Big Portage 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 38 (Oligotrophic) and was determined using chlorophyll data. For a Deep Seepage lake, this is considered Excellent. Deep Seepage lakes stratify, or form separate layers of water, during the summer months and have no inlet or outlet.

Big Portage Lake has been monitored by volunteers since 1991. 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 Portage Lake - Deep Hole	643165	Map	2024	Details
Big Portage Lake - West Bay	643510	Map	2023	Details