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of hardy grasses. Agricultural operations in the valley consist maiLl) af fE~it.. .e~et.aBle. aRe lih9st.gek fee@. gr<;?P~ ?et'~9'i?~ elevatlons at ~UUU and tlUUU Leet, the prImary aralnage area or Colorado River upstream of Grand Junction, pinon pine, juniper, oak, big sagebrush, serviceberry, and Douglas fir trees arc pro- minent. From an elevation of 8000 feet to timberline (headwaters of 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. 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 material of shale or sandstone origin; i.e. the Mancos Shale and a Mesaverde sandstone. Around Grand Junction, the soils are characteristic of soils in desert and semiarid regions. The climate of Grand Junction is classified as arid to semiarid. The mountainous regions around Grand Junction are subject to moder- ately heavy precipitation. Elevation greatly influences the precipi- tation amounts. The annual precipitation of Grand Junction averages approximately 8.4 inches (Reference 2), the higher mesas (headwater areas of Indian Wash) receive from 10 to 20 inches, and the high mountainous regions (headwaters of Colorado River) average approxi- mately 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 approxi- mately 300 inches in the higher mountainous regions. Snowfall ismgenerally 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 380F 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 -340F and 640F for January and 380F and 1110F for July, respectively. Both the Colorado River and Indian Wash flood plains are moderately developed with commercial and residential structures. 5