The purpose of this study is to assess the impact of septic tank soil-absorption systems on ground-water quality for three areas in Cedar Valley where septic tank soil-absorption systems are typically used for wastewater disposal. These areas have some existing development, but we anticipate that there will be additional development in the future. The Utah Geological Survey evaluated the potential impact of the projected potential development on ground-water quality based on septic-tank-system densities using a mass-balance approach similar to an analysis conducted by Hansen, Allen, and Luce for Heber and Round Valleys, Wasatch County, Utah. The selection of the evaluated areas was made in consultation with local government officials. This study may be used as a model for other evaluations of the impact of proposed subdivision site(s) on ground-water quality and allow planners to more effectively determine appropriate development densities.