Merrimack River Watershed Flood Data

Below are three examples of historic data from the Merrimack River Watershed.

Merrimack River at Lowell, MA

According to NOAA, the weekly chance of exceeding river stage at this location through 12/16 will stay well below even minor flooding range (NOAA, 2024). With minor flooding being 52ft, moderate flooding being 54ft, and major flooding being 58ft, you can see from recent crests (below) that the most severe flooding in this location since 2000 was in 2006, with moderate flooding (NOAA, 2024).

Image source: NOAA, 2024

The highest crest ever in 1936 is known as the "Great Flood," and more information can be found in the following links (LibGuides, n.d.):

• https://libguides.uml.edu/Isolation_Hospital/Lowell_Flood_1936

• https://www.facebook.com/LowellHistoricBoard/posts/on-this-day-in-1936-the-great-flood-struck-lowell-as-the-merrimack-river-crested/3109971302370090/

• https://www.lowellsun.com/2016/05/12/remember-when-flood-of-1936-slideshow/

Merrimack River at Haverhill, MA

While Haverhill is still not predicted to have a weekly chance of exceeding river stage reaching even minor flooding, the chances are significantly closer than they are in Lowell (NOAA², 2024). Major flooding in this area does not take much, with the elevation being 18ft (NOAA², 2024). Moderate flooding is 16ft and minor flooding is 13ft (NOAA², 2024). The historic crest of 27.75ft shown below is the same as the Great Flood listed above.

Image source: NOAA², 2024

The flooding in 2006 was known as the "Mother's Day Flood," impacting a variety of Massachusetts towns, including Haverhill (Eagle Tribune, 2016). More information can be found in the following links:

• https://www.eagletribune.com/photos-2006-mothers-day-flood/collection_7529f65e-13c0-11e6-ade5-4369c6154e1e.html

• https://www.facebook.com/watch/?v=10156472993517010

Merrimack River at Goffs Falls, NH

The Merrimack River at Goffs Falls has experience some flooding in more recent years, with minor flooding at 11ft, moderate flooding at 15ft, and major flooding at 17ft (NOAA³, 2024). Weekly chances of exceeding river stage here are similar to Haverhill (NOAA³, 2024). Many of the high points are for the same major floods listed above on the same dates.

Image source: NOAA³, 2024

The following source is a letter from the governor of NH to the President of the United States, seeking to declare a major disaster for the flooding that took place in December 2023 (State of New Hampshire, 2024):

https://www.nh.gov/safety/divisions/hsem/documents/december-2023-disaster-request.pdf

Sources:

• LibGuides. n.d. The "Great Flood" 1936. https://libguides.uml.edu/Isolation_Hospital/Lowell_Flood_1936

• NOAA. 2024. Merrimack River at Lowell. https://water.noaa.gov/gauges/lowm3

• NOAA². 2024. Merrimack River at Haverhill. https://water.noaa.gov/gauges/HVRM3

• Eagle Tribune. 2016. PHOTOS: 2006 Mother's Day Flood. https://www.eagletribune.com/photos-2006-mothers-day-flood/collection_7529f65e-13c0-11e6-ade5-4369c6154e1e.html

• NOAA³. 2024. Merrimack River at Goffs Falls. https://water.noaa.gov/gauges/GOFN3

• State of New Hampshire. 2024. State of New Hampshire Office of the Governor. https://www.nh.gov/safety/divisions/hsem/documents/december-2023-disaster-request.pdf