USACE unveils Isabella Dam modifications in ribbon cutting

April 10, 2023
Improvements to the dam, including improved filtering/drainage systems and a new labyrinth weir, will reduce flood risk and provide water storage for the surrounding area.

The U.S. Army Corps of Engineers (USACE) Sacramento District held a ribbon cutting ceremony on Tuesday, April 4, to celebrate the end of Phase 2 construction for the Isabella Dam Safety Modification Project.

The safety modification project will reduce flood risk for the southern Central Valley of California and provide water storage for downstream water users.

“The amount of technical expertise on display behind me is matched only by the incredible and collaborative relationships between our partners,” said Lt. Gen. Scott Spellmon, USACE commanding general, as he stood in front of the new 28-foot-high labyrinth weir at Isabella Dam. “I want to extend a very special thanks to the community who came together to help make today a reality.”

Isabella Dam consists of a main and auxiliary dam located just north of Lake Isabella, California. In 2006, a USACE study found the dam vulnerable to three potential failure modes: overtopping, seepage, and seismic damage. The Isabella Dam improvements, begun in late 2017, were designed to address each of these failure modes.

Over the next five years, the USACE Sacramento District raised both the main and auxiliary dams by 16 feet, excavated a new emergency spillway, improved the dam’s filtering and drainage systems, and installed the labyrinth weir. These safety improvements were substantially completed in November 2022.

The USACE Sacramento District has coordinated closely with Kern River Water Master Mark Mulkay, who also spoke at the ceremony, and downstream water users to determine how

Follow-on construction in Phase 3 will include building a new U.S. Forest Service visitor center in Lake Isabella and a permanent operations building for the USACE staff that oversee the daily operations of Isabella Dam.

Completed in 1953, Isabella Dam is located approximately 40 miles northeast of Bakersfield. The reservoir is impounded by two earthen dams on the Kern River and Hot Springs Valley. Today, Isabella Lake and its dams reduce flood risk for Bakersfield and the surrounding region and is a primary water source for water users throughout Kern County. The Isabella Dam Safety Modification Project addresses overtopping, seismic and seepage issues identified with Isabella Lake’s main and auxiliary dams to reduce the likelihood of dam failure. Construction of the dam modifications began in 2017 with the relocation of facilities within the project footprint, and the project achieved substantial completion in 2022.

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