Euastacus dharawalus is NSW’s rarest spiny crayfish species and in 2006 the Australian Crayfish Project identified an additional threat of significance to this species. Euastacus dharawalus is only found in one small stream (Wildes Meadow Creek) roughly 11 km long above Fitzroy Falls. The Falls is an 80 m straight drop and we surmise that E. dharawalus is just a remnant population isolated from all the other species in the surrounding area by the barrier of the falls.
A water supply reservoir was constructed on this small creek as part of the supply of drinking water to Sydney. This huge reservoir on the tiny creek has significantly altered the hydrology of the area and impacted on the states rarest spiny crayfish. Now, to exasperate the problem an invasive crayfish species The Yabby Cherax destructor has been introduced to the area and it has gone forth and multiplied creating an ongoing and growing threat to the endemic Euastacus dharawalus.