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At the road crossings of the left bank tributary at elevations of 7.050 and 7,200 feet, very extensive debris-flow deposits occur. The drainage area is estimated to be 2 square miles. There are several 100 foot long debris-flow levees with 2 to 3 foot diameter boulders on the top surface. The channel is 50 feet wide and the deposits are 10 or more feet above the streambed. Also, at several abrupt channel expansions there are deposits with boulders as large as 10 feet. The boulders are completely lichen covered and there are many 3 to 4 foot diameter trees growing on the debris-flow deposit surfaces suggesting the deposits are 200 or more years old. The recent channel (there are no indications of higher water-flows) is 3 feet wide and less than a foot deep. The stream banks and channel boulders are completely covered with moss or lichen. Recent peak discharge is estimated to be 30 cubic feet per second. The lack of flood evidence indicates that flows have not exceeded the erosion threshold discharge of 200 to 300 cubic feet per second in the last hundred years or more. Par about 1/2 mile upstream, to Crystal Park lake, the hillside is extremely steep and probably is the source area for the debris flow. Several possible source areas for the debris flow were considered, but because of the length of intervening time the location could not be pinpointed without closer inspection. Williams Canyon Williams Canyon drains 2.7 square miles. Prom the Cave of the Winds road switchback downstream, the canyon has been extensively modified; hence paleoflood studies, particularly to identify large floods, were not done. At an elevation of about 6,840 feet, there is is large flood bar or boulder berm (these result from highly concentrated sediment-laden floods, but not a debris flow) that is about 200 feet long and 20 feet wide (indicative of a large flood). The top of the berm is about 10 feet above the streambed and the width is 70 feet; the mean flood depth is about 6 feet. The surface of the berm is covered with boulders 4 to 5 feet in diameter, many 4 to 5 inch diameter scrub oak, and several 12 to 15 diameter spruce trees indicating the berm may have been deposited about 75 to 100 years ago. These deposits represent the largest flood that has occurred in the channel and suggests that the maximum historic peak discharge is about 4,200 cubic feet per second. Given that the flow contained a large , amount of sediment, the water discharge may have only been about a half this discharge. At an elevation of about 7,040 feet, there are flood-boulder deposits (boulders up to 3 feet in diameter) in the channel that are about 10 feet above the streambed (mean depth is about 5 feet) and the channnel width is 25 feet. The decayed organic flood debris, several 6 to 10 inch diameter spruce trees suggest that this medium flood occurred about 40 to 50 years ago. The peak discharge for this flood is about 1,200 cubic feet per second. Prom this elevation downstream to the switchback in the Cave of the Winds road there is very consistent evidence of recent flows. The channel is about 6 feet wide and the banks are covered with grass and brush. Organic flood debris that is less than about 10 years old on i.