A major electric utility in the Northwest, PacifiCorp, said yesterday that it would pay $17 million to remove a dam rather than cough up the $30 million that would have been needed to make it less harmful to fish. At 125 feet in height, the Condit Dam on the White Salmon River in southwestern Washington would be the tallest dam ever breached in the U.S. Under an agreement announced yesterday, which still needs approval from federal regulators, the dam would be removed in seven years. Enviros are optimistic that as many as 10,000 salmon could return to the river once the dam comes down. The decision, which was praised by Interior Secretary Bruce Babbitt and Washington Gov. Gary Locke (D), gives a boost to a growing dam-removal movement.