Zion National Park is one of the natural wonders of the country, if not the world. In eastern Utah, the park is the 10th most-visited national park according to the National Park Service (NPS) and has struggled with constant overcrowding during the pandemic as many hikers flock in to squeeze onto one hiking trail: the Narrows.
The Narrows, aptly named, are the narrowest part of Zion Canyon. Hiking involves sloshing through the Virgin River, which is surrounded on both sides by huge rock walls.
But a few weeks ago, the park was forced to warn visitors about the Narrows along with another popular hike due to the spread of toxic bacteria in the park’s waterways.
In a statement, the NPS wrote, “Toxin-producing cyanobacteria have been discovered in the North Fork of the Virgin River and will remain in a warning notice.” It added, “During warning and health warnings, recreation seekers should avoid primary contact activities such as swimming or head immersion.” . With hazard warnings, recreational users should consider avoiding any direct contact with the water.”
This isn’t the first national park or national recreation area to address a water issue. Earlier this year, 202 visitors to the Grand Canyon contracted norovirus, which lived in the river’s tepid waters, and the Everglades did consistently fought with algal blooms, also known as red tides.
And even more surprisingly, this isn’t the first time bacteria have forced the Narrows to close. Two years ago, a dog died within an hour after swimming in the river and “snapping” at algae growing on the rocks. It was unable to walk and had seizures before its death, McClatchy News previously reported.
dr Kate Fickas, an aquatic biologist who worked with the US Geological Service in Zion two years ago when it first surfaced but is now focusing on South Dakota, said they were initially puzzled as to what caused the dog’s death.
“Often dogs just drink water too quickly, so we thought that was it,” she said.
However, after testing, they found the water contained cyanobacteria, commonly known as blue-green algae, exactly the same results the park discovered just a few weeks ago.
It’s not entirely uncommon. At higher temperatures, dangerous blue-green algae blooms sprout across the country. Take the Great Lakes, for example, where harmful algal blooms are commonplace. earlier this year, The new scientist reported that harmful algal blooms are becoming more common around the world.
Conservationists are concerned, arguing that the sheer number of national parks with damaged water sources leaves many questions unanswered. “More than half of national parks have water bodies that are considered impaired under the Clean Water Act,” Sarah Gaines Barmeyer, associate vice president for conservation programs at the National Parks Conservation Association, told The National Park Traveler, citing pollution caused by outside of the parks comes a major cause of water quality degradation.
However, there are a few things that make the algae in Zion a stranger case than most. The first is that algal blooms are most common in lakes, which are large stagnant bodies of water; but in this case, an algal bloom occurred in a river.
“Algal blooms don’t often happen in rivers,” says Fickas, adding that “they especially don’t happen in pristine rivers.”
One of the biggest causes of algal blooms is fertilizer runoff in nearby cities. If a large body of water doesn’t disperse these organisms through movement, they accumulate and that’s when you get blooms. This is not possible in Zion, so scientists knew that these algae were a little outside the norm.
“So we started to suspect that the algae were benthic,” Fickas said. Benthic cyanobacteria differ from typical algae in that they live closer to the bottom of the body of water rather than floating on the surface. It also implies that the algae have always been a part of the flow, they just haven’t flourished or been discovered and have historically become a source of health concerns.
Scientists have a few theories as to what caused them to bloom two years ago and a few weeks ago, although not much research has been done on the subject.
“An increase in water temperature would theoretically be problematic,” says Dr. Don Bryant, Professor Emeritus of Biotechnology at Pennsylvania State University. “This problem would be greatest in the summer and any drought season that is now of course ongoing in the West.”
Another theory, the park says, is that high-flow events could trigger rapid regrowth. A spokesman for Zion said: “National Park Service scientists have observed that flood events (such as spring snowmelt or flash floods) wash away cyanobacteria. After high flow events, park scientists have observed regrowth of cyanobacteria over the following weeks and months.”
But of course, identifying the cause of the bacteria is only half the battle. And while Bryant says it’s likely difficult to get rid of the bacteria because they’re part of the river’s natural flora, the National Park Service is instead turning its attention to ongoing sampling and testing, as well as alerting the public through various meanings.
In a statement to The Daily Beast, a Zion National Park spokesman outlined their efforts.
“In partnership with the Utah Department of Environmental Quality (Utah DEQ) and the Utah Department of Health & Human Services (Utah DHHS), we are issuing health advisories so visitors can make informed decisions about recreation in the park. We share updates about cyanobacteria on our park website, on social media posts, and in person at park visitor centers, on hiking trails, and in conversations with rangers. In all of these updates, we are reminding visitors not to drink or filter water from the North Fork of the Virgin River, La Verkin Creek or North Creek.”
But Bryant doesn’t think Recreators should worry too much. At least not yet. “One of the more interesting things to think about,” Bryant said, “is that a lot of the bacteria that we’re finding have always been there. We’ve only gotten more conscientious about testing them and telling people where it’s safe to swim.”
“I’ll put it that way,” Bryant continued. “I grew up swimming in lakes and ponds and I don’t think that’s changed much. But would I swim in it today if I knew what I know now? Absolutely not.”