Upper Colorado River Basin Study Unit
The Upper Colorado River Basin encompasses about 17,800 square miles. The primary river, the Colorado River, originates in the mountains of central Colorado and flows about 230 miles southwest into Utah. The basin is composed of two physiographic provinces: the Southern Rocky Mountains and the Colorado Plateau. The topography varies from rugged mountainous regions in the east to high plateaus bordered by steep cliffs along valleys in the west. Because of differences in altitude of about 10,000 feet from east to west, the climate ranges from alpine conditions to semiarid/arid conditions. Precipitation ranges from 40 inches or more per year at high elevations in the eastern part of the basin to less than 10 inches per year at low elevations in the western part of the basin. USGS Circular 1214 explores water quality issues in the Upper Colorado River Basin.