Keystone Lake
Hillsborough County, FloridaEutrophic
Keystone Lake is a productive, nutrient-rich eutrophic lake in Hillsborough County, Florida. Water quality is graded C based on 2 sampling years through 2025. Compared to the 221 other monitored lakes in Hillsborough County, Keystone Lake ranks #142 for water quality.
Source: EPA Water Quality Portal sampling records, Florida DNR, last sampled 2025-06-10. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Very murky, less than 2.6 ft of visibility. Phosphorus level: 18 µg/L. Trophic State Index: 55.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.6 ft | F |
| Phosphorus | 18 µg/L | B |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 55 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Location
County Ranking
Ranked #142 of 222 lakes in Hillsborough County
Cleaner Lakes Within 30 Miles
Keystone Lake holds Grade C. 5 nearby lakes hold higher grades.
- AHillsborough-Alice LakeHillsborough County · 0.9 mi · Two grade letters higher (C → A)
- AHillsborough-Mound LakeHillsborough County · 1.3 mi · Two grade letters higher (C → A)
- BHillsborough-Island Ford LakeHillsborough County · 0.7 mi · Higher grade (C → B)
- BHillsborough-Keystone LakeHillsborough County · 0.8 mi · Higher grade (C → B)
- BHillsborough-Taylor LakeHillsborough County · 1.2 mi · Higher grade (C → B)
Nearby Lakes in Hillsborough County
More Florida Lake Rankings
Other Grade C Lakes in Florida
Orange County · Clarity: 3.5 ft
Walton County · Clarity: 4.2 ft
Seminole County · Clarity: 4.5 ft
Seminole County · Clarity: 2.9 ft
Polk County · Clarity: 3.5 ft
Volusia County · Clarity: 4.5 ft
Eutrophic 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: 2025-06-10
Monitoring stations: 1
Where to stay near Keystone Lake
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