The consequences of climate change are being felt, most acutely, in waters and watersheds throughout the United States. Water supply, water quality, natural flow regimes, and the human beings and ecosystems depending on them are all being deeply affected, imposing mounting new pressures on watershed management and on water and wastewater utilities.
According to a recent study by the American Water Works Association Research Foundation and University Corporation for Atmospheric Research, the best science suggests that the global climate cycle will become more intense, resulting in heavier but less frequent periods of precipitation. The science points to the possibility of longer periods of drought alternating with spells of heavy rainfall and runoff, usually very polluted. Greater variability in runoff and variation in flow regimes would make the maintenance of optimal reservoir levels more difficult, reducing the reliability of water storage.
Increased reliance on groundwater during extended dry spells would reduce aquifer levels and discharges to surface water bodies with unintended consequences for aquatic systems. Shorter periods of snow accumulation in mountainous regions, especially at lower altitudes, would result in reduced snow pack, which, along with earlier melting in the spring, would lead to reduced flows in late summer when water is scarce and demand rises. Floods, droughts, hurricanes, and wildfires -- as well as the soil erosion they cause -- would increase, threatening water quality, aquatic habitats, and utility infrastructure. And rising sea levels would lead to saltwater intrusion and flooding of infrastructure in coastal zones.
Treatment costs could increase for drinking water and wastewater utilities due to heavier runoff carrying sediment, nutrients, and other pollutants. This is commonly referred to as nonpoint source pollution, a major present obstacle to water quality because most of its diffuse sources are not regulated by the federal Clean Water Act.
In 2003 the U.S. General Accountability Office surveyed water managers and determined that even under normal or nondrought conditions, 36 states anticipated water shortages in localities, regions, or the entire state in the next 10 years. Under drought conditions 46 states expected shortages over the same period. With increasing population and declining groundwater levels, the freshwater supply appeared to be reaching its limits in some locations. Moreover, construction of new, large reservoirs has tapered off, and existing storage is threatened by age and sedimentation.
Problems have surfaced even in the humid Southeast, as current shortages in Georgia and Alabama have made painfully clear. In the arid West, specifically in the Colorado River basin, a kind of perfect storm is brewing. The Colorado watershed covers 240,000 square miles and seven states, including California and parts of Mexico. Recently a blue-ribbon scientific committee of the National Research Council of the National Academies reviewed data from tree-rings studies, which provide a much longer-term view of weather and climate than do stream gauges, which extend back only 100 years. The tree-ring data go back 300, 500, even 800 years or more. The committee found that average annual flows vary more than previously assumed and that extended droughts are not uncommon and are even, as The New York Times put it in a February 2007 headline for a story on the Southwest's arid conditions, "normal."
Moreover, future droughts may be longer and more severe because of a regional warming trend. The evidence suggests that rising temperatures will reduce the Colorado River's flow and water supplies. 2002 and 2004 were among the 10 driest years on record in the upper basin (Colorado, New Mexico, Utah, and Wyoming). Water storage in the basin's reservoirs dropped sharply during this period. Water flows into Lake Powell were 25 percent of the average. Add to this the rapid increases in population in states such as Arizona (a 40 percent rise since 1990), Colorado (30 percent growth in the same period), and Nevada (Viva Las Vegas!), and you can see why water is becoming as precious as oil.
The reality of this situation will require tremendous resilience in adapting and, where the opportunities present themselves, even mitigating the untoward impacts of climate change on the hydrologic cycle and aquatic systems. The case for immediate and sustained action, in terms of adaptation, is very compelling. Adaptation offers immediate, tangible, cost-effective, and, therefore, politically viable methods for coping with climate change in the context of water. Adaptation will not be easy. It will surely require systemic economic and social transformation amounting to a culture change in Americans' attitudes to the value of water in all its aspects -- chemical, physical, and biological.
On a technical level, no single climate model will yield reliable projections of future climatic conditions. Climate change models will have to be "downscaled" to the relevant watershed level but informed by robust data collection and monitoring. Nonetheless, a recent report sponsored by the American Water Works Association (AWWA) argues strongly that prudence dictates "planning for uncertainty," which entails implementing "precautionary, adaptive strategies designed to foster utility systems and operations that are robust, resilient, and flexible in anticipating alternative climate scenarios."
This primer also recognizes that the real solution goes beyond the confines of the individual utility itself. It contends that a broader approach known as Integrated Water Resources Management is the most effective means by which to engage all stakeholders and customers in assessing the management options available across the entire watershed. Generous conservation programs funded through the U.S. Department of Agriculture have had tremendous success in reducing soil erosion. However, the Soil and Water Conservation Society, looking at historic and predicted precipitation rates, foresees increases in soil erosion ranging from 4 percent to 95 percent and increases in runoff from 6 percent to 100 percent on cropland. Absent additional protective measures, these increases "could reverse much of the progress that has been made in reducing soil degradation and water pollution from cropland in the United States."
While all major water and wastewater utilities are newly focused on the challenges directly posed by climate change, other climate-related concerns have also emerged. Wastewater utilities remain attuned to legislative developments because they generate substantial emissions of carbon dioxide, methane, and nitrous oxide -- all greenhouse gases. They may have to limit these emissions, or they may be able to sell credits based on converting, say, methane, into energy. And all utilities are feeling the pinch of rising energy costs. The water sector consumes 3 percent of total electricity generated by the U.S. electric power industry. Energy accounts for roughly one-third of utilities' operating costs, and energy costs are expected to increase more than 20 percent in the next 15 years, which will drive the quest for greater energy efficiency and conservation.
We need to get the price right, both for the water itself and the infrastructure that protects it. The U.S. subsidizes water use: Most utilities barely capture the full cost of treating and delivering water. We may have the lowest water and waste-water rates of all the free-market democracies. We need to move to full-cost pricing and, if possible, conservation-based pricing in order to overcome the paradox of water and diamonds as noted by Adam Smith, who observed that diamonds are priceless, but water is cheap. Only in this way will water users be encouraged to conserve and husband this most valuable resource.
Corporations must recognize the business case for sustainable water use. Many, such as Intel, Coca-Cola, and other water-dependent companies, are already doing so. Stewardship of water resources, both in the plant and the surrounding community, would appear to meet sustainability's "triple bottom line" in terms of economics, the environment, and equity.
We need to develop efficient water markets, subject to reasonable environmental regulation, to facilitate the movement of water from low-value agriculture to other high-value uses while protecting flows for fish and wildlife. In most Western states the vast majority of the water is controlled by agriculture due to the long-standing legal doctrine of prior appropriations ("first in time, first in right"). In Nevada agriculture consumes 90 percent of the water; the Strip in Las Vegas, with 15 of the world's 20 largest hotels, complete with fountains and sea battles, accounts for less than 1 percent of the state's water use while producing 60 percent of its economic output. Cities, water trusts, and environmental groups are willing to buy these water rights, even at outrageous prices, to protect their values and meet their water needs.
Mitigating the effects of climate change is preferable. Adapting to it will be essential over the long haul, especially in the case of managing America's precious water resources.