When you look at the scattering of farm dams across most rural properties in Australia, you begin to realise how much water in total is stored in these structures and how vital they are to farming systems in both Australia and to a lesser extent in New Zealand.
You also see a significant number of failed dams if you look closely enough to understand that building a farm dam is not a case of digging a hole and waiting for it to fill with water. Many farm dams fail because they were not planned or built properly.
Most farm dams are compacted earth structures built at depressions, gullies or hillsides. Farm dams should be planned and built with the same care you would apply to building a new house.
There are several things to think about when planning and building a farm dam:
- which government regulations (if any) apply
- who should build the dam
- how big to make it
- where to put it
- how to prepare the site
- how to build the dam
- how to look after it.
Government regulations
Dams are considered significant structures in all states of Australia, throughout New Zealand and in fact in most countries throughout the world. This is because of the scale of most dam structures and the risks that there will be off-site consequences if these structures fail.
In NSW for instance, some Councils require a Development Application for every dam built in their area. You are advised to check with your local Council to see if you must comply with any development control plans.
You may also need a licence to build your dam. The Department of Infrastructure, Planning and Natural Resources (DIPNR) in NSW for example, issues the licences and can advise you on whether you wil need one.
In NSW, some dams may need to be registered with a Dam Safety Committee, which considers the consequences of dam failure. Although registration is required for very few farm dams, you should check the need for registration by contacting your local water authority or Council in the first instance.
The removal of trees within 20 metres of a watercourse may be prohibited. Sometimes, special permits are issued to allow tree removal. If the location of your proposed dam is affected by trees, check with your Local Council and DIPNR before you start building.
Finally, a local authority usually considers the suitability of works at or near a watercourse, lake or estuary. A permit is required for any excavations, placement of fill or construction in or near these areas. You should approach your local water/Catchment Authority to find out if your dam is affected.
