Chapter
Twenty-One
Environmental
History
of the Colorado River:
The Changing Focus of Science
B Y E M M A P. B E N E N AT I

AND

J O S E P H P. S H A N N O N

To quote the authors, the “Colorado River has a plethora of national and local agencies and organizations firmly shackled to it
for reasons ranging from preservation to profits.” Rather than propose specific actions to protect the river’s biological integrity,
a task far too complex for a single presentation, Emma Benenati and Joseph Shannon help unravel the issues by outlining
the history and changing focus of scientific investigations of the pre-dam (before 1964) and post-dam era in relation to the
evolution of human values and our views of the natural world. Along the way, they identify some of the problems of modern river management by stakeholders with conflicting agendas.
Although long appreciated for phenomenal beauty and natural attributes, in recent decades the Grand Canyon and
the Colorado River flowing within have become the center
of political, economic, and environmental controversy. The
heart of this controversy stems from differing views on the
best use, or nonuse, of the resource. Factors contributing to
controversy include:
•
•
•

•

Grand Canyon National Park (GCNP) visitation now
approaches five million people annually.
The number of Colorado River rafters below Lake Powell
and in the Grand Canyon exceeds 50,000 annually.
The river corridor is critical habitat for endangered
species, including the humpback chub, razorback sucker,
Kanab ambersnail, and southwestern willow flycatcher
(Schmidt et al. 1998).
Rainbow and brown trout, introduced fish that thrive in
the cold waters below Glen Canyon Dam, provide a
sport-fishing industry for nearby communities, yet are
responsible for the decline of native fish through predation and competition for food and habitat.

•

The river lies between two of the largest dams and
reservoirs in the United States and is part of a regulated
system that exports more water out of its basin than any
other river basin on earth (Hirsch et al. 1990).

Because of conflicting interests and uses, the Colorado
River has a plethora of national and local agencies and
organizations firmly shackled to it for reasons ranging from
preservation to profits. Examples of the wide range of
Grand Canyon “stakeholder” groups include the Bureau of
Reclamation (BOR), Western Area Power Administration,
Colorado River Energy Distributor Association, Arizona
Game and Fish, Grand Canyon Trust, Bureau of Indian
Affairs, commercial fishing and rafting companies, boaters’
and river runners’ organizations, states, and several American Indian tribes.
The nature of scientific investigations on the Colorado
River has evolved over time, reflecting prevailing human
values in much the same way as changes in management
policies and laws. Relationships and influence among scientists, managers, legislators, and the public are convoluted

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and dynamic, and as population and resource demands
have exploded, “final authority” has fluctuated between
these sectors. This is primarily because managing agencies
are confused about their mission or have not been allowed
to follow it. Years of vague and conflicting legislation combined with political influence within and outside management agencies have made it dangerous to voice an opinion,
much less make decisions that benefit the resource.
For example, during the Bridge Canyon Dam controversy in the early 1950s, all Grand Canyon National Park
personnel were prohibited from voicing personal opinions
after Acting Superintendent Lemuel Garrison expressed
anti-dam sentiments in written correspondence. National
Park Service (NPS) Region Three Director M. R. Tillotson
immediately ordered park personnel to limit comments to
“factual data and known Service policies or decisions.” A
decade later, during hearings on Marble Canyon Dam,
NPS Director Conrad Wirth spoke against reclamation
projects that involved park lands after having been warned
by Secretary of the Interior Stewart Udall not to express
his personal opinions (Pearson 1992). Within a year Udall
removed Wirth as NPS director.
All too often, responsible government agencies rely on
the most powerful voice of the time, a dubious way to
manage natural resources. In this paper we will describe the
changing focus of scientific investigations of the Colorado
River over the past four centuries since Europeans realized
its existence. This change in focus is presented in relation
to the evolution of human values and our view of the natural world relative to ourselves.

PRE-DAM INVESTIGATIONS
The Grand Canyon and the Colorado River have a long
history of human investigations. Recorded history over the
past few hundred years shows the slow progression of
investigative themes shifting from exploration to exploitation to restoration. Science has been a part of all these
themes and has grown in importance, especially in the last
few decades. Biological investigations on the river had a
rather slow start, largely because the objectives and priorities of early researchers were more physical-based. The
most striking features of the Colorado River and the
Grand Canyon to most observers are their physical components: rocks, colors, depth, danger, rapids, etc. Moreover,
surface appearances did not reveal much “biology” in predam days, with the river corridor generally appearing as a
scoured, muddy waterway with little riparian vegetation.
Biological features were subtle and required time to be
noticed and understood, which is still the case, even after

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post-dam increases in ecological systems. Today, however,
due to the effects of Glen Canyon Dam, the corridor
appears to be a biological wonderland with both positive
and negative aspects.
One element that has not changed is that the Grand
Canyon is both a spectacular and challenging place to conduct scientific investigations. The challenge of travel on the
Colorado River often impedes science, and it can be a
struggle to keep the research in perspective. Scientists have
always had to deal with conditions that confront expeditions in remote settings, such as a lack of outside assistance
in the event of illness or equipment loss. Other common
problems include collecting data in or beside the river
regardless of season or weather conditions. Living in
cramped or awkward conditions tests a person’s resolve, as
does constant packing and unpacking of gear. One hundred
and fifty rapids must be negotiated while preventing loss or
damage to equipment and workers. Despite these challenges, however, most of us gladly accept the inconveniences
and danger just to work in the Grand Canyon.
Explorations in the canyon region from the 1500s
through the early 1800s were primarily land based and not
“scientific” as we define the term today. During these years,
Spaniards dominated the investigative landscape, searching
for gold, silver, and other immediate economic opportunities (Spicer 1962). Science became a part of exploration in
the mid-1800s, when a series of government surveys
scoured the Colorado Plateau; at that time, scientific objectives changed to more in-depth examination of land
resources, mapping, and wagon-road and railroad surveys.
Natural-history observations of plants and animals were
also documented, usually by physicians who served as the
collectors and naturalists in addition to their medical
duties. Professional geologists such as John Newberry and
Grove Karl Gilbert were often employed to study rock
strata and construct geologic cross sections of explored areas.
These expeditions were led by military officers, including
John C. Frémont, Lorenzo Sitgreaves, John Gunnison, and
Amiel Whipple, and usually assisted by civilian specialists
such as the trapper-guide Antoine Leroux and artistcartographer Richard Kern (Wallace and Lubick 1991). Two
of the first Colorado River surveys were accomplished by
Lieutenant Joseph Ives in 1857–58, and by Lieutenant
George Wheeler in 1871–72, both of whom concentrated on
the lower river. Ives determined the lower river’s navigability
by steaming upstream from the Gulf of California as far as
Black Canyon, the present site of Hoover Dam. Wheeler
undertook the more difficult task of exploring the river
within the Grand Canyon itself, rowing, towing, and portaging rowboats upriver from Camp Mohave near today’s
Needles, California, to Diamond Creek.

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The earliest systematic research was a geographical and
geological survey conducted by John Wesley Powell during
two river trips in 1869 and 1871–72 (Powell 1895).
Although Powell’s research comprised a predominantly
physical examination of the largely unknown river drainage,
he also documented some plant species. He later proved
instrumental in ushering in the age of reclamation, a
decade before the 1902 Reclamation Act. As head of the
U.S. Geological Survey in 1889, entrusted with management of the new Irrigation Survey project, Powell directed
numerous survey trips on western rivers to map potential
dam sites (Aton 1988). Based on his research, Powell
developed a democratic and science-based reclamation plan
for the West that logically organized water districts based
on watershed boundaries and available water. His plan
explicitly excluded government interference, and instead
proposed that the support, labor, and control of western
water development remain with local cooperative associations after initial government surveys for dam sites. His
ideas were never implemented, however, due to opposition
by members of Congress who stood to gain personally
through governmental development of western water
(Worster 1994). Powell appreciated the beauty of the rivers
and canyons, as his romantic descriptions attest; however,
he supported the control and damming of western waters,
in particular, large rivers such as the Colorado and Rio
Grande (Aton 1988). One can only speculate what his
opinion would be of monopolistic policies practiced by
today’s BOR and Western Area Power Administration.
Coincident with Powell’s years of governmental service,
a national environmental movement began to flourish.
The 1890 census revealed an end to the American “frontier,” and concerns regarding land use continued to grow
in two directions. One view held that there was an
increasing and justified need for use of land and resources
for national progress and growth. The opposite view held
that land and natural-resource consumption was occurring
too quickly and carelessly, requiring immediate conservation. While Americans struggled with these ideas from
the middle 1800s to the early 1900s (Merchant 1993), a
national conservation movement began, a movement split
between those who would preserve the land and those
who would conserve it. Preservationists, ideologically
associated with Henry David Thoreau and John Muir,
believed that the best in life could be found in nature and
that land development did not necessarily lead to
progress. Conservationists, led by Theodore Roosevelt,
defined their policy as the “use of natural resources for the
greatest good of the greatest number for the longest
time.” Many citizens were caught between these opposing
ideologies, wanting to preserve the qualities of wilderness

yet desiring the advantages and conveniences afforded by
development of wild lands. While preservationists were
often viewed as radicals and romantics, conservationists
considered their position to be based in science.
The roots of conflict between the use and preservation
of the Colorado River date to the early-twentieth-century
conservation movement and its scientific base. More than
two decades of controversy preceded the passage of legislation creating Grand Canyon National Park in 1919; unfortunately, thanks to Arizona Senator Carl Hayden, the same
law allowed for reclamation projects within park boundaries. When questioned on his position, Hayden responded
that reservoirs for water storage and irrigation would be
built only when “consistent with the primary purposes of
the park” (Pearson 1992). Since the primary purpose of
national parks, to paraphrase the National Park Service
Organic Act of 1916, is to conserve the scenery, the natural
and historic objects, and the wildlife therein, and to provide
for the enjoyment of the same in such manner and by such
means as will leave them unimpaired for the enjoyment of
future generations, it is clear that human-induced additions
or “impairment” of the Grand Canyon and its wildlife are
inconsistent with the “primary purposes of the park.” The
problem that scientists as well as managers, politicians, and
environmentalists grapple with today, however, is that
although nearly two thousand miles of the river and its
tributaries are legally protected as national parklands or are
designated critical habitat, water has become the lifeblood
of the Southwest (Carothers and Brown 1991).
Theodore Roosevelt illustrated early on the conflict and
political contradiction between conservation and preservation. In 1903 he spoke at the canyon’s South Rim and
asked its residents and, by implication, the nation, “to keep
this great wonder of nature as it is now . . . Leave it as it is.
You cannot improve on it” (quoted in Hughes 1978). Five
years later, in his White House speech formally inaugurating the conservation movement, Roosevelt proclaimed the
virtue of using our national resources in such a manner not
only as to leave them undiminished, but to “actually be
improved by wise use.” He added that “men can improve
on nature by compelling the resources to renew and even
reconstruct themselves to serve increasingly beneficial
uses—while the living waters can be so controlled as to
multiply their benefits” (Merchant 1993). He must have
forgotten his visit to the Grand Canyon.
Back on the Colorado River, the general theme of
investigation changed from exploratory-based expeditions
to exploitation using the physical sciences but still very little biology. In 1889–90, Frank Brown, president of the
Denver, Colorado Cañon, and Pacific Railroad Company,
and his engineer Robert Brewster Stanton surveyed the

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river through the Grand Canyon for a water-level railway
that would run from Grand Junction, Colorado, to San
Diego, California (Smith and Crampton 1987). The expedition incidentally gathered information on plant life. In
August 1923 Claude Birdseye led a U.S. Geological Survey
trip that produced a topographical map of the canyon bottom and, more importantly, twenty-one potential dam sites
within the Grand Canyon. They called this survey the
“conquest of the Colorado,” an excellent reflection of the
sentiment of contemporary citizens and government.
By the 1930s biological research was on the rise.
Between 1933 and 1938 a series of trips sponsored by the
Museum of Northern Arizona floated the San Juan and
Colorado rivers as far as Lees Ferry. Although archaeology
was their main purpose, researchers also pursued biological
studies of mammals, birds, reptiles, insects, and plants. In
1938 Norm Nevills guided the first biological research trip
through the canyon. Professor Elzada Clover and her graduate student, Lois Jotter, of the University of Michigan—
the first women to float all the way through the Grand
Canyon—studied botany on this trip. Nevills himself used
the publicity to launch a commercial river-running business. Angus Woodbury of the University of Utah conducted
biological studies on the river in the late 1950s (Woodbury
1959), although he worked above the later site of Glen
Canyon Dam.
Despite the rise in scientific interest, very little information was obtained on the Colorado River prior to the
completion of Glen Canyon Dam in 1963. Immediately
thereafter, the physical and biological condition of the river
corridor began to change dramatically (Carothers and
Brown 1991; Webb et al. 1999). It took years for managers
to realize the dam’s effects. Some were immediate and
obvious, but many developed over time and are still developing today. Although the river and corridor appears to be
“improved” to many people, with its clear water, lucrative
trout fishery, abundance of riparian life, and absence of
scouring floods, a tremendous part of the natural ecosystem
has been lost.
Research conducted since the gates of Glen Canyon
Dam closed has revealed that the ecosystem today is completely altered above and below the dam (Stanford and
Ward 1986; Blinn and Cole 1991). One of the changes is
river water temperature, which remains in a narrow range
between forty-six and fifty degrees Fahrenheit. Therefore,
the macroinvertebrate community is dominated by alien
cold-adapted species that also have a narrow range of temperature tolerance (Oberlin et al. 1999; Blinn and Cole
1991). The dam as barrier has reduced the former carbon
source of “externally produced” upland woody vegetation
that used to wash in and serve as the base of the food web

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(Haden et al. 1999, 2003). The loss of sediment, at least 80
percent less today, results in greater water clarity and
exposed cobble substrate on the river bottom, which allows
sunlight to penetrate the water column and promotes photosynthesis and growth of aquatic plants such as algae and
macrophytes that now serve as an “internally produced”
base of the food web (Blinn et al. 1998; Benenati et al.
2000). Finally, due to the lack of seasonal floods, discharge
has changed to a narrow range of flows on an annual basis;
however, due to the production of hydropower, there is now
a daily tide that influences physical and biological aspects
of the river channel (Benenati et al. 1998).

POST-DAM INVESTIGATIONS
The 1970s ushered in an era of long-term research on the
Colorado River. The 1960s wave of national environmental
awareness gained momentum due to proposed dams within
the Grand Canyon. Congress passed environmental legislation, such as the Endangered Species Act in 1973 and the
National Environmental Policy Act in 1969, which mandated improved management of national resources
(Carothers and Brown 1991). Science commissions under
the Department of the Interior called for the NPS to manage in accordance with the original intent of the NPS
Organic Act of 1916 and to use scientific research as a
basis for NPS policies (National Research Council 1992).
Meanwhile, greater numbers of people were rafting
through the Grand Canyon, both creating and publicizing
problems on the river. Campsites were trashed, vegetation
was trampled, and human feces and toilet paper permeated
beaches. As many as 5,000 unregulated potty dumps
occurred every season along the corridor; favorite beaches
could receive more than 150 potty dumps per year (Phillips
and Lynch 1977). Waterfalls, side canyons, and other scenic spots were polluted with urine, feces, and garbage.
These problems of overuse prompted the Colorado River
Research Program in the early 1970s, combining the efforts
of Grand Canyon National Park, the BOR, and the
Museum of Northern Arizona (Grand Canyon National
Park 1979). The Colorado River Research Program was
“reactive science” that addressed well-established recreational use problems from the previous decade. Participants
studied conditions and assisted in the development of the
1979 Colorado River Management Plan to mitigate recreational impacts, but little thought was given to the effects
of dam operations. Implementation of the river plan did
result in better camping and cooking procedures and
portable toilets, however, and studies did include the effects
of feral burros and how to remove them, as well as the issue

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of motor use. Research in the later 1970s also produced a
flora and fauna survey, documentation on native and nonnative fishes, and some attention to the effects of dam
operations on riverine resources.
A research program known as the Glen Canyon
Environmental Studies (GCES) followed the Colorado
River Research Program from 1982 through 1996. GCES
was envisioned as a multiagency, multibureau effort to
study the dam’s effects on downstream aquatic and terrestrial resources. The scope was wider than previous projects
of the 1970s, although still something less than a total
ecosystem approach due to program restrictions and lack of
direction from responsible agencies; the underlying
assumption of some scientists outside the GCES was that
no useful information would be obtained (Wegner 1991).
Initially, the main areas of study included sediment, biology,
and recreation, with additional studies in river temperature
modification and hydrology. The BOR established this
program in response to public pressure regarding concerns
for the overall effects of Glen Canyon Dam on the river.
Listing of the humpback chub as an endangered species in
1978 and concern for other native species served as catalysts. Two primary triggers for the GCES were concerns
regarding the “peaking power program,” which resulted in
large, erratic fluctuations in daily water discharge (for the
purpose of instantaneous electricity production and revenues), and the BOR’s proposed “uprate and rewind project” on dam generators to increase hydropower production.
Although resigned to an environmental study mandated
by the National Environmental Policy Act, the BOR wanted
to avoid an Environmental Impact Statement (EIS) that
would have entailed a full-scope examination of dam operations (National Research Council 1996). The Department
of the Interior decided that the bureau would instead proceed with an Environmental Assessment, a scaled down
version of an EIS requiring no new data collection, and at
the same time proceed with the generator upgrade. The
GCES, originally envisioned to be a two-year project, was
intended to provide data that would support the BOR’s
decision not to conduct an EIS (National Research Council
1996). This was essentially the root of most problems that
would plague research for years. Because GCES was created
and funded by the BOR essentially to minimize environmental compliance and support their water-development
mission, the program and program manager would remain
subject to BOR control and authority for the duration of
the program.
Aside from limited direction, the GCES research scope
was constrained both geographically and conceptually.
Studies were initially limited to only the Glen Canyon
reach of the Colorado River, hence the name, Glen Canyon

Environmental Studies. Any analysis that might result in
reduced hydropower revenues was prohibited, as were
investigations of cultural and aesthetic values, referred to as
“non-use values,” a term still used today. The BOR also
limited research to agency scientists, precluding more
objective academic and outside scientists. Even before these
constraints became known, BOR administrators had been
criticized for conflict of interest because of their close association with the Western Area Power Administration,
which marketed power, and because both agencies provided
the funds and management of the research program and
both stood to benefit from the status quo of dam operations (National Research Council 1996).
In 1986, to maintain credibility for conducting its own
environmental studies, the BOR asked the National
Research Council to review the science of the GCES. The
National Research Council reviewers, who are outside professionals and scientists charged with ensuring quality and
objectivity in federal research, addressed many of the problems hampering the research program. Research scope and
scientific expertise were expanded, economic (power) and
cultural aspects were added, and an ecosystem emphasis
was incorporated into the program. By 1989, GCES had
gathered considerable evidence of the dam’s negative environmental impacts that enabled Secretary of the Interior
Manuel Lujan to order an EIS to be completed by 1994.
Under the direction of program manager Dave Wegner,
the GCES project became the database for analysis of
potential management alternatives for the EIS process
(Wegner 1991).
Although conflicts with the BOR continued through
the GCES years, the program contributed significant environmental knowledge regarding the Colorado’s ecosystem
and management specifically as well as large regulated
rivers in general. The EIS supplied a wide range of dam
management options to Secretary of the Interior Bruce
Babbitt’s Record of Decision announced in 1996. The secretary’s decision authorized a “Modified Low Fluctuating
Flow Alternative” that would somewhat reduce the daily
change in discharge volume and ramping rates (speed of
increasing or decreasing water discharge). In addition,
GCES devised a long-term research and monitoring plan
to be implemented following the EIS called the Glen
Canyon Dam Adaptive Management Program (GCDAMP). Another benefit of the GCES program was an
informed and involved general public, and the growth of
numerous environmental watchdog organizations.
In 1997 GCES was reorganized into the Grand
Canyon Monitoring and Research Center (GCMRC)
under the GCD-AMP. The GCMRC’s purpose is to coordinate scientific studies suggested by designated work

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groups of the AMP that address requirements of the
Grand Canyon Protection Act of 1992. The purpose of the
GCD-AMP is to use data from ongoing, long-term monitoring and experiments as a basis for change or “adaptation”
in management policy in order to better manage the
ecosystem and ensure compliance with the Grand Canyon
Protection Act (National Research Council 1999). In the
AMP hierarchy, GCMRC is on the bottom tier along with
a technical advising work group (TWG) and an independent review panel. These three groups report to the second
tier, the Adaptive Management Work Group (AMWG),
which has the authority to vote for or against science studies
and experiments as well as recommend implementation of
certain operational policies to the secretary of the interior’s
designee. The secretary’s designee sits on the third tier, and
after receiving the recommendations of the AMWG,
reports them to the secretary for a decision.
The science advisory groups TWG and AMWG are
composed of representatives of “stakeholders” who have an
interest related to the Grand Canyon or the Colorado
River. Stakeholders include the BOR, Western Area Power
Association, Colorado River Energy Distributor
Association, each of the seven basin states that receive
water or electricity benefits of the Colorado River, commercial recreation groups, Arizona Game and Fish, U.S.
Fish and Wildlife Service, Grand Canyon National Park,
seven southwestern American Indian tribes, and two environmental organizations: Grand Canyon Trust and
Southwest Rivers. The large number of stakeholders with
their own interests and infrequent meetings often result in
stalemates and a lack of measurable progress for months or
years at a time; such delays benefit the agendas of water
and power interests.
The organizational structure of the GCD-AMP
appears well-planned, but a critical problem that hampers
environmental successes is a lack of scientific expertise at
all levels. Representatives of TWG and AMWG are largely
administrators who are far removed from science. The
National Research Council has made several unheeded recommendations to GCMRC for an outside senior scientist
to serve as an advisory and interpretive liaison between the
science work groups and the secretary of the interior
(National Research Council 1999). In addition, GCMRC
administrators do not recruit outside objective researchers,
but instead use their own agency technicians for research
projects—a continuing problem from the GCES era. The
National Research Council has also identified conflicts
within GCMRC in executing its role of science coordination versus expending considerable effort performing
administrative tasks requested by AMP stakeholders.

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The GCD-AMP has not attained an integrated ecosystem approach to Colorado River scientific research. In reality,
the program appears to be following the historical pattern,
with physical resources, especially sediment retention,
continuing to dominate research funding and effort over
biological and cultural studies (Fritzinger et al. 2001). Sediment loss, movement, and retention remain primary investigation objectives, despite the fact that no data exist to
show a positive relationship between biological resources
and the amount of sediment in or along the river. The
impacts of Glen Canyon Dam encompass a wide range of
interconnected biological and ecological effects, yet biological
research since the inception of this program in 1997
remains unfocused and single-species directed.
To its credit the AMP has taken on a complex, controversial task and at least posits the need for a worldwide
river-resource-management plan. Although the concept of
adaptive management is good, adaptive-management programs of the past have been criticized for being all talk and
no action and for failing to change management policies
(Moir and Block 2001). A major drawback is the anticipation of quick environmental fixes, an unrealistic hope that
leads to a loss of commitment, effort, and funding to continue long-term studies to truly understand the ecosystem
(Hardin 1985).
Recent events indicate that the public is once again
awakening to the issues. A missing link in the GCD-AMP
identified by the National Research Council was public
outreach and education (National Research Council 1999).
The AMP finally added public outreach to its 2002
Monitoring and Research Plan (Fritzinger et al. 2001). In
addition, since 1997, environmental organizations have
been informing the public of their views of GCD-AMP
progress toward compliance with the Grand Canyon
Protection Act. Several prominent environmental groups,
including the Center for Biological Diversity, Living
Rivers, Sierra Club, and Audubon Society, joined in an
early 2002 effort to pressure the AMP to show progress in
their charge to protect the Grand Canyon ecosystem
(Living Rivers 2002). Although the AMWG voted not to
acknowledge receipt of the written challenge (per David
Orr, Living Rivers), a revised AMP operational plan complete with a series of experimental flows and nonnative fish
eradication efforts was announced to the public several
months later. Perhaps through the combined efforts of
long-term science and an involved society, future management decisions and legislation will reflect human values as
well as protect our natural treasures great and small while
they still exist.

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