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Flooding along the Salt, Gila, Verde, and Agua Fria Rivers in February and March of 1978 resulted in extensive damage to property in Central Arizona and in the disruption of ground transportation and commerce in the greater Phoenix area. Major flooding also occurred along these rivers in December, 1978 and February, 1980. The recognition of this flooding problem, and of requirements for the regulatory storage of Central Arizona Project (CAP) water, prompted the U.S. Department of the Interior, Bureau of Reclamation (Reclamation) to initiate the Central Arizona Water Control Study (CAWCS) in July of 1978. The objectives of the CAWCS were to identify and evaluate alternative measures for flood control and regulatory water storage in Central Arizona. Both structural (i.e., dam construction or modification, levee construction), and nonstructural (i.e., flood proofing, flood plain regulation, water exchange) alternatives were to be considered within a large study area. A Safety of Dams (SOD) issue was subsequently recognized and incorporated in the CAWCS study process. As the study progressed through a consideration of eight alternative plans, a preferred alternative (the agency-proposed action) to address these objectives was selected by Reclamation. Several critical factors were considered in comparing alternative plans, and in defining the preferred plan alternative, including: - flood control performance of a plan - regulatory water storage performance - dam safety - economics (cost/benefits) - environmental impacts - social impacts - institutional constraints Each of these factors was thoroughly evaluated in relation to the plan alternatives during the three stage study process. Stage I established the parameters of the flood control and regulatory water storage problems to be addressed, defined a number of actions (termed elements) which might contribute to the resolution of these problems, and recommended specific actions that warranted further study on the basis of their performance characteristics. Of the 34 elements reviewed during Stage I, 20 were recommended for further consideration at a Stage II level of analysis. During the Stage II analysis, competing elements (those which served similar functions but which were at different locations) were compared in order to define and retain those which best served a particular function. These 10 remaining elements were then combined into 13 intermediate plans, termed systems, each of which could provide for flood control and regulatory water storage. At the beginning of Stage III, 10 elements remained in the study. These were combined into seven candidate plans, each of which satisfied flood control, safety of dams, and regulatory water storage objectives. An eighth plan (No Action) was also defined as a basis for evaluating the effects of a proposed undertaking. As the critical factors were considered in relation to each plan, two of the eight plans (numbers 4 and 5) were eliminated due to cost and associated adverse social and environmental effects. The remaining six plans were analyzed in detail; one plan (dubbed Plan 6) was subsequently identified as the agency-proposed action. In undertaking this study, Reclamation contracted with the firm of Dames and Moore to assist in defining and evaluating the alternative plans, and to prepare a draft environmental impact statement for the agency-proposed action. Archaeological Research Services, Inc., and the Arizona State University, Department of Anthropology (Office of Cultural Resource Management) were under subcontract to Dames and Moore for the historic and prehistoric cultural resource aspects of the CAWCS respectively. The historic cultural resource study was initiated in April, 1979, and concluded in December, 1981, and involved preparing reports and supporting documentation relative to each of the study stages above. For the purposes of this study, historic cultural resources are defined as those sites or properties which were occupied after the time at which written records became available for an area. As applied to the Southwestern United States, historic sites may include those in existence at or subsequent to the period of initial Spanish contact (during the 16th century). |
