric mean concentrations for one parameter, Pb. It had the lowest geometric mean concentrations for two parameters: Ortho-P and Hardness. Summer had the highest geometric mean concentrations for one parameter, E. coli. It had the lowest geometric mean for eight parameters: TKN, CL, TDS, cBOD, Sulfate, Sp. Cond., Cu, and Zn. Fall had the lowest geometric mean concentrations for eight parameters: TP, TDP, NH3, NO3NO2, TSS, VSS, pH, and Pb.
Table 22-8 shows the 2017 chemistry data for the sampled storms. These data generally show peaks during snowmelt and early spring for many parameters. Stormwater concentrations can be extremely variable because there are multiple factors affecting the concentrations like the amount or intensity of precipitation or BMP presence and maintenance.
The bold June SO4 data in Table 22-8 are data that failed a blind laboratory monthly performance standard. Internal QAQC procedures flag the data for an entire month for any parameter if the blind standard fails ± 20% recovery. It was deemed the data can be used with caution, noting that performance standards were outside the 80-120% recovery standards.
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Table 22-7. 2017 statistical summary of concentrations by season from all sites (6 –9). STDEV= standard deviation, COV= coefficient of variation, ND = no data. Blue highlighted cells have the highest seasonal geometric mean, orange cells have the lowest seasonal geometric means.
TP TDP Ortho-P TKN NH3 NO3NO2 Cl Hardness TSS VSS TDS cBOD Sulfate Sp.Cond. pH std E. coli Cu Pb Zn 2017 Season Statistical Function mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L µhmos units MPN/100mL ug/L ug/L ug/L SNOWMELT (January-March) MEAN (geometric) 0.606 0.093 0.260 5.20 1.520.360 1668193 161 67 394044284064 8.6 37 34 10 138 SNOWMELT (January-March) MEAN (arithmetic) 0.646 0.145 0.334 5.67 1.640.627 4430231 213 75 77104833 11809 8.7 85 41 16 216 SNOWMELT (January-March) MAX 1.07 0.444 0.798 9.69 2.901.19 6785500 384 111 118369846 19020 10.3 201 54 31 299 SNOWMELT (January-March) MIN 0.412 0.040 0.106 2.83 0.8490.079 1580 33 27 11828 7 218 7.3 781 10 SNOWMELT (January-March) MEDIAN 0.499 0.069 0.192 5.18 1.510.725 5025200 222 85 85793837 16190 8.3 24 50 16 264 SNOWMELT (January-March) STDEV 0.269 0.171 0.279 2.63 0.760.526 2625161 137 33 45422815 10138 1.3 97 19 11 118 SNOWMELT (January-March) NUMBER 555555555555535 5555 SNOWMELT (January-March) COV 0.417 1.18 0.834 0.465 0.4610.839 0.5930.696 0.644 0.448 0.589 0.582 0.456 0.858 0.1531.14 0.469 0.685 0.548 SPRING (April-May) MEAN (geometric) 0.272 0.054 0.037 2.25 0.9430.2924 22 80 29 41 75 74 7.1 481 22 1154 SPRING (April-May) MEAN (arithmetic) 0.348 0.066 0.047 2.83 1.090.3599 24 110 42 6311 6 90 7.1 1810 25 2592 SPRING (April-May) MAX 1.46 0.213 0.091 10.5 2.830.665 4456 334 144 1574912247 8.4 6488 56 98 358 SPRING (April-May) MIN 0.076 0.017 0.005 0.684 0.4280.0151 12 15 6313 28 6.5 47 11 2 10 SPRING (April-May) MEDIAN 0.288 0.059 0.046 2.21 0.9240.3482 20 94 32 49 76 66 7.1 242 22 1358 SPRING (April-May) STDEV 0.314 0.047 0.028 2.32 0.6470.172 1413 87 37 5212 3 66 0.5 2681 12 3292 SPRING (April-May) NUMBER 17 1717 17 17171717 17 17 1416171717 6 17 1717 SPRING (April-May) COV 0.902 0.710 0.580 0.819 0.5950.480 1.480.523 0.786 0.894 0.818 1.12 0.493 0.738 0.0671.48 0.507 1.27 1.01 SUMMER (June-August) MEAN (geometric) 0.193 0.055 0.077 0.906 0.4590.2062 23 43 17 39 45 70 6.7 3316 15 5 36 SUMMER (June-August) MEAN (arithmetic) 0.212 0.069 0.092 1.25 0.5390.2935 25 48 19 50 65 80 6.7 4445 16 8 48 SUMMER (June-August) MAX 0.377 0.222 0.235 2.85 1.190.649 4646 124 48 1352213 212 7.3 9208 29 43 145 SUMMER (June-August) MIN 0.068 0.020 0.029 0.250 0.1250.01518 16 6913 29 6.3 1515 71 10 SUMMER (June-August) MEDIAN 0.214 0.048 0.068 1.13 0.5330.3551 24 41 16 41 55 67 6.7 2613 14 4 45 SUMMER (June-August) STDEV 0.087 0.050 0.058 0.861 0.2630.1839 11 24 9 36 63 47 0.3 4161 6 1134 SUMMER (June-August) NUMBER 27 2323 26 24242727 27 27 232223 2724 3 25 2525 SUMMER (June-August) COV 0.413 0.716 0.624 0.691 0.4880.625 1.890.425 0.496 0.488 0.726 1.00 0.575 0.584 0.0390.936 0.367 1.28 0.711 FALL (Sept-Nov) MEAN (geometric) 0.162 0.027 0.039 1.11 0.4370.1467 31 40 17 74 58 113 6.5 ND 17 4 52 FALL (Sept-Nov) MEAN (arithmetic) 0.181 0.028 0.042 1.17 0.4410.241 1334 46 19 80 79 126 6.5 ND 17 6 59 FALL (Sept-Nov) MAX 0.331 0.039 0.066 1.70 0.4890.673 2468 85 38 1041410222 6.6 ND 26 15 107 FALL (Sept-Nov) MIN 0.066 0.018 0.029 0.697 0.3560.0151 16 16 8 42 26 45 6.2 ND 12 1 24 FALL (Sept-Nov) MEDIAN 0.176 0.028 0.030 1.03 0.4780.140 1634 45 15 94 4 10127 6.6 ND 16 5 48 FALL (Sept-Nov) STDEV 0.088 0.011 0.021 0.423 0.0740.231 1016 25 10 33 62 59 0.2 ND 55 31 FALL (Sept-Nov) NUMBER 933839889933383 ND 888 FALL (Sept-Nov) COV 0.485 0.371 0.506 0.361 0.1670.957 0.7620.473 0.542 0.537 0.416 0.924 0.286 0.468 0.033 ND 0.291 0.775 0.530
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Table 22-8. 2017 NDPES sampled event data by site. ND=no data. Sample TP TDP OrthoP TKN NH3 NO3NO2 Hardness TSS VSS TDS cBOD Sulfate Sp.Cond. pH std E. Coli Zn Date Sampled Time Site Location Type mg/L mg/L mg/L mg/L mg/L mg/L Cl mg/L mg/L mg/L mg/L mg/L mg/L mg/L µhmos units MPN Cu ug/L Pb ug/L ug/L 1/18/2017 14:15 22nd & Aldrich Grab 0.763 0.132 0.386 6.56 2.90 0.084 5905 500 222 85 10376 98 42 19020 7.8 24 50 31 299 4/26/2017 8:27 22nd & Aldrich Composite 0.226 0.017 0.067 1.6 0.88 0.301 10.0 20 77 35 34 7 <5.00 55 6.9 6488 18 35 65 5/15/2017 14:10 22nd & Aldrich Grab ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 3654 ND ND ND 5/15/2017 14:11 22nd & Aldrich Composite 1.46 0.213 0.08 10.5 2.83 <0.030 4.4 40 334 144 116 49 12 134 6.5 ND 56 98 358 5/16/2017 9:32 22nd & Aldrich Composite 0.450 0.118 0.089 3.83 1.09 0.336 2.5 20 154 55 65 11 6 71 7.0 ND 33 68 129 5/17/2017 4:32 22nd & Aldrich Composite 0.288 0.081 0.078 3.02 1.19 0.464 <2.00 12 106 104 32 6 5 52 7.2 ND 15 33 58 5/17/2017 19:31 22nd & Aldrich Composite 0.298 0.073 0.047 2.17 0.462 0.171 <2.00 16 124 35 ND 4 5 46 7.0 ND 23 93 84 6/11/2017 10:44 22nd & Aldrich Composite 0.371 ND ND 2.16 ND ND <2.00 24 68 32 ND ND ND 63 6.3 ND 14 20 59 6/12/2017 17:35 22nd & Aldrich Composite 0.287 0.100 0.121 1.85 0.820 0.376 0.9 20 56 28 34 5 6 60 6.5 ND 16 24 65 7/19/2017 22:36 22nd & Aldrich Composite 0.344 ND ND ND ND 0.533 <2.00 32 124 48 ND ND ND 90 ND ND ND ND ND 7/25/2017 20:00 22nd & Aldrich Composite 0.271 0.085 0.053 2.39 0.885 0.368 <2.00 24 76 32 50 8 9 67 6.7 ND 23 36 74 8/3/2017 8:15 22nd & Aldrich Composite 0.318 0.108 0.167 2.85 0.516 0.037 <2.00 18 49 21 53 16 7 63 6.3 ND 28 43 99 8/3/2017 8:55 22nd & Aldrich Grab ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 9208 ND ND ND 8/10/2017 1:19 22nd & Aldrich Composite 0.152 0.047 0.054 1.48 0.550 0.193 <2.00 16 41 18 41 3 <5.00 45 6.8 ND 19 3 56 9/26/2017 6:43 22nd & Aldrich Composite 0.189 ND ND 0.898 ND <0.030 <2.00 32 21 12 ND ND ND 80 ND ND 13 10 38 1/18/2017 14:05 14th & Park Grab 0.412 0.069 0.190 4.09 1.51 0.725 5025 144 131 56 8579 38 34 16190 8.3 179 38 15 225 4/26/2017 8:33 14th & Park Composite 0.076 0.021 0.049 0.684 0.547 0.203 10.0 16 15 6 49 8 6 67 7.0 256 11 3 34 5/15/2017 13:50 14th & Park Grab ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 228 ND ND ND 5/15/2017 14:27 14th & Park Composite 0.523 0.080 0.039 5.25 1.97 0.348 18.7 28 124 56 120 29 11 159 6.6 ND 45 13 192 5/16/2017 9:27 14th & Park Composite 0.241 0.071 0.029 2.27 0.924 0.556 4.9 16 94 28 59 9 6 69 7.3 ND 23 17 113 5/17/2017 4:17 14th & Park Composite 0.315 0.047 0.070 2.21 1.07 0.373 <2.00 20 185 32 50 5 <5.00 66 8.4 ND 22 10 42 5/17/2017 21:42 14th & Park Composite 0.159 0.028 0.023 1.22 0.428 0.221 2.5 12 63 18 ND 3 5 45 7.1 ND 20 12 56 6/11/2017 10:25 14th & Park Composite 0.214 ND ND 1.45 ND ND 2.28 16 39 16 ND ND ND 55 6.3 ND 17 4 34 6/12/2017 17:13 14th & Park Composite 0.150 0.033 0.063 1.36 0.650 0.610 5.0 20 28 16 41 7 6 78 6.6 ND 19 6 54 7/19/2017 22:40 14th & Park Composite 0.215 0.025 0.048 2.65 1.185 0.649 12.1 44 41 22 122 22 13 155 6.9 ND 29 8 107 7/26/2017 4:56 14th & Park Composite 0.133 0.048 0.033 0.975 0.585 0.350 <2.00 16 39 14 27 5 <5.00 46 6.9 ND 14 7 40 8/3/2017 8:26 14th & Park Composite 0.263 0.071 0.164 2.04 0.666 0.365 4.1 44 80 30 61 17 7 75 6.6 ND 25 14 145 8/3/2017 8:40 14th & Park Grab ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 1515 ND ND ND 8/10/2017 1:20 14th & Park Composite 0.106 0.022 0.036 0.725 0.630 0.340 <2.00 14 35 14 43 <1.00 <5.00 47 6.9 ND 14 6 55 8/16/2017 7:32 14th & Park Composite 0.075 0.029 0.029 <0.500 <0.250 0.172 <2.00 10 25 9 22 <1.00 <5.00 32 6.7 ND 11 5 32 8/16/2017 21:22 14th & Park Composite 0.068 0.021 0.030 <0.500 <0.250 0.132 <2.00 8 23 8 9 <1.00 <5.00 29 6.7 ND 9 6 28 9/26/2017 4:33 14th & Park Composite 0.066 ND ND ND ND 0.106 ND ND 24 13 ND ND ND ND ND ND ND ND ND 10/21/2017 9:37 14th & Park Composite 0.279 ND ND 1.70 ND 0.105 2.97 24 75 38 ND ND ND 76 ND ND 26 15 100
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Table 22-8. 2017 NDPES sampled event data by site. (Continued) ND=no data Sample TP TDP OrthoP TKN NH3 NO3NO2 Hardness TSS VSS TDS cBOD Sulfate Sp.Cond. pH std E. Coli Zn Date Sampled Time Site Location Type mg/L mg/L mg/L mg/L mg/L mg/L Cl mg/L mg/L mg/L mg/L mg/L mg/L mg/L µhmos units MPN Cu ug/L Pb ug/L ug/L 2/14/2017 13:25 Pershing Grab 1.07 0.444 0.798 5.18 1.52 0.079 14.5 80 33 27 118 46 7 218 7.3 201 8 1 <20.0 4/26/2017 7:36 Pershing Composite 0.094 0.034 0.046 0.821 0.674 0.376 10.0 16 27 10 20 <1.00 <5.00 28 7.2 ND 19 2 <20.0 5/15/2017 14:21 Pershing Composite 0.353 0.078 0.005 3.81 2.09 0.630 2.48 40 30 20 <5.00 ND 6 86 6.5 ND 24 2 35 5/16/2017 8:37 Pershing Composite 0.162 0.031 0.008 1.75 0.992 0.373 <2.00 16 27 11 11 7 <5.00 44 6.9 ND 13 2 <20.0 5/17/2017 4:23 Pershing Composite 0.152 0.033 0.038 1.43 0.845 0.348 <2.00 20 45 11 19 3 6 57 7.4 ND 14 2 <20.0 5/17/2017 16:37 Pershing Composite 0.267 0.092 0.091 1.32 0.462 0.196 <2.00 24 46 14 3 7 62 7.3 ND 12 4 <20.0 7/18/2017 0:06 Pershing Composite 0.321 0.048 0.055 1.69 0.885 <0.030 <2.00 28 49 28 46 7 5 75 6.7 ND 14 2 <20.0 7/19/2017 23:09 Pershing Composite 0.233 0.119 0.151 0.823 0.585 0.360 <2.00 32 28 10 38 4 7 74 7.3 ND 13 1 <20.0 7/25/2017 18:44 Pershing Composite 0.224 0.126 0.141 1.057 0.735 0.391 <2.00 24 46 16 18 5 <5.00 67 7.3 ND 13 2 <20.0 8/3/2017 8:29 Pershing Composite 0.377 0.222 0.235 2.73 0.470 <0.030 6.9 38 30 16 105 ND 6 109 ND ND ND ND ND 8/5/2017 18:13 Pershing Composite 0.255 ND ND 1.72 0.411 ND <2.00 32 28 14 ND ND 84 ND ND 14 2 31 8/10/2017 1:03 Pershing Composite 0.151 0.089 0.106 <0.500 0.426 0.166 <2.00 18 34 16 9 <1.00 <5.00 46 6.6 ND 7 2 <20.0 8/16/2017 7:15 Pershing Composite 0.168 0.114 0.125 <0.500 0.470 0.137 <2.00 18 16 6 15 <1.00 <5.00 48 6.4 ND 10 1 <20.0 8/16/2017 21:18 Pershing Composite 0.138 0.058 0.079 0.501 <0.250 0.110 <2.00 16 40 12 22 <1.00 <5.00 34 6.7 ND 9 4 <20.0 10/21/2017 10:18 Pershing Composite 0.176 ND ND 0.898 ND 0.140 <2.00 16 50 19 ND ND ND 45 ND ND 16 3 24 1/17/2017 14:45 61st & Lyndale Grab 0.491 0.042 0.106 2.83 0.849 1.19 6785 232 297 95 11836 28 46 >19990 9.9 12 54 16 264 1/18/2017 13:45 61st & Lyndale Grab 0.499 0.040 0.192 9.69 1.44 1.05 4422 200 384 111 7639 33 37 >19990 10.3 7 53 17 280 4/26/2017 11:35 61st & Lyndale Grab ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 189 ND ND ND 5/15/2017 13:30 61st & Lyndale Grab ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 47.1 ND ND ND 5/15/2017 17:55 61st & Lyndale Composite 0.431 0.051 0.030 3.35 1.12 0.531 43.8 56 217 68 157 19 11 247 7.2 ND 37 14 180 5/16/2017 8:43 61st & Lyndale Composite 0.426 0.059 0.018 2.94 0.890 0.665 43.8 44 207 61 148 13 9 240 7.9 ND 33 14 174 6/12/2017 20:40 61st & Lyndale Composite 0.185 0.020 0.088 1.20 0.422 0.427 45.6 40 65 20 135 7 9 209 6.8 ND 19 5 80 7/18/2017 5:40 61st & Lyndale Composite 0.171 0.024 0.045 1.00 0.666 0.378 9.3 28 49 15 49 7 7 101 6.8 ND 13 3 30 8/3/2017 8:15 61st & Lyndale Grab ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 2613 ND ND ND 8/10/2017 7:55 61st & Lyndale Composite 0.120 0.026 0.054 <0.500 0.450 0.439 9.33 26 42 13 57 3 5 97 6.9 ND 15 3 45 8/16/2017 3:46 61st & Lyndale Composite 0.153 0.044 0.068 <0.500 <0.250 0.076 10.3 20 89 24 37 <1.00 <5.00 92 6.9 ND 15 4 51 8/25/2017 8:57 61st & Lyndale Composite 0.251 0.116 0.182 <0.500 0.426 0.401 4.7 46 46 15 121 5 11 212 6.9 ND 12 3 56 9/18/2017 16:11 61st & Lyndale Composite 0.237 0.039 0.030 1.58 0.356 0.145 22.3 40 85 31 104 4 10 175 6.2 ND 21 7 107 9/20/2017 7:11 61st & Lyndale Composite 0.120 0.018 0.029 0.697 0.489 0.419 14.4 20 45 11 42 2 6 110 6.6 ND 12 3 42 9/25/2017 7:55 61st & Lyndale Composite 0.143 0.028 0.066 1.17 0.478 0.503 22.8 36 34 15 94 14 10 159 6.6 ND 17 3 54 9/26/2017 8:25 61st & Lyndale Composite 0.091 ND ND 0.756 ND 0.673 18.2 38 16 8 ND ND ND 143 ND ND 12 1 34 10/22/2017 0:15 61st & Lyndale Composite 0.331 ND ND 1.68 ND 0.064 24.3 68 67 27 ND ND ND 222 ND ND 22 7 71
2017 Water Resources Report – Minneapolis Park and Recreation Board Page 22-13
Median Comparison
Table 22-9 shows a comparison of MPRB and Nationwide Urban Runoff Program (NURP) median residential, mixed use, and composite land use stormwater values. The MPRB data are split into 2017 and 2001-2016 data for comparison.
In 2017, the three MPRB land use categories were significantly lower or had similar values in the median concentrations of almost all chemical parameters when compared to the NURP data. The exception is TKN in all land uses. It is unknown why some of the MPRB TKN median data are higher than the NURP data. A possible explanation is that there is more decaying vegetative material (e.g. leaf litter) in the Minneapolis watersheds than in the NURP watersheds that were studied from 1979 to 1983.
When the NURP study data were collected, lead (Pb) was widely used in gasoline (from the 1920s to 1990s). The significant lead reduction in the environment is clearly seen in the MPRB data sets since it was collected after lead in gas was banned in 1996.
It is important to note that the MPRB sites monitored in 2001-2004 were in different watersheds and have similar but not identical land uses to those monitored in 2005-2017. It is not believed this effected comparison results.
Table 22-9. Typical median stormwater concentrations from MPRB and NURP data.
Land Use Residential Residential Residential Mixed Mixed Mixed Composite Composite Composite Location MPRB1 MPRB2 NURP MPRB3 MPRB4 NURP MPRB5 MPRB6 NURP 2001– Year(s) 2017 2001–2016 1980's 2017 1980's 2017 2001–2016 1980's 2016 TP (mg/L) 0.298 0.387 0.383 0.187 0.222 0.263 0.235 0.321 0.330 TKN (mg/L) 2.28 2.42 1.9 1.70 1.55 1.29 1.70 2.03 1.5
NO3NO2 (mg/L) 0.319 0.358 0.736 0.348 0.424 0.558 0.360 0.424 0.68 cBOD (mg/L) 7 11 10 8 10 8 7 9 9 TSS (mg/L) 77 82 101 40 56 67 47 80 100 Cu (µg/L) 21 18 33 20 17 27 17 18 30 Pb (µg/L) 34 30 144 8 11 114 6 12 140 Zn (µg/L) 69 77 135 55 80 154 59 77 160 1 Site 6 data. 2 Sites 1 and 2 data, (Site 6, 2005-2017). 3 Site 7 data. 4 Sites 5 and 5a data, (Site 7, 2005-2017). 5 Sites 6 – 9 data. 6 Sites 1 – 5a data, (Site 6 – 9, 2005-2017).
Geometric Mean Comparison
Table 22-10 lists statistical calculations for all measured parameters for each individual land use site, and then all land use sites combined. Stormwater data have a significant amount of variance and outliers in the data set. The geometric mean calculation is the best statistical tool to understand data that have outliers and extreme outliers. 2017 Water Resources Report – Minneapolis Park and Recreation Board Page 22-14
Site 6 (22nd and Aldrich) is an older residential watershed with a dense tree canopy. It had the highest geometric means for: TP, Ortho-P, TKN, NH3, TSS, VSS, cBOD, E. coli, Cu, Pb, and Zn. The cause of the higher TP values may be either pet waste or dense leaf canopy in the watershed adding to the organic load. The higher Pb is likely the result of vehicular wear inputs (e.g. brake dust, tire weights) or legacy exterior lead paint. The geometric mean concentration of Pb has been persistently high at this site compared to the other monitored sites and is possibly a remnant of lead-based paints shedding from the older houses and the soils. The low NO2NO3 values are likely due to plant uptake in the watershed.
Site 7 (14th and Park) is a dense mixed-use watershed. There were none of the highest geometric mean concentrations found at this site. Site 7 (14th and Park) had the lowest geometric mean for TP, Ortho-P, and Hardness. It is unknown why these parameters were low in this watershed. This is likely the result of the hard surface landscape, with minimal vegetation, in this mixed-use watershed.
Site 8 (Pershing) is a Minneapolis park. It had the highest geometric means for TDP. The TDP is likely coming from the soils and vegetation decomposing in the park. Site 8 (Pershing) had the lowest geometric means for most parameters: Cl, TSS, VSS, TDS, cBOD, Sulfate, Sp. Cond., Cu, Pb, and Zn. This is likely due to the park’s less developed vegetated parkland grass covered watershed. The E. coli sample was collected during snowmelt and not used for analysis since it was the only sample collected at the site.
Site 9 (61st and Lyndale) is a commercial/industrial watershed. It had the highest geometric mean for st seven parameters: NO2NO3, Cl, Hardness, TDS, Sulfate, Sp. Cond., and pH. Site 9 (61 and Lyndale) had the lowest geometric mean values for four parameters: TDP, TKN, NH3, and E. coli. This watershed is a light industrial site (cement factory, natural gas facility, City maintenance facility, etc.) and it is expected that many of the parameters would be higher than other watersheds due to extensive industrial activities.
2017 Water Resources Report – Minneapolis Park and Recreation Board Page 22-15
Table 22-10. 2017 statistics on chemical parameter by site and aggregated. All = all 4 sites, STDEV = standard deviation, COV = coefficient of variation. Blue boxes are the highest geometric mean chemical parameter. Orange boxes are the lowest geometric mean chemical parameter. NA = data not available.
TP TDP Ortho-P TKN NH3 NO3NO2 Cl Hardness TSS VSS TDS cBOD Sulfate Sp.Cond. pH std E. coli Cu Pb Zn Site ID Statistical Function mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L µhmos units MPN/100mL ug/L ug/L ug/L 6, 22nd Aldrich MEAN (geometric) 0.342 0.082 0.091 2.61 0.989 0.144 3 28 87 39 88 10 6.68 102 6.8 1510 23 29 89 6, 22nd Aldrich MEAN (arithmetic) 0.417 0.097 0.114 3.28 1.213 0.241 456 60 112 50 1200 21 9.70 1527 6.8 4843 26 41 115 6, 22nd Aldrich MAX 1.46 0.213 0.386 10.5 2.90 0.533 5905 500 334 144 10376 98 42.2 19020 7.8 9208 56 98 358 6, 22nd Aldrich MIN 0.152 0.017 0.047 0.898 0.462 0.015 1 12 21 12 32 3 2.50 45 6.3 24 13 3 38 6, 22nd Aldrich MEDIAN 0.298 0.093 0.079 2.28 0.883 0.247 1 20 77 35 50 7 5.99 63 6.8 5071 21 34 69 6, 22nd Aldrich STDEV 0.348 0.053 0.102 2.71 0.904 0.180 1637 133 86 39 3441 30 11.7 5256 0.4 3933 14 30 103 6, 22nd Aldrich NUMBER 13 10 10 12 10 12 13 13 13 13 9 10 10 13 11 4 12 12 12 6, 22nd Aldrich COV 0.835 0.542 0.895 0.826 0.745 0.748 3.59 2.23 0.768 0.777 2.87 1.47 1.21 3.44 0.062 0.812 0.546 0.741 0.895 7, 14th Park MEAN (geometric) 0.170 0.038 0.049 1.33 0.621 0.293 5 21 50 19 68 6 5.43 92 7.0 355 20 8 66 7, 14th Park MEAN (arithmetic) 0.206 0.043 0.062 1.81 0.801 0.350 340 29 64 23 765 11 7.69 1146 7.0 545 22 9 84 7, 14th Park MAX 0.523 0.080 0.190 5.25 1.97 0.725 5025 144 185 56 8579 38 33.5 16190 8.4 1515 45 17 225 7, 14th Park MIN 0.066 0.021 0.023 0.250 0.125 0.105 1 8 15 6 9 1 2.50 29 6.3 179 9 3 28 7, 14th Park MEDIAN 0.187 0.033 0.039 1.45 0.650 0.348 3 16 40 17 49 7 5.90 67 6.9 242 20 8 55 7, 14th Park STDEV 0.131 0.022 0.053 1.39 0.527 0.203 1296 34 48 15 2461 12 8.43 4162 0.6 648 10 5 62 7, 14th Park NUMBER 16 13 13 15 13 15 15 15 16 16 12 13 13 15 14 4 15 15 15 7, 14th Park COV 0.637 0.510 0.862 0.766 0.658 0.580 3.82 1.17 0.758 0.660 3.22 1.06 1.10 3.63 0.088 1.19 0.468 0.496 0.741 8, Pershing MEAN (geometric) 0.228 0.084 0.072 1.17 0.629 0.157 2 25 34 14 22 3 4.13 63 6.9 201 12 2 13 8, Pershing MEAN (arithmetic) 0.276 0.114 0.144 1.62 0.763 0.238 3 28 35 15 35 7 4.59 72 7.0 201 13 2 14 8, Pershing MAX 1.07 0.444 0.798 5.18 2.09 0.630 15 80 50 28 118 46 7.42 218 7.4 201 24 4 35 8, Pershing MIN 0.094 0.031 0.005 0.250 0.125 0.015 1 16 16 6 3 1 2.50 28 6.4 201 7 1 10 8, Pershing MEDIAN 0.224 0.089 0.091 1.32 0.630 0.181 1 24 33 14 20 3 5.41 62 7.0 201 13 2 10 8, Pershing STDEV 0.234 0.112 0.206 1.36 0.508 0.177 4 17 10 6 38 13 2.09 46 0.4 NA 4 1 9 8, Pershing NUMBER 15 13 13 15 14 14 15 15 15 15 12 11 13 15 12 1 14 14 14 8, Pershing COV 0.847 0.978 1.43 0.843 0.665 0.744 1.39 0.595 0.289 0.407 1.07 1.81 0.456 0.642 0.052 NA 0.337 0.430 0.618 9, 61st Lyndale MEAN (geometric) 0.224 0.037 0.059 1.16 0.545 0.379 41 47 79 26 183 7 9.89 157 7.3 72 21 5 80 9, 61st Lyndale MEAN (arithmetic) 0.261 0.042 0.076 1.97 0.643 0.498 820 64 117 37 1702 11 13.6 167 7.4 574 24 7 105 9, 61st Lyndale MAX 0.499 0.116 0.192 9.69 1.44 1.19 6785 232 384 111 11836 33 45.7 247 10.3 2613 54 17 280 9, 61st Lyndale MIN 0.091 0.018 0.018 0.250 0.125 0.064 5 20 16 8 37 1 2.50 92 6.2 7 12 1 30 9, 61st Lyndale MEDIAN 0.211 0.040 0.060 1.19 0.484 0.433 23 40 66 22 113 7 9.61 167 6.9 47 18 4 64 9, 61st Lyndale STDEV 0.147 0.026 0.058 2.44 0.369 0.326 2079 66 113 34 3859 10 13.4 58 1.3 1142 15 6 85 9, 61st Lyndale NUMBER 14 12 12 14 12 14 14 14 14 14 12 12 12 12 12 5 14 14 14 9, 61st Lyndale COV 0.562 0.626 0.768 1.24 0.575 0.655 2.54 1.03 0.965 0.912 2.27 0.925 0.981 0.349 0.176 1.99 0.611 0.787 0.812 All MEAN (geometric) 0.229 0.055 0.065 1.44 0.664 0.228 5 28 57 22 69 6 6.11 95 7.0 292 18 7 49 All MEAN (arithmetic) 0.284 0.074 0.099 2.11 0.836 0.335 396 44 80 30 907 12 8.75 729 7.1 1759 21 14 78 All MAX 1.46 0.444 0.798 10.5 2.90 1.19 6785 500 384 144 11836 98 45.7 19020 10.3 9208 56 98 358 All MIN 0.066 0.017 0.005 0.250 0.125 0.015 1 8 15 6 3 1 2.50 28 6.2 7 7 1 10 All MEDIAN 0.235 0.050 0.065 1.59 0.666 0.348 2 24 47 20 49 6 5.92 74 6.9 215 17 6 54 All STDEV 0.233 0.071 0.125 2.06 0.604 0.249 1444 74 79 29 2792 18 9.94 3320 0.8 2859 12 21 81 All NUMBER 58 48 48 56 49 55 57 57 58 58 45 46 48 55 49 14 55 55 55 All COV 0.818 0.971 1.26 0.973 0.723 0.741 3.65 1.67 0.991 0.938 3.08 1.42 1.14 4.55 0.111 1.63 0.578 1.49 1.03
2017 Water Resources Report – Minneapolis Park and Recreation Board Page 22-16
Mean Comparison
The 2017 MPRB mean data are shown in Table 22-11 along with urban stormwater data from other studies. These studies include the Nationwide Urban Runoff Program (NURP, USEPA 1996), Center for Watershed Protection (CWP, 2000), the Monroe study area by Bannerman et al. (1993), stormwater studies done by Minneapolis public works (1992), St. Paul (1994), and the MPRB (2001- 2016).
Data set from MPRB Sites 1–5a (2001–2004) and 6–9 (2005–2016) were partially similar to Sites 6– 9 in 2017. The MPRB 2017 mean TP, TDP, NO3NO2, NH3, TSS, and Pb were lower when compared to the 2001-2016 mean data. The 2017 mean increase in Cl and TDS are likely related to the timing of when snowmelt samples were taken. The 2007 mean Pb was significantly lower when compared to all other studies. The exact cause for this 2017 mean Pb decrease is welcome but unknown. Overall, the MPRB mean stormwater data are comparable to the five-other urban stormwater studies.
Table 22-11. Typical Mean urban stormwater concentrations. " -- " = not reported.
Bannerman et MPRB MPRB Parameter NURP CWP Mpls PW St. Paul al. 2001–2016 2017 TP (mg/L) 0.5 0.3 0.66 0.417 0.484 0.443 0.284 TDP (mg/L) -- -- 0.27 0.251 -- 0.144 0.074 TKN (mg/L) 2.3 ------2.46 2.73 2.38 NO3NO2 0.86 ------0.362 0.584 0.361 (mg/L) NH3 (mg/L) ------0.234 -- 0.584 0.361 230 Cl (mg/L) ------284 682 (winter) BOD (mg/L) 12 -- -- 14.9 25 16 15 TDS (mg/L) ------73.3 78 546 928 TSS (mg/L) 239 80 262 77.6 129 121 80 Cu (µg/L) 50 10 16 26.7 30 23.6 20.9 Pb (µg/L) 240 18 32 75.5 233 22.5 13.8 Zn (µg/L) 350 140 204 148 194 115 95
Flow-weighted Mean Comparison
The flow-weighted comparison removes the variability of dilution and is a more accurate comparison. Flow-weighted mean concentrations for Cl and TDS were difficult to estimate using FLUX32 due to large outliers from the snowmelt samples; therefore, these estimates should be used with caution. When samples were below the reporting limit, half of the reporting limit was used for calculations. The flow-weighted mean concentrations presented in Table 22-12 were calculated using FLUX32. Sample chemistry concentrations and associated daily average flows were used as inputs for these calculations. The data were run unstratified and stratified by flow or month to achieve the lowest coefficient of variation, producing the most accurate and precise results. The methods (2 or 6) event mean concentration with the lowest coefficient of variation was almost always chosen as the final
2017 Water Resources Report – Minneapolis Park and Recreation Board Page 22-17
concentration value. If a statistical anomaly occurred in Flux32, where the lowest coefficient of variation was an obvious and extreme outlier, then the next value was chosen.
Table 22-12. 2017 flow-weighted mean concentrations and related statistics. Flow-weighted mean concentrations for Cl and TDS were difficult to estimate using FLUX32 due to large outliers from the two snowmelt samples; these estimates should be used with caution. STANDEV= standard deviation. Blue highlighted data are the highest and orange highlighted data are the lowest.
TP TDP Ortho-P TKN NH3 NO3NO2 Cl* Hardness TSS VSS TDS* cBOD Sulfate Cu Pb Zn Site (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
6, 22nd Aldrich 0.163 0.065 0.073 2.23 0.779 0.309 2 21 73 40 42 7 4.0 0.018 0.035 0.068
7, 14th Park 0.212 0.043 0.052 1.63 0.723 0.331 3 18 107 24 42 5 3.7 0.017 0.007 0.053
8a, Pershing 0.191 0.085 0.092 0.962 0.668 0.235 1 21 35 13 19 3 4.0 0.012 0.002 0.011
9, 61st Lyndale 0.255 0.046 0.067 0.940 0.471 0.502 22 34 115 35 92 8 8.0 0.022 0.005 0.097
MEAN 0.205 0.060 0.071 1.44 0.660 0.344 7 23 83 28 49 6 4.9 0.017 0.012 0.057
MEDIAN 0.202 0.056 0.070 1.30 0.696 0.320 2 21 90 30 42 6 4.0 0.018 0.006 0.061
STANDEV 0.039 0.020 0.017 0.616 0.134 0.113 10 7 37 12 31 2 2.1 0.004 0.015 0.036
Site 6 (22nd and Aldrich) has a multi-family residential watershed. Site 6 had the highest modeled concentrations of TKN, NH3, VSS, TDS (tied), cBOD, Sulfate, and Pb. Site 6 had the lowest modeled concentration of TP. It is hypothesized that this may be due to its location between two heavily traveled thoroughfares (Hennepin and Lyndale) where a mature dense leaf canopy may collect airborne material and deposit it following precipitation. The decaying leaf litter may be the cause of the increased nitrogen and cBOD. Site 7 (14th and Park) has a densely developed mixed use watershed. Site 7 had the highest TDS (tied) modeled parameter. Site 7 had the lowest modeled TDP, Ortho-P, and Sulfate. These are all likely due to the dense, highly developed, and low vegetation nature of the watershed. Site 8a (Pershing) has a parkland watershed. Site 8a had the highest TDP and Ortho-P modeled event mean concentrations. Site 8a had the lowest modeled NO3NO2, Cl, TSS, VSS, TDS, cBOD. This is likely due to the more natural vegetative state of the watershed and an absence of street runoff. Site 9 (61st and Lyndale) has a commercial/industrial watershed. Site 9 had the highest modeled concentration of TP, NO3NO2, Cl, Hardness, TSS, Cu, and Zn. Site 9 had the of the lowest modeled event mean concentrations of TKN and NH3. Industrial activities in this watershed likely explain the higher pollutant loads. Site 9 is located adjacent to a large cement aggregate mixing facility which may explain the higher TSS values. This site sometimes had a very small baseflow. Table 22-13 includes flow-weighted mean pollutant concentrations of data collected in the 1980s and reported by the U.S. Geological Survey (USGS) for various sites within the Twin Cities (as cited in MPCA, 2000). The Yates watershed was a stabilized residential area, the Iverson site was a residential watershed under development, and the Sandberg watershed was predominantly a light industrial land use area, as reported by the USGS. Site 6 (22nd and Aldrich) is more closely related to the Yates residential watershed land use characteristics and is shaded blue in the table. Site 7 (14th
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and Park) and Site 9 (61st and Lyndale) are more comparable to the Sandberg light industrial watershed land use characteristics and is shaded orange in the table. Table 22-13. 2017 flow-weighted mean stormwater pollutant concentrations (mg/L) and ranges as reported by the USGS (as cited in MPCA, 2000).
Iverson Site 6 Site 9 Pollutant Yates area area Sandburg Site 7 (22nd (61st (Range) (stabilized (developing area (light (14th Park) Aldrich) Lyndale) residential) residential) industrial) 133 73 740 337 107 115 TSS (2 – 758) (21 – 334) (17- 26,610) (7 – 4,388) (15 – 185) (15 – 384) 0.23 0.035 0.02 0.19 0.007 0.005 Pb (0.015 –1.8) (0.003 -0.098) (0.008-0.31) (0.003 –1.5) (0.003 – 0.017) (0.001 – 0.098) 0.198 0.068 0.235 0.185 0.053 0.097 Zn (0.02 – 2.2) (0.038 -0.358) (0.028-0.53) (0.02 –0.81) (0.028 – 0.225) (0.010 – 0.358) 3.6 2.23 1.2 2.5 1.63 0.940 TKN (0.6 – 28.6) (0.898 – 10.5) (1.0 – 29.2) (0.4 – 16.0) (0.250 – 5.25) (0.250 – 10.5) 0.63 0.163 0.62 0.63 0.212 0.255 TP (0.10 –3.85) (0.153 – 1.46) (0.2 – 13.1) (0.07 – 4.3) (0.066 – 0.523) (0.066 – 1.46)
When comparing the USGS flow-weighted mean concentrations to the MPRB sites in Table 22-13, Site 6 (22nd and Aldrich) was significantly lower than Yates for all parameters. The Iverson data are shown only for comparison purposes of a developing residential neighborhood. Compared to Sandberg, Sites 7 and 9 have lower flow-weighted mean concentrations for all parameters and are well within the ranges shown in Table 22-13. Site 7 (14th and Park) had significantly lower values than Sandberg for all parameters. Site 9 (61st and Lyndale) had roughly half (or lower) of the Sandberg values. The overall flow-weighted mean comparison of Table 22-13 to MPRB water quality values at sites 6, 7, and 9 shows that the Minneapolis sites were the same or roughly half of the values for the compared parameters. The Minneapolis mean Pb values are much lower than the Yates and Sandburg studies.
Table 22-14 shows the flow-weighted mean concentrations in 2017 compared to 2005 through 2016 flow-weighted mean concentrations. Many parameters have decreasing concentration for this time period: TP, TDP, TKN, NO2NO3, Hardness, TSS, TDS, Sulfate, Cu, Pb, and Zn.
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Table 22-14. MPRB flow-weighted mean concentration compared to previous years. Each year is the average flow-weighted mean concentration of all sites monitored that year. ND = data not collected. NA= data not analyzed for.
Parameter 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 TP (mg/L) 0.354 0.548 0.472 0.486 0.583 0.341 0.355 0.368 0.369 0.313 0.337 0.297 0.205 TDP (mg/L) 0.123 0.135 0.108 0.139 0.249 0.063 0.126 0.123 0.157 0.121 0.089 0.088 0.060 Ortho-P (mg/L) ND ND ND ND ND ND 0.179 0.097 0.194 0.129 0.109 0.093 0.071 TKN (mg/L) 3.48 3.54 4.43 3.22 3.61 1.53 1.74 2.00 2.34 2.40 1.68 1.72 1.44
NH3(mg/L) 1.74 1.64 0.970 0.966 1.64 0.666 0.922 0.719 0.747 1.00 0.262 0.430 0.660
NO3NO2 (mg/L) 0.448 0.638 0.496 0.582 0.755 0.414 0.498 0.397 0.402 0.937 0.396 0.290 0.344 Cl (mg/L) 18 91 412 139 803 60 213 14 72 205 229 12 7 Hardness (mg/L) NA ND ND ND ND NA 48.0 37 41 41 30 32 23 TSS (mg/L) 108 156 180 148 121 107 104 101 95 123 87 90 83 VSS (mg/L) ND ND ND ND ND ND 30 31 29 34 31 32 28 TDS (mg/L) 252 183 737 507 3323 124 693 97 301 359 59 62 49 cBOD (mg/L) 9 9 17 25 53 7 11 13 13 10 8 7 6 Sulfate (mg/L) ND ND ND ND ND ND 15 18 8 7 6 6 5 Cd (µg/L) 2.50 ND ND ND ND ND ND ND ND ND ND ND ND Cu (µg/L) 19 29 36 16 40 23 25 16 19 13 8 9 17 Pb (µg/L) 41 31 34 28 23 24 18 15 22 16 8 13 12 Zn (µg/L) 86 94 133 132 204 100 103 90 79 68 62 58 57 Note: Cadmium (Cd) was discontinued from monitoring in 2006 because Cd concentrations had typically been below detection for the Minneapolis/St. Paul area and it was not useful information. It should also be noted the detection limit for Cd has changed over time. In 2002 it was <0.500 µg/L; in 2003 it was <2.00 µg/L and in 2004 it was <5.00 µg/L. In 2011, ortho-P (or TDP), hardness (for metals toxicity calculations), and sulfate were added.
Chemical concentrations in stormwater are highly variable. Climatological factors such as precipitation amount and intensity, or physical factors like street sweeping type and frequency, BMP maintenance frequency can cause fluctuations in chemical concentrations. Table 22-14 illustrates the variability of stormwater from year to year. The variability from year to year is likely due to three causes. In 2005 two sites were different than monitored in subsequent years. The timing between street sweeping, BMP maintenance, and the storms sampled probably affect variability within the monitoring year and between years. Also, precipitation frequency, intensity, and duration also affect results.
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23. LOWRY SAND FILTER BACKGROUND
The Lowry Sand Filter (LSF) is a large underground BMP (Best Management Practice) used to treat stormwater, Figure 23-1. The tributary area is 120.5 acres and the majority land uses are residential (66%) and industrial/commercial (22%). Stormwater from the watershed in a 30 inch RCP pipe under Lowry Ave. and is diverted by a flow splitter weir to shunt water to the LSF 15 inch inlet RCP pipe, Figure 23-2. The structure has three chambers: a sedimentation chamber, a sand filtration chamber, and a discharge chamber. The purpose of this study is to measure the efficacy of the LSF at removing solids and large particle pollutants.
The LSF sedimentation chamber dimensions are 40 feet by 40 feet with a standing 3 foot water depth. The LSF sand filter chamber dimensions are 40 feet by 52 feet. The base of the sand filter chamber consists of five rows of perforated 6 inch PVC pipes to carry away filtered stormwater to the 15 inch outlet RCP to the Mississippi River. On top of the PVC pipes is a 10 inch layer of filter aggregate covered with filter fabric. On top of that is a bed of 22 to 25 inches of sand. The discharge chamber is 40 feet long and 6 feet wide. There is an internal bypass weir that maintains a 4 foot depth of stormwater to infiltrate through the sand filter bed. Once water depth exceeds 4 feet, it bypass’s over the internal weir directly to the outlet. The sand filter is designed to drain within 40 hours of rainfall. If the sand filter bed should become plugged there is a bypass valve and pipe assembly that can be opened to drain standing water from the sand bed. The maintenance manual states that cleaning and maintenance activity is to occur every 3 to 5 years. It was designed by SRF Engineering and constructed in 2012 with Hennepin County Public Works overseeing construction.
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Figure 23-1. Aerial photo of The Lowry Sand Filter with the flow-splitter weir, inlet, sand filter bypass weir, and outlet.
Figure 23-2. Downstream Photo of the flow splitter weir to the Lowry Sand Filter.
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Site Installation
Equipment needed to be installed at the flow-splitter weir, inlet, sand filter bypass weir, and outlet. In 2017, the sampling equipment could not be installed at the splitter weir, inlet, or sand filter bypass weir due to deep standing water in the LSF which backed up water through the inlet to the flow splitter weir. Equipment was installed at the outlet on 5/9/17 and was removed on 10/2/17. Eye bolts were installed to hang equipment at the inlet and the sand filter bypass weir on 6/27/17, but equipment could not be installed due to deep standing water in the LSF. No eye bolts or equipment were installed at the flow splitter weir due to pipe-full conditions upstream of the weir. The flow-splitter weir in the Lowry Avenue turn lane was extremely busy and required significant traffic control measures to safely open the manhole.
Monitoring equipment at the outlet site included an ISCO 2150 datalogger, 2105ci interface module cell phone modem, a low-profile AV probe, and a 3700 ISCO sampler. Equipment at the outlet was hung from eye-bolts below grade at the access manhole. The datalogger used the cell phone modem to upload data to a database server Monday through Friday. The datalogger could also be remotely called up and programmed to turn samplers on or off, and adjust the level, pacing, or triggers.
Sample Collection
The LSF was plugged, a full equipment set up could not be installed, therefore there was no sample collection in 2017. When the LSF is cleaned and functioning, the inlet, bypass, and outlet will be metered, and the samplers will be flow-paced and multiplexed.
RESULTS & DISCUSSION
Sample Collection
In 2017, there were no samples collected, therefore there are no chemistry data. The outlet was metered, and the stage and discharge are shown in Figure 23-3. Only the storm on May 17th, 2017 had a pipe full condition, all others were below 15 inches of flow in the outlet pipe.
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Figure 23-3. 2017 Lowry Sand Filter outlet stage and discharge for the period of record.
CONCLUSION
In conclusion, the Lowry Sand Filter is plugged. Equipment cannot be installed until it is cleaned and maintained. When the BMP is functioning, it will be monitored for its ability to filter and treat stormwater. The sand filter is currently scheduled to be cleaned in 2018.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 23-4 24. Winter Infiltration Basin
BACKGROUND
The Winter Infiltration Basin (WIB) Best Management Practice (BMP) was built to infiltrate and treat stormwater from the surrounding neighborhood, Figure 24-1. It was built in 2015 by Meyer Contracting Inc. The total drainage area the WIB treats is 31.32 acres. The west inlet drains 1.17 acres and the major land use in this drainage area is 51% industrial and 27% residential. The south inlet drains 30.15 acres and the major land use is 57% industrial and 20% residential in this drainage area. The south inlet has hydrodynamic separator to help remove solids prior to discharging into the WIB. If the outlet discharges under large or intense storms, the water goes to the Mississippi River.
Figure 24-1. Aerial photo of the Winter Infiltration Basin. It has two inlets and one outlet.
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Site Installation
In 2017, equipment at the west inlet and at the outlet was installed on 6/5/17 and equipment at the south inlet was installed on 6/6/17. The WIB west inlet is a 12 inch RCP pipe, the south inlet is a 24 inch RCP pipe, and the outlet is a 20 inch RCP pipe. All equipment was removed on 11/6/17.
Monitoring equipment at each site included: an ISCO 2150 datalogger, a 2105 interface module, a 2105ci or a 2103ci cell phone modem, an antenna, a low-profile AV probe, and a 3700 ISCO sampler. The AV probes were secured with a stainless steel plate or a stainless steel spring ring. All sites required secure above ground doghouse monitoring boxes and flexible conduit to protect the AV- cable and sampler tubing.
Each datalogger used a cell phone modem to remotely upload data to a Flowlink database server Monday through Friday. All dataloggers could also be remotely called up and programmed to turn samplers on or off, adjust the level, pacing, or triggers.
The samplers were flow-paced and equipped with 24 one-liter bottles, 3/8” ID (inner diameter) vinyl tubing, and an intake strainer. The sampler was programmed to multiplex, taking four flow-paced samples per bottle, allowing for 96 flow-paced samples per storm.
Sample Collection
With all new sites sample collection parameters need to be adjusted from initial assumptions. The west inlet was initially set to trigger at 0.8 inches and initially paced at 10 cubic feet, but the pacing was changed on 6/23/17 to 25 cubic feet. The south inlet was initially set without a trigger and initially paced at 150 cubic feet, but the pacing was changed on 10/16/17 to 300 cubic feet. The outlet was set without a trigger and paced at 100 cubic feet.
RESULTS & DISCUSSION
Sample Collection
In 2017, twenty events were collected at the west inlet, nine events were collected at the south inlet, and two events were collected at the outlet. The sample bottle containing the composite outlet event of 8/26/17 was cracked and the event sample was lost, Table 24-1.
The south inlet delivered most of the water to the WIB. It had a hydrodynamic separator that was either undersized or in need of maintenance, as large amounts of debris were caught in the south inlet trash rack. The debris needed to be cleaned several times to prevent water from backing up the pipe.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 24-2 Table 24-1. The 2017 precipitation events captured at Winter Infiltration Basin. The rain gauge was located at the MPRB SSSC at 38th and Bryant Ave. S. A precipitation event was defined as a storm greater than 0.10 inches and separated by eight hours or more from other precipitation. Full = all chemical parameters. Partial = some chemical parameters were not run due to low volume or expired holding times.
Hours Winter Winter since Basin Basin Winter Start End Rain Duration Intensity last south west Basin Start Date Time End Date Time (inches) (hours) (in/hr.) Rain. inlet inlet outlet
6/22/2017 5:45 6/22/2017 15:30 0.43 9.75 0.04 47 - Full - 6/28/2017 3:00 6/28/2017 9:15 0.61 6.25 0.10 131 Partial Full - 6/30/2017 15:00 7/1/2017 0:15 0.44 9.25 0.05 54 Partial - - 7/17/2017 21:30 7/18/2017 18:30 1.11 21.00 0.05 405 - Full - 7/19/2017 14:45 7/19/2017 21:45 0.27 7.00 0.04 20 Partial - - 7/25/2017 17:00 7/26/2017 7:15 1.25 14.25 0.09 139 Partial - - 8/9/2017 10:45 8/10/2017 16:15 1.10 29.50 0.04 54 - Full - 8/16/2017 2:15 8/16/2017 6:15 0.52 4.00 0.13 50 - Full - 8/16/2017 18:30 8/17/2017 5:15 1.44 10.75 0.13 12 - Full - Sample 8/25/2017 21:30 8/26/2017 15:15 1.48 17.75 0.08 16 - Full Lost 9/20/2017 1:30 9/20/2017 2:00 0.34 0.50 0.68 35 - Full - 9/25/2017 1:45 9/25/2017 9:30 0.19 7.75 0.02 120 - Partial - 10/1/2017 0:15 10/3/2017 9:30 3.32 57.25 0.06 115 Partial Full Partial 10/6/2017 13:15 10/7/2017 12:00 0.46 22.75 0.02 76 Partial Partial - 10/14/2017 13:30 10/15/2017 3:00 0.43 13.50 0.03 170 Partial Partial - 10/21/2017 6:15 10/21/2017 20:15 0.43 14.00 0.03 147 Partial Partial -
The two WIB inlets stage and discharge can be seen in Figure 24-2 and Figure 24-3. The WIB outlet stage and discharge can be seen in Figure 24-4. The outlet figure shows that the WIB infiltrates most storms. Only large storms greater than 1.44 inches result in the WIB discharging any stormwater.
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Figure 24-2. The 2017 winter west inlet stage and discharge.
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Figure 24-3. The 2017 winter south inlet stage and discharge.
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Figure 24-4. The 2017 winter outlet stage and discharge.
Storm Event Data and Statistics
Table 25-2 shows the 2017 Winter Infiltration Basin chemistry data. Some of the events collected were analyzed for limited parameters because of low volume or expired holding times. The south inlet experienced significant software issues in July and August and was unable to collect flow-paced hydrograph samples. New equipment installed was installed 9/29/18 and the south inlet began collecting flow-paced samples. Two outlet storms were collected, and both were of very low volume.
The June sulfate failed the MPRB blind monthly performance standard and the effected sulfate data in Table 24-2 are marked in bold. It was deemed the data can be used with caution, noting that performance standards were outside the 80-120% recovery standards, Section 29, Quality Assurance Assessment Report.
Table 24-3 shows the 2017 statistics from the Winter Infiltration Basin inlets and outlet. When statistical analysis was performed on the data sets and values below the reporting limit were present, half of the reporting limit was used in the calculations.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 24-6 The geometric means of inlets vs outlet cannot be compared since the outlet only had one sample. In 2017, the outlet produced only five events, one was captured. The one outlet event that was able to be successfully captured was a very small aliquot and only limited parameters were run.
The south inlet had more pollutants than the west inlet. The majority of the stormwater comes from the south inlet.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 24-7 Table 24-2. 2017 Winter Infiltration Basin water chemistry events data. ND = data not available due to expired holding time or low volume. Data that are bold had a blind performance standard failure for that month, for that parameter.
Sample TP TDP OrthoP TKN NH3 NO3NO2 Hardness TSS VSS TDS cBOD Sulfate Sp.Cond. pH std Cu Pb Zn Date Sampled Time Site Location Type mg/L mg/L mg/L mg/L mg/L mg/L Cl mg/L mg/L mg/L mg/L mg/L mg/L mg/L µhmos units ug/L ug/L ug/L 6/28/2017 9:30 Winter Basin In S Composite 0.183 0.043 ND ND ND 0.442 ND 24 48 17 ND ND 5 ND 7.4 ND ND ND 7/17/2017 22:15 Winter Basin In S Composite 0.465 ND ND ND ND 0.040 NDND 113 40 219 ND ND 332 ND ND ND ND 9/20/2017 3:19 Winter Basin In S Composite 0.340 ND ND ND ND 0.412 NDND 234 61 ND ND ND ND ND ND ND ND 9/25/2017 3:19 Winter Basin In S Composite 0.344 ND ND ND ND 0.464 NDND 254 73 ND ND ND ND ND ND ND ND 10/1/2017 15:39 Winter Basin In S Composite 1.14 ND ND 1.27 ND 0.439 6.3 28 25 10 ND ND ND 94 ND 18 3 113 10/2/2017 2:29 Winter Basin In S Composite 1.22 0.758 0.900 0.874 <0.250 0.244 9.1 22 140 39 45 <1.006 92 6.9 45 13 256 10/6/2017 17:18 Winter Basin In S Composite 0.195 ND ND 0.981 ND 0.324 2.9 22 61 19 ND ND ND 67 ND 25 7 142 10/14/2017 20:02 Winter Basin In S Composite 0.248 ND ND 1.04 ND 0.270 4.9 28 116 35 ND ND ND 79 ND 38 12 241 10/21/2017 21:24 Winter Basin In S Composite 0.397 ND ND 1.76 ND 0.334 3.4 36 168 51 ND ND ND 106 ND 37 13 306 6/22/2017 11:36 Winter Basin In W Composite 0.103 0.03 0.043 1.33 0.824 0.423 5.0 20 20 10 53 7 8 71 7.2 20 2 69 6/28/2017 7:29 Winter Basin In W Composite 0.096 0.046 0.034 0.590 0.353 0.193 2.2 16 15 8 30 5 5 42 7.3 12 2 51 7/17/2017 23:30 Winter Basin In W Composite 0.153 0.033 0.041 1.11 0.654 0.418 2.3 16 20 11 27 57 51 6.7 17 2 76 8/10/2017 1:19 Winter Basin In W Composite 0.088 0.022 0.037 0.690 0.626 0.280 <2.00 12 22 12 28 3 <5.00 44 6.8 19 22 47 8/16/2017 7:59 Winter Basin In W Composite 0.063 0.016 0.024 <0.500 0.265 0.201 2.4 10 14 7 20 3 <5.00 36 6.6 16 1 38 8/16/2017 23:30 Winter Basin In W Composite 0.036 0.015 0.024 <0.500 <0.250 0.208 <2.006 8 4 10 <1.00 <5.00 27 6.7 91 21 8/26/2017 4:23 Winter Basin In W Composite 0.041 ND ND <0.500 ND 0.273 <2.008 5 3 ND ND ND 31 ND 81 23 9/20/2017 3:14 Winter Basin In W Composite 0.162 0.031 0.028 1.25 0.678 0.312 <2.00 10 64 22 23 49 56 6.4 18 4 104 9/25/2017 3:16 Winter Basin In W Composite 0.201 ND ND 1.50 ND 0.697 3.8 20 68 27 ND ND ND 76 ND 31 6 151 10/2/2017 2:20 Winter Basin In W Composite 0.067 ND ND 0.544 ND 0.184 <2.00 12 22 11 ND ND ND 32 ND 11 2 45 10/3/2017 0:07 Winter Basin In W Composite 0.067 0.012 0.024 <0.500 <0.250 0.194 <2.00 10 25 9 10 <1.00 <5.00 35 6.7 12 2 51 10/6/2017 16:59 Winter Basin In W Composite ND ND ND ND ND ND NDND ND ND ND ND ND ND ND 18 2 36 10/14/2017 19:38 Winter Basin In W Composite 0.089 ND ND 0.331 ND 0.190 <2.008 32 14 ND ND ND 29 ND 15 3 66 10/21/2017 7:26 Winter Basin In W Composite 0.185 ND ND 1.28 ND 0.752 2.5 20 43 23 ND ND ND 73 ND 21 3 115 8/26/2017 2:31 Winter Outlet Composite ND ND ND ND ND ND NDND ND ND ND ND ND ND ND ND ND ND 10/2/2017 23:47 Winter Outlet Composite 0.210 ND ND ND ND <0.030 NDND 77 26 ND ND ND ND ND ND ND ND
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 24-8 Table 24-3. 2017 Winter Infiltration Basin data showing statistics for the inlets and outlet. COV=Coefficient of Variation. ND=no data. The outlet only had one sample, so statistics were not able to be calculated. All data below the reporting limit were transformed into half the reporting limit for statistical calculations (e.g. Cl <2 becomes 1).
TP TDP OrthoP TKN NH3 NO3NO2 Cl Hardness TSS VSS TDS cBOD Sulfate Sp.Cond. pH std Cu Pb Zn Site ID Statistical Function mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L µhmos units ug/L ug/L ug/L Winter Basin In S MEAN (geometric) 0.400 0.181 0.900 1.15 ND 0.280 4.9 26.3 103 32 100 ND 5.5 108 7.1 30.9 8.0 198 Winter Basin In S MEAN (arithmetic) 0.503 0.401 0.900 1.18 ND 0.330 5.3 26.7 129 38 132 ND 5.5 128 7.1 32.5 9.4 212 Winter Basin In S MAX 1.22 0.758 0.900 1.76 ND 0.464 9.1 36.0 254 73 219 ND 5.8 332 7.4 45.0 12.9 306 Winter Basin In S MIN 0.183 0.043 0.900 0.874 ND 0.040 2.9 22.0 25 1045 ND 5.367 6.9 18.0 2.5 113 Winter Basin In S MEDIAN 0.344 0.401 0.900 1.04 ND 0.334 4.9 26.0 116 39 132 ND 5.593 7.1 36.5 11.8 241 Winter Basin In S STDEV 0.394 0.506 ND 0.353 ND 0.134 2.5 5.3 80 21 123 ND 0.4 101 0.4 10.7 4.5 81.1 Winter Basin In S NUMBER 921509569920262555 Winter Basin In S COV 0.783 1.26 ND 0.298 ND 0.407 0.5 0.2 111 ND 0.1 1 0.1 0.3 0.5 0.4 Winter Basin In W MEAN (geometric) 0.091 0.035 0.045 1.02 0.527 0.280 3.8 15.8 41 1730 4 6.460 6.9 18.6 3.4 79.4 Winter Basin In W MEAN (arithmetic) 0.104 0.101 0.128 1.08 0.567 0.318 4.2 17.6 72 2347 4 6.675 6.9 21.0 5.7 108 Winter Basin In W MAX 0.201 0.758 0.900 1.76 0.824 0.697 9.1 36.0 254 73 219 7 8.7 332 7.4 45 21.8 306 Winter Basin In W MIN 0.036 0.012 0.024 0.544 0.265 0.040 2.2 6.0 53 10 3 4.927 6.4 8.1 0.66 20.7 Winter Basin In W MEDIAN 0.089 0.031 0.034 1.08 0.640 0.296 3.6 16.0 37 1528 4 6.356 6.8 18.2 2.3 72.3 Winter Basin In W STDEV 0.054 0.231 0.289 0.369 0.213 0.143 2.2 8.3 75 2062 2 1.571 0.3 11.0 6.1 88.8 Winter Basin In W NUMBER 13 10 9 12 6 20 1017 20 2010 66 17 10 16 1616 Winter Basin In W COV 0.522 2.30 2.26 0.343 0.376 0.450 0.5 0.5 1110 0.2 1 0.0 0.5 1.1 0.8 Winter Outlet MEAN (geometric) 0.210 ND ND ND ND ND ND ND 77 26 ND ND ND ND ND ND ND ND Winter Outlet MEAN (arithmetic) 0.210 ND ND ND ND ND ND ND 77 26 ND ND ND ND ND ND ND ND Winter Outlet MAX 0.210 ND ND ND ND ND ND ND 77 26 ND ND ND ND ND ND ND ND Winter Outlet MIN 0.210 ND ND ND ND ND ND ND 77 26 ND ND ND ND ND ND ND ND Winter Outlet MEDIAN 0.210 ND ND ND ND ND ND ND 77 26 ND ND ND ND ND ND ND ND Winter Outlet STDEV ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND Winter Outlet NUMBER 100000001100000000 Winter Outlet COV ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 24-9
Table 24-4 shows the 2017 infiltration volume and load reductions for the WIB. The load calculations used the geometric mean of the chemical parameter as the final concentration. Loads were only calculated where there were data for the inlets and outlet. Only one sample was collected at the outlet. The sample collected from the outlet was from a significant storm, 3.32 inches. When more samples from the outlet are collected it is believed the calculated performance of the WIB would likely improve.
Table 24-4. Infiltration and load calculations for the performance of the Winter Infiltration Basin.
Total Vol. TP TSS Site (L) (Lbs.) (Lbs.)
Winter Basin In S 30,588,374 27.0 6,953 Winter Basin In W 1,414,368 0.28 129 Winter Outlet 2,167,679 1.0 370 Percent removed 93% 96% 95%
CONCLUSION
The Winter Infiltration Basin needs maintenance. Trash appears to be building up inside the trash racks at both inlet outfalls and should be removed. Sand is accumulating by the outfalls and needs to be removed. The hydrodynamic separator at the south inlet may also need to be cleaned.
The challenges at this site were parking for site access/sample collection, determining appropriate pacing for the inlets and outlet, ISCO datalogger software failures, the limited number of outlet events, and paper wasps building nests in the above ground outlet monitoring box.
In conclusion, the Winter Infiltration Basin appears to infiltrate and treat 100% of the storms under 1.44 inches. The load table (Table 24-4) shows the Winter Infiltration Basin is 90+% effective at infiltration as well as TP and TSS removal. There is a need to collect samples from more storms and larger events to verify the Winter Infiltration Basin is working. Specifically, more samples need to be collected at the outlet to help determine if resuspension is occurring during large storms.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 24-10 25. 24th & Elm Infiltration Chamber
BACKGROUND
The 24th & Elm Infiltration Chamber (EIC) (Figure 25-1) drains a total of 14.27 acres and was built to infiltrate stormwater from a light industrial and mixed-use watershed. The EIC stormwater Best Management Practice (BMP) was constructed in 2016 by the City of Minneapolis Public Works. The EIC was constructed to both treat stormwater by infiltrating it, and to reduce stormwater volume discharging to the Mississippi River. Reducing volume alleviates hydraulic pressure on downstream stormwater conveyance infrastructure.
The EIC is a large cement infiltration box that is open at the bottom to promote infiltration and buried under 24th Ave. SE. The chamber is 12 feet wide, 462 feet long and 10 feet high. The EIC has the unique feature of having the outlet also function as an inlet when hydraulic relief is needed from the downstream Elm Street SE pipe. The BMP has two main inlets: The north inlet is a 36 inch RCP and drained 3.93 acres, and the south inlet is a 36 inch RCP and drained 10.34 acres. Both inlets have hydrodynamic separators pretreat stormwater by removing solids from prior to discharge to the EIC. The outlet and north inlet are the same pipe (36 inch RCP); therefore, dataloggers and samplers were placed at different locations to capture inflow to the EIC and outflow from the EIC through this pipe. Under normal conditions, most of the water entering the EIC infiltrates, but under a large or intense storm it can produce outflow that drains to the Mississippi River via the Elm St. SE pipe.
Figure 25-1. Aerial photo of 24th & Elm Infiltration Chamber. Blue arrows show the direction of flow.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-1 METHODS
Site Installation
On 5/8/17, both the north and south inlet monitoring equipment was installed upstream of the hydrodynamic separators. Access to the inlets at 24th & Elm was very tight, Figure 25-2. The outlet monitoring equipment was installed on 5/2/17. All equipment was removed on 11/3/17.
Monitoring equipment at each of the sites included: ISCO 2150 datalogger, 2105 interface module, 2103ci cell phone modem or 2015ci combined interface/modem, low-profile AV probe, and a 3700 ISCO sampler. The equipment at the north inlet and outlet was hung from eye-bolts below grade at each access manhole. Installation at the south inlet required a cross hanger due to its shallowness. The datalogger used the cell phone modem to remotely upload data to a MPRB database server from Monday through Friday. The datalogger could also be remotely called up and programmed to turn samplers on or off, adjust the level, pacing, or triggers.
The samplers were flow-paced and equipped with 24 one-liter bottles, 3/8” ID (inner diameter) vinyl tubing, and an intake strainer. The sampler was programmed to multiplex, taking four flow-paced samples per bottle, allowing for 96 flow-paced samples per storm.
Figure 25-2. Photograph of the 36 inch south inlet at 24th & Elm prior to equipment installation. Note the hydrodynamic separator downstream on the left. The blue arrow shows the direction of flow.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-2 Sample Collection
With all new sites sample collection, parameters need to be adjusted from initial assumptions. In 2017, both the north and south inlets were set to trigger at 0.80 inches of flow and paced at 150 cubic feet. On 6/22/17, the north inlet pacing was changed to 100 cubic feet. The outlet trigger was initially set for 0.8 inches and paced at 1 cubic foot. On 6/12/17 the outlet pacing was changed to 10 cubic feet.
RESULTS & DISCUSSION
Sample Collection
Sample collection was difficult for most of the summer due to trucks parking on top of manholes Figure 25-3. Requests were made starting May 31st for parking services to install no parking signs in small stretches where access was needed. The no parking signs were finally installed in late September.
Figure 25-3. Truck parked over the outlet manhole cover at 24th & Elm.
In 2017, at both the north and south inlets, samples from fourteen events were collected. Four events were sampled at the outlet, as shown in Table 25-1. The table shows the start and end dates and times as well as the rain amount, duration, intensity, and the hours since last rain. The largest storm event sampled was on 10/1-3/17 and had 3.32 inches of precipitation.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-3 Table 25-1. The 2017 precipitation events captured at 24th & Elm Infiltration BMP. The rain gauge was on the roof of the MPRB SSSC, 3800 Bryant Ave. S. Minneapolis, MN. A precipitation event was defined as a storm greater than 0.10 inches and separated by eight hours or more from other precipitation. Full = all chemical parameters run. Partial = some chemical parameters were not run due to low volume or expired holding times. - = storm not sampled.
Hours 24th & 24th & since Elm Elm 24th Start End Rain Duration Intensity last north south & Elm Start Date Time End Date Time (inches) (hours) (in/hr.) Rain. inlet inlet outlet 6/11/2017 7:45 6/11/2017 9:45 0.90 2.00 0.45 501 Partial Partial Partial 6/12/2017 13:45 6/12/2017 16:15 0.32 2.50 0.13 28 Full Full - 6/22/2017 5:45 6/22/2017 15:30 0.43 9.75 0.04 47 Full Full - 6/28/2017 3:00 6/28/2017 9:15 0.61 6.25 0.10 131 Full Full - 7/17/2017 21:30 7/18/2017 18:30 1.11 21.00 0.05 405 Partial - - 7/19/2017 14:45 7/19/2017 21:45 0.27 7.00 0.04 20 - Partial - 7/25/2017 17:00 7/26/2017 7:15 1.25 14.25 0.09 139 Full Full Full 8/3/2017 5:45 8/3/2017 23:00 0.35 17.25 0.02 191 - Full Partial 8/5/2017 16:45 8/5/2017 17:30 0.13 0.75 0.17 42 Partial Partial - 8/6/2017 18:00 8/7/2017 4:45 0.09 10.75 0.01 25 Partial Partial Partial 8/25/2017 5:00 8/25/2017 6:00 0.13 1.00 0.13 192 Partial Partial - 8/25/2017 21:30 8/26/2017 15:15 1.48 17.75 0.08 16 Partial Partial - 9/4/2017 15:45 9/4/2017 16:45 0.16 1.00 0.16 192 Partial Partial - 9/18/2017 3:15 9/18/2017 14:00 0.35 10.75 0.03 323 Full - - 9/20/2017 1:30 9/20/2017 2:00 0.34 0.50 0.68 35 Full Full - 9/25/2017 1:45 9/25/2017 9:30 0.19 7.75 0.02 120 Full Full - 9/25/2017 19:15 9/26/2017 5:15 0.19 10.00 0.02 10 Partial Partial - 10/1/2017 0:15 10/3/2017 9:30 3.32 57.25 0.06 115 Full Full Full 10/6/2017 13:15 10/7/2017 12:00 0.46 22.75 0.02 76 Partial Partial - 10/14/2017 13:30 10/15/2017 3:00 0.43 13.50 0.03 170 Partial Partial - 10/21/2017 6:15 10/21/2017 20:15 0.43 14.00 0.03 147 Partial Partial -
Figure 25-4 and Figure 25-5 show the north inlet and south inlet stage and discharge for 2017. Both inlets yielded roughly the same volume of water in 2017. Figure 25-6 shows the outlet stage and discharge for 2017. The outlet had fewer events due to the infiltration chamber infiltrating all smaller storms. At the outlet, stormwater can go both into and out of the BMP during large events. This phenomenon is shown as by the area velocity probe having both positive and negative velocities during the same event.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-4
Figure 25-4. 2017 24th & Elm north inlet stage and discharge.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-5
Figure 25-5. 2017 24th & Elm south inlet stage and discharge.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-6
Figure 25-6. 2017 24th & Elm outlet stage and discharge.
Storm Event Data and Statistics
Table 25-2 shows the 2017 24th & Elm Stormwater water chemistry data. Some of the events collected were analyzed for limited parameters because of low volume or expired holding times.
The June sulfate data that are bold in Table 25-2 failed MPRB’s blind monthly performance standard for that month. It was deemed the data can be used with caution, noting that performance standards were outside the 80-120% recovery standards, Section 29, Quality Assurance Assessment Report.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-7 Table 25-2. 2017 24th & Elm Stormwater chemistry events data. Cells with less than values indicate that the concentration of that parameter was below reporting limit. ND = no data due to expired holding time or low volume. Data that are bold had a blind performance standard failure for that month, for that parameter.
Sample TP TDP OrthoP TKN NH3 NO3NO2 Hardness TSS VSS TDS cBOD Sulfate Sp.Cond. pH std Cu Pb Zn Date Sampled Time Site Location Type mg/L mg/L mg/L mg/L mg/L mg/L Cl mg/L mg/L mg/L mg/L mg/L mg/L mg/L µhmos units ug/L ug/L ug/L 6/11/2017 11:07 24th & Elm in N Composite 0.213 ND ND 1.75 ND ND 8.2 32 74 25 ND ND ND 117 6.6 9 3 57 6/12/2017 17:44 24th & Elm in N Composite 0.155 0.021 0.061 2.39 0.831 0.482 6.4 36 50 15 87 6 33 122 7.0 20 4 49 6/22/2017 12:33 24th & Elm in N Composite 0.193 0.029 0.087 1.08 0.297 0.366 4.1 44 85 18 90 8 6 118 7.8 20 6 70 6/28/2017 8:37 24th & Elm in N Composite 0.129 0.027 0.044 0.65 <0.250 0.320 2.7 32 30 14 67 24 5 89 7.1 12 6 40 7/18/2017 11:01 24th & Elm in N Composite 0.124 ND ND ND ND ND ND 76 ND ND ND ND ND 204 ND ND ND ND 7/26/2017 5:52 24th & Elm in N Composite 0.186 0.035 0.062 0.987 0.643 0.344 3.2 40 113 36 59 5 6 104 7.6 22 7 60 8/5/2017 19:02 24th & Elm in N Composite 0.202 ND ND 1.58 0.204 ND 6.0 48 77 31 ND ND ND 146 ND 29 5 77 8/6/2017 14:19 24th & Elm in N Composite 0.180 ND ND 0.867 0.249 ND <2.00 28 100 31 ND ND ND 91 ND 19 7 68 8/25/2017 7:10 24th & Elm in N Composite 0.121 ND ND 1.77 ND <0.030 17.8 50 31 14 ND ND ND 198 ND 9 2 54 8/26/2017 2:41 24th & Elm in N Composite 0.051 ND ND 0.673 ND 0.212 2.4 24 37 14 ND ND ND 69 ND 12 2 31 9/4/2017 17:45 24th & Elm in N Composite 0.169 ND ND 1.92 ND <0.030 15.3 ND 26 18 ND ND ND 227 ND ND ND ND 9/18/2017 15:02 24th & Elm in N Composite 0.162 0.034 0.062 1.08 0.667 0.369 6.1 50 <1.00 <2.00 85 4 7 143 6.3 19 3 48 9/20/2017 3:49 24th & Elm in N Composite 0.207 0.031 0.060 0.886 0.423 0.343 2.4 30 142 20 49 <1.00 7 105 6.6 19 6 75 9/25/2017 6:06 24th & Elm in N Composite 0.151 0.031 0.044 1.12 0.578 0.426 3.3 44 56 19 75 13 8 120 6.4 24 4 66 9/26/2017 6:30 24th & Elm in N Composite 0.072 ND ND 0.473 ND 0.251 4.2 48 7 6 ND ND ND 114 ND 17 1 <20.0 10/1/2017 14:25 24th & Elm in N Composite 0.078 ND ND 0.626 ND 0.371 3.4 42 9 3 ND ND ND 109 ND 12 1 <20.0 10/2/2017 4:58 24th & Elm in N Composite 0.078 ND ND <0.500 ND 0.229 <2.00 24 30 6 ND ND ND 68 ND 12 3 36 10/2/2017 19:25 24th & Elm in N Composite 0.130 0.012 0.039 0.709 <0.250 0.261 <2.00 30 90 15 30 <1.00 <5.00 83 7.2 14 5 52 10/6/2017 17:15 24th & Elm in N Composite ND ND ND ND ND ND ND ND ND ND ND ND ND ND 8 2 29 10/14/2017 20:11 24th & Elm in N Composite 0.133 ND ND 0.768 ND 0.292 <2.00 34 86 23 ND ND ND 94 ND 10 5 56 10/21/2017 21:32 24th & Elm in N Composite 0.110 ND ND 0.886 ND 0.431 3.9 36 55 19 ND ND ND 97 ND 16 3 57
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-8 Table 25-2 (continued). 2017 24th & Elm stormwater chemistry events data. Cells with less than values indicate that the concentration of that parameter was below reporting limit. ND = no data due to expired holding time or low volume. Data that are bold had a blind performance standard failure for that month, for that parameter.
Sample TP TDP OrthoP TKN NH3 NO3NO2 Hardness TSS VSS TDS cBOD Sulfate Sp.Cond. pH std Cu Pb Zn Date Sampled Time Site Location Type mg/L mg/L mg/L mg/L mg/L mg/L Cl mg/L mg/L mg/L mg/L mg/L mg/L mg/L µhmos units ug/L ug/L ug/L 6/11/2017 10:46 24th & Elm in S Composite 0.337 ND ND 2.27 ND ND 8.2 28 136 55 ND ND ND 110 6.5 22 8 75 6/12/2017 17:28 24th & Elm in S Composite 0.187 0.026 0.047 2.03 0.695 0.504 5.0 24 45 21 74 5 9 101 6.7 15 3 49 6/22/2017 16:06 24th & Elm in S Composite 0.112 0.026 0.042 0.899 0.376 0.400 2.7 24 31 14 56 7 6 77 7.3 12 2 41 6/28/2017 8:46 24th & Elm in S Composite 0.138 0.059 0.034 0.549 <0.250 0.193 2.2 24 18 8 53 7 6 68 7.2 12 1 37 7/19/2017 22:46 24th & Elm in S Composite 0.146 ND ND ND ND <0.030 12.6 60 18 13 ND ND ND 219 ND ND ND ND 7/26/2017 5:41 24th & Elm in S Composite 0.167 0.054 0.034 1.13 0.654 0.287 2.7 20 77 26 34 5 6 76 7.1 17 5 58 8/3/2017 8:32 24th & Elm in S Composite 0.231 0.058 0.067 1.35 0.654 0.236 2.3 28 66 22 68 15 9 88 6.7 19 5 84 8/5/2017 18:56 24th & Elm in S Composite 0.211 ND ND 1.64 0.088 ND 4.6 30 52 23 ND ND ND 100 ND 18 4 61 8/6/2017 14:45 24th & Elm in S Composite 0.169 ND ND 1.30 0.183 ND 2.3 18 31 11 ND ND ND 63 ND 17 7 67 8/25/2017 6:40 24th & Elm in S Composite 0.128 ND ND 1.15 ND 0.145 6.6 36 19 10 ND ND ND 121 ND 11 1 36 8/26/2017 2:55 24th & Elm in S Composite 0.054 ND ND 0.556 ND 0.167 <2.00 16 18 7 ND ND ND 48 ND 8 1 22 9/4/2017 18:13 24th & Elm in S Composite 0.168 ND ND 1.50 ND <0.030 10.6 ND 16 12 ND ND ND 182 ND ND ND ND 9/20/2017 3:38 24th & Elm in S Composite 0.217 0.049 0.058 1.15 <0.250 0.178 <2.00 22 122 29 25 3 <5.00 80 6.3 23 7 112 9/25/2017 4:58 24th & Elm in S Composite 0.227 0.066 0.088 1.42 0.645 0.167 4.7 32 49 20 83 13 8 105 6.3 15 3 60 9/26/2017 6:23 24th & Elm in S Composite 0.179 ND ND 0.993 ND 0.315 5.1 38 8 5 ND ND ND 114 ND ND ND ND 10/1/2017 14:20 24th & Elm in S Composite 0.192 ND ND 0.650 ND 0.208 5.3 34 7 6 ND ND ND 113 ND 10 1 <20.0 10/2/2017 3:40 24th & Elm in S Composite 0.06 ND ND <0.500 ND 0.191 <2.00 16 22 9 ND ND ND 48 ND 11 2 27 10/2/2017 18:25 24th & Elm in S Composite 0.129 0.026 0.023 0.508 <0.250 0.294 <2.00 18 52 17 19 <1.00 <5.00 58 6.8 14 4 46 10/6/2017 17:47 24th & Elm in S Composite 0.071 ND ND <0.500 ND 0.171 <2.00 18 17 7 ND ND ND 54 ND 8 1 26 10/7/2017 7:56 24th & Elm in S Composite 0.054 ND ND <0.500 ND 0.048 <2.00 26 4 3 ND ND ND 65 ND 7 0 <20.0 10/14/2017 20:57 24th & Elm in S Composite 0.119 ND ND 1.30 ND 0.209 <2.00 20 34 13 ND ND ND 67 ND 14 2 42 10/21/2017 21:40 24th & Elm in S Composite 0.120 ND ND 0.886 ND 0.155 2.0 24 41 19 ND ND ND 74 ND 16 3 46 6/11/2017 10:02 24th & Elm Out Composite 1.79 ND ND 5.52 ND ND 100 36 1132 22 ND ND ND 684 6.6 93 53 240 7/26/2017 4:33 24th & Elm Out Composite 0.338 0.064 0.115 1.49 0.550 0.456 10.2 40 269 68 64 5 9 143 7.7 29 14 109 8/3/2017 8:16 24th & Elm Out Composite 0.571 ND ND ND ND ND ND ND ND ND ND ND ND 409 ND ND ND ND 8/6/2017 14:02 24th & Elm Out Composite 0.297 ND ND 1.60 0.220 ND <2.00 32 246 70 ND ND ND 116 ND 30 13 146 10/2/2017 20:16 24th & Elm Out Composite 0.481 0.053 0.179 1.22 <0.250 0.254 3.4 42 338 63 80 <1.00 7 148 7.4 33 17 110
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-9 Table 25-3 shows the 2017 statistics from the 24th & Elm inlets and outlet. Statistics were only calculated for a chemical parameter if there were two or more measured values. When statistical analysis was performed on the data sets and values below the reporting limit were present, half of the reporting limit was used in the calculations.
When comparing the geometric means of the inlets and outlet, the outlet pollutant concentration was higher than the inlets for many parameters. The higher outlet pollutant concentration is likely from large storms causing resuspension or scour in the EIC. It is important to remember that the outlet events were of very low volume, and from both a limited number of events and only 5 large storms.
Table 25-4 shows the 2017 water balance and chemical load calculations for the 24th & Elm Infiltration Chamber. The load calculations used the geometric mean of the chemical parameter as the final concentration. Conversions were made to express the concentration in pounds.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-10 Table 25-3. 2017 24th & Elm stormwater data showing statistics of the inlets and outlet. All data below the reporting limit were transformed into half the reporting limit for statistical calculations (e.g. Zn <20 becomes 10).
TP TDP OrthoP TKN NH3 NO3NO2 Cl Hardness TSS VSS TDS cBOD Sulfate Sp.Cond. pH std Cu Pb Zn Site ID Statistical Function mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L µhmos units ug/L ug/L ug/L 24th & Elm in N MEAN (geometric) 0.133 0.026 0.056 0.946 0.340 0.222 3.5 37.8 39 13 64 5 7.0 114 6.9 15.1 3.4 43.9 24th & Elm in N MEAN (arithmetic) 0.142 0.028 0.057 1.08 0.414 0.295 4.9 39.4 58 17 68 8 9.3 121 6.9 16.0 3.8 49.6 24th & Elm in N MAX 0.213 0.035 0.087 2.39 0.831 0.482 17.8 76.0 142 36 90 24 33.1 227 7.8 29.2 6.8 76.7 24th & Elm in N MIN 0.051 0.012 0.039 0.250 0.125 0.015 1.0 24.0 11 30 1 2.568 6.3 8.2 1.1 10.0 24th & Elm in N MEDIAN 0.142 0.030 0.061 0.886 0.360 0.332 3.4 36.0 55 18 71 6 6.5 112 7.0 16.4 3.8 53.6 24th & Elm in N STDEV 0.048 0.008 0.015 0.556 0.252 0.133 4.6 12.3 39 9 21 8 9.744 0.5 5.7 1.9 19.5 24th & Elm in N NUMBER 20 88 19 1016 19.0 19.0 19 19 888 20 9.0 19 19 19 24th & Elm in N COV 0.338 0.278 0.266 0.517 0.607 0.449 0.933 0.311 0.671 0.545 0.309 0.974 1.047 0.361 0.074 0.353 0.488 0.394 24th & Elm in S MEAN (geometric) 0.140 0.042 0.045 0.880 0.273 0.155 2.7 25.1 28 13 46 5 5.585 6.8 13.4 2.3 40.5 24th & Elm in S MEAN (arithmetic) 0.155 0.046 0.049 1.05 0.367 0.205 3.8 26.5 40 16 52 7 6.192 6.8 14.1 3.1 47.8 24th & Elm in S MAX 0.337 0.066 0.088 2.27 0.695 0.504 12.6 60.0 136 55 83 15 9.0 219 7.3 22.8 8.1 112 24th & Elm in S MIN 0.054 0.026 0.023 0.250 0.088 0.015 1.0 16.0 43 19 1 2.548 6.3 7.1 0.35 10 24th & Elm in S MEDIAN 0.157 0.052 0.045 1.13 0.280 0.191 2.5 24.0 31 13 54 6 6.179 6.7 14.1 2.5 45.7 24th & Elm in S STDEV 0.068 0.017 0.021 0.561 0.266 0.121 3.3 10.0 35 11 23 5 2.642 0.4 4.5 2.3 25.6 24th & Elm in S NUMBER 22 88 21 1019 22.0 21.0 22 22 888 22 9.0 19 19 19 24th & Elm in S COV 0.438 0.370 0.429 0.535 0.725 0.590 0.858 0.379 0.868 0.712 0.455 0.689 0.418 0.454 0.055 0.317 0.735 0.536 24th & Elm Out MEAN (geometric) 0.548 0.058 0.143 2.00 0.247 0.340 7.7 37.3 399 51 72 2 8.1 233 7.2 40.6 20.4 143 24th & Elm Out MEAN (arithmetic) 0.695 0.059 0.147 2.46 0.298 0.355 28.7 37.5 496 56 72 3 8.1 300 7.3 46.5 24.5 151 24th & Elm Out MAX 1.79 0.064 0.179 5.52 0.550 0.456 100 42.0 1132 70 80 5 9.2 684 7.7 93.3 53.3 240 24th & Elm Out MIN 0.297 0.053 0.115 1.22 0.125 0.254 1.0 32.0 246 22 64 1 7.1 116 6.6 29.2 13.4 109 24th & Elm Out MEDIAN 0.481 0.059 0.147 1.55 0.220 0.355 6.8 38.0 304 66 72 3 8.1 148 7.4 31.7 15.7 128 24th & Elm Out STDEV 0.620 0.008 0.045 2.05 0.223 0.143 47.7 4.4 426 23 11 3 1.4 245 0.6 31.3 19.3 61.6 24th & Elm Out NUMBER 522432 4.0 4.0 442225 3.0 444 24th & Elm Out COV 0.893 0.133 0.308 0.834 0.748 0.402 1.67 0.118 0.858 0.406 0.157 0.957 0.178 0.818 0.083 0.673 0.787 0.407
Table 25-4. 2017 24th & Elm stormwater water balance, chemical load calculations in pounds, and percent removed. Decimals were used to show removal rates between 99% and 100%.
TP TDP OrthoP TKN NH3 NO3NO2 Cl Hardness TSS VSS TDS cBOD Sulfate Cu Pb Zn Site Vol Liters lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. 24th & Elm in N 7,957,615 2.33 0.461 0.977 16.6 5.96 3.90 61.0 663 680 236 1,127 86.8 123 0.265 0.059 0.770 24th & Elm in S 8,259,388 2.55 0.773 0.826 16.0 4.96 2.82 49.6 456 516 234 838 99.7 100 0.244 0.042 0.738 24th & Elm Out 76,370 0.092 0.010 0.024 0.337 0.042 0.057 1.30 6.28 67.2 8.52 12.1 0.383 1.36 0.007 0.003 0.024 Percent removed 99.5% 98% 99% 99% 99% 99.6% 99% 99% 99% 94% 98% 99% 99.8% 99% 99% 97% 98%
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-11 CONCLUSION
In conclusion, the problem of trucks parking on top of manholes appears to have been largely solved with traffic control installing no parking signs. These sites were very tight to work in to both install and uninstall. With the flow-pacing set, antennas buried in the street, eye bolts and anchor hardware set, 2018 monitoring should be easier to accomplish.
In reviewing Table 25-4, the 24th & Elm Infiltration Chamber infiltrated 99.5% of the stormwater and 94% to 99.6% of the nutrients and chemicals found in the stormwater it received. Decimal percents were used to show removal rates between 99% and 100%. The EIC is working very well, as most other BMPs (e.g. ponds) only achieve a 50% to 80% reduction in most chemical parameters. Caution must be noted as this is the first year of monitoring following construction and additional monitoring should be done after years of service have passed.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 25-12 26. GOLF COURSE WETLAND MONITORING
BACKGROUND
The Audubon Cooperative Sanctuary Program for Golf (ACSPG) is described as an award-winning education and certification program that helps golf courses protect the environment and preserve natural areas. By helping enhance the valuable natural areas and wildlife habitats that golf courses provide, improving efficiency, and minimizing potentially harmful impacts of golf course operations, the program serves an important environmental role. Audubon International provides both a Site Assessment and Environmental Planning Form to provide guidance for certification. The areas used for the certification process are:
• Environmental Planning
• Wildlife and Habitat Management
• Chemical Use Reduction and Safety
• Water Conservation
• Water Quality Management
• Outreach and Education
Environmental Management assists the MPRB golf courses in collecting both water and vegetation data required for their annual certification by the ACSPG. The ACSPG has a water quality and aquatic plant monitoring component as part of their final certification. Each golf course integrates these data (plant and water chemistry) into their final certification application.
Theodore Wirth and Meadowbrook Golf Courses have requested annual monitoring since 2001. Columbia, Hiawatha and Gross Golf Courses have included environmental monitoring to their programs since 2009. The ACSPG certification and plant and water chemistry data collected will hopefully help lead to improved land/water stewardship.
Golf Course Foremen assisted Water Resources staff in choosing representative water bodies on each MPRB course. A visual survey of aquatic and wetland vegetation was conducted at each sample site. The ACSPG suggests the monitoring of basic physical water quality parameters such as, temperature, conductivity, pH, and dissolved oxygen. These parameters were measured with a Hydrolab Minisonde 5 Multiprobe. The ACSPG also suggest the chemical parameters to be monitored as total phosphorus, nitrate/nitrite, and ammonia. Water samples were collected and taken to Instrumental Research, Inc. for laboratory analysis of the chemical parameters. Standard MPRB sampling and QA/QC procedures were followed. This report details the last five years of data and older data can be found in previous reports.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-1
COLUMBIA GOLF COURSE
Three ponds on the Columbia Golf Course were chosen for monitoring and are shown in Figure 26-1 and Figure 26-2. The headwaters pond is just off of Pond 1, Hole 4. Pond 1 receives water from a groundwater well used to irrigate the golf course and had clear water all year. Pond 2, Driving Range Pond, receives surface drainage from the driving range and drains to an unsampled pond downstream of Pond 1. Pond 3, Outlet Pond, is the last pond in the series and outlets to a low area before entering a storm sewer that drains to the Mississippi River. 2017 was the ninth year of monitoring at Columbia Golf Course. On July 28th, 2017, aquatic, terrestrial, and wetland plants, in the ponds and surrounding buffer zones were surveyed.
Figure 26-1. Photographs of Columbia Golf Course Ponds 1-3.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-2
Figure 26-2. Sample sites on the Columbia Golf Course.
All plant species identified from Columbia Golf Course are presented in Table 26-1. Cattails, smartweeds, and stinging nettles are the most prevalent species surveyed in the past five years. One new native species, water stargrass, was discovered in 2017. The water quality monitoring results from 2013-2017, from the Hydrolab and water chemistry, at Columbia Golf Course are shown in Table 26-2.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-3
Table 26-1. Dominant plants within and surrounding the Columbia Golf Course Ponds.
Columbia Golf Course Hole 4 Pond Driving Range Pond Outlet Pond Scientific Name Common Name Aug-13 J ul-14 J ul-15 J ul-16 J ul-17 Aug-13 J ul-14 J ul-15 J ul-16 J ul-17 Aug-13 J ul-14 J ul-15 J ul-16 J ul-17 Terrestrial and Wetland Species Agrostis gigantea Redtop X Alisma subcordatum Water Plantain X X Ambrosia artemisiifolia Common Ragweed X X Arctium minus Burdock X X X Asclepias incarnata Marsh Milkweed X X X X Asclepias syriaca Common Milkweed X X X X X X Aster spp Aster 1 X X X X Carex spp Sedge X Cerastium vulgatum Mouse-eared Chickweed X Cirsium spp Thistle X X X X X X X X X X Cyperus esculentus Yellow Nut Sedge X Eliocharis obtusa Spike Rush X X Fraxinus Pennsylvanica Green Ash X X X Nepta cataria Catnip X Parthenocissus quinquefolia Virginia Creeper X X X X Persicaria lapathifolia Nodding Smartweed X Poa pratensis Kentucky Bluegrass X X X X X X Polygonum pensylvanicum Smartweed X X X X X X X X X X Potentilla millegrana Diffuse Cinquefoil X X Potentilla norvegica Rough Cinquefoil X X Rorippa palustris Common Yellowcress X X Rumex crispus Curled Dock X X X X X X X X X X X Salix spp Sandbar Willow X X X X Schoenoplectus acutus Hardstem Bulrush X X X Scirpus fluviatilis River Bulrush X X Sinapis spp Mustard X X X X X X X X Solanum dulcamara Bittersweet Nightshade X X X X X X X X Solidago spp Goldenrod X X Typha spp Cattail X X X X X X X X X X X X X X Ulmaceaespp Elm X Urtica dioica Stinging Nettle X X X X X X X X X X X X X Verbena hastata Blue Vervain X X X X X X X X X X Vitus riparia Riverbank Grape X X X X X
Aquatic Species Hole 4 Pond Driving Range Pond Outlet Pond Scientific Name Common Name Aug-13 J ul-14 J ul-15 J ul-16 J ul-17 Aug-13 J ul-14 J ul-15 J ul-16 J ul-17 Aug-13 J ul-14 J ul-15 J ul-16 J ul-17 Aquatic Species Filamentous algae Filamentous algae X X X X X Lemna minor Lesser Duckweed X X X X X X X X Potamogeton zosteriformis Flat Stem Pondweed X Vallisneria americana Water Celery X Zosterella dubia Water Stargrass X
Water quality monitoring results for Columbia Golf Course are shown in Table 26-2. Pond 1 receives water from a groundwater well that is aerated in the pond by a fountain; therefore, the dissolved oxygen concentration in Pond 1 remains relatively high, despite the slight increase in nutrient levels over the past five years. Pond 2 historically had low levels of dissolved oxygen potentially due to eutrophication caused by organic material and nutrients draining into it. Pond 2 is completely anoxic and continues to have low levels of dissolved oxygen and high nutrient concentrations. In 2017 Pond 3 had relatively low dissolved oxygen. Definitive conclusions cannot be drawn from a single sample once a year, but may provide a general overview.
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Table 26-2. Water quality monitoring results for Columbia Golf Course. NS=not sampled.
Temp DO% DO pH SpCond TP NH3 NO3/NO2 Colombia Date Time °C Sat mg/l Units µS/cm mg/L mg/L mg/L Pond 1 - Hole 4 8/15/2013 10:00 14.9 83 8.23 8.1 1615 0.058 0.871 <0.030 Pond 1 - Hole 4 7/30/2014 10:30 16.3 82 7.87 7.5 1633 0.057 0.684 0.064 Pond 1 - Hole 4 7/23/2015 10:20 17.8 NS NS 7.6 1538 0.034 <0.500 0.137 Pond 1 - Hole 4 7/7/2016 11:00 19.7 145 12.89 8.0 1192 0.054 <0.500 1.70 Pond 1 - Hole 4 7/28/2017 9:55 19.6 100 8.93 7.7 1373 0.018 <0.500 0.042 Pond 2 - Driving Range 7/17/2012 NS NS NS NS NS NS NS NS NS Pond 2 - Driving Range 8/15/2013 10:15 19.6 9 0.78 7.7 1357 2.24 6.23 <0.030 Pond 2 - Driving Range 7/30/2014 10:50 19.6 0 0.00 7.2 926 0.671 1.53 1.28 Pond 2 - Driving Range 7/23/2015 10:30 21.4 NS NS 7.5 593 0.536 1.55 0.036 Pond 2 - Driving Range 7/7/2016 11:20 20.5 5 0.40 7.7 662 1.16 2.40 2.22 Pond 2 - Driving Range 7/28/2017 10:05 20.4 11 0.92 7.0 1406 0.98 2.40 0.09 Pond 3 - Outlet 8/15/2013 10:25 19.2 111 10.04 7.2 1591 0.058 3.37 0.063 Pond 3 - Outlet 7/30/2014 11:00 20.7 14 1.19 7.2 1372 0.847 3.33 2.58 Pond 3 - Outlet 7/23/2015 10:50 25.3 NS NS 7.4 1595 0.357 2.63 0.131 Pond 3 - Outlet 7/7/2016 11:35 21.3 10 0.85 7.6 779 0.742 1.55 0.696 Pond 3 - Outlet 7/28/2017 10:15 19.6 48 4.26 6.9 1857 0.389 2.61 0.033
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-5
GROSS NATIONAL GOLF COURSE
Three ponds and a low area site were chosen on Gross National Golf Course. Photographs are presented in Figure 26-3 of the ponds, and a map in Figure 26-4. Pond 7 is one of the oldest water bodies on the golf course and may be a remnant of a natural wetland. The pond is hydrologically isolated, with no drain tile outlets and no connection to the golf course irrigation system. Ponds 14 and 12 were constructed in the mid-1990’s to help improve drainage on the golf course. Drain tile from the surrounding fairways leads to each of these ponds. Groundwater for irrigation of the golf course is pumped to Pond 14. Pond 14 drains to Pond 12. The low area was originally chosen as an additional vegetation survey site since it contained different vegetation than most of the golf course. 2017 was the ninth year of monitoring at Gross Golf Course.
Figure 26-3. Photographs of Gross National Golf Course Ponds 7, 12, and 14.
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Figure 26-4. Sample sites on the Gross National Golf Course.
All species identified from Gross Golf Course are presented in Table 26-3. On July 28th, 2017, aquatic, terrestrial, and wetland plants in the ponds and surrounding buffer zones were surveyed. Curled dock, Kentucky bluegrass and broad-leaved arrowhead were the most prevalent species surveyed in the past five years. One new native species, water stargrass, was found in 2017. In 2017, much of the vegetation surrounding the water bodies was cut down, and a reduction of species could be possibly attributed to the lack of vegetation.
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Table 26-3. Dominant plants at the Gross National Golf Course sample sites.
Gross Golf Course Pond 7 Pond 12 Pond 14 Low Area Scientific Name Common Name Aug-13 Jul-14 Jul-15 Jul-16 Jul-17 Aug-13 Jul-14 Jul-15 Jul-16 Jul-17 Aug-13 Jul-14 Jul-15 Jul-16 Jul-17 Aug-13 Jul-14 Jul-15 Jul-16 Jul-17 Terrestrial and Wetland Species Acer saccharinum Silver Maple XX Achillea millefolium Yarrow XX X Ajuga reptans Bugleweed X Alnus incana Speckled Alder X X X Ambrosia spp Ragweed XX Arctium ssp Burdock X X Asclepcias incarnata Marsh Milkweed X Asclepcias syriaca Common Milkweed X X Aster spp Aster X X Brassica rapa Field Mustard X Carex spp Sedge X Circaea spp Enchanter's Nightshade X Cirsium spp Thistle XX XX XX X Cirsium avense Canadian Thistle XX X XX XXX Cyperus esculentus Yellow Nutsedge XX Cyperus odoratus Flat sedge X Daucus carota Queen Anne's Lace X Erigeron annuus Daisy fleabane X Echinochloa crusgalli Barnyard Grass X X Eloecharis obtusa Blunt Spikerush X X X Eupatorium perfoliatum Boneset XX Fraxinus pennsylvanica Green Ash XX Lythrum salicaria Purple Loosestrife XX Mimulus ringens Square-stemed Monkeyflower X X Parthenocissus quinquefolia Virginia Creeper X Phalaris arundinacea Reed Canary Grass XXXXX X X XXX Poa pratensis Kentucky Bluegrass XXXXXXXXXX X X XXX Polygonum pensylvanicum Smartweed XXXXX XXX X X Populus deltoides Eastern Cottonwood X X Populus tremuloides Aspen XXXX X X Potentilla norvegica Rough Cinquefoil X Rhamnus cathartica Common Buckthorn X X X Rudbeckia hirta Black eyed susan X XXX Rumex crispus Curled Dock XX XX XXX X X Sagittaria latifolia Broad-leaved Arrowhead XXXX XX X X X Salix spp Weeping Willow XXX Salix spp Sandbar Willow XX XX X X X Salix nigra Black Willow X X Schoenoplectus acutus Hardstem Bulrush X X Scripus atrovirens Green Bulrush X Scirpus fluviatilis River Bulrush XXXXXXX X X Scirpus validus Soft stem Bulrush X Scutellaria galericulata Marsh Skullcap X Solanum dolcamara Bittersweet Nightshade XX X Sonchus ssp Sow Thistle XX Setaria veridis Foxtail XX X Sinapis spp Mustard XX Solidago canadensis Canada goldenrod XX X X Sonchus oleraceus Common Sow-thistle X Typha spp Cattail XXXXXXXXXX Urtica dioica Stinging Nettle X Verbena hastata Blue Vervain X XX Verbena urticifolia White Vervain X Vitus riparia Riverbank Grape X X X
Aquatic Species Pond 7 Pond 12 Pond 14 Low Area Scientific Name Common Name Aug-13 Jul-14 Jul-15 Jul-16 Jul-17 Aug-13 Jul-14 Jul-15 Jul-16 Jul-17 Aug-13 Jul-14 Jul-15 Jul-16 Jul-17 Aug-13 Jul-14 Jul-15 Jul-16 Jul-17 Aquatic Species Ceratophyllum demersum Coontail X X Filamentous algae Filamentous algae X X X X X Lemna minor Lesser Duckweed X XX X XXX XXXX Spirodela polyrhiza Big Duckweed X Zosterella dubia Water Stargrass X
Water quality monitoring results for Gross Golf Course are shown in Table 26-4. The Pond 7 dissolved oxygen levels, in 2016 and 2017, have been well above the levels of the previous years. Additionally, nutrient levels appear to be trending downward. Ponds 12 and 14 are aerated with fountains. The fountains increase dissolved oxygen levels in these two ponds. Ammonia and nitrates/nitrites remained relatively low for both Ponds 12 and 14. The phosphorous levels for Ponds 12 and 14 show a moderate decrease over time. Definitive conclusions cannot be drawn from a single sample once a year, but can provide general information.
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Table 26-4. Water quality monitoring results for Gross National Golf Course. NS=not sampled.
Temp DO% DO pH SpCond TP NH3 NO3/NO2 Gross Date Time °C Sat mg/l Units µS/cm mg/L mg/L mg/L Pond 7 8/15/2013 8:50 18.9 5 0.47 6.8 412 1.60 1.02 <0.030 Pond 7 7/30/2014 9:00 21.0 2 0.15 7.3 360 0.811 <0.500 0.485 Pond 7 7/22/2015 9:00 23.5 NS NS 7.6 351 0.514 0.629 <0.030 Pond 7 7/7/2016 10:00 24.8 102 8.22 8.0 387 0.871 <0.500 0.350 Pond 7 7/28/2017 8:50 24.8 95 7.74 8.2 408 0.583 <0.500 0.04 Pond 12 8/15/2013 9:15 19.1 13 1.15 6.7 346 0.320 1.01 <0.030 Pond 12 7/30/2014 9:40 20.5 21 1.86 7.4 289 0.119 <0.500 <0.030 Pond 12 7/22/2015 9:45 25.7 NS NS 7.6 447 0.222 <0.500 <0.030 Pond 12 7/7/2016 10:10 24.6 42 3.42 8.0 382 0.430 <0.500 0.035 Pond 12 7/28/2017 9:10 24.9 90 7.28 8.0 482 0.071 <0.500 0.033 Pond 14 8/15/2013 9:10 18.1 96 8.90 7.6 385 0.075 0.637 <0.030 Pond 14 7/30/2014 9:30 20.1 86 7.62 7.9 391 0.244 <0.500 <0.030 Pond 14 7/22/2015 9:30 23.0 NS NS 7.7 448 0.344 <0.500 0.037 Pond 14 7/7/2016 10:30 24.7 50 4.06 7.9 361 0.347 <0.500 1.45 Pond 14 7/28/2017 9:00 24.3 85 6.98 7.9 488 0.083 <0.500 <0.030
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-9
HIAWATHA GOLF COURSE
Water quality staff, in consultation with the golf course Foreman, chose four representative sample sites at the Hiawatha Golf Course. Ponds 1, 2 and 3 are part of an interconnected chain of ponds pumped to Lake Hiawatha (Figure 26-5 and Figure 26-6). Stormwater and groundwater, carried by drain tile between ponds, are the two sources of pond water. During storm events, stormwater from neighborhood streets drain to the Hiawatha pond chain. The golf course parking lot is also drained to Pond 1. 2017 was the ninth year of monitoring at Hiawatha Golf Course.
Figure 26-5. Photographs of Hiawatha Golf Course Ponds 1 – 4.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-10
Figure 26-6. Sample sites on the Hiawatha Golf Course.
All species identified from Hiawatha Golf Course are presented in Table 26-5. On August 1st, 2017, aquatic, terrestrial, and wetland plants in the ponds and surrounding buffer zones were surveyed. Kentucky bluegrass, reed canary grass, and cattails were the most prevalent species surveyed in the past five years. One new species, orange jewelweed, was found in 2017. All plant species identified from the last five years of monitoring Hiawatha Golf Course are presented in in Table 26-5.
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Table 26-5. Dominant plants within and surrounding the Hiawatha Golf Course sample sites.
Hiawatha Golf Course Pond 1 Pond 2 Pond 3 Pond 4 Scientific Name Common Name Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Terrestrial and Wetland Species Acer spp Maple (saplings) XXXXXXX X Ambrosia artemisiifolia Common Ragweed X XXXXXXX X X Ambrosia trifida Giant Ragweed XXXX XX X Asclepias spp Milkweed X Asclepias syriaca Common Milkweed X X Aster spp Aster X X X X Carex spp Sedge XXXXX Cirsium spp Thistle X XX X X Eloecharis obtusa Blunt Spikerush XXXX Impatiens capensis Orange Jewelweed X Fraxinus pennsylvanica Green Ash XXXX X Gleditsia triacanthos Honey Locust X XX Impatiens pallida Pale Jewel Weed X Larix laricina Tamarack XXX Lythrum salicaria Purple Loosestrife X X Menispermum canadence Moonseed X Phalaris arundinacea Reed Canary Grass XXXXXXXXXXXXXXX Poa pratensis Kentucky Bluegrass XXXXXXXXXXXXXXXXXXXX Polyganum perfoliatum Tearthumb XX X XX Polygonum hydropier Smartweed X X X X Rumex crispus Curled Dock XXXX X XXXX X X Sagiteria latifolia Broad-leaf Arrowhead XXX Salix spp Sandbar Willow XX XX XXXX Scirpus fluviatiis River Bulrush XXX XX Solidago spp Goldenrod XXX Sonchus oleraceous Common Sow Thistle XXXXXXXX X Typha spp Cattail XXXXXXXX X X X Unknown Annual Weeds XXX X X Urtica diotica Stinging Nettle XX XXX XX Verbena hastata Blue Vervain XXX X
Aquatic Species Pond 1 Pond 2 Pond 3 Pond 4 Scientific Name Common Name Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aquatic Species Ceratophyllum demersum Coontail X X Filamentous Algae Filamentous Algae X Elodea canadensis Canadian Waterweed X Lemna minor Lesser Duckweed X X XXX Nymphaea odorata White Water Lily X Potamogeton foliosus Narrow Leaf Pondweed X X X X Potamogeton pectinatus Sago Pondweed X
Water quality monitoring results for Hiawatha Golf Course are shown in Table 26-6. In 2017, ponds 1, 2 and 3 continued to have high dissolved oxygen. The high oxygen in Pond 4 during the 2015 survey appears to be an outlier, as low dissolved oxygen levels were observed every other year.
High nutrients can lead to eutrophication causing undesirable low oxygen and algal growth. In 2017, nitrate/nitrite levels were higher in Pond 2 but lower in Pond 1. Ponds 3 and 4 remained largely the same with slight increases in nitrates/nitrites and ammonia. In 2017, all four ponds had a decrease in total phosphorous. Definitive conclusions cannot be drawn from a single sample once a year, but can provide general information.
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Table 26-6. Water quality monitoring results for Hiawatha Golf Course. NS=not sampled.
Temp DO% DO pH SpCond TP NH3 NO3/NO2 Hiawatha Date Time °C Sat mg/l Units µS/cm mg/L mg/L mg/L Pond 1 8/16/2013 9:30 21.4 129 11.21 7.9 598 0.046 <0.500 <0.030 Pond 1 7/31/2014 9:50 23.1 94 7.82 7.8 668 0.179 <0.500 0.081 Pond 1 7/29/2015 9:30 27.3 137 10.52 8.1 679 0.108 <0.500 <0.030 Pond 1 7/7/2016 13:50 25.8 137 10.86 7.8 581 0.090 0.562 1.53 Pond 1 8/1/2017 10:30 24.3 107 8.78 8.1 814 0.036 <0.500 0.034 Pond 2 8/16/2013 9:20 16.9 65 6.18 7.2 986 0.039 0.660 0.622 Pond 2 7/31/2014 10:10 18.6 150 13.63 7.5 1004 0.150 <0.500 2.306 Pond 2 7/29/2015 9:45 24.5 126 10.19 7.7 905 0.084 <0.500 0.355 Pond 2 7/7/2016 14:00 20.1 100 8.78 7.6 915 0.073 <0.500 0.045 Pond 2 8/1/2017 10:40 19.3 78 7.01 7.5 990 0.032 0.743 2.02 Pond 3 8/16/2013 9:10 18.9 71 6.45 7.4 936 0.073 0.590 0.540 Pond 3 7/31/2014 10:20 21.0 94 8.17 7.5 952 0.193 0.760 0.390 Pond 3 7/29/2015 10:00 24.1 99 8.07 7.7 909 0.102 <0.500 0.213 Pond 3 7/7/2016 14:10 22.4 78 6.56 7.6 925 0.107 0.818 0.236 Pond 3 8/1/2017 10:50 21.5 77 6.61 7.5 982 0.045 1.330 0.616 Pond 4 8/16/2013 8:55 18.3 21 1.93 7.1 937 0.118 1.27 0.771 Pond 4 7/31/2014 10:30 18.1 21 1.94 7.1 996 0.240 2.81 2.66 Pond 4 7/29/2015 10:30 23.7 109 8.92 7.6 873 0.174 0.706 0.232 Pond 4 7/7/2016 14:20 21.9 17 1.42 7.4 962 0.135 2.62 0.140 Pond 4 8/1/2017 11:00 22.6 37 3.17 7.1 1027 0.055 3.44 0.532
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-13
MEADOWBROOK GOLF COURSE
Four water bodies are monitored at Meadowbrook Golf Course: Meadowbrook Lake, Wetland C, Wetland L, and Wetland N. Photographs are shown in Figure 26-7 and a map in Figure 26-8. Each of the sampled water bodies on the Meadowbrook Golf Course had unique hydrologic characteristics. Wetland C is the furthest upstream and only receives runoff from the surrounding course. Wetland N is near the course edge and receives stormwater from the neighborhood. Wetland L is a pond. Minnehaha Creek flows through Meadowbrook Lake. 2017 was the seventeenth year of Audubon monitoring at Meadowbrook Golf Course.
Figure 26-7. Photographs of Meadowbrook Golf Course water quality and vegetation monitoring locations.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-14
Figure 26-8. Meadowbrook Golf Course water quality and vegetation monitoring locations
All species identified from Meadowbrook Golf Course are presented in Table 26-7. On August 1st, 2017, aquatic, terrestrial, and wetland plants in the ponds and surrounding buffer zones were surveyed. Reed canary grass, hybrid cattails and Kentucky bluegrass were the most prevalent species surveyed in the past five years.
Wetland L had not been easily accessed since 2015 due to a lack of mowing following the flooding in 2014. The area is surrounded by 50 yards of 4-foot-tall grass and was inaccessible for monitoring in 2016.
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Table 26-7. Dominant buffer zone plants surrounding the Meadowbrook Golf Course sample site
Meadowbrook Golf Course Wetland C Wetland N Wetlantd L Medowbrook Lake Scientific Name Common Name Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 NS Jul-15 Jul-16 Aug-17 Wetland and Upland Species Acer ginnala Amur maple XXX Ajuga spp Bugleweed X Arctium minus Burdock X XXX XX Asclepias incarnata Marsh Milkweed X XXX X Asclepias syriaca Common Milkweed X XXX X Asteraceae sonchus Sow Thistle X Carex spp Sedge spp XXX XX Carex meadii Mead's Sedge X Cirsium avense Canadian Thistle X XXX X X Conyza canadensis Horseweed X Echinocystis lobata Wild Cucumber X Eleocharis acicularis Needle spike-rush X X Fraxinus pennsylvanica Green Ash XXXXX X Helenium autumnale Common Sneezeweed X Mimulus ringens Square-stemmed Monkeyflower X Impatiens capensis Orange Jewelweed X X Leonurus cariaca Motherwort XX Lycopus americanus American Bugleweed X Lycopus spp. Bugleweed X X Lythrum salicaria Purple Loosestrife XX Melilotus albus medikus Sweet White Clover X Monarda Bee Balm X Parthenocissus quinquefolia Virginia Creeper X X Persicaria lapathifolia Nodding Smartweed X Phalaris arundinacea Reed Canary Grass XXXXXX XXXX X XX Poa pratensis Kentucky Bluegrass X XXX XXX Polygonum amphibium Water Smartweed XX Polygonum hydropier Common Smartweed X Populus deltoides Eastern Cottonwood X XXXX Populus ssp Aspen X Potentilla norvegica Rough Cinquefoil X Rhamnus cathartica Buckthorn X Rubus strigosus Raspberry X Rudbeckia hirta Black eyed susan X XX Rumex crispus Curled dock XXXX Salix exigua Sandbar Willow X XX Salix nigra Black Willow XXX XX Schoenoplectus acutus Hardstem Bulrush X X Scirpus atrovirens Green Bulrush X X X Scutellaria galericulata Marsh Skullcap X XX Sedge spp. Sedge spp X Solanum dulcamara Bittersweet Nightshade X X Solidago canadensis Canada Goldenrod X X Sonchus oleraceus Common Sow-thistle X XX Sparganium eurycarpum Common Bur-reed X XXX XX Spartina pectinata Prairie cordgrass X Typha angustifolia Narrow leaved cattail X XX Typha latifolia Broad-leaved cattail XXXXXX XX XX Typha X glauca Hybrid Cattail XXXXXXXXXX XX Ulmus pumilla Siberian Elm X XX Ulmus americana American Elm X Urtica dioica Stinging Nettle X XX X Verbena hastata Blue vervain XXX X Vicia cracca Cow Vetch X XX X X X Vitus riparia Riverbank Grape X X X XX Zizea aurea Golden Alexanders X
Aquatic Species Wetland C Wetland N Wetland L Medowbrook Lake Scientific Name Common Name Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 Jul-14 Jul-15 Jul-16 Aug-17 Aug-13 NS Jul-15 Jul-16 Aug-17 Floating Species Lemna minor Lesser Duckweed XXXXXXXXXX X XXXX Nymphaea odorata White Water Lily XX Spirodela polyrhiza Big duckweed XXXX XXX X XX X Wolffia columbiana Watermeal XXXX XXX XXX Submerged Species Ceratophyllum demersum Coontail X X X Filamentous algae Filamentous algae X X Myriophyllum spicatum Eurasian Watermilfoil X X Potamogeton crispus Curly-leaf pondweed X Potamogeton zosteriformis Flat-stem pondweed X Vallisneria americana Water celery X
Water quality monitoring results for Meadowbrook Golf Course are shown in Table 26-8. Wetland C and Wetland N historically have low levels of dissolved oxygen due to the abundance of organic decomposition that is typical of wetland ecosystems. Wetland N returned to its more typical state of low oxygen in 2017 after high oxygen levels were observed in 2016. Nutrient levels in Wetlands C
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-16
and N have remained relatively low and stable. Wetland L was not sampled this year due to inaccessibility.
Meadowbrook Lake experienced a minor increase in ammonia and phosphorous levels in 2017, but generally had relatively stable levels of nutrients and oxygen over the past six years. Definitive conclusions cannot be drawn from a single sample once a year, but may help provide a general overview.
Table 26-8. Water quality monitoring results for Meadowbrook Golf Course. NS=not sampled.
Temp DO% DO pH SpCond TP NH3 NO3/NO2 Meadowbrook Date Time °C Sat mg/l Units µS/cm mg/L mg/L mg/L Meadowbrook Lake 7/19/2012 9:45 26.1 64 5.04 7.4 493 0.104 0.313 0.093 Meadowbrook Lake 8/13/2013 9:25 22.9 61 5.13 7.6 445 0.030 0.714 <0.030 Meadowbrook Lake 7/29/2014 NS NS NS NS NS NS NS NS NS Meadowbrook Lake 7/21/2015 9:00 25.0 NS NS 8.1 608 0.034 <0.500 <0.030 Meadowbrook Lake 7/14/2016 13:00 25.0 65 5.18 7.8 487 0.028 <0.500 0.044 Meadowbrook Lake 8/1/2017 9:30 25.7 54 4.35 7.8 570 0.341 1.270 0.087 Wetland C 7/19/2012 8:55 22.8 4 0.33 6.7 347 0.235 1.34 <0.030 Wetland C 8/13/2013 9:00 18.7 2 0.21 6.8 218 0.130 0.794 <0.030 Wetland C 7/29/2014 9:45 20.8 5 0.41 7.0 544 0.767 1.13 0.078 Wetland C 7/21/2015 9:15 27.4 NS NS 8.0 188 0.142 0.651 <0.030 Wetland C 7/14/2016 12:35 22.8 13 1.06 8.1 246 0.302 <0.500 0.105 Wetland C 8/1/2017 9:05 21.2 1 0.05 7.9 442 0.133 <0.500 0.031 Wetland L 7/19/2012 9:45 19.8 7 0.61 7.2 823 0.353 2.59 <0.030 Wetland L 8/13/2013 9:35 16.1 4 0.34 7.0 875 0.206 2.29 0.131 Wetland L 7/29/2014 10:25 23.5 15 1.23 7.4 516 0.290 <0.500 0.052 Wetland L 7/21/2015 9:30 NS NS NS NS NS NS NS NS Wetland L 7/14/2016 13:30 NS NS NS NS NS NS NS NS Wetland L 8/1/2017 NS NS NS NS NS NS NS NS NS Wetland N 7/19/2012 9:15 23.2 4 0.33 7.0 335 0.811 1.48 <0.030 Wetland N 8/13/2013 9:15 19.3 5 0.45 7.0 373 0.201 0.771 <0.030 Wetland N 7/29/2014 10:15 22.4 18 1.55 7.4 417 0.325 <0.500 <0.030 Wetland N 7/21/2015 10:00 26.0 NS NS 7.9 318 0.152 0.750 <0.030 Wetland N 7/14/2016 12:45 23.5 102 8.46 8.0 227 0.118 <0.500 0.100 Wetland N 8/1/2017 9:20 21.4 6 0.48 7.8 179 0.185 <0.500 <0.030
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-17
THEODORE WIRTH GOLF COURSE
In consultation with the golf course Foreman three sample sites were chosen at Theodore Wirth Golf Course. The Inlet and Outlet of Bassett Creek are monitored in order to assess how the golf course affects stream water quality. The Par 3 wetland is unconnected to Bassett Creek and is located adjacent to a recently developed housing complex and accepts stormwater from this region. The Par 3 wetland had had an increase in the volume in stormwater runoff due to residential development. Figure 26-9 and Figure 26-10 show photographs and the map location of the monitoring sites on the golf course. 2017 was the seventeenth year the Theodore Wirth Golf Course was monitored for Audubon.
Figure 26-9. Photographs of Wirth Golf Course water quality and vegetation monitoring locations.
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Figure 26-10. Wirth Golf Course water quality and vegetation monitoring locations.
On July 27th, 2017, aquatic, terrestrial, and wetland plants in the ponds and surrounding buffers were surveyed. All species identified from Theodore Wirth Golf Course are presented in Table 26-9. Reed canary grass, sandbar willow, and Kentucky bluegrass were the most prevalent species surveyed in the past five years. Two new species, birdsfoot trefoil and wild bergamot, were observed in 2017.
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Table 26-9. Aquatic vegetation monitoring results for the Wirth Golf Course.
Water quality monitoring results for Wirth Golf Course are shown in Table 26-10. The Bassett Creek Inlet shows consistently high concentrations of oxygen as it enters Wirth Golf Course. The Bassett Creek Outlet had a lower amount of oxygen. The Inlet had lower amounts of nutrients than the Outlet.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-20
Higher nutrients may indicate declining water quality of the creek as it flows through the golf course and receives increasing amounts of nutrients from runoff. Historically the Outlet also had higher amounts of nutrients compared to the Inlet. This may indicate that water quality declines as the creek flowed through the golf course and received nutrients from runoff. Uncharacteristically, in 2017 the Outlet possessed lower nutrient levels than the Inlet.
The Par 3 Wetland historically contained low amounts of dissolved oxygen, which is typical of a wetland with an abundance of organic decomposition. During the last two years the oxygen level in the Par 3 wetland had been higher than in previous years. The nutrient concentration in the wetland was similar to previous years but with a slight reduction in phosphorous. Definitive conclusions cannot be drawn from a single sample once a year but may help provide a general overview.
Table 26-10. Water quality monitoring results for Wirth Golf Course. NS=not sampled.
Temp DO% DO pH SpCond TP NH3 NO3/NO2 Wirth Date Time °C Satmg/l Units µS/cm mg/L mg/Lmg/L Bassett In 8/13/201310:35 19.2807.257.88800.072 0.7600.196 Bassett In 7/29/201411:45 20.5958.377.88210.074 <0.500 <0.030 Bassett In 7/21/2015 11:30 22.4 NSNS 7.63050.068 <0.500 0.100 Bassett In 7/5/201611:00 21.3827.07.71011 0.078 <0.500 0.31 Bassett In 7/27/20179:50 22.580.66.87.06050.097 <0.500 0.21 Bassett Out 8/13/201311:15 22.0393.367.58670.085 0.8400.110 Bassett Out 7/29/201412:25 21.2 0 0.007.68100.099 <0.500 0.289 Bassett Out 7/21/2015 12:00 23.5 NSNS 8.07210.088 <0.500 0.093 Bassett Out 7/5/201611:20 23.3292.417.9928 0.12 <0.500 1.20 Bassett Out 7/27/201710:30 24.7665.397.36010.07 <0.500 0.10 Par 3 Wetland 8/13/201311:00 20.6 1 0.117.04220.4221.15 <0.030 Par 3 Wetland 7/29/201411:15 22.3120.987.33340.231 <0.500 <0.030 Par 3 Wetland 7/21/2015 11:00 22.4 NSNS 7.97060.367 0.915 <0.030 Par 3 Wetland 7/5/201611:30 23.2292.47.9300 0.200 0.6440.03 Par 3 Wetland 7/27/201710:10 24.5403.27.12970.101 <0.500 0.04
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 26-21
27. CLIMATOLOGICAL SUMMARY
NATIONAL WEATHER SERVICE DATA
Annual climate data is tracked and reported due to its year to year variability and significant impact on water resources. Table 27-1 and Figure 27-1 shows the Minneapolis National Weather Service (NWS) total monthly precipitation and monthly average temperature for the year 2017.
The climate of Minneapolis is classified as humid continental. It has hot summers and cold winters. In 2017, it was generally warm and had near normal annual precipitation.
The 2017 annual mean temperature was 48.5° F, which was 2.4° F above normal, Table 27-1. Three months had below normal temperatures and nine months had above normal temperatures. The warmest month of the year was July and the coolest month was December. It should be noted that February had the largest temperature deviation from normal at 10.4°F. The average monthly January and February temperatures were above normal with the remaining months near normal, Figure 27-1.
The 2017 annual recorded precipitation total was 32.36 inches, which was 0.14 inches above normal, Table 27-1. Seven months had below normal precipitation and five months had above normal precipitation. The wettest month of the year was August and the driest month was November. The average monthly precipitation shows some significant monthly deviations from normal: April, May, August, and October were wet; and March, September, and November were dry, Figure 27-1.
Table 27-1. Minneapolis precipitation, mean temperature and deviation from normal as recorded by the National Weather Service. Total Mean Precipitation Temp. Year 2017 (inches) Normal Comparison: (F) Normal Comparison: January 0.98 0.08" above normal 20.9 5.3 F above normal February 0.64 0.13" below normal 31.2 10.4 F above normal March 0.68 1.21" below normal 34.0 1.2 F above normal April 4.45 1.79" above normal 50.5 3.0 F above normal May 4.80 1.44" above normal 58.5 0.6 F below normal June 4.23 0.02" below normal 71.4 2.6 F above normal July 3.12 0.92" below normal 75.3 1.5 F above normal August 6.75 2.45" above normal 68.7 2.5 F below normal September 1.04 2.04" below normal 67.3 5.3 F above normal October 4.49 2.06" above normal 51.3 2.4 F above normal November 0.39 1.38" below normal 34.1 0.4 F above normal December 0.79 0.37"below normal 18.9 0.8 F below normal Annual Data 32.36 0.14" above normal 48.5 2.4 F above normal
All NWS data was obtained from NOAA (National Oceanic and Atmospheric Administration) monthly publications.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 27-1
Figure 27-1. Comparison showing the NWS 30-year “normal” with 2017 temperature and precipitation data.
TWIN CITIES RAIN GAUGE COMPARISON
To better understand the local spatial pattern of precipitation, monthly NWS rainfall data were compared to the MPRB weather station.
The MPRB operates a heated tipping bucket rain gauge in southwest Minneapolis, located on the roof of the Southside Operations Center at 3800 Bryant Ave. South. The NWS heated tipping bucket rain gauge is located at the Twin Cities airport. The monthly precipitation and the differences between the MPRB and NWS can be seen in Table 27-2. They were roughly comparable with the exceptions of January, May, and June where the differences were greater than ½”.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 27-2 Table 27-2. Monthly totals for 2017 recorded at the NWS and MPRB SSSC rain gages. Months with * are heated rain gauges and the water equivalent.
NWS MPRB Difference Month (inches) (inches) (inches) Jan* 0.98 0.43 0.55 Feb* 0.64 0.71 0.07 March* 0.68 0.54 0.14 April 4.45 4.76 0.31 May 4.80 5.40 0.60 June 4.23 3.41 0.82 July 3.12 2.83 0.29 August 6.75 6.98 0.23 September 1.04 1.26 0.22 October 4.49 4.80 0.31 November* 0.39 0.12 0.27 December* 0.79 0.44 0.35 Totals 32.36 31.68 0.68
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 27-3 28. WATER QUALITY EDUCATION
ACTIVITIES
In 2017, Minneapolis Park & Recreation Board (MPRB) staff provided water quality education programs throughout the City. Environmental Management naturalist staff participated in 30 Minneapolis community festivals, neighborhood events, as well as concerts and movies (Figure 28- 1). Hands-on water quality educational displays focused on neighborhood watersheds and how human activities impact local water bodies. Education staff utilized portable mini-golf, bean bag toss, an aerial photo floor graphic of the city and its watersheds, and other hands learning activities. In addition, 495 people experienced water quality education while canoeing the lakes of Minneapolis. Other children’s programming focused on water quality education themes in summer programs including a partnership with the Minneapolis Institute of Art that used art and water related activities to serve 335 kids between 6 and 12 years old. Still more programs incorporated water education themes into the summer camps called Urban Adventure Camp, Outdoor Survival, and Nature Explorers serving 245 kids between 6 and 12.
Figure 28-1. Map and list of water quality education sites in 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 28-1 At the lakes
The MPRB continued its’ extensive Aquatic Invasive Species (AIS) Inspection Program at the public boat launches located at Bde Maka Ska (formerly Lake Calhoun), Lake Harriet, and Lake Nokomis. The boat launches are staffed seven days a week from May 1 to December 1 and all boats entering and leaving the lakes are inspected for AIS. In addition to providing boat inspections, staff are an information source for the park visitors. Staff directly interacted with 18,000 park visitors in 2017. Adjacent to the AIS booths are sandwich boards with action steps people can take to be a good water steward. The sandwich board messages can be changed out daily based on weather, time of year, etc. Annually more than five million people visit the Chain of Lakes and more than one million visit Lake Nokomis.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 28-2 Do Not Feed the Ducks
Based on a successful pilot program in 2016 that focused on persuading park patrons to not feed the ducks, the MPRB moved forward with fabrication of permanent education pieces in 2017. An oversized buoy in the shape of a rubber duck will float along the Lake Harriet shoreline that abuts Bread & Pickle (see photos). And more than 200 table-toppers featuring regular size ducks and ‘do not feed the ducks’ messaging will be installed on picnic tables at Bread & Pickle, Sand Castle (Lake Nokomis), and Lola’s (Bde Maka Ska) in 2018.
Minnehaha Park
A moveable water quality education exhibit was deployed at Minnehaha Park near the pavilion that houses the popular restaurant, Sea Salt. The spinning cubes provides information about watersheds, stormwater runoff, and actions people can take to positively impact water quality. This location was chosen because of the consistent captive audience of people standing in line waiting to order food. Intermittent staff observations throughout the season confirmed that many of the people waiting in line were reading the cubes.
Canines for Clean Water
More than 100,000 dogs reside in the City of Minneapolis. They generate an estimated 41,000 pounds of solid waste each day. A water quality education program targeting dog owners was initiated in 2009 called Canines for Clean Water, and we continue to build on this work.
In 2017 the Canines for Clean Water campaign continued to focus on Public Service Announcements (PSAs) shown at the Riverview Theatre, located near the Mississippi River and Lakes Nokomis and Hiawatha. The PSAs focus on two main actions: getting pet owners to pick up after the dogs, and encouraging all property owners to stop or reduce their use of salt or chlorides. The PSAs had a simple message with images of the Mississippi River, Lake Nokomis, and Minnehaha Creek. The summer and fall message was to Protect the River, Protect the Lake, Protect the Creek: Grab a Bag and Scoop the Poop. For winter, the images featured winter scenes of the Mississippi River, Lake Nokomis, and dogs frolicking in the snow. The message here was to Protect the River, Protect the Lakes, Protect the Paws: Shovel, Don’t Salt. The word chloride was not used in the PSA because more people understood ice melt as salt. Detailed information about chlorides, their impacts, best practices for distribution was found on the Minneapolis Park & Recreation Board website www.minneapolisparks.org/dogs
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 28-3 Greening Teen Teamworks
Teen Teamworks is a summer youth employment program managed by the Minneapolis Park & Recreation Board for 30+ years. In 2017 Teen Teamworks hired and trained 150 youth to assist in park maintenance work for eight weeks. The Greening Teen Teamworks program, led by two MPRB Environmental Educators, meets weekly with all sites supervisor and youth to provide education on storm water runoff, water quality, and actions that should be taken to help keep our lakes, creeks, and river healthy. These site-based youth crews are charged with keeping the parks stormwater drains clear and curblines picked up, and at parks with waterbodies, the crews remove debris from outlets and tidy up shorelines.
All program participants complete a pre and post knowledge test. Teens participate in park-based education opportunities, demonstrating what they’ve learned about water quality to children and adults. By sharing their newfound knowledge, it reinforces water quality concepts. Post knowledge test results show that the teens - and their adult supervisors - increase their knowledge and understanding of water quality, watersheds, runoff, and the actions that should be taken to benefit our lakes, creeks, and river. In 2017 work sites included the following parks: Bottineau, Farview, Folwell, Martin Luther King Jr, North Commons, Pearl, Powderhorn, and Webber. The Greening Teen Teamworks program is funded by the Mississippi Watershed Management Organization.
Earth Day Watershed Clean-up
The Earth Day Watershed Clean-up was initiated in 1995 to draw attention to the water quality improvement needs of Minneapolis’ lakes, and the effects that individual actions have on urban water quality. The goals of the Earth Day Clean-Up event are to prevent trash and debris from entering Minneapolis water bodies, and to provide a volunteer experience and environmental education to Minneapolis residents and park users. This annual event occurs in Minneapolis parks and neighborhood areas that are part of the watersheds of Minneapolis water bodies, including the Chain of Lakes, Lake Nokomis, Lake Hiawatha, Powderhorn Lake, Diamond Lake, Shingle Creek, Minnehaha Creek, Bassett Creek, and the Mississippi River (Table 28-1).
The 2017 Minneapolis Earth Day Clean-Up Event was held at 38 sites throughout the City of Minneapolis. It is a collaborative effort between the Minneapolis Park & Recreation Board (MPRB) and City of Minneapolis Solid Waste and Recycling. More than 1800 volunteers collected an impressive 7,700 pounds of trash, recycling and metal. Hands-on learning activities were also provided throughout the day and focused on water quality, recycling, composting, and organic gardening and lawn care.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 28-4 Table 28-1. 2017 Earth Day Clean Up Sites.
SITE ADDRESS 29th Ave and Midtown Greenway 29th Ave and Midtown Greenway Bassett's Creek SE corner of Penn Ave. N. and 1 1/2 Ave. N Bde Maka Ska East Corner of W Lake St. & E Calhoun Pkwy Bde Maka Ska West W 32nd Street and Calhoun Parkway Beltrami Park 1111 Summer Street NE Boom Island 724 Sibley St. NE Bryant Square Park 3101 Bryant Ave S Cedar Lake Cedar Lake Pkwy & 25th St. W Columbia Columbia Pkwy & 35 Ave NE (playground parking lot) Creekview 5001 Humboldt Ave. N East River Pkwy E River Pkwy & Franklin Ave. Father Henn Bluff 100 6th Ave. SE Folwell Park 1615 N Dowling Ave Heritage Park/Sumner Field 10th Ave. N and Van White Memorial Parkway Kenny/Grass Lake 1328 58th St. W Kenwood 2101 Franklin Ave. W Lake Harriet 4135 Lake Harriet Parkway, Band Shell parking lot Lake Hiawatha 2701 E 44th St. Lake of the Isles East W 27th St and E Lake of the Isles Pkwy Longfellow Park 3435 36th Ave S Loring 1382 Willow Street Lynnhurst 1345 W Minnehaha Pkwy Mill Ruins 102 Portland Ave S, Minneapolis, MN 55401 Minnehaha Falls 4801 South Minnehaha Drive ML King 4055 Nicollet Ave. S Nokomis 2401 Minnehaha Pkwy. E Pearl 414 Diamond Lake Rd. E Powderhorn 3400 15th Ave. S Seward Towers West Cleaning up frontage road and 9th St. Sibley 1900 E 40th Street Theodore Wirth 3200 Glenwood Ave (Wirth Beach Parking lot) 10th Street between 4th and 5th Ave. between the in-bound and Triangle Park out-bound access ramps to 35W W River Pky 24th W River Parkway and 24th Street W River Pky 36th W River Pkwy & 36th W River Pky 44th W River Pkwy & 44th Waite Park 1810 34th Ave. NE (near playground off Garfield) Webber Park 4300 Webber Parkway Whittier 425 W 26th St.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 28-5 Mississippi River Green Team
The Mississippi River Green Team (Green Team) is a conservation-based teen crew engaged in daily hands-on environmental work throughout the summer. There are two crews of ten youth each, which work mostly in the natural areas of the Minneapolis park system, and within the watershed of the Mississippi River. Typical work days include invasive species removal, weed wrenching, planting, watering, mulching, and citizen science work. As part of weekly career exposure days, the crews learned about being an arborist with the Minneapolis Park & Recreation Board, a water quality specialist with the Mississippi Watershed Management Organization, a garden designer with MetroBlooms, a Forest Plant Ecologist and a Wildlife Biologist with the US Forest Service, and lots more. The Green Team also participated in the new Pollinator Ambassadors Program led by the University of Minnesota’s Bee Lab.
In 2017 the Green Team continued their work as citizen scientists for the Minnesota Dragonfly Society. Each week the teens caught and identified dragonflies at North Mississippi Regional Park. Dragonflies are an indicator species for assessing habitat and water quality in wetlands, riparian forests, and lakeshore habitats. You can read more about dragonfly survey work here: http://www.mndragonfly.org
The Mississippi River Green Team is made possible through a partnership between the Minneapolis Park & Recreation Board and the Mississippi Watershed Management Organization, with additional funding through the City of Minneapolis STEP-UP Youth Employment Program.
The Green Team is also supported by City of Minneapolis Public Works through their contract with Wetland Habitats Restoration (WHR), which manages vegetation at storm water BMPs throughout the city. WHR and the Green Team’s work in 2017 focused on weed and invasive species management at Heritage Park. The crew also toured the newly renovated Nicollet Mall to see the work WHR completed at this site.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 28-6 29. QUALITY ASSURANCE ASSESSMENT REPORT
BACKGROUND
Environmental monitoring and management requires the collection of highly reliable data. Data accepted for inclusion in a database must be of known quality and must meet established criteria. A Quality Assurance Program is a defined protocol for sample collection, handling, and analysis to ensure that the quality of the data collected is quantified and tracked. Quality Assurance consists of two components (Standard Methods, 2005):
• Quality Assessment (QA) Periodic evaluations of laboratory performance through the submission and analysis of externally provided blanks, standard solutions, duplicates, and split samples.
• Quality Control (QC) Documented operator competence, recovery of known additions, and analysis of internally provided reagent blanks, proper equipment calibration, and maintenance of control charts.
DESCRIPTION
This Quality Assurance Project Plan (QAPP) describes the procedures and quality control measures used for water quality monitoring and laboratory analyses completed in 2017 for the Minneapolis Chain of Lakes monitoring, the National Pollutant Discharge Elimination Systems (NPDES) stormwater monitoring, and other studies. The project activities for lake sampling are detailed in the Lake Monitoring Program Overview, Section 1. Stormwater monitoring procedures are explained in the Stormwater Monitoring Program Manual (MPRB, 2001).
QA/QC definitions, as presented by T.A. Dillaha, et al. (1988) and Standard Methods for the Examination of Water and Wastewater (2005), are used in the presentation of the information in this document.
• Precision is a measure of the degree of agreement between independent measurements of some property. Precision is concerned with the closeness of the results and is usually expressed in terms of the standard deviation of the data for duplicate or replicate analyses. Precision is a measure of how close the results are together with respect to each other not how close they are to a true value.
• Accuracy is a measure of the degree of agreement of a measured value with an accepted reference or true value. It is usually expressed in terms of percent recovery of the expected value (standard solution) and is an expression of the amount of bias in the data. Accuracy is a measure of how close the results are to a known true value.
• Representativeness is a measure of the degree to which data accurately and precisely represent the characteristics of the population which is being monitored.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-1 • Completeness is a measure of the amount of valid data obtained from a measurement system compared to the amount expected to be obtained under correct normal conditions. For example, a data set for a lake will not be complete if the laboratory did not analyze all expected parameters. Completeness is usually expressed as a percent of the true value.
• Comparability expresses the confidence with which one data set, measuring system, or piece of equipment can be compared with another. Data can be considered comparable if they are similar to those reported by others in the literature, data from previous years, and if the analysis procedures produce results similar to those reported by other laboratories for split samples.
The frequencies of quality assessment and quality control activities are set forth to ensure the validity of the database is listed in Table 29-1. The QA/QC plan follows the recommendations of Standard Methods for the Examination of Water and Wastewater (2005).
Table 29-1. Summary and frequency of QA/QC activities.
Sample type Description Function Frequency Reagent-grade de-ionized water Estimating background values End of sampling Equipment Blank subject to sample collection, due to sample collection, season processing and analysis processing and analysis Reagent-grade de-ionized water Estimating background values Bottle Blank/Field Blank subject to sample processing and due to sample processing and Each sampling trip analysis analysis; carried in the field Duplicate of lake sampling Estimating lab batch and Field Duplicate Each sampling trip procedures sampling procedure precision Blind QA/QC Audit Synthetic sample to mimic a Estimating overall batch Once/Month Standard natural sample precision and lab bias Laboratory Calibration Standard solution from a source Calibrate the instrument before One/lab batch (10% Standard other than the control standard samples are analyzed of samples)
Laboratory Calibration Identifying signal drift and One/lab batch (10% Reagent-grade de-ionized water Blank contamination of samples of samples) Laboratory Reagent Reagent-grade de-ionized water Identifying contamination of One/lab batch (10% Blank plus reagents reagents of samples) Determining accuracy and Laboratory Control Standard solution from a source One/lab batch (10% consistency of instrument Standard other than calibration standard of samples) calibration Split of lake sample sent to Once during Split Samples Determining comparability different laboratories for analysis sampling season Determining analytical precision 10% of samples (at Laboratory Duplicate Split of sample aliquot within batches least one per batch) Laboratory Matrix Known spike of sample (recovery Determining percent recovery of 10% of samples (at Spike/Matrix Spike of known additions) parameter analyzed least one per batch) Duplicate
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-2 OBJECTIVES
The primary objective of this QAPP is to ensure and identify the completeness, representativeness, precision, accuracy, and comparability of the data collected. The following pages summarize these data characteristics for results from both field measurements and parameters as analyzed by Instrumental Research Inc. (IRI) located in Fridley, MN. In 2017, metals analysis was performed by Pace Laboratories located in Minneapolis, MN.
This program was designed to clearly establish which data were: 1) usable, 2) of questionable usability and needed to be flagged, or 3) unusable. Quantitative data quality descriptions have been included to provide data users with background on why certain data were deemed to be questionable or unusable. This enables the data user to apply more or less stringent acceptance limits on defining usability to meet the objectives of their own analyses. Quantitative data quality indicators were calculated for each analysis method individually. To estimate quantitative data quality indicators on a method-by-method basis, all samples analyzed using a given method were treated as belonging to the same population (Fairless and Bates, 1989).
The QAPP set forth target frequencies for all QA/QC activities:
• Every sampling batch included analysis blanks, standards, and duplicates for each set of samples analyzed.
• Ten percent of all samples were run in duplicate.
• The fall sampling trip had equipment blanks associated with them.
• A bottle field blank was associated with every sampling trip.
• One laboratory reagent blank was analyzed for every ten samples run.
• Filter blanks were analyzed where appropriate.
• A matrix spike was analyzed with every ten samples.
Blind performance evaluation samples of known concentration were submitted monthly to the laboratory by the MPRB for analysis. The performance evaluation samples served as a quality assessment of monthly analytical runs. IRI used the following procedures during each analytical run:
• Blanks for water and reagents (one for each) were analyzed for every 10 samples run.
• A standard of known concentration was analyzed for each analytical run.
• One spike (recovery of known additions) was analyzed for every 10 samples run.
• One duplicate sample was analyzed for every 10 samples run, which included duplicate spikes.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-3 Additional quality control measures used in the contract laboratory were as follows:
• Control charts were maintained for all routinely measured parameters and analyses were not performed unless control (reference) samples fell within the specified acceptance limits see Table 29- 2.
• Experienced individuals trained technicians before they could conduct analyses by themselves and their supervisors routinely reviewed their performance.
Table 29-2. 2017 IRI analytical laboratory and Pace laboratory reporting limits (RL), the performance evaluation (PE) percent recovery acceptance limits, and relative percent difference (RPD) allowed with duplicates. NA = Not Applicable. MPN = most probable number. PE % Rec Duplicate Parameter Abbreviation IRI RL Pace RL Limits RPD Limits Alkalinity, Total Alk 2.0 mg/L NA 80-120 ±10% Arsenic, Total As NA 20 µg/L 80-120 ±10%
Ammonia, Un-ionized as N NH3 0.250 mg/L NA 80-120 ±10% BOD, 5 Day carbonacious cBOD 1.0 mg/L NA 80-120 ±10% Chloride, Total Cl 2.0 mg/L NA 80-120 ±10% Chlorophyll-a Chl-a 5 µg/L NA NA ±10% Conductivity Cond 10 µmhos/cm NA 80-120 ±10% Copper, Total Cu NA 1 µg/L 80-120 ±10% 1 MPN per Escherichia coli E. coli 100ml NA NA NA
Hardness, Total as CaCO3 Hard 2.0 mg/L NA 80-120 ±10% Iron Fe NA 50 80-120 ±10% Kjeldahl Nitrogen, Total TKN 0.500 mg/L NA 80-120 ±10% Lead, Total Pb NA 0.1 µg/L 80-120 ±10% NOx or Nitrite+Nitrate, Total as N NO2NO3 0.030 mg/L NA 80-120 ±10% Nitrogen, Total (persulfate) TN 0.500 mg/L NA 80-120 ±10% pH pH 1.00 Std Units NA 80-120 ±10% Phosphorus, Dissolved TDP 0.010 mg/L NA 80-120 ±10% Phosphorus, Total TP 0.010 mg/L NA 80-120 ±10% Silica, Reactive Si 0.500 mg/L NA NA ±10% Solids, Total Dissolved TDS 2.0 mg/L NA 80-120 ±10% Solids, Total Suspended TSS 1.0 mg/L NA 80-120 ±10% Solids, Volatile Suspended VSS 2.0 mg/L NA 80-120 ±10% Soluble Reactive Phosphorus SRP 0.003 mg/L NA 80-120 ±10%
Sulfate SO4 5.0 mg/L NA 80-120 ±10% Zinc, Total Zn NA 20 µg/L 80-120 ±10%
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-4 METHODS
Laboratory results and field data were entered into a spreadsheet. Data were evaluated to determine usability according to the methods below. Data were categorized into one of three levels of usability: fully usable, questionable usability, or unusable. To be fully usable the data had to meet all of the data quality criteria: completeness, representativeness, comparability, precision, and accuracy. Data rated as questionable usability met all but one of the quality criteria. Unusable data were those that were known to contain significant errors or data that met fewer than four of the data quality criteria.
Completeness
Data sets were deemed to be complete if fewer than 5% of the data were missing or not analyzed appropriately.
Representativeness
Data sets were deemed to be representative if samples were collected according to the sampling schedule and standard collection and handling methods were followed. Monitoring locations, frequencies, and methods followed suggested protocol to ensure representativeness (Wedepohl et al., 1990).
Comparability
Data for a given parameter were deemed to be highly comparable if the laboratory split results from all three labs for that parameter had a Coefficient of variation (CV) of less than 20% and if reported values were consistent with past results. If the CV between labs for a given parameter was more than 20%, but the majority of data reported were within 20%, the data set for that parameter was deemed to be moderately comparable.
Coefficient of Variation = standard deviation/mean.
Precision
Data sets were deemed precise if two criteria were met (Standard Methods, 2005):
1. The relative percent difference of results for each pair of duplicate analyses was within acceptance limits for each given parameter.
|푥 −푥 | Relative Percent Difference (RPD) = 1 2 × 100% (푥1+푥2)÷2
2. The percent recovery of known standard additions met the established acceptance limits for each parameter.
표푏푠푒푟푣푒푑 푣푎푙푢푒 = × 100% Percent Recovery (% Rec) 푒푥푝푒푐푡푒푑 푣푎푙푢푒
Precision was further quantified by calculating the average range and standard deviation of results for duplicates.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-5 ∑|푥 −푥 | 1 2 Average Range (R) = 푛
훴(푥−푥 푠푎푚푝푙푒 푚푒푎푛)2 푠 = √ Standard Deviation (estimated) 푛−1
Accuracy
Data sets were deemed accurate if the percent recovery reported for performance evaluation standards fell within the established acceptance limits for each given parameter and had been deemed precise (Table 29-2). The percent recovery estimates bias in the data set. Together, bias and precision reflect overall data set accuracy (Standard Methods, 2005). Low bias and high precision translates to high accuracy.
The standard solutions used for performance evaluation samples were manufactured by Environmental Resource Associates (ERA) located in Arvada, Colorado and diluted by MPRB staff to achieve the desired concentrations. ERA provided performance acceptance limits for the recovery of each analyte. These performance limits defined acceptable analytical results given the limitations of the United States Environmental Protection Agency (US EPA) approved and Standard Methods methodologies (US EPA Reports, 1979, 1980, 1985, 1986). The acceptance limits were based on data generated by laboratories in ERA's InterLab program and data from the US EPA and closely approximated the 95% confidence interval. If a laboratory failed a blind monthly performance standard all of the monthly data for that parameter were flagged as questionable. Laboratories were allowed ± 20% recovery for all parameters except soluble reactive phosphorus and total dissolved phosphorus data which were allowed ± 30% recovery due to the low phosphorus concentrations.
The contract laboratories provided minimum detection limits (MDL) and reporting limits (RL). The IRI laboratory calculated the MDL based upon documented performance studies and the RL are two to five times the MDL. Table 29-2 lists the reporting limits for analyses as provided by IRI.
RESULTS AND DISCUSSION
If the blind monthly performance standard failed to achieve the required percent recovery (±20%), the entire month’s data were flagged by underlining the data. There was a total of one data point flagged in 2017, the June sulfate sample.
Completeness
The data collected in 2017 was deemed to be complete. Missing data and improper analyses accounted for less than 1% of the samples collected. A minimum of 10% of the final data were checked by hand against the raw data sent by the laboratories to ensure there were no errors entering or transferring the data.
Representativeness
The 2017 lakes data were deemed to be representative of actual in-lake conditions. Samples were collected over the deepest point of each lake to create a profile at appropriate depths. The duration of monitoring, sampling frequency, site location, and depth intervals sampled met or exceeded the recommendations to collect representative data and to account for seasonal changes and natural variability (Wedepohl et al., 1990). Sample collection and handling followed established protocol for monitoring water quality as detailed in Standard Methods for the Examination of Water and
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-6 Wastewater (2005). NPDES stormwater samples were collected in accordance with the Stormwater Monitoring Program Manual (MPRB, 2001).
Comparability
Between Years
The 2017 lakes data were deemed to be comparable to previous years’ data. In reviewing box and whisker plots of total phosphorus, Secchi transparency, and chlorophyll-a data, reported values appeared to be consistent with values reported at the same times during the 2013 - 2016 monitoring seasons. The 2017 monitoring season was roughly comparable to the 2016 monitoring season. Stormwater data for 2017 appeared to be very comparable to other stormwater data, however, it should be noted that stormwater concentrations are highly variable.
Between Laboratories
To determine data comparability between laboratories lake samples were split in the field and shared with IRI, Minnehaha Creek Watershed District (MCWD), and Three Rivers Park District (TRPD). MCWD used RMB Environmental Laboratories, Detroit Lakes, MN as their laboratory and TRPD uses their own in-house laboratory. Data for a given parameter were deemed to be highly comparable if the laboratory split results for that parameter from all the laboratories had a coefficient of variation (CV) less than 20% and if reported values were consistent with past results. Generally, if the CV between laboratories for a given parameter was more than 20% then the data set for that parameter was deemed to be moderately comparable. If most of the parameters tested for the data set had a laboratory outlier the comparability was deemed low.
Care must be taken when interpreting these data at very low levels or near reporting limits. For example, the CV between 1 and 2 µg/L is 47%, but the CV between 10 and 11 µg/L is 7%. Both have a difference of 1 µg/L. The rule of sensibility was used to evaluate low level data and whether to flag it or not. The rule of sensibility is applying common sense to data interpretation. Low level samples less than 5 times the reporting limit, ± the reporting limit is used as an acceptable range. Samples greater than 5 times the reporting limit ± 20% of the CV is used as acceptable range. In Table 29-3 the SRP values reported below reporting limits did not have CV’s calculated if more than two laboratories were below reporting limits.
The MPRB shared round-robin format split samples with the participating laboratories from the sampling event on September 11th, 2017. The results from all agency split samples are summarized in Table 29-3 and in Figures 29-1 through 29-5. The 2017 lake split data set were deemed to be generally comparable to data analyzed by TRPD and MCWD, but there were issues with two SRP samples and one Cl sample, highlighted in red, and seen in Table 29-3.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-7 Table 29-3. Summary of 2017 split sample results reported by IRI, MCWD, and TRPD. CV = Coefficient of Variation. Split failures are written in red. ID Parameter Units Depth Lake MPRB MCWD TRPD CV 1 Chla mg/M3 0-2 Wirth 15.7 17.4 21.7 17% 2 Chla mg/M3 0 Med 40.9 57.4 59.5 19% 3 Chla mg/M3 0 LWS01 31.3 39.2 41.0 14% 4 TP mg/l 0-2 Wirth 0.027 0.019 0.027 19% 5 TP mg/l 7 Wirth 1.08 0.892 0.905 11% 6 TP mg/l 0 Med 0.081 0.075 0.085 6% 7 TP mg/l 12 Med 0.446 0.469 0.409 7% 8 TP mg/l 0 Reb 0.147 0.153 0.161 5% 9 TP mg/l 0 LWS01 0.072 0.061 0.072 9% 11 TP mg/l 10 LWS01 1.64 1.44 1.41 8% 12 SRP mg/l 0-2 Wirth 0.004 0.003 0.006 34% 13 SRP mg/l 7 Wirth 0.029 0.023 0.029 12% 14 SRP mg/l 0 Med 0.016 0.013 0.038 62% 15 SRP mg/l 12 Med 0.241 0.274 0.267 7% 16 SRP mg/l 0 Reb 0.109 0.112 0.109 2% 17 SRP mg/l 0 LWS01 0.006 0.003 0.002 53% 19 SRP mg/l 10 LWS01 0.068 0.012 0.007 117% 20 TN mg/l 0-2 Wirth 0.564 0.571 0.650 8% 21 TN mg/l 0 Med 1.09 1.04 1.09 3% 22 TN mg/l 0 Reb 1.31 1.61 1.15 17% 23 TN mg/l 0 LWS01 1.28 1.51 1.60 11% 24 Cl mg/l 0-2 Wirth 134 122 125 5% 25 Cl mg/l 7 Wirth 189 174 180 4% 26 Cl mg/l 0 Med 134 128 130 2% 27 Cl mg/l 12 Med 129 130 135 2% 28 Cl mg/l 0 Reb 10.6 33.1 12.0 68% 29 Cl mg/l 0 LWS01 25.4 26.4 26.0 2% 30 Cl mg/l 10 LWS01 26.8 28.2 28.0 3%
The comparability of the inter-laboratory split sample within each of the parameters differed considerably. Table 29-4 details the variability within parameters and lists the determined level of comparability for each. The comparability between years was determined by comparing 2017 values to previous year’s data. The final CV calculated for SRP should not be used if many are below or near detection limit values.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-8 Table 29-4. 2017 comparability of parameters analyzed as a part of the inter-laboratory split sample program and compared to previous years’ data. Values listed are the range and mean for the coefficient of variation between labs.
2017 CV Mean Comparability Parameter 2017 CV Range % Between labs Chl-a 14%-19% 17% High TP 5%-19% 9% High SRP 2%-117% 41% High TN 3%-17% 10% High Cl 2%-68% 12% High
The split samples for chlorophyll-a were moderately comparable as seen in Figure 29-1. All laboratories used a spectrophotometer. There were no outliers.
Chlorophyll-a concentrations can be extremely variable due to inherent sampling limitations and plankton patchiness as well as the difficulty in laboratory grinding and analysis. The average CV for chlorophyll-a was 17%.
Figure 29-1. Plot of chlorophyll-a split sample results reported for 2017. See Table 29-3 to reference ID numbers with sample descriptions and results.
Total phosphorus splits were moderately comparable as seen in Figure 29-2. Most of the samples were moderate to lower level concentrations but none were at the reporting limit. There were no outliers. Phosphorus is an important and limiting aquatic nutrient and accuracy for this element is critical. The average CV for TP was 9%.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-9
Figure 29-2. Scatter plot of total TP split sample results reported for 2017. See Table 29-3 to reference ID numbers with descriptions and results.
Two concentrations of the submitted SRP split samples were near lab reporting limits as seen in Figure 29-3. There was two outlier sample ID numbers 14 and 19 analyzed by TRPD and IRI respectively. IRI and MCWD (RMB laboratory) had a reporting limit of 0.003 mg/L, while TRPD has a reporting limit of 0.006 mg/L. The low level split SRP data must be deemed of questionable comparability especially at concentrations below 0.006 mg/L. Users of these data must decide if this loss of resolution at low concentrations is of significant concern for any given data application. The average CV for SRP was 41%.
Figure 29-3. Scatter plot of SRP split sample results reported for 2017. See Table 29-3 to reference sample ID numbers with descriptions and results.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-10 Total nitrogen (TN) splits were completed by IRI, TRPD, and MCWD as seen in Figure 29-4. The were no significant outliers for TN. TRPD and IRI perform a persulfate digestion and MCWD (RMB laboratory) performs a sum of the nitrogen species TKN and NO3NO2. The average CV for TN was 10%.
Figure 29-4. Scatter plot of TN split sample results reported for 2017. See Table 29-3 to reference ID numbers with descriptions and results.
Chloride splits were completed by IRI, TRPD, and MCWD as seen in Figure 29-5. There was only one significant outlier (sample ID number 28) analyzed by MCWD. This sample was not a true field split but a standard made by TRPD. Chloride is an extremely stable test and there is generally little variability between laboratories. The average CV for chloride was 12%.
Figure 29-5. Scatter plot of Cl split sample results reported for 2017. See Table 29-3 to reference ID numbers with descriptions and results.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-11 Historically the split data has shown the MPRB laboratory (IRI) as a consistently low outlier in the Chl-a split samples. The issue of IRI Chl-a samples being outliers seems to be resolved. The TRPD and MPRB each had a SRP outlier (14 and 19 respectively). The MCWD had a Cl outlier (28). The data sets appear moderately comparable since two parameters had at least one outlier. Depending on the parameter, 2017 saw less scatter among the splits than in 2016.
Precision
The first criterion used for assessing data precision was the relative percent difference (RPD) between duplicates. For reporting and calculation purposes, the average of duplicate samples was used.
Field Duplicates
Field duplicates test the reproducibility of field methods and lake uniformity. Table 29-5 summarizes the results from field duplicate samples in 2017. Significant differences between duplicates was defined as having a RPD greater than 20%. The goal is to have the average RPD for parameters to be 10% or less. When values are near the reporting limit the RPD calculations are skewed but most times the data are considered acceptable.
The difference in some samples may also be the result of lake or pond sediment being disturbed by a boat anchor, water sampling device such as the Kemmerer sampler, or particles in the epilimnion. Further investigation should consider any cause(s). Low values, for example, of 0.003 and 0.004 with a RPD of 29% should not be considered a true duplicate failure but rather a statistical anomaly.
Table 29-5. 2017 summary of field duplicate sample results and acceptability for IRI Laboratory.
Average Relative % Std. Dev. Parameter Units Difference Average Range (estimated) Acceptable Chl-a µg/L 7.6 26.5 23.5 Yes Silica mg/L 4.5 0.7 0.6 Yes TP mg/L 5.7 0.8 0.7 Yes SRP mg/L 8.9 0.4 0.3 Yes TKN mg/L 0.9 0.0 0.0 Yes TN mg/L 5.5 1.0 0.9 Yes
NO2NO3 mg/L 3.4 0.0 0.0 Yes Alk mg/L 0.6 6.0 5.3 Yes Hard mg/L 3.4 24.0 21.3 Yes Cl mg/L 2.9 122.6 108.6 Yes Sulfate mg/L 3.6 4.1 3.6 Yes NH3 mg/L 5.4 0.1 0.1 Yes
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-12 Lab Duplicates
IRI reported all internal QA/QC results to the MPRB. The reported RPD values for duplicate analyses were within acceptance limits. All duplicate analyses were deemed acceptable.
Performance Evaluation Samples
The second criterion for assessing data precision was percent recovery of performance evaluation samples. Performance evaluation standards were purchased from ERA. MPRB water resources staff used prepared standards mixed to concentrations similar to those being measured in the field for submission to the contract laboratory. Table 29-6 and Figures 29-6 through 29-19 summarize the performance evaluation sample results for each parameter. Of the 2017 performance parameters tested June SO4 fell outside the recovery limits, and all the June SO4 samples were flagged. All other performance evaluation samples fell within acceptance limits.
The historically low IRI Chl-a split recovery persisted in 2017. There is no official chlorophyll-a calibration standard. The MRPB submitted a sample from Turner Instruments with a concentration determined by High Pressure Liquid Chromatography (HPLC) for analysis. The IRI spectrophotometer absorbance fell within the acceptable range provided by Turner Instruments.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-13 Table 29-6. Performance evaluation samples analyzed by IRI in 2017. Sample IRI % ID Parameter Date Calc. Value Value Recovery 1 Alk 1/26/2017 50.3 45.0 89% 2 Alk 4/18/2017 44.6 43.0 96% 3 Alk 5/11/2017 108 107 99% 4 Alk 6/14/2017 107 107 100% 5 Alk 7/11/2017 108 109 101% 6 Alk 8/8/2017 40.1 40.0 100% 7 Alk 9/21/2017 77.7 77.0 99% 8 Alk 10/24/2017 30.9 30.0 97% 9 BOD5C 1/26/2017 13.4 13.1 98% 10 BOD5C 4/18/2017 13.4 14.2 106% 11 BOD5C 5/11/2017 13.4 11.4 85% 12 BOD5C 6/14/2017 10.4 10.0 96% 13 BOD5C 7/11/2017 10.4 10.5 101% 14 BOD5C 8/8/2017 10.4 10.7 103% 15 BOD5C 9/21/2017 10.4 10.5 101% 16 BOD5C 10/24/2017 10.4 10.6 102% 17 Cl 1/26/2017 70.2 65.2 93% 18 Cl 4/18/2017 108 102 94% 19 Cl 5/11/2017 44.3 46.5 105% 20 Cl 6/14/2017 67.6 72.4 107% 21 Cl 7/11/2017 44.3 43.5 98% 22 Cl 8/8/2017 71.1 67.2 95% 23 Cl 9/21/2017 38.0 39.2 103% 24 Cl 10/24/2017 87.1 84.0 96% 25 Cond 1/26/2017 422 455 108% 26 Cond 4/18/2017 462 466 101% 27 Cond 5/11/2017 358 371 104% 28 Cond 6/14/2017 453 468 103% 29 Cond 7/11/2017 358 343 96% 30 Cond 8/8/2017 351 334 95% 31 Cond 9/21/2017 295 283 96% 32 Cond 10/24/2017 474 497 105%
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-14 Table 29-6. (continued) Performance evaluation samples analyzed by IRI in 2017. Sample IRI % ID Parameter Date Calc. Value Value Recovery 33 Cu 1/26/2017 74.4 79.0 106% 34 Cu 4/18/2017 74.4 78.2 105% 35 Cu 5/11/2017 74.4 78.2 105% 36 Cu 6/14/2017 174 172 99% 37 Cu 7/11/2017 172 189 110% 38 Cu 8/8/2017 172 176 103% 39 Cu 9/21/2017 172 182 106% 40 Cu 10/24/2017 172 169 98% Ecoli - 518 (283- 41 Quarterly 4/18/2017 1140) 686.7 100% Ecoli - 42 Quarterly 4/18/2017 <1 <1 100% Ecoli - 1280 (493- 43 Quarterly 7/11/2017 3320) 1986 100% Ecoli - 44 Quarterly 7/11/2017 <1 <1 100% Ecoli - 445 (150- 45 Quarterly 9/21/2017 1320) 921 100% Ecoli - 46 Quarterly 9/21/2017 <1 <1 100% 47 NH3 1/26/2017 1.61 1.56 97% 48 NH3 4/18/2017 1.61 1.63 101% 49 NH3 5/11/2017 1.61 1.62 101% 50 NH3 6/14/2017 3.42 3.49 102% 51 NH3 7/11/2017 3.42 3.37 99% 52 NH3 8/8/2017 3.42 3.17 93% 53 NH3 9/21/2017 3.42 3.46 101% 54 NH3 10/24/2017 3.42 3.45 101% 55 Nox 1/26/2017 0.722 0.720 100% 56 Nox 4/18/2017 0.722 0.716 99% 57 Nox 5/11/2017 0.722 0.706 98% 58 Nox 6/14/2017 1.06 0.916 87% 59 Nox 7/11/2017 1.06 1.02 97% 60 Nox 8/8/2017 1.06 1.05 99% 61 Nox 9/21/2017 1.06 1.04 98% 62 Nox 10/24/2017 1.06 0.982 93%
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-15 Table 29-6. (continued) Performance evaluation samples analyzed by IRI in 2017. Results in red are outside acceptance limits. Sample IRI % ID Parameter Date Calc. Value Value Recovery 63 Ortho P 7/11/2017 0.017 0.019 115% 64 Ortho -P 1/26/2017 0.019 0.021 108% 65 Ortho-p 4/18/2017 0.019 0.018 93% 66 Ortho-p 5/11/2017 0.019 0.016 82% 67 Ortho-P 6/14/2017 0.017 0.017 103% 68 Ortho-P 8/8/2017 0.017 0.020 121% 69 Ortho-P 9/21/2017 0.017 0.018 109% 70 Ortho-P 10/24/2017 0.017 0.017 103% 71 Pb 1/26/2017 17.0 17.2 101% 72 Pb 4/18/2017 17.0 17.7 104% 73 Pb 5/11/2017 17.0 17.8 105% 74 Pb 6/14/2017 22.2 20.2 91% 75 Pb 7/11/2017 20.2 21.8 108% 76 Pb 8/8/2017 20.2 21.8 108% 77 Pb 9/21/2017 20.2 20.9 104% 78 Pb 10/24/2017 20.2 19.8 98% 79 SO4 1/26/2017 38.1 36.5 96% 80 SO4 4/18/2017 7.89 6.92 88% 81 SO4 5/11/2017 10.7 8.54 80% 82 SO4 6/14/2017 11.0 13.4 122% 83 SO4 7/11/2017 10.7 8.64 81% 84 SO4 8/8/2017 12.2 11.1 91% 85 SO4 9/21/2017 10.9 8.75 80% 86 SO4 10/24/2017 46.0 46.9 102% 87 SRP 1/26/2017 0.019 0.021 108% 88 SRP 4/18/2017 0.019 0.018 93% 89 SRP 5/11/2017 0.019 0.017 87% 90 SRP 6/14/2017 0.017 0.018 109% 91 SRP 7/11/2017 0.017 0.018 109% 92 SRP 8/8/2017 0.017 0.019 115% 93 SRP 9/21/2017 0.017 0.017 103% 94 SRP 10/24/2017 0.017 0.017 103%
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-16 Table 29-6. (continued) Performance evaluation samples analyzed by IRI in 2017. Sample IRI % ID Parameter Date Calc. Value Value Recovery 95 TDP 1/26/2017 0.019 0.020 103% 96 TDP 4/18/2017 0.019 0.021 108% 97 TDP 5/11/2017 0.019 0.023 118% 98 TDP 6/14/2017 0.017 0.018 109% 99 TDP 7/11/2017 0.017 0.021 127% 100 TDP 8/8/2017 0.017 0.018 109% 101 TDP 9/21/2017 0.017 0.020 121% 102 TDP 10/24/2017 0.017 0.019 115% 103 TDS 1/26/2017 291 271 93% 104 TDS 4/18/2017 296 289 98% 105 TDS 5/11/2017 336 343 102% 106 TDS 6/14/2017 369 396 107% 107 TDS 7/11/2017 336 336 100% 108 TDS 8/8/2017 225 226 100% 109 TDS 9/21/2017 254 241 95% 110 TDS 10/24/2017 287 294 102% 111 TKN 1/26/2017 1.96 1.88 96% 112 TKN 4/18/2017 1.96 1.86 95% 113 TKN 5/11/2017 1.96 2.02 103% 114 TKN 6/14/2017 1.89 1.69 90% 115 TKN 7/11/2017 1.89 1.80 95% 116 TKN 8/8/2017 1.89 1.70 90% 117 TKN 9/21/2017 1.89 1.77 94% 118 TKN 10/24/2017 1.87 1.74 93% 119 TN 1/26/2017 1.96 2.00 102% 120 TN 4/18/2017 1.96 2.00 102% 121 TN 5/11/2017 1.96 1.80 92% 122 TN 6/14/2017 1.89 1.93 102% 123 TN 7/11/2017 1.89 1.89 100% 124 TN 8/8/2017 1.89 2.10 111% 125 TN 9/21/2017 1.89 1.98 105% 126 TN 10/24/2017 1.87 1.85 99%
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-17 Table 29-6. (continued) Performance evaluation samples analyzed by IRI in 2017. Sample IRI % ID Parameter Date Calc. Value Value Recovery 127 Total Hardness 1/26/2017 332 316 95% 128 Total Hardness 4/18/2017 250 244 98% 129 Total Hardness 5/11/2017 174 164 94% 130 Total Hardness 6/14/2017 280 268 96% 131 Total Hardness 7/11/2017 220 204 93% 132 Total Hardness 8/8/2017 250 240 96% 133 Total Hardness 9/21/2017 213 200 94% 134 Total Hardness 10/24/2017 173 160 92% 135 TP01 1/26/2017 0.058 0.060 103% 136 TP01 4/18/2017 0.058 0.065 111% 137 TP01 5/11/2017 0.058 0.058 99% 138 TP01 6/14/2017 0.042 0.042 101% 139 TP01 7/11/2017 0.042 0.044 106% 140 TP01 8/8/2017 0.042 0.044 106% 141 TP01 9/21/2017 0.042 0.043 103% 142 TP01 10/24/2017 0.042 0.043 103% 143 TP02 1/26/2017 1.17 1.13 97% 144 TP02 4/18/2017 1.17 1.18 101% 145 TP02 5/11/2017 1.17 1.16 99% 146 TP02 6/14/2017 0.832 0.796 96% 147 TP02 7/11/2017 0.832 0.797 96% 148 TP02 8/8/2017 0.832 0.811 97% 149 TP02 9/21/2017 0.832 0.823 99% 150 TP02 10/24/2017 0.832 0.810 97% 151 TSS 1/26/2017 68.7 62.7 91% 152 TSS 4/18/2017 58.1 53.0 91% 153 TSS 5/11/2017 43.5 42.7 98% 154 TSS 6/14/2017 79.0 66.0 84% 155 TSS 7/11/2017 48.7 39.3 81% 156 TSS 8/8/2017 58.1 47.3 81% 157 TSS 9/21/2017 84.6 76.7 91% 158 TSS 10/24/2017 60.8 57.3 94%
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-18 Table 29-6. (continued) Performance evaluation samples analyzed by IRI in 2017. Sample IRI % ID Parameter Date Calc. Value Value Recovery 159 Zn 1/26/2017 108 109 101% 160 Zn 4/18/2017 108 108 100% 161 Zn 5/11/2017 108 108 100% 162 Zn 6/14/2017 598 592 99% 163 Zn 7/11/2017 592 594 100% 164 Zn 8/8/2017 592 631 107% 165 Zn 9/21/2017 592 616 104% 166 Zn 10/24/2017 592 619 105%
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-19
Figure 29-6. Scatter plot of reported percent recoveries for performance evaluation samples in 2017. See Table 29-6 to reference ID numbers with descriptions and results.
Figure 29-7. Scatter plot of reported percent recoveries for performance evaluation samples in 2017. See Table 29-6 to reference ID numbers with descriptions and results.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-20
Figure 29-8. Scatter plot of reported percent recoveries for performance evaluation samples in 2017. See Table 29-6 to reference ID numbers with descriptions and results.
Figure 29-9. Scatter plot of reported percent recoveries for performance evaluation samples in 2017. See Table 29-6 to reference ID numbers with descriptions and results.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-21 Most of the performance evaluation standards were acceptable for all months. Alkalinity, chloride, hardness, pH, TDS, and TSS are pre-made and are the only standards that do not require dilution. The remaining standards were diluted before they were submitted to the lab.
All E. coli standards were acceptable. The performance acceptance limits for E. coli supplied by ERA are much wider than for the other parameters, (+/- 50%). The coliform standards are shipped directly to the (MPRB laboratory) IRI from ERA.
Ortho, SRP and TDP performance evaluation samples were mixed to low concentrations approximately 10-20 times the minimum detection limit. Standard Methods (2005) recommends that performance evaluation samples be mixed to a minimum concentration of 5 times the minimum detection limit. Because of the low concentrations the acceptance limit for Ortho-P, SRP, and TDP were historically widened from the recommended 80-120% range to 70-130% recovery. All Ortho, SRP, and TDP samples were acceptable in both the 80-120% and 70-130% range.
The June SO4 blind monthly performance samples were flagged as failing for that month with 122% recovery.
Analysis of Equipment Blanks and Field Blanks
Equipment blanks were run for both lake water and stormwater sampling equipment. Results from lake equipment blanks for 2017 yielded non-detects for all parameters. The stormwater equipment detected a small amount of Cu (3.1 µg/L) and Zn (0.13 µg/L). These metals samples were rerun and confirmed. Since these metals values were so small they were simply noted and not subtracted from the final stormwater values. The 2017 results from the bottle/field blanks which were carried in the field unopened yielded non-detects for all parameters. Reagent blanks run by IRI laboratories during batch analyses resulted in no detectable levels for all parameters analyzed.
Recovery of Known Additions and Internally Supplied Standard Solutions
All recovery values for spike samples (known additions) reported by IRI were within acceptance limits. All reported recoveries for internally supplied standards of known concentration were within acceptance limits.
FINAL ASSESSMENT OF DATA USABILITY
Table 29-7 lists the overall completeness, representativeness, comparability, and precision determined for the 2017 data by parameter. All additional parameters not analyzed by IRI and collected in the field (dissolved oxygen, temperature, conductivity, pH, and Secchi transparency) were deemed to be fully usable. These measurements followed standard methods and protocols for collection and daily equipment calibration.
The 2017 data designated as questionable usability may still meet the data quality needs of some analyses. Users of these data should assess if the data quality indicators discussed in this document meet their needs. Much of the data designated as questionably usable are categorized as such because of a missed performance evaluation standard or split samples with low comparability.
The parameters listed on Table 29-7 as questionably usable are only so for the months that they failed monthly performance standards or for split comparability. No parameters in 2017 failed performance standards for every month. When reviewing the monthly performance and split samples, the rule of sensibility must be applied, and the percent recovery must be viewed in relation to the recovery
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-22 values (low or high), stability of the test, and the multiple of the detection limit to create the reporting limit used for the data.
Table 29-7. Summary of 2017 data usability by parameter. Fully denotes that acceptance criteria were met, questionably denotes that some of the data were of questionable usability, and not denotes data were not within acceptable range.
Completeness Representativeness Precision Comparability Parameter (<5% missing (representative of (lab field dups, (splits, 2017 data) data) natural samples) performance) Alkalinity fully fully fully fully Ammonia fully fully fully fully BOD 5 day fully fully fully fully Conductivity fully fully fully fully Chloride fully fully fully fully Chlorophyll-a fully fully questionably fully Copper fully fully fully fully E. coli fully fully fully fully Hardness fully fully fully fully Iron fully fully fully fully Lead fully fully fully fully Nitrate+Nitrite fully fully fully fully Ortho-P fully fully fully fully pH fully fully fully fully Silica fully fully fully fully Soluble Reactive Phosphorus fully fully fully fully Sulfate fully fully fully questionably Total Dissolved Phosphorus fully fully fully fully Total Dissolved Solids fully fully fully fully Total Kjeldahl Nitrogen fully fully fully fully Total Nitrogen fully fully fully fully Total Phosphorus fully fully fully fully Total Suspended Solids fully fully fully fully Zinc fully fully fully fully
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 29-23 30. ADDITIONAL SOURCES OF WATER QUALITY INFORMATION
Minneapolis Park and Recreation Board
Water Quality Homepage https://www.minneapolisparks.org/park_care__improvements/water_resources 612.230.6400
City of Minneapolis
Storm and Surface Water Management Website http://www.ci.minneapolis.mn.us/stormwater/
Minneapolis Surface Water Management Plan http://www.minneapolismn.gov/publicworks/stormwater/stormwater_local-surface
Results Minneapolis Lake water quality http://www.minneapolismn.gov/coordinator/strategicplanning/citygoalresults
Watershed Management Organizations
Bassett Creek Watershed Management Commission http://www.bassettcreekwmo.org/
Minnehaha Creek Watershed District http://www.minnehahacreek.org/
Mississippi Watershed Management Organization http://www.mwmo.org/
Shingle Creek Watershed Management Commission http://www.shinglecreek.org/
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 30-1 Hennepin County or Metro Resources
Hennepin County Environmental Services https://www.hennepin.us/residents#environment
Hennepin County Wetland Health Evaluation Project (WHEP) https://www.hennepin.us/your-government/get-involved/wetland-health-evaluation-program
Hennepin County Public Beaches https://www.hennepin.us/residents/health-medical/public-swim-beaches
Metropolitan Council – Environmental Services https://metrocouncil.org/Wastewater-Water/Services/Water-Quality-Management.aspx
State of Minnesota Resources
Minnesota Department of Natural Resources Information on lake surveys, maps, fish stocking, fish advisories and more. http://www.dnr.state.mn.us/lakefind/
Aquatic Invasive Species http://www.dnr.state.mn.us/invasives/index_aquatic.html
Minnesota Pollution Control Agency Information on environmental monitoring, clean-up, and more. https://www.pca.state.mn.us/
Minnesota Department of Health http://www.health.state.mn.us/
Minnesota Lake Superior Beach Monitoring Program http://www.mnbeaches.org
Minnesota Department of Agriculture – Water https://www.mda.state.mn.us/protecting/waterprotection
Minnesota Extension Service http://www.extension.umn.edu/
Minnesota Sea Grant http://www.seagrant.umn.edu
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 30-2 US Federal Government
US Army Corps of Engineers St. Paul District https://www.mvp.usace.army.mil/
US Geological Survey – Minnesota Stream data and links to the national website http://mn.water.usgs.gov/
US Geological Survey – Nonindigenous Aquatic Species Information and maps of invasive aquatic plants and animals http://nas.er.usgs.gov/default.aspx
Environmental Protection Agency https://www.epa.gov/environmental-topics/water-topics
Environmental Protection Agency Healthy Beaches https://www.epa.gov/beaches/learn-human-health-beach
Other Resources
Minnesota Climatology Working Group http://climate.umn.edu/
Ice On/Out Information From Environment Canada https://www.naturewatch.ca/icewatch/
Midwest Invasive Plant Network http://www.mipn.org
Minnesota Invasive Species Advisory Council http://www.mda.state.mn.us/misac/
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 30-3 31. REFERENCES
Balaban, N.H. (Ed.). (1989). Geologic atlas Hennepin County, Minnesota. Minnesota Geologic Survey Atlas C-4.
Bannerman, R.T., R. Dodds, Hornewer, N.J., & Owens, D.W. (1993). Sources of pollutants in Wisconsin stormwater. Water Science Technology. 28(3-5), 241-259.
Barr Engineering Company. (2010). Wirth Lake Excess Nutrients Total Maximum Daily Load Report. Prepared for the Minnesota Pollution Control Agency
Blue Water Commission. (1998). Report and recommendations for the management of Lake Nokomis and Lake Hiawatha.
Borman, S., Korth, R., & Temte, J. (1997). Through the Looking Glass…A Field Guide to Aquatic Plants. Wisconsin Lakes Partnership. Stevens Point, WI. 248 pages.
Brugam, R.B., Speziale, B.J. (1983). Human Disturbance and the paleolimnological record of change in the zooplankton community of Lake Harriet, Minnesota. Ecology. 64(3), 578-591.
Byappanahalli, Muruleedhara, Fowler, M., Shively, D., & Whitman, R. (2003). Ubiquity and persistence of Escherichia coli in a midwestern coastal stream. Applied and Environmental Microbiology. 69(8), 4549-4555.
Byappanahalli, M. N., Sawdey M., Ishii S., Shively, D., Ferguson J., Whitman, R., & Sadowsky, M. (2009). Seasonal stability of Cladophora-associated Salmonella in Lake Michigan watersheds. Water Research. 43(3), 806-814.
Carlson, R.E. (1977). A trophic state index for lakes. Limnology and Oceangraphy. 22, 361-369.
Center for Watershed Protection (CWP) and the Maryland Department of the Environment. (2000). 2000 Maryland stormwater design manual, Volumes I & II. http://www.mde.state.md.us/Programs/WaterPrograms/SedimentandStormwater/stormwater_ design/index.asp
City of Minneapolis, Public Works Department. (1992, November 16). NPDES permit application for discharges from municipal separate storm sewer systems, Part 2. Minneapolis, MN.
Dillaha, T.A., Eddleton, C.D., McClellan, P.W., & Mostaghimi, S. (1988). Quality control/quality assurance for water quality monitoring. American Society of Civil Engineers Meeting presentation 88-2648, Chicago, IL.
European Union. (2006). Directive 2006/7/EC of the European Parliament and the council of 15 February 2006 concerning the management of bathing water quality and repealing Directive 75/160/EEC
Eydeler, I. & Spieker, J. (2010). Keimelimination durch zooplankton. Archiv des Badewesens. 1-9.
Fairless, B.J., & D.I. Bates. (1989). Estimating the quality of environmental data. Pollution Engineering. March, 108-111.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 31-1 Fassett, N. C. (1957). A Manual of Aquatic Plants. The University of Wisconsin Press. Madison, WI. 405 pages.
Fink, D.F. (1994). A Guide to Aquatic Plants: Identification and Management. Minnesota Department of Natural Resources. Ecological and Water Resources Division. St. Paul, MN. 52 pages.
FLL. (2011). Recommendations for Planning, Construction, Servicing and Operation of Outdoor Swimming Pools with Biological Water Purification (Swimming and Bathing Ponds); Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e. V. (FLL; Landscaping and Landscape Development Research Society) Friedensplatz 4, 2nd edition (german version 2011), download edition, 2013; 1st edition (as "Recommendations for Planning, Construction, Servicing and Operation of Public Swimming and Bathing Ponds), 2006
Genthner, F.J., Friedman, S.D., James, J.B., & Yates, D.F. (2005). Use of composite data sets for source-tracking enterococci in the water column and shoreline interstitial waters on Pensacola Beach, Florida. Marine Pollution Bulletin, 50, 724-732.
Gernes, M. (2002). Vegetation Method for Wetland Evaluation
Ha Kim, J. & Grant, S.B. (2004). Public mis-notification of coastal water quality: A probabilistic evaluation of posting errors at Huntington Beach, California. Environmental Science and Technology, 38(9), 2497-2504.
Heiskary, S.A., E.B. Swain, & M.B. Edlund. (2004). Reconstructing historical water quality in Minnesota lakes from fossil diatoms. Environmental Bulletin Number 4. St. Paul, MN: Minnesota Pollution Control Agency, Environmental Outcomes Division.
Huser, B.J. (2005). Phosphorus sorption by sediments in eutrophic and acidic lakes. (Unpublished doctoral dissertation) University of Minnesota, Minneapolis.
Ishii, Satoshi, W.B. Ksoll, R.E. Hicks, & M.J. Sadowski. (2005). Presence and growth of naturalized Escherichia coli in temperate soils from Lake Superior watersheds. Applied and Environmental Microbiology. 72(1), 612-621.
Ishii, Satoshi, D.L. Hanson, R.E. Hicks, & M.J. Sadowski. (2007). Beach sand and sediments are temporal sinks and sources of Esherichia coli in Lake Superior. Environmental Science and Technology. 41(7), 2203-2209.
Klak, G.E. (1933). A comparative study of summer phytoplankton from 22 bodies of water in the vicinity of Minneapolis and St. Paul, MN. Unpublished master’s thesis, University of Minnesota, Minneapolis.
Lee, J.T., & J.R. Jontz. (1997). An overview of the monitoring plan and water quality of Minneapolis lakes. 1991-1996. In: E. Derby, J. Lee and D. Pilger (Eds.) Minneapolis Lakes and Parks— Special Session Proceedings, 1997. Sixteenth Annual North American Lake Management Society International Symposium, Minneapolis, MN.
Madsen, J. (1999). Point Intercept and Line Intercept Methods for Aquatic Plant Management. APCRP Technical Notes Collection (TN APCRP-MI-02). U.S. Army Engineer Center, Vicksburg, M.S., U.S.A
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 31-2 Magnuson, J. J., D. M. Robertson, B. J. Benson, R. H. Wynne, D. M. Livingstone, T. Arai, R. A. Assel, R. G. Barry, V. Card, E. Kuusisto, N. G. Granin, T. D. Prowse, K. M. Stewart and V. S. Vuglinski (2000) Historical trends in lake and river ice cover in the Northern Hemisphere. Science, 289, 1743-1746.
Metropolitan Council. (2015). ANNUAL USE ESTIMATE OF THE METROPOLITAN REGIONAL PARKS SYSTEM FOR 2014. St. Paul, MN. https://metrocouncil.org/Parks/Publications-And-Resources/PARK-USE-REPORTS/2014- Annual-Use-Estimate-of-the-Regional-Parks-Sys.aspx
MPRB. (1999). Powderhorn Lake Restoration Project. MPRB documents, 80pp.
MPRB. (2001). Stormwater monitoring program manual. Minneapolis, MN: Minneapolis Park and Recreation Board, Environmental Operations Section, Water Quality.
MPRB. (2004). Minneapolis lakes recreation/aesthetic indicator development. Minneapolis, MN: Minneapolis Park and Recreation Board, Environmental Operations Section, Water Quality.
Minnehaha Creek Watershed District. (2013). Lake Nokomis Water Quality Improvement Project: Implementation of Biomanipulation Study. Author: Kelly Dooley.
Minnesota Department of Health (MDH). (2017). Waterborne Illness Surveillance Statistics. Retrieved February 20, 2018, from http://www.health.state.mn.us/divs/idepc/dtopics/waterborne/statistics.html#illness
Minnesota Department of Natural Resources. (1953). Diamond Lake survey report.
Minnesota Department of Natural Resources. (n.d.). Aquatic Invasive Species in Minnesota. Retrieved March 3, 2015, from http://www.dnr.state.mn.us/invasives/aquatic/index.html
Minnesota Pollution Control Agency (MPCA). (2000). Protecting water quality in urban areas: Best management practices for dealing with stormwater runoff from urban, suburban and developing areas of Minnesota. St. Paul, MN: Author.
Minnesota Pollution Control Agency (MPCA). (2004). Lake water quality assessment data base summary. St. Paul, MN: Author.
Minnesota Pollution Control Agency and Minnehaha Creek Watershed District. (2011). Minnehaha Creek Watershed Lakes TMDL: Lake Nokomis, Parley Lake, Lake Virginia, and Wassermann Lake. Prepared by Emmons & Olivier Resources, Inc.
Minnesota Pollution Control Agency. (2014). Guidance Manual for Assessing the Quality of Minnesota Surface Waters for Determination of Impairment: 305(b) Report and 303(d) List. Retrieved from http://www.pca.state.mn.us/index.php/view-document.html?gid=16988
Paerl, H. W. (1998). Growth and reproductive strategies of freshwater Blue-green algae (Cyanobacteria). In C.D. Sandgren (Ed.) Growth and Reproductive Strategies of Freshwater Phytoplankton (pp. 261-315). Cambridge, MA: Cambridge University Press.
Perleberg, D., P. Radomski, S. Simon, K. Carlson, and J. Knopik. 2016. Minnesota Lake Plant Survey Manual, for use by MNDNR Fisheries Section and EWR Lake Habitat Program. Minnesota
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 31-3 Department of Natural Resources. Ecological and Water Resources Division. Brainerd, MN. 128 pages including Appendices A-E.
Pulscher, M.L. (1997). History of Minneapolis parks and lakes. In: Minneapolis Lakes and Parks - Special Session Proceedings. Sixteenth Annual North American Lakes Management Society International Symposium. Minneapolis, MN.
Shapiro, J., & H. O. Pfannkuch. (1973). The Minneapolis chain of lakes, a study of urban drainage and its effects. Interim Rept. No. 9, Limnological Research Center, Univ. Minnesota, Minneapolis, 250 p.
Shapiro, J. (1975). Report to the City of Minneapolis Park and Recreation Board on the Condition of Lakes in Minneapolis, 1974. Limnological Research Center, Interim Report No 12. Minneapolis, MN.
Shingle Creek Watershed Management Commission. (2014). Twin and Ryan Lakes Nutrient TMDL Five Year Review. Prepared by Wenk Associates Inc.
Standard Methods for the Examination of Water and Wastewater. (2005). Joint Editorial Board, American Public Health Association, American Water Works Association, Water Environment Fed., 21st ed. Washington, DC.
Swain, E.B. (1984). The paucity of blue-green algae in meromictic Brownie Lake: iron limitation or heavy-metal toxicity? Unpublished doctoral dissertation, University of Minnesota, Minneapolis.
Trembley, N. G. (2012). The Changing Face of Cedar Lake: 1900–1918. (Unpublished master’s thesis). University of Minnesota, Minneapolis, 131 p.
US Army Corps of Engineers and PCA. (2014). FLUX32 [computer model] Retrieved from https://www.pca.state.mn.us/wplmn/flux32
US EPA. (1979). Methods for chemical analysis of water and waste, US EPA Environmental Monitoring and Support Laboratory. Cincinnati, OH.
US EPA. (1980). Interim guidelines and specifications for preparing quality assurance project plans. QAMS-005/80. Office of Research and Development, Washington, D.C.
US EPA. (1985). Working protocol for sampling, sample analysis, and QA/QC for the EPA long-term surface water monitoring program. Corvallis, OR: Environmental Research Laboratory.
US EPA. (1986). Ambient water quality criteria for bacteria – 1986 (EPA Publication No. EPA440/5- 84-002). Washington, DC: Office of Water.
US EPA. (1996). Protecting natural wetlands: A guide to stormwater best management practices (EPA Publication No. EPA-843-B-96-001). Washington, DC: Office of Water.
US EPA. (2005). The EMPACT beaches project: Results from a study on microbiological monitoring in recreational waters (EPA Publication No. EPA 600/R-04/023). Washington, DC: Office of Research and Development.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 31-4 US EPA. (2012). Recreational Water Quality Criteria.
US EPA, Minnesota Pollution Control Agency and Minnehaha Creek Watershed District. (2013). Minnehaha Creek E. Coli Bacteria / Lake Hiawatha Nutrients Total Maximum Daily Load. Prepared by Tetra Tech.
U. S. Fish and Wildlife Service. Publication date (2012). National Wetlands Inventory website. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. http://www.fws.gov/wetlands/
Wedepohl, R.E., D.R. Knauer, G.B. Wolbert, H. Olem, P.J. Garrison, and K. Kepford. 1990. Monitoring Lake and Reservoir Restoration. EPA 440/4-90-007. Prep. by N. Am. Lake Manage. Soc. for U.S.E.P.A.
Whitman, Richard L., Byappanahalli, M.N., Nevers, M.B., Pawlik, H., & Shively, D.A. (2003). Occurrence of Escherichia coli and Enterococci in Cladophora (Chlorophyta) in nearshore water and beach sand of Lake Michigan. Applied and Environmental Microbiology, 69(8), 4714-4719.
Whitman, Richard L., & M. B. Nevers. (2003). Foreshore sand as a source of Escherichia coli in nearshore water of a Lake Michigan beach. Applied and Environmental Microbiology, 69(9), 5555-5562.
Winfield, Mollie D., & E. A. Groisman. (2003). Role of nonhost environments in the lifestyles of Salmonella and Escherichia coli. Applied and Environmental Microbiology, 69(7), 3687- 3694.
Wirth, Theodore. (1945). Minneapolis Park System, 1883-1944. Minneapolis: Board of Park Commissioners.
WHO, 2000. Monitoring Bathing Waters - A Practical Guide to the Design and Implementation of Assessments and Monitoring Programmes Edited by Jamie Bartram and Gareth Rees © 2000 WHO.
ISBN 0-419-24390-1Zumberge, J.H. (1952). The lakes of Minnesota: Their origin and classification. St. Paul, MN: The University of Minnesota Press.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page 31-5 APPENDIX A
This section contains box-and-whisker plots for each of the regularly monitored Minneapolis lakes for the entire period of record. A detailed explanation of box-and-whisker plots can be found in Section 1.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-1 Brownie Lake 1993-2016
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-2 Bde Maka Ska 1991-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-3 Cedar Lake 1991-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-4 Diamond Lake 1992-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-5 Grass Lake 2002-2016
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-6 Lake Harriet 1991-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-7 Lake Hiawatha 1992-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-8 Lake of the Isles 1991-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-9 Loring Pond 1992-2017 Note: Loring was not sampled in 1997.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-10 Lake Nokomis 1992-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-11 Powderhorn Lake 1992-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-12 Powderhorn Lake Nitrogen 1994-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-13 Spring Lake 1994-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-14 Spring Lake 1994- 2017 Nitrogen
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-15 Webber Pond 1992-2013
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-16 Wirth Lake 1992-2017
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-17 Wirth Lake 1994-2017 Nitrogen
2017 Water Resources Report – Minneapolis Park & Recreation Board Page A-18 Appendix B
This section contains lake monitoring data for 2017.
2017 Water Resources Report – Minneapolis Park & Recreation Board Page B-1 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0031 Calhoun 1/19/2017 9:41 0 0.26 85.8 12.09 7.87 665.1 0 1.70 1.07 0.957 0.037 0.027 1.060 1.123 0.243 123 148 132 9.11 27-0031 Calhoun 1/19/2017 9:41 1 1.69 86.5 11.72 7.85 671.3 0 27-0031 Calhoun 1/19/2017 9:40 2 1.87 86.5 11.65 7.85 668.7 0 27-0031 Calhoun 1/19/2017 9:40 3 1.88 86.2 11.62 7.83 668.8 0 27-0031 Calhoun 1/19/2017 9:39 4 1.91 85.5 11.51 7.82 668.3 0 27-0031 Calhoun 1/19/2017 9:39 5 1.99 83.6 11.23 7.79 667.6 0 27-0031 Calhoun 1/19/2017 9:38 6 2.08 80.2 10.75 7.74 667 0 0.038 0.028 27-0031 Calhoun 1/19/2017 9:36 7 2.13 74.3 9.95 7.7 668.8 0 27-0031 Calhoun 1/19/2017 9:35 8 2.17 73 9.76 7.68 673.2 0 27-0031 Calhoun 1/19/2017 9:34 9 2.21 75.4 10.07 7.69 674.5 0 27-0031 Calhoun 1/19/2017 9:34 10 2.27 75.6 10.07 7.68 678.9 0 27-0031 Calhoun 1/19/2017 9:33 11 2.26 74.4 9.92 7.65 684.8 0 27-0031 Calhoun 1/19/2017 9:33 12 2.38 70.3 9.35 7.62 687.7 0 0.041 0.028 27-0031 Calhoun 1/19/2017 9:32 13 2.36 70.4 9.37 7.6 697.8 0 27-0031 Calhoun 1/19/2017 9:31 14 2.39 64.2 8.53 7.54 704.2 0 27-0031 Calhoun 1/19/2017 9:30 15 2.45 60.3 7.99 7.49 706.2 0 27-0031 Calhoun 1/19/2017 9:29 16 2.38 55.7 7.4 7.43 742.4 0 27-0031 Calhoun 1/19/2017 9:28 17 2.47 54.3 7.2 7.4 756.3 0 27-0031 Calhoun 1/19/2017 9:27 18 2.48 53.6 7.11 7.38 769.8 0 0.048 0.038 27-0031 Calhoun 1/19/2017 9:27 19 2.44 49 6.5 7.33 814.8 0 27-0031 Calhoun 1/19/2017 9:26 20 2.71 35.4 4.66 7.27 838.9 0 27-0031 Calhoun 1/19/2017 9:25 21 2.87 18.1 2.37 7.21 850.2 0 27-0031 Calhoun 1/19/2017 9:24 22 3.01 12.7 1.66 7.2 839.5 0 0.090 0.071 160 10.88 27-0031 Calhoun 1/19/2017 9:23 23 3.15 1.3 0.17 7.16 880.3 0 27-0031 Calhoun 1/19/2017 9:21 24 3.38 0 0 7.12 899.9 0.9 27-0031 Calhoun 1/19/2017 9:20 24.6 3.75 0 0.01 7.08 910.2 6.2 27-0031 Calhoun 4/13/2017 10:38 5.68 0 7.09 97.5 11.68 8.16 702.1 0 1.28 0.96 <0.500 0.043 0.007 0.609 0.818 0.254 126 128 130 9.06 <0.250 27-0031 Calhoun 4/13/2017 10:37 1 7.1 97.4 11.67 8.16 702.2 0 27-0031 Calhoun 4/13/2017 10:36 2 7.08 98.1 11.76 8.15 702.2 0 27-0031 Calhoun 4/13/2017 10:36 3 7.06 97.6 11.7 8.15 702.4 0 27-0031 Calhoun 4/13/2017 10:35 4 7.01 97.1 11.66 8.2 702 0 27-0031 Calhoun 4/13/2017 10:35 5 6.96 97.1 11.68 8.14 702 0 27-0031 Calhoun 4/13/2017 10:34 6 6.9 96.6 11.64 8.14 702.2 0 0.038 0.008 27-0031 Calhoun 4/13/2017 10:34 7 6.89 96.5 11.63 8.14 702.2 0 27-0031 Calhoun 4/13/2017 10:33 8 6.85 96.7 11.66 8.14 702 0 27-0031 Calhoun 4/13/2017 10:33 9 6.77 96.8 11.69 8.14 702.2 0 27-0031 Calhoun 4/13/2017 10:32 10 6.7 96.4 11.67 8.13 702.2 0 27-0031 Calhoun 4/13/2017 10:32 11 6.68 96.3 11.66 8.13 702 0 27-0031 Calhoun 4/13/2017 10:31 12 6.66 95.9 11.61 8.12 702.3 0 0.039 0.007 27-0031 Calhoun 4/13/2017 10:30 13 6.59 95.8 11.63 8.12 702 0 27-0031 Calhoun 4/13/2017 10:30 14 6.58 96.1 11.67 8.12 702.1 0 27-0031 Calhoun 4/13/2017 10:29 15 6.56 95.7 11.62 8.11 701.9 0 27-0031 Calhoun 4/13/2017 10:29 16 6.54 95.8 11.64 8.11 702 0 27-0031 Calhoun 4/13/2017 10:28 17 6.49 95.2 11.59 8.1 702.3 0 27-0031 Calhoun 4/13/2017 10:28 18 6.45 94.8 11.55 8.09 701.7 0 0.046 0.007 27-0031 Calhoun 4/13/2017 10:27 19 6.4 94.6 11.53 8.08 701.9 0 27-0031 Calhoun 4/13/2017 10:26 20 6.39 93.9 11.46 8.07 701.7 0 27-0031 Calhoun 4/13/2017 10:26 21 6.4 93.9 11.45 8.06 701.8 0 27-0031 Calhoun 4/13/2017 10:26 22 6.38 93.3 11.39 8.05 702.1 0 0.046 0.008 140 9.56 27-0031 Calhoun 4/13/2017 10:25 23 6.3 92.5 11.31 8.03 702 0 27-0031 Calhoun 4/13/2017 10:24 24 6.25 92.1 11.27 8.02 702.2 0 27-0031 Calhoun 5/9/2017 10:46 6.28 0 13.8 115.9 11.7 8.46 693.4 3.2 2.82 0.79 <0.500 0.020 <0.003 <0.500 0.608 0.178 127 148 137 9.22 <0.250 27-0031 Calhoun 5/9/2017 10:46 1 13.22 116 11.86 8.46 690.6 3.3 27-0031 Calhoun 5/9/2017 10:45 2 13.01 116.3 11.95 8.46 691.3 3.4 27-0031 Calhoun 5/9/2017 10:44 3 12.94 116.3 11.96 8.45 691.5 3.5 27-0031 Calhoun 5/9/2017 10:42 4 12.78 113.7 11.74 8.41 691.3 3.8 27-0031 Calhoun 5/9/2017 10:41 5 12.44 112.8 11.73 8.37 690.3 4.1 27-0031 Calhoun 5/9/2017 10:40 6 10.53 104.3 11.34 8.26 692 4.1 0.025 0.017 27-0031 Calhoun 5/9/2017 10:38 7 9.84 97.1 10.73 8.16 691.9 4.5 27-0031 Calhoun 5/9/2017 10:36 8 9.4 89.4 9.99 8.08 692.6 4.7 27-0031 Calhoun 5/9/2017 10:35 9 9.33 88.1 9.85 8.07 692.9 4.9 27-0031 Calhoun 5/9/2017 10:34 10 9.17 84.8 9.52 8.06 694.1 5.2
2017 Water Resources Report - Minneapolis Park Recreation Board Page B1 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0031 Calhoun 5/9/2017 10:31 11 9.08 84.1 9.46 8.05 694.1 5.4 27-0031 Calhoun 5/9/2017 10:31 12 8.99 84.2 9.5 8.05 693.7 5.2 0.027 0.007 27-0031 Calhoun 5/9/2017 10:30 13 8.88 84.4 9.54 8.04 693.5 5.4 27-0031 Calhoun 5/9/2017 10:29 14 8.82 83.1 9.41 8.03 694.1 5.6 27-0031 Calhoun 5/9/2017 10:28 15 8.76 81.4 9.23 8.01 694.2 5.8 27-0031 Calhoun 5/9/2017 10:27 16 8.66 79.9 9.08 7.99 695.3 5.9 27-0031 Calhoun 5/9/2017 10:26 17 8.47 75.2 8.59 7.97 695.3 5.9 27-0031 Calhoun 5/9/2017 10:24 18 8.25 71.6 8.22 7.95 696.5 6.4 0.036 0.017 27-0031 Calhoun 5/9/2017 10:23 19 8.13 68.7 7.91 7.94 697.5 6.7 27-0031 Calhoun 5/9/2017 10:22 20 8.06 65.8 7.59 7.93 698.5 6.8 27-0031 Calhoun 5/9/2017 10:20 21 8.02 65.6 7.58 7.93 698.3 7.9 27-0031 Calhoun 5/9/2017 10:19 22 8.04 65.8 7.59 7.93 697.6 8.2 0.055 0.030 133 9.84 27-0031 Calhoun 5/9/2017 10:17 23 8.4 63.6 7.28 7.93 693.7 366.7 27-0031 Calhoun 5/24/2017 10:23 5.75 0 14.11 96.7 9.65 8.39 663.2 0 1.87 0.84 0.022 0.005 0.693 138 27-0031 Calhoun 5/24/2017 10:22 1 14.12 96.7 9.65 8.39 663.1 0 27-0031 Calhoun 5/24/2017 10:21 2 14.11 96.8 9.66 8.38 663.2 0 27-0031 Calhoun 5/24/2017 10:20 3 14.1 96.5 9.64 8.37 663.2 0 27-0031 Calhoun 5/24/2017 10:20 4 14.11 96.6 9.64 8.37 662.8 0 27-0031 Calhoun 5/24/2017 10:19 5 14.09 96.4 9.63 8.35 662.7 0 27-0031 Calhoun 5/24/2017 10:18 6 14.03 97.3 9.73 8.3 662.6 0 0.026 0.005 27-0031 Calhoun 5/24/2017 10:17 7 10.79 89.5 9.63 8.09 693.2 0 27-0031 Calhoun 5/24/2017 10:16 8 10.08 83.1 9.1 8.04 694.5 0 27-0031 Calhoun 5/24/2017 10:15 9 9.78 79 8.7 8.01 693.7 0 27-0031 Calhoun 5/24/2017 10:14 10 9.46 72.9 8.09 7.98 695.6 0 27-0031 Calhoun 5/24/2017 10:13 11 9.28 69.4 7.74 7.97 695.3 0 27-0031 Calhoun 5/24/2017 10:12 12 9.16 72.2 8.07 7.98 694.2 0 0.033 0.021 27-0031 Calhoun 5/24/2017 10:11 13 9.03 64.3 7.22 7.95 696.2 0 27-0031 Calhoun 5/24/2017 10:10 14 8.84 61.8 6.96 7.93 695.6 0 27-0031 Calhoun 5/24/2017 10:09 15 8.51 55.1 6.26 7.91 696.7 0 27-0031 Calhoun 5/24/2017 10:09 16 8.43 53.4 6.07 7.91 696.8 0 27-0031 Calhoun 5/24/2017 10:08 17 8.4 51.1 5.82 7.91 697.2 0 27-0031 Calhoun 5/24/2017 10:07 18 8.38 50.5 5.75 7.92 697.7 0 0.090 0.068 27-0031 Calhoun 5/24/2017 10:03 19 8.34 48.7 5.56 7.95 697.8 0 27-0031 Calhoun 5/24/2017 10:02 20 8.31 46.7 5.33 7.95 698.1 0 27-0031 Calhoun 5/24/2017 10:01 21 8.29 42.3 4.83 7.95 698.7 0 27-0031 Calhoun 5/24/2017 10:01 22 8.28 41.5 4.74 7.95 699.2 0 0.109 0.097 147 27-0031 Calhoun 5/24/2017 10:00 23 8.28 37.6 4.3 7.97 700.3 0 27-0031 Calhoun 5/24/2017 9:59 24 8.26 34.3 3.92 8 701 0 27-0031 Calhoun 6/6/2017 10:03 4.55 0 21.23 126.1 10.97 8.66 705 3.4 3.19 0.79 <0.500 0.019 0.003 0.532 136 27-0031 Calhoun 6/6/2017 10:02 1 21.12 126.3 11.02 8.64 706 3.7 27-0031 Calhoun 6/6/2017 10:01 2 20.36 129.3 11.44 8.56 709.2 4.3 27-0031 Calhoun 6/6/2017 10:01 3 17.42 125 11.74 8.47 698.6 4.7 27-0031 Calhoun 6/6/2017 10:01 4 16.61 116.2 11.1 8.36 700.2 5 27-0031 Calhoun 6/6/2017 10:00 5 15.98 106.5 10.32 8.21 702.4 5.2 27-0031 Calhoun 6/6/2017 10:00 6 13.94 85.4 8.64 7.97 707.3 5.5 0.022 0.003 27-0031 Calhoun 6/6/2017 9:59 7 11.79 77.5 8.23 7.89 718.8 5.8 27-0031 Calhoun 6/6/2017 9:59 8 10.38 68.5 7.51 7.86 728.1 6.2 27-0031 Calhoun 6/6/2017 9:58 9 9.78 59 6.57 7.84 730.2 6.6 27-0031 Calhoun 6/6/2017 9:57 10 9.44 53.7 6.03 7.83 731.6 7.5 27-0031 Calhoun 6/6/2017 9:57 11 9.19 54.6 6.16 7.82 731.9 8.1 27-0031 Calhoun 6/6/2017 9:56 12 8.95 55.1 6.26 7.81 730.2 8.5 0.052 0.041 27-0031 Calhoun 6/6/2017 9:56 13 8.72 48.2 5.5 7.8 730.8 9.2 27-0031 Calhoun 6/6/2017 9:55 14 8.6 40.8 4.67 7.78 732.1 10.1 27-0031 Calhoun 6/6/2017 9:55 15 8.52 36 4.13 7.78 732.8 11 27-0031 Calhoun 6/6/2017 9:54 16 8.45 31.7 3.64 7.77 733.6 12.5 27-0031 Calhoun 6/6/2017 9:54 17 8.41 30.7 3.52 7.77 734 14 27-0031 Calhoun 6/6/2017 9:53 18 8.4 30 3.45 7.76 734.8 16.3 0.122 0.112 27-0031 Calhoun 6/6/2017 9:53 19 8.41 29.7 3.42 7.76 734.4 17.7 27-0031 Calhoun 6/6/2017 9:52 20 8.4 28.5 3.27 7.75 734.8 9.6 27-0031 Calhoun 6/6/2017 9:52 21 8.39 26.8 3.08 7.74 734.9 12.1 27-0031 Calhoun 6/6/2017 9:51 22 8.4 26.7 3.07 7.73 735.1 4.7 0.147 0.124 140 27-0031 Calhoun 6/6/2017 9:50 23 8.4 25.7 2.95 7.71 735.4 56.7
2017 Water Resources Report - Minneapolis Park Recreation Board Page B2 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0031 Calhoun 6/6/2017 9:50 24 8.38 24.4 2.8 7.68 736.5 351.6 27-0031 Calhoun 6/6/2017 9:49 24.2 8.89 1.3 0.15 7.49 747.6 406 27-0031 Calhoun 6/21/2017 9:50 2.55 0 22.76 113.4 9.52 8.72 667.9 1.8 6.46 3.41 0.022 0.004 0.516 128 27-0031 Calhoun 6/21/2017 9:50 1 22.71 113.5 9.54 8.71 668.4 2.2 27-0031 Calhoun 6/21/2017 9:50 2 22.57 112 9.43 8.68 668.9 3.1 27-0031 Calhoun 6/21/2017 9:49 3 22.52 110.3 9.29 8.63 669.1 3.7 27-0031 Calhoun 6/21/2017 9:49 4 22.43 104.4 8.82 8.48 666.5 4.4 27-0031 Calhoun 6/21/2017 9:48 5 18.85 88.3 8 8.15 678.9 5.8 27-0031 Calhoun 6/21/2017 9:48 6 14.23 65 6.49 8.01 689.3 1968 0.022 0.003 27-0031 Calhoun 6/21/2017 9:47 7 12.07 54.8 5.74 7.98 695 6.6 27-0031 Calhoun 6/21/2017 9:47 8 10.91 51.7 5.56 7.97 704 6.8 27-0031 Calhoun 6/21/2017 9:46 9 10.23 42.4 4.64 7.95 706.2 7 27-0031 Calhoun 6/21/2017 9:46 10 9.75 34.6 3.82 7.94 708.3 7.1 27-0031 Calhoun 6/21/2017 9:45 11 9.42 41 4.57 7.95 706.3 7.3 27-0031 Calhoun 6/21/2017 9:44 12 9.26 37 4.13 7.94 707.3 7.4 0.046 0.029 27-0031 Calhoun 6/21/2017 9:43 13 9.11 35.3 3.96 7.93 707.3 7.5 27-0031 Calhoun 6/21/2017 9:43 14 8.81 27.1 3.06 7.92 707.7 7.5 27-0031 Calhoun 6/21/2017 9:42 15 8.62 19.6 2.23 7.91 710.2 7.5 27-0031 Calhoun 6/21/2017 9:42 16 8.57 16.5 1.88 7.91 709.9 7.5 27-0031 Calhoun 6/21/2017 9:41 17 8.47 10.2 1.17 7.9 711.1 7 27-0031 Calhoun 6/21/2017 9:40 18 8.45 7.6 0.87 7.9 711.7 6.7 0.145 0.129 27-0031 Calhoun 6/21/2017 9:40 19 8.45 6.5 0.74 7.9 711.7 6.7 27-0031 Calhoun 6/21/2017 9:39 20 8.41 4 0.46 7.9 712.1 6.4 27-0031 Calhoun 6/21/2017 9:39 21 8.42 2.7 0.31 7.91 712.2 5.8 27-0031 Calhoun 6/21/2017 9:38 22 8.43 2.3 0.26 7.91 713.6 5.4 0.184 0.158 132 27-0031 Calhoun 6/21/2017 9:37 23 8.42 1.9 0.21 7.9 714 3.9 27-0031 Calhoun 6/21/2017 9:36 24 8.4 1.2 0.14 7.94 716.4 2.5 27-0031 Calhoun 7/11/2017 9:36 4.66 0 25.2 116.8 9.36 8.59 654.4 6 4.53 1.32 <0.500 0.017 0.004 0.941 0.965 <0.030 112 132 122 9.27 0.339 27-0031 Calhoun 7/11/2017 9:36 1 25.1 116.9 9.39 8.59 654 6.4 27-0031 Calhoun 7/11/2017 9:35 2 24.92 116.2 9.36 8.53 655.2 7.5 27-0031 Calhoun 7/11/2017 9:35 3 24.65 116.2 9.41 8.49 651.4 7.9 27-0031 Calhoun 7/11/2017 9:34 4 22.4 118.2 9.98 8.33 658.5 8.4 27-0031 Calhoun 7/11/2017 9:34 5 21.07 107 9.28 8.15 657.5 8.7 27-0031 Calhoun 7/11/2017 9:33 6 17.14 52.9 4.96 7.85 671.1 8.9 0.022 0.005 27-0031 Calhoun 7/11/2017 9:33 7 13.4 30.6 3.11 7.81 690.8 9.1 27-0031 Calhoun 7/11/2017 9:32 8 11.03 20.5 2.2 7.81 699.5 9.3 27-0031 Calhoun 7/11/2017 9:31 9 10.22 10.8 1.19 7.81 699.7 9.6 27-0031 Calhoun 7/11/2017 9:31 10 9.93 4.1 0.45 7.81 700.5 9.7 27-0031 Calhoun 7/11/2017 9:30 11 9.47 5.8 0.65 7.81 700.5 10.2 27-0031 Calhoun 7/11/2017 9:29 12 9.1 7.8 0.88 7.82 698.9 9.6 0.062 0.045 27-0031 Calhoun 7/11/2017 9:29 13 8.82 5.1 0.58 7.81 699.3 9.7 27-0031 Calhoun 7/11/2017 9:29 14 8.65 0 0 7.81 702.1 9.9 27-0031 Calhoun 7/11/2017 9:28 15 8.55 0 0 7.82 702.4 10.1 27-0031 Calhoun 7/11/2017 9:27 16 8.5 0 0 7.83 703.1 10.8 27-0031 Calhoun 7/11/2017 9:27 17 8.49 0 0 7.84 703.3 10.9 27-0031 Calhoun 7/11/2017 9:26 18 8.49 0 0 7.85 703.3 11 0.186 0.169 27-0031 Calhoun 7/11/2017 9:26 19 8.48 0 0 7.87 703.1 11.4 27-0031 Calhoun 7/11/2017 9:25 20 8.47 0 0 7.91 704.1 11.5 27-0031 Calhoun 7/11/2017 9:24 21 8.45 0 0 7.95 704.4 12.2 27-0031 Calhoun 7/11/2017 9:24 22 8.42 0 0 7.97 704.8 12.4 0.216 0.190 131 8.15 27-0031 Calhoun 7/11/2017 9:23 23 8.45 0 0 8.01 704.6 11.9 27-0031 Calhoun 7/11/2017 9:23 24.1 8.47 0 0 8.06 708 11.1 27-0031 Calhoun 7/25/2017 9:41 3.11 0 24.68 103.5 8.41 8.46 653.9 7.3 5.85 1.63 0.020 0.005 <0.500 129 27-0031 Calhoun 7/25/2017 9:41 1 24.63 103.6 8.42 8.45 654.2 8 27-0031 Calhoun 7/25/2017 9:41 2 24.59 103.4 8.42 8.42 654 9.1 27-0031 Calhoun 7/25/2017 9:40 3 24.5 103 8.4 8.36 655 10.8 27-0031 Calhoun 7/25/2017 9:39 4 24.47 98.6 8.04 8.2 654.2 13.2 27-0031 Calhoun 7/25/2017 9:39 5 22.94 82.8 6.96 7.97 665.7 15 27-0031 Calhoun 7/25/2017 9:38 6 17.71 34.9 3.25 7.78 689 17.2 0.030 0.004 27-0031 Calhoun 7/25/2017 9:38 7 14.49 6 0.6 7.76 704.1 18.5 27-0031 Calhoun 7/25/2017 9:37 8 11.73 1.2 0.13 7.76 706.3 20.8 27-0031 Calhoun 7/25/2017 9:37 9 10.65 1.9 0.21 7.77 707.3 21.6
2017 Water Resources Report - Minneapolis Park Recreation Board Page B3 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0031 Calhoun 7/25/2017 9:36 10 10.1 1.6 0.17 7.77 707.4 23.9 27-0031 Calhoun 7/25/2017 9:35 11 9.75 0 0 7.77 707.8 24 27-0031 Calhoun 7/25/2017 9:35 12 9.37 0.1 0.01 7.78 706.6 28.3 0.071 0.053 27-0031 Calhoun 7/25/2017 9:34 13 9 0 0 7.78 706.8 27.3 27-0031 Calhoun 7/25/2017 9:34 14 8.81 0 0 7.78 708.4 22.1 27-0031 Calhoun 7/25/2017 9:33 15 8.65 0 0 7.79 709 26.2 27-0031 Calhoun 7/25/2017 9:33 16 8.58 0 0 7.79 709.2 22.3 27-0031 Calhoun 7/25/2017 9:32 17 8.52 0 0 7.8 711.4 22.5 27-0031 Calhoun 7/25/2017 9:31 18 8.49 0 0 7.81 710.8 11.5 0.209 0.193 27-0031 Calhoun 7/25/2017 9:31 19 8.49 0 0 7.82 710.8 19.5 27-0031 Calhoun 7/25/2017 9:30 20 8.45 0 0 7.84 711.6 15.5 27-0031 Calhoun 7/25/2017 9:29 21 8.47 0 0 7.86 712.2 22.9 27-0031 Calhoun 7/25/2017 9:28 22 8.47 0 0 7.9 711.5 36.3 0.236 0.219 140 27-0031 Calhoun 7/25/2017 9:28 22.8 8.45 0 0 7.93 712.9 30.2 27-0031 Calhoun 8/8/2017 10:37 2.3 0 23.8 114.4 9.51 8.57 646.9 0 6.94 1.75 1.040 0.023 0.004 0.526 126 1.00 27-0031 Calhoun 8/8/2017 10:36 1 23.67 113.9 9.5 8.55 646.5 0.3 27-0031 Calhoun 8/8/2017 10:35 2 23.35 112.9 9.48 8.52 646.1 1.1 27-0031 Calhoun 8/8/2017 10:35 3 22.97 109.4 9.24 8.47 645.4 1.9 27-0031 Calhoun 8/8/2017 10:34 4 22.75 105.8 8.98 8.39 647 2.8 27-0031 Calhoun 8/8/2017 10:33 5 22.28 89.9 7.7 8.12 652.2 4.4 27-0031 Calhoun 8/8/2017 10:32 6 20.41 6.6 0.59 7.86 678.3 5.4 0.025 0.005 27-0031 Calhoun 8/8/2017 10:31 7 14.39 0 0 7.84 708.6 6.5 27-0031 Calhoun 8/8/2017 10:30 8 11.89 0 0 7.85 710.4 7.2 27-0031 Calhoun 8/8/2017 10:29 9 10.72 0 0 7.85 712.3 7.9 27-0031 Calhoun 8/8/2017 10:28 10 10.24 0 0 7.86 712 8.8 27-0031 Calhoun 8/8/2017 10:27 11 9.89 0 0 7.86 711.8 10.2 27-0031 Calhoun 8/8/2017 10:26 12 9.43 0 0 7.87 709.6 11.2 0.085 0.063 27-0031 Calhoun 8/8/2017 10:26 13 8.91 0 0 7.88 711.3 12.3 27-0031 Calhoun 8/8/2017 10:25 14 8.66 0 0 7.88 713.1 12.9 27-0031 Calhoun 8/8/2017 10:24 15 8.57 0 0 7.88 714.3 13.4 27-0031 Calhoun 8/8/2017 10:24 16 8.54 0 0 7.9 714 13.9 27-0031 Calhoun 8/8/2017 10:23 17 8.5 0 0 7.91 714.5 13.6 27-0031 Calhoun 8/8/2017 10:23 18 8.5 0 0 7.92 715.3 13.7 0.235 0.205 27-0031 Calhoun 8/8/2017 10:22 19 8.5 0 0 7.94 714.8 13.5 27-0031 Calhoun 8/8/2017 10:21 20 8.45 0 0 7.96 716.3 13.6 27-0031 Calhoun 8/8/2017 10:21 21 8.46 0 0 7.98 717.2 13.8 27-0031 Calhoun 8/8/2017 10:20 22 8.52 0 0 8.01 716.7 12.3 0.275 0.261 140 27-0031 Calhoun 8/8/2017 10:19 23 8.5 0.6 0.07 8.06 719.4 12.6 27-0031 Calhoun 8/8/2017 10:19 24 8.96 0 0 8.11 716.6 39.3 27-0031 Calhoun 8/22/2017 10:04 2.8 0 22.27 97.6 8.32 8.35 623.1 0 7.50 0.67 0.023 0.005 0.602 127 27-0031 Calhoun 8/22/2017 10:03 1 22.29 97.4 8.29 8.34 623.5 0 27-0031 Calhoun 8/22/2017 10:03 2 22.27 97.3 8.29 8.32 622.6 0 27-0031 Calhoun 8/22/2017 10:02 3 22.28 97.3 8.29 8.3 622.6 0.7 27-0031 Calhoun 8/22/2017 10:01 4 22.26 97.1 8.28 8.26 622.8 1.6 27-0031 Calhoun 8/22/2017 10:00 5 22.21 96.4 8.22 8.19 622.5 2.6 27-0031 Calhoun 8/22/2017 9:59 6 22.01 92.5 7.92 8.02 621.6 3.6 0.022 0.005 27-0031 Calhoun 8/22/2017 9:58 7 17.52 0.1 0.01 7.72 692.3 4.5 27-0031 Calhoun 8/22/2017 9:57 8 13.4 0 0 7.72 711.8 5.3 27-0031 Calhoun 8/22/2017 9:56 9 11.31 0 0 7.73 712.4 5.9 27-0031 Calhoun 8/22/2017 9:56 10 10.43 0 0 7.74 712.5 6.3 27-0031 Calhoun 8/22/2017 9:55 11 9.99 0 0 7.75 713.3 6.6 27-0031 Calhoun 8/22/2017 9:54 12 9.72 0 0 7.76 711 7 0.099 0.074 27-0031 Calhoun 8/22/2017 9:53 13 9.23 0 0 7.76 712.7 7.1 27-0031 Calhoun 8/22/2017 9:53 14 9 0 0 7.77 712.8 7.3 27-0031 Calhoun 8/22/2017 9:52 15 8.89 0 0 7.78 712.7 7.6 27-0031 Calhoun 8/22/2017 9:51 16 8.77 0 0 7.8 714 8.4 27-0031 Calhoun 8/22/2017 9:50 17 8.71 0 0 7.82 714.4 8.7 27-0031 Calhoun 8/22/2017 9:50 18 8.59 0 0 7.83 714.9 8.8 0.206 0.180 27-0031 Calhoun 8/22/2017 9:49 19 8.57 0 0 7.84 715.1 8.6 27-0031 Calhoun 8/22/2017 9:48 20 8.54 0 0 7.88 716 8 27-0031 Calhoun 8/22/2017 9:47 21 8.5 0 0 7.91 716 6.7 27-0031 Calhoun 8/22/2017 9:47 22 8.53 0 0 7.94 716.1 5.6 0.249 0.225 145
2017 Water Resources Report - Minneapolis Park Recreation Board Page B4 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0031 Calhoun 8/22/2017 9:46 23 8.54 0 0 8 716.7 1.9 27-0031 Calhoun 8/22/2017 9:45 23.3 8.56 0 0 8.08 717 0 27-0031 Calhoun 9/12/2017 10:34 2.73 0 20.71 113.3 9.96 8.09 634.9 2.9 7.31 1.04 1.120 0.021 0.005 0.640 131 27-0031 Calhoun 9/12/2017 10:34 1 20.46 99.1 8.76 8.06 634.6 3.5 27-0031 Calhoun 9/12/2017 10:33 2 20.14 132.3 11.76 7.99 634.4 4.4 27-0031 Calhoun 9/12/2017 10:33 3 19.76 98.4 8.82 7.96 630 4.8 27-0031 Calhoun 9/12/2017 10:32 4 19.58 85 7.64 7.91 633.6 5.4 27-0031 Calhoun 9/12/2017 10:32 5 19.37 86.7 7.82 7.85 634.8 6 27-0031 Calhoun 9/12/2017 10:32 6 19.19 84.5 7.66 7.79 634.5 6.6 0.025 0.005 27-0031 Calhoun 9/12/2017 10:31 7 18.93 76.2 6.94 7.71 632.9 7.2 27-0031 Calhoun 9/12/2017 10:30 8 15.52 0 0 7.58 707.7 8.2 27-0031 Calhoun 9/12/2017 10:30 9 11.63 0 0 7.59 716.5 9.2 27-0031 Calhoun 9/12/2017 10:29 10 10.5 0 0 7.61 717.9 9 27-0031 Calhoun 9/12/2017 10:28 11 10.1 0 0 7.62 717.8 8.9 27-0031 Calhoun 9/12/2017 10:28 12 9.72 0 0 7.63 715.5 9 0.106 0.086 27-0031 Calhoun 9/12/2017 10:27 13 9.21 0 0 7.64 715.5 9.3 27-0031 Calhoun 9/12/2017 10:27 14 8.87 0 0 7.64 716.5 9.8 27-0031 Calhoun 9/12/2017 10:26 15 8.68 0 0 7.65 719.1 10.2 27-0031 Calhoun 9/12/2017 10:26 16 8.63 0 0 7.66 719.3 10.2 27-0031 Calhoun 9/12/2017 10:26 17 8.55 0 0 7.67 721 10.1 27-0031 Calhoun 9/12/2017 10:25 18 8.54 0 0 7.69 720.4 9.9 0.253 0.240 27-0031 Calhoun 9/12/2017 10:25 19 8.52 0 0 7.7 721 9.8 27-0031 Calhoun 9/12/2017 10:25 20 8.55 0 0 7.71 721.1 9.9 27-0031 Calhoun 9/12/2017 10:24 21 8.5 0 0 7.74 721.7 10.3 27-0031 Calhoun 9/12/2017 10:24 22 8.55 0 0 7.78 722.1 13.3 0.289 0.271 141 27-0031 Calhoun 9/12/2017 10:23 23 8.59 0 0 7.8 722.2 11.9 27-0031 Calhoun 9/26/2017 10:08 2.7 0 21.38 113.2 9.77 8.31 619 6.68 2.95 0.023 0.003 0.542 117 27-0031 Calhoun 9/26/2017 10:07 1 21.38 111.4 9.62 8.29 618.9 27-0031 Calhoun 9/26/2017 10:06 2 21.38 111.6 9.64 8.26 618.6 27-0031 Calhoun 9/26/2017 10:05 3 21.38 111.6 9.63 8.19 618.1 27-0031 Calhoun 9/26/2017 10:04 4 21.38 111 9.58 8.09 618.1 27-0031 Calhoun 9/26/2017 10:04 5 21.15 94.3 8.18 7.84 618.8 27-0031 Calhoun 9/26/2017 10:02 6 19.48 58.8 5.27 7.37 626.5 0.018 <0.003 27-0031 Calhoun 9/26/2017 10:01 7 18.57 31.7 2.89 7.16 631.8 27-0031 Calhoun 9/26/2017 10:00 8 15.25 1.5 0.15 6.99 681.2 27-0031 Calhoun 9/26/2017 9:58 9 11.97 1.1 0.12 6.93 697.9 27-0031 Calhoun 9/26/2017 9:57 10 10.79 1.4 0.15 6.9 695.9 27-0031 Calhoun 9/26/2017 9:55 11 10.25 1.2 0.13 6.9 694.9 27-0031 Calhoun 9/26/2017 9:53 12 9.87 1.3 0.14 6.88 695 0.118 0.079 27-0031 Calhoun 9/26/2017 9:52 13 9.22 1.3 0.15 6.86 694.6 27-0031 Calhoun 9/26/2017 9:50 14 8.94 1.4 0.16 6.83 696.9 27-0031 Calhoun 9/26/2017 9:48 15 8.82 1.4 0.16 6.81 697.7 27-0031 Calhoun 9/26/2017 9:45 16 8.73 1.7 0.19 6.81 698.8 27-0031 Calhoun 9/26/2017 9:44 17 8.7 1.8 0.2 6.81 699 27-0031 Calhoun 9/26/2017 9:43 18 8.68 2.2 0.25 6.81 699.4 0.268 0.246 27-0031 Calhoun 9/26/2017 9:42 19 8.68 2.4 0.27 6.82 699.9 27-0031 Calhoun 9/26/2017 9:41 20 8.67 2.6 0.3 6.83 700 27-0031 Calhoun 9/26/2017 9:41 21 8.66 2.6 0.3 6.82 700 27-0031 Calhoun 9/26/2017 9:40 22 8.65 3.1 0.36 6.86 700.6 0.274 0.256 131 27-0031 Calhoun 9/26/2017 9:38 23 8.63 4.3 0.49 6.92 701.2 27-0031 Calhoun 11/13/2017 11:21 4.85 0 5.39 73 9.15 7.93 657.4 0.5 4.58 1.06 0.703 0.049 0.030 0.669 0.819 0.081 125 142 124 8.01 0.393 27-0031 Calhoun 11/13/2017 11:20 1 5.39 72.9 9.14 7.94 657.5 0.5 27-0031 Calhoun 11/13/2017 11:20 2 5.39 73 9.15 7.93 657.6 0.5 27-0031 Calhoun 11/13/2017 11:19 3 5.39 72.9 9.14 7.93 657.6 0.5 27-0031 Calhoun 11/13/2017 11:19 4 5.38 72.7 9.12 7.93 657.6 0.5 27-0031 Calhoun 11/13/2017 11:19 5 5.37 72.9 9.14 7.92 657.3 0.5 27-0031 Calhoun 11/13/2017 11:18 6 5.36 72.7 9.11 7.92 657.4 0.4 0.046 0.030 27-0031 Calhoun 11/13/2017 11:17 7 5.35 72.3 9.08 7.91 657.6 0.4 27-0031 Calhoun 11/13/2017 11:17 8 5.35 72.4 9.08 7.91 657.6 0.4 27-0031 Calhoun 11/13/2017 11:16 9 5.35 72.3 9.07 7.9 657.3 0.4 27-0031 Calhoun 11/13/2017 11:15 10 5.35 72.4 9.09 7.9 657.7 0.4 27-0031 Calhoun 11/13/2017 11:15 11 5.34 72.3 9.07 7.9 657.7 0.4
2017 Water Resources Report - Minneapolis Park Recreation Board Page B5 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0031 Calhoun 11/13/2017 11:14 12 5.34 72.4 9.09 7.89 657.6 0.4 0.046 0.030 27-0031 Calhoun 11/13/2017 11:14 13 5.34 72.4 9.09 7.89 657.6 0.4 27-0031 Calhoun 11/13/2017 11:13 14 5.32 72.5 9.1 7.89 657.6 0.4 27-0031 Calhoun 11/13/2017 11:12 15 5.31 72.3 9.08 7.88 657.5 0.3 27-0031 Calhoun 11/13/2017 11:11 16 5.31 72.3 9.07 7.87 657.6 0.3 27-0031 Calhoun 11/13/2017 11:11 17 5.3 72.2 9.07 7.87 657.4 0.3 27-0031 Calhoun 11/13/2017 11:10 18 5.3 72.2 9.07 7.86 657.4 0.2 0.049 0.029 27-0031 Calhoun 11/13/2017 11:10 19 5.3 72.2 9.07 7.85 657.4 0.2 27-0031 Calhoun 11/13/2017 11:09 20 5.3 72.1 9.06 7.85 657.4 0.1 27-0031 Calhoun 11/13/2017 11:08 21 5.3 72.1 9.06 7.84 658.3 0.1 27-0031 Calhoun 11/13/2017 11:08 22 5.28 72.2 9.07 7.83 657.6 0.1 0.050 0.029 124 8.14 27-0031 Calhoun 11/13/2017 11:07 23 5.26 71.9 9.05 7.82 657.6 0 27-0031 Calhoun 11/13/2017 11:07 24.1 5.24 72 9.06 7.81 657.5 0 27-0039 Cedar 1/19/2017 11:04 0 0.61 78.6 10.98 7.93 681.1 0 13.70 3.37 3.720 0.080 0.035 1.190 1.340 0.313 141 176 123 11.95 27-0039 Cedar 1/19/2017 11:03 1 2.58 70.2 9.28 7.75 676.5 0 27-0039 Cedar 1/19/2017 11:02 2 2.61 68.5 9.05 7.73 676.6 0 27-0039 Cedar 1/19/2017 11:01 3 2.68 57 7.52 7.65 679.6 0 27-0039 Cedar 1/19/2017 11:00 4 2.73 55.8 7.34 7.64 685.3 0 27-0039 Cedar 1/19/2017 11:00 5 2.8 54.6 7.18 7.64 686.6 0 0.069 0.051 27-0039 Cedar 1/19/2017 10:59 6 2.73 57.7 7.6 7.65 693.7 0 27-0039 Cedar 1/19/2017 10:58 7 2.68 56.7 7.47 7.64 699.4 0 27-0039 Cedar 1/19/2017 10:57 8 2.76 53.8 7.08 7.62 703.5 0 27-0039 Cedar 1/19/2017 10:56 9 2.75 58.3 7.67 7.64 708.7 0 27-0039 Cedar 1/19/2017 10:55 10 2.86 52.5 6.88 7.61 708.4 0 0.073 0.054 27-0039 Cedar 1/19/2017 10:54 11 2.89 48.2 6.32 7.59 709.5 0 27-0039 Cedar 1/19/2017 10:53 12 2.89 45.5 5.96 7.54 709.5 0 27-0039 Cedar 1/19/2017 10:52 13 2.99 26.6 3.48 7.44 714.6 0 27-0039 Cedar 1/19/2017 10:51 14 3.14 3.5 0.46 7.35 716.4 19.3 0.113 0.108 132 11.75 27-0039 Cedar 1/19/2017 10:50 15 3.19 2.8 0.36 7.3 719.7 2200 27-0039 Cedar 4/13/2017 11:49 1.22 0 9.03 124.8 14.26 8.84 705.2 5.5 15.40 4.34 1.400 0.058 <0.003 0.983 1.040 0.092 143 176 125 12.03 <0.250 27-0039 Cedar 4/13/2017 11:49 1 8.96 124.6 14.27 8.84 705.4 3.1 27-0039 Cedar 4/13/2017 11:47 2 8.55 115.9 13.4 8.75 705.5 3.2 27-0039 Cedar 4/13/2017 11:47 3 7.92 110.1 12.94 8.69 708.2 2.6 27-0039 Cedar 4/13/2017 11:46 4 7.75 110.5 13.03 8.69 705.6 3.6 27-0039 Cedar 4/13/2017 11:46 5 7.6 109.5 12.96 8.67 705.2 3.4 0.052 <0.003 27-0039 Cedar 4/13/2017 11:45 6 7.5 108.2 12.84 8.64 705.4 3.7 27-0039 Cedar 4/13/2017 11:44 7 7.3 105.2 12.55 8.58 707.5 2 27-0039 Cedar 4/13/2017 11:43 8 7.14 100 11.98 8.5 708.2 1.7 27-0039 Cedar 4/13/2017 11:43 9 6.64 93.6 11.35 8.38 710.5 1.4 27-0039 Cedar 4/13/2017 11:42 10 5.66 85.1 10.57 8.15 708.3 1.3 0.049 <0.003 27-0039 Cedar 4/13/2017 11:42 11 5.42 85.6 10.7 8.14 707.4 1.3 27-0039 Cedar 4/13/2017 11:41 12 5.34 84.9 10.64 8.12 707.4 1.6 27-0039 Cedar 4/13/2017 11:40 13 5.24 79.9 10.04 8.06 707 2 27-0039 Cedar 4/13/2017 11:39 14 5.21 76.3 9.59 8.01 707.8 0.1 0.054 <0.003 130 11.77 27-0039 Cedar 4/13/2017 11:38 15 5.18 66.6 8.38 7.95 709.3 3.2 27-0039 Cedar 5/9/2017 12:23 1.41 0 16.2 128.3 12.3 8.72 710.5 14.7 10.41 2.71 1.365 0.050 0.007 0.860 0.976 <0.030 141 170 135 11.90 0.754 27-0039 Cedar 5/9/2017 12:22 1 15.81 128 12.37 8.71 710 16.2 27-0039 Cedar 5/9/2017 12:21 2 15.02 128 12.58 8.7 702.5 17.7 27-0039 Cedar 5/9/2017 12:20 3 12.34 127.4 13.29 8.63 705.6 18.8 27-0039 Cedar 5/9/2017 12:19 4 10.8 103.8 11.21 8.43 704.8 19 27-0039 Cedar 5/9/2017 12:18 5 10.1 82.4 9.05 8.24 706.7 17.9 0.052 0.012 27-0039 Cedar 5/9/2017 12:17 6 9.82 73.7 8.15 8.16 707.3 18.3 27-0039 Cedar 5/9/2017 12:16 7 9.52 67.6 7.52 8.11 708.4 19.1 27-0039 Cedar 5/9/2017 12:15 8 9.11 57.8 6.49 8 710.4 20.5 27-0039 Cedar 5/9/2017 12:14 9 8.33 37.8 4.33 7.88 712.8 22.2 27-0039 Cedar 5/9/2017 12:13 10 7.59 23.9 2.79 7.81 713.1 24.4 0.070 0.041 27-0039 Cedar 5/9/2017 12:11 11 7.04 5.4 0.63 7.75 714.1 27.9 27-0039 Cedar 5/9/2017 12:10 12 6.56 0 0 7.75 715 28.9 27-0039 Cedar 5/9/2017 12:08 13 6.43 0 0 7.75 716.9 33.1 27-0039 Cedar 5/9/2017 12:07 14 6.37 0 0 7.8 717.6 36.6 0.128 0.090 135 11.80 27-0039 Cedar 5/24/2017 12:02 1.23 0 15.11 115.2 11.26 8.63 661 21.1 17.00 0.52 0.038 0.005 0.666 138 27-0039 Cedar 5/24/2017 12:01 1 14.91 116.7 11.45 8.62 658.1 22.3
2017 Water Resources Report - Minneapolis Park Recreation Board Page B6 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0039 Cedar 5/24/2017 12:01 2 14.57 114 11.27 8.56 658.2 24.9 27-0039 Cedar 5/24/2017 12:00 3 14.28 107.6 10.71 8.45 659.3 26.6 27-0039 Cedar 5/24/2017 12:00 4 12.97 88.2 9.03 8.18 661.3 28.5 27-0039 Cedar 5/24/2017 11:59 5 11.55 77.5 8.2 8.03 695.6 29.6 0.056 <0.003 27-0039 Cedar 5/24/2017 11:58 6 10.22 45 4.9 7.81 706.8 26.2 27-0039 Cedar 5/24/2017 11:58 7 9.69 20.3 2.24 7.75 707.6 24.2 27-0039 Cedar 5/24/2017 11:57 8 9.09 13.3 1.49 7.74 709.4 24.2 27-0039 Cedar 5/24/2017 11:57 9 8.31 0 0 7.71 714.7 24.1 27-0039 Cedar 5/24/2017 11:56 10 7.75 0 0 7.7 716.9 25.6 0.079 0.049 27-0039 Cedar 5/24/2017 11:55 11 7.22 0 0 7.7 716.2 30.5 27-0039 Cedar 5/24/2017 11:55 12 6.96 0 0 7.69 716.7 37.6 27-0039 Cedar 5/24/2017 11:54 13 6.79 0 0 7.7 718.2 42.6 27-0039 Cedar 5/24/2017 11:54 14 6.73 0 0 7.7 718.7 42.3 0.180 0.133 152 27-0039 Cedar 5/24/2017 11:53 15 6.56 0 0 7.73 721.2 105.5 27-0039 Cedar 6/6/2017 12:04 1.81 0 23.66 127.6 10.6 8.79 690.1 14.1 5.66 0.78 0.506 0.026 0.003 0.656 121 27-0039 Cedar 6/6/2017 12:03 1 22.64 131.5 11.13 8.81 687.4 16.1 27-0039 Cedar 6/6/2017 12:02 2 21.5 138.2 11.96 8.8 689.2 18.9 27-0039 Cedar 6/6/2017 12:01 3 16.53 132.8 12.7 8.78 689.1 23.6 27-0039 Cedar 6/6/2017 12:00 4 14.18 117.9 11.87 8.64 697.9 28 27-0039 Cedar 6/6/2017 11:59 5 11.5 47.4 5.07 7.93 734.7 32.7 0.037 0.002 27-0039 Cedar 6/6/2017 11:58 6 10.29 19.6 2.15 7.87 744.8 31.7 27-0039 Cedar 6/6/2017 11:57 7 9.39 0 0 7.83 746.4 33.3 27-0039 Cedar 6/6/2017 11:56 8 8.71 0 0 7.82 750.8 36.4 27-0039 Cedar 6/6/2017 11:56 9 8.32 0 0 7.8 753.8 40.8 27-0039 Cedar 6/6/2017 11:55 10 7.83 0 0 7.79 754.9 46.4 0.150 0.115 27-0039 Cedar 6/6/2017 11:54 11 7.25 0 0 7.77 757.9 42.6 27-0039 Cedar 6/6/2017 11:54 12 7.12 0 0 7.78 756.4 43 27-0039 Cedar 6/6/2017 11:53 13 6.9 0 0 7.77 757.9 47.3 27-0039 Cedar 6/6/2017 11:52 14 6.68 0 0 7.77 761.6 57.7 0.251 0.214 131 27-0039 Cedar 6/6/2017 11:51 15 6.76 0 0 7.79 761.9 60.3 27-0039 Cedar 6/6/2017 11:51 16 6.8 0 0 7.84 761.8 57.7 27-0039 Cedar 6/6/2017 11:50 16.3 6.96 0 0 7.9 759.3 78 27-0039 Cedar 6/21/2017 10:50 1.69 0 23.39 116.1 9.63 8.7 654.8 9.3 12.20 <0.500 0.030 0.004 0.703 119 27-0039 Cedar 6/21/2017 10:50 1 23.34 116 9.63 8.68 654.1 9.8 27-0039 Cedar 6/21/2017 10:50 2 23.14 114.8 9.56 8.62 653.2 10.6 27-0039 Cedar 6/21/2017 10:49 3 23 99 8.27 8.38 654.3 11.5 27-0039 Cedar 6/21/2017 10:48 4 15.84 60.4 5.82 7.99 688.1 12.9 27-0039 Cedar 6/21/2017 10:47 5 12.69 8.8 0.91 7.85 705.7 14 0.038 0.004 27-0039 Cedar 6/21/2017 10:46 6 11.06 0 0 7.82 718.9 16.8 27-0039 Cedar 6/21/2017 10:45 7 9.92 0 0 7.81 724.4 18.3 27-0039 Cedar 6/21/2017 10:43 8 8.88 0 0 7.79 728.5 23.6 27-0039 Cedar 6/21/2017 10:41 9 8.21 0 0 7.77 732 29.5 27-0039 Cedar 6/21/2017 10:41 10 7.83 0 0 7.76 734.5 33 0.174 0.145 27-0039 Cedar 6/21/2017 10:40 11 7.47 0 0 7.76 735.1 37.1 27-0039 Cedar 6/21/2017 10:39 12 7.23 0 0 7.76 736.8 41.9 27-0039 Cedar 6/21/2017 10:38 13 7.04 0 0 7.76 738.7 48.7 27-0039 Cedar 6/21/2017 10:38 14 6.95 0 0 7.76 740.8 55.7 0.350 0.302 132 27-0039 Cedar 6/21/2017 10:36 15 6.88 0 0 7.78 743.7 88.1 27-0039 Cedar 6/21/2017 10:36 15.3 6.93 0 0 7.79 750.1 100.5 27-0039 Cedar 7/11/2017 12:35 1.92 0 25.91 118.4 9.37 8.54 638.4 14.8 8.51 1.28 0.939 0.019 0.004 0.585 0.678 <0.030 118 144 118 11.40 0.373 27-0039 Cedar 7/11/2017 12:35 1 25.86 118.3 9.37 8.52 638.3 16.1 27-0039 Cedar 7/11/2017 12:34 2 25.45 118.8 9.48 8.47 639.5 19.4 27-0039 Cedar 7/11/2017 12:32 3 22.88 102.8 8.61 8.26 644.6 23.5 27-0039 Cedar 7/11/2017 12:31 4 19.19 31.9 2.87 7.78 663.5 28.4 27-0039 Cedar 7/11/2017 12:30 5 14.14 1.3 0.13 7.69 695.8 33.7 0.032 0.005 27-0039 Cedar 7/11/2017 12:30 6 11.7 0 0 7.67 707.4 38.1 27-0039 Cedar 7/11/2017 12:29 7 9.85 0 0 7.65 714.9 42.6 27-0039 Cedar 7/11/2017 12:28 8 8.98 0 0 7.63 719.5 37.3 27-0039 Cedar 7/11/2017 12:27 9 8.29 0 0 7.59 724.6 42.5 27-0039 Cedar 7/11/2017 12:26 10 7.8 0 0 7.57 730.2 47 0.229 0.194 27-0039 Cedar 7/11/2017 12:25 11 7.52 0 0 7.57 730 52.7 27-0039 Cedar 7/11/2017 12:24 12 7.3 0 0 7.57 732.9 61.2
2017 Water Resources Report - Minneapolis Park Recreation Board Page B7 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0039 Cedar 7/11/2017 12:23 13 7.16 0 0 7.58 733.4 72.3 27-0039 Cedar 7/11/2017 12:22 14 7.01 0 0 7.6 741.3 70.8 0.426 0.377 122 11.10 27-0039 Cedar 7/11/2017 12:21 15 6.98 0 0 7.69 745.4 93.8 27-0039 Cedar 7/11/2017 12:20 16 7.78 0 0 7.78 739.6 3000 27-0039 Cedar 7/25/2017 10:56 1.04 0 25.16 114.7 9.24 8.53 635.9 18.6 19.22 3.11 0.023 0.004 0.726 121 27-0039 Cedar 7/25/2017 10:56 1 25.16 114.4 9.22 8.49 634.5 19.7 27-0039 Cedar 7/25/2017 10:55 2 25.1 111.8 9.01 8.4 635.8 21.7 27-0039 Cedar 7/25/2017 10:55 3 25.05 106.5 8.6 8.21 635.7 24.2 27-0039 Cedar 7/25/2017 10:54 4 21.31 4.9 0.42 7.72 667.5 27.6 27-0039 Cedar 7/25/2017 10:54 5 14.92 0 0 7.7 705.4 30.7 0.043 0.005 27-0039 Cedar 7/25/2017 10:53 6 11.73 0 0 7.65 718.6 35.4 27-0039 Cedar 7/25/2017 10:52 7 10.18 0 0 7.64 723.7 36.8 27-0039 Cedar 7/25/2017 10:52 8 8.88 0 0 7.61 728.7 41.7 27-0039 Cedar 7/25/2017 10:51 9 8.25 0 0 7.59 734 46.6 27-0039 Cedar 7/25/2017 10:50 10 7.83 0 0 7.58 736.6 54.7 0.289 0.245 27-0039 Cedar 7/25/2017 10:50 11 7.66 0 0 7.58 738.2 58.9 27-0039 Cedar 7/25/2017 10:49 12 7.4 0 0 7.57 741.7 69 27-0039 Cedar 7/25/2017 10:48 13 7.23 0 0 7.57 744.3 68.2 27-0039 Cedar 7/25/2017 10:48 14 7.03 0 0 7.58 749 72 0.483 0.434 131 27-0039 Cedar 7/25/2017 10:47 15 7.05 0 0 7.59 748.9 78.5 27-0039 Cedar 7/25/2017 10:46 16 7.05 0 0 7.63 752.4 78.9 27-0039 Cedar 7/25/2017 10:45 16.4 7.13 0 0 7.72 751 102.1 27-0039 Cedar 8/8/2017 11:30 0.52 0 24.23 144.5 11.93 8.7 629.7 23.7 28.44 3.65 <0.500 0.036 0.005 0.676 121 1.00 27-0039 Cedar 8/8/2017 11:30 1 23.96 146 12.11 8.67 628.7 25.6 27-0039 Cedar 8/8/2017 11:29 2 22.97 127.1 10.74 8.31 629.8 31.7 27-0039 Cedar 8/8/2017 11:28 3 22.4 67.8 5.79 7.93 636.9 35.3 27-0039 Cedar 8/8/2017 11:28 4 21.23 13.5 1.18 7.82 656.4 38 27-0039 Cedar 8/8/2017 11:27 5 15.33 0 0 7.76 709.1 41.8 0.050 0.005 27-0039 Cedar 8/8/2017 11:27 6 12.24 0 0 7.74 727.2 43.7 27-0039 Cedar 8/8/2017 11:26 7 10.38 0 0 7.73 732.1 46.5 27-0039 Cedar 8/8/2017 11:26 8 8.97 0 0 7.7 739.2 51.2 27-0039 Cedar 8/8/2017 11:25 9 8.4 0 0 7.69 742.8 57 27-0039 Cedar 8/8/2017 11:25 10 7.98 0 0 7.67 745.9 58.7 0.279 0.239 27-0039 Cedar 8/8/2017 11:24 11 7.67 0 0 7.68 749.2 63.4 27-0039 Cedar 8/8/2017 11:24 12 7.35 0 0 7.68 754.7 68.1 27-0039 Cedar 8/8/2017 11:23 13 7.22 0 0 7.69 757.7 75.9 27-0039 Cedar 8/8/2017 11:23 14 7.06 0 0 7.69 763.9 73.2 0.491 0.465 135 27-0039 Cedar 8/8/2017 11:22 15 7.14 0 0 7.74 764.2 86.9 27-0039 Cedar 8/8/2017 11:21 15.3 7.03 0 0 7.82 766.2 74.9 27-0039 Cedar 8/22/2017 11:13 0.71 0 22.53 105.1 8.91 8.28 596.3 13.5 34.60 2.82 0.033 0.008 1.050 113 27-0039 Cedar 8/22/2017 11:13 1 22.41 104.5 8.88 8.24 596.6 14.3 27-0039 Cedar 8/22/2017 11:12 2 22.38 104.3 8.87 8.17 596.4 15.3 27-0039 Cedar 8/22/2017 11:11 3 21.95 77.5 6.64 7.87 596.7 17.7 27-0039 Cedar 8/22/2017 11:11 4 20.92 23.4 2.05 7.7 614.1 20 27-0039 Cedar 8/22/2017 11:10 5 17.97 0 0 7.61 700.1 22.3 0.038 0.005 27-0039 Cedar 8/22/2017 11:09 6 13.18 0 0 7.59 728.6 25.5 27-0039 Cedar 8/22/2017 11:09 7 10.79 0 0 7.57 735.5 30.5 27-0039 Cedar 8/22/2017 11:08 8 9.62 0 0 7.56 738.9 35.4 27-0039 Cedar 8/22/2017 11:07 9 8.52 0 0 7.54 745.9 38.3 27-0039 Cedar 8/22/2017 11:07 10 8.16 0 0 7.54 750.9 44.3 0.306 0.286 27-0039 Cedar 8/22/2017 11:06 11 7.88 0 0 7.54 754 46.9 27-0039 Cedar 8/22/2017 11:05 12 7.65 0 0 7.56 754.4 54.6 27-0039 Cedar 8/22/2017 11:04 13 7.38 0 0 7.57 761.6 62.4 27-0039 Cedar 8/22/2017 11:04 14 7.29 0 0 7.59 765 68.6 0.465 0.445 117 27-0039 Cedar 8/22/2017 11:02 15 7.21 0 0 7.66 768.3 72.9 27-0039 Cedar 9/12/2017 9:32 0.8 0 20.98 109.6 9.59 7.84 605.1 10.7 22.60 2.08 2.250 0.032 0.005 1.004 117 27-0039 Cedar 9/12/2017 9:31 1 20.61 105.5 9.29 7.73 603.8 11.9 27-0039 Cedar 9/12/2017 9:30 2 19.87 87.1 7.79 7.6 604.3 13.8 27-0039 Cedar 9/12/2017 9:30 3 19.7 79.4 7.12 7.51 604.8 15.8 27-0039 Cedar 9/12/2017 9:29 4 19.38 72.7 6.56 7.43 605.7 18 27-0039 Cedar 9/12/2017 9:28 5 18.18 19.6 1.81 7.32 623.6 20.4 0.029 0.004 27-0039 Cedar 9/12/2017 9:27 6 14.42 0.2 0.02 7.22 722.5 23
2017 Water Resources Report - Minneapolis Park Recreation Board Page B8 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0039 Cedar 9/12/2017 9:27 7 11.14 0 0 7.21 734.6 26.5 27-0039 Cedar 9/12/2017 9:26 8 9.66 0.1 0.01 7.2 741.7 31.6 27-0039 Cedar 9/12/2017 9:25 9 8.8 0 0 7.18 748.8 37.3 27-0039 Cedar 9/12/2017 9:24 10 8.29 0 0 7.18 754.8 44.2 0.336 0.300 27-0039 Cedar 9/12/2017 9:23 11 7.98 0 0 7.19 758.8 51.8 27-0039 Cedar 9/12/2017 9:22 13 7.53 0 0 7.19 765.7 57.8 27-0039 Cedar 9/12/2017 9:21 14 7.42 0.1 0.01 7.22 772.5 68.3 0.501 0.467 136 27-0039 Cedar 9/12/2017 9:20 14.7 7.61 0 0 7.27 778.6 76.4 27-0039 Cedar 9/26/2017 11:22 1.32 0 21.55 93.7 8.06 8.14 593.9 13.75 3.36 0.035 0.003 0.905 103 27-0039 Cedar 9/26/2017 11:21 1 21.56 93.3 8.02 8.1 593.9 27-0039 Cedar 9/26/2017 11:20 2 21.56 93.2 8.01 8.03 593.6 27-0039 Cedar 9/26/2017 11:18 3 21.49 80.4 6.93 7.81 593.7 27-0039 Cedar 9/26/2017 11:17 4 19.76 11.3 1.01 7.24 595.4 27-0039 Cedar 9/26/2017 11:16 5 17.89 1.4 0.13 7.18 621.7 0.035 0.003 27-0039 Cedar 9/26/2017 11:14 6 13.92 1.2 0.12 6.98 715.5 27-0039 Cedar 9/26/2017 11:13 7 11.37 0.9 0.1 6.91 719 27-0039 Cedar 9/26/2017 11:11 8 9.56 1.1 0.12 6.85 724.8 27-0039 Cedar 9/26/2017 11:09 9 8.7 1.2 0.14 6.79 732.1 27-0039 Cedar 9/26/2017 11:08 10 8.32 1.1 0.12 6.76 734.9 0.346 0.301 27-0039 Cedar 9/26/2017 11:06 11 8.01 1.2 0.14 6.75 738.2 27-0039 Cedar 9/26/2017 11:04 12 7.79 1.2 0.14 6.72 741.4 27-0039 Cedar 9/26/2017 11:03 13 7.63 1.3 0.16 6.72 745.1 27-0039 Cedar 9/26/2017 11:02 14 7.62 1.5 0.16 6.72 745.2 0.533 0.484 122 27-0039 Cedar 9/26/2017 11:01 15 7.51 1.6 0.19 6.73 747.8 27-0039 Cedar 9/26/2017 10:59 16 7.5 2 0.23 6.77 748.3 27-0039 Cedar 11/13/2017 10:20 2.8 0 4.29 54.3 7 7.57 648.4 7 6.49 1.59 4.070 0.074 0.040 1.090 1.180 0.118 139 164 114 9.99 0.799 27-0039 Cedar 11/13/2017 10:20 1 4.29 54.6 7.04 7.55 648.6 9.2 27-0039 Cedar 11/13/2017 10:19 2 4.27 54.1 6.97 7.53 648.5 18.7 27-0039 Cedar 11/13/2017 10:18 3 4.27 54.2 7 7.52 648.9 27.5 27-0039 Cedar 11/13/2017 10:17 4 4.25 53.9 6.95 7.51 648.1 51.3 27-0039 Cedar 11/13/2017 10:16 5 4.25 53.9 6.95 7.5 648.4 1.1 0.073 0.043 27-0039 Cedar 11/13/2017 10:14 6 4.23 53.4 6.9 7.48 648.3 1.2 27-0039 Cedar 11/13/2017 10:14 7 4.23 53.3 6.88 7.47 648.4 1.2 27-0039 Cedar 11/13/2017 10:13 8 4.23 53.5 6.9 7.45 648.3 1.1 27-0039 Cedar 11/13/2017 10:13 9 4.24 53.4 6.89 7.44 648.4 1.1 27-0039 Cedar 11/13/2017 10:12 10 4.23 53.5 6.91 7.42 648.8 1 0.077 0.041 27-0039 Cedar 11/13/2017 10:11 11 4.25 53.4 6.9 7.41 648.2 1 27-0039 Cedar 11/13/2017 10:10 12 4.25 53.6 6.92 7.38 647.9 1 27-0039 Cedar 11/13/2017 10:09 13 4.23 53.6 6.92 7.36 648 1 27-0039 Cedar 11/13/2017 10:08 14 4.24 53.7 6.93 7.34 647.8 0.9 0.076 0.041 114 9.92 27-0039 Cedar 11/13/2017 10:08 15 4.2 53.4 6.9 7.33 649 1.1 27-0039 Cedar 11/13/2017 10:07 16 4.2 52.9 6.84 7.3 648 1.3 27-0039 Cedar 11/13/2017 10:07 17 4.17 48.8 6.31 7.29 648.2 865 27-0022 Diamond 1/31/2017 11:15 0 0.31 36.1 5.05 6.98 1729 0 3.20 1.34 2.580 0.136 0.030 1.210 1.330 0.180 70 88 541 8.90 27-0022 Diamond 1/31/2017 11:13 0.7 2.01 4.9 0.65 6.87 4504 48 27-0022 Diamond 4/11/2017 12:27 0 9.09 75 8.51 7.57 1358 1.4 7.37 3.25 <0.500 0.072 0.004 0.608 0.674 0.077 71 88 388 8.49 <0.250 27-0022 Diamond 4/11/2017 12:27 0.3 9.06 75.3 8.55 7.58 1357 1.8 27-0022 Diamond 5/8/2017 10:44 0 16.59 96 9.15 8.47 1043 6.3 8.61 6.46 0.696 0.064 0.009 0.915 0.959 <0.030 63 64 517 8.57 <0.250 27-0022 Diamond 5/8/2017 10:44 0.5 16.41 97.3 9.31 8.52 1043 101.5 27-0022 Diamond 5/23/2017 9:35 0 14.95 111.5 10.94 8.38 702.1 0 5.77 1.43 0.039 0.005 <0.500 185 27-0022 Diamond 5/23/2017 9:34 0.7 14.55 102.8 10.18 8.23 658.6 32.2 27-0022 Diamond 6/8/2017 9:08 0 23.62 89.8 7.43 8.98 797.5 0 22.64 9.86 0.671 0.064 0.015 0.718 206 27-0022 Diamond 6/8/2017 9:07 0.5 23.02 48 4.01 8.74 796.4 88.5 27-0022 Diamond 6/20/2017 9:33 0 20.72 24.9 2.18 7.86 484.4 0 13.00 9.60 0.105 0.008 0.703 119 27-0022 Diamond 7/14/2017 9:49 0 22.01 37.2 3.21 8.38 635.5 0 10.94 5.29 0.640 0.033 0.004 0.598 0.660 <0.030 59 58 150 5.53 0.290 27-0022 Diamond 7/14/2017 9:48 0.4 21.49 9.3 0.81 8.48 611 4.6 27-0022 Diamond 7/26/2017 9:41 0 23.82 9.5 0.78 8.52 166.2 0 43.17 11.35 0.110 0.007 0.893 27 27-0022 Diamond 7/26/2017 9:41 0.4 23.6 1.3 0.11 8.45 274.3 0 27-0022 Diamond 8/9/2017 9:18 0 21.79 31.1 2.68 8.35 444.9 0 23.52 9.41 0.846 0.064 0.006 0.585 103 6.00 27-0022 Diamond 8/23/2017 9:33 0 20 38.7 3.46 8.18 269.6 0 10.47 3.74 0.042 0.006 <0.500 62 27-0022 Diamond 8/23/2017 9:33 0.3 19.6 26 2.34 8.21 266.2 0 27-0022 Diamond 9/21/2017 10:36 0 19.39 40.1 3.61 8.44 305.7 0 10.92 2.55 <0.500 0.049 0.004 <0.500 52
2017 Water Resources Report - Minneapolis Park Recreation Board Page B9 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0022 Diamond 9/25/2017 9:25 0 21.94 7.91 320.2 0 27.03 6.37 0.066 0.004 0.580 70 27-0022 Diamond 11/7/2017 9:32 0 2.41 102.3 15.33 8 329.8 0 26.17 2.62 <0.500 0.048 0.004 <0.500 0.621 0.034 66 58 68 5.66 <0.250 27-0016 Harriet 1/18/2017 10:39 0 0.98 83.7 11.61 7.92 644.3 219.1 2.10 1.45 0.537 0.069 0.060 0.865 0.977 0.172 121 144 132 7.44 27-0016 Harriet 1/18/2017 10:39 1 1.94 84.6 11.41 7.9 640.1 0 27-0016 Harriet 1/18/2017 10:38 2 1.93 84.9 11.47 7.9 640.3 0 27-0016 Harriet 1/18/2017 10:37 3 1.94 86 11.61 7.9 640.2 0 27-0016 Harriet 1/18/2017 10:37 4 1.94 85.4 11.53 7.89 640.5 0 27-0016 Harriet 1/18/2017 10:36 5 1.95 84.6 11.42 7.89 640.2 0 27-0016 Harriet 1/18/2017 10:35 6 1.98 83.1 11.2 7.87 639.8 0 0.071 0.061 27-0016 Harriet 1/18/2017 10:35 7 2.14 81.3 10.92 7.84 637.5 0 27-0016 Harriet 1/18/2017 10:34 8 2.3 80.2 10.72 7.81 638.4 0 27-0016 Harriet 1/18/2017 10:33 9 2.35 80.7 10.77 7.8 641.2 0 27-0016 Harriet 1/18/2017 10:33 10 2.44 79 10.52 7.76 643.1 0 27-0016 Harriet 1/18/2017 10:32 11 2.49 75.4 10.03 7.71 644.6 0 27-0016 Harriet 1/18/2017 10:31 12 2.55 68.7 9.12 7.66 648.3 0 0.069 0.059 27-0016 Harriet 1/18/2017 10:31 13 2.7 63.1 8.35 7.6 650 0 27-0016 Harriet 1/18/2017 10:30 14 2.86 40.5 5.34 7.48 652.9 0 27-0016 Harriet 1/18/2017 10:29 15 2.92 37.1 4.88 7.44 655.6 0 0.097 0.089 27-0016 Harriet 1/18/2017 10:28 16 2.95 27.2 3.58 7.38 661.2 0 27-0016 Harriet 1/18/2017 10:28 17 3.06 15 1.96 7.33 663.9 0 27-0016 Harriet 1/18/2017 10:27 18 3.06 9.4 1.23 7.31 668.3 0 27-0016 Harriet 1/18/2017 10:26 19 3.09 6.6 0.87 7.3 671.7 0 27-0016 Harriet 1/18/2017 10:25 20 3.13 5.1 0.67 7.28 677.9 0 0.186 0.164 136 7.52 27-0016 Harriet 1/18/2017 10:24 21 3.2 3.9 0.51 7.26 685.1 0 27-0016 Harriet 1/18/2017 10:24 22 3.29 5.7 0.74 7.26 697.4 0 27-0016 Harriet 1/18/2017 10:23 23 3.27 15.4 2 7.26 703.2 0 27-0016 Harriet 1/18/2017 10:22 24 3.47 3.5 0.45 7.22 708.2 2.8 27-0016 Harriet 1/18/2017 10:22 24.5 3.62 2.1 0.27 7.18 711.8 6 27-0016 Harriet 4/19/2017 9:59 5.15 0 9.29 102.6 11.56 8.53 636.2 0 2.24 1.20 <0.500 0.058 0.028 0.674 0.728 0.096 120 140 120 8.25 <0.250 27-0016 Harriet 4/19/2017 9:58 1 9.25 102.7 11.59 8.53 636.1 0 27-0016 Harriet 4/19/2017 9:57 2 9.22 102.8 11.61 8.53 636 8.9 27-0016 Harriet 4/19/2017 9:57 3 9.19 102.5 11.58 8.53 635.9 0 27-0016 Harriet 4/19/2017 9:56 4 9.16 102.5 11.59 8.52 636.1 0 27-0016 Harriet 4/19/2017 9:55 5 9.16 102.6 11.6 8.52 636.3 0 27-0016 Harriet 4/19/2017 9:54 6 9.13 102.5 11.6 8.52 636 0 0.068 0.027 27-0016 Harriet 4/19/2017 9:53 7 8.96 101.7 11.56 8.5 636.4 0 27-0016 Harriet 4/19/2017 9:52 8 8.02 99.7 11.58 8.46 637.3 0 27-0016 Harriet 4/19/2017 9:51 9 7.45 96.5 11.37 8.43 637.9 0 27-0016 Harriet 4/19/2017 9:50 10 6.99 95.4 11.38 8.4 638.1 0 27-0016 Harriet 4/19/2017 9:49 11 6.82 94.4 11.3 8.39 638.8 0 27-0016 Harriet 4/19/2017 9:48 12 6.72 94.3 11.32 8.38 638.7 0 0.072 0.033 27-0016 Harriet 4/19/2017 9:47 13 6.69 93.8 11.26 8.37 638.7 0 27-0016 Harriet 4/19/2017 9:46 14 6.6 93.4 11.24 8.36 638.8 0 27-0016 Harriet 4/19/2017 9:45 15 6.51 93.4 11.27 8.35 638.9 0 0.052 0.029 27-0016 Harriet 4/19/2017 9:45 16 6.46 92.5 11.18 8.34 640.4 0 27-0016 Harriet 4/19/2017 9:43 17 6.39 92.3 11.17 8.31 639.6 0 27-0016 Harriet 4/19/2017 9:43 18 6.38 90.5 10.96 8.29 639.2 0 27-0016 Harriet 4/19/2017 9:42 19 6.39 90.8 10.99 8.28 639.3 0 27-0016 Harriet 4/19/2017 9:41 20 6.39 90.4 10.94 8.28 639 0 0.075 0.044 120 7.99 27-0016 Harriet 4/19/2017 9:40 21 6.35 89.6 10.85 8.26 639 0 27-0016 Harriet 4/19/2017 9:39 22 6.35 89.5 10.84 8.25 638.7 0 27-0016 Harriet 4/19/2017 9:38 23 6.36 89.5 10.84 8.24 639.2 0 27-0016 Harriet 4/19/2017 9:37 24 6.4 89.6 10.84 8.22 638.2 5.4 27-0016 Harriet 5/10/2017 9:58 8.01 0 14.75 112.4 11.11 8.55 632 2.1 3.07 <0.500 0.640 0.039 0.011 0.534 0.658 0.081 122 132 128 8.50 0.518 27-0016 Harriet 5/10/2017 9:57 1 14.33 112.4 11.21 8.53 632.2 2.3 27-0016 Harriet 5/10/2017 9:57 2 14.08 113 11.34 8.54 632.3 2.4 27-0016 Harriet 5/10/2017 9:56 3 13.46 111.4 11.33 8.5 631.7 2.6 27-0016 Harriet 5/10/2017 9:55 4 12.73 108.4 11.21 8.44 631.2 2.9 27-0016 Harriet 5/10/2017 9:53 5 11.5 99.4 10.56 8.33 630 3 27-0016 Harriet 5/10/2017 9:53 6 10.16 89.9 9.86 8.24 630.9 3.1 0.045 0.023 27-0016 Harriet 5/10/2017 9:52 7 9.73 87.2 9.66 8.21 632 3.2 27-0016 Harriet 5/10/2017 9:51 8 9.4 82.9 9.26 8.16 631.3 3.3
2017 Water Resources Report - Minneapolis Park Recreation Board Page B10 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0016 Harriet 5/10/2017 9:49 9 9.22 82.4 9.24 8.15 631.7 3.4 27-0016 Harriet 5/10/2017 9:47 10 9.03 77.5 8.74 8.09 632.2 3.7 27-0016 Harriet 5/10/2017 9:44 11 8.84 72.2 8.17 8.03 633.7 4.2 27-0016 Harriet 5/10/2017 9:42 12 8.71 69.2 7.86 8 633.9 4.7 0.066 0.048 27-0016 Harriet 5/10/2017 9:41 13 8.31 66 7.56 7.97 634.6 5 27-0016 Harriet 5/10/2017 9:38 14 7.96 58.2 6.72 7.9 636.1 5.8 27-0016 Harriet 5/10/2017 9:37 15 7.89 55.6 6.43 7.89 636.9 6.2 0.079 0.061 27-0016 Harriet 5/10/2017 9:35 16 7.74 51.4 5.97 7.86 637.4 6.7 27-0016 Harriet 5/10/2017 9:33 17 7.67 50 5.82 7.86 637.6 7.4 27-0016 Harriet 5/10/2017 9:31 18 7.63 48.8 5.69 7.85 638.7 8.1 27-0016 Harriet 5/10/2017 9:31 19 7.52 44.6 5.21 7.84 638.8 8.1 27-0016 Harriet 5/10/2017 9:30 20 7.51 44.2 5.17 7.84 639.3 8.6 0.102 0.082 128 7.63 27-0016 Harriet 5/10/2017 9:28 21 7.5 42.2 4.93 7.85 639 8 27-0016 Harriet 5/10/2017 9:26 22 7.5 41.1 4.81 7.86 639.2 8.1 27-0016 Harriet 5/10/2017 9:25 23 7.49 39.8 4.66 7.87 642.9 9 27-0016 Harriet 5/10/2017 9:23 24 7.54 37.4 4.36 7.85 640.2 3.1 27-0016 Harriet 5/25/2017 10:11 5.95 0 15.07 105.1 10.26 8.55 617.8 0.3 4.97 0.89 0.040 0.006 0.649 138 27-0016 Harriet 5/25/2017 10:09 2 14.85 104.8 10.27 8.52 618 1.1 27-0016 Harriet 5/25/2017 10:08 3 14.65 100.9 9.93 8.48 617.7 1.5 27-0016 Harriet 5/25/2017 10:07 4 14.28 97.7 9.7 8.43 617.6 1.9 27-0016 Harriet 5/25/2017 10:06 5 13.87 89.5 8.96 8.34 618.9 2.3 27-0016 Harriet 5/25/2017 10:04 6 12.24 87.5 9.09 8.12 627.2 3.2 0.037 0.016 27-0016 Harriet 5/25/2017 10:03 7 10.13 82.4 8.98 8.05 632.8 3.4 27-0016 Harriet 5/25/2017 10:02 8 9.53 71.7 7.92 7.97 634 3.7 27-0016 Harriet 5/25/2017 10:01 9 9.08 61.1 6.83 7.91 635.2 4 27-0016 Harriet 5/25/2017 10:00 10 8.82 54.7 6.15 7.89 637.3 4.2 27-0016 Harriet 5/25/2017 9:59 11 8.59 48.2 5.45 7.86 637.2 4.3 27-0016 Harriet 5/25/2017 9:58 12 8.43 46.3 5.25 7.86 637.5 4.4 0.110 0.097 27-0016 Harriet 5/25/2017 9:58 13 8.23 41.8 4.77 7.84 638.1 4.6 27-0016 Harriet 5/25/2017 9:57 14 8.09 39.3 4.5 7.84 637.5 4.7 27-0016 Harriet 5/25/2017 9:56 15 7.98 33.4 3.83 7.82 639.4 4.8 0.121 0.107 27-0016 Harriet 5/25/2017 9:55 16 7.95 30.7 3.53 7.82 640.1 4.9 27-0016 Harriet 5/25/2017 9:54 17 7.88 26.4 3.03 7.81 640.1 5.2 27-0016 Harriet 5/25/2017 9:53 18 7.83 20.9 2.41 7.8 641.2 5.2 27-0016 Harriet 5/25/2017 9:52 19 7.81 18.1 2.09 7.8 641.4 5 27-0016 Harriet 5/25/2017 9:51 20 7.79 13.8 1.59 7.79 642.3 5.1 0.174 0.164 133 27-0016 Harriet 5/25/2017 9:51 21 7.75 13.2 1.52 7.79 642.9 4.6 27-0016 Harriet 5/25/2017 9:50 22 7.77 12.4 1.44 7.8 642.8 4.6 27-0016 Harriet 5/25/2017 9:49 23 7.75 8.8 1.02 7.78 644.5 4.1 27-0016 Harriet 5/25/2017 9:48 24 7.79 8.9 1.02 7.79 643.9 2.9 27-0016 Harriet 5/25/2017 9:47 24.2 7.82 6.8 0.79 7.8 643.2 1.8 27-0016 Harriet 6/7/2017 9:12 3.95 0 22.17 122.6 10.5 8.88 630.3 3.8 2.28 0.66 <0.500 0.021 0.004 0.555 126 27-0016 Harriet 6/7/2017 9:12 1 22.09 123.5 10.59 8.86 631.2 3.2 27-0016 Harriet 6/7/2017 9:11 2 21.56 126.7 10.98 8.81 634.9 3.5 27-0016 Harriet 6/7/2017 9:10 3 18.24 121.5 11.25 8.7 626.2 3.8 27-0016 Harriet 6/7/2017 9:10 4 17.01 102.8 9.77 8.53 626.2 4.1 27-0016 Harriet 6/7/2017 9:09 5 15.37 79.5 7.82 8.24 625.9 4.5 27-0016 Harriet 6/7/2017 9:08 6 13.24 70.7 7.28 8.1 630 4.8 0.032 0.011 27-0016 Harriet 6/7/2017 9:07 7 10.96 67.8 7.36 8.02 637.5 5.1 27-0016 Harriet 6/7/2017 9:07 8 9.89 59.9 6.66 7.97 637.4 5.2 27-0016 Harriet 6/7/2017 9:06 9 9.16 43.3 4.91 7.91 639.7 5.5 27-0016 Harriet 6/7/2017 9:05 10 8.85 33.7 3.84 7.88 642.4 5.6 27-0016 Harriet 6/7/2017 9:05 11 8.58 30 3.45 7.87 641.6 5.8 27-0016 Harriet 6/7/2017 9:04 12 8.43 24.9 2.87 7.86 641.9 6 0.143 0.124 27-0016 Harriet 6/7/2017 9:03 13 8.16 17.3 2 7.84 642.5 6.2 27-0016 Harriet 6/7/2017 9:03 14 8.12 11.1 1.28 7.83 643.3 6.4 27-0016 Harriet 6/7/2017 9:02 15 8.01 7 0.82 7.83 644 6.8 0.022 0.003 27-0016 Harriet 6/7/2017 9:01 16 7.98 4.3 0.51 7.83 644.4 7.4 27-0016 Harriet 6/7/2017 9:00 17 7.97 2.1 0.25 7.83 644.2 8.1 27-0016 Harriet 6/7/2017 8:59 18 7.95 0.9 0.1 7.83 645 9.2 27-0016 Harriet 6/7/2017 8:58 19 7.93 0 0 7.83 645.3 8.8 27-0016 Harriet 6/7/2017 8:58 20 7.88 0 0 7.83 645.4 9.6 0.213 0.196 131
2017 Water Resources Report - Minneapolis Park Recreation Board Page B11 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0016 Harriet 6/7/2017 8:57 21 7.89 0 0 7.83 645.2 13.3 27-0016 Harriet 6/7/2017 8:56 22 7.9 0 0 7.83 645.4 7.8 27-0016 Harriet 6/7/2017 8:56 23 7.87 0 0 7.82 645.7 8.3 27-0016 Harriet 6/7/2017 8:55 24 7.89 0 0 7.81 646.1 4.8 27-0016 Harriet 6/7/2017 8:54 24.5 7.89 0 0 7.8 646.4 3.8 27-0016 Harriet 6/23/2017 9:22 3.3 0 22.51 104.1 8.74 8.76 627.6 1.4 9.16 1.92 0.035 0.003 0.648 123 27-0016 Harriet 6/23/2017 9:22 1 22.49 104.2 8.75 8.75 627.6 1.6 27-0016 Harriet 6/23/2017 9:21 2 22.47 104.3 8.76 8.74 627.3 2.2 27-0016 Harriet 6/23/2017 9:20 3 22.48 104.1 8.74 8.73 627.5 2.7 27-0016 Harriet 6/23/2017 9:19 4 22.36 102.6 8.64 8.69 627.4 3.3 27-0016 Harriet 6/23/2017 9:17 5 17.5 52.9 4.91 8.07 626.5 4.2 27-0016 Harriet 6/23/2017 9:17 6 13.12 54.7 5.58 8.05 632.5 4.5 0.038 0.006 27-0016 Harriet 6/23/2017 9:16 7 11.29 51.9 5.51 8.02 638.7 4.7 27-0016 Harriet 6/23/2017 9:15 8 10.1 42.3 4.62 7.99 639.5 5.1 27-0016 Harriet 6/23/2017 9:14 9 9.5 33.3 3.68 7.97 640.4 5.5 27-0016 Harriet 6/23/2017 9:13 10 9.06 20.6 2.31 7.94 642.5 5.8 27-0016 Harriet 6/23/2017 9:12 11 8.78 13.8 1.56 7.94 643.4 6.2 27-0016 Harriet 6/23/2017 9:10 12 8.57 6.7 0.76 7.93 643.7 7 0.182 0.153 27-0016 Harriet 6/23/2017 9:09 13 8.4 0 0 7.93 644.7 8.2 27-0016 Harriet 6/23/2017 9:07 14 8.32 0 0 7.93 644.7 9.2 27-0016 Harriet 6/23/2017 9:06 15 8.22 0 0 7.93 645.4 10.8 0.211 0.190 27-0016 Harriet 6/23/2017 9:05 16 8.17 0 0 7.93 645.8 11.3 27-0016 Harriet 6/23/2017 9:04 17 8.11 0 0 7.93 645.9 11.8 27-0016 Harriet 6/23/2017 9:04 18 8.08 0 0 7.93 646.4 12.2 27-0016 Harriet 6/23/2017 9:03 19 8.06 0 0 7.94 646.5 12.8 27-0016 Harriet 6/23/2017 9:02 20 8.04 0 0 7.93 646.6 13.4 0.246 0.231 128 27-0016 Harriet 6/23/2017 9:02 21 8.04 0 0 7.94 646.9 14.1 27-0016 Harriet 6/23/2017 9:01 22 8.04 0 0 7.94 647.3 15.1 27-0016 Harriet 6/23/2017 8:59 23 8.05 0 0 7.95 647.4 15.6 27-0016 Harriet 6/23/2017 8:56 24 8.08 0 0 8.01 647.6 19.9 27-0016 Harriet 7/13/2017 9:29 3.42 0 25.21 114.2 9.22 8.61 632.7 3.5 4.01 0.57 <0.500 0.022 0.003 <0.500 <0.500 <0.030 113 132 118 8.02 0.350 27-0016 Harriet 7/13/2017 9:28 1 25.17 114.5 9.25 8.59 632.8 4 27-0016 Harriet 7/13/2017 9:28 2 25.15 114.7 9.27 8.57 632.8 4.8 27-0016 Harriet 7/13/2017 9:27 3 25.11 115 9.3 8.53 632.6 5.4 27-0016 Harriet 7/13/2017 9:27 4 25.18 115.2 9.31 8.44 631.3 6.3 27-0016 Harriet 7/13/2017 9:26 5 19.5 72.4 6.53 7.96 634.3 7.4 27-0016 Harriet 7/13/2017 9:24 6 15.42 34.8 3.41 7.75 640.1 8.1 0.035 0.008 27-0016 Harriet 7/13/2017 9:24 7 12.39 33.1 3.47 7.75 642.4 8.9 27-0016 Harriet 7/13/2017 9:23 8 10.32 18.4 2.03 7.72 644.3 9.8 27-0016 Harriet 7/13/2017 9:22 9 9.62 9.8 1.1 7.72 645.4 10.8 27-0016 Harriet 7/13/2017 9:21 10 9.29 2.6 0.29 7.71 646.3 11.8 27-0016 Harriet 7/13/2017 9:20 11 8.89 0 0 7.7 647.4 12.9 27-0016 Harriet 7/13/2017 9:19 12 8.66 0 0 7.7 648.4 13.5 0.203 0.175 27-0016 Harriet 7/13/2017 9:19 13 8.49 0 0 7.69 648.8 13.8 27-0016 Harriet 7/13/2017 9:18 14 8.37 0 0 7.69 649.5 13.8 27-0016 Harriet 7/13/2017 9:18 15 8.29 0 0 7.69 650.3 14.2 0.261 0.247 27-0016 Harriet 7/13/2017 9:17 16 8.24 0 0 7.69 650.6 14.6 27-0016 Harriet 7/13/2017 9:16 17 8.2 0 0 7.69 650.7 15.1 27-0016 Harriet 7/13/2017 9:16 18 8.15 0 0 7.69 651.7 15.3 27-0016 Harriet 7/13/2017 9:15 19 8.13 0 0 7.69 651.8 15.6 27-0016 Harriet 7/13/2017 9:14 20 8.12 0 0 7.7 652.2 14.4 0.306 0.303 122 8.41 27-0016 Harriet 7/13/2017 9:13 21 8.11 0 0 7.71 652.1 14.2 27-0016 Harriet 7/13/2017 9:13 22 8.13 0 0 7.74 651.5 13.9 27-0016 Harriet 7/13/2017 9:12 23 8.23 0 0 7.79 652.6 12.3 27-0016 Harriet 7/13/2017 9:11 24 8.13 0.2 0.02 7.86 651.9 9.6 27-0016 Harriet 7/24/2017 9:40 4.42 0 4.11 0.74 0.022 0.005 <0.500 121 27-0016 Harriet 7/24/2017 9:39 1 25.1 104.5 8.45 8.41 634.5 1.6 27-0016 Harriet 7/24/2017 9:38 2 25.01 103.9 8.41 8.39 634.4 2.7 27-0016 Harriet 7/24/2017 9:37 3 24.92 103.4 8.39 8.32 633.6 3.4 27-0016 Harriet 7/24/2017 9:36 4 24.88 101.9 8.27 8.14 632 4.2 27-0016 Harriet 7/24/2017 9:35 5 21.54 74.2 6.42 7.81 642.3 5 27-0016 Harriet 7/24/2017 9:34 6 16.52 25.6 2.45 7.62 647.1 5.8 0.034 0.004
2017 Water Resources Report - Minneapolis Park Recreation Board Page B12 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0016 Harriet 7/24/2017 9:33 7 12.7 17 1.77 7.6 646.2 6.8 27-0016 Harriet 7/24/2017 9:32 8 10.61 9.9 1.08 7.59 649.4 7.5 27-0016 Harriet 7/24/2017 9:31 9 9.71 0 0 7.58 651.3 8.6 27-0016 Harriet 7/24/2017 9:31 10 9.25 0 0 7.57 653.5 9.5 27-0016 Harriet 7/24/2017 9:30 11 9.04 0 0 7.57 654.4 10.7 27-0016 Harriet 7/24/2017 9:29 12 8.71 0 0 7.56 655.2 11.3 0.227 0.191 27-0016 Harriet 7/24/2017 9:28 13 8.48 0 0 7.55 656.2 10.3 27-0016 Harriet 7/24/2017 9:27 14 8.34 0 0 7.54 656.8 10.5 27-0016 Harriet 7/24/2017 9:26 15 8.24 0 0 7.53 657.7 11.4 0.286 0.264 27-0016 Harriet 7/24/2017 9:25 16 8.22 0 0 7.53 658.3 9.8 27-0016 Harriet 7/24/2017 9:25 17 8.18 0 0 7.53 658.6 17.8 27-0016 Harriet 7/24/2017 9:24 18 8.16 0 0 7.53 658.4 13.2 27-0016 Harriet 7/24/2017 9:23 19 8.13 0 0 7.53 659.2 13.4 27-0016 Harriet 7/24/2017 9:22 20 8.12 0 0 7.53 659.4 25.3 0.352 0.327 121 27-0016 Harriet 7/24/2017 9:21 21 8.09 0 0 7.54 659.8 17.9 27-0016 Harriet 7/24/2017 9:20 22 8.09 0 0 7.56 660 17.2 27-0016 Harriet 7/24/2017 9:19 23 8.2 0 0 7.61 659.7 32.1 27-0016 Harriet 7/24/2017 9:18 23.6 8.54 0 0 7.68 660.4 186 27-0016 Harriet 8/8/2017 9:08 3.49 0 23.49 108 9.04 8.45 627.1 0 7.24 3.10 0.846 0.019 0.005 <0.500 124 1.00 27-0016 Harriet 8/8/2017 9:08 1 23.51 108.2 9.05 8.42 627 0 27-0016 Harriet 8/8/2017 9:07 2 23.43 107.6 9.02 8.39 625.8 0 27-0016 Harriet 8/8/2017 9:06 3 23.23 107.9 9.08 8.33 624.8 0 27-0016 Harriet 8/8/2017 9:05 4 23.09 102.5 8.64 8.21 625.5 0 27-0016 Harriet 8/8/2017 9:04 5 22.57 82.7 7.04 7.98 628.9 0 27-0016 Harriet 8/8/2017 9:03 6 18.97 15.5 1.42 7.72 646.2 0.3 0.026 0.005 27-0016 Harriet 8/8/2017 9:01 7 14.16 2.3 0.23 7.72 648.7 1.5 27-0016 Harriet 8/8/2017 9:00 8 10.89 0.6 0.06 7.73 654.1 2.3 27-0016 Harriet 8/8/2017 8:59 9 10.04 2.9 0.32 7.73 649 11.5 27-0016 Harriet 8/8/2017 8:58 10 9.26 0 0 7.72 652.7 11.7 27-0016 Harriet 8/8/2017 8:57 11 8.94 0 0 7.71 652.7 12.2 27-0016 Harriet 8/8/2017 8:56 12 8.73 0 0 7.7 653.6 12.4 0.234 0.205 27-0016 Harriet 8/8/2017 8:55 13 8.47 0 0 7.7 654.5 11.9 27-0016 Harriet 8/8/2017 8:54 14 8.35 0 0 7.7 655.4 12.3 27-0016 Harriet 8/8/2017 8:54 15 8.32 0 0 7.7 655.9 12.7 0.314 0.297 27-0016 Harriet 8/8/2017 8:53 16 8.2 0 0 7.72 657.1 13.4 27-0016 Harriet 8/8/2017 8:52 17 8.19 0 0 7.73 657.5 13.9 27-0016 Harriet 8/8/2017 8:51 18 8.15 0 0 7.76 658.7 14.7 27-0016 Harriet 8/8/2017 8:50 19 8.14 0 0 7.79 658.9 15.2 27-0016 Harriet 8/8/2017 8:50 20 8.14 0 0 7.8 658.7 15.6 0.386 0.365 131 27-0016 Harriet 8/8/2017 8:49 21 8.1 0 0 7.84 659.3 15.7 27-0016 Harriet 8/8/2017 8:48 22 8.09 0 0 7.88 659.8 14.9 27-0016 Harriet 8/8/2017 8:48 23 8.1 0 0 7.92 659.7 13.8 27-0016 Harriet 8/8/2017 8:47 24 8.09 0 0 7.97 660.4 12.9 27-0016 Harriet 8/8/2017 8:46 24.2 8.24 0 0 8.06 657.6 12 27-0016 Harriet 8/21/2017 10:50 3.69 0 23.99 111.7 9.2 8.57 605.5 0 4.27 0.96 0.020 0.005 0.663 117 27-0016 Harriet 8/21/2017 10:50 1 23.57 113.5 9.42 8.56 604.8 0 27-0016 Harriet 8/21/2017 10:48 2 23.23 113 9.44 8.52 604 0 27-0016 Harriet 8/21/2017 10:47 3 22.85 110.9 9.33 8.47 602.3 0.7 27-0016 Harriet 8/21/2017 10:46 4 22.06 104.6 8.93 8.38 602.5 2.2 27-0016 Harriet 8/21/2017 10:45 5 21.75 96.7 8.3 8.24 605.7 3.9 27-0016 Harriet 8/21/2017 10:42 6 20.46 35.1 3.09 7.85 624.1 7.6 0.023 0.004 27-0016 Harriet 8/21/2017 10:41 7 13.92 1.6 0.16 7.79 676.2 9.1 27-0016 Harriet 8/21/2017 10:40 8 11.51 1.2 0.13 7.8 647.3 10 27-0016 Harriet 8/21/2017 10:39 9 10.4 0.7 0.08 7.81 647.3 11.4 27-0016 Harriet 8/21/2017 10:38 10 9.88 0 0 7.81 649 11.9 27-0016 Harriet 8/21/2017 10:37 11 9.45 0 0 7.8 651.3 12 27-0016 Harriet 8/21/2017 10:35 12 9.08 0 0 7.81 653.2 12.5 0.053 0.018 27-0016 Harriet 8/21/2017 10:34 13 8.77 0.1 0.01 7.81 652.8 13 27-0016 Harriet 8/21/2017 10:33 14 8.54 0 0 7.81 653.6 13.6 27-0016 Harriet 8/21/2017 10:32 15 8.41 0 0 7.82 654.5 13.5 0.299 0.275 27-0016 Harriet 8/21/2017 10:30 16 8.31 0 0 7.83 655.9 14.1 27-0016 Harriet 8/21/2017 10:30 17 8.23 0 0 7.84 657 14.7
2017 Water Resources Report - Minneapolis Park Recreation Board Page B13 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0016 Harriet 8/21/2017 10:29 18 8.2 0 0 7.85 657.8 15.3 27-0016 Harriet 8/21/2017 10:28 19 8.2 0 0 7.87 657.7 16 27-0016 Harriet 8/21/2017 10:27 20 8.23 0 0 7.9 657.8 16.9 0.396 0.383 127 27-0016 Harriet 8/21/2017 10:26 21 8.2 0 0 7.92 658.2 17.5 27-0016 Harriet 8/21/2017 10:24 22 8.22 0 0 7.98 658.6 18.4 27-0016 Harriet 8/21/2017 10:23 23 8.23 0 0 8.02 658.2 18.7 27-0016 Harriet 8/21/2017 10:22 24 8.27 0 0 8.06 659 18.5 27-0016 Harriet 8/21/2017 10:21 24.6 8.91 0 0 8.15 653.9 17.7 27-0016 Harriet 9/13/2017 9:35 3.11 0 21.19 111.4 9.58 8.46 610.2 4.9 3.44 0.86 0.622 0.019 0.004 0.602 122 27-0016 Harriet 9/13/2017 9:35 1 21.2 110.5 9.5 8.44 609.8 5.8 27-0016 Harriet 9/13/2017 9:35 2 21.11 110.4 9.51 8.42 609.1 6.9 27-0016 Harriet 9/13/2017 9:34 3 20.18 105.9 9.3 8.39 610.6 8.1 27-0016 Harriet 9/13/2017 9:33 4 19.66 101.8 9.03 8.32 607.9 10.3 27-0016 Harriet 9/13/2017 9:33 5 19.46 97.7 8.7 8.24 609.6 12.8 27-0016 Harriet 9/13/2017 9:32 6 19.42 92.2 8.21 8.16 607.4 14.2 0.021 0.004 27-0016 Harriet 9/13/2017 9:32 7 17.97 61.7 5.66 8.02 622.2 16.6 27-0016 Harriet 9/13/2017 9:31 8 13.31 0 0 7.92 657.9 20.3 27-0016 Harriet 9/13/2017 9:30 9 10.1 0 0 7.92 653.9 20.5 27-0016 Harriet 9/13/2017 9:30 10 9.24 0 0 7.92 657.2 19.4 27-0016 Harriet 9/13/2017 9:30 11 8.9 0 0 7.93 656.4 18.7 27-0016 Harriet 9/13/2017 9:29 12 8.64 0 0 7.94 657.4 18.6 0.283 0.267 27-0016 Harriet 9/13/2017 9:29 13 8.46 0 0 7.96 658.4 18.7 27-0016 Harriet 9/13/2017 9:29 14 8.39 0 0 7.97 659 18.7 27-0016 Harriet 9/13/2017 9:28 15 8.4 0 0 8.01 658.5 19 0.377 0.366 27-0016 Harriet 9/13/2017 9:28 16 8.33 0 0 8.05 659.9 18.6 27-0016 Harriet 9/13/2017 9:27 17 8.3 0 0 8.08 660.6 18.7 27-0016 Harriet 9/13/2017 9:27 18 8.32 0 0 8.12 661.4 19.1 27-0016 Harriet 9/13/2017 9:26 19 8.33 0 0 8.17 660.6 20.3 27-0016 Harriet 9/13/2017 9:26 20 8.29 0 0 8.21 661.5 23.6 0.418 0.389 127 27-0016 Harriet 9/13/2017 9:26 21 8.3 0 0 8.27 663.4 28.7 27-0016 Harriet 9/13/2017 9:25 22 8.32 0.1 0.01 8.31 662.8 43.6 27-0016 Harriet 9/13/2017 9:25 23 8.66 0.2 0.03 8.41 660.6 15.9 27-0016 Harriet 9/27/2017 11:22 3.4 0 20.66 94.8 8.38 8.43 614.3 5.34 1.39 0.019 0.003 0.595 117 27-0016 Harriet 9/27/2017 11:21 1 20.7 94.8 8.39 8.37 613.8 27-0016 Harriet 9/27/2017 11:21 2 20.67 90.2 7.98 8.27 610.3 27-0016 Harriet 9/27/2017 11:20 3 20.61 90.7 8.04 8.18 612.1 27-0016 Harriet 9/27/2017 11:20 4 20.49 85.9 7.62 8.03 611.9 27-0016 Harriet 9/27/2017 11:20 5 20.51 78.4 6.96 7.79 612.5 27-0016 Harriet 9/27/2017 11:19 6 19.69 54.6 4.93 7.47 618.6 0.020 0.003 27-0016 Harriet 9/27/2017 11:19 7 18.11 11.8 1.1 7.2 631 27-0016 Harriet 9/27/2017 11:18 8 14.1 2.6 0.27 7.11 657.8 27-0016 Harriet 9/27/2017 11:18 9 10.84 2.4 0.26 7.1 661.7 27-0016 Harriet 9/27/2017 11:18 10 9.75 2.5 0.29 7.07 661.8 27-0016 Harriet 9/27/2017 11:17 11 9.26 2.6 0.29 7.06 662.5 27-0016 Harriet 9/27/2017 11:17 12 8.88 2.6 0.3 7.04 663.6 0.278 0.240 27-0016 Harriet 9/27/2017 11:16 13 8.68 2.8 0.32 7.03 664.4 27-0016 Harriet 9/27/2017 11:16 14 8.58 2.9 0.34 7.02 665.6 27-0016 Harriet 9/27/2017 11:16 15 8.51 3.1 0.35 7.04 666.6 0.369 0.366 27-0016 Harriet 9/27/2017 11:15 16 8.42 3.2 0.37 7.02 667.8 27-0016 Harriet 9/27/2017 11:15 17 8.39 3.3 0.38 7.04 670.1 27-0016 Harriet 9/27/2017 11:15 18 8.35 3.4 0.39 7.05 672.1 27-0016 Harriet 9/27/2017 11:14 19 8.34 3.9 0.45 7.06 672.2 27-0016 Harriet 9/27/2017 11:13 20 8.34 4.3 0.5 7.1 673.1 0.447 0.411 127 27-0016 Harriet 9/27/2017 11:13 21 8.33 4.6 0.54 7.12 672.9 27-0016 Harriet 9/27/2017 11:12 22 8.34 6 0.7 7.22 673.5 27-0016 Harriet 9/27/2017 11:12 23 8.4 7.1 0.82 7.26 673.1 27-0016 Harriet 9/27/2017 11:11 24 8.37 9.6 1.11 7.35 672.9 27-0016 Harriet 11/13/2017 12:06 4.39 0 5.56 67.8 8.46 8.03 630.2 0 6.94 1.12 0.648 0.093 0.070 0.807 0.872 0.075 122 138 119 7.07 0.459 27-0016 Harriet 11/13/2017 12:07 1 5.55 67.2 8.38 8.03 629.8 0 27-0016 Harriet 11/13/2017 12:08 2 5.55 67 8.36 8.03 630.7 0 27-0016 Harriet 11/13/2017 12:08 3 5.55 66.7 8.32 8.02 630.2 0.1 27-0016 Harriet 11/13/2017 12:09 4 5.55 66.9 8.34 8.02 630.2 0.2
2017 Water Resources Report - Minneapolis Park Recreation Board Page B14 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0016 Harriet 11/13/2017 12:10 5 5.55 66.8 8.34 8.02 631 0.2 27-0016 Harriet 11/13/2017 12:11 6 5.55 66.9 8.36 8.01 630.3 0.2 0.096 0.070 27-0016 Harriet 11/13/2017 12:12 7 5.53 66.8 8.34 8.01 630.3 0.3 27-0016 Harriet 11/13/2017 12:13 8 5.53 66.2 8.26 8.01 630.5 0.3 27-0016 Harriet 11/13/2017 12:13 9 5.52 66.3 8.28 8.01 630.5 0.3 27-0016 Harriet 11/13/2017 12:14 10 5.51 66.3 8.29 8 630.5 0.3 27-0016 Harriet 11/13/2017 12:14 11 5.5 65.4 8.18 8 630.5 0.4 27-0016 Harriet 11/13/2017 12:15 12 5.49 65.5 8.18 8 630.5 0.4 0.091 0.072 27-0016 Harriet 11/13/2017 12:16 13 5.5 65.3 8.16 7.99 630.7 0.4 27-0016 Harriet 11/13/2017 12:16 14 5.49 65.4 8.17 8 630.9 0.4 27-0016 Harriet 11/13/2017 12:17 15 5.49 65.1 8.14 7.99 631.3 0.4 0.094 0.071 27-0016 Harriet 11/13/2017 12:17 16 5.49 65.3 8.17 7.99 631 0.4 27-0016 Harriet 11/13/2017 12:18 17 5.49 65.2 8.15 7.99 630.7 0.4 27-0016 Harriet 11/13/2017 12:18 18 5.49 65.2 8.14 7.99 630.6 0.4 27-0016 Harriet 11/13/2017 12:19 19 5.49 65.2 8.15 7.99 630.8 0.5 27-0016 Harriet 11/13/2017 12:19 20 5.48 65.3 8.16 7.98 631.4 0.5 0.093 0.072 124 7.17 27-0016 Harriet 11/13/2017 12:20 21 5.48 65.3 8.17 7.98 630.8 0.6 27-0016 Harriet 11/13/2017 12:20 22 5.48 65.3 8.16 7.98 630.8 0.6 27-0016 Harriet 11/13/2017 12:21 23 5.47 65.5 8.19 7.98 630.7 0.6 27-0016 Harriet 11/13/2017 12:21 24.1 5.47 65.3 8.17 7.98 630.8 0.6 27-0018 Hiawatha 1/31/2017 10:45 0 0.09 79.1 11.17 7.53 1052 0 4.80 0.77 8.100 0.091 0.043 1.460 1.600 0.401 177 220 262 12.87 27-0018 Hiawatha 1/31/2017 10:44 1 0.66 73.3 10.18 7.49 1185 0 27-0018 Hiawatha 1/31/2017 10:44 2 0.64 78.7 10.93 7.53 1303 2.4 27-0018 Hiawatha 1/31/2017 10:42 3 0.97 52 7.16 7.29 1573 0 27-0018 Hiawatha 1/31/2017 10:41 4 1.48 29.1 3.94 7.21 1878 0 0.080 0.041 380 13.49 27-0018 Hiawatha 1/31/2017 10:40 5 1.56 29.6 3.99 7.17 2397 0.4 27-0018 Hiawatha 1/31/2017 10:39 6 1.63 24.8 3.34 7.15 2463 12.3 27-0018 Hiawatha 4/12/2017 10:18 1.05 0 10.13 98.2 10.91 8.23 524 84.1 13.80 3.12 1.690 0.054 0.003 0.903 0.923 0.053 148 168 72 7.13 <0.250 27-0018 Hiawatha 4/12/2017 10:18 1 10.13 97.4 10.82 8.22 525.6 90.1 27-0018 Hiawatha 4/12/2017 10:17 2 10.08 96 10.68 8.19 525.8 20.3 27-0018 Hiawatha 4/12/2017 10:16 3 9.93 92.4 10.32 8.12 524.6 3.9 27-0018 Hiawatha 4/12/2017 10:15 4 9.87 88.5 9.89 8.04 525 7.8 0.051 0.003 72 7.39 27-0018 Hiawatha 4/12/2017 10:15 5 9.61 81.2 9.14 7.95 529.8 8 27-0018 Hiawatha 4/12/2017 10:14 6 8.32 72 8.35 7.85 645.5 4 27-0018 Hiawatha 4/12/2017 10:13 7 4.14 58.7 7.55 7.7 940.5 0.8 27-0018 Hiawatha 4/12/2017 10:11 7.3 3.86 34.3 4.45 7.59 1075 1.5 27-0018 Hiawatha 5/11/2017 10:47 1.52 0 16.25 88.1 8.5 8.11 514.3 6.6 9.12 3.08 1.860 0.044 <0.003 0.695 0.658 <0.030 141 156 80 7.34 0.281 27-0018 Hiawatha 5/11/2017 10:46 1 16.17 88.2 8.52 8.11 514.1 7.6 27-0018 Hiawatha 5/11/2017 10:46 2 16.03 86 8.33 8.08 514.2 10.2 27-0018 Hiawatha 5/11/2017 10:45 3 15.92 83.2 8.07 8.05 514.9 15 27-0018 Hiawatha 5/11/2017 10:44 4 15.72 79.2 7.73 8.01 518.9 21.4 0.045 <0.003 85 6.90 27-0018 Hiawatha 5/11/2017 10:43 5 12 37.6 3.98 7.88 504.8 38.7 27-0018 Hiawatha 5/11/2017 10:43 5.5 10.33 52.1 5.73 7.91 494.4 106 27-0018 Hiawatha 5/26/2017 10:22 2.1 0 15.79 93.2 8.96 8.15 478.3 0 7.90 1.54 0.041 0.007 0.719 81 27-0018 Hiawatha 5/26/2017 10:21 1 15.7 92.4 8.9 8.16 478.4 0 27-0018 Hiawatha 5/26/2017 10:21 2 15.51 89.8 8.68 8.15 478 0 27-0018 Hiawatha 5/26/2017 10:20 3 15.4 87.5 8.48 8.15 478.2 0 27-0018 Hiawatha 5/26/2017 10:19 4 15.25 86.6 8.42 8.17 476.8 0 0.031 0.008 86 27-0018 Hiawatha 5/26/2017 10:18 5 14.73 77.7 7.64 8.21 474.3 37.6 27-0018 Hiawatha 6/9/2017 11:44 2.6 0 24.44 96.7 7.86 8.01 485.7 7.1 5.00 1.80 2.100 0.042 0.009 0.726 69 27-0018 Hiawatha 6/9/2017 11:44 1 23.83 94.1 7.74 7.99 483.8 7.6 27-0018 Hiawatha 6/9/2017 11:43 2 23.66 92.3 7.62 7.97 483.3 9.5 27-0018 Hiawatha 6/9/2017 11:41 3 23.45 87.1 7.21 7.94 483.5 12.5 27-0018 Hiawatha 6/9/2017 11:40 4 22.93 72.1 6.03 7.86 485 19.4 0.038 0.013 69 27-0018 Hiawatha 6/9/2017 11:37 5 18.21 0.1 0.01 7.72 491.1 39.9 27-0018 Hiawatha 6/9/2017 11:36 6 12.94 0.7 0.08 7.83 467.9 45.6 27-0018 Hiawatha 6/9/2017 11:34 7.3 9.35 0 0 7.79 639.9 21.8 27-0018 Hiawatha 6/27/2017 12:37 1.57 0 20.66 106.9 9.43 7.97 473.5 43.4 20.60 5.67 0.046 0.007 0.773 68 27-0018 Hiawatha 6/27/2017 12:36 1 20.6 106.7 9.43 7.97 474.6 31.1 27-0018 Hiawatha 6/27/2017 12:35 2 20.05 100.4 8.97 7.93 474.5 46.2 27-0018 Hiawatha 6/27/2017 12:34 3 19.85 94.4 8.46 7.91 473.9 89.9 27-0018 Hiawatha 6/27/2017 12:34 4 19.88 91.4 8.19 7.91 473.1 130.5 0.050 0.010 68
2017 Water Resources Report - Minneapolis Park Recreation Board Page B15 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0018 Hiawatha 6/27/2017 12:33 4.2 19.9 91.4 8.18 7.93 473.3 106.4 27-0018 Hiawatha 7/13/2017 12:45 1.7 0 25.37 120 9.66 8.24 530.4 5 13.41 4.86 <0.500 0.028 0.005 0.718 0.724 <0.030 138 152 81 10.10 0.273 27-0018 Hiawatha 7/13/2017 12:44 1 25.19 120 9.69 8.2 530.6 7.8 27-0018 Hiawatha 7/13/2017 12:43 2 24.87 117.4 9.54 8.11 532.8 11.2 27-0018 Hiawatha 7/13/2017 12:42 3 24.04 58.1 4.8 7.64 530.3 16.4 27-0018 Hiawatha 7/13/2017 12:41 4 23.37 2.8 0.23 7.54 526.1 23 0.043 0.005 77 7.03 27-0018 Hiawatha 7/13/2017 12:40 5 20.51 0.2 0.02 7.59 496.7 25.2 27-0018 Hiawatha 7/13/2017 12:39 6 15.18 0.1 0.01 7.68 512.6 31.9 27-0018 Hiawatha 7/13/2017 12:38 7 10.7 0.1 0.01 7.57 756.3 41.9 27-0018 Hiawatha 7/13/2017 12:37 7.4 9.87 0.3 0.04 7.49 901.4 42.8 27-0018 Hiawatha 7/27/2017 10:27 1.65 0 24.89 70.6 5.73 7.83 463.2 0 19.25 5.12 0.036 0.006 0.751 69 27-0018 Hiawatha 7/27/2017 10:27 1 24.72 68.8 5.61 7.83 460.4 1 27-0018 Hiawatha 7/27/2017 10:26 2 24.4 61.7 5.05 7.81 462.3 5.2 27-0018 Hiawatha 7/27/2017 10:25 3 24.34 46.2 3.79 7.83 467 13 27-0018 Hiawatha 7/27/2017 10:24 4 23.8 24 1.99 7.85 477.5 22 0.071 0.011 74 27-0018 Hiawatha 7/27/2017 10:23 5 23.38 16.5 1.38 7.89 493.2 28.5 27-0018 Hiawatha 7/27/2017 10:23 6 19.49 0.4 0.04 7.95 513.8 29.8 27-0018 Hiawatha 7/27/2017 10:22 7 12.09 0 0 7.84 752.3 40.3 27-0018 Hiawatha 7/27/2017 10:21 7.5 10.76 0.2 0.02 7.78 968.9 37.4 27-0018 Hiawatha 8/11/2017 9:57 1.24 0 21.91 78.2 6.72 7.93 508.9 0 21.46 6.65 2.360 0.058 0.009 0.735 79 27-0018 Hiawatha 8/11/2017 9:57 1 21.63 68.3 5.9 7.93 509.9 0 27-0018 Hiawatha 8/11/2017 9:56 2 21.44 64.7 5.61 7.91 511.1 0 27-0018 Hiawatha 8/11/2017 9:55 3 21.3 70.6 6.14 7.96 516.1 0 27-0018 Hiawatha 8/11/2017 9:54 4 21.1 72.6 6.33 7.98 521.7 0 0.048 0.011 89 27-0018 Hiawatha 8/11/2017 9:52 5 21.08 65.4 5.71 8.03 521.8 0.5 27-0018 Hiawatha 8/11/2017 9:52 6 20.21 7.8 0.69 8.06 532.8 10.2 27-0018 Hiawatha 8/11/2017 9:51 7 14.2 0 0 7.97 775.3 86 27-0018 Hiawatha 8/11/2017 9:50 7.3 11.74 0.2 0.02 7.89 994.1 54.4 27-0018 Hiawatha 8/24/2017 10:39 1.54 0 21.62 92.3 7.99 7.82 477.9 0 15.05 3.83 0.051 0.008 1.075 78 61.00 27-0018 Hiawatha 8/24/2017 10:38 1 21.56 91.8 7.95 7.81 477.6 0 27-0018 Hiawatha 8/24/2017 10:37 2 21.52 89.3 7.74 7.79 477.4 0 27-0018 Hiawatha 8/24/2017 10:36 3 21.5 85.7 7.43 7.77 477.4 0 27-0018 Hiawatha 8/24/2017 10:35 4 21.48 85 7.37 7.76 477.3 0 0.052 0.008 78 27-0018 Hiawatha 8/24/2017 10:32 5 21.2 58.2 5.08 7.73 476 0 27-0018 Hiawatha 8/24/2017 10:31 6 20.38 8.5 0.75 7.75 477.8 17.9 27-0018 Hiawatha 8/24/2017 10:29 7 17.2 0.2 0.02 7.74 636.2 40.7 27-0018 Hiawatha 8/24/2017 10:28 7.4 14.92 0.2 0.02 7.66 863.1 53.7 27-0018 Hiawatha 9/21/2017 12:11 1.5 0 20.08 86.5 7.67 7.82 472.9 7.2 12.37 1.66 2.250 0.045 0.005 0.890 66 27-0018 Hiawatha 9/21/2017 12:10 1 20.07 86 7.63 7.82 472.7 10.7 27-0018 Hiawatha 9/21/2017 12:09 2 19.84 80.6 7.18 7.81 471.4 17.7 27-0018 Hiawatha 9/21/2017 12:08 3 19.77 76.6 6.84 7.8 474.9 25.1 27-0018 Hiawatha 9/21/2017 12:08 4 19.62 72.6 6.5 7.8 474.1 29 0.047 0.005 61 27-0018 Hiawatha 9/21/2017 12:07 5 19.43 48.8 4.39 7.81 475.5 41.3 27-0018 Hiawatha 9/21/2017 12:07 6 18.87 16.2 1.48 7.79 507.2 52.7 27-0018 Hiawatha 9/21/2017 12:06 7 18.01 0.6 0.06 7.8 567.5 117.7 27-0018 Hiawatha 9/21/2017 12:06 8.1 16.51 2.9 0.28 7.7 756 185.7 27-0018 Hiawatha 9/28/2017 10:00 1.56 0 11.75 3.20 0.050 0.006 0.769 71 27-0018 Hiawatha 9/28/2017 10:00 4 0.050 0.007 71 27-0018 Hiawatha 11/8/2017 9:29 2.38 0 3.05 91.1 12.16 8.05 506.4 1.3 4.81 1.17 4.780 0.034 0.008 0.647 0.724 0.110 152 178 68 6.55 <0.250 27-0018 Hiawatha 11/8/2017 9:29 1 3.05 91.1 12.16 8.05 506.6 1.3 27-0018 Hiawatha 11/8/2017 9:28 2 3.05 91 12.14 8.05 506.6 1.5 27-0018 Hiawatha 11/8/2017 9:27 3 3.06 90.5 12.07 8.04 506.4 0.7 27-0018 Hiawatha 11/8/2017 9:26 4 3.1 90.3 12.04 8.04 506.7 3.4 0.033 0.007 72 6.55 27-0018 Hiawatha 11/8/2017 9:26 4.8 3.38 87.6 11.59 8.03 513.3 0.6 27-0040 Isles 1/19/2017 10:25 0 0.28 76.4 10.77 7.68 628.2 0 13.20 2.83 1.260 0.057 0.015 1.110 1.250 0.379 126 148 123 9.92 27-0040 Isles 1/19/2017 10:24 1 2.51 55.7 7.38 7.49 629.9 0 27-0040 Isles 1/19/2017 10:23 2 2.42 47.1 6.26 7.46 633 0 27-0040 Isles 1/19/2017 10:22 3 2.45 44.9 5.95 7.44 636.6 0 27-0040 Isles 1/19/2017 10:21 4 2.49 47.2 6.25 7.45 641.6 0 27-0040 Isles 1/19/2017 10:21 5 2.54 46.8 6.19 7.44 646.1 0 0.069 0.057 27-0040 Isles 1/19/2017 10:20 6 2.57 48.1 6.36 7.44 656.2 0 27-0040 Isles 1/19/2017 10:19 7 2.59 48.5 6.41 7.43 662.3 0
2017 Water Resources Report - Minneapolis Park Recreation Board Page B16 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0040 Isles 1/19/2017 10:19 8 2.69 46.8 6.17 7.41 671.2 0 0.074 0.052 127 10.49 27-0040 Isles 1/19/2017 10:18 9 2.86 36.7 4.82 7.34 680.4 20.1 27-0040 Isles 4/13/2017 11:14 1.43 0 10.38 103.5 11.46 8.46 704.8 0.9 10.55 4.15 <0.500 0.056 <0.003 0.661 0.806 0.068 120 138 144 9.19 <0.250 27-0040 Isles 4/13/2017 11:13 1 10.36 103.3 11.44 8.45 704.7 0.7 27-0040 Isles 4/13/2017 11:12 2 10.34 102.4 11.35 8.43 704.8 1 27-0040 Isles 4/13/2017 11:11 3 10.24 100.3 11.14 8.37 705.8 0.5 27-0040 Isles 4/13/2017 11:10 4 9.78 90.2 10.14 8.18 701.4 0 27-0040 Isles 4/13/2017 11:10 5 9.11 85 9.7 8.07 706.3 0 0.039 <0.003 27-0040 Isles 4/13/2017 11:08 6 8.06 68.1 7.97 7.76 703.3 0 27-0040 Isles 4/13/2017 11:07 7 6.45 59.7 7.27 7.65 703 0 27-0040 Isles 4/13/2017 11:06 8 6.04 54.3 6.68 7.58 702.4 0 0.035 <0.003 140 8.88 27-0040 Isles 4/13/2017 11:04 9 5.89 38 4.69 7.42 704.7 235.8 27-0040 Isles 4/13/2017 11:03 9.2 5.91 0 0 7 791.7 375 27-0040 Isles 5/9/2017 11:36 1.78 0 16.67 128.6 12.2 8.77 660.8 8.3 6.34 2.54 <0.500 0.039 0.011 0.580 0.629 <0.030 113 132 137 9.01 0.293 27-0040 Isles 5/9/2017 11:35 1 16.13 129.4 12.42 8.76 659.4 9.4 27-0040 Isles 5/9/2017 11:34 2 14.15 130.6 13.09 8.69 668 11.2 27-0040 Isles 5/9/2017 11:33 3 11.77 128.6 13.59 8.59 661.9 12.7 27-0040 Isles 5/9/2017 11:32 4 10.54 112.9 12.27 8.45 663.1 14 27-0040 Isles 5/9/2017 11:30 5 9.8 70.6 7.81 7.87 666 15.3 0.063 0.012 27-0040 Isles 5/9/2017 11:29 6 9.57 53.2 5.92 7.79 666.8 15.3 27-0040 Isles 5/9/2017 11:28 7 9.42 47.5 5.3 7.77 668.1 16.3 27-0040 Isles 5/9/2017 11:25 8 8.94 15.6 1.77 7.68 672.2 24.7 0.048 0.007 142 8.62 27-0040 Isles 5/9/2017 11:24 9 8.04 0 0 7.64 689.1 46.2 27-0040 Isles 5/9/2017 11:23 9.5 7.71 0 0 7.67 697.9 47 27-0040 Isles 5/24/2017 11:33 2.71 0 14.98 110.4 10.82 8.62 609.5 6.5 8.49 <0.500 0.032 0.004 0.640 133 27-0040 Isles 5/24/2017 11:32 1 14.86 110.5 10.86 8.61 609.4 7.7 27-0040 Isles 5/24/2017 11:31 2 14.66 109 10.75 8.54 610.5 9.9 27-0040 Isles 5/24/2017 11:30 3 14.45 104.2 10.33 8.43 607.7 12.7 27-0040 Isles 5/24/2017 11:30 4 13.52 90.5 9.16 8.22 620 16.1 27-0040 Isles 5/24/2017 11:29 5 10.86 82.6 8.87 7.93 665 19.7 0.058 0.004 27-0040 Isles 5/24/2017 11:28 6 9.83 6.1 0.67 7.65 666.2 14.8 27-0040 Isles 5/24/2017 11:27 7 9.37 0 0 7.65 668.1 15.2 27-0040 Isles 5/24/2017 11:27 8 9.03 0 0 7.65 671.9 26.7 0.073 0.039 138 27-0040 Isles 5/24/2017 11:26 9 8.37 0 0 7.63 684.5 35.1 27-0040 Isles 5/24/2017 11:25 10 7.96 0 0 7.63 698 45.1 27-0040 Isles 6/6/2017 11:26 3.61 0 23.08 147 12.34 9.11 615.7 18.3 5.24 1.30 <0.500 0.025 0.003 0.578 126 27-0040 Isles 6/6/2017 11:26 1 22.73 144 12.18 9.09 617 20.5 27-0040 Isles 6/6/2017 11:25 2 19.88 175.2 15.66 9.03 621.3 23.5 27-0040 Isles 6/6/2017 11:23 3 17.65 116.1 10.86 8.71 644.3 29.5 27-0040 Isles 6/6/2017 11:22 4 14.47 110.3 11.03 8.58 653.8 33 27-0040 Isles 6/6/2017 11:20 5 11.44 53.2 5.7 7.88 699.5 51.4 0.047 0.003 27-0040 Isles 6/6/2017 11:16 6 10.01 0 0 7.75 699.8 56.1 27-0040 Isles 6/6/2017 11:15 7 9.52 0 0 7.74 704.3 55.5 27-0040 Isles 6/6/2017 11:14 8 8.99 0 0 7.72 711.3 52.5 0.127 0.087 140 27-0040 Isles 6/6/2017 11:13 9 8.28 0 0 7.69 730.7 53.6 27-0040 Isles 6/6/2017 11:11 9.3 8.12 0 0 7.77 736.2 1691 27-0040 Isles 6/21/2017 10:17 2.65 0 23.49 105.3 8.71 8.82 593.5 21.4 9.44 1.74 0.034 0.004 0.625 105 27-0040 Isles 6/21/2017 10:17 1 23.37 105.6 8.76 8.78 592.9 23.9 27-0040 Isles 6/21/2017 10:16 2 23.16 100.3 8.36 8.7 593.4 27.7 27-0040 Isles 6/21/2017 10:16 3 22.53 95.5 8.05 8.51 598.1 31.5 27-0040 Isles 6/21/2017 10:15 4 16.35 82.5 7.87 8.11 634.5 37.5 27-0040 Isles 6/21/2017 10:15 5 12.15 5.3 0.55 7.86 680.1 46.6 0.044 0.004 27-0040 Isles 6/21/2017 10:14 6 10.39 0 0 7.84 680.8 55.3 27-0040 Isles 6/21/2017 10:14 7 9.89 0 0 7.83 682.8 47.9 27-0040 Isles 6/21/2017 10:13 8 9.11 0 0 7.79 692.7 46.4 0.165 0.107 132 27-0040 Isles 6/21/2017 10:13 9 8.58 0 0 7.77 706.7 52.1 27-0040 Isles 7/11/2017 11:56 0.87 0 26.25 140.8 11.07 8.64 580 22 26.11 1.70 <0.500 0.044 0.007 1.035 1.250 <0.030 93 108 113 8.41 0.339 27-0040 Isles 7/11/2017 11:56 1 26.17 137.1 10.8 8.43 579.9 24.3 27-0040 Isles 7/11/2017 11:55 2 24.82 44.9 3.62 7.76 592.8 26.1 27-0040 Isles 7/11/2017 11:54 3 21.63 6.1 0.53 7.63 601.8 31.4 27-0040 Isles 7/11/2017 11:54 4 17.94 0 0 7.58 624 41.2 27-0040 Isles 7/11/2017 11:53 5 13.11 0 0 7.54 669.2 64.2 0.039 0.005
2017 Water Resources Report - Minneapolis Park Recreation Board Page B17 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0040 Isles 7/11/2017 11:52 6 10.96 0 0 7.52 676.1 56.1 27-0040 Isles 7/11/2017 11:50 7 9.98 0 0 7.5 679.9 51.4 27-0040 Isles 7/11/2017 11:50 8 9.29 0 0 7.48 686.5 120 0.222 0.191 131 6.71 27-0040 Isles 7/11/2017 11:49 9 8.66 0 0 7.49 712.4 90.3 27-0040 Isles 7/11/2017 11:48 9.2 8.71 0 0 7.56 712.3 93 27-0040 Isles 7/25/2017 10:24 0.71 0 24.9 93.5 7.57 8.64 577.1 0.7 50.97 1.23 0.048 0.005 1.218 121 27-0040 Isles 7/25/2017 10:23 1 24.8 96.5 7.83 8.6 576.7 2.3 27-0040 Isles 7/25/2017 10:22 2 24.86 87.1 7.06 8.48 577.1 4.9 27-0040 Isles 7/25/2017 10:21 3 24.73 63.4 5.15 8.17 580.4 7.4 27-0040 Isles 7/25/2017 10:18 4 18.39 0.3 0.03 7.65 627.1 12.6 27-0040 Isles 7/25/2017 10:17 5 14.13 0.2 0.02 7.59 669 17.9 0.041 0.005 27-0040 Isles 7/25/2017 10:16 6 11.05 0 0 7.55 683.6 28.2 27-0040 Isles 7/25/2017 10:16 7 10.02 0 0 7.52 688.3 37.4 27-0040 Isles 7/25/2017 10:14 8 9.08 0 0 7.33 707.6 93.1 0.223 0.213 135 27-0040 Isles 7/25/2017 10:13 8.2 9.19 0 0 7.43 710.5 389.7 27-0040 Isles 8/8/2017 11:03 0.65 0 23.9 130.1 10.8 8.64 573.2 19.4 51.02 9.23 2.060 0.073 0.006 1.218 112 <1 27-0040 Isles 8/8/2017 11:03 1 22.35 82.4 7.05 8.13 570 22.7 27-0040 Isles 8/8/2017 11:02 2 21.98 12 1.03 7.94 579.9 28.2 27-0040 Isles 8/8/2017 11:01 3 21.18 0.2 0.02 7.91 588.8 31.6 27-0040 Isles 8/8/2017 11:01 4 18.78 0.1 0.01 7.86 641.3 35.8 27-0040 Isles 8/8/2017 11:00 5 13.67 0 0 7.81 684.6 41.8 0.042 0.018 27-0040 Isles 8/8/2017 10:59 6 11.44 0 0 7.8 692.3 44.8 27-0040 Isles 8/8/2017 10:58 7 10.12 0 0 7.8 702.4 50.9 27-0040 Isles 8/8/2017 10:58 8 9.51 0 0 7.78 712.8 54.8 0.302 0.240 140 27-0040 Isles 8/8/2017 10:57 9 8.78 0 0 7.77 742.1 59.8 27-0040 Isles 8/8/2017 10:56 9.3 8.74 0 0 7.86 748.1 60.6 27-0040 Isles 8/22/2017 10:41 0.42 0 22.19 91.6 7.82 8.37 537.9 2.6 52.53 3.36 0.056 0.005 1.370 117 27-0040 Isles 8/22/2017 10:40 1 21.97 88.3 7.57 8.2 537.4 3.9 27-0040 Isles 8/22/2017 10:39 2 21.67 64.3 5.54 7.9 539.4 5.3 27-0040 Isles 8/22/2017 10:38 3 21.2 4.5 0.39 7.68 549.1 6.8 27-0040 Isles 8/22/2017 10:37 4 19.39 0.1 0.01 7.62 613.2 7.6 27-0040 Isles 8/22/2017 10:36 5 15.39 0.1 0.01 7.54 681.4 8.8 0.041 0.005 27-0040 Isles 8/22/2017 10:36 6 11.96 0.2 0.02 7.52 698.6 10.9 27-0040 Isles 8/22/2017 10:34 7 10.74 0 0 7.5 705.1 15.4 27-0040 Isles 8/22/2017 10:33 8 9.84 0 0 7.48 714.4 26.7 0.252 0.223 141 27-0040 Isles 8/22/2017 10:32 9 9.08 0 0 7.45 741.7 33.8 27-0040 Isles 8/22/2017 10:31 10 8.87 0.1 0.01 7.48 758.4 3000 27-0040 Isles 8/22/2017 10:28 10.3 8.98 0 0 7.74 767.2 845 27-0040 Isles 9/12/2017 10:01 0.8 0 21.14 128.6 11.22 8.24 547.6 0 35.37 3.14 1.660 0.047 0.005 1.246 108 27-0040 Isles 9/12/2017 10:01 1 20.77 122.8 10.79 8.11 545.8 1.2 27-0040 Isles 9/12/2017 9:59 2 19.45 78.1 7.05 7.66 548.4 5.2 27-0040 Isles 9/12/2017 9:58 3 19.12 62.6 5.68 7.54 548.8 9.6 27-0040 Isles 9/12/2017 9:58 4 18.66 34.9 3.2 7.49 552.1 15.3 27-0040 Isles 9/12/2017 9:57 5 16.99 0.4 0.04 7.4 619.2 21.9 0.055 0.004 27-0040 Isles 9/12/2017 9:56 6 12.84 0.2 0.02 7.34 707.4 15.4 27-0040 Isles 9/12/2017 9:55 7 11.12 0.1 0.01 7.37 716.2 10.7 27-0040 Isles 9/12/2017 9:55 8 10.36 0.8 0.09 7.42 723.7 0 0.380 0.326 141 27-0040 Isles 9/26/2017 10:37 0.85 0 21.48 81 6.98 8.13 537.8 18.74 6.53 0.056 0.003 0.845 99 27-0040 Isles 9/26/2017 10:35 1 21.45 79.9 6.89 7.98 537.2 27-0040 Isles 9/26/2017 10:34 2 21.1 36.6 3.18 7.31 538.4 27-0040 Isles 9/26/2017 10:32 3 19.87 2.4 0.22 7.14 534.2 27-0040 Isles 9/26/2017 10:32 4 19 2.2 0.2 7.08 544.4 0.046 0.003 27-0040 Isles 9/26/2017 10:31 5 16.04 2.2 0.21 6.94 642.7 27-0040 Isles 9/26/2017 10:31 6 13.07 2.4 0.24 6.83 691.2 27-0040 Isles 9/26/2017 10:30 7 11.29 2.4 0.26 6.78 700.6 27-0040 Isles 9/26/2017 10:29 8 9.7 3 0.33 6.73 723.1 0.320 0.265 117 27-0040 Isles 9/26/2017 10:29 9 9.35 3.2 0.36 6.71 744 27-0040 Isles 9/26/2017 10:29 10 9.27 3.3 0.37 6.75 747.4 27-0040 Isles 11/9/2017 10:14 1.25 0 3.73 87.5 11.44 8.2 543.8 1.9 28.44 5.30 1.580 0.050 0.003 0.997 1.020 0.095 114 130 110 7.10 0.327 27-0040 Isles 11/9/2017 10:14 1 3.73 87.5 11.44 8.18 543.9 1.9 27-0040 Isles 11/9/2017 10:13 2 3.73 87.4 11.42 8.13 544.1 1.8 27-0040 Isles 11/9/2017 10:13 3 3.74 87.6 11.45 8.18 543.9 1.9
2017 Water Resources Report - Minneapolis Park Recreation Board Page B18 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0040 Isles 11/9/2017 10:12 4 3.74 86.8 11.35 8.14 543.8 1.9 27-0040 Isles 11/9/2017 10:11 5 3.74 86.4 11.29 8.09 545.1 2.2 0.056 0.003 27-0040 Isles 11/9/2017 10:10 6 3.72 82 10.73 8.01 544.1 2.1 27-0040 Isles 11/9/2017 10:10 7 4.44 8.6 1.1 7.64 543.8 112.4 27-0040 Isles 11/9/2017 10:08 7.3 3.69 13.4 1.75 7.66 545.9 33.5 27-0040 Isles 11/9/2017 10:08 8 0.048 0.003 106 7.10 27-655 Loring 1/30/2017 11:07 0 0.8 135.8 18.75 8.51 1022 0 23.20 13.23 13.100 0.082 0.015 0.825 0.864 0.041 189 264 248 15.21 27-655 Loring 1/30/2017 11:06 1 3.19 50 6.46 7.44 1191 273.6 27-655 Loring 1/30/2017 11:04 2 3.66 32.8 4.19 7.39 1213 1.1 27-655 Loring 1/30/2017 11:03 3 4.2 20 2.51 7.35 1252 1.3 27-655 Loring 1/30/2017 11:02 4 4.58 0.5 0.06 7.29 1404 31.5 0.189 0.136 276 14.90 27-655 Loring 1/30/2017 11:01 4.4 5.85 1.7 0.2 7.2 1813 33.2 27-655 Loring 4/11/2017 10:20 1.21 0 10.31 94.3 10.41 8.08 1067 1 11.10 3.29 3.690 0.103 0.012 0.946 0.990 <0.030 170 236 226 11.95 <0.250 27-655 Loring 4/11/2017 10:20 1 10.3 94 10.38 8.08 1067 44.2 27-655 Loring 4/11/2017 10:20 2 10.3 94 10.38 8.08 1067 0.9 27-655 Loring 4/11/2017 10:19 3 10.3 94.2 10.41 8.06 1067 0.7 27-655 Loring 4/11/2017 10:18 4 10.16 92.4 10.24 8.03 1067 51.9 0.111 0.013 226 11.61 27-655 Loring 5/8/2017 12:36 1.3 0 16.37 108.2 10.36 8.34 1013 9.8 6.89 2.60 2.080 0.109 0.033 0.807 0.902 0.037 155 212 223 13.30 <0.250 27-655 Loring 5/8/2017 12:34 1 16.17 106.4 10.24 8.33 1013 19 27-655 Loring 5/8/2017 12:33 2 15.83 104.1 10.09 8.31 1012 30.4 27-655 Loring 5/8/2017 12:32 3 15.71 100.6 9.77 8.28 1012 31.4 27-655 Loring 5/8/2017 12:31 4 15.27 88.9 8.72 8.2 1013 3000 0.100 0.043 204 11.70 27-655 Loring 5/8/2017 12:30 4.4 14.96 26.6 2.62 8.14 1019 2999 27-655 Loring 5/23/2017 10:53 1.46 0 15.91 79.3 7.62 7.81 934.4 0 7.22 3.38 0.135 0.090 0.833 218 27-655 Loring 5/23/2017 10:52 1 15.85 77.8 7.48 7.8 934.2 0 27-655 Loring 5/23/2017 10:51 2 15.75 76.1 7.34 7.79 934 0 27-655 Loring 5/23/2017 10:51 3 15.7 76 7.34 7.78 934 0 27-655 Loring 5/23/2017 10:50 4 15.69 73.6 7.11 7.77 934.4 0 0.132 0.097 209 27-655 Loring 5/23/2017 10:49 4.5 15.63 72.6 7.02 7.76 934.2 1.9 27-655 Loring 6/8/2017 10:51 0.87 0 22.75 91.8 7.71 8.16 957.4 35.5 6.66 2.96 3.580 0.165 0.059 0.897 215 27-655 Loring 6/8/2017 10:51 1 22.65 88.8 7.47 8.13 957.9 37.3 27-655 Loring 6/8/2017 10:50 2 22.31 69.5 5.89 7.95 958.5 40.4 27-655 Loring 6/8/2017 10:50 3 21.86 41.7 3.56 7.8 959.4 42.9 27-655 Loring 6/8/2017 10:48 4 21.42 7.4 0.63 7.8 965.9 55.6 0.142 0.071 196 27-655 Loring 6/20/2017 11:07 1.1 0 23.74 66.8 5.49 7.55 962.4 0 22.00 14.30 0.180 0.094 1.040 208 27-655 Loring 6/20/2017 11:05 1 23.38 62.8 5.2 7.51 964.8 0 27-655 Loring 6/20/2017 11:04 2 23.25 55.1 4.58 7.5 964.3 0 27-655 Loring 6/20/2017 11:03 3 23.1 46.8 3.9 7.49 963.6 0 27-655 Loring 6/20/2017 11:02 4 22.94 35.5 2.97 7.5 964.9 0 0.176 0.099 208 27-655 Loring 6/20/2017 11:01 4.1 22.94 36.7 3.07 7.53 964.9 0 27-655 Loring 7/14/2017 11:25 1.1 0 24.52 41.1 3.38 7.41 1013 0 24.96 7.87 6.980 0.125 0.072 1.090 1.177 <0.030 146 204 209 11.90 0.328 27-655 Loring 7/14/2017 11:24 1 24.45 31.8 2.62 7.41 1013 0 27-655 Loring 7/14/2017 11:24 2 24.37 23 1.89 7.42 1012 0 27-655 Loring 7/14/2017 11:23 3 24.31 16.2 1.33 7.44 1013 0 27-655 Loring 7/14/2017 11:22 4 24.18 13.4 1.11 7.48 1014 0 0.156 0.080 209 11.54 27-655 Loring 7/14/2017 11:22 4.1 24.17 13.4 1.11 7.52 1015 0 27-655 Loring 7/26/2017 11:05 0.85 0 24.48 28 2.28 7.3 1029 0 14.06 12.55 0.137 0.082 0.877 209 27-655 Loring 7/26/2017 11:05 1 24.1 26.1 2.14 7.3 1029 0 27-655 Loring 7/26/2017 11:04 2 24.08 25.8 2.11 7.31 1029 0 27-655 Loring 7/26/2017 11:03 3 24.01 22.2 1.83 7.31 1030 0 27-655 Loring 7/26/2017 11:03 4 23.69 14.6 1.21 7.3 1036 0 0.145 0.087 204 27-655 Loring 7/26/2017 11:02 4.1 23.52 11.7 0.97 7.31 1039 0 27-655 Loring 8/9/2017 10:48 1.18 0 22.45 22.4 1.91 7.54 1026 0 15.27 9.41 10.400 0.139 0.076 0.701 210 11.00 27-655 Loring 8/9/2017 10:47 1 22.44 22.2 1.89 7.55 1026 0 27-655 Loring 8/9/2017 10:47 2 22.43 22.2 1.89 7.57 1026 0 27-655 Loring 8/9/2017 10:46 3 22.42 21.3 1.81 7.59 1026 0 27-655 Loring 8/9/2017 10:46 4 22.36 14.4 1.23 7.61 1027 0 0.143 0.077 210 27-655 Loring 8/23/2017 10:59 1.7 0 21.82 23.6 2.03 7.52 1006 0 6.93 5.52 0.125 0.085 0.867 197 27-655 Loring 8/23/2017 10:58 1 21.21 13.9 1.21 7.52 1003 0 27-655 Loring 8/23/2017 10:57 2 21.14 11.7 1.02 7.53 1006 0 27-655 Loring 8/23/2017 10:57 3 21.05 9.6 0.84 7.55 1006 0 27-655 Loring 8/23/2017 10:56 4 20.98 8.5 0.74 7.58 1006 0 0.145 0.088 201
2017 Water Resources Report - Minneapolis Park Recreation Board Page B19 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-655 Loring 8/23/2017 10:55 4.3 20.96 6.3 0.55 7.62 1006 0 27-655 Loring 9/13/2017 10:53 1.94 0 20.95 47.5 4.1 7.86 998.8 17.1 7.98 5.94 8.920 0.145 0.091 0.936 178 27-655 Loring 9/13/2017 10:52 1 20.86 45.9 3.97 7.88 998.3 17 27-655 Loring 9/13/2017 10:52 2 20.79 44.9 3.89 7.92 999 16.9 27-655 Loring 9/13/2017 10:51 3 20.71 42.9 3.72 8.01 998.5 14.9 27-655 Loring 9/13/2017 10:51 4 20.66 36.8 3.2 8.15 999.4 8.7 0.146 0.094 201 27-655 Loring 9/25/2017 10:52 0.84 0 22.64 7.26 1004 0 21.17 13.01 0.175 0.095 1.090 200 27-655 Loring 9/25/2017 10:51 1 22.67 7.26 1004 0 27-655 Loring 9/25/2017 10:49 2 22.54 7.25 1004 0 27-655 Loring 9/25/2017 10:48 3 22.06 7.25 1004 0 27-655 Loring 9/25/2017 10:47 4 21.48 7.3 1010 0 0.175 0.115 191 27-655 Loring 11/7/2017 10:57 0.75 0 3.51 90.9 13.2 8.12 946.2 2.9 24.37 7.65 8.030 0.137 0.048 0.979 1.095 0.173 174 240 191 13.14 <0.250 27-655 Loring 11/7/2017 10:56 1 3.38 90.6 13.2 8.1 947.9 3 27-655 Loring 11/7/2017 10:55 2 3.35 90.6 13.22 8.08 946.2 3.1 27-655 Loring 11/7/2017 10:54 3 3.42 89.9 13.09 8.04 945.9 3.7 27-655 Loring 11/7/2017 10:53 4 3.44 89.1 12.96 8 946.5 2.5 0.133 0.050 191 13.98 27-655 Loring 11/7/2017 10:52 4.3 3.46 89.2 12.96 7.97 946.3 3.6 27-0018 Nokomis 1/31/2017 10:09 0 0.29 97.5 13.72 7.94 423.7 0 2.40 1.19 8.700 0.020 0.003 0.664 0.923 0.331 125 128 78 6.48 27-0018 Nokomis 1/31/2017 10:09 1 2.46 96.6 12.81 7.88 475.4 1 27-0018 Nokomis 1/31/2017 10:08 2 2.72 84.2 11.09 7.65 480.4 0 27-0018 Nokomis 1/31/2017 10:06 3 2.94 59.8 7.83 7.47 488.5 0 27-0018 Nokomis 1/31/2017 10:04 4 3.49 20.2 2.6 7.27 518.5 2.1 0.042 0.004 27-0018 Nokomis 1/31/2017 10:03 5 3.6 13.3 1.71 7.26 543.6 0.4 27-0018 Nokomis 1/31/2017 10:01 6 3.48 18.5 2.38 7.25 659.1 0.8 27-0018 Nokomis 1/31/2017 10:00 7 3.45 24.9 3.21 7.24 732.5 1 0.074 0.015 111 6.17 27-0018 Nokomis 1/31/2017 9:59 8 3.61 20.4 2.62 7.21 807.5 0.7 27-0018 Nokomis 4/12/2017 9:37 0.99 0 9.36 105.2 11.91 8.28 484.1 8.2 12.80 2.51 8.650 0.071 <0.003 1.080 1.130 0.150 128 132 72 6.22 <0.250 27-0018 Nokomis 4/12/2017 9:37 1 9.35 105.1 11.9 8.27 484.1 8.4 27-0018 Nokomis 4/12/2017 9:36 2 9.13 102.7 11.69 8.24 484.2 9.1 27-0018 Nokomis 4/12/2017 9:34 3 8.87 97.6 11.18 8.14 484.7 9.7 27-0018 Nokomis 4/12/2017 9:33 4 8.8 94.6 10.85 8.09 485.1 9.4 0.048 <0.003 27-0018 Nokomis 4/12/2017 9:33 5 8.76 93.1 10.69 8.05 485.3 8.8 27-0018 Nokomis 4/12/2017 9:32 6 8.76 92.4 10.62 8.03 485.2 9.4 27-0018 Nokomis 4/12/2017 9:32 7 8.72 89.1 10.24 7.98 485.7 10.9 0.051 0.004 77 6.35 27-0018 Nokomis 5/11/2017 9:50 1.89 0 15.29 109.9 10.81 8.58 493.9 20.5 8.44 1.09 8.230 0.027 <0.003 0.594 0.661 <0.030 128 128 80 6.69 0.338 27-0018 Nokomis 5/11/2017 9:48 1 15.27 109.6 10.79 8.57 493.8 24.3 27-0018 Nokomis 5/11/2017 9:47 2 15.2 109.7 10.82 8.56 493.9 29.3 27-0018 Nokomis 5/11/2017 9:46 3 14.91 106.9 10.6 8.47 493.9 46.1 27-0018 Nokomis 5/11/2017 9:45 4 11.73 61.7 6.57 8.07 500.7 59.2 0.054 <0.003 27-0018 Nokomis 5/11/2017 9:43 5 11.54 49.2 5.26 7.98 501.8 65.5 27-0018 Nokomis 5/11/2017 9:42 6 11.45 41.9 4.49 7.95 503.1 71.8 27-0018 Nokomis 5/11/2017 9:40 7 10.93 11.4 1.24 7.88 503.2 3000 0.082 <0.003 85 6.71 27-0018 Nokomis 5/11/2017 9:39 7.4 10.74 2.1 0.22 7.92 504.6 2239 27-0018 Nokomis 5/26/2017 9:33 2.95 0 16.3 93.3 8.87 8.29 500.8 10.2 6.38 0.70 0.032 0.004 0.706 91 27-0018 Nokomis 5/26/2017 9:32 1 16.08 93.4 8.92 8.28 500.6 10.8 27-0018 Nokomis 5/26/2017 9:31 2 15.94 90.8 8.7 8.23 501.6 13.2 27-0018 Nokomis 5/26/2017 9:31 3 15.56 85.1 8.22 8.16 501.3 15.2 27-0018 Nokomis 5/26/2017 9:30 4 14.81 67.7 6.65 8.01 501.4 17.6 0.032 0.003 27-0018 Nokomis 5/26/2017 9:29 5 14.36 42.2 4.18 7.91 506.6 20.9 27-0018 Nokomis 5/26/2017 9:29 6 13.8 23.7 2.38 7.86 509 24.2 27-0018 Nokomis 5/26/2017 9:28 7 11.96 0 0 7.81 516.2 27.6 0.055 0.010 95 27-0018 Nokomis 5/26/2017 9:26 8 11.02 0 0 7.78 535 19.1 27-0018 Nokomis 6/9/2017 10:14 2.15 0 24.15 112.8 9.23 8.35 516.9 9.4 6.53 <0.500 5.010 0.026 0.003 0.680 82 27-0018 Nokomis 6/9/2017 10:13 1 23.6 117.8 9.73 8.35 516 13 27-0018 Nokomis 6/9/2017 10:12 2 23.31 117.2 9.73 8.31 516.6 17.2 27-0018 Nokomis 6/9/2017 10:11 3 20.14 106.6 9.42 8.02 507.6 18.9 27-0018 Nokomis 6/9/2017 10:10 4 17.29 37.9 3.55 7.62 515.1 18.9 0.032 0.004 27-0018 Nokomis 6/9/2017 10:10 5 16.27 7.9 0.76 7.55 520.3 25.2 27-0018 Nokomis 6/9/2017 10:09 6 15.85 1.9 0.19 7.54 519.2 33.3 27-0018 Nokomis 6/9/2017 10:08 7 13.78 0.1 0.01 7.49 524.4 45.2 0.057 0.014 87 27-0018 Nokomis 6/9/2017 10:07 8 11.26 0.5 0.06 7.37 561 95.5 27-0018 Nokomis 6/27/2017 10:13 1.44 0 21.22 93.5 8.16 8.26 517.7 1 14.20 2.23 0.037 0.003 0.703 91
2017 Water Resources Report - Minneapolis Park Recreation Board Page B20 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0018 Nokomis 6/27/2017 10:12 1 21.22 93.5 8.16 8.24 517.3 2.2 27-0018 Nokomis 6/27/2017 10:11 2 21.07 92 8.05 8.23 517.2 4.6 27-0018 Nokomis 6/27/2017 10:11 3 20.99 91 7.98 8.21 517.5 7 27-0018 Nokomis 6/27/2017 10:10 4 20.92 90.8 7.97 8.18 518.1 10.8 0.044 0.003 27-0018 Nokomis 6/27/2017 10:09 5 20.78 85.9 7.56 8.1 517.9 19.8 27-0018 Nokomis 6/27/2017 10:07 6 17.2 0.1 0.01 7.73 531 46.8 27-0018 Nokomis 6/27/2017 10:06 7 14.65 0 0 7.7 535.8 52.3 0.124 0.046 81 27-0018 Nokomis 6/27/2017 10:05 7.8 13.07 0 0 7.65 555.3 77.8 27-0018 Nokomis 7/13/2017 11:56 1.13 0 25.53 108.2 8.69 8.18 503.4 0.9 10.27 0.61 3.600 0.032 0.004 0.689 0.726 <0.030 121 116 86 6.25 0.295 27-0018 Nokomis 7/13/2017 11:55 1 25.45 108.4 8.72 8.15 503.6 2.5 27-0018 Nokomis 7/13/2017 11:54 2 25.32 107.1 8.63 8.05 503.5 5.4 27-0018 Nokomis 7/13/2017 11:53 3 24.94 87.6 7.11 7.8 507 9.3 27-0018 Nokomis 7/13/2017 11:52 4 21.49 0.4 0.03 7.42 527.4 17.3 0.060 0.004 27-0018 Nokomis 7/13/2017 11:51 5 20.97 0.2 0.01 7.42 531.3 26.6 27-0018 Nokomis 7/13/2017 11:50 6 20.58 0.2 0.02 7.43 531.7 68.8 27-0018 Nokomis 7/13/2017 11:49 7 15.01 0.4 0.04 7.38 548.6 57.3 0.195 0.049 86 <5.00 27-0018 Nokomis 7/13/2017 11:48 7.2 14.16 0.7 0.07 7.38 554.6 3000 27-0018 Nokomis 7/27/2017 9:42 1.05 0 25.36 87.9 7.07 8.22 498.9 0.4 16.48 1.25 0.038 0.004 0.768 83 27-0018 Nokomis 7/27/2017 9:41 1 25.16 84.6 6.84 8.17 498.6 1.2 27-0018 Nokomis 7/27/2017 9:39 2 25.05 82.2 6.66 7.97 500.2 3.3 27-0018 Nokomis 7/27/2017 9:37 3 24.68 41.1 3.34 7.71 501.2 7.9 27-0018 Nokomis 7/27/2017 9:36 4 24.33 16.9 1.38 7.68 509.5 13.3 0.058 0.004 27-0018 Nokomis 7/27/2017 9:35 5 23.06 0.3 0.03 7.69 525.5 27.9 27-0018 Nokomis 7/27/2017 9:33 6 20.05 0.1 0.01 7.72 539.3 46.8 27-0018 Nokomis 7/27/2017 9:32 7 15.99 0.3 0.03 7.74 552.6 76.6 0.303 0.063 88 27-0018 Nokomis 7/27/2017 9:31 7.8 14.11 0.1 0.01 7.75 600.7 150.8 27-0018 Nokomis 8/11/2017 9:15 0.84 0 22.85 91.5 7.72 8.17 499.1 3.4 35.81 6.60 5.670 0.055 0.006 0.902 89 27-0018 Nokomis 8/11/2017 9:14 1 22.82 90.5 7.64 8.15 498.5 4.9 27-0018 Nokomis 8/11/2017 9:13 2 22.74 84.9 7.18 8.1 499.2 7.7 27-0018 Nokomis 8/11/2017 9:12 3 22.7 82.4 6.98 8.08 499.5 5 27-0018 Nokomis 8/11/2017 9:11 4 22.69 83.5 7.07 8.05 499 7 0.068 0.005 27-0018 Nokomis 8/11/2017 9:10 5 22.54 76.7 6.51 7.99 499.4 4.1 27-0018 Nokomis 8/11/2017 9:09 6 21.49 0.8 0.07 7.9 512.6 15.4 27-0018 Nokomis 8/11/2017 9:08 7 17.27 0.2 0.02 7.83 570.6 169.7 0.223 0.058 89 27-0018 Nokomis 8/11/2017 9:07 7.3 15.69 0 0 7.85 593.8 3000 27-0018 Nokomis 8/24/2017 9:48 0.68 0 22.58 111.4 9.46 8.08 488.7 0 31.01 1.37 0.047 0.006 1.130 85 4.00 27-0018 Nokomis 8/24/2017 9:47 1 22.51 108.4 9.22 7.98 488.7 0 27-0018 Nokomis 8/24/2017 9:46 2 22.38 97.3 8.3 7.76 490 0 27-0018 Nokomis 8/24/2017 9:45 3 22.29 80 6.83 7.59 491.7 1 27-0018 Nokomis 8/24/2017 9:44 4 22.15 56.8 4.87 7.46 494.9 3.9 0.069 0.006 27-0018 Nokomis 8/24/2017 9:43 5 22.07 46.9 4.02 7.43 496.7 7.7 27-0018 Nokomis 8/24/2017 9:42 6 21.85 7.8 0.67 7.4 500.5 13 27-0018 Nokomis 8/24/2017 9:41 7 20.94 0.1 0.01 7.38 513.6 14.4 0.076 0.005 85 27-0018 Nokomis 8/24/2017 9:40 8 16.32 0.4 0.04 7.23 624.9 107.6 27-0018 Nokomis 8/24/2017 9:39 8.3 15.18 0.4 0.04 7.28 645.1 195.1 27-0018 Nokomis 9/21/2017 13:12 0.8 0 21.01 94.7 8.25 8.14 498.8 24.3 23.34 2.54 5.954 0.071 0.003 0.739 71 27-0018 Nokomis 9/21/2017 13:11 1 20.79 94.3 8.25 8.11 498.4 26.8 27-0018 Nokomis 9/21/2017 13:10 2 20.43 79.9 7.04 8.01 499.8 29.5 27-0018 Nokomis 9/21/2017 13:09 3 20.33 65.5 5.78 7.95 500.9 33.3 27-0018 Nokomis 9/21/2017 13:08 4 20.23 47.3 4.18 7.92 502.5 35.1 0.087 0.003 27-0018 Nokomis 9/21/2017 13:07 5 20.02 16.9 1.5 7.92 505.4 65.4 27-0018 Nokomis 9/21/2017 13:07 6 20 7.9 0.7 7.95 505.8 52.1 27-0018 Nokomis 9/21/2017 13:06 7 19.83 0 0 8 510.5 57.4 0.096 0.004 75 27-0018 Nokomis 9/21/2017 13:05 7.5 19.7 1 0.09 8.04 521.7 115.3 27-0018 Nokomis 9/28/2017 9:33 0.58 0 20.19 76.8 6.87 7.84 170.8 15.62 2.14 0.085 0.003 1.160 85 27-0018 Nokomis 9/28/2017 9:32 1 20.23 76.8 6.86 7.84 482.5 27-0018 Nokomis 9/28/2017 9:32 2 20.22 77.4 6.91 7.81 482.9 27-0018 Nokomis 9/28/2017 9:31 3 20.22 74.3 6.63 7.75 481.6 27-0018 Nokomis 9/28/2017 9:30 4 20.22 73.2 6.53 7.69 481.4 0.092 0.003 27-0018 Nokomis 9/28/2017 9:29 5 20.23 73.1 6.52 7.6 481.6 27-0018 Nokomis 9/28/2017 9:28 6 20.22 72 6.42 7.43 480.9 27-0018 Nokomis 9/28/2017 9:28 7 20.13 48.9 4.37 7.03 486.5 0.092 0.003 85
2017 Water Resources Report - Minneapolis Park Recreation Board Page B21 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0018 Nokomis 9/28/2017 9:27 8 19.55 9.5 0.86 6.75 515.2 27-0018 Nokomis 11/8/2017 8:51 1.45 0 4.7 78.9 10.08 8 496.1 5.3 18.46 3.14 9.080 0.075 0.003 1.330 1.660 0.090 125 124 82 5.84 0.635 27-0018 Nokomis 11/8/2017 8:50 1 4.71 78.9 10.08 8.01 496.1 5.4 27-0018 Nokomis 11/8/2017 8:50 2 4.7 78.7 10.05 7.99 496.3 5.5 27-0018 Nokomis 11/8/2017 8:49 3 4.69 78.6 10.05 7.98 495.7 5.5 27-0018 Nokomis 11/8/2017 8:49 4 4.69 78.9 10.09 7.97 496.4 5.5 0.080 0.003 27-0018 Nokomis 11/8/2017 8:48 5 4.68 78.9 10.08 7.97 496 5.4 27-0018 Nokomis 11/8/2017 8:47 6 4.68 78.9 10.09 7.98 496.4 6.3 27-0018 Nokomis 11/8/2017 8:47 7 4.67 78.7 10.07 7.99 496.4 10.1 0.069 0.003 82 6.10 27-0018 Nokomis 11/8/2017 8:46 8 4.68 78.3 10.02 8.01 496.4 12.6 27-0018 Nokomis 11/8/2017 8:46 8.7 4.67 77 9.85 8.03 495.9 1.7 27-0014 Powderhorn 1/30/2017 12:12 0 0.72 73.5 10.2 7.09 289.5 0.9 21.90 8.52 1.680 0.128 0.046 1.350 1.350 0.189 35 40 83 7.08 27-0014 Powderhorn 1/30/2017 12:11 1 2.46 18.6 2.46 6.88 432.7 1.3 27-0014 Powderhorn 1/30/2017 12:10 2 2.56 11 1.44 6.84 719.2 2.7 27-0014 Powderhorn 1/30/2017 12:09 3 2.5 2.7 0.35 6.78 1124 2.7 27-0014 Powderhorn 1/30/2017 12:07 4 2.6 3.3 0.43 6.8 1330 2.1 0.130 0.053 27-0014 Powderhorn 1/30/2017 12:06 5 2.84 16.6 2.16 6.83 1473 1.5 27-0014 Powderhorn 1/30/2017 12:05 6 3.05 0 0 6.77 1652 31.6 0.137 0.033 413 7.68 27-0014 Powderhorn 1/30/2017 12:04 6.5 3.59 0.1 0.01 6.67 1772 292.2 27-0014 Powderhorn 4/11/2017 11:54 1.05 0 10.04 71.5 7.95 7.35 715.2 139.3 11.90 8.07 1.000 0.148 0.033 1.740 1.760 0.073 43 48 226 6.90 0.596 27-0014 Powderhorn 4/11/2017 11:54 1 9.77 70.5 7.9 7.33 714.9 7.2 27-0014 Powderhorn 4/11/2017 11:53 2 9.44 67.5 7.61 7.29 714.8 7.5 27-0014 Powderhorn 4/11/2017 11:52 3 9.36 65.8 7.43 7.23 714 6.6 27-0014 Powderhorn 4/11/2017 11:51 4 6.36 9.3 1.13 6.99 742.6 6.2 0.141 0.032 27-0014 Powderhorn 4/11/2017 11:51 5 5.19 0 0 6.96 774.3 8.6 27-0014 Powderhorn 4/11/2017 11:49 6 5.06 0 0 6.84 881.6 332.5 0.388 0.034 226 6.14 27-0014 Powderhorn 4/11/2017 11:48 6.7 5.24 0 0 6.57 1255 589 27-0014 Powderhorn 5/8/2017 11:28 0.98 0 16.42 132.9 12.73 8.95 572 31.3 34.50 32.70 1.250 0.159 0.015 1.470 1.730 <0.030 40 36 152 6.61 0.439 27-0014 Powderhorn 5/8/2017 11:27 1 15.82 116 11.26 8.53 570.3 42.8 27-0014 Powderhorn 5/8/2017 11:26 2 11.99 46.4 4.9 7.57 563.7 47 27-0014 Powderhorn 5/8/2017 11:25 3 9.99 17.9 1.98 7.51 569.8 48 27-0014 Powderhorn 5/8/2017 11:24 4 9.59 10.6 1.18 7.49 577.2 57.9 0.110 0.012 27-0014 Powderhorn 5/8/2017 11:23 5 8.86 0 0 7.44 620.1 108.4 27-0014 Powderhorn 5/8/2017 11:22 6 7.74 0.2 0.03 7.32 765.5 3000 0.695 0.334 185 5.31 27-0014 Powderhorn 5/8/2017 11:21 6.7 7.26 2.4 0.29 7.36 857 3000 27-0014 Powderhorn 5/23/2017 10:11 0.85 0 15.92 73.4 7.06 7.47 430.9 2.9 22.10 7.64 0.149 0.014 1.650 119 27-0014 Powderhorn 5/23/2017 10:11 1 15.59 56.2 5.45 7.42 429.4 6 27-0014 Powderhorn 5/23/2017 10:10 2 14.01 18.4 1.85 7.39 430.1 7.7 27-0014 Powderhorn 5/23/2017 10:09 3 13.67 0.3 0.03 7.38 432.5 14.5 27-0014 Powderhorn 5/23/2017 10:09 4 11.79 0 0 7.26 581 18.6 0.220 0.021 27-0014 Powderhorn 5/23/2017 10:08 5 10.16 0 0 7.28 611.1 24.3 27-0014 Powderhorn 5/23/2017 10:07 6 9.01 0 0 7.21 679.5 39.7 0.401 0.218 171 27-0014 Powderhorn 5/23/2017 10:06 7 8.5 0 0 7.18 760.2 41.7 27-0014 Powderhorn 6/8/2017 9:51 0.65 0 23.08 75.4 6.31 7.69 466.5 17.3 80.98 26.36 1.355 0.131 0.005 1.742 121 27-0014 Powderhorn 6/8/2017 9:50 1 23.08 75.9 6.35 7.71 466.8 17.2 27-0014 Powderhorn 6/8/2017 9:49 2 23.08 76 6.35 7.74 467 17.6 27-0014 Powderhorn 6/8/2017 9:49 3 23.05 74.3 6.22 7.76 467.1 18.1 27-0014 Powderhorn 6/8/2017 9:48 4 23.07 75.1 6.28 7.81 467.2 20.6 0.149 0.006 27-0014 Powderhorn 6/8/2017 9:47 5 23.02 70.3 5.89 7.84 467.5 22.2 27-0014 Powderhorn 6/8/2017 9:46 6 22.98 61.9 5.19 7.89 468 500 0.139 0.005 115 27-0014 Powderhorn 6/20/2017 10:15 0.41 0 23.96 87.6 7.19 7.35 441.5 0 101.79 27.51 0.194 0.004 1.810 110 27-0014 Powderhorn 6/20/2017 10:14 1 23.95 87.3 7.17 7.36 441 0 27-0014 Powderhorn 6/20/2017 10:13 2 23.94 86.5 7.1 7.37 440.7 0 27-0014 Powderhorn 6/20/2017 10:12 3 23.88 81 6.66 7.4 441.8 0 27-0014 Powderhorn 6/20/2017 10:10 4 23.85 79 6.5 7.44 440.2 0 0.187 0.004 27-0014 Powderhorn 6/20/2017 10:09 5 23.85 78.4 6.45 7.5 441.9 0 27-0014 Powderhorn 6/20/2017 10:07 6 23.79 73.4 6.05 7.59 439.8 0 0.191 0.004 110 27-0014 Powderhorn 6/20/2017 10:06 6.5 23.56 65.4 5.41 7.67 426.5 424 27-0014 Powderhorn 7/14/2017 10:30 0.44 0 25.07 89.6 7.3 7.61 437.5 0 26.53 15.02 2.620 0.198 0.005 1.860 2.020 <0.030 41 36 104 5.41 0.450 27-0014 Powderhorn 7/14/2017 10:29 1 25.05 88 7.17 7.59 437.2 0 27-0014 Powderhorn 7/14/2017 10:29 2 25.05 88.7 7.23 7.57 437.2 0 27-0014 Powderhorn 7/14/2017 10:28 3 25.07 87.7 7.15 7.54 437.1 0.9
2017 Water Resources Report - Minneapolis Park Recreation Board Page B22 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0014 Powderhorn 7/14/2017 10:28 4 25.03 86.1 7.02 7.49 437.1 4.6 0.204 0.005 27-0014 Powderhorn 7/14/2017 10:27 5 24.99 80.5 6.57 7.45 437.4 16.4 27-0014 Powderhorn 7/14/2017 10:26 6 24.93 71 5.8 7.41 438.4 0 0.231 0.007 100 <5.00 27-0014 Powderhorn 7/14/2017 10:25 6.5 24.87 33.9 2.77 7.4 443.5 819 27-0014 Powderhorn 7/26/2017 10:20 0.34 0 25.74 62.9 5.02 7.62 389.2 0 92.52 23.27 0.202 0.008 1.944 88 27-0014 Powderhorn 7/26/2017 10:19 1 25.74 62 4.95 7.64 388.8 0 27-0014 Powderhorn 7/26/2017 10:19 2 25.73 62.4 4.98 7.67 389.2 0 27-0014 Powderhorn 7/26/2017 10:18 3 25.74 62.5 4.98 7.69 389.3 0 27-0014 Powderhorn 7/26/2017 10:18 4 25.73 62.1 4.96 7.74 388.8 0 0.207 0.005 27-0014 Powderhorn 7/26/2017 10:17 5 25.72 62.5 4.98 7.79 389.5 0 27-0014 Powderhorn 7/26/2017 10:16 6 25.69 61.6 4.92 7.84 390 0 0.214 0.005 93 27-0014 Powderhorn 7/26/2017 10:15 6.8 25.56 54.3 4.35 7.97 391.8 1155 27-0014 Powderhorn 8/9/2017 9:58 0.28 0 23.88 77.3 6.41 7.75 390.4 0 129.60 38.07 3.770 0.239 0.006 0.943 89 115.00 27-0014 Powderhorn 8/9/2017 9:58 1 23.89 75.5 6.26 7.74 390.5 0 27-0014 Powderhorn 8/9/2017 9:57 2 23.89 75.4 6.25 7.77 390.1 0 27-0014 Powderhorn 8/9/2017 9:56 3 23.88 76.4 6.34 7.78 390 0 27-0014 Powderhorn 8/9/2017 9:55 4 23.88 69 5.72 7.82 390.2 0 0.236 0.007 27-0014 Powderhorn 8/9/2017 9:54 5 23.84 78.9 6.55 7.84 390.6 0 27-0014 Powderhorn 8/9/2017 9:53 6 23.8 73.1 6.07 7.9 391.2 0 0.242 0.012 89 27-0014 Powderhorn 8/9/2017 9:52 6.4 23.77 77.2 6.42 7.94 391 1255 27-0014 Powderhorn 8/23/2017 10:12 0.28 0 22.35 59.7 5.1 7.78 318.9 18.9 66.68 22.47 0.174 0.011 2.670 80 27-0014 Powderhorn 8/23/2017 10:12 1 22.34 59.6 5.09 7.77 319.2 18.5 27-0014 Powderhorn 8/23/2017 10:11 2 22.33 58.9 5.03 7.81 319 16.9 27-0014 Powderhorn 8/23/2017 10:11 3 22.34 59.7 5.09 7.84 319.1 15.6 27-0014 Powderhorn 8/23/2017 10:09 4 22.35 59.6 5.09 7.91 319.1 18.3 0.241 0.013 27-0014 Powderhorn 8/23/2017 10:09 5 22.3 58.2 4.97 7.95 319.2 25.8 27-0014 Powderhorn 8/23/2017 10:08 6 22.24 58.4 5 8 319.4 45.9 0.244 0.013 80 27-0014 Powderhorn 8/23/2017 10:07 6.4 22.23 56.3 4.82 8.05 319.5 76.2 27-0014 Powderhorn 9/21/2017 9:45 0.28 0 20.59 52.8 4.65 7.96 288.7 13.6 63.44 23.73 3.980 0.219 0.004 0.860 61 27-0014 Powderhorn 9/21/2017 9:45 1 20.6 52.9 4.65 7.98 288.7 11.5 27-0014 Powderhorn 9/21/2017 9:44 2 20.59 52.4 4.6 8.04 288.5 10 27-0014 Powderhorn 9/21/2017 9:44 3 20.59 51.8 4.55 8.1 288.6 7 27-0014 Powderhorn 9/21/2017 9:43 4 20.58 51.6 4.54 8.19 288.6 0 0.203 0.004 27-0014 Powderhorn 9/21/2017 9:42 5 20.6 51.9 4.56 8.3 288.6 0 27-0014 Powderhorn 9/21/2017 9:42 6 20.59 51.5 4.52 8.38 288.6 0 0.205 0.006 61 27-0014 Powderhorn 9/21/2017 9:41 6.2 20.55 50.4 4.43 8.61 288.7 0 27-0014 Powderhorn 9/25/2017 10:05 0.27 0 22.75 7.48 281.2 8.6 154.86 25.50 0.248 0.004 2.540 70 27-0014 Powderhorn 9/25/2017 10:03 1 22.77 7.53 281 6.4 27-0014 Powderhorn 9/25/2017 10:02 2 22.77 7.56 281 3.8 27-0014 Powderhorn 9/25/2017 10:01 3 22.77 7.61 281.1 3 27-0014 Powderhorn 9/25/2017 9:59 4 22.77 7.68 281 1.8 0.245 0.004 27-0014 Powderhorn 9/25/2017 9:58 5 22.75 7.74 281 3.4 27-0014 Powderhorn 9/25/2017 9:57 6 22.66 7.8 281.4 3.6 0.197 0.003 65 27-0014 Powderhorn 9/25/2017 9:56 6.4 22.6 7.88 282.3 13.5 27-0014 Powderhorn 11/7/2017 10:09 0.35 0 4.03 81.9 11.76 8.13 227.6 37.9 92.28 14.48 4.450 0.163 <0.003 1.530 1.950 0.033 36 32 44 <5.00 0.294 27-0014 Powderhorn 11/7/2017 10:09 1 4.02 82 11.78 8.15 226.9 28.8 27-0014 Powderhorn 11/7/2017 10:09 2 3.99 82.4 11.84 8.15 227.5 28.9 27-0014 Powderhorn 11/7/2017 10:08 3 3.98 81.5 11.71 8.17 227.7 29.2 27-0014 Powderhorn 11/7/2017 10:08 4 3.98 81.6 11.73 8.18 227.3 28.7 0.170 0.003 27-0014 Powderhorn 11/7/2017 10:07 5 3.97 81.4 11.7 8.19 226.6 27.8 27-0014 Powderhorn 11/7/2017 10:07 6 3.97 81.3 11.69 8.21 227.4 42.2 0.168 0.003 49 <5.00 27-0014 Powderhorn 11/7/2017 10:06 6.6 3.98 81.6 11.73 8.22 227.8 28.8 27-654 Spring 1/30/2017 11:30 0 0.31 1.5 0.21 7.04 2024 788 11.20 7.87 19.700 0.987 0.814 3.740 3.750 0.078 360 590 578 81.48 27-654 Spring 1/30/2017 11:29 1 2.82 3.2 0.42 6.93 2584 74.4 27-654 Spring 1/30/2017 11:28 2 5.12 1.5 0.18 6.67 3047 6.8 27-654 Spring 1/30/2017 11:27 3 7.4 1 0.11 6.47 4204 12 27-654 Spring 1/30/2017 11:27 4 8.65 0.3 0.03 6.37 4966 19.5 0.999 0.804 27-654 Spring 1/30/2017 11:26 5 8.58 0.2 0.02 6.3 5263 22 27-654 Spring 1/30/2017 11:26 6 8.37 0.2 0.02 6.26 5457 28.7 6.453 5.857 1217 54.38 27-654 Spring 1/30/2017 11:25 7 8.01 0.4 0.04 6.23 5694 29.9 27-654 Spring 4/11/2017 10:56 1.14 0 9.68 140.1 15.64 7.95 2141 0 133.00 30.40 17.100 0.530 0.127 1.890 2.470 0.107 336 530 580 87.48 0.361 27-654 Spring 4/11/2017 10:55 1 9.94 425.3 47.11 7.92 2691 193.2
2017 Water Resources Report - Minneapolis Park Recreation Board Page B23 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-654 Spring 4/11/2017 10:53 2 6.35 0.1 0.02 6.61 3349 11 27-654 Spring 4/11/2017 10:53 3 6.29 0.2 0.03 6.5 4157 12.7 27-654 Spring 4/11/2017 10:52 4 7.21 0.3 0.04 6.42 4650 15.2 4.550 2.997 27-654 Spring 4/11/2017 10:52 5 7.97 0.3 0.03 6.34 5064 19.8 27-654 Spring 4/11/2017 10:51 6 8.23 0.5 0.06 6.25 5371 25.7 7.340 6.447 1252 43.95 27-654 Spring 4/11/2017 10:50 7 8.26 0.7 0.08 6.2 5549 30.9 27-654 Spring 5/8/2017 13:14 1.44 0 17.75 11.6 1.07 7.46 2388 68.8 5.90 5.28 17.000 0.551 0.404 2.080 2.540 <0.030 336 530 565 74.80 1.520 27-654 Spring 5/8/2017 13:13 1 14.71 0.5 0.05 7.23 2352 114.9 27-654 Spring 5/8/2017 13:12 2 10.41 0.2 0.02 6.85 3294 175.8 27-654 Spring 5/8/2017 13:11 3 7.28 0.1 0.02 6.72 4212 169.9 27-654 Spring 5/8/2017 13:10 4 7.28 0.2 0.02 6.65 4655 174.5 3.840 3.410 27-654 Spring 5/8/2017 13:09 5 7.82 0.3 0.03 6.59 5016 260.9 27-654 Spring 5/8/2017 13:08 6 8.17 0.4 0.04 6.55 5384 312.8 27-654 Spring 5/8/2017 13:07 7 8.33 0.4 0.05 6.56 5516 378.2 27-654 Spring 5/8/2017 13:06 7.3 8.88 0.7 0.08 6.58 5568 3000 27-654 Spring 6/8/2017 11:31 1.8 0 23.98 20 1.63 7.35 2052 5.6 6.66 2.96 14.000 0.535 0.458 1.738 513 27-654 Spring 6/8/2017 11:29 1 19.96 0.6 0.05 7.06 2286 21.9 27-654 Spring 6/8/2017 11:28 2 12.45 0.1 0.02 6.74 3385 26.8 27-654 Spring 6/8/2017 11:27 3 8.5 0.2 0.03 6.55 4413 202.9 27-654 Spring 6/8/2017 11:26 4 7.66 0.2 0.02 6.45 4812 218.4 4.240 4.194 27-654 Spring 6/8/2017 11:25 5 7.83 0.2 0.03 6.36 5175 253.5 27-654 Spring 6/8/2017 11:24 6 8.06 0.3 0.03 6.31 5472 293.8 7.123 6.779 1402 27-654 Spring 6/8/2017 11:23 7 8.49 0.4 0.05 6.29 5564 1575 27-654 Spring 7/14/2017 12:09 1.15 0 21.82 2.9 0.25 7.08 2131 106.3 48.51 11.06 10.300 0.314 0.252 1.350 1.427 <0.030 300 448 541 68.70 0.550 27-654 Spring 7/14/2017 12:08 1 19.78 0.5 0.05 6.91 2348 144.8 27-654 Spring 7/14/2017 12:07 2 14.34 0.8 0.08 6.66 3404 219.5 27-654 Spring 7/14/2017 12:06 3 9.94 0.5 0.06 6.49 4377 253.9 27-654 Spring 7/14/2017 12:04 4 8.39 0.4 0.04 6.41 4819 276.4 5.017 4.602 27-654 Spring 7/14/2017 12:03 5 8.02 0.4 0.04 6.36 5165 251.5 27-654 Spring 7/14/2017 12:02 6 8.17 0.3 0.04 6.33 5440 289.8 6.236 5.975 1223 72.00 27-654 Spring 7/14/2017 12:01 7 8.34 0.4 0.04 6.35 5533 307 27-654 Spring 7/14/2017 12:01 7.2 8.56 0.9 0.1 6.39 5658 2145 27-654 Spring 8/9/2017 11:24 0.95 0 20.41 16.3 1.44 7.12 2095 76.6 81.70 55.47 13.200 0.404 0.283 1.427 607 27.00 27-654 Spring 8/9/2017 11:23 1 18.78 0.4 0.03 6.97 2357 98.4 27-654 Spring 8/9/2017 11:22 2 14.53 0.5 0.05 6.79 3475 121.8 27-654 Spring 8/9/2017 11:21 3 10.62 0.8 0.09 6.66 4354 168.7 27-654 Spring 8/9/2017 11:20 4 8.71 0.6 0.07 6.6 4873 205.4 4.322 4.003 27-654 Spring 8/9/2017 11:18 5 8.28 0 0 6.58 5207 232.4 27-654 Spring 8/9/2017 11:17 6 8.21 0 0 6.59 5384 248.9 6.829 5.910 1353 27-654 Spring 8/9/2017 11:17 7 8.41 0 0 6.63 5558 310.7 27-654 Spring 9/13/2017 11:23 0.75 0 21.12 14.6 1.25 6.95 2085 120.4 152.13 39.44 11.950 0.549 0.405 1.811 544 27-654 Spring 9/13/2017 11:23 1 18.34 3.5 0.32 6.9 2174 144.1 27-654 Spring 9/13/2017 11:24 2 15.96 0.5 0.05 6.67 2907 171.4 27-654 Spring 9/13/2017 11:24 3 11.87 0.5 0.05 6.5 4268 187.5 27-654 Spring 9/13/2017 11:25 4 9.6 0.4 0.05 6.47 4773 201 5.038 4.780 27-654 Spring 9/13/2017 11:25 5 8.67 0.5 0.05 6.45 5082 207.6 27-654 Spring 9/13/2017 11:26 6 8.26 0.5 0.06 6.47 5390 275.9 6.913 6.622 1361 27-654 Spring 9/13/2017 11:26 7 8.27 0.6 0.07 6.5 5506 405 27-654 Spring 11/7/2017 11:34 0.9 0 4.43 65.2 9.19 7.31 2250 10.4 259.00 41.00 17.400 0.817 0.530 2.660 2.710 <0.030 326 500 534 65.11 0.580 27-654 Spring 11/7/2017 11:34 1 4.28 60.1 8.51 7.27 2250 11.2 27-654 Spring 11/7/2017 11:34 2 4.24 49.5 7.02 7.25 2252 13.5 27-654 Spring 11/7/2017 11:33 3 8.39 2.5 0.32 6.89 4002 17.2 27-654 Spring 11/7/2017 11:33 4 10 2.5 0.31 6.81 4746 19.2 4.231 3.803 27-654 Spring 11/7/2017 11:32 5 9.17 2.5 0.31 6.79 5094 22.2 27-654 Spring 11/7/2017 11:32 6 8.45 2.4 0.3 6.78 5354 26.9 7.198 6.595 1340 75.65 27-654 Spring 11/7/2017 11:31 7 8.17 2.5 0.32 6.81 5539 30.8 27-0037 Wirth 1/18/2017 11:36 0 0.67 77.1 10.77 7.8 855.8 0 10.55 2.77 9.210 0.028 0.005 0.771 0.963 0.316 202 278 144 13.01 27-0037 Wirth 1/18/2017 11:35 1 2.26 73.2 9.79 7.73 848.5 0 27-0037 Wirth 1/18/2017 11:34 2 2.39 64.3 8.57 7.67 849.1 0 27-0037 Wirth 1/18/2017 11:33 3 2.61 38.3 5.08 7.5 850.7 0 27-0037 Wirth 1/18/2017 11:31 4 2.74 24.9 3.29 7.42 879 0 0.025 0.008 27-0037 Wirth 1/18/2017 11:30 5 2.85 21.3 2.8 7.37 922.2 0
2017 Water Resources Report - Minneapolis Park Recreation Board Page B24 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0037 Wirth 1/18/2017 11:29 6 3.11 7 0.92 7.31 1023 0 27-0037 Wirth 1/18/2017 11:28 7 3.31 8 1.04 7.27 1294 1.1 0.036 0.018 178 16.39 27-0037 Wirth 1/18/2017 11:27 7.7 3.32 20.9 2.7 7.18 2737 7.9 27-0037 Wirth 4/19/2017 11:02 1.4 0 12.48 109 11.4 8.4 886 10.8 21.10 6.38 7.850 0.068 0.008 0.630 0.680 0.045 217 292 116 16.07 <0.250 27-0037 Wirth 4/19/2017 11:02 1 12.45 108.3 11.33 8.38 885.4 9.8 27-0037 Wirth 4/19/2017 11:01 2 12.32 105.3 11.06 8.29 886.9 3.7 27-0037 Wirth 4/19/2017 11:00 3 10.65 73.7 8.04 7.92 892.1 2.3 27-0037 Wirth 4/19/2017 10:59 4 9.09 51.8 5.86 7.75 894.3 0.6 0.060 0.006 27-0037 Wirth 4/19/2017 10:58 5 7.94 25.1 2.92 7.55 898.7 1.2 27-0037 Wirth 4/19/2017 10:56 6 6.62 3.4 0.41 7.44 917 1.8 27-0037 Wirth 4/19/2017 10:55 7 5.71 0 0 7.4 1063 6.6 0.065 0.012 135 14.40 27-0037 Wirth 4/19/2017 10:54 7.4 5.61 0.5 0.06 7.3 1655 21.6 27-0037 Wirth 5/10/2017 11:01 4.08 0 16.86 117.5 11.09 8.3 877.5 9.7 1.36 0.74 5.900 0.030 <0.003 <0.500 <0.500 0.045 213 88 147 15.60 0.349 27-0037 Wirth 5/10/2017 11:00 1 16.64 120.3 11.42 8.28 878.4 11.7 27-0037 Wirth 5/10/2017 10:59 2 15.4 112.4 10.95 8.2 881.7 14.6 27-0037 Wirth 5/10/2017 10:57 3 13.13 96.1 9.84 8.07 885.6 20.8 27-0037 Wirth 5/10/2017 10:56 4 11.11 79.3 8.5 8 884.9 29.5 0.036 <0.003 27-0037 Wirth 5/10/2017 10:54 5 9.87 54.7 6.04 7.88 886.7 35 27-0037 Wirth 5/10/2017 10:53 6 8.94 7.9 0.9 7.72 919.7 44.2 27-0037 Wirth 5/10/2017 10:51 7 8.01 0 0 7.63 1065 124.1 0.089 0.007 171 13.30 27-0037 Wirth 5/10/2017 10:50 7.4 7.42 0.4 0.04 7.57 1329 900 27-0037 Wirth 5/25/2017 11:13 3.5 0 15.54 102.9 9.93 8.17 809.5 0 2.69 0.72 0.027 0.005 <0.500 147 27-0037 Wirth 5/25/2017 11:12 1 15.56 104.6 10.09 8.14 805.7 47.5 27-0037 Wirth 5/25/2017 11:11 2 15.01 95.9 9.35 8.05 807.2 61.2 27-0037 Wirth 5/25/2017 11:10 3 14.03 75.8 7.56 7.93 808.7 78.3 27-0037 Wirth 5/25/2017 11:10 4 12.3 78 8.08 7.88 879.4 98.5 0.024 0.003 27-0037 Wirth 5/25/2017 11:09 5 10.62 43.4 4.67 7.76 888.5 138.1 27-0037 Wirth 5/25/2017 11:08 6 9.38 0 0 7.66 924.8 208.8 27-0037 Wirth 5/25/2017 11:07 7 8.24 0 0 7.56 1080 320.3 0.134 0.023 190 27-0037 Wirth 5/25/2017 11:07 7.5 7.62 0 0 7.41 1409 304 27-0037 Wirth 6/7/2017 10:00 2.6 0 22.84 111.2 9.4 8.45 825.5 5.6 3.33 2.40 0.890 0.018 0.003 0.501 126 27-0037 Wirth 6/7/2017 10:00 1 22.77 110.9 9.38 8.45 826.2 6.9 27-0037 Wirth 6/7/2017 9:59 2 21.11 126 11 8.38 834.8 11.7 27-0037 Wirth 6/7/2017 9:58 3 17.38 120 11.3 8.32 850.9 20.6 27-0037 Wirth 6/7/2017 9:56 4 13.93 121.8 12.35 8.33 877 41.6 0.031 0.003 27-0037 Wirth 6/7/2017 9:56 5 11.4 28 3.01 7.98 905.4 52.4 27-0037 Wirth 6/7/2017 9:55 6 9.64 0.2 0.02 7.95 945.8 52.9 27-0037 Wirth 6/7/2017 9:54 7 8.41 1.4 0.16 7.99 1127 275.6 0.041 0.004 164 27-0037 Wirth 6/23/2017 11:16 3.3 0 22.81 102.6 8.56 8.37 797.7 0 4.49 1.42 0.021 0.004 <0.500 137 27-0037 Wirth 6/23/2017 11:16 1 22.77 102.5 8.56 8.37 798 0 27-0037 Wirth 6/23/2017 11:15 2 22.72 101.5 8.48 8.33 798.5 0.5 27-0037 Wirth 6/23/2017 11:14 3 21.02 85.8 7.41 8.18 829 0.4 27-0037 Wirth 6/23/2017 11:14 4 16.1 90.5 8.64 8.18 872.2 14.5 0.031 0.009 27-0037 Wirth 6/23/2017 11:13 5 12.41 34 3.52 8.05 907.2 48.4 27-0037 Wirth 6/23/2017 11:12 6 10.15 0 0 7.95 960.8 179.6 27-0037 Wirth 6/23/2017 11:11 7 9.37 0 0 7.75 1140 59.5 0.181 0.043 169 27-0037 Wirth 6/23/2017 11:10 7.1 8.88 0 0 7.93 1180 13.3 27-0037 Wirth 7/13/2017 10:14 2.7 0 25.48 112.8 9.05 8.28 778.8 0 5.97 <0.500 2.080 0.026 0.004 <0.500 0.526 <0.030 162 232 131 14.80 0.262 27-0037 Wirth 7/13/2017 10:14 1 25.48 113.5 9.11 8.27 778.6 12.9 27-0037 Wirth 7/13/2017 10:13 2 25.2 113.3 9.14 8.2 782.1 25.5 27-0037 Wirth 7/13/2017 10:12 3 22.25 95.9 8.18 7.95 813.4 42.5 27-0037 Wirth 7/13/2017 10:11 4 18.63 46.7 4.27 7.87 851.9 57.2 0.037 0.011 27-0037 Wirth 7/13/2017 10:11 5 14.47 43.4 4.34 7.84 906 84 27-0037 Wirth 7/13/2017 10:10 6 11.21 0 0 7.76 961.3 130.5 27-0037 Wirth 7/13/2017 10:10 7 9.27 0 0 7.65 1157 177.1 0.359 0.068 172 8.88 27-0037 Wirth 7/24/2017 10:35 2.33 0 25.46 111.1 8.92 8.15 769.7 2.9 11.94 3.51 0.032 0.006 0.535 131 27-0037 Wirth 7/24/2017 10:32 1 25.31 111.9 9.01 8.12 768.6 9.2 27-0037 Wirth 7/24/2017 10:30 2 25.12 93.4 7.55 7.92 770.8 19 27-0037 Wirth 7/24/2017 10:29 3 24.03 42.8 3.53 7.66 808.5 31.3 27-0037 Wirth 7/24/2017 10:28 4 19.45 0.8 0.07 7.68 866.2 53.6 0.070 0.005 27-0037 Wirth 7/24/2017 10:27 5 14.95 0.3 0.03 7.69 908.7 85.7 27-0037 Wirth 7/24/2017 10:26 6 11.57 0.3 0.03 7.65 982.5 123
2017 Water Resources Report - Minneapolis Park Recreation Board Page B25 Red and underlined data are suspect due to monthly performance failure.
Date Time Secchi Depth Temp DO pH SpCond TurbSC Chl-a Pheo-a Silica TP SRP TKN TN NO3NO2 Alk Hard Cl SO4 E. Coli NH3 Lake ID Lake Name MM/DD/YYYY HH:MM:SS meters meters °C %DO mg/L units µS/cm NTU mg/M3 mg/M3 mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mpn/100mL mg/L 27-0037 Wirth 7/24/2017 10:24 7 9.4 0.1 0.01 7.57 1190 158.8 0.833 0.005 187 27-0037 Wirth 7/24/2017 10:23 7.7 9.18 0 0 7.57 1343 250.8 27-0037 Wirth 8/8/2017 12:07 1.54 0 24.17 135 11.15 8.42 756.1 2.4 12.40 2.03 4.840 0.033 0.005 <0.500 135 <1 27-0037 Wirth 8/8/2017 12:06 1 24 131.2 10.87 8.23 756.1 9.6 27-0037 Wirth 8/8/2017 12:05 2 22.96 85.8 7.25 8.01 764.7 14.2 27-0037 Wirth 8/8/2017 12:05 3 22.12 7.5 0.65 7.92 779.2 23.9 27-0037 Wirth 8/8/2017 12:04 4 20.09 0.4 0.03 7.89 847.9 40.5 0.061 0.005 27-0037 Wirth 8/8/2017 12:03 5 15.37 0 0 7.9 912.5 60.5 27-0037 Wirth 8/8/2017 12:02 6 11.59 0.2 0.02 7.84 1006 139.1 27-0037 Wirth 8/8/2017 12:01 7 9.63 0 0 7.8 1190 178.1 0.510 0.053 182 27-0037 Wirth 8/8/2017 12:00 7.1 9.67 0 0 7.89 1205 179.6 27-0037 Wirth 8/21/2017 11:42 1.65 0 24.79 138 11.19 8.39 700.2 28.5 11.52 0.63 0.031 0.005 0.663 131 27-0037 Wirth 8/21/2017 11:42 1 23.81 141.3 11.67 8.34 700.1 32.2 27-0037 Wirth 8/21/2017 11:41 2 22.12 109.2 9.32 8.09 710.8 44.8 27-0037 Wirth 8/21/2017 11:40 3 21.34 13.8 1.19 7.88 739.8 63.6 27-0037 Wirth 8/21/2017 11:39 4 20.23 3.2 0.29 7.87 799.5 81 0.036 0.005 27-0037 Wirth 8/21/2017 11:38 5 15.94 0.1 0.01 7.85 907 107.4 27-0037 Wirth 8/21/2017 11:38 6 12.09 0 0 7.8 1003 130.9 27-0037 Wirth 8/21/2017 11:37 7 10.44 0 0 7.74 1163 148.4 0.458 0.110 173 27-0037 Wirth 8/21/2017 11:36 7.3 10.32 0 0 7.77 1210 157 27-0037 Wirth 9/11/2017 9:08 2.45 0 19.87 112.7 10.12 7.82 702.4 7.2 15.72 1.56 5.810 0.027 0.004 0.564 134 27-0037 Wirth 9/11/2017 9:07 1 19.87 112.5 10.09 7.74 702.5 10.2 27-0037 Wirth 9/11/2017 9:06 2 19.88 111.8 10.03 7.62 703 15 27-0037 Wirth 9/11/2017 9:05 3 19.7 96.6 8.7 7.39 704.6 22.7 27-0037 Wirth 9/11/2017 9:04 4 18.87 10.6 0.97 7.24 736.4 37.7 0.033 0.005 27-0037 Wirth 9/11/2017 9:03 5 16.03 0.2 0.02 7.12 903 55.7 27-0037 Wirth 9/11/2017 9:03 6 12.87 0.1 0.01 7.05 993.6 81.5 27-0037 Wirth 9/11/2017 9:01 7 10.47 0.1 0.01 6.98 1178 107.2 1.076 0.029 189 27-0037 Wirth 9/11/2017 9:00 7.6 10.16 0.3 0.03 7.04 1202 71.7 27-0037 Wirth 9/27/2017 9:45 2.4 0 20.28 74.7 6.66 7.66 720.6 16.09 3.35 0.038 0.003 0.622 122 27-0037 Wirth 9/27/2017 9:44 1 20.28 73.9 6.59 7.98 719.6 27-0037 Wirth 9/27/2017 9:42 2 20.28 72.5 6.46 7.82 719.6 27-0037 Wirth 9/27/2017 9:41 3 20 7.2 0.65 7.29 738 27-0037 Wirth 9/27/2017 9:39 4 19.02 6.8 0.62 7.17 768.9 0.041 0.003 27-0037 Wirth 9/27/2017 9:38 5 16.39 6.7 0.65 7 913.8 27-0037 Wirth 9/27/2017 9:37 6 12.77 6.8 0.71 6.81 1079 27-0037 Wirth 9/27/2017 9:36 7 10.92 7.1 0.77 6.7 1205 1.640 0.077 183 27-0037 Wirth 11/9/2017 9:22 2.65 0 4.45 85.6 10.98 7.63 748.7 12.6 13.61 2.82 8.860 0.045 0.004 0.625 0.747 0.091 181 252 129 11.22 0.283 27-0037 Wirth 11/9/2017 9:22 1 4.48 85.9 11 7.61 749.3 26.2 27-0037 Wirth 11/9/2017 9:21 2 4.49 85.8 10.99 7.56 749.2 77.5 27-0037 Wirth 11/9/2017 9:20 3 4.5 85.3 10.92 7.52 749.2 6.6 27-0037 Wirth 11/9/2017 9:19 4 4.51 84.4 10.8 7.48 749.2 1.9 0.058 0.003 27-0037 Wirth 11/9/2017 9:18 5 4.51 84.4 10.81 7.42 750.1 0.6 27-0037 Wirth 11/9/2017 9:18 6 4.51 84.4 10.8 7.34 749.2 0.1 27-0037 Wirth 11/9/2017 9:17 7 4.5 84.5 10.81 7.27 749.4 0.2 0.058 0.006 134 11.46 27-0037 Wirth 11/9/2017 9:15 7.2 4.49 84.5 10.82 7.02 749.6 8.4
2017 Water Resources Report - Minneapolis Park Recreation Board Page B26