SAN MARCOS - Opponents of Palomar Station, a controversial mixed-use project approved by the City Council on Tuesday night, say they have begun preparing for a ballot referendum campaign to overturn the council's decision.

Opponents said Wednesday that they hope to gather enough signatures to give San Marcos voters a chance to reject the project, which would feature 333 condos built above dozens of ground-level shops and restaurants.

The opponents argue the project is "immoral" because a city analysis concludes that the roughly 1,000 condo residents in Palomar Station could be subject to potentially significant cancer risks from air toxins emitted by nearby industrial businesses.

But a representative for the developer has said that the risk would be minimal because the city's analysis was based on an unlikely worst-case scenario.

Three members of the council expressed reservations Tuesday night about the health risks, but the project was eventually approved 4-1, with Councilman Mike Preston casting the lone vote against it.

If at least 10 percent of the city's 30,414 registered voters sign a petition seeking a referendum by Aug. 23, the council would have to overturn its approval of the project or present Palomar Station to local voters in an upcoming election, according to City Clerk Susie Vasquez.

The deadline would be Aug. 23 because that is 30 days after July 24, the date the council is slated to approve a second reading of two ordinances associated with the project.

Cynthia Skovgard, a local chiropractor who has spearheaded the opponents' campaign, said she's confident that enough volunteers will gather signatures this summer.

"People are just totally shocked that the City Council approved it," said Skovgard. "They didn't seem to understand the health risks that come with placing residents in an industrial zone."

Jason Simmons, who represents the project's developer, said Wednesday that a referendum campaign would be a mistake.

"They certainly have talked about a referendum, and that's their right," said Simmons. "But we would urge them not to take that step because of the strong merits of the project and the obvious misconceptions their opposition is based on."

Potential health risks to Palomar Station residents have been the main focus of the opposition.

The city's analysis assumed that a film manufacturing company next to the project would emit the maximum allowable amount of methylene chloride, and that residents would live in a condo for 30 years and spend 24 hours per day outdoors on their patio.

Supporters of the project have said such a worst-case scenario is highly unlikely, but Skovgard said that a referendum would allow local voters to decide the issue.

"The more you talk to local residents outside the political world of San Marcos, the more you see they are appalled at this idea," said Skovgard.

Among the opponents are business owners near the project site, which is across Mission Road from Palomar College. They recently hired Escondido attorney Everett Delano, who has helped several other citizens groups in North County fight projects.

"We basically ask voters to say the city did the wrong thing," Delano said Wednesday. "If we do a referendum, the voters get a chance to tell the council, 'You've got to be kidding.' "

Delano said the signature drive will be difficult because of the tight time frame, but he said the subsequent campaign will be even more crucial. "The main hurdle is getting the message to the voters," said Delano.

A similar citizens effort in 2003 successfully overturned the City Council's approval of a Wal-Mart near the city's border with Carlsbad. Opponents gathered the required signatures, and voters defeated the project in March 2004 by 56 percent to 44 percent.

Randy Walton, who led the effort against Wal-Mart, said Wednesday that referendums are very difficult.

"The only way to pull it off is to have a very motivated electorate, and it has to be something people care about citywide" said Walton. "Everyone has opinions about Wal-Mart even if they lived far away from the site, but I'm not sure there is the same public outrage toward this project."

- Contact staff writer David Garrick at (760) 761-4410 or dgarrick@nctimes.com.