Marion-Mill Dam Lake
Marion-Mill Dam Lake in Marion County, Florida has a water quality grade of B (Good). Water clarity: 11 ft visibility. Phosphorus: 9 µg/L.
- Clarity
- 11 ft
- Max depth
- ~31 ft est.
- Type
- Oligotrophic
- Public access
- Yes
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Marion-Mill Dam Lake is a cold, clear oligotrophic lake in Marion County, Florida with an estimated average depth of about 31 feet. Water quality is graded B based on 1 sampling years through 2020. 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-Mill Dam Lake ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2020-06-16. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyLimited data
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 11 ft. Phosphorus level: 9 µg/L. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11 ft | Not graded |
| Phosphorus | 9 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Marion-Mill Dam Lake
Compare lakeside cabins, hotels, and vacation rentals near Marion-Mill Dam 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-Mill Dam Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~31 ft est. |
| Average Depth | ~11 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-Mill Dam 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
- Mill Dam Recreation AreaPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Marion-Mill Dam Lake
EPA Impairment Status
Marion-Mill Dam Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit FL2779A · Official waterbody report · Matched by proximity (0.56 km)
County Ranking
Ranked #9 of 18 lakes in Marion County
Nearby Lakes in Marion County
Frequently asked questions about Marion-Mill Dam Lake
Where is Marion-Mill Dam Lake?
- Marion-Mill Dam 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-Mill Dam Lake?
- Marion-Mill Dam Lake in Marion County, Florida has a water quality grade of B (Good). Water clarity: 11 ft visibility. Phosphorus: 9 µg/L.
Is Marion-Mill Dam Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Marion-Mill Dam Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Marion-Mill Dam Lake?
- No published bathymetric survey covers Marion-Mill Dam Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 31 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-Mill Dam Lake?
- Marion-Mill Dam Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Mill Dam Recreation Area. Public access is listed as yes.
Explore Marion-Mill Dam Lake across LakeQuality
More Florida Lake Rankings
Other Grade B Lakes in Florida
Oligotrophic Lakes in Florida
Where this data comes from
12 measurements from 3 monitoring stations, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- FLORIDA LAKEWATCH
21FLKWAT_WQX12 samples · 2020
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