Henne, also known as Lake Henne, is a private water resource located in Angwin, California, in Napa County. Built in 1959, this earth dam stands at a height of 49 feet and has a storage capacity of 109 acre-feet, serving primarily for water supply purposes, including irrigation and recreation. The dam sits on Angwin Stream, with a drainage area of 0.91 square miles, providing vital water resources to the surrounding area.

Managed by the California Department of Water Resources (DWR) under the Safety of Dams program, Henne is regulated, inspected, and enforced by the state to ensure its safe operation. With a high hazard potential but a satisfactory condition assessment as of September 2017, this dam plays a crucial role in water management in the region. Although there are no associated structures and limited information on its emergency action plan and risk assessment, Henne remains an essential component of the local water infrastructure.

Located within the Sacramento District and overseen by Congressman Mike Thompson, Henne presents a blend of historical significance and contemporary water resource management. As climate change continues to impact water availability and quality, understanding and maintaining dams like Henne becomes increasingly important for ensuring sustainable water management practices in the face of evolving environmental challenges.