Pesticides in irrigation water a big concern for human health and freshwater ecosystems

December 06, 2006

Friends of the Earth today raised concerns about the off-site impacts of pesticide use in irrigation areas, particularly in the Murray Goulburn Valley. The concerns were brought to light through a recent freedom of information to Goulburn Murray Water (G-MW).

The F.o.I has revealed high pesticide readings in G-MW channels for the herbicides Amitrole, 2,4-D Amine and Glyphosate as well as lower levels of agricultural pesticides leaching from orchards and other farming enterprises. The insecticides Endosulfan, Chlorpyrifos and Parathion Methyl have been detected as well as the herbicide Atrazine in G-MW drainage infrastructure. The readings will also have some ramifications for other irrigated regions for Victoria.

Following a massive fish kill in the Goulburn region in 2004, the EPA conducted an audit in 2005.  In that audit of the ‘Goulburn River - Lake Eildon to the Murray River 2005’, G-MW was directed to recalculate the residual herbicide concentration and biodegradation processes to include 2,4-D amine as well as Amitrole and Glyphosate. These herbicides, as well as the Acrolein are used by G-MW to kill aquatic weeds within G-MW channels and drainage infrastructure. (Southern Rural Water also use Acrolein in the Macalister Irrigation District in Gippsland).

According to the EPA audit p153 ‘In general, their channels are not a drinking water supply... where bulk entitlements are sourced from  channels, the urban water authority is given prior notice of the treatment, including the herbicide involved, and they forgo diversions for a number of days’.

Furthermore the audit said on p181 ‘If ANZECC (2000) criteria are exceeded or likely to be exceeded, a contingency plan should be implemented. (If not already in place the contingency plan should be developed as a matter of urgency)’.

On the 10th of April 2006, Amitrole readings from the Community Surface Drain, Rodney Drainage System reached 1.06mg/L. This is approximately 1000 times over the ANZECC guideline limit for drinking water and 500 times over residual limits for irrigation water.  The ANZECC guidelines for residual limits for irrigation water were also breached by GMW on 7 seperate occasions at Rodney Main Drain, Wyuna.

Measurements of 2,4-D amine applied by GMW were also excessively high at CH 1/5 in May 9 2006 with levels of 2.96mg/L recorded. This is almost 30,000 times over the ANZECC guideline for drinking water and 30 times the recreational limit. Readings were exceedingly high for 4 days.

Glyphosate levels on 12/4/06 in Drain 8, Ardmona were 10.5mg/L, 1000 times over the ANZECC guideline for drinking water and 50 times over the recreational limit. Glyphosate readings were also quite high in the Broken Creek on the 8th of May.

Amitrole is a carcinogen, an endocrine disruptor and potential ground water contaminant.  It has a half-life in water of about one month. 2,4-D is a possible carcinogen, potential groundwater contaminant and has a half-life in water of 1-2 weeks (but up to 4 months in anaerobic conditions).

Friends of the Earth researcher Anthony Amis said; “We have big concerns about how these pesticides breakdown in the water.  What happens to the polluted water once the pesticides are applied? From our understanding traces of these chemicals will still be found in the water for months after application.  How far downstream do these pesticides travel? Is anyone drinking this water. If water from channels is supplying local communities how safe is their drinking water? We understand that up to 25 communities alone rely on channel water for drinking in mid-northern Victoria.”

Furthermore positive readings for the organochlorine insecticide Endosulfan have been recorded in G-MW drains during 2004/6 at the following sites; Nagambie, Torganah, Ardmona, Mooroopna, Kyabram, Corop, West Boort, Appin and Kangaroo Lake.

The organophosphorus insecticide Chlorpyrifos was also detected during 2004/6 with most occurrences occurring near Shepparton and Ardmona. The organophosphate insecticide Parathion Methyl was detected in 2005/6 at Tornganah, Shepparton and Ardmona.  The triazine herbicide Atrazine was detected at many sites with the most concern being consistent readings at West Boort.

Although the readings for these pesticides were within ANZECC guidelines for raw irrigation, stock and domestic supply and town supply, the levels for Endosulfan and Chlorpyrifos in some instances breached the ANZECC guidelines for the purpose of aquaculture and fish farming. 

FoE said; "This is of concern regarding the plight of native fish and ecosystems that GMW water infrastructure drains into. FoE have concerns that if these levels are regarded as being dangerous for fish farming then they may also be dangerous to wild populations of native fish and other species. There may also be a risk for human health if any of this tainted water ends up being consumed for drinking water further downstream. We are also unclear about what the synergistic effect is of combining these pesticides" said Mr Amis.

Of most concern are the Chlorpyrifos readings for Ardmona, where in a 4 month period between August to November 2005 the ANZECC guidelines were consistently breached between 10 and 60 times over the guideline limit for aquaculture.

Chlorpyrifos readings for Shepparton showed consistent breaching of ANZECC guidelines for several months at between 15-30 times the ANZECC aquaculture guidelines. In terms of Endosulfan, the highest breach to the ANZECC guidelines was at Ardmona in September 2004. Endosulfan was also regularly detected over a 7 month period at Kyabram from September 2005 to March 2006. Endosulfan was also regularly recorded at Mooroopna.

According to the Pesticides Action Network; Chlorpyrifos is a cholinesterase inhibitor and suspected endocrine disruptor, It has a half life in water of almost 2 months. Endosulfan is a suspected endocrine disruptor with a half life in water of just over 3 months. Parathion Methyl has a half life in water of over one month. The herbicide Atrazine is a carcinogen, a ground water contaminant and suspected endocrine disruptor.  It has a half life in water of one month.

"It is a concern to FoE that residues of these particular substances may be ending up further downstream from where they are applied, and if the residues remain active for over a month who knows what impact these substances are really having on all facets of the freshwater ecosystem.  Traces of the herbicide hexazinone were found 50 km downstream of a pine plantation in Geelong’s Water supply between December 2004 and June 2006.  A similar pollution event may be occurring in the Goulburn/Murray system, especially where the agricultural drains outfall into ‘natural’ waterways" said Mr Amis.

”We are particularly concerned about the pesticide impacts on threatened native fish including; Trout Cod, Macquarie Perch, Murray Cod, Silver Perch, Freshwater Catfish, Murray Hardyhead and Murray Rainbow Fish” said Mr Amis.

Similar concerns apply to the Macalister Irrigation District, but to date there has been no comprehensive water quality monitoring and testing of drainage waters and agricultural wastes that discharge to the Thomson and Latrobe river systems and feed into the internationally accredited wetlands; The Gippsland Lakes. A Freedom of Information Request to Southern Rural Water earlier in the year revealed that Acrolein and Roundup are used in that drainage system.

For further information contact Anthony Amis (03) 9419 8700.
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