The Arrowsmith River catchment lies between the Hill River to the south, and the Irwin River to the north. The headwaters of the Arrowsmith River are just west of the town of Three Springs and the river then flows west for 85 km. Approximately the upper third of the Arrowsmith River is a gaining river, meaning at least part of its surface flow is supplemented by groundwater. This area is an important source of groundwater for a variety of uses.
The Arrowsmith river is an internally draining river, and it terminates at Lake Arrowsmith about 10 km inland of Cliff Head on the coast. Average annual rainfall is about 500 mm near the coast, falling to about 375 mm further inland. Catchment land area is just over 1,600 km2, most of which is used for non-irrigated cropping with some grazing, particularly in the upper catchment to the east. Much of the lower catchment, in the west, is conservation and minimal land use, and a large area of plantation forest (managed resources) lies in the centre of the catchment.