As a part of a new law California legislators passed, the state must cut back on organic waste in landfills by 75 percent, or 17.3 million tons, by 2025.

Instead of landfills, the food waste will either be used for composting or will be converted through anaerobic digestion into biogas, an energy source that, like natural gas, can be used for heating and electricity.

According to the U.S. Department of Agriculture, about 40 percent of food in the U.S. is wasted. Food sitting in landfills emits methane, a damaging greenhouse gas. Organic waste like food makes up a fifth of California’s methane emissions, CalRecycle said.

The new measure also aims to donate 20 percent of food that would otherwise have gone to landfills to people in need by 2025. It will require supermarkets to start giving their excess food by January, and other public places serving food such as schools, restaurants and hospitals to begin by 2024.

Rachel Wagoner, director of the California Department of Resources Recycling and Recovery, called the new law “the biggest change to trash since recycling started in the 1980s.”

“(It) is the single easiest and fastest thing that every single person can do to affect climate change.”

A handful of states and nations, including France, have passed laws requiring grocery stores and other large businesses to recycle or donate excess food to charities, but California’s program targets households and businesses.

Starting in January, all cities and counties that provide trash services are supposed to have food recycling programs in place and grocery stores must donate edible food that otherwise would be thrown away to food banks or similar organizations.

“There’s just no reason to stick this material in a landfill, it just happens to be cheap and easy to do so,” said Ned Spang, faculty lead for the Food Loss and Waste Collaborative at the University of California, Davis.

Vermont, home to 625,000 people compared to California’s nearly 40 million, is the only other state that bans residents from throwing their food waste in the trash. Under a law that took effect in July 2020, residents can compost the waste in their yards, opt for curbside pick up or drop it at waste stations. Cities like Seattle and San Francisco have similar programs.

Most local governments will allow homeowners and apartment dwellers to dump excess food into yard waste bins, with some providing countertop containers to hold the scraps for a few days before taking it outside. Some areas can get exemptions for parts of the law, like rural locations where bears rummage through trash cans.

The donation part of California’s law will contribute toward a federal goal of cutting food waste in half by 2030.

Davis is among California cities that already have a mandatory food recycling program. Joy Klineberg, a mother of three, puts coffee grounds, fruit rinds and cooking scraps into a metal bin labeled “compost” on her countertop. When preparing dinners, she empties excess food from the cutting board into the bin.

Every few days, she dumps the contents into her green waste bin outside that is picked up and sent to a county facility. Unpleasant countertop bin smells haven’t been a problem, she said.

“All you’re changing is where you’re throwing things, it’s just another bin,” she said. “It’s really easy, and it’s amazing how much less trash you have.”

Implementing similar programs in bigger cities is more challenging.

The state’s two most populous — Los Angeles and San Diego, which together account for about one of every eight Californians — are among cities that won’t have their programs ready for all households next month.

That’s because it takes time to buy the necessary equipment, like green waste bins for homes that don’t already have them for yard waste and to set up facilities to take the material. Trash collection fees will go up in many places.

Like Davis, CalRecycle wants to focus more on education and less on punishment. Governments can avoid penalties by self-reporting to the state by March if they don’t have programs in place and outlining plans for starting them. Cities that refuse to comply could eventually be fined up to $10,000 per day.

Ken Prue, deputy director of San Diego’s environmental services department, said the city put nearly $9 million in this year’s budget to buy more waste bins, kitchen top containers and trucks to haul the additional waste.

Prue hopes San Diego residents will quickly realize the importance of recycling food waste after the program starts next summer.

“Hopefully before they know it, it becomes second nature,” he said.

The Associated Press contributed to this report.