Some Cook County lakes are losing water clarity, but some are getting healthier. Cook County Soil & Water Conservation District Water Plan Coordinator Cindy Gentz gave a report to the county board Tuesday, July 13, 2010 on the 2008-2009 volunteer lake monitoring program that was funded by the Minnesota Pollution Control Agency.
Seven lakes were assessed for phosphorus, a catalyst for plant growth; chlorophyll, an indicator of the presence of plants such as algae; and water clarity.
Plants in Cook County usually have enough nitrogen, water, and oxygen, Gentz said, but the availability of phosphorus tends to be a mitigating factor in whether plants will grow. Lakes need some vegetation, but too much plant growth can take oxygen away from fish species such as lake trout. Plants do give off oxygen, but when they die and decompose, they use up oxygen needed for a healthy lake trout population.
Poplar Lake has experienced a downward trend in water clarity since 1989, Gentz said. Caribou Lake has also experience a downward trend since 1988, at least in two of four sites sampled around the lake. Getting clean bills of health were West Bearskin, Hungry Jack, and Birch lakes, whose phosphorus levels were “really low,” Gentz said. Hungry Jack’s clarity has actually been increasing. Other lakes monitored were Onagon and Seagull, whose assessments fell within normal ranges.
The data will be used to identify problems before they get out of hand, guide land use decisions, inform property owners who can affect water quality by what they do to the watershed leading to the lakes, and evaluate the effectiveness of best management practices.
Lakes that will start being monitored this year are Agnes, Devil Track, Flour, Greenwood, Gunflint, Ward, and Pike. Another grant will fund monitoring of East Bearskin, Elbow, Gust, Leo, McFarland, and Tom lakes through 2012.
“Why do we care?” said Biz Clark of the Cook County Coalition of Lake Associations. “People like wilderness experiences on pristine lakes. Clean lakes keep property values high. I hope that Cook County will always have the most pristine lakes in the state as well as the nation.” She thanked Cindy Gentz for her work to keep Cook County lakes healthy.
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