East Branch Reservoir

East Branch Reservoir, formed by impounding the eponymous branch of the Croton River, is part of New York City's water supply network. It is located in the Putnam County town of Southeast, near the village of Brewster 35 miles (56 km) north of the city.

It was placed into service in 1891, and holds 5.2 billion US gallons (20,000,000 m3) at full capacity. It drains a 75-square mile (180 km²) area that includes Bog Brook Reservoir as well, and from the East Branch Reservoir, the water flows into the continuation of the East Branch of the Croton River, then into The Diverting Reservoir, then via the Croton River to the Muscoot Reservoir and the New Croton Reservoir, into the New Croton Aqueduct, and finally to the Jerome Park Reservoir in the Bronx for daily distribution. It has a surface area of 525 acres (2.12 km2) and reaches a mean depth of 32 feet (10 m).

It is one of two double reservoirs in NYC's system; it is connected to the Bog Brook Reservoir via a 1,778-foot (547.07 m) tunnel. When the two were being built, the project's name was "Double Reservoir I". The second double reservoir project ("Double Reservoir II") would create the Croton Falls and Diverting reservoirs.

The village of Southeast Center, named for the town of Southeast, was levelled and flooded to create the reservoir. Parts of the village remain, including Sodom Rd, at the foot of the Sodom Dam, which holds the reservoir back.

Construction of the reservoir also flooded part of the village of Milltown, in the northeastern corner of Southeast, near present-day Deforest Corners. Many of the village's original buildings were moved to higher ground, onto present-day Milltown Rd, one of Southeast's longest roads running from New Fairfield, CT to Route 22 in Southeast. The village of Milltown's 1-room schoolhouse still stands today as a private residence. Foundations, rock walls and roadbeds for both villages can still be seen during droughts.