We divide the irrigation year into three phases:
This approach recognises Lake Glenmaggie as an annual storage, and makes all water available for use during the year. The reservoir will generally increase in volume in winter and spring (filling most years) then spill during springtime and gradually empty during late spring, summer and autumn. Because winter and spring inflows are generally enough to fill Lake Glenmaggie, we don’t need to carry over water from one irrigation season to the next.
The filling phase
The filling phase starts at the beginning of the irrigation season.
The spilling phase
The spilling phase begins once Lake Glenmaggie has filled (usually between September and October). The spilling phase ends on 15 December each season. During this time, Southern Rural Water may allocate up to 100% high reliability water shares with the utilisation of the Thomson Drought Reserve. No low reliability water shares (Sales) are available during this period.
The emptying phase
This phase will start when we begin to draw down on the water held in Lake Glenmaggie. Depending on inflows into Lake Glenmaggie during the emptying phase, Southern Rural Water may announce allocation against low reliability water shares.
Maximum efficiency rule
In very dry seasons, the Maximum Efficiency Rule is applied to help secure water supplies by keeping losses to a minimum during the filling and emptying periods. Our planners will schedule water deliveries to maximise efficiency and to conserve the volume of water in storage. This may mean a small change to your requested water order day or time of delivery.
In seasons of low allocation, irrigation rosters may also be introduced to maximise efficiency, so that channel operating losses are reduced. As an example, a channel system may operate for a week and be closed for a week. Customers will be notified well in advance if channel rosters are going to be introduced.
Spill entitlement
Once Lake Glenmaggie spills, all water used from the start of the season is called spill entitlement. As a result, all water that has already been used when spill entitlement is announced will be credited back as “usable allocation”, leaving you with your full seasonal allocation to use.
The process of crediting your usage during the spill period will continue until the maximum communal volume of 62,000 megalitres is reached.
To receive spill entitlement, all water orders must have been both placed and delivery completed, before the spill finishes.
If Lake Glenmaggie doesn’t spill, there will be no spill entitlement and any water used will continue to be deducted from your seasonal allocation.
High Reliability
Low Reliability
