In last October’s flood, the water moved so quickly into the loch that the bars could not be removed and Goulburn-Murray Water, which operates the loch, had to abandon attempts to lift all the bars.
A Loch Garry reference committee, comprising stakeholders and landowners, was set up to examine the operating rules and come up with recommended changes, which will go to the G-MW board for final endorsement.
The Goulburn River at Shepparton peaked at 12.03m on October 17, 2022.
The operating rule of 2022 stated that when the river level at Shepparton reached 10.36m, notification would be given to Loch Gary Flood Protection District customers that the removal of the bars would start in accordance with the operating rules.
The new rules stipulate that in situations of a moderate flood forecast by the Bureau of Meteorology (above 10.36m but below 11m at Shepparton), G-MW will send out notifications to the Loch Garry Flood Protection District customers by text messages as soon as possible, to notify customers that bars will start to be removed 24 hours after the gauge reaches 10.36m
If the bureau forecasts a large event, exceeding 11m at Shepparton, G-MW will send out notifications to the Loch Garry landholders by text as soon as possible to advise that all bars will be removed on the day the Shepparton gauge reaches 10.36m.
On the day that the Shepparton gauge reaches 10.36m, all bars will be removed during daylight hours.
The committee agreed that the bars should not have to be pulled out at night.
Loch Garry Reference Committee member Colin Gilby said he was pleased with the outcome the committee had reached.
“Everyone on the committee worked together with the community’s best interests in mind,” he said.
“The revised operating rules that we have endorsed will ensure the regulator can be operated differently depending on the nature of the flood, enabling the rules to be effectively applied in different scenarios.”
G-MW water delivery services general manager Warren Blyth thanked the committee for their dedication.
“We’re grateful for the time and effort that all the members of the Loch Garry Reference Committee have invested into this review process,” he said.
“The committee has had to absorb a lot of complex information and make some challenging decisions, but all the members approached the task with open minds and with a great deal of professionalism.”
The revised operating rules the committee has recommended can be viewed on G-MW’s YourSay website: https://yoursay.gmwater.com.au
THE NEW OPERATING RULES FOR LOCH GARRY
Event (above 10.36m but below 11m):
When the Bureau of Meteorology forecasts the river level at the Shepparton Gauging Station 405204 will exceed 10.36m but will not exceed 11m the following operating rule will apply:
1. G-MW will send out a notification to the Loch Garry Flood Protection District customers by SMS as soon as practicable after the forecast is available to notify customers that bars will start to be removed 24 hours after the Shepparton gauge reaches 10.36m.
2. G-MW will send out a notification to the Loch Garry Flood Protection District customers by SMS as soon as practicable when the Shepparton gauge reaches 10.36m.
3. Bars will start to be removed 24 hours after this level has been reached.
4. The formula for bar removal is that 24 hours after the Shepparton gauge exceeds 10.36 m, 25 bars (based on 140mm bars) are removed for every 31mm rise. If the river continues to rise to 10.96m then all bars would be removed from the loch 24 hours after this height is reached.
5. The replacement of bars is a reversal of this procedure.
Important:
- Bars are to be removed progressively across the structure so that the ‘crest’ remains level across the structure.
- Bar removal and replacement can only occur during daylight hours. Any bars that are scheduled to be removed after sunset and before sunrise the following day will be removed prior to sunset.
Large event (exceeds 11m):
When the Bureau of Meteorology forecasts the river level at the Shepparton Gauging Station 405204 will exceed 11m the following operating rule will apply:
1. G-MW will send out a notification to the Loch Garry Flood Protection District customers by SMS as soon as practicable after the forecast is available to notify customers that all bars will be removed on the day that the Shepparton gauge reaches 10.36m.
2. G-MW will send out a notification to the Loch Garry Flood Protection District customers by SMS as soon as practicable when the Shepparton gauge reaches 10.36m.
3. On the day that the Shepparton gauge reaches 10.36m, all bars will be removed during daylight hours.
4. The replacement of bars is the same procedure as for below 11m.
Source: G-MW.
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