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ii' ,No., ., US 40, was diverting all the flow on September 2 (based on channel evidence it appeared flow is diverted much of the time). The estimated discharge on September 2 upstream from the diversion was about 10 cubic feet per second. In the channel for about 3/4 of a mile upstream from the diversion (as far upstream as I hiked) there were three types of reaches alternating along the channel: short steep reaches of extensive channel bank erosion; wide, flatter, depositional reaches, and: reaches with minimal flood deposits that are relatively straight and uniform (nondepositional reaches). The steep valley side slopes did not show any evidence of recent or past rill or gully erosion that would indicate intense rainfall had occurred. The small tributaries did not indicate any recent erosion. I did not get up in the headwaters of the basin and could not adequately see the tributaries with binoculars. There did not appear to be any large debris flows or landslides in the eastern part of the upper basin. The erosional reaches are typically in steeper reaches where channel gradient is 2 to 4 percent. There are some very old and extensive debris-flow deposits along the sides of the channel that appear to be the primary source area of the flood deposits. The deposits are very poorly sorted fines, gravel, cobbles, and boulders. The deposits are noncohesive and are easily eroded, Where erosion has occurred (mostly lateral erosion), sections of bank up to 50 feet in length and 10 feet in width had been eroded. Upstream from the diversion dam there are extensive flood deposits on both banks because it is a backwater area from the diversion structure. The channel gradient in this reach is about 2 percent, the channel width varies from about 15 to 30 feet and the thickness the deposits varies from 0.5 to 3.5 feet. Flood deposits are poorly sorted sand, gravel, cobbles, and boulders up to about 18 inches in diameter. There is no imbrication of the coarse material. In some deposits, the largest boulders are located on the surface of the flood deposits and others are concentrated on the inside of channel bends. No recent debris-flow levees were observed. Most of. the larger flood deposits are located upstream from natural channel constrictions. During the flood, organic material (trees and willows) formed temporary dams at.these constrictions causing extensive backwater conditions and overbank flooding that deposited extensive amounts of sediment. The debris dams only remain in the channel margins and overbank areaS. There were no other older flood deposits along Jim Creek. In a relatively uniform reach of channel about 300 feet upstream from the diversion, the channel width averages 30 feet. The main channel is 15 feet wide and has a mean flood depth of 3 feet (based on the top of the flood deposits). The channel has large cobbles and boulders. I estimate the mean flo" velocity during the flood was about 6 feet per second (based on hydraulic conditions at similar sites where I have measured the flow velocity), The left overbank width is about 15 feet and the mean flood depth is'about 1 foot. The mean flood velocity in the left < -,---,-.;~'. - ,- ,'".;,- ." ,,~ -'-'''''''''''''''-~'''--