What is the water quality grade for Raccoon Lake?

Raccoon Lake in Marion County, Wisconsin received a water quality grade of F (Very Poor). Water clarity: 1.2 ft visibility. Phosphorus: 202.5 µg/L. Surface area: 730 acres.

Is Raccoon Lake safe to swim in?

Avoid swimming, very poor water quality, potential algae toxins. Raccoon Lake has an overall water quality grade of F. Always check local health department advisories before swimming.

Raccoon Lake

Marion County, WisconsinHypereutrophic

Raccoon Lake is a 730-acre highly nutrient-loaded hypereutrophic lake in Marion County, IL. Water quality is graded F based on 2 sampling years through 2021. Compared to the 5 other monitored lakes in Marion County, Raccoon Lake ranks #5 for water quality.

Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2021-11-09. Grade methodology: LakeGrade methodology.

Swimming Safety

Avoid swimming, very poor water quality, potential algae toxins

Water Quality Grade: F, Very Poor

Very murky, less than 1.2 ft of visibility. Phosphorus level: 202.5 µg/L. Trophic State Index: 78.

Metric	Value	Grade
Water Clarity (Secchi Depth)	1.2 ft	F
Phosphorus	202.5 µg/L	F
Chlorophyll-a (Algae)	No data
Trophic State Index (TSI)	78	Hypereutrophic

Very high nutrients, dense algae, poor clarity

Lake Details

Characteristic	Value
Surface Area	730 acres

Location

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County Ranking

Ranked #5 of 6 lakes in Marion County

Cleaner Lakes Within 30 Miles

Raccoon Lake holds Grade F. 3 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Marion County

More Wisconsin Lake Rankings

Cleanest lakes in Wisconsin

Top 25 by overall water quality score

Best swimming lakes in Wisconsin

Grade A/B + low algae filter

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Panfish-rich, public access

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Full state directory

Other Grade F Lakes in Wisconsin

Lake Charlemagne

Cook County · Clarity: 2 ft

Bode Lake North

Cook County · Clarity: 1.5 ft

Great Lakes Quarries West

Cook County · Clarity: 2.5 ft

Bull Frog Lake

Cook County · Clarity: 3 ft

Belly Deep Slough Lake

Cook County · Clarity: 0.7 ft

Sauk Lake

Cook County · Clarity: 1 ft

Hypereutrophic Lakes in Wisconsin

Bode Lake North Belly Deep Slough Lake Sauk Lake Washington Park Lagoon Lake

Reservoir Info (USACE NID)

Raccoon Lake is a man-made reservoir impounded by the Raccoon Lake Dam (completed 1943), built primarily for water supply on the RACCON CREEK; earth-type dam, 29 ft tall and 1,480 ft long.

Surface area: 730 ac
Normal storage: 4,709 ac-ft
Max storage: 6,700 ac-ft
Drainage area: 48.5 sq mi
Hazard class: High
Owner: CITY OF CENTRALIA

Source: USACE National Inventory of Dams, NID ID IL00242 · Operator website

EPA Impairment Status

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

Causes of impairment

MercuryNutrients (phosphorus, nitrogen)PesticidesPCBs

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

Source: EPA ATTAINS assessment unit IL_ROK · 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

Most recent sample: 2021-11-09

Monitoring stations: 3