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New council strategy to improve fish passage at pumps

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Published: 20/12/2024

Waikato Regional Council’s Integrated Catchment Management Committee has endorsed a strategy to improve the safe downstream passage of fish at Waikato Regional Council (WRC) managed pump stations.

Work to develop the Pathways to the Sea Strategy – Fish passage at pump stations, a partnership project with iwi, industry and other councils, was started five years ago and included extensive research.

More than 20 technical reports were produced and seven different methods tested, with all subsequent recommendations brought together to inform the strategy.

Key recommendations of the strategy include:

  • trap and transfer of tuna to be undertaken at priority sites every year during eel migration
  • installation of gravity bypass outlets during pump replacements and investigation into fish-friendly designs
  • installation of fish friendly pumps during pump replacements and as opportunities arise
  • to investigate options and solutions for safe upstream passage at pump stations
  • to undertake eDNA sampling, from 2025, in pumped catchments where there is little or no fish information
  • sensor (robot) fish testing of all new pump types that are installed.
  • testing of other fish friendly pumps
  • to trial changes to how pump stations are operated.

Waikato Regional Council owns and operates 124 flood protection and land drainage pump stations across the region, which is the largest number operated by any council in New Zealand. 

Many of these assets were installed decades ago (50+ years) with the primary focus to clear floodwaters. 

Some pump stations are ‘pump only’ and do not provide a gravity outlet bypass or alternative route for native fish to pass in and out of the catchment.

Most of the pump stations contain axial type pumps which are known to injure or cause fish mortality, and these pumps can be particularly harmful to tuna because of their migratory behaviour and size.

Pathways to the Sea project manager Michelle White told the committee that as it was not financially feasible to go out and replace all pump stations with fish friendly assets at once, the catchments would be prioritised for remediation.

“As part of the strategy, we developed a prioritisation matrix based on fish mortality records, cultural values, catchment size, fish records, lakes/wetlands in the catchment, abundance of tuna, and floodgate presence.”

As part of research that contributed to the strategy outcome, the council installed fish friendly pumps as part of three pump station upgrades and monitored the results.

A modified MacEwans pump, which was commissioned by the council to replace existing axial pumps, was found to be 97 per cent fish friendly, while encased Archimedes screw pumps – fitted at two locations – was found to be 99 per cent fish friendly.

The Pathways to the Sea programme included co-funding by: Bay of Plenty Regional Council, Nelson City Council, Hawkes Bay Regional Council, Greater Wellington Regional Council, Southland Regional Council, Marlborough District Council, Ministry for Primary Industries Sustainable Farming Fund, Department of Conservation, Lotteries, Waikato River Authority, Waikato-Tainui College for Research and Development, Waikato Catchment Ecological Enhancement Trust and One.NZ.