Bare bulbs in wire cages light Aspect staff’s way down a flight of stairs through a damp concrete passage. One after another, we duck our heads, crawl through a water-tight steel hatch, and emerge in a cavernous chamber lit by a single halogen shop light. Our breath hangs in the cold air, and the sound of water drips from the surrounding shadows.
Our guide tips back his hardhat, stares upwards, and explains that we have now descended 150 feet below the surface of the Columbia River. He points with his flashlight towards the middle of the room, to where one of Wells Dam’s Kaplan turbines—a five-bladed spinning top the size of a garbage truck—sits idle. A month from now, when this chamber is again flooded by the river, water will push against those blades, turning a shaft that will activate a generator, create a charge, and produce electricity—enough to power all the houses in the Wenatchee Valley, and then some.
Celebrating the 50th Anniversary of the Nation’s Only Hydrocombine Dam
Fifty miles downstream of Wells Dam, geologists and engineers in Aspect’s Wenatchee office regularly interact with hydropower in our week-to-week work. From evaluating utility district water rights, supporting environmental compliance at fish hatcheries, to helping clients adhere to FERC permit requirements, the influence of dams in the Northwest is far-reaching.
When Douglas County PUD offered us an invitation to visit Wells Dam, which celebrated its 50th anniversary earlier this year, Aspect Wenatchee jumped at the opportunity.
Driving north along Highway 97 on a cold, snowy day in November, we had two things on our mind: what makes Wells unique, and what does it mean for a dam to reach this milestone? Here’s what we learned:
- Wells is the only dam in the U.S. designed as a hydrocombine, where the generating units, spillways, fish ladder, and switchyard are vertically stacked (as opposed to horizontally aligned). This gives the dam its compact footprint but presents certain logistical challenges for major maintenance operations.
- Like all Columbia River hydropower projects, Wells is a run-of-the-river dam. Reservoirs created by run-of-the-river dams have limited capacity to store water and must respond to fluctuations in seasonal river flows. For dams on the Columbia, this means that most of the available water comes from snowpack and is in greatest supply during the spring.
- Generating power at Wells represents a balancing act between storing and spilling water. In addition to coordinating reservoir levels with upstream and downstream dams, operators must forecast and respond to the Methow and Okanogan rivers, which eventually flow into the Columbia, all while complying with a suite of regulations for the protection of fish and wildlife, and fluctuating market demands of the regional grid.
- Like anything that involves a complex assortment of moving parts, things inside a hydropower project eventually wear out. For Wells, turning 50 means that each of the 10 generating units is reaching its in-service design life. Work is actively underway to completely refurbish, replace, or re-machine the turbine components to extend their service life another 30 to 40 years.
We greatly appreciated the tour and getting an up-close look at one of our region’s hydroelectric projects. Happy 50th Anniversary, Wells—thanks for keeping our lights on!