Big Saint Germain Lake

Water Quality

One measure of a lakes health is the trophic state, which relates to the amount of algae in the water. The average summer trophic state for the last 5 years was 55 (Eutrophic) and was determined using chlorophyll data. For a Two-Story lake, this is considered Poor.

Big Saint Germain Lake has been monitored by volunteers since 1989. Volunteers monitor water clarity with a black and white Secchi disk. Some also collect water samples, which are sent to the State Lab of Hygiene to be analyzed. Volunteers are the source of the majority of Wisconsin's lake water quality data, and their dedication is greatly appreciated. Additional monitoring has been done through projects funded in part by DNR Lake Grants and Aquatic Invasive Species Grants. Reports and graphs featuring data collected by volunteers, DNR staff and others can be viewed below.

Water Quality Reports and Graphs

Station Name	Station ID	Map	Max Year	Reports
Big St Germain Lake - Deep Hole	643051	Map	2024	Details
Big St. Germain Lake - Eastern Part Of Lake	10042272	Map	2015	Details
Big St. Germain Lake - North Of Bradford Point	10042271	Map	2015	Details