A preliminary investigation has been made of an area near Lake Woolpolool to assess its suitability as a source of concrete sand for the Chowilla Dam Project. The work included logging of sections along existing test excavations, and the drilling of four cable tool holes up to 13 m deep. Fluviatile sands of the Coonambidgal Formation occur in a near-horizontal horizon overlain by Holocene aeolian sands. Field and laboratory observations indicate that both materials are of doubtful quality, with much variability in both grainsize and grain composition. The total quantity of sand in the western part of the deposit is estimated as approximately 400 000 cubic metres.