The mitigation hierarchy is a tool that is used to limit the amount of damage an action, such as a development, will have on the environment. There are three steps, and each step must be followed in order and to the greatest extent possible before moving on to the next. These steps are:
Preliminary analysis - determine the maximum possible impact
When planning a proposed action, first think about the impact your project might have on protected matters (including nationally significant plants, animals, ecological communities and places). For example, you might want to build new infrastructure such as sheds, roads, or a new dam where there are some plants that are habitat for an endangered species.
You should first think about how big your development needs to be, and where you will put it. This is known as the development footprint. Next consider the maximum size of the impact, known as the impact area. This may be bigger or smaller than the development footprint because impacts can be both direct (for example, clearing trees within your development footprint) and indirect (for example, increased lighting in the area at night or accidentally introducing or spreading weeds). Then consider how permanent the impacts are likely to be, for example will the disturbed ground be covered by a building or can some areas around the building be rehabilitated after development has been completed?
Once you have a good idea of what your impacts might be, you can decide whether it is likely that your project will impact a protected matter. You will need to consider what protected matters might be present on the site. This might include consideration of what animals use the area as habitat and how important that habitat is. For example, is it isolated or connected, is in good or poor condition, how many animals does it support?
We have a protected matters search tool available to help you identify potential protected matters that may be impacted by your project.
If your project is likely to have a significant impact on a protected matter (see Significant Impact Guidelines) you will need to refer it to the minister under the EPBC Act.
Step 1: avoid impacts
One way to reduce your impact is to avoid developing areas where there are protected matters. For example, you may be able to use land which is already cleared or construct your new infrastructure closer together to reduce the amount of vegetation you need to clear or to avoid a heritage place.
Even if it is not possible to completely avoid a protected matter there may be ways to reduce the impact. A relevant expert such as an ecologist should be employed to undertake a survey of the proposed project area. They may find that some areas are more important than others.
Example: Avoid impacts
- Trees with hollows that birds are nesting in, or patches of vegetation which have fewer weeds. You might be able to avoid these important areas with small changes to your project design. This could reduce your total impact on protected matters, even if the amount you will clear will be the same.
Step 2: mitigate impacts
Once you have avoided impacts as far as possible through changes to the design of your project, you will need to consider what other things you can do to reduce the impacts that cannot be avoided.
Mitigation is what you can do to reduce how likely or serious the unavoidable impact will be. You need to consider both what direct and indirect impacts your action might have and options to minimise these. Indirect impacts are often able to be mitigated. Depending on the impact there may be relevant guidelines or standards which can assist you in identifying suitable mitigation methods.
Example: mitigate impacts
- During clearing of trees, you might need to use heavy machinery which will disturb the ground and produce a lot of dust or cause soil erosion. If dust was blown by the wind on to vegetation you are not removing, it could bury small, protected plants or hurt protected animals. Mitigation by spraying water during machinery use would reduce the likelihood of dust impacting protected matters.
- The risk of soil erosion can be mitigated by not using machinery during heavy rainfall.
- The machinery you use during construction may also have been used on other sites where there was a plant disease such as dieback. You can reduce the risk of spreading disease by cleaning machinery before it enters the project site.
Mitigating ongoing impacts
You should also think about how you will mitigate the ongoing impacts of your project. Ongoing impacts come from the operation of your new project once clearing or construction is completed.
Example: mitigating ongoing impacts
- You may have built a new access road on your property. You have avoided clearing some important bushland and have made sure that no dust, weeds or disease have spread during clearing and construction. However, you now have traffic on the road where it is likely that protected animals will cross at certain times of the day. They could be killed or injured if hit by vehicles. You could mitigate this impact by requiring lower speed limits to allow the driver more time to stop if they see an animal. You might also consider scheduling truck movements during the day, rather than at dawn or dusk when animals are more likely to be active. Installing wildlife crossing structures could also help.
Step 3: offset
Offsetting is the final step in the mitigation hierarchy and should only be applied once impacts have been avoided and mitigated. Even after you have made every attempt to avoid or mitigate an impact, your proposed action may still significantly affect a protected matter. This is called having a residual significant impact. If the action you referred to the minister is found to be acceptable and is approved, a condition of that approval may require you to have an offset to make up for these impacts.
Requirements for offsets are set out in the Environmental Offsets Policy.
The offset will need to fully make up for the impact. You might do this by:
- purchasing, protecting, and improving another area of land which supports the same protected matter you are impacting; or
- funding research that will provide more information about the protected matter and it to be protected better in the future (see: Direct and indirect offsets).
Delivering an offset that evenly balances out your impact is called having no net loss. This means that, although you have affected a protected matter in one area, you have improved it in another. No net loss is required to be in accordance with the Environmental Offsets Policy and be considered as an acceptable offset under the EPBC Act.
Sometimes, you will be able to do better than no net loss and improve a protected matter to a state better than it was before your action had an impact. This is called net gain. Net gain is not required under the EPBC Act but may be seen as an aspirational target.