Deciding between options to reduce P in the Gippsland Lakes

A target to reduce phosphorus (P) flows into the Gippsland Lakes in south-eastern Australia by 40% in order to improve water quality has previously been established by stakeholders. This target has been set mostly on the basis of environmental concerns, with limited consideration of issues such as technical feasibility, socio-economic constraints, political factors and associated costs and benefits. An integrated analysis at the catchment scale was undertaken to
evaluate the feasibility and cost-effectiveness of different options.

While it’s technically feasible to achieve a 40% reduction in P load entering the Lakes, the least-costly way of doing so would cost a billion dollars over 25 years. This represents a dramatic increase in the current levels of funding provided for management. On the other hand, a 20% P reduction could be achieved at much lower cost: around $80 million over 25 years and requiring more modest land-management changes.

Reliance on voluntary adoption of ‘Current Recommended Practices’ is unlikely to deliver changes in management practices at the scale required to have sufficient environmental impacts. Enforcement of existing regulations for the dairy industry would be amongst the most cost-effective management strategies.

The major implications of this work for agriculturally induced diffuse-source pollution include the need for feedback between goal setting and program costs, and consideration of factors such as the levels of landholder adoption of new practices that are required and the feasibility of achieving those adoption levels. Costs, landholder adoption of new practices and socio-political risks appear neglected in the formulation of many water quality programs.

Roberts AM, DJ Pannell, G Doole & O Vigiak (2012). Agricultural land
management strategies to reduce phosphorus loads in the
Gippsland Lakes, Australia. Agricultural Systems 106: 11–22.

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