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Onr'c?8 U.cJ't . . states approaching the average annual flow (which increases the need to keep the reservoirs nearly full), there is a high probability over the next several years that flood control releases will have to be made in excess of downstream delivery requirements as has occurred during the past few years. This will be done in accordance with the Army Corps of Engineers' Hoover Dam Flood Control Regulations. During the decades since Hoover Dam was built, residential and recreational structures were built on the riparian lands along the river that had been previously subjected to flooding. Hoover Dam does provide protection from the peak flows that had formerly ravaged the ripar ian lands. However, when operating the dam to achieve the optimum balance between water conservation, flood control, and power generation under full reservoir conditions, as is now being done, Hoover Dam releases may occasionally have to be made at flow rates higher than those experienced from 1935 through 1982. This fact was brought forth in 1983 when flood control releases had to be made which adversely affected many of the structures that had been improperly located in the floodway. The Bureau of Reclamation provided information on its expected future Colorado River operations to the public in the mid to late 1970s and explained how such operations would impact developments in the floodway. The term "floodway" refers to the channel of the river and any additional area necessary to convey the design flood. Brochures delineating the floodway were published, and a report was issued in 1976 and given wide public distribution. The report indicated that flows of 40,000 cfs could be anticipated within the next 10 years, with the expected filling of Lake powell. Flood Control Regulations The Secretary of the Interior's operations for flood control are governed by the Army Corps of Engineers' Hoover Dam Flood Control Regulations. The regulations, established pursuant to the Flood Control Act of 1944 (33 U.S.C. sec. 709), have evolved with time. When there were no major Upper Basin storage facilities and when the average annual water supply far exceeded downstream demands, inflexible mandatory criteria reserved 9,500,000 acre-feet of vacant system storage space on April 1 of each year. Now, a more flexible concept enhances all project purposes while providing a degree of flood protection equivalent to that provided under the earlier criteria. The flexible concept arose with the techn ical abi 1 i ty to for ecast runoff and from per iod ic reviews of the regulations conducted by the Corps of Engineers, in cooperation with the Bureau of Reclamation and the Basin states. The most recent review and update of those regulations occurred between 1978 and 1982. -3-