Grafton Millpond
Grafton Millpond in Ozaukee County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 110 µg/L. Surface area: 35 acres.
- Area
- 35 acres
- Public access
- Yes
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Why Grafton Millpond has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Grafton Millpond, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded phosphorus, but not water clarity and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by WI DNR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Grafton Millpond is a 35-acre lake in Ozaukee County, Wisconsin. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2024-08-12. Grade methodology: LakeQuality methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Grafton Millpond
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Phosphorus level: 110 µg/L. Trophic State Index: 72.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 110 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Grafton Millpond
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 35 acres |
| Public Access | Yes |
No bathymetric survey has been published for Grafton Millpond, so its depth is not documented here.
Recreation & Access
- GraftonPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Grafton Millpond
Reservoir Info (USACE NID)
Grafton Millpond is a man-made reservoir impounded by the Grafton (completed 1918), built primarily for recreation on the MILWAUKEE; buttress-type dam, 20 ft tall and 206 ft long.
- Surface area
- 35 ac
- Normal storage
- 260 ac-ft
- Max storage
- 400 ac-ft
- Drainage area
- 451 sq mi
- Hazard class
- Significant
- Owner
- Village Of Grafton
Source: USACE National Inventory of Dams, NID ID WI00171 · Operator website · Matched by proximity (0.23 km)
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Grafton Millpond under Clean Water Act (NPDES) discharge permits, including 2 classified by the EPA as major dischargers. 2 facilities have a reported Clean Water Act violation in the past three years.
- Grafton Village Water & Wastewater UtilityGrafton · 1.4 mi away · NPDES WI0020184MajorRecent violation
- Cedarburg City WwtfCedarburg · 2.6 mi away · NPDES WI0020222MajorRecent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Graded lakes near Grafton Millpond
Grafton Millpond has no grade, but these lakes within a short drive do.
Nearby Lakes in Ozaukee County
Frequently asked questions about Grafton Millpond
Where is Grafton Millpond?
- Grafton Millpond is a lake in Ozaukee County, Wisconsin. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for Grafton Millpond?
- Grafton Millpond in Ozaukee County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 110 µg/L. Surface area: 35 acres.
Is Grafton Millpond safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Grafton Millpond is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Are there boat ramps on Grafton Millpond?
- Grafton Millpond has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Grafton. Public access is listed as yes.
Explore Grafton Millpond across LakeQuality
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Where this data comes from
1 measurement from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX1 sample · 2024
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory