Using a predictive data model, Southern Rural Water has been able to give irrigators early indication that they will be allocated a minimum of 40% against their low reliability water shares on December 15.
Manager Water Supply East, Terry Clapham said that, despite the recent rainfall across the district, it was becoming increasingly unlikely that Lake Glenmaggie will fill and spill. For irrigators, this means there will not be any spill entitlement this year.
“Lake Glenmaggie is currently 95% full, but the inflows have been exceeded by customer demand, which is only going to increase as the season continues,” he said.
The short to medium-term outlook from the Bureau of Meteorology suggests we will receive warmer than average temperatures across the region and a neutral rainfall outlook leading from spring into summer. SRW records show a lower than average rainfall and inflow to storages throughout 2017.
“Lake Glenmaggie is one of the most reliable and predictable storages in Australia,” Mr Clapham said. “This gives us the opportunity to look ahead and help customers plan their water use for the non-spill period of the season.”
If there is no significant rainfall in the next few weeks, Lake Glenmaggie will not spill. This will be the first time since 2006 that there will be no spill entitlement for customers.
“Irrigators have become accustomed to factoring ‘spill’ into their planning for the year, given how regularly it occurs. Because of this unusual year, we wanted to let everyone know early that low reliability allocation will be possible on December 15 should the dam not spill. This is because a significant portion of customer entitlements have already been used in the district,” he said.
However, if Glenmaggie does spill before 15 December 2017, the allocation will remain at 100% of high reliability and no low reliability will be issued on 15 December. This is because all customer entitlements are reset to 100% HRWS at the end of the spill period.
Water allocations are reviewed fortnightly throughout the season and are adjusted to take into account future rainfall and inflows into the storage.