On the May 15, the Department for Environment and Water advised an increase from 2% to 8% opening irrigation allocations for the 2020-21 water year. While a 6% improvement from such a low starting point may not bring reassurance to many there is also plenty of positive news to consider when making important business decisions.
There has been improved rainfall over large parts of the Murray-Darling Basin and the catchment is well primed for future inflows. These improved inflows are trending back towards long term average inflows for May and June 2020 and the Darling is flowing through to the Murray, a welcome sight not seen for many years.
Water Storage levels are however a long way off long term average levels. This is the key factor responsible for the very conservative allocation outlook taken by South Australia and is based on a worst case scenario. This scenario is based on conditions worse than those occurring in the Millennium drought and means that water allocations will never go backwards during any water year.
The improved rainfall outlook of a 50% chance of rainfall exceeding the median for June to August 2020 has the potential to greatly improve storage levels and hence irrigation allocations in the coming months. The Department for Environment and Water will again provide monthly Water Allocation Statements detailing a range of probability scenarios which will be reflected as improvements as inflows occur. The current Water Allocation Statement shows that there is: a 95% likelihood that irrigation allocations will increase to 60% by the end of water use year; and a 75% likelihood that irrigation allocations will increase to 90% by the end of the water use year.
It is important to keep in mind that 80% of river system inflows are typically received in the June to November period. With the outlook for rainfall and temperature conditions being very positive over the coming months we can certainly expect improvements, the timing of these improvements should be considered when planning how you are going to use water in your vineyards over the coming months.
More information is available on the DEW website.
Watch the Department for Environment and Water presentation where Jarrod Eaton provides useful information regarding River Murray system inflows and storages, current water resource position and climate outlook and water allocation outlook under differing climate scenarios.