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Council predicts adequate power supply despite low Columbia River flows, but surplus power sales, wind-power backup, and fish passage will be affected

April 14 2010  | 

PORTLAND, Oregon — The Northwest electricity supply will remain adequate throughout the spring and summer despite abnormally low runoff in the Columbia River Basin, where hydroelectric dams provide more than half of the region’s electricity, according to an analysis by the Northwest Power and Conservation Council.

“Low flows will reduce hydropower generation below normal, but there is no danger of a serious curtailment to electricity service, according to our analysis,” Council Chair Bruce Measure 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.”

Columbia River basinwide precipitation since last October, which is the beginning of the water year for recordkeeping purposes, is 79 percent of normal, and snowpack is 73 percent of normal, according to the Northwest River Forecast Center of the National Oceanic and Atmospheric Administration. At this time in 2009, the snowpack was 91 percent of normal.

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.

While the Council expects an adequate power supply, the dry year will have consequences, according to the analysis. Less surplus hydropower will be available for sale in the wholesale power market, and so the revenue from those power sales would be lower than in a normal year. As well, less hydropower will be available to back up wind power, which is highly variable.

Lower-than-normal flows also will make migration conditions more difficult for juvenile salmon and steelhead this spring and summer by slowing travel time and perhaps by increasing water temperature. The federal biological opinion on Columbia River hydropower dam operations, which is intended to protect threatened and endangered species of salmon and steelhead, calls for maximizing barge transportation of juvenile fish down the river in low-flow conditions. However, the biological opinion is being challenged in federal court, and a judge will decide whether to follow the strategy in the biological opinion and maximize transportation — that is, no spill at the three dams that have smolt-collection facilities — this year or order additional spill in conjunction with barge transportation as the plaintiffs have requested. The judge has ordered additional spring and summer spills since 2007.

According to the Council’s analysis, additional spill, if it is ordered by the court, will not affect river flows or the elevation of reservoirs behind Columbia and Snake river dams. However, water that is spilled over dams cannot be used to generate electricity, and the additional spill, if it is the same amount as the court ordered for the spring and summer of 2009, would reduce power generation by about 350 average megawatts across the April-through-August 2010 period. One average megawatt, 1 million watts, is enough for about 670 Northwest homes, and so the April-through-August loss would be approximately equal to the power use of 234,500 homes. This reduction in hydropower generation would be in addition to the annual reduction due to the required spill in the biological opinion and would not affect the reliability of the power supply, according to the analysis.

See Council staff report (60k PDF) and presentation (1mb PowerPoint)