Beaulieu Lake

Beaulieu Lake grades an F: water clarity, phosphorus, and chlorophyll-a all rate poorly, placing it among the most stressed lakes monitored in Minnesota. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

The hypereutrophic status — TSI 71 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Within the 16 graded lakes of Mahnomen County, Beaulieu Lake sits at rank 16, near the bottom of the county list.

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