Lifeline for native fish in Gwydir Valley
Native fish in the Gwydir river system will be thrown a lifeline with environmental water flowing this week, toward refuge pools that are drying out, downstream of Tyreelaroi Weir to the Gwydir and Lower Gwydir Rivers, Gingham Watercourse, Mehi River and Carole Creek.
The NSW Office of Environment and Heritage will start a low volume water release to ensure a gradual increase in river levels throughout the Gwydir river system. This watering event occurs ahead of a larger water release planned by WaterNSW to occur in May.
OEH Senior Team Leader Debbie Love said these flows would be managed using the best available data and scientific expertise to improve habitat conditions for native fish.
"Rivers in western areas of the Gwydir system ceased to flow in early March 2016. Since then, native fish have congregated in refuge pools scattered throughout the system," Ms Love said.
"While native fish are adapted to sheltering in pools during drought, they are at increasing risk without the flow of water for extended periods as the water quality deteriorates and food resources are reduced.
"By delivering environmental water to the system we are aiming to improve conditions for native fish and prime the system in readiness for the replenishment flow in May.
"We expect that the combination of priming flows followed by higher flows will allow water to reach the lower ends of the system and provide widespread benefits to fish, plants and general ecosystem health.
"At this stage OEH plans to deliver a low flow that will gradually increase in the lead up to higher flow levels scheduled for May.
"OEH has worked with other water managers to design the release of water in the lead-up to the May release, in a bid to reduce the risk of fish death from blackwater which can occur as a result of a sudden high flow," Ms Love said.
OEH will deliver 6,000 megalitres of water from environmental accounts to rivers and creeks in lowland portions of the Gwydir system over the course of several weeks.
Half of this water will be provided by the Commonwealth Environmental Water Holder and be delivered to the Mehi River and Carole Creek.
"We are working closely with DPI Fisheries to assess the risk of a blackwater event under a variety of scenarios," said Ms Love.
"If we do nothing between now and May, waterholes will continue to shrink and the risk of a blackwater event will increase.
"Monitoring of refuge pools is ongoing and we are keeping members of the local Gwydir environmental water advisory group up-to-date," said Ms Love.
Contact: Sarah Scroope