AECOM provided engineering design, environmental services, and design services during construction for the 290-mgd Croton water treatment plant, as part of a joint venture. The new plant was the first water filtration plant in the city and supplies 10% of the city's average water needs and as much as 25% of the city's needs in time of drought.

The plant was built underground at the Mosholu Golf Course site in Van Cortlandt Park in the Bronx. AECOM's services included siting studies; planning; modeling; pilot testing; conceptual, preliminary, and final design; environmental impact statement; permitting; and public participation.

The new facility provides filtration and disinfection of water from the city's Croton supply of 13 reservoirs and controlled lakes, 30 miles north of the city. The facilities include a new raw water tunnel from the New Croton Aqueduct to the plant, coagulation/mixing, flocculation, stacked dissolved air flotation, dual-media filtration, and ultraviolet disinfection. The plant has two process trains, each capable of independent operation, to provide added operational flexibility and redundancy. This two-train concept was extended to the pumping stations, chemical systems, and electrical systems.