Sunday, July 26, 2020

WATER WARS, Ch. 11, Evaluation of Options

Water Wars Sharing the Colorado River
an extensIve analysIs and evaluation of options for assuring adequate water supplies in the Colorado River Basin was published in 2012 by the Bureau of Reclamation, and we summarize it here. [Colorado River Basin Water Supply and Demand Study, Executive Summary, Bureau of Reclamation, U.S. Department of the Interior, Washington, DC, December 2012]
The report makes the following warning: “The Colorado River is the lifeblood of the southwestern United States….Nearly 40 million Americans rely on the Colorado River….there exists a strong potential for significant imbalances between the supply and demand for water in the coming decades.”
From 1906-2011, the Colorado River had average natural flow of 16.4 maf/year. The Study was done to predict imbalances for the next 50 years, 2010-2060. The Study area was the hydrologic basin area plus adjoining states that receive water from the Colorado.
Four water-supply scenarios and six water-demand scenarios were studied to try to predict the future needs.


        Observed Resampled (past 100 years).
        Paleo Resampled (past 1250 years)
        Paleo Conditioned (mix of Observed and Paleo)
        Downscaled GCM (warming climate from 112 Global Climate Models), which predicts a nine percent decrease in flow at Lees Ferry and higher-than-historical frequency and variation in droughts, which are predicted to have lengths of five years or more 50% of the time in the upcoming 50 years.


To get a good depiction of future consumptive use demand, a set of six scenarios was developed:
        A. Current Projected
        B. Slow Growth (18.1 maf, 49.3 million people)
        C1. Rapid Growth 1 (20.4 maf, 76.5 million people)
        C2. Rapid Growth 2
        D1. Enhanced Environment 1 •          D2. Enhanced Environment 2
Comparing the medians from the supply and demand scenarios, the likely imbalance by 2060 is 3.2 maf, with a wide range of uncertainty. Some of this can be met with reservoir storage to smooth out variability. By 2010, the ten-year running average of demand had already exceeded the ten-year running average of supply, and the trends were for this difference to increase.


        Increase Supply
        Reduce Demand
        Modify Operations
        Modify Governance
The criteria used to evaluate the options were
        Technical (feasibility, risks, viability, flexibility)
        Social (recreation, policy, legal, socioeconomics)
        Environmental (permitting, energy needs, energy sources, other environmental factors)
        Other (yield quantity, timing, cost, hydropower, water quality)
Where possible they were evaluated based on cost, $/maf, year available, and potential yields (2035, 2060).
Adding all options gave additional yearly flow of 5.7 maf by 2035 and 11 maf by 2060. Ruling out some options considered infeasible gave additional flow estimates of 3.7 and 7 maf for 2035 and 2060.
Four portfolios of options were then chosen: B, C, inclusive A=B+C, and selective D = options shared by both B and C.


Criteria came from analyzing:
        Water delivery
        Water quality
        Recreational use
        Flood control
        Ecological resources
Reliability was measured against keeping Lake Mead at 1000 ft above mean sea level and keeping the 10-year flow at Lees Ferry at 75 maf. Conclusion: without action, it will be difficult to meet these goals using the Baseline arrangements for the next 50 years.
Over 20,000 simulations were run for each portfolio.
Study Table 4 shows the % of years in which the criteria were not met when analyzed using the Baseline model and Models A,B,C,D. For all criteria except flood control, the Baseline model performed worst of the options. Of the resource criteria, Baseline failed most often at keeping Lake Mead at 1000 feet above msl. By that criterion, all portfolios and the Baseline option failed 30% or more of the instances, and they failed almost as often at keeping the Colorado River flow above the targeted value. As expected logically, the inclusive Portfolio A did the best and the exclusive Portfolio D the worst at meeting the criteria.
Study Figure 4 Shows the various options and their cost estimates and the percentage of the 2010-2060 years in which the system is vulnerable. There are wide ranges of vulnerabilities, and the costs vary as well, but are limited to about $2 billion to $7 billion per year.
The report does not choose the best option, leaving that to others.


The authors note that the study is limited by available data, assessment methods, current models:
The Colorado River Simulation System (CRSS) was used to model behavior and assess impacts.
The CRSS uses historical inflows based on USGS data for four tributaries downstream of Lees Ferry, making the Lower Basin predictions subject to substantial uncertainty.
The model assumed reduced agricultural use, as such flows will be diverted to urban use instead. This may not be correct.
A limited set of options was considered, and future developments and technological change may make other options important.


Improved modeling of future supply and demand will continue. Demand can be assumed to increase, making shortages more likely, and no one option is likely to be optimal. Investment in conservation, reuse, and augmentation will be needed to improve reliability and sustainability.


Nothing in the Study is to be used as part of any litigation in a variety of possible actions outlined in this Disclaimer. 

Note that although governmental command-and-control activities might seem adequate to handle the need for clean drinking water in the future, there are practical political and economic factors that get in the way, as pointed out in a recent article in The City Journal:
In 2014, amid a drought, 2/3 of California voters voted for Proposition 1, to have a bond for $2.7 billion worth of water storage projects, as part of a larger $7 billion Water Quality, Supply, and Infrastructure Improvement Act. Four years later, no funding for water storage had been passed by the state water commission. This contrasts with the relatively rapid creation of the San Luis Reservoir, with a capacity of 2 million acre-feet, done five years from 1963-68, facing far fewer challenges in the courts.
Mid-2018, the California Water commission announced plans to fund projects with Proposition 1 money, only a third of the projects actually related directly to water storage. The proposed storage sites will add a capacity of 2 million acre-feet, compared with the annual residential water use by Californians of 4 million acre-feet per year. The Sites Reservoir, the largest of the projects, is expected to be completed by 2029, at a cost of about ten times the cost of the comparable San Luis Reservoir finished in the mid-1960s in one-fourth the time. Litigation is a major factor in the added costs and time for completion. [https://]


Sharing the use of water resources raises many possible equity issues, some of which we discuss next. Essentially, these come down to who uses how much of the resources and how. To make progress in analysis of policy options, the problem needs to be stated clearly, and its boundaries marked (Hardin, 1968). We start with the simpler cases and build from there.
A single body of water, such as a lake or inland sea, has inlets and outlets, with users around its shores and on its surface. Like a common grazing area of earlier times, it is susceptible to the “tragedy of the commons,” where each user benefits more directly from using than from contributing to its well-being, its maintenance. Biologist Garrett Hardin (1968) popularized the term and showed that for finite resources we cannot obtain “the greatest good for the greatest number.” Each user is tempted to use as much as wanted and to contribute nothing. A solution is to obtain enforceable agreements among all involved or to have rules enforced by a governing body. Then, one must be able to verify what is being done. A lake may be in one governmental jurisdiction, allowing simplified enforcement of one set of laws. A larger body of water may have multiple governing authorities, requiring agreements among them on rules of use and manner of enforcement. If the body of water can overflow its banks, then issues of compensation for damages are added.
The lake will likely have inlets and outlets, and the control of these flows adds another dimension to the complexity. What is done upstream is of particular concern, and likely needs agreements, laws, and policing.
Similarly, a river has upstream and downstream regions, with upstream behavior affecting the flow and its quality in the downstream areas. Again, agreements or laws and enforcement will seem desirable.
In the case of the “lake” or the “river,” the agreements or laws may have sharp-edge restrictions, yes/no, or an attempt may be made to put prices on various types and amounts of “use.” Enforcement again becomes critical.
Monitoring the level of a lake or inland sea is relatively straightforward in comparison with determining the carrying capacity and the amount of water carried in an aquifer, which is a region of porous solids, liquid, and air. Again, there are inputs and outputs and issues of capacity, volume, flow, and quality.
If these considerations were not complex enough, we have the added issue of the degree to which current use and users will impact future use and users and how to manage the somewhat different concerns of the two populations, complicated further by the likelihood of technological and demographic changes.

I will continue serializing here the Microsoft Word transcription of the final galley proof .pdf copy ot WATER WARS, and the book itself  is most conveniently found at

or at DWC's author's book title list

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