Calif. city brings back controversial tactic to clean up stinky beach

The city of San Diego is bringing back a controversial technique to rid its award-winning beach of a potent smell of animal waste. But not everyone in the area welcomes the move.

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The San Diego Parks and Recreation Department filed for a permit to begin spraying “Bioactive Odor Counteractant and Cleaner” on 2,180 square feet of the La Jolla Coastal Bluffs above the cove. City spokesperson Benny Cartwright told the San Diego Union-Tribune that the solution, a water-based blend of bacteria and surfactant “similar to those in household soaps,” is diluted and then sprayed to mask the smell of bird guano and sea lion waste caused by “high ammonia levels and harmful bacteria.”

Spraying in the area has been intermittent since 2016. Bob Evans, president of La Jolla Parks and Beaches, told SFGATE that complaints from nearby restaurants and residents likely prompted the resumption of mitigation efforts, and he’s grateful they’ll continue. 

“The stench is increasingly becoming more unbearable as one visits the area,” he said. “Our main concern was for the health and well-being of the marine wildlife, along with the risk of fecal runoff into the Cove and further polluting the marine protected area for beachgoers and recreational users.”

However, environmentalists in the area are concerned about the chemical’s impact on the environment. Lesley Handa, an ornithologist with the San Diego Bird Alliance, told SFGATE that the chemicals could have detrimental effects on the area’s wildlife.

 “We’re also concerned about the chemicals,” Handa said. “If the birds are walking in the area and they get the chemicals on their fur or feet during breeding. Because then they’ll go back to the nest, and since the egg shells are porous, all kinds of chemicals can be absorbed through the eggshells and interrupt the development of the eggs.”

Recreational users are also concerned about the spray’s use. At a June 4 meeting, local swimmer Eric Fletcher told the La Jolla Planning Association that the chemical could have concerning impacts for humans as well as wildlife.

“While some feel frustration with the odor [at La Jolla Cove] … putting a chemical and biological cocktail directly over our marine protected area is a dangerous and short-sighted mistake,” Fletcher said at the meeting, the San Diego Union-Tribune reported.

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As SFGATE previously reported, the San Diego Regional Water Quality Control Board discontinued the previous spraying program in 2023. Handa said her organization had advocated for that decision at the time over environmental concerns. In 2025, after looking over the reports provided by the city, the board declined to further regulate the process, opening the door for the city to resume spraying. 

In 2013, the city of San Diego said the process was a success after a previous application of spray, and  last year, the San Diego Regional Water Quality Control Board said the solution “does not negatively affect the habitat, wildlife, nor public enjoyment.” Handa, though, warns reports of effectiveness aren’t conclusive and that evaluations of a remaining smell are “subjective.”

“They have someone go out before they spray and sniff the air, then do the same afterward,” she said. “Some reports showed no difference before and after spraying, essentially indicating that it wasn’t doing anything. The city hasn’t done their work investigating the impacts or how to properly address this issue.”