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CJ c; N c...;. '--.' CHAPTER IV CONSULTATION AND COORDINATION c:~) recharge of the ground-water aquifer in the spring, this return flow occurs as'a steady flow. An estimate of the flow rate currently returned to the river can be obtained by converting the 610 and 1,005 acre-feet of irrigation system seepage into flow rates by dividing this volume into a uniform flow over the irrigation season. Doing so results in an equivalent flow rate of 1.5 cfs for the Stubb Ditch seepage and 2.5 cfs for the Price Ditch seepage. The "saved" or "salvaged" water from the proposed improvements would be reallocated to 1) increased tailwater from irrigated fields, 2) increased crop consumptive use, and, 3) increased administrative spills. Water distribution records indicate about 44 percent of the water entering the canal systems is delivered to the farm. With an average on-farm efficiency of 43 percent in the Grand Valley, about 19 percent (43 percent of the 44 percent) of the water delivered to the farm is consumptively used. If the irrigation distribution systems are capable of picking up and delivering the saved water and if the timing of the availability of the saved water coincides with on-farm demand, then the consumptive use of the saved water could approach 19 percent. It is unlikely that all of the saved water will meet the above criteria. However, if all of the above criteria are met (creating the highest use of the seepage water) the maximum potential consumptive use associated with the saved water would be 0.3 cfs for the Stubb Ditch and 0.5 cfs for the Price Ditch. This increase in supply should not result in more on-farm seepage, since increased water supply usually results in higher application rates and a corresponding decrease in on-farm seepage. Both the Mesa County Irrigation District and the Palisade Irrigation District are land- locked and have contractually agreed not to use any saved water to irrigate new lands. Except for the increased consumptive use, the balance of the saved water from both systems will return to the Colorado River. It is anticipated that since it will be possible for some of the tailwater and administrative spills to enter into other irrigation systems, the location of the return flow will be further downstream on the Colorado River than is currently the case. -Mr.Skinner asked about costs of litigation concerning saved water. Litigation costs, if they occurred, would be considered part of normal O&M expenses. As such, if these expenses, along with other O&M expenses, exceeded the districts' agreed upon base O&M expense, the cost would be reimbursed. -Ms. Hutchins questioned whether salt tonnage and cost estimates for both the Price and Stubb Ditches reflect the existing improvements on these ditches. Both the costs and tonnage estimates in the assessment reflected the existing improvements. Table 1 in the assessment has been modified to clarify this. -Ms. Hutchins asked how the capacity of the Price Ditch could be in question when the known Palisade Irrigation District's water right is 80 cfs. Palisade Irrigation District's senior water right is 80 cfs, but they also have a junior water right for about 23.5 cfs. The size of the Price Ditch is in question because a portion of the Price Ditch water right is delivered directly from the Government Highline Canal. The final allocation of PIO's water between the Government Highline Canal and the Price Ditch has not been resolved. Additionally, the amount of tailwater and runoff flowing into the Price Ditch from irrigated land to the north is not known. It will be necessary to size the canal to accommodate these flows. 39