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LakeQuality
F

Timm Lake

Yellow Medicine County, MinnesotaLimited DataEutrophic

On the LakeGrade rubric Timm Lake fails the cutoffs — a TSI of 67 and persistent algal pressure put it in the bottom tier. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

At a TSI of 67, Timm Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. 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. Within the 5 graded lakes of Yellow Medicine County, Timm Lake sits at rank 5, near the bottom of the county list.

No invasive species are currently listed at Timm Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Timm Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-05-13. Grade methodology: LakeGrade methodology.

Swimming Safety

Avoid swimming, very poor water quality, potential algae toxins

Water Quality Grade: F, Very Poor

Very murky, less than 2 ft of visibility. Trophic State Index: 67.

MetricValueGrade
Water Clarity (Secchi Depth)2 ftF
PhosphorusNo data
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)67Eutrophic

High nutrients, frequent algae, reduced clarity

Location

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County Ranking

Ranked #5 of 5 lakes in Yellow Medicine County

Nearby Lakes in Yellow Medicine County

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Timm Lake. 1 report on file.

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2024-05-13

Monitoring stations: 1