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.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.5 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 64 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.031 m/yr | 5 |
Location
County Ranking
Ranked #140 of 141 lakes in Itasca County
Nearby Lakes in Itasca County
More Minnesota Lake Rankings
State Parks Near Cowhorn Lake
Other Grade F Lakes in Minnesota
Eutrophic Lakes in Minnesota
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Cowhorn Lake. 3 reports on file.
- —Aquatic Plant Report — Cowhorn (0552)Aquatic Plant Report · MN DNR LakeFinder
- —Aquatic Plant Report — Cowhorn (2054)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — CowhornPublic Water Access Sites · MN DNR LakeFinder
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