Completion Date: May 2017

The Department of Agriculture and Fisheries sets dam operators with guidelines and minimums for fish retention in dams across South East Queensland. Trapped fish are captured and released upstream, back into the dam. The intention is to maintain fish stocks in dams for both recreational fishing and aquatic biodiversity.

Over 2014 and 2015 at Hinze Dam, research and monitoring activities assessed the effectiveness of the existing fishway and the rate of fish escape from the trapping area. The results indicated that the existing Vee-traps allowed up to 30 per cent of the fish to escape from the trapping area, preventing their release back into the dam.

Further to this, a trial was conducted based on best practice design principles to reduce fish escape. This trial involved testing the effectiveness of two alternative traps including a modified Vee-trap and a new, concept Cone-trap design. The modified Vee-trap failed to demonstrate a marked improvement on the 30 per cent escapement rate of the existing design. Conversely, the new Cone-trap design achieved a significantly higher trapping rate and escape was effectively eliminated.

The overall results of the research indicated that the more cost effective choice for Seqwater would be to replace the existing Vee-trap units with newly fabricated Cone-traps.

Practical Engineering’s capacity to custom design, fabricate and install fit-for-purpose solutions placed the company well to meet the needs of Seqwater as they looked to upgrade the Hinze Dam fishway. Utilising the initial concept design, the Cone-trap design was further developed then fabricated and delivered to the site. The old Vee-traps were removed and the surrounding infrastructure was upgraded to suit the new trap design before the new Cone-traps were installed. Seqwater is now able to meet the expectations of the Department of Agriculture and Fisheries by ensuring a higher rate of fish entrapment and ultimately healthier and more diverse source water.