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Snowmelt-generated floods dominate above elevations of 7600 feet (Jarrett, 1989). Rainfall-generated floods are most likely to occur during the summer months, when thunderstorm cells produce intense precipitation over limited areas. Rainfall floods generally affect smaller areas, and have flashier hydrographs than snowmelt floods. These are the floods which cause damage and loss of life in the Front Range channels, as in the 1976 Big Thompson flood. Front Range floods may also originate from dambursts. The 1982 Big Thompson flood provides a spectacular example of a flood caused by the breaching of a man-made darn. There are numerous sites along the upper Poudre which appear to have been temporarily dammed by landslides and debris flows, and the floods which resulted when these darns were breached have undoubtedly had an important influence on channel morphology. IV. METHODOLOGY Information on paleofloods can be obtained from fine-grained sediments known as slackwater deposits, which settle from suspension in zones of reduced flow velocity during large floods. Accumulation sites include the mouths of tributary channels, caves or alcoves along the channel margins, in the lee of obstructions to flow (talus slopes, bedrock knobs), and above and below abrupt channel constrictions. At each of these sites, a series of deposits accumulates, both as a vertical stack and as insets, with each depositional unit representing an individual flood event. In a confined, stable channel like the Poudre Canyon, the top of each sedimentary unit provides a minimum estimate of the peak stage of the associated flood. The estimates are minimum values due to; (a) the high probability that there is some depth of clear water over the highest sediments, and (b) potential removal of some of the upper deposits due to weathering and erosion after the flood. Multiple slackwater deposits along a channel reach may be used to define a water-surface profile for the flood. Computerized step-backwater flow simulation models may then be used, in combination with surveyed channel geometry and water- surface profiles defined from slackwater deposits, in an iterative procedure which matches simulated water-surface profiles to field-defined profiles. Using this approach, slackwater deposits provide a record of past flood discharges. Slackwater deposits also record flood frequency. organic materials associated with the flood sediments can be used to develop a radiocarbon-based flood chronology. Depending on the material analyzed, the radiocarbon dates may provide a maximum limiting age for the flood event (charcoal), or they may provide a more precise date of flood occurrence (leaf litter and twigs). Where multiple depositional units are present, it is necessary to obtain multiple radiocarbon ages in order to accurately characterize flooding.