The Bellamy River, in Strafford County, southeastern New Hampshire, is a tributary of the Piscataqua River about 15 miles long. It rises in Swains Lake in Barrington, 9 miles west of Dover. It flows east through the Bellamy Reservoir in Madbury and through Dover, then southeast as a tidal river to Little Bay, the channel connecting Great Bay with the Atl…The Bellamy River, in Strafford County, southeastern New Hampshire, is a tributary of the Piscataqua River about 15 miles long. It rises in Swains Lake in Barrington, 9 miles west of Dover. It flows east through the Bellamy Reservoir in Madbury and through Dover, then southeast as a tidal river to Little Bay, the channel connecting Great Bay with the Atlantic Ocean. The river at one time provided water for swimming behind a dam at Bellamy Park in Dover. This park was a favorite spot for local neighborhood children and young adults, but fell into disrepair in the late 1960s. The Dover High School class of 1976 held a school-approved burning of the remains of the dam as a class activity.