"Merrimack River Watershed Assessment Study".pdf

The Merrimack River Watershed Assessment Study was conducted to evaluate existing conditions in the watershed, which covers 5,010 square miles in New Hampshire and Massachusetts. The study aims to identify planning-level benefits and costs of investment strategies to improve water quality and beneficial uses of the water. The watershed has a varied terrain and climate, with precipitation evenly distributed throughout the year, and temperatures varying widely on an annual basis. Land use is dominated by deciduous and evergreen forest (77%), with urban areas making up 10% of the total watershed area. The water quality of the Merrimack River has improved significantly since the 1960s, but further work is required to address issues such as pollution from urban runoff, natural sources, municipal point sources, and combined sewer overflow discharges. Elevated bacteria levels, low dissolved oxygen concentrations, and high nutrient levels are primary causes of non-supporting use in the basin.