TERROIR AND SOILS OF THE VINEYARDS OF CLARK COUNTY, WASHINGTON

Clark County, Washington is located in SW Washington just north of Portland, Oregon on the Columbia River. Vancouver is its largest city, and the county has an area of 630 square miles. Twelve wineries have sprung up in the past 10 years and are beginning to produce some good wines. It is not officially part of the Willamette Valley AVA so we have begun to characterize their terroir to help the wine producers understand their terroir. Seven of the wineries have vineyards in county with over 150 acres of grapes in production, with over half of that production at Bethany Vineyards. Climate of the area is xeric (wet winters and dry summers) with an average precipitation of 37 in/yr. About 80% of the vineyards are on Missoula Flood deposits and are fine grained. Those major soil series are: Hillsboro (Ultic Argixeroll), Odne (Aquuultic Argixeroll), and Olequa (Ultic Haploxeroll). Three other vineyards are located in the NE of the county near Battleground, an area that is above the Missoula Floods and is of volcanic origin. Most of the bedrock is basalt of Pliocene age. The main soil series is the Hesson series (Xeric Palehumult), and it is found in skeletal and fine grained facies. It is the county’s exact equivalent of the Jory Series in the Willamette Valley (Oregon’s state soil and the major wine producing soil). All volcanic soils are more than 15,000 calendar years old and have a Bt horizon in the profile.