Harmful algal blooms have overtaken Utah Lake, and officials are asking all swimmers and waders, including dogs, to stay out of the water, the state announced Wednesday.
As of Thursday at 1:30 p.m., all 16 Department of Environmental Quality monitoring locations in Utah Lake were under a “health watch,” a lower level of advisory. However, department spokesperson Ginger Zamora said that officials anticipated raising those watches to “warning advisories” later in the day.
Under a “warning advisory,” officials urge people not to drink or otherwise come in contact with the water, meaning they also advise against such activities as water skiing or riding personal watercraft like a Jet Ski.
(Chris Samuels | The Salt Lake Tribune) Paddle boarders at Utah Lake at American Fork, Thursday, July 31, 2025.
Officials also warn against paddling in areas with algae. Fishing and boating remain OK, but the department says anglers should clean their fish well and discard the skin and guts.
The Utah Lake Authority learned of the likelihood of harmful blooms on Monday, and received further confirmation Wednesday before alerting the public of the lake-wide bloom.
Utah Lake — along with many other lakes in Utah and the United States — has struggled with harmful algae for years because of its shallow waters and high phosphorus levels.
Phosphorus feeds algae, and the green, plant-like organism thrives in Utah Lake’s relatively warm waters. Such algal blooms have plagued the lake often — including last year. A dog reportedly died after walking along the shoreline during a harmful algal bloom as recently as 2023, though it’s unclear if the toxic algae caused the dog’s death.
(Chris Samuels | The Salt Lake Tribune) Algae can be seen on the shore of Utah Lake at American Fork, Thursday, July 31, 2025.
This spring, the Utah Lake Authority launched a campaign to lure recreationists to the lake. The campaigned touted the millions that had been spent to clear pollution and invasive species, and that harmful algal blooms were down as a result.
Regardless of those interventions, authority spokesperson Kelly Cannon-O’Day said the lake will still experience harmful algal blooms occasionally. She said a lake-wide bloom, like what is occurring now, happens about once a year.
“We continue to do everything we can do to eliminate them,” Cannon-O’Day said.
She said a barge has been deployed on the lake that sucks up the blooms like a vacuum, and efforts to remove non-native carp and plant species continue.
Carp, she said, are an issue because they root around in the lake bed, kicking up its phosphorus and nitrogen-rich sediments that then feed the algae. Native plants will also better filter those nutrients so they don’t end up in the lake.
A news release from the authority said officials have seen an overall 50% reduction in harmful algal blooms at Utah Lake since 2019.
“[Harmful algal blooms] are an unfortunate, but natural part of lake life that require some temporary adjustments for avid recreators,” Luke Peterson, executive director of the Utah Lake Authority, said in a written statement. “It’s like the need for precaution in Utah’s ski country during avalanche season, or in red rock country during flash flood season.”
For updates on water quality and harmful algal blooms, visit the Department of Environmental Quality’s recreational water monitoring website.