Matrix Detention Basin in Washington Township, Mercer, New Jersey, is a privately owned flood risk reduction structure regulated by the New Jersey Department of Environmental Protection. Completed with an earth dam that stands at 8 feet high and spans 1950 feet in length, the basin has a storage capacity of 70 acre-feet and covers a surface area of 7 acres. It serves the primary purpose of mitigating flooding in the area, with a low hazard potential and a condition assessment that has not been rated.

Located in Robbinsville Township within the Philadelphia District, the basin has a drainage area of 0.25 square miles and a maximum discharge capacity of 428 cubic feet per second. Although last inspected in December 2000 with a frequency of every 4 years, the structure's emergency action plan status and risk assessment measures remain unspecified. Despite lacking certain details, Matrix Detention Basin plays a crucial role in managing water resources in the region and reducing flood risks for the community.