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Algae bloom fish kills prompt new Bay Area wastewater treatment plant requirements costing $11 billion

Toxic algae bloom killing off thousands of fish in Bay Area waters
Toxic algae bloom killing off thousands of fish in Bay Area waters 02:29

Ten years. That's how much time the Bay Area's 37 wastewater treatment plants will have to reduce fertilizer and sewage in their water by 40%. The estimated price tag for the facility upgrades is $11 billion.

The San Francisco Regional Water Quality Control Board plans to adopt the change as part of its new discharge permit requirement beginning June 12. Previous permits did not require reductions, according to Lorien Fono, executive director of the Bay Area Clean Water Agencies, which oversees the region's wastewater treatment plants. She spoke from the Oro Loma Sanitary District in San Lorenzo on Thursday. The facility is considered a model for upgrades.

The regulatory change follows a damaging algae bloom in 2022 and 2023. A brown algae species called Heterosigma akashiwo, which feeds off the nitrogen in wastewater, infected the Bay and damaged aquatic ecosystems.

wastewater treatment
First phases of bacterial wastewater treatment at the Oro Loma Sanitary District in San Lorenzo, Mar. 14, 2024. Ruth Dusseault / Bay City News

"We don't know the extent of fish kill, but thousands of white sturgeon and green sturgeon died, and many thousands of small fish died," said Ian Wren, staff scientist with the environmental group San Francisco Baykeeper.

"Four-to-six-foot dead sturgeon, which the state categorizes as species of special concern, were all over the shoreline. The bloom got so big that all the oxygen in the South Bay was sucked up, none was recorded at many depths for several days," Wren said.

The conditions for that bloom were simply nice weather, he said. The Bay was clearer, and that light penetration helped foster algal blooms.

"It was sunny, not a lot of fog or wind, the Bay was calm," he said.


The hope is that reducing nutrient loads to the bay will reduce the extent of that damage. Wren said conditions improved with similar efforts in Tampa Bay, Florida, and the Chesapeake Bay in the Mid-Atlantic.

"I don't think that anybody believes that we're going to be able to end harmful algae in the Bay," said Fono. "It's a worldwide problem at this point."

Without federal or state grants, the cost will amount to $4,000 per household, which Fono said would be financed by the agency, like a mortgage, and then spread out over time.

In the early 1970s, the federal government distributed funds to build some of the region's first water treatment plants with the passage of the Clean Water Act. Many of those facilities are reaching the end of their usable life right now, Fono said. "It makes sense to incorporate nutrient removal as part of their rebuilds."

Fono said funds could possibly be raised through grants from the U.S. Environmental Protection Agency, but they are hoping the state budget situation improves and they can get state grants.

In San Lorenzo, the Oro Loma Sanitary District got a head start in 2019 when it used bonds to pay for upgrades. Improvements included a recycling system that piped water with some nutrients to feed a nearby golf course. They added biodigesters, which convert the thick stuff into methane that fuels the plant. They also invested in an experimental nature-based solution, the Transforming Shorelines Project, a horizontal levee.

The levee project started in 2015, when Oro Loma partnered with researchers at UC Berkeley to design a 400-by-200-foot green slope. They delivered wastewater through pipes buried deep under the soil. The projects successfully removed waste nutrients, metals and trace contaminants, while providing wildlife habitat up top. As a natural buffer to sea level rise, researchers imagine them happening all around the Bay.

"It's been a successful experiment in that it's inspired other agencies around the Bay Area to follow suit, including Palo Alto," said Fono.

The Oro Loma facility serves a population of about 47,000 in San Lorenzo, Ashland, Cherryland, Fairview, portions of Castro Valley, and parts of Hayward and San Leandro. It averages a flow of 12 million gallons of wastewater each day. Like most of the districts in the state, the wastewater pipes are separate from the stormwater pipe system, which diverts rainwater straight to the Bay.

The facility uses natural bacteria, which eats the sewage until it's nearly clear. Last steps include a shot of bleach to kill the bacteria, followed by another shot of bleach remover. Out it goes, heading north to join the flow from six other facilities that are part of the East Bay Dischargers Authority, a joint powers agency that includes local cities and sanitary districts.

The waste is then piped seven miles out into the Bay from a station in San Leandro. 

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