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C

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.

Reviewed by LakeQuality Editorial Team · Updated

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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.

MetricValueGrade
Water Clarity (Secchi Depth)5 ftD
Phosphorus40 µg/LC
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)56Eutrophic

High nutrients, frequent algae, reduced clarity

Water Quality Trend: Declining

Based on 2 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.215 m/yr2

Ice Season

Historical ice data from Minnesota DNR (11 observations).

Typical Ice-Out
Apr 9
Typical Ice-In
Nov 26

Estimated open water season: 231 days

EarliestLatest
Ice-Out2002-03-31 (2002)2008-04-24 (2008)
Ice-In2003-11-11 (2003)2006-11-30 (2006)

Most recent ice-out: 2008-04-24

Location

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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.

See full comparison →

Nearby Lakes in Otter Tail County

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

Impaired biota (cause unknown)Mercury

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