SCDES Issues Recreational Water Watch for Lake Hartwell in Anderson County 

FOR IMMEDIATE RELEASE:
April 30, 2025  *UPDATED May 1, 2025*

COLUMBIA, S.C. — The South Carolina Department of Environmental Services (SCDES) today issued a Recreational Water Watch for the entirety of Lake Hartwell in Anderson County after identifying the presence of a harmful algal bloom (HAB). 

SCDES was notified of a potential HAB by multiple residents of Lake Hartwell, prompting staff to collect samples from three lake locations near Brooks Drive, Gordon Road, and Whitfield Road in Anderson County on April 29. SCDES received additional notifications on April 30 that residents spotted the HAB in other areas of the lake.    

Cyanobacteria (blue-green algae) capable of producing cyanotoxins were observed in each of the samples collected. These samples were then analyzed for the presence of two cyanotoxins: cylindrospermopsin and microcystins. Concentrations of cylindrospermopsin were below the analytical detection limit in all three samples. Microcystins were detected in two of the three samples but were below the recreational standard of 8 micrograms per liter (µg/L).  

While cyanotoxin concentrations associated with this HAB are low, it is recommended to avoid contact with the water and to keep pets and animals from swimming or drinking from the lake until the bloom has subsided. 

UPDATED RECOMMENDATION (May 1, 2025): While cyanotoxin concentrations associated with this HAB are low, current recommendations are to avoid direct contact with Lake Hartwell water in areas where the HAB is observed or expected and to keep pets and animals from swimming or drinking from the lake in these areas until the bloom has subsided.

SCDES has been coordinating and communicating with Anderson Regional Joint Water System, Pioneer Rural Water District, U.S. Army Corps of Engineers, and representatives from neighboring Georgia.  

Harmful algal blooms (HABs) are a common occurrence in natural bodies of water, most likely to occur in South Carolina in late spring to early fall when water temperatures are warmer and there is increased sunlight. They can persist for several weeks. These blooms can look like bright green spilled paint or blue-green discoloration of the water. With cooler temperatures, heavy winds, and rain, these blooms may begin to break up and die off.  

For more information, contact SCDES’s Bureau of Water at 803-898-8374. If calling after hours, please 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. 

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