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Presented to: Reitz Lake Open House July 12, 2005 Randy Anhorn Principle Environmental Scientist Metropolitan Council Environmental Services

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Presentation on theme: "Presented to: Reitz Lake Open House July 12, 2005 Randy Anhorn Principle Environmental Scientist Metropolitan Council Environmental Services"— Presentation transcript:

1 Presented to: Reitz Lake Open House July 12, 2005 Randy Anhorn Principle Environmental Scientist Metropolitan Council Environmental Services Lake Ecology and Water Quality and Reitz Lake Metropolitan Council Environmental Services

2 Minnesotans are passionate about their lakes and rivers “Look! What a Peach I Landed–and How!” Greetings from Big Sandy Lake

3 Metropolitan Council Environmental Services Ecology and Biology of Lakes

4 Minnesota Ecoregions Summer Average Water Quality Values North Central Hardwood Forest TPClaSecchi Percentile(   g/l) (   g/l) (m) Western Corn Belt Plains TPClaSecchi Percentile (   g/l) (   g/l) (m)

5 Physiographic Lake Regions in the Twin Cities Metropolitan Area Metropolitan Council Environmental Services

6 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

7 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

8 Reitz Lake is in the Carver Creek Watershed. Carver Creek discharges to the Minnesota River Metropolitan Council Environmental Services

9 More Development (impervious surface) = More Runoff

10 Water Quality The idea of lake water quality is tied to a concept of aging or “Eutrophication”

11 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

12 General Trophic Classification of Lakes Reitz Lake Oligotrophic Mesotrophic Eutrophic Reitz Lake Total Phosphorus (  g/l) Chlorophyll-a (  g/l) Secchi Transparency (m) ~ ~100 ~ 45 8 ~ 45 ~ 2 >4 2-4 <2 ~ 2

13 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

14 DNR ID # 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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18 Lake Quality Report Card System GradePercentileTP (   g/l) CLA (   g/l) Secchi (m) A 3.0 B C30/ D F>90>152>77<0.7

19 Reitz Lake Water Quality Grades Based on Summer Means

20 2004 Lake Grades CAMP and Metropolitan Council Monitored Lakes

21 Using Satellite Technology to Assess Regional Water Quality on an Annual Basis

22 Invasive Species Curly-leaf Pondweed Purple Loosestrife Zebra Mussels Eurasian Watermilfoil

23 (Carver County Environmental Services) (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 (Minnesota Pollution Control Agency) (Minnesota Dept. of Natural Resources) (Board of Water and Soil Resources) (Minnesota Lakes Association) Randy Anhorn Some Internet Sites of Note


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