Publications by Year
Preliminary materials budget (nutrients and sediments) in the Ord River: Implications for current and proposed irrigation areas.
An ecological risk assessment (ERA) was undertaken of the impacts of irrigation return on the Lower Ord River catchment. A materials budget (mass balance) for nutrients and sediment was prepared for the…
An ecological risk assessment (ERA) was undertaken of the impacts of irrigation return on the Lower Ord River catchment. A materials budget (mass balance) for nutrients and sediment was prepared for the ERA process to establish the relative contribution of irrigation return to the catchment. The Ord River Dam (forming Lake Argyle) effectively splits the River catchment into two sections. The lower section ranges from downstream of the Ord River Dam to near Carlton Crossing (the upper extent of the salt wedge). This section receives irrigation return from the Ivanhoe Plains and Packsaddle Plains areas and will be the focus of this study. In addition, runoff from rangelands enters through several creeks and the Dunham River. All relevant water quality and flow data from the irrigation area or River were used to prepare the budgets. A high degree of interpolation and assumption was necessary due to the limited data availability, which limits the accuracy of the final budgets. Despite this, it appears that irrigation return water is a substantial contributor of Phosphorus (P) and nitrate/nitrite to the Lower Ord River. In comparison with rangelands, the irrigation area produced significantly higher loads of P, nitrate/nitrite and suspended sediment per unit area and in total. The return water produced a detectable increase in river P and nitrate/nitrite concentrations. This paper will discuss the impact of these results on current planning for the development of Ord Stage II and in moves towards best management practices within the current irrigation area.