Namoi catchment

The Namoi Catchment occupies an area of approximately 42,000 square kilometres. The catchment is bounded by the Great Dividing Range in the east, the Liverpool Ranges and Warrumbungle Ranges in the south, and the Nandewar Ranges and Mt. Kaputar to the North. Major tributaries of the Namoi River include Coxs Creek and the Mooki, Peel, Cockburn, Manilla, and McDonald Rivers, all of which join the Namoi upstream of Boggabri. Stretching from Bendemeer in the east to Walgett on the western boundary the Catchment is over 350 kilometres long.

Fish passage

Case Study - Review of barriers to fish passage in the Namoi

As a result of funding from the former Namoi Catchment Management Authority (now Local Land Services), NSW DPIRD has completed a project entitled “The Assessment and Modification of Barriers to Fish Passage in the Namoi Catchment”.

A total of 496 instream structures across eight Local Government Areas were assessed with respect to their impacts on fish passage. 162 of these structures were identified as fish passage barriers, with 31 of these listed as High Priority and requiring immediate remediation. Included in these structures were nine causeways, eight weirs, five fords, five water gauge structures, three culverts and one water-supply pipe. Remediation of fish passage at all 31 high priority sites will open up approximately 1000kms of additional free passage for fish in the Namoi catchment.

This project was undertaken to identify barriers to fish passage in the Namoi catchment and in doing so provide the former Catchment Management Authority with information necessary to undertake targeted remediation works. A range of remediation options have been recommended for reinstating fish passage at High Priority sites, including:

  • Basic management and maintenance of sites, such as the regular removal of sediment and debris;
  • Modification of structures, such as retrofitting low-flow channels, modifying outlet levels, and installing fishways, and;
  • Complete removal and, where necessary, replacement of structures.

Demonstration sites have been established as part of this project to illustrate best practice techniques associated with the design, construction, and remediation of instream barriers. Four case study sites have been selected from the list of High Priority structures and remediation is underway.

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