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Adapting to Low Lake Levels and the Implications of a Changing Climate

Adapting to Low Lake Levels and the Implications of a Changing Climate. Bass Patterson Lake, Washburn County (E. Cook). Susan Knight May 24, 2014. Mildred Lake 2013 Results sampled 9 days in 2013

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Adapting to Low Lake Levels and the Implications of a Changing Climate

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  1. Adapting to Low Lake Levels and the Implications of a Changing Climate Bass Patterson Lake, Washburn County (E. Cook) Susan Knight May 24, 2014

  2. Mildred Lake 2013 Results sampled9days in 2013 water clarity ●temperature ●total phosphorus ●chlorophyllSecchidisk (summer average) =18.5 feet Northeast Georegion(summer average) = 10.6 feetChlorophyll (summer average) = 2.1 µg/l Northeast Georegion(average) = 12.3 µg/l. Total Phosphorus (summer average)=6.1 µg/l. Trophic State Index* = 40 =oligotrophic. *based on chlorophyll

  3. Declining Lake Levels • Why are some lakes more vulnerable to declining water? • What are the effects on water quality? • What are the effects on plant and animal habitats? • Why is this happening here? now?

  4. What factors affect water levels? • Lake morphology and hydrology • Landscape position • Natural variability (weather) • Short term drought (and wet) cycles • Water level control structures (dams) • Climate change • Human water use (i.e. water withdrawals)

  5. Lake Types • Seepage • Groundwater Drainage • Drainage • Impoundments • Oxbow

  6. Seepage Lake • Natural Lake • Water Source • Groundwater • Precipitation • Runoff • No Stream Outlet/ Inlet

  7. Drainage Lake • Water Source • Streams • Groundwater • Precipitation • Runoff • Stream Drained

  8. Landscape Position

  9. Response of Lakes to Drought Drainage lake Seepage lakes Seepage lakes much more vulnerable to drought. Magnuson et al. 2006

  10. LAKE BASIN SHAPE: • The shallower the grade, the more littoral zone exposed

  11. DEEP versus SHALLOW • Deep parts may be unaffected • Shallower parts highly affected • Black Oak Lake, Vilas County

  12. What factors affect water levels? • Lake morphology and hydrology • Landscape position • Natural variability (weather) • Short term drought (and wet) cycles • Water level control structures (dams) • Climate change • Human water use (i.e. water withdrawals)

  13. Current USGS Drought Watch Map

  14. Much below normal

  15. Evaporation Increasing • Fewer rainy days more sunny days • More sunny days more evaporation • Later ice-on, earlier ice-off more days of open water for evaporation • Warmer air temperatures more evaporation • Lakes shallower lake water warmer in summer • Warmer lake water more evaporation

  16. Declining Lake Levels • Why are some lakes more vulnerable to declining water? • What are the effects on water quality? • What are the effects on plant and animal habitats? • Why is this happening here? now?

  17. Consequences of Low Lake Levels on Water Quality • Shallow lakes have water quality issues that may become problems for lakes with declining water levels such as: • more mixing and more nutrient re-suspension because shallow lakes do not stratify • more mixing and increased turbidity from disturbance of bottom sediments by boat motors • lower oxygen concentrations due to more plant growth and subsequent plant decomposition

  18. Declining Lake Levels • Why are some lakes more vulnerable to declining water? • What are the effects on water quality? • What are the effects on plant and animal habitats? • Why is this happening here? now?

  19. Declining water levels and habitat changes Plants Wetlands Invertebrates Fish and wildlife

  20. Lake Habitat Zones

  21. Lake Littoral Zone • Functions • Intercepts Nutrients • Refuge from Predators • Nursery for Fish

  22. Declining water levels and woody habitat: Wood left above the water line may lead to: • Loss of habitat for fish (feeding, hiding, spawning) • Slower growth rates for fish • Loss of food chain associated with wood including algae, zooplankton and other invertebrates • Loss of habitat for vertebrates and invertebrates that rely on wood

  23. Declining water levels and invertebrates Many invertebrates are mobile and can move to deeper habitat Inverts relying on wood and emergent plant stems will lose habitat Some inverts will have trouble with different, perhaps softer substrates deeper in water Potential for huge loss of invertebrates with declining water levels

  24. Declining water levels and Fish • Reproduction will be the biggest challenge for fish in dealing with changing water levels. • Preferred substrate for spawning may not be available

  25. Declining Lake Levels • Why are some lakes more vulnerable to declining water? • What are the effects on water quality? • What are the effects on plant and animal habitats? • Why is this happening here? now?

  26. Many factors affect water levels • Natural variability (weather) • Short term drought (and wet) cycles • Lake morphology and hydrology • Landscape position • Water level control structures (dams) • Climate change • Human water use (i.e. water withdrawals)

  27. Global Warming Is Unequivocal: • The recent IPCC report has clearly stated that “warming of the climate system is unequivocal” and it is “very likely” caused by human activities.

  28. Evidence of Climate Change in the Great Lakes Region • Temperatures are rising, especially in winter. • Extreme rainfall events (24-hr and 7-day) are becoming more frequent. • Winters have become shorter. • Spring is coming earlier. • Duration of ice cover is shorter, especially on smaller lakes. Source; Edge of the Wilderness Scenic Byways SOURCE: UCS/ESA, 2003

  29. Declining Water Levels: Vulnerable Lakes, Water Quality & Habitat Changes Summary • Drought and increased evaporation responsible for declining water levels • Seepage lakes most vulnerable • As lakes become shallower, may experience: • more mixing higher nutrient levels more turbidity • more vegetation lower oxygen concentrations • Plants growing near shoreline must retreat with water line • Woody habitat exposed, no longer part of lake ecosystem • Fish: reproduction affected by changes in water levels • Climate change real and causing: increased lake evaporation changes in fish species composition

  30. Declining Water Levels: What You Can Do • Understand your lake: Be especially careful in sensitive areas • Do not to disturb shores, especially if muddy • Do not move wood – leave it so it is present • when water levels come back • Watch boat speeds: GO DEEP • Watch for and remove invasive • species, especially on shore • Remove plants on exposed shore by • hand only, unless you have a permit

  31. Anvil Lake water levels, with evident periodicity of high and low levels

  32. Acknowledgements John Magnuson, Barbara Benson, Tim Kratz, UW Madison Tim Asplund, Scott Provost, Pamela Toshner, Dick Lathrop, Frank Koshere, Carl Watras, Paul Garrison, WDNR Sandy Gillum, Vilas Co. Lake Association Brian Ewart, Berry Lake Association Bill Rose, Dale Robertson, USGS George Kraft, Samantha Kaplan, UWSP

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