Lake Brantley
Seminole County, FloridaView mapDirections
Florida DEP publishes the water-quality measurements for Lake Brantley. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
- Limited data
Lake Brantley in Seminole County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 9.5 ft visibility. Phosphorus: 11.5 µg/L.
Lake Brantley 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, Lake Brantley ranks #36 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-04-01. Methodology: how these readings are compared.
If you are planning to stay, you can search lake houses and cabins around Lake Brantley on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
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. Lake Brantley is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Lake Brantley 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 Lake Brantley
These are the measurements Florida DEP publishes for Lake Brantley, 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 9.5 ft. Phosphorus 11.5 µg/L. TSI 42.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 9.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 11.5µg/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. | 42 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
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Answers come straight from the public measurements and survey records on this page.
Water Temperature
Lake Brantley typically sits around 78°F at the surface in October. Summer average is about 89°F. Usually warmest in Jul (about 89°F) and coldest in Jan (about 63°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (63°F) to its warmest (89°F).
Typical surface water temperature by month, from 57 field readings (2010–2025) via the EPA Water Quality Portal. See the full Lake Brantley water temperature breakdown →
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Stays near Lake Brantley
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Fishing Lake Brantley
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
Lake Brantley 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 Lake Brantley
Where is Lake Brantley?
- Lake Brantley 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 Lake Brantley?
- Lake Brantley in Seminole County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 9.5 ft visibility. Phosphorus: 11.5 µg/L.
Is Lake Brantley safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Brantley is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Lake Brantley?
- Lake Brantley typically sits around 78°F at the surface in October, from 57 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
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Where this data comes from
41 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples41 samples · 2020–2025
Monitoring station identifiers (1)
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