Chapter 1. Bureau of Reclamation Glen Canyon Dam Adaptive Management Program Triennial Budget and Work Plan—Fiscal Years 2018–2020
- Adaptive Management Work Group (AMWG) Costs
- Technical Work Group (TWG) Costs
- Program Administration, ESA Compliance, and Management Actions
- NHPA Compliance and Cultural Resources Program Management
Chapter 2. U.S. Geological Survey, Southwest Biological Science Center, Grand Canyon Monitoring and Research Center Triennial Budget and Work Plan—Fiscal Years 2018–2020
- Administrative History and Guidance That Informs This Work Plan
- 2011 Draft General Core Monitoring Plan
- 2012 AMWG Desired Future Conditions
- 2016 LTEMP ROD
- 2017 LTEMP Science Plan
Project A: Streamflow, Water Quality, and Sediment Transport and Budgeting in the Colorado River Ecosystem
The primary linkage between Glen Canyon Dam (GCD) operations and the characteristics of the
physical, biological, and cultural resources of the CRe downstream from GCD is through the
stage, discharge, water quality, and sediment transport of the Colorado River. This project makes
and interprets the basic measurements of these parameters at locations throughout the CRe. The
data collected by this project are used to implement the HFE Protocol (i.e., trigger and design
HFE hydrographs), to evaluate the reach-scale sand mass-balance response to the HFE Protocol
(U.S. Department of the Interior, 2011; Grams and others, 2015), and to evaluate the downstream
effects of releases conducted under the LTEMP EIS (U.S. Department of the Interior, 2016a, b).
The data collected by this project are also required by the other physical, ecological, and sociocultural
projects funded by the GCDAMP. Most of the project funds support basic data
collection at USGS gaging stations, with only a small amount of project funds supporting
interpretation of basic data. The funds requested under this proposal cover only ~70% of the
costs required to operate and interpret data at the network of USGS gaging stations used by this
project; other funding for this network is provided to the USGS Arizona Water Science Center
from funds appropriated by Congress for the USGS, the Bureau of Land Management, and the
Arizona Department of Environmental Quality (AZDEQ). This project is designed to provide
measurements of stage (i.e., water elevation), discharge (i.e., streamflow), water quality, and
suspended sediment at sufficiently high temporal resolutions (~15-minute) to resolve changes in
these parameters and to allow accurate determination of suspended-sediment loads for use in
sediment budgeting. The proposed monitoring under this project will be very similar to that
conducted over the last 5-10 years.
The 3 elements of this project are as follows:
Stream gaging:
This element partially funds the collection, serving, and interpretation of continuous 15-minute
measurements of stage and discharge on the main-stem Colorado River at USGS streamflow
gaging stations located at river miles (RM) 0, 30, 61, 87, 166, and 225, and at gaging stations on
the major tributaries and in a representative subset of the smaller, formerly ungaged tributaries
(Water Holes Canyon, Badger Creek, Tanner Wash, House Rock Wash, North Canyon, Shinumo
Wash, and Bright Angel Creek).
Water quality:
This element funds the collection, serving, and interpretation of continuous 15-minute
measurements of water temperature, specific conductance (a measure of salinity), turbidity, and
dissolved oxygen at the above-mentioned six mainstem Colorado River gaging stations, as well
as continuous measurements of water temperature at additional stations on the Colorado River
and in the major tributaries. In addition, this element provides a small amount of funding toward
the logistics required to collect samples for laboratory water-chemistry analyses (including
nutrients) at gaging stations on the Colorado River.
Sediment transport and budgeting:
This element funds the collection, serving, and interpretation of continuous 15-minute
measurements and also episodic measurements of suspended sediment and bed sediment at the
above-mentioned gaging stations on the Colorado River and its tributaries. The continuous
suspended-sediment measurements at the six mainstem Colorado River gaging stations, and the
episodic suspended-sediment measurements in the tributaries are used in the construction of
mass-balance sand budgets. These budgets inform scientists and managers on the effects of dam
operations on the sand mass balance in the CRe between Lees Ferry and Lake Mead divided into
6 reaches (Figure 1). Increases in the sand mass balance in a reach indicate an increase in the
amount of sand in that reach and therefore an increase in the amount of sand available for
sandbar deposition during HFEs, whereas decreases in the sand mass balance in a reach indicate
a net loss of sand from that reach. All measurements made by this project are made using
standard USGS and other peer-reviewed techniques. All of these measurements can be plotted
and/or downloaded at: https://www.gcmrc.gov/discharge_qw_sediment/ or
https://cida.usgs.gov/gcmrc/discharge_qw_sediment/. Plots of continuous parameters can be
made in time-series or duration-curve formats. In addition, the user-interactive mass-balance
sand budgets for the six CRe reaches are available at this website (Sibley and others, 2015). In
addition to the collection and serving of the basic streamflow, water-quality, and sedimenttransport
data, time is spent in this project interpreting the data and reporting on the results and
interpretations in peer-reviewed articles in the areas of hydrology, water quality, and sediment
transport. The interpretive papers published by this project are designed to address key questions
relevant to river management, especially to management in the GCDAMP. To date, this ongoing
project has published over 80 peer-reviewed journal articles, books, proceedings articles, and
USGS reports, a full listing of which are available at: qt-science_center_objects link. This website also provides urls to
download these publications.
Project B. Sandbar and Sediment Storage Monitoring and Research
The purposes of this project are to a) track the effects of individual HFEs on sandbars, b) monitor
the cumulative effect of successive HFEs and intervening operations on sandbars and sand
conservation, and c) investigate the interactions between dam operations, sand transport, and
eddy sandbar dynamics.
The sand deposits on the bed and banks of the Colorado River in Glen, Marble, and Grand
Canyons are directly affected by the operations of GCD. Depending on the relative magnitudes
of dam releases and tributary sediment inputs, sand either accumulates or is eroded from the bed
of the river. When evaluated over long river reaches, sand is evacuated from the river bed during
sustained periods of high dam-releases (Topping and others, 2000; Grams and others, 2015) and
sand accumulates during periods of average dam-releases and substantial tributary sediment
inputs (Grams, 2013; Grams and others, 2013). Sandbars along the river banks above average
base flow (about 8,000 ft3/s) also change in response to dam operations, but in a different pattern,
because they are not always inundated and because they comprise a small fraction of the sand in
the system (Hazel and others, 2006; Grams and others, 2013). These deposits aggrade
significantly during HFEs that exceed powerplant capacity (Schmidt and Grams, 2011) and, to a
lesser extent, during powerplant capacity flows (Hazel and others, 2006). These deposits
typically erode during normal powerplant operations between HFEs (Hazel and others, 2010).
One of the stated goals in the ROD for the recently completed LTEMP (U.S. Department of the
Interior, 2016) is to "increase and retain fine sediment volume, area, and distribution...for
ecological, cultural, and recreational purposes." Expectations of improved sandbar building and
conservation of sediment were among the criteria used in the selection of the preferred
alternative. One of the central components of the selected alternative is the continued
implementation of HFEs for building sandbars. The LTEMP extends the program initiated with
the Environmental Assessment for Development and Implementation of a Protocol for HighFlow
Experimental Releases from Glen Canyon Dam (HFE Protocol) which asked the question,
"Can sandbar building during HFEs exceed sandbar erosion during periods between HFEs, such
that sandbar size can be increased and maintained over several years?" In other words, does the
volume of sand aggraded into eddies and onto sandbars during controlled floods exceed the
volume eroded from sandbars during intervening dam operations? Additional, conditiondependent
experiments are included in the preferred alternative, with objectives related to
sandbar building and sediment conservation. Project B includes elements that are designed to
evaluate whether the sediment-related goals of the LTEMP are met, provide the information that
is needed to proceed with or abort LTEMP experimental activities, and evaluate the effectiveness
of implemented experiments.
Thus, one of the most important objectives of Project B is to monitor the changes in sandbars
over many years, including a period that contains several controlled floods, in order to compile
the information required to answer the fundamental question of the HFE Protocol. The
monitoring program described here continues the program implemented in previous work plans
and is based on annual measurements of sandbars, using conventional topographic surveys
supplemented with daily measurements of sandbar change using ‘remote cameras’ that
autonomously and repeatedly take photographs. These annual measurements and daily
photographs are included in Project Element B.1. This project element also includes work to
more efficiently conduct quantitative analyses of the remote camera images. Because these longterm
monitoring sites represent only a small proportion of the total number of sandbars in Marble
and Grand Canyons, Project Element B.2 includes periodic measurements of nearly all sandbars
within individual 50 to 130 km sediment budget reaches (see Project A for description of
sediment budget reaches).
Another critical piece of information that is needed to evaluate the outcome of the HFE Protocol
and the LTEMP is the change in total sand storage in long river reaches. HFEs build sandbars by
redistributing sand from the low-elevation portion of the channel to sandbars in eddies and on the
banks. The sand available for deposition is the sand that is in storage on the channel bed, which
is the sum of the sand contributed by the most recent tributary inputs, any sand that may have
accumulated since GCD was completed, and any sand that remains from the pre-dam era. The
goal of the HFE protocol is to accomplish sandbar building by mobilizing only the quantity of
sand most recently contributed by the Paria River, thereby preventing depletion of pre-dam era
sand. Some of the sand mobilized by HFEs is deposited in eddies where it builds eddy sandbars.
Some of the sand is eventually transported downstream to Lake Mead. The most efficient floods
for the purposes of sandbar building are those that maximize sandbar aggradation yet minimize
the amount of sand transported far downstream, thus minimizing losses to sand storage. Dam
operations between HFEs also transport sand downstream, causing decreases in sand storage.
Sediment delivered by the LCR also contributes to sand storage downstream from the LCR
confluence. However, this tributary has contributed only a small fraction of the quantity of sand
delivered by the Paria River (Griffiths and Topping, 2015) and is not included in the HFE
protocol.
Measured trends in sand storage along the channel bed combined with trends in exposed
sandbars will provide the necessary context on which to base future decisions about dam
operations and other potential management options. If sand storage is maintained or increased,
we expect the response to future HFEs to be similar to or better than that observed following
recent HFEs. In contrast, depletions of fine sediment in the active channel are potentially
irreversible if sand supply from tributaries is consistently less than downstream transport. This
situation would threaten the long-term ability to maintain eddy sandbars. These long-term trends
are measured in Project Element B.2, which includes one “channel mapping” campaign to map
changes in sand storage in both lower Marble Canyon (RM 30-61) and eastern Grand Canyon
(RM 61-87) in 2019. Because these sediment-budget reaches have been mapped previously and
because mapping efficiency has increased, we are able to map longer river reaches in a single
river trip than previously. These data will be used to provide long-term (8 to 10 year)
assessments of sandbar and sand storage change for these reaches and a robust evaluation of 7
years of implementation of the HFE Protocol. Project Element B.3 includes work to improve the
control network in support of this and other work plan projects, with focus on the segment
between RM 87 and RM 166, which has never been mapped. The control work is needed to
prepare for mapping this segment in the next (FY2021-23) work plan.
This project also includes one element that provides contingency data collection for HFE
experiments. Project Element B.4 describes studies that will be conducted to monitor and
evaluate the condition-dependent experiments that affect sandbars and sediment resources. This
work plan also includes description of two research components that, because of budget
constraints, were not funded. Project Element B.5 describes a modeling project to produce flow
models that predict the inundation extent and flow velocities for dam operations and HFEs in
Marble Canyon and improve capabilities for predicting sandbar response to dam operations. The
modeling project element also includes description of proposed laboratory experiments to
address the same suite of questions as the condition-dependent experimental HFEs are designed
to test. Project Element B.6 is a research project that proposes to investigate river channel
adjustment and redistribution of reservoir delta sediment on the Colorado River within the CRe
between Diamond Creek and the western boundary of Grand Canyon National Park.
Project C. Riparian Vegetation Monitoring and Research
This project seeks to monitor riparian vegetation response to dam operations in order to
determine if the LTEMP Resource Goals for riparian vegetation are being met (Elements 1 and
2), use the data created by riparian vegetation monitoring in Elements 1 and 2 to address gaps
related to predicting the responses of vegetation to dam operations (Element 3), and support the
implementation of experimental vegetation treatments directed by the LTEMP ROD (Element 4).
Monitoring the state of riparian vegetation along the mainstem is ongoing and critical for
understanding the effects of dam operations on riparian vegetation and associated resources.
Long-term monitoring assesses if riparian vegetation is being maintained “in various stages of
maturity, such that they are diverse, healthy, productive, self-sustaining, and ecologically
appropriate” and assesses if dam operations under the new ROD, daily and experimental flows,
have the expected result of “more native plant community cover, higher native plant diversity, a
higher ratio of native to nonnative plants, less arrowweed, and more wetland,” (VanderKooi and
others, 2017). This project utilizes annual field measurements (Element 1) and digital imagery
(Element 2) for integrated monitoring of changes in vegetation at river segment (for example
Glen Canyon, Marble Canyon, etc.) and system-wide scales. Included in monitoring are a 5-year
assessment of vegetation change (Element 1) and an analysis of a new system-wide remote
sensing vegetation classification for, providing an assessment of tamarisk beetle defoliation from
2009-2013 and sand/vegetation turnover dynamism (Element 2). Each of these products provides
an assessment of the status of plant communities identified as being of interest or concern by
stakeholders. Elements 1 and 2 are complementary methods of vegetation monitoring that
determine status and trends at different spatial and temporal scales (Palmquist and others, in
press). These two elements will be integrated through an assessment of relations between finescale,
ground-based monitoring with the coarser-scale, spatially continuous remotely-sensed
data. This assessment will allow us to identify the appropriate frequency of the ground-based
monitoring (annual, biennial, or otherwise) and to integrate ecological processes occurring across
different spatial and temporal scales.
Element 3 proposes to analyze vegetation data from Elements 1 and 2, existing historic
vegetation data, and flow data to examine the influence of dam operations and other
environmental variables on riparian vegetation distribution and address other knowledge gaps
regarding vegetation response. A recent knowledge assessment that was conducted to identify
the current understanding of vegetation response to dam operations elucidated uncertainties
regarding how daily flows and experimental flows impact vegetation complexity, functional
diversity, and species composition. We plan to address some of these uncertainties by creating
predictive models of vegetation responses to LTEMP flow scenarios based on the vegetation
monitoring and remote-sensing products outlined above (and described below). These predicted
outcomes will be generated across multiple spatial scales in order to better understand how
experimental flows are impacting the integrity of riparian vegetation. The results of this work
will help predict vegetation response to dam operations outlined in the LTEMP, help assess if the
LTEMP management goals for vegetation are advancing, and inform the parameters in which
vegetation management will be most successful.
As stated in the LTEMP ROD, NPS and tribal partners will coordinate with GCMRC to conduct
targeted vegetation removal and plantings, including “control of nonnative plant species and
revegetation with native species (U.S. Department of Interior, 2016).” Project element 4 will
help address information needs and management design required for the successful
implementation of this required vegetation management. The NPS, Tribes, and other
stakeholders will also seek to preserve sand resources, camp sites, and archeological sites
through vegetation removals, restore native riparian plants by planting native species, and control
exotic plants. The long-term success of planting efforts will depend on matching genetically
suitable plant material to specific sites varying in substrate stability and existing vegetation.
Monitoring of post-removal vegetation trajectories could identify how successional processes
interact with dam operations, determine methods for the long-term preservation of these sites,
and prioritize needs for future interventions on a site-by-site basis. These sites will encompass
only a small portion of the riparian corridor and will have different goals and locations from the
monitoring outlined in Elements 1 and 2, so this work cannot replace ongoing monitoring efforts
throughout the CRe.
Project D. Geomorphic Effects of Dam Operations and Vegetation Management for Archaeological Sites
Glen Canyon Dam has reduced downstream sediment supply to the Colorado River by about
95% in the reach upstream of the Little Colorado River confluence and by about 85% below the
confluence (Topping and others, 2000). Operation of the dam for hydropower generation has
additionally altered the flow regime of the river in Grand Canyon, largely eliminating pre-dam
low flows (i.e., below 5,000 ft3/s) that historically exposed large areas of bare sand (U.S.
Department of the Interior, 2016a; Kasprak and others, 2017). At the same time, the combination
of elevated low flows coupled with the elimination of large, regularly-occurring spring floods in
excess of 70,000 ft3/s has led to widespread riparian vegetation encroachment along the river,
further reducing the extent of bare sand (U.S. Department of the Interior, 2016a, Sankey and
others, 2015).
The changes in the flow regime, the reductions in river sediment supply and bare sand, and the
proliferation of riparian vegetation have affected the condition and physical integrity of
archaeological sites and resulted in erosion of the upland landscape surface by reducing the
transfer (termed “connectivity”) of sediment from the active river channel (e.g., sandbars) to
terraces and other river sediment deposits in the adjoining landscape (U.S. Department of
Interior, 2016a; Draut, 2012; East and others, 2016). Many archaeological sites and other
evidence of past human activity are now subject to accelerated degradation due to reductions in
sediment connectivity under current dam operations and riparian vegetation expansion tied to
regulated flow regimes (U.S. Department of the Interior, 2016a; East and others, 2016).
The LTEMP EIS predicts that conditions for achieving the goal for cultural resources, termed
“preservation in place”, will be enhanced as a result of implementing the selected alternative.
HFEs are one component of the selected alternative that will be used to resupply sediment to
sandbars in Marble and Grand Canyons, which in conjunction with targeted vegetation removal,
is expected to resupply more sediment via wind transport to archaeological sites, depending on
site-specific riparian vegetation and geomorphic conditions (Sankey and others, 2017).
At the same time, HFEs can also directly erode some river sediment deposits containing cultural
resources, particularly large terraces in the Glen Canyon reach (U.S. Department of Interior,
2016a).
This project quantifies the geomorphic effects of ongoing and experimental dam operations, as
well as the geomorphic effects of riparian vegetation expansion and management, focusing on
effects to the supply of sediment to cultural sites and terraces. The ongoing and experimental
dam operations and vegetation management of interest are those that will be undertaken under
the LTEMP ROD (U.S. Department of the Interior, 2016b) during the next 20 years. The data
and analyses from this project will allow the GCDAMP to objectively evaluate whether and how
these non-flow and flow actions affect cultural resources, vegetation, and sediment dynamics,
and how they ultimately affect the long term preservation of cultural resources and other
culturally-valued and ecologically important landscape elements located within the river corridor
downstream of GCD.
Project E. Nutrients and Temperature as Ecosystem Drivers: Understanding Patterns, Establishing Links and Developing Predictive Tools for an Uncertain Future
Ecosystem temperature and nutrient dynamics can influence both species composition and
metabolic rates across many different types of ecosystems (Allen and others, 2005; Brown and
others, 2004; Elser and others, 2003; Elser and others, 1996; Yvon-Durocher and others, 2012).
Given the importance of nutrients and temperature as drivers of the aquatic ecosystem, it is
important to understand their spatio-temporal patterns both because they may be altered by
management actions considered in the LTEMP, and because they may provide essential context
for interpreting responses to flow experiments. Given the potential importance of nutrients and
temperature in driving CRe dynamics, we propose monitoring, research and modeling to: 1)
identify processes that drive spatial and temporal variation in nutrients and temperature within
the CRe, and 2) establish quantitative and mechanistic links among these ecosystem drivers,
primary production, and higher trophic levels. Parallel work in Lake Powell that aims to identify
the controls on nutrient concentrations in the GCD outflow is planned with external funding from
Bureau of Reclamation (see Appendix 1).
Both temperature and nutrients change in response to various processes. A dense network of
stream gaging stations in Grand Canyon provides information on temperature at fine temporal
resolutions (Project A) and a temperature model exists to predict downriver temperature (Wright
and others, 2008). This model was used to predict responses of downriver native fish populations
and warm water non-native fish species to management alternatives in the LTEMP. Although the
Wright and others (2008) temperature model was a valuable tool for EIS modeling efforts, it has
important limitations. For example, Wright and others (2008) clearly acknowledge that their
model overestimates temperatures in downstream reaches during fall low flow months by as
much as 2 °C, however, this assumption does not appear to have been acknowledged in LTEMP
modeling of downstream temperatures. We are currently modifying Wright’s model and propose
to finish this work in FY2018. These modifications are expected to improve downriver
predictions.
In contrast to our detailed understanding of temperature, we lack even a basic understanding of
gross patterns in nutrient concentrations and their variation over time and along the river. SRP,
the most bioavailable phosphorus, is likely to be especially important given the high N:P in the
CRe, but our understanding of patterns in soluble reactive phosphorus (SRP) availability is
especially lacking. While continuous nutrient monitoring at Lees Ferry shows a strong
correspondence between nutrient availability in the reservoir outflow and in the Lees Ferry reach
(Vernieu, 2009), there are very few measurements of nutrients downstream of the Paria River
inflow, with no measurements of SRP routinely made. While the dam releases contribute
substantially more discharge than all tributary inputs combined, tributaries like the Paria River
and LCR are the major sources of sediment and labile organic matter inputs to the Colorado
River and can drive riverine suspended sediment dynamics independent of total river discharge
(Topping and others, 2007; Ulseth, 2012). In the Paria River, total phosphorus concentrations are
1-2 orders of magnitude higher than in the mainstem Colorado (Lawson, 2007; Deemer
unpublished data). While total phosphorus and SRP are both relatively low during baseflow in
the LCR (Deemer, unpublished data; Moody and Muehlbauer, unpublished data), we expect that
storm events may flush significant amounts of P into the Colorado before this P has time to be
sequestered via abiotic reactions (as is highly likely to be occuring during baseflow). More
generally, nutrient loads are likely to vary, at least in part, with suspended sediment loads such
that storms may be important to overall budgets in the Paria River as well.
Indirect evidence suggests that reservoir inputs may dominate nutrient concentrations in the
upper parts of the CRe, but other factors may become more important downriver. For example,
as nutrient concentrations in Lake Powell declined during 2014, Colorado River invertebrate and
fish populations between GCD and Lees Ferry and near the LCR confluence declined
dramatically. However, in more downriver portions of the CRe, the catch of humpback chub,
especially juvenile life stages, was higher in 2014 than in prior years. This suggests either that
nutrient limitation is currently not a controlling factor in the lower half of the CRe (see
hypotheses H5, H6, and H8 in Project G), or that there are unaccounted sources of nutrients in
the lower CRe. These unaccounted sources of nutrients in the lower CRe could consist of
tributary inputs, release of geologically bound P under different environmental conditions, or
elevated mineralization with higher temperature and/or organic matter inputs (see hypothesis H7
in Project G).
To address these critical management uncertainties, we propose a multi-pronged approach that
aims to better understand processes affecting temperature and nutrient availability in the CRe,
and to further investigate links between these drivers and Colorado River food webs. We have
used the available literature and data to generate a suite of 11 hypotheses which are outlined
below. While there are many other hypotheses one could generate to describe patterns in
nutrients and temperature and their effects on higher trophic levels, we have done our best to
select what we believe are the most probable, management-relevant, and feasible-to-test
hypotheses with the intention that we can build on this information in future work plans.
Project F. Aquatic Invertebrate Ecology
Project G. Humpback Chub Population Dynamics throughout the Colorado River Ecosystem
Project H. Salmonid Research and Monitoring
Project I. Warm-Water Native and Non-Native Fish Research and Monitoring
Project J. Socioeconomic Research in the Colorado River Ecosystem
Project K. Geospatial Science and Technology
Project L. Remote Sensing Overflight in Support of Long-term Monitoring and LTEMP
Project M. Administration
Project N. Hydropower Monitoring and Research
Appendices
- Appendix 1. Lake Powell Water Quality Monitoring
- Appendix 2a. Potential Budget Allocation Summary by Project and Year
- Appendix 2b. Potential Budget Allocation – FY2018
- Appendix 2c. Potential Budget Allocation – FY2019
- Appendix 2d. Potential Budget Allocation – FY2020
- Appendix 2e. Potential Budget Allocation Experimental Projects
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