NH Floods Information

Holding back the floods

New Hampshire has known flooding in the 20th century, but today it need not be as devastating. The state's worst flood, in March 1936, caused great damage, even leaving Manchester's West Side under water for days. After that, the state, with help from the U.S. Army Corps of Engineers, devised a flood control system using dams and reservoirs that allow officials to control storm and winter runoff and alleviate much of the threat of damaging floods.

Great NH Floods
Date	Rivers	Noteworthy
December 1740	Merrimack	First recorded flood in NH
Oct. 23, 1785	Cocheco, Baker, Pemigewasset, Contoocook and Merrimack	Set record for discharge at Lowell, Mass., that stood through 1902.
April 21-24, 1852	Winnipesaukee, Pemi, Contoocook, Blackwater and Ashuelot	Merrimack River at Concord highest in 70 years.
Nov. 3-4, 1927	Pemi, Baker, Ammonoosuc, Merrimack and Connecticut	Upper Pemi and Baker river levels exceeded 1936 flood.
March 11-21, 1936	Statewide	Double flood caused by rain and snowmelt.
April 1960	Merrimack, Piscataquog	Third highest flood on these rivers
Sept. 18-19, 1999	Central and southwest NH	Hurricane Floyd causes flooding in Belknap, Cheshire and Grafton Counties
October 2005	Monadnock region	Alstead one of the hardest hit. Four people were killed, 36 homes destroyed. In 30 hours, 12 inches of rain fell, making it the wettest month in NH history to date, with 14.5 inches. Experts called the flood a once-in-500-years event.
May 2006	Statewide	Gov. John Lynch declared a state of emergency, May 14, 2006, after torrential rainfall throughout most of New Hampshire forced evacuations and washed out roads.