Foss Valley, located in Napa, California, is a privately owned Earth dam completed in 1988 for the primary purpose of water supply. The dam stands at 56 feet tall with a storage capacity of 800 acre-feet and a surface area of 31 acres. It serves multiple purposes including irrigation and recreation, and is regulated by the California Department of Water Resources (DWR) under the Safety of Dams program. The dam is situated on Tr Milliken Creek within the Sacramento District.

With a high hazard potential and satisfactory condition assessment as of September 2017, Foss Valley dam undergoes regular inspections to ensure its safety. The last inspection was conducted in April 2021, highlighting its compliance with state regulations and enforcement. The dam's Emergency Action Plan (EAP) is periodically updated, with the latest review in January 2021, although details on its preparedness and adherence to guidelines are not specified in the data. Despite the lack of specific risk assessments or management measures, Foss Valley remains a vital water resource structure in the region, providing essential services to the surrounding area.