Four Mile Valley N0 4 is a Federal-owned earth dam located in Modoc, California, with a primary purpose of fire protection, stock, or small fish pond. Completed in 1951 by the Forest Service, this dam stands at 8 feet in height and spans 1485 feet in length, providing a storage capacity of 172 acre-feet. The dam is regulated by the Forest Service and has an uncontrolled spillway with a width of 30 feet, along with an outlet gate also uncontrolled.

With a low hazard potential and a moderate risk assessment rating, Four Mile Valley N0 4 has not been rated for condition assessment as of the last inspection in August 2011. The dam's emergency action plan status, inundation maps, and risk management measures are not specified, indicating a need for further evaluation and planning. Despite its moderate risk level, this dam plays a crucial role in providing water resources for fire protection, livestock, and small fish, highlighting the importance of its maintenance and upkeep in ensuring the safety and sustainability of the surrounding environment.