In the first half of the twentieth century, most firms sought to reduce emissions, effluents, and other pollution-causing discharges only when it resulted in the recovery of valuable material or decreased the amount of money spent on damage and nuisance suits. However, this did not necessarily mean that engineers and technical managers saw themselves—or the firms that employed them—as polluters. Rather, they assumed that as they made industrial operations more efficient, they would also address pollution concerns. This article illustrates the initial success and ultimate failure of this efficiency-based ethic of self-regulation by examining efforts to eliminate the pollution associated with the disposal of oil field brines. Until the 1950s, it argues, efforts to address problems associated with the disposal of oil field brines reinforced the notion that economic incentives to increase the efficiency of industrial operations overlapped with efforts to fight pollution. However, by the late 1950s, economic incentives proved incapable of encouraging further reductions in brine contamination. Yet pollution concerns remained. Since then, the efficiency-based ethic of self-regulation has gradually been replaced by an ethic that most people—and most firms—now treat as legitimate: reaching consensus on environmental objectives and then regulating pollution-causing discharges to meet those objectives.