Dam demolition begins on Klamath River

Copco 2 is a diversion dam about a quarter-mile downriver of the larger Copco 1, which impounds Copco Lake east of Yreka in Northern California. The name “Copco” is an acronym referring to the California Oregon Power Company which merged with what is now PacifiCorp in 1961.

Completed in 1925, Copco 2 measured 35 feet tall and 278 feet long. It diverted water released from Copco 1 into a series of tunnels and penstocks ending at a rectangular powerhouse capable of producing up to 27 megawatts of electricity.

Power generation at Copco 2 stopped June 1, and the dam is now rapidly being dismantled by heavy machinery. Final removal is expected by September.

“It certainly is a momentous occasion,” said Mark Bransom, executive director of the Klamath River Renewal Corporation, or KRRC. “It is the culmination of work that has been done over the last couple of decades, most notably by tribal members and tribal governments that have been advocating for this action since the early 2000s.”

The Klamath Hydroelectric Project also includes J.C. Boyle Dam, upstream from Copco 1 in Southern Oregon near Keno, and Iron Gate Dam, downstream from Copco 2 near Hornbrook, Calif. The dams were built between 1911 and 1962, and collectively produced up to 169 megawatts of electricity.

By tearing down the dams and restoring a free-flowing river, tribes and environmental groups claim it will open 400 miles of previously blocked habitat for migratory salmon.

Razing Copco 2 marks the first step in that process, Bransom said.

In order for excavators to even reach the dam, the construction team, led by Kiewit Corp., first had to dewater the stretch of river between Copco 1 and Copco 2. That was accomplished by altering reservoir levels behind Copco 1 and Iron Gate dams.

From June 1-8, Bransom said they drew down Copco Lake by 8 feet. The water was sent downriver past Copco 2 into Iron Gate Reservoir, where it is now being stored and gradually released to meet minimum streamflows for salmon under the Endangered Species Act.

Additional storage capacity in Copco Lake has allowed for the area behind Copco 2 to remain mostly dry until the dam is fully removed.

“Of course, we have a little bit of flow. But by and large, it’s just a tiny amount,” Bransom said.

The gates, walkway and two of five bays down to the spillway have already been taken out at Copco 2. Meanwhile, hydraulic drills continue to chip away at the concrete weir, breaking it into smaller rubble pieces for disposal.