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Oak Knoll District AVA
Oak Knoll District AVA
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Oak Knoll District AVA
Oak Knoll District AVA
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Oak Knoll District AVA
Oak Knoll District AVA

Images Courtesy of Suzanne Becker Bronk


The Oak Knoll District AVA is a Napa Valley Appellation located at the southern end of the mid-valley floor, known for its close proximity to the San Pablo Bay, resulting in relatively cooler and more moderate temperatures.





Appellation Details

Oak Knoll District is located in the southern end of central Napa Valley, California and was officially designated an American Viticultural Area in 2004. Known for its relatively cooler climate and long growing season, the Oak Knoll District is one of Napa Valley's more renowned sub-appellations. Oak Knoll is one of Napa Valley’s flatter appellations and it enjoys primarily deep loam soils. Its location to the north of Napa city places it right in the path of the daily fog that creeps up from the Bay, making it one of the cooler AVAs. Because of this, many white grapes can be found here, along with pockets of Merlot, Cabernet Sauvignon and some old vine Zinfandel.

The center of the appellation is dominated by rich fluvial soils, which are deposited over time by the rivers meandering path and regular flooding. These deep fertile soils make for fruity and charming wines (no strict mountain tannins here!). Things get slightly more complicated in the west, where a small alluvial fan sits at the base of Mount Veeder; here the soil is more gravelly and the terrain slightly undulating. From a climatic perspective, the regular fog keeps the temperatures down, which means the wines tend to be among the more elegant and understated in Napa Valley.

Elevation:

  • Sea level to 800 feet (244 m)
  • The Oak Knoll District of Napa Valley lies at relatively low elevations compared to many other Napa Valley Appellations. This is likely due to the early influence of marine processes and then the development of the Dry Creek Alluvial Fan that was formed as the San Pablo Bay retreated back south over 100,000 years ago.

Soils:

  • The valley's largest alluvial fan formed by Dry Creek creates the defining feature of the district
  • The northwest area is composed of volcanically derived soils, with stony or gravelly consistency
  • Southern and eastern areas transition from gravel to silty clay loam near the river
  • Irrigation is often essential

Climate:

  • The Oak Knoll District AVA and neighboring Yountville AVA are two of the coolest of the Napa Valley Sub-Appellations, featuring long, cool growing seasons averaging eight months. The climate in this area is relatively uniform due to the broad, flat nature of the valley floor.
  • Moderate to cool, marine air and fog can remain until late-morning
  • Late afternoon breezes frequently occur, maintaining slightly cooler temperatures than the upper valley.
  • Mid-summer temperatures may reach 92°F (33°C) and drop to around 50°F (10°C) at night.

Rainfall:

  • Up to 36 inches (91 cm) annually

Principal Varieties:

  • Cabernet Sauvignon
  • Chardonnay
  • Merlot
  • Sauvignon Blanc
  • Riesling



Oak Knoll District AVA History

Capt. Joseph W. Osborn

Capt. Joseph W. Osborn

The area now known as the Oak Knoll District was originally part of the Rancho Napa land grant, nearly 23,000 acres of land given to Salvador Vallejo in 1838 by Mexican Governor Juan Alvarado. Salvador Vallejo was the younger brother of General Mariano Vallejo and had served as the Captain of Militia at the Sonoma Mission. Rancho Napa bordered George C. Yount's Rancho Caymus to the north and Rancho Yajome to the east, on the other side of the Napa River.

In 1851 Joseph W. Osborne was one of the first people to introduce fine vinifera varieties to the area, including Zinfandel, after purchasing an 800 acre plot of land in Rancho Napa. He named it Oak Knoll Ranch and as early as 1857 was already winning awards in the Bay Area for his wine made from "Foreign Grapes." Despite this early recognition, viticulture was not the most important agricultural activity here during this time, with only around 5% of available land used for vineyards in the 1880's. Then, local wine production declined even further with the onset of Phylloxera in the late 1890's and Prohibition in 1920.

Since the end of Prohibition, numerous vineyards have been planted in the Oak Knoll District, now totalling over 4,150 acres of planted grapevines. The Oak Knoll District was officially designated an American Viticultural Area in 2004.




Quotes

"The Oak Knoll District is a unique and distinctive grapegrowing area that has been informally recognized as a viticultural area for decades. It deserves to be recognized as an important American Viticultural Area within the Napa Valley."
- Janet Trefethen, Trefethen Vineyards

"The location of the Oak Knoll District at the mouth of the Napa Valley, with our warm sunny days moderated by the daily cool breezes off of the bay, means that the fruit can ripen slowly, maintaining freshness and aromatic lift, while developing a soft and elegant mouthfeel with balance and finesse."
- Steve Matthiasson, Matthiasson Wines




Notable Wines sourced from Oak Knoll District AVA

Lobo Wines
Lobo Wines 2015 Pinot Noir

A true "Napa Valley" Pinot Noir--rich and bright, from a family-owned vineyard in Napa's Oak Knoll District.

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Silenus Winery
Silenus Winery 2021 Cabernet Sauvignon

The Silenus Estate Cabernet Sauvignon comes from our estate vineyard located in the Oak Knoll District of Napa Valley. The OKD is one of the most diverse growing regions in the Napa Valley. The close proximity to the San Pablo Bay provides the fruit with warm days and cool nights. It has a perfect convergence of growing conditions, the mildest climate in the Napa Valley, alluvial fan soils that provide the right balance of nutrients and stress, and the longest growing season, about 8 months, that results in full and complex flavor development in the grapes. Silenus’ estate vineyard is located on the alluvial fan soils and is bounded on the North by Dry Creek. This location allows a touch more warmth than other areas of OKD. The result is a lush, balanced and profound wine.

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Alpha Omega
Alpha Omega 2018 'Sunshine Valley Vineyard' Cabernet Sauvignon

Sunshine Valley Vineyard is located on the western side of Highway 29 in the Oak Knoll District AVA.This vineyard is a cooler climate site, facilitating grapes to ripen slowly and allowing aromatics and tannins to ripen harmoniously and evenly at the same natural pace as the Brix. The deep soils provide wonderful complexity and structure.

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Fortunati Vineyards
Fortunati Vineyards 2022 'Estate ' Viognier

The Oak Knoll District, and our soil composition, are an ideal growing site for this exotic Rhône varietal! Vibrant and extremely aromatic, we whole-cluster press our estate-grown grapes to highlight the fruit components both in the nose and on the tongue. A heady perfume of peach, apricot and white flowers, plus a hint of coconut reveals itself as soon as the cork is removed. A dance across the palate reveals freshness and intensity, with tantalizing zings of cooking spices.

View Winery Profile

Oak Knoll District Resources and References

  1. "§ 9.161 Oak Knoll District of Napa Valley" (Title 27: Alcohol, Tobacco and Firearms; Part 9 — American Viticultural Areas; Subpart C — Approved American Viticultural Areas). Code of Federal Regulations. Retrieved October 30, 2007.
  2. Grossinger, R., & Beller, E. (2007). Landscape history of the trancas: Historical ecology research summary for the trancas crossing park and Napa River Trail, city of napa. San Francisco Estuary Institute. Retrieved from https://www.sfei.org/sites/default/files/biblio_files/NapaRiver_LandscapeHist_Trancas.pdf.
  3. Oak Knoll District of Napa Valley. (2018, December 20). Oak Knoll District: Napa Wine, Winery & Grape Growers Association. OAK KNOLL DISTRICT OF NAPA VALLEY. Retrieved September 23, 2022, from https://www.okdnapa.com/
  4. Elliot-Fisk, D.L. 1993. Viticultural Soils of the Trefethen Vineyards, Southern Napa Valley, Napa County, California. 89pp., unpublished.
  5. Oak Knoll District of Napa Valley (n.d.). Retrieved September 23, 2022, from https://www.trefethen.com/learn/place/oak-knoll-district-of-napa-valley/
  6. Palmer, Lyman L.; Wells, Harry Laurenz (1881). History of Napa and Lake Counties, California. Slocum, Bowen & Company. ISBN 978-1363000555.
  7. Weber, Lin (1998). Old Napa Valley: The History to 1900. Wine Ventures Publishing. ISBN 9780966701401.

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