The Squannacook and Nissitissit Rivers are major tributaries to the Nashua River, and their health is of key overall importance to the Nashua River watershed. The combined inter-state Squannacook-Nissitissit sub-basin is 132 square miles, includes headwaters, and spans five MA towns (Ashby, Groton, Pepperell, Shirley, Townsend) and six NH towns (Brookline, Greenville, Hollis, Mason, Milford, New Ipswich).

The MA portion of the sub-basin is designated Outstanding Resource Waters. The growth rate in the MA towns in the sub-basin is projected to be 25-40% through 2010, in the NH towns 40-70%. Approximately 70% of the sub-basin is forested, with only 10-25% actively managed.

For the location of the Squannacook and Nissitissit Rivers in the Squannacook and Nissitissit Rivers watershed, see our watershed map.