Army Corps to raise spillway at Success Lake. It's nothing like Oroville

The Army Corps of Engineers will spend $74 million to enlarge Success Lake east of Porterville, doubling flood protection for the city and boosting the water supply for farmers.

It’s not the only Army Corps project in the majority leader’s district that got major funding. Lake Isabella in Kern County is getting $258 million for a dam safety modification project.

Porterville Mayor Milt Stowe credited House Majority Leader Kevin McCarthy, R-Bakersfield, whose district includes Porterville, for getting the money for the local project that area officials have been working on for years. Construction is expected to start construction in four years.

“We would sincerely like to thank Congressman McCarthy for his dedicated efforts and tireless support for this long needed project,” Stowe said.

The money is from a $17 billion appropriation by Congress for long-term disaster recovery projects and short-term repair projects across the nation. A list of projects approved by the Corps, including for Success and Isabella, was released Thursday.

The Success reservoir enlargement project would widen the spillway and raise it by 10 feet. Design is expected to take two years.

According to both the Corps and local water experts, the spillway at Success Dam is nothing like Oroville Dam, where erosion of the concrete spillway forced a mass evacuation last year.

Success Dam doesn’t have erosion, Army Corps spokesman Tyler Stalker in Sacramento said.

“The project does not have any issues that would cause concerns about the integrity of the dam or the spillway,” he said.

Dan Vink, executive director of the South Valley Water Association, said the main spillway at Oroville goes over the top of the dam, but at Success the spillway is a channel in the ground next to the dam.

“We don’t use the spillway to make controlled releases,” he said. “We have gates at the bottom of the reservoir.”

Success Dam was built in 1961 for flood control and irrigation water storage.

The lake holds 82,300 acre-feet of water. Raising the spillway would increase storage to 110,000 acre-feet – about one-third larger.

That would increase flood protection for Porterville and the floodplain around Tule River, with flood risk rising from one in a 49-year flood to one in a hundred-year flood.

A bigger lake means irrigation districts and farmers could store more water in wetter years.

“There will be 8,000 acre feet of additional water supply on average,” Vink said.

The cost may be less than $74 million, he said. The local economic impact is not known but it’s likely bids would come from in-state companies, he said.

Enlarging the lake was envisioned about three decades ago but the project was stopped about 15 years ago when concerns about the dam failing in an earthquake emerged. Those concerns were dismissed after a Corps study said the dam would hold.

Lewis Griswold: 559-441-6104, @fb_LewGriswold