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East Loon Lake

Otter Tail County, MinnesotaOligotrophic

On the LakeGrade rubric, East Loon Lake pulls an A: clarity at 13.5 ft and 12 µg/L of phosphorus put it in the top bracket for Minnesota. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.

Trophically, East Loon Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. East Loon Lake is unusually deep for Minnesota at 105 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. At 1,044 acres, East Loon Lake is one of the larger lakes in Otter Tail County, with 17.1 miles of shoreline supporting multiple distinct use patterns. Among the 97 graded lakes in Otter Tail County, East Loon Lake sits at rank 30, above the county median.

Zebra mussel presence at East Loon Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. The fishery includes walleye among the lake's 17 documented species — a notable draw for Minnesota anglers. A documented public access point at East Loon Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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 2024-09-15. 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 13.5 ft. Phosphorus level: 12 µg/L. Trophic State Index: 40.

MetricValueGrade
Water Clarity (Secchi Depth)13.5 ftB
Phosphorus12 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)40Oligotrophic

Low nutrients, clear water, excellent for swimming

Lake Details

CharacteristicValue
Maximum Depth105 ft
Surface Area1.0K acres
Shoreline Length17.1 mi
Littoral Zone57%
Public AccessYes

Fish Species

black bullhead,black crappie,bluegill,bowfin (dogfish),brown bullhead,common carp,green sunfish,hybrid sunfish,largemouth bass,northern pike,pumpkinseed,rock bass,tullibee (cisco),walleye,white sucker,yellow bullhead,yellow perch

Click a species to see all Minnesota and Wisconsin lakes where it is found.

→ Best fishing times for East Loon Lake (14-day solunar calendar)

→ Is it safe to eat fish from East Loon Lake? (mercury & PFAS guide)

East Loon 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.

zebra mussel

Water Quality Trend: Stable

Based on 4 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.342 m/yr4
Phosphorus Declining+0.99 µg/L/yr4
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (4 observations).

Typical Ice-Out
Apr 13
EarliestLatest
Ice-Out2004-04-10 (2004)2022-05-07 (2022)
Ice-In2003-12-01 (2003)2003-12-01 (2003)

Most recent ice-out: 2022-05-07

Location

Loading map…

County Ranking

Ranked #30 of 97 lakes in Otter Tail County

Nearby Lakes in Otter Tail County

DNR Fisheries Survey Summary

8 surveys on file from MN DNR Fisheries. Most recent: 2025-07-14 (Targeted Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Bluntnose Minnow37.42
Bluegill28.100.17 lb
Green Sunfish26.110.13 lb
Largemouth Bass13.091.01 lb
IOD9.49
BCS7.27

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.

Bluegill

223 fish · 38 in · 2025-07-14
77390345678

Green Sunfish

2 fish · 33 in · 2008-07-28
2103

Largemouth Bass

24 fish · 516 in · 2025-07-14
9505678910111213141516

From the 2025-07-14 survey

Loon Lake is a 1,048-acre mesotrophic (moderately fertile) lake located in north-central Otter Tail County. The town of Vergas, MN abuts the northeast shoreline of the lake. The immediate watershed is composed primarily of agricultural land interspersed with hardwood woodlots. The lake has a maximum depth of 105 feet;…

Source: MN DNR LakeFinder Fisheries Lake Survey

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for East Loon Lake. 3 reports on file.

EPA Impairment Status

East Loon Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Mercury

Source: EPA ATTAINS assessment unit MN56-0523-00 · 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: 2024-09-15

Monitoring stations: 3