The Otara River is fed from the steep hill country of the Raukumara and has a catchment area of 350 square kilometres. The upper catchment is mainly forest-covered ranges made up of Urewera Greywacke and Cretaceous conglomerates, sandstones and siltstones. The river then travels through Holocene deposits used for farming and some horticulture. The Otara forms the eastern boundary of Opotiki before joining with the Waioeka River.
Water quality monitoring at Brown’s Road and shows increasing turbidity.