Leech Lake
Cass County, MinnesotaLimited DataMesotrophic
Leech Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.
A TSI near 45 places Leech Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. 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. Leech Lake ranks 124 of 133 in Cass County — at the lower end of the locally monitored distribution.
Leech 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 Leech Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. A documented public access point at Leech Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been logged at Leech Lake more than two dozen times, putting the median around Apr 28 — a useful baseline for tracking climate trends. 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 2021-10-23. Grade methodology: LakeGrade methodology.
Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Moderate clarity, visible to about 9 ft. Trophic State Index: 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9 ft | C |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Invasive Species
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.31 m/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (74 observations).
Estimated open water season: 200 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 1945-04-09 (1945) | 1950-05-23 (1950) |
| Ice-In | 2018-11-13 (2018) | 2021-11-25 (2021) |
Most recent ice-out: 2022-05-08
Location
County Ranking
Ranked #124 of 133 lakes in Cass County
Nearby Lakes in Cass County
More Minnesota Lake Rankings
State Parks Near Leech Lake
Other Grade C Lakes in Minnesota
Mesotrophic Lakes in Minnesota
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Leech Lake. 1 report on file.
- —Public Water Access Sites — Leech (Main Basin)Public Water Access Sites · MN DNR LakeFinder
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Ice data from Minnesota DNR Climate
Most recent sample: 2021-10-23
Monitoring stations: 1