"[1][2][3] The uppermost tributaries of the Quinapoxet River rise in the town of Princeton, Massachusetts, the watershed generally known as the Upper Worcester Plateau, or the Monadnock Upland.

The Quinapoxet and Stillwater rivers are the two major tributaries to the Wachusett Reservoir, which serves as the primary source of water for 2.5 million consumers in 43 communities of central and eastern Massachusetts.

The U.S. Geological Survey, in cooperation with the Massachusetts Department of Conservation and Recreation, operates stream-flow monitoring gages near the mouths of both rivers.

The City of Worcester owns the land that immediately surrounds each of its reservoirs and approximately 25% of its entire water supply watershed.

Chaffins Brook is considered a "moderately septic polluted stream", and its lower reach has noxious aquatic plants in an impoundment.