Fish entrainment into irrigation channels is an issue globally. In the USA and Europe, self-cleaning screens are used to limit fish movement into waterways, hydroelectric power stations and pump houses. In some cases, legislation requires it, which has resulted in a well-established and innovative industry. Fish entrained in irrigation channels are usually exposed to poor quality habitat, low-to-no over winter flows, increased predation, injury or death from irrigation pumps, and generally have no passage to return to the natural system.
The Arthur Rylah Institute has highlighted the extent of fish losses in gravity fed diversions in Victoria, with electrofishing surveys of 59 irrigation channel sites in the Murray Valley and Torrumbarry Irrigation areas collecting over 10,000 juvenile and adult fish from ten native species. A larval drift study undertaken by the North Central Catchment Management Authority (CMA) in Gunbower Creek in November-December 2017 revealed that approximately 5500 native fish larvae from four species, including more than 160 Murray cod larvae are being entrained per day in the Cohuna Channel during the peak larval drift period.
To prevent these losses, North Central CMA, in partnership with the Victorian Environmental Water Holder and AWMA Water Control Solutions, are installing Australia’s first self-cleaning irrigation channel screen to prevent fish entrainment from Gunbower Creek into the Cohuna Channel. The Cohuna screen has been designed to suit the needs and spawning strategies of Murray-Darling Basin fish species. The design builds on the extensive knowledge of AWMA, and their industry partners in the USA, to factor in local hydrology and ensure that the delivery of irrigation water is not impeded.
This presentation will outline findings from larval drift and adult fish pump out studies in the Gunbower Creek and Cohuna Channel system and the challenges associated with designing, constructing and installing Australia’s first irrigation channel screen.