Woman Lake - Cass County, Minnesota

Woman Lake 11-0201-00 CASS COUNTYSummaryWoman Lake is located about three miles west of the city of Longville, MN inCass County. It covers 5,520 acres, which places it in the upper 5% of lakes inMinnesota in terms of size.Woman Lake is part of a chain of lakes along the Boy River. The Boy Riverenters the west side of Woman Lake from Child Lake and exits on the east sideinto Girl Lake and then continues north to Leech Lake. The Leech Lake Riverexits Leech Lake and flows east to join the Mississippi River.Woman Lake includes a central basin and several large bays. Broadwater Bay at the north end ofthe lake is the largest bay with an area of about 1,000 acres (including channel to main basin).Water quality data have been collected on Woman Lake and Broadwater Bay since 1987. Thesedata show that the lake is mesotrophic (page 9). Mesotrophic Lakes are excellent for recreationand fishing and have clear water with occasional algae blooms in late summer.The Woman Lake Property Owners Association was established in 1976. In 1978, Child and GirlLake Property Owners joined the Association. Their mission is to promote the improvement ofliving, recreational, environmental and ecological conditions on lakes and waterways served by theAssociation. The Association has been involved in numerous activities including water safety,wetland conservation, land conservation, fish management, pollution, land use controls, publicaccess policies and property taxes, water quality monitoring, education, Healthy Lakes Initiative,and is a member of the Association of Cass County Lakes (ACCL).VitalsMN Lake ID: 11-0201-00County:CassEcoregion: Northern Lakes and ForestMajor DrainageBasin:Upper Mississippi RiverLatitude/Longitude: 46.94864369/-94.28222869Water Body Type: PublicMonitored Sites(Primary):Monitored Sites(Secondary):Invasive species:Data AvailabilityTransparency dataChemical dataInlet/Outlet dataWoman: 201, 207Broadwater: 102Woman: 202, 203, 205, 206Broadwater: 204none documentedPhysical CharacteristicsSurface area (acres): 5,520Littoral area (acres): 1,953% Littoral area: 35%Max depth (ft): 54 (m): 16.5Mean depth (ft): 17.8 (m): 5.4Lakeshed size (acres): 12,652Lakeshed : lake area ratio 2.3:1Inlets2 – Boy River andBlackwater CreekOutlets1 – Boy RiverAccesses2 publicNumerous yearly secchi readings from 1987-2008through the MPCA CLMP program.Total Phosphorus and Chlorophyll a data have beencollected in 1988, 2004 and 2008.No inlet or outlet monitoring has been conducted.Recommendations For recommendations refer to page 12.Woman Lake and Broadwater Bay Report generation: 2008, RMB Environmental Laboratories 1 of 12

Figure 1. Map of Wabedo Lake illustrating bathymetry, lake sample site locations, stream inlets and outletsand aerial land use. The pink shaded areas in the lake illustrate the littoral zone, where the sunlight canusually reach the lake bottom allowing aquatic plants to grow.Basin Lake Site Depth (ft) Monitoring ProgramsWoman 103 36 MPCA: 1988, 2004Woman 201 50 CLMP: 1987-2004; MPCA: 1988, 2004; Outdoor Corps: 2004Woman 202 55 CLMP: 1987-1998; MPCA: 1988, 2004Woman 203 30 CLMP: 1988-1998Woman 205 35 CLMP: 1988, 1993-2003Woman 206 35 CLMP: 2004-2007Woman 207 64 CLMP: 2005-2008; RMB Lab: 2008Broadwater 102 44 MPCA: 1988, 2004; RMB Lab: 2008Broadwater 204 50 CLMP: 1988-2003Woman Lake and Broadwater Bay Report generation: 2008, RMB Environmental Laboratories 2 of 12

Trend AnalysisFor detecting trends, a minimum of 8-10 years of data with 4 or more readings per season arerecommended. Minimum confidence accepted by the MPCA is 90%. This means that there is a90% chance that the data are showing a true trend and a 10% chance that the trend is a randomresult of the data. Only short-term trends can be determined with just a few years of data, becausethere can be different wet years and dry years, water levels, weather, etc., that affect the waterquality naturally.There is not enough historical data to perform trend analysis for total phosphorus or chlorophyll aon Woman Lake. There was enough transparency data for both basins to perform a long-termtrend analysis. The data was analyzed using the Mann Kendall Trend Analysis.Basin Lake Site Parameter Date Range Trend ProbabilityBroadwater 204 Transparency 1988-2003 Improving 99.9%Woman 201 Transparency 1987-2004 Improving 99.9%Woman 202 Transparency 1987-1998 Improving 99.9%Woman 203 Transparency 1988-1998 Improving 99.9%Woman 205 Transparency 1988-2003 Improving 95%Figure 11. Transparency trend for Woman Lake, site 201 from 1987-2004.For all sites with more than 8 years of data there is a significant improving trend in transparency(99.9% probability). Each site in Broadwater and Woman has improved an average of 4 feet intransparency. Transparency monitoring should continue in both basins so that this trend can betracked in future years.Woman Lake and Broadwater Bay Report generation: 2008, RMB Environmental Laboratories 10 of 12

Ecoregion ComparisonsMinnesota is divided into seven ecoregions based onland use, vegetation, precipitation and geology. TheMPCA has developed a way to determine the "averagerange" of water quality expected for lakes in eachecoregion. From 1985-1988, the MPCA evaluated thelake water quality for reference lakes. These referencelakes are not considered pristine, but are considered tohave little human impact and therefore arerepresentative of the typical lakes within the ecoregion.The "average range" refers to the 25 th - 75 th percentilerange for data within each ecoregion. For the purposeof this graphical representation, the means of thereference lake data sets were used.Woman Lake is in the NorthernLakes and Forests Ecoregion.The mean total phosphorus,chlorophyll a and transparency(secchi depth) for Woman Lake and Broadwater Bay are within the expectedecoregion ranges (Figures 12a-c).60300Total Phosphorus (ug/L, ppb)5040302010Chlorophyll-a (ug/L, ppb)252015105Secchi depth (ft)5101520increasedalgae0NLF EcoregionWoman LakeBroadwater Bay0a b cNLF EcoregionWoman LakeBroadwater Bay25crystalclearFigures 12a-c. Woman Lake and Broadwater Bay ranges compared to Northern Lakes and ForestEcoregion ranges. The Woman Lake total phosphorus and chlorophyll a ranges are from 29 data points ineach basin collected in May-September of 1988, 2004, and 2008. The Broadwater Bay total phosphorus andchlorophyll a ranges are from 10 data points in each basin collected in May-September of 2004 and 2008.The secchi depth range for both lakes is from 161 data points in each basin collected in May-Septemberfrom 1987-2004.Woman Lake and Broadwater Bay Report generation: 2008, RMB Environmental Laboratories 11 of 12

Inlet/Outlet Data AssessmentNo inlet or outlet data have been collected for Woman Lake or Broadwater Bay.Assessment/Findings RecommendationsTransparencyTransparency monitoring at all sites continued annually. It is important to continue transparencymonitoring weekly or at least bimonthly every year to enable year-to-year comparisons and trendanalyses.Impaired Waters Assessment 303(d) ListThere are two main types of Impaired Waters Assessment for lakes: eutrophication (excessphosphorus) for aquatic recreation and mercury in fish tissue for aquatic consumption. WomanLake was not listed as impaired for mercury in fish tissue or for eutrophication.Aquatic Recreational Use Assessment 305(b)In the 2008 MPCA Aquatic Use Assessment (305(b)), Woman Lake was classified as being fullysupporting for recreational use.Inlet/Outlet AssessmentBecause of the lack of inlet/outlet data and Woman Lake’s position in the Boy River Watershed,a mass balance project should be considered. This study answers questions about nutrientloading into the lake and nutrient budget within the lake.Organizational contacts and reference sitesChild, Girl, Woman Lake PropertyOwners AssociationCass County EnvironmentalServices DepartmentDNR Fisheries OfficeRegional Minnesota PollutionControl Agency OfficeRegional Board of Soil and WaterResources OfficePO Box 335Longville, MN 56655info@womanlakechain.orghttp://www.womanlakechain.org/303 Minnesota Avenue W, P.O. Box 3000, Walker, MN 56484-3000(218) 547-7241http://www.co.cass.mn.us/esd/home_esd.html7316 State Hwy 371 NW, Walker, MN 56484(218) 547-1683http://www.dnr.state.mn.us/lakefind/index.html7678 College Road, Suite 105, Baxter, MN 56425(218) 828-2492http://www.pca.state.mn.us1601 Minnesota Drive, Brainerd, MN 56401(218) 828-2383http://www.bwsr.state.mn.usWoman Lake and Broadwater Bay Report generation: 2008, RMB Environmental Laboratories 12 of 12