West Coast
San Francisco Examiner

CA - Harmful S.F. Bay algal bloom bigger than expected and growing

Sometimes, water issues are best seen from the sky.Thirsty riverbeds. Flooded neighborhoods. And this week, a harmful algal bloom overtaking San Francisco Bay.

That’s why David Houghton, a volunteer pilot with the environmental nonprofit LightHawk fired up the engine on his forest green 1979 Mooney M20K on Wednesday morning and pointed its small propeller skyward.

As soon as the plane bounced to 1,000 feet, there it was: long tendrils of rust-colored water, swirling under the San Mateo Bridge, creeping up to the shoreline near San Francisco Airport, hovering near Hayward, Foster City and Vallejo.

First reported by residents living in houseboats along the Alameda estuary in late July, the bloom, caused by a microscopic marine organism called Heterosigma akashiwo has now fanned out across much of the bay, turning the otherwise blue waters ruddy brown.

Although scientists are still working to construct a comprehensive timeline of the algal bloom, including what caused it and how it spread, data from researchers and the California Department of Public Health confirm that the bloom now spans much of the bay, including north of the Bay Bridge into Marin and Richmond, which has been previously unseen.

“This is the largest and longest lasting red tide on record for San Francisco Bay,” said Jon Rosenfield, a senior scientist at the environmental watchdog Baykeeper. “Something of this magnitude and this duration definitely does not happen every year or even every decade.”

Such blooms are expected to increase with a warming climate, said Eileen White, an executive officer for the State Water Resources Control Board.

Though the cause of any bloom is complex and hinges on various environmental factors, including temperature, tides and wind patterns, experts have also pointed to the heavy nutrient load entering the bay from the nearly 40 storm and wastewater facilities surrounding it.

“The bay is highly enriched for nitrogen and phosphorus,” said Rosenfield, largely due to the wastewater and stormwater that cities like San Francisco dump into it.

It’s an issue that the state water board is paying attention to, said White, adding that events like this may factor into the agency’s future permitting requirements and could include capping the amount of nutrients cities can release in their wastewater.

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