What went wrong at Oroville?

Dam experts release a report on the California dam’s spillway vulnerabilities.

 

After intense rainstorms in February 2017, two spillways at Northern California’s Oroville Dam began to disintegrate under the force of the water rushing down them. Officials, concerned that erosion might undermine the side of the reservoir itself, evacuated more than 180,000 people. The reservoir ultimately held, but the spillways required extensive, ongoing reconstruction.

In early January, an independent group of dam experts tasked with determining what went wrong released its final report. It describes the physical factors that caused the spillways to crumble, problems like unstable rock foundations and cracked concrete that allowed water beneath the main spillway.

The report also highlighted human and organizational errors, including faulty design details, shortsighted inspections and “overconfident and complacent” management by the California Department of Water Resources. The department “take(s) the findings very seriously,” said then-director Grant Davis in a statement. “We will … incorporate the lessons learned going forward.”

So what can Western dam owners and regulators learn from Oroville? One lesson, according to the report, is simply to pay more attention to the dangers of deteriorating spillways, which can be overlooked during dam-centric safety assessments. Dam failures are clearly catastrophic, but other emergencies — like a spillway collapse — can also be dangerous and expensive.

Another lesson is the need for inspections that go beyond mere physical checkups. For example, reviews of original design records are necessary to help inspectors determine whether spillways are too outdated to be safe. And those reviews should be independent, not cut-and-paste insertions from previous reports. That could help prevent errors from propagating, an issue at Oroville that led officials to underestimate the risks of spillway erosion.

Oroville’s spillways failed despite state oversight, regulation by a federal agency and repeated evaluations by outside inspectors. That, the report notes, “is a wake-up call for everyone involved in dam safety.”

Hover on the numbers on the photo below to see some of the report’s conclusions.

Emily Benson is an editorial fellow at NewTowncarShare News.

NewTowncarShare News Classifieds
  • Position Summary: Western Resource Advocates (WRA) is seeking a Staff Attorney who is passionate about Western communities and the protection of the natural environment to...
  • Deschutes River Conservancy in Bend, Oregon
  • Position Summary: Western Resource Advocates seeks a passionate Water Policy Analyst with knowledge of western water issues to join our Healthy Rivers Team to strengthen...
  • 9+ acre inholding. Passive solar strawbale off the grid and next to the Continental Divide Trail in ponderosa pine/doug fir forest at 7400.
  • Conservation nonprofit Friends of Cedar Mesa in Bluff, Utah is hiring an Education Center Director to oversee the operation of the Bears Ears Education Center....
  • Friends of the Verde River, Cottonwood, AZ. Apply at https://verderiver.org/employment-opportunities/
  • Verde River Exchange - Friends of the Verde River, Cottonwood, AZ. Apply at https://verderiver.org/employment-opportunities/
  • Teton County Planning & Building is hiring! Our ideal candidate is a team-player, a problem-solver, pays attention to detail, and can clearly communicate technical material...
  • Studio Architects is seeking a full time Architectural drafts-person/project manager with1-3 years of experience to join our firm. At Studio Architects our mission is to...
  • needed for 16,000+ acre conservation property in south central Colorado. Qualified candidate would have experience working on a ranch or wilderness property, general forestry/fire management...
  • Nanny for 18-mnth-old. Yearly salary, vacation, health insurance. Spanish/other foreign-language native spkr prefrrd.
  • Washington Association of Land Trusts seeks an ED to build on WALTs significant success & to lead the association to new levels of achievement. See...
  • Secluded, energy efficient Southwestern home on 40 wooded acres. Broker - Rand Porter - United Country Real Colorado Properties. 970-261-1248, $425K
  • 57 acres in Skull Valley, AZ, 17 miles from Prescott, year-round creek, swimming holes, secluded canyon, hiking/meditation trails, oaks, pines, garden, greenhouse. House, office building,...
  • Title: Public Lands Organizer About the Arizona Wildlife Federation (AWF) The AWF is a non-profit organization dedicated to educating, inspiring, and assisting individuals and organizations...
  • Historic 1893 Ranch Headquarters. 4 Bdrm, 3.5 Ba, 4000 ft2. Remodeled 2002. Includes 2 studio apts, stables, arena, workshop, 5 RV hookups. Chirachua & Peloncillo...
  • The Vice President of Retail Operations will provide overall leadership and accountability for purchasing, product development, merchandising planning, visual merchandising, retail operational excellence, oversight and...
  • Grand Staircase Escalante Partners seeks an experienced fundraiser with excellent communication and organizational skills.
  • position in Phoenix with the Babbitt Center for Land and Water Policy.
  • Vaulted ceilings, two fireplaces, two bedrooms, loft, jetted tub, wifi. Forest, mountain views. Wildlife. [email protected]