PORTLAND (AP) — The Confederated Tribes of the Warm Springs and Portland General Electric have agreed to restore fish passage around the Pelton and Round Butte dams, which they own jointly.

The project will allow downriver passage of salmon and steelhead in the Metolius, Upper Deschutes and Crooked rivers for the first time in 40 years.

The tribe and utility say passage will be restored through a unique 273-foot underwater tower and fish collection station at Round Butte Dam, the farther upstream of the two. The reservoirs store water from all three rivers.

The tower is designed to modify currents and temperatures to mimic natural conditions and attract migrating fish into the collection facility. These fish will be sorted, and young salmon and steelhead will be trucked downstream past Pelton Dam to continue to the Columbia River and the Pacific Ocean.

When they return as adults, the fish reaching the lowest dam are to be sorted and trucked above Round Butte Dam to reach the upstream spawning grounds.

“This is an innovative solution to restoring fish passage in the Deschutes River Basin,” said Stephen Quennoz, PGE’s vice president of power supply and generation.

“This new tower is the result of a commitment the tribes made 10-plus years ago when relicensing was in its infancy. This helps restore a fishery that has been a vital part of our culture,” said Bobby Brunoe, general manager of natural resources for the tribes.

Construction on the $108 million project above Round Butte Dam in Lake Billy Chinook is under way and on target to be operational by spring of 2009.

The Pelton Round Butte project produces enough energy to serve a city the size of Salem and is the only one in the nation jointly owned by a tribe and a private utility.