Grafton Millpond
Ozaukee County, WisconsinLimited DataHypereutrophic
On the LakeGrade rubric Grafton Millpond fails the cutoffs — a TSI of 72 and persistent algal pressure put it in the bottom tier. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.
The hypereutrophic status — TSI 72 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. 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 the 9 graded lakes of Ozaukee County, Grafton Millpond sits at rank 9, near the bottom of the county list.
Grafton Millpond has no invasive species recorded in Wisconsin state databases as of 2024, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Grafton Millpond, 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 2024-08-12. Grade methodology: LakeGrade methodology.
Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
No clarity data. Phosphorus level: 110 µg/L. Trophic State Index: 72.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 110 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Location
County Ranking
Ranked #9 of 9 lakes in Ozaukee County
Cleaner Lakes Within 30 Miles
Grafton Millpond holds Grade F. 3 nearby lakes hold higher grades.
- AGreen LakeWashington County · 12.3 mi · Two grade letters higher (F → A)
- BWatts LakeOzaukee County · 6.2 mi · Two grade letters higher (F → B)
- BSandhill LakeOzaukee County · 8.7 mi · Two grade letters higher (F → B)
Nearby Lakes in Ozaukee County
More Wisconsin Lake Rankings
State Parks Near Grafton Millpond
Other Grade F Lakes in Wisconsin
Hypereutrophic Lakes in Wisconsin
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Fish and recreation data from Wisconsin DNR Lakes
Most recent sample: 2024-08-12
Monitoring stations: 1