INTRODUCTION The first offshore oil field in the Gulf of Mexico was developed in the late 1930s and the first production well out of sight of land was completed 12 miles off the Louisiana coast in 1947. By the end of 1982@ approximately 27@000 wells had been drilled in U.S. coastal waters (National Academy of Sciences@ 1983). In 1981@ there was a total of 3843 offshore platforms in operation in U.S. waters@ 3470 of them offshore Louisiana (Offshore@ 1983). Because of the sharp downturn in the price of oil and gas@ there has been a leveling off of offshore exploration and development in U.S. coastal and offshore waters during the last several years. The number of wells drilled on the U.S. outer continental shelf has remained relatively constant with 1151 wells in 1984@ 1166 wells in 1985@ and 1200 wells drilled in 1986 (Minerals Management Service@ 1988). In 1986@ the U.S. outer continental shelf accounted for approximately 12 percent of the total domestic oil production and 23 percent of domestic gas production (Minerals Management Service@ 1988)@ The U.S. Geological Survey has estimated that as much as 33.8 percent of the nation's undiscovered recoverable oil and 28.1 percent of natural gas may lie beneath U.S. coastal and outer continental shelf waters (Kash@ 1983). Reliance on these offshore resources will increase as onshore fossil fuel reservoirs are depleted. This magnitude of exploration for and development of petroleum resources in U.S. coastal and outer continental shelf waters has led to a growing concern that such activities may cause serious long-term damage to the marine environment and the living resources it supports. The focus of this concern in recent years has been on the discharge of used drilling fluids and cuttings to the ocean (Neff@ 1982; Petrazzuolo@ 1983; National Academy of Sciences@ 1983; Neff et al.@ 1987). More recently@ concern has grown about the possible environmental impacts of produced water discharges to the ocean (Middleditch@ 1984; Neff et al.@ 1987).