The major goals of this program were to develop preliminary survey information on the organophosphorus pesticide industry wastewater streams and to develop analytical methods to monitor levels of organic compounds present in these streams. The identification and quantification of organophosphorus compounds were emphasized, but nonphosphorus chemicals were also included in the survey. A secondary goal of the program was to use the survey information to evaluate the efficiency of various waste treatment processes. The wastewater from five pesticide plants that produced eight organophosphorus pesticides was sampled. The pesticides were: diazinon; methyl parathion; azinphos-methyl and disulfoton; fonofos, phosmet and benulide; and EPN. Samples were taken at pre-, mid- and posttreatment locations. The analytical methodology included extraction and partitioning, gas chromatography with specific element detection, thin-layer chromatography, infrared spectroscopy and gas chromatography/mass spectrometry. Methods and procedures were developed by analysis of (a) distilled water samples fortified with model compounds and (b) an actual wastewater sample from the azinphos-methyl/disulfoton production plant. The 116 compounds identified included organophosphorus pesticides, related organophosphorus esters, organophosphorus acids, volatile organic compounds, thiocarbamate pesticides, triazine herbicides, and miscellaneous extractable process chemicals, by-products, and compounds of unknown origin. The levels of parent pesticides in the final effluents were below 0.005 mg/liter. Oxygen analogs of the pesticides were not a significant degradation product of any of the waste treatment processes. Phosphorothioates and organophosphorus acids were only partially removed by the treatment processes, and were observed the parts per million levels in some final effluents. Phenylphosphonate esters closely related to the parent pesticides were observed in a final effluent sample at parts per billion levels. Volatile organic compounds were effectively removed by the treatment systems with the exception of one totally enclosed system. One effluent which was disposed in an injection well contained over 150 mg/liter organic disulfides, almost 200 mg/liter thiocarbamate pesticides and over 100 mg/liter organophosphorus acids. Recommendations were made regarding further work in treatment system evaluation, synergistic toxicity studies of organophosphorus compounds, analytical mehtod development, and the fate of wastewater in injection well systems.