Sumter-Big Gant Lake
Sumter-Big Gant Lake in Sumter County, Florida has a water quality grade of C (Fair). Water clarity: 3 ft visibility. Phosphorus: 56.5 µg/L. Surface area: 93 acres.
- Clarity
- 3 ft
- Typical in May
- 78°F
- Max depth
- ~52 ft est.
- Area
- 93 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
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Sumter-Big Gant Lake is a 93-acre productive, nutrient-rich eutrophic lake in Sumter County, Florida with an estimated average depth of about 52 feet. Water quality is graded C based on 1 sampling years through 2025. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 10 other monitored lakes in Sumter County, Sumter-Big Gant Lake ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-04-22. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Very murky, less than 3 ft of visibility. Phosphorus level: 56.5 µg/L. Trophic State Index: 62.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 56.5 µg/L | Fair |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 62 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Sumter-Big Gant Lake
Compare lakeside cabins, hotels, and vacation rentals near Sumter-Big Gant Lake in Sumter 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.
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Water Temperature
Sumter-Big Gant Lake typically sits around 78°F at the surface in May. Usually warmest in May (about 78°F) and coldest in Jan (about 60°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 12 field readings (2010–2014) via the EPA Water Quality Portal. See the full Sumter-Big Gant Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~52 ft est. |
| Average Depth | ~10 ft est. |
| Surface Area | 93 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Florida has not published bathymetry for Sumter-Big Gant Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Roy Bug Story ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Sumter-Big Gant Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.21 m/yr | 5 |
| Phosphorus | ↓ Declining | +4.5 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Sumter-Big Gant Lake is a man-made reservoir impounded by the S-11 (completed 1965), built primarily for water supply on the Canal C; other-type dam, 20 ft tall and 64 ft long.
- Surface area
- 93 ac
- Normal storage
- 1,181 ac-ft
- Max storage
- 1,250 ac-ft
- Drainage area
- 20 sq mi
- Hazard class
- Significant
- Owner
- SWFWMD
All listed purposes: Water Supply;Flood Risk Reduction.
Source: USACE National Inventory of Dams, NID ID FL77000 · Operator website · Matched by proximity (0.73 km)
EPA Impairment Status
Sumter-Big Gant Lake 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 FL1378 · Official waterbody report · Matched by proximity (0.66 km)
County Ranking
Ranked #9 of 11 lakes in Sumter County
Nearby Lakes in Sumter County
Frequently asked questions about Sumter-Big Gant Lake
Where is Sumter-Big Gant Lake?
- Sumter-Big Gant Lake is a lake in Sumter County, Florida. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Sumter-Big Gant Lake?
- Sumter-Big Gant Lake in Sumter County, Florida has a water quality grade of C (Fair). Water clarity: 3 ft visibility. Phosphorus: 56.5 µg/L. Surface area: 93 acres.
Is Sumter-Big Gant Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Sumter-Big Gant Lake has a water quality grade of C (Fair). Always check local health department advisories before swimming.
What is the water temperature of Sumter-Big Gant Lake?
- Sumter-Big Gant Lake typically sits around 78°F at the surface in May, from 12 EPA Water Quality Portal field readings (2010–2014). That is a typical value for the month, not a live reading.
How deep is Sumter-Big Gant Lake?
- No published bathymetric survey covers Sumter-Big Gant Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 52 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 93 acres.
Are there boat ramps on Sumter-Big Gant Lake?
- Sumter-Big Gant Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Roy Bug Story Park. Public access is listed as yes.
Explore Sumter-Big Gant Lake across LakeQuality
More Florida Lake Rankings
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Where this data comes from
131 measurements from 3 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- FLORIDA LAKEWATCH
21FLKWAT_WQX131 samples · 2020–2025
Monitoring station identifiers (3)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory