Low rainfall could mean big problems

Sandi Doughton; The News Tribune


Western Washington is basking in a rare spell of golden fall weather, but too much of a good thing could turn nasty, say the experts who track the region's water.

The unusually dry weather already is taking a toll on salmon. If it persists much longer, it could cause problems for water supplies and power generation, U.S. Geological Survey hydrologist Bob Kimbrough said.

"If it would continue to be dry, we could have the potential to have an even lower runoff than two years ago," he said.

Two years ago, the region was hit by one of the worst droughts in the past century, driving the power system into crisis and leading to huge electricity rate increases.

Power and water managers say it's far too early to panic. A normal, wet November and December and a healthy winter snowpack could easily erase the early fall water deficit.

But with a moderate El Niño blossoming, this winter has the potential to be warmer and slightly drier than usual, said Brad Colman, science officer at the National Weather Service Seattle headquarters.

"We don't know fully what's going on," he said, "but it's certainly consistent with El Niño."

The winter weather pattern should become apparent by late November or early December, Colman said.

"It's too early to say much - except go out and enjoy the good weather while it's here."

The Weather Service's climate models are predicting at least another nine days of clear, dry weather. After that, the model suggests rain may reappear - but last week, the same model was predicting a soggy Halloween week, Colman cautioned.

Whatever happens over the next months, the past month was one for the record books.

With a scant 0.66 inches of rainfall, it was the second-driest October on record at Sea-Tac Airport.

The four-month period from July 1 to Oct. 31 was the driest ever at several spots across the state, including Sea-Tac, Bellingham and the Washington coast. In a normal year, slightly more than 7 inches of rain falls at Sea-Tac between July and October. This year's total was 1.76 inches.

The lack of rain is shrinking rivers and streams to record low levels for this time of year, stranding migrating salmon and forcing closure of popular fishing areas, Kimbrough said.

From an office in downtown Tacoma, he and his co-workers monitor stream and river flows at 250 sites across the state. At most of those sites, automated stream gauges record measurements several times a day and beam the information to the computerized USGS network.

The data are displayed as colored dots on a series of maps: Green and blue for streams where flows are above normal; reddish hues for those where flows are lower than normal - including those hitting new daily lows.

In mid-September, the red dots began proliferating, and the situation is only getting worse, Kimbrough said.

October is usually one of the region's reliably rainy months, added USGS hydrologist John Vaccaro.

"Dry Octobers are very rare," he said. "There have probably only been three or four in the last hundred years."

Last winter's snow and rain never completely replenished the groundwater lost in the 2000-2001 drought, which seems to be aggravating the current low stream flows, Vaccaro said.

"It can take several years to recover," he added.

On Thursday, the stream flow in the Puyallup River, near Orting, was 132 cubic feet per second, less than one-fourth the normal level of 584 cfs.

The Nisqually River was flowing at 109 cfs, compared with the normal level of 586 cfs.

The biggest impact of the low flows has been on the north coast of the Olympic Peninsula, where some flows are one-tenth normal, and migrating chinook salmon are fighting to make their way up rivers with barely a trickle of water, said Craig Bartlett of the Washington Department of Fish and Wildlife.

Sandi Doughton: 253-597-8516




This year: 0.66 inches

Normal: 3.23 inches

Record low: 0.31 inches, 1987


This year: 1.76 inches, a record low

Normal: 7.01 inches

Previous record: 1.90 inches, 1987

Data from Sea-Tac Airport, U.S. Weather Service


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