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The effects of the combined in-bank and overflows at 7th Street to about 2000 cfs will raise the in- bank flow levels at cross section 7 to about the top of the tinilier-walled channel. consistent with the grade of the top of the timbered channel wall from section 7 to the post office, a first floor elevation grade line is indicated 1.0 feet above the wall grade. This grade line is also consistent with existing grade on Argentine which at the present time is with- out curbs and pavement. Conclusions: 1. The proposed "structural" use of the particular area behind the post office, with the reco~~ended first floor' elevations is not affected by any flood hazards of an infrequent flow of 2500 cfs. 2. Since the flooding conditions were estimated by cross section intervals relative to the particular area from 6th to 7th Streets, the cross section information provided between and Rose Streets i!ldicate the extent of the limits of infrequent flooding conditions as affecting more areas than represented by the cross sections required for particular area behind the post office. Accurate locations of these flood limits will require accurate topographic and terrain information. As represented by accurate contours and the location of land features in addition to the cross section information limited to this particular evaluation. 3. Cross sections taken for the ground elevations, with subsequent flow elevations estimated, were based on an elevation control bench mark at the post office with an assumed datum of 150.00 ft. As additional flood elevation information is required for adjoining areas, whose elevation control is uerived from, USGS mean sea level elevations, a closure equation will be required to adjust the 150.00 datum to USGS as the USGS bench marks are extended and made available. 4. For the statistical 100 year flow frequency relation- ships for Clear Creek flows, a review of flood estimates for flood studies in progress at this time indicates an insufficient record of measured flooding for which statistical reliability standards required for the type of flooding occurrences unique to the Georgetown area. Standards for which other means are required to ascer- tain a reliability of a "statistical measure of certainty" include evaluation of historically reported flooding and precipitation loss determinations whose difference as a flooding condition is identified with regard to snow-melts and combinations of snow-melts and rainfall such as a thunderstorm flood. Recent information received from the FIA studies in progress, indicate an evaluation is presently being made of historically -4-