River Junction, at the confluence of the San Joaquin and Stanislaus Rivers, is one of the few California appellations that is home to a single proprietor, McManis Family Vineyards. McManis successfully petitioned to have this area recognized as an AVA due to its unique combination of climate and soil. The proprietor noticed that the area seemed to be a depository for cooler maritime air, causing land surrounding the river junction to be an average of two to five degrees cooler than other Central Valley areas. The soil is unique in this area, since it’s the only place that a substantial amount of Grangeville fine sandy loam is found. These soils, located in the delta’s driest part, combine with the region’s cool temperatures to foster successful vineyards. River Junction encompasses 1,300 acres, with three-quarters of it already under vine. Chardonnay constitutes 90% of the planting. Grapes are susceptible to seasonally later frosts, which could prove challenging in some years.