Fish Passage Restoration Project

Tuesday, 24 November 2009

In 2008 WCEET confirmed part funding of NIWA’s fish passage project to install spoiler baffles in a 68 m long culvert under River Road, Hamilton to facilitate the passage of fish into Bankwood Stream. This supplements previous work where a fish ramp was installed for the overhanging culvert. The project is now complete and is part of a larger FRST funded project with involvement from Environment Waikato and the Hamilton City Council.

New Era Plastic produced the baffles, including construction and design of the moulds to make the baffles. Hamilton City Council provided funding to install the baffles and Environment Waikato is currently assisting NIWA in the monitoring of the baffles. The culvert in this project carries bankwood stream under River road after passing through Donny Park.    

Initial results to date confirm that the overhanging culvert prevented many fish species from entering the stream. The fish ramp was installed prior to the spoiler baffles and although the fish ramp provided access to the culvert for fish, the high water velocity within the culvert pipe appeared to still limit fish passage.

The baffles break up and reduce water velocities along the base of the culvert, providing resting areas for fish while passing through the culvert. Installation of the baffles was completed in late January 2009.

Monitoring early this year has shown that the fish ramp and baffles are now allowing inanga, smelt, torrentfish and common bully to access the stream, whereas previously only eels, giant kokopu and banded kokopu were present. Further monitoring will take place this summer (2009/10).

Baffles in place - West end of culvert

Baffles in place - West end of culvert