Toowoomba council water supply: Report reveals possible impacts of climate change, population boom by 2071

Toowoomba won’t have a sustainable water source using existing supplies by 2071 if the region suffers from climate change or very high population growth. Read the figures here:

The impacts of climate change and a possible population boom could leave Toowoomba’s water supplies vulnerable within 40 years, forcing potentially billions in infrastructure to be brought forward by decades.

That’s according to the details of a new report into the Toowoomba Regional Council’s water security until 2071, which offers fascinating insights into how it could respond to environmental challenges like less rain and longer droughts.

The new Water Vision 2071 report, which was endorsed by councillors at Tuesday’s ordinary meeting, explores the portfolio of works the TRC might need to ensure the city had a sustainable bulk water supply for the next 50 years.

The document, which will be updated every four years, predicts the city will require 29,000ML per year by 2071 based on current levels of service for residents and industry.

Aerial photograph of Lake Cressbrook. Photo Kevin Farmer / The Chronicle Helicopter services courtesy of Heliwest Group

Aside from base works until 2040, which include increasing allocations to 33GL per year by 2027, upgrading the Mt Kynoch water treatment plant to 75ML per day by 2034 and connecting five southern communities to bulk water by 2027, a future council can look at three long-term water strategies.

They include the utilisation of existing supplies like further increases of Toowoomba’s allocation from Wivenhoe to 21GL per year (portfolio 1), exploring alternative supplies like 15ML/day of recycled water into Cooby Dam by 2049 (portfolio 2) or connecting Toowoomba to a water source (like a new or existing dam) outside the region by 2046 (portfolio 3).

But the accompanying technical report by Engeny Water Management paints a grim picture for council coffers when considering the impacts of climate change or higher-than-expected population growth.

When based on industry-standard modelling of raising global temperatures by 4.3 degrees by the year 2100 and an extra 95,000 residents using bulk water over the next 50 years (from 145,000 people to 240,000), the report found none of the listed portfolios of works could deliver for the city’s current water usage to 2071.

The current level of service (LOS) is based on 200 litres per person per day and no more than one period of medium level water restrictions (175 litres daily per person) during a 10-year period – that period also not lasting longer than two years.

The year of deficit (when water supply and demand becomes unsustainable) is predicted to be as early as 2061 if the council chooses to focus on existing water supplies.

Introducing recycled water to Cooby Dam only extends this D-Day by three years.

“TRC water security is potentially susceptible to the impacts of climate change which may result in future (and larger) water sources being required earlier to meet the year 2071 projected demands,” Engeny’s report said.

“Under (the) climate change scenario, none of the representative options portfolios can deliver the required LOS yield in Year 2071.

“Infrastructure upgrades are brought forward with the need for new water source to be identified within the 50-year planning horizon.”

It means the council will need to either find an additional water connection before this point, or residents will have to get used to higher-level water restrictions more frequently and lower overall use.

However, a potential population boom could have significant consequences far earlier, with the report finding having 250,000 people connected to bulk water by 2071 (an extra 2150 residents per year) would bring forward most works slated for construction before 2050 by as much as 14 years.

For example, the planned upgrade of the Cressbrook pump station (from 44ML/day to 53ML/day) is meant to be built by 2032, but a huge spike in the population would require be finished by 2027.

The high-growth model posited by Engeny also doesn’t factor in climate change, as it is used as a different dataset to compare against that scenario.

Toowoomba to Warwick pipeline ready by 2027

State water Minister Glenn Butcher looks at the corridor for the Toowoomba to Warwick pipeline, which is still under pre-works.

Construction won’t start on the Toowoomba to Warwick pipeline until 2025, but Water Minister Glenn Butcher has promised it will be ready to use before the Darling Downs is hit by drought.

Mr Butcher gave the assurance in Toowoomba on Tuesday as part of promoting the $13.4m for pre-works on the project committed in the latest state budget.

SEQwater and surveyors are currently inspecting the corridor for the 109km water pipeline, which will connect Warwick to Wivenhoe Dam via Toowoomba.

It will also hook four drought-affected communities — Cambooya, Greenmount, Clifton and Nobby — to bulk water.

Mr Butcher said a number of steps needed to be ticked offer before pipes could be laid in the ground.

“There are a lot of things under the ground that you can’t see, so that have to make sure services under the ground aren’t impacted by this pipeline,” he said.

“We’re certainly continuing these pre-works into next year, we’re hoping to have the proponents announced by the end of next year, and then we’ll be starting in 2025 with this project, making it quite clear that we want this thing up and ready to run by 2027.

“The reason for that is if it doesn’t rain between now and then, we’ll have this pipeline ready to go if Leslie Dam (at Warwick) runs out.”

The announcement of the project has been a subject of controversy for the Toowoomba Regional Council in the past, but Mr Butcher said the state government was now working closely with the council.

“Toowoomba Regional Council has been working closely with us on this project and we wanted to make sure that if this water was being taken from Toowoomba to Warwick, that some of those important council projects could also be delivered,” he said.

“They were going to go and (connect communities to bulk water) themselves, we’re now doing it as part of this project.”

Mr Butcher met with mayor Paul Antonio later on Tuesday, with the latter describing it as a productive discussion.