WWLA were commissioned to review the hydrogeological information available and conducted an investigation into the degree of connectivity between the Q2-Q4 aquifer and the Ruamahanga River. A MODFLOW and MT3D model was developed to simulate the groundwater surface water interaction, and differences in water chemistry between the river and brackish aquifer. A three-dimensional geological model was developed to better understand the geological context of the valley. Deliverables included Environment Court Evidence for the Ongaha Farm consent appeal, and Evidence for a submission on the Proposed Regional Plan change.