Millstone Lake
Millstone Lake in Wright County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 0.8 ft visibility. Phosphorus: 186 µg/L. Chlorophyll-a (algae): 62.8 µg/L. Maximum depth: 8.5 ft. Surface area: 199.63 acres.
- Clarity
- 0.8 ft
- Typical in August
- 68°F
- Max depth
- 8.5 ft
- Area
- 200 acres
- Type
- Hypereutrophic
- Public access
- Yes
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Millstone Lake →
Next lake in Wright County
Millstone Lake is a 200-acre highly nutrient-loaded hypereutrophic lake in Wright County, Minnesota with a maximum depth of 9 feet (4-foot average). Water quality is graded F based on 2 sampling years through 2022. The lake supports 4 documented fish species including black bullhead, black crappie, and bluegill. Public access is available. Compared to the 50 other monitored lakes in Wright County, Millstone Lake ranks #45 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-10-12. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom
Water Quality Grade: F (Algae-prone)
Very murky, less than 0.8 ft of visibility. Phosphorus level: 186 µg/L. Chlorophyll-a: 62.8 µg/L. Trophic State Index: 77.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.8 ft | Not graded |
| Phosphorus | 186 µg/L | Poor |
| Chlorophyll-a (Algae) | 62.8 µg/L | Poor |
| Trophic State Index (TSI) | 77 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Millstone Lake
Compare lakeside cabins, hotels, and vacation rentals near Millstone Lake in Wright County, Minnesota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Millstone Lake are listed below.
Top-rated places to stay near Millstone Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Millstone Lake typically sits around 68°F at the surface in August. Summer average is about 72°F. Usually warmest in Jun (about 75°F) and coldest in Sep (about 62°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 62 field readings (2022–2022) via the EPA Water Quality Portal. See the full Millstone Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 8.5 ft |
| Average Depth | 4.2 ft |
| Surface Area | 200 acres |
| Shoreline Length | 2.6 mi |
| Littoral Zone | 100% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Millstone Lake
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.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —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
EPA Impairment Status
Millstone 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 MN86-0152-00 · Official waterbody report
County Ranking
Ranked #45 of 51 lakes in Wright County
Nearby Lakes With Higher Grades
Millstone Lake holds Grade F. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Wright County
Frequently asked questions about Millstone Lake
What is the water quality grade for Millstone Lake?
- Millstone Lake in Wright County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 0.8 ft visibility. Phosphorus: 186 µg/L. Chlorophyll-a (algae): 62.8 µg/L. Maximum depth: 8.5 ft. Surface area: 199.63 acres.
Is Millstone Lake safe to swim in?
- Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Millstone Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 62.8 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Millstone Lake?
- Millstone Lake typically sits around 68°F at the surface in August, from 62 EPA Water Quality Portal field readings (2022–2022). That is a typical value for the month, not a live reading.
How deep is Millstone Lake?
- Millstone Lake has a maximum depth of 8.5 feet and an average depth of 4.2 feet. The lake covers 199.63 acres.
What fish are in Millstone Lake?
- Fish species found in Millstone Lake include black bullhead, black crappie, bluegill, green sunfish. Millstone Lake is located in Wright County, Minnesota.
Explore Millstone Lake across LakeGrade
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Where this data comes from
40 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA40 samples · 2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder