Developers are thinking about building a new transmission line to help meet the Northwest’s energy needs; a high-voltage transmission line that would run under the Columbia River.
Developers say that the region urgently needs new transmission and more ways to get energy from eastern Washington and Oregon to the more populated areas in the west. “Despite the potential for large-scale wind and solar east of the Cascades, much more east-west transmission to reach western load centers would be needed before most of these resources could successfully be built,” said Chris Hocker, with Cascade Renewable Transmission. The company is made up of a group of private companies that came together to build the transmission line.
Since above-ground transmission lines pose challenges and vulnerabilities with extreme weather and wildfires, the developers are proposing a 100-mile transmission line that would be buried underwater. It would start in The Dalles, Oregon, and end up in Portland. Part of the line would move out of the river to bypass the Bonneville Dam in Skamania County, Washington.
The project is still in the early stages of environmental review, from the Washington State Energy Facility Site Evaluation Council, or EFSEC. Construction would work like this: A hydroplow would dig a 24-inch underground trench using water jets. At the same time, a vessel on the water surface would pull the hydroplow along, as it lowered the bundle of transmission cables into the trench. The cables would be buried at least 10 feet below the riverbed. Finally, the trenches would be backfilled.
The trenching process caused concern for river advocates and Northwest tribes. For one thing, it could unearth historic burial grounds, said Elaine Harvey, a member of the Yakama Nation and watershed department manager with the Columbia River Inter-Tribal Fish Commission.
“My people are from the Columbia River, and the potential impacts that my ancestors will be uplifted during the trenching of this potential cable in the river, it’ll be very hurtful to see our ancestors unburied,” Harvey said during a webinar opposing the transmission line.
Other concerns include disturbing the riverbed and bottom-dwelling fish like lamprey or sturgeon, as well as the potential for the transmission cables to increase river temperatures at the detriment to migrating fish.
Read more about the project from OPB, A proposed 100-mile transmission line could be built under the Columbia River. Environmental groups and tribes say they have concerns, by Courtney Flatt.