1. Owyhee Dam detail

Concrete work on the Owyhee Reservoir’s spillway-regulating ring gate, or “glory hole,” is expected to enter its second phase in late 2021.

A concrete structure near southeastern Oregon’s Owyhee Dam houses a steel ring 60 feet in diameter and weighing more than a ton. Differential valves are used to float or sink the ring. Sinking it increases outflows through three release points in the dam.

The system’s seals were refurbished about a decade ago.

“We learned some things we probably can improve on next time,” Owyhee Irrigation District Project Manager Jay Chamberlin said.

The nearly 89-year-old district supplies irrigation water to more than 167,000 acres near Adrian, Nyssa and Ontario, Ore. Phased improvements to the ring gate housing’s exterior concrete will increase durability and better protect the internal structure.

Crews from mid-October to mid-December built access infrastructure, restored and added reinforcement bars, and dismantled and replaced a roughly 40-foot section of concrete crest around the ring gate. Chamberlin said the district expects costs, still being tallied, to be between $30,000 and $40,000.

He said the project took about three times longer than expected due to challenging prep work, weather delays and coronavirus-related worker shortages. Most of the concrete was placed and finished by hand because access was difficult.

“The first (phase) was very difficult,” Chamberlin said. “It went longer than anticipated because of the unknowns. But the finished product, we were very pleased with.”

He said work on the second phase is expected to start around Nov. 1, depending on weather and reservoir levels. Five phases are planned.

Chamberlin said the district plans to buy a concrete pump, concrete saw and other equipment to increase efficiency and, ideally, improve a longer segment in 2021. A total cost of less than $50,000 is anticipated.