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<br />although the mean daily flow hydro graph (Figure 7) shows a much higher average. This is due to <br />the skewing effect of the extremely high flows in wet years. <br /> <br />The filling of an enlarged Red Mesa Ward Reservoir would follow the current procedures but the <br />duration of the diversion would be extended. The filling of the reservoir takes place only during <br />the non-irrigation season and during the high spring flows when there is no call3 on the river. <br />Any extended diversion would therefore come on the 'shoulder' of the hydrograph. The canal <br />leading to the reservoir has a capacity of 120 cfs and will not be enlarged. Thus, there would be <br />minimal effect to the high spring peak over and above what is presently occurring. This <br />additional diversion, while potentially significant, comes during a time when peak flows are <br />present, which, when combined with the flashy nature and high sediment carrying capacity of the <br />La Plata River system, will continue to allow effective native riparian species recruitment in the <br />MA. Peak flows in Cherry Creek, a major tributary just upstream of the MA would not be <br />impacted and would still provide flushing flows through the MA regardless of possible impacts <br />to the mainstem flows. <br /> <br />The extended diversion period into the enlarged Red Mesa Ward Reservoir would not likely <br />reduce the current channel maintenance flow frequency of occurrence due to the very high flows <br />that have historically occurred on the La Plata River System on an approximate four-year cycle. <br /> <br />3.2.2.1.3 Red Mesa Enlargement Impacts to the MA Assessment Conclusion <br /> <br />The conclusion from this discussion is that an expansion of Red Mesa Ward Reservoir could <br />have some affect on the duration of the high flows through the mitigation area, but would provide <br />an opportunity for more irrigation return flow and ground water to reach the mitigation area <br />increasing groundwater re-charge to the river bottom alluvial aquifer during low La Plata River <br />flow periods. <br /> <br />Regarding peak flows and channel maintenance, the operation of this reservoir expansion project <br />would not prevent high flows in wet years from providing stream channel maintenance flows as <br />discussed above, but in marginal years might prevent the full 85 cfs from flowing for a full week. <br />This is not likely to affect the channel maintenance flow frequency (approximately 1 year in 4) <br />through the MA, as this estimate is based on high flow years. This does not remove the <br />possibility that during infrequent marginal years the target channel maintenance flows would not <br />be reached due to the operation of an expanded reservoir. On dry years the diversion would make <br />no difference since diversions to the reservoir would be out of priority early in the year. <br /> <br />If for some reason Red Mesa Ward Reservoir is not operated as presently envisioned and it is <br />determined that there would be significant negative impacts to flows through the MA from a Red <br />Mesa Ward Reservoir Enlargement, Reclamation will augment supplies to ensure that adequate <br /> <br />3. A senior water right places a call on the river because a junior water right is diverting <br />and the senior water right cannot divert its allocated amount. <br /> <br />-25- <br />