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Larimer County has grown from a 1970 population of 89,900 to a 2000 population of 251,494 (References 2 and 61). The climate varies from the mountains in the west to the eastern plains. The average annual temperature in the western part of the county is in the lower 400F range, with annual precipitation of approximately 16 inches. The eastern portion of the county has an average temperature of 500F and annual precipitation of approximately 14 inches (Reference 3). The studied section of the Big Thompson River is approximately 41 miles long. The river originates in the Rocky Mountains, and the basin extends to the Continental Divide at an elevation of 14,250 feet on Long's Peak. The Big Thompson River flows in an easterly direction through the southern part of Larimer County. Considerable residential development has taken place along the riverbanks, especially in the narrow canyon area. Channel slopes range from approximately 18 feet per mile in the area near Loveland to 130 feet per mile through the narrows. The soils in the Big Thompson River study area consist of Fluvaquents-Fluvents, Haploborolls-Camborthids- Argiborolls, and Argiborolls-Rock Outcrop Associations (Reference 4). The studied section of the North Fork Big Thompson River is approximately 9.8 miles long, with the lower study limit being at the confluence with the Big Thompson River at Drake. The average channel width through the studied section is 25 feet, and the channel slope averages 132 feet per mile. Soils consist of North Rock Outcrop and Haploborolls- Camborthids-Argiborolls Associations (Reference 4). Numerous small tributaries were included in this study. The sections studied along these tributaries are generally less than 0.5 miles. The stream channels are narrow and have slopes averaging 400 feet per mile. Two larger tributaries to the North Fork Big Thompson River, West Creek and Devils Gulch, near Glen Haven were also studied. West Creek and Devils Gulch have average channel widths of 25 feet, and their slopes are 90 feet per mile and 400 feet per mile, respectively. The soils along West Creek and Devils Gulch are of the Haploborolls-Camborthids-Argiborolls Associations (Reference 4). Buckhorn Creek flows east and south through Larimer County and joins the Big Thompson River approximately 5 miles west of Loveland. Redstone Creek flows south on the east side of the Buckhorn Creek basin and joins Buckhorn Creek at Masonville. Development in the two basins is confined to those areas where the valley width permits it, and consists mostly of farming units. The channel slope of Buckhorn Creek in the studied section is approximately 58 feet per mile, and the Redstone Creek channel slope averages approximately 185 feet per mile. Soils in the Buckhorn Creek and Redstone Creek basins are of the Fluvaquents Fluvents, Argiborolls-Rock Outcrop, and Arguistolls-Haplustolls Associations (Reference 4). Boxelder Creek flows in a southerly direction through Larimer County past the west side of the Town of Wellington. Very little development has occurred in the flood plain within the county. The Boxelder Creek watershed, approximately 32 miles long with an average width of 8 miles, flows from an altitude of 7,720 feet at its headwaters in Wyoming to 10