In Canada, the yellow lampmussel is only known in two locations: the Sydney River, Cape Breton, Nova Scotia and the lower Saint John River near Fredericton, New Brunswick. Blackett's Lake, formed when the Sydney River was dammed in 1902, is the main centre of the yellow lampmussel population in Nova Scotia. Most of the Canadian population of yellow lampmussel is found below the head-of-tide in the main Saint John River, including five of its large tributaries and several large lakes.

The yellow lampmussel has an oval-shaped shell and an exterior glossy surface that varies in colour from bright yellow to reddish brown. The interior is coloured white to pink and has several strong hinge teeth. The soft parts of the body, called the mantle, are visible between the shell valves in living animals. The visible edges of the mantle are smooth and pigmented with grey streaks and dots. Although the yellow lampmussel has been observed as large as 110 mm in length, it is typically approximately 75 mm. The yellow lampmussel can live up to 17 years.