VALLEY, Ala. (WRBL) – A warning from the Chattahoochee Riverkeepers to tread carefully when recreating along Lake Harding in Alabama and Georgia. Harmful Algal Blooms (HABs) are occurring in warm, shallow portions of the lake, producing toxins that can hurt people, animals, fish, birds, and other wildlife.

Ashley Desensi with Chattahoochee Riverkeepers has tracked Harmful Algal Blooms or HABs for nearly three years.HABs are created when high amounts of naturally occurring cyanobacteria (also called blue-green algae) grow out of control and produce cyanotoxins that can harm animal and human health. Cyanotoxins can cause human and animal illness through skin contact, ingestion, or inhalation.

“The algal are visible when it does bloom, and it will form a layer on top of the water that is like a scummy, green color. Sometimes it is lime green,” said Desensi.

If humans touch, ingest or inhale it, they can get skin rashes, GI upsets, and other illnesses. Typically, humans are okay. However, animals can get severely ill. In 2021, the Chattahoochee Riverkeepers documented the first suspected animal death due to a HAB on the main stem of the Chattahoochee River in Bull Sluice Lake along the Gold Branch Trail.

“If you have animals, especially dogs, you want to keep them away from the water; if you are at the lake, bring water for them to drink. Please do not drink the water and do not let them get in and then groom themselves. Dogs are very sensitive to this, and this alga can be very toxic to them,” said Desensi.

Scientists predict climate change and increasing nutrient pollution like agriculture and fertilizer runoff, septic and sewage issues may increase harmful blooms. In addition, increased rainfall can deliver excess nutrients to waterways, feeding the cyanobacteria and causing blooms. Also, warmer, slower-moving water can promote the growth of cyanobacteria. Most conditions along the Chattahoochee River (cold water, fast current) prevent HABs from becoming a problem locally. However, in stagnant or still water on lakes and reservoirs, cyanobacteria can bloom to problematic levels.

The Chattahoochee Riverkeepers is a non-profit group with the mission to educate, advocate and secure the protection and stewardship of the Chattahoochee River, including its lakes, tributaries, and watershed, to restore and conserve their ecological health for the people and wildlife that depend on the river system and in recognition of the critical ecosystem functions provided throughout the region and planet.

“So always avoid areas where it is actively blooming. If you are going to recreate on the lake, go out into the middle, those areas are usually fine,” said Desensi.

If you see visual signs of bloom, suspect pollutants, or environmental issues in a waterway, please contact CRK via the hotline below or call (404) 352-9828. Reports should also be made to the proper state authorities. For Alabama complaints, please report to the Alabama Department of Environmental Management. For Georgia complaints, please write to Georgia Environmental Protection Division by emailing