More types of fish and mollusks are found in French Creek than any other stream in Pennsylvania. The Watershed is home to 27 species of mussels, 15 species of darters, and four important bird areas (IBA). Many species that thrive in French Creek have been extirpated from their natural ranges due to habitat loss and degradation of water quality. Nevertheless French Creek remains relatively healthy, leading The Nature Conservancy to include the French Creek Watershed in its listing of national “hot spots” with ten or more at-risk fish and mussel species, and citing it as a critical watershed to conserve these species.