The Quaboag River is a Massachusetts river that heads at Quaboag Pond south of East Brookfield, Massachusetts at an elevation of 594 feet (181 m) MSL. It continues to the town of Three Rivers, Massachusetts, at an elevation of 290 feet.
The Quaboag River heads at Quaboag Pond, flows through the towns of Brookfield, West Brookfield where Lake Wickaboag drains into it, and Warren before joining the Ware River and Swift River in Three Rivers, to form the Chicopee River. This river is therefore part of the Chicopee River Watershed.
Numerous local brooks and streams from the towns of East Brookfield, Brookfield, West Brookfield, and Warren drain the watershed into the Quaboag River. Lake Lashaway in East Brookfield drains into Quaboag Pond and several other significant water sources drain into it. There are also several wetlands associated with this watershed, the two mayor ones being the Great Swamp south of Brookfield, and the Allen Swamp south of East Brookfield.
Whitewater kayakers and canoeists paddle the Quaboag from a put-in at Lucy Stone Park in Warren, downstream to a take-out along Route 67. The river is Class III and features several named rapids, Mousehole and Trestle Rapid above the dam, and, downstream, Angel's Field and Devil's Gorge, which contains an abrupt three-foot waterfall called Quaboag Drop. The river has a large watershed, holds its water well (is well formed), and is paddleable at levels above four feet on the Brimfield USGS gauge. It contains one mandatory portage around an unrunnable dam next to a factory.