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imate methods. However, analysis showed that the lOa-year flood plains for Tributary 1 and Tributary 2 were consistently less than 200 feet wide within the unincorporated areas of Moffat County. Therefore, the area was designated a zone of minimal flood hazards. 2.2 Community Description Moffat County, the second largest county in Colorado, is located in the northwestern corner of the state and contains an area of approximately 4760 square miles. The City of Craig is located in the eastern portion of Moffat County and is both the largest city in the county and the county seat. Moffat County was created by a division of Routt County in 1911. Moffat County is bordered by Sweetwater and Carbon Counties, Wyoming, to the north; Daggett and Uintah Counties, Utah, to the west; Rio Blanco County, Colorado, to the south; and Routt County, Colorado, to the east. The Ute Indians were the earliest residents of western Colorado. Settlement did not occur in northwestern Colorado until the nomadic Ute Indians were permanently relocated in Utah in 1881. Ranching (cattle and sheep) and energy production (coal, natural gas, and oil) comprise the major economic base for Moffat County with energy production rapidly taking the lead. The estimated county population in 1976 was 10,000 (Reference 1). Between 1976 and 1979, the Craig area alone experienced a population increase of approximately 5600. This rate of increase is expected to continue because it is an energy-impacted area. Yampa River, tributary to Colorado River via Green River, has its headwaters in the Elkhead Mountains to the north, the Park Range on the east, and the White River Plateau on the south and west. The watershed areas at the upstream and downstream limits of detailed study are approximately 1873 and 2150 square miles, respectively. The drainage basin of Yampa River drops from an elevation of approximately 12,500 feet at its headwaters to 6,150 feet at the downstream limit of study. The average slope upstream of this study is approximately 1.1 percent. The average slope for the 7-mile reach in this study is approximately 0.11 percent. Fortification Creek has its headwaters in the Elkhead Mountains in Routt National Forest, approximately 20 miles north of the City of Craig. Fortification Creek flows from its origin near Black Mountain southerly to its confluence with Yampa River approx- imately 0.5 mile south of the southern corporate limits of Craig. The areas drained by Fortification Creek at the mouth and upstream limits of detailed study are approximately 258 and 220 square miles, respectively. The drainage basin of Fortification Creek drops fram an elevation of 10,800 feet at its headwaters to 6,170 feet at its confluence with Yampa River. The average slope through the study area is approximately 8 feet per mile, or 0.15 percent. 4