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..... ,. tr' ". - - Looking upstream at Glen Canyon Dam and powerplanl GLEN CANYON DAM WATER OPERATIONS Glen Canyon Darn was authorized as a unit of the Colorado River Storage Project by Congressional Act on April 11, 1956, and construction of the dam began in the fall of 1956. Storage of water in lake Powell began in 1963. The dateo! authorization and closure of the dam preceded the 1969 National Environmental Policy Act (NEP A) and, accordingly, NEP A compliance was not required. Lake Powell first filled to its capacity at elevation 3,700 feet in 1980. In 1983 and 1984, the storage was allowed to rise above elevation 3,700 through the installation of temporary structures on the spillway gates, as temporary safety measures against higher-than-expected reservoir inflows. Lower-than-average inflows beginning in 1988 have resulted in a reservoir draw down of 64 feet as of November 30, 1990, to elevation 3,636. The dam has three means of releasing water: (l)through the powerplant, up to a capacity of about 33,200 cubic feet per second (cfs); (2)through the outlet works, with a capacity of about 15,000 cis; and, (3)over the two spillways with a combined capacity of about 276,000 cfs. Except under flooding conditions, maximum releases have been and will continue to be limited to no more than 31.soo cfs, until environmental study information is available to help determine the appropriate maximum flow. The minimum allowable releases are currently 1,000 cis from Labor Day to Easter and 3,000 cis from (Continued on page 17) NOTES ON ALTERNATIVE FORMULATION by BobMoeller(Deparlment afthe Interior Solicitor with responsibility to provide legal guidance to the EIS Team) The primary objective of the Glen Canyon Dam E15 is to evaluate the impacts of current and alternative dam operations on the dO","TlStream environmental and ecological resources of the Glen Canyon National Recreational Area and Grand Canyon National Park The EIS team has interpreted the phrase "dam operations" broadly in response to public scoping comments and in order to provide information on a yariety of potential actions. This approach facilitated the formulation of the widest possible range of reasonable alternatives as a starting point for agency and public comment. This framework constitutes an array of selected alternatives 2 containing various measures which may be selected in the formulation of reasonable alternatives to be included in the E15. The alternatives have been structured, for analytical convenience, to display impacts in a representative order. As the analysis proceeds, the EIS team may adjust an alternative if it is found that the original goals and objectives of that alternative are not being met. The EIS team elected to combine components that address the recurring scoping suggestions into various alternatives, affording the Secretary of Interior greater flexibility in arriving at the best possible decision on the future operation of Glen Canyon Dam.