Pool on Lake St. Croix

Pool on Lake St. Croix earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. 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 78 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. Pool on Lake St. Croix covers 8,393 acres alongside 124.5 miles of shoreline, large enough that conditions can vary meaningfully between bays. Within the 31 graded lakes of Washington County, Pool on Lake St. Croix sits at rank 24, near the bottom of the county list.

Eurasian watermilfoil is established at Pool on Lake St. Croix, which can dampen recreational access and pressure the native plant community. Pool on Lake St. Croix's fishery is anchored by muskellunge, with 36 documented species in total — a destination water for muskie anglers. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.