A GIS was designed to integrate Summit County land parcel boundaries, septic system permitting data, geology, soil types, and residential well water quality sample results. This study resulted in multiple ArcInfo coverages for the Summit County Environmental Health Department and the Summit Water Quality Committee to use in planning. This Thesis is available the Department of Earth Resources, Colorado State University, Fort Collins, Colorado. The subsurface hydrologic environment has the primary influences on groundwater movement and hence pollutant migration to the surface water.
Summit County has complex and varied geology and therefore topography and soils.
The actual transmissivities of these formations is not known, but the ranges of hydraulic conductivity, water supply data, and texture descriptions were used to classify the groups. These groups, ranging from highest to lowest transmissivities, are the Quaternary Age alluvium deposits, Tertiary Intrusive crystalline rocks, Shales from Cretaceous Age, the Sedimentary Bedrock, and Metamorphic - Igneous rocks of Tertiary age. Ten unique soil groups were then distinguished manually by these characteristics. Different hydrogeologic units were created from the intersection of the geology and soils coverages. Each hydrogeologic response unit will have a different potential for groundwater pollution due to different hydrologic response, providing an effective unit to describe source areas as well as relative rates of attenuation and travel of nitrate from its source to the surface waters.