In the 1970's the effects of Glen Canyon dam flows on the downstream ecosystem began to be noticed. Vigorous concern for these ecological impacts, largely from environmental organizations like the Sierra Club, prompted the Bureau of Reclamation to launch scientific studies on dam operations dubbed "Glen Canyon Environmental Studies phase 1." These studies ascertained that dam operations produced adverse effects on the ecosystem. In 1989, a grassroots political campaign forced Interior Secretary Manuel Lujan to order an extensive Environmental Impact Study on the operations of Glen Canyon Dam. Based on the Department's findings, "interim flows" were instituted in 1991 to slow the damage. According to the Glen Canyon Trust, however, these actions were primarily stopgap measures conceived to prevent more restrictive changes to dam operations from occuring.
Grassroots pressure yielded significant change in 1992 by pushing Congress to pass the Grand Canyon Protection Act which directed the operation of the dam "in such a manner as to protect, mitigate adverse impacts to, and improve the values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established, including, but not limited to natural and cultural resources and visitor use" (Title XVIII--Grand Canyon Protection, sec. 1801 a). Under the Act, the Secretary of the Interior is required to "implement Operations in consultation with appropriate agencies of the Department of the Interior, including the Bureau of Reclamation, United States Fish and Wildlife Service, and the National Park Service; The Secretary of Energy; The Governors of the States of Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming; Indian Tribes; and the general public, including representatives of the academic and scientific communities, environmental organizations, the recreation industry, and contractors for the purchase of Federal power produced at Glen Canyon Dam" (Title XVIII Grand Canyon Protection, sec. 1802, 1-5). The Act also includes a "Final Environmental Impact Statement" (FEIS) to ensure that long-term operation of the dam is in compliance with the stated intention to operate the dam for the benefit of the river's natural and cultural resources.
In 1994 the Draft Environmental Impact Statement (DEIS), prepared by six Native American tribes, five federal agencies and the Arizona Game and Fish Department, outlined nine choices for flow restrictions and concluded it would be best to continue with the 1991 restrictions. In addition, the Bureau would stabilize flows in the spring, summer, and fall of low-water years to try to help endangered fish populations. The limited flows would affect the amount of power generated, necessitating customers of the Western Area Power Administration to use other sources for their peak power. According to the Bureau, benefits to the Colorado River and the Grand Canyon would be significant, as "‘sediment would accumulate in the river system and long-term beach degradation would stop. . .streamside vegetation would stabilize. . . [and] cultural resources, including archeological sites and traditional cultural properties important to Native Americans, would be protected. Flows would favor river runners while protecting the beaches necessary for camp sites'" ("BUREC," 1994). American Rivers called the DEIS a "significant step in protecting the environment of the Grand Canyon" ("American," 1994). In addition, American Rivers noted that the DEIS represented both a "change in thinking about how the Bureau approaches water resources and water management in the West, and an acknowledgment that the Bureau will mitigate the impacts of their dams and water project operations on the river ecosystems of the West" ("American," 1994). The Final Environmental Impact Statement, issued in 1995, called for the leveling out of wide daily fluctuations in water flow from Glen Canyon Dam to lessen the downstream effects. Debate then ensued from a range of groups. The Grand Canyon Trust argued that the 1991 restrictions "don't go far enough"("Fight," 1995). The Salt Lake City-based Colorado River Electrical Distributor's Association (CREDA), representing 150 non-profit utility companies, however, lobbied for easing tighter flow restrictions ("Fight," 1995). Congressman Jim Hansen (R-Utah) warned that the DEIS showed that "very little thought has been given to the cost to the environment of replacing clean hydro power with power generated from the burning of fossil fuels" ("Final," 1995). Following the EIS, the General Accounting Office (GAO), as mandated under the Grand Canyon Protection Act, reviewed the costs and benefits of alternatives included in the EIS. The GAO's findings, as released on October 3, 1996, supported the EIS.
On October 9, 1996, Interior Secretary, Bruce Babbitt, signed a "record of decision," making permanent the changes first ordered in 1991 aimed at minimizing erosion downstream. According to Babbitt, the new measure begins a "new chapter in the fabled history of the Grand Canyon and Glen Canyon Dam," marking a "sea [of] change in the way we view the operation of large dams. We have shown they can be operated for environmental purposes as well as water capture and power generation" (Kenworthy, 1996). Babbitt also announced the results of the man-made flood, provided for in the EIS, which took place for two weeks from March 22nd to April 7th of 1996. The flood was executed in order to stir up collected sediment at the bottom of the river and then redeposit it on the river's shores to rebuild beaches, sand bars and habitat for threatened and endangered species. Babbitt reported that the flood resulted in "significant improvement in the size and number of the river's beaches" and "creation of backwater habitat for endangered species" ("Grand," 1996). However, several groups continued to oppose the flood despite its apparent success. River guides felt that Glen Canyon's non-native trout fishery was being "sacrificed for the better known Grand Canyon" ("Grand," 1996) and nine native american tribes were concerned that the floods could damage 470 cultural and religious sites along the river ("Grand," 1996).