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s ti This study wil I investigate minimum streamflow and sediment transport In the Yampa Canyon In northwestern Colorado. The historic sediment load wil I be analyzed for the period of record for the available gaging station data. A minimum streamfIow hydrograph for the Yampa fn Dinosaur National Monument has been previously proposed by the National Park Service (O'Brien,. 1984). This study wil I examine that hydrograph and test possible alternative minimum stream flow hydrographs. These minimum streamflcw hydrographs w i l l be evaluated for their effect on sediment supply to the canyon and sediment transport through the canyon. The comprehensive goal of this project is to investigate the potential for designing a minimum streamfl ow hydroggraaph that would preserve and maintain the natural condi ti ons and processes vital to the bi of ogical system of the Yampa River in Dinosaur National Monument. This investigation would rev few and ref ine previous work by the U. S. Geological Survey (USGS Elliott, et al., 1984) and the National Park Service (NPS O'Brien, 1984) and would attempt to analyze adverse impacts on sediment transport from a reduced or otherwise altered seasonal discharge. The scope of work to accompl ish this objective is outlined below in four tasks. 1. Analyze the sediment supply from the Little Snake and Yampa Rivers upstream of Dinosaur National Monument for the period of record from water years 1921 to 1984. Daily sediment load records are avail able for approximately five years on the Little Snake (1959- 1964) and twelve years on the Yampa (1952-1958) and (1976-1982). 2. Review the sediment transport analysis by the USGS (El I iott, et al., 1984) at Deerlodge Park and the NPS (O'Brien, 1984) at Mathers Hof e a nd ev al uate the rel ati onsh i p between th i s data and the upstream supply data at the USGS gaging stations. 3. Determine the nature of the sediment load passing through Dinosaur (as measured at Mathers Hole) over the period of record (1921-1984) and evaluate whether a_sediment eguil ibrium condition is being maintained In the Monument. 4. If sediment equilibrium has been maintained, formulate a minimum daily flow hydro rah over the period of record t At approximatel y maintains th s historic sediment equi brium at Mathers Hole. BACKGROUND I N FORMATION The riverine environment of the Yampa River In Dinosaur National Monument is created through a diverse blend of physical conditions and processes. These include the steep channel slope and coarse bed material In the canyon and the water and sediment supply from two tributaries upstream of the Monument boundary, the Yampa and the Little Snake Rivers. The two