Marion-Mill Dam Lake
Marion County, FloridaView mapDirections
Florida DEP publishes the water-quality measurements for Marion-Mill Dam Lake. Here is what has been measured.
- Oligotrophic
- Impaired · Mercury
- 31 ft max depth
- Public access
- Limited data
Marion-Mill Dam Lake in Marion County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 11 ft visibility. Phosphorus: 9 µg/L.
Marion-Mill Dam Lake is a cold, clear oligotrophic lake in Marion County, Florida with an estimated average depth of about 31 feet. 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. Methodology: how these readings are compared.
What Marion-Mill Dam Lake is good for
From access and monitoring records, not editorial picks.
- Clear water11 ft of visibility
- Boat launch1 documented ramp
- Camping1 public campground nearby
Swimming conditions
Readings onlyLimited data
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-Mill Dam Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Marion-Mill Dam 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-Mill Dam Lake
These are the measurements Florida DEP publishes for Marion-Mill Dam Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 11 ft. Phosphorus 9 µg/L. TSI 39.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 11ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 9µg/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. | 39 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Marion-Mill Dam Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~31 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-Mill Dam Lake.
Lake Size & Watershed
Watershed (drainage) area
28 sq mi
HydroLAKES / HydroSHEDS
Surface area
163 acres
HydroLAKES / HydroSHEDS
Shoreline
1.8 mi
HydroLAKES / HydroSHEDS
Elevation
46 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
- Mill Dam Recreation AreaPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Marion-Mill Dam Lake
- Mill Dam Group Camp0.7 kmReserve
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Stays via Stay22
Stays near Marion-Mill Dam Lake
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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
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit FL2779A · Official waterbody report
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. Its water-quality measurements are published by Florida DEP and shown on this page as reported.
What is the water quality of Marion-Mill Dam Lake?
- Marion-Mill Dam Lake in Marion County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 11 ft visibility. Phosphorus: 9 µg/L.
Is Marion-Mill Dam Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Marion-Mill Dam Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
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.
Can I fish at Marion-Mill Dam Lake?
- Marion-Mill Dam 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.
Are there campgrounds on Marion-Mill Dam Lake?
- Marion-Mill Dam Lake has 1 public campground from USGS The National Map within 5 km, including Mill Dam Group Camp. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
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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)
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
Public campgrounds from USGS The National Map Structures, within about 3 miles