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• covered in the Sege Creek discussion, Sites YSS3 end YSSF2 ere covered in the Y-7 <br />tributary discussion, Site YSA F4 is addressed with the Annend Drew discussion, end Site <br />YSGFS Is addressed in the discussion of Cressy Creek. All date collected at each site <br />(both tabular end graphical instantaneous and continuous discharge measurements and <br />discharge statistics) has been compiled end is presented in Appendix 7-6. One site along <br />Sage Creek has been assigned two different site IDs. This is because for a portion of its <br />monitoring history it was a flume monitoring site end for the remainder of the time, e <br />periodic monitoring site. The site ID for the continuous monitoring period is YSSF1 end <br />the site ID for the instantaneous monitoring period is T552. The reader should refer to <br />Exhibit 7-1 to find stream monitoring site locations. Tab 75, "Hydrologic Monitoring <br />Program", contains specific monitoring site information such es instrumentation, <br />monitoring history, monitoring methods, end monitoring frequencies for sites discussed in <br />the following sections. <br />The seasonal variability of discharges in the above-referenced basins generally follows <br />the pattern presented previously for the Yampa River Basin (see Regional Surface Yater <br />Flow). The larger streamf lows in these drai neges result from snowmelt runoff, beginning <br />• typically in march or April (with more severe winter conditions) and lasting into June for <br />years with above average snowfall. <br />Besef low in the larger channels (Sage Creek end Grassy Creek) is commonly maintained after <br />conclusion of the snowmelt runoff through the summer months end into the fell by the <br />discharge of shallow ground water into the channels. Occasionally, baseflow in the larger <br />stream channels is increased by runoff resulting from summer thunderstorms (June, July, <br />and August), or from frontal storms that occur in April end Mey, ar October and November. <br />These frontal storms commonly exhibit precipi ten on as a mixture of snow and rein, end <br />only produce runoff if precipitation is intense end of long duration. In the larger <br />streams, bas eflow often increases measurably in October through December, es <br />evapotranspiration rates of valley bottom vegetation attenuate end cease with the onset of <br />fell end winter, end shallow ground water becomes more available for contributing to <br />streamflow. <br />Precipitation varies from year to year owing to a variety of variables. AnnueL end <br />monthly precipitation totals for the period 1978 to 1993 is presented in Table 7-32 to <br />• provide one with an indication of yearly variability as well ea variability over a decade <br />or more. For the 76 years of record presented, 4 years have been below the long term mean <br />of 15.9 inches end 12 years have seen above average precipitation. Five of the years of <br />95 <br />