Located in Mesa, Washington, the 804 Reservoir Dam is a state-owned structure primarily used for irrigation purposes. Completed in 1979, this earthen dam stands at a hydraulic height of 12 feet and a structural height of 10 feet, with a length of 150 feet. It has a storage capacity of 160 acre-feet and covers a surface area of 10 acres, serving the surrounding area with water for agricultural needs.

Managed by the Washington Department of Ecology, the 804 Reservoir Dam is regulated, permitted, inspected, and enforced by the state. Its hazard potential is rated as low, and its condition assessment is currently not rated. The dam is situated offstream and falls under the jurisdiction of the Walla Walla District of the US Army Corps of Engineers. With a maximum discharge capacity of 50 cubic feet per second, this dam plays a crucial role in water resource management in the region.

Congressional District 04, represented by Dan Newhouse, oversees the 804 Reservoir Dam, ensuring its compliance with state regulations and safety standards. As a key infrastructure for irrigation in Franklin County, this dam underscores the importance of sustainable water resource management in the face of changing climate conditions. With its strategic location and vital role in supporting agricultural activities, the 804 Reservoir Dam stands as a testament to the resilience and adaptability of water infrastructure in the Pacific Northwest.