Heavy rainfall and flooding in northern NSW and Queensland has triggered pre-releases from the Menindee Lakes system for the third time in two years. With the Menindee lakes storage levels already increasing as a result of high flows earlier this summer, there is limited capacity to manage the impending additional flow.
As a result, the NSW Office of Water and State Water Corporation began flood pre-release operations on Thursday 2 February 2012, increasing releases from 15,000 megalitres per day to a target of 29,000 megalitres per day by Tuesday 14 February. However, as the scale of flooding in the upstream valleys is becoming apparent, the rate of releases from
Menindee Lakes will now continue to rise further to target 35,000 megalitres per day by Friday 17 February. These releases to the Lower Darling will make room in the storage for the second period of high inflows that are expected to arrive in March and April 2012, and will protect the township of Menindee from extensive flooding. Currently the various flood peaks are still making their way along the Gwydir, Namoi, Moonie, Warrego and Balonne/Culgoa/Bokhara river systems. Flood flows from the Moonie, Namoi and Gwydir Rivers will flow into the Barwon-Darling system first, followed by flood flows from the other Queensland Rivers. The full extent of these flood flows into the Barwon-Darling system is not yet fully clear, but it is expected to be
significantly larger than last summer, with flood peaks even higher than those experienced in 1998. This could result in the largest flood in the Barwon-Darling system since 1976.