Harbor Isles Lake
Pinellas County, FloridaView mapDirections
Florida DEP publishes the water-quality measurements for Harbor Isles Lake. Here is what has been measured.
- Eutrophic
Harbor Isles Lake in Pinellas County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 1.6 ft visibility. Phosphorus: 95 µg/L.
Harbor Isles Lake is a productive, nutrient-rich eutrophic lake in Pinellas County, Florida. Overall water quality is improving over recent sampling years. Compared to the 33 other monitored lakes in Pinellas County, Harbor Isles Lake ranks #15 for water quality.
Source: EPA Water Quality Portal sampling records, FDEP, last sampled 2022-10-05. Methodology: how these readings are compared.
Swimming conditions
Readings onlyElevated nutrients
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Harbor Isles Lake is safe to swim in today is a call for the Florida Department of Environmental Protection and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Harbor Isles Lake
These are the measurements Florida DEP publishes for Harbor Isles Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.6 ft of visibility. Phosphorus 95 µg/L. TSI 70.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 95µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 70 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Harbor Isles Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Harbor Isles Lake typically sits around 78°F at the surface in October. Summer average is about 89°F. Usually warmest in Jul (about 90°F) and coldest in Jan (about 64°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (64°F) to its warmest (90°F).
Typical surface water temperature by month, from 60 field readings (2020–2022) via the EPA Water Quality Portal. See the full Harbor Isles Lake water temperature breakdown →
Stays via Stay22
Stays near Harbor Isles Lake
Compare lakeside cabins, hotels, and vacation rentals near Harbor Isles Lake 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Harbor Isles Lake are listed below.
Top-rated places to stay near Harbor Isles Lake
Prices for Oct 16–18, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Florida’s top lakes →
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Fishing Harbor Isles Lake
Water quality readings over time
3 seasons of samples on record (2020–2022). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving3 years
Phosphorus
Improving-8.5 µg/L/yr3 years
Nearby Lakes in Pinellas County
Frequently asked questions about Harbor Isles Lake
Where is Harbor Isles Lake?
- Harbor Isles Lake is a lake in Pinellas County, Florida. Its water-quality measurements are published by Florida DEP and shown on this page as reported.
What is the water quality of Harbor Isles Lake?
- Harbor Isles Lake in Pinellas County, Florida has water-quality measurements published by Florida DEP, shown here as reported. Water clarity: 1.6 ft visibility. Phosphorus: 95 µg/L.
Is Harbor Isles Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Harbor Isles Lake?
- Harbor Isles Lake typically sits around 78°F at the surface in October, from 60 EPA Water Quality Portal field readings (2020–2022). That is a typical value for the month, not a live reading.
Explore Harbor Isles Lake across LakeQuality
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Where this data comes from
110 measurements from 4 monitoring stations, 2020–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples110 samples · 2020–2022
Monitoring station identifiers (4)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.