WWLA were commissioned to undertake sustainable yield assessment through the development of a groundwater flow model using MODFLOW-USG on a section of the Aupouri Aquifer in the Far North of New Zealand between Motutangi in the north and Waiharara in the south. The user group consisted of seventeen avocado orchardists who were seeking a total of ~15,050 m3/day in groundwater allocations from a ~20 m thick shellbed aquifer 100 m below the ground surface. Issues that required consideration included saline intrusion and impacts on a regionally important wetland.