Rohnert Park councilmembers will be asked Tuesday night to endorse a countywide ban on plastic bags, a step some had previously expressed doubts about.

The proposed ordinance has been discussed since early 2011 and is intended to reduce trash sent to landfills and the reliance on oil-based products such as plastic shopping bags.

The Sonoma County Waste Management Agency had sought a uniform county law, saying that would ensure consistency. But roadblocks arose as cities -#8212; most vocally Santa Rosa but also Rohnert Park and Petaluma -#8212; voiced concerns about turning over authority to another jurisdiction.

"My concern was that the city loses control," said Rohnert Park Mayor Joe Callinan.

Under pressure, the waste agency board -#8212; made up of a representative from each city -#8212; crafted an amendment allowing cities to opt out of the ban as well as to create their own ordinance if they chose to. That change has so far smoothed the way by preserving the cities' autonomy.

"It's not perfect but I think it keeps us all on the same page," said Susan Harvey, a Cotati councilwoman who chairs the waste agency board and has long been a strong supporter of the bag ban.

All the county's cities but Santa Rosa and Rohnert Park have voted in support of the law. Santa Rosa and Rohnert Park take it up Tuesday night.

Tuesday night's decision is "absolutely essential," said Henry Mikus, the agency's executive director. "To enact a new program, we have to have a unanimous vote."

If a city simply opts out, the ordinance can move forward. But if a city rejects the ban, it cannot take effect.

No city has yet opted out. In Rohnert Park, city staff have recommended that the council support the proposed ordinance. City officials appear to favor the county ban.

Callinan said he was "pretty much convinced" that the city was better off letting the county handle the ban on plastic bags, but he wanted to see its presentation. Vice-Mayor Amy Ahanotu said he has some questions about how exceptions to the ban are defined, but that "it is moving in the right direction."

Mikus said he is encouraged going into Tuesday night's Rohnert Park meeting, which precedes the waste agency's own Wednesday morning public hearing on the proposed ordinance.

"A big first step is when you have people who are working there, your board member and the city manager, say it's a good idea," Mikus said.

The proposed ban would affect a range of retail outlets, including grocery, clothing, electronics vendors, hardware and drug stores, and convenience and liquor stores. It would not apply to bags that hold meat or produce, or to restaurants, stand-alone delis or charities.

Retailers would have to provide paper bags of at least 40 percent recycled content, charging customers who wanted them 10 cents per bag. Fines could be levied against businesses that don't comply, though few expect that to be necessary.

"There's not been any place that our staff has been able to find that they actually had to penalize anyone," Harvey said.