sentences:  The river is one of the few major rivers close to Perth which is devoid of dams for public water supply.It includes a catchment area including a large part of the wheatbelt and southwest of the state, draining from /year average rainfall country in the east near Pingelly, westward through the high rainfall parts of the Darling Range around Dwellingup with an average rainfall of /year.The first of the two major tributaries, the Hotham River, starts its journey near Narrogin.