Des Moines Lake Water Quality
One of the most notable attributes of Des Moines Lake is the high degree of water quality that lake residents are able to enjoy. According to a recent survey of lake association members, maintaining our lake’s water quality is a high priority. Water clarity is important aesthetically and can affect property values and recreational use of a water body (Tim Asplund, WI DNR, March 2000). For the past several years, Des Moines Lake has actively participated in the Citizen Lake Monitoring Network (CLMN) in collaboration with the Wisconsin DNR. CLMN program goals include: collecting high quality data, educating and empowering volunteers, and sharing this data and knowledge. On Des Moines Lake, volunteers measure water clarity, using the Secchi Disk method, as an indicator of water quality. Volunteers also collect chemistry, temperature and dissolved oxygen data. See below for an informative summary of the annual report generated by the DNR.
Water Clarity (Secchi) Monitoring
Water clarity is a measure of the amount of particles in the water, or the extent to which light can travel through the water.
Water clarity monitoring is a process in which a volunteer lowers an 8” diameter, black & white disc (“Secchi disc”) into the deepest part of the lake to determine how far down they can see the disc as it is lowered. Water clarity monitoring is done every 10-14 days throughout the open-water season. Water clarity is a quick way to estimate lake health, and it plays an important role in determining the types of plants and animals that a water body can support.
For more information, download our Des Moines Lake Association presentation from January 2021.
You can also view an October 2020 Wisconsin DNR webinar through YouTube here.
Water Chemistry Monitoring
Chemistry volunteers, in addition to measuring water clarity and temperature, collect water samples for analysis for phosphorus and chlorophyll levels four times a year. Chlorophyll-a, is a measurement of the amount of algae that is in the water. Volunteer collected samples are sent to the State Laboratory of Hygiene (WSLH) for analysis. Training and equipment for chemistry monitoring are provided by the Wisconsin DNR. The information volunteers collect when monitoring both Secchi and water chemistry is used to determine the trophic state of the lake.
Temperature and Dissolved Oxygen
Water clarity is important for a number of reasons. It affects the depth to which aquatic plants can grow, dissolved oxygen content, and water temperature. Volunteers measure the temperature profile of the lake at 3-foot intervals from the top to the bottom of the lake. This data contributes to a measure of trophic status, or an indicator of ecosystem health.
Des Moines Lake – Deep Hole 2021 Results
Below is a narrative summary of the 2021 annual report prepared by the WI DNR. Full report can be access here.
2021 Narrative Summary
Des Moines Lake – Deep Hole was sampled 8 different days during the 2021 season.
The average summer (July-Aug) secchi disk reading for Des Moines Lake – Deep Hole (Burnett County, WBIC: 2674200) was 18.92 feet. The average for the Northwest Georegion was 9.1 feet. Typically the summer (July-Aug) water was reported as CLEAR and BLUE.
Chemistry data was collected on Des Moines Lake – Deep Hole. The average summer Chlorophyll was 1.6 µg/l (compared to a Northwest Georegion summer average of 13.2 µg/l). The summer Total Phosphorus average was __ µg/l (negligible, or below readable range). Lakes that have more than 20 µg/l and impoundments that have more than 30 µg/l of total phosphorus may experience noticeable algae blooms.
The overall Trophic State Index (based on chlorophyll) for Des Moines Lake – Deep Hole was 38. The TSI suggests that Des Moines Lake – Deep Hole was oligotrophic. This TSI suggests deeper lakes still oligotrophic, but bottom water of some shallower lakes will become oxygen-depleted during the summer.
NOTE: For a more detailed explanation, please see Interpretive Guide to CLMN Water Quality Reports