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Water-surface profiles for Cherry Creek utilized in this FIS were obtained from a COE Flood plain Information report (Reference 14), and were developed using the COE HEC-2 step-backwater computer program (Reference 25). The computations were based on channel and flood plain conditions as represented by the survey data gathered in April 1975 and as supplemented by later field investi- gations. Cross section data were obtained by field measurements except for portions of East plum and Happy Canyon Creeks, and Sellers, New- lin, Baldwin, Sulphur, and Tallman Gulches. These areas were photographed and mapped, and digitized cross sections were ob- tained from the contour plans. All bridges, culverts, and other structures were surveyed to obtain elevation data and structural geometry. Locations of selected cross sections used in the hydraulic ana- lyses are shown on the Flood profiles (Exhibit 1). For stream segments for which a floodway was computed (Section 4.2), selected cross section locations are also shown on the Flood Insurance Rate Map (Exhibit 2). Roughness coefficients (Manning's "n") were estimated by field investigation and from pictures of the stream and its flood plain using.USGS Water Supply Paper 1849 (Reference 26), Open-Channel Hydraulics (Reference 27), and Handbook of Applied Hydraulics (Reference 28). The "n" values for plum Creek, East Plum Creek, West plum Creek, Indian Creek, Hangmans Gulch, Sellers Gulch, Unnamed Tributary to Sellers Gulch, and Carpenter Creek ranged from 0.03 to 0.06 in the main channels and from 0.04 to 0.12 for the overbanks. The "n" valuE!S for Cherry Creek ranged from 0.04 to 0.055 for the channel and from 0.061 to 0.095 for the over- banks. For Happy Canyon CreE!k, Newlin Gulch, Baldwin Gulch, Sulphur Gulch, Tallman Gulch, and Bayou Gulch, the "n" values ranged from 0.03 to 0.05 for the main channels and from 0.03 to 0.12 for thE! overbanks. For the South platte River, Horse CrE!ek, and West Creek, the "n" valuE!s ranged from 0.03 to 0.045 for the main channels and from 0.016 to 0.12 f~r the overbanks. For Cherry Creek, the COE used critical depth to determine the starting water-surface elevation. For every other stream studied by detailed methods, the starting water-surface elevation was determined using the stream slope at a starting valley cross section. The methods used in estimating elevations of streams studied by approximate methods included direct use of UDFCD information, calculation of normal depth from field cross sections with an 2S '.