Holbrook, located in Ash Valley, California, is a privately owned dam that serves multiple purposes including flood risk reduction, irrigation, and water supply. Built in 1952, this earth dam stands at a height of 26 feet and has a storage capacity of 719 acre-feet, providing essential water resources for the region. The dam is situated on Ash Creek and has a drainage area of 14 square miles, with a surface area of 122 acres.

Managed by the California Department of Water Resources and regulated by the Safety of Dams agency, Holbrook is in a satisfactory condition with low hazard potential. Despite being a smaller dam, it plays a crucial role in mitigating flood risks and ensuring water availability for agricultural and residential needs in the area. The dam underwent its last inspection in August 2020, with a planned inspection frequency of once per year to ensure its continued functionality and safety.

Overall, Holbrook serves as a vital infrastructure in Lassen County, California, contributing to the region's water resource management and climate resilience efforts. With its strategic location and multiple purposes, the dam plays a significant role in supporting the local community's water supply needs and protecting against potential flooding events. Continuous monitoring and maintenance efforts ensure that Holbrook remains a reliable asset for water storage and flood risk reduction in the area.