In February, Friends of the Earth sent a Freedom of Information request to Gippsland Water for information pertaining to pesticide detections in drinking water between 2017-2024 and PFAS detections at Gippsland Regional Organics facility at Dutson Downs. FoE received information back from Gippsland Water in early April 2025. The Dutson Downs information can be viewed here.
Pesticides can find their way into drinking water supplies mainly through runoff, accidents and spray drift. The FOI data reveals 111 pesticide detections over the 8 year period (~14 incidents per year). This information is generally not publicly provided because if pesticide levels don't exceed drinking water guidelines they do not have to be reported in annual drinking water quality reports by water authorities. Pesticides leaching offsite into waterways are generally not tested in Victoria with water authority data being the main source of determining what pesticides are being sprayed where and which are ending up in drinking water supplies.
Gippsland Water now has a rigorous pesticide testing procedure which is a step forward from over a decade ago when pesticide testing was 'sporadic'. It should be noted that although there were 111 pesticide pollution incidents, all except one occurred in raw water, prior to treatment at water treatment plants. Depending on the treatment used, pesticide levels are generally reduced by water treatment.
21 different pesticides were detected in Gippsland Water tests, with nine water supplies detecting pesticides. Over 115,000 pesticide tests were conducted by Gippsland Water between 2017 and 2024. About one third of these tests were conducted at two locations at Moe, one on Narracan Creek and the other on the Tanjil River.
This short summary has helped shed a spotlight on pesticides detected both in raw water supplies (before treatment) and has compared detections to drinking water guidelines and ecological guidelines.
If you want to make a tax deductible donation for our pesticide research, you can do so here.
Map highlighting where pesticides have been detected in raw water (pre treatment across the Gippsland Water network). Red pins indicate the amount of detections. Blue pins represent no detections. 53% of all detections were in the Moe domestic water supply. Information for Moe was listed in the FoI information simply as Site 1 and Site 2. Moe get their drinking water from Narracan Creek and the Tanjil River. It is most likely that the highest number of detections were in the Narracan Creek catchment. Moe Water Treatment plant does employ a Granular Media Filter which would be expected to lower pesticide residuals. Moe Water Treatment plant provides drinking water to Moe, Darnum, Newborough, Yallourn North, Trafalgar and Yarragon.
No traces of pesticides were detected at Boisdale, Boolara, Churchill, Cowwarr, Drouin, Erica, Jumbuk, Morwell, Newborough, Noojee, Rawson, Rokeby-Buln Buln, Rosedale, Sale, Stratford, Thorpdale, Toongabbie, Traralgon, Traralgon South-Hazelwood, Tyers-Glengarry, Willow Grove, Yallourn North, Yarragon or Yinnar.
Narracan Creek catchment, with Moe drinking water offtake marked with red pin, looking south west towards Thorpdale. FoE is assuming that this is Site 1 as listed in the Gippsland Water FoI data. 42% of pesticide detections throughout the Gippsland Water network between 2017-2024 most likely occurred in the Narracan Creek Catchment. The most frequently detected pesticides at this location were 2,4-D (17), Triclopyr (14) and MCPA (7). Other pesticides detected included: Bromacil, Picloram, Metolachlor, Prometryn, Fluproponate and 2,4-DB. The average level of Triclopyr detected between 2017-2024 from 110 samples was ~0.007µg/L, with the highest level being 0.3µg/L (or 1.5% of the drinking water guideline). Almost 13% of water samples therefore contained traces of Triclopyr, with 15.4% of samples containing 2,4-D. The most serious ecological impact could have been associated with a detection of Metolachlor in November 2018 over two times higher than the 99% ecological default guideline level of 0.0084µg/L. Pesticides were detected in 28% of pesticide screens between 2017-2024, with most samples occurring between late winter, early summer. Gippsland Water also increased sampling to once a week during this time of the year. Hundreds of pesticides are tested for.
The Tanjil River catchment with the number of pesticide detections marked with the red pin. The Tanjil River is also part of the Moe drinking water supply. The Latrobe River can be seen on the left side of the image. The most frequently detected pesticide in the Tanjil River was 2,4-D (8), MCPA (2), Atrazine (1) and Flupropanate* (1). (*registered for use against grass species). The average level of 2,4-D was 0.049µg/L (or 0.16% of the Australian drinking water guidelines. The large water body is Blue Rock Dam 8km west of the Moe drinking water offtake.
Mirboo North water supply is sourced from the northern Little Morwell River catchment. A large section of the catchment is forested, but there are also farms in the catchment. The herbicide Bentazon was detected 11 times in raw water at Mirboo North water treatment plant between 2017-2024. Bentazon is registered for use in Victoria to control broadleaf weeds in some types of bean crops. It is also allowed to be used on lawns. According to FoE records Bentazon has only been detected in one other water supply in Australia. Triclopyr was detected once in treated water at 0.1% of the Australian Drinking Water guidelines. The average level of Bentazon in raw water between 2017-2024 was ~0.007µg/L (with the highest level being 0.2µg/L in October 2018, or 0.05% of the Australian drinking water guideline). Other pesticides detected at Mirboo North include: Paraquat, 2,4-D, Metribuzin, Atrazine, Picloram, Prothios and Terbufos. The Terbufos detection was the highest in terms of drinking water concerns, representing 2.2% of the drinking water guideline in April 2020. Only 4 of the pesticides detected at Mirboo North have ecological guidelines, with a detection of Paraquat in December 2018 being 6.2% of the 99% default guideline level. This is the first time that Paraquat has been detected in a domestic water supply in Australia, according to FoE records. Paraquat is a high controversial herbicide linked with Parkinsons Disease. Paraquat has been banned in 70 countries.
Neerim South can source its drinking water from the Tarago Reservoir and Icy Creek/Deep Creek near Noojee. The exact source of the significant pollution incident at Neerim South has not been identified. Both the organophosphate insecticides, Diazinon and Chlorpyrifos were detected on the 17th of October 2024. The herbicide Metolachlor was also detected. Because of the exceedingly low 99% ecological levels for Diazinon (0.00004µg/L, Chlorpyrifos (0.00003µg/L) and Metolachlor (0.0084µg/L) any detection of these three pesticides in water is likely to exceed ecological guidelines. Only the 17th of October 2024, Chlorpyrifos was detected at 0.01µg/L, Diazinon at 0.01µg/L and Metolachlor at 0.01µg/L. These levels exceed the 99% Ecological Default Trigger Level by 333 times, 250 times and 1.2 times respectively! What was the source? Was there an investigation? Ecological guidelines do not generally apply to water reservoirs. Such high pulses of insecticides may have an impact on macroinvertebrates in rivers and fish. Metolachlor as a herbicide will impact on river algae. Tarago Reservoir also supplies some communities in the Melbourne Water system. All detections however were well under Australian Drinking Water Guidelines. Ecological guidelines do not generally apply to water reservoirs.
Graphs
Gippsland Water's risk assessments have obviously highlighted Moe in terms of pesticide risks, hence the large amount of testing there. Moe is followed by Seaspray, Neerim South, Mirboo North and Briagolong. Briagolong is the only community sourcing from bore water. Moe raw water was tested at two locations, with Seaspray tested at 4 locations.
Pesticide detections were dominated by the herbicides 2,4-D, Triclopyr, Bentazon and MCPA. 25 of the 40 2,4-D detections were at Moe.
Of the 21 pesticides, 16 (76%) have guideline levels published in the Australian Drinking Water Guidelines (which haven't been updated since 2011). In terms of ecological guidelines 8 of the 21 pesticides (38%) have guidelines. (Some guidelines eg for Atrazine and 2,4-D not being updated for a quarter of century). For 62% of the pesticides types detected it is therefore unclear what the ecological impact could potentially be.
Of the 111 pesticide detections, 53% occurred in the domestic water supply for Moe. Moe has two sources of drinking water, the Tanjil River and Narracan Creek. 47 of the 59 pesticide detections occurred at Moe (Site 1), with 12 occurring at Moe (site).
Most pesticide detections occurred in 2021.
Detections mainly occur between August and November - which is when the most spraying is done. Moe water supply is also targeted for more frequent testing during these months.
The average pesticide level across Gippsland Water was 0.0559µg/L. This total was increased due to higher averages detected at Seaspray (due mainly to a Clopyralid detection of 1.8µg/L in November 2022).
Average levels of pesticide detections, as a percentage in comparison to Australian Drinking Water Guidelines were 0.173%. The highest average level was at Heyfield, which recorded one detection of Fenthion at 1.143% of the drinking water guideline in July 2017. 103/111 (92.8%) positive results had a drinking water guideline level. These results are inflated in terms that the graphs do not include all detections, just positive detections.
In terms of ecological guidelines, the average level of detected pesticides, as a percentage in comparison to 99% Default Trigger Levels were 962%, due mainly to the two detections of Chlorpyrifos and Diazinon at Neerim South in October 2024. If those detections are excluded the average level decreases to 4.5% of the 99% Default Guideline level. 61/111 (54.9%) positive results had an ecological guideline level. Of the eight pesticides that have a 99% Default Guideline, the only detections of Chlorpyrifos and Diazinon were 333 and 250 times higher than the guideline. Two detections of Metolachlor were 1.8 times over the 99% DGV followed by Paraquat 6.25%, Picloram 2.33%, Atrazine 0.88%, MCPA 0.44% and 2,4-D 0.019% of the 99% DGV. It should also be pointed out that Atrazine and 2,4-D have not had their ecological guidelines reviewed for a quarter of a century.
If you want to make a tax deductible donation for our pesticide research, you can do so here.
For more information contact [email protected]