Surely there must be little doubt Orange lacks sufficient water storage capacity for long term growth.
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Supplementing storage with the Macquarie pipeline, stormwater and bores since Suma last spilled after raising the dam wall level, still sees Orange facing severe water restrictions within just three years.
The millennium drought persisted longer, yet Orange's water storage is lower now with these additional supplementary water sources than it was when the millennium drought broke in 2010.
Orange's first water storage, Gosling Creek Dam, opened in 1890.
Eighteen years later (1918), Meadow Creek Dam (Lake Canobolas) was completed, increasing Orange's storage capacity by 108 per cent.
Thirteen years later (1931), Spring Creek Reservoir was built, further increasing Orange's storage capacity by 247 per cent.
Another sixteen years later (1947), Spring Creek Reservoir's wall was raised, increasing Orange's combined storage capacity by another 46 per cent.
Then fifteen years later (1962), Suma Park Dam was completed, increasing Orange's total water storage capacity by 348 per cent.
Another 54 years after Suma Park Dam opened, Suma's wall was raised in 2016, increasing Orange's combined water storage capacity by just eight per cent - maybe not the significant change in long term water storage capacity Orange needs to sustain future growth.
Since the end of the millennium drought, Suma Park Dam spilled in 2010, 2011, 2012 and again in 2016.
Enough water has flowed over the dam wall during those spill periods to fill an equivalent size dam many times over.
A site exists in reasonable proximity to Suma Park for an off-stream storage dam where some of this spill volume could be transferred for additional supply when needed.
This site, let's call it the new "Bulga Dam", could potentially store a similar amount of water as Suma Park Dam, effectively doubling Suma's capacity.
The site is approximately 60 per cent deeper than Suma with possibly around half the surface area, therefore having half the evaporation loss of Suma.
To advantage also, the Full Supply Level (FSL) would be around 50 metres lower that Suma's FSL, allowing water to be easily gravity fed by pipeline to this new storage dam.
Pumping this water back to Orange's Icely Road water treatment plant would be significantly cheaper than lifting water 470 m over 37 kilometres from the Macquarie River.
Not to mention, cleaner than harvested urban stormwater runoff and possibly more amenable than treated effluent.
Unfortunately such a project might be too visionary and ambitious for Orange City Council.
Denis Marsh
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