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24 inches annually. Land use adjacent to the streams is primarily residential, with same commercial buildings. The terrain is mountainous with steep slopes. Soil types within the study area vary. The soils of the Allen Park Series, which fo~d on the mountain Slopes between 6,300- and 8,200-foot elevations, are loamy colluviwn and weathered granite residuum. The surface layer, approximately 2 inches thick, is dark-gray, gravelly, sandy loam. The subsurface layer is light brownish-gray, gravelly, sandy loam. The Pern Cliff Series is loamy mixed a11uviwn on short fans and valley side Slopes in the mountian area in the same elevation range. The top layer of this series is dark grayish-brown, stony, sandy loam and the subsurface layer is light-gray, stony, sandy loam. The barren areas are predominantly exposed bedrock that consist of mixed materials, including granite, sandstone, shale, and limestone. The dominant land-cover species is ponderosa pine, and, above 8,000 feet elevation, there are some Douglas fir and lodgepole pines. The Town of Superior is located in southeastern Boulder County, approximately 20 miles northwest of Denver. Xn 1970, the population of Superior was 171 (Reference 15). Nearby communities are Louisville, 5 miles northeast; Boulder 6 miles northwest; Lafayette, approximately 7 miles northeast; and Broomfield, 7 mdles southeast. Superior is surrounded by the unincorporated areas of Boulder County. Coal Creek flows through primarily agricultural land. which is not zoned within the Town of Superior, is residential. Land use, primarily Average annual precipitation is approximately 18.5 inches and the normal mean temperature is 51.80P. Extremes of annual precipitation have varied fram a max~ of 29.09 inches in 1938 to a minimum of 10.91 inches in 1954. The mean maximum and minimum temperatures in JUly are 85.30P and 59.0oP, respectively. 2.3 Principal Plood Problems Flooding in Boulder County is due mainly to snowmelt combined with heavy rainfall, although heavy rainfall, especially in the fo~ of cloudbursts, is alone capable of causing flooding. Ploods caused by rainsto~s can peak within a few hours of the rainfall, leaving little time for evacuation. Much of the floodplain is used for agriculture, thus the flood damage is mainly to crops, irrigation equipment, roads and bridges. Damage to residential and industrial areas occurs in and around several communities that are excluded from the study area. However, many of these communities are experiencing rapid growth, and thus are increasing encroachment on the adjacent floodplains. There are also undefined, very localized zones of velocity hazard throughout the studied reaches of Lefthand Creek. Generally, these zones are in the channel and near bridges. 13