Hillsborough-Thonotosassa Lake
Hillsborough County, FloridaView mapDirections
Florida DEP publishes the water-quality measurements for Hillsborough-Thonotosassa Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Algal growth
Hillsborough-Thonotosassa Lake in Hillsborough County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 1.5 ft visibility. Phosphorus: 321 µg/L.
Hillsborough-Thonotosassa Lake is a highly nutrient-loaded hypereutrophic lake in Hillsborough County, Florida. Water clarity is improving over recent sampling years. Compared to the 123 other monitored lakes in Hillsborough County, Hillsborough-Thonotosassa Lake ranks #103 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2024-06-08. Methodology: how these readings are compared.
If you are planning to stay, you can search lake houses and cabins around Hillsborough-Thonotosassa Lake on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
Swimming conditions
Readings onlyRecreation use not supported
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. Hillsborough-Thonotosassa Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, impaired biota (cause unknown), nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Hillsborough-Thonotosassa Lake 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 Hillsborough-Thonotosassa Lake
These are the measurements Florida DEP publishes for Hillsborough-Thonotosassa Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.5 ft of visibility. Phosphorus 321 µg/L. TSI 79.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 321µg/L | Poor 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. | 79 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Hillsborough-Thonotosassa Lake
Answers come straight from the public measurements and survey records on this page.
Stays via Stay22
Stays near Hillsborough-Thonotosassa Lake
Compare lakeside cabins, hotels, and vacation rentals near Hillsborough-Thonotosassa Lake in Hillsborough County, Florida — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Hillsborough-Thonotosassa Lake are listed below.
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Fishing Hillsborough-Thonotosassa Lake
Water Quality Trend: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Improving6 years
Phosphorus
Worsening+8.56 µg/L/yr6 years
EPA Impairment Status
Hillsborough-Thonotosassa Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit FL1522B · Official waterbody report
Nearby Lakes in Hillsborough County
Frequently asked questions about Hillsborough-Thonotosassa Lake
Where is Hillsborough-Thonotosassa Lake?
- Hillsborough-Thonotosassa Lake is a lake in Hillsborough County, Florida. Its water-quality measurements are published by Florida DEP and shown on this page as reported.
What is the water quality of Hillsborough-Thonotosassa Lake?
- Hillsborough-Thonotosassa Lake in Hillsborough County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 1.5 ft visibility. Phosphorus: 321 µg/L.
Is Hillsborough-Thonotosassa Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Hillsborough-Thonotosassa Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, impaired biota (cause unknown), nutrients (phosphorus, nitrogen). Check local advisories before you swim.
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Where this data comes from
95 measurements from 3 monitoring stations, 2022–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- FLORIDA LAKEWATCH
21FLKWAT_WQX95 samples · 2022–2024
Monitoring station identifiers (3)
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