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<br />tributary basin is narrow, composed of highly erodible clay loam <br />soils, and hydraulically steep. The ground elevations range from <br />approximately 5,500 feet in the northwestern portion of the city <br />to 5,300 feet in the southeastern portion. Ground cover in the <br />undeveloped portion of the basin is predominately buffalo grass, <br />with willow and cottonwood trees. Niver Creek and Tributary L of <br />Niver Creek share the above characteristics with the exception of <br />the specific ground elevations. <br /> <br />The major geologic units found adjacent to the flood plain areas <br />in Federal Heights are post-piney alluvium and Piney Creek alluvium. <br />The soils found in the flood plain areas are Arvada loam, ulm loam, <br />sansil-shingle complex, and loamy alluvial. <br /> <br />Federal Heights is located in a' semiarid high plain climatic region <br />modified by the proximity of the Rocky Mountains. Because Colorado <br />is situated in the central portion of a large landmass and is far <br />removed from coastal moisture, the major influence on the climate <br />is the State's continental location. In general, the climate is <br />characterized by meager precipitation, a distinct summer season, <br />and a marked winter season, when precipitation is mostly snow. <br /> <br />The annual precipitation in Federal Heights is approximately 15 <br />inches, which includes an average snowfall of approximately 58 <br />inches. Average daily temperatures range from 300F in January to <br />730F in July, with a daily temperature fluctuation of 25 to 30 <br />degrees. <br /> <br />2.3 Principal Flood Problems <br /> <br />Severe flood runoff is transported through Federal Heights as both <br />overland shallow flow and as channel flow. The steep slope of the <br />land, the close proximity of mopile homes to Tributary M of Niver <br />Creek, and the presence of several culverts that are inadequate to <br />convey major storm runoff combine to create flooding problems. <br /> <br />The runoff upstream of Zuni Street is overland flow that can overtop <br />roads and inundate mobile home trailers. The average slope is 3.5 <br />percent I therefore, excessive velocities occur. <br /> <br />Downstream of Zuni Street, the runoff flows through culverts and <br />well-defined channelsl however, there is some overland flow. Roads <br />and trailer homes can be inundated. The average slope in this <br />area is 1.5 percent. <br /> <br />On June 13, 1984, severe rainfall runoff caused considerable damage <br />to mobile home trailers, to private property, and to the channel. <br />One fatality was directly attributable to the shallow overland <br />flow. Unofficial estimates gave the peak dicharge from the storm <br />as 800 to 1,000 cubic feet per second (cfs) at Pecos Streetl this <br />was the result of a 4.2-inOO rainfall, which fell within 3 hours. <br /> <br />4 <br />