By Marcy Stamper
As it moves forward with potentially generating power again at Enloe Dam, the Okanogan County Public Utility District (PUD) needs to examine the condition of the almost-century-old dam.
The PUD is soliciting proposals from firms that can dewater the face of the dam on the Similkameen River so they can inspect parts that are normally under water. The inspection will examine the toe — where the dam sits on the riverbed — and where the structure meets each shoreline, according to Tim DeVries, director of engineering and operations for the PUD.
Most dams are built so that water can be diverted, but Enloe is a run-of-the-river dam, meaning that water is constantly flowing over it, said DeVries. Possible techniques for exposing the face of the dam include pumping or siphoning the water, or diverting the river to one side of the dam with batten boards and then switching to the other side, he said.
“It’s going to be interesting — we’re not sure what we’re going to do,” said DeVries.
The PUD has a license from the Federal Energy Regulatory Commission (FERC) to restart Enloe. A safety inspection of the infrastructure is one condition for moving ahead with plans to generate power there.
The inspection will also assess conditions of the crest and face of the dam, including the spillway chute, according to the PUD’s solicitation. The rock foundation will also be inspected.
The PUD anticipates the inspection will be conducted in part by divers. Provisions for the inspection include not only safety for the inspectors but also a means of creating underwater visibility, given the turbulence in the river.
Any inspection would have to be done in accordance with environmental regulations to protect water quality, fish and aquatic vegetation, according to the solicitation.
The PUD plans to do the inspection during the low flows of August and September.
In addition to moving ahead with the FERC licensing process, the PUD is still in discussions with groups that favor removal of the dam. Parties working on a potential plan for removal are still developing a proposal and seeking a lead agency to supervise the decommissioning of the dam and to eliminate all liability for the PUD. They have until the end of June to identify a lead agency, said DeVries.