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.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.4 ft | C |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 26 µg/L | D |
| Trophic State Index (TSI) | 55 | 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 | ↓ Declining | -0.149 m/yr | 6 |
| Chlorophyll-a | ↓ Declining | +5.91 µg/L/yr | 6 |
Recreation & Access
Location
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.
- CMilwaukee Harbor LakeMilwaukee County · mi · Higher overall water quality score
- CMilwaukee Harbor LakeMilwaukee County · mi · Higher overall water quality score
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 (2.75 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
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