Marion-Halfmoon Lake
Marion County, FloridaView mapDirections
Florida DEP publishes the water-quality measurements for Marion-Halfmoon Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
- 42 ft max depth
- Public access
Marion-Halfmoon Lake in Marion County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 4.5 ft visibility. Phosphorus: 14 µg/L.
Marion-Halfmoon Lake is a mesotrophic lake in Marion County, Florida with an estimated average depth of about 42 feet. 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. Methodology: how these readings are compared.
What Marion-Halfmoon Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyLow algae
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. Marion-Halfmoon Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, oxygen depletion (low DO). Check local advisories before you swim.
Whether Marion-Halfmoon Lake is safe to swim in today is a call for the Florida Department of Environmental Protection and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Marion-Halfmoon Lake
These are the measurements Florida DEP publishes for Marion-Halfmoon Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4.5 ft. Phosphorus 14 µg/L. TSI 49.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 14µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 49 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Marion-Halfmoon Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~42 ft est.
Public access
Yes
Listed by Florida DEP
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
Watershed (drainage) area
19 sq mi
HydroLAKES / HydroSHEDS
Surface area
306 acres
HydroLAKES / HydroSHEDS
Shoreline
3.5 mi
HydroLAKES / HydroSHEDS
Elevation
43 ft
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
Stays via Stay22
Stays 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
Prices for Oct 16–18, 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 trip? Cabins and lodging at Marion-Halfmoon Lake → · more Florida lake trips
Follow Marion-Halfmoon Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Marion-Halfmoon Lake
Water Quality Trend: Improving
Based on 5 years of monitoring (2020–2024).
Water clarity
Improving5 years
Phosphorus
Improving-1.45 µg/L/yr5 years
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
Designated uses not supporting: Aquatic life, Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit FL2781A · Official waterbody report
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. Its water-quality measurements are published by Florida DEP and shown on this page as reported.
What is the water quality of Marion-Halfmoon Lake?
- Marion-Halfmoon Lake in Marion County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 4.5 ft visibility. Phosphorus: 14 µg/L.
Is Marion-Halfmoon Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Marion-Halfmoon Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, oxygen depletion (low DO). Check local advisories before you swim.
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.
Can I fish at Marion-Halfmoon Lake?
- Marion-Halfmoon 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 Florida's fish and wildlife agency, so check its current regulations before you go.
Explore Marion-Halfmoon Lake across LakeQuality
More lakes in Florida
Other 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)
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)
Named boat-access points from the USGS National Boat Ramps inventory