Lake-Joanna
Lake-Joanna in Lake County, Florida has a water quality grade of B (Good). Water clarity: 7.5 ft visibility. Phosphorus: 9 µg/L.
- Clarity
- 7.5 ft
- Typical in August
- 84°F
- Type
- Mesotrophic
- Trend
- ↓ Declining
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Lake-Joanna is a mesotrophic lake in Lake County, Florida. Water quality is graded B 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, Lake-Joanna ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-03-19. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyLow algae
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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Moderate clarity, visible to about 7.5 ft. Phosphorus level: 9 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.5 ft | Not graded |
| Phosphorus | 9 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lake-Joanna
Compare lakeside cabins, hotels, and vacation rentals near Lake-Joanna 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.
Top-rated places to stay near Lake-Joanna
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Planning a whole trip? See where to stay at Florida’s top lakes →
Water Temperature
Lake-Joanna typically sits around 84°F at the surface in August. Summer average is about 84°F. Usually warmest in Aug (about 84°F) and coldest in Mar (about 69°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 10 field readings (2015–2019) via the EPA Water Quality Portal. See the full Lake-Joanna water temperature breakdown →
Fishing Lake-Joanna
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.63 m/yr | 6 |
| Phosphorus | ↓ Declining | +1.73 µg/L/yr | 6 |
EPA Impairment Status
Lake-Joanna 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 FL2821B · Official waterbody report
County Ranking
Ranked #3 of 128 lakes in Lake County
Nearby Lakes in Lake County
Frequently asked questions about Lake-Joanna
Where is Lake-Joanna?
- Lake-Joanna is a lake in Lake County, Florida. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake-Joanna?
- Lake-Joanna in Lake County, Florida has a water quality grade of B (Good). Water clarity: 7.5 ft visibility. Phosphorus: 9 µg/L.
Is Lake-Joanna safe to swim in?
- Good for swimming, clear water with low algae levels. Lake-Joanna has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Lake-Joanna?
- Lake-Joanna typically sits around 84°F at the surface in August, from 10 EPA Water Quality Portal field readings (2015–2019). That is a typical value for the month, not a live reading.
Explore Lake-Joanna across LakeQuality
More Florida Lake Rankings
Other Grade B Lakes in Florida
Mesotrophic Lakes in Florida
Where this data comes from
330 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_WQX330 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