Saint Croix Flowage Lake

Saint Croix Flowage Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Douglas County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Trophically, Saint Croix Flowage Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Saint Croix Flowage Lake ranks 18 of 40 in Douglas County — solidly in the upper half of the local distribution.

Saint Croix Flowage Lake has no invasive species recorded in Wisconsin state databases as of 2020, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Saint Croix Flowage Lake, 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.