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. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Mesotrophic conditions dominate at Lac la Croix Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. 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. With 29,597 acres of surface and 482.4 miles of shoreline, Lac la Croix Lake is a large water by Minnesota standards — recreational pressure is spread across a long shoreline. Lac la Croix Lake sits at rank 118 of 187 in St. Louis County, in the lower half of the local distribution.

An invasive species record — spiny waterflea — has been logged at Lac la Croix Lake; Minnesota PCA maintains the official infested-waters list. The fishery includes walleye alongside the lake's other 12 documented species — a notable draw for Minnesota anglers. No formal public access is documented at Lac la Croix Lake — most use is by shoreline residents and their guests. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.