Cooler temperatures seem to have finally subdued Stockton’s stinky algae monster for 2016, but an expert warned the Delta Protection Commission this week that, in general, toxic blooms are getting worse.

In 2014, a bloom at Franks Tract in the central Delta persisted for eight months — twice as long as scientists had noted in any previous year, said Peggy Lehman, a scientist with the state Department of Fish and Wildlife.

It is possible that once-seasonal algae blooms in the Delta could survive all year in the future, she said.

Low stream flows have a lot to do with the emerging problem. So do average summertime temperatures, which have been warmer than normal for several years. The algae also thrive on nutrients that drain from farmers’ fields, storm drains and treated city wastewater.

Blooms have been spotted along the San Joaquin River between Vernalis and Antioch, and on the Sacramento River near Brannan Island. In the south Delta, Discovery Bay suffered an especially severe case this year.

“It does move throughout the Delta,” Lehman told the commission.

And that makes testing for the toxic variety — Microcystis, often called “blue-green algae” though it is technically bacteria — more difficult.

“We can’t afford to run tests all over the Delta,” said Stockton attorney Dante Nomellini, who sits on the commission. "I don’t think anybody is testing for this on a broad scale ... I’m a little bit reluctant to teach my grandchildren how to water ski in the Delta."

Local public health agencies have issued warnings periodically and put up signs, but it’s hard to be certain, in any one place and at any one time, how dangerous the algae might be. Microcystis, first spotted in the Delta in 1999, has been linked to liver cancer in humans and wildlife. Dogs are vulnerable if they lick their fur after swimming in the water. The bacteria also disrupts the food chain and can harm imperiled fish such as baby Delta smelt and salmon.

It’s unclear how to control Microcystis on a Delta-wide scale, Lehman said. In small places, aerators that stir the surface of the water may help, though the bubblers at the Stockton waterfront didn’t appear to make much difference this year.

Barbara Barrigan-Parrilla, director of Stockton-based Restore the Delta, told commissioners that improved public outreach is needed, particularly to non-English speakers.

“We have to have signs when there are toxic algal blooms, in multiple languages,” she said.

Commissioner Oscar Villegas, a Yolo County supervisor, asked the staff of the small state agency to look at some ways to “elevate awareness” in the future.

— Contact reporter Alex Breitler at (209) 546-8295 or Follow him at and on Twitter @alexbreitler.