Oil displacement by injection of brines (the waterflood process) entails the surface processing of large quantities of saline waters, creating the potential for pollution of surface waters and shallow freshwater aquifers. Improved waterflooding techniques involve the introduction of surface active agents (detergents), caustics, and organic polymer compounds (particularly polyacrylamide), thus increasing the potential for pollution. It is increased further by the micellar-polymer process, since the micellar solution is a mixture of surfactant, oil, water, and a cosurfactant (usually an alcohol). Enhancement of oil production by thermal methods adds another dimension to the environmental hazards through air pollution from steam generators and the produced fluids. Other field operations, such as drilling and renovation of wells, create local environmental hazards, but these are becoming regional concerns as the search for new oil and the reactivation of old oil fields accelerates. This paper presents the potential pollution hazards of the enhanced oil-recovery processes and the environmental surveillance program being instituted by the Department of Energy (DOE).