The Souhegan is a Protected River. What does that mean?

You may have seen the signs saying Protected River as you drive over the Souhegan. The State has selected approximately 20 rivers across New Hampshire for preservation of the water, shorelines, and adjacent lands. There are many aspects of this conservation work, and most of it is done by local volunteers. The Souhegan Watershed Association sponsors sampling of water across the watershed to evaluate the health of the ecosystem and the river’s suitability for paddling, fishing, and swimming. Volunteers observe, make a difference, and have fun. Contact us through the SWA website or Facebook if you're also interested in preserving our wonderful river.

https://www.des.nh.gov/water/rivers-and-lakes/rivers-management-and-protection
NH Designated River Corridor Web Map
https://www.souheganriver.org/
https://www.facebook.com/groups/souheganriver

Our latest water sampling was completed on Tuesday, August 5, 2025, and lab processing took another day.

E. coli Levels Summary.
The Souhgan’s water was generally at acceptable and typical E. coli spec levels. The usual hotter areas were along Keyes Park in west Milford, and the river’s middle course through Amherst. This session, the E. coli levels in these areas were in the 300s MPN. According to NH DES specs for safe swimming, E. coli MPN levels should be under 88. Unfortunately, two of the four places we observed folks swimming were in the 300’s.. The other two swimming holes, Wildcat Falls and Watson Park, both in the Town of Merrimack, had safe swimming levels of fecal bacteria.

The lower NH Merrimack River had exceptionally low levels of E. coli, except for a high number at the Goff's Falls sample site. Low levels are typical of the Merrimack River when there is no active rainfall runoff or sewer inflow.

This session's E. coli, Dissolved Oxygen, and pH results spreadsheet is available for viewing via the links below.

https://docs.google.com/spreadsheets/d/1s696Ay3umiR_DJBhjEzApq9BJtf54qh4pgYuSc7BV6I/edit?usp=drive_link

Sampling Locations

https://www.google.com/maps/d/...