Lake Thonotosassa
Hillsborough County, FloridaHypereutrophic
Lake Thonotosassa is a highly nutrient-loaded hypereutrophic lake in Hillsborough County, Florida. Water quality is graded F based on 2 sampling years through 2025. Compared to the 221 other monitored lakes in Hillsborough County, Lake Thonotosassa ranks #192 for water quality.
Source: EPA Water Quality Portal sampling records, Florida DNR, last sampled 2025-07-14. Grade methodology: LakeGrade methodology.
Watch Lake Thonotosassa water quality
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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: 380 µg/L. Trophic State Index: 82.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | F |
| Phosphorus | 380 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 82 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Location
County Ranking
Ranked #192 of 222 lakes in Hillsborough County
Cleaner Lakes Within 30 Miles
Lake Thonotosassa holds Grade F. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Hillsborough County
More Florida Lake Rankings
Other Grade F Lakes in Florida
Polk County · Clarity: 1.3 ft
Polk County · Clarity: 1 ft
Alachua County · Clarity: 2.4 ft
Volusia County · Clarity: 2 ft
Brevard County · Clarity: 1.6 ft
Highlands County · Clarity: 1 ft
Hypereutrophic Lakes in Florida
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-07-14
Monitoring stations: 1
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