Wal-Mart has begun eliminating disposable shopping bags at its Ukiah store and two others in California, a move that environmentalists hope will spread nationwide and lead to the demise of the bags that are clogging landfills and littering highways and oceans.

"The potential to really drive this across the retailing supply chain is pretty extraordinary," said Michelle Harvey, the Environmental Defense Fund's project manager for corporate partnerships who has been working with Wal-Mart on its green projects.

The giant retailer this month quietly stopped stocking plastic bags in its stores in Ukiah, Citrus Heights and Folsom. The pilot programs will continue through 2010 and determine whether Wal-Mart expands the program to all of its U.S. stores.

The policy already is in place in some of its stores overseas where disposable shopping bags are on the way out.

"We're committed to reducing the plastic bag waste by one-third by the end of 2013. This test could help," said Wal-Mart spokeswoman Amelia Neufeld.

When the bags in the three pilot stores run out, shoppers who don't carry their own shopping bags will have the option of buying one of several reusable Wal—Mart bags, which sell for 15 cents, 50 cents and $1.

That's already the case at some of the Ukiah store's checkstands and the store anticipates phasing the disposable bags out entirely by Oct. 25.

Wal-Mart may seem an unlikely environmental hero, but environmentalists are hoping the powerful retailer's clout will help push disposable plastic shopping bags into oblivion.

The company already has pressured its suppliers to reduce packaging and lessen the amount of mercury in fluorescent lightbulbs, Harvey said.

If Wal-Mart succeeds in convincing shoppers to abandon disposable bags, other stores are likely to follow, she said.

"The ripple effect is just outstanding," Harvey said.

The idea of banning or limiting disposable shopping bags is not new.

About 20 other countries, including China, have banned or curbed the use of disposable plastic bags, Harvey said.

In the United States, IKEA stores have begun charging for disposable bags, effectively reducing their use.

San Francisco has banned disposable plastic shopping bags at large retail and grocery stores. However it allows paper bags, which some argue are as bad or worse than plastic.

Other local governments in Sonoma and Mendocino counties have been leery of mandating restrictions on disposable bags because manufacturers have threatened to sue.

The least expensive reusable bags the super store is now offering for 15 cents are made from polypropylene and can be reused about 75 times.

They're washable and can hold up to 100 pounds, Harvey said. When the bags wear out, they can be returned to Wal—Mart for recycling.

Wal-Mart's goal of reducing its plastic bag waste around the world by 33 percent by 2013 would eliminate 135 million pounds of plastic bag waste and reduce oil consumption by 678,000 barrels of oil every year, Neufeld said.