The challenges of dynamic water management in the American West.

• Author: Doremus, Holly

1. INTRODUCTION II. WESTERN WATER PROJECTS ARE HIGHLY VULNERABLE TO GLOBAL WARMING III. ADAPTATION WILL BE DIFFICULT, AT BEST A. Infrastructure constraints B. Institutional constraints IV. THE APPEAL OF STABILITY V. BARRIERS TO REDISTRIBUTING WATER VI. INSTITUTIONAL BARRIERS TO CHANGING PROJECT OPERATIONS VII. COURTING TRAIN WRECKS VIII. CAN CREATURES WHO CRAVE STABILITY DEAL WITH CHANGE? IX. CONCLUSION I. INTRODUCTION

   The premise of this climate change symposium is one whose importance the legal community in the United States has been slow to understand. There is wide agreement among climate scientists that global climate change calls for two distinct types of response. The first is a reduction in the amount and rate of greenhouse gas emissions, so as to slow increases in global temperatures and limit the impacts of associated climatic shifts. This response has attracted much attention from lawyers and economists. They have sought to force policy shifts through litigation, opined about the pros and cons of various policy designs, and purported to forecast the economic and social impacts of various strategies.

   The second response, which has received much less attention, is adaptation. Among some climate scientists, talk of adaptation has been almost taboo for fear that it might be seen as a substitute for aggressive emission reduction measures. (1) Although lawyers may not see discussion of adaptation as taboo, until very recently they have not been much interested in it. Perhaps adaptation seems less glamorous than devising new schemes to regulate carbon dioxide emissions, perhaps it seems too difficult, or perhaps it is seen as potentially undermining the impulses toward environmental protection that provide the conceptual and political foundation for environmental law. (2)

   Difficult and unappealing as it may be, however, there can be no doubt that we need to confront adaptation. No matter how quickly and how aggressively we act to rein in future emissions, the profligate consumption of fossil fuels since the industrial revolution has already irrevocably committed the globe to substantial climatic changes. (3) Dealing with those changes will pose substantial challenges, requiring that we embrace flexibility and dynamism in a way that does not come naturally to law, to our institutions, or - for that matter - to human nature. Drawing upon the history of water distribution in the arid American west, this article offers a cautionary lesson about the difficulties of meeting the challenge of climate change. While there are some hopeful signs, no one should underestimate the barriers, or the need for lawyers and legal academics to devote continued attention and energy to the task of adapting to those aspects of climate change that cannot be mitigated.

2. WESTERN WATER PROJECTS ARE HIGHLY VULNERABLE TO GLOBAL WARMING

   In California, 36 million people depend upon a Mediterranean climate characterized by three important features. First, precipitation is highly seasonal. Rain and snow are almost entirely confined to the winter months, which is great for barbecuing but not ideal for growing crops or even lawns. While 80% of the precipitation in California occurs between October and March, about 75% of the water use occurs between April and September. Second, annual precipitation is highly variable. Both floods and droughts are common. Odd as it sounds, "average" water years are rare. (4) Third, the precipitation is geographically separated from the demand for water. Average precipitation varies by an order of magnitude, from less than 12 inches to more than 120 inches per year across the state. Both population centers and key agricultural districts are concentrated in relatively dry areas. About two-thirds of all precipitation in California falls to the north of Sacramento, while about two thirds of all the water use occurs to the south. Moreover, much of the precipitation occurs in the interior mountains, while most of the population lives along the coast. (5) Because of its climate, California must rely on an elaborate plumbing system to store water in the winter and spring for use later in the year, reserve water for future years, and convey water to points of use.

   The climatic details vary across the arid West, but the general picture is the same. Current patterns of human settlement throughout the region have been made possible only by more than a hundred years of intensive investment in storage and conveyance. Every major river basin in the west is dotted with large water projects that irrigate crops, produce electricity without carbon emissions, protect against flooding, and provide drinking water for cities. The rivers those projects have channelized, tamed, and put to human work still manage to support native fish, wildlife, and vegetation - but just barely. (6)

   The West is acutely aware of the impacts that global warming will have on the hydrologic cycle and, through it, on the water systems that sustain us. Those systems face a number of linked challenges. To begin with, the snowpack in western mountains provides a vital reservoir. To use California as a specific example of a more general problem, even assuming that temperature increases fall at the low end of the climate model predictions, we stand to lose half or more of the snowpack storage capacity by the end of the 21st century. (7) Warmer temperatures will mean that more of our precipitation falls as rain and runs off immediately. That has multiple consequences. First, unless additional manmade storage is developed, we will lose part of our winter precipitation that, historically, has been stored naturally for summer, ending up with a smaller effective water supply. This point has been overlooked in much of the economic analysis of the impacts of climate change on water supply, which tends to focus on the total amount of precipitation and to ignore timing. The fact is that, in a warmer climate, we could have twice as much precipitation in January and February and not one drop more of water available in July and August when it is needed. Second, the increased winter runoff and earlier snowmelt that warmer winters bring will worsen floods, which already regularly threaten to overtop or undermine our levees and drown our homes and businesses. Third, as peak flows shift earlier in the year, flows during the main irrigation season (April-September) will decline. Under a business-as-usual emissions scenario, spring and summer streamflow will decline by about 20% before mid-century and about 50% before the end of the century. Fourth, earlier snowmelt will also make it more difficult for dam operators to retain the water needed to generate hydroelectric power in the summer, when the demand for electricity is highest. To complicate matters, awareness of global warming has already increased the value of hydropower. California now requires that every electric utility meet targets for renewable energy production, (8) and hydropower is, for now at least, easily the most economical renewable energy source.

   California's water supply will also be impacted by sea level rise. Rising sea levels will cause increased saltwater intrusion into coastal aquifers such as those in Orange County and Monterey County. Another effect, peculiar to California and even more damaging, is the threat posed to the Sacramento-San Joaquin Delta--the hub of California's plumbing system, which supplies water to some twenty million people and three million acres of farmland. (9) The system relies on a network of Delta islands protected by levees, in combination with a controlled pattern of freshwater releases, to keep saltwater away from the water supply pumps in the South Delta. The levees are frail and becoming increasingly vulnerable. If there were an earthquake on one of the faults near the Delta, it might damage the levee system enough to allow an irreversible incursion of seawater into parts of the Delta that are currently fresh. Even without an earthquake, rising sea levels will increase the likelihood of levee destruction. The danger is greatest in the winter and early spring. In a winter storm, the crest of the waves is several feet higher than mean sea level, so that a levee can be overtopped even if it stands above mean sea level. The likelihood of a destructive wave increases exponentially with a rise in sea level. Warming temperatures will add to the stresses on the levees by making flood flows in the Sacramento and San Joaquin watersheds more likely in winter and spring, both by increasing the intensity of winter rainstorms and by accelerating melting of the snowpack.

3. ADAPTATION WILL BE DIFFICULT, AT BEST

   The scientific evidence of climate change is sufficiently certain at this point to leave no doubt that we must make changes to western water systems if we hope to preserve their utility. As a species, Homo sapiens is nothing if not adaptable, and the United States has the additional advantage of wealth. We are confident that America will respond to the most important of human needs for water. No one will go thirsty. Based on the Western water management experience of the last one hundred years, however, we are pessimistic that the needed changes will be made in an economically rational, proactive manner; that they will introduce sufficient flexibility to allow our water systems to continue to adapt smoothly as the climate changes; or that they will take much account of the non-human world. Although there are some reasons for cautious optimism, no one should underestimate the challenges of introducing a dynamic approach to water allocation. It will require fundamental changes in the way we think about both nature and law.

   1. Infrastructure constraints

      Water facilities have both physical and operational constraints. Some things can be changed relatively easily, but others cannot. If, for example, western states want to replace the storage capacity lost with the...