Wednesday, June 8, 2011
Above average snowpack across the western United States and Canada, combined with a cooler and wetter than average spring have contributed to the highest water levels the Columbia River has seen in 15 years. In the Bonneville Pool - the section of river between The Dalles and Bonneville dams - the river is flowing at close to half a million cubic feet per second; while downstream of Bonneville, the river level as of Thursday at the I-5 bridge near Vancouver, Wash., was half an inch from flood stage.
What happens with water levels in the next few weeks will depend on what happens with the weather. If the Columbia basin doesn't see serious rain, and temperatures are close to average for this time of year, the river is expected to continue to rise slowly, peak not far from where it is now and head steadily back toward normal in July. If, however, warm and wet weather combine, especially in high elevations with extensive snowpack, the river could spike significantly higher and approach record levels that haven't been seen since 1996, when the Columbia was more than 11 feet over flood stage at Vancouver.
From Hood River, the most obvious sign of the high water is the missing sandbar, which is covered by about three feet of cloudy water.
"This is a very different year," said Chuck Orwig, senior hydrologist for the National Weather Service. "A lot of the higher-elevation snow across the basin has hardly been depleted; it's about a month behind. We're expecting the overall trend to remain upward into July."
"There's a tremendous amount of snow out there that's starting to melt," said Scott Clemens, Army Corps of Engineers. "Earlier this week there was rainfall in excess of 2.5 inches in Northeast Oregon and the Cascades, and the elevated levels we're seeing now are a result of that water making its way through the system."
Clemens said on Wednesday that The Dalles Dam was running at about 440,000 cfs and Boneville at 459,000 cfs. which is roughly the volume of water equivalent to submerging a football field ten feet deep in water every second. Corps officials caution that if warm weather patterns continue, flows may reach 480,000 cfs next week.
In periods of extreme flow on the Columbia River, Bonneville Power Administration and the Army Corps of Engineers, among others, have a difficult balancing act to achieve. The energy generated from the series of dams up and down the river must match the demand on the grid, which is now interconnected throughout the west coast.
"From our perspective, all this water generates a lot of power," said Michael Milstein of Boneville Power Administration. "And that supply must match the demand at all times."
He explained that in addition to managing supply from dams, wind generators and thermal power sources, agencies must also pay close attention to water quality for the safety of fish and aquatic wildlife. Increased turbulence and churning of water from spillways increases dissolved gas levels in the water, which can be harmful or deadly for fish.
"Rising runoff has pushed dissolved gas levels at most of the eight federal dams on the Lower Snake and Columbia Rivers above 120 percent, exceeding Washington and Oregon water quality standards and threatening protected salmon and steelhead," BPA stated in a press release earlier this week. "Reducing hydroelectric generation in such circumstances would send more water through spillways and could push gas levels higher for longer periods, further endangering fish."
Milstein said that to address that conundrum, dams are running as much water as possible through their turbines to cut down on turbulence created by simply running water through spillways. The effect of that, though, means dams are generating a lot of power in a time when the demand isn't at a peak.
In a decision that took effect Wednesday morning, BPA acted to limit all coal, natural gas and other thermal generation to minimum levels required for grid stability and safety so as to allow the dams to run as much water as possible though turbines.
Milstein said coal was the first to go offline and wind energy was the last, and the reverse will apply when alternate forms of generation are able to come back online; which, he says, will be as soon as possible.
The decision didn't sit well with a group that represents wind energy interests.
"BPA tries to claim it would curtail wind generation instead of spilling water over its hydroelectric dams for environmental reasons," read a statement from the American Wind Energy Association. "Rather than being an environmental issue, the policy is a classic case of anti-competitive and discriminatory behavior by a utility with a conflict of interest … BPA, as the 'air traffic controller' for the Northwestern grid, is allowing some generators to operate while blocking others … BPA has not sufficiently pursued other measures before curtailing wind, despite its claim that curtailment is a last resort."