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Glen Canyon Environmental Studies: An Interagency Effort
to Resolve Resorce Management Conflicts1
'1
John R. Thomar;'-
Abstract.--The Glen Canyon Environmental Studies are a
cooperative effort between four federal and state agencies to
quantify the effects of Glen Canyon Dam operations on n3tural and recreational resources in Glen and Gran~ Canyons and
to develop mitigation strategies for demonstrated
impacts.
The GCES are being conducted a~; a cooper-·
ative interagency effort by agencies with
management responsibilities for the Colorado River
in Glen and Grand Canyons.
This cooperative effort is
notable as
management qoals anrt
policies of the
participating a0encies can be,
anrt frequently are,
in riisaqreement.
The
i~­
volved agencies and their mandates are:
INTRODUCTION
The history of modern man's utilization
of the Colorado River is one of controversy.
As development of the arid Southwest progressed,
the Colorado River was
looked upon as the salvation of water
hungry enterprises.
Laws,
regulations,
and agreements were developed to allocate
the waters of the Colorado River,
effect
flood control and irrigation,
and generate power.
Often projects which were
designed to serve one entity were viewed
by other parties as detrimental to
their
interest.
In 1982,
a proposal by the
Bureau of Reclamation (BR) to
increase
the power generation capacity of Glen
Canyon Dam through generator uprating (BR
1982a)
resulted in conflict over the
priority given power generation versus
environmental concerns.
The Glen Canyon
Environmental
Studies
(GCES) were
initiated to facilitate resolution of this
conflict through detailed evaluation of
the impact of dam operations on instream
resources below Glen Canyon Dam.
This
paper will discuss the GCES and the agencies involved.
BR,
to
constnlct and operate water
development and flood control projects,
National
Pi:1.rk Service
(NPS),
to 0erpetuate natural
prOCP3ses and
provide
visitor use opportunities within
the
national parks,
Arizona Game and Fish Department (AGFD),
to manaqe terrestrial a.nd aquatic wildlife resources within Arizona for
consumptive and noncomsumptive 1.1'';(', and
U.S.
Fish and ~.-.Jildlife Service (USFWS),
enela nger,.;:,c!
to preserve migratory 3nd
wildlife on federal lands.
On one hand is BR, an aqencv with a clear
development mandate.
On the other
is
NPS,
USFWS, and AGFD, aqencies with pr0servation or conservation mandates.
That
these
two Ijroups 'Nould hav(.> conflictinq
qoals reqardinq the:> r.1il.naqernent of a
COfTlmon resource is almost inevitahle.
The purpose of the GCES is
to quantify
the
impacts of existing flow regimes and
the increase of maximum release capacity
through uprating to 33,100 cfs.
If the
GCES demonstrate that current operations
have a detrimental impact on downstream
resources then recommendations for alternative operating criteria will be made.
These recommendations will be evaluated
through an envi ronrnenta 1 impact s ta t~?rnf'n t
process.
Generator
Uprat~
Prooos~l
A major aspect of BR's mission at Glen
Canyon Dam is the qeneration of electrical power.
The oriqinal Glen Canyon
qenerators WE're not capable of utilizinq
the
full capacity of the
penstocks and
tlJrbinE~s.
Increasinq qenerator capacity,
o r up r ,1 tin q, VJ 0 U I d all 0 'N a ma x Ln urn 011 t put
frc)rT1 the rO'N(:~r plant of 1,336 meqa'Natts,
an
incn:asc of 168 ~1~v (BR 1982C1).
The
urn.l.te cl'/ould {(:'sult in tlv" not":"ntial
for
a
lGOn
cubic feet j)('I" ~,;('cond (cf~-~)
in-
1
Paper presented at the First North
American Riparian Conference,
Tucson,
Arizona, April 16-18, 1985.
2
Resources Management Specialist,
Grand Canyon National Park, Arizona.
72
crease in the maximum water discharge
through the powerplant (31,5000 to 33,100
cfs) .
In February 1982, a draft environmental
assessment for uprating the Glen Canyon
generators was issued by BR (BR 1982a).
The assessment met with substantial comment and concern from Grand Canyon interest groups, including government agencies
with management responsibilities below
the dam. These groups perceived a potential for exacerbation of ongoing impacts
associated with dam operations as a result of increased maximum discharge and
higher fluctuations.
Comment on the
assessment centered on two major points:
1)
BR did not have a data base which
could
accurately describe impacts of
uprating on downstream resources and 2)
the assessment did not address impacts of
existing
Glen Canyon Dam
operations
exclusive of uprating (BR 1982b).
Canyon averaged 140 million tons annually
with extremes ranging from 50 to 500
million tons. Upper basin sediments are
now trapped in Lake Powell.
As a result
of these major habitat changes three of
eight native fish species in Grand Canyon
have
been extripated
(Carothers
and
Johnson 1983).
Before completion of Glen Canyon Dam,
spring floods scoured the river channel
and reworked alluvial deposits.
These
floods no longer occur and as a result
extensive riparian ecosystems have developed along the river at the new post-dam
high waterline
(Carothers and Johnson
1983). Vegetation established at the old
pre-dam high waterline may be senescent
as the watering and reproduction resulting from pre-dam floods no longer occurs.
Without floods, there is no mechanism to
deposit sediment above the river stage
associated with maximum power plant discharge. Erosion has resulted in a net
loss of sand bar deposits in some areas
in Grand Canyon (Brian and'Thomas 1984).
The continuation of this process will
result in the loss of river runner campsites and substrate supporting Colorado
River riparian ecosystems
After release of the draft assessment,
the involved agencies participated in
extensive dialogue regarding the implications
of the uprate and impacts of
existing operations. A final environmental assessment was released in December
1982 with a Finding of No Significant
Impact
for
generator
uprating
(BR
1982b) .
BR made a commitment in the
final assessment
to 1) determine how
present
operations impact the
total
riverine environment in Grand Canyon and
to 2) undertake an analysis of alternative operating criteria to determine if
feasible alternatives exist which will
address concerns over existing operations. This commitment was to be met
through a cooperative effort between BR,
NPS, and USFWS with participation of
other Federal and non-Federal agencies.
The GCES are the foundation of this
effort.
Releases through the dam are controlled
by electrical power demand and downstream
water delivery
commitments.
Peaking
power demands create a daily river tide.
The resulting fluctuating flow pattern
can result in low flows which are unpassable for river runners and have a yet to
be determined impact on aquatic ecosystems.
In 1983, Lake Powell was not able to
contain the spring runoff.
It was necessary to bypass the power plant with releases through the spillways.
Discharge
ranged from 38,000 cfs to over 90,000 cfs
during June, July, and August 1983 (personal
communication,
BR) .
Alluvial
deposits were altered and riparian vegetation was impacted to varying degrees.
INFLUENCE OF GLEN CANYON DAM
The GCES are not addressing pristine
systems. The resources of concern have
been dramatically influenced by the dam
and its operation.
After completion of
Glen Canyon Dam in 1963, drastic changes
occurred in the physical and biological
nature of the Colorado River in Glen and
Grand Canyons. Historically, flow of the
Colorado River ranged from 700 cfs in
December 1924 to 127,000 cfs in July of
1927 (Carothers and Johnson 1983). Power
plant discharges can now range from 1000
cfs to 31,500 cfs.
Water temperature
fluctuated
seasonally
from over
70
degrees F in the summer months, to less
than 40 degrees F during winter.
Water
released through the power plant is now
consistently 46 degrees F due to the
location of penstock intakes below the
thermocline of Lake Powell. Prior to the
dam, sediment discharge through Grand
RESEARCH PROJECTS
The GCES are not directed at a single
resource, but rather, the riverine environment as a whole. The study addresses
this holistic approach through four substudies;
Sediment
Transport
and
Hydrology,
Terrestrial
and
Aquatic
Biology, Recreation, and Dam Operations.
BR is the lead agency and is providing
the majority of funding.
BR staff fill
the Project Manager and Sub-team leader
positions.
NPS, AGFD, and USFWS personnel are involved in the sub-teams
which reflect their agencies'
interests
and expertise; Sediment Transport- NPS,
Biology- NPS and AGFD, and USFWS, and
73
Recreation- NPS and BR.
2.
The importance of tributaries
native and exotic species.
The objective of the Sediment Transport
studies is to describe the relationship
between magnitude and fluctuation
of
discharge and the erosion,
movement, and
deposition
of alluvial sediments.
The
first task is to model the relationship
between channel erosion/deposition and
various discharge patterns.
To gather
data necessary for modeling,
sediment
transport and discharge sampling stations
have been established at five
locations
within the canyon and on three main Colorado River tributaries. Channel bottom
surveys using side-scan sonar, acousticvelocity profiler, and fathometer have
been employed to quantify the volume of
sediment in storage in the channel bed.
Sand bar studies will
investigate the
susceptability of beaches and banks to
erosion under various discharge regimes.
Sediment transport modeling will be integrated with sand bar research to predict
sand bar longevity resulting from various
flow regimes.
Sediment transport and
hydrology research is being conducted by
BR, u.S. Geological Survey, and NPS.
for
3.
The effects of fluctuating flows on
the life history of the alga Cladophora
glomerta.
4.
The effects of fluctuatino flows on
the life history of Gammarus lacustris
and fish utilization of this amphipod.
5.
The
natural
fishery.
importance of stocking
reproduction for
the
versus
trout
The aims of the terrestrial biology research are to quantify the effects of dam
operations on riparian vegetative community sucession,
herpetofauna and avifauna habitat; and to quantify impacts of
the 1983 floods on riparian communities.
Terrestrial biology research is being
conducted by NPS, BR, and AGFD.
Riparian vegetation community substrate
mapping based on 1960, 1973,
1980, and
1984 photography is being employed to
evaluate
succession and
colonization
trends.
Habitat requirements for herpetofauna and avifauna including vegetation
and substrate characteristics are being
determined.
The direct effects of fluctuating flows and floods on avifauna and
herpetofauna are also being assessed.
Impacts of the 1983 floods on new riparian zone vegetation are being quantified
through comparison of pre-flood data sets
with post-flood data.
The effects of
1983 floods on old high waterline vegetation will be determined by measuring
post-flood growth and reproduction rates
and comparing this data to evidence of
growth and reproduction in the postdam/pre-flood era. This analysis will
indicate if it is possible to perpetuate
this habitat via periodic spills releases. Avifauna and herpetofauna density
and diversity data are being gathered in
both the old and new riparian zones.
Results of the sediment transport research will be pivotal for the recreation
and biology studies.
Accurate prediction of the influence of dam operations
on recreation and biological resources
requires that sediment transport relationships are well understood.
The
majority of river runners use sand bars
for campsites, hence,
the fate of these
deposits is a major recreation issue.
The species composition, densities,
and
spatial extent of terrestrial and aquatic
communities are to a large degree determined by the substrates available.
The
future character of riparian and aquatic
substrates is directly tied to erosion
rates.
Aquatic biology research will evaluate
management practices and elements of the
post-dam Colorado River ecosystem which
are both important to the fishe~y and
influenced by dam operations.
The research is being conducted primarily by
AGFD.
Aquatic research findings will be
integrated with sediment transport study
predictions regarding changes in substrate, velocity, and river stage as a
function of specific flow regimes.
The
impact of dam operations on aquatic habitat and lower trophic level organisms
will
form the basis for
evaluating
effects on reproduction,
development,
distribution,
and relative densities of
native and exotic fishes.
Research is
divided into five main projects:
Terrestrial biology research will determine the best case future scenario for
the extent of riparian vegetation based
on the direction and rate of succession
and
availability of substrates
for
colonization, effects of flow regimes
including floods on the species composition and structure of these communities,
and effect of changes in vegetation on
avifauna and herpetofauna populations.
Sediment transport research will predict
the extent of available substrates under
various flow regimes.
These analyses
will
allow prediction of the future
status of riparian ecosystem conditions
under various flow regimes.
If preservation of one habitat, old or new zone,
requires the sacrifice of the other, then
information on the relative importance of
each in terms of flora and fauna density
1. The importance of mainstream habitats
for native and exotic fish species and
the impact of fluctuating flows on those
habitats.
74
and diversity will be available.
this process will be based on the research findings and alternative operational strategies of the GCES.
Areas of concern in recreation are the
effect of flows on safety, on number of
river runner contacts, and the ability of
river runners to experience those aspects
of Grand Canyon which they value, such as
side canyon hikes and sand beaches for
camping.
The
safety issue will be
addressed through analysis of the correlation between accidents and flow levels.
The
Wilderness Use Simulation
Model
(Shechter and Lucas 1978) has been modified to define contact levels as a function of launch schedules.
The relationship of contacts to flow will be
determined by modifying the model to
allow the incorporation of flow rates in
the calculation of contact levels.
A
contingent valuation method study will be
used to determine the relative value to
the river runner of flow sensitive attributes
of
the
Grand
Canyon
river
experience.
If in decisions following the
GCES,
environmental concerns are considered on
an comparable basis with power generation
then a major precedent in Colorado River
politics and management will have been
established.
This precedent will not
diminish future conflicts, but will ensure
a more even treatment for all
resource values.
LITERATURE CITED
Brian, J. N. and J. R. Thomas. 1984. 1983
Colorado River beach campsite inventory.
Unpubl.
report, Grand Canyon
National Park, Arizona.
Bureau of Reclamation.
1982 a.
Draft
environmental
assessment for Glen
Canyon powerplant uprating.
Upper
Colorado Region,
Salt Lake City,
Utah.
The Operations study will define the
legal and administrative constraints on
Glen Canyon Darn operating criteria.
The
limits on mitigating strategies will be
determined through this analysis.
Bureau of Reclamation. 1982 b. Finding of
no significant impact for Glen Canyon
powerplant uprating.
Upper Colorado
Region, Salt Lake City, Utah.
The final project report will compile all
of the component studies and describe
impacts to downstream resources resulting
from various flow regimes.
Glen Canyon
Darn operational strategies which mitigate
impacts will be identified.
If,
as is
probable, certain regimes favor one resource,
including power generation, over
another then the real nature of cooperation between the involved agencies will
be exhibited. The recommendations for
alternative operating criteria will result from a process of negotiation and
compromise.
If significant impacts are
identified,
an
environmental
impact
statement process will be
initiated.
Carothers,
S.W. and R.R. Johnson. 1983.
Status of the Colorado River ecosystem in Grand Canyon National Park and
Glen Canyon National Recreation Area.
in Procedings of the 1981 Symposium
on Aquatic Resources Management of
the Colorado River Ecosystem,
Utah
State University, Logan, Utah.
Shechter, M. and R.C. Lucas. 1978. Simulation of recreational use for parks
and wilderness management.
Resources
for
the Future,
Inc. Johns Hopkins
University
Press.
Baltimore,
Maryland.
75