1962 December: Malmsbury Reservoir Spillway. Pesticides: Amitrole, Diquat, Paraquat

State Rivers and Water Supply Commission

6th of December 1962

Weed control – Malmsbury Reservoir.

My memorandum to *** of 16th November gave recommendations for the control of weeds on the embankment, spillway and paths at Malmsbury Reservoir. After further consideration, I have some doubts about the wisdom of using Weedazol Total or any other Weedicide in the spillway.

I had assumed the first flow over the spillway after treatment would be in midwinter when there was no use of the Malmsbury pool for watering gardens. In actual fact however, a heavy rain soon after spraying could result in water moving over the spillway, even though there was no discharge through the gates, at a time when there was a considerable demand for water from the pool. In other words there is a possibility that the use of Weedazol Total in the spillway could cause damage to private gardens in Malmsbury. Its use should therefore be limited to the embankment.

As regards spray treatments using Diquat and Paraquat, you have already been advised of the withdrawal from use of these two chemicals in all areas. This will affect the recommendation concerning treatment of the paths and the follow-up spraying of the embankment.

Your requirements then as regards weedicides for Malmsbury are thus 60 lbs of Weedazol Total and 1/2 gallon of Plus 50 to be used on the embankment, preferably during December.