Discusses geologic control of supply and water quality in the mountainous part of Jefferson County. Includes general geology, water resources, chemical quality of surface water and groundwater, factors influencing water quality, water management problems and alternatives, graphs and tables of water-quality data. 51 pages. 42 figures. 8 tables. Digital PDF download. B-36D
This publication documents the occurrence of groundwater and the suitability of the environment for on-lot sewage treatment facilities in the approximate western one-half of Jefferson County. It has long been recognized that if on-lot sewage treatment facilities are not installed in a favorable geologic environment the effluent can cause pollution of surface water and groundwater. Hydrologic investigations in a 300-square-mile (7SO-square-kilometre) area in the mountains of Jefferson County, Colo., indicate that the chemical and biological quality of the water is being degraded, especially in the more densely populated locales. Chemical and bacteriological tests were performed on water samples collected from about 800 wells and springs; drinking-water standards recommended by the Colorado Department of Health were exceeded for coliform bacteria in 20 percent of the samples and for nitrate concentration in 5 percent of the samples. Twenty-five streams were tested seasonally; they almost always contained some coliform and fecal-coliform bacteria, but are seriously contaminated only locally.