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Slide 1: Kaylee Nelson: Good afternoon. This is Kaylee Nelson with the Bureau of Reclamation.
Thank you for joining us on this educational outreach session on the Colorado River Basin Study.
Because more than 100 people are joining the webinar we will be muting the webinar except for the webinar presenters.
To ask a questionplease type your question into the question box on the webinar tool bar.
We will address questions at the end of the presentation.
And now I'd like to introduce Carly Jerla, Reclamation's Co-Manager for the Colorado River Basin Water Supply and Demand Study.
Carly Jerla: Thank you Kaylee and thank you everyone for joining us here today for this webinar.
Before we get started I also want torecognize the Study Manager for our cost-share partners, the Seven Basin States, and that was
Kay Brothers with Southern Nevada Water Authority.
So this is the final of three outreach sessions that we have been putting on. And the reason that we are doing these outreach sessions is to
provide the public a more - an opportunity for a more in-depth understanding of the findings in this very complex and technical study.
We have about a three hour webinar scheduled today. There will be 30 minutes allotted at the end for questions and we will have a ten minute
break in between at about an hour into the study.
And as Kaylee indicated you all are on mute and if you have any questions please feel free to type those in and we will begin answering those
during our question-and-answer session.
Slide 2: Carly Jerla: This is the agenda for today's outreach session. I will start with a brief
introduction; then talk about the water supply and demand assessment portion of the study.
I will then talk about the options and strategies that were explored in the study and the development of the strategies or the portfolios
which are groups of options. We will then break for about ten minutes.
And then Ken Nowak and Alan Butler who were the technical leads for the modeling aspects of the study - will take over and present the
system reliability analysis, both the methodology and the results;
leading us up to really the open question-and-answer session which will be about 2-1/2 hours into the webinar.
Slide 3: Carly Jerla: The introduction portion of this session will be comprised of a short background
on the layout of the Colorado River Basin.
I will talk briefly about the WaterSMART Program; this is what the Basin Study Program is a part of
and what the study was conducted under.
I will then do a broad overview of the basin study and talk about the objectives and the phases that we -
that the study was laid out in to accomplish those objectives. And then briefly talk about the final report and how to comment on that report.
Slide 4: Carly Jerla: So as many of you know the setting of the Colorado River Basin; it's approximately
250 square miles. It spans from the headwaters of the Green River in Wyoming down to Mexico.
The study area, the area of which the study is conducted over, is defined as the hydrologic boundaries of the basin and those adjacent
areas that receive Colorado River water. And those adjacent areas are denoted on the map in the red hatched areas.
The annual allocations in the basin do exceed the basin long-term average flow. That long-term average flow has been about 15 million acre feet
over the past 100 years.
We're going to use the term natural flow a lot when we're talking about supply on the basin.
And that term really means what is the flow into the basin had humans not existed; so without the impact of humans depleting the flow or any
reservoir regulation on the system.
We talk about the term Lees Ferry a lot also when we're measuring the total flow on the basin. And that's a point just below Lake Powell
where about 90% of the flow in the basin culminates at and that's a really good measure of the total flow in the basin.
So you'll hear that term a lot as well.
Those flows are highly variable and we'll see that in figures - in a couple slides away. And due to the storage that we have on this system,
the ability to store four times that average annual in-flow or about 60 million acre feet; that storage has provided us flexibility in meeting
those demands.
The system has worked really exactly as it has been designed; we've been able to store water in high flow years to meet demands during the
lower flow years.
And because of that we have essentially made all of our delivery commitments despite having pretty severe drought on the basin over the last
ten years.
The system is managed in accordance with the Law of the River.
This is a compilation of documents dating back to the 1922 Colorado River Compact.
And this Law of the River is constantly evolving and is what we manage our system under.
Slide 5: Carly Jerla: This figure shows the historical annual basin supply and use over the roughly
last 100 years; so dating back to 1914.
The blue line is the annual water supply; this is a measure of total basin supply. And the red line is the annual basin water use;
so this is a measure of the total use on the basin.
You can clearly see that the use has been on the increase really since the last 100 years while the supply has been very, very variable.
There has been many years in the past where our use has exceeded the supply and as I mentioned previously due to our reservoir
storage we have been able to meet deliveries during those periods despite that imbalance.
Slide 6: Carly Jerla: If we look at the ten year running average of these two lines; so this is the same
data we looked at in the previous figure, but we're now looking at the 10-year running average to better view the trends.
You can clearly see supply - or sorry, use is increasing while supply has really started to decrease in the last ten years.
That's the recent drought we've been experiencing. And we have really surpassed the supply over the last ten years.
And we know that we are currently in an imbalance in this system.
And as we move forward and really the purpose of the study is to see how those supply and demand curves are going to change moving into
the future over the next 50 years.
Slide 7: Carly Jerla: Reclamation's WaterSMART initiative puts into place many different activities
that allow us to conduct studies that are going to look at these types of issues.
The WaterSMART initiative puts into place authority set forth in the SECURE Water Act; the SECURE Water Act was passed into law on
March 30, 2009.
And this statute establishes that Congress find an adequate and safe supply of water to meet many of the fundamental things that water
is essential for. And to do so considering the impact of global climate change.
There are three major programs that are in place to tackle these issues.
The basin study deals with risks, impacts, adaptation and mitigation strategies and is looking towards feasibility type studies after the
completion of a basin study.
Slide 8: Carly Jerla: So underneath that Basin Study Program,
the Colorado River Basin Water Supply and Demand Study was conducted.
The objective of the study is broad and that's the same for any basin study that's conducted under this program.
The objective is to assess future water supply and demand imbalances over the next 50 years in the basin and to develop and evaluate
opportunities or options and strategies for resolving those imbalances.
Every basin study has a cost-share component, so it's conducted with stakeholders throughout the basin.
This basin study was conducted by Reclamation and the agencies representing the Seven Basin States that was roughly equally cost-shared.
And those cost-share partners are listed in the table there on the right.
But, it was also conducted in collaboration with stakeholders throughout the basin; many Native American tribes and communities,
conservation organizations, recreational organizations and others were very involved in the study.
And their involvement was critical to the success of the study.
The study was about a three year effort. It began in January of 2010 and it was completed just in December of last year.
And the study is exactly that; it's a study. It does not result in any decisions.
It is not a NEPA analysis or an EIS; there is no recommendations on how to move forward to resolve future imbalances.
Its aim is really to provide a technical foundation for future activities and for future discussions to build upon.
Slide 9: Carly Jerla: The study consists of four major phases to accomplish
the objectives of the study.
In the first phase which is the water supply assessment we're looking 50 years into the future and projecting what water supply might
look like on this basin under a range of different future scenarios.
And the water supply - sorry in Phase 2, water demand assessment, we're doing the same thing except for demand.
We're looking 50 years into the future, trying to understand how demand under many different sectors may be changing on this basin.
In Phase 3 we bring those projections of supply and demand together to understand how the system reliability changes under those
scenarios.
And this is understood by first identifying what we call system reliability metrics.
These are things that are going to indicate how well the resources that the system operates for are performing.
Once we understand how well the resources are performing, then we can think about different opportunities to enhance performance of those
resources or resolve those supply and demand imbalances.
And we do that in Phase 4 beginning with the development of those opportunities, testing the effectiveness of those against how well system
reliability improves and then the finalization of those opportunities.
Slide 10: Carly Jerla: The study had a consultant team that consisted of CH2M Hill and
Black & Veatch.
These consultants were brought onto the study early on in April of 2010 and really provided the overall support for the study
as well as bringing technical assistance to the supply and demand assessment and the other components listed here.
They also provided technical integration across all aspects of the study and documentation support.
Early last year the RAND Corporation was brought on really to provide support for the system reliability phase of the study and also
the vulnerability assessment and the portfolio development and evaluation which we will get into a little later in the session.
Slide 11: Carly Jerla: The final study report is really a collection of reports.
There are seven technical reports, A-G, that are going to cover roughly and about a total of 1500 pages; all technical aspects of the study.
Those 1500 pages are summarized in a 100 page study report which also contains discussion of the next steps after the study.
And then there is a much shorter 20 page executive summary that we'll summarize each major technical finding in the study.
All of those documents are available for download up on our website and we are also happy to provide CD's of the document at
request.
Slide 12: Carly Jerla: You can request one of those CD's and also submit comments on any of the details
found in the study by the website or email listed here. We are asking comments to be submitted by April 19 and there's a variety of ways to
submit those comments.
What we plan to do with these comments is to summarize them and post them to our website and use these as we move forward both in next
steps after the study, but in future basin planning activities as well.
Slide 13: Carly Jerla: So that's covers the broad introduction into the study.
I'm now going to shift into the water supply assessment; this was the first phase of the study.
I'll talk shortly about the objective of this phase and then talk through the development of our water supply scenarios and then the
quantification of those scenarios.
Slide 14: Carly Jerla: The objective of the water supply assessment was to assess the probable
magnitude and variability of both the historical and future natural flow in the basin.
And as I mentioned before, natural flow represents the flow that would have occurred at a location without the impact of human
depletions or reservoir regulation upstream of that location.
This assessment includes the potential effects of both future climate variability and change.
Slide 15: Carly Jerla: Because we wanted to look very broadly in terms of what future supply might look
like on the basin, we identified four different scenarios.
I'm going to step through the scenarios one by one and as I do so think about how each scenario sort of expands the range at which
supply may evolve in the future.
The first scenario is called Observed Resampled; what it does is resample through the Observed historical record as an indication
of what future hydrology might be like on the basin.
So the idea behind this is really history repeats itself. The figure here are natural flow record at Lees Ferry; it's dating back to 1906.
You again can see the variability from extreme low years; in 1977 for example our natural flow was barely above 5 million acre feet to some of
the years during the 80s where we were reaching 25 million acre feet.
This water supply scenario Observed Resampled is really saying that the next 50 years will be identical to the last 100 years.
Each supply scenario consists of multiple different sequences for future stream flow.
By doing this we're able to get distribution of how supply may play out under a certain scenario.
So to get a distribution assuming the history repeats itself, we resample through each one of this past record to get 103 sequences of
future stream flows. This record is 103 years long, so we can get 103 sequences of future stream flow.
Slide 16: Carly Jerla: To expand the range of how hydrology may play out, we've added to the
supply scenarios the Paleo Resampled Scenario.
So this relying on the tree ring record that are reconstructed for the last 1250 years to give us an indication of what future stream flow might
look like.
We are able to generate 1244 sequences of future stream flow in this scenario.
And the figure here is showing you the 25 year running average of this historical paleo record. So it's dating back to 762.
There's two different reconstructions, both done at the University of Arizona by Dave Meko and Connie Woodhouse.
And then the lime green portion is showing what the last 100 years has been relative to the last 1200 years of the Paleo Reconstruction.
That dotted lime green line is where our recent 25 year average is and you can see that that's a pretty low average even by measure of what
we've seen in the last 1200 years from the paleo record.
Slide 17: Carly Jerla: To expand that range to think about more extreme drought spells or different surplus
spells than we've even seen in our historical or the paleo record; we introduced a third water supply scenario.
It's called Paleo Conditioned and it's really blending both the historical supply on the basin with the Paleo supply on the basin.
The approach here will give us 500 sequences of future stream flow.
Slide 18: Carly Jerla: Finally, we want to look at what happens if temperature and precipitation are
much different than what we've seen in the measured past.
What is common through the previous three scenarios we just looked at is they're all assuming stationary climate.
And we want to expand the range even more by looking at what happens if we find ourselves in the future with changing precipitation and
temperature much different than what we've seen in the past.
So we introduce the Downscaled Global Climate Model Projected or down-scaled GCM projected scenario.
To get this scenario we utilized 112 projections from global climate models under three different emission scenarios.
These were bias corrected and down-scaled for precipitation and temperature.
We took that precipitation and temperature and moved that through a hydrologic model to get projections of stream flow and then we can use
those 112 sequences of future stream flow to understand the impacts on the system.
Slide 19: Carly Jerla: We're now going to look at a summary of the quantification of those different
scenarios.
So the figure here it's showing you the distribution for each one of those scenarios with the history repeats itself scenario on the far left
in the blue and the climate change scenario on the far right in the red.
And we're looking at the distribution of the future long-term averages from 2011 to 2060, natural flow at Lees Ferry.
If you focus on the Observed Scenario you can see that the median of that distribution which is indicated by the triangle, the orange triangle
there, is right at 15 million acre feet. So that is what our historical average has been on this basin.
So it would make sense that the statistics you see or the future long-term average wouldn't be much different than what we've seen in our past
historical long-term average.
If you follow that 15 million acre feet where the median is of the Observed all the way to the right for the climate projection statistics, you
see that that triangle is a bit lower.
It's sitting at about 13.6 million acre feet and that's about a 9% decline from that 15 million acre foot average.
So you definitely are seeing a decline in the long-term mean from the historical average, but you're also seeing the biggest spread is
indicated by the width of that box in terms of the variability around that number.
And at the 25th percentile; we are just above 12 million acre feet as a long-term future mean.
The dotted line here indicates what our recent 20 year average has been on the basin; it's been at about 13.6 million acre feet which is about
where we find the median ending up at for the climate change projection.
Slide 20: Carly Jerla: If we think about future drought and surplus statistics, what we found in these
different scenarios is if you define a deficit period as a period when the two year running mean is below the observed mean of 15 million
acre feet; we want to look at a two year running mean here because we all know on this basin in the variability that we see one year of good flow
doesn't necessarily break a drought spell.
But in defining a deficit that way and a surplus is just the opposite, we're seeing that the frequency of those events occurring, ones occur
that last five years or longer, happen more frequently under the climate change scenario. And that's 48% and it's circled there.
If we look at surplus frequency five years or longer, we see the most frequent occurrence of those being under our history repeats itself type
scenario and less than 1% if we're looking at the down-scaled GCM projected scenario.
Slide 21: Carly Jerla: I'm now going to shift into the results of the water demand assessment.
These results are highlighted and much more detail is provided in our Technical Report C.
I'll talk basically the same structure as through the water supply, talk about the objectives, the development of the scenarios and the
quantification of those scenarios.
Slide 22: Carly Jerla: So the objective of the water demand assessment was to assess both the
quantity and location of both current and future water demands within the Study Area. So again, the study area is defined as the hydrologic
boundaries within the United States, plus those adjacent areas that receive Colorado River water.
And approximately 25 percent of the water in the upper basin is exported to these adjacent areas and it’s double that in the lower basin, about
50 percent.
So understanding demand in these areas is critical to understanding the total demand placed upon the Colorado River.
Resources that we have included in both the assessment of demand and in the system reliability analysis which we'll look at a little later
include municipal and industrial use, agricultural use, hydropower generation, recreation and fish and wildlife habitat.
Slide 22: Carly Jerla: We developed six demand scenarios that indicate how demand may evolve
under changes and different driving forces on the basin.
And the way these demand scenarios were crafted was through a multi-stakeholder team that really thought about the different driving
forces that would influence the way demand might change in the basin.
And those types of driving forces include population, water efficiency changes, changes in irrigated agriculture, changes in water demand
for energy, changes in water to meet tribal needs and so on.
So this group thought about different pathways that these driving forces could take and then weaved these pathways together into storylines.
What's shown here is really the brief version of those storylines and we have six different scenarios that came from these storylines.
The first is called Current Projected; this is really your kind of middle of the road business as usual type demand scenario.
We're looking at medium growth, medium changes in population projections and development patterns in institutions that
continue along recent trends.
At a much slower pace we have the Slow Growth demand scenario; this has a much slower rate of growth in terms of population with
an emphasis on economic efficiency.
So there is not the economic environment for the adoption of a lot of new technology in this demand scenario.
In Rapid Growth we're really looking at the complete opposite; there's an economic resurgence of both population and energy
demand to meet that population growth.
And that is coupled with two different branches for how technology may evolve;
a slow technology adoption and a rapid technology adoption.
And this has current preferences towards human and environmental values. And that will make more sense once I talk about the last two
demand scenarios; this is in the Enhanced Environment scenario.
There's two branches here.
And so this is looking at preferences towards environmental values that are different and more expanded than what we see in rapid growth.
And we're expanding that environmental awareness and stewardship along with a growing economy and we're coupling that with
both a moderate population growth in D1 and a rapid population growth in D2.
And this really translates into the rate at which we adopt new water efficiency technologies and that expanded environmental awareness results
in a much greater adoption of some of those technologies.
Slide 23: Carly Jerla: So how do we take these storylines and come up with quantified demands?
We do so in the approach described here.
So we begin with that storyline and we have all of the different driving forces or parameters that comprise that storyline.
And each one of those parameters impacts a different category of demand.
So for example if we're looking at agricultural demand, that's impacted by irrigation efficiency and irrigated acreage.
We put numbers to each one of these parameters or driving forces.
The numbers were provided by both the Basin States, but also by various tribes
and environmental organizations involved in the study.
As we put numbers to these we can quantify what the study area demand is and then back into what our Colorado River demand is,
we need to make some assumptions about what some of those other supply may be providing.
So this is really how we deal with some of those adjacent areas that are outside of the basin that received Colorado River water,
but also rely on other sources to meet the demands within that area.
There are assumptions that are made about these other supplies who arrive at the Colorado River demand and after implementing these
assumptions we result in a quantified demand scenario.
Slide 24: Carly Jerla: The figure here shows the results of those quantified demand scenarios.
We're looking at both historical use on the basin which is in the left since 1970 and then added on for the future part of the figure;
so from 2012 to 2060 is those future demand scenarios.
The demand scenarios are bracketed by the Slow Growth and Rapid Growth scenarios; that's in the orange and the red.
There's about a 20 percent spread in the change and demand between those two scenarios. And it's roughly from about 18.1 million acre feet
under slow growth to 20.4 million acre feet by 2060 under rapid growth.
And this is when you factor in the treaty delivery to Mexico and losses on the system due to reservoir evapotranspiration losses to native