The Waima catchment is located in the driest area of Marlborough with annual rainfall typically less than 600mm, particularly towards the coast, with higher rainfall inland towards the Blue Mountains. The Waima catchment flows through a limestone area characterised by steep limestone cliffs. Water quality is characterised by high conductivity and pH. The lower reaches are ephemeral, frequently drying up for months at a time during the summer. Approximately 40% of the catchment is covered in native forest and shrub and a nearly equal amount of pasture.