Finnegan Lake

Finnegan Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Oconto County. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

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. A maximum depth of 38 ft puts Finnegan Lake in the middle of Wisconsin's depth distribution. At 25 acres, Finnegan Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Finnegan Lake sits at rank 48 of 66 in Oconto County, in the lower half of the local distribution.

Finnegan Lake carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. The fishery includes walleye alongside the lake's other 3 documented species — a notable draw for Wisconsin anglers. Public access is available — the lake is on the Wisconsin DNR public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.