Located in Jefferson County, Colorado, the D.O.E. Rocky Flats A-4 dam, also known as N. Walnut Creek No. 4, was completed in 1979 and is owned and regulated by the Department of Energy. The primary purpose of this earth dam is flood risk reduction along the North Walnut Creek, with a storage capacity of 160 acre-feet and a maximum discharge of 6000 cubic feet per second. The dam spans 1050 feet in length and stands at a height of 40 feet, with a structural height of 54 feet.

Despite its low hazard potential, the condition assessment of the D.O.E. Rocky Flats A-4 dam is not available. However, it undergoes inspections every 6 years, with the last one conducted in October 2011. The risk assessment for this dam is moderate, with a DSAC assigned date not specified. Emergency action plans, risk management measures, and inundation maps for the dam are also not currently available, emphasizing the need for continued monitoring and evaluation of this critical infrastructure in the face of changing climate conditions and water resource management challenges.