Winsor Dam

Winsor Dam is the main dam of the Quabbin Reservoir, an earthen dam across the Swift River at the south-west corner of the reservoir in Belchertown, inside Quabbin Park. It and Goodnough Dike were built in the 1930s and together hold back 412 billion gallons of water. The visitor center is at its west end, and you can walk or bike across the top for free. Cars are not allowed on it.

It is named for Frank E. Winsor, the engineer appointed in 1926 to run the Quabbin project. He died in 1939, the year the reservoir began to fill, before the water ever reached the spillway.

How to Visit Winsor Dam

Turn in at Quabbin Park's West (main) entrance on Route 9 in Belchertown, 100 Winsor Dam Road, and park at the Administration Building, where the visitor center is. The dam starts at the rotary beside the building. DCR keeps cars off both the dam and Goodnough Dike for security, so the dam is a walk, not a drive. DCR's own winter guide suggests bringing bikes and helmets to ride across on a mild day.

Parking at the main entrance is limited. If it's full, the rest of Quabbin Park is through the Middle and East entrances on Route 9, but there is no driving from there to the dam.

The Spillway and the Y Pool

At the north end of the dam, the spillway carries overflow out of the reservoir once the water reaches a set level. When the reservoir is full and the spillway is running, DCR's trail guide says you can see a waterfall from the Spillway Bridge and from the trail below it. The spillway water and the water released from the power station meet below the dam in the "Y" Pool, named for its shape from above. That is also where the rerouted Swift River rejoins its original bed and flows south.

The reservoir first reached the spillway in 1946, seven years after filling began on August 14, 1939, according to the MWRA. Under a 1931 U.S. Supreme Court settlement with Connecticut, the Friends of Quabbin chronology notes, Massachusetts agreed to keep the Swift River flowing below the dam with a release of 20 million gallons a day.

Walks Around the Dam

• Visitor Center Loop Trail (pink, 1.7-mile loop): starts inside the rotary on the dam, drops through hemlocks to the Swift River and the Y Pool, and climbs a ridge back to the visitor center.
• Spillway Trail (brown, 1.1-mile loop): from the Spillway Bridge, along the old bed of the Rabbit Run railroad, with a clearing that looks across the Y Pool to Winsor Dam.

Full trail details are on the trail map page.

Fly Fishing Below Winsor Dam

The Swift River from the Y Pool down to Route 9 is the one place in Quabbin Park where fishing is allowed, and it is open all year: fly fishing only, catch and release, from 4 a.m. to 9 p.m. Wading in waders is allowed. A no-trespassing zone surrounds the power station, and the river, the Y Pool and the Route 9 parking area are closed from 11 p.m. to 4 a.m. Reservoir fishing rules are separate; see the fishing guide.

A Short History

• 1926: Frank E. Winsor is appointed chief engineer of the Quabbin project (Friends of Quabbin).
• 1933: the Swift River Diversion tunnel goes into full use, bypassing water around the dam area (Friends of Quabbin).
• 1938: Goodnough Dike, the reservoir's second dam, is completed (DCR). A September hurricane raises the Swift River 15 feet at Winsor Dam (Friends of Quabbin).
• August 14, 1939: the reservoir begins to fill (MWRA). Winsor dies the same year.
• 1946: water first flows over the spillway (MWRA).
• 1988: a rededication of the Winsor Memorial is held during the "Year of Remembrance" for the four valley towns (Friends of Quabbin).

For the bigger story, see Quabbin history and Goodnough Dike.

Rules on the Dam

No dogs, even on a leash; no drones; no alcohol. Obey posted security signs. The dam is open during Quabbin Park's posted hours; see hours.