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In some locations, towering cliffs constitute the transition from river level to high forested mesas and mountains. Land bordering the broad river valleys generally rises in benches cut by narrow tributary valleys. All streams in Garfield County are direct or indirect tributaries to the Colorado River, the main stem of which traverses the south- central and southeastern sections of the county on a west-south- westerly course. In general, East and West Salt Creeks drain the far western portion of the county; Roan, Parachute, Rifle, Main Elk Creeks, and a number of other smaller creek systems, all flowing southerly, drain the west-central, central, and northeastern portions of the county. The Roaring Fork River is the principal tributary to the Colorado River in the county, but, flowing northwesterly, it drains only the southeastern corner of the county. Garfield, Divide, Mamm, and Beaver Creeks, all flowing northerly, drain most of the southeastern portion of the county. Drainage from the most north- eastern sector of the county is northwesterly to the system of the White River, which is tributary to the Colorado River via the Green River. The tributary stream systems show markedly dendritic patterns, and the streamways are steep and well-defined. Average stream gradients on the watercourses studied by detailed methods ranged from 10 to 15 feet per mile on the Colorado River, from 25 to 40 feet per mile on the Roaring Fork River, and are 100 and 145 feet per mile on Cattle and Alkali Creeks, respectively. Gradient:s on the tributary water- course segments studied by approximate met:hods range from 100 feet per mile, on East Elk Creek, to 800 feet per mile on the Glenwood Washes. Climate in Garfield County is characterized by cool summers and moderately severe winters, especially in t:he mountainous northeast corner. Pronounced climatic variations occur within relatively short distances due to dramatically varying topography. Character- istically, great temperature changes occur from summer to winter, and local weather conditions may change rapidly due to movement of storm systems from west to east through the region. Precipitation is directly influenced by elevation with the river valleys receiving from 10 to 15 inches and the high, mountainous northeastern areas receiving from 30 to 40 or more inches annually. Most wintertime precipitation occurs as snow and a deep snowpack normally accumu- lates. In the study area, average snowfall varies from approxi- mately 40 inches at Rifle to approximately 70 inches at Glenwood Springs. Snowpack normally begins to accumulate in late October, and snowmelt' begins in late April.and cont:inues into June or early July. General rain may occur over large areas of the county from late spring through late fall, and convect:ive type cloudburst storms occur in summer. The largest amounts of precipitation usually occur from January through April and in August. In river valley areas, 5 ~. r ~ . c ~ . -~