Hydrology of area 58, northern Great Plains and Rocky Mountain coal provinces, Colorado and Utah

Abstract

The topics encompass the complete physical and hydrologic setting of Area 58, located primarily in west-central Colorado in the Southern Rocky Mountain and Colorado Plateau physiographic provinces. The headwaters of the Colorado and most of its tributaries originate in the mountains forming the eastern boundary of the area. Precipitation in the mountains can exceed 40 in annually, most of it as snow. Most of the runoff then is a result of snow melting in the spring. Surface water is the principal source of water supplies in the area, and irrigation is the major water use. Groundwater supplies are mainly from wells completed in alluvium or fractured bedrock. All coal mines in the basin but one are underground. Surface water quality is best in the mountains. Dissolved solids concentrations in the Colorado River increase an average of 647 mg/L as it flows through the area. The causes of this increase are nearly equally divided between natural sources and irrigation activities in the sedimentary basins. The climate in these basins is semi-arid, and the soils are not adequately leached. Concentrations of several major elements and trace elements in the groundwater can be large enough to limit water uses. Among those elements exceedingmore » recommended or required standards for use are calcium, chromium, iron, manganese, and lead. 166 refs., 39 figs., 2 tabs.« less