Results of 2016-2020 Lake Study

In June 2021, a detailed study of Green Lake was completed by the US Geological Survey, Michigan Technological Institute, and the Green Lake Association. The project began in 2016 with the GLA securing a grant to fund the study of depleted oxygen levels within the lake’s thermocline (approx. 30’ below the lake surface). Additionally, the study evaluated phosphorus reductions needed from the watershed to improve the lake’s water quality to un-impaired levels. In the last 40 years, the lake has faced negative impacts from increased shoreland development, intensive agriculture throughout the watershed, the advent of harmful aquatic invasive species, increasingly intense rainfall events, and many of the wettest years on historical record. These are significant challenges to overcome. The results of the study are daunting. It shows that to make the changes necessary to meet our water quality goals, we must reduce phosphorus loading from our watershed by roughly 50%.

The GLSD along with our Lake Management Planning (LMP) Team partners are committed to working with our local farm community to add soil-saving best management practices (BMPs) to lands within the watershed. In September, the GLSD hosted a Watershed Farmer Appreciation event at Deacon Mills Park in Green Lake. The event was a way to recognize the farmers working to help the lake as well as promote our Watershed Soil Health Program. Through the Watershed Soil Health Program, the GLSD (with DNR funding) works with Green Lake and Fond du Lac Counties to provide cost sharing for additional seed and equipment used to plant cover crops. The more lands that are covered with root systems, the less soil leaving fields and entering Green Lake. Participation in these practices is voluntary for our agricultural community; we cannot be successful without their support.

The GLSD, GLA, and County Land Conservation Departments are working together to reach these goals. One of the biggest concerns shared by all is the level of staffing needed to achieve more best management practices (BMPS) in the watershed. It takes a great deal of time to make the necessary contacts, build relationships, plan projects, oversee construction, etc. to get soil-reduction projects in place on the landscape. Both Counties are stretching tight budgets while dealing with other lakes and watersheds within their boundaries. It is becoming apparent that we need additional staff/funding to get these critical projects completed on the scale necessary to make real reductions in the phosphorus loading to Green Lake.

To read the completed lake study, please visit the Green Lake Association website: