The operators of a pipeline that leaked crude oil onto California beaches have agreed to plead guilty to environmental pollution charges and pay $13 million, these companies said Friday. 

A Texas company operating the pipeline of Huntington Beach, Amplify Energy, and two of its subsidiaries -- Beta Operating Co. and San Pedro Bay Pipeline Co. -- said they would admit to allowing oil to foul the waters off southern California in October last year. 

They will pay a $7.1 million fine and $5.8 million in restitution to federal agencies that helped clean up 25,000 gallons of crude oil that leaked from their pipeline as part of plea agreements reached in federal court.

South of Los Angeles, between Huntington Beach and Laguna Beach - a stretch of coast that is popular with surfers and serves as a dolphin habitat - 18 miles (24 kilometers) of coast were blackened by the spill. Underwater inspections disclosed that a major segment of the pipeline has been displaced and revealed a rupture in the pipe. 

Given that the area is frequently crowded with cargo ships waiting to reach the big ports of Los Angeles and Long Beach, investigators stated last year that they feared the damage may have been caused by the anchor of a ship. Amplify's President and CEO, Martyn Willsher, stated that the business had "cooperatively" worked to fix the issue as soon as it was identified.

Read more: Confusion Spirals: California Pipeline Might Have Leaked for Hours

"We believe this resolution, which is subject to court review and approval, reflects the commitments we made immediately following the incident to impacted parties and is in the best interest of Amplify and its stakeholders."

"We are committed to safely operating in a way that ensures the protection of the environment and the surrounding communities."

Amplify has also promised to upgrade the pipeline's leak detection system and improve inspections there. "This oil spill affected numerous people, businesses and organizations who use the Southern California coastal waters," Acting US Attorney Stephanie Christensen said. 

"The companies involved are now accepting their responsibility for criminal conduct and are required to make significant improvements that will help prevent future oil spills."

The October accident sparked a new round of discussion about oil platforms that are only a few miles from the heavily populated southern California coastline. A total of 23 oil and gas platforms operate in federal waters just off the coast.