Marion-Halfmoon Lake
Marion-Halfmoon Lake in Marion County, Florida has a water quality grade of B (Good). Water clarity: 4.5 ft visibility. Phosphorus: 14 µg/L.
- Clarity
- 4.5 ft
- Max depth
- ~42 ft est.
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
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Marion-Halfmoon Lake is a mesotrophic lake in Marion County, Florida with an estimated average depth of about 42 feet. Water quality is graded B based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 17 other monitored lakes in Marion County, Marion-Halfmoon Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-03-27. 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)
Murky, only visible to about 4.5 ft. Phosphorus level: 14 µg/L. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.5 ft | Not graded |
| Phosphorus | 14 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Marion-Halfmoon Lake
Compare lakeside cabins, hotels, and vacation rentals near Marion-Halfmoon Lake in Marion County, Florida — 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 Marion-Halfmoon Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~42 ft est. |
| Average Depth | ~7 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Florida has not published bathymetry for Marion-Halfmoon Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Halfmoon Lake - Ocala National ForestPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Marion-Halfmoon Lake
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.46 m/yr | 5 |
| Phosphorus | ↑ Improving | -1.45 µg/L/yr | 5 |
EPA Impairment Status
Marion-Halfmoon Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit FL2781A · Official waterbody report · Matched by proximity (0.06 km)
County Ranking
Ranked #4 of 18 lakes in Marion County
Nearby Lakes in Marion County
Frequently asked questions about Marion-Halfmoon Lake
Where is Marion-Halfmoon Lake?
- Marion-Halfmoon Lake is a lake in Marion County, Florida. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Marion-Halfmoon Lake?
- Marion-Halfmoon Lake in Marion County, Florida has a water quality grade of B (Good). Water clarity: 4.5 ft visibility. Phosphorus: 14 µg/L.
Is Marion-Halfmoon Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Marion-Halfmoon Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Marion-Halfmoon Lake?
- No published bathymetric survey covers Marion-Halfmoon Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 42 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Marion-Halfmoon Lake?
- Marion-Halfmoon Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Halfmoon Lake - Ocala National Forest. Public access is listed as yes.
Explore Marion-Halfmoon Lake across LakeQuality
More Florida Lake Rankings
Other Grade B Lakes in Florida
Mesotrophic Lakes in Florida
Where this data comes from
211 measurements from 3 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- FLORIDA LAKEWATCH
21FLKWAT_WQX211 samples · 2020–2025
Monitoring station identifiers (3)
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)
Named boat-access points from the USGS National Boat Ramps inventory