Carlos Lake

Carlos Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Douglas County. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI value of 39 puts Carlos Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Carlos Lake is unusually deep for Minnesota at 163 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. At 2,605 acres, Carlos Lake is one of the larger lakes in Douglas County, with 12.8 miles of shoreline supporting multiple distinct use patterns. Carlos Lake ranks 12 of 51 in Douglas County, putting it in the upper tier of locally monitored lakes.

Zebra mussels have been documented at Carlos Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at Carlos Lake, one of 21 fish species on record for the lake. A documented public access point at Carlos Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a partial ice record — 16 observed ice-outs, centered near Apr 21. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.