CBS Los Angeles, March 3, 2013 (Emphasis Added): Authorities say a foul odor that spurred calls to fire departments throughout the city on Sunday is possibly the result of the large release of methane in the Santa Monica Bay. Santa Monica Fire said in a department statement that they believe the strong odor was caused by a naturally occurring methane leak below the ocean floor. “This morning there was a large release of natural ocean floor methane released in the Santa Monica Bay,” the statement said. [...] Brian Humphrey, a spokesman for the Los Angeles City Fire Department, said the odor was noted inland from the Santa Monica Bay.
KPCC (h/t Anonymous tip), March 3, 2013: Santa Monica fire haz-mat crews detected unusual concentrations of odorless methane gas in the air that they believed to be coming from either a patch of pungent algae or a sulfurous gas-laced methane bubble, said a dispatcher. That may night be the case, however. Sam Atwood, a spokesman for the Air Quality Management District (AQMD), said his agency has not confirmed the Santa Monica Fire Department’s theory.
KTLA, March 4, 2013: Officials say a foul stench in Santa Monica over was probably caused by a large release of methane in the ocean. [...] A Santa Monica fire hazmat team took readings off the coast near San Vicente Blvd., and found methane in the water. [...] Authorities said that recent changes in water temperature may have caused plankton and algae beds to bloom, releasing methane just below the surface. The gas also might have been produced by a geologic event, such as a shift in tectonic plates.
KABC, March 3, 2013: Santa Monica hazmat crews found unusual concentrations of odorless methane gas in the air. Officials believe either a pocket of stinky algae, or a bubble of methane laced with sulfurous gas, surfaced in the ocean.