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.
- 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.
- 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)
High Flow Experimental Releases (HFEs) refer to controlled, high-volume water releases from dams designed to mimic natural floods and rebuild ecological habitats.
The Concept: Between 1990 and 1995, scientists associated with pioneering ecologist Duncan Patten engaged in highly controversial "formative discussions" about the concept of controlled flooding.
The Debate: At the time, major federal water agencies and traditional engineers were deeply wary of intentionally flooding river systems. These early 1990s discussions served to lay the scientific groundwork for changing dam discharge patterns.
The Result: This period directly led to the implementation of interim operating criteria at major sites like the Glen Canyon Dam, culminating in the first historic, massive test of an environmental HFE in the Grand Canyon in 1996.
Beginning of Interim Operating Criteria (1991)
The interim operating criteria for Glen Canyon Dam officially began implementation in August 1991, following an initial testing period and a formal Interagency Agreement.
- Testing Phase: Tested by the Bureau of Reclamation between August 1 and October 31, 1991, to evaluate research flows and downstream ecological data.
- Interagency Agreement: Formalized via an agreement executed between the Bureau of Reclamation and the Western Area Power Administration (WAPA) on October 2, 1991 (with exception criteria detailed further on October 21, 1991).
- Operational Flexibility: Allowed WAPA a 10% fluctuation buffer around operational constraints to manage electrical control areas while accommodating downramp limits.
- Environmental Context: Preceded the landmark Grand Canyon Protection Act of 1992, which legally mandated protecting downstream resources in Grand Canyon National Park and Glen Canyon National Recreation Area.
The Grand Canyon Protection Act of 1992 directed the Secretary of the Interior to manage the Glen Canyon Dam to protect downstream environmental, cultural, and recreational resources in the Grand Canyon.
Key Provisions
- Dam Operations: Required the Bureau of Reclamation to operate Glen Canyon Dam in a way that mitigates adverse impacts on natural and cultural resources and visitor use in a manner fully consistent with and subject to the Law of the River.
- Water Priority: Made environmental protection subordinate to the primary water storage and delivery functions of the Colorado River Compact.
- Environmental Impact Statement (EIS): Mandated a comprehensive EIS on dam operations, leading to a 1996 Record of Decision.
- Long-Term Monitoring: Ordered the establishment of long-term monitoring programs and adaptive management to continually evaluate downstream ecosystem health.
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)
The Grand Canyon Monitoring and Research Center (GCMRC) was officially established in November 1995 to measure how Glen Canyon Dam operations affect natural, physical, biological, and cultural resources along the Colorado River.
Legislative Mandate: Created to fulfill the long-term monitoring and research requirements of the Grand Canyon Protection Act of 1992.
Core Mission: Ensure that Glen Canyon Dam operates in a way that protects and improves the values of Grand Canyon National Park and Glen Canyon National Recreation Area.
Program Integration: Absorbed the earlier Glen Canyon Environmental Studies program and became the main science provider for the Glen Canyon Dam Adaptive Management Program (GCDAMP).
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.
The Long-Term Experimental Plan Environmental Impact Statement (LTEP
EIS) was begun in late 2006 to address flow and non-flow actions in the
Colorado River below Glen Canyon Dam. The Bureau of Reclamation
completed public scoping for the proposed action in January 2007 and
issued a scoping report in March 2007. Multiple factors, including
extraordinarily large sediment inputs from tributaries, new information on
the endangered humpback chub population, and litigation, have led to a
temporary suspension of work on the LTEP EIS, and instead a primary
focus on Endangered Species Act and National Environmental Policy Act
compliance on a five-year plan of experimental flows, including a high-flow
test that was completed in early March 2008.
The High Flow Experiment 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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