Salmon, shad, and alewives were formerly abundant here, and taken in weirs by the Indians ... until the dam and afterward the canal at Billerica, and the factories at Lowell, put an end to their migrations hitherward; though it is thought that a few more enterprising shad may still occasionally be seen in this part of the river.... Perchance, after a few thousands of years, if the fishes will be patient, and pass their summers elsewhere meanwhile, nature will have leveled the Billerica dam, and the Lowell factories, and the Grass-ground River run clear again, to be explored by new migratory shoals.
Henry David Thoreau (1817–1862), U.S. philosopher, author, naturalist. A Week on the Concord and Merrimack Rivers (1849), in The Writings of Henry David Thoreau, vol. 1, p. 32, Houghton Mifflin (1906).
Thoreau here translates the local Native American name, "Musketaquid" ("Grass-ground River"), for the Concord River.