A massive red tide and thousands of dead fish washing up across shorelines have cast light on a threat to the Bay that’s usually invisible: nutrient pollution.
While nutrients sound like a good thing, excessive phosphorus and nitrogen – combined with warm sunny weather and stagnant water flows – provide ideal conditions for many types of algae to bloom, like the “red tide” that recently spread throughout the Bay.
In July, Baykeeper started getting pollution hotline reports of murky, reddish-brown waters in the East Bay. Agencies confirmed that the bloom was of the algae species Heterosigma akashiwo.
As our field investigators closely monitored, the red tide quickly spread to San Francisco, the Central Bay, and the South Bay. By August, our hotline was receiving reports of unprecedented numbers of dead fish, bat rays, sharks, and other creatures washing up on the Bay’s shores.