Lake Thonotosassa
Lake Thonotosassa in Hillsborough County, Florida has a water quality grade of D (Nutrient-rich). Water clarity: 1.3 ft visibility. Phosphorus: 380 µg/L.
- Clarity
- 1.3 ft
- Typical in August
- 86°F
- Type
- Hypereutrophic
- Trend
- → Stable
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Lake Thonotosassa →
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Lake Thonotosassa is a highly nutrient-loaded hypereutrophic lake in Hillsborough County, Florida. Water quality is graded D based on 1 sampling years through 2025. Water clarity is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 123 other monitored lakes in Hillsborough County, Lake Thonotosassa ranks #104 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-07-14. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
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 | Not graded |
| Phosphorus | 380 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 82 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Lake Thonotosassa
Compare lakeside cabins, hotels, and vacation rentals near Lake Thonotosassa 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 grade measures nutrients and algae, not lodging — cabins and rentals around Lake Thonotosassa are listed below.
Top-rated places to stay near Lake Thonotosassa
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Planning a whole trip? See where to stay at Florida’s top lakes →
Water Temperature
Lake Thonotosassa typically sits around 86°F at the surface in August. Summer average is about 86°F. Usually warmest in Jul (about 87°F) and coldest in Dec (about 64°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 43 field readings (2017–2025) via the EPA Water Quality Portal. See the full Lake Thonotosassa water temperature breakdown →
Recreation & Access
- John B. Sargeant Public Boat RampPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Lake Thonotosassa
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.029 m/yr | 6 |
| Phosphorus | ↓ Declining | +8.56 µg/L/yr | 6 |
EPA Impairment Status
Lake Thonotosassa is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit FL1522B · Official waterbody report
County Ranking
Ranked #104 of 124 lakes in Hillsborough County
Nearby Lakes in Hillsborough County
Frequently asked questions about Lake Thonotosassa
Where is Lake Thonotosassa?
- Lake Thonotosassa is a lake in Hillsborough County, Florida. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Thonotosassa?
- Lake Thonotosassa in Hillsborough County, Florida has a water quality grade of D (Nutrient-rich). Water clarity: 1.3 ft visibility. Phosphorus: 380 µg/L.
Is Lake Thonotosassa safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Lake Thonotosassa has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
What is the water temperature of Lake Thonotosassa?
- Lake Thonotosassa typically sits around 86°F at the surface in August, from 43 EPA Water Quality Portal field readings (2017–2025). That is a typical value for the month, not a live reading.
Are there boat ramps on Lake Thonotosassa?
- Lake Thonotosassa has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include John B. Sargeant Public Boat Ramp. Public access is listed as yes.
Explore Lake Thonotosassa across LakeQuality
More Florida Lake Rankings
Other Grade D Lakes in Florida
Hypereutrophic Lakes in Florida
Where this data comes from
30 measurements from 1 monitoring station, 2022–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples30 samples · 2022–2025
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Named boat-access points from the USGS National Boat Ramps inventory