At French Lake, divers helped restore a critical piece of water infrastructure.

 

It’s not every day you see commercial divers working beneath the surface of an NID reservoir. But this summer, a dive crew descended into French Lake to work on a piece of water infrastructure that has been operating for nearly nine decades.

The project focused on the low-level outlet gate at French Dam, NID’s oldest dam still in use. Built in 1858–1859, French Dam sits on Canyon Creek in the South Yuba watershed at an elevation of about 6,660 feet.

The gate itself dates to 1937, and its underwater hydraulic actuator—the mechanism that opens and closes the gate—had been in service for 89 years.

Over time, the actuator and hydraulic lines had become worn and leaky, making the gate increasingly difficult to operate. What once took a relatively straightforward hydraulic operation had become a labor-intensive job requiring roughly 200 hand-pumping strokes.

That’s where the divers came in.

Working beneath the surface, the dive crew removed the aging hydraulic ram so its dimensions could be accurately measured and a replacement actuator fabricated. The project also included replacing the deteriorating hydraulic lines and restoring reliable control of the low-level outlet gate.

The work is part of NID’s ongoing effort to maintain and modernize the infrastructure behind the District’s water system. The French Lake low-level outlet is important for safely managing water stored at the reservoir; maintaining its reliable operation helps ensure the District can properly control releases from the lake. NID’s project documents identify the aging hydraulic lines, pump and ram as needing replacement to ensure safe and proper operation.

Nearly 90 years old—and still doing its job

French Dam is a reminder that much of NID’s water system has deep roots. The District operates infrastructure ranging from historic facilities dating to the Gold Rush era to modern treatment, monitoring and control systems. French Dam was constructed in 1859 and raised in 1948; today, the reservoir holds nearly 14,000 acre-feet of water.

Keeping that system reliable means maintaining it long before a problem becomes an emergency.

Sometimes that means crews working on a canal or pipeline. Sometimes it means replacing aging equipment. And, occasionally, it means sending divers into a mountain reservoir to bring an 89-year-old piece of infrastructure back to reliable working order.

For NID, maintaining the past is part of preparing the water system for the future.