Lloyd EcoDistrict director Joshua Baker spends many hours each summer organizing a popular Portland event series where people can listen to a live DJ while jumping into the Willamette River from an eastside dock.

The Portland-based climate nonprofit was looking forward to wrapping up its final two events of the season with no hiccups. Then, Baker said the group received a message from a community member who noticed something weird along the dock where the events take place.

“Later that afternoon, I went out just to inspect [and] sort of verify what they suspected,” he said. “And it was clear that conditions were present for an algae bloom around the dock that evening.”

Soon after, the nonprofit announced it would cancel the following events until the Oregon Health Authority confirms whether it’s safe to swim.

“We’ve been doing a lot to restore people’s confidence that the Willamette is a safe and fun place to swim. So when we have to report that there’s an algae bloom in August, it doesn’t feel great,” Baker said.

The Human Access Project — a nonprofit that’s advocated for a more proactive response to the blooms at the Ross Island Lagoon — also cancelled a riverside gathering it hosts on Fridays at Audrey McCall Beach during the summer.

The Oregon Health Authority said in a statement Friday that Oregon Department of Environmental Quality water samples “do not meet the criteria for OHA to issue a recreational advisory.”

“We know the images of the Ross Island bloom are striking and understandably cause concerns that there may be a lot of toxin in the water,” OHA said in the statement.

The agency said Oregon DEQ is sampling multiple sites on the lower Willamette River, where the Human Access Project and Lloyd EcoDistrict noticed signs of the bloom, and that the department will share those results with OHA.

“However, pets are more sensitive than humans, and the present levels are above what is considered safe for pets,” OHA said.

Oregon DEQ did not immediately respond to a request for comment.

The threat to pets — and people, should the bloom become more toxic — prompted Baker to notify the community in the absence of an official warning.

“I realize testing of the algae blooms in the waters takes time,” Baker said. “But we were the ones, and [the] Human Access Project, that was sort of notifying the community that you shouldn’t swim in the water.”

In a press release Friday, Human Access Project director Scott Fogarty encouraged people to watch for signs of the toxin-producing bacteria that can turn blooms harmful, including foul odors, green scum and discolored water.

Warm and stagnant waters allow algae to reproduce into large colonies, which can turn into harmful blooms if they begin producing toxins. Warmer and drier conditions driven by climate change, including low snowpack, can lead to longer and more severe outbreaks.

News Source : https://www.opb.org/article/2026/08/29/large-annual-algae-bloom-prompts-local-groups-to-cancel-events/