South Twin Lake

South Twin Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Washburn 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. South Twin Lake reaches 29 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. South Twin Lake covers 106 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Among the 47 graded lakes in Washburn County, South Twin Lake sits at rank 17, above the county median.

An invasive species record — Chinese Mystery Snail — has been logged at South Twin Lake; Wisconsin DNR maintains the official infested-waters list. Walleye are documented at South Twin Lake, one of 4 fish species on record for the lake. Public access is available — the lake is on the Wisconsin DNR public-access list. 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.