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C

Milwaukee Harbor Lake

Milwaukee County, WisconsinEutrophic

Milwaukee Harbor Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

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. 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. Milwaukee Harbor Lake ranks 2 of 14 in Milwaukee County, putting it in the upper tier of locally monitored lakes.

No invasive species are currently listed at Milwaukee Harbor Lake — the lake remains off the Wisconsin infested-waters roster. The state fisheries records do not list documented species for Milwaukee Harbor 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 2025-11-05. Grade methodology: LakeGrade methodology.

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Swimming Safety

Generally safe for swimming, moderate water quality

Water Quality Grade: C, Fair

Moderate clarity, visible to about 8.2 ft. Chlorophyll-a: 14 µg/L. Trophic State Index: 52.

MetricValueGrade
Water Clarity (Secchi Depth)8.2 ftC
PhosphorusNo data
Chlorophyll-a (Algae)14 µg/LC
Trophic State Index (TSI)52Eutrophic

High nutrients, frequent algae, reduced clarity

Water Quality Trend: Declining

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

MetricTrendChange/YearYears
Water Clarity Declining-0.14 m/yr6
Chlorophyll-a Declining+6.87 µg/L/yr6
See year-by-year chart →

Location

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County Ranking

Ranked #2 of 14 lakes in Milwaukee County

Nearby Lakes in Milwaukee County

State Parks Near Milwaukee Harbor Lake

EPA Impairment Status

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

Causes of impairment

Metals (other than mercury)Pathogens (E. coli, fecal)PCBs

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

Source: EPA ATTAINS assessment unit WI10008753 · Official waterbody report · Matched by proximity (1.34 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

Most recent sample: 2025-11-05

Monitoring stations: 1

Where to stay near Milwaukee Harbor Lake

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

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