For the first time in three years, the city of San Diego requested to spray a bioactive odor counteractant and cleaner (BIOCAAC) on the La Jolla Cove rocks to manage the smell from the marine wildlife waste.
The spray was last applied in 2023 but had to pause applications after the California Regional Water Quality Control Board requested additional information, according to the city.
The spray is a water-based blend of cultures, non-pathogenic bacteria and surfactants manufactured by ARK Environmental Solutions, Inc. in Coronado.
In 2025, the California Regional Water Quality Control Board determined that the application did not require their regulation.
The city voluntarily paused the application of the spray and has since submitted a Coastal Development Permit in April 2026, which is currently under review by the City’s Development Services Department.
Spraying will not resume unless all required approvals are obtained.
The San Diego Water Board said the city communicated its best management practices regarding the spray to prevent harm to people and animals.
If the application is approved, the city plans to dilute the spray with water to accelerate the natural breakdown of organic material, helping reduce odors associated with animal waste, according to the City’s email statement.
The deodorizer is diluted at a 10:1 ratio or 100 gallons of water to 10 gallons of deodorizer, according to a spokesperson from the San Diego Water Board.
“This natural process produces water and carbon dioxide, and the bacteria will become inactive once the treated surface dries,” the city said.
Some of the City’s best practices communicated to the water board were storm drain protection, spraying above the highest high tide, avoiding windy conditions, not spraying when rain is expected and having a biological monitor on site.
The spokesperson said the water board does not expect the deodorizer to enter the ocean and said there is limited information on its potential effect on the water.
Additionally, it is not expected to be harmful to the environment, but it may cause skin sensitization to people if there is direct contact with the concentrate.
However, the spokesperson said there have been concerns from other non-governmental organizations about the harassment and impacts to marine mammals and nesting birds.
Jennifer Leigh Warner, professional wildlife conservation photographer from Experience Wildlife, said La Jolla is one of the most biodiverse places in California and it is essential we protect its habitat.
“Exposure to chemicals could harm their health, affecting reproduction and survival rates,” Leigh Warner said.
She said the purpose of the bright white splatters of guano on the cove rocks is to act as visible navigation for birds looking for safe places to nest along the cliffs.
Leigh Warner also mentioned how La Jolla Cove is home to one of the only mainland California Sea Lion rookeries where pups are born directly on the cove every June.
“The introduction of chemicals could lead to skin irritation or other health issues, especially to pups that are more susceptible to environmental threats,” Leigh Warner said.
Sea lions also play a vital role in nutrient movement in marine ecosystems, and a chemical spray in the coastal waters via runoff can alter the bacteria that fertilize the ocean’s vegetation.
“While addressing the odor problem at La Jolla Cove is important, it is crucial to prioritize the health of the ecosystem and the wildlife that call it home,” Leigh Warner said.
Tourists at La Jolla Cove don’t seem to mind the smell when visiting, as it is the cost of seeing them so close.
“We’re here to see the wildlife,” Nancy, a visitor from Chicago, said. “I can smell it … but honestly, it’s not that bad.”
Northern California resident Jim VanHuysse says he heard about the city wanting to spray the rocks but felt it wasn’t necessary, as it didn’t bother him or his family.
“It’s nature,” VanHuysse said. “We shouldn’t need to alter nature.”
