San Francisco may have one of the toughest plastic-bag bans in the United States, but that could be news to the wildlife of Mission Creek.

Save the Bay named Mission Creek as one of the most polluted, plastic-bag-choked waterways in the Bay Area today in its annual "trash hot spots" survey.

The creek, which drains into San Francisco Bay near AT&T Park, at times looks clean enough to swim in. But it's often a receptacle for trash from homeless camps, storm drains and ball games - clogging up with plastic bags and other debris that is most visible at low tide.

"I'm really surprised Mission Creek made the list," said Linda Hunter, director of the Watershed Project, a Bay Area nonprofit that promotes urban creek protection. "This tells us that banning plastic bags isn't enough. We need to use less stuff, have less packaging."

The other creeks on Save the Bay's list are also in cities that have already enacted, or are planning to enact, bans on plastic bags or Styrofoam.

They are Damon Slough in Oakland, Guadalupe River in San Jose, Baxter Creek in Richmond and Pulgas Creek in San Carlos.

Compiling the list

Save the Bay compiles its list based on data provided by Bay Area cities and counties to the San Francisco Regional Water Quality Control Board as part of its storm runoff permit requirements. In addition, Save the Bay conducts its own research on the dirtiest creeks. In all, 225 creeks and waterways made the list.

San Francisco's plastic-bag ban only covers large retailers, like Safeway, but the city's creeks would benefit if the ban went further, said David Lewis, director of Save the Bay.

"This is something all cities should do," he said. "Cleanups are great, but they only have a short-term impact. Strengthening plastic-bag bans is really the way to go."

Supervisor Ross Mirkarimi has proposed legislation to broaden San Francisco's ban, which was the first in the nation when it was enacted in 2007. San Francisco also bans Styrofoam food takeout containers.

San Jose's ban - set to go into effect in January - should be a model for all cities, Lewis said. It prohibits plastic bags from nearly all retailers, "virtually eliminating plastic bags from the environment," he said.

If all the pending bans go into effect, next year's list of messy creeks should look a little different, Lewis said. Mission Creek will, it is hoped, be among the cleanest, or at least have fewer bags tangled in the pickleweed.

Get dirty

The public will have a chance to clean up Mission Creek and the other hot spots Saturday during the annual California Coastal Cleanup Day, which is Saturday.

Last year, volunteers collected more than 172 tons of trash from the Bay Area shoreline, including more than 48,000 plastic bags.

Much of that trash was collected from Damon Slough, historically one of the messiest waterways in the Bay Area and a perennial on Save the Bay's trash list.

But despite the annual cleanup and attention from nonprofits, Damon Slough remains as polluted as ever. Fast-food wrappers, Styrofoam cups, plastic bags and other debris from the nearby Coliseum, flea market and Interstate 880 accumulate in the slough, harming wildlife and creating an eyesore to those walking along the Bay Trail.

"I've been looking at the same grocery basket for the past three or four years," said Rebecca Miller, 36, who works at nearby Zhone Technologies and regularly walks the Bay Trail along Damon Slough. "When the tide is out ... you'll see tires, grocery baskets. ... All the junk sticks out."

The perpetual glut of litter in Damon Slough and other waterways is especially frustrating because litter is the most preventable type of pollution, said Geoff Brosseau, director of the Bay Area Storm Water Management Agencies Association, a nonprofit that works with Bay Area cities and counties on storm water issues.

"It's personal pollution. Unlike pollution that comes from big industries, it's something we all have personal control over," he said. "It's virtually 100 percent preventable."