The Newfound River is a 3.2-mile-long river in central New Hampshire in the United States. It is a tributary of the Pemigewasset River, part of the Merrimack River watershed. The Newfound River begins at the outlet of Newfound Lake in Bristol, New Hampshire. The river drops rapidly through the town of Bristol, passing over several hydroelectric dams before re…The Newfound River is a 3.2-mile-long river in central New Hampshire in the United States. It is a tributary of the Pemigewasset River, part of the Merrimack River watershed. The Newfound River begins at the outlet of Newfound Lake in Bristol, New Hampshire. The river drops rapidly through the town of Bristol, passing over several hydroelectric dams before reaching the Pemigewasset.