Denham Lake
Denham Lake in Lake County, Florida has a water quality grade of D (Nutrient-rich). Water clarity: 0.8 ft visibility. Phosphorus: 84.4 µg/L.
- Clarity
- 0.8 ft
- Typical in August
- 87°F
- Type
- Hypereutrophic
- Trend
- ↓ Declining
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Denham Lake →
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Denham Lake is a highly nutrient-loaded hypereutrophic lake in Lake County, Florida. Water quality is graded D based on 1 sampling years through 2025. Overall water quality is declining over recent sampling years. Compared to the 127 other monitored lakes in Lake County, Denham Lake ranks #127 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-01-29. 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, Denham Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 5 samples across 2 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: D (Nutrient-rich)
Very murky, less than 0.8 ft of visibility. Phosphorus level: 84.4 µg/L. Trophic State Index: 74.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.8 ft | Not graded |
| Phosphorus | 84.4 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 74 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Denham Lake
Compare lakeside cabins, hotels, and vacation rentals near Denham Lake in Lake 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 Denham Lake are listed below.
Top-rated places to stay near Denham Lake
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Planning a whole trip? See where to stay at Florida’s top lakes →
Water Temperature
Denham Lake typically sits around 87°F at the surface in August. Summer average is about 87°F. Usually warmest in Aug (about 87°F) and coldest in Oct (about 68°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 10 field readings (2011–2025) via the EPA Water Quality Portal. See the full Denham Lake water temperature breakdown →
Fishing Denham Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.212 m/yr | 5 |
| Phosphorus | ↓ Declining | +4.34 µg/L/yr | 5 |
EPA Impairment Status
Denham Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit FL2832A · Official waterbody report
County Ranking
Ranked #127 of 128 lakes in Lake County
Nearby Lakes With Higher Grades
Denham Lake holds Grade D. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Lake County
Frequently asked questions about Denham Lake
Where is Denham Lake?
- Denham Lake is a lake in Lake County, Florida. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Denham Lake?
- Denham Lake in Lake County, Florida has a water quality grade of D (Nutrient-rich). Water clarity: 0.8 ft visibility. Phosphorus: 84.4 µg/L.
Is Denham Lake safe to swim in?
- Based on E. coli testing, Denham Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 5 samples across 2 seasons. That works out to a bacteria swim-safety grade of A — a historical summary of past testing, not a current reading. Denham Lake has a water quality grade of D (Nutrient-rich). 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 Denham Lake?
- Denham Lake typically sits around 87°F at the surface in August, from 10 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
Explore Denham Lake across LakeQuality
More Florida Lake Rankings
Other Grade D Lakes in Florida
Hypereutrophic Lakes in Florida
Where this data comes from
9 measurements from 1 monitoring station, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples9 samples · 2024–2025
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