Lake Mendota

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 56 (Eutrophic) and was determined using Secchi data. For a Two-Story lake, this is considered Poor.

Lake Mendota was monitored by volunteers between 2016 and 2022. Volunteers monitor water clarity with a black and white Secchi disk. 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
LAKE MENDOTA NEAR YAHARA R. INLET WATER DEPTH ABOUT 5 FEET	10031711	Map	1997	Details
Lake Mendota - Central Deep Hole	133318	Map	2024	Details
Lake Mendota - Deep Central Region Coring Location	10046986	Map	2016	Details
Lake Mendota - Lake Mendota	206	Map	1970	Details
Lake Mendota - Pheasant Branch Deep Area	10031991	Map	2016	Details
Lake Mendota - West Side	133536	Map	1990	Details
Lake Mendota - Yahara Bay	10031720	Map	2016	Details
Lake Mendota - east end St. Cyr Rd	10043399	Map	2014	Details
Lake Mendota at Burrows Rd	10043401	Map	2014	Details
Lake Mendota at Upham Ct	10043400	Map	2014	Details