Detailed vertical profiles of salinity, temperature, oxygen, nitrate, phosphate, nitrite, and silicate have been taken on 6 cruises over a 14‐month period in the Santa Barbara basin. In May 1970, during a period of intense upwelling, the temperature, oxygen, and nitrate content of the basin water from the sill (475 m) to the bottom (580 m) showed significant changes from their normal conditions: the oxygen content increased from 0.05–0.10 ml/ liter to 0.35–0.43 ml/liter; the nitrate concentration, which previously decreased markedly below the sill due to nitrate reduction showed little nitrate reduction; and the temperature decreased by 0.14–0.19C. The results from 2 subsequent cruises in June and July 1970 kinetically follow the basin water back to its normal conditions. After 2 months the oxygen content had almost returned to normal with a measured average oxygen consumption rate of 1.3 ml liter−1 yr−1, while the water temperature rose at a rate of 0.02–0.04C/ month. These data indicate that the Santa Barbara basin was flushed out with seawater coming over the sill. This first direct evidence for the flushing of any California basin suggests that its oceanography is dynamic and that it is capable of flushing on a shorter time scale than previously thought.