This is the Merrimack river, a medium sized river that is the dominant
geographic feature of the area I live in, cleverly known as the Merrimack
Valley. It has quite a history, too. It fueled huge textile mills and made
Lawrence and Lowell (MA, USA) two of the leading textile producing cities of
the late 19th and early 20th century. In the 1970s, it was so polluted it
caught fire, and nearly burned down a bridge. It's much cleaner now, and a
major source of water, electricity, and recreation.