In June 2023, the Army Corps of Engineers began physical work on a gate rehabilitation contract, which was to repair cracked welds identified during routine gate inspections and to re-paint the gate.

As part of this rehabilitation contract, gate 3 was removed and the spare gate was put in its place.

The paint on gate 3 was removed and an in-depth gate inspection was completed. 

During the gate rehabilitation, steel defects were discovered in critical girders in April 2024.

These base metal defects include holes and cracks in the steel. In the event a gate should fail, it could lead to injury to the crane operator, damage to the crane and bridge, and loss of control of lake level. 

The current defects were likely a result of the steel rolling process that was used in the 1950s. The rolled steel has likely worsened over time.

All spillway gates and the spillway bridge were built at the same time (1950s) with the same steel fabrication (Federal Specification QQ-S-741a or ASTM A7 Steel).

The only way the current defects could have been effectively discovered and identified was after gate 3 was removed from service and its paint removed. 

The current defects can increase/grow through further gate use and subjecting them to load from water pressure. Operating the gates to control water flow creates dynamic loads on the gates, increasing risk/stress on them.

These defects do not pose a safety risk to the public.

Safety of our dam operators and maintaining our routine operations is paramount. As a result of these defects, in May 2024 we restricted operations for the 2024 water year which includes:

Lowering summer lake elevation band to an intermediate 2061.75 ft. - 2062.25 ft. level to avoid static loading stress concerns on the gates. For summer 2024, we achieved 2061.75 ft on June 19th. The lake was held in that band until September 22nd when we started fall drawdown. 

Minimizing gate movements to minimize the risk of gate failure by operating the gates in either fully open or fully closed positions only.

Operating conservatively today reduces the risk of a catastrophic failure of any gate. 

In the event of a gate failure, several impact scenarios exist depending on multiple factors such as how the failure occurs and the time of year. 

• Implications of a gate failure to upstream residents could result in a SLOW loss of lake level below an elevation of 2051 ft.
• Implications of a gate failure to downstream residents would NOT result in flooding as the river channel capacity can absorb the inflow in the event of a sudden, uncontrolled release of water. 

Regardless of the scenario, failure of a spillway gate would impact the project's ability to maintain stable lake levels. 

• Over the 2024 winter, the Army Corps will evaluate the best approach for a safe and effective spring refill and summer operation for 2025. 

• The Army Corps is working toward a temporary repair to gate 3, to return it to service in time for spring 2025 runoff, and allowing the project to have its one backup gate. Restricted operations will remain in place. ​​

• Funding for the new spillway gate/s design has been secured. Design is already ongoing and expected to be completed fall 2025.​​

• The first gate installation is anticipated in 2027 and subsequent gates to arrive in 6-month intervals, dependent on industry capability.