This article first appeared in WBM, 2008
Langhorne Creek is at the end of the line when it comes to water allocations. Its innovative water management initiatives have been lauded as exemplars for the entire Murray Darling basin.
The irony is impossible to miss in Langhorne Creek. The area was identified for vineyards 150 years ago because of the natural annual flood events as the Angas and Bremer Rivers carried winter runoff from the Adelaide Hills toLakeAlexandrinanear the mouth of the River Murray. Today, the region that built its history on these floods is suffering perhaps more than any other in the devastating wake of the drought.
“The flood waters don’t come any more,” explained deputy chair of the Angas Bremer Water Management Committee and Zonte’s Footstep vigneron, John Pargeter. More than 7000 dams in the Mt Lofty ranges catch any runoff long before it reaches the plain below.
The region has traditionally relied on its artesian groundwater for irrigation, but when reserves were strained in the early 1980s, policies were developed to encourage the exchange of groundwater allocations for River Murray allocations. Investments were made and pipelines were built, but now theMurrayhas stopped flowing and salinity has increased ten-fold.
Growers are again on the hunt for alternative water sources, and they have redoubled their efforts after this year’s vintage. Langhorne Creek Cabernet Sauvignon production was cut by three-quarters as growers watched crops shrivel before their eyes during the heatwave.
LakeAlexandrinais long lost as a water source for the region. “It looks likeLake Eyre,” bemoaned winemaker Ben Potts (Ben Potts Wines), who has erected seven kilometres of fencing along his property to keep his stock from running out across the lake. “You could almost break a land speed record on what was formerly known asLakeAlexandria!” he quipped.
Proposals for a pipeline connected further up theMurraywhere salinity is lower have been rejected as unsustainable. “This could only ever be a short-term fix,” explained Dennis Elliott of Karanto Wines, “because it would still draw on the same water.” Or lack of water.
Perhaps more plausible is an 80km pipeline to bring recycled water from treatment plants in Glenelg or theAdelaideAirport. “But this water is more likely to be used to irrigateAdelaide’s parklands,” suggested Pargeter. “And besides, it would be very expensive and would require federal funding, so it’s not likely to go ahead.”
The region is faced with desalination plants as the most viable option. “Quite a few people are going into desalination,” said Phil Cross of Angas Plains winery, “but the power demands will put an infrastructure drain on the region.”
Discussion will continue around the merits of each proposal, but what is clear is that the end result will be a combination of initiatives. “I wish we could say that there is a magic bullet of a sustainable and permanent water supply, but it doesn’t exist,” Pargeter pointed out. “We need to be careful not to spend all our time looking for one magic cure while ignoring the fifteen little things that really need to be done.”
One of these is to provide storage of runoff from winter rains, a strategy already well practiced in the region. Phil Cross is in the middle of construction of a large dam on his property, while Rebecca Willson is a little more resourceful at herBremertonfacility. “When our rainwater tanks fill up, we pump the overflow into empty tanks in the winery,” she said.
The region has also been clever in managing its largest water storage resource of all – the artesian water basin.
“We’re fortunate to have a very slow-moving aquifer,” explained Mac Cleggett (Cleggett Wines). “Any water we can put down there will still be there in a few thousand years.”
When rising salinity was identified in the groundwater in the early 1980s, bores were used to siphon winter floodwater back into the artesian supply, a process dubbed “Aquifer Storage and Recovery.” According to Pargeter, the only way to maintain low salinity in the aquifer is to “recharge” it with fresh water.
It took some negotiating with the authorities to make this happen. “The EPA wanted to do a $600 test on a sample of any water planned to go into the aquifer,” said Pargeter. “But by the time the test came back the river had gone down. So a lot of people put river water into it without the test.” The region has now reached agreement with the EPA that the aquifer may be “recharged” without the test, provided that salinity is sufficiently low.
The system has been so successful that during winter rains last year, the aquifer was topped up more than in any year in history, apart from 1992 – an impressive result in a drought year.
The region has also been successful in establishing systems which encourage growers to minimise their water usage. More than a decade ago, a system of “Irrigation Annual Reporting” was initiated by growers to keep each other accountable to improved water management practices.
Each grower is required to comply with a code of practice, and those who meet the code successfully each year are accredited and allowed to retain their water allocation. The system has four requirements of growers.
First, each grower needs to use an inexpensive CSIRO “FullStop” device to monitor and minimise drainage below the root zone to ensure that the water table does not rise. The device detects when the soil is wetted at a particular depth, and collects a water sample to measure salinity.
Second, growers must install a six metre deep monitoring well and use it to measure and report the height and salinity of the water table quarterly. This is more effective than using fewer wells in strategic locations across the region because it involves every grower and if the water table does rise, growers will themselves immediately drive the steps needed to manage the problem.
Third, growers must plant two hectares of deep-rooted, winter-active vegetation for each 100 megalitres of water allocated.
Finally, and most importantly, growers need to complete “Irrigation Annual Reports” by providing extensive detail on their water usage, flooding, salinity, revegetation and other indicators on their property. Accuracy is ensured by correlating results with known measurements such as water meter readings. Every grower is presented with a copy of the annual report, and public meetings and training workshops are held to present and analyse the information.
Of particular interest to growers are a series of scatter plots which graph the irrigation level of each grower against the area irrigated. “Individual names are kept confidential, so no one knows who is represented by each dot,” explained Pargeter, “but it gives everyone a chance to benchmark themselves against their peers. A peer group pressure has developed which encourages higher users to improve their water management and join the group of best operators.”
The results of the system speak for themselves. Many growers have significantly reduced their water usage over the decade that the program has been operating, and are now using less than a megalitre of water per hectare. The region is only using half of its Murray River allocation, and growers voluntarily let the water go through the system without on selling it up the Murray, for the sake of the mouth of the river and the Coorong.
The region has received national interest for its leadership in water resource management. The River Murray Catchment Water Management Board has identified Langhorne Creek as leading the way in monitoring irrigation efficiency auditing. Minister for Climate Change and the River Murray System, Penny Wong, uses Langhorne Creek as an example in discussions withQueenslandcotton growers.
Pargeter believes that it will take a wide range of strategies to addressAustralia’s water crisis. “Up theMurrayeveryone is looking for the big thing that a politician can cut the ribbon on but ignoring the little wetland project or the other small things that can be done to make a difference,” he said.
The success of water management in Langhorne Creek has been a credit to its strong local leadership, community involvement and government support over more than two decades. Extensive detail of the initiatives and copies of the reports are publicly available through the Angas and Bremer Water Management Committee web site at http://www.angasbremerwater.org.au/.
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