Opuha River at Skiptons Bridge 2

Opuha and Kakahu river health explored at community hui

Date:

A community information session about the health of the Opuha and Kakahu (Te Kākaho) Rivers was well attended, with around 40 members of the community gathering to discuss the findings of our recently commissioned report.

Community members included residents, scientists, consultants and other representatives from throughout the rural sector.

Cawthron's freshwater scientists Dr Roger Young and Roland Eveleens summarised their report and outlined their key findings, before inviting questions from the floor. They also highlighted the recommendations and potential next steps and encouraged the community to work collaboratively to help address some of the concerns identified.

Councillor Nick Ward, who chaired the meeting, thanked the Cawthron scientists for their presentation and mahi in producing the report.

Our Chief Scientist Dr Fiona Shanhun said it was great to see the community's interest in the health of the catchment and the willingness to discuss the report’s recommendations.

"Along with the community, we’ve been concerned about the health of the waterways in this catchment. That’s why we commissioned an independent review of all the information available.

"The report provides a helpful synthesis of the key factors influencing ecological health. We now need to understand more about the specific drivers of water quality in each river.

"It also identifies some recommendations for further work, and we look forward to talking to the local community and collectively considering next steps.

"This is just the start of the conversation. It's great to hear residents and landowners’ views and we look forward to working together to find possible solutions" Dr Shanhun said.

Key themes of the meeting included:

  • Concerns about sediment and its effects on water clarity, particularly in the Kakahu River.
  • Identifying knowledge gaps that could be filled to better understand key drivers of ecological health in the Opuha and Kakahu rivers.
  • Report recommendations, further studies and potential next steps.

The Opuha and Kakahu Rivers report

We commissioned the report, carried out by the Cawthron Institute, to provide an independent review of the ecological health of the Opuha and Kakahu Rivers. It includes information on the current state of the waterways, as well as identifying suggestions for further work to help inform how the health of these waterways could be improved.

Key findings

The report provides insights into drivers of river health as well as opportunities for further work that could help inform next steps.

The report’s key findings are:

  • There are multiple stresses that have influenced the current ecological health of both the Opuha and Kakahu Rivers.
  • The ecological health of the Opuha River below the Opuha Dam has declined over time and is currently assessed as poor.
  • The ecological health of the Kakahu River in the vicinity of the Kakahu Irrigation Scheme discharge is assessed as 'moderate,’ but declines to ‘poor’ further downstream.
  • Key drivers of the health of the Opuha River are the regulated flow regime and persistence of the invasive algae didymo.
  • The key ecological driver of concern for the Kakahu River in the vicinity of the Kakahu Irrigation Scheme discharge is fine sediment arising from the discharge, with the increased variability and volume of flow also likely to play a major role.
  • Knowledge gaps identified include the state of the Opuha trout fishery, drivers of turbidity in Lake Opuha, sources of fine sediment in the Kakahu River and the effects of changes in water flow.
  • Claims of extreme DDT contamination have been extensively investigated and no work to date has substantiated these claims.
 Download the 'Review of the ecological health of the Opuha and Kakahu Rivers (PDF file, 4.26MB)' report.

Last updated:

Back to top