As dams remain low or dry, think about desilting

AS WE are heading for spring after a drier-than-normal autumn and winter, it may be time to take a look at desilting your dams.

Usually, most dams would be full by now, but as this is not the case, it could be just the right opportunity to turn a bad into a good by removing built-up sediment from dams.

However, Agriculture Victoria land management extension officer Clem Sturmfels is encouraging famers to think carefully before proceeding with sediment removal works.

“Cleaning out dams at this time of the year can be difficult, dangerous and expensive,” Mr Sturmfels said.

“Handling wet dam sediment requires specialised equipment and using a excavator to remove this sediment is slow and tedious work and dozers usually don’t have the reach to do this work efficiently.

“Dams with fresh deposits of soil, manure, and other organic matter are more likely to grow algae and bacteria.

“Allowing these deposits to dry out over summer allows the material to be removed using a scraper or bulldozer which is way more efficient.”

The department advise that it’s important to closely monitor the dams while waiting for them to dry out to avoid any animal health issues.

Dams with older sediment are less likely to have water quality concerns and a metre or so of sediment will have little impact on dam capacity.

Assessing the depth of sediment in a dam can be difficult and farmers can make an estimate by measuring the depth of the dam and comparing that to the dam’s dimensions.

A depth sounder or Damdeep measuring device can be used, and there are online videos of how to make and use a Damdeep that are very informative.

Farmers are encouraged to consider the following when undertaking dam cleaning activities:

The sides of dams can be slippery and pose a risk to humans, stock and plant operators

Dam sediment should be placed in a location where it cannot re-enter the dam or other waterways

Steepening the sides of the dam can result in erosion and further sedimentation, and

Avoid any works which impact the structural integrity of the dam or associated outlet devices.

Agriculture Victoria recommend contacting the local rural water authority in your area before starting sediment removal works, as a permit may be required.