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~ C": ~ ,~ ~~,;~;;~":;.: ~ -:.-... . c on l. January. A maximum average monthly rel.ease 01' 77,000 cubic 1'eet per second was made during June 8Dd Jul,y. On l. August, 1'l.ood-control storage space slightly in excess 01' the required l.,500,000 acre-1'eet was availabl.e in Lake Mead. 35. Routing of l.9l.7 spriDg SDOWlllelt flood.--The l.9l.7 spring snOWlllel.t tl.ood was routed throush lake Mead by the Bureau of Reolalllation as shown on plate 5, using the current operation plan. It was ass\lIIIed that 1;I1e ...yh.... inf'l.ow torecast was the S81118 as the actual. intl.ow. It was also ass\lllllld that the m1n1mum necessary tlood-control. storage space bel.ov el.e- vation l.,229 of 1,500,000 acre-feet in Lake Mead, and a total of 5,350,000 acre-teet incl.ud1ng storage at upstre_ dams, was ava1J.abl.e on 1. January. A _n- average monthly releasa ot "5T,000 cubic teet per second was _de during June and July. On 1 August, the required l.,500,000 acre-feet ot tlood-control storage space was available in Lake Mead. 36. Routio.. the ",y"-- probable spring tlood.--The "'''''IM1Jll probable spring flood (table 3) was originally developed during studies pertaining to the Bridge Canyon De.m site. The flood was routed through Lake Mead by the Bureau of Reclalllation as shown on plate 6, using 1;I1e ourrent operation plan. It was ass\lDled that the m1n1mUII necessary tl.ood-control storage space below el.evatioD 1,229 ot 1,500,000 acre-teet in Lake Mead, and a total ot 5,350,000 acre-teet including storage at upstre_ dams, was avail.- abl.e on 1 January. A max1lllulll average monthly release ot 75,000 cubic feet per second was made during the months ot April. throush July. It _y be noted that the necessary l. August tlood-control. storage space below ele- vation l.,229 was less than l.,500,000 acre-teet in JUDa and July, but was avaiJ.able by 1 August. 37. Routing the 1IIBx1mum probable rain tl.ood. --For development 01' the 1IIBn- probable rain tlood (table 4), data and COlllpUtations assembled tor the Bridge Canyon spillway design flood study of September 1951 vere used. Maximum possible precipitation val.ues vere obtained from the U.S. Weather Bureau I s ~OIIIeteorologic:aJ. Section. That portion ot the 1'lood origina- ting above Glen Cauyon D8111 was routed through the daa and combined with the portion originating below the dam. This theoretical. tl.ood was routed throush Lake Mead by the Bureau ot Reclamation as shown on plate 7, using the current operation pJ.an and assllll1ng the reservoir tulJ. to the top of the spillway gates in the raised position (1,218,000 acre-teet of storage space bel.ov elevation l.,229 feet). The ....y........ release as determined froll table 7 ot Appendix A was 86,500 cubic teet per second. 38. Routing the standard project rain tl.ood.--A standard project rain flood was developed by the Bureau ot Reclamation, using the three J.argest rain floods recorded in the area. The hydrographs ot these flooda were superimposed and a combined hydrograph prepared, with daily tlows arranaed in a standard pattern. Assuming releases from Gl.en Canyon De.m woul.d be l.1III1ted to lJ<:Nerplant capabil.1ties, the Bureau routed the tl.ood throush Lake Mead as snvwu on plate 8. Using the current operating plan and assUllling l.3