Mudro Lake

On the scoring rubric Mudro Lake grades a D: clarity at 4.3 ft and phosphorus readings still being added keep it in the lower bracket for St. Louis County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. At 76 ft of maximum depth, Mudro Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. At 94 acres, Mudro Lake sits below the Minnesota median: a small water where shoreline activity has an outsized effect on water quality. Within the 215 graded lakes of St. Louis County, Mudro Lake sits at rank 201, near the bottom of the county list.

Mudro Lake has no invasive species recorded in Minnesota state databases as of 2025, though prevention practices still apply at all access points. The fishery includes walleye alongside the lake's other 7 documented species — a notable draw for Minnesota anglers. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.