With the population of the Caboolture River catchment expected to increase by over 100,000 people in the next 20–25 years, Unitywater faced a growing challenge: how to sustainably manage the effluent produced by the South Caboolture Sewage Treatment Plant (STP). Although effluent is A-grade and suitable for a range of non-potable uses, without intervention, the increased nutrient loading could threaten the health of the Caboolture River and downstream waterways. 

To address this, Unitywater launched the Wamuran Irrigation Scheme (WIS)—a circular economy initiative to beneficially reuse treated effluent in agriculture. Verterra was appointed to provide deep expertise in agronomy, irrigation, land capability, and environmental planning to help guide the project’s success. 

This client sought an innovative, sustainable, and community-aligned solution for the beneficial reuse of A-grade effluent from a Sewage Treatment Plant, located just 10 km upstream of a major drinking water supply dam. Rather than pursuing a conventional advanced treatment facility, Verterra delivered an award-winning, nature-based solution.

In regions of Australia where rainfall is unreliable, treated wastewater (effluent) is increasingly recognised as a valuable resource—particularly for irrigating tree crops and other vegetation. However, to safely and effectively reuse effluent for irrigation, its quality must be carefully monitored and managed. This case study demonstrates how Verterra approached successfully undertook risk assessment and development of a management plan that would enable its beneficial reuse for a forest plantation.

Northern Australia is considered a high-potential region for expanding irrigated agriculture due to the availability of rainfall and relatively undeveloped land. However, increasing land under irrigation can elevate the risk of sediment, nutrient, and pesticide runoff—particularly into sensitive waterways that feed into the Great Barrier Reef.  In this case study, Verterra demonstrates how a thorough understanding of environmental risk is the first step to designing irrigation schemes with minimal off-site impact.