Lake Seminole
Lake Seminole in Pinellas County, Florida has a water quality grade of D (Nutrient-rich). Water clarity: 1 ft visibility. Phosphorus: 63 µg/L. Surface area: 320 acres.
- Clarity
- 1 ft
- Typical in August
- 89°F
- Area
- 320 acres
- Type
- Hypereutrophic
- Trend
- ↑ Improving
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Lake Seminole →
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Lake Seminole is a 320-acre highly nutrient-loaded hypereutrophic lake in Pinellas County, Florida. Water quality is graded D based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 33 other monitored lakes in Pinellas County, Lake Seminole ranks #18 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-02-13. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyBacteria B
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 Seminole rarely exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 4.3% of 23 samples across 7 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 1 ft of visibility. Phosphorus level: 63 µg/L. Trophic State Index: 71.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1 ft | Not graded |
| Phosphorus | 63 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 71 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Lake Seminole
Compare lakeside cabins, hotels, and vacation rentals near Lake Seminole in Pinellas 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 Lake Seminole are listed below.
Top-rated places to stay near Lake Seminole
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Planning a whole trip? See where to stay at Florida’s top lakes →
Water Temperature
Lake Seminole typically sits around 89°F at the surface in August. Summer average is about 88°F. Usually warmest in Jun (about 89°F) and coldest in Jan (about 63°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 166 field readings (2010–2025) via the EPA Water Quality Portal.
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 320 acres |
| Public Access | Yes |
No bathymetric survey has been published for Lake Seminole, so its depth is not documented here.
Recreation & Access
- Lake Seminole Park and Public Boat RampPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Lake Seminole
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.196 m/yr | 5 |
| Phosphorus | ↑ Improving | -14.1 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Lake Seminole is a man-made reservoir impounded by the Lake Seminole Dam (completed 1949), built primarily for recreation on the Long Bayou; earth-type dam, 15 ft tall and 2,000 ft long.
- Surface area
- 320 ac
- Normal storage
- 3,000 ac-ft
- Max storage
- 4,800 ac-ft
- Drainage area
- 0 sq mi
- Hazard class
- Low
- Owner
- PINELLAS COUNTY
All listed purposes: Recreation;Other.
Source: USACE National Inventory of Dams, NID ID FL00429 · Operator website
EPA Impairment Status
Lake Seminole is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4B).
Causes of impairment
Source: EPA ATTAINS assessment unit FL1618 · Official waterbody report
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Lake Seminole under Clean Water Act (NPDES) discharge permits, including 5 classified by the EPA as major dischargers.
- Seminole, City OfSeminole · 1.4 mi away · NPDES FLS648388Major
- Redington Beach, Town OfRedington Beach · 2.6 mi away · NPDES FLS648477Major
- Madeira Beach, City OfMadeira Beach · 3.3 mi away · NPDES FLS648272Major
- North Redington Beach, Town OfNorth Redington Beach · 3.3 mi away · NPDES FLS648469Major
- Redington Shores, Town OfRedington Shores · 3.4 mi away · NPDES FLS648485Major
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 #18 of 34 lakes in Pinellas County
Nearby Lakes With Higher Grades
Lake Seminole 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 Pinellas County
Frequently asked questions about Lake Seminole
Where is Lake Seminole?
- Lake Seminole is a lake in Pinellas County, Florida. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Seminole?
- Lake Seminole in Pinellas County, Florida has a water quality grade of D (Nutrient-rich). Water clarity: 1 ft visibility. Phosphorus: 63 µg/L. Surface area: 320 acres.
Is Lake Seminole safe to swim in?
- Based on E. coli testing, Lake Seminole rarely exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 4.3% of 23 samples across 7 seasons. That works out to a bacteria swim-safety grade of B — a historical summary of past testing, not a current reading. Lake Seminole 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 Lake Seminole?
- Lake Seminole typically sits around 89°F at the surface in August, from 166 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
Are there boat ramps on Lake Seminole?
- Lake Seminole has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lake Seminole Park and Public Boat Ramp. Public access is listed as yes.
Explore Lake Seminole across LakeQuality
More Florida Lake Rankings
Other Grade D Lakes in Florida
Hypereutrophic Lakes in Florida
Where this data comes from
12 measurements from 1 monitoring station, 2023–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples12 samples · 2023–2025
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)
Named boat-access points from the USGS National Boat Ramps inventory