Laserfiche WebLink
360 <br />115FE.W <br />UTAH 1— <br />ARIZONA dam, Lake Powell <br />09382000 <br />Glen Canyon Dam <br />iQ <br />a Lees Ferry <br />AZ (09380000) <br />J � <br />RM30 <br />T <br />C <br />�II <br />V <br />Zi0 <br />09402300 <br />RM61 <br />C %� 1z, <br />RM8 Qa. vIt, <br />ob11 <br />0 km S0 % <br />`P <br />0 miles 30 <br />Figure 1. Colorado River below Glen Canyon Dam (GCD). Lees Ferry is designated river -mile (RM) 0 and is <br />about 15.5 miles downstream from the dam. RM 30, RM 61, and RM 87 denote model nodes and are labeled <br />according to river miles downstream from Lees Ferry. 8 -digit numbers denote U.S. Geological Survey gaging <br />stations referenced in the text. <br />Glen Canyon Dam Flow Release Scenarios <br />Six scenarios for GCD hourly release hydrographs were identified through discussions with the GCDAMP Technical <br />Work Group. For each of the six hourly release scenarios, two annual release volumes were evaluated, that is, two <br />possibilities for the total volume of water to be released in WY 2011 (for a total of 12 simulations). Based on the April 2010 <br />24 -month study from the Bureau of Reclamation (http: / /www.usbr.gov /uc /water /crsp /studies/24Month 04.pdf, accessed May <br />4, 2010), the most probable annual release volume was 11.0 million acre -feet (MAF). For comparative purposes, we also <br />evaluated an annual release volume of 8.23 MAF because this volume has been the most common release volume over the <br />past decade during multi -year drought conditions (8 of 9 water years from 2001 to 2009, based on data from Lees Ferry, U.S. <br />Geological Survey station 09380000). Figure 2A shows the expected pattern of monthly release volumes for current <br />operations, known as Modified Low Fluctuating Flows (U.S. Department of the Interior, 1995) for the two annual release <br />volumes. The pattern of monthly volumes for 11.0 MAF is based on the April 2010 24 -month study, while the pattern for <br />8.23 MAF is based on historical data and available synthetic hydrographs, discussed in more detail below: <br />