There were 2 periods of "red water" in La Jolla Bay in 1942. In May, discoloration persisted for a week and was caused by Prorocentrum micans; in Sept. it lasted for 3 weeks, caused by Goniaulax polyedra. The populations drifted in from the west and have not been found > 25 miles from the coast. Their sudden appearance has not been satisfactorily explained.