Oroville – The group that 12 years ago warned the Oroville Dam emergency spillway could fail, Tuesday released a new set of recommendations for operation of the dam and the Feather River flood control system.

“It’s not enough to be right in the rearview mirror,” said Eric Wesselman, executive director of Friends of the River in a media call Tuesday morning. “Existing infrastructure needs to be fixed now.”

In 2005, Friends of the River, along with the Sierra Club and the South Yuba Citizens League, asked the Federal Emergency Regulatory Commission to require the Department of Water Resources to build a full concrete emergency spillway to replace the existing concrete weir with a bare hillside below it.

The request was rejected, and when the emergency spillway was first used in February, rapid erosion of the hillside threatened the weir’s collapse, and prompted evacuation orders for 188,000 people, the largest evacuation in California history.

Now the Friends of the River have produced “The Oroville Dam 2017 Spillway Incident and Lessons from the Feather River Basin,” in concert with the California Sportfishing Protection Alliance, the South Yuba River Citizens League, and American Whitewater.

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The report is available at the Friends of the River website, www.friendsoftheriver.org. It includes a full history of the dam, this year’s spillway emergency and actions taken since then.

Recommendations

The group still calls for a “real” full concrete emergency spillway, instead of the cutoff wall and concrete splash pad DWR has planned.

Failing that, it said the lake level should be kept even lower to accommodate huge inflows such as those that happened in February and overwhelmed DWR’s efforts to manage the lake level with the damaged main spillway.

In an email, DWR spokeswoman Erin Mellon said, “DWR is exploring all long-term options at Oroville Dam including a fully lined emergency spillway or another flood control spillway. Current construction at the emergency spillway includes building an underground secant pile cut-off wall, which will prevent the kind of uphill erosion that occurred in February.”

The report also called for DWR to review and upgrade the “dam complex’s physical deficiencies.”

It listed changes to ensure the Hyatt Powerhouse could release water, and remediation of cracking concrete and settlement of the main spillway headworks.

Investigation of seepage through the dam — the green spot — was included, and a warning system was called for.

Operational changes were also urged. The report noted the operational manual for the dam prepared by the Corps of Engineers decades ago assumed another dam would be operating on the Yuba River, but it was never built.

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