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LakeQuality
F

Cowhorn Lake

Itasca County, MinnesotaLimited DataEutrophic

On the LakeGrade rubric Cowhorn Lake fails the cutoffs — a TSI of 64 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 64, Cowhorn 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. Cowhorn Lake ranks 140 of 141 in Itasca County — at the lower end of the locally monitored distribution.

No invasive species are currently listed at Cowhorn Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Cowhorn Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. A documented public access point at Cowhorn Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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 2024-08-11. 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 2.5 ft of visibility. Trophic State Index: 64.

MetricValueGrade
Water Clarity (Secchi Depth)2.5 ftF
PhosphorusNo data
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)64Eutrophic

High nutrients, frequent algae, reduced clarity

Water Quality Trend: Improving

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.031 m/yr5

Location

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County Ranking

Ranked #140 of 141 lakes in Itasca County

Nearby Lakes in Itasca County

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Cowhorn Lake. 3 reports on file.

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2024-08-11

Monitoring stations: 1