 The USGS operated two stream gauges on San Juan Creek in the city of San Juan Capistrano, one from 1929 to 1969 and the second from 1970 to 1984. For the former gauge, the highest recorded peak flow during that period was 22,400 cubic feet per second (630 m3 / s) per second on 25 February 1969, with a gauge height of 5.6 feet (1.7 m). The second highest peak flow during that period was 13,000 cubic feet per second (370 m3 / s) on 2 March 1938, presumably at the peak of the Los Angeles Flood of 1938. For the more recent stream gauge, the highest recorded flow was 14,700 cubic feet per second (420 m3 / s) on 4 March 1978, gauge height 17 feet (5.2 m). The second highest flow was 11,700 cubic feet per second (330 m3 / s) on 20 February 1980, gauge height 15.43 feet (4.70 m). The highest flow recorded on San Juan Creek of all time, however, was not by a USGS stream gauge; the flow of 33,650 cubic feet per second (953 m3 / s) was recorded on 11 January 2005.
