“The long-term protection of two highly valued ecosystems – the Vasse Wonnerup Wetlands and Geographe Bay – has motivated the development of this water quality improvement plan. Land-use changes as a result of urbanisation and more intensive agriculture in the south-west region have resulted in large loads of nutrients being discharged into the wetlands and bay. Without management intervention, this pollution is predicted to significantly increase over the next 20 years. Thus the purpose of this plan is to guide management strategies to reduce the total nitrogen and phosphorus loads being delivered to these important ecosystems.
This plan brings together the best-available scientific knowledge about the current water quality status of Vasse Wonnerup Wetlands, Geographe Bay and their waterways for the purposes of nutrient management planning. Water quality modelling tools developed by the Department of Water are used to provide a breakdown of each catchment’s nutrient sources and to identify how much nutrient reduction is required to prevent or alleviate water quality problems in each system. This modelling has established nutrient-load reduction targets for each catchment (shown on the next page) expressed as the required reduction in tonnes per year, and as the required percentage reduction of the current nutrient loads. These are ambitious targets that will require a concerted and cooperative effort if they are to be achieved.”