Tall, stately trunked, full and deep, with russet leaves, the copper beech has a dignity that overshadows its green peers. There are copper beeches in front of Chateau Ste. Michelle in Woodinville, Wash. Like the trees themselves, they give the mansion an air of permanence . . . a deceptive air, for the building is only five years old. The estate on which it is set is just outside Seattle, and belonged to a timber baron back around 1910. Today's mansion is the headquarters and one of the wineries of Chateau Ste. Michelle, Washington State's best known wine producer. What would the "baron" have thought of this new industry, an industry that is becoming as much a part of the Northwest as the forests from which he made his pile?

Some even believe that wine could become more important than wood. The people at Chateau Ste. Michelle forecast that Washington state will provide at least one-quarter of all American wines by the end of this century.

Their confidence is based on the natural advantages of the Columbia Valley, the location of their vineyards. And wine in Washington state really means wine from the confluence of the Columbia, Yakima and Snake rivers. The latitude, on the 46th parallel, provides long midsummer days to help the vines in mid-cycle. Then, near harvest time, the less intense, shorter days and cool nights help to round out the balance of sugar and acidity in the grapes.

The Columbia Valley is in the eastern half of the state, so efficiently protected from the grey and rainy west by the Cascade range that the average annual rainfall amounts to a scant eight inches. However, there is a plentiful supply of water for irrigation and rarely-needed frost protection from the big rivers.

The low rainfall keeps many vineyard insects and diseases at bay, including phylloxera. Further helped by sandy soils, Washington state has never had to worry about the root-eating louse, and vinifera vines are grown on their own roots.

There's another, currently attractive, advantage that is not loudly promoted: land prices. Desirable vineyard land in the Columbia Valley is being sold for one-tenth of prime Napa Valley prices, $3,000 an acre versus $30,000 an acre. Right now, I reckon that that's as good a reason for long-term growth as any.

Chateau Ste. Michelle's reputation here has been made with white wines rather than reds. Admitting early problems controlling high malic acid in the reds, the company is releasing three wines from red grapes, with which it is happier.

The '76 Blanc de Noir, $20, a champagne-method sparkling wine, was a mid-'70s solution to the problem of excessive acidity in the pinot noir. The wine, which is totally pinot noir though it has no hint of a blush, was left on the yeasts of the second fermentation for more than three years. It's assertive and full-flavored, with a dry finish.

The '76 Reserve, Cabernet Sauvignon, Washington State, was bottled in magnums only, $34. It carries a new designation, Chateau Reserve, and a new label design. The wine is ready to drink, having an attractively soft, fruity style, and will be here in August.

The '78 Reserve, Cabernet Sauvignon, Cold Creek Vineyards, $15, will not be released for a few months. With more depth and firmness than the '76, it was the first year in which the winery bottled a single vineyard wine and used small French oak barrels.