Willis Lake
Willis Lake in Orange County, Florida has a water quality grade of B (Good). Water clarity: 7.2 ft visibility. Phosphorus: 6 µg/L.
- Clarity
- 7.2 ft
- Typical in August
- 88°F
- Max depth
- ~39 ft est.
- Type
- Oligotrophic
- Trend
- → Stable
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Willis Lake is a cold, clear oligotrophic lake in Orange County, Florida with an estimated average depth of about 39 feet. Water quality is graded B based on 1 sampling years through 2025. Water clarity is improving over recent sampling years. Compared to the 319 other monitored lakes in Orange County, Willis Lake ranks #121 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-02-17. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyBacteria A
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.
Based on E. coli testing, Willis Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 29 samples across 8 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Florida’s current beach and health-department advisories before swimming.
Water Quality Grade: B (Good)
Moderate clarity, visible to about 7.2 ft. Phosphorus level: 6 µg/L. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.2 ft | Not graded |
| Phosphorus | 6 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Willis Lake
Compare lakeside cabins, hotels, and vacation rentals near Willis Lake in Orange 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.
Top-rated places to stay near Willis Lake
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Water Temperature
Willis Lake typically sits around 88°F at the surface in August. Summer average is about 88°F. Usually warmest in Jun (about 88°F) and coldest in Feb (about 69°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 54 field readings (2010–2025) via the EPA Water Quality Portal. See the full Willis Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~39 ft est. |
| Average Depth | ~10 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Florida has not published bathymetry for Willis 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.
Fishing Willis Lake
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.16 m/yr | 5 |
| Phosphorus | ↓ Declining | +1.8 µg/L/yr | 5 |
EPA Impairment Status
Willis 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 FL3169C · Official waterbody report · Matched by proximity (2.98 km)
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Willis Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Sea WorldOrlando · 1.2 mi away · NPDES FL0629332Recent violation
- Discovery CoveOrlando · 1.2 mi away · NPDES FL0622648
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
County Ranking
Ranked #121 of 320 lakes in Orange County
Nearby Lakes in Orange County
Frequently asked questions about Willis Lake
Where is Willis Lake?
- Willis Lake is a lake in Orange County, Florida. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Willis Lake?
- Willis Lake in Orange County, Florida has a water quality grade of B (Good). Water clarity: 7.2 ft visibility. Phosphorus: 6 µg/L.
Is Willis Lake safe to swim in?
- Based on E. coli testing, Willis Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 29 samples across 8 seasons. That works out to a bacteria swim-safety grade of A — a historical summary of past testing, not a current reading. Willis Lake has a water quality grade of B (Good). Bacteria levels can spike quickly after heavy rain, so always check Florida's current beach and health-department advisories before you swim.
What is the water temperature of Willis Lake?
- Willis Lake typically sits around 88°F at the surface in August, from 54 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Willis Lake?
- No published bathymetric survey covers Willis Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 39 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Willis Lake across LakeQuality
More Florida Lake Rankings
Other Grade B Lakes in Florida
Oligotrophic Lakes in Florida
Where this data comes from
63 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples63 samples · 2020–2025
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)