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<br />001672 <br /> <br />Operation Plan for the Proposed Long Hollow Reservoir-Preliminary Draft, March 17, 2004 <br /> <br />characteristics along the La Plata River. Flows typically hover between 5 and 8 cfs at Hesperus <br />and 2 to 5 cfs at the Colorado-New Mexico state line. <br /> <br />3.2 Split River Flow Conditions <br /> <br />During most years and after spring runoff, the La Plata River becomes dry along a reach from the <br />Town of Breen to Cherry Creek. Two additional ramp flumes were installed on the La Plata <br />River during late 2001 and were operational in mid-April 2002.. One is located near Breen (C.R. <br />122) and the other immediately below Cherry Creek (C.R. 100). Hydrographs of daily flows <br />show that the La Plata River was dry from June 19,2002 to December 31,2002 and from July 5, <br />2003 to August 11,2003 at Breen (see Figure 5), and from June 4,2002 to March 12,2003 and <br />from July 7,2003 to August 11,2003 below Cherry Creek (see Figure 6 ). <br /> <br />The low flows at Hesperus and the losing nature of the La Plata River streambed can present <br />administrative challenges to Colorado. The "Breen Hole" divides river flows into upper and <br />lower sections. At these times the river is administered as a split river. The average annual <br />balance of Compact deliveries under split river administration during the study period was <br />calculated to be a debit of 69.8 AF/yr, with a range of 537.9 credit to 560.7 debit. Table 1 shows <br />~ ~ <br /> <br />these values and lists the periods between 1989 and 2002 that split river conditions existed. This <br />operation plan has reserved a 300-AF pool in LHR to help to make up Colorado's Compact <br />-- ~ <br /> <br />debits during split river conditions. <br /> <br />3.3 Compact Reserve Pool <br /> <br />The Compact Reserve Pool amount was determined by calculating the average amount of annual <br />debit that occurred in water delivery to New Mexico under split river administration conditions <br />for WY 1989 through WY 2002 (see Table 1). The average annual debit during this period was <br />224.9 AF. Accounting for estimated annual evaporation of _ AF from this pool results in a <br />total pool of 300 AF. It should be noted that there are annual average credits of 155.1 AF during <br />split river conditions and that the average annual balance is a 69.8 AF debi~. Notwithstanding <br /> <br />991-077.000 <br />March 2004 <br /> <br />Wright Water Engineers, Inc. <br /> <br />Page 3 <br />