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.... Hr. Sid Fox ^'HjIlSI 77, 1981 I'dg(' iwo Further discussions on ihe hydrology of the Eagle RIver downstream of Minturn appears to be necessary to sdLisfacLorlly resolve this Issue for future studies. 7. Rouqhn~ss Co~fficlpnis In our opinion from a visit to the site on August 13, 1981, ihe roughness co~rricients (n channel = 0.040 dnd n overhank = 0.070) drp st iJ I too low. The staff feel s they should be from 0.045 to 0.050 for the channel and from 0.080 to 0.100 for Lhe overbank immediately adjacent 1.0 the chdnnel for this reach. ThIs opInIon was also given independlly by Bob Jarrelt, an expert at the USGS, using photographs of the reach, 3. Wdter Surface ProfilE' The combined impact of our concerns on the water surface profile prepared by Mr. Dezmdn would be an Increase In depth ranging from dpproximdtely 1.4 feet at the upstream end to about 1.0 feet at the downstream end based on prel imindry est imdtes. A re-rUn of the progrdm is the only way to accurately test the sIgnifIcance of varying the roughness coeffient. 4. Flooded Area Boundary The combined impact of our concerns on the floodplaIn boundary perpared by Mr. Dezman would be to increase the 100-year flooded area and therefore decrease the net developable land for this site by approxImately 0.6 acres. 5. Flood Hazards On I y proposed bu I I dings 0 and P appear to be part i ally exposed to 100-yedr flood hazards a~d they are probably not in a floodway or high hazard area, If both of these structures were moved approximately 50 feet due east, they would he beyond the limits of the 100-year floodplain. FloodprooFing and raising first floor elevations also appears to be a possible alternatIve to mitigating the flood hazard. All the other proposed structures appear to be well above and outsIde of the 100-year flood hds~d on our criteria. 6.' .First Floor Elevations The rc'comml'llddiloll hy Mr. I)l'J:m.\I1 thdt 7.3 feet of freeboclrd (dhove the wdier surface profile for 4500 cfs)