MAP: Where the water will flow when the barrage is raised
CONCERNS that raising the Fitzroy River Barrage by half a metre to add 10,000ML storage would cause major inundation of land upstream have been allayed by Rockhampton Region mayor Margaret Strelow.
Cr Strelow said the issues raised by some readers following a recent report in The Morning Bulletin may have been based on a previous barrage-raising study.
"I'm wondering whether some people are confusing the plan to raise the barrage 50cm with a plan from years ago which talked about a much higher raising of the barrage,” Cr Strelow said.
"The current plan is very modest and the extra water is largely contained within the existing banks.
"The increased storage volume, if anything, may provide a benefit to the irrigators on either side of the river who will have longer access to the water and the pumps.”
The council has provided a colour-coded map based on a 0.5m increase which shows the projected areas of inundation.
Cr Strelow said the map showed that any areas of new inundation (coloured red) were very minor compared to the area already inundated by water under the current operating arrangement (coloured blue).
One reader, who had researched previous studies, claimed that the raising of the barrage gates would "cause many thousands of hectares of low-lying land to be flooded” which would ruin plans for further expansion of cultivation areas.
Cr Strelow said this outcome would not happen under the 0.5m plan.
"We are not anticipating that productive land will be impacted,” she said.
"Overall, the expectation is that the increased storage volume will lead to very little inundation of land that is currently used for any productive purposes. Instead, it will provide positive outcomes by prolonging the access that some landholders have to water in the barrage for stock and domestic use, and other water entitlements.”
The increased storage benefit was identified through a Regional Water Supply Security Assessment in partnership with the State Government in October 2015, which assessed Rockhampton's water source and supply infrastructure and future security based on population projections.
The work included surveying more than 40km of the river channel upstream of the barrage to accurately calculate the volume of water stored behind the barrage and use this volume along with other information to model Rockhampton's water supply security.
The work found that at current levels of usage and without any water restrictions imposed, the barrage might be at risk of water supply failure on average about one in every 108 years.
Feasibility and failure impact assessments confirmed the barrage height could safely be increased without risk to the community downstream in the event of structure failure.
The extra 10,000ML would not provide Rockhampton with an increase to its current 50,000 ML allocation, but by increasing storage volume, it reduces the chance of the storage dropping beneath accessible levels in a dry year before the community can use all of its annual allocation.
Fitzroy River Water has been working with the Queensland Government to ensure that any proposed changes to the barrage comply with relevant legislation relating to water resources, planning issues, and the environment.
This will include interacting with local stakeholders to ensure that important local wildlife such as Fitzroy River turtles and the local fishery are not impacted.
So far preliminary mapping work shows that the vast majority of the increased storage volume is contained within the existing height of the river banks.
The council expects to commence consultation with the community in the second half of the year, with project construction to commence in late 2019 and extend through to late 2020.