A crystal ball for the Pacific Northwest’s climate

This year’s drought is as bad as scientists predict for mid-century.

 

If you’re looking for unexpected ways the current drought is affecting the West, you might take a look in Kathie Dello’s inbox. Until recently, Dello, the deputy director of Oregon’s climate service, had been getting the same emails from prospective residents: I’m thinking about moving to the Pacific Northwest, but I’m worried it’s too wet. How much does it rain there, really?

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NOAA, Natural Resources Conservation Service and California Snow Survey as of April 1

But this winter, as declarations of water shortages swept across the state, the questions changed. “I started to get emails from people wondering whether they should still move to the Pacific Northwest, because of the drought,” Dello told me recently. They worry there won’t be enough water once they get there.

Dello doesn’t have an easy answer, but she knows this is just the beginning. In the Pacific Northwest, the water shortage isn’t due to a lack of precipitation; most of Oregon and Washington saw near-normal amounts. But that moisture arrived mostly as rain, not snow. The rain ran off without adding to the snow reserves, and unseasonably warm temperatures have burned off a good part of the rest. That means there’s little or no snowmelt to take the sting out of the region’s dry summer. And that is close to what climate change models predict for the region.

“We absolutely are looking at our future, right now,” Dello said.

Climate projections suggest that the West can expect years like this one to become more frequent by the middle of the century, although changes are already in motion. In the Northwest and the Northern Rockies, that means more rain and less snow. A rainier winter means lower springtime flows for fish and farmers and a less predictable summer water supply for reservoirs. In the Southwest, climate change likely means extended periods of drought, with low precipitation and a low snowpack, much like the one in California.

One of the hardest-hit places in the Northwest has been Oregon’s Malheur County, an agricultural region of alfalfa farms and rocky rangelands tucked against the border with Idaho. Malheur received a near-normal amount of precipitation, 93 percent, but the snowpack was just 1 percent of normal on April 14. The Owyhee Reservoir, which provides much of the county’s water, is at just 28 percent of capacity, thanks to the skimpy snowpack and a series of dry years before this one. Anticipating less than half their usual water allotment from storage, farmers have fallowed fields and switched to crops such as triticale, a hybrid of wheat and rye, that don’t demand as much water.

“There’s a prevailing thought that this is a dry spell,” says Bill Buhrig, a crops agent for Oregon State University and a local farmer himself. But a disturbing question has started to percolate: “How long do you keep calling it a dry spell before you start making long-term adjustments to your operations?”

For municipal water-supply managers in the Northwest, this year’s conditions are a crystal ball for a warmer, rainier future. Typically, water managers go through seasonal cycles of holding water back and then releasing it in order to juggle the shifting needs of human users and salmon. This year, the usual seasonal patterns have shifted, since winter barely arrived and summer looks to be coming early. That means managers have to adjust the times they release the water and how much of it they let go.

Seattle Public Utilities, which manages the city’s water supply, has gone further than many in preparing for climate change, running a series of virtual scenarios. Paul Fleming, the director of the utility’s climate resilience group, says that this year is a useful real-world test for the utility’s infrastructure and strategy.-

“It’s helpful to be able to see how resilient your system is,” he says. The utility is adjusting how it fills and draws down its reservoirs, which could prove useful as conditions like this year’s become more common. In order to respond to low snowpack and paltry spring flows, Seattle Public Utilities kept reservoirs higher through the winter and spring. Most years, the reservoirs are kept lower to prevent flooding if a big storm hits. Other water managers are holding more water back longer into spring as well and figuring out which reservoirs to keep high, based on which areas are likely to get less snowmelt and which streams need water for fish.

This drought obviously isn’t the first Westerners have experienced. Severe droughts in the 1970s, 1980s and early 2000s helped spur ongoing water conservation efforts, and much of the West has been flirting with drought for a decade and a half. But Oregon climate expert Dello says that though dry spells typically fade from people’s memories, this year is different. “Folks are saying, ‘OK, something’s changed. If this is going to keep happening, we can’t keep doing what we’re doing,’ ” she told me. “It won’t be so easy to forget.”

Photo: Peter Stevens/CC Flickr