An audit of 650 California dams considered hazardous found that only a small fraction have completed emergency plans required after the Oroville Dam spillway collapsed three years ago and forced the evacuation of nearly 200,000 people.

State Auditor Elaine Howle’s recent report says only 22 of the at-risk dams have finalized their plans, which are supposed to include inundation maps and specify what they would do “to minimize loss of life and property.”

Some 250 dam operators haven’t even bothered to submit plans, and there is a major backlog of plans awaiting approval, the report, Assessment of High-Risk Issues, concluded. The deadline for owners of “extremely high hazard” dams to submit emergency plans was Jan. 1, 2018. Owners of “high hazard” dams had until Jan. 1, 2019.

The state regulates more than 1,200 dams and assigns each a hazard rating based on how much harm and damage might result if they failed. A little more than half — 650 — were rated “high or extremely high hazard.”

The state Office of Emergency Services has approved only 5% of the 400 emergency plans it has received, even though the inundation maps were approved by water resources officials. Most were sent back for revisions, the report said.

The audit was also critical of the condition of many of the dams that do not yet have emergency plans. Of the 102 dams that are in “less-than-satisfactory” condition, 84 have been designated a significant hazard, meaning life or property would be at risk if they failed.

“Inadequately maintained dams or those not meeting standards, especially those whose failure could affect large populations, pose significant risks to California residents,” the report stated, using the Oroville Dam spillway collapse as an example. Department of “Water Resources data indicate that a majority of dams within the state with less-than-satisfactory condition ratings are in areas where they pose downstream hazard potential to life or property.”

Cal OES officials said they are committed to holding individual dam owners accountable and have done nothing wrong.

“The report operates on the incorrect premise that Cal OES has a backlog of emergency action plans,” said Brian Ferguson, the spokesman for the Office of Emergency Services. “Under statute, Cal OES has 60 days to review a completed EAP with approved inundation maps, and return it for revisions or approve. There are currently no EAPs under review at Cal OES that have failed to meet that 60-day deadline.”

Erin Mellon, the spokeswoman for the California Department of Water Resources, said significant progress has been made in dam safety since the Oroville incident.

“The Division of Safety of Dams is moving aggressively to reduce risks by inspecting dams and working with dam owners to meet the most rigorous standards in the nation and correct any deficiencies identified on an ongoing basis,” Mellon said in a statement. “In addition, DSOD is updating its inspection protocols to identify previously unknown dam safety risks and work with owners to mitigate those risks.”

Part of the problem, according to experts, is that many small dam owners don’t have the money to do expensive reports, let alone pay tens of thousands of dollars to make repairs.

The auditor noted that “there are no state-level programs that provide financial assistance to dam owners for repairing their dams and resolving deficiencies.”

Fixing the problems will take time and require patience, resources officials said.

The state spent $1.1 billion rebuilding Oroville Dam’s two faulty spillways after heavy rains in February 2017 broke up the main spillway, forcing operators to use an emergency spillway, which poured water over a mostly barren hillside that quickly eroded.

A team of independent engineers blamed the failure on weakened concrete, poor drainage and a history of shoddy maintenance, including a failure to adequately review for problems. The Oroville failure raised concerns about the rest of California’s aging water infrastructure, prompting legislators to require dam operators to prepare the emergency plans.

Since the rebuild, Oroville Dam has moved from unsatisfactory, the worst ranking on the rating scale, to fair, which is the second highest behind satisfactory. It is still considered a “high hazard” dam, and its emergency plan is one of the 22 that have been approved.

Robert Bea, a professor emeritus of engineering and project management systems at UC Berkeley, said there have been major improvements — Oroville is one example — but the auditor’s report just confirms that infrastructure is still a problem

“I am very discouraged at this point,” Bea said. “Unfortunately, the failure to have learned constructively from the previous failures continues at this point. We’ve developed this sickening reactive approach to these failures — once it fails, fix it fast and return to business as usual.”

It’s not a new problem, as Bea points out. There are a total of 1,585 dams in the state, including private dams, and many of them are aging.

A 2017 Chronicle review of federal data found several dam-safety deficiencies in California. At that time, about a dozen state-monitored dams had gone more than two years between inspections, a year longer than it is normal.

And there have been other near failures.

The San Francisco Public Utilities Commission spent almost $22 million in 2018 and 2019 repairing and reinforcing Moccasin Dam in Tuolumne County after a storm sent a torrent of water and debris into the reservoir, raising fears the 60-foot-tall earthen barrier would collapse.

Peter Fimrite is a San Francisco Chronicle staff writer. Email: pfimrite@sfchronicle.com Twitter: @pfimrite