Beaver Brook
Beaver Brook at the Collinsville Dam in Dracut, Massachusetts
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Location
Country	United States
States	New Hampshire, Massachusetts
Counties	Rockingham and Hillsborough, NH; Middlesex, MA
Towns and cities	Chester, Derry, Londonderry, Windham, Hudson and Pelham, NH; Dracut and Lowell, MA
Physical characteristics
Source
• location	Chester, Rockingham County, NH
• coordinates	42°57′18″N 71°16′36″W / 42.95500°N 71.27667°W / 42.95500; -71.27667
• elevation	435 ft (133 m)
Mouth	Merrimack River
• location	Lowell, Middlesex County, MA
• coordinates	42°39′30″N 71°19′6″W / 42.65833°N 71.31833°W / 42.65833; -71.31833
• elevation	55 ft (17 m)
Length	30.7 mi (49.4 km)
Basin features
Tributaries
• left	West Running Brook, Golden Brook, Peppermint Brook
• right	Shields Brook, Gumpas Pond Brook, Double Brook

Beaver Brook is a 30.7-mile-long (49.4 km) river located in New Hampshire and Massachusetts in the United States. It is a tributary of the Merrimack River, part of the Gulf of Maine watershed.

Beaver Brook rises in Chester, New Hampshire, and flows south into Derry, passing through Harantis Lake, Adams Pond, and Beaver Lake. Continuing south, the brook forms the boundary between Londonderry and Windham, then flows through Pelham.^[1] The brook crosses the state line into Dracut, Massachusetts, and reaches the Merrimack River in the city of Lowell.

Most of the brook's course is through gently hilly terrain that is rapidly being converted into suburban land use.^{[citation needed]}

• List of rivers of Massachusetts
• List of rivers of New Hampshire
• New Hampshire historical marker no. 58: Scotch-Irish Settlement