McDonald's Brook is tributary of the Passaic River. It is a natural stream originating in Clifton, New Jersey, passing through Passaic, New Jersey. For most of its length, it runs underground in a culvert constructed by the United States Army Corps of Engineers. Prior to the construction of the culvert, larger parts of it ran through a ground-level stream bed, though parts of it ran underground even in its natural configuration.
The brook, throughout its length, is used as a catchment for storm drain by the cities of Clifton and Passaic. Parts of Clifton's combined storm/sewer lines run adjacent, and when they overflow or have breakages, feed additional stormwater or raw sewage into the brook.
In the past, Clifton industry took advantage of the brook for wastewater dumping, mostly illegally.
The brook runs through Passaic's Third Ward Veterans Memorial Park, constructed in the 1930s as part of the Works Project Administration (WPA). At the time of the park's construction, the brook's path was altered slightly, and a small lake bed was dug in the center of the park, creating a pond fed by the brook. The pond was open to fishing and boating until the detection of industrial pollution.
Presently, the park contains the only exposed portion of the brook. Near the foot of the In a late 20th century rehabilitation of the park, the brook was rerouted again. Much of the new bed eroded to the sides.