Final Report - Hyacinth Recovery and Reuse Pilot - Cooperative Research Centre for Developing Northern Australia

Summary

Water hyacinth is an invasive aquatic weed that was introduced as an ornamental plant but once it entered waterways has a long-term impact due to the rate of growth, density of biomass and seed life. The Fitzroy River has seen rafts of weed up to 1km long that block recreational use, impact on irrigators and result in poor water quality when it enters the estuarine reach and dies. The continual supply of nutrient and ideal growing conditions provides an almost year-round growing season for the weed.

The weed is likely “here to stay” however the use of the weed as a vector for the removal of nutrient from the waterway and reuse of this nutrient in lieu of imported nutrient for cropping and grazing will contribute to improved water quality flowing to the Great Barrier Reef.

The aim of this project is to identify and evaluate methods for the beneficial reuse of water hyacinth in the Fitzroy River including effective removal, dewatering, utilisation as a nutrient and/or carbon source, understanding of the risks associated with a declared weed and estimation of potential scale up challenges. Answer longer term questions including, is there potential for the extraction of the weed to become a cost-neutral exercise, will the harvesting reduce the impacts of the weed on native flora and fauna, what are the factors that contribute to the regrowth of the weed / the location of the weed and modelling of the benefits to water quality.

Making Water Work: Integrating nutrient, waste and energy streams in agriculture development through hyacinth harvest and processing

This project investigated how invasive water hyacinth in the Fitzroy River could be transformed from an environmental management challenge into a productive agricultural resource. Originally introduced to Central Queensland as an ornamental plant, water hyacinth has become a significant aquatic weed due to its rapid growth, dense biomass and long-lived seed bank, reducing waterway health, impacting ecosystem condition and creating ongoing management costs for land managers and local councils. The project explored practical pathways for harvesting and reusing water hyacinth biomass, with a focus on its potential as a soil ameliorant for agricultural production in the Lower Fitzroy region. By removing nutrient-rich biomass from the waterway, the project also examined opportunities to reduce nutrient loads in the Fitzroy catchment, improve water quality flowing to the Great Barrier Reef and support healthier aquatic ecosystems. Research findings highlighted strong potential for water hyacinth to be repurposed into agricultural products such as compost, mulch and biochar, reducing reliance on imported soil amendments while supporting more circular approaches to land and water management. The project also assessed the economic feasibility of different beneficial end uses, including a cost-benefit analysis of harvesting and processing pathways to identify realistic implementation opportunities. By linking invasive weed management with nutrient recovery and agricultural development, the project provides a practical model for turning an environmental liability into a productive resource, with potential benefits for water quality, farming productivity, waste reduction and regional resource efficiency across northern Australia.