Isabella power plant operators have a plan to make repairs without drying up Kern River

December 29, 2023
by Lois Henry
Isabella Partners power plant at the base of the main Isabella Dam. SOURCE: Army Corps of Engineers
Lois Henry

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Engineers with Isabella Partners, which operates the power plant at the base of Isabella Dam, believe they’ve found a way to make repairs to the plant without drying up the lower Kern River for weeks on end.

If successful, water levels will drop from where they are now, but the river won’t go totally dry.

The work around will require fast action by an Isabella Partners crew that has been training on practice runs to weld a temporary “muscle wall” in one of two portals through the plant while water is cut back. Water will then be ramped back up through the main portal and dropped into the river bed, according to an explanation from Isabella Partners to William McKinnon, attorney for Water Audit California.

Roger Kirk, manager of the Isabella Partners’ plant, referred questions to McKinnon.

McKinnon has been working with Isabella Partners to find a way to keep flows in the river to protect fish populations since learning of the project several weeks ago.

The operation is expected to begin at 11 a.m. December 31, according to what McKinnon was told. The Army Corps of Engineers will cut releases from the dam to zero to drain both portals. Once they are clear, Isabella Partners’ crew will move in with the muscle wall.

“IP’s crew have trained to move as quickly as possible in the close quarters, and based on practice runs anticipate being able to start to restore flows in about 90-120 minutes, before the downstream channel will have appreciably dried,” according to Isabella Partners.

Flows through the main portal will ramp back up to 200 cubic feet per second and remain at that level throughout the repair project, which McKinnon was told is estimated to take seven days with crews working round the clock.

Concrete was damaged during heavy flows last spring when the plant had to be shut down after operators heard a “vibration.”

The Isabella Partners power plant at the main Isabella Dam is marked in orange. SOURCE:

Once repairs are made, the process will be repeated with flows cut off so crews can take out the muscle wall, according to what Water Audit was told.

McKinnon said the planned work around was successfully tested last week, but added: “This is innovative engineering and lives are at risk. As always, safety is primary. Highly qualified engineers will be supervising on site and will have the final go/no go decision.”

Isabella Partners had initially requested the Army Corps cut flows through the dam to just 25 cfs starting Dec. 18 and lasting several weeks, which would have decimated newly re-emerged fish populations downstream.

Water Audit and several other public interest groups had won an injunction in late October requiring the City of Bakersfield keep enough water in the river to protect the fish. But that injunction doesn’t extend to the Army Corps, nor Isabella Partners and neither had been informed of the court action.

When Water Audit learned of the impending flow shut down, “I flipped out,” wrote McKinnon in an email. He reached an attorney for Isabella Partners who he said worked diligently to find this solution.

“Unfortunately, for whatever reasons, the (agricultural districts with Kern River rights) and the City did not share the injunction with Isabella partners or USACE and did not share the shut down problem with Water Audit,” McKinnon wrote in an email.

He praised Isabella Partners and the Army Corps for putting “a lot of effort into preserving the living Kern River. IP and USACE are true heroes of the River.”

SJV Water is an independent, nonprofit news site dedicated to covering water in the San Joaquin Valley. Get inside access to SJV Water by becoming a member.


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