The largest dam removal project in the United States is under way on the Klamath River along the Oregon-California border.
Copco Number 2 was the first of four dams to be removed.
“The river was stopped here for nearly 100 years. And seeing the river flows go through this canyon now can inspire a lot of hope,” said Ren Brownell, Klamath River Renewal Corporation public information officer.
The other — JC Boyle closer to Klamath Falls, Copco Number 1, just upstream from this site and Iron Gate, a few miles downstream — will be removed in 2024.
“This one has a unique situation because this one was only 33 feet high, whereas Iron Gate is 180 feet, but it still had quite an impact on the landscape,” Brownell said. “Because it was a diversion dam, it went straight across where we are standing here and diverted all the river’s flows into a tunnel system that fed a powerhouse downstream — 1.7 river miles downstream where we are standing, essentially de-watering the canyon below us.”
The dams were built from 1918 to 1962. Their sole purpose was to generate hydroelectric power.
Their impacts were catastrophic to the environment. Salmon runs crashed as fish were cut off from hundreds of mile of spawning habitat. Water quality in the reservoirs became toxic at times, resulting in multiple fish kills.
As it became clear the costs to modernize the dams exceeded the value of upgrading and relicensing them, Pacific Corps agreed to remove them with financial support from the states of Oregon and California.
“There’s a lot of communities downstream, a lot of protected species so in the scenario of these dams we are going to do a very slow draining of these reservoirs. We are going to drain them at 3,000-4,000 cubic feet per second. We will do that over the period from January to February. If we get a big winter, there’s potential for the dams to refill a bit and we’ll have to redrain them again. We expect we will have deconstruction underway in earnest by next summer,” Brownell said.
There’s 17- to 20-million cubic yards of sediment sitting behind the dams, much of which will be flushed downstream. Project managers say the river will be muddy for months next spring and summer as the reservoirs are drained and the dams are removed.
As the water levels in the reservoirs drops, restoration will begin.
“As the reservoirs are draining for the last time, we’ll have crews out scattering seed, taking advantage of the moisture in the soil. There’s currently 2,200 acres submerged in the reservoirs. We’ll be restoring all of that with native trees.”
Explorer John C. Fremont found salmon in what is currently Klamath Falls all the way back in 1846. Salmon made it all the way up to the Sprague, Williamson and Wood rivers in south central Oregon. Their nature is to swim upstream and find spawning habitat. They are expected to explore and repopulate the Klamath and the tributaries once the dams are removed.