Hennepin Lake

Hennepin Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in Minnesota. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI near 44 places Hennepin Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. Hennepin Lake is a shallow lake at 14 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. At 418 acres, Hennepin Lake fits the Minnesota median for monitored lakes, with 5.5 miles of shoreline. Hennepin Lake sits at rank 51 of 77 in Hubbard County, in the lower half of the local distribution.

No invasive species are currently listed at Hennepin Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Hennepin Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.