APPENDIX 1

Since the use of weather satellites began in the 1960s, great advances have been made in understanding the world’s weather patterns. This has enabled scientists to explain and even predict the cycles of droughts and floods that are so much a feature of the weather pattern over much of Australia.

El Nino, La Nina and Southern Oscillation Index are terms used to describe a major influence on this weather pattern.

El Nino refers to the extensive warming of the central and eastern Pacific Ocean that leads to a major shift in weather patterns across the Pacific. In Australia, and particularly in the eastern part of Australia, El Nino events are associated with an increased probability of dry conditions. The most recent strong El Nino event was 1997/98. Another weak to moderate event occurred in 2002/03, causing major rainfall deficiencies across the country.

La Nina describes the reverse of the El Nino effect and is related to changes in atmospheric conditions and ocean circulation. In Australia, and particularly in the eastern part of Australia, La Nina events are associated with an increased probability of wetter conditions. The most recent strong La Nina was 1988/89, a much wetter than average season across much of Australia. A fairly weak La Nina event occurred in late 1995 and early 1996, leading to conditions slightly wetter than average in many areas. A moderate event occurred in 1998/99, which weakened back to neutral conditions before forming again for a shorter period in 1999 and ending in 2000.

The Southern Oscillation Index describes a key indicator of this weather pattern based on measurements of atmospheric pressure. It is used to predict the likelihood of extended very wet or very dry periods.

The El Nino phenomenon affects runoff in catchments serving all major Australian water supply systems.

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Where sufficient low-cost water is available, irrigated agriculture is practised in Australia. This activity is attracting increased attention from government policy-makers as concern grows at the proportion of water flows taken from the environment and at how efficiently water is used in irrigated agriculture.

In recent years, the irrigation industry has undergone major changes in the way it is structured, in the way water is priced and with the use of market mechanisms to reallocate resources to more productive uses. Efforts have also been made to promote efficient and sustainable irrigation practices.

In the past, state governments have met the cost of establishing the irrigation industry. The price structure for irrigation water is now moving to better reflect the value of the resource.

It is difficult to provide a typical figure for the cost of water used in irrigated agriculture because it is influenced by many factors. However, a large proportion of irrigation water would be available for less than $50 a megalitre.

In contrast, one megalitre of good quality drinking water would cost an urban household in Australia between $500 and $1,000 piped to their home.

Vegetables and fruit are the most valuable irrigated crops per megalitre of water used while rice produces the lowest value. Rice is also the thirstiest crop per hectare of irrigated area.

Further information about irrigation in Australia can be obtained from several sources, including CSIRO Land and Water ( http://www.clw.csiro.au ), the National Program for Irrigation Research and Development ( http://www.npird.gov.au ) and the Irrigation Association of Australia ( http://www.irrigation.org.au ).

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In some limited areas, catchments exist in their natural state and minimal water treatment is needed. For example, most of the water supply for Melbourne and Canberra comes from natural wilderness catchments set aside solely for water harvesting.

In contrast, most of Adelaide’s water is derived from the Murray River, the catchment for which is a vast area of Australia, home to almost two million people, containing more than 50,000 farms and referred to as the Murray Darling Basin. The other significant source of Adelaide’s water supply is harvested in the catchments of the Mount Lofty Ranges.

Within larger catchments, water harvesting can be one of a variety of often competing activities. Other activities such as logging, farming, mineral extraction, recreation and tourism, as well as residential and industrial development, may occur.

As Australia has been developed, increased urbanisation, industrialisation and intensive farming have affected the quality of water entering streams and rivers. The water collected by such waterways requires varying degrees of treatment before it is suitable for drinking.

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The Murray Darling Basin, located in south-eastern Australia, is of particular significance as a catchment. It contains Australia’s three longest rivers, the Darling (2740km), the Murray (2530km) and the Murrumbidgee (1690km). It also drains 18.2 per cent of the land area of Australia containing 42.3 per cent of the nation’s farms. Irrigation in the Murray Darling Basin accounts for about 70 per cent of the water used in agriculture in Australia.

Detailed information on the Murray Darling Basin can be obtained from the Murray Darling Basin Commission (www.mdbc.gov.au)

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The major source of Adelaide's water is the Murray River. This water is supplemented by water from catchments in the Mount Lofty Ranges. This locally harvested water is stored in various water supply reservoirs around Adelaide.

The proximity of these catchments to Adelaide has meant that grazing, broad scale cropping, intensive horticulture and urban development have occurred there. For example, more than 70 per cent of the Onkaparinga catchment, which supplies the Mount Bold and Happy Valley Reservoirs, is affected by urban developments, intensive horticulture or mixed agriculture.

Land use and water quality are closely linked. Water running from undisturbed native vegetation is of the highest quality, while water coming from developed areas, particularly where there is urban development and intensive horticulture, is of lesser quality.

Because of the poor quality of the source waters, the water supply for Adelaide requires extensive treatment before it is distributed for use.

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Source: ANCOLD Register of Large Dams in Australia

Generally speaking, few additional sources of surface and/or groundwater remain unexploited to meet the future needs of major urban communities in Australia. These communities are demanding that the environment be managed in a sustainable manner. This will require more water resources being allocated to the environment rather than less. The water supply industry can no longer rely on building new dams to quench the thirst of growing cities. It needs to consider other strategies to match supply with demand.

In these circumstances, governments and industry have started to regard treated urban wastewater (sewage) flows as a potential resource rather than an effluent to be quickly discharged back into the environment at the nearest convenient point. Urban stormwater flows are also being examined for their potential as a water source.

While it is technically feasible to treat these sources to drinking water quality, as currently happens with most raw water supplies, there are greater public health risks, requiring multiple precautions and incurring greater costs.

Furthermore, the human psychological resistance to consuming our "own" has been a major public disincentive for further considering these schemes, despite the fact that all water is eventually recycled.

Indirect use of wastewater for drinking has been occurring for a long time, particularly in denser populated areas, such as Europe and the United States, where flows from upstream cities and towns are fully treated before being discharged to cities and towns downstream. Recycling of river water in this way occurs less frequently in Australia, due to our smaller and less dense population.

In a recent development in South Australia, below ground storage of treated effluent is being investigated where aquifers are being recharged. The water is intended for irrigation. For further information see: http://www.groundwater.com.au

In recognition of the need for national guidance on water reuse for a range of different purposes, in 2004 the Environment Protection and Heritage Council and the Natural Resource Management Ministerial Council initiated the development of National Guidelines for Water Recycling (http:/www.ephc.gov.au/ephc/water_recycling.html) The guidelines will comprise a risk management framework and specific guidance on managing the health risks and the environmental risks associated with the use of recycled water. The first stage of guideline development will be completed in 2006.

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These guidelines are subject to review by these organisations and are updated as new medical and scientific information becomes available. The review is a transparent process and submissions are routinely invited from the public, interested organisations, state and federal governments, and scientific and professional bodies. Scientists associated with the Cooperative Research Centre for Water Quality and Treatment are contributing to this review process.

The document provides guidance to the Australian water industry on the treatment levels and procedures needed to manage water supply systems that are required to produce safe and pleasant drinking water.

An Internet version of the Australian Drinking Water Guidelines can be found at http://www.nhmrc.gov.au/publications/synopses/eh19syn.htm

Bacteria are tiny, single-celled microorganisms that are often observed forming colonies. They can occur in various shapes, for example, round, rod-like, or spirals. Typically, they can be as small as half to one micron wide, and as large as several microns long.

Bacteria capable of causing human illness through contaminated water supplies include Campylobacter, Salmonella, Shigella, Vibrio and Yersinia.

Other bacteria of environmental origin may be found in water supplies including Aeromonas, Legionella, Mycobacterium and Pseudomonas aeruginosa. If found in drinking water, these bacteria are generally less of a health risk than those of faecal origin.

Viruses are a large group of infectious agents, much smaller than bacteria, and are able to be viewed only through an electron microscope. They are not cells but biologically active particles that vary in size from 0.01 to 0.1 microns.

Viruses may survive in the environment for some time in soil or water, but they cannot multiply unless they infect a suitable host. The viruses that are of concern for water supplies can only infect humans, therefore they can arise only from human waste.

Viruses cannot be simply cultured in the laboratory in the way bacteria are identified, and for this reason it is difficult to detect viruses.

Problem viruses identified in the Australian Drinking Water Guidelines include adenovirus, enterovirus, hepatitis viruses, norwalk viruses and rotaviruses.

The term protozoa refers to a collection of generally colourless, single-celled organisms with a well-defined nucleus. They are much bigger than bacteria, ranging in length from 5 to 100 microns.

Protozoa are among the simplest of all living organisms. As a group, protozoa are extremely diverse. Pathogenic protozoa found in water supplies include Cryptosporidium, Giardia, Cyclospora, Naegleria, Acanthamoeba and Entamoeba.

Other causes of waterborne disease in humans include helminths. These worms or worm-like parasites infect the intestine and include roundworms, tapeworms and flatworms. The worms in humans that originate from helminth eggs are relatively easy to cure and present a problem only in developing countries where proper nourishment is a problem.

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Four types of water-related diseases are recognised in public health:

Waterborne diseases are those where a person contracts the disease by drinking water contaminated with the disease-causing organism. Most diseases of this type are spread by the faecal-oral route (for instance, by swallowing small amounts of faecal material in water, in food, or from hands).

Water-washed diseases are those which can be reduced by improving domestic and personal hygiene. Such improvements in hygiene usually depend on the increased availability of water for washing people, cooking utensils and clothing, rather than the quality of the water.

These diseases include pathogens that are transmitted by the faecal-oral route, as well as skin and eye diseases such as scabies, bacterial and fungal skin infections, and trachoma. Other health problems, such as lice and ticks, are also reduced by better hygiene.

Water-based diseases are those where the pathogen spends part of its life cycle in a water snail or other aquatic animal. These diseases are caused by parasitic worms, and include schistosomiasis and dracunculiasis (Guinea-worm).

Water-related insect-borne diseases are carried by blood-sucking insects that breed in water or by insects that bite near water. Examples of these are diseases such as malaria, yellow fever and dengue fever that may be carried by mosquitos, and trypanosomiasis (sleeping sickness) carried by tsetse flies.

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When drinking water treatment was first developed, it was recognised that faecal contamination from humans and animals posed the greatest threat to water supplies. A need was recognised to test untreated water to determine whether such contamination had occurred, and treated water to check that contamination had been successfully removed.

However, testing water for harmful microorganisms was not practical because knowledge of the organisms responsible for disease was very limited and the methods for detecting them were complex and time consuming.

Instead, public health microbiologists decided to search for microorganisms that were always associated with faecal pollution, but did not cause illness. The desirable properties of such microorganisms were:

• Always present in faeces of humans and animals.
• Present in high numbers.
• Easy to detect by simple and inexpensive methods.
• Unable to multiply after they had left the body and entered the water supply.

Thus the presence of indicator microorganisms could serve as a warning that faecal contamination had occurred, and that faecal pathogens might also be present in the water supply. A series of indicator organisms was identified, and these became the basis of microbiological quality monitoring around the world.

This group of bacteria includes E. coli and other intestinal bacteria that are able to grow at 44° C. It also includes some bacteria that live in decaying vegetation and agricultural or industrial waste. In some laboratories, a slightly different testing method is used, and the bacteria detected are called faecal coliforms. Faecal coliforms and thermotolerant coliforms are essentially the same.

Thermotolerant coliforms are less specific indicators of faecal contamination than E. coli, because they may sometimes arise from non-faecal as well as faecal sources.

This is a larger group of bacteria which includes E.coli and faecal coliforms. It also includes many non-faecal organisms that can grow in the environment. Total coliforms occur in much greater numbers in water sources than faecal coliforms or E. coli, and for this reason changes in their numbers (reduction by disinfection) are easier to detect.

Total coliforms are not good indicators of faecal contamination, because they may originate from many sources other than faeces. Increases in their numbers in water distribution systems may be due to regrowth or external contamination.

Microbiologists can often tell the difference between contamination and naturally occurring microorganisms in the pipeline. Contamination is likely to produce a growth of fairly uniform and limited number of species; natural growth is likely to contain a much wider variety of organisms.

The HPC measures a broad group of bacteria that are defined by their ability to grow under certain laboratory conditions. These bacteria have no direct relationship to faecal contamination or health risks but are used as a general indicator of the microbiological content of water, and the levels of nutrients that can support bacterial growth.

An elevated HPC can be useful as an early indicator of excessive bacterial growth (possibly regrowth during warmer periods) in the distribution system, particularly on pipe walls and sediments.

The HPC can also be a useful measurement to water authorities in managing disinfection in distribution systems.

It has long been recognised that among indicator organisms, E. coli provides the most specific warning of faecal contamination, however in the early 1900s there was no simple test available to distinguish E. coli from other coliform bacteria.

The observation that E. coli formed the majority of coliform bacteria in human faeces, and that total coliforms were readily isolated from contaminated waters, led to the belief that the presence of total coliforms reflected the presence of E. coli. Therefore total coliforms were adopted as the standard indicator organism. At the time, sanitation standards were low and faecal contamination of water supplies was common. As such, total coliforms were a reasonable surrogate for E. coli.

As sanitation standards improved in developed nations, faecal contamination of water supplies became less common. The percentage of total coliforms in water that were of faecal origin declined, and total coliforms were no longer a good indicator of faecal contamination.

In 1948, the more specific test for faecal/thermotolerant coliforms was developed, and this was soon adopted for general use in water quality monitoring. Total coliform testing was retained because it had already gained wide acceptance.

Over the years, the test methods used to identify coliform organisms have been changed to make them simpler and more rapid, however this has also meant that more non-faecal bacteria are now detected by the tests. Therefore the relationship between these indicator bacteria (total coliforms and faecal coliforms) and faecal pollution is not as definite as it used to be.

More recently, rapid and inexpensive methods for identification of E. coli have been developed, and this organism is being adopted as the primary indicator organism in a number of countries.

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Cyanobacteria, also known as blue-green algae, are a group of microorganisms with bacteria-like properties. Although not pathogenic themselves, that is they cannot bring about an infectious disease, they produce toxins which are of considerable concern to water supply and public health authorities.

Cyanobacteria are naturally occurring components of all aquatic environments. Individual cells are microscopic but are capable of dividing and doubling every two to three days and forming thick smelly green scum, the consistency of paint, on water surfaces. These concentrations of cyanobacteria are often referred to as "blooms".

The species that most commonly affect water supplies in Australia are:

• Anabaena (reservoirs and slow-moving rivers).
• Microcystis and Cylindospermopsis (reservoirs and dams).
• Nodularia (brackish waters).

Some cyanobacteria produce toxins that can kill animals and are highly toxic to humans. For example, microcystin LR (produced by Microcystis) has a relative toxicity 1000 times greater than cyanide.

Some cyanobacterial toxins can damage the tissues of vital organs such as the liver and kidneys, and even the skin. Other cyanobacterial toxins damage nerve cells. There is also concern regarding long-term exposure to some toxins which have been demonstrated to be carcinogens.

There is some debate as to the cause of blooms and in fact whether there is an increase in their occurrence. There is no doubt that the presence of nutrients (such as phosphate and nitrate), strong sunlight and slow flowing warm water are conditions which favour bloom formation.

In Australia, water authorities monitor their water sources for cyanobacteria during warmer, sunny periods - conditions that favour growth of cyanobacteria.

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