The clubshell was once found from Michigan to Alabama and from Illinois to West Virginia.  The northern riffleshell occurred throughout the Ohio River Valley and north into Michigan.  Both species’ populations have declined dramatically throughout their range due to declining habitat quality. 

Because of the mussels’ rapid decline and highly isolated populations, the Service believes the augmentation and reintroduction of the clubshell and riffleshell will be an essential tool in upgrading their status to threatened, and eventually, in recovering the two species.