Moon Lake
Moon Lake in Vilas County, Wisconsin has a water quality grade of B (Good). Water clarity: 13 ft visibility. Phosphorus: 14.1 µg/L. Maximum depth: 38 ft. Surface area: 131 acres.
Wisconsin DNR lists Panfish as common on Moon Lake. DNR survey details →
- Clarity
- 13 ft
- Typical in August
- 69°F
- Max depth
- 38 ft
- Area
- 131 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
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Moon Lake is a 131-acre mesotrophic lake in Vilas County, Wisconsin with a maximum depth of 38 feet. Water quality is graded B based on 1 sampling years through 2026. Overall water quality is improving over recent sampling years. The lake supports 6 documented fish species including Musky, Panfish, and Largemouth Bass. Compared to the 102 other monitored lakes in Vilas County, Moon Lake ranks #49 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-22. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyLow algae
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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Good clarity, visible to about 13 ft. Phosphorus level: 14.1 µg/L. Trophic State Index: 41.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13 ft | Not graded |
| Phosphorus | 14.1 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Moon Lake
Compare lakeside cabins, hotels, and vacation rentals near Moon Lake in Vilas County, Wisconsin — 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
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Water Temperature
Moon Lake typically sits around 69°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 78°F) and coldest in Aug (about 69°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 9 field readings (2024–2025) via the EPA Water Quality Portal. See the full Moon Lake water temperature breakdown →
Wisconsin DNR lists Panfish as common on Moon Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Moon Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1986. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 38 ft |
| Surface Area | 131 acres |
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 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 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.521 m/yr | 6 |
| Phosphorus | ↑ Improving | -1.84 µg/L/yr | 7 |
EPA Impairment Status
Moon Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit WI8128746 · Official waterbody report · Matched by proximity (1.1 km)
County Ranking
Ranked #49 of 103 lakes in Vilas County
Nearby Lakes in Vilas County
Frequently asked questions about Moon Lake
Where is Moon Lake?
- Moon Lake is a lake in Vilas County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Moon Lake?
- Moon Lake in Vilas County, Wisconsin has a water quality grade of B (Good). Water clarity: 13 ft visibility. Phosphorus: 14.1 µg/L. Maximum depth: 38 ft. Surface area: 131 acres.
Is Moon Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Moon Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Moon Lake?
- Moon Lake typically sits around 69°F at the surface in August, from 9 EPA Water Quality Portal field readings (2024–2025). 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. The lake covers 131 acres.
What fish are in Moon Lake?
- Fish species found in Moon Lake include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye. Moon Lake is located in Vilas County, Wisconsin.
What did the DNR fisheries survey find at Moon Lake?
- Wisconsin DNR lists Panfish as common on Moon Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Moon Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Explore Moon Lake across LakeQuality
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Fish species and best lakes in Vilas County
Species activity outlook by water temperature and season
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Where to stay at Wisconsin's top lakes, each with its grade
Lakes in the Wisconsin River Watershed, ranked by water quality
Moderate nutrients, good water quality
Wisconsin's cleanest and most-polluted lakes, ranked
More Wisconsin Lake Rankings
Other Grade B Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
Where this data comes from
44 measurements from 1 monitoring station, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX44 samples · 2020–2026
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes