Seminole-Brantley Lake
Seminole County, FloridaView mapDirections
Florida DEP publishes the water-quality measurements for Seminole-Brantley Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
Seminole-Brantley Lake in Seminole County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 9 ft visibility. Phosphorus: 15 µg/L.
Seminole-Brantley Lake is a mesotrophic lake in Seminole County, Florida. Water clarity is declining over recent sampling years. Compared to the 121 other monitored lakes in Seminole County, Seminole-Brantley Lake ranks #42 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-04-05. 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. Seminole-Brantley Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Seminole-Brantley 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-Brantley Lake
These are the measurements Florida DEP publishes for Seminole-Brantley Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 9 ft. Phosphorus 15 µg/L. TSI 44.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 15µg/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. | 44 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
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Fishing Seminole-Brantley Lake
Water Quality Trend: Stable
Based on 5 years of monitoring (2020–2024).
Water clarity
Worsening5 years
Phosphorus
Improving-0.3 µg/L/yr5 years
EPA Impairment Status
Seminole-Brantley 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 FL2956F · Official waterbody report
Nearby Lakes in Seminole County
Frequently asked questions about Seminole-Brantley Lake
Where is Seminole-Brantley Lake?
- Seminole-Brantley 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-Brantley Lake?
- Seminole-Brantley Lake in Seminole County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 9 ft visibility. Phosphorus: 15 µg/L.
Is Seminole-Brantley Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Seminole-Brantley Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
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Where this data comes from
266 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_WQX266 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