Harris 2nd Qrt 07 Newsletter_7-26 (2)

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CWCB's consumptive use mo del StateCU. This will be looked at on both the demand side by this Agricultural irrigated acreage, diversions, Consumptive Group and on the supply side in the consumptive use, and shortages were identified in Supply Availability Study. the SWSI Report. There have been changes in irrigated acreage due to urbanization, water transfers, and impacts of well augmentation requirements. Irrigated acreage and updated Several roundtables have identified that the estimates of consumptive use based on high increasing demand for Colorado's limited water altitude coefficients will be made. supplies suggests the need to examine how our Limited progress was made on agricultural water water resources can be used more efficiently. One efficiency by the SWSI Phase 2 Conservation and method to maximize beneficial use is to use Efficiency TRT and this remains a significant surface and groundwater re sources in a more fully challenge. Based on initial work, there appears to integrated manner through conjunctive use be some opportunities to achieve additional management. This is a proven strategy that efficiencies in agricultural water use. However, recharges aquifers during wet periods and relies on since agricultural return flows are used by them during dry periods. Studies conducted by the downstream water users, at a watershed level CWCB and Colorado Geological Survey have shown there are significant limitations in the overall net that considerable storage exists in both alluvial potential savings that can be realized. and bedrock aquifers throughout the State. Nevertheless, since agricultural water use accounts for over 85 percent of total water use in the state, The current Gap identified in SWSI is 118,200 AF follow-up efforts should in clude this group of water based on the ability of the IPPs to address new users. CWCB and Colorado State University are demands. An update to the IPPs and the new working with the agricultural community to further demand projections out to 2050 will be used to examine these issues and opportunities. recalculate for each basin. Additional considerations of climate variability and groundwater sustainability will also be considered SWSI Phase 2 provided an extensive look at all in recalculating the Gap. Climate variability will alternatives to a traditional transfer and concluded play a role in determining the revised Gap and is that fallowing has the most potential statewide, described in detail below. In the South Metro area and may require state assistance. Interruptible it is also anticipated that aquifer production will supply strategies will also be assessed. There may decline by 40 to 80 percent by the year 2050, and be a role for the state, through the CWCB for that municipal well production will decline. example, to "level the playing field" through the Conjunctive use of available surface water supplies use of incentives to encourage M&I providers and can reduce these costs and decrease the annual users to use alternatives to traditional agricultural demand on the aquifers by 50 percent. transfers in order to foster the maximum utilization of the state's waters and to ensure that other non-market values (open space, wildlife habitat) are retained. Several roundtables have requested that this move forward. Global warming is expected to alter the pattern of water supply and use in Colorado and should be factored into any long-range planning. Global warming- based changes to supply availability can be examined by comparing projected changes in streamflow to current hydrographs at locations throughout the State, and estimating evaporative loss to reservoirs. The change in consumptive water demands in Colorado will be evaluated using the - 3 -