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8,800 feet is about 24 inches with a water equivalent of about 6.8 <br /> inches on or about April 1 . Data for the period of record for this <br /> station were utilized in a snowmelt flooding analysis for Ralston <br /> Creek (see Appendix B-1) . <br /> 3.3.3 Runoff Characteristics <br /> The greatest volume of surface runoff in the Ralston Creek <br /> watershed commonly occurs from snowmelt. However, peak flows generally <br /> result from late spring and summer thunderstorms. According to Jarrett <br /> (Oral Communication, 1983) , the most destructive flooding on Ralston <br /> Creek would result from intense rainfall associated with severe thunder- <br /> storm activity. <br /> Data on streamflow volume and - treated Schwartzwalder Mine <br /> water flow in Ralston Creek are available for calendar years 1975 <br /> through 1978. These flows, in acre-feet, are summarized by month and <br /> calendar year in the report "Surface Water Flows in Ralston Creek, <br /> 9 <br /> 1975 <br /> Through 1978" , prepared for the Cotter Corporation by Hazen Re- <br /> search, Inc. (Golden, Colorado) in 1979. Collection of this volumetric <br /> data continues. At present, however, no continuous-record data are <br /> available for Ralston Creek suitable for determination of peak discharge <br /> information. <br /> Peak flood flow estimates for Ralston Creek are reported by the <br /> Urban Drainage and Flood Control District in the "Major Drainageway <br /> Plannng, Phase B Master Plan" for Ralston and Leyden Creeks (1977) . <br /> These estimates have been designated and approved by the Colorado Water <br /> Conservation Board. Because these peak flows are the result of the most <br /> detailed study that has been done for Ralston Creek to date, and have <br /> been approved by the agencies, they have been adopted as the basis for <br /> use in this study and are further discussed in Section 5.2.1. <br /> - 12 - <br />