The Tuapiro sub-catchment is located two kilometres north of Katikati Township. It is 7,675 hectares in area and flows from the northern Kaimai ranges to the Tauranga Harbour at the Tuapiro estuary. The sub-catchment is located within the Tauranga Ecological District, and mostly covers the area wet and east from Lindeman Road to Wolsely Road. The sub-catchment is about 15 kilometres long and six kilometres wide. It includes 125 kilometres of streams, 250 kilometres of riparian margins (both banks) and 15 kilometres of harbour margin. The primary waterway in the sub-catchment is the Tuapiro Stream. There are seven named tributary streams (Ananui Stream, Hikurangi Stream, Tahawai Stream, Tamaki Stream, Tuapiro Creek, Wairoa Stream and Waitengau Stream) and numerous unnamed tributaries. The most widely spread class of vegetation cover in the sub-catchment is indigenous vegetation at 48 percent and is largely confined to the upper sub-catchment. Pastoral land covers 32 percent and horticultural land covers 15 percent. Exotic forest covers five percent of the sub-catchment. Large areas of estuarine wetland surround the Tuapiro Estuary.