Castlereagh River
The Castlereagh rises 20 km west of Coonabarabran in the heart of the Warrumbungle mountains at an elevation of about 850 metres. From its commencement upstream in the mountains the river initially flows east through the town of Coonabarabran. It then arcs round south and southwesterly to the village of Ulamambri, then south to Binnaway, and SSW to the small town of Mendooran which lies at the eastern side of the river's hook-shape. From here the Castlereagh flows in a westerly direction at the flattened bottom of the hook and then turns north-westerly towards the town of Gilgandra. From Gilgandra it continues to run northwesterly across the plains through Gulargambone and Coonamble, then continuing across expansive plains, with no urban centres, where elevations are less than 200m, until it joins the Macquarie River at its uppermost reaches beyond the Macquarie Marshes. Its confluence with the Macquarie is about 65 km SW of Walgett. Not far from the Castlereagh/Macquarie confluence the Macquarie itself joins the Barwon River at a place about halfway between Walgett and Brewarrina.
Castlereagh River
The first European record of Aboriginal people along the Castlereagh came through the John Oxley exploration party of 1818. Waiting for waters in the Castlereagh near present-day Coonamble to recede, Oxley wrote on 27 July 1818 that ""Natives appear to be numerous; their guniahs (or bark-huts) are in every direction, and by their fire-places several muscle-shells of the same kind as those found on the Lachlan and Macquarie Rivers were seen. Game (kangaroos and emus), frequenting the dry banks of the river, were procured in abundance"." At the time, Oxley's party was camped at the banks of the Castlereagh River, and the spot is today marked with a memorial stone 2 km north of the town. After finally crossing the river on 3 August and heading easterly towards the Warrumbungle mountains, Oxley wrote the next day: ""The natives appear pretty numerous: one was very daring, maintaining his ground at a distance armed with a formidable jagged spear and club, which he kept beating against each other, making the most singular gestures and noises that can be imagined: he followed us upwards of a mile, when he left us, joining several companions to the right of us. Emus and kangaroos abound, and there is a great diversity of birds, some of which have the most delightful notes, particularly the thrush.""