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C

Milwaukee Harbor Lake

Milwaukee County, WisconsinEutrophic

The LakeGrade rubric puts Milwaukee Harbor Lake at a C: clarity at 7.4 ft, phosphorus readings still being added, and a TSI of 55 signal an intermediate trophic state. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. 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. Within Milwaukee County's 14 graded lakes, Milwaukee Harbor Lake ranks 9 — below the local median, though not at the bottom.

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. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.

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

Swim with caution, moderate algae may be present

Water Quality Grade: C, Fair

Moderate clarity, visible to about 7.4 ft. Chlorophyll-a: 26 µg/L. Trophic State Index: 55.

MetricValueGrade
Water Clarity (Secchi Depth)7.4 ftC
PhosphorusNo data
Chlorophyll-a (Algae)26 µg/LD
Trophic State Index (TSI)55Eutrophic

High nutrients, frequent algae, reduced clarity

Water Quality Trend: Declining

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

MetricTrendChange/YearYears
Water Clarity Declining-0.149 m/yr6
Chlorophyll-a Declining+5.91 µg/L/yr6
See year-by-year chart →

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #9 of 14 lakes in Milwaukee County

Cleaner Lakes Within 30 Miles

Milwaukee Harbor Lake holds Grade C. 2 nearby lakes hold higher grades.

See full comparison →

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 (2.75 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: 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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