An assessment of the regional surface water quality in the Harvey irrigation area - implications for regional environmental sustainability.

The Harvey Irrigation Area (HIA) located around Harvey in the south west of Western Australia currently has around 10,000 ha of land under permanent irrigation for dairy farming, beef grazing and horticulture, with a total irrigable area of approximately 30,000 ha. This region is presently experiencing some soil salinity problems common to other areas subject to irrigation, as well as producing drainage water that runs to environmentally sensitive estuarine receiving bodies including RAMSAR-listed wetlands. In 1996 South West Irrigation (now known as Harvey Water) was established as a fully privately operated cooperative to oversee the supply and distribution of irrigation water to irrigators in the HIA. This study was commissioned by Harvey Water in an attempt to obtain accurate, factual data regarding the quality of irrigation water from the headwaters of the HIA through to outfall into the broader regional drainage systems. The Department of Agriculture, Western Australia (the Department) was contracted by Harvey Water to undertake the water quality survey as part of an ongoing partnership between the two organisations. The collection of such data in the HIA is important to the Department in terms of better defining sustainability issues, prioritising natural resource investment and developing sustainable farming systems in what is presently a relatively poorly understood region.