Historical pesticide monitoring of Victorian waterways – a jigsaw with many missing pieces

Anthony Amis

From Chain Reaction #122, Nov 2014, www.foe.org.au/chain-reaction

"In Victoria no information is available on contamination of water supplies although fish mortalities from time to time in some streams are an indication that some pesticides from farms lands are getting into water which may be drawn off for town supply."

Commission of Enquiry Into Effects Of Pesticides, 1966

For some time I have been researching the impacts of pesticides on waterways. I have been particularly interested in the impacts of pesticides on human health and ecology. The focus of my research has been domestic water supplies. Because I have been based in Victoria for the past 30 years, my attention has been on Victorian waterways. Much of the data gathering has required years of Freedom of Information requests. Data has been sparse because in most cases the information did not exist at all or was buried in unpublished government reports.

One area of research that appears to have passed many people by is the impact of spraying weeds in irrigation channels and drains. Victoria was the first state in Australia to start a massive irrigation scheme with the construction of the Goulburn Weir between 1887 and 1891. Water from this weir was diverted across hundreds of thousands of hectares of land throughout northern Victoria. Since the late 1800s, much of this region has been criss-crossed by tens of thousands of kilometres of channels and drains. Regular spraying of these channels and drains with herbicides as a means of controlling aquatic weeds, including natural vegetation, has occurred since the 1950s. Some of the channels and drains outflow into natural streams, with herbicides contributing to ecological decline in those streams. Some natural streams have been sprayed directly.

I have also been interested in the continuing impact of legacy chemicals, or those long-lasting, highly toxic chemicals that were used frequently until the 1990s, when regulators took the chemicals off the market due to safety concerns. It is important to understand that in terms of health problems, illnesses may not be observed until many years after exposure. Many people suffering illnesses today may have been exposed decades ago.

Over 60 communities currently rely on drinking water from irrigation channels in Victoria. Herbicides are commonly used in channels and drains. Acrolein, for example, is injected directly into flowing water, whilst amitrole, glyphosate and 2,4-D are spot sprayed when the weeds are not submerged. Excessively high levels of 2,4-D, glyphosate and amitrole were detected in Goulburn-Murray Water drains in 2006. Goulburn-Murray Water has also sprayed glyphosate into water supplies such as Broken Creek and Nine Mile Creek. The Murray River and water bodies such as Lake Nagambie are also sprayed. Channel water can also be diverted to supply raw water for potable use. It is likely that communities relying on channel water have been exposed to dangerous levels of herbicides in the past; however, monitoring of pesticide residues simply did not occur.


Pesticide Action Network lists amitrole as a carcinogen and suspected endocrine disruptor. It also affects thyroid function. Amitrole's Health Guideline in the 2011 Australian Drinking Water Guidelines (ADWG) is 0.9 parts per billion (ppb). This was reduced from 10 parts per billion under the preceding 2004 guidelines, a reduction of 91%. No explanation of this reduction was given in the ADWGs, which are determined by the National Health and Medical Research Council. It also means that levels of amitrole under 10 ppb, would not have been regarded as "dangerous" as recently as 2011 before the new Guidelines were published.

Amitrole was and is used widely across irrigation areas of Victoria as a control to aquatic weeds such as couch grass in drains and channels. Approval was first given in September 1962 at the Intergovernmental Committee on Pesticides for the State Rivers and Water Supply Commission (SRWSC) to use amitrole provided that the level in domestic drinking water did not exceed 300 parts per billion. Gippsland was excluded from this approval as it is a goitre (enlarged thyroid gland) area. In June 1963 the Commission adopted a maximum concentration of amitrole in streams of 2 ppb.

SRWSC started testing for amitrole in 1962. Sample sizes were small and by 1965 only 47 samples were tested, mainly from, the Murray River at Swan Hill and the Tongala Drain outfall near Echuca on the Murray River. By 1970/71, 297 samples had been taken from rivers, drains and streams. Five samples gave a positive reading of between 30 and 100 ppb. Up until 1970, the limit for analytical determination was 30 ppb, dropping to 8 ppb a year or so later. This means that no amitrole would have been detected at levels now regarded as dangerous, a ruse often employed by government agencies.

By 1971 about 2000 pounds of amitrole had been used to control couch grass in drains in Victoria, the same year that the US Environmental Protection Agency banned amitrole for crop use in the US. Excessively high levels of amitrole were recorded in the Murray River at Swan Hill in 1972 and Broken Creek in 1972. Broken Creek is a domestic water supply for Nathalia, Numurkah and Wunghnu and the Murray River is the drinking water supply for Swan Hill and many communities along the Murray, including Mildura.

As discussed, the Health Guideline for amitrole in the 2011 Australian Drinking Water Guidelines is 0.9 parts per billion. The highest levels recorded in Nathalia and Swan Hill in 1972 were 430 and 320 ppb respectively! As far as I can determine, these two cases are the most serious concerning water contamination by pesticides in Victoria and possibly Australia. Amitrole was recorded in Broken Creek at levels above current drinking water guidelines regularly between 1973−75.


In 1968, the SRWSC was alarmed by the increasing amount of paraquat used in streams to control cumbungi. Possibly 5 gallons of paraquat was used in drains and channels in the Kerang region with another 20 gallons used in drains at Nathalia. Paraquat is highly toxic to humans and the SRWSC was concerned that "some of the chemical will be entering water systems which could eventually be used for human consumption". As little as one teaspoon of the herbicide is lethal and it is currently the leading cause of fatal poisoning in the Pacific, Americas and Asia. Paraquat currently has an Acceptable Daily Intake four times higher than amitrole, yet for some reason the SRWSC didn't appear to be as concerned with amitrole.


The Victorian state government owned the patent for 2,4-D application in waterways in the 1950s. In 1971 the SRWSC began testing the Broken Creek at Nathalia for 2,4-D residues. 2,4-D was directly applied to the creek as a means of controlling weeds and had been for some years. It was regularly detected during the two months when testing occurred in June and December 1971. 2,4-D and glyphosate are still used in Broken Creek to control aquatic weeds, with high readings recorded at Numurkah in 2006.

The Pesticide Action Network classes 2,4-D as a potential carcinogen and suspected endocrine disruptor. It can also contain dioxins, as a result of impurities in the manufacturing process. It is possible that communities relying on Broken Creek for drinking water have been ingesting both 2,4-D and amitrole for decades.

Ovens River

In 1971/72 pesticide testing was also established in the Ovens River, which supplied the town of Wangaratta with drinking water. The Ovens River was also home to Victoria's "notorious" tobacco industry, which had been linked to pesticide pollution for many years.

The Commission of Enquiry Into Effects of Pesticides noted in its February 1966 report: "Evidence was received concerning the tobacco growing areas along the Ovens, King and Buffalo Rivers that weekly spraying with persistent insecticides and fungicides is a routine practice and that a proportion of the spraying is done by aircraft. Fish have been killed on occasions when pesticides have reached the river ..."

Five different pesticides were recorded in Wangaratta filtered water in 1971/72, namely HCB, TDE, lindane and DDT. My family was living in Wangaratta at this time. Twenty years later more tests were conducted into Wangaratta's drinking water by the Victorian Enivironmental Protection Authority. High levels of heptachlor and dieldrin were detected. Is it possible that residents in Wangaratta were consuming pesticide-tainted drinking water for decades?

The ABC reported in 2005: "Melbourne scientists have helped to explain why women in an area of Victoria's north-east have a much higher incidence of breast cancer. Monash University researchers analysed the breast milk of hundreds of Victorian women for traces of pesticides. Dr Narges Khanjani says the highest levels have been found in samples from women in the Ovens Valley district. She says it is an area where organochlorine pesticides have been used on tobacco crops since the 1940s." (ABC, 29/1/05, 'Breast cancer cluster linked to crop chemicals'.)

Increased herbicide arsenal

By 1972 the SRWSC had increased its herbicide arsenal against a variety of aquatic weeds to include the following: acrolein, dalapon, amitrole, ammonium sulphate, copper sulphate, Diuron, atrazine, boron trioxide, picloram, 2,4-D and xylene.

Diana Crumpler wrote in a 1994 book: "Another time, a herbicide was added directly to the water and allowed to wash downstream. Our neighbour, Lionel, was told by one of the government workers that they had to drop the chemical in the channel from a bridge on the main road, because it was too explosive to carry across country. And then Lionel collapsed when the fumes wafted up from the channel near where he was working. In later years, when we were discussing events with Lionel, we came to suspect that this particular herbicide was acrolein − because the warnings we received to remove stock from the channel, and our indirect discovery of the chemical's explosive nature and its extreme volatility, all match what we now know to be the properties of acrolein.” (Chemical Crisis − One Woman's Story − Humanity's Future, Scribe )

Use of phenoxy herbicides 2,4-D and 2,4,5-T was also common throughout state rivers and the water supply system during the 1960s and 1970s. 2,4,5-T was used to kill blackberry in the Mornington Peninsula, Coliban and Koo-Wee-Rup systems. 2,4-D was used to kill furze, arrowhead, rushes, and woody species in Koo-wee-rup, Shepparton, Coliban and Murray Valley. Herbicides were also regularly used in the Macalister Irrigation District in Gippsland. Both 2,4,5-T and 2,4-D can be contaminated with dioxins, some of the most toxic substances known.

Pesticide exposure from aquatic weed spraying in and near irrigation areas such as Swan Hill, Wangaratta, Numurkah, Nathalia and Wunghnu is likely to be the tip of the iceberg. In 2005 three pesticides including esfenvalerate were detected in a channel that supplies the town of Kerang with drinking water in Victoria's most serious pesticide-in-drinking-water case in the past 40 years. This event was never publicly reported. A number of other towns in Victoria that rely on channel water have also recorded levels of pesticide residue over the past decade. The problem appears to be that the communities are small, and that the economic power of the chemical and agricultural industries, along with compliant regulatory bodies, allow the problem to continue to be swept under the carpet.

Anthony Amis is a member of Friends of the Earth Melbourne. [email protected]

More information:

Pesticide detections between 1998−2012: www.foe.org.au/sites/default/files/PesticidesVictorianWaterSupplies1998-...

Weed sprayers demand action

The Ballarat Courier has recently run a series of articles concerning the ill-health of workers who were involved in spraying herbicides for the Lands Department from the 1960s to the 1980s. The Victorian Labor opposition and federal opposition leader Bill Shorten are calling for a public inquiry into the issue, which has seen workers die young and suffer from horrible diseases.

It appears that the workers were exposed to high levels of dioxin associated with the spraying of 2,4,5-T to kill a variety of weeds. Friends of the Earth supports an inquiry, but we would like to see it broadened to include other people who were exposed to the pesticides either through spray drift or water pollution.

The Victorian government ran a similar inquiry in 1978 after a cluster of birth deformities was found in the South Gippsland town of Yarram. The results of that inquiry were controversial because of poor statistical assumptions that were used at the time. Unions have been concerned about these problems for decades.

− Anthony Amis