It is a tributary of Lake Winnipesaukee, part of the Merrimack River watershed.

The Melvin River lies entirely within the town of Tuftonboro.

It begins at the outlet of Melvin Pond, near the town's eastern border, and flows west along the base of the Ossipee Mountains to the north.

The river reaches Lake Winnipesaukee at Melvin Village.

This article related to a river in New Hampshire is a stub.