Sierra Pelona Valley AVA

Sierra Pelona Valley is an American Viticultural Area (AVA) in the heart of the Sierra Pelona Mountains, located in northwestern Los Angeles County, California north of State Route 14 (SR 14) between the towns of Santa Clarita and Palmdale, east of the Pacific Ocean and southwest of the Mojave Desert. It was established on July 21, 2010, by the Alcohol and Tobacco Tax and Trade Bureau (TTB), Treasury after reviewing the petition submitted by Mr. Ralph Jens Carter on behalf of Antelope Valley Winegrowers Association (AVWA), Rancho Santiago Vineyards and Madsen Vineyards proposing the viticultural area named "Sierra Pelona Valley."

Encircling the community of Agua Dulce just north of the city of Los Angeles, the viticultural area is a valley expanding with approximately of cultivation. The local usage of the name "Sierra Pelona" applies to the expansive valley landform, as well as the mountain range to the north. The Sierra Pelona Valley name best describes the viticultural area, according to the petitioner. Viticulture in the Sierra Pelona Valley area started in 1995 and by 2008, the region had of commercial vineyards.

Terroir

Topography

The petition asserts that the distinguishing features of the Sierra Pelona Valley viticultural area include climate, geology, soils, topography, and elevation. The inland location of the Sierra Pelona Valley both influences its distinguishing features and contributes to the success of its viticulture.

The geology of the viticultural area includes mostly consolidated alluvium between 23 and 37 million years old, but also includes some more recent alluvium, between 1.5 and 2 million years old. Further uniformity in the area is provided by a granitic intrusion, ranging from 195 to 225 million years
old, that spans the Sierra Pelona Valley. In contrast to the valley alluvium and
the granitic intrusion, the surrounding mountains, ranging from 195 million to
4.5 billion years old, consist mainly of very different rocks. The petition states that elevations of the viticultural area vary from . Those of the mountains to the west and of the mountain ridges to the north, east, and south vary from . Elevations of a canyon in the Santa Clarita area, about southwest of the boundary line, drop to approximately .

The large Sierra Pelona Valley region, oriented northeast-to-southwest, comprises Hauser Canyon, upper Agua Dulce Canyon, and Mint Canyon, including Sleepy Valley. The USGS Agua Dulce and Sleepy Valley maps show that the long, narrow, gentle side slopes of the Sierra Pelona Valley are surrounded by projecting mountain ridges to the north, east, and south and by a mountain and a chord of radiating canyons to the west. The valley floor itself has many isolated knolls but that most of the valley is on gentle slopes suited to viticulture. The USGS Agua Dulce and Sleepy Valley maps also show that intermittent tributaries in the Sierra Pelona Valley flow into Agua Dulce Canyon and create a single, south-flowing stream that eventually joins the Santa Clara River. The petition explains that the alluvium derived from rocks at higher elevations is carried downstream by these tributaries. This pattern of alluvium deposition contributes to the unique mix of mineral and chemical soil properties in the viticultural area. The fine quality winegrapes are universally associated with soils on midslopes where outwash accumulates and deeper soils form. These midslopes, the petition notes, are sometimes called viticulture "bellies," because they hold the sediment washed from the weathered rocks above and create vineyards. In most of the proposed viticultural area, winegrapes are grown on gentle midslopes.
The petition states that the viticultural area has other features besides gentle slopes are favorable for viticulture. Good water and air drainage and soils with low fertility and a high mineral content produce grapevines with reduced vigor but with more natural balance.

Elevation

With peaks rising up to almost , the Sierra Pelona Mountains form a substantial geological barrier between the ocean-cooled, low-lying Los Angeles Basin and the hot, dry elevations of the California High Desert. According to the USGS maps of the region and the petition, elevations in the viticultural area vary from . Elevations also
gradually decline approximately over the from the east side to the west side of the boundary line. At the town of Agua Dulce and the Agua Dulce Air Park in the Sierra Pelona Valley floor, elevations range from . The petition states that elevations outside of the viticultural area are generally higher than those in the valley. Some close-in peaks in the Sierra Pelona Range are Mount McDill to the north, and west of Mount McDill, a promontory at Bear Springs and a peak at Willow Springs. According to the petition and the USGS Sleepy Valley map, southeast of Sierra Pelona Valley, Windy Mountain stands at and two unnamed peaks reach elevations of , all within of the boundary line.

Climate

The petition, citing the "Soil Survey of the Antelope Valley Area", states that precipitation in the viticultural area averages between per year and occurs mainly in winter. The Sierra Pelona Valley daily growing season temperatures can vary by , with summer daytime temperatures reaching , and summer nighttime temperatures frequently dropping to . To contrast the climate in the viticultural area with that in
the surrounding areas, the petition gives climate data for several locations
outside the area. Sandberg is at an elevation of in the high mountains northwest of the viticultural area, and although it has a total annual average precipitation of , about the same as the upper-end precipitation in the viticultural area, Sandberg
has average daily growing season maximum and minimum temperatures of . San Fernando at an elevation of in a low-lying area to the southwest of the viticultural area, has a total average
monthly precipitation of and average daily growing season maximum and minimum temperatures of . Palmdale, at an elevation of in the desert due east of the viticultural area, has a total average monthly precipitation of and average daily growing season maximum and
minimum temperatures of .
Air drainage from surrounding higher elevations to the Sierra Pelona Valley floor reduces the hazard of frost damage in spring. In addition, air movement across the slopes reduces the threat of leaf fungus and the need for heavy spraying of pesticides. Wind direction is frequently shifted and redirected by hills, knolls, and valleys. The petition states that the climate of the mountainous surrounding areas does not support viticulture due to an excessively short growing season, cooler summers, and vine-killing, cold winters.

Soils

According to the petition, climate, especially rainfall and heat, influences
soils through the growth of plant types, the decomposition rate of organic
matter, and the weathering of minerals. Rainfall in the viticultural area makes it a transitional zone between desert and forest.
The soils on the valley floor in the viticultural area have significant differences compared to those on the surrounding mountains. On the valley floor and on foot slopes at the edges of the valley floor, the soils are very deep and moderately drained. The slope-wash soils on the foot slopes are poor, and have rock fragments on the surface in many areas. However, these rock fragments diffuse and reflect sunlight to lower leaves shaded by canopy, help keep the soil
warm, and increase soil moisture, all of which benefits viticulture. And although the poor soils reduce the growth rate of the vines, the wines made from the grapes of those vines have more natural balance. The petition explains further that the soils of the area benefit the classic grape varieties, which generally produce well only in poor sandy soils. The reduced vine growth rate decreases the need for summer pruning, irrigation, and use of farm equipment. On the other hand, these soils have multidirectional sun exposures, which allow for the planting of a variety of grapes. In the viticultural area soil depth is or more. The petition states that soil depth is important for vine growth because most vine roots grow to a depth of . Such deep roots are important because vines can extract of moisture for each foot of rooting depth. In contrast, the soils on the surrounding mountains are shallow, excessively drained, and infertile. They are dominantly on steep slopes, and are subject to erosion. These soils are suited to recreation, range, and wildlife, and to use as a watershed. The soils in Land Resource Area #19 are placed in capability units on the assumption that these conditions exist:
# The temperature generally is mild, and the frost-free period ranges from 210 to 300 days. Frosts occur locally, but protection is provided for crops that have a high cash value. Water erosion also is a hazard.
# Irrigation water is available for most irrigable land from wells, local reservoirs or sources outside the land resource area. All reasonable means are taken to conserve water. Rainfall generally is adequate so that most crops are not affected by accumulation of salt.
# Drainage and flooding generally are not a problem, though a few areas require further control of flooding. Flooding along the major streams has been reduced through flood-control works.
# A wide variety of common field, truck, fruit and nut crops are grown.
# A moderately high level of management is used.

References

External links

Los Angeles Vintners Association

Antelope Valley Winegrowers Association

TTB AVA Map

American Viticultural Areas of Los Angeles County, California
Sierra Pelona Ridge
Valleys of Los Angeles County, California
2010 establishments in California