Macquarie River Pipeline boosting Orange’s water supply

7 December 2017

The Macquarie River to Orange water pipeline is making its first major contributions to Orange’s water supply reserves.

Why hasn’t it been used before now?

The 39 kilometre pipeline was completed in 2015 but hasn’t needed to be used before now due to the increased capacity of Suma Park dam and high dam levels.

The pipeline was completed early in 2015, giving Orange residents access to a much larger catchment area in the upper reaches of the Macquarie River.

In the months after the dam-wall raising project was completed, water began flowing over the dam wall (July 2016). The level of Suma Park stayed at around 100% until December last year and it’s been gradually declining since then. Last week Suma Park was at just over 70% of capacity.

Decisions about when to call on Orange’s water sources (Macquarie pipeline, stormwater harvesting and underground bores) are managed through a complex operational tool.

The council water management team uses the tool to predict future water storage needs based on water storage levels, long term weather forecasts and current water use.

The operational tool then informs staff which water source, such as the pipeline, to use. The tool's aim is to keep overall water storage levels at around 80% of capacity.

In recent weeks, water from stormwater harvesting and district water bores has been used, and this week the Macquarie pipeline pumps have been turned on for the first time.

During an average day of pumping, the :

• Underground bores contribute 0.9 megalitres of water/day
• Stormwater harvesting contribute 8.6 megalitres of water/day
• Macquarie pipeline contributes up to 12 megalitres of water/day *
• Currently water from the catchment surrounding Suma Park is contributing 8.2 megalitres /day.

These four sources of water produce around 30 megalitres or water a day.

The Orange community is currently using around 15 megalitres of water a day.

As part of its environment controls, the pipeline can only be used when there is 108 megalitres/day (or the equivalent of 43 Olympic swimming pools per day) flowing past the off-take point in the Macquarie River.

Following heavy rain across the region last weekend, the flow at the off-take point climbed from 104 meg/day on Saturday to 475 meg/day on Monday.

The aim is that by pumping during periods of good flow in the river, Suma Park dam will be ‘topped-up’ and pumping won’t be needed during drier times.

Under conditions imposed on the project to protect the river environment the pipeline can also only be used when the level of Suma Park dam has dropped below 90% of capacity.

The pipeline can only take half of one per-cent of average annual flows in the river.

* CORRECTION : An earlier version of this article included an incorrect figure for the amount of water produced by the Macquarie pipeline. This error has now been corrected.