1953 January: Irrigation Weed Poisoning. Pesticide

Fisheries Office
Swan Hill,

The Superintendent,
Fisheries Branch,

Weed poisoning by Victorian State Rivers and Water Supply Commission.

I have to report that on the 17th January I attended a weed killing experiment carried out by Victorian State Rivers and Water Supply Commission at Lake Boga.

Two irrigation channels were treated, each with a different type of poison, effect of poison on fish life is as follows.

Channel No.1

About 11.30am on the 17th of January, 40 gallons of E.F.805M, was released in a irrigation channel near Lake Boga. E.F.805M. is a Vacuum Oil Co. product, (weed killer).

A mixture of E.F.805M and water was pumped into the Channel through a fine spray, the process took about 1 hour. As the weed killer was taken downstream by the run of water in the channel, water turned a milky colour, about 20 minutes after operations began small carp were observed leaping from water, ten minutes later large numbers of carp from 1/2″ to 6″ in length began to float to the surface, by this time the water was very milky from place of pumping to about 60 yards downstream.

It was noticed that poison had no effect on fish where water was not milky. When operations ceased (1 Hour) the water was milky for about 130 yards downstream from pump and dead Carp were floating to surface in large numbers throughout this area. I counted 158 dead fish in 40 yards, this would be no accurate count as many fish could not float to the surface owing to the thick weeds in the channel. About 2 hours later larger carp were observed floating on the water and number of dead Yabbies were observed on the bank.
Channel No.2

About 2.30 p.m on the 17th January, 40 gallons of E.F.860M, was released in an irrigation channel near Lake Boga. About 10-15 minutes after operations began water began to turn milky to about 35 yards downstream from point where poison was released.

Small carp and Redfin began leaping from water. Ten minutes later dead fish began to float to the surface, it was noticed that many small Redfin had leaped onto the bank in an attempt to escape poison, as weed killer spreads slowly I am of the opinion that many of the larger fish may have swan downstream ahead of it.

About 45 minutes after operations began all marine life in an area 50 yards downstream from pump appeared to be extinct, large numbers of small Carp, Redfin were floating on the surface, Yabbies had ceased to move among the weeds and no shrimps were apparent. When pumping operations ceased water was discoloured to about 150 yards downstream and poison was still moving further down the channel, about 1 hour later dead Carp and Redfin were observed on the surface doe about 350 yards downstream.

I removed 6 Carp and 6 Redfin which were floating on the surface but still kicking, the fish were placed in a tin of freshwater, the Redfin died but all Carp revived and were kept for 48 hours when they were destroyed by me.