HOPES remain high that thermal pollution flowing down the Macquarie River from the depths of Burrendong Dam, NSW, will stop once and for all, with the reinstallation almost complete of the $3.4 million dollar curtain after it failed in 2016.
For decades cold water pollution has made the waters of the Macquarie unbearable for not only river users, but also for native fish such as Murray cod and golden perch. Cold water pollution has contributed to crashing native fish stocks, with numbers plummeting to just 10% of their pre European settlement levels in some areas. Some species are now all but extinct in the region, such as the Macquarie perch, with others endangered including the trout cod, purple spotted gudgeon, and the Western olive perchlet.
With the breeding season for native fish about to get underway from around September 1, the reinstallation may just save an entire native fish breeding season for a 160 kilometre stretch of the Macquarie. Decades of cold outflows have seen temperatures nowhere near natural levels that allow fish to successfully breed.
The 2016 breeding season was severely compromised when the curtain’s failure saw river temperatures crash from 22.4 degrees to a more than chilly 13 degrees in just a 2-week period. The Murray Cod breeding season is triggered in spring when the Macquarie River’s temperatures rise to 16 to 20 degrees, with natural, warm waters needed to ensure that newly born fish survive.
Water NSW said in a recent media release that re-installation of the now redesigned cold water pollution curtain has reached the final stage, with work to be completed in mid-August, allowing the trial to control downstream water temperatures to resume.
WaterNSW has undertaken extensive work to engineer a revised design for the curtain, which has been progressively installed on Burrendong Dam’s intake tower over recent months. The reinstallation is the culmination of extensive repairs and follows the replacement of manufactured components deep below the water surface.
Following the curtain’s malfunction in November 2016, WaterNSW engineers conducted an exhaustive review of the incident and worked to redesign the curtain.
New guidewire connections and rollers have been manufactured to improve the device’s reliability, according to WaterNSW Executive Manager Asset Solutions and Delivery, Andrew George.
“The redesign process demonstrates the capability both of our engineering expertise and the local businesses engaged to manufacture the new connections and rollers”, Mr George said.
“WaterNSW will shortly resume monitoring and testing of the curtain and assess its potential as a long-term option for managing cold water releases once it has been commissioned and the dam storage level rises.”
Instrumentation has been installed to monitor the performance of the new design and existing temperature loggers from Wellington to Warren will provide data at half hour intervals to monitor surface water temperatures further downstream of the dam.
