Date of this Version A survey in the Little Blue Basin
documented the presence of 22 extant or extirpated unionid
mollusk species. Bivalve habitat is severely impaired by surface
and subsurface water withdrawals, erosion, siltation, and
grazing. Chemical contaminants and other pollutants washed into
area streams from agricultural fields probably exert a further
deleterious impact upon the fauna of the region. Half of the
species recovered were represented only by chalky or badly
weathered shells, suggesting their possible elimination from the
basin. The generally poor condition of shells of many of the
remaining species suggests they are also in severe decline in
the region.