Systemic failures at dam

Photo: The Canadian Press

"Long-term and systemic failures" by California dam managers and regulators to recognize inherent construction and design flaws at the tallest U.S. dam caused last year's near-disaster there, an independent panel of dam safety experts said Friday, calling it a wake-up call for dam operators around the country.

Members of the Association of State Dam Safety Officials and the U.S. Society on Dams carried out an independent investigation into the human and technical problems that caused the crisis at California's Oroville Dam. The experts issued their report Friday.

Both spillways at the half-century-old Oroville Dam gave way in February 2017, forcing evacuation orders for nearly 200,000 people downstream. The feared uncontrolled release of massive amounts of water over the top did not happen, and residents were allowed to return home days later.

The independent panel of safety experts said the dam had been badly built from the start in the 1960s.

The report faults California's Department of Water Resources - which operates the dam - and dam regulators for allegedly failing to recognize and address the problems in the 770-foot (230 metre) structure, over the course of decades of inspections and reviews.

"There were many opportunities to intervene and prevent the incident," the report said.

The experts also said the Oroville crisis made clear that it was essential for dam managers and inspectors to review the original building of dams in the light of modern engineering practices.

"Like many other large dam owners, DWR has been somewhat overconfident and complacent regarding the integrity of its civil infrastructure," the dam experts said.

State spokeswoman Erin Mellon said California officials would respond to the findings shortly.

Dam experts say the Oroville crisis should be a warning for operators and regulators around the world.

"The fact that this incident happened to the owner of the tallest dam in the United States, under regulation of a federal agency, with repeated evaluation by reputable outside consultants, in a state with a leading dam safety regulatory program, is a wake-up call for everyone involved in dam safety," the experts said in Friday's report.

The average age of the United States' more than 90,000 dams is 56 years, making thorough inspections and maintenance increasingly important for the safety of people downstream, dam experts say.