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SPDSS Groundwater Technical Peer Review Committee Meeting Minutes <br />February 13, 2007 <br />Page 5 <br />3. Water level trends are due to local pumping and aquifer effects. <br />c. Aquifer Water Levels Conclusions <br />i. Bedrock water levels have declined from 0 - 35 ft/yr. <br />ii. Alluvial water level trends generally stable year to year, but affected seasonally by local <br />pumping. <br />d. Aquifer Water Levels Discussion <br />i. Question: Was water level data requested from various entities, or was it just volunteered? <br />Response: Data was solicited from a large number of entities, most of whom were willing to <br />cooperate. <br />ii. Question: Why is there a decrease in number of bedrock measurements after 2004? <br />Response: This is likely due to site access issues since that time. <br />iii. Question: Expand on the alluvial water level measurement dates. <br />Response: Wells have been measured by the SEO in spring since 1988 and wells along the <br />main stem of the South Platte are also measured in the autumn. The SPDSS program has <br />focused on autumn measurements to provide a more widespread dataset with which to <br />evaluate seasonal effects. <br />iv. Questions were posed by PRC members on general water level trends, alluvial-bedrock <br />interactions, the effects of drought on water levels, gain/loss trends in the rivers over time, <br />and the effects of having the bedrock aquifers transition from confined to unconfined <br />conditions in localized areas. The Technical Memoranda discuss regional water level trends <br />in both the bedrock and alluvial aquifers but the detailed questions on localized areas are <br />beyond the scope of the water level characterization reports. <br />5. Task 41 - M&I Pumping Estimates <br />a. Pumping rates >500 gpm wells and pumping rates >1000 gpm wells. <br />b. Water rights pumping -1950 to 2005, fill data. <br />c. Generally - 1000 - 3000 of per year in alluvial aquifer. Not very high, small compared to <br />agricultural pumping. <br />6. Task 48 and 50 -Alluvial Aquifer Modeling Overview <br />a. Regional model used for planning purposes. To model effects o£ pumping and water transfers <br />on stream depletions/accretions; interaction of bedrock and alluvial aquifer; effects of irrigation <br />efficiency on stream. <br />b. Phase 3 -model precalibration (i.e. model framework). Intended for March 2007. <br />c. Phase 4 -fully calibrated model. Intended for May 2008. <br />