This study examines wastes associated with the onshore exploration and production of crude oil and natural gas in the United States. The objective of this study was to update and enhance the current state of knowledge with regard to oil and gas waste quantities, the potential environmental impact of these wastes, potential methods of treatment, and the costs associated with meeting various degrees of treatment. To meet this objective, the study consisted of three tasks: 1) the development of a Production Environmental Database (PED) for the purpose of assessing current oil and gas waste volumes by state and for investigating the potential environmental impacts associated with current waste disposal practices on a local scale; 2) the evaluation of available and developing technologies for treating produced water waste streams and the identification of unit process configurations; and 3) the evaluation of the costs associated with various degrees of treatment achievable by different treatment configurations. An updated assessment of the annual domestic production volume of drilling waste and produced water by onshore drilling and production activity showed there to be a general decline in the volumes of drilling waste being produced over the period 1985 - 1992 as well as an apparent reduction in the volume of produced water generated since 1986. A 59% reduction in the volume of drilling waste over 1985 levels was estimated. This reduction is tied to a reduction in the amount of drilling activity and, more closely, to a reduction in the amount of drilled footage taking place. Current estimates show that some 150 million barrels of drilling waste and 18.3 billion barrels of produced water are being generated annually. An analysis of the environmental settings surrounding oil and gas activities in 8 Texas counties showed that local conditions can be far different from those described by the EPA in their nationwide study and used in their risk assessment. The evaluation of feasible technologies for the treatment of produced water waste streams was handled in the context of comparing the level of treatment achievable with the associated cost of treatment. Treatment processes were evaluated for the removal of four categories of produced water contaminants: particulate material, volatile organic compounds, absorbable organic compounds, and dissolved inorganic species. Results showed dissolved inorganic species to be the most costly to remove. The potential cost of treating all 18.3 billion barrels of produced water generated in a year amounts to some 15 billion dollars annually.