An evaluation of the water quality aspects germane to the spillage of hazardous polluting substances is developed. Emphasis is placed on definition and classification of chemical materials; the nature of the sources of spillage and past experience; and analysis of the relative threat to water quality offered by such substances; a review of presently available detection, control, and removal technology; relationship to water quality standards; and the relevant administrative, enforcement, and cost recovery aspects. Over 800 chemical substances were evaluated as to their annual production and transport quantities, their critical concentration in the aquatic environment resulting in water quality impairment for the several beneficial water uses, detection limits (both field and laboratory), and the control and removal methods presently available or potentially practicable. Over 250 chemicals and compounds, generally those in large scale production and utilization, are priority ranked in order of relative threat to water quality in terms of annual production/sales, intrinsic hazard to water quality, transport mode, and past statistical accident frequency. Recommendations are presented regarding future research and development efforts aimed at mitigating damage and a consensus of informed parties is presented relating to the need for additional legislation. (Author)