Californian Terroir: The Russian River Valley

Within this narrow band, climate conditions are ideally balanced, with the chilly maritime influence gradually waning as it nears the hot, dry Central Valley, where superior viticulture is not possible.

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In the United States, legalized wine areas, which must be approved by an arm of the U.S. Treasury Department, are called “American Viticultural Areas,” or AVAs. They are the equivalent of France’s appellations d’origine controlee. In order to bear an AVA on the bottle label, a wine must contain at least 85% of grapes from that area.

California contains more than 100 individual AVAs; the number changes with some rapidity, as new ones are applied for frequently. The Russian River Valley is simply one of this multitude of AVAs, although, at 96,000 acres (about 39,000 hec), it is one of the state’s largest, ranking 17th in size. The Russian River Valley also was one of the first to be officially recognized, with a formal date of Nov. 21, 1983. In my first book, A Wine Journey along the Russian River, I trace much of the history of Pinot Noir in this lovely, forested region, which lies some 60 miles north of San Francisco. The important thing to understand about the Russian River Valley is the Russian River itself. From its source in the Mendocino Highlands, it carves out a tortured path to the Pacific Ocean, running in a straight southerly direction until it takes a sudden turn to the southwest, below Healdsburg, before heading west to its junction with the sea, at Jenner.

It used to be said, and there is truth to it, that the Russian River was the main conduit of chilly air and fog into the valley. Without the river, the valley would be dry and hot, as is the Alexander Valley, immediately adjacent to its northeast corner; yet Alexander Valley is patently too warm for the Pinot Noir. That the Russian River does help to funnel cool air into the Russian River Valley is indisputable. However, newer research, aided by satellite imagery, has shown also that cool maritime air pours into the valley from at least two sources: through gaps in the coastal mountains leading toward Bodega Bay (where Alfred Hitchcock filmed “The Birds”), in the southwest, and through the so-called Petaluma Gap. One drives through the latter, south of the Russian River Valley, along the 101 Freeway; near the city of Petaluma, one passes a huge, broad plain, unencumbered by hills, stretching south to the windswept shores of San Pablo Bay, an extension of the great San Francisco Bay. Thus, the cool maritime air also reaches the Russian River Valley through the Petaluma Gap (which is likely to achieve its own AVA status).

A glance at the map, however, shows that the cooling influence is strongest along the valley’s southern stretches, from Occidental in the west to Santa Rosa in the east. The more northerly you travel in its 15-mile length, the warmer the average temperature climbs. There also are complicating factors in the land’s exposition and soils. In the Green Valley of the Russian River Valley (a separate AVA within the greater AVA), the coastal hills can reach elevations of 600-700 feet. In the valleys between them, the temperature is quite cool, the vineyards often are shaded, and the lower elevation acts as a sink into which maritime air and, in particular, fog invades. This is Pinot Noir terroir.

Yet the higher elevations may be quite sunny all day long, rarely experiencing much fog, and exposed to higher levels of solar radiation. Here, Zinfandel is at its best. So these varieties, Pinot Noir which loves coolness and Zinfandel which requires warmth, may co-exist virtually side by side, due to extreme differences in local conditions.

This complexity of terroir exists throughout the greater Russian River Valley, which is why serious proposals have been put forth, by vintners, to sub-divide the valley into a series of smaller AVAs, perhaps as many as 6 or 7. So far, nothing has come of these proposals, due to the politics that almost always accompanies anything to do with new AVAs or changing the boundaries of existing ones. But from the point of view of the critic, the Russian River Valley does need to be sub-appellated, with greater distinctions being made concerning its warmest and coolest corners.

Written by Steve Heimoff

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