Lake Dubay

Lake Dubay earns a D — measurements through 2026 show persistent nutrient pressure that limits clarity through the summer. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. At 7,800 acres, Lake Dubay is one of the larger lakes in Marathon County, with partial shoreline records supporting multiple distinct use patterns. Within Marathon County's 6 graded lakes, Lake Dubay ranks 4 — below the local median, though not at the bottom.

Lake Dubay has no invasive species recorded in Wisconsin state databases as of 2026, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Lake Dubay, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.