Kaipara Harbour Catchment
The Kaipara Harbour is the largest harbour in New Zealand and one of the largest harbours in the world. It covers 947 square kilometres at high tide. The harbour extends for 60 kilometres from north to south and has a catchment of over 640,000 hectares.
The Kaipara Harbour is a productive marine ecosystem, with diverse habitats. There are tidal reaches, intertidal mudflats and sandflats, freshwater swamps and lakes, maritime rushes, reed beds and coastal scrublands. The area includes 125 square kilometres of mangrove forest with subtidal fringes of seagrass.
Pastoral land uses occupy about 70% of the catchment by area (sheep & beef 47% of the catchment and dairy 23% of the catchment), with the remainder primarily in native or plantation forest.
About 13% of the catchment is identified as “highly erodible land”, which
produces about 77% of the land-based erosion. About half of the sediment
loss comes from sheep & beef farms, and about one quarter comes from
Currently the catchment sediment load is about 692,000 tonnes per year.