Ok, let’s all recite this together: Do not count on long-range forecasts about weather in the Pacific Northwest. You are almost always bound to be wrong. Three months ago, in February, I looked at precipitation in the mountains and precipitously noted a growing deficit in the region’s snowpack.
This is important information, I noted with seriousness, since many industries in the state, especially irrigated farming in Eastern Washington, depend on adequate snowfall in the mountains. An El Niño year was creating a mild winter and little snow in the mountains after an initial dump of good snow in late November and December. By February, a deficit was mounting.
Time to sound the alarm, I thought. Low snowpack. Problems in the summer. Farmers eyeing the brown foothills of the Cascades. The ski season in peril.
Silly me. My only saving grace was to have noted that, of course, it all depends on how the spring unfolds. A cool/cold spring would keep the snowpack from melting quickly and might ease the overall problem.
So a cold spring and recent heavy spring snowfall in the mountains have made a mess of the early forecast. The Basin Outlook Report for April, published by the National Resources Conservation Service, said snowpack levels statewide were at 89 percent of average at the end of the month and “by the time of this release (May 8) we are at 98 percent.”
“For the most part near normal temperatures and above average precipitation are helping bring conditions as close to normal as we’ve seen all year,” the report said. “The welcome rain and mountain snow have increased soil moisture conditions and built snowpack which has brought a sigh of relief to many across the state.”
The report is not beyond making its own assumptions about the weather. It says weather forecast models are predicting the rest of May will be warm and mild, and “summer is also shaping up for a warm and dry season.” The phrase “shaping up" is a good one to cover the unknown.
Of course, the “water year” runs only from October to June because even normal summer precipitation accounts for just 13 percent of total annual rainfall.
Some details on snowpack from the report: The Similkameen River, which runs through southern British Columbia into the Okanogan River near Oroville, Okanogan County, reported the lowest readings at 13 percent of average. Readings from the Olympic Peninsula reported the highest at 119 percent of average.
Westside averages included the North Puget Sound river basins, 78 percent of average; the Central Puget Sound river basins, 72 percent; and the Lewis-Cowlitz basins, 102 percent. Snowpack along the east slopes of the Cascade Mountains included the Yakima area with 84 percent and the Wenatchee area with 95 percent.
A number of agencies track stream flows for various reasons. The Bonneville Power Administration tracks snowpack and river flows because of the impact on its revenues. The BPA does not think we are out the woods by any means on snowpack. It said last week in a release:
“The Bonneville Power Administration now estimates it will likely finish the fiscal year with negative net revenues of approximately $230 million. This shortfall was reported in BPA’s second quarterly review published April 30 and is a direct result of the Northwest’s low snowpack. Reduced stream flows have resulted in $450 million less revenue than BPA anticipated at the beginning of the fiscal year.
“Traditionally, BPA’s sales of surplus power — power available beyond BPA’s commitments to its customers — have represented about a fifth of the agency’s revenues. Snowpack is the fuel that typically provides surplus power from the hydro system, and revenues from these sales help keep Northwest electricity rates down.”
BPA Administrator Steve Wright said that “this is a bad situation that has just gotten worse. We had hoped a wet spring would help snowpack across the Columbia River Basin, but that didn’t happen.” BPA said the agency is looking at the fifth lowest runoff since the hydro system has been in existence. Columbia River flows depend in part on snowpack in the Canadian side of the watershed, where levels are as low as 50 percent of normal.
However, another agency that monitors Northwest power said the Northwest electricity supply will remain adequate throughout the spring and summer despite abnormally low runoff in the Columbia River Basin.
The Northwest Power and Conservation Council said the power available from generating plants, including hydropower dams, wind turbines and power plants that burn fossil fuels, is more than adequate to meet the anticipated demand for electricity this year.
The Council recognizes the Columbia River flow will be much lower than normal. In a statement the Council said that “based on precipitation to date, the forecast for runoff through the end of August also is much lower than normal — just 65 percent of average measured at The Dalles Dam. If that estimate proves accurate, 2010 would be the second-lowest runoff year since 1992. Only 2001 was lower.”
Closer to home, Seattle Public Utilities says water supplies for its 1.3 million customers are good this summer.
According to the city, most Seattle water is from the 90,000-acre Cedar River Watershed and the 13,300-acre South Fork Tolt River Watershed in eastern King County; combined that’s an area about the equivalent of two cities the size of Seattle.
Late April rains and snow have increased reservoir inflows. A city report dated May 4 said Chester Morse Lake at the Overflow Dike is about 4.3 feet above its long-term average (based on the years 1989 to 2005). Masonry Pool Reservoir at Masonry Dam is about 5.3 feet above its long-term average.
“We have three seasons,” said Tom Fox, Water Resources Manager. October through February is the flood season, when the region gets the most rain. From about February to June, it’s the refill season, trying to get reservoirs to the highest level possible. “Then it’s waiting for the rains to return season.”Fox said it was an unusual season with some concern in March because of low snowpack and much less rain than usual in the two basins. But the April and early May precipitation has turned things around and it looks like a fairly normal year for water supplies. Seattle water managers, like the managers of many of the region’s streams and rivers, must also release enough water for migrating fish.
Seattle customers continue to be responsible users of water. A recent seven-day average of 103 million gallons a day came in less than the 114 million consumed during the same period last year — and dramatically less than the average of 123 million used during the same period over the years 1999-2008.
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