ARCA 2015 Annual Meeting Exhibits

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sized flow peak of approximately 4,000 cfs was measured on Fountain Creek. The release rate from Pueblo Dam was cut from over 5,000 cfs to less than 700 cfs to minimize the flood impacts of the Fountain Creek peak as it passed through the middle valley of the Arkansas River Basin. As a result of the increased rate of storage when Pueblo Dam outflow was cut, storage climbed into the Flood Pool early in the morning of June 13. By the morning of June 14, releases from Pueblo Dam had been brought back up to 4,850 cfs, but inflows to the project were over 6,000 cfs. Late in the evening of June 15, a very significant rain event in the Colorado Springs area resulted in a peak of over 18,000 cfs on Fountain Creek. This peak triggered another cut in releases from Pueblo Dam and reservoir storage was driven higher into the Flood Pool. By June 18, the Arkansas River above Pueblo Dam peaked at over 7,000 cfs and began a gradual decline, but the pool at Pueblo Dam continued to rise towards the historic pool of record. As a result of recent experience with large flow peaks in the middle Arkansas River valley, it was determined that the system could handle flows in excess of 6,000 cfs at Avondale. The decision was made to increase releases out of Pueblo Dam above the published channel capacity in an effort to slow, and possibly stop, the rise in the flood pool. Before making the planned increases, a monitoring plan was established for four locations on the Arkansas River which have typically been sensitive to high river stages. On June 19, USACE increased Pueblo Dam releases by 500 cfs, resulting in 6,500 cfs at the Avondale Gage. A second 500 cfs increase was made on June 20, and the pool elevation at Pueblo Dam pool began to level off. Pueblo Reservoir storage peaked at elevation 4,887.4 ft on June 22, nearly 7 ft within the Flood Pool. Over the next several days, the weather was closely tracked along with the previously identified monitoring points along the middle valley. During this same period, Pueblo Dam's pool began to drop. On June 24, after several days of high sustained flows on the Arkansas River, Pueblo Dam's release was reduced by 500 cfs to reduce river stage and ease pressures along the Arkansas River. The levee system in La Junta was showing signs of distress and localized inundation of lowlands in the Avondale area were reported. Another cut was made on the June 25, and the basin was allowed to recover for several days. By the June 29, the weather had turned hot and dry. Pueblos Dam's outflow was increased by 500 cfs to accelerate the evacuation of Pueblo Dam's Flood Pool. Shortly thereafter, notice was received that diversions along the middle valley would be reduced as off-system reservoirs in the basin reached capacity. This reduction in diversions would occur upstream of La Junta, and it would essentially put over 800 cfs back into the Arkansas River. Pueblo Dam outflow was cut by 500 cfs on July 1 to reduce the threat to the La Junta spoil bank levees. The Fort Lyon Storage Canal reduced their river diversions by 200 cfs on July 1, and then by an additional 150 cfs on July 2, returning a total of 350 cfs to the river. Arkansas River stages at La Junta continue to stay within acceptable levels, and the July 1 cut from Pueblo Dam was 2