During the go-go years, was this not an American idyll, where newly minted dot-com gazillionaires could buy their piece of paradise in the hills of Napa Valley, oh, say, for $100,000 an acre, plant fields of cabernet and sell those inky dark cult wines from their vanity vineyards for $100 a bottle?

It was so, once upon a time, when the Nasdaq composite index crested 5,000.

But after a decade of explosive growth, the California wine industry is as flat as last night's champagne. And now this: The winemakers are under assault from environmentalists, who have begun to disparage their trellised fields as sterile "alcohol farms" and accuse the growers of "graping the land."

A few radicals have even compared the vintners to "merchants of death," as if a tasty ripe Syrah with blackberry notes and flavors of sweet toast were akin to a pack of Camels or a Mac-10 pistol.

The environmentalists have targeted lovely and touristy Napa, where a chapter of the usually staid Sierra Club is raising Cain -- through lawsuits and ballot initiatives -- to stop winemakers from clearing trees and planting vineyards along the valley's steep hillsides and rocky streams, activities they allege foul the drinking water and threaten steelhead trout, spotted owls and a creature called the vernal pool fairy shrimp.

The vintners' defense was not helped when, during a December storm, a boutique vineyard built on a steep hillside slid down the mountain and its topsoil spilled into Friesen Lakes, a source of municipal drinking water for about 1,500 residents of the Napa town of Angwin.

It was the third time a vineyard fouled a reservoir here.

In part, the vintners are victims of their success. In the 1990s, California farmers added 240,000 new acres of grapes, a leap of more than 70 percent. Sonoma added 22,713 acres. Napa put on 7,301 more. The number of California labels also increased from 600 to more than 9,000, fueled by smaller boutique vintners, the Mister Bigs who cashed out of Wall Street and Silicon Valley to find their place in the sun.

Now, the California wine industry is being squeezed by a weak economy, a grape glut and plenty of competition from less expensive imports. "There is major discounting," said John DeLuca, president of the Wine Institute, an advocacy association of California vintners. "Bottles that were once $60 are now $30, and a bottle that used to cost $25 is now $15."

But in premier growing regions such as Napa, many vintners say they can weather the economic cycle. What really rankles the wine growers is the assertion that their grapevines are not welcome, and that the growers, who consider themselves people of taste and sophistication, are no better than strip-mall developers in the eyes of the environmentalists.

"Yes, we have some problems. Yes, we need to work the land reasonably, which I argue that we have," said Stuart Smith, the founder of Smith-Madrone Winery. "But this is not an environmental crisis and if these people are not careful, they will cripple this industry."

Volker Eisele, who came in the 1970s and creates his own complex cabernet on the family's organic farm, has watched Napa change for better and worse over the years.

"This is where you could buy a rare and wonderful dream," Eisele said. Napa was catnip to the boomers in the 1990s, a land of fresh truffles flown into the Sunshine Market and a Land Rover's commute from the San Francisco opera house. A place one could "go back to the land," but not get dirty. Fabulous parties of food-wine "pairings." And best of all, your name on the label of a killer cab.

"But a lot of people forgot that this is a business, too," Eisele said.

The growth of small vineyards was propelled by semi-retired, newly pastoral power couples fresh from the corporate boardrooms, who spared no expense buying land, building chalets, hiring vineyard managers and winemakers, and producing the explosive big cabernets as dark as motor oil that are favored by many connoisseurs and tastemakers such as wine critics Robert Parker and James Laube.

Previously, most of the grapes from Napa were grown on the valley floor. But beginning in the late 1980s, vineyards began to pock the steep hillsides, which also happen to produce the kind of intense grape that can become a cult wine.

But there are problems with hillsides. They are often covered by forests that must be chopped down to plant grapes. And they can be unstable.

"They believe that wine is the nectar of the gods and that no one should stand in their way," said Peter Mennen, the former postmaster here, who woke up one day and found out that he had not been disowned, as he thought, but had inherited millions from a fortune built by his family upon the sale of deodorants and after-shaves.

Before he inherited his money, Mennen might have been just another Napa Valley character, a mailman who worked with a parrot named Ricki Lake perched on his shoulder. But that was before he created the Mennen Environmental Foundation, which has funded the work of Chris Malan, a physical therapist and a leader of the local group of the Sierra Club.

"There is just this arrogance," Malan said. "They're saying, 'I'm rich and I'm right, and I want a vineyard in the forest.' They say these hills are made for grapes, and if you don't like it, you can get the hell out of here."

The Sierra Club successfully sued the Napa County Board of Supervisors and five vintners, arguing that the local government was not enforcing its ordinances requiring prudence and oversight of the proliferating vineyards that began appearing on the steeper hillsides.

These struggles about how to preserve the unique agriculture and environment of Napa against the press of wealth and development are being closely watched as a test case and possible model. They are also the subject of James Conaway's "The Far Side of Eden," a well-received book about the challenges facing Napa.

Now, the Sierra Club is prepared to launch another lawsuit to further tighten environmental controls. The activists also have gotten an initiative on the 2004 ballot that would greatly restrict cutting down trees to plant vineyards and would also require more protection for streams and the Napa River. Some vintners say the so-called streamside setbacks could ruin them.

"If it passes, you might as well close down the shop," said Eisele, who fears the environmentalists are going too far.

For their part, the vintners have accused the environmentalists of extremism, and they warn, ominously, that if the agricultural traditions are assaulted, this whole place could convert to tract housing. They also complain that they are already the most heavily regulated agricultural entity in the nation.

Jack Cakebread, a former auto mechanic who founded Cakebread Cellars, came to Napa in 1973, when valley floor land cost $800 an acre and his first bottle of cabernet retailed for $3. Three decades later, vineyards are selling for more than $100,000 an acre, and Cakebread's reserve wines sell for almost $100 a bottle. He foresees the day, not too far off, when land will go for $1 million an acre.

"People come to me and say, 'Jack, we're scared,' " Cakebread said. Meaning: Can all this be sustained? The bottle prices? The pretty valley? The river and fish and forests? "If we're very careful," Cakebread said. "But there has to be a balance, ecologically but also economically. If we don't figure it out, we won't be here."

Special correspondent Kimberly Edds contributed to this report from Los Angeles.

Shafer Vineyards winemaker Elias Fernandez of Napa, Calif., walks through a cave where wine is aged in barrels.