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the case, then this also raises reasonable questions regarding other Illustrative Tool <br />average-year assumptions - for example, do development trends in the southern part of <br />the South Platte basin (south of Denver) still support the initial Illustrative Tool <br />assumption that non-tributary groundwater development will be the source of 50% of <br />new water supplies in an average year? (and 70% in a dry year?) <br />In summary, Colorado's report raises the following questions for me: <br />Is Colorado obligated under the Program to replace/re-regulate water to offset <br />depletions each year relative to average-year conditions, or relative to recent <br />conditions in the basin (wet, average, dry)? (My understanding is the former, but <br />I could be wrong). <br />If Colorado's offset obligations are to be determined relative to the average-year <br />condition, then: <br />Is their proposed adjustment to the Illustrative Tool's water supply from native <br />flows and from water re-use justified for the "average year" based on recent data <br />from a drought period? <br />If the answer to the above is "yes", then do we also need to re-visit the assumed <br />average-year distribution of water supplies derived from the other four sources of <br />water supply in Colorado's Illustrative Tool, also using recent data? (For <br />example: are the assumed percentages of water supplied by non-tributary <br />groundwater still accurate?) <br />If Colorado's offset obligations are to be determined relative to recent hydrologic <br />conditions in the basin (e.g., using a four-year rolling average, as suggested on page 5 <br />of their report), then: <br />Will offsets be determined in this manner only "if the drought continues", or <br />under all conditions, both wet and dry? <br />¦ If applied under all conditions, then will Colorado have the physical capacity to <br />replace the corresponding net depletions occurring in May, June, and/or other <br />months if the South Platte basin experiences a series of unusually wet years? <br />Colo Cumulative Effects 2007 DMA comments.doc <br />2