Lake Water Quality Data

To view the water quality data and other public data regarding Harbor Isle Lake, please visit the archive pages below, by the clicking the associated button.

Known Issues

• Confirmed Most Significant Contributor of Nutrient Loading (Nitrogen and Phosphorous) is from Sediment - Fill Material

• Lack of Sample Points

The City Contractor, Solitude Lake Management, was sampling 3 areas of the lake from Jan-March 2020, but then changed to only one sample point thereafter-- this reduced valuable data points. It is now more limited data. Considering the entire lake is affected, this water quality monitoring does not accurately measure the effectiveness of current implementations or treatments throughout the 26 acre lake-- such as prior reports in Jan-March 2020-- where at least sampling locations were being tested in father away lake lobe sections. They've now been eliminated. Why?

According to the August 13, 2020 City Council Meeting, the City had also contracted another environmental firm, GPI, to take water quality samples for 2020. This collected water quality data has not been publicly posted for access either.

At this time, the City has still not provided a public website for access of all these reports, data, and other updates as the city receives them. This has been a reoccurring problem since 2019.

• Dominant Toxic Blue-Green Algae (Cyanobacteria) blooms year-round, instead of no non-toxic green algae types

• High Nutrient Levels (Nitrogen and Phosphorous) in Bottom Water

• High Nutrient Levels (Nitrogen and Phosphorous) in Water Column

• High Nutrient Levels in the Sediment - Fill Material

& Very Likely:

• Still Not Enough Dissolved Oxygen at the Harbor Isle Lake's bottom through-out the lake -- more sample sites would further confirm or deny problem areas

• Lack of Enough Circulation of Water from Top - Down to distribute oxygen, disrupt algae / plant growth -- for entire lake or specific high input-loading areas

The measurements of these parameters, such as in Solitude's monthly reports or others, are on a extremely small scale. In order to better understand the scale of these values, please note:

1 milligram per liter (mg/L) = 1,000 micrograms per liter (µg/L) OR 1 microgram per liter (µg/L) = 0.001 mg/L
1 microgram per liter (µg/L) = 1 parts per billion (ppb)
1 parts per billion (ppb) is approximately 1 drop of water in an Olympic-size swimming pool.

"Total Phosphorous concentrations above 30 ppb are enough to stimulate algae blooms
Inorganic Nitrogen concentrations above 300 ppb are able to stimulate algae growth"

From Solitude's Monthly Reports from Jan-March 2020 -- Harbor Isle Lake had greater than 300 ppb Phosphorous and 2500 ppb Nitrogen in the 3 sample testing sites for surface and bottom water.

High Nutrient Levels in the Sediment - Fill Material

Previous Sediment Sample Lab Analysis for Nutrients :

September 2021 Harbor Isle Lake Sediment Report contracted by the City of St. Pete re-confirmed this problem. The report can be found on the archive page here.