Document Type

Conference Proceeding

Publication Date


Conference Title

Presented at the 7th International RiverSymposium, Brisbane Australia, Aug 31st – 3rd Sept 2004


Best management practices; cost-effectiveness; nutrient management; modelling


Agriculture | Environmental Indicators and Impact Assessment | Natural Resources Management and Policy | Water Resource Management


Algal blooms in south west Western Australia are a symptomatic response to excess nutrient input. Whilst a range of Best Management Practices (BMPs) are available to address the causes of nutrient pollution, most investment has been directed towards symptoms. In order to treat nutrient pollution causes effectively it is important to evaluate possible nutrient reductions and costs, and to determine whether accrued benefits can influence BMP adoption. Models were developed for catchments near Albany (south coast of Western Australia), and for the Peel-Harvey catchment (70 km south of Perth) to estimate costs and benefits of implementing conventional BMPs in scenarios representing the current nutrient reduction effort, the maximum feasible and the most cost effective suite of BMPs. For catchments without ready access to Alkaloam™ (a nutrient-retentive soil amendment), model estimates indicate that current nutrient reductions are around 10%, with a further 20-30% possible. Those with access to Alkaloam™ could reduce phosphorus by a further 25%. Over a 10 year period, the net cost of BMPs was budget positive, resulting in a net benefit to land managers. Economic barriers to the adoption of these BMPs appear limited and bring the current low adoption levels into question. The maximum possible reductions using available BMPs may not be sufficient to arrest water quality decline and to achieve water quality targets.