Construction began Oct. 26 on a $35.7-million stormwater and water-reuse system in New York City’s Central Park, designed to reduce runoff entering combined sewers serving Harlem and East Harlem.

The park's northern water bodies—the Pool, Loch and Harlem Meer—are currently supplemented with city drinking water that flows by gravity through the system, while stormwater from the surrounding park watershed can add to flows entering the combined sewer system. The new project aims to capture and reuse more of that water while creating additional runoff capacity during heavy storms.

The North End Recirculation System will connect the three water bodies through new pumping, filtration and conveyance infrastructure. During dry weather, water will be pumped from the Meer south toward the Pool, where it will be filtered before gravity carries it through the Loch and back into the Meer.…