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Presented to: Reitz Lake Open House July 12, 2005 Randy Anhorn Principle Environmental Scientist Metropolitan Council Environmental Services randy.anhorn@metc.state.mn.us 651.602.8743 Lake Ecology and Water Quality and Reitz Lake Metropolitan Council Environmental Services
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Minnesotans are passionate about their lakes and rivers “Look! What a Peach I Landed–and How!” Greetings from Big Sandy Lake
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Metropolitan Council Environmental Services Ecology and Biology of Lakes
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Minnesota Ecoregions Summer Average Water Quality Values North Central Hardwood Forest TPClaSecchi Percentile( g/l) ( g/l) (m) 25-7523-505-221.5-3.2 Western Corn Belt Plains TPClaSecchi Percentile ( g/l) ( g/l) (m) 25-7565-15030-800.5-1.0
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Physiographic Lake Regions in the Twin Cities Metropolitan Area Metropolitan Council Environmental Services
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Generalized Lake Ecosystem (Summertime Average Conditions) Diagram not to scale Epilimnion (Mixed Layer) warm, light water Hypolimnion (cool, heavy water) Thermocline (prevents mixing) Metalimnion 0-4 meters 4-17 meters
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Lake Communities Limnetic Community Profundal Community Area of open water; habitat of algae, zooplankton and fish Area of no light penetration; domain of bacteria and fungi Littoral Community Aquatic plants dominant
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Reitz Lake is in the Carver Creek Watershed. Carver Creek discharges to the Minnesota River Metropolitan Council Environmental Services
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More Development (impervious surface) = More Runoff
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Water Quality The idea of lake water quality is tied to a concept of aging or “Eutrophication”
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Lake Aging Process Mesotrophic lake: sedimentation, increased nutrient levels, more abundant aquatic vegetation Oligotrophic lake: few nutrients, little aquatic vegetation Decades Centuries Nautral Eutrophication, caused by nutrient-rich nonpoint source runoff and growth and decay of aquatic vegetation Cultural Eutrophication accelerates the aging process by introducing nutrient-rich point source and additional nonpoint source runoff from human activities
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General Trophic Classification of Lakes Reitz Lake Oligotrophic Mesotrophic Eutrophic Reitz Lake Total Phosphorus ( g/l) Chlorophyll-a ( g/l) Secchi Transparency (m) ~100 26 ~100 ~ 45 8 ~ 45 ~ 2 >4 2-4 <2 ~ 2
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Relative Costs of Lake Restoration versus Prevention Costs Corrective Measures 0 Lake Restoration after Serious Degradation Extensive Lake Management Limited Lake Management Simple Prevention and Protection
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DNR ID # 10-0052 Surface area: 79 acres Watershed area: 3,600 acres W-to-S ratio46:1 Maximum depth 11.0 m (36 ft) Mean depth4.0 m (13 ft) Volume of water1,027 ac-ft % littoral58% ThermoclineYes Reitz Lake
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Lake Quality Report Card System GradePercentileTP ( g/l) CLA ( g/l) Secchi (m) A 3.0 B10-3023-3210-202.2-3.0 C30/7032-6820-481.2-2.2 D70-9068-15248-770.7-1.2 F>90>152>77<0.7
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Reitz Lake Water Quality Grades Based on Summer Means
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2004 Lake Grades CAMP and Metropolitan Council Monitored Lakes
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Using Satellite Technology to Assess Regional Water Quality on an Annual Basis
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Invasive Species Curly-leaf Pondweed Purple Loosestrife Zebra Mussels Eurasian Watermilfoil
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www.co.carver.mn.us/water/ (Carver County Environmental Services) www.metrocouncil.org/environment/index.htm (Metropolitan Council) annual lake report- /environment /RiversLakes/Lakes/index.htm annual WQ Summary- /planning/environment/environment/LWQ2004.pdf annual Satellite Summary- /planning/environment/environment/TCWaterClarity2004.pdf www.pca.mn.us (Minnesota Pollution Control Agency) www.dnr.state.mn.us/lakefind/ (Minnesota Dept. of Natural Resources) www.bwsr.state.mn.us (Board of Water and Soil Resources) www.mnlakes.org (Minnesota Lakes Association) www.shorelandmanagement.org Randy Anhorn randy.anhorn@metc.state.mn.us 651.602.8743 Some Internet Sites of Note
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