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" HYDRO - TRIAD', LTD. November I, 1978 Mr. Bill Stanton Colorado Water Conservation Board Department of Natural Resources 1313 Sherman Denver, Colorado 80203 Dear Bi 11: r Pursuant to our contract with the Colorado Water Conservation Board and the City and County of Montrose regardi n!l the Montrose Floodplain Definition Study, enclosed al'e the Dry Cedar Creek plan and profiles indicating extent of flooding, as well as a new set of the plan and profile data for Montrose Arroyo, as that data apparently was not completely furnished during our meeting of last week. Al so enclosed are three revised. crossing rating forms for Dry Cedar Creek. As di scussed, di screpanci es between c1i git ited and mappi ng contour data resulted in some adjustment to our initialitation ratings. These tl1ree revi sed ratings thus suppl ant the correspond'! ng rat i ngs shown in the Hydraulics Addendum. Forthcoming shortly will be several summary sheets of computer backwater cal cul at ions. These sect ions of the vari ous streams wi 11 be re-run so as to reflect revised initial vlater surface elevations. The revi s ions are resultant from the di giti zed data versus map contour discrepancies. It is not anticipated that revisions will be required of the map data, as the profile was prepa:red using the revised initial water surface elevations, and the backwater effect resultant from the revision was accounted for in setting th,=, water surface elevations. r F r r r r r r In preparing the final report, several items n,=ed to be clarified: a) On the profil es, a deci s1 on must be made whl~ther to show the thalweg as determined from the d'igitized data, or from con- tours. The digitized data will ref"lect the hydraulics as cal cul ated, whereas the contour dat,l will mai ntai n agreement between plan and profile. r I I 1500 VV, MISSISSIPPI AVE. ' SUITE 10 LAKEWOOD, COLORADO B0226 PHONE 303,934.24l7 ----.