Risk assessments for impacts from non-sewered subdivisions

The Moreton Bay Waterways and Catchments Partnership commissioned the Queensland Department of Natural Resources & Mines to undertake a desktop review of modelling approaches for assessing the risk of nitrogen (N), phosphorus (P) and pathogen contamination of waterways from on-site wastewater systems in preparation for recommending the best approach. Twenty-seven models were reviewed and classified into seven basic approaches, (in order of increasing complexity) Hazard, Empirical, Mass balance, Analytical, Biophysical, Dedicated, and Integrated Systems. The strengths and weaknesses of each modelling approach, the competing methodologies, the scale and details of their predictions and field validation were assessed, considering the data and analytical requirements, applicability to SEQ region and ease of use, and the associated potential costs of application to SEQ.