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Leek Lake

Otter Tail County, MinnesotaMesotrophic

On the LakeGrade rubric, Leek Lake pulls an A: clarity at 11.0 ft and 15 µg/L of phosphorus put it in the top bracket for Minnesota. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.

Mesotrophic conditions dominate at Leek Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. 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. Among the 97 graded lakes in Otter Tail County, Leek Lake sits at rank 44, above the county median.

Leek Lake is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. The state fisheries records do not list documented species for Leek 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. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-16. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

Good clarity, visible to about 11 ft. Phosphorus level: 15 µg/L. Trophic State Index: 43.

MetricValueGrade
Water Clarity (Secchi Depth)11 ftB
Phosphorus15 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)43Mesotrophic

Moderate nutrients, good water quality

Invasive & Introduced Species

Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.

flowering rushzebra mussel

Water Quality Trend: Improving

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

MetricTrendChange/YearYears
Water Clarity Improving+0.682 m/yr5
Phosphorus Improving-1.3 µg/L/yr5
See year-by-year chart →

Location

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County Ranking

Ranked #44 of 97 lakes in Otter Tail County

Nearby Lakes in Otter Tail County

DNR Reports & Resources

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

EPA Impairment Status

Leek Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Mercury

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit MN56-0532-02 · Official waterbody report

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

Grading methodology based on Metropolitan Council standards

Most recent sample: 2024-09-16

Monitoring stations: 1