Cosumnes River is an AVA in the north-western corner of Lodi, in California's Central Valley. The low elevation of the land and the Sacramento Delta just south of the region contribute to the climate here, which is cooler and more maritime than the rest of the appellations in Lodi. This is perfect for the production of white wines, and plantings in Cosumnes River are dominated by Chardonnay and Sauvignon Blanc.
The AVA is bounded by highways: the highway that connects Sacramento and Lodi makes up the eastern border of the region, while the highway connecting Sacramento with Stockton is in the west. The Alta Mesa and Clarksburg AVAs can be found across these borders, east and west respectively. The Cosumnes river itself runs through the AVA before reaching the Sacramento Delta in the south-west.
The Delta provides an almost-constant marine layer of fog to the low-lying vineyards of Cosumnes River, most of which do not quite reach 50ft (15m) above sea level. This is better for white wine than for red: a lack of heat in the growing season preserves acidity in the grapes.
Soils in the Cosumnes River AVA are mainly alluvial deposits from the river with varying levels of fertility. The river, which comes from the western slopes of the Sierra Nevada mountains (where it also forms the boundary between Amador and El Dorado counties), is prone to flooding in its southern extremes which poses a risk to viticulture in the area. As with most of Lodi, there are few wineries within the boundaries of the AVA itself. Most vineyards here are owned by producers in other parts of Lodi and contribute to wines made under the larger Lodi and regional Central Valley AVAs.
