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LakeQuality
A

Cedar Lake

Manitowoc County, WisconsinOligotrophic

Cedar Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Manitowoc County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Cedar Lake ranks 2 of 18 in Manitowoc County, putting it in the upper tier of locally monitored lakes.

No invasive species are currently listed at Cedar Lake — the lake remains off the Wisconsin infested-waters roster. The state fisheries records do not list documented species for Cedar Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. 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 2025-08-11. Grade methodology: LakeGrade methodology.

Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

Crystal clear, you can see 34.5 ft down. Phosphorus level: 17.3 µg/L. Trophic State Index: 36.

MetricValueGrade
Water Clarity (Secchi Depth)34.5 ftA
Phosphorus17.3 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)36Oligotrophic

Low nutrients, clear water, excellent for swimming

Water Quality Trend: Stable

Based on 7 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.243 m/yr7
Phosphorus Improving-1.15 µg/L/yr6

Location

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County Ranking

Ranked #2 of 18 lakes in Manitowoc County

Nearby Lakes in Manitowoc County

DNR Reports & Resources

Wisconsin DNR Fisheries scientists publish multi-year survey reports for Cedar Lake covering fish populations, stocking, water quality, and management. 2 reports on file.

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2025-08-11

Monitoring stations: 2