San Francisco Baykeeper has been sending up drones to monitor eight sites between Discovery Bay and downtown Stockton, as well as photo-documenting the spread and intensity of HABs from airplanes flown by Lighthawk Conservation Flying. At the same time, volunteers with Restore the Delta have been conducting water quality testing for HABs and the toxins they produce.
“The airplane and drones together allow us to get a really broad geographic understanding of where these neon green HABs are occurring, says Baykeeper’s Jon Rosenfield. “That paired with site specific water quality testing that Restore the Delta is doing allows us to get different spatial scales of analysis of this problem.”
These HABs, which Rosenfield says occur during the late-spring and summer in “really wide areas” of the southern Delta, are formed by cyanobacteria that thrive where high temperatures and slow moving water combine with a nutrient-rich environment, and can pump toxins that are dangerous for people and animals into the water—and possibly the air.
Researchers from the University of North Carolina at Chapel Hill are studying the aerosolization of both the cyanobacteria and their toxins in the Delta. Aerosols are released when bubbles on the water’s surface burst, says UNC’s Haley Plaas. “We’re trying to better understand what environmental conditions might promote a higher release of these toxins into the air,” she says. “Is it something that we need to be concerned about from a human health standpoint? And we know very, very little about how exposure to those toxins in the air might be impacting like human lung health.” Back in North Carolina, Plaas says that her team identified the bacterial DNA of 15 types of cyanobacteria in the air that could be traced to the water. They also found aerosolized particles with diameters of 2.5 microns or smaller increased during the bloom. PM2.5 is regulated by the EPA because particles that size can be drawn deep into the lungs. “While we don’t have a ton of compositional information, we know that something coming off of the blooms is found in association with increased PM2.5.”
Rosenfield notes that although the Central Valley Regional Water Board is also conducting some monitoring, and the California Water Quality Monitoring Council has a portal for HAB reporting, there is no coordinated response to the growing HABs problem, including no water quality standard for HABs. “It’s sort of a ragtag group out there trying to document the existence of the HABs, their duration and their extent as well as their toxicity. Community members are doing what you would expect the government agencies to do.”
Although HABs have been a growing problem in inland waters for years, the summer of 2022 brought them to San Francisco Bay and Oakland’s Lake Merritt as well, killing thousands of fish. The San Francisco Estuary Institute has created a web portal for citizens to report fish kill sightings. CHT
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