RECENT TESTING OF FISH FRIENDLY WATERWAY CROSSINGS
A recent study has been carried out on three causeways located on northern NSW Class 2 streams. All three structures contained high velocity, low flow pipe(s) that restricted upstream fish passage. The study involved replacing each causeway with a fish friendly multi-cell culvert.
At Ewingar and Tenterfield Creeks, the new box culverts incorporated variations in cell size and bed and side-wall roughness. At Laura Creek, a multi-cell pipe culvert was installed with the cells being partially buried to mimic natural bed conditions within the cells.
Ewingar Ck, before
Low-flow water depths through the structures were increased at all three sites. The designs also resulted in significant reductions in flow velocities through the crossings. For
example, at Laura Creek, typical flow velocities were reduced from 0.52 m/s to 0.38 m/s and minimum flows from 0.45 m/s to 0.03 m/s.
Ewingar Ck, after
Fish sampling was undertaken to determine differences in fish passage both before and after the crossings were upgraded. Fish passage results for the box culvert designs were positive, but mixed.
The Ewingar Creek culvert recorded an improvement from 0 per cent to 44 per cent with the new design. The Tenterfield Creek site recorded an increase in fish passage from 0 per cent to 14 per cent. The Laura Creek pipe culvert recorded an increase in fish passage from 20 per cent to 69 per cent.
Contact NSW DPI (Fisheries) for further information on this research.
This document has been prepared in consultation with a National Steering Committee incorporating membership from the following organisations from each state and territory in Australia:
NSW Roads and Traffic Authority
NSW Local Government and Shires Associations
Queensland Department of Primary Industries
Catchments & Creeks Pty. Ltd. (engineering consultant)
Department of Primary Industries (Fisheries Section) (Northern Territory)
The Department of Fisheries, Western Australia
Primary Industries and Research South Australia
Department of Sustainability and Environment (Victoria)
Inland Fisheries Service (Tasmania)
Australian Landscape Trust
Murray Darling Basin Commission
The member's time and effort in reviewing and providing feedback on the guidelines is gratefully acknowledged.
fish passage requirements for waterways crossings