Lake Kathryn
Lake Kathryn in Seminole County, Florida has a water quality grade of B (Good). Water clarity: 3 ft visibility. Phosphorus: 25 µg/L.
- Clarity
- 3 ft
- Typical in August
- 88°F
- Max depth
- ~47 ft est.
- Type
- Eutrophic
- Trend
- ↑ Improving
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Lake Kathryn is a productive, nutrient-rich eutrophic lake in Seminole County, Florida with an estimated average depth of about 47 feet. Water quality is graded B based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. Compared to the 121 other monitored lakes in Seminole County, Lake Kathryn ranks #38 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-03-31. 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, Lake Kathryn never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 19 samples across 6 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)
Very murky, less than 3 ft of visibility. Phosphorus level: 25 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 25 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Lake Kathryn
Compare lakeside cabins, hotels, and vacation rentals near Lake Kathryn 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 Lake Kathryn
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Florida’s top lakes →
Water Temperature
Lake Kathryn typically sits around 88°F at the surface in August. Summer average is about 87°F. Usually warmest in Aug (about 88°F) and coldest in Jan (about 65°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 50 field readings (2019–2025) via the EPA Water Quality Portal. See the full Lake Kathryn water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~47 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 Lake Kathryn.
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 Lake Kathryn
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.2 m/yr | 5 |
| Phosphorus | ↑ Improving | -1.45 µg/L/yr | 5 |
EPA Impairment Status
Lake Kathryn is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5A).
Causes of impairment
Source: EPA ATTAINS assessment unit FL2994K · Official waterbody report · Matched by proximity (1.09 km)
County Ranking
Ranked #38 of 122 lakes in Seminole County
Nearby Lakes in Seminole County
Frequently asked questions about Lake Kathryn
Where is Lake Kathryn?
- Lake Kathryn 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 Lake Kathryn?
- Lake Kathryn in Seminole County, Florida has a water quality grade of B (Good). Water clarity: 3 ft visibility. Phosphorus: 25 µg/L.
Is Lake Kathryn safe to swim in?
- Based on E. coli testing, Lake Kathryn never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 19 samples across 6 seasons. That works out to a bacteria swim-safety grade of A — a historical summary of past testing, not a current reading. Lake Kathryn 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 Lake Kathryn?
- Lake Kathryn typically sits around 88°F at the surface in August, from 50 EPA Water Quality Portal field readings (2019–2025). That is a typical value for the month, not a live reading.
How deep is Lake Kathryn?
- No published bathymetric survey covers Lake Kathryn, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 47 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Lake Kathryn across LakeQuality
Planning a trip around Canaveral?
Lake Kathryn is about 36 miles from Canaveral National Seashore. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Canaveral →More Florida Lake Rankings
Other Grade B Lakes in Florida
Eutrophic Lakes in Florida
Where this data comes from
66 measurements from 3 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples38 samples · 2020–2025
- Submitting organization not recorded for these samples28 samples · 2022–2024
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)