During World War One, American involvement in the war brought the historic DEP Police to duties protecting the NYC water supply. As of the current today 2019, the DEP Police today still has the same mission guarding the water supply, and is a participant of the annual First Provisional Regiment memorial services, held at the Village of Sleepy Hollow, NY. This Aqueduct Defense Memorial Service honors and remembers 40 soldiers who died while serving New York State during World War I. DEP Police provides an honor guard, cooperates with the NY state defense force, and local government officials to remember those perished while on aqueduct duties.
In 1914, American participation in World War One redirected the historic DEP Police to safeguarding New York City's water supply. Today, the DEP Police continues to fulfill this mission and honors fallen soldiers through its involvement in the annual First Provisional Regiment memorial service.