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C

Coon Lake

Anoka County, MinnesotaEutrophic

Coon Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. Clarity is the limiting factor — phosphorus is reasonable but suspended particles or algal cells keep water transparency below Minnesota norms.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. A maximum depth of 27 ft puts Coon Lake in the middle of Minnesota's depth distribution. At 1,481 acres, Coon Lake is one of the larger lakes in Anoka County, with 16.3 miles of shoreline supporting multiple distinct use patterns. Among the 24 graded lakes in Anoka County, Coon Lake sits at rank 8, above the county median.

Coon Lake carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. The fishery includes walleye among the lake's 14 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a partial ice record — 21 observed ice-outs, centered near Apr 4. Multiple sampling years from Minnesota PCA volunteers and partner agencies back the grade, so the letter should hold steady absent a major watershed shift.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-19. 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 5.6 ft. Phosphorus level: 23 µg/L. Chlorophyll-a: 7.9 µg/L. Trophic State Index: 51.

MetricValueGrade
Water Clarity (Secchi Depth)5.6 ftD
Phosphorus23 µg/LB
Chlorophyll-a (Algae)7.9 µg/LB
Trophic State Index (TSI)51Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

CharacteristicValue
Maximum Depth27 ft
Average Depth10 ft
Surface Area1.5K acres
Shoreline Length16.3 mi
Littoral Zone74%
Public AccessYes

Fish Species

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

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

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

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

Coon 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.

Eurasian watermilfoil

Water Quality Trend: Improving

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.117 m/yr5
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (32 observations).

Typical Ice-Out
Apr 4
Typical Ice-In
Nov 25

Estimated open water season: 235 days

EarliestLatest
Ice-Out2016-03-15 (2016)2018-05-01 (2018)
Ice-In2002-11-15 (2002)2001-12-20 (2001)

Most recent ice-out: 2025-03-22

Location

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County Ranking

Ranked #8 of 24 lakes in Anoka County

Cleaner Lakes Within 30 Miles

Coon Lake holds Grade C. 2 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Anoka County

DNR Fisheries Survey Summary

17 surveys on file from MN DNR Fisheries. Most recent: 2025-06-16 (Standard Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Bluegill48.230.11 lb
Black Bullhead26.250.51 lb
Black Crappie15.690.16 lb
Pumpkinseed7.820.12 lb
Northern Pike6.832.34 lb
Brown Bullhead6.070.58 lb

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

627 fish · 27 in · 2025-06-16
3571790234567

Black Bullhead

13 fish · 714 in · 2025-06-16
4207891011121314

Black Crappie

53 fish · 411 in · 2025-06-16
22110trophy 104567891011

Pumpkinseed

107 fish · 37 in · 2025-06-16
6231034567

From the 2025-06-16 survey

Coon Lake is a 1,250 acre lake located in northern Anoka County and assigned to lake class 35. There are two major basins with the eastern one being the deeper but smaller of the two. This lake was historically susceptible to winterkills but there are currently two aeration systems in place which appear to be…

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 Coon Lake. 3 reports on file.

EPA Impairment Status

Coon Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Mercury

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit MN02-0042-00 · 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: 2024-10-19

Monitoring stations: 6