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Drought Driving Toxic Algal Blooms Along Ohio River

U.S. Environmental Protection Agency

Drought-like conditions across the Ohio Valley are producing toxic blue-green algal blooms in patches along the Ohio River stretching from Louisville to West Virginia.

Ohio and Kentucky have released recreational advisories warning people and pets to avoid swimming and wading in areas impacted by the harmful algal blooms, said Greg Youngstrom, environmental scientist at the Ohio River Valley Water Sanitation Commission.

The algal blooms are growing sporadically throughout a 300-mile-long stretch of the river, often appearing as green, paint-like scum on the water's surface.

“Stay out of the algae wherever you see it and make sure your pets don’t get into it,” Youngstrom said.

Blue-green algae can produce a toxin known as microcystin that’s harmful to the liver. When ingested or touched, the toxin can cause stomach pain, nausea, vomiting, numbness and other health effects. Pets are particularly vulnerable.

Researchers observed the highest concentrations of the algae in the river near downtown Cincinnati. The sample was about 125 times higher than the 8 microgram-per-liter advisory threshold in Kentucky, Youngstrom said.

Much of the Ohio Valley is facing a moderate to severe drought. River levels are among the lowest the National Weather Service has seen in the last few years, said meteorologist Kyle Wilkins.

It’s these hot, sunny low-flow conditions driving the growth of harmful algal blooms, a trend that could continue until heavy rains upriver restore water levels.

“When there is no rain, the water slows down in the river. The dams are holding back water to allow for navigation and the river becomes very close to being a series of lakes,” Youngstrom said.

Officials say the blue-green algae can affect the taste and odor of drinking water, but that utilities are well-equipped to treat the water for any ill-effects.

Louisville Water Company began treating the city’s drinking water about six weeks ago to ensure there are no health or quality issues.

“To kind of put it in perspective, [the bloom] can be as big as your pinky, the top of your finger to make 100 million gallons have that musty odor,” said Louisville Water spokeswoman Kelley Dearing Smith.

Louisville is on track to have the driest month ever recorded with only four-hundredths an inch of rain, according to the National Weather Service. At the same time, the city is still four and a half inches above normal rainfall for the year. These conditions are consistent with climate change impacts in Kentucky.

Climate scientists say the frequency of extreme weather events will become more common as the temperature rises. In order to avoid the worst impacts of man-made climate change, the planet needs to drastically reduce its use of fossil fuels in the coming decades.

Per the Kentucky Division of Water, the following is recommended to avoid exposure to harmful algal blooms (HABs):

  • Individuals should avoid direct contact, including swimming, wading, paddling, diving, and water skiing, with affected water that has a visible bloom, unusual color, or algal scum.
  • People who are prone to respiratory allergies or asthma should avoid areas with HABs. Children may be particularly at risk.
  • If contact has been made with water containing blue-green algae, wash off with fresh water. In some cases, skin irritation will appear after prolonged exposure. If symptoms persist, consult your health care provider.
  • If fishing in affected waters, fish fillets (not organs) may be consumed after the fillets have been rinsed in clean, potable water.
  • Prevent pets and livestock from coming into contact with water where HABs are apparent.
Ryan Van Velzer is the Kentucky Public Radio Managing Editor. Email Ryan at rvanvelzer@lpm.org.

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