Skip to Content

Blue-green algae update

Weekly Update from the Florida Department of Environmental Protection (DEP)


Dec. 1 – Dec. 7, 2023 – There were four reported site visits in the past seven days with four samples collected. Algal bloom conditions were observed by samplers at four of the sites.

The best available satellite imagery for Lake Okeechobee is from 12/6, and it shows low to moderate bloom potential on approximately 5-10% of the lake, primarily in the nearshore waters on the western half of the lake. 

The best available satellite imagery for the Caloosahatchee Estuary is from 12/6, and it shows very scattered moderate bloom potential on visible portions of the estuary. 

The best available satellite imagery for the St. Lucie Estuary is from 12/6, and it shows no bloom potential on visible portions of the estuary. 

Satellite for the St. Johns River from 12/7 shows lightly scattered low bloom potential on Lake George and the mainstem of the St. Johns River down to the Doctors Lake. 

Please keep in mind that bloom potential is subject to change due to rapidly changing environmental conditions or satellite inconsistencies (i.e., wind, rain, temperature or stage.)


Blue-green algae field visits this past week


On 12/4, Florida Department of Environmental Protection (DEP) staff collected a Harmful Algal Bloom (HAB) response sample at Tiger Lake – Center. There was no dominant algal taxon and a trace level [0.45 parts per billion (ppb)] of microcystins was detected.

On 12/7, Highlands County staff collected three HAB response samples from Lake Placid, Lake June-in-Winter – Boat Ramp and Lake Glenada – Boat Ramp. Results are pending.

Last Week

On 11/30, St. Johns River Water Management District staff collected a routine HAB monitoring sample at Lake Monroe – Center. There was no dominant algal taxon and no cyanotoxins detected.

Results for completed analyses are available at FloridaDEP.gov/AlgalBloom

Previous week

On 11/20 – 11/29, Florida Department of Environmental Protection (DEP) staff collected seven Harmful Algal Bloom (HAB) response samples. Dominant algal taxa and cyanotoxin results follow each waterbody name.

Lake Drawdy – Center: Microcystis aeruginosa; trace level [0.16 parts per billion (ppb)] of microcystins was detected.

Lake Down – S Boat Ramp: Microcystis aeruginosa; no cyanotoxins detected.

Chrise Lake: Microcystis wesenbergii; no cyanotoxins detected.

Lake Howell – Center: Microcystis aeruginosa; no cyanotoxins detected.

Lake Taylor – Odessa: Coelasphaerium kuetzingianum; trace level (0.25 ppb) microcystins detected.

Pioneer Lake – NE Shore: Microcystis aeruginosa; trace level (0.62 ppb) microcystins detected.

Blanton Lake – South Lobe: Co-dominated by Microcystis aeruginosa and Microcystis wesenbergii; 8.6 ppb microcystins detected.

On 11/20 – 11/30, St. Johns River Water Management District staff collected six routine HAB monitoring samples. Dominant algal taxa and cyanotoxin results follow each waterbody name.

Lake Washington – Center: no dominant algal taxon; no cyanotoxins detected.

Stick Marsh – North: Microcystis aeruginosa; no cyanotoxins detected.

Blue Cypress Lake – Center: no dominant algal taxon; no cyanotoxins detected.

Lake Yale South of Center: Co-dominated by Microcystis aeruginosa and Cylindrospermopsis raciborskii; trace level (0.30 ppb) cylindrospermopsin detected.

Lake Jesup – Center: Co-dominated by Microcystis aeruginosa and Cylindrospermopsis raciborskii; trace level (0.17 ppb) cylindrospermopsin detected.

Lake Monroe – Center: Results pending.

On 11/20, Highlands County staff collected a HAB response sample at Lake Genada – Boat Ramp. The sample was dominated by Microcystis aeruginosa and had 25 ppb microcystins detected.

Two weeks ago

On 11/13 – 11/15, Florida Department of Environmental Protection (DEP) staff collected five HAB response samples. Dominant algal taxa and cyanotoxin results follow each waterbody name.

Lake Weir – Eatons Beach: Botryococcus braunii; no cyanotoxins detected.

Gee Creek – Murphy Rd: No dominant algal taxon; no cyanotoxins detected.

Lake Rowena – near NE corner: Microcystis aeruginosa; trace level [0.52 parts per billion (ppb)] of microcystins were detected.

Lake Marian – Boat Ramp: Microcystis aeruginosa; microcystins were estimated to be 3.0 ppb.

Blanton Lake – South Lobe: Microcystis aeruginosa and Microcystis wesenbergii were co-dominant; 9.0 ppb microcystins detected.

On 11/13 – 11/15, South Florida Water Management District staff collected 10 HAB routine samples. Lake Okeechobee stations S308C (lakeside), KISSR0.0, LZ2, L005, POLESOUT, CLV10A, PALMOUT, LZ30 and RITTAE2 had no dominant algal taxon and no cyanotoxins detected. The C44 Canal – S308C sample had no dominant algal taxon and a trace level (0.26 ppb) of microcystins was detected.

Last Week

On 11/8, DEP staff collected a harmful algal bloom (HAB) response sample at Lake Drawdy – S Shore. The sample was dominated by Microcystis aeruginosa and microcystins were estimated to be 2.3 ppb.

On 11/8, St. Johns River Water Management District (SJRWMD) collected five HAB routine samples and one HAB response sample. Dominant algal taxa and cyanotoxin results follow each waterbody name.

Lake George – Center: Aphanizomenon flosaquae and Cylindrospermopsis raciborskii were co-dominant; no cyanotoxins were detected.

Crescent Lake – mouth of Dunns Creek: No dominant algal taxon; no cyanotoxins detected.

Crescent lake – mouth of Haw Creek: Microcystis aeruginosa; no cyanotoxins detected.

Results for completed analyses are available at FloridaDEP.gov/AlgalBloom

Blue-green algae field test results

blue-green algae blue green 12 8 Blue-green algae update
The blue dots represent samples taken in the past week. The green dots represent tests over the past 30 days. For an interactive version of this map, which allows you to zoom in for test results in specific areas for the past 90 days, click on this map or go to floridadep.gov/AlgalBloom

blue-green algae
Blue-green algae bloom. (Photo courtesy St. Johns River Water Management District.)

Blue-Green Algae statewide dashboard — LIVE map prepared by the Florida Dept of Environmental Protection

More from Florida Rambler: The Florida Red Tide Report


Contributing factors to both red tide and blue-green algae.

blue-green algae site 1web final algae red tide inforgraphic Blue-green algae update
Contributing factors to both red tide and blue-green algae. (Florida Audubon)

Blue-green algae

In water bodies with blue-green algae, if people or animals splash or if boats create wakes, the cyanotoxins in the algae can release into the air. The toxins mix with water droplets and spray—that’s how people and animals can inhale the toxin. These toxins can’t pass through your skin easily so swallowing large amounts of contaminated water is what causes illness. This algae is blue, bright green, brown or red, and can have a strong odor like rotting plants. Pets can become sick from blue-green algae so keep them out of those areas and away from contaminated marine animals and fish.

SYMPTOMS? Stay away from blue-green algae.  For some people, blue-green algae can cause rashes, stomach cramps, nausea, diarrhea and vomiting. People who are very sensitive to smells can have respiratory irritation. Sometimes, high exposures of toxin can affect the liver and nervous system.
If you come into contact with blue-green algae, get out of the area and wash off with soap and water. See your doctor if you think blue-green algae has made you sick.

CONTAMINATED WATER. Water from areas with blue-green algae can make animals and people sick—stay away from these areas.

SWIMMING. Don’t swim in or around blue-green algae.

BLUE-GREEN ALGAE AND FISH.  Fish tested from water with blue-green algae show that cyanotoxins don’t accumulate much in the edible parts — muscle or fillet — of fish, but can in other organs. Rinse fish fillets with tap or bottled water. Throw out guts. Cook fish well.

blue-green algae
Blue-green algae update 7

This article is original, produced exclusively for our readers and protected by U.S. Copyright law. Any use or re-publication without written permission is against the law.

This page contains affiliate links from which we may earn a small commission when you make a purchase. This revenue supports our efforts to produced original, unbiased content for your enjoyment.



This site uses Akismet to reduce spam. Learn how your comment data is processed.

This site uses Akismet to reduce spam. Learn how your comment data is processed.