Alligator Lake
Pinellas County, FloridaHypereutrophic
Alligator Lake is a highly nutrient-loaded hypereutrophic lake in Pinellas County, Florida. Water quality is graded F based on 2 sampling years through 2025. Compared to the 54 other monitored lakes in Pinellas County, Alligator Lake ranks #50 for water quality.
Source: EPA Water Quality Portal sampling records, Florida DNR, last sampled 2025-04-09. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 1.3 ft of visibility. Phosphorus level: 140 µg/L. Trophic State Index: 74.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | F |
| Phosphorus | 140 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 74 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Location
County Ranking
Ranked #50 of 55 lakes in Pinellas County
Cleaner Lakes Within 30 Miles
Alligator Lake holds Grade F. 3 nearby lakes hold higher grades.
- BChatauqref LakePinellas County · 2 mi · Two grade letters higher (F → B)
- BLake ChautauquaPinellas County · 1.9 mi · Two grade letters higher (F → B)
- DPinellas-Cliff Stephens Park LakePinellas County · 1.5 mi · Higher grade (F → D)
Nearby Lakes in Pinellas County
More Florida Lake Rankings
Other Grade F Lakes in Florida
Hypereutrophic Lakes in Florida
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Alligator Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger.
- Safety Harbor, City OfSafety Harbor · 1.1 mi away · NPDES FLS648370Major
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-04-09
Monitoring stations: 1
Where to stay near Alligator Lake
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