Halfmoon Lake
Halfmoon Lake in Oconto County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 17 ft visibility. Phosphorus: 11.8 µg/L. Maximum depth: 38 ft. Surface area: 28 acres.
Wisconsin DNR lists Panfish as common on Halfmoon Lake. DNR survey details →
- Clarity
- 17 ft
- Max depth
- 38 ft
- Area
- 28 acres
- Trend
- → Stable
- Public access
- Yes
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Why Halfmoon Lake 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 Halfmoon Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity and phosphorus, but not 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.
Halfmoon Lake is a 28-acre lake in Oconto County, Wisconsin with a maximum depth of 38 feet. Water clarity is improving over recent sampling years. The lake supports 2 documented fish species including Panfish and Largemouth Bass. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-07-04. 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 Halfmoon Lake
These readings exist but are not enough for an A–F grade — see why.
Crystal clear, you can see 17 ft down. Phosphorus level: 11.8 µg/L. Trophic State Index: 38.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 17 ft | Not graded |
| Phosphorus | 11.8 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 38 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Halfmoon Lake
Compare lakeside cabins, hotels, and vacation rentals near Halfmoon Lake in Oconto 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 Halfmoon Lake
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Wisconsin DNR lists Panfish as common on Halfmoon Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on Halfmoon Lake — official chemistry is on file, not a letter, and the water-quality trend over 7 years of monitoring is stable. 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 1987. 1 station on file (most recent sample 2026).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 38 ft |
| Surface Area | 28 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Halfmoon LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Halfmoon 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: → Stable
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.907 m/yr | 7 |
| Phosphorus | ↓ Declining | +3.82 µg/L/yr | 4 |
Graded lakes near Halfmoon Lake
Halfmoon Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Oconto County
Frequently asked questions about Halfmoon Lake
Where is Halfmoon Lake?
- Halfmoon Lake is a lake in Oconto 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 Halfmoon Lake?
- Halfmoon Lake in Oconto County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 17 ft visibility. Phosphorus: 11.8 µg/L. Maximum depth: 38 ft. Surface area: 28 acres.
Is Halfmoon Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Halfmoon Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
How deep is Halfmoon Lake?
- Halfmoon Lake has a maximum depth of 38 feet. The lake covers 28 acres.
What fish are in Halfmoon Lake?
- Fish species found in Halfmoon Lake include Panfish, Largemouth Bass. Halfmoon Lake is located in Oconto County, Wisconsin.
What did the DNR fisheries survey find at Halfmoon Lake?
- Wisconsin DNR lists Panfish as common on Halfmoon Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on Halfmoon Lake — official chemistry is on file, not a letter, and the water-quality trend over 7 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Halfmoon Lake?
- Halfmoon Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Halfmoon Lake. Public access is listed as yes.
Explore Halfmoon Lake across LakeQuality
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Where this data comes from
33 measurements from 1 monitoring station, 2021–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX33 samples · 2021–2026
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory