1984 February: Boort area (Vic) Fish Kill. Pesticide: Fenvalerate

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State Rivers and Water Supply Commission February 5 1984

I inspected the No.2 and the 2/2 with *** and *** on Monday 9th January, 1984.

Dead Fish were found in Allotment 9 and on the No.2 channel down to the Lake Neran outfall. At every bridge over the channel dead fish could be observed floating at the margin of the channel.

While inspecting the channels, we spoke to two of the tomato growers. Both *** and *** were extremely candid about what pesticides had been used on their tomatoes and I subsequently contacted the aerial spray contractor, *** of Elmore. He gave me the following information I had been given by the tomato growers.

Sumicidin (Fenvalerate), Kocide (Copper Oxychloride), Dithane, Endosulfan.

Detection of Dead Fish

The supervision water bailiffs on the No. 2 Channel first noticed distressed fish at noon on Wednesday 4th January, 1984. By the following day, Thursday, many dead fish were floating in the water and no distressed fish were observed.

On Friday 6th January, 1984, a number of dead fish were removed by Commission workers after a local landholder had expressed concern about the dead fish and the possible detrimental affect on water for domestic supply.

Initially I suspected endosulfan as the cause of the fish kill but according to the growers and the spraying contractor, endosulfan was only used adjacent to the 2/2 channel. It is worth noting that the 2/2 channel was treated with acrolein some two weeks prior to the aerial spraying so very few live fish would have been present.

However, it has been reported to me by one of the markers to the spraying contractors noticed one small fish in the 2/2 was distressed after Allotment 53 was sprayed with endosupfan, fenvalerate and kocide on the 4th January 1984.

The most toxic material used near the No.2 channel was fenvalerate. Therefore at this stage, without any residue data to support any conclusions it appears that the fish in the No.2 channel were killed by inadvertent drift of fenvalerate from the aerial spraying of tomatoes in Allotments 45, 10, 9 and 8 C.

It is inevitable that some chemical will drift from any type of spraying operations but the disturbing feature of this fish kill is that fish appeared to have died some 6 kilometres downstream from the point of spraying…

Conclusion

1. The fish kill in the No.2 channel was caused by accidental drift from aerial spraying of tomatoes adjacent to the channel.

2. Fenvalerate appears to have been the pesticide responsible.

3. It was an isolated incident in an area where tomatoes have been grown for at least 10 years and where aerial spraying has been the predominant method of applying pesticides in the past 6 years.

Recommendation

Aerial spraying of crops adjacent to channels be closely observed to identify if this incident was as isolated as we believe.