TALLAHASSEE -- The Florida Department of Environmental Protection (FDEP) continues to monitor algal blooms in lakes, rivers and canals throughout the state.
During the seven day period from May 7 to May 13, there were 30 reported site visits, with 30 samples collected by FDEP. Algal bloom conditions were observed by the samplers at 19 of the sites.
If you see algae in the water, do not swim there or let pets drink the water, advised FDEP. Only about 25% of the species of cyanobacteria (blue-green algae) known to live in the Lake Okeechobee Waterway are capable of producing toxins, and those capable of producing toxins do not always do so. However, you cannot tell what species is dominant in a bloom and you cannot tell if toxins are present without laboratory testing.
The World Health Organization considers microcystin toxin levels above one part per billion (ppb) to be unsafe for drinking water and levels above 8 ppb to be unsafe for human recreational contact (such as swimming.)
The National Oceanic and Atmospheric Administration (NOAA) satellite imagery for Lake Okeechobee from May 11 showed moderate to high potential on approximately 95% of Lake Okeechobee, with the heaviest accumulation along the northwest and southeast shorelines. Images from May 13 and 14 showed cloud cover. (On the satellite image, areas in bright green show moderate algae potential. Areas in red or orange show high potential for algae. Areas in red or orange are most likely to have visible algae on the surface of the water.)
Extended cloud cover that blocks sunlight to the water column can cause algae to die. The image from May 15 showed just a small portion of the lake with moderate algae potential, and no areas likely to have surface algae.
According to FDEP, “bloom potential is subject to change due to rapidly changing environmental conditions or satellite inconsistencies (i.e., wind, rain, temperature or stage).”
The NOAA imagery shows potential for algae based on estimations of chlorophyll in the water based on pigments in the water detected by the satellite cameras. The imagery does not show what species of algae are present. It does not indicate if toxins are present. It is not unusual for the NOAA image to show cyanobacteria potential in the water when no algae are visible to the human eye. Algae are microscopic organisms. They become visible when they reproduce rapidly into sufficient quantity to be a visible “bloom.” Cyanobacteria, also called “blue-green algae” can move up and down in the water column by inflating and deflating gas vesicles. Algae are most often seen early in the day, when they rise up to the water surface for sunlight and heat. They are moved around by water currents and wind. A visible bloom is most common in stagnant water or in areas along a shoreline.
During the May 7-13 period, algal blooms were reported on the Caloosahatchee River at the Franklin Lock and near Barron Park.
Algal blooms were also observed in the C-44 canal (aka the St. Lucie Canal) between the Port Mayaca Lock and the St. Lucie Lock.
Elsewhere in the state, algal blooms were reported in St. Johns River and Lake George.
On May 10, South Florida Water Management District (SFWMD) staff collected samples on the Caloosahatchee river side of the Moore Haven Lock at the Franklin Lock. Both samples were dominated by Microcystis aeruginosa and had 2.5 parts per billion (ppb) and a trace level (0.63 ppb) of microcystins detected, respectively.
On May 10, FDEP staff collected samples at Lake Okeechobee side and the C-44 canal side of the Port Mayaca Lock. Both samples were dominated by Microcystis aeruginosa and had 65 ppb and 21 ppb of microcystins detected, respectively.
On May 10, Highlands County staff sampled Huckleberry Lake. The sample had no dominant algal taxon and a trace level (0.65 ppb) of microcystins were detected.
On May 10 and May 11, St. Johns River Water Management District (SJRWMD) collected samples from Blue Cypress Lake – Center, Stick Marsh – North and Crescent Lake – Mouth of Dunns Creek. The Blue Cypress Lake – Center sample was dominated by Microcystis sp. and had a trace level (0.63 ppb) of microcystins detected. The Stick Marsh – North sample had no dominant algal taxon and had a trace level (0.30 ppb) of microcystins detected. The Crescent Lake – Mouth of Dunns Creek sample was dominated by Microcystis aeruginosa and had a trace level (0.36 ppb) of microcystins detected.
On May 10, FDEP staff collected samples from Manatee River – Mouth, Anna Maria Sound – Safe Harbor Channel and Anna Maria Sound – 2714 Ave B by Dock in response to filamentous algae mats. Algal samples were collected and sent to the FWC Fish and Wildlife Research Institution for identification; those results are still pending. No cyanotoxins were detected in the water samples.
On May 12, City of Orlando staff sampled Lake Rowena – 0.1 miles from Mills Ave. There was no dominant algal taxon and 0.74 ppb of cylindrospermopsin was detected.
On May 12 and May 13, FDEP staff collected samples from Caloosahatchee River – Baron Park; Little Lake Conway – off FOP Lodge Dock; Lake Okeechobee – Clewiston Boat Ramp; Manatee River – 1220 Mill Creek by Dock; Lake Toho – Marina Dock; and Drainage to Sarah Bayou. The Caloosahatchee River – Baron Park sample was dominated by Microcystis aeruginosa and had 3.7 ppb microcystins detected. The Little Lake Conway – off FOP Lodge Dock sample had no dominant algal taxon and no cyanotoxins were detected. Sample results are still pending for Lake Okeechobee – Clewiston Boat Ramp; Manatee River – 1220 Mill Creek by Dock; Lake Toho – Marina Dock; and Drainage to Sarah Bayou.
On May 12 and May 13, SFWMD staff collected samples from Lake Okeechobee – S352 (Lakeside); C51 Canal – S155A (Upstream); C51 Canal – S155 (Upstream); M Canal – at 60th Street North; and C44 Canal – S80 (Upstream). The Lake Okeechobee – S352 (Lakeside) sample was dominated by Microcystis aeruginosa and had 4.3 ppb microcystins detected. Results are still pending for C51 Canal – S155A (Upstream); C51 Canal – S155 (Upstream); M Canal – at 60th Street North; and C44 Canal – S80 (Upstream).
On May 12 and May 13, SJRWMD staff collected samples at St. Johns River – Mandarin Point; Doctors Lake; St. Johns River – Shands Bridge; Lake Monroe – Center; and Lake Jesup – Center. The St. Johns River – Mandarin Point, Doctors Lake and St. Johns River – Shands Bridge samples had no dominant algal taxon and had no cyanotoxins detected, with saxitoxin results still pending. Sample results are still pending for Lake Monroe – Center and Lake Jesup – Center.
On May 13, Lee County staff collected samples from the Caloosahatchee River – Alva Boat Ramp and Caloosahatchee River – Davis Boat Ramp. Those results are still pending.