Farmers are advised to ask some important questions before constructing a new dam or adding water infrastructure or equipment to their property.
Before engaging an earthmoving contractor for a new dam, investigate answers to important questions like: How much water do I need, will the dam hold water, will it fill most years, how big should it be, is there a good site for a spillway, do I need a permit or license, what will it cost?
Longer, hotter summers and decreased cool season rainfall has meant many smaller dams built in previous years are drying up.
Lack of run-off, increased water consumption and evaporation contribute to this issue.
Many new dams built across Victoria are also failing within the first few years due to inappropriate materials or poor construction techniques.
As a result, farmers need a bigger catchment area to improve the chances of filling dams regularly.
At least 10 hectares of catchment for every megalitre of water stored in a dam is recommended.
Run-off from nearby roads and tracks is an effective way of getting water, especially in a dry year.
A livestock dam should be as deep as your site will allow and have a minimal surface area to reduce evaporation.
Consideration should be given to planning a key large dam to use for reticulating water to troughs across the property, via gravity or pumps.
Allow a minimum spillway width of 5 metres. The spillway should end with a level spreader to ensure water leaves the dam in a thin wide sheet.
A gently sloping, well grassed area is essential for a safe and stable spillway. The spillway should have little or no slope with a flat cross-section.
The addition of a trickle flow pipe set below the spillway level will minimise ongoing maintenance.
Purchasing appropriately sized pumps, tanks, troughs and pipes is essential for providing the flow of water needed on a hot day.
Ensure the construction and design of troughs are not vulnerable to livestock damage and are easy to maintain.
A single inferior fitting in a farm pipeline could result in total system failure and loss of valuable water.
Reputable products will be marked with the manufacturer’s details, date of manufacture, a relevant description and appropriate industry markings.
For example, the markings on good quality rural polyethylene pipe will include PE80 or PE100, indicating the long-term strength of the materials.
When purchasing pipeline equipment and fittings, deal with a reputable supplier with a good track record, spare parts and after-sales service.
Selecting an experienced and reliable contractor, plus a few basic soil tests, will minimise the risk of failure.
Ensure your contractor has the appropriate skills, a good reputation and up-to-date equipment. Ask the contractor for examples of their work and a guarantee.
A permit or licence may be required to build, extend or repair a farm dam in Victoria.
Contact your local rural water authority before starting works.
For further information, visit: https://agriculture.vic.gov.au/farm-management/water/managing-dams/maintaining-your-farm-dam
– Clem Sturmfels
Land management extension officer
Agriculture Victoria
