(Wine-Spectator) - Three million visitors come to Napa every year to enjoy great wine, food and gorgeous scenery. But some vintners are worried a casino may join the landscape, and the issue has created a bitter legal and public relations battle.

A group of Native Americans, the Mishewal Wappo Tribe of Alexander Valley, filed a federal lawsuit in 2009 asking for recognition of their tribal status. The group's 350 members, most of whom live in Sonoma County today, say they are descendants of the Wappo people, who once inhabited parts of Sonoma, Lake County and much of Napa Valley, and that they were unfairly stripped of tribal status. Tribal leaders insist they simply want recognition. But winemakers worry such status would allow the tribe to petition for lands and eventually build a casino in Napa County.

The case's roots date back to federal policies in the late 1940s and 1950s designed to dissolve tribes and assimilate Native Americans as U.S. citizens. Those policies have had repercussions since as tribes have appealed to regain their status.

The Wappo tribe was dissolved as part of the California Rancheria Act of 1958, which called for the distribution of communal lands to individual tribe members. Before the land could be distributed, a government survey had to be performed on the Wappo property. According to tribal leadership, because members lived on the land seasonally, the federal survey only made contact with two people on the land, both of whom voted to dissolve the tribe. The land was divided and given to those two. Both later sold the property.

After years of exploring ways to regain tribal status, the Mishewal Wappo filed their suit seeking federal recognition five years ago. The case has dragged through the courts since.

Tribal recognition isn't what's scaring vintners—it's what might come next. If the tribe wins, it would become a sovereign nation, and any lands they were granted by the federal government or that they purchased would be exempt from local land-use and zoning restrictions. Motions to dismiss the Wappo's claim have been denied. Last July a federal judge affirmed a ruling that Napa and Sonoma counties had no standing to fight recognition of the tribe, escalating widespread apprehension that a casino could find a home in Napa’s agricultural region.

In 1968, the Napa Valley Agricultural Preserve was established to protect the land in Napa Valley. Its basic tenant: Agriculture is the highest and best use of the land. The preserve covers 23,000 acres of agricultural land stretching from Napa to Calistoga. Over the years, the preserve has expanded in several areas, but no land has ever been removed or rezoned for a non-agricultural use.

“The industry is rooted in the land,” said Rex Stults, government relations director for the Napa Valley Vintners association. “The foundation of our success is in the ag preserve. It was troubling to hear that land could be given up in one fell swoop.”

Tribal leaders say there are no plans yet for developing any land they gain. But in recent years, when a tribe acquires land, a casino follows. There are now more than 60 Native American-owned casinos in California. Sonoma’s Graton Rancheria tribe opened the latest the past November, after achieving recognition in 2000 and acquiring 254 acres in Rohnert Park.

“We’re an environmentally conscious community,” said vintner Janet Viader of Viader Vineyards. “[A casino] would destroy everything that we’ve been trying to protect in Napa Valley.”

A source close to tribal leadership believes the story has been blown out of proportion and that there is a misguided fixation on a casino. “[Napa officials] made it clear that land conservation was their biggest issue, and I guaranteed to let them know what my intentions were,” he told Wine Spectator. He added that during earlier talks with county officials, before the suit was filed, the tribe agreed to not buy land in Napa for 10 years and to follow whatever rules the county desired. “They wanted 40 years, so we didn’t settle.”