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remalnlng 60 percent of the precipitation Occurs as snow. The small amounts of water in the air are accompanied by a large percentage of sunshine and sizable temperature changes from day to night. Winters in the study area are long and cold, with mean daily temperatures of approximately 30.FI. Summers are hot and mild with mean daily temperatures near the m~d 70s (References 4 and 5). The soils in the area are generally deep, well-drained, clayey soils that are neutral or mildly a1ka1in~ (Reference 6). 2.3 Principal Flood Problems Flood problems within the Sloans Lake subbasin in the City of Edgewater are due to overflow fro~ the drainageway between Ingalls Street and 20th Avenue to the ea'stern corporate limits at Depew Street. Upstream of Ingalls Stree~ and 20th Avenue to the western corporate limits, overflow is split between a storm sewer and the streets. Flooding in this area is caused in part by thunderstorms during the spring, perpetuated by antecedent ground moisture and melting snow. 2.4 Flood Protection Measures The City of Edgewater, in conjunct~on with the City of Lakewood and City and County of Denver, permitt~d the Denver Urban Drainage and Flood Control District (UD&FCD) tq plan and implement channel and culvert improvements in 1977. TheiUD&FCD constructed the West 18th Avenue extension channel from Depew Street to Sheridan Boulevard. To improve the efficiency of bridge culverts at Depew Street and Sheridan Boulevard, the UD&FCD installed twin 12- by 5-feet culverts at Depew Street and fout. 7- by 5-feet precast-concrete boxes at Sheridan Boulevard. All construction was completed by early 1983. The newly installed culverts relieve bottleneck conditions caused by inundation. , In 1987, channel improvements between Ingalls Street and 20th, Avenue to Depew Street were completed. A detention pond outside the corporate limits at 25th Avenue and Wadsworth Street reduces sheet flow east of Pierce Street. 3.0 ENGINEERING METHODS For the flooding sources studied by de~ai1ed methods in the community, standard hydrologic and hydraulic study: methods were used to determine the flood hazard data required for thi~ study. The flood event of a magnitude which is expected to be equaled or exceeded once on the average during any 100-year period (recurrence interval) has been selected as having special significance for floodplain management and for flood insurance rates. The event, commonly termed the 100-year flood, has a 1-percent chance of being! equaled or exceeded during any year. Although the recurrence interval represents the long-term avera2e score period between floods of a specific magnitude, rare floods could occur at short intervals! or even within the same year. 4