New study paints ominous picture of algae blooms

SALEM, Ore. — The words blasted to cellphones around Oregon’s capital city were ominous: “Civil emergency. prepare for action.”

Within half an hour, a second official alert clarified the subject wasn’t impending violence but toxins from an algae bloom, detected in Salem’s water supply.

Across the U.S., reservoirs that supply drinking water and lakes used for recreation are experiencing similar events with growing frequency. The trend represents another impact of global warming and raises looming questions about the effects on human health, researchers say.

“When water bodies warm up earlier and stay warmer longer ... you increase the number of incidents,” said Wayne Carmichael, a retired professor at Wright State University in Fairborn, Ohio, who specializes in the organisms. “That’s just logical, and it’s being borne out.”

Cyanobacteria, the organisms that create the blooms, are present nearly everywhere water is found. They also create a unique class of toxins, the impact of which on humans is only partly understood.

Long linked to animal deaths, high doses of the toxins in humans can cause liver damage and attack the nervous system, but less is known about exposure at lower doses, especially over the long term.

Small studies have linked exposure to liver cancer — one toxin is classified as a carcinogen, and others have pointed to potential links to neurodegenerative disease. But definitively proving those links would require larger studies, said Carmichael, who helped set the first safe exposure standards for the toxins.

“It’s absolutely certain in my mind that warming temperatures are going to end up causing more of these algal blooms,” said Steven Chapra, an environmental engineering professor at Tufts University in Medford, Massachusetts.

Chapra led a team including scientists from the Massachusetts Institute of Technology and the U.S. Environmental Protection Agency in one of the most In September 2017, a catfish could be seen floating to the top of algae-filled waters near Toledo. Long linked to animal deaths, high doses of the toxins in algae can cause liver damage in humans and attack the nervous system.

comprehensive studies of the interplay between global warming and the blooms, published in 2017.

Higher summer temperatures and more frequent heat waves help the organisms. More-frequent droughts also cause reservoirs to be shallower in summer, causing them to warm faster. More intense rainstorms can wash more nutrients from farms where nitrogen and phosphorous-rich fertilizers are used into lakes and reservoirs, Chapra said.

In Utah, a 2016 algae bloom in a recreational-use lake sickened more than 100.

Officials only recently started carefully logging the blooms, but they seem to be becoming more intense, said Ben Holcomb, a biologist for Utah’s environmental agency. “They’re starting earlier, they’re lasting longer, and their peaks seem to be getting bigger,” Holcomb said. “I don’t think any state is isolated.”

In Lake Erie, a major bloom in 2014 caused authorities to warn against drinking tap water in Toledo, cutting off the main water source for more than 400,000 people.

Now, blooms happen every year in Utah and Ohio. Officials in both states say they’ve largely been able to stop them from toxifying drinking water. But the blooms can still sicken people and pets that go in the water, and often hit recreation businesses that depend on lake access.

Other blooms have been logged in recent years in New York, Florida and California.

In Oregon, officials lifted Salem’s drinking water advisory after several days, but then had to re-issue the warning. The water supply serves a population of just over 150,000 in the city, along with residents outside city limits.

Officials also warned that dozens of other water supplies could be vulnerable, and indeed, when workers from the city of Cottage Grove inspected another reservoir, they found a bloom, according to a report by Oregon Public Broadcasting.

Testing for the blooms isn’t required by either federal or state law, officials noted.