The Squam River is a 3.6 miles (5.8 km) river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 located in central New Hampshire

New Hampshire

New Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It is the outlet of Squam Lake

Squam Lake

Squam Lake is a lake located in central New Hampshire, USA, south of the White Mountains, straddling the borders of Grafton, Carroll, and Belknap counties. The largest town center on the lake is Holderness...

, the second-largest lake in New Hampshire, and it is a tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Pemigewasset River

Pemigewasset River

The Pemigewasset River , known locally as "The Pemi", is a river in the state of New Hampshire, the United States. It is in length and drains approximately...

, which itself is a tributary of the Merrimack River

Merrimack River

The Merrimack River is a river in the northeastern United States. It rises at the confluence of the Pemigewasset and Winnipesaukee rivers in Franklin, New Hampshire, flows southward into Massachusetts, and then flows northeast until it empties into the Atlantic Ocean at Newburyport...

.

The Squam River first appears as a narrow channel in Holderness, New Hampshire

Holderness, New Hampshire

Holderness is a town in Grafton County, New Hampshire, United States. The population was 2,108 at the 2010 census. An agricultural and resort area, Holderness is home to the Squam Lakes Natural Science Center and is located on Squam Lake...

 between Squam Lake and Little Squam Lake

Little Squam Lake

Little Squam Lake is a water body located in Grafton County in the Lakes Region of central New Hampshire, United States, in the towns of Holderness and Ashland. The lake connects upstream via a short channel to Squam Lake in Holderness...

 downstream. The two lakes have the same elevation, due to a dam below the outlet to Little Squam, so the river in Holderness village is not free-flowing. Below Little Squam Lake the river proceeds south for over a mile before reaching the dam that controls the two lakes' water level. Below here it quickly reaches the backwater from a mill dam in the town of Ashland

Ashland, New Hampshire

Ashland is a town in Grafton County, New Hampshire, United States. The population was 2,076 at the 2010 census. Located near the geographical center of the state, Ashland is home to Scribner-Fellows State Forest....

.

In Ashland, the river drops 50 feet (15.2 m) in 0.2 mile (0.321868 km), sufficient to provide hydropower for numerous industries when the town originally grew in the 19th century. Below the center of town, the river wanders southeast under railroad tracks and Interstate 93

Interstate 93

Interstate 93 is an Interstate Highway in the New England section of the United States. Its southern terminus is in Canton, Massachusetts, in the Boston metropolitan area, at Interstate 95; its northern terminus is near St. Johnsbury, Vermont, at Interstate 91...

and past the Ashland sewage treatment plant before entering the Pemigewasset River.