Seminole-Mary Lake
Seminole County, FloridaView mapDirections
Florida DEP publishes the water-quality measurements for Seminole-Mary Lake. Here is what has been measured.
- Mesotrophic
- 37 ft max depth
Seminole-Mary Lake in Seminole County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 5.5 ft visibility. Phosphorus: 17 µg/L.
Seminole-Mary Lake is a mesotrophic lake in Seminole County, Florida with an estimated average depth of about 37 feet. Overall water quality is declining over recent sampling years. Compared to the 121 other monitored lakes in Seminole County, Seminole-Mary Lake ranks #37 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-02-28. Methodology: how these readings are compared.
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. Check local advisories before you swim.
Whether Seminole-Mary 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 Seminole-Mary Lake
These are the measurements Florida DEP publishes for Seminole-Mary 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 5.5 ft. Phosphorus 17 µg/L. TSI 49.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 17µg/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
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Lake Details
Max depth
~37 ft est.
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Florida has not published bathymetry for Seminole-Mary Lake.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Surface area
77 acres
HydroLAKES / HydroSHEDS
Shoreline
2.6 mi
HydroLAKES / HydroSHEDS
Elevation
49 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.
Stays via Stay22
Stays near Seminole-Mary Lake
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Top-rated places to stay near Seminole-Mary Lake
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Fishing Seminole-Mary Lake
Water Quality Trend: Worsening
Based on 5 years of monitoring (2020–2024).
Water clarity
Worsening5 years
Phosphorus
Worsening+0.9 µg/L/yr5 years
Nearby Lakes in Seminole County
Frequently asked questions about Seminole-Mary Lake
Where is Seminole-Mary Lake?
- Seminole-Mary Lake is a lake in Seminole County, Florida. Its water-quality measurements are published by Florida DEP and shown on this page as reported.
What is the water quality of Seminole-Mary Lake?
- Seminole-Mary Lake in Seminole County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 5.5 ft visibility. Phosphorus: 17 µg/L.
Is Seminole-Mary Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Seminole-Mary Lake?
- No published bathymetric survey covers Seminole-Mary Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 37 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Seminole-Mary Lake across LakeQuality
Planning a trip around Canaveral?
Seminole-Mary Lake is about 34 miles from Canaveral National Seashore. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Canaveral →More lakes in Florida
Other Lakes in Florida
Mesotrophic Lakes in Florida
Where this data comes from
197 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_WQX197 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
Lake size & watershed from HydroLAKES (HydroSHEDS)