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Owhiro Stream catchment

Owhiro Stream catchment

Updated 5 February 2019 10:10am

The Owhiro Bay community have been concerned about the level of pollution and the state of the Owhiro Stream and its inhabitants. In early 2017 we met with the Owhiro Stream community to talk about stream health issues.

Following the meeting, we commissioned a report to bring together everything we know about the condition of the stream and what’s affecting it.

The Report identified gaps in knowledge that will help us monitor the stream future and identify potential citizen science projects. Citizen science is scientific research carried out, in whole or in part, by amateur scientists and communities.

It also confirms that water quality is impacted throughout much of the stream length by sewage and stormwater infrastructure and contaminants from landfills.

Summary of Owhiro Stream catchment ecology

What are we doing about it?

In response to what we know about the Owhiro Stream and recommendations in the report, a number of projects have already started. Some of these projects are a collaborative effort between us, Wellington City Council, Wellington Water, consent holders and/or the community and include:

1. Further community engagement initiatives

We were so encouraged by the number of people within the community who attended the open day at Owhiro School in March 2017, including all the great questions and ideas that were put forward, that we are organising another community event for early 2018.

Keep an eye out here and on our Facebook page for details.

2. T&T Landfill clean water diversions and wetland construction

In 2016 and early 2017 we were told about discolouration and foaming in the Owhiro Stream. An investigation determined that this was the result of discharges from T&T Landfill, and that they were causing significant adverse effects on water quality and ecology in the stream as well as the tributary that runs through the landfill.

An ecological assessment recommended that a wetland at the toe of the landfill and clean water diversions around the landfill be constructed with urgency.

These physical works have now been completed (see photos below). The clean water diversions will result in less water making its way through the fill, and carrying contaminants downstream. The wetland will provide some treatment of any leachate coming from the landfill.

3. Catchment wide approach to monitoring

We are also looking at the various monitoring programmes currently being undertaken in the Owhiro catchment by T&T Landfill, C&D Landfill, Southern Landfill, Wellington Water and ourselves.

This is to determine whether changes should and can be made to better understand the effects of activities within the catchment.

4. Wellington Harbour/ Hutt Valley Whaitua

The Owhiro catchment forms part of the Wellington Harbour and Hutt Valley Whaitua. The Wellington Harbour and Hutt Valley Whaitua Committee will be a group of local people tasked with recommending ways to improve the quality of our freshwater.

The committee will need to understand the ways in which Whaitua communities use and value water, what the issues are, and how local communities want to deal with those issues. This committee will be established in 2018.

You are encouraged to have your say on the content and direction of the committee’s work. To find out more and get involved visit

5. Wastewater and stormwater infrastructure improvements

Wellington City Council (WCC) has invested in wastewater asset upgrades and renewals in the catchment over the three year period from 2009-2012. We believe the results of this effort are seen in the downward trend of bacterial contamination presented in the report.

Although encouraged by the success of the upgrades and renewals, it is recognised that more work will be required to meet your expectations.

WCC has also lodged an application for region-wide stormwater consent, which will provide a catalyst for the alignment of water quality monitoring effort. There are, of course, multiple sources of contamination in this catchment, and a holistic stormwater management strategy that addresses wastewater infiltration, and Whaitua objectives will be developed and actioned as part of the Natural Resources Plan.

Further information

The following pages aim to provide easily accessible information to the public and community affected by these water quality issues and to assist in understanding the process for reporting environmental incidents to GWRC.

Frequently asked questions

Logging an environmental incident to GWRC

Previous updates 

If you have a question or would like to find out more, please contact our Environmental Help Desk at 04 830 4255 or