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<br />. <br /> <br />. <br /> <br />USFWS - Palisade/Grand Junction Stream Flow Analyses - DRAFT <br />May 12, 1995 <br />'Page 20 <br /> <br />VII ~ASE INFLOW <br /> <br />, One ,objective in the gaging evaluation effort is to collect information on the base, or <br />minimum local inflows, that might be experienced in the critical reach. It is still difficult <br />to derive conclusions about the base inflows that may occur to the critical reach from flow <br />data collected in 1991, 1992 and 1993 because 1) above average precipitation occurred <br />during the September through November period in 1991 and 1992, and in August and <br />October of 1993,2) exceedence of rating curve data in all three years, 3) operation of the <br />upstream local irrigation company diversion structures, and 4) ice effects caused by poor <br />quality records in late December, 1992 and 1993. By analyzing the August through <br />October flows' the difficulties associated with items 3 and 4 can generally be omitted, and <br />excluding the those days that recorded flows exceeded the rating curve, the difficulties <br />with item 2 can be omitted. The average daily local inflow rate for August through <br />October are summarized in Table 2. Average daily local inflows ranged from 185 cfs in <br />,1993 to 249 cfs in 1992 with an average of 212 cfs for all four years. <br /> <br />Table 2 <br />Calculated Average Monthly Local Inflows (cfs) <br /> <br />Year July August September October Aug-Oct <br /> Average <br />1991 NA 208 224 189 207 <br />1992 NA 234 248 266 249 <br />1993 NA 205 188 162 185 <br />1994 187 204 217 193 205 <br />, <br />Average - 213 219 203 212 <br /> <br />Figure 10 is a flow duration curve of the daily August through October local inflows, <br />showing the probability of a certain flow being equaled or exceeded. The relatively flat <br />slope portion of the curve between 10 and 90 percent can be interpreted as the range of <br />the base local inflows. <br />