The Goulburn Broken Catchment irrigation system, northern Victoria, Australia

The GB catchment covers 2.1 million hectares in the Murray-Darling Basin in Australia. Aboriginal people lived in the catchment for millennia before colonization around 1830.  The upper, mountainous area of the catchment (900 000 ha) is more than 50% forested. The mid catchment (1 million ha) of riverine plains, low slopes and foothills has less than 20% of native vegetation cover remaining, which is highly fragmented, and the rest is used for dryland cropping and grazing. The Shepparton irrigation region is adjacent to the Goulburn and Murray Rivers in the lower catchment (about 500,000 ha) with about 2% native vegetation cover and 300,000 ha used for irrigated dairy and fruit production. It is a very productive region, and a major contributor to the economy of Victoria and Australia.

The main social dilemma faced by the region is that past clearing of native vegetation has caused saline water tables (the groundwater system is a CPR) to rise, threatening crop production. Groundwater pumping is necessary but leads to discharging salt into the Murray River (salt removal capacity of the river is a CPR) at levels that can be unacceptable to downstream users . The recent drought has reduced the immediate threat of rising water tables, but resulted in insufficient water for irrigation. Climate change threatens the future viability of irrigation.