All farm dam owners are legally responsible for the safety of their dams and any death, injury or damage they cause if they fail.
Even if someone else is responsible for your dam failure, you are still very likely to be liable for expenses – which are often more than the original cost of building the dam.
You should regularly inspect and maintain your dams to keep them in good order, and check you have the right licenses to build or operate them. If you live in a rural residential area, you may also need to register your dam with your local water corporation.
Dam licenses ensure dam owners take proper precautions to protect life and property. Under the Water Act 1989, you need a license to build, operate, alter or decommission dams on waterways or dams that are considered hazardous in size.
Operating licenses for large dams
You must obtain an operating license if you:
- own a dam on a waterway
- own a large dam off a waterway that is potentially hazardous
Potentially hazardous dams include those that have a:
- wall height of 5 metres or more and a capacity of 50 mega litres or more
- wall height of 10 metres or more and a capacity of 20 mega litres or more
- wall height of 15 metres or more regardless of capacity
Such dams require surveillance plans, and must usually be regularly inspected by a qualified engineer. You must also have an emergency management plan in case your dam fails or has any other structural fault.
You must pay an annual fee for your operating license.
Construction licenses for building new dams
If you are thinking about building a new dam you should contact GWMWater and your local Council for advice, as you may need a construction licence and/or a Council planning permit.
For more information regarding constructing a new dam head to GWMWater.
Generally you do not need our permission to build a dam that is not on a waterway/floodplain and is:
- used only for domestic and stock purposes
- filled exclusively from roof run off
However, you should seek advice to build any dam for irrigation or commercial purposes and you must obtain a construction license for building any:
- dam on a waterway (from the Catchment Management Authority)
- large dam off a waterway that are potentially hazardous
Construction licenses usually need a suitably qualified engineer to design the dam and supervise its construction. They also usually require flow bypass arrangements that allow water to pass through or around the dam outside of any authorised filling period.
We generally do not support building new on-waterway dams because they harm the waterway environment and downstream flows. We will only consider them for minor tributaries where there is no alternative site, and where an environmental impact study determines there will not be adverse impacts.
Triggers for Council planning permits:
Council planning permit may be required where;
- Earthworks which change the rate of flow or the discharge point of water across a property boundary.
Works on Waterways Permits (from the relevant Catchment Management Authority)
Works that occur within a waterway, wetland or designated flood plain will require a "Works on Waterways Permit".