A Rise Of Toxic Algae Blooms

Aug 13, 2019

Aerial photo taken August 4, 2019, shows a large algae bloom in the Chowan River. State officials are warning the public to avoid the bloom, which has tested positive for microcystins.
Credit Environmental Working Group / EWG

Toxic algae are increasingly showing up in lakes across the country. A new study from the Environmental Working Group examines how state and federal agencies monitor microcystins, which are toxins that can form in blue-green algae.

In North Carolina, samples from nearly three dozen bodies of water across the state tested positive for the toxins in monitoring conducted in 2007, 2012, and 2018. Three of last year's samples showed levels above the E.P.A.'s recommended recreational exposure level.

Soren Rundquist is the director of spatial analysis with the Environmental Working Group. He said it's important for the public to know what's in local lakes and rivers.

"If you're just recreating in the water, or if you happen to ingest any of the water, or if your tap water relies on surface water for drinking, there are a variety of health effects that can be associated with ingesting microcystins, from headaches, to diarrhea, to more severe issues with stomach problems," said Rundquist.

Algae blooms tend to peak in the summer months, fed by warm water and sunlight. Heavy rains combined with nutrient run-off from agriculture and landscaping can also feed the algae.  

Rundquist said North Carolina is among 20 states making information about toxic algae blooms available.

"The state of North Carolina is doing a good job of staying out in front of this toxic algal bloom issue, especially in comparison to the rest of the United States," he said.

The state Department of Environmental Quality maintains an online map tracking algal blooms from 2012 through the present. In June, environmental officials warned the public to avoid a toxic bloom in the Chowan River that tested positive for microcystins.

Scientists with the N.C. Sea Grant will host a public information workshop on harmful algae blooms on August 24 in Edenton.