ARWA Centre for EcohydrologySeeking to Understand and Manage Water

Guiding BMP Adoption to improve Water Quality in various Estuarine Ecosystems in Western Australia.

The Australian Government's Coastal Catchment Initiative (CCI) seeks to achieve targeted reductions in nutrient pollution to key coastal water quality hotspots, reducing algal blooms and fish kills. Under the CCI a Water Quality Improvement Plan is being prepared for for the Wan-Canning Estuary (near Perth) and the Vasse-Geographe Estuary (140km South of Perth) to address nutrient pollution issues. A range of projects are developing , testing and implementing BMPs (Best Management Practices) to reduce the load of nutrients reaching the receiving waters. This work builds on progress-to-date achieved in a similar project in the Peel-Harvey Catchment (70km South of Perth).

Here we introduce the CCI funded activities currently being undertaken in the Swan-Canning and the Vasse-Geographe catchments, and uses the Peel-Harvey as a case study to highlight the some activities, relevant findings and approach. A paper describing this project in full is available for download, below.

Catchment Management Environment

The south west of WA has a Mediterranean climate, with cool wet winters and dry, temperate summers. Coastal annual rainfall varies between 700 mm to 1100 mm and average daily temperatures ranging from 17 to 30 degrees C in summer and 6 to17 degrees C in winter.

Overview of BMPs

For nutrient management plans to be effective at a farm level and in a watershed context, BMPs should first be assessed and developed at a small scale in the watersheds of concern. This assessment is underway as part of the Swan-Canning and Vasse Geographe CCI programs.

BMP audits, farm-gate nutrient balance and stakeholder opinions

The CCI program offered an opportunity through a range of projects, two of which focussed on agricultural nutrient sources, to guide the development of a WQIP. The agricultural projects included an assessment of current levels of adoption of BMPs by farmers and their attitudes towards water quality problems (Lavell et al., 2004), along with assessments of farm-gate nutrient balance (Neville et al., 2004).

Decision Support System

It is important to evaluate what nutrient reductions are possible, and at what cost, so that limited funds can be targeted to realise the greatest moderation of nutrient loss for the least cost.

Guiding Principles for BMP Implementation

There are a range of criteria that could be used to provide guidance over which BMPs are implemented and where. These criteria can include

Water quality targets
Cost benefits
Effectiveness of BMPs in reducing nutrient loads to estuaries or
combinations of these criteria.

CCI Catchments

Vegetation (light green), rainfall isohyets (mm), location and catchment boundaries (dark green) of Swan-Canning (Ellenbrook catchment), Peel-Harvey, Vasse-Geographe and Albany Harbours catchments which have been the focus of nutrient management issues in WA Swan-Canning (Ellenbrook catchment), Peel-Harvey, and Vasse-Geographe have been part of the CCI program.

Sankey diagram of the Peel-Harvey P flows and stores for various land use sectors. Width of each bar represents the relative contribution from each land use sector and flow (tonnes).

Contact

Download the full report here.

This report was presented at DIPCON 2007 and published in Water, Science and Technology, Volume 57, Number 11.

Nardia Keipert

bmps.pdf

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