I recently became curious as to just how many acres of vineyards there are in the Santa Cruz Mountains and Santa Clara Valley AVAs; surprisingly it's not an easy question to answer. Mapping county figures to the AVAs is tricky, as the AVAs cross county lines. According to the official figures from the National Agricultural Statistics Service there are just 377 acres of vines in Santa Cruz County, with 358 producing fruit in 2008. Similarly in Santa Clara County there are 1462 acres planted, with 1432 in production.
There are approximately 300 acres of vineyard in the Santa Clara AVA which lie inside the San Benito County border, and there is probably a similar amount of vineyard in the Santa Cruz Mountains AVA that lie within Santa Clara or San Mateo Counties. So at a rough estimate, there are probably around 700 acres of vines in the Santa Cruz Mountains AVA and at least twice that in the Santa Clara Valley AVA.
There are few large vineyards in the Santa Cruz Mountains; the rugged terrain isn't easily farmed. Anything over 20 acres is considered to be extensive. The largest, and most famous, is Ridge's Monte Bello Vineyard. This is in fact a number of smaller vineyards located at different elevations, giving a total of 108 acres. Other well known vineyards include Mount Eden and the Regan Vineyard owned by Bargetto, both of which are over 40 acres.
In Santa Clara Valley, most of the acreage is concentrated in a few large vineyards, several of which are located along Highway 152 in the San Ysidro District and Pacheco Pass AVAs. San Ysidro District lies to the east of Gilroy on Highway 152. While the AVA may be small at just 2,340 acres, it is home to two of the largest vineyards in the area. Mistral Vineyard and San Ysidro Vineyard sit side by side to the north of Highway 152.
Mistral is slightly the larger of the two, with 260 acres planted from a total of 375. It is understood to contain mainly Chardonnay and Merlot which is sold to large producers, though there is a small amount of the port grapes Touriga Nacional, Tinta Cao and Tinta Madeira. Until its sale in 2007 the vineyard was owned by Millbrook Wine of New York, through their Pebble Ridge Vineyards subsidiary. (I have yet to determine who the new owners are.) Millbrook also own the highly regarded Williams Selyem winery in Sonoma, who have produced a port-style wine from the vineyard. The San Ysidro Vineyard has around 250 acres planted. A little over half is Pinot Noir with the remainder being Chardonnay and a small amount of Merlot. It is owned by the San Ysidro Corporation, the parent company of United California Citrus.
Further along, just before the 152 meets the 156 is the Dunne Ranch Vineyard, the largest in the AVA. As the road rises towards Pacheco Pass the vineyards are to the right, in the valley below. This 1000 acre ranch is owned by the Blackburn family, who also own the Pietra Santa winery in nearby Cienega Valley, but if you have $20M to spend it's understood to be for sale. Pietra Santa use only a fraction of the fruit; the majority is sold. The vineyard has around 300 acres of Chardonnay, 66 acres of Gewurztraminer and 10 acres of Pinot Gris; this alone makes Chardonnay the most planted variety in the AVA, and also makes Gewurztraminer the second most planted white variety. The western portion of the vineyard lies within the Pacheco Pass AVA. Further still, and also within the Pacheco Pass AVA, lies the San Felipe Vineyard; it covers some 122 acres and is evenly divided into Pinot Noir and Chardonnay. It is also owned by the San Ysidro Corporation.
Between them, these four vineyards account for over 1,000 acres of vines, yet their names rarely appear on any labels. It's understood that much of the Chardonnay goes to large producers such as Kendall Jackson, Au Bon Climat and Beringer; the owners don't like to talk about who their clients are. Some fruit is used by local producers; Storrs, Picchetti and Cronin have all produced Merlot from San Ysidro, and Calera use Chardonnay from the San Ysidro and San Felipe vineyards.
I would be interested in any additional information about any of these vineyards; if you can help please contact me.