Abstract: Key findings for the Fitzroy catchmentIntroduction The Fitzroy catchment covers an area of approximately 94,000 km2. The Fitzroy River flows more than 700 km from its upper reaches to King Sound. The population is approximately 7500 people with two main population centres at Derby and Fitzroy Crossing. The dominant land use is pastoralism (over 95% of the catchment) with natural and conservation uses prioritised in the remaining areas.Indigenous people have continuously occupied and managed the Fitzroy catchment for tens of thousands of years and retain significant and growing rights and interests in land and water resources, including crucial roles in water and development planning and as co-investors in future development.Agriculture and aquaculture opportunitiesThe Fitzroy catchment has up to 5.4 million ha of potentially irrigable agricultural soils. Of this land area, 4.0 million ha are suitable for spray irrigation of cereals, between 400,000 ha and 590,000 ha for furrow irrigation of cereals, 2.8 million ha for spray-irrigated sugarcane, and about 400,000 ha for sugarcane with furrow irrigation. For aquaculture, such as prawns and barramundi, about 55,000 ha of land are suitable using lined ponds. For all of these uses the land is considered moderately suitable with considerable limitations and would require careful soil management.Livestock enterprises are already proven in the Fitzroy catchment. The use of irrigated forage (Figure 1-1) to overcome the feed gap, especially for lactating cows, could significantly increase beef production by increasing calving percentage, enabling earlier weaning and increasing rate of weight gain.Up to 120 GL/year of groundwater (<5% of recharge) could be extracted from the interconnected Grant Group and Poole Sandstone aquifers. Under a wet season sowing on loamy soils, this volume of water could irrigate about 20,000 ha of a crop such as cotton at an annual gross value of production of approximately $90 million, creating about $140 million of regional economic activity reoccurring annually and the generation of about 560 jobs. There is up to 50 GL/year of additional groundwater across the catchment that would allow numerous small (<1 GL) to medium-scale (1 to 5 GL) developments suited to irrigated forage production.It is physically possible to pump 1700 GL of water in 85% of years from major rivers and tributaries in the Fitzroy catchment into ringtanks near agricultural soils. This volume of water would fill 425 ringtanks (each of capacity 4 GL) and cost approximately $935 million. This would enable 160,000 ha of clay soils under dry-season cotton to be irrigated. This could generate an annual gross value of production of approximately $750 million, and the region would benefit from $1.1 billion of additional annual economic activity and generation of about 4700 jobs.Impacts and risksWhether based on groundwater or offstream storage, irrigated agricultural development has a wide range of potential benefits and risks that differentially intersect diverse stakeholder views on ecology, economy and culture. The detailed reports upon which this catchment report is based provide information that can be used to quantify the trade-offs required for agreed development plans.Streams, wetlands and riparian areas remain of critical importance to Indigenous people. They have cultural significance and provide nutritional food. These habitats are also key to the movement of animals, plants and nutrients through a highly interconnected system, keeping the ecosystem healthy, supporting critical downstream habitats like mangroves and salt flats and providing food for recreational and commercial fishing. The catchment harbours a diverse assemblage of fish. Forty-two different species have been recorded, many of which depend on being able to move up and down the river systems to complete their life cycle. Many of the fish species are dependent on the highly seasonal flow pulses that characterise the Fitzroy River. King Sound and the adjacent Fitzroy catchment is one of the few known remaining habitats for the early life stages of the remnant population of freshwater sawfish.
Petheram, Cuan, Bruce, Caroline, Chilcott, Chris, Watson, Ian, 2018, Water resource assessment for the Fitzroy catchment: A report to the Australian Government from the CSIRO Northern Australia Water Resource Assessment, part of the National Water Infrastructure Development Fund: Water Resource Assessments, Report, viewed 18 August 2022, https://www.nintione.com.au/?p=14891.