Trouble in paradise.

NAPA VALLEY, about an hour and a half's drive from San Francisco, has become known throughout the United States as allegedly the nation's best wine-producing region. It has also become (has worked hard to become, I should say) the kind of place Americans seem to prefer for their holidays. In addition to its natural beauties, and the chance to eat and drink very well at high prices, Napa has started filling the summer with art exhibits, cooking schools, contests, auctions, and concerts, to show that culture is not forgotten.

And yet the hordes of tourists who come to Napa every summer are part of the tangle of problems that are tied up with the valley's attractions, as tourist facilities gobble up scarce land that is, after all, necessary to make the wines that made the valley famous in the first place.

When I first visited Napa some 25 years ago, these problems, if they existed at all, were of little consequence. Napa (the word means "plenty" in the local Indian dialect) was slumbering peacefully. I first stopped at Yountville, largely to have my hair done in the major local beauty parlor. Dutifully, I admired a little six-room hotel furnished with antiques. I thought nothing of the tiny farm town, where Napa's first grape vines had been planted and the first wines had been produced in the early 1800s; I was glad I did not have to drink them.

Today, "progress" has reached Yountville, for better or for worse. American and, especially, Napa wines are fashionable, bringing a whole new set of opportunities and problems, very different from the days when America's idea of a bottle of wine was a half-gallon jug of Hearty Burgundy.

The man who brought Napa to America's attention was Robert Mondavi. I first met him not long after he had broken away from his family's wine-making business. An energetic and enthusiastic man, Mondavi was determined from the start to make better wines than anybody else. Constantly comparing his wines to the great Bordeaux (how well I remember him asking for a Lafite to compare his Cabernet with), he also constantly invested in the newest techniques and machines to improve his wines. Unquestion ably, Monda vi was Napa's most progressive wine-maker in those early days. He also never stopped talking about wines, his own and Napa's. My, how he could talk-and still can.

As Napa's wines became known, so did their place of origin, a beautiful mountainous spot said to resemble certain parts of Tuscany. No wonder Napa attracted many Italians in its early days of wine-making. It was the traditional hospitableness of these winemakers that in turn attracted the tourists, who wanted to see a winery in action and afterward quaff a few free sips of the winery's lesser brews, Nowadays, as I discovered last year to my surprise, a number of the old, established wineries have found it necessary to regulate their flow of visitors by handing out admission tickets, as for any mass event that is free.

But Napa's growing popularity, as with so many things in this life, has proved to be something of a mixed blessing. In the first place, as I mentioned, there is the problem of the tourist facilities: not only do they bid up the price of land, but they force the wine people to divert some of their attention from making wine to preserving the valley's agricultural status for tax purposes.

Secondly, there is the popularity of the wine itself and of wine-making, Since owning a winery and perhaps enough land to grow your own grapes has become an "in" thing to do, a lot of rich people have been moving in. New wineries are established every year (about a dozen in 1979, with the total now more than seven hundred), and many of the new owners are simply amateurs who want to live the Napa dolce vita: they put up the money but don't really interest themselves in the craft of wine-making.

Like the tourist facilities, all these new wineries bid up the price of good grape land. And, since the American public is so fickle in its wine-drinking habits, some wineries that don't have a lot of money have trouble riding out the rough spots. At the same time, the newcomers, wanting to recoup the money they spent on their establishments, raise the price of their wines, making it hard for the consumer to find anything good at a reasonable price.

Finally, as if all the local problems were not enough, the wine-makers are now struggling with the new Prohibitionists in Washington who wish to change wine labels to make them more "informative," or so they say. Napa dwellers less ebullient than Robert Mondavi must be wondering whether fame and fortune were worth the price.