Moon Lake
Douglas County, Minnesota139 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Moon Lake. Here is what has been measured.
- Oligotrophic
- Impaired · Mercury
- zebra mussel
- 38 ft max depth
- Public access
- Limited data
Moon Lake in Douglas County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 21 ft visibility. Phosphorus: 11 µg/L. Chlorophyll-a (algae): 1.8 µg/L. Maximum depth: 38 ft. Surface area: 139.09 acres.
Minnesota DNR's Standard Survey on June 26, 2023 caught 0.67 walleye per gill net at Moon Lake. DNR survey details →
Moon Lake is a 139-acre cold, clear oligotrophic lake in Douglas County, Minnesota with a maximum depth of 38 feet (19-foot average). Overall water quality is improving over recent sampling years. The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 36 other monitored lakes in Douglas County, Moon Lake ranks #16 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-08-30. Methodology: how these readings are compared.
Moon Lake covers about 140 acres in Douglas County. It has one public boat landing. Vrbo is where to look for cabins and lake homes around Moon Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Moon Lake is good for
From access and monitoring records, not editorial picks.
- Clear water21 ft of visibility
- Boat launch1 documented ramp
- Fishing12 species recorded
- Deep water38 ft surveyed max depth
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Moon Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Moon Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Moon Lake
These are the measurements Minnesota PCA publishes for Moon Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 21 ft down. Phosphorus 11 µg/L. Chlorophyll-a 1.8 µg/L. TSI 36.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 21ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 11µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 1.8µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 36 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Moon Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Moon Lake typically sits around 65°F at the surface in September. Summer average is about 71°F. Usually warmest in Jul (about 73°F) and coldest in Apr (about 48°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (48°F) to its warmest (73°F).
Typical surface water temperature by month, from 126 field readings (2019–2025) via the EPA Water Quality Portal. See the full Moon Lake water temperature breakdown →
Minnesota DNR's Standard Survey on June 26, 2023 caught 0.67 walleye per gill net at Moon Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Moon Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2023-06-26 (Standard Survey).
10 surveys on file · most recent 2023-06-26 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Largemouth Bass | 36.44 | 5–17 in 2023-06-26 | 0.83 lb |
| Bluntnose Minnow | 19.88 | ||
| Bluegill | 16.83 | 3–10 in 2023-06-26 | 0.22 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Largemouth Bass
Bluegill
From the 2023-06-26 survey
Moon Lake is a 126-acre natural lake located just southeast of Brandon in western Douglas County. Maximum depth is 38.0 feet. Average depth is estimated at 19.0 feet due to steep banks and a rapid drop off along much of the north, west, and south shorelines. Water quality is very good. Summer water clarity…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Moon Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — MoonFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Moon (0921)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — MoonFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — MoonPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
38 ft
Average depth
19 ft
Surface area
139 acres
Shoreline
2.7 mi
Littoral zone
32%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,368 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Moon LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Moon Lake
Compare lakeside cabins, hotels, and vacation rentals near Moon Lake in Douglas 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.
Top-rated places to stay near Moon Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Follow Moon Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fish Species
Click a species to see every lake where it is documented.
Fishing Moon Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Improving6 years
EPA Impairment Status
Moon Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN21-0226-00 · Official waterbody report
Nearby Lakes in Douglas County
Frequently asked questions about Moon Lake
Where is Moon Lake?
- Moon Lake is a lake in Douglas County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Moon Lake?
- Moon Lake in Douglas County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 21 ft visibility. Phosphorus: 11 µg/L. Chlorophyll-a (algae): 1.8 µg/L. Maximum depth: 38 ft. Surface area: 139.09 acres.
Is Moon Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Moon Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Moon Lake?
- Moon Lake typically sits around 65°F at the surface in September, from 126 EPA Water Quality Portal field readings (2019–2025). That is a typical value for the month, not a live reading.
How deep is Moon Lake?
- Moon Lake has a maximum depth of 38 feet and an average depth of 19 feet. The lake covers 139.09 acres.
What fish are in Moon Lake?
- Fish species found in Moon Lake include black bullhead, black crappie, bluegill, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white crappie, white sucker, yellow perch. Moon Lake is located in Douglas County, Minnesota.
What did the DNR fisheries survey find at Moon Lake?
- Minnesota DNR's Standard Survey on June 26, 2023 caught 0.67 walleye per gill net at Moon Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Moon Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Moon Lake?
- Moon Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Moon Lake. Public access is listed as yes.
Can I fish at Moon Lake?
- Moon Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Moon Lake across LakeQuality
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Douglas County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Alexandria Lakes area
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the St. Croix Watershed, ranked by water quality
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
Lakes in the Sauk River Watershed, ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
More lakes in Minnesota
State Parks Near Moon Lake
Other Lakes in Minnesota
Oligotrophic Lakes in Minnesota
Where this data comes from
120 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA120 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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
Named boat-access points from the USGS National Boat Ramps inventory