Consolidated Toxin Chart of DEP/Stantec Results:

Consolidated Table of DEP/ Stantec Results:

March 2020: The FL-DEP sampled at the southern entrance after the 'GreenClean' algacide treatment occurred, no toxin was detected. The Northwest Lobe did have small amounts of visible blue-green algae along the shore within the vegetation and an odor, at that time, but it was not sampled/tested. 

Apr - May -2020: Blue-green algae and likely dying BGA was visibly documented in smaller amounts.

Aug 2020: A large blue-green algae bloom has been occurring and documented in various lake lobes. On Aug 10, 2020 the bloom was reported to the FL-DEP. They finally tested on Aug 24, 2020 -- after email inquiry for the delay and reasons why. Results were as follows: Southern (Entrance) Lobe: Microcystin Toxin: 28 micrograms/L (or ppb); Northwest Lobe: Microcystin Toxin: 45 micrograms/L (or ppb)

Sept 15 2020: The FL-DEP sampled at the southern entrance after the 2nd 'GreenClean' algacide treatment occurred on Sept 11. Microcystin Toxin: 7.2 micrograms/L (or ppb)  The Northwest Lobe did have amounts of visible blue-green algae streaking, but it was not sampled/tested despite being sampled the month prior.

November 16 2020 : FL-DEP sampled at the southern entrance and northwest lobe, and measured Microcystin Toxin: 2.2 micrograms/L (or ppb)  and 1.6 micrograms/L (or ppb). The samples were taken from water not directly where BGA build-up was present.

December 15 2020: FL-DEP sampled at the southern entrance and northwest lobe, and measured Microcystin Toxin: 6 micrograms/L (or ppb)  and 5.4 micrograms/L (or ppb). The samples were taken from water not directly where maximum BGA build-up was present.

May 24 2021: FL-DEP sampled 3 locations of the lake. Entrance shoreline, Northwest Lobe near Cattails, and Middle of the Lake. They detected no microcystin toxin at this time.  Considered harmful "Prorocentrum minimum" algae was present in the sample in the middle of the lake. The other samples had various algae present, but no dominant type was found.

October 13 2021: FL-DEP sampled, within 30 minutes of a copper algaecide treatment on the lake, at the southern entrance, northwest lobe, and "center of lake" and measured Microcystin Toxin: 3.2 micrograms/L (or ppb)  and 1.5 micrograms/L (or ppb) and 1.6 micrograms/L (or ppb). The sample at the southern entrance was not taken where maximum BGA build-up was present, at scums near shoreline.

December 9 2021: FL-DEP sampled, 24 hours after a major GreenClean peroxide treatment on the lake, at the southern entrance, northwest lobe, and "center of lake" and measured Microcystin Toxin: 0.85 micrograms/L (or ppb)  and 1 micrograms/L (or ppb) and 0.93  micrograms/L (or ppb). Prop wash from the multiple boats and the treatment the previous day could have affected the baseline measurement. No before treatment sample was taken. 

January 18 2022: FL-DEP sampled, at the southern entrance lobe only and measured Microcystin Toxin: 8.2 micrograms/L (or ppb).

Chart and Table  last updated: Oct 11-14 2023

Photos last updated: Feb 25 2020

Late 2022 - 2023 Microcystin Toxin Data is available 

on Harbor Isle Lake Archive click here