EPA’s Lower Merrimack River Initiative
Water quality and other information for the Merrimack River in southern New Hampshire and Massachusetts: https://www.epa.gov/lowermerrimackriver
Watershed Report Cards (2008, 2010, 2012)
Surface water quality assessment reports are available for 12-digit Hydrologic Unit Code (HUC) watersheds.
2010 Designated River Surface Water Quality Report Cards