Laserfiche WebLink
<br />Flood Control <br /> <br />Lake Mead is operated in accordance with updated flood <br />control regulations which are specified in the Field Working <br />Agreement between Reclamation and the Corps of <br />Engineers, signed in 1982. The regulations stipulate the <br />minimum release levels needed from Lake Mead to route <br />the reasonable maximum inflow. The reasonable maximum <br />inflow is the estimated inflow volume that, on the average, <br />will not be exceeded 19 out of 20 times. This volume is <br />derived by adding an "uncertainty" term to the most probable <br />runoff forecast. In 1983, unusual hydrometeorologicaI events <br />resulted in unprecedented large forecasting errors. <br />Subsequent reassessment of the estimate of the 'uncertainty" <br />term led to adoption of larger values for use in determining <br />the reasonable maximum inflow in 1984 and thereafter. <br /> <br />Due to the amount of vacant storage space in Colorado <br />River reservoirs, no flood control releases are anticipated in <br />1994, but in future years, as Lake Mead refills and flood <br />control releases are again required by the Hoover Dam <br />Flood Control Regulations, consideration will be given to <br />making those releases over the fall and winter months to <br />avoid high flow rates during the January to July runoff <br />season. This distribution of water reduces the chance of <br />bypassing hydroelectric powerplants below Hoover Dam and <br />avoids the adverse im pacts of higher flood control releases <br />on fish and wildlife, recreation, water quality, and river <br />stabilization. <br /> <br />Routine maintenance of bankline protection 'facilities were <br />carried out during water year 1993. As in the previous years, <br />greater than normal bankline repair was necessitated in part <br />by increased wave action from boating and other recreational <br />river traffic. During water year 1993, the river channel in <br />the Lower Basin has remained in good balance, neither <br />aggrading nor degrading significantly in any particular reach. <br /> <br />Total Colorado River reservoir system storage at the start of <br />water year 1993 was approximately 50.8 billion cubic meters <br />(41.2 million acre-feet) and about 59.7 billion cubic meters <br />(48.4 million acre-feet) at the end of the water year, <br />representing a 8.9 billion cubic meters (7.2 million acre-foot) <br />decrease in total remaining available reservoir space. <br /> <br />Both Alamo and Painted Rock dams on the Bill Williams <br />and Gila Rivers (in the Lower Basin) respectively, received <br />significant flood inflows during water year 1993. During <br />water year 1994, the Corps of Engineers flood control <br />facilities; Painted Rock (Gila River) and Alamos Reservoirs <br />are expected to be operated in accordance with Reclamation <br />project releases and established flood control criteria to <br />maximize the available flood control space in their respective <br />reservoirs. <br /> <br />22 <br />