The warf wedgemussel, Alasmidonta heterodon, is an endangered species of freshwater mussel. It is a rare species found solely in North America's Atlantic coast streams and rivers of various sizes and moderate current. The dwarf wedgemussel's current range extends from New Hampshire to North Carolina. In May 2000, the Canadian Species at Risk Act listed the Dwarf Wedgemussel as being extirpated in Canada. This mussel may be found in small creeks to deep rivers in stable habitat with substrates ranging from mixed sand, pebble and gravel, to clay and silty sand. In the southern portion of its range, it is often found buried under logs or root mats in shallow water (USFWS 1993), whereas in the northern portion of its range, it may be found in firm substrates of mixed sand, gravel or cobble, or embedded in clay banks in water depths of a few inches to greater than 20 feet (Fichtel and Smith 1995; Gabriel 1995; Gabriel 1996; Nedeau and Werle 2003; Nedeau 2004a, 2004b, 2006).