Big Bass Lake

Big Bass Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Marathon 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.

Mesotrophic conditions dominate at Big Bass Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. At only 13 ft deep, Big Bass Lake is shallow — wind keeps the water column mixed and sediment resuspension drives phosphorus levels harder to manage. At 177 acres, Big Bass Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Among the 5 graded lakes in Marathon County, Big Bass Lake ranks 1 — in the top quartile locally.

Eurasian watermilfoil is established at Big Bass Lake, which can dampen recreational access and pressure the native plant community. Bass fishing is part of the appeal: the species list runs to 3, anchored by largemouth and/or smallmouth bass. 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.