Hancock Outflow Lake
Hancock Outflow Lake in Polk County, Florida has a water quality grade of D (Nutrient-rich). Water clarity: 0.7 ft visibility. Phosphorus: 478 µg/L. Surface area: 4541 acres.
- Clarity
- 0.7 ft
- Typical in September
- 83°F
- Area
- 4,541 acres
- 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 Hancock Outflow Lake →
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Hancock Outflow Lake is a 4,541-acre highly nutrient-loaded hypereutrophic lake in Polk 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 176 other monitored lakes in Polk County, Hancock Outflow Lake ranks #171 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2025-09-15. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyBacteria advisory
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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 0.7 ft of visibility. Phosphorus level: 478 µg/L. Trophic State Index: 88.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.7 ft | Not graded |
| Phosphorus | 478 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 88 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Hancock Outflow Lake
Compare lakeside cabins, hotels, and vacation rentals near Hancock Outflow Lake in Polk 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 Hancock Outflow Lake are listed below.
Top-rated places to stay near Hancock Outflow Lake
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Planning a whole trip? See where to stay at Florida’s top lakes →
Water Temperature
Hancock Outflow Lake typically sits around 83°F at the surface in September. Summer average is about 84°F. Usually warmest in Jun (about 84°F) and coldest in Dec (about 67°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 9 field readings (2023–2025) via the EPA Water Quality Portal.
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 4,541 acres |
No bathymetric survey has been published for Hancock Outflow Lake, so its depth is not documented here.
Fishing Hancock Outflow Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.002 m/yr | 5 |
| Phosphorus | ↓ Declining | +65.33 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Hancock Outflow Lake is a man-made reservoir impounded by the P-11 (completed 1965), built primarily for flood risk reduction on the Saddle Creek; concrete-type dam, 10 ft tall and 110 ft long.
- Surface area
- 4,541 ac
- Normal storage
- 44,048 ac-ft
- Max storage
- 31,787 ac-ft
- Drainage area
- 131 sq mi
- Hazard class
- Significant
- Owner
- SWFWMD
Source: USACE National Inventory of Dams, NID ID FL13003 · Operator website · Matched by proximity (0.95 km)
EPA Impairment Status
Hancock Outflow Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit FL1623K · Official waterbody report · Matched by proximity (2.19 km)
County Ranking
Ranked #171 of 177 lakes in Polk County
Nearby Lakes in Polk County
Frequently asked questions about Hancock Outflow Lake
Where is Hancock Outflow Lake?
- Hancock Outflow Lake is a lake in Polk County, Florida. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Hancock Outflow Lake?
- Hancock Outflow Lake in Polk County, Florida has a water quality grade of D (Nutrient-rich). Water clarity: 0.7 ft visibility. Phosphorus: 478 µg/L. Surface area: 4541 acres.
Is Hancock Outflow Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Hancock Outflow Lake has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
What is the water temperature of Hancock Outflow Lake?
- Hancock Outflow Lake typically sits around 83°F at the surface in September, from 9 EPA Water Quality Portal field readings (2023–2025). That is a typical value for the month, not a live reading.
Explore Hancock Outflow Lake across LakeQuality
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Where this data comes from
18 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 samples18 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