Difference between revisions of "Glen Canyon Dam Adaptive Management ADMINISTRATIVE HISTORY"

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−
==Glen Canyon Environmental Studies==
+
==Glen Canyon Environmental Studies - Phase I (1982-1988)==
−
While the National Park Service, Native Americans, river runners, and scientists had noticed that some beaches were disappearing and that plant and animal life along the Colorado River were
+
−
changing since Glen Canyon Dam was completed in 1963, the Glen Canyon Environmental Studies program of the Bureau of Reclamation was the first systematic effort to investigate the effects of dam operations on downstream resources. The program began in 1982 and lasted through 1996. The Glen Canyon Environmental Studies did identify a mix of positive and negative consequences of dam operations on the downstream environment. In response to
+
−
substantial public concern over the findings of the Glen Canyon Environmental Studies, in 1989 the Secretary of the Interior announced that an environmental impact statement would be completed to evaluate the operation of Glen Canyon Dam. With this announcement, the Glen Canyon Environmental Studies focused on providing specific data for use in the Glen Canyon Dam Environmental Impact Statement (Reclamation 1995). [http://www.riversimulator.org/Resources/GCDAMP/GCDAMPchronicle/StrategicPlanGCDamp2001.pdf]
+
  
−
==Grand Canyon Protection Act==
+
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.
−
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.
+
*Purpose: Assess the short- and long-term impacts of Glen Canyon Dam operations on downstream resources, including vegetation, wildlife, fisheries, recreation, and sand beaches.
  
−
(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.
+
*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.
  
−
(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.
+
*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.
  
−
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. [http://www.riversimulator.org/Resources/GCDAMP/GCDAMPchronicle/StrategicPlanGCDamp2001.pdf]
+
==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.
 +
 
 +
*Subsequent Publication: The findings and reviews initiated around this period culminated in the landmark NRC report, [https://www.nationalacademies.org/publications/1832 Colorado River Ecology and Dam Management], published in 1990.
 +
 
 +
==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.
 +
 
 +
==[https://gcdamp.com/index.php/Grand_Canyon_Protection_Act Grand Canyon Protection Act (1992)]==
 +
 
 +
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)==
  
−
==Glen Canyon Dam Environmental Impact Statement==
 
 
The Glen Canyon Dam Environmental Impact Statement (Reclamation 1995) was completed in
 
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
 
March 1995. Its purpose was to “determine specific options that could be implemented to
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preferred alternative was the Modified Low Fluctuating Flow Alternative.
 
preferred alternative was the Modified Low Fluctuating Flow Alternative.
  
−
==Record of Decision on the Operation of Glen Canyon Dam==
+
==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
 
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 rationale for choosing the Modified Low Fluctuating Flow Alternative. As noted in the Record of Decision:
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Group 1998) with Endangered Species Act and National Environmental Policy Act compliance.
 
Group 1998) with Endangered Species Act and National Environmental Policy Act compliance.
  
−
==Statutes, Policies, and Resolutions==
+
==Strategic Planning Subcommittee (1997-2000)==
−
The Colorado River is managed and operated under numerous compacts, federal and state laws,
+
 
−
court decisions and decrees (including Native American water claim settlements), contracts,
+
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).
−
treaties, and regulatory guidelines collectively known as the Law of the River. This collection of
+
 
−
documents apportions the water among the seven Basin States and Mexico, and regulates and
+
==AMWG and TWG fully established (1997)==
−
manages the river flows of the Colorado River. Some of the statutes included within the Law of
+
 
−
the River that have a major impact on dam operations are the Colorado River Compact of 1922,
+
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.
−
the Upper Colorado River Basin Compact of 1948, the Colorado River Storage Project Act of
+
 
−
1956, the Colorado River Basin Project Act of 1968, and the Grand Canyon Protection Act of
+
==AMWG Colorado River trip (1999)==
−
1992. In addition to Colorado River specific legislation, the Endangered Species Act of 1973
+
 
−
and court decrees including Arizona v. California affect the extent to which water developments
+
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 and Mission 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.
−
and diversions can be utilized in the Colorado River Basin. The Law of the River and this
+
 
−
additional legislation control and influence the Adaptive Management Program.
+
The combined Vision and Mission statement reads as follows:
 +
*The Grand Canyon is a homeland for some, sacred to many, and a national treasure for all. In honor of past generations, and on behalf of those of the present and future, we envision an ecosystem where the resources and natural processes are in harmony under a stewardship worthy of the Grand Canyon.
 +
*We advise the Secretary of the Interior on how best to protect, mitigate adverse impacts to, and improve the integrity of the Colorado River ecosystem affected by Glen Canyon Dam, including natural biological diversity (emphasizing native biodiversity), traditional cultural properties’ spiritual values, and cultural, physical, and recreational resources through the operation of Glen Canyon Dam and other means.
 +
*We do so in keeping with the federal trust responsibilities to Indian tribes, in compliance with applicable federal, state, and tribal laws, including the water delivery obligations of the Law of the River, and with due consideration to the economic value of power resources.
 +
*This will be accomplished through our long-term partnership utilizing the best available scientific and other information through an adaptive ecosystem management process. [http://www.riversimulator.org/Resources/GCDAMP/GCDAMPchronicle/StrategicPlanGCDamp2001.pdf]
 +
 
 +
==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)
 +
 
 +
==[http://www.riversimulator.org/Resources/Legal/GCD/ReclamationLTEPwebPage.pdf Long-Term Experimental Plan (LTEP) EIS (2006)] ==
 +
 
 +
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.
 +
 
 +
==[https://gcdamp.com/index.php/Portal:Desired_Future_Conditions_-DFCs Desired Future Conditions (2012)]==
 +
 
 +
Desired Future Conditions were developed as statements of qualitative goals and objectives for the AMP,
 +
realistic and achievable through the operation of Glen Canyon Dam and related activities, subject
 +
to the Law of the River and other laws and authorities and consistent with the Grand Canyon
 +
Protection Act.
 +
 
 +
==[https://gcdamp.com/index.php/The_HFE_Page The High Flow Experiment (HFE) Protocol (2012)]==
 +
 
 +
An HFE Protocol was developed in 2012 and describes how these experimental releases are designed to achieve a better understanding of whether, how, and when to incorporate high releases into future dam operations in a manner that maintains or improves beaches, sandbars, and associated habitat. The LTEMP HFE Protocol establishes a decision-making framework consisting of three components: (1) planning and budgeting, (2) modeling, and (3) decision and implementation.
 +
 
 +
Under the 2016 LTEMP, HFE releases are restricted to limited periods of the year when the highest volumes of sediment are most likely available for building sandbars. Sediment-triggered HFEs may be made in spring (March to June) or fall (October to November; Figure 1). Fall extended-duration HFEs range from greater than 96 hr to 250 hr. Spring and fall HFEs that are not extended-duration range from less than 1 hr to 96 hr. Proactive HFEs may be implemented in spring or early summer (April, May or June), and have a duration range up to 24 hr. HFE magnitudes range from 31,500 cubic feet per second (cfs) to 45,000 cfs. The frequency of HFEs is determined by tributary sediment inputs, annual release volumes, resource conditions, and decisions of the Department. Extended-duration fall HFEs are limited to a frequency of 4 times total in the 20-year LTEMP period.
 +
 
 +
==[https://gcdamp.com/index.php/Long-term_Experimental_and_Management_Plan_(LTEMP) The Long-term Experimental and Management Plan (LTEMP) EIS (2016)]==
  
−
Additional laws, Acts of Congress, executive orders, policies, tribal resolutions, etc., that control
+
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.”
−
or influence the Adaptive Management Program include the National Park Service Organic Act,
+
−
enabling legislation for Grand Canyon National Park and Glen Canyon National Recreation
+
−
Area, and Executive Orders that established reservation boundaries for the Navajo Nation and
+
−
the Hualapai Tribe. In addition, Section 204 of Title II of Public Law 106-377 controls the level
+
−
of funding of Adaptive Management Program activities from Colorado River Storage Project
+
−
power revenues. The Federal Advisory Committee Act controls operation of the Adaptive
+
−
Management Work Group and the Technical Work Group.
+
  
−
Environmental laws and regulations are important to the Adaptive Management Program. These
+
The purpose of the proposed action is to provide a comprehensive framework for adaptively managing Glen Canyon Dam over the next 20 years consistent with the GCPA and other provisions of applicable Federal law. The proposed action will help determine specific dam operations and actions that could be implemented to improve conditions and continue to meet the GCPA's requirements and to minimize, consistent with law-adverse impacts on the downstream natural, recreational, and cultural resources in the two park units, including resources of importance to American Indian Tribes.
−
include, but are not limited to, the Endangered Species Act, National Historic Preservation Act
+
−
of 1966, and National Environmental Policy Act of 1969. Adaptive Management Program
+
−
compliance with these statutes, regulations, policies, directives, etc., is described in a later
+
−
section.
+
  
−
==Guidance Document for the Adaptive Management Program==
+
The need for the proposed action stems from the need to use scientific information developed since the 1996 ROD to better inform DOI decisions on dam operations and other management and experimental actions so that the Secretary of the Interior may continue to meet statutory responsibilities for protecting downstream resources for future generations, conserving species listed under the Endangered Species Act (ESA), avoiding or mitigating impacts on National Register of Historic Places (NRHP)-eligible properties, and protecting the interests of American Indian Tribes, while meeting obligations for water delivery and the generation of hydroelectric power.
−
Since the Adaptive Management Program became fully operational in 1997, questions and
+
−
uncertainties have arisen over the relationships of program elements, compliance priorities, and
+
−
other legal matters. Answers were sought from a Department of the Interior Solicitor. The
+
−
questions posed and answers received from the Department of the Interior’s Solicitor (Loveless
+
−
2000) are called the “Guidance Document for the Adaptive Management Program.” This
+
−
document is provided as [http://www.riversimulator.org/Resources/GCDAMP/GCDAMPchronicle/StrategicPlanGCDamp2001.pdf| '''Appendix B'''] in the '''[[GCDAMP Strategic Plan]]'''.  
+
  
 
|}
 
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*[https://gcdamphistory.org/history/historical-timeline/ Historical Timeline]
 
*[https://gcdamphistory.org/history/historical-timeline/ Historical Timeline]
 
*[[GCDAMP AHAHG Page| Administrative History Ad-Hoc Group (AHAHG) page]]
 
*[[GCDAMP AHAHG Page| Administrative History Ad-Hoc Group (AHAHG) page]]
 +
*[[GCES Documents| GCES Documents]]
  
 
|-
 
|-
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−
*[[GCDAMP History Time-Line -Years]]
 
  
 
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Latest revision as of 15:00, 29 September 2026


2013-01 TWG Pics.jpg

History of the Glen Canyon Dam Adaptive Management Program

The Secretary of the Interior Bruce Babbitt, created the Glen Canyon Dam Adaptive Management Program (GCDAMP) in response to the 1995 Environmental Impact Statement on the Operations of Glen Canyon Dam. The GCDAMP is responsible for implementation of the Grand Canyon Protection Act of 1992, to monitor the operation of Glen Canyon Dam, to ensure the dam is operated in compliance with a range of laws and regulations and mitigate any significant environmental impacts. [1]

--
Click here to see the Expanded GCDAMP History Timeline
--

History of the Glen Canyon Dam Adaptive Management Program

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.

Grand Canyon Protection Act (1992)

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 and Mission 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.

The combined Vision and Mission statement reads as follows:

  • The Grand Canyon is a homeland for some, sacred to many, and a national treasure for all. In honor of past generations, and on behalf of those of the present and future, we envision an ecosystem where the resources and natural processes are in harmony under a stewardship worthy of the Grand Canyon.
  • We advise the Secretary of the Interior on how best to protect, mitigate adverse impacts to, and improve the integrity of the Colorado River ecosystem affected by Glen Canyon Dam, including natural biological diversity (emphasizing native biodiversity), traditional cultural properties’ spiritual values, and cultural, physical, and recreational resources through the operation of Glen Canyon Dam and other means.
  • We do so in keeping with the federal trust responsibilities to Indian tribes, in compliance with applicable federal, state, and tribal laws, including the water delivery obligations of the Law of the River, and with due consideration to the economic value of power resources.
  • This will be accomplished through our long-term partnership utilizing the best available scientific and other information through an adaptive ecosystem management process. [2]

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)

Long-Term Experimental Plan (LTEP) EIS (2006)

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.

Desired Future Conditions (2012)

Desired Future Conditions were developed as statements of qualitative goals and objectives for the AMP, realistic and achievable through the operation of Glen Canyon Dam and related activities, subject to the Law of the River and other laws and authorities and consistent with the Grand Canyon Protection Act.

The High Flow Experiment (HFE) Protocol (2012)

An HFE Protocol was developed in 2012 and describes how these experimental releases are designed to achieve a better understanding of whether, how, and when to incorporate high releases into future dam operations in a manner that maintains or improves beaches, sandbars, and associated habitat. The LTEMP HFE Protocol establishes a decision-making framework consisting of three components: (1) planning and budgeting, (2) modeling, and (3) decision and implementation.

Under the 2016 LTEMP, HFE releases are restricted to limited periods of the year when the highest volumes of sediment are most likely available for building sandbars. Sediment-triggered HFEs may be made in spring (March to June) or fall (October to November; Figure 1). Fall extended-duration HFEs range from greater than 96 hr to 250 hr. Spring and fall HFEs that are not extended-duration range from less than 1 hr to 96 hr. Proactive HFEs may be implemented in spring or early summer (April, May or June), and have a duration range up to 24 hr. HFE magnitudes range from 31,500 cubic feet per second (cfs) to 45,000 cfs. The frequency of HFEs is determined by tributary sediment inputs, annual release volumes, resource conditions, and decisions of the Department. Extended-duration fall HFEs are limited to a frequency of 4 times total in the 20-year LTEMP period.

The Long-term Experimental and Management Plan (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.”

The purpose of the proposed action is to provide a comprehensive framework for adaptively managing Glen Canyon Dam over the next 20 years consistent with the GCPA and other provisions of applicable Federal law. The proposed action will help determine specific dam operations and actions that could be implemented to improve conditions and continue to meet the GCPA's requirements and to minimize, consistent with law-adverse impacts on the downstream natural, recreational, and cultural resources in the two park units, including resources of importance to American Indian Tribes.

The need for the proposed action stems from the need to use scientific information developed since the 1996 ROD to better inform DOI decisions on dam operations and other management and experimental actions so that the Secretary of the Interior may continue to meet statutory responsibilities for protecting downstream resources for future generations, conserving species listed under the Endangered Species Act (ESA), avoiding or mitigating impacts on National Register of Historic Places (NRHP)-eligible properties, and protecting the interests of American Indian Tribes, while meeting obligations for water delivery and the generation of hydroelectric power.


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