Hillsborough-Keystone Lake
Hillsborough County, FloridaMesotrophic
Hillsborough-Keystone Lake is a mesotrophic lake in Hillsborough County, Florida. Water quality is graded B based on 2 sampling years through 2025. Compared to the 221 other monitored lakes in Hillsborough County, Hillsborough-Keystone Lake ranks #16 for water quality.
Source: EPA Water Quality Portal sampling records, Florida DNR, last sampled 2025-04-06. Grade methodology: LakeGrade methodology.
Watch Hillsborough-Keystone Lake water quality
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Murky, only visible to about 6 ft. Phosphorus level: 14 µg/L. Trophic State Index: 47.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6 ft | C |
| Phosphorus | 14 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Location
County Ranking
Ranked #16 of 222 lakes in Hillsborough County
Cleaner Lakes Within 30 Miles
Hillsborough-Keystone Lake holds Grade B. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Hillsborough County
More Florida Lake Rankings
Other Grade B Lakes in Florida
Bay County · Clarity: 4 ft
Brevard County · Clarity: 9.8 ft
Alachua County · Clarity: 5.5 ft
Seminole County · Clarity: 5 ft
Marion County · Clarity: 7 ft
Walton County · Clarity: 4 ft
Mesotrophic 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: 2025-04-06
Monitoring stations: 3
Where to stay near Hillsborough-Keystone Lake
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