[2][3][4][5] The flow of the river is impounded by Copeton Dam, with storage used for town water supply, stock, domestic use and irrigation.

Further distributaries above Moree are the Carole which then joins with the GilGil Creek to the north that flow into the Barwon River when during times of high rainfall/runoff or water deliveries.

Explorer Allan Cunningham crossed the river at Gravesend in 1827 and named it after his patron, Peter Burrell, Baron Gwydyr (Welsh pronunciation: [ˈɡwɪdˈiː.ər]), who took his title from Gwydir Castle in Wales.

Aborigines in the district were repeatedly pursued by parties of mounted and armed stockmen and Day claimed that great numbers of them had been killed at various spots.

It also reduced or stopped periodical flushes of water into ephemeral creeks, watercourses and wetlands in the Gingham, Lower Gwydir and Mallowa and other smaller systems.

[9] Some 1,021 square kilometres (394 sq mi) of the Gwydir Wetlands have been identified by BirdLife International as an Important Bird Area because, when they receive adequate water inflows, they support more breeding waterbirds than any other site in the country.

At times more than half a million nesting waterbirds have been present, including over 1% of the world populations of nankeen night herons, intermediate egrets, and of white and straw-necked ibises.