BOULDER - Of all the current and future impacts of climate change, threats to water resources may be the most painful in the American West, according to a new report published Monday.
"Protecting the lifeline of the West," written by Western Resource Advocates, a Boulder-based environmental law and policy organization, brings together dozens of studies by climate and water experts, detailing the ways in which water, energy and climate are deeply entwined in states like Colorado, Wyoming, Utah and Arizona.
"Of all the implications of a hotter climate, the water implications are the most dramatic or long-term," said Bart Miller, the organization's water-program director. "There's no way to adjust by making more water."
The report's release coincides with the U.S. Senate's return to Washington to take up energy and climate legislation this week.
"One aspect of the global-warming challenge that is not often talked about inside the Beltway is the threat posed by global warming to the West's most critical natural resource - water," said Dan Grossman, regional director for Environmental Defense Fund. "In addition to helping increase droughts that are associated with climate change, developing clean-energy technologies will also let us move away from water-intensive energy sources so we can devote more of our water to meet the growing needs of Western cities, agriculture, recreation and the environment."
Scientists have already documented trends in declining snowpack and earlier spring runoff across the West. Even if precipitation levels hold steady in places like Colorado's north-central mountains, snow will continue to melt sooner and faster, winter will be shorter, and less water will be stored in the peaks, according to Miller. And those changes in the water cycle can have negative implications for reservoir storage, aquatic habitat, ski seasons, rafting seasons and water quality.
"Regardless of whether there's less snow, we're going to have issues of lower flows and dryer conditions in July and August," Miller said.
Global average temperatures rose 1 degree Fahrenheit during the 20th century, and data show the West to have been consistent with that trend. But while the U.S. as a whole became wetter, researchers have found evidence of increased drought severity and duration in the West.
Authors of the report say climate change projections for the 21st century are nowhere more troubling than in the Colorado River Basin. The river supplies water for municipal use, industry and agriculture for more than 30 million people and 1.4 million acres of farmland. Seven Western states and two states in Mexico have legal rights to the water, but those rights on paper exceed the actual amount of water in the river. Furthermore, the population in the seven interior Western states is projected to grow by more than 9 million by 2030. Add the impacts of climate change to the mix, and you have an expanding number of guests at the table, all to share a shrinking pie.
Today, an 11-year drought has reduced water in two of the Colorado River's largest reservoirs - Lake Mead and Lake Powell - to 55 percent of capacity. And this year's runoff is projected to be only 63 percent of average, according to the National Weather Service.
The report's authors say today's drought conditions could well become the new norm in the Southwest, and that future drought conditions could be more severe than any in recent centuries. The report references a 2007 study published in the journal Science in which 46 of 49 global climate models predicted a more arid future for the southwestern U.S. Twenty-three of 24 models project decreased runoff for the Colorado River by mid-century.
The production of climate-changing gases isn't the only way fossil fuel consumption puts pressure on water supplies. Their extraction and burning can be water-intensive processes, according to the report. In 2005, power plants (nuclear, coal, natural gas and biomass) in the interior Western states used more than 680 million gallons of water per day, 56 percent of which was consumed, through evaporative loss. The total volume of water used by the power plants was equal to the combined water use of Denver, Albuquerque, Phoenix and Tucson. An average Colorado household uses about 130,000 gallons per year.
There are options for power plants to be more efficient with water, though. Xcel Energy's Comanche 3 plant in Pueblo will use a cooling system that is expected to use half the water a conventional cooling system does.
According to the report, wind and photovoltaic solar systems use very little in comparison to traditional power plants. Replacing a 5-megawatt pulverized-coal plant with wind turbines would save 1.9 billion gallons a year of water withdrawals and 1.6 billion gallons of water consumption.
The U.S. Department of Energy recently projected that water consumption from gas production in the 10-state Rocky Mountain Oil and Gas Supply Region will reach 450 million gallons per day by 2030. Oil production will use a projected 250 million gallons per day by 2030.
"Development of oil shale resources would carry even more dramatic implications for dwindling Western water supplies," the report authors wrote. "Oil shale extraction is a highly water-intensive process - directly consuming up to four barrels of water per barrel of oil produced."
Shell Oil has proposed to divert about 8 percent of the Yampa River's spring flows for oil shale development in northwestern Colorado.