Souhegan River at Merrimack, NH
River level and flood forecast · Hillsborough County
The river is 6.3 ft below flood stage (9 ft).
Forecast to rise to 3.0 ft Wed 8 PM, below the 9 ft flood stage.
Flow: 110 cubic feet per second (USGS).
Higher than normal for October 13.
Usual for October 13: 27 to 97 cubic feet per second (the middle half of 92 years).
The last 7 days and the forecast
NWS forecast issued Mon, Oct 12, 11:14 AM. Forecasts change as rain falls and as upstream water arrives.
Get flood alerts for this river
An email when the National Weather Service forecasts Souhegan River at Merrimack to flood, when it floods, and when it's over.
Flood stages
| Major flood stage | 13 ft |
| Moderate flood stage | 11 ft |
| Flood stage | 9 ft |
| Action stage | 8 ft |
| Record crest (March 19, 1936) | 16.2 ft |
What floods at each level
From the National Weather Service, highest first.
- 13 ftSignificant flooding affects homes in the area of Beacon Drive in Merrimack. Other low lying sections upstream into Amherst and Milford experience flooding.
- 11 ftIn Merrimack, homes in the Beacon Drive area flood. Other low lying areas upstream into Amherst and Milford flood.
- 10 ftIn Merrimack, several homes along a small portion of Beacon Drive begin to flood. In Amherst, low lying areas begin to flood.
- 9 ftFlooding of low lying areas along the river begins in the town of Merrimack.
Highest crests on record
- 16.2 ft — March 19, 1936
- 12.78 ft — September 21, 1938
- 12.71 ft — April 17, 2007
- 11.82 ft — April 8, 1924
- 10.88 ft — June 25, 1944
Recent crests: 8.57 ft (December 19, 2023) · 7.52 ft (December 26, 2020) · 7.3 ft (December 15, 2019) · 7.26 ft (January 25, 2019) · 8.14 ft (October 31, 2017)
Highest flow on record
16,900 cubic feet per second — March 19, 1936. From the USGS's yearly peaks since 1910.
Up and down the river, and nearby
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (SOHN3); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.