Following a request from the SA Department of Environment and Natural Resources at Berri in the Riverland, a hydrogeological assessment of the Moorook and New Residence irrigation areas was carried out. The water table aquifer occurs in fine to coarse sands known as the Loxton Sands, which are covered by the Blanchetown Clay in the New Residence area. The clay is largely absent in the Moorook area. Groundwater mounds have developed under both irrigation areas. The hydrogeological impact of these mounds is an increase in salt load to the river and floodplains that is up to 10 times the pre-irrigation level. Also, the salinity of native groundwater under the irrigation areas, which was originally between 10 000 and 25 000 mg/L, has been diluted by drainage water to below 10 000 mg/L. In the last three years, the observation well network has shown a drop in watertable elevation, possibly due to improvements in irrigation efficiency. However, it is recommended that monitoring of the watertable elevation be continued to observe any future changes.