Sylvan Lake
Sylvan Lake in Seminole County, Florida has a water quality grade of B (Good). Water clarity: 5.6 ft visibility. Phosphorus: 14 µg/L.
- Clarity
- 5.6 ft
- Typical in August
- 87°F
- Type
- Mesotrophic
- Trend
- → Stable
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Sylvan Lake is a mesotrophic lake in Seminole County, Florida. Water quality is graded B based on 1 sampling years through 2025. Water clarity is declining over recent sampling years. Compared to the 121 other monitored lakes in Seminole County, Sylvan Lake ranks #72 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-05-13. 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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Murky, only visible to about 5.6 ft. Phosphorus level: 14 µg/L. Trophic State Index: 47.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.6 ft | Not graded |
| Phosphorus | 14 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Sylvan Lake
Compare lakeside cabins, hotels, and vacation rentals near Sylvan Lake in Seminole 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 Sylvan Lake
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Water Temperature
Sylvan Lake typically sits around 87°F at the surface in August. Summer average is about 87°F. Usually warmest in Jul (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 Sylvan Lake water temperature breakdown →
Fishing Sylvan Lake
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.61 m/yr | 5 |
| Phosphorus | ↑ Improving | -2.9 µg/L/yr | 5 |
EPA Impairment Status
Sylvan 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 FL2961 · Official waterbody report
County Ranking
Ranked #72 of 122 lakes in Seminole County
Nearby Lakes in Seminole County
Frequently asked questions about Sylvan Lake
Where is Sylvan Lake?
- Sylvan Lake is a lake in Seminole County, Florida. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Sylvan Lake?
- Sylvan Lake in Seminole County, Florida has a water quality grade of B (Good). Water clarity: 5.6 ft visibility. Phosphorus: 14 µg/L.
Is Sylvan Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Sylvan Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Sylvan Lake?
- Sylvan Lake typically sits around 87°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.
Explore Sylvan Lake across LakeQuality
More Florida Lake Rankings
Other Grade B Lakes in Florida
Mesotrophic Lakes in Florida
Where this data comes from
40 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 samples40 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