Leaders of a group suing to stop the Graton Resort & Casino in Rohnert Park urged Petaluma-area residents Wednesday night to pressure their city leaders to join their legal battle as a means to stop the Dry Creek Rancheria from building a casino on pasture land just south of the city limits.

As the Graton casino plans its Nov. 5 opening, the Stop the Casino 101 Coalition is seeking the support of the Petaluma City Council. The group is appealing a Sonoma County judge's August ruling against their effort to invalidate Graton's contract with the state that allowed the Las Vegas-style casino on the tribe's 254-acre Wilfred Avenue parcel.

In a meeting attended by about two dozen residents, group leaders Chip Worthington and lawyer Bruce Miroglio urged Petalumans to attend Monday night's council meeting, where the council is set to discuss legal matters with the city attorney in a closed session before the regular meeting.

Closed-session discussions are secret, but if the council takes action — to join the coalition's lawsuit or initiate its own — it must be announced publicly. The closed-session agenda begins at 6 p.m.

"The best way to stop Dry Creek in Petaluma is to stop Graton," Miroglio said. "When you start getting cities involved it adds a certain gravitas."

Graton Resort & Casino is set to open next month as the Bay Area's largest gambling hall, with more than 2,000 employees and 3,000 slot machines. The casino likely will siphon off millions of dollars from Dry Creek's River Rock casino farther north in Geyserville.

Dry Creek also owns 277 acres east of Highway 101 near Kastania Road south of Petaluma and is seeking to have the land taken into federal trust — a necessary step before a casino can be built.

Tribal chairman Harvey Hopkins has said development plans for the land don't include a casino, but Petaluma and county leaders are wary, fearing the Dry Creek Rancheria could eventually use the land as a means to leap-frog the Graton Resort & Casino and capture Bay Area customers.

The City Council in August unanimously signed a letter to the area's federal representatives urging them to oppose the tribe's request to take the land into trust.

"The only way, I submit, we're going to stop this action (a Petaluma-area casino) is to stop Graton," Miroglio said. "That's the focus."

"The battle is not over," Worthington said.

You can reach Staff Writer Lori A. Carter at 762-7297 or lori.carter@pressdemocrat.com.