Reducing evaporation in dams

Benalla farmers David and Anna Stewart are convinced that using a silicon-based anti-evaporative agent on their dam prevented them from running out of water in 2010. The development of a whole farm plan  and the reticulation of water to where it is needed has provided them with much improved water security.

Applying the anti-evaporative to the dam

The couple who run a small prime lamb enterprise on 100ha, applied the product in January after they realised the water in the main dam was 'disappearing at an alarming rate'.

At first David doubted that the product, which is advertised as being able to reduce evaporation by up to 50 per cent, would work. 'When I saw how little product was required (200ml per 1000m² of surface area), I was sceptical,' he says.

They continued to apply it every 10 days until the end of autumn.

According to David, the product was very easy to apply. 'You simply pour it into the dam and it quickly spreads to form a very thin, oil-like film across the water's surface that is hardly visible,' he says.

It was also extremely cost effective — David estimates he spent no more than $50 on the product over the 16-week period.

Measuring success

Happily, David's scepticism was unfounded. Although he did not take any proper measurements other than to mark the water level from week to week, it soon became clear that the product was working. 'The rate of evaporation had reduced markedly to the point that we made it through the dry summer and autumn comfortably with water remaining in the dam.'

David saw no indication that the silicon-based product was harmful or distasteful to stock or wildlife. 'The manufacturers claim it presents no risk to grazing animals or wildlife, and certainly I didn't observe any adverse effects,' he says.

With drier conditions predicted to continue, the product is giving David and Anna confidence in managing their water supplies.

Key points

  1. The use of an anti-evaporative agent on the dam surface substantially reduced the amount of evaporative loss in the dam over the summer months.
  2. The installation of a reticulation system has increased flexibility and improved grazing management.

More information

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Page last updated: 17 Jun 2020