WATER: by Patrick J. ByrneNews Weekly
Wimmera-Mallee major water conservation project underway
, October 19, 2002
The widespread, worsening drought that could wipe $6 billion off the incomes of already struggling farmers, has highlighted the need to drought proof Australia. The Wimmera-Mallee Sustainable Water Management Strategy has the potential to greatly assist this for a large area of Western Victoria. Pat Byrne reports.According to The Macquarie World Atlas, "While Australia can be described as the world's driest continent, it does not follow that the country is short of water. On a per capita basis, few countries in the world are so favourably endowed. However, there are problems, especially in terms of the location of much of the water in relation to the main centres of population, the variability of run-off, and the uses to which the water is put.
"The growing evidence of pollution is one problem. In the final analysis, the major problem is the management of Australia's water resources" (pg 158).
This description of Australia's water availability, delivery and environmental problems is epitomised in the Wimmera-Mallee region of Victoria. It is one of the driest areas of the state with irregular water flows, and suffers from major wastage in delivery and attended environmental problems. Yet it has substantial available water.
A review of existing Wimmera-Mallee water operations 1994-1999, showed average annual releases from the Grampian Mountains storages of 120,000 megalitres.
Of this, approximately 85,000 megalitres is lost from the channels and drains each year, with seepage responsible for 95% of these losses. Of the 35,000 megalitres that reach its intended destination, another 18,000 megalitres is estimated to be lost from farm dams each year, with evaporation constituting a significant component of this loss.
In other words, of the 120,000 megalitres released, about 86% is lost to seepage and evaporation.
The problems of water loss, consequent salinity, and other environment problems from reduced river flows, led to the development of a Northern Mallee piped water development system that has proved highly successful. This initial project has replaced the open channel delivery system with piped water, mostly in plastic piping, that has dramatically cut water losses.
The Northern Mallee project's success led to a feasibility study for extending the piped water system across the rest of the Wimmera-Mallee region.
With the strong backing of local communities, the Wimmera-Mallee Sustainable Water Management Strategy is ready to move into the detailed engineering design stage. The $7 million needed for this stage is coming from the Federal Government, Victorian Government (through the State Regional Development Fund), Wimmera-Mallee Water, twelve municipal councils, four catchment management authorities and Powercor.
The eventual pipeline project is estimated to cost $300 million, with funding to come primarily from the Federal Government.
According to Brian Hogan, a farmer near Birchip in the centre of the project area, the project has received strong community support.
He said that there were "two things we would like to ensure: that there are sufficient farm dams still supplied to sustain the local wild life so birds and animals don't have to depend on stock troughs, and the diversion of some water into lakes for recreational purposes.
"Such places are important places for farmers to socialise and unwind. Better to have good recreational facilities than the government having to supply a bus load of counsellors to help depressed farmers."
The current open channel Wimmera-Mallee Domestic and Stock Supply System is the most extensive of its kind in the world. Overall, it comprises 18,000 km of open, earthen channels that provide water deliveries to 22,000 farm dams and 51 towns across three million hectares (10% of the State), from the Grampians in the south to the River Murray in the north. Farm dams are currently supplied once a year.
Water is sourced from twelve storages in and around the Grampians and from the Waranga Western Channel, frequently augmented by direct diversions from natural waterways. Parts of this extensive system are over 100 years old.
The supply system is located in one of the driest parts of Victoria, with average rainfall varying from 1,000 millimetres in the south to only 300 millimetres in the north. This rainfall is highly variable from year to year.
The present settlement in the Wimmera-Mallee was only made possible by the availability of water through the existing system.
The new project would replace the 18,000 km of open channels with 6,500 km of new pipes and 40 pumping stations.
It will deliver to about 9,000 service points and 40 towns. Four main trunk pipelines will transmit water continually from the Grampians headworks to existing urban storages. Water from these storages will be distributed to on-farm tanks and then to households and stock troughs.
Water sourced from the Grampians headworks will continue to be supplemented by water from the Waranga Western Channel and the River Murray.
The first key benefit of the project is that it will provide near full supply in 93 years out of 100. The project's nominated target for an improved system is full supply in 96 years out of 100.
The unreliability of the existing system has been demonstrated over the past four years, where below average in-flows into the storages have resulted in:
- storage levels at 12% of capacity;
- only 33% of farm dams able to be filled, as at May 2001; and
- water restrictions in a number of towns.
Also, there is insufficient water for adequate environmental flows in the region's river systems, or to meet demands for existing and potential uses, including recreation and tourism, agricultural processing and other new industries.
The project will significantly improve the health of the Wimmera, Glenelg and other river systems that are used to supply this region. They have all suffered from changes to the flow regime (particularly the absence of low to medium flushing flows), poor water quality (elevated salinity and nutrient concentrations and depleted dissolved oxygen levels) and changes to geomorphology have disrupted ecological processes within the Wimmera River.Benefits
Other key benefits of the project include:
- more reliable and better quality water to the farms, towns and businesses of the Wimmera Mallee region;
- opportunities for regional economic development through on-farm diversification and new industry;
- restoration of the aquatic systems of the Wimmera and Glenelg rivers;
- increased frequency of flows to the region's nationally significant terminal lakes system, including Lake Hindmarsh and Lake Albacutya; and
- increased water for recreation purposes, with substantial flow-on tourism benefits.
These benefits will address many of the major problems being experienced in the Wimmera-Mallee region, such as curtailed agricultural productivity, "stressed" rivers and dry terminal lakes, and restricted recreation and tourism.
Water restrictions currently applied to stock and domestic and urban customers should not be experienced once piping has been completed.
Primary production will benefit mostly from the project. The pipeline will facilitate increased productivity through improved efficiency of existing farming operations, diversification of current activities (made possible by the additional 9,500 megalitre capacity of the domestic and stock system) and new development opportunities (generated by the additional 10,000 megalitre capacity provided for outside the current system boundaries).
Of these benefits, increased productivity generated by new development opportunities is directly attributable to the proposed allocation of 10,000 megalitres of the water savings to areas outside the current system boundaries.
Potential opportunities include premium, cool-climate wines in the Great Western and western Pyrenees areas, water supply for mineral sands mining and processing at Douglas, and piped water supply to towns such as Nhill.