Visited in 1791 by convicts, who called it the Coal River, it was renamed in 1797 for John Hunter (colonial governor, 1795–1800). The coal outcrops found by these early visitors were being worked by 1800. The most important mines are in the Singleton–Muswellbrook–Denman “triangle,” but the mines on the lower river between Cessnock and Maitland were important in establishing the Newcastle iron and steel industry. Six major thermal electricity generating plants in the area make it a major exporter of power to other parts of the state. The valley also supports diverse agriculture, including fruit orchards and wine vineyards. Cattle, sheep, and horses graze the upper valley, where timber is also cut. The riverine flats of the middle and lower reaches below Singleton are devoted to dairying and forage crops—corn (maize), hay, and lucerne (alfalfa). Poultry raising is the largest agricultural industry in the area, followed by beef production. Overcutting of timber has contributed to severe flooding, and control measures, such as Glenbawn Dam (1958), have been installed. Erratic seasonal changes in its level seriously limit navigation on the Hunter, but its valley is served by a rail line and two highways to Sydney.