Waiwhetū Stream

The Waiwhetū Stream is a small watercourse in Lower Hutt, in the North Island of New Zealand. The stream drains the eastern side of the Hutt Valley, and enters Wellington Harbour at the Hutt River estuary. Development and urbanisation of the Hutt Valley since the arrival of settlers led to increasing pollution and degradation of the stream environment. The stream was diverted into concrete culverts in some sections in an attempt to reduce flooding.

Industrial development in the area around the lower reaches of the stream led to that section becoming an industrial sewer. Discharges of industrial waste into the lower reaches ceased in the 1980s when trade wastes were connected to piped sewer mains. However, the stream remained highly polluted with toxic sediments. In 2010, the stream was described as one of the most polluted waterways in New Zealand. Pressure from the community beginning around 2003 helped to trigger a major project to clean up the lower reaches. This project was declared complete in June 2010, after the removal of 56,000 tonnes of toxic waste.

In 2010–2011, a community group was formed to lead restoration of the upper reaches of the stream. Over a period of 10 years, volunteers cleared invasive aquatic weeds and rubbish from six kilometres (3.7 mi) of the stream bed and established around 34,000 locally sourced native plants on the banks of the stream.