A toxic algae bloom is disrupting Fourth of July weekend recreation at one of the West’s most popular lakes.
National Park Service officials detected the presence of cyanotoxins in the mouth of Lake Powell’s Arizona-based Antelope Canyon.
The lake, which spans 186 miles, is located in the Glen Canyon National Recreation Area. The recreation area takes up 1.25 million acres across Arizona and Utah, and it saw some 5.2 million visitors in 2023.
The level of cyanotoxins detected in the canyon were in concentrations that are “at the high end of safe exposure levels,” the agency wrote in a statement. Cyanotoxins can be harmful to humans and animals. The toxic byproducts of cyanobacterial blooms — also known as blue-green algae — cyanotoxins occur most often in freshwaters.
There are relatively few documented cases of severe human health effects, but exposure to cyanotoxins and cyanobacteria can result in rashes, eye irritation, respiratory symptoms, inflammation of the stomach and intestines, liver and kidney failure, or even death.
Some recent research has found living near bodies of water frequently impacted by the blooms and cyanobacteria toxins may put residents at an increased risk of dying from ALS, the debilitating neurodegenerative disease.
“The most likely pathway to exposure for humans is through accidental ingestion or inhalation during recreational activities in lakes, rivers and bays,” the Environmental Protection Agency explained.
The most common cyanotoxin, microcystin, is a potent liver toxin and possible human carcinogen. People should contact their doctors if they start to exhibit nausea, vomiting, digestive distress, breathing problems, seizure, or unexplained illness.
Cyanotoxins can also kill any pets or livestock that drink the affected waters.
Although recreation on Lake Powell remains open, park officials have told swimmers to stay out of water with an algal bloom and not to boat on scummy water.
“These activities can cause toxins to become airborne, increasing the likelihood you will inhale them,” the Park Service wrote.
They noted other areas of the lake may also contain the toxins.
Harmful algal blooms also affected the recreation area last fall, and are increasingly occurring due to the impacts of climate change and hotter temperatures.
In Michigan, the blooms have long plagued Lake Erie. Because of the warmer waters, Gregory Dick, a professor of biology who leads the University of Michigan’s Cooperative Institute for Great Lakes Research, says the blooms are lasting even longer than before.
This year, the National Oceanic and Atmospheric Administration detected the toxins in Lake Erie earlier than ever before. He noted that a 2022 bloom in Lake Erie persisted into November, which “is rare, if not unprecedented.”
The state has responded by updating is domestic action plan, including measures to reduce nutrient run-off that can lead to the blooms. But, water and air temperatures aren’t falling.
“Warm, still water is the perfect breeding ground for cyanobacteria and the addition of nutrients like nitrogen and phosphorus that enter the lake from outside sources, encourage the growth of algae and bacteria,” the Park Service noted.
