Rush Lake

Rush Lake earns a D — measurements through 2024 show persistent nutrient pressure that limits clarity through the summer. 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 24 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. With 1,494 acres of surface and 11.0 miles of shoreline, Rush Lake is a large water by Minnesota standards — recreational pressure is spread across a long shoreline. Rush Lake ranks 26 of 31 in Chisago County — at the lower end of the locally monitored distribution.

Rush Lake carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. Rush Lake's fishery is anchored by muskellunge, with 16 documented species in total — a destination water for muskie anglers. Public access is available — the lake is on the Minnesota PCA public-access list. Multiple sampling years from Minnesota PCA volunteers and partner agencies back the grade, so the letter should hold steady absent a major watershed shift.