Berger Lake
Otter Tail County, MinnesotaEutrophic
Berger Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.
At a TSI of 56, Berger 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. Within the 97 graded lakes of Otter Tail County, Berger Lake sits at rank 84, near the bottom of the county list.
No invasive species are currently listed at Berger Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Berger Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The lake lacks a documented public access point, so visitor use is limited. The lake has a partial ice record — 5 observed ice-outs, centered near Apr 9. 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 2022-09-18. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Murky, only visible to about 5 ft. Phosphorus level: 40 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | D |
| Phosphorus | 40 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.215 m/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (11 observations).
Estimated open water season: 231 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2002-03-31 (2002) | 2008-04-24 (2008) |
| Ice-In | 2003-11-11 (2003) | 2006-11-30 (2006) |
Most recent ice-out: 2008-04-24
Location
County Ranking
Ranked #84 of 97 lakes in Otter Tail County
Cleaner Lakes Within 30 Miles
Berger Lake holds Grade C. 5 nearby lakes hold higher grades.
- ABig Mcdonald LakeOtter Tail County · mi · Two grade letters higher (C → A)
- AKerbs LakeOtter Tail County · mi · Two grade letters higher (C → A)
- ALittle Mcdonald LakeOtter Tail County · mi · Two grade letters higher (C → A)
- ASybil LakeOtter Tail County · mi · Two grade letters higher (C → A)
- APaul LakeOtter Tail County · mi · Two grade letters higher (C → A)
Nearby Lakes in Otter Tail County
More Minnesota Lake Rankings
State Parks Near Berger Lake
Other Grade C Lakes in Minnesota
Eutrophic Lakes in Minnesota
EPA Impairment Status
Berger Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN56-0386-01 · Official waterbody report · Matched by proximity (2.14 km)
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
Ice data from Minnesota DNR Climate
Most recent sample: 2022-09-18
Monitoring stations: 1