The Upper Brisbane River near Linville (Photo: Mattinbgn. Wikimedia Commons)

Report Tests Different Sizes

The Prefeasibility report tests different scenarios for a dam at Linville.

The size could range from 240,000ML (with a maximum capacity of 672,100ML) to 570,000ML (a maximum of 1,172,400ML).

The cost for this new dam at current prices would vary from $401 million to $575 million.

Approximately 49 properties, including up to 25 houses, would have to be acquired by the State Government under the various scenarios.

The report also tests various outcomes for raising the Wivenhoe Dam wall from between 1.5 metres and 8 metres, raising the existing spillway and installing a second emergency spillway.

December 16, 2014

The chances of a new dam being built near Linville have increased following the release today of new State Government report.

The “Prefeasibility Investigation Into Flood Mitigation Storage Infrastructure” considers potential options to improve the flood defences of Brisbane and Ipswich.

The preferred options are new dams near Linville and Willowbank, and raising the Wivenhoe Dam wall.

Water Supply Minister Mark McArdle said Brisbane and Ipswich could never be “flood-proofed” but the State Government was committed to doing everything possible to better protect lives, homes and businesses.

“The prefeasibility study we are releasing today is the first step in understanding how new dams could help us tackle these challenges and better protect Brisbane and Ipswich from future floods,” he said.

Initially, sites for eight potential new dams – plus the raising the dam wall at Wivenhoe – were identified and investigated as part of flood mitigation options:

  • Upper Brisbane River (near Linville)
  • Cooyar Creek (near Benarkin National Park)
  • Emu Creek (near Harlin)
  • Bremer River (near Mt Walker)
  • Stanley River (near Peachester)
  • Tenthill Creek (near Gatton)
  • Lockyer Creek (near Murphy’s Creek), and
  • Cressbrook Creek (near Kipper).

However, the number of new potential dam sites was then expanded from the initial eight to 39.

The prefeasibility investigation developed a shortlist of dam options which were assessed in 47 combinations, testing the proposed infrastructure against the 20 largest floods recorded.

Mr McArdle said the prefeasibility study, which was completed this month, narrowed the flood mitigation options down to three that were worthy of further consideration:

  • Increasing the flood mitigation compartment of Wivenhoe Dam by raising the dam wall;
  • A new dam on the Brisbane River upstream of Linville; and
  • A new dam on the Lower Warrill Creek near Willowbank.

“It is important to stress no decisions have been made about which dams may or may not be built,” he said.

“A more detailed investigation will now be carried out to consider the benefits, estimated costs, and potential impacts of each of the three options or combinations of options.

“New operational strategies for Wivenhoe and North Pine dams released last month could mean as many as 1500 fewer buildings in Brisbane and Ipswich would be flooded in a repeat of the 2011 flood.

“The new dams we are investigating could save thousands more homes and businesses if there was a repeat of the 2011 floods, but it is still early days and we will now do more detailed studies into these options.”

A “feasibility” investigation will begin in January to explore the three preferred options.

* * *

Member for Nanango Deb Frecklington has thanked the Somerset community for their patience in regards to the announcement of the dam options.

“I know that many people in the Somerset region have been awaiting this announcement and I thank them as well for their patience and understanding in this process,” she said.

“I would like to reassure everyone who may be impacted by this announcement that we hope to know the final choice by mid-2015, so people can start making decisions and plans.

“In the meantime, I will be working with the community through a thorough consultation process.

“The two other dam options which had been identified were Cooyar Creek Dam and Emu Creek Dam, but neither of these has been chosen for further scoping.”

[UPDATED]

A map shows the site of the two new potential dams (Source: State Government)

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