Upper Cormorant Lake
Becker County, MinnesotaMesotrophic
Upper Cormorant Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.
Mesotrophic conditions dominate at Upper Cormorant Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. Upper Cormorant Lake reaches 29 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Upper Cormorant Lake covers 974 acres alongside 12.9 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within Becker County's 93 graded lakes, Upper Cormorant Lake ranks 66 — below the local median, though not at the bottom.
Zebra mussel presence at Upper Cormorant Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. Walleye are documented at Upper Cormorant Lake, one of 13 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a partial ice record — 10 observed ice-outs, centered near Apr 26. 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 2024-08-31. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Moderate clarity, visible to about 8.7 ft. Phosphorus level: 30 µg/L. Trophic State Index: 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.7 ft | C |
| Phosphorus | 30 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 50 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 29 ft |
| Surface Area | 974 acres |
| Shoreline Length | 12.9 mi |
| Littoral Zone | 48% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Upper Cormorant Lake (14-day solunar calendar)
→ Is it safe to eat fish from Upper Cormorant Lake? (mercury & PFAS guide)
→ Upper Cormorant Lake fishing regulations (limits, seasons, special rules)
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.027 m/yr | 5 |
| Phosphorus | ↑ Improving | -1.3 µg/L/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (20 observations).
Estimated open water season: 211 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2016-03-29 (2016) | 2022-05-06 (2022) |
| Ice-In | 1995-11-10 (1995) | 2017-12-07 (2017) |
Most recent ice-out: 2023-05-05
Location
County Ranking
Ranked #66 of 93 lakes in Becker County
Cleaner Lakes Within 30 Miles
Upper Cormorant Lake holds Grade C. 3 nearby lakes hold higher grades.
- AMiddle Cormorant LakeBecker County · mi · Two grade letters higher (C → A)
- ATurtle LakeBecker County · mi · Two grade letters higher (C → A)
- BIda LakeBecker County · mi · Higher grade (C → B)
Nearby Lakes in Becker County
More Minnesota Lake Rankings
State Parks Near Upper Cormorant Lake
Other Grade C Lakes in Minnesota
Mesotrophic Lakes in Minnesota
Compare Upper Cormorant Lake With Nearby Lakes
DNR Fisheries Survey Summary
13 surveys on file from MN DNR Fisheries. Most recent: 2025-08-11 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Largemouth Bass | 40.62 | 1.01 lb |
| Bluegill | 30.74 | 0.19 lb |
| Bluntnose Minnow | 17.39 | — |
| Green Sunfish | 11.78 | 0.16 lb |
| Yellow Bass | 11.53 | 0.61 lb |
| CNM | 9.62 | — |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Largemouth Bass
Bluegill
Green Sunfish
Yellow Bass
From the 2025-08-11 survey
Upper Cormorant Lake is an 856-acre, class 25 lake located in southwestern Becker County. It consists of a main basin and a long, narrow, northern arm with several shallow bays. Two narrow channels, not navigable in low water years, provide access to Rossman and Nelson Lakes to the east and eventually connect to…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Upper Cormorant Lake. 3 reports on file.
- —Fisheries Lake Survey — Upper CormorantFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — Upper CormorantFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Upper CormorantPublic Water Access Sites · MN DNR LakeFinder
EPA Impairment Status
Upper Cormorant Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN03-0588-00 · 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
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate
Most recent sample: 2024-08-31
Monitoring stations: 2