Government in lockdown over water management

By ERWIN CHLANDA
 
The NT Government has slapped an information black-out on any details relating to the water supply of Alice Springs – and this includes answering questions about issues already on the public record.
 
Tomorrow the barely functional Alice Springs Water Advisory Committee – it has not met for two years – will convene between 1pm and 5pm at the Arid Zone Research Institute on South Stuart Highway.
 
There will be an announcement after that meeting, the Alice Springs News Online has been told.
 
The meeting is not open to the public. It is not clear how that sits with the government’s boast, articulated on its water policy website, to have a “transparent stakeholder driven plan that will protect environmental and human interests”.
 
According to a source no agenda has been given to the members although it is assumed that significant new water allocations will be announced.
 
The members are understood to be Steve Brown, whose family is planning a major subdivision in the south-western corner of the municipality; Ricky Hayes, who runs a major horticultural operation at Rocky Hill south-east of Alice Springs; Jimmy Cocking, CEO of the Arid Lands Environment Centre); Glenda Shields and Steve Shearer, of the Chamber of Commerce.
 
Cr Brown, a town council nominee, has apparently been replaced by Cr Eli Melky but the minister hasn’t gotten round to ratifying that appointment.
 
Water issues have been front and centre in public discussions about the Angela Pamela uranium project (now dormant), fracking, the growth of the town and ambitions for expansion of horticulture and mining.
 
This summary is sourced from a News report last year and the Alice Springs Water Resource Strategy 2006-2015.
 
We also spoke with Robert Read, a hydrogeologist with long experience in Central Australia and now retired in Tasmania. He rang alarm bells earlier this year in a letter to the editor of the News about further allocations to Rocky Hill.
 
All quantities are in Mega Liters (ML), that is one million liters, or about half the size of an Olympic swimming pool.
 
TOWN USE:
Alice Springs uses 10,000 ML a year.
 
RESERVES:
Known reserves in 2005 in the aquifers of the Amadeus Basin were:
Paccota 314,000, Shannon 239,000, Roe Creek 797,200, Rocky Hill 3,750,000. TOTAL 5,100,000
 
GOOD WATER:
Mr Read says these volumes are of water under 1000 mg/L total dissolved salts. That is much inferior than what is usually regarded as drinking water for large communities (500 mg/L – the quality we’re presently getting from Roe Creek). The quantity of 500 ml/L water in the Rocky Hills aquifers is “not known with any precision” but is much less than in the summary above, he says. “1000 is acceptable for small communities and very hard to meet in many areas.”
 
ESTIMATES:
Mr Read describes the precision of the estimate for Rocky Hill – the biggest aquifer and the future source of water for the town, as “ridiculous” as it has three significant figures where it is doubtful that the resource is known to one significant figure.
He says the estimate is for water of 1000 milligrams per litter (mg/L) total dissolved salts.
The town’s (dwindling) current supply from Roe Creek is of a much higher quality, at 500 mg/L, the usual norm for drinking water in large communities.
The volume of the Rocky Hill aquifer is not known with much accuracy, says Mr Read. Only a small number of exploration wells have been drilled.
 
RECHARGE:
The annual recharge is 100 ML for Roe Creek and 2000 ML for Rocky Hill, a total of 2100 ML, according to the 2004 report.
“My best estimate is 1000 ML a year average recharge.  This is the figure the original Rocky Hill allocation was based on,” says Mr Read.
 
EXCESS USE:
The 2004 report predicted an annual use of 14,000 ML for town use and agricultural purposes. That means we are using 6.6 times more than the recharge, using the report’s calculations. Using Mr Read’s we’re using 14 times the total recharge.
 
SEWERAGE PLANT:
The sewage plant evaporates 2000 a year, about the equivalent of the Rocky Hill recharge, by the report’s estimate, or double that, by Mr Read’s.
 
HOW MANY YEARS LEFT?
Let’s look at the quantities listed in [2] above.
Accepting the inferior 1000 mg/L quality, using the figure for the reserves reported in 2004, and the uses projected in the report for 2015, we have 364 years left.
But we don’t know the supplies of drinking water, with under 500 mg/L dissolved salts, which is what we’re getting now, says Mr Read.
 
THE BIGGER PICTURE:
The Amadeus Basin Aquifers cover 8,200 sqkms. We are currently drawing from a small portion of that basin. Neither the CLP nor the Labor governments on the NT have bothered to carry out the extent of exploration needed to make reliable predictions for the future water supply of the town and its regions.
Says Mr Read: “Not all of the basin has usable aquifers. In some places the Mereenie Sandstone has yields of only a few litres per second.”
 
GRAPES:
One hectare of mature grapes requires 10 ML/year. At Ti-Tree it is 7, says Mr Read.
 
IMAGES: Ross Engineering.