The Water Authority has stated that following the completion of the Pinjar groundwater development, a new major water supply source will be required by 1992. This reasoning is based on current and predicted water consumption demand even in view of the Water Authority's public water conservation programme.

Because of the extent, magnitude and likely environmental implications of developing a new water supply source, the EPA required the Water Authority to prepare an ERMP for this project. It was agreed that it would be a staged assessment, with Stage 1 evaluating the available alternatives and seeking the EPA agreement in principle to the Water Authority's basis for selection of options, then Stage 2 discussing those details the EPA required for any of the options selected in Stage 1.