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normal mean temperature is 51. 8oF. Extremes of annual precipitation have varied fram a maximum of 29.09 inches in 1938 to a minimum of 10.91 inches in 1954. The mean maximum and minimum temperatures in July are 85.30F and 59.0oF, respectively. The City of Longment is located in northeastern Boulder County, approximately 38 miles north of Denver. Agriculture is the economic base of Longment, although nearby Denver and Boulder have influenced the growth of new commercial and industrial development. This is reflected in the population trends of Longment. The population figures for Longmont for 1950, 1960, 1970, 1980, and 1990 are 8,099, 11,489, 23,209, 42,942, and 68,154, respectively. The climate is temperate. Daily average temperatures are 650F for May to September and 370P for October to April. The average annual precipitation is 12 inches for the City of Longmont and nearly 17 inches in the mountains of Boulder County, with an average monthly rate of 1.5 inches fram April to September. The city lies within the St. Vrain Creek Basin; headwaters extend by way of North and South St. Vrain Creeks into the Rocky Mountains up to the Continental Divide. Elevations range from 4,900 feet in Longmont to over 14,000 feet at Longs Peak. The water of St. Vrain Creek has been appropriated for municipal and irrigation usage. The topography of St. Vrain Creek, Lefthand Creek, and Dry Creek No. 1 Basins ranges fram rugged and heavily forested Rocky Mountain canyons in the west, to Slightly rolling prairie land near Longmont, where pasture land and cropland border streambanks lined with brush, willow, and cottonwood trees. Spring Gulch has a basin that extends to Terry Lake, but it has a channel only from 15th Avenue to St. Vrain Creek in Longmont. Loamiller Basin lies entirely within Longment. Dry Creek No.1, Spring Gulch, and Lefthand Creek originate outside the PMA of Longment in the Rocky Mountain foothills and follow generally easterly courses through the city. Spring Gulch consists of an improved channel that starts south of East 15th Avenue and continues as a concrete-lined channel through Spring Gulch Linear Park to Third Avenue, then down to St. Vrain Creek. Loomiller Basin is a depression oriented in a northwest-souteast direction through central Longment. Floodwater accumulates in the depression and subsequently drains into Spring Gulch Basin near Third Avenue and Atwood Street. A large portion of the area within the PMA of Longment limits and adjoining the streams is fully developed. Commercial and residential development exist in the floodplains of all the streams studied. On St. Vrain Creek, from Airport Road to the confluence with Dry Creek No.1, industrial and commercial buildings, fa~s, and mohile home parks share the flOOdplain with gravel-mining sites. The D~ Creek No. 1 floodplain is occupied by both commercial building and single-family dwellings from Sunset Street to the confluence with St. Vrain Creek. Development along Spring Gulch is also represented by pastureland and a linear park 11