SANTA MONICA, Calif.–Santa Monica joined Long Beach and unincorporated areas of Los Angeles County in adopting a ban on single-use plastic bags at grocery stores, a measure designed to encourage shoppers to provide their own reusable bags.

The Santa Monica City Council approved the bag ban in January and the law technically took effect in March, but enforcement began Sept. 1.

The ordinance applies to grocery stores, convenience stores, mini-marts, liquor stores, drug stores and pharmacies. Shoppers who don’t bring reusable bags can purchase paper bags, which must be made of at least 40 percent recycled material, for 10 cents each.

“I look forward to the day when plastic bags stop swirling around our feet in the waves, and no longer mar our beaches or kill marine life,” said Assemblywoman Julia Brownley, D-Santa Monica, who is pushing for a statewide ban on plastic grocery bags. Californians throw away about 16 billion plastic bags a year, she said.

Plastic bags wind up in rivers, lakes, parks and the ocean, where they entangle marine life or are mistaken for food and consumed, studies have found.

Earlier this year, a study by scientists at the Scripps Institute of Oceanography at UC San Diego found plastic in nearly one in 10 small fish collected in the Pacific Ocean and estimated that fish are ingesting as much as 24,000 tons of plastic annually.

The study raised concerns that plastic pollution may be climbing the food chain into seafood consumed by humans.