WENATCHEE — The big drawdown of the reservoir behind Wanapum Dam has stabilized a cracked spillway there, but it’s coming at the cost of lost power generation.
Wanapum Dam has the ability to generate some 700 megawatts this time of year. The drawdown, which dropped the level of the reservoir by 26 feet, has reduced generation to 360 megawatts.
The Wenatchee World reports that no financial-impact estimates were immediately available from the Grant County Public Utility District, owner of the Columbia River dam.
But the Chelan County PUD, owner and operator of the two dams immediately upriver of Wanapum, has had to stop all power generation at its Rock Island Dam. That means power with an estimated daily market value of more than $400,000 is no longer being generated there.
Chelan County PUD’s long-term contracts with its power purchasers — and the ability to increase generation at its Rocky Reach Dam — limit the financial hit to the utility.
“We’ll forego some revenue on the open market,” Mark O’Bryan, financial planning director at Chelan PUD, said, “but it doesn’t appear it will stress our financial conditions to the point we need to look at rates.”
Chelan PUD General Manager Steve Wright said restoring generation at Rock Island Dam and devising a plan to get migrating fish past the dam are now the utility’s two biggest priorities. PUD engineers are working to determine how much more water would have to be in the river for Rock Island to start generating again.
They hope to ask the Bonneville Power Administration to coordinate releases of enough water from big federal dams upriver to get Rock Island back on line. Portland-based Bonneville oversees power and water coordination on the Columbia River.
On the fish side of things, the clock is ticking. Adult fish will start heading upriver to spawn in late April and continue until November.
The Grant County PUD said that if the water level remains low into the migration season, one option to provide upstream passage is modifying existing Wanapum Dam fish ladders. Another option is to trap and haul fish via trucks around the dam.
With the cracked portion of the dam now stable, the Grant County PUD is studying the cause of the fracture, which was discovered on Feb. 27, and how best to repair the structure.