The Wahluke Slope could define the phrase, "Emerging viticultural region."

It's not home to dozens of modern tasting rooms, restaurants or plush bed-and-breakfasts - not yet.

The appellation has just two wineries and one hard-to-find tasting room at Fox Estate Winery in Mattawa.

But it does have 81,000 acres of land, with nearly 5,200 acres of vineyards, which is nearly 20 percent of the state total. Top winemakers discovered the area's potential for rich-flavored fruit long ago and are liberally pouring the region's grapes into many of Washington's most acclaimed wines.

Col Solare, Northstar, L'Ecole, Fidélitas, Snoqualmie, Chateau Ste. Michelle's Indian Wells wines and K Vintners are just a few that contain Wahluke fruit.

Few bottles sport Wahluke Slope designations, but wine grape growers hope that will change soon because the area was approved in early 2006 as an American Viticultural Area.

In the wine business, a regional designation can mean big money.

Consumers often use appellations to distinguish between superb and less-blessed vineyards.

Charlie Hoppes, winemaker and owner of Fidélitas Winery on Red Mountain, said he's made wine with Wahluke Slope fruit since the early 1980s, though few of his customers have ever seen the region.

"It's so remote, it's not on the way to any place," he said.

Hoppes uses nearly 25 percent Wahluke fruit in his popular Fidélitas blends.

Rob Griffin, owner of Barnard Griffin Winery in Richland, Wash., said his award-winning reds couldn't do without Wahluke Merlot and Cabernet.

Griffin said Wahluke vineyards produce red wines with big fruit, deep body and loads of varietal character.

"It's a warmer site, it has nice air drainage, and the soils are properly crummy," he said. "For my Merlot in particular, Wahluke fruit is the key," he said.

The dry area allows grape growers to control the vigor of the vines, and the warm slope allows red wines to become fully mature, he said.

Griffin drives through the desolate patch of highway between Richland and Wahluke more than twice a week during harvest. It's critical to harvest the grapes when they aren't overly ripe or with underdeveloped tannins, he said.

The Wahluke Slope is an immense gravel and silt bench left by the great Ice Age floods some 15,000 years ago. On a recent visit, area growers explained how the ancient land form has diverse soils and altitudes that influence temperatures and how grapes ripen.

The Wahluke Slope's soils change dramatically from coarse gravel and large erratic boulders near the Columbia River in the west to talcumlike dust farther up the slope.

"We would have been about 600 to 800 feet under water at this point during the height of the outburst floods," said Alan Busacca, a soil scientist and Ice Age Floods expert during a recent visit to the Wahluke Slope. "(It's) an unimaginable amount of water."

Busacca explained that when massive amounts of water rocketed through the confined channel of Sentinel Gap, they had tremendous power and carried loads of sand and boulders.

But as the water spread out again, the large boulders and sands settled out of the flood waters.

Now, hundreds of boulders line Highway 243, where farmers have made room to plant grapes.

"They give us a real clue as to the power that shaped these landscapes," Busacca said.

Growers have planted mostly Merlot, Syrah, Cabernet Sauvignon, Riesling and Chardonnay.

Grapes near the west end are some of the state's earliest ripening, while those to the east - just 13 miles away - often are among the last to be picked.

Sometimes, growers leave fruit to hang on the vines until early November.

Kent Waliser, general manager of Sagemoor, Bacchus, Dionysus and Weinbau vineyards, said many Wahluke growers planted grapes because they were looking for something more profitable than apples.

Later, others saw the success of that idea and started planting vines, too.

Now, growers are trying to develop their identity as a grape-growing region.

Despite roots as farmers, many Wahluke vineyard owners say they hope to build their own wineries, though probably in more established and popular wine tourism areas such as Prosser, the Tri-Cities, Red Mountain, Wenatchee, Leavenworth or Woodinville.

Butch and Jerry Milbrandt, owners of Milbrandt Vineyards, recently built a winemaking facility near Mattawa and plan to open a tasting room in the Prosser Business Park.

"We chose the Prosser site because it's already a destination," Jerry Milbrandt said. "But in five years, we could certainly have a tasting room here."

For those who like to mix a bit of adventure with their wine tasting, the Wahluke Slope already has a lot to offer. The quiet place isn't overrun with busloads of visitors and jam-packed tasting rooms.

The trellis-covered slope is hemmed in by rugged hills, expansive desert and the great, meandering Columbia River. Native song birds flit among the vines, a steady breeze buffets the sandy landscape, and there are few buildings to mar the pastoral view.

Visitors here have ample opportunities to see vines and well-known grape growers up close. Two small bergs - Mattawa and Desert Aire - offer intrepid tourists a brief repose for a soda, ice cream bar and tank of gas.

Several local Mexican restaurants cater to the hundreds of seasonal farm workers who harvest the area's fruit-laden branches and vines. And venturing off the printed menu is a good bet for those seeking some authentic dishes.

Hikers can explore the nearby Hanford Reach National Monument, which is particularly spectacular when desert wildflowers bloom in the spring. Or visitors can enjoy a leisurely picnic and a dip in the Columbia during the summer months.

But the agrarian wine touring experience may only be available to those who visit soon. Eastern Washington towns such as Walla Walla, Prosser and Wenatchee are rapidly shedding their rustic image for sleek shops, hotels and Seattle-priced restaurants.

Jerry Fox, owner of Fox Estate Winery and one of the pioneering growers in the Wahluke Slope, said he envisions the area chock full of metropolitan wineries soon.

He's seen a lot of change in the remote area since he planted his first grapes in 1978 - more cars pass along the highway and his winery's annual BratFest drew more than 350 people last year.

Perhaps the Wahluke Slope isn't a tourist mecca yet, but the region's scenic landscape, unique growing conditions and flavorful grapes are sure to lure more visitors soon.

"The grapes love it. They think it's the best place to be," Fox said.

Quick facts about the Wahluke Slope

- Established in 2006, the Wahluke Slope is one of Washington's newest appellations.

- Naturally bounded by the Columbia River to the west and south, by the Saddle Mountains on the north, and by the Hanford Reach National Monument on the east.

- The Wahluke Slope appellation is within the established Columbia Valley appellation and is home to more than 20 vineyards.

- The 81,000-acre region has about 5,200 acres of vineyards, or nearly 20 percent of the total wine grape acreage in the state.

- The appellation's top grape varieties include Merlot, Syrah, Cabernet Sauvignon, Riesling and Chardonnay.

- Wahluke Slope has one of the driest and warmest climates in the state, which gives growers nearly complete control of their vines.

(Source: Washington Wine Commission)

ANNA KING is a regular contributor to Wine Press Northwest.