The Verde Valley
The Verde Valley Wine Consortium, on behalf of the local grape growers and winemakers, prepared the petition to establish the approximately 200 square-mile Verde Valley AVA in Yavapai County, Arizona. The entire geological feature known as the ‘‘Verde Valley’’ encompasses approximately 714 square miles, most of which is National Forest land.
The AVA, however, encompasses a much smaller area and excludes much of the public lands that are unavailable for viticulture. Although an effort was made to exclude as many public lands from the AVA as possible, including Montezuma’s Castle and Montezuma’s Well National Monuments and the Prescott and Coconino National Forests, approximately 33 percent of the land within the Verde Valley AVA is still part of either the Prescott or Coconino National Forests. It was not practical to draw a boundary that would exclude all Federal land because several of the vineyards within the AVA are ‘‘islands’’ of private land surrounded on all sides by Federal land. Even with the amount of Federal land remaining within the AVA, there is still plenty of privately owned land available for vineyards within the boundaries. The AVA currently has 19 commercial vineyards, with approximately 136 acres under vine.
Several existing vineyards are planning to expand by a total of an estimated 24 acres in the near future. In addition, there are 11 wineries located within the AVA and 25 winery-operated tasting rooms. The distinguishing features of the Verde Valley AVA are its climate, soils, and topography. The information and data pertaining to the AVA contained herein comes principally from the petition that was filed for the Verde Valley AVA and its supporting exhibits.
Name History
The Verde Valley AVA is located within the larger valley of the Verde River in central Arizona. The region of the AVA has been referred to as the ‘‘Verde Valley’’ since 1583, when the Spanish explorer Antonio de Espejo recorded his travels in the area. It has been known as the Verde Valley ever since. With the passing of the Homestead Act in 1862, which granted land in the area to settlers who were willing make productive use of the land, pioneers began moving to the region. In 1865, the U.S. Army arrived and began providing protection to the Verde Valley settlers. They established Camp Verde in 1871 and, in 1879, when they renamed the post Fort Verde, the surrounding town continued to be known as Camp Verde.
There are several examples of written works over the years that refer to the ‘‘Verde Valley.’’ An early geological study of the region, published in 1890, was entitled, ‘‘Thenardite, mirabilite, glauberite, halite, and associates, of the Verde Valley, Arizona Territory.’’ A 1963 publication by the U.S. Department of Interior was titled, ‘‘Geology and Ground Water in the Verde Valley–The Mogollon Rim Region, Arizona.’’ In 2012, Lonely Planet, the largest travel publisher in the world, named the Verde Valley in its Top 10 list of U.S. travel destinations for 2013, primarily because of the Verde Valley wineries. The article notes, ‘‘Between Phoenix and the Grand Canyon, the Verde Valley is taking off as Arizona’s go-to destination, and not just among the spa and crystal Sedona fans of years past.’’ Finally, an article about the wine industry in Arizona, published in a 2013 edition of the In Business magazine, states that the majority of Arizona’s wine grapes are grown in ‘‘the greater Willcox area and the Verde Valley.’’ The Arizona Department of Transportation has posted “Welcome to the Verde Valley” signs on every highway leading into the valley.
Boundary Evidence
The Verde Valley AVA is in Yavapai County, Arizona, approximately 100 miles north of the Phoenix metropolitan area. The Verde River flows through the center of the valley from northwest to southeast, and steep foothills rise up around the valley. The northern boundary separates the AVA from the Coconino National Forest. The northern boundary primarily follows the 3,800-foot elevation contour because the terrain becomes too steep for cultivation above that elevation. The eastern boundary follows a series of elevation contours to separate the AVA from extremely steep terrain, as well as from the public lands within the Coconino National Forest and Montezuma’s Well and Montezuma’s Castle National Monuments. The southern boundary follows section lines on the U.S.G.S. topographic maps. Most of the land south of the boundary is uninhabited and is part of the Coconino National Forest. The western boundary primarily follows the 3,800-foot elevation contour, to exclude the steeper terrain of the Black Hills range and the public lands within the Prescott National Forest.
Distinguishing Features
The Verde Valley AVA is distinguished by its climate, soils, and topography. Climate encompasses information on the annual precipitation amounts, temperature range, and growing degree day (GDD) accumulations within the Verde Valley AVA.
Average annual rainfall amounts within the Verde Valley AVA are significantly lower than in the surrounding regions. Due to the low rainfall amounts, vineyard owners within the AVA must use irrigation to ensure adequate hydration for their vines. There are sufficient sources of groundwater within the AVA for irrigation, and vineyard owners employ water conservation methods such as drip irrigation and the use of agriculturally approved reclaimed water.
While cooler than the lower Arizona deserts, temperatures within the Verde Valley AVA are warmer than in each of the surrounding regions and provide suitable heat and sunlight for photosynthesis. The warm daytime temperatures lead to high annual GDD accumulations. The temperatures and GDD accumulations within the AVA are well suited for growing warm climate grapes such as Syrah, Cabernet Sauvignon, Petite Sirah, Zinfandel, Malvasia Bianca, and Viognier.
Finally, the difference between the daytime high temperatures and nighttime low temperatures within the AVA, known as ‘‘diurnal temperature swings,’’ are substantial. Although temperatures in the AVA are high during the daytime, cool nighttime air drains into the AVA from the surrounding higher elevations and lowers the nighttime temperatures. As a result, the difference between daytime high temperatures and nighttime low temperatures within the AVA can exceed 30 degrees F, which is a greater difference than found in any of the surrounding regions. Such a significant drop in nighttime temperatures delays grape ripening, lessens the respiration of acids, and increases phenolic development in the grapes. The following tables show the mean diurnal temperature swings for each month during the growing season for the years 2014 to 2016.
Soils
The soils within the Verde Valley AVA are primarily alluvial soils. The majority are of the Altar, Mule, Cornville, Anthony, Retriever, House Mountain, Cowan, and Arizo soil series. The composition of these soils ranges from very fine sandy loam to gravelly loam with silt and limestone. Traces of the Supai, Verde, and Martin Limestone formations can also be found throughout the AVA.
The soils of the AVA generally provide appropriate water drainage and have above-moderate levels of nutrients, although low calcium and magnesium levels are common. Additionally, high bicarbonate levels in the groundwater of the AVA have been found to increase soil pH and inhibit nutrient uptake in the vines. These unfavorable vineyard conditions can be mitigated through rootstock, varietal, and clonal selections that can tolerate and even benefit from these nutrient deficiencies.
To the north and east of the Verde Valley AVA, along the Mogollon Rim, the soils are described as ‘‘stony.’’ The most prominent soil series in these two regions are Brolliar stony loam and Siesta stony silt loam. The remainder of the soil to the north and east of the AVA is comprised of approximately 22 other defined soil series, most of which have the terms ‘‘stony’’ or ‘‘very stony’’ in their names. To the west and southwest of the AVA, in the Black Hills, the soils are also typically stony. Major soil series in these regions include Brolliar very stony clay loam, Soldier cobbly loam, Lonti-Wineg, and Lynx.
Topography
The Verde Valley AVA is located within the basin of the Verde River. The shape of this basin has been described as a ‘‘bowl with a crack in it to the south where the river flows out of the valley.’’ The edges of the ‘‘bowl’’ gently slope down towards the valley floor at angles of 2 to 15 percent. Elevations within the AVA range from approximately 3,000 feet to 5,000 feet, although most of the AVA is below 3,800 feet.
The AVA is surrounded on all sides by higher elevations and steeper slopes. To the north and northeast of the AVA, elevations rise up to 8,000 feet along the edge of the Mogollon Rim. To the west and southwest of the AVA are the Black Hills, which have steep slopes and elevations up to approximately 7,800 feet.
The Verde Valley AVA’s topography affects viticulture. Gentle slopes allow for easier vineyard management than steep slopes. Furthermore, because the AVA is lower than the surrounding regions, cold air drains from the higher elevations into the AVA during the spring and fall. As a result, the risk of frost damage increases in the AVA, particularly in vineyards adjacent to the river and the river’s numerous tributary creeks flowing from the north. Vineyard owners mitigate the risk of frost by using inversion fans and protective sprays and by planting late-budding varietals of grapes.
Summary Of Distinguishing Features
The evidence provided in the petition indicates that the climate, soil, and topography of the Verde Valley AVA distinguish it from the surrounding regions in each direction. The following table summarizes the features of the AVA and the surrounding regions.
The Southwest Wine Center
The Southwest Wine Center at Yavapai College is a premier wine industry and community resource, offering a comprehensive hands-on education from vineyard-to-bottle with programs in enology, viticulture and business/entrepreneurship through its estate vineyard, teaching winery, fully-operational tasting room, and region-wide wine industry research epicenter. It is the only college in Arizona offering degree and certificate educational programs in viticulture and enology.
