LOIS HENRY: Dam repairs on track | Lois Henry – Bakersfield, California

Bakersfield, California 2021-06-13 16:00:00 –

On schedule, it’s probably the sweetest phrase a project manager can hear.

Scheduling is especially important for projects that are the scale and scope of Isabella Dam and Schaefer Dam repairs.

Regarding a major repair of Isabella Dam in Kern County, Army Corps of Engineers spokesman Richard Brown said:

Both projects have been “in the book” for years, according to Brown.

“All these projects will take years,” he said. “It’s harder to repair an existing dam than to build a whole new dam.”

Repairs to Isabella, which had penetrated under the auxiliary dam and had a lively and quiet seismic fault running beneath it, actually began in 2012, when actual construction began just three or four years ago.

The main task of the auxiliary dam was to reinforce the downstream side to prevent erosion. At the main dam, concerns were raised as water sloshed after a major quake.

To prevent that, the corps raised both dams 16 feet. We also constructed a second emergency floodway with a “maze weir” at the estuary. The existing spillway will continue to be used as needed.

The labyrinth weir is a 10-foot high, 1,100-foot wide concrete zigzag structure that allows water to flow in a more controlled manner during very high water volumes.

According to Brown, the spillway is more than half complete and the maze weir is about 40 percent complete.

He said the $ 650 million project is within budget and is expected to be completed by next spring.

Downstream water users do not get extra water from dam repairs because they do not increase the amount of water they can hold in the lake. However, the repair will once again fill the lake to a capacity of 568,000 acre feet. After the infiltration and seismic faults were discovered, safety concerns limited it to only 360,000 acre feet.

The repair of the Lake Success Dam in Tulare County was renamed in 2019 in honor of Richard L. Schaefer, a longtime water master of the Tule River, but not as extensive as the repair of Isabella Dam.

But they are just as complex in their own way. The first phase is almost complete. The corps had to readjust Avenue 146, which was essentially running through the outflow of the dam.

Once that is complete, the corps will begin work to extend the spillway from approximately 200 feet to 300 feet and build a 10-foot-high “Ozzy Weir” at the spillway mouth. The Ozzy Weir is a concrete barrier with a rounded downstream surface. Similar to the labyrinth weir, it provides a controlled runoff in high water years.

The Schaeferdam project will increase the amount of water retained in Lake Success from 82,300 acre-foot to 110,300 acre-foot. That extra 28,000 acre-foot will be allocated to water users based on existing rights.

The $ 135 million project is expected to be completed in 2023.

The corps also operates Lake Cavea and Lake Pine Flat.

Lois Henry He is the CEO and editor of SJV Water, a non-profit, independent online news publication that addresses the water issues of the San Joaquin Valley.She can reach at

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