Millstone Lake
Wright County, MinnesotaHypereutrophic
On the LakeGrade rubric Millstone Lake fails the cutoffs — a TSI of 80 and persistent algal pressure put it in the bottom tier. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.
The hypereutrophic status — TSI 80 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. Millstone Lake is a shallow lake at 9 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. At 200 acres, Millstone Lake fits the Minnesota median for monitored lakes, with 2.6 miles of shoreline. Millstone Lake ranks 59 of 64 in Wright County — at the lower end of the locally monitored distribution.
Millstone Lake has no invasive species recorded in Minnesota state databases as of 2022, though prevention practices still apply at all access points. 4 fish species are on record, with panfish making up the recreational core. A documented public access point at Millstone Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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, Minnesota DNR LakeFinder, last sampled 2022-10-12. Grade methodology: LakeGrade methodology.
Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 0.8 ft of visibility. Phosphorus level: 186 µg/L. Trophic State Index: 80.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.8 ft | F |
| Phosphorus | 186 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 80 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 8.5 ft |
| Average Depth | 4.2 ft |
| Surface Area | 199.63 acres |
| Shoreline Length | 2.6 mi |
| Littoral Zone | 100% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Millstone Lake (14-day solunar calendar)
→ Is it safe to eat fish from Millstone Lake? (mercury & PFAS guide)
→ Millstone Lake fishing regulations (limits, seasons, special rules)
Location
County Ranking
Ranked #59 of 64 lakes in Wright County
Nearby Lakes in Wright County
More Minnesota Lake Rankings
State Parks Near Millstone Lake
Other Grade F Lakes in Minnesota
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 2019-05-07 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 12.50 | — |
| Black Bullhead | 8.75 | — |
| Green Sunfish | 2.75 | — |
| Black Crappie | 0.25 | — |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
From the 2019-05-07 survey
Millstone Lake is located four miles north of Maple Lake in Wright County. It has a surface area of 202 acres and a maximum depth of eight to ten feet depending on water levels. The watershed is small (705 acres) mostly agricultural, and water quality is poor. Millstone Lake has not been considered to be a "fish lake"…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Millstone Lake. 3 reports on file.
- —Fisheries Lake Survey — MillstoneFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Millstone (2011)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — MillstonePublic Water Access Sites · MN DNR LakeFinder
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Lake details from Minnesota DNR LakeFinder
Most recent sample: 2022-10-12
Monitoring stations: 1