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
From the 1830's, pastoralists began squatting on the Castlereagh, commonly moving north-westerly from the Mudgee area moving cattle onto land along the river, cared for by employed men who were often assigned convicts or ex-convicts. The area was at that time outside the official nineteen counties limits of settlement. This meant that pastoralists sending their stock westwards were technically squatting illegally, taking the land for free. In these early days it was mostly the established pastoralists who had access to land information through their friends and contacts in the highest government levels, and who had sufficient capital to own stock already, or buy more, and who were able to send animals and men up-country with supplies for long periods. In 1836, the government realised it had lost the game in terms of keeping settlement within specified areas (thereby limiting its own obligations); so it established a system of pastoral licences requiring the payment of a licence fee and capping 'run' sizes at 16,000 acres. Existing squatters overcame the size limitation by dividing their stations into different areas of 16,000 acres each.