The South Carolina Department of Environmental Services (SCDES) has released its latest bi-weekly update on Harmful Algal Bloom (HAB) activity in Lake Hartwell. Based on a detailed lake survey conducted on June 3, 2025, the new report outlines continued improvement in many coves and nearshore areas—but also emphasizes the importance of remaining cautious.
In this latest sampling, cyanotoxin microcystin was detected in all 10 testing sites, though at concentrations (maximum 0.89 µg/L) well below the recreational health standard of 8 µg/L. As a result, SCDES has lifted the Recreational Watch for several areas, including:
- Tugaloo River lake arm upstream of I-85
- Seneca River lake arm upstream of West Cherry Road
- Six and Twenty lake arm upstream of Centerville Road
Despite this progress, the Recreational Watch remains in effect for downstream areas. SCDES advises the public to avoid direct contact with lake water in affected zones and to keep pets from swimming or drinking in areas where blooms are visible. Even in areas cleared from the Watch, some residual HAB presence may remain near the shore.
Download the full June 5, 2025 HAB Report (PDF)
Click here to view or download
For questions or background on toxicity levels, swim safety, or HAB behavior, visit des.sc.gov/habs or check out the live Algal Bloom Monitoring Map.
We’ll continue sharing these bi-weekly updates to help the Lake Hartwell community stay safe and aware.
If you want to stay informed on lake conditions, water quality updates, and advocacy efforts year-round, become a member of the Lake Hartwell Association today.