GO WITH THE FLOW: Environmental scientist Leonie Martin at Long Point near the proposed extraction point for the Macquarie Pipeline.
THE Macquarie Pipeline is back on, or at least it would have been switched back on, had it been built in time to catch the 90-millimetres of rain that fell in the Bathurst region over the past week.
Orange City Council has taken the opportunity to hit back at pipeline opponent Matt Hansen who labelled the pipeline a “white elephant” when it was revealed low flows at the pump site just over a week ago would have forced the council to keep the pipeline turned off for days, despite Suma Park Dam dropping below 90 per cent.
Rain over the Macquarie River’s catchment saw river flows at Long Point, near the proposed extraction point, reach 11 megalitres per day last Thursday.
On Friday, flows increased to 79 megalitres, more than double the minimum 38-megalitre flow the river needs to reach before the pipeline can start pumping.
By Monday the river had reached 927 megalitres and on Wednesday 1494 megalitres, but yesterday flows dropped to 1139 megalitres.
The high flows mean up to 12 megalitres could have been taken each day over the past week, adding close to seven days water supply to Suma Park Dam.
Mayor John Davis said the recent low flows and rain in the catchment above the pipeline extraction point proved low flows would not be touched and showed how storm events occured even in extended dry periods.
But Mr Hansen said Orange had got lucky in this instance.
“Yes, we had a rain event that was much needed. But it’s still a white elephant if we don’t get rain for six months,” he said.
Cr Davis said the rain event was just a snapshot, but 100 years worth of data modelling backed the benefits of the pipeline and demonstrated the limitations of Suma Park Dam.
But Mr Hansen said the council’s data was little more than 120 years worth of assumptions, as the river’s oldest gauge at Bruinbin wasn’t established until 1947.
“I don’t trust council assessments of any data whatsoever after what their employed experts who went to down to the river were able to catch,” he said.
“They can bend figures and data to back up any report they want.”
But council spokesman Nick Redmond defended the modelling saying it was based on rainfall and the effect on the river’s flow in relation to the size of the catchment.
The 7227 square kilometre catchment of the pipeline extraction point is almost 42 times larger than Suma Park Dam’s 179 square kilometre catchment, meaning the 55 millimetres of rain that fell in Orange did not top up the dam.
Instead the dam level dropped by over half a per cent from 86.9 per cent last Friday to 86.39 per cent as of yesterday.
clare.colley@fairfaxmedia.com.au
