Pacifastacus leniusculus leniusculus is distributed throughout British Columbia in Canada, and in California, Idaho, Oregon, and Washington in the USA. Pacifastacus leniusculus klamathensis is distributed throughout British Columbia in Canada, Idaho and south to central California in the USA. Pacifastacus leniusculus trowbridgii is distributed throughout British Columbia in Canada and California, Idaho, Oregon and Washington in the USA, and has been introduced into California and Nevada in the USA, and also introduced into Japan. Furthermore, this species is also known to occur in Greece (Koutrakis et al. 2007).

Pacifastacus leniculus has been introduced into many countries throughout Europe, as well as to California, Nevada and Utah in the USA. This species was introduced during the 1970s and 1980s, is widely cultivated and is established in the wild, from where it is harvested (Harlio?lu and Holdich 2001).