Red Rock Lake

The LakeGrade rubric puts Red Rock Lake at a C: clarity at 3.6 ft, 54 µg/L of phosphorus, and a TSI of 60 signal an intermediate trophic state. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. The lake bottoms out at 22 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. The lake's 904 acres and 11.7 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Within the 51 graded lakes of Douglas County, Red Rock Lake sits at rank 41, near the bottom of the county list.

Red Rock Lake is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. The fishery includes walleye alongside the lake's other 13 documented species — a notable draw for Minnesota anglers. A documented public access point at Red Rock Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a partial ice record — 17 observed ice-outs, centered near Apr 7. 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.