The Texas company operating the pipeline that caused a massive oil spill in the waters off Huntington Beach agreed to plead no contest to state environmental charges and pay $4.9 million in fines and penalties, prosecutors announced Thursday.

Orange County and state prosecutors this week charged Houston-based Amplify Energy Corp. and two subsidiaries — Beta Operating Co. and San Pedro Bay Pipeline Co. — with misdemeanor counts of pollution and failing to immediately report last fall’s discharge of oil into state waters to the Office of Emergency Services.

The firms were also charged with four misdemeanor counts for the deaths of two brown pelicans, which are protected birds, and two migratory nongame birds — a western grebe and a Brandt’s cormorant, according to a criminal complaint filed in Orange County Superior Court.

The plea agreement still needs to be approved by a judge. Officials expect Judge Larry Yellin to consider it at a hearing Friday.

California Atty. Gen. Rob Bonta said that the plea deal reached with the company is believed to be the largest state misdemeanor criminal fine in Orange County history. About $3.45 million will go to the state and the rest will go to the county.

“While the exact cost of the spill is still unknown, today’s announcement marks an important step toward accountability,” Bonta said at a news conference Thursday in Santa Ana.

Under the agreement with prosecutors, Amplify Energy will be placed on a yearlong probation and will be required to install a new leak detection system in the pipeline. The company must also train employees to immediately notify regulators of potential spills and conduct other operational safety measures, including biannual visual inspections of the pipeline, Bonta said.

Amplify President and Chief Executive Martyn Willsher said in a prepared statement that the agreement “further reflects the commitments we made immediately following the incident.”

Amplify has worked “diligently” to help address the aftermath of the spill, including sending more than 1,800 contractors to assist with cleanup and environmental remediation and paying “covered claims as expeditiously as possible,” Willsher said.

The news comes nearly two weeks after Amplify Energy and its subsidiaries agreed to plead guilty to federal environmental charges and pay nearly $13 million in connection with the oil spill, which sent at least 25,000 gallons of crude into the ocean in a 14-hour period early last October.

Despite hours of signals that their 17.3-mile oil pipeline may have been leaking, the companies continued to negligently pump crude oil into the waters off Huntington Beach, according to prosecutors.

“Amplify unequivocally hit the snooze button,” said Orange County Dist. Atty. Todd Spitzer. “They knew they had a leak. Their leak detection system detected a leak and shut down the pipeline. They started it up again, and there were seven more instances where the alarm notified them that there was a leak. Over and over again, they kept ignoring it.”

The underwater pipeline, which runs between a production and processing platform and the Port of Long Beach, was being operated by “an understaffed and fatigued crew” that “had not been provided sufficient training regarding the pipeline’s automated leak detection system,” according to a federal indictment filed in December.

The oil spill required significant cleanup, disrupted activity along the coast for weeks and forced the cancellation of the Pacific Airshow in Huntington Beach, one of the city’s most popular annual events.

“It’s great that the prosecution of violations of the Clean Water Act is resulting in better enforcement and environmental protections for our beautiful coast,” Orange County Supervisor Katrina Foley said. “But we can’t just let it go. We have to make sure those pipelines are remediated and removed.”

Last month, Amplify also tentatively agreed to settle more than a dozen lawsuits brought by business owners and residents who say they were financially affected by the spill. The terms of the settlement have not been disclosed.

Willsher has said that the firm is still pursuing a lawsuit against the companies that own and operate two container ships that have been accused of dragging their anchors across the sea floor and damaging the pipeline months before the spill.

Times staff writer Laura J. Nelson contributed to this report.