Wodonga – Victoria – Turbidity
16/10/10–17/10/10 Wodonga LL1 Dirty Water – elevated turbidity in reticulation (~13NTU)
Heavy rainfall within the catchment resulted in significant turbidity levels, which coincided
with changes to process configuration that led to blocked filters and subsequent elevated turbidity in drinking water. Response was rapid, which included significant flushing of water mains, as well as shutting down of pump stations, which isolated the turbid water to localised sections of the reticulation. Extensive monitoring was undertaken. Longer term actions included implementation of more rapid automated plant shutdown, stricter protocols when introducing process changes as well as improved infrastructure flexibility to run non compliant water to waste.
2010/11: Wodonga (low level) Turbidity 15NTU
2011/12: Wodonga (low level) Turbidity 10NTU
2013/14: Wodonga (low level) Turbidity 8NTU
2014/15: Wodonga (low level) Turbidity 18NTU
2016/17 Wodonga (high level) Turbidity 5.8NTU
2019/20 Wodonga (low level) Turbidity 62NTU
Chlorine-resistant pathogen reduction: Where filtration alone is used as the water treatment
process to address identified risks from Cryptosporidium and Giardia, it is essential
that filtration is optimised and consequently the target for the turbidity of water leaving
individual filters should be less than 0.2 NTU, and should not exceed 0.5 NTU at any time
Disinfection: A turbidity of less than 1 NTU is desirable at the time of disinfection with
chlorine unless a higher value can be validated in a specific context.
Aesthetic: Based on aesthetic considerations, the turbidity should not exceed 5 NTU at the
consumer’s tap.
Wodonga – Victoria – Iron
2015/16: Wodonga (low level) Iron 0.61mg/L
Based on aesthetic considerations (precipitation of iron from solution and taste),
the concentration of iron in drinking water should not exceed 0.3 mg/L.
No health-based guideline value has been set for iron.
Iron has a taste threshold of about 0.3 mg/L in water, and becomes objectionable above 3 mg/L. High iron concentrations give water an undesirable rust-brown appearance and can cause staining of laundry and plumbing fittings, fouling of ion-exchange softeners, and blockages in irrigation systems. Growths of iron bacteria, which concentrate iron, may cause taste and odour problems and lead to pipe restrictions, blockages and corrosion. ADWG 2011
Wodonga (Low Level) (Victoria) – Colour
2008/9 Wodonga Low Level (Victoria) – Colour 16HU (highest level)
Based on aesthetic considerations, true colour in drinking water should not exceed 15 HU.
“… Colour is generally related to organic content, and while colour derived from natural sources such as humic and fulvic acids is not a health consideration, chlorination of such water can produce a variety of chlorinated organic compounds as by-products (see Section 6.3.2 on disinfection by-products). If the colour is high at the time of disinfection, then the water should be checked for disinfection by-products. It should be noted, however, that low colour at the time of disinfection does not necessarily mean that the concentration of disinfection by-products will be low…
2020: Wodonga (Victoria) – Taste & Odour
Murray River Taste and Odour Event
Some towns in North East Water’s region supplied from the Murray system were affected by a taste and odour event from Australia Day in January through to March 2020. The taste and odour event was caused by naturally occurring taste and odour compound known as geosmin. This organic compound has a very strong, earthy taste and odour that is unpleasant. The compound can be produced by blue-green algae, bacteria and sometimes protozoa, and can be smelled at very low concentrations (around 10 ng/L). The compounds are generally present in drinking water but below noticeable levels. Geosmin can cause objectionable taste and odour in drinking water, but is an aesthetic issue only, with the water remaining safe to drink. In late January 2020, an algae bloom occurred in Lake Hume that produced extremely high concentrations of geosmin. The dominant algae species was Dolichospermum c.f. crassum, a known geosmin producer. This bloom subsequently spread downstream to Wodonga, Wahgunyah and Yarrawonga offtakes. This taste and odour event eventually spread much further down the Murray River and affected water utilities on both sides of the Victorian and NSW border.
Traditional treatment processes do not fully remove geosmin and instead powdered activated carbon (PAC) is dosed to adsorb the compound before removal via filtration. All of North East Water’s Murray system towns have this process in place, however, the concentrations of geosmin in the source water were so high that regular dose rates were unable to fully remove the compound from the treated drinking water. North East Water’s Yarrawonga supply experienced the highest concentrations of geosmin, peaking at 1,800 ng/L (see Table 3-27 for full results). This is the highest concentration ever recorded by North East Water. This resulted in a high rate of customer complaints relating to the taste and odour of water in localities supplied by Wodonga, Wahgunyah and Yarrawonga systems. The Corporation implemented customer communication via social media while the Operations teams were busy upgrading PAC dosing systems to achieve higher dose rates. North East Water 2019/20 Drinking Water Quality Report
Wodonga (Victoria) – Aluminium
2019/20: Wodonga Low Level (Victoria) Aluminium 3.3mg/L (max), 0.29mg/L (av.)
According to the ADWG, no health guideline has been adopted for Aluminium, but that the issue is still open to review. Aluminium can come from natural geological sources or from the use of aluminium salts as coagulants in water treatment plants. According to the ADWG “A well-operated water filtration plant (even using aluminium as a flocculant) can achieve aluminium concentrations in the finished water of less than 0.1 mg/L.
The most common form of aluminium in water treatment plants is Aluminium Sulfate (Alum). Alum can be supplied as a bulk liquid or in granular form. It is used at water treatment plants as a coagulant to remove turbidity, microorganisms, organic matter and inorganic chemicals. If water is particularly dirty an Alum dose of as high as 500mg/L could occur. There is also concern that other metals may also exist in refined alum.
While the ADWG mentions that there is considerable evidence that Aluminium is neurotoxic and can pass the gut barrier to accumulate in the blood, leading to a condition called encephalopathy (dialysis dementia) and that Aluminium has been associated with Parkinsonism dementia and amyotrophic lateral sclerosis, the NHMRC, whilst also acknowledging studies which have linked Aluminium with Alzheimer disease, has not granted Aluminium a NOEL (No Observable Effect Level) due to insufficient and contradictory data. Without a NOEL, a health guideline cannot be established. The NHMRC has also stated that if new information comes to hand, a health guideline may be established in the future.
In communication with Aluminium expert Dr Chris Exley (Professor in Bioinorganic Chemistry
The Birchall Centre, Lennard-Jones Laboratories, Keele University, Staffordshire UK) in March 2013 regarding high levels of Aluminium detected in the South Western Victorian town of Hamilton
“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.