Modelos de parámetros tecnológicos en SiC

Between the 1930s and the 1970s, many multipurpose dams and reservoirs were constructed in the Colorado River basin in an effort to smooth natural variations in the river’s flows and to store flood waters for use during drier periods. The prototype of these structures was Hoover Dam. The Colorado River Storage Project (CRSP) of 1956 represented another water development milestone as it authorized construction of Glen Canyon Dam (in Arizona near the Utah border), Flaming Gorge Dam (on the Green River in Utah near the Wyoming border), Navajo Dam (on the San Juan River in New Mexico near the Colorado border) and the multidam Wayne N. Aspinall Storage Unit (on the Gunnison River in western Colorado; see http://www.usbr.

gov/dataweb/html/crsp.html). The CRSP represented the zenith of

large-scale dam construction across the basin. Following the 1956 passage of CRSP and the construction of its authorized projects, new factors in the planning of western water resources began reducing the prospects for new projects. A burgeoning environmental movement in the post-World War II era raised awareness of environmental changes wrought by dams, leading in part to the defeat of proposals to build dams at Echo Park in Dinosaur National Monument (in the 1950s) and at Bridge and Marble Canyon near Grand Canyon Na- tional Park in the 1960s (Nash, 1967; Reisner, 1986). The trend to- ward fewer traditional, structural western water projects continues today, as the best sites for storage reservoirs have been developed and as concerns have grown over environmental impacts of large dams, both in the Colorado basin and elsewhere (see WCD, 2000). Some water storage and delivery projects were completed in the 1980s and 1990s, perhaps most notably the Central Arizona Project in 1992, but the declining trend of the viability of traditional water projects has been clear.

In addition to environmental and other concerns related to large dams, traditional water projects today face a more stringent series of planning and feasibility studies and other obligations than in the past, which can entail literally decades of project planning and related ac- tivities. (Box 4-1 discusses the Animas-La Plata project in south- western Colorado, which is an example of the complexities that sur- round contemporary dam authorization, appropriation, and construc- tion.) In efforts to augment water supplies, some basin states and

BOX 4-1

The Animas-La Plata Project

Congress authorized the Animas-La Plata project in 1968, calling for a multipurpose dam project to serve a range of agricultural, munici- pal, and industrial uses in southwestern Colorado. Today, 37 years af- ter project authorization, the Bureau of Reclamation’s Animas-La Plata project is under construction. Although scheduled for construction in the early 1980s, discussions were initiated to achieve a negotiated settle- ment of water rights claims of the Southern Ute Indian and Mountain Ute tribes in southwestern Colorado. Following negotiations, a settle- ment of water rights claims held by these tribes was agreed to in a Final Settlement Agreement, signed on December 10, 1986.

In 1990, the U.S. Fish and Wildlife Service issued a draft biological opinion regarding the federally endangered Colorado pike minnow and how it might be affected by Animas-La Plata. A final biological opinion was issued in 1991, which allowed for construction of several Animas- La Plata project features, but limited annual project depletions to 57,100 acre-feet while an endangered fish recovery program was conducted. After the U.S. Bureau of Reclamation was authorized to initiate con- struction, several challenges were made to the completeness of Recla- mation’s 1980 final environmental impact statement, and in 1992 legal actions brought by environmental organizations halted construction. Reclamation worked with the Fish and Wildlife Service to address new biological information, and in 1996 the Service issued a biological opin- ion with a reasonable and prudent alternative limiting project construc- tion to features that would initially result in an average annual water de- pletion of 57,100 acre-feet. Construction of the Ridges Basin Dam, the centerpiece of the Animas-La Plata Project that will impound 120,000 acre-feet, began in 2005. The reservoir, to be named for former Colo- rado Senator Ben Nighthorse Campbell, is expected to be filled in 2011.

The history of the Animas La-Plata project reflects how difficult it can be for western water projects to move from planning to construction. The process today is far more complicated than during the 1950s and 1960s. Although future storage dams may be built within the Colorado River basin, the Animas-La Plata experience offers little evidence that they will be built quickly.

SOURCES: http://www.usbr.gov/uc/progact/animas/background.html;

municipalities may still wish to pursue the option of constructing a new water storage reservoir(s). Viable prospects for new project con- struction in the near to medium term, however, are limited: “Except for the Central Utah Project, as recently modified by Congress, and perhaps the Animas-La Plata Project, it seems unlikely that other ma- jor water storage facilities will be constructed in the Colorado River Basin in the foreseeable future” (MacDonnell et al., 1995). Although a diversion dam on the Virgin River has been discussed, there is no current proposal to build such a project, and it is one of the few dam projects that has even been discussed in the basin in recent years.

An interesting chapter in the history of efforts to augment Colo- rado River basin water supply storage involves various plans to im- port water from outside the basin. The most ambitious of these was the North American Water and Power Alliance (NAWAPA), an engi- neering scheme proposed in 1964 by the Ralph M. Parsons Company of Pasadena, California. The plan envisioned moving large quantities of water from water-rich regions of Alaska and the Canadian Yukon to the arid western United States through a complex system of reser- voirs, tunnels, pumping stations, and canals. Dams were also to gen- erate hydropower, sales of which were to help finance project con- struction. The Parsons Company 1964 cost estimate was $80 billion, adjusted to $130 billion in 1979. The price tag in today’s dollars would undoubtedly be in the hundreds of billions. Political and envi- ronmental objections would also impede, and likely block, attempts to revive even a scaled-down version of the NAWAPA scheme. Simi- larly, prospects of towing icebergs south from Alaska or other arctic regions to augment Colorado River water supplies are equally unreal- istic. Declining prospects for traditional water supply projects are perhaps more correctly seen not as an end to “water projects” but as part of a shift toward nontraditional means for enhancing water sup- plies and better managing water demands. The following sections of this chapter examine some nonstructural and nontraditional means of augmenting water supplies.