Mountains, it is often said, are the West’s water towers. If snowfall fails to fill the towers, or warm temperatures empty them too early in the year, fish, farmers and other water users face a dry summer. That’s especially true for the sprawling Columbia River Basin, the Texas-sized watershed that not only covers large sections of Oregon, Washington and Idaho, but also drains parts of four other states and British Columbia.
The Columbia River and its largest tributary, the Snake, are constrained by large dams for irrigation, flood control and power generation, but their reservoirs store relatively little water. While the Colorado River reservoir system can store about 300 percent of that river’s annual flow, Columbia reservoirs can hold only about 30 percent — with more than half that capacity in Canada. That makes the basin, with its approximately 7 million U.S. residents, roughly 7 million irrigated acres, and huge hydropower demands, especially dependent on what’s stored in its alpine water towers.
But this spring, the Northern Rockies and the Cascade Range are far from full. Because of low snowfall and early melting of the snowpack, the federal Natural Resources Conservation Service expects streamflow between April and July at the lower end of the Snake River to be just 51 percent of average. And at The Dalles, about 80 miles east of Portland, the projected spring and early summer streamflow in the main stem of the Columbia is 65 percent of average. Only the basin’s northernmost neighborhood, in Canada, can expect anything approaching average flows.
Utilities and fish feel the squeeze
So far, electric utilities in the Columbia Basin expect to be able to meet power demands, but low flows could lead to higher rates this summer or fall. Price hikes would squeeze not only individual consumers, but also industrial customers, such as the region’s energy-intensive aluminum smelters.
The dry summer will also add stress to a strained natural system. "Essentially, every year is a drought year for fish in the basin," says Andrew Purkey, director of the Columbia Basin Water Transactions Program. That’s because many rivers and streams in the basin are overappropriated, he says, meaning that more water rights have been granted than there is water to meet them. To remedy this situation, Purkey’s program uses funding from the Bonneville Power Administration and other groups to lease and purchase water rights for fish. But he expects to have a hard time finding irrigators willing to let go of water this year.
Low summer flows aren’t the only problem facing fish, particularly salmon and other anadromous species that migrate between freshwater spawning grounds and the sea. "Different stocks in different rivers have adapted to a particular timing of streamflow," says Patty Glick, climate specialist for the National Wildlife Federation. If warm temperatures cause peak flows to happen significantly earlier than usual, she explains, adults may arrive at the mouth of a stream too late for upstream travel, or juveniles may not be ready to ride downstream.
"In the Columbia and Snake rivers, there are already so many obstacles that have altered the rivers," she says. "If the runoff happens too early, that’s just an added whammy."
The future looks dry
State officials are hastening to prepare for summer water shortages. In Washington, a statewide drought emergency has freed up funding from the state Drought Emergency Account; it also allows the state Department of Ecology to quickly transfer water rights between water users, and to permit additional use of groundwater. Gov. Christine Gregoire, D, recently requested about $12 million in extra drought-response funds from the state Legislature, money that could be used to buy water and pay for water-supply projects.
Oregon Gov. Ted Kulongoski, D, declared drought emergencies for two counties in early March, and the Oregon Drought Council has recommended that he add six more counties to the list. Kulongoski is also seeking $450,000 from the federal government for a statewide assessment of future water needs.
If climate scientists are correct, long-term planning is not only prudent, but necessary. Alan Hamlet and his colleagues from the Climate Impacts Group at the University of Washington anticipate that by the 2040s, average summer flows in the Columbia at The Dalles will drop by 11 percent — assuming that winter precipitation remains largely unchanged. If winter precipitation declines, summer flows could plummet as much as 25 percent by the 2040s. "The real concern is that we’re going to have to choose between hydropower and fish," says Hamlet.
Such difficult choices could cause Northwesterners to cast a covetous eye at the Canadian lobe of the Columbia Basin, which is colder in winter and likely to retain more of its mountain snowpack in the future. Unless the two countries plan ahead, says Hamlet, the potential for a cross-border "train wreck" is high.
A legacy of faulty assumptions
How did the basin get into this fix? Even before human-fueled global warming reached its present pace, persistent drought was no stranger to the Columbia. Forest Service research biologist David Peterson and his colleagues recently read the rings of venerable Douglas firs, ponderosa pines and other trees throughout the basin, and found that six major multi-year droughts have hit the Columbia and its tributaries during the past 250 years. One especially severe drought began in the 1840s and lasted 12 years, while another deep dry spell occurred in the 1930s.
But as in the rest of the West, relatively wet conditions during much of the 20th century lulled Northwesterners into complacency, and led them to develop beyond the Columbia’s capacity to provide water in dry times. "Natural systems are adapted to drought," says Peterson. "It’s human systems that are not well-adapted."