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Subject:   A New Water Year Begins:
Will it ever get wet again in the Northwest?
For Immediate Release:   
10/3/2003  12:00:00 AM
For More Information Contact:
Scott Thomsen  (206) 386-4233

SEATTLE— Happy New Year!

New water year, that is. For City Light and other hydropower-based electrical utilities in the Pacific Northwest, the water year begins Oct. 1 and runs through Sept. 30.

“We’re all hoping that the new water year is much wetter than the one that just ended,” said City Light Superintendent Jim Ritch. “As a hydro-dependent utility, we like rain and snow. A drought can reduce our surplus power revenues by millions of dollars. We can usually ride out a one-year drought, but anything longer than that begins to put pressure on rates.”

City Light’s dams on the Skagit and Pend Oreille rivers generate about 50 percent of the utility’s total power resources. Much of the rest comes from Bonneville Power Administration dams on the Columbia River system. Ninety percent of the electricity Seattle uses comes from hydropower.

Obviously, when it comes to Seattle’s electricity needs, wetter is better. But the ‘02-’03 water year wasn’t very wet.

Here are the dry facts:

  • City Light’s Skagit River watersheds received only 0.79 inches of rain for all of June, July and August
  • .
  • The watersheds for Boundary Dam on the Pend Oreille fared a little better, with 4.15 inches during those months.
  • The Skagit had the driest October and the wettest March on record.
  • The flow of the Skagit River into Ross Reservoir averaged 1,186 cubic feet per second in August and 748 cfs in September, the lowest flows in those months since record keeping began in 1909.
  • The Skagit watersheds ended the year at 72 percent of normal (44.56 inches).
  • Boundary watersheds ended at 86 percent of normal (40.09 inches).

So what’s a hydroelectric utility to do when Mother Nature won’t cooperate?

One thing City Light can do is use its reservoir like a big battery. At the Skagit, City Light can store water in Ross Reservoir. Stored water is stored power, which the utility can use or sell as needed. After a very dry October, November and December last year, City Light began to save water at Ross Reservoir. Usually, City Light draws Ross down during the winter months – Seattle’s peak demand season – and counts on the spring runoff to refill it. This past winter, the utility kept Ross about 35 feet higher than normal to help ensure refill in the summer.

It’s important to refill Ross by July 1 every year to keep it useable for recreation. A full Ross also ensures that City Light will have enough water to generate power and protect spawning Skagit fish and their eggs in the following fall and winter. Keeping more water in Ross cost City Light some revenue but left the utility and the fish in good shape for the fall and winter.

So what is the prognosis for the ‘03-’04 water year?

Long-range weather forecasting is part science, part Las Vegas. Most long-range forecasts are calling for near-normal precipitation. But that’s what they said last year. That’s also what was predicted for 2000-01, when the Northwest suffered through one of the worst droughts in history.

Because of the hot, dry summer and current low inflows into Ross Lake, City Light would like to see it rain early and often. However, because City Light was careful to refill Ross, and because it has other sources of power, there is no question that the utility will be able to meet retail demand this winter. The question is how much surplus will it have to sell on the wholesale market. This is revenue that is helping the utility pay off its short-term debt and recover from the 2000-01 energy crisis.

City Light will be paying close attention to the forecasts as the water year begins. This fall the utility will begin to track snowpack data from automated measuring sites called Snotels and will take its own snow measurements beginning in January. Snow in the mountains eventually ends up as water in the reservoir.

So happy new water year, Seattle. City Light hopes we’ll all be breaking out the bumbershoots soon.


(City Light customers can keep track of water conditions in City Light watersheds at http://www.cityofseattle.net/light/ctracks.html .)

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