YAKIMA — A hilly tract of land on the Columbia River's north slope, affectionately called Horse Heaven Hills, will be the state's seventh federally recognized wine-grape-growing region.

Known as American Viticultural Areas or appellations, such designations recognize a region's distinct climate and soil features.

Wineries and grape growers in the 570,000-acre Horse Heaven Hills submitted an application for recognition in 2002. The U.S. Treasury Department's Alcohol and Tobacco Tax and Trade Bureau approved the appellation request, effective Aug. 1.

Such approval is a significant achievement for the state's wine industry, because it allows vintners to distinguish wines produced in the region and allows consumers to easily identify those wines, said Robin Pollard, executive director of the Washington Wine Commission, a promotional state agency funded by fees on member wineries and growers.

The recognition also speaks to the degree of development and sophistication of Washington's wine industry, she said.

"Diversity, that is really one of our state's greatest assets," she said. "It just gives us yet another tool to help raise awareness in terms of what makes Washington wines so special."

Washington state is the nation's second-largest producer of wine, after California. More than 300 wineries, 300 wine-grape growers and 30,000 vineyard acres support the $2.4 billion annual industry.

The federal government already has recognized the state itself as an appellation and six appellations inside the state.

Horse Heaven Hills is above the only sea-level passage through the Cascade Mountains, linking growers there to both the marine environment of the Pacific Ocean and the semiarid desert of Eastern Washington.

Its warmer temperatures than in some areas of the state, such as the Yakima Valley appellation, make Horse Heaven Hills ideal for such varieties as merlot and cabernet sauvignon. At the same time, vintners are finding success with some white-wine varieties as well, such as chardonnay and riesling, said Kevin Corliss, director of viticulture for Ste. Michelle Wine Estates.

In addition, cool breezes that blow across the plain reduce the risk of disease and pests and create balanced fruit that is not too sweet or acidic, he said.

Winemakers often seek blocks of grapes that will provide a different taste, because of the soil, temperature or other climate features. True wine aficionados know exactly where the wine that touches their palate is produced — down to the hillside.

That Horse Heaven Hills sits entirely inside the already-recognized Columbia Valley appellation speaks to growers and winemakers drawing even further distinctions for their products, Corliss said.

The region now includes four wineries, and more than 20 vineyards produce grapes for some of the state's premier wineries, according to the Washington Wine Commission.

Even the name for the region is unique.

In 1857, a Central Washington rancher followed the tracks of his escaped horses up a steep mountainside to find them munching grass atop a beautiful upland plain.

As the story goes, James Kinney proclaimed, "Surely, this is horse heaven." More than a century later, the name for the region still stands.