Ada Lake

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

The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. At 60 ft of maximum depth, Ada Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. At 963 acres, Ada Lake fits the Minnesota median for monitored lakes, with 7.2 miles of shoreline. Ada Lake ranks 52 of 133 in Cass County — solidly in the upper half of the local distribution.

Ada Lake has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. The fishery includes walleye alongside the lake's other 16 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. Ice-out has been logged at Ada Lake more than two dozen times, putting the median around Apr 21 — a useful baseline for tracking climate trends. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.