Chain Lake

Chain Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI value of 30 puts Chain Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. A maximum depth of 42 ft puts Chain Lake in the middle of Wisconsin's depth distribution. Chain Lake is small — 76 acres alongside partial shoreline records — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Among the 66 graded lakes in Oconto County, Chain Lake ranks 2 — in the top quartile locally.

An invasive species record — Banded Mystery Snail — has been logged at Chain Lake; Wisconsin DNR maintains the official infested-waters list. The fishery is bass-led, with 3 documented species across the lake's records. 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.