Posted on May 21, 2025
We are working in partnership with others to restore the biodiversity of the Waimatuku Stream. This project is part of the Ngā Awa river restoration programme.
About the stream
The Waimatuku Stream begins near Heddon Bush and flows southwards through the Southland Plains between the Aparima River to the west and the Ōreti River to the east. It joins Foveaux Strait/Te Ara a Kiwa at Ōreti Beach.
The stream is fed by Bayswater bog (a raised peat bog), several spring-fed tributaries and groundwater. It occupies a historic channel of the Aparima River. There are two large shallow-water wetlands near the coast – Long White Lagoon and Big Lagoon – and a saltmarsh runs parallel to the beach.
The catchment is relatively flat and covers an area of about 25,400 ha. Wetlands currently occupy 702 ha.
Waimatuku Stream has a gentle, relatively constant flow with very few floods or low flow events. Dredging to deepen and straighten the stream bed began in the 1920s and took more than 20 years to complete. This created the channelised stream and uniform banks that are present today.
In the 1990s, the mouth of the estuary was cut through to reduce erosion in the sandhills. The estuary and stream mouth now change their courses relatively often.
The Southland Plains were once cloaked in native forest with braided rivers, swamps and bogs scattered through the landscape. This habitat supported a diverse range of plants and animals.
Today about 2% of the catchment is DOC land or is covered with native vegetation, including the Bayswater Peatland Scenic Reserve and the Drummond Swamp Wildlife Management Reserve. About 94% of the catchment is farmed (mainly sheep, beef and dairy) with 90% covered in pasture.
Ecosystem health
As water flows through the catchment, it receives high loads of nutrients and E. coli from intensively farmed land. Water from artificial drainage networks also joins the stream and adds contaminants.
Environment Southland’s monitoring indicates that freshwater ecosystem health and water quality are poor in many parts of the catchment. Excess suspended sediment, nitrogen, phosphorus and E. coli are the main issues.
In some areas, nitrogen levels in groundwater exceed drinking water standards. This nitrogen-rich groundwater joins the stream and contributes to its high levels of nitrogen.
See Waimatuku and Taunamau catchment summary
Treaty partners and project partners
Te Rūnaka o Ōraka-Aparima and Te Rūnanga o Waihopai are our Treaty partners for this project. They have shared kaitiaki interests in the Waimatuku Stream, as it is the boundary between the two rūnanga takiwā. The takiwā of Te Rūnaka o Ōraka-Aparima extends east to the Waimatuku. The other Murihiku Rūnaka (Te Rūnanga o Awarua, Te Rūnanga o Waihopai and Hokonui Rūnaka) have shared interests in this area.
We are working with Environment Southland, Thriving Southland, landowners and other members of the local community in this project. This includes the Waimatuku Catchment Group, part of ACE (Aparima Community Environment).
Catchment reports and assessments
Waimatuku Stream baseline report
DOC commissioned this report to bring together information about the climate, geology, species, land uses and state of the Waimatuku Stream. It summarises past and present research and restoration work in the catchment and lists opportunities and actions for future restoration.
Read the report 2024-06-04 Ngā Awa Waimatuku Baseline Report (PDF, 4,808K).
Baseline surveys
The Waimatuku Stream was surveyed in 2023 by a team from DOC, Ōraka-Aparima Rūnaka and Environment Southland.
The surveys collected samples of environmental DNA, assessed barriers to fish passage at bridges and culverts, and carried out rapid habitat assessments at 23 sites throughout the catchment.
Read summaries of the results:
