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.
At a TSI of 52, Milwaukee Harbor Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. 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 4 of 14 in Milwaukee County — solidly in the upper half of the local distribution.
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.
Watch Milwaukee Harbor Lake water quality
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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.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.2 ft | C |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 14 µg/L | C |
| Trophic State Index (TSI) | 52 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.036 m/yr | 6 |
| Chlorophyll-a | ↓ Declining | +3.41 µg/L/yr | 6 |
Recreation & Access
Location
County Ranking
Ranked #4 of 14 lakes in Milwaukee County
Nearby Lakes in Milwaukee County
More Wisconsin Lake Rankings
State Parks Near Milwaukee Harbor Lake
Other Grade C Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit WI10008753 · Official waterbody report · Matched by proximity (2.58 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
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