Where is this vineyard in California wine country?

Can you tell us where this vineyard is located in California wine country? Write your answer in the comment section? Here are some clues.

• This is a small AVA located in Sonoma County.
• There are no wineries or tasting rooms located here.
• Approximately 150 acres are planted with grape vines.
• Elevation is 800 feet or more.
• Zinfandel is the most planted grape in this wine region.

Name this wine region.