Tuesday, November 3, 2015

Extreme drought now in less than half of state

by Dan Partridge, communications manager, Water Resources Program

The rain came down in sheets over the weekend, pouring more than three inches of rain on Western Washington as measured at Sea-Tac Airport. Storms were intense and rivers swollen, leading many folks to ask: Is the statewide drought over?

The answer is no but the rain and snow did improve the drought picture considerably. Less than half the state is now in “extreme” drought and several areas of the state that were in “severe” drought have been upgraded to “moderate” drought, according to the U.S. Drought Monitor .

The weekend storms dumped 19 inches of snow in the North Cascades, as measured by the Natural Resources Conservation Service. Hart’s Pass received 15 inches of snow and Mount Rainer at Paradise received more than a foot of snow.

In a normal year, snowpack accumulates in our mountains over the winter and then runoff from melting snow feeds our rivers and streams through the spring, summer and fall. While the drought monitor report is encouraging, forecasters are concerned that much of the snow received last weekend will melt away before winter if the warm temperatures of October persist. The month was the second-warmest October on record for Washington.

The Yakima basin benefitted from the storms but the basin is still in that half of the state in extreme drought.

The basin is the most productive agricultural region in the state. The rain increased water storage in the five reservoirs managed by the U.S. Bureau of Reclamation for irrigation from 39 to 61 percent of average and the weekend storms brought the area up to 207 percent of its normal precipitation for the month of October.

“It was a very good rain over here,” said Chris Lynch, hydrologist and civil engineer with the Bureau.

For most of this year, however, water shortages have caused hardships in the Yakima basin and across the state. Record-low snowpack was found in the Yakima basin on April 1 and May 1, at 12 percent and 11 percent of average. Statewide, most of our snowpack was gone by the first of June. 

More water in irrigation reservoirs is good news for farmers who were cut back on their water allocations this year to 47 percent of normal, but there is still a significant deficit in water supplies for the Yakima Basin. The reservoirs are holding about 180,000 acre-feet of water (one acre-foot equals 325,851 gallons of water.) A year ago, the reservoirs were holding 385,000 acre-feet of water on Nov. 1, 2014, and the Yakima Basin was still one of the first regions of the state to be declared in a drought this year, on March 13, because of lack of snow.

If temperatures cool and significant snow begins to accumulate in the mountains, the picture may continue to improve for our statewide drought. However, predictions remain for a warmer-than-normal winter with below-normal snowpack. The El Nino weather pattern bringing those conditions is expected to be among the three warmest on record, dating back to 1950.

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