The Royal Slope vineyards is the newest American Viticultural Area (AVA) of Washington State. The process of achieving AVA status is long and expensive. Many factors must be qualified: historical context, soil significance, particular climate, and unique flavor in final wine. The result has been an AVA achieving the highest scoring wines of Washington State and a reputation for excellence.

The future is very bright for the Royal Slope, with further sub-AVAs likely and promises of many more high-quality vintages. Let’s take a closer look at this latest AVA.

How Do Vineyards Qualify as AVAs?

Achieving AVA status is very costly and time consuming. The proposed area must meet specific qualifications to be considered, including historical context, unique terroir, and distinctive taste profiles in the wines.

Royal Slope has been producing wines that are absolutely rocking people’s worlds.

Historical Context

The first step is hiring a licensed geologist. In this case, Dr. Alan Busacca was tasked with providing evidence that there was historical context and unique terroir that warranted this new AVA. The name Royal Slope has been used since at least the 1950s. It is believed that the name originated from two Scotsman that climbed the Saddle Mountains and remarked on the slope’s majestic quality.

The Royal Slope AVA is 156,389 acres, of which 1,900 acres are currently planted to wine grapes. Wine grapes were first planted here in 1983, but the Royal Slope did not achieve AVA status until September 2nd, 2020. Today there are 13 commercial vineyards and one winery located in this AVA.

Washington State AVAs - Royal Slope AVA
Washington State AVAs – Royal Slope AVA highlighted

Unique Terroir

As it pertains to unique terroir, “The AVA is something of an island geographically that is surrounded on all four sides by very different lands,” Dr. Busacca explained. To the north are the flatlands and sand dunes of the Quincy Valley. To the east and south is the barren, uncultivable “badlands.” To the west are the bedrock cliffs that run into the Columbia River. What makes the soil of the Royal Slope unique is the very fine, sandy loam and silt combined with bedrock basalt.

Another important aspect of the Royal Slope AVA is its unique elevation and range in temperature. Elevation ranges from 610 feet above sea level to the heights of 1,756 feet. This is considerably higher than any neighboring AVAs and permits huge temperature variations. This diurnal swing (difference between night and daytime temperature) allows for 22 different varieties to be cultivated. Aryn Morell, winemaker for Mullan Road explains, “You get all the heat benefits of Red Mountain AVA, but with the advantage of three weeks’ longer hangtime due to the very cool nights.”  For comparison, the average elevation of Royal Slope AVA is 1,300 feet, while Wahluke Slope AVA, just 15 miles to the south, averages 600 feet elevation.

Lawrence Vineyard, Columbia Valley, Washington

Distinctive Taste Profile

This individual terroir leads us to our final qualifier: unique taste profile in the wines from the Royal Slope. Aryn Morell explains that the very warm afternoon allows for optimal fruit ripeness while eliminating the green bell pepper flavors typical of Cabernet Sauvignon. At the same time, the ripe fruit flavors are perfectly balanced by fresh, natural acidity due to the very cool nights. This combination of natural acidity, ripe fruit, and very well integrated tannins are the hallmark of the Royal Slope AVA.

Stillwater Creek Vineyard in Royal Slope AVA, Mullan Road Cellars
Stillwater Creek Vineyard in Royal Slope AVA, Mullan Road Cellars

Worth the Wait

The process for filing and achieving approval from The Alcohol and Tobacco Tax and Trade Bureau for the Royal Slope AVA took 4-5 years. The cost was tens of thousands of dollars paid for by the vineyards in the Royal Slope. However, they believe that detailing Royal Slope on their wine labels will be worth the investment and appreciated by both wine enthusiasts and sommeliers. Vineyards located in Royal Slope annually score the highest ratings of all the AVAs of Washington State. Winemaker Aryn Morell believes it to be the very best AVA for all 22 varieties they grow. Achievements such as being Washington State’s first ever 100-point Syrah wine support this claim. This means premium producers such as Mullan Road that use 90% fruit from this AVA will change their label to read Royal Slope AVA.  This could begin as soon as the 2019 vintage.

The Royal Slope AVA is a very large AVA with potential for further fragmentation. The very top of the slope is locally known as Frenchman Hills, followed by another premium area called Stillwater Creek. Both of these will likely push for their own AVAs in the near future. Dr. Busacca says the future is bright. “In a short period of time,” he said, “Royal Slope has been producing wines that are absolutely rocking people’s worlds. [It] has jumped onto the wine map very quickly based on exceptional fruit character and quality.”

The addition of Royal Slope makes a total of 16 AVAs in Washington State. The process for achieving this status was long and costly; however, the unique history, terroir, and character of the wine warranted the effort. The exceptionally high pedigree of the Royal Slope vineyards has been validated by critics and high scores. The future is bright here, and it has only just begun.


Nick Poletto, DipWSET,CSS,CSW has an extensive wine background that began in 2002 and includes studying abroad in both Italy and Argentina, working a harvest season at a winery in Martinborough, New Zealand, and teaching the WSET at Johnson and Wales University. Currently the Director of Wine and Spirit Education for Kobrand Corporation, Nick is a "practical only" MW student, meaning he has passed the theory portion of the Master of Wine exam.

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