Climate Change and Drinking Water
The issue of climate change impacts on local domestic water supplies has not yet been addressed by many climate campaigners. But as climate change impacts on water availability, it will increasingly also affect water quality.
New research by Friends of the Earth is revealing some localised impacts in Victoria which could have national ramifications. Of particular concern is the alteration to water quality, particularly in times of low environmental flows, which may be placing water consumers' health at greater risk. It should be pointed out that flooding and heavy rainfall also severely test water authorities abilities to provide safe drinking water, however issues associated with flooding have not been covered in this short article.
Substantial investment will be required for many regional drinking water treatment plants to respond to the problems of deteriorating water quality. Infrastructure costs needed to deal with perceived water shortages, such as desalination, have already severely tested Government resources across the country, and a large percentage of these costs could probably be attributed to climate change. The costs associated with being able to provide adequate quantities of safe drinking water are a significant aspect of what will constitute a meaningful adaptation response to climate change in coming years.
Most of Friends of the Earth's work in regards to drinking water quality has been focussed on risks associated with a range of pollutants, most specifically pesticides. However the risks posed by pesticides to drinking water can seem minor in comparison to risks associated with water treatment chemicals such as chlorine and aluminium, amongst others.
The Millennium Drought (1995-2009) impacted on water supplies throughout Victoria. The project completed by Friends of the Earth in 2010 “Water Quality Issues Ballarat, Bendigo and Benalla” focused on land use issues, however it also raised problems experienced by water authorities due to low rainfall scenarios.
[Image: Upper Coliban reservior, October 2006]
regional impacts – Victoria
Water levels in Ballarat's White Swan Reservoir fell to 7% in April 2008. This in turn caused problems through algal growth which inturn created increases in the organic chemicals Methylisoborneol (MIB) and Geosim. As a result, prolonged dosing with Powder Activated Carbon was required during the water treatment process which successfully removed 80% of the taste and odour compounds associated with MIB. Cyanobacteria was also detected and increased levels of Alum were required to deal with these problems.
Low reservoir levels also meant that water had to be taken from the lowest offtake in the reservoir, meaning higher levels of manganese, iron, colour, turbidity, alkalinity and organic content, which can also lead to dirty water with poor taste and odours. Low water levels in reservoirs can also cause stratification, where there is a distinct separation of a layer of warmer water at the top and colder layer of anaerobic water at the bottom. When the outside temperature drops during autumn the two layers mix, with manganese being oxidised during this process.
These issues were alleviated to a certain extent with the construction of the $180m Goldfields Superpipe completed in May 2008, which diverted Goulburn River irrigation water to the cities of Bendigo and Ballarat. The pipeline had to be fast tracked by two years, due to the critical supply situation in Ballarat and Bendigo.
The situation in Bendigo was also very serious, with one the city's water sources, Lake Eppalock reaching <1% of capacity between April and August 2007. A Blue-green algal (BGA) alert was announced in March 2007, advising the public to avoid direct bodily contact with water from Lake Eppalock for five weeks. Pumping from Lake Eppalock ceased in April 2007 due to high levels of Manganese, with levels up to ten times higher than normal being found in the lake. Stage 4 Water Restrictions were announced in Bendigo in September 2006.
Alert Level 3 for Toxigenic BGA was reached in May/June 2006 and 2007 and increases in salinity also occurred during 2006. Storage levels reached <1% of capacity from April to July 2007 before reaching 7% by the end of the year. The highest level of electrical conductivity was reached
in July 2007. Nutrient and turbidity levels also increased. Of the 36 most serious instances of BGA
recorded at Lake Eppalock over the past decade, 61% of these occurred in 2005/6 and 2006/7.
The Millennium Drought also caused problems in the south west Victorian town of Hamilton. Hamilton sources its drinking water from the Grampians National Park or more specifically seven
streams on the western slopes of the Victoria Range and three drought relief bores. Surface water flow from the Grampians actually ceased during 2006/7, meaning that Hamilton had to rely solely on groundwater sources.
Aluminium Sulphate is added by water authorities to assist in the process called coagulation. Serious problems started emerging with the Hamilton water supply in July 2007. An aluminium level of 19mg/L was reached at Hamilton in July 2008 (95 times over the Australian Guideline), possibly an Australian record, and possibly one the highest Aluminium levels recorded anywhere in the world.
The Hamilton source water is high in dissolved organic material and is also highly coloured. According to a statement from the water authority Wannon Water in 2010: “During winter months, the source water coming from the Grampians has extremely high colour and low turbidity. This requires higher doses of coagulant which reduces the pH significantly, and this causes coagulation issues and aluminium exceedance. High lime doses are also required to counter the low pH caused by high doses of coagulant. The lime system was difficult to operate and was not capable of dosing sufficient lime in response to water quality changes.”
High levels of Aluminium started to be detected in Hamilton in July 2007. The groundwater sources were of a different quality to the traditional surface water. Higher levels of salt, iron and manganese were some of the differences. Because the treatment process at Hamilton was not designed to optimally treat water of this highly variable make up, high levels of aluminium were detected. Essentially water entering the treated plant had deteriorated to the extent that was outside the design specifications of the plant. Due to drought Wannon Water was also attempting to capture as much of this water as possible.
The higher doses of Alum in late 2006 that were required to treat the water also made it difficult to control the pH of the chemically dosed water, which probably resulted in dissolved aluminium
passing through filters at the treatment plant.
The 52 kilometre Hamilton-Grampians pipeline was completed in June 2010, which has secured Hamilton's long term water needs. The excessive aluminium levels meant that a project team was established to deal with the problem, which eventually meant that $850,000 had to be spent on upgrading the water treatment plant through an undertaking with the Department of Health. How many other Australian communities will face the same dilemma in coming years, as higher levels of Aluminium are required to help treat increasingly worse quality water?
According to Aluminium Expert Professor Chris Exley (1): “It is my opinion that any value above 0.5 mg/L is totally unacceptable and a potential health risk. Where such values are maintained over days, weeks or even months, as indeed is indicated by the data you sent to me, these represent a significant health risk to all consumers. While consumers may not experience any short term health effects the result of longer term exposure to elevated levels of aluminium in potable waters may be a significant increase in the body burden of aluminium in these individuals. This artificially increased body burden will not return to 'normal' levels when the Al content of the potable water returns to normal but will act as a new platform level from which the Al body burden will continue to increase with age.”
Grampians Wimmera Mallee Water
Just north of Hamilton, many small communities in Victoria's Wimmera region suffered high levels of chlorine disinfection by-products (DBP's) during the 2009 drought. A severe water shortage was experienced across the region, with the capacity of some of GWMWater's headwork reservoirs falling as low as 2.5%. The prolonged drought meant that many communities who were reliant on water being channelled to their communities from the headwork reservoirs soon found that this could not occur, and they were left with older water which had been retained in their town storages. This water became more saline and the salinity directly impacted on the concentration of DBP's produced.
Chlorine disinfection products are formed when chlorine reacts with organic molecules in source water. Some DBP's have been linked with cancer. Seven hundred have been discovered by scientists since 1974. Approximately ten of these are tested for by Victorian water authorities, however it is highly likely that in many smaller communities elsewhere in Australia no testing is done. In October 2012, Friends of the Earth also revealed that high levels of DBP's, particularly the Trihalomethane Bromodichloromethane has been detected in several South Australian communities, including suburbs in Adelaide, above World Health Organisation Guidelines, for many years.
[Image: Lauriston Reservoir, near Kyneton]
Water authorities face a complex risk trade-off when dealing with the thorny issue of DBP's. On one hand there is the very real risk of increases in water-borne diseases if disinfection levels are lowered, compared to the lower risks associated with people potentially developing bladder and other cancers if exposed to high levels of DBP's. Alternative treatment plants may be the safest option, however for many communities these may be financially unviable.
For further information:
Friends of the Earth water campaigner
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South West Victoria. Wannon Water/Barwon Water
Specific Drinking Water Issues 2006-2012
Aluminium, Arsenic & Bromodichloromethane. March 2013
SA Water Drinking Water Quality
January 2000 – July 2012
Australian Drinking Water Overview
(1) Christopher Exley PhD
Professor in Bioinorganic Chemistry
The Birchall Centre, Lennard-Jones Laboratories,
Keele University, Staffordshire, ST5 5BG, UK
Tel: 44 1782 734080;