The Gisborne District Council has almost one hundred stream and river monitoring sites where a range of water quality indicators are tested. Some sites are sampled throughout the year while others are sampled during the summer months as part of biomonitoring or recreational surveys.
In the rural environment water quality is dominated by production of sediment from the soft rocks (which is accelerated where there is little forest cover), and livestock access to waterways. Unstable hill country makes riparian fencing very difficult.
The district is renowned for soil erosion susceptibility due to historical clearing of indigenous forest from the soft rock hills for pastoral farming.
The main rivers entering Poverty Bay are the Waipaoa River, draining a catchment of approximately 216,000 ha and the Waimata River with a catchment of 37,000 ha.
Further north, the Waiapu catchment of 173,00 ha is the largest and includes the Mata, Waitahia and Tapuaeroa rivers.