The document discusses shallow lake ecology, focusing on Crooked Lake in Anoka County, Minnesota. It provides an overview of physical properties, biological characteristics, water quality drivers, and diagnostic tools for shallow lakes. Key points include: 1) Shallow lakes are defined as having a maximum depth of 15 feet or less, or with 80% of the area shallow enough to support aquatic plants. 2) Water quality in shallow lakes is driven by nutrients like phosphorus, with high phosphorus leading to turbid conditions and low phosphorus resulting in clear water. 3) Management strategies aim to switch shallow lakes from a turbid state to a clear water state and include external nutrient control, biomanipulation of

1. Shallow Lake Ecology Crooked Lake Anoka County, MN February 2008 Coon Creek Watershed District Wenck Associates, Inc.

3. Crooked Lake Watershed

4. Physical Data Watershed area does not include the lake surface area

5. http://waterontheweb.org/under/lakeecology/index.html

8. Aquatic Communities – Plankton & Fisheries

9. Lake Zones

11. Trophic Cascades Adapted from Metropolitan Council Environmental Services Pike Clear-water state Carp, minnows Invertebrates Algae Submerged plants Sediment Resuspension Turbid-water state

13. Carp Exclusion

14. Crooked Lake Fish Community

15. Crooked Lake Fish Community

16. Refuge for small invertebrates (especially Cladocera) against fish predations AQUATIC PLANTS “ Services” to people through bank edge protection against erosion, products, (reed, sedge, biomass, fish and fowl), amenity and conservation Absorb wind and wave energy, minimizing turbidity caused by sediment resuspension High production creates sediment conditions favoring nitrogen loss by denitrification and phosphate availability through release Food for invertebrates Food for adult fish Habitat, food cover and nesting materials for birds Provide habitat for attached algae Maintenance of clear water Maintenance of clear water Moss et al. 1996 Refuges for small fish against predators Cover and habitat for piscivorous fish Spawning habitat for fish

17. Typical Littoral Zone Vegetation Graphic from: Smith, R.L. Elements of Ecology . 1992 Third Addition.

18. Crooked Lake Aquatic Vegetation

22. Relationship between TP and Transparency Oligotrophic Mesotrophic Eutrophic Hyper- Eutrophic Total Phosphorus ( µ g/L)

23. MPCA Standards

24. Total Phosphorus and Chlorophyll-a Crooked Lake

25. Secchi Depth Crooked Lake

27. Phosphorus Sources

28. Lake Response Model

32. More Development (impervious surface) = More Runoff

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

34. McComas, Unpublished data

38. Crooked Lake Shoreline Characteristics

42. Lake Response to Restoration

43. Lake Response to Restoration

44. Competing Management Goals

45. Design Strategy Implement Monitor Evaluate Assess Progress Adaptive Management