Milwaukee Harbor South Half Lake
Milwaukee County, WisconsinEutrophic
Milwaukee Harbor South Half Lake earns a D — measurements through 2025 show persistent nutrient pressure that limits clarity through the summer. Chlorophyll-a is the limiting factor: even when clarity looks acceptable, the algal community drives the grade down.
At a TSI of 56, Milwaukee Harbor South Half 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 South Half Lake ranks 11 of 14 in Milwaukee County — at the lower end of the locally monitored distribution.
Milwaukee Harbor South Half Lake has no invasive species recorded in Wisconsin state databases as of 2025, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Milwaukee Harbor South Half 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 South Half Lake water quality
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Moderate clarity, visible to about 7.2 ft. Chlorophyll-a: 31 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.2 ft | C |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 31 µg/L | F |
| Trophic State Index (TSI) | 56 | 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 | -0.134 m/yr | 6 |
| Chlorophyll-a | ↓ Declining | +6.84 µg/L/yr | 6 |
Location
County Ranking
Ranked #11 of 14 lakes in Milwaukee County
Cleaner Lakes Within 30 Miles
Milwaukee Harbor South Half Lake holds Grade D. 5 nearby lakes hold higher grades.
- CMilwaukee Harbor LakeMilwaukee County · mi · Higher grade (D → C)
- CMilwaukee Harbor LakeMilwaukee County · mi · Higher grade (D → C)
- CMilwaukee Harbor LakeMilwaukee County · mi · Higher grade (D → C)
- CMilwaukee Harbor LakeMilwaukee County · mi · Higher grade (D → C)
- CMilwaukee River LakeMilwaukee County · mi · Higher grade (D → C)
Nearby Lakes in Milwaukee County
More Wisconsin Lake Rankings
State Parks Near Milwaukee Harbor South Half Lake
Other Grade D Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
EPA Impairment Status
Milwaukee Harbor South Half 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 (1.51 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
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