16-05-2025
SCDES continues to monitor harmful algal blooms on Lake Hartwell: Water Watch expanded
Heavy rain over the past few days in the Upstate, which can sometimes break up harmful algal blooms, has instead moved or pushed the blooms into different coves within Lake Hartwell.
This shift in location necessitates further monitoring and testing to ensure the safety of the affected areas.
Almost three weeks have passed since the South Carolina Department of Environmental Services identified, surveyed, and collected three samples from several coves in Lake Hartwell to test for harmful algal blooms.
Between May 6 and May 15, officials reported that additional areas in Lake Hartwell were identified as having harmful algal blooms, according to a news release.
Most reports indicate harmful algal blooms are in coves and along the shore.
The South Carolina Department of Environmental Services continues to monitor harmful algal blooms (HAB) on Lake Hartwell.
The Aquatic Science Division team will thoroughly assess the lake and collect an additional round of sampling the week of May 19.
The South Carolina Department of Environmental Services will issue a new update with the latest information and recommendations to the public before Memorial Day weekend.
The South Carolina Department of Environmental Services also works closely with the Anderson Regional Joint Water System, Pioneer Rural Water District, the U.S. Army Corps of Engineers, and representatives from neighboring Georgia.
Harmful algal bloom samples were collected on April 29-30 near Brooks Drive, Gordon Road, and Whitfield Road in Anderson County and analyzed for two cyanotoxins, cylindrospermopsin and microcystin, according to a news release.
On May 6, the department conducted further surveys and collected 16 additional samples to assess whether toxin levels had changed since the harmful algal bloom watch was initially reported on April 30.
Preliminary results indicated that these samples contained cyanobacteria capable of producing harmful cyanotoxins.
Additionally, cindrospermopsin concentrations were below the analytical detection limit in all three samples.
A Recreational Water Watch continues for Lake Hartwell in light of this additional assessment.
The Recreational Health Advisories for Lake Hartwell have established safety thresholds for microcystins and cylindrospermopsin, toxins produced by harmful algal blooms, according to the South Carolina Department of Environmental Services.
The advisory levels are 8 µg/L for microcystins and 15 µg/L for cylindrospermopsin.
Exceeding these levels may pose health risks to humans and animals.
While cyanotoxin concentrations associated with this HAB continue to be low, the lake's Recreational Water Watch remains in effect.
The South Carolina Department of Environmental Services recommends avoiding direct contact with Lake Hartwell water in areas where harmful algal blooms are observed.
It is also advised that pets and animals not swim in or drink from the lake in these areas until the bloom subsides.
As described by the Centers for Disease Control and Prevention, harmful algal blooms may be identified by their appearance, often resembling scum, foam, mats, or paint.
These blooms can alter the water's color into shades of green, blue, brown, or red, producing a foul odor similar to rotten eggs or decaying vegetation.
South Carolina Department of Environmental Services officials recommend keeping pets and animals from swimming in or drinking lake water until the bloom has fully subsided to prevent potential health risks.
According to the South Carolina Department of Environmental Services, if your pet experiences any of the symptoms listed below after coming into contact with a body of water, please consult your veterinarian.
Physical: hypersalivation, weakness, labored breathing, seizures, and other neurologic symptoms
Chemical: elevated liver enzymes, low blood sugar, low protein, abnormal coagulation
Harmful algal blooms (HABs) occur when algae and cyanobacteria, tiny plant-like organisms, overgrow in bodies of water such as rivers, lakes, and oceans, according to a news release.
These blooms are most common in natural water bodies where nutrient levels are elevated, often due to agricultural runoff or wastewater discharges.
This rapid growth is called an algal bloom and can be associated with foam, scum, or thick layers of algae on the surface of water.
Most harmful algal blooms occur in South Carolina in late spring to early fall when water temperatures are warmer and sunlight increases.
Light, temperature, and nutrients significantly influence cyanobacteria's growth and reproduction.
According to the South Carolina Department of Environmental Services, for Harmful Algal Blooms to grow and form, they need the following.
Sunlight
Slow-moving water
Nutrients (nitrogen and phosphorus)
Relatively warm water temperature
Algae blooms can persist for several weeks. However, with cooler temperatures, heavy winds, and rain, they may break up and die off.
It's important to note that nutrient pollution can make algal blooms worse, resulting in more frequent and more severe blooms.
For more information, contact SCDES's Bureau of Water at 803-898-8374. If calling after hours, leave a message that can be returned.
For additional information about harmful algae in South Carolina, visit the SCDES HABs webpage and Algal Bloom Monitoring Map.
Travis Rose covers Anderson County for the Independent Mail. Reach him via email at trose@
This article originally appeared on Greenville News: What to know about Water Watch for harmful algal blooms on Lake Hartwell
