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The following streams were studied under the original studies and contracts shown below: Butcherknife. Fish. Soda. and Spring Creeks Under Inter-Agency Agreement No. lAA-H-16-75, Project Order No. 17, cross sections for backwater analyses were located at close intervals upstream and downstream of bridges and culverts in order to establish the significant backwater effects of the structures. Cross sections were furnished by the State of Colorado or developed in whole or in part from topographic data (at a scale of 1 :2,400, with a contour interval of 2 feet) furnished by the Routt County Planning Commission (Reference 28); by Dale Y. Foster, Inc., at a scale of 1:4,800, with a contour interval of 5 feet (Reference 29); and by the State of Colorado at scales of 1 :2,400 and 1 :4,800, with a contour interval of 2 feet (Reference 30). Field surveys and observations were used as needed to supplement available topographic data. Selected cross sections are shown on the maps. Roughness factors (Manning's "n") for hydraulic computations were assigned on the basis of stream gage data and field inspection of floodplain areas. Roughness values for Butcherknife, Fish, Soda, and Spring Creeks are shown in Table 2. Dry Creek Under Inter-Agency Agreement Nos. IAA-H-12-16 and lAA-H-28-75, Project Nos. 1 and 2, cross-section data for Dry Creek were obtained from field survey measurements taken in approximately 300-foot intervals. Cross sections were located at close intervals above and below bridges and culverts in order to compute the backwater effects of these structures. At various locations along Dry Creek, the original cross sections were manipulated and/or extended by interpolation to better defme the physical and natural conditions that exist. All bridges and culverts were surveyed to obtain elevation data and structural geometry. Roughness coefficients (Manning's "n") for water-surface computations were determined from field inspection, aerial photographs, and a USGS Water Supply Paper (Reference 31) for all floodplain areas. These roughness values are listed in Table 2, Manning's "n" Values. Water-surface profiles were developed through use of the USBR computer program WSPP5H (Reference 32). Starting flood elevations for Dry Creek were extracted from a rating curve developed from the railroad crossing, which is constructed of four large culverts. Oak Creek The CWCB completed an analysis of the hydraulic characteristics of Oak Creek to determine WSELs for the loo-year flood. Bridge elevations and sizes of openings were surveyed and measured in the field on January 21 and 22, 1986. These data were combined with cross-section data on Oak Creek taken from 2-foot contour mapping of the Town of Oak Creek (Reference 33). These cross-section data were the input data in the USACE HEC-2 (Reference 34) step-backwater computer program. 33