The groundwater resources of the Tertiary sand aquifer in the County Musgrave Proclaimed Wells Area (PWA) have been reviewed in order to assess the potential for their use to augment groundwater currently extracted from the unconfined Quaternary limestone aquifer. The Tertiary sand aquifer is a confined aquifer where it is overlain by the Quaternary limestone aquifer, and semi-confined to unconfined in other parts of the PWA. The groundwater quality varies significantly throughout the area, ranging from 500 mg/l to in excess of 35 000 mg/l. Yields range from 1 to 10 l/s due to the variation in permeability within the Tertiary sand. Results from aquifer tests indicate that transmissivities of the Tertiary sand aquifer vary from 20 to 270 m3/day/m. This report concludes that there is the potential to extract low salinity water from the Tertiary sand aquifer, via a network of low-yielding wells, to au gment the water supply for Eyre Peninsula. It is important that this is done in conjunction with close monitoring of both the Quaternary and Tertiary aquifers. If the Tertiary sand aquifer was to be considered for use as part of the reticulated supply, then further work would be required to fully prove the resource.