Summer heat often brings algae blooms, and the Florida Department of Environmental Protection (FDEP) and the South Florida Water Management District (SFWMD) are keeping a close watch on conditions in Lake Okeechobee.

While some algae have been visible in the Lake O water this year, tests found no toxins.

The Lake Okeechobee Waterway (which includes the St. Lucie River, St. Lucie (C-44) Canal, Lake O and the Caloosahatchee River) is home to 28 species of cyanobacteria according to the U.S. Geological Survey. Cyanobacteria – commonly called blue-green algae – are the oldest documented form of life on the planet and are part of the natural ecosystem. About 25% of the species of cyanobacteria are capable of producing toxins. However, you can’t tell which species of cyanobacteria may be dominant in a bloom or if toxins are present without laboratory tests.

Studies conducted by Florida Atlantic University found cyanobacteria are more likely to produce toxins if high levels of dissolved inorganic nitrogen are present in the water. In coastal algal blooms, high nitrogen levels are often linked to sewage spills or runoff from septic tanks.

FDEP responds to reports of visible algal blooms. May 19-21, FDEP collected samples of 15 algal blooms in Florida, including two on Lake Okeechobee. The Lake O sample, which was collected near Port Mayaca, contained no toxins. Another sample, which was taken from the C-44 canal (St. Lucie canal) near Port Mayaca, also contained no toxins.

The Environmental Protection Agency considers microcystin toxin levels below 1 part per billion (ppb) to be safe for drinking water, and levels below 8.0 ppb to be safe for human recreational contact (such as swimming).

Other algal blooms sampled by FDEP included:

• Lorraine Lake — West Shore: Microcystis aeruginosa; trace level [0.38 part per billion (ppb)] of cylindrospermopsin detected.
• Eagle Lake — Park: Microcystis aeruginosaand Botryococcus braunii co-dominant; no cyanotoxins detected.
• East Lake — South Dock: Microcystis aeruginosa; no cyanotoxins detected.
• Ward Lake — Jiggs Landing: Dolichospermum circinale; no cyanotoxins detected.
• Dunn’s Creek — Highway 17 Bridge:Microcystis aeruginosa and Raphidiopsis raciborskii co-dominant; trace level (0.27 ppb) of cylindrospermopsin detected.
• Georges Lake — Center: Microcystis aeruginosa and Dolichospermum co-dominant; no cyanotoxins detected.
• Georges Lake — Boat Ramp:Microcystis aeruginosa and Dolichospermum co-dominant; no cyanotoxins detected.
• Bimini Basin Canal — off Four Freedoms Park:No dominant algal taxon; no cyanotoxins detected.
• Lake Grady — at Shadow Run Dam: Microcystis wesenbergii and Dolichospermum circinale co-dominant; trace level (0.52 ppb) of microcystins detected.
• Lake Sampson — Rowell and Sampson Canal:Microcystis aeruginosa; no cyanotoxins detected.
• Lake Weir — North: Raphidiopsis raciborskii and Botryococcus brauniico-dominant; no cyanotoxins detected.
• Lake Marian — Pavilion: Microcystis aeruginosaand Raphidiopsis raciborskii co-dominant; an estimated 1.6 ppb of microcystins detected.
• Lake Kissimmee — Joe Overstreet Road Boat Ramp: Microcystis aeruginosa and Coelosphaerium  co-dominant; no cyanotoxins detected.

May 20-21, SFWMD staff collected 26 routine samples from Lake Okeechobee.

Lake Okeechobee — KISSR0.0: Planktolyngbya limnetica; no cyanotoxins detected.

• Lake Okeechobee — LZ2: Planktolyngbya limnetica; no cyanotoxins detected.
• Lake Okeechobee — NES191:Dolichospermum circinale; no cyanotoxins detected.
• Lake Okeechobee— L001: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — NES135:No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — NCENTER: Microcystis aeruginosa; no cyanotoxins detected.
• Lake Okeechobee — EASTSHORE:Microcystis aeruginosa; no cyanotoxins detected.
• Lake Okeechobee — L004: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — L008: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — L005: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — POLESOUT3: Microcystis aeruginosa; no cyanotoxins detected.
• Lake Okeechobee — POLESOUT2: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — POLESOUT1: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — POLESOUT:Planktolyngbya limnetica; no cyanotoxins detected.
• Lake Okeechobee — KBARSE: Planktolyngbya limnetica; no cyanotoxins detected.
• Lake Okeechobee — CLV10A: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — LZ40:No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — L006: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — PALMOUT3:No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — PALMOUT2:Microcystis aeruginosa; no cyanotoxins detected.
• Lake Okeechobee — PALMOUT1:Microcystis aeruginosa; no cyanotoxins detected.
• Lake Okeechobee — PALMOUT:No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — LZ30: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — POLE3S: No dominant algal taxon; no cyanotoxins detected.
• Lake Okeechobee — L007:Microcystis aeruginosa; no cyanotoxins detected.
• Lake Okeechobee — LZ25A:No dominant algal taxon; no cyanotoxins detected.
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Around the state, other agencies also conduct water sampling.

On may 19, St. Johns River Water Management District (SJRWMD) staff collected one routine HAB monitoring sample and one HAB response sample.  

• Lake Washington — Center: No dominant algal taxon; no cyanotoxins detected.
• Lake Yale — Center: Microcystis aeruginosaand Botryococcus braunii co-dominant; trace level (0.12 ppb) of microcystins detected.

On May 20, Florida Fish and Wildlife Conservation Commission staff collected one HAB response sample at Old Tampa Bay — Rocky Shores Drive Canal. There was no dominant algal taxon and no cyanotoxins detected.