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Errors Found in Bonneville Dam Spill Volume by Associated Press Seattle Post-Intelligencer - July 31, 2004

PORTLAND -- Records on the volume of water flowing through the Bonneville Dam spillway during the past 30 years may be off by as much as 30 percent, authorities said yesterday.

Army Corps of Engineers authorities blamed the inaccurate water-volume estimates on incorrectly calibrated gate openings dating back to replacement of the spillway gates in the early 1970s. The height of the gates was increased, leading to the error. But the effect went unnoticed until recently, authorities said.

The total flow of water past the dam, which is on the Columbia River about 40 miles east of Portland, was not affected, only the volume through the spillway, said Cindy Henriksen, reservoir control center chief for the corps in Portland.

"The amount of water passing the dam remains the same. We are not holding water back," Henriksen said. But now that the error has been identified, "adjustments are fairly simple to make," she added.