The River Junction AVA is an American Viticultural Area

American Viticultural Area

An American Viticultural Area is a designated wine grape-growing region in the United States distinguishable by geographic features, with boundaries defined by the Alcohol and Tobacco Tax and Trade Bureau , United States Department of the Treasury....

 located in both San Joaquin County

San Joaquin County, California

San Joaquin County is a county located in Central Valley of the U.S. state of California, just east of the San Francisco Bay Area. As of the 2010 census, the population was 685,306. The county seat is Stockton.-History:...

 and Stanislaus County

Stanislaus County, California

Stanislaus County is a county located in the Central Valley of the U.S. state of California. As the price of housing has increased in the San Francisco Bay Area, many people who work in the southern reaches of the Bay Area have opted for the longer commute and moved to Stanislaus County for the...

, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. West of the city of Modesto

Modesto, California

Modesto is a city in, and is the county seat of, Stanislaus County, California. With a population of approximately 201,165 at the 2010 census, Modesto ranks as the 18th largest city in the state of California....

, the wine region is located at the confluence

Confluence

Confluence, in geography, describes the meeting of two or more bodies of water.Confluence may also refer to:* Confluence , a property of term rewriting systems...

 of the San Joaquin River

San Joaquin River

The San Joaquin River is the largest river of Central California in the United States. At over long, the river starts in the high Sierra Nevada, and flows through a rich agricultural region known as the San Joaquin Valley before reaching Suisun Bay, San Francisco Bay, and the Pacific Ocean...

 and the Stanislaus River

Stanislaus River

The Stanislaus River in California is one of the largest tributaries of the San Joaquin River. The river is long and has north, middle and south forks...

. The AVA was created as a result of a petition by McManis Family Vineyards, the only commercial winery in the appellation. River Junction AVA is cooler than surrounding areas of the Central Valley, and is the only place in the valley where high concentrations of fine sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

y loam

Loam

Loam is soil composed of sand, silt, and clay in relatively even concentration . Loam soils generally contain more nutrients and humus than sandy soils, have better infiltration and drainage than silty soils, and are easier to till than clay soils...

 are to be found. 90% of the vineyard

Vineyard

A vineyard is a plantation of grape-bearing vines, grown mainly for winemaking, but also raisins, table grapes and non-alcoholic grape juice...

 land planted in the AVA is in Chardonnay

Chardonnay

Chardonnay is a green-skinned grape variety used to make white wine. It is originated from the Burgundy wine region of eastern France but is now grown wherever wine is produced, from England to New Zealand...

 grape

Grape

A grape is a non-climacteric fruit, specifically a berry, that grows on the perennial and deciduous woody vines of the genus Vitis. Grapes can be eaten raw or they can be used for making jam, juice, jelly, vinegar, wine, grape seed extracts, raisins, molasses and grape seed oil. Grapes are also...

s.