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On time is perhaps the sweetest phrase a project manager can hear.
For projects that are of the size and scope of the Isabella and Schäfer dam reforms, adherence to the schedule is particularly important.
“It has been a long time and we are now close to the finish line,” Richard Brown, a spokesman for the Army Corps of Engineers, said of the comprehensive repairs to the Isabella Dam in Kern County.
Brown said both projects have been “on the books” for years.
“All of these projects take years and years,” he said. “Repairing existing dams is more difficult than building an entirely new dam.”
Repairs to Isabella, which had a leak under the additional dam and an active, quiet earthquake fault below, actually began in 2012 with actual construction only beginning three or four years ago.
Major work on the additional dam involved cementing the downstream side to prevent erosion. On the main dam, the concern was the overflow of the flowing water after the great jolt of the earthquake.
To prevent this, the Corps raised both dams by 16 feet. It also built a second emergency drain with a “maze weir” in its mouth. The existing drain duct will remain in use as needed.
The Labyrinth Dam is a meandering concrete structure 10 feet high and 1,100 feet wide so that water flows in a more controlled manner during the very high water years.
Brown said the drain is more than half finished and the maze weir is 40 percent finished.
He said the $650 million project is in the budget and on track for completion next spring.
Downstream users will not get any additional water from dam repairs because they will not increase the amount of water that can be held in the lake. But the repairs will allow the lake to be filled to a capacity of 568,000 acres again. It was restricted to 360,000 acres only for safety reasons after the discovery of the leakage fault and the earthquake.
Dam repairs at Lake Success in Tulare County, which was renamed in 2019 in honor of longtime Toole River water pioneer Richard L. Schaeffer, are not as extensive as those made on Isabella Dam.
But they are complicated in their own way. The first stage is about to end. The Corps had to reorganize 146th Street, which operated primarily above the dam’s downstream.
Once this is completed, the Corps will begin work to expand the drain channel from about 200 to 300 feet and build a 10-foot “ogee Weir” at the mouth of this flow. The Oji Dam is a concrete barrier with a circular face downstream. Similar to the labyrinth dam, it provides a controlled flow in high water years.
The Schaeffer Dam project will increase the amount of water in Lake Success from 82,300 acres to 110,300 acres. An additional 28,000 acres will be allocated to water users based on existing rights.
The $135 million project is expected to be completed in 2023.
The Corps also manages Lakes Kaweah and Pine Flat.
Louis Henry is the CEO and Editor of SJV Water, an independent, non-profit online newsletter dedicated to covering water issues in the San Joaquin Valley. She can be reached at [email protected]. The site is sjvwater.org.
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