Grindle Lake

Grindle Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Oconto 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. Grindle Lake reaches 23 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 40 acres, Grindle Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Among the 66 graded lakes in Oconto County, Grindle Lake ranks 11 — in the top quartile locally.

An invasive species record — Chinese Mystery Snail — has been logged at Grindle Lake; Wisconsin DNR maintains the official infested-waters list. The fishery is bass-led, with 3 documented species across the lake's records. A documented public access point at Grindle Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.