In March 1978, the Santa Ana Regional Water Control Board in Southern California (henceforth the Regional Board) faced an emergency situation. Heavy rains that winter wreaked havoc in the form of flash floods, mudslides, and overtopping of local rivers and reservoirs. Particularly alarming was the state of the Stringfellow Acid Pits in an unincorporated area of Riverside County. In 1955 the Regional Board, in conjunction with other county and state agencies, had authorized the creation of Stringfellow in order to meet the growing waste disposal needs of the region’s aerospace-industrial complex.¹ Between 1956 and 1972, the seventeen-acre site received over