The Rocky Mountain Ridged Mussel occurs from southern British Columbia to southern California and eastward to southern Idaho and northern Nevada in the United States. In Canada, this species is limited to the Columbia River system and its tributaries, including the Okanagan and Kootenay rivers. This species is probably also present in other similar areas in southern British Columbia.

The Rocky Mountain Ridged Mussel lives in fresh water. It is found in various sizes of lakes and streams in shallow water where the flow is constant and especially where the bottom is composed of fine material. The species seems to avoid murky, nutrient-rich water. This mussel will attach itself to gravel or firm mud on the bottom so long as this bottom also contains a small amount of fine material such as sand or clay; depending on how fine the bottom is, the mussel may bury itself partially or completely. It is not unusual to see individuals of all non-larval age classes together at a single location.

The Rocky Mountain Ridged Mussel is a large freshwater mussel. Its shell is trapezoidal and up to 12.5 cm long and 0.4 cm wide. It is typically rather thin, but can be up to 6.5 cm high toward the posterior. Like that of all other mussels, the shell of the Rocky Mountain Ridged Mussel is composed of two parts, known as valves, connected by a hinge. This hinge is medium-sized and has small, irregular, indistinct anterior teeth. The surface of the shell is marked by well-defined growth rings, and the dorsal valve is distinguished by a sharp, prominent ridge at the beak. In juveniles of this species, the outside of the shell is greenish or ochre, while adults are typically darker, becoming bluish-black. The inside of the shell is white tinged with coppery blue.

As with all freshwater mussels, the survival rate of the larvae is low. According to counts of annual growth rings, it is estimated that the adult can live up to 30 years.