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a-foot diameter corrugated metal pipe culvert to its confluence with Clear Creek. The intervening l-square-mile basin between the confluence of East and West Forks Kenneys Run and the mouth of Kenneys Run is a heavily urbanized area lying in the valley between Lookout and South Table Mountains. The flood plain areas for the entire length of Kenneys Run and the lower portions of East and West Forks Kenneys Run have been densely developed. Lena Gulch has its source on Lookout Mountain and flows northeasterly, where it joins Clear Creek in Wheat Ridge. Apex and Jackson Gulches drain the foothill area south of Lookout Mountain before joining below Heritage Square at the base of the foothills to form Lena Gulch. Lena Gulch then flows parallel to the north side of U.S. Highway 40 through Golden. This reach also receives runoff from the northwestern slope of Green Mountain. The total drainage area of Lena Gulch affecting Golden, 3.68 square miles, is charac- terized by steep slopes, bedrock outcrops, and some forested areas in the foothills, and by heavily developed flood plain areas in Golden. At several locations along Lena Gulch, the natural channel has been diverted and partially filled. The climate in the Golden area is characterized by cold winters and warm summers. Mean monthly temperatures range from 3l.9*F in January to 73.l*F in July, with an average annual temperature of 5l.l*F. The average annual precipitation is 14.95 inches, falling mainly from April to August (Reference 4). The heaviest recorded general rainfalls have come in late May and early June, when the temperature contrast between warm surface air and cool upper air is greatest. The Golden area is also subject to a meteor- ological phenomenon known as cloudbursts. They are confined chiefly to the eastern foothills regions below an elevation of 7,500 feet and extend eastward toward the plains for approximately 50 miles. Cloudbursts develop when there is a marked temperature range within a relatively small area and occur in the afternoon or early evening of an unusually warm day. Cloudbursts are characterized by intense rainfall of short duration that is confined to a very small area. These storms have rarely occurred where precipitation could be measured at a weather station (Reference 5). In the Golden area, the peak discharge from a cloudburst is greater than that caused by rainfall during a period of snowmelt. 2.3 Principal Flood Problems Manmade and natural obstructions in stream channels and flood plain areas impede the flow of water, creating a backwater effect that increases flood heights. In Golden, these obstructions include bridges, culverts, stream-regulating structures, channel realine- ments from their natural course, buildings in the flood plains, and trees and brush in the stream channels. 5