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D

Eau Claire Lake

Eau Claire County, WisconsinEutrophic

Eau Claire Lake pulls a D on the LakeGrade rubric — phosphorus loading and limited clarity hold it below the Wisconsin average. clarity and phosphorus rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. Eau Claire Lake reaches 25 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 870 acres, Eau Claire Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Within Eau Claire County's 3 graded lakes, Eau Claire Lake ranks 2 — below the local median, though not at the bottom.

An invasive species record — Chinese Mystery Snail — has been logged at Eau Claire Lake; Wisconsin DNR maintains the official infested-waters list. The fishery includes walleye among the lake's 5 documented species — a notable draw for Wisconsin anglers. 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, Wisconsin DNR Surface Water, last sampled 2024-10-07. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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Swimming Safety

Swimming not recommended, poor water quality with high algae risk

Water Quality Grade: D, Poor

Very murky, less than 2.8 ft of visibility. Phosphorus level: 88 µg/L. Trophic State Index: 66.

MetricValueGrade
Water Clarity (Secchi Depth)2.8 ftF
Phosphorus88 µg/LD
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)66Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

CharacteristicValue
Maximum Depth25 ft
Surface Area870 acres

Fish Species

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

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

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

Eau Claire 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.

Chinese Mystery SnailCurly-Leaf Pondweed

Water Quality Trend: Stable

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

MetricTrendChange/YearYears
Water Clarity Declining-0.25 m/yr3
Phosphorus Improving-3.09 µg/L/yr4
See year-by-year chart →

Location

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County Ranking

Ranked #2 of 3 lakes in Eau Claire County

Cleaner Lakes Within 30 Miles

Eau Claire Lake holds Grade D. One nearby lake has a higher grade.

See full comparison →

Nearby Lakes in Eau Claire County

State Parks Near Eau Claire Lake

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. 12 stations on file (most recent sample 2024).

DNR Assessment
Fair · Reservoir lake
Trophic State Index 62 (eutrophic) · 5-year average

Fish Species (DNR-rated)

Walleye(Abundant)Musky(Common)Largemouth Bass(Common)Smallmouth Bass(Common)Panfish(Present)

EPA Impairment Status

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

Causes of impairment

Nutrients (phosphorus, nitrogen)

Source: EPA ATTAINS assessment unit WI10004681 · 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: 2024-10-07

Monitoring stations: 2