Tasmanian government axes pesticide monitoring in waterways

Anthony Amis

It was confirmed in October 2014 that the new Hodgman Liberal government in Tasmania had axed the unique decade-long pesticide testing program conducted by the Department of Primary Industries, Parks, Water and Environment (DPIPWE). This means that there is no routine monitoring of pesticides in waterways except for irregular monitoring by drinking water authorities.

In 2005, the Tasmanian government embarked on an ambitious project to monitor pesticide residues in waterways. The pollution was largely caused by agricultural and forestry practices. Eighty-three sampling sites were used during the nine years that the project was active. This was an important project, as no other state sampled the same number of sites for such a period of time.

Approximately 36 pesticides were (sometimes) tested for, depending on the location of the sampling site. Sites were generally sampled once every two to three months. The most frequently detected pesticide was MCPA (2-methyl-4-chlorophenoxyacetic acid), which was detected 72 times at a number of locations, followed by 2,4-D (35 times), prometryn (25 times), simazine (17), metalaxyl (12), cyanazine (9), metsulfuron methyl (9), triclopyr (9) and a number of others.

MCPA is a selective herbicide used to control broadleaved weeds in cereals, linseeds, pasture and turf. 2,4-D is a herbicide used in Tasmania to control broadleaf weeds in cereals, pastures and non-agricultural areas. Prometryn is a herbicide used in vegetable crops. Simazine is a herbicide used in a variety of guises. Metalaxyl is a fungicide used in vegetable crops. It is clear that the majority of the detections were a result of farming practices.

None of the samples breached Australian Drinking Water Guidelines levels. A detection of the insecticide diazinon at 0.1micrograms per litre (ug/L) in July 2008 at the Jordon River, Mauriceton, breached Australian ecological guidelines. Several detections of simazine also breached ecological guidelines. There are no ecological guidelines however for MCPA.

Of particular concern were a number of high detections of the herbicides MCPA, 2,4-D and simazine. The highest level recorded for simazine was 2.2 ug/L at the South Esk River at Perth in October 2005. The South Esk River supplies a large portion of the city of Launceston’s drinking water. Similarly, a simazine level of 1.27 ug/L was detected in the Macquarie River in July 2007.

Simazine is a triazine herbicide, closely related to atrazine. During the 1990s, Forestry Tasmania placed restrictions on the use of triazines after widespread contamination of waterways, mostly in the northern part of the state. Private forestry owners such as Gunns continued using simazine, as did many farmers.

The highest level of 2,4-D was 11.2 ug/L, recorded at the Clyde River, Bothwell, in July 2014. Levels of 2,4-D above 1 ug/L were recorded at the Rubicon River (July 2008), Tuckers Creek (July 2012), the Duck River (July 2013) and the Welcome River (July 2014).

MCPA was frequently detected in the Duck River near Smithton for nine years, yet the highest amount of MCPA recorded was in the Rubicon River in January 2014. The level detected was 19.1 ug/L, which is probably the highest amount of MCPA recorded in an Australian waterway.

It seems odd timing that the new Tasmanian government decided to stop the pesticide monitoring program during the same year that the highest amounts of 2,4-D and MCPA were recorded by the program. Maybe it isn't so odd when one considers that 63% of all positive detections occurred between 2012−14. Indeed, detections in 2014 had already been on track to be easily the most of any year, with 46 positive detections up to July 2014 − 20% of all detections since 2005!

As the project developed, it appeared to more accurately target catchments where problems were occurring. The most detections of any catchment occurred in the Panatana Rivulet located again near Port Sorell and these 36 detections all occurred after 2011. At the nearby Rubicon River 27 positive detections had been recorded since 2011 – between them almost 28% of all positive samples, all in less than three years. At Tuckers Creek in the state’s north east 27 positive samples were recorded since sampling began there in 2011.

It would be interesting to learn what farming bodies lobbied the Hodgman government to axe the program, a decision that is short-sighted and has the interests of agricultural industry at heart. It is also interesting that despite over 200 positive detections over nine years, no prosecutions for water pollution eventuated. It would appear that the old-fashioned attitude of waterways being little more than agricultural drains again holds sway in Tasmania.

Anthony Amis is FoE Australia's spokesperson for pesticides and drinking water.

From Chain Reaction #123, April 2015, national magazine of Friends of the Earth, Australia, www.foe.org.au/chain-reaction/editions/123