The feasibility of a lagoon treatment-spray irrigation system for the combined domestic wastes and industrial wastewaters in Muskegon County, Michigan, was investigated in this study. The largest volume of industrial wastewaters are those discharged by a pulp and paper mill. Various aspects of the project were investigated including: (1) sampling and analyses of wastewaters for a variety of parameters, (2) a review of available information concerning the effect of trace elements on soils and crops, (3) laboratory tests of the treatability of the combined wastewaters by lagoon treatment, (4) development of a simulation model to assist in analyzing the volume and water quality aspects of a treated wastewater storage lagoon, (5) soils and groundwater field and office studies regarding the management of groundwater levels to ensure an adequate aerobic treatment zone in the soil as well as to prevent ponding in the site area, and (6) investigations of certain agricultural aspects in using treated wastewaters as spray irrigation water. (Author)