The effects solid waste disposal sites in and near Iowa located on alluvial systems have upon groundwater quality were studied at Ames, Des Moines, Mason City, and Omaha. The hydrogeologic study was pursued to satisfy four major objectives. The first was to determine the composition and variations in the composition of groundwater affected by leachate flowing from solid waste disposal sites. The second objective was to determine the shape of the contaminated zone of groundwater and the approximate direction and rate of groundwater flow in the vicinity of the landfills. A third objective was to evaluate the effects that precipitation and variations in stream discharge had upon the static water level, the composition of the groundwater, and groundwater movement in the vicinity of the landfills. The fourth was the development of general cases that could be applied to similar hydrogeologic environments.