Lac la Croix Lake

Lac la Croix Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade.

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. At 168 ft of maximum depth, Lac la Croix Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. Lac la Croix Lake covers 29,597 acres alongside 482.4 miles of shoreline, large enough that conditions can vary meaningfully between bays. Within St. Louis County's 187 graded lakes, Lac la Croix Lake ranks 117 — below the local median, though not at the bottom.

An invasive species record — spiny waterflea — has been logged at Lac la Croix Lake; Minnesota PCA maintains the official infested-waters list. Walleye are documented at Lac la Croix Lake, one of 12 fish species on record for the lake. No formal public access is documented at Lac la Croix 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.