Thole Lake

On the LakeGrade rubric Thole Lake fails the cutoffs — a TSI of 66 and persistent algal pressure put it in the bottom tier. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

At a TSI of 66, Thole Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. A maximum depth of just 12 ft means sediment-bound phosphorus releases back into the water column whenever wind stirs the bottom — a classic shallow-lake dynamic. At 119 acres, Thole Lake fits the Minnesota median for monitored lakes, with 5.2 miles of shoreline. Within Scott County's 24 graded lakes, Thole Lake ranks 18 — below the local median, though not at the bottom.

Eurasian watermilfoil is established at Thole Lake, which can dampen recreational access and pressure the native plant community. Bass fishing is part of the appeal: the species list runs to 12, anchored by largemouth and/or smallmouth bass. A documented public access point at Thole Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is supported by multiple sampling years from Minnesota PCA volunteers and partner agencies, giving the letter a reasonably stable foundation.