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B

Big Cedar Lake

Washington County, WisconsinMesotrophic

Big Cedar Lake comes in at a B on the grading rubric — a respectable showing for a Wisconsin lake of its size and depth. The lake's weakest score is on Secchi depth — the water looks more turbid than its phosphorus number alone would predict.

A TSI near 44 places Big Cedar Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. Big Cedar Lake is unusually deep for Wisconsin at 105 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. The lake's 937 acres and partial shoreline records put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Big Cedar Lake sits at rank 9 of 15 in Washington County, in the lower half of the local distribution.

Big Cedar Lake is on the Wisconsin infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. The fishery includes walleye alongside the lake's other 4 documented species — a notable draw for Wisconsin anglers. Public access is available — the lake is on the Wisconsin DNR public-access list. 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 2026-04-20. Grade methodology: LakeGrade methodology.

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Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Moderate clarity, visible to about 9.8 ft. Phosphorus level: 15.5 µg/L. Trophic State Index: 44.

MetricValueGrade
Water Clarity (Secchi Depth)9.8 ftC
Phosphorus15.5 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)44Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth105 ft
Surface Area937 acres
Public AccessYes

Fish Species

Click a species to see every graded lake where it is documented.

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

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

Big Cedar 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.

Banded Mystery SnailChinese Mystery SnailCurly-Leaf PondweedEurasian Water-MilfoilZebra MusselStarry Stonewort

Water Quality Trend: Improving

Based on 6 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.379 m/yr6
Phosphorus Improving-1.06 µg/L/yr6
See year-by-year chart →

Recreation & Access

4
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #9 of 15 lakes in Washington County

Cleaner Lakes Within 30 Miles

Big Cedar Lake holds Grade B. 4 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Washington County

Mesotrophic Lakes in Wisconsin

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. 3 stations on file (most recent sample 2025).

DNR Assessment
Reported
Trophic State Index 43 (mesotrophic) · 5-year average

Fish Species (DNR-rated)

Largemouth Bass(Abundant)Panfish(Common)Northern Pike(Common)Walleye(Present)

EPA Impairment Status

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

Causes of impairment

Cause unknown

Source: EPA ATTAINS assessment unit WI10008013 · Official waterbody report · Matched by proximity (2.78 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

Fish and recreation data from Wisconsin DNR Lakes

Public boat-access points from the USGS National Boat Ramps inventory

Most recent sample: 2026-04-20

Monitoring stations: 1

Where to stay near Big Cedar Lake

Compare lakeside cabins, hotels, and vacation rentals near Big Cedar Lake in Washington County, Wisconsin — live availability and prices for your trip.

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