Large Scale Lake Planning
Consistent with previous surveys conducted by the WDNR in the early 1990s, lake monitoring results demonstrated that Birch Lake exhibits conditions typical for degraded (eutrophic) impoundments. For four decades, this small impoundment has trapped eroded soil and nutrients from the surrounding watershed depositing sediment as thick as five feet in some areas. These conditions have favored the growths of dense water weed (Elodea) beds and filamentous algae. The dense plant growths undermine recreational uses and the ecological balance in the lake. Dissolved oxygen levels fluctuate at extreme levels and create stressful conditions for aquatic life. The water quality problems documented previously and in 2009 will continue unless management is targeted to reverse the long term sedimentation in the lake. In spite of the degraded water quality, the bluegill population offered decent angling opportunities where open water could be found. In May 2009, the average bluegill length was about 6.9 inches with a range of 5.7 inches to 8.1 inches. Panfish typically become stunted in weedy impoundments but that was not the case for Birch Lake. Perhaps low recruitment due to poor water quality prevented overpopulation and stunting?
The Village of Barneveld proposes to complete a diagnostic study on Birch Lake, Iowa County, to assess current water quality conditions and use impairments. The project activities include: 1. estimating nutrient and sediment inputs, 2. assessing in-lake conditions and 3. assessing current condition of the outlet structure, and potential impacts to both impoundment and trout stream below the dam. Deliverables for this grant include a water resources appraisal report as part of the overall lake management plan, and all applicable ranking question deliverables.