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through the City of Grand Junction to its confluence with the Colorado River. The natural vegetation of the Grand Valley, w,ere not disturbed by human encroachment, consists of desert shrubs such as winterfat and sagebrush, cottonwood trees, willow trees, and an understory of hardy grasses. Agricultural operations in the valley consist mainly of frui t, vegetable, and lives tock feed crops. Between the elevations of 5,000 and 8,000 feet, the primary drainage area of the Colorado River upstream of Grand Junction, pinon pine, junipert oak, big sagebrush, serviceberry, and Douglas fir trees are prominent. From an elevation of 8,000 feet to timberline (headwaters of the Colorado River], vegetation consists mainly of subalpine fir, aspen, Engelmann's spruce, and lodgepole pine trees. Alpine willow, grasses, and sedges exist above the timberline trees. Vegetation in the Indian Wash watershed is sparse. consisting of greasewood, salt brush, and sagebrush in the foothills and pinon pine, juniper, and hardy grasses at the higher elevations. Valley soils in the Colorado River basin have developed primarily from shale material of sandstone origin, i.e. the Mancos Shale and a Mesaverde sandstone. Around Grand Junction the soils are characteristic of soils 10 desert and semiarid regions. The climate of Grand Junction is classified as arid to semiarid. The mountainous regions around Grand Junction are subject to moderately heavy preclpltation. Elevation greatly influences precipitation amounts. The annual precipitation of Grand Junction averages approximately 8.4 inches (Reference 4), the higher mesas receive from 10 to 20 inches, and the high mountainous regions (headwaters of the Colorado River) average approximately 40 inches. Occurrence of precipitation is extremely variable with a large part of the total concentrated in several months. Late summer convection-type cloudburst storms of small aerial extent and early fall general rain over large areas normally cause August, September, and October to be the wettest months of the year. Most winter precipitation occurs as snow and, in the higher elevations, a deep snowpack generally accumulates. Average snOwfall ranges from approximately 19 inches at Grand Junction to approximately 300 inches in the higher mountainous regions. Snowfall is generally dominated by a few large storms. Snowpack ordinarily begins in late October and snowmelt in late April; snowmelt continues through early July. The temperature extremes at Grand Junction are shown by mean maximums ranging from approximately 380p in January to approximately 940F in July, and by mean minimums ranging from approximately 150F in January to 620F in July. Cooler temperatures prevail in higher mountain areas. Record low and high temperatures are -J40F and 640F for January and 380F and 1110F for July, respectively. 5