The Petaluma Gap - an American Viticultural Area
American Viticultural Area

The Petaluma Gap AVA

AVAs, or American Viticultural Areas, are an important part of how we think about and choose our wines. AVAs designate a specific area where grapes are grown and are therefore critical to understanding the growing conditions that affect the aromas and flavors of the wine. Names like Napa Valley, Sonoma County, Russian River Valley and Carneros are all AVAs. In December of 2017 the federal agency that regulates winemaking designated the Petaluma Gap (where McEvoy Ranch sits) as the country’s newest American Viticultural Area (AVA).

AVA applications are evaluated on the climate, geology, soils, physical features, and elevation, as well as the area’s cultural recognition. The two characteristics that most define the Petaluma Gap are the wind and topography. Here at McEvoy Ranch, there is another factor: the fog. There are actually two fog systems at play. Fog moves easily through the Golden Gate to San Pablo Bay, then up the Petaluma River Valley, spreading throughout the eastern portion of the Gap. At the same time, the low-lying coastal hills surrounding Petaluma also allow Pacific marine fog to travel further inland than many other places in the Coast Ranges.

These two fog systems meet in the middle in places of lower elevation, creating some of the best natural grasslands on the coast. The vineyards at McEvoy Ranch are planted in the hills above San Antonio Creek, uniquely situated between and above the two fog systems. There are many summer mornings when we wake up to dense fog in the Petaluma River Valley. Leaving Petaluma southwest towards McEvoy Ranch, crossing San Antonio Creek and climbing Red Hill, the fog starts to thin. Nearing the top of the hill and approaching the final gate to enter the Ranch, the fog disappears and brilliant rays of sunshine bounce off the mist that still hangs in the air. The temperature is cool but the sun’s rays are warm, the vines are wet with dew and the leaves glisten in light.

Looking back towards Petaluma, you can see other rounded peaks basking in the sun above an ocean of fog. Looking west towards the Azaya Vineyard in Hicks Valley, there is a bank of fog perched forebodingly along the ridge. It throws little wisps of fog down towards the ranch that burn off soon after separating from the bank. By 10 or 11am, it is clear that the warmth of the day will push the fog back towards the ocean.

Some days, the elevation of the marine layer is so high that we are blanketed from all directions, but that is rare. It is much more typical that the vineyards here at McEvoy Ranch will enjoy extra morning sunshine hours compared to Azaya Vineyard and many other places in the Gap.

This became very clear to us several years ago when we began farming the Azaya Vineyard. It is less than two miles from McEvoy Ranch but the fruit is often picked 2-3 weeks later. There are two clones of Pinot Noir that are grown on both sites and the resulting wines are strikingly different. We think this is largely due to the climate, but of course the role of soil plays an indispensable role as well.

So, simply by studying this very small, 5 square mile part of the world, the importance of place and the need for the AVA system becomes very clear. The Pinot Noir we produce at McEvoy Ranch is quite different than those grown in the cooler, fog shrouded valley, and the reasons are primarily climate and topography. Isn’t science wonderful? We have started labeling our wines with this new AVA to let people know about this beautiful and distinctive growing area!

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