Glen Canyon Environmental Studies - Phase I (1982-1988)
Phase I of the Glen Canyon Environmental Studies (GCES), conducted from 1982 to 1988, was a major scientific research program launched by the U.S. Bureau of Reclamation to evaluate how dam operations affected the downstream ecosystem of the Colorado River.
Key Details of Phase I
- Purpose: Assess the short- and long-term impacts of Glen Canyon Dam operations on downstream resources, including vegetation, wildlife, fisheries, recreation, and sand beaches.
- Main Findings: Scientists discovered that rapid daily water fluctuations and high-volume releases from the dam were causing significant damage to downstream environments, native habitats, and cultural resources.
- Conclusion and Next Steps: Phase I concluded in 1988 with a final report. The alarming evidence gathered directly triggered Phase II in 1989 and forced the Secretary of the Interior to order a comprehensive Environmental Impact Statement (EIS) to reform dam management.
Glen Canyon Environmental Studies - Phase II (1988-1988)
The Glen Canyon Environmental Studies (GCES) Phase II was a major scientific research program conducted in the 1990s to evaluate how the operations of Glen Canyon Dam affected the downstream ecosystem of the Colorado River through Glen and Grand Canyons.
Key Aspects of GCES Phase II
- Purpose: Launched by the Bureau of Reclamation following Phase I, Phase II gathered comprehensive data to understand the physical, chemical, and biological impacts of dam releases (such as fluctuating flows for power generation) on beaches, native fish, and cultural resources.
- Scientific Integration: It integrated diverse scientific disciplines—including hydrology, sediment transport, aquatic ecology, and terrestrial biology—to create experimental high flows and steady flow tests.
- Legacy and Outcome: The extensive data and environmental assessments produced during Phase II directly provided the scientific foundation for the 1996 Glen Canyon Dam Environmental Impact Statement (EIS) and the subsequent establishment of the Glen Canyon Dam Adaptive Management Program (GCDAMP).
National Research Council workshop on Colorado River (1989)
In 1989, the National Research Council (NRC) sponsored a pivotal symposium/workshop that reviewed existing scientific knowledge on the Colorado River ecosystem.
Context and Core Focus
This workshop was a critical milestone in the history of the Glen Canyon Dam Adaptive Management Program (GCDAMP). Prior to this, Phase I of the Glen Canyon Environmental Studies (GCES) (spanning 1982–1988) had revealed that the daily fluctuating water releases from the Glen Canyon Dam were causing significant degradation downstream. This included the erosion of sandbars used for campsites and the destruction of critical habitats for native and endangered fish in the Grand Canyon.
The 1989 NRC workshop brought together scientists, resource managers, and policymakers to synthesize what was known about these human-induced ecological impacts.
Historical Significance & Outcomes
- Catalyst for Policy Change: The symposium coincided with a major turning point. In July 1989, Secretary of the Interior Manuel Lujan used these compounding scientific concerns to formally order a comprehensive Environmental Impact Statement (EIS) on Glen Canyon Dam operations. This marked the first time a retroactive EIS was mandated for an active, major federal dam.
- Transition to Phase II: The workshop helped structure the scientific hypotheses for Phase II of the GCES (1989–1996), shifting the focus toward integrated ecosystem modeling and formal adaptive management.
Formative discussions on the concept for HFEs (1990-1995)
Studies of discharge patterns and river flows (1990-1991)
Beginning of Interim Operating Criteria (1991)
Grand Canyon Protection Act (1992)
The Grand Canyon Protection Act (Appendix A) was enacted on October 30, 1992. Section
1802 states:
(a) IN GENERAL.−The Secretary shall operate Glen Canyon Dam in accordance with the additional criteria and operating plans specified in Section 1804 and exercise other authorities under existing law 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.
(b) COMPLIANCE WITH EXISTING LAW.−The Secretary shall implement this section in a manner fully consistent with and subject to the Colorado River Compact, the Upper Colorado River Basin Compact, the Water Treaty of 1944 with Mexico, the decree of the Supreme Court in Arizona vs. California, and the provisions of the Colorado River Storage Project Act of 1956 and the Colorado River Basin Project Act of 1968 that govern allocation, appropriation, development, and exportation of the waters of the Colorado River Basin.
(c) RULE OF CONSTRUCTION.−Nothing in this title alters the purposes for which the Grand Canyon National Park or the Glen Canyon National Recreation Area were established or affects the authority and responsibility of the Secretary with respect to the management and administration of the Grand Canyon National Park and Glen Canyon National Recreation Area, including natural and cultural resources and visitor use, under laws applicable to those areas, including, but not limited to, the Act of August 25, 1916 (39 Stat. 535) as amended and supplemented.
The Secretary of the Interior was also directed to establish and implement long-term monitoring programs and activities to ensure that Glen Canyon Dam is operated in a manner consistent with the Grand Canyon Protection Act. These programs include necessary research and studies to determine the effect of management of the dam on the natural, recreational, and cultural downstream resources. These actions will also be undertaken in consultation with other federal agencies, the Governors of the Basin States, Indian Tribes, and the general public, including representatives of academic and scientific communities, environmental organizations, the recreation industry, and contractors for the purchase of federal power produced at Glen Canyon Dam. To accomplish these requirements, the Glen Canyon Dam Adaptive Management Program was established. [2]
Glen Canyon Dam Environmental Impact Statement (1995)
The Glen Canyon Dam Environmental Impact Statement (Reclamation 1995) was completed in
March 1995. Its purpose was to “determine specific options that could be implemented to
minimize—consistent with law—adverse impacts on the downstream environmental and cultural
resources and Native American interests in Glen and Grand Canyons.” The Glen Canyon Dam
Environmental Impact Statement analyzed nine alternatives to allow the Secretary of the Interior
to balance competing interests and to meet statutory responsibilities for protecting downstream
resources and producing hydropower, and to protect affected Native American interests. The
preferred alternative was the Modified Low Fluctuating Flow Alternative.
Establishment of the Grand Canyon Monitoring and Research Center (1995)
Transition Work Group (1995-1996)
The informal group was assembled to act as a bridge between GCES and GCDAMP personnel and methods. It was comprised mostly of soon-to-be GCDAMP stakeholders.
Record of Decision on the Operation of Glen Canyon Dam (1996)
On October 9, 1996, the Secretary of the Interior signed the Record of Decision that presented
the rationale for choosing the Modified Low Fluctuating Flow Alternative. As noted in the Record of Decision:
The goal of selecting a preferred alternative was not to maximize benefits for the most
resources, but rather to find an alternative dam operating plan that would permit recovery
and long-term sustainability of downstream resources while limiting hydropower
capability and flexibility only to the extent necessary to achieve recovery and long-term
sustainability. [Reclamation 1996:10]
The Record of Decision (Appendix G) included seven environmental and monitoring
commitments:
- Adaptive Management
- Monitoring and Protection of Cultural Resources
- Flood Frequency Reduction Measures
- Beach/Habitat-Building Flows
- New Population of Humpback Chub
- Further Study of Selective Withdrawal
- Emergency Exception Criteria
The commitments are explained in detail in the Record of Decision (Reclamation 1996;
Appendix G) and in the Glen Canyon Dam Environmental Impact Statement (Reclamation
1995:33-34); however, it should be noted that subsequent work of the Technical Work Group
and Adaptive Management Work Group have altered some commitments (Technical Work
Group 1998) with Endangered Species Act and National Environmental Policy Act compliance.
Strategic Planning Subcommittee (1997-2000)
Formed at the behest of SOI Bruce Babbitt for the transition from GCES to GCDAMP/AMWG. There were seven members, representing recreation, environmental, tribal, hydropower and Department of the Interior interests. According to Andre Potochnik, it was this group that took the Colorado River trip described in detail by Mary Orton (see 1999, below).
AMWG and TWG fully established (1997)
In 1997 Secretary of Interior Bruce Babbitt established the Glen Canyon Dam Adaptive Management Work Group (AMWG) as a formal Federal Advisory Committee, under the authority and guidelines of the Federal Advisory Committee Act of 1972. The purpose of AMWG was to monitor implementation of the ROD, provide recommendations to the Secretary regarding its effectiveness, and recommend science-based adjustments to the operation of Glen Canyon Dam to better achieve restoration and maintenance of downstream resources. AMWG held its first meeting on September 10-11, 1997, and officially formed the Glen Canyon Technical Work Group (TWG) as a subgroup to work on tasks charged to them by the AMWG.
AMWG Colorado River trip (1999)
As described in Mary Orton’s oral history interview, this trip through Grand Canyon helped soothe contention among AMWG stakeholders, who had not been working together for very long, and resulted in a Vision Statement for the group. Most oral history interviewees involved in GCDAMP at the time have shared a recollection of the trip or its impact on the program.
Publication of first GCDAMP Strategic Plan (2001)
“This strategic plan is a guidance document for the Glen Canyon Dam Adaptive Management Program and was developed by program members. Elements of this plan include the Glen Canyon Dam Adaptive Management Work Group’s vision and mission statements, as well as principles, goals, and management objectives.” (From the Foreword to the Stategic Plan)
Experimental design initiated (2002)
Adaptive Management Work Group recommends implementation of the first 2 years of an experimental design proposed by the GCMRC.
Experimental fish programs launched (2003)
Experiment begun to remove nonnative fish from the Colorado River in Grand Canyon. Fluctuating nonnative fish suppression releases from January through March implemented and continued through 2005.
First High Flow Experiment under a new HFE Protocol (2012)
“Secretary of the Interior Ken Salazar triggered the first release under the experimental long-term protocol in November 2012. The protocol calls for conducting more frequent high-flow experimental releases and timing them to occur following sediment inputs to the Colorado River downstream from Glen Canyon Dam.”
LTEMP EIS (2016)
LTEMP “provides the basis for decisions that identify management actions and experimental options that will provide a framework for adaptively managing Glen Canyon Dam operations over the next 20 years.”
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