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Table 2.--Peak discharges at selected statiolls fiJr the floods o[March 1938 and January 1969 . [Discharge figures for 1969 are provisional and therefore subject to revision] Stream-gaging station Drainage area (square miles) Peak discharge, in cubic feet per second March 1938 January 1969 East of Los Angeles County East Twin Creek near Arrowhead Springs_____ Waterman Canyon Creek near Arrowhead Springs______ Lytle Creek at Colton_________________ Santa Ana River at Prado Dam____________ 8.8 4.6 172 1,485 3,360 2.350 21.500 100.000 2,300 LI80 14,500 '75,000 Los Angeles County San Gabriel River near Azusa_______________ Los Angeles River at Sepulvcda Dam___________ Arroyo Seco near Pasadena____m _______ Los Angeles River at Long Beach ______ Ballona Creek at Sawtelle Blvd., near Culver City______ 214 158 16.0 832 III 65.700 12,000 8,620 99,000 22,500 48,000 13,800 8,540 101,000 15.600 West of Los Angeles County 251 1,595 188 789 60,000. 165.000 55,000 100,000 Sespe Creek near Fillmore_____________ Santa Clara River at Saticoy___ Ventura River near Ventura_________________ Santa Ynez River near Lompoc_____________ 56,000 120,000 39,200 45,000 llnflow of 75,000 cfs was reduced by storage to outflow of 5,800 cfs. comparing flood magnitudes. West of Los Angeles County peak discharges were greater in 1969, and east of Los Angeles County the 1938 peak discharges were greater. In Los Angeles County itself, the relative magnitude of the two floods varied somewhat randomly, but more commonly the greater peak discharges were those that occurred in 1938. Table 2 lists peak flows for the two floods at selected stations. EFFECT OF FLOOD-CONTROL MEASURES ON FLOOD DAMAGE The various storage and conveyance facilities for flood control--reservoirs, debris basins, improved channels, and storm drains--operated effectively during the January flood, and the B8 damage they prevented has been estimated at $1.2 billion. The flows received by the flood-control reservoirs during the first phase of the storm, January 18-21, were released quickly, and consequently the reservoirs were essentially either empty or at conservation-pool level when the critical second phase of the storm began on January 23. During this second phase, none of the large reservoirs that were built primarily for flood control by the Corps of Engineers were completely filled by the heavy runoff. The other reservoirs in the area have an important water supply and conservation function, and although most of them filled during the storm, many were effective in reducing the magnitude of peak flow. downstream from the reservoirs. The discharge