2002 Johnson Lake Water Quality Report Available on Revised DNR Website


Information about the health of the Johnson Lake ecosystem is now available on the re-designed Wisconsin DNR website. You can look at the results of monitoring by members of the Johnson Lake Property Owners Association and learn how you can contribute to a healthier lake.

According to the 2002 Executive Summary, the average summer (July-Aug) secchi disk reading for Johnson Lake - Deep Hole was 8 feet. The average for the NW Georegion was 9 feet. Typically the summer water was reported as Murky and Green.

The DNR says this suggests that the secchi depth may be mostly impacted by algae. Algal blooms are generally considered to decrease the aesthetic appeal of a lake because people prefer clearer water to swim in and look at. Algae are always present in a balanced lake ecosystem. They are the photosynthetic basis of the food web. Algae are eaten by zooplankton, which are in turn eaten by fish. You will know algae are causing reduced Secchi depth if the water generally appears green when you assess the color against the white background of the secchi disc.

Chemistry data was also collected. The average summer Chlorophyll was 4 µg/l (compared to a NW Georegion summer average of 12 µg/l). The summer Total Phosphorus average was 17 µg/l. This compares to a Total Phosphorus average of 31 µg/l for the NW Georegion. Lakes that have more than 20 ug/l and impoundments that have more than 30 µg/l of total phosphorus may experience noticable algae blooms.

The overall TSI for Johnson Lake - Deep Hole is 45. The TSI suggests that Johnson Lake is mesotrophic. Mesotrophic lakes are characterized by moderately clear water, but have a increasing chance of low dissolved oxygen in deep water during the summer.

Click here to see the readings for 2002


JLPOA volunteers continue regular water quality testing, in cooperation with the Wisconsin DNR. You can help keep the lake healthy by leaving as much natural vegetation as possible along your shoreline. These plants control wave erosion and consume nutrients which enter the lake in runoff. You can help limit those algae-encouraging nutrients by avoiding lawn fertilizers which contain Phosphorus.

Posted: Tue - September 23, 2003 at 05:18 PM      

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Content Copyright 2004-2006, Johnson Lake Property Owners Association, Inc.