LOS ANGELES – Los Angeles became the largest city in the nation Wednesday to adopt a ban on plastic bags at supermarket checkout lines, handing a major victory to clean-water advocates who sought to reduce the amount of trash clogging landfills, the region’s waterways and the ocean.

Egged on by actress Julia Louis-Dreyfus and an array of environmental groups, the Los Angeles City Council voted 13-1 to phase out plastic bags over the next 12 months at an estimated 7,500 stores. Councilman Bernard Parks cast the lone no vote.

“Let’s get the message to Sacramento that it’s time to go statewide,” said Councilman Ed Reyes, who has focused on efforts to revitalize the Los Angeles River.

Council members quietly backed away from a more controversial plan to also ban use of paper grocery bags, which was first proposed by appointees of Mayor Antonio Villaraigosa.

Wednesday’s vote kicks off a four-month environmental review of the bag ban, followed by passage of an ordinance putting it into effect. Larger stores would then have six months to phase out plastic bags and smaller markets a 12-month phase-out period. For paper bags, retailers would be required to charge 10 cents per bag starting one year after the plastic bag ban is enacted.

Councilman Paul Koretz, who pushed for the ban, said city officials would conduct a study in two years to determine whether the prohibition should be expanded to include paper. “My hope is that so few paper bags will be used as a result of this measure that the formal ban … on paper bags may not even be necessary,” he said.

The plan drew strong praise from environmental activists, who had long argued that L.A. needed to follow in the footsteps of San Jose, San Francisco, Long Beach and dozens of other municipalities in the state.

“Plastic harms our environment. It is a threat to the coastal economy. It is a danger to marine life and it is an unconscionable burden to taxpayers who have to foot the bill for cleanups year after year,” said attorney H. David Nahai.

Employees of plastic bag manufacturers, wearing T-shirts reading “Don’t Kill My Job,” pleaded unsuccessfully for council members to change course, saying they feared they would soon be unemployed. “My family depends on my job and my benefits, too,” said Alejandro Ortega, a 10-year employee of manufacturer Crown Poly.

Environmentalists had tried unsuccessfully for four years to get the plastic bag ban through the council. But the proposal languished in a committee that handled environmental matters. In the meantime, dozens of other cities and counties up and down the state adopted similar bans.

Villaraigosa’s appointees on the five-member Board of Public Works voted last year to embrace a ban on all single-use bags, saying that paper bags lead to deforestation. But some environmentalists said they were not troubled by the council’s decision to back away from the paper bag ban.

Los Angeles County’s 10-cent fee on paper bags has led to a 94 percent reduction in the use of those bags, said Jennie R. Romer, the founder of www.plasticbaglaws.org.

“There are times every once in a while when there is a need for a paper bag, so having that option is great,” said Romer, who has advised cities throughout California on bag laws.