8 min read | June 9, 2023

Understanding the Mitigation Hierarchy

From start to end, the mitigation hierarchy underpins every aspect of the new BNG regime. Understanding the hierarchy is key to successfully complying with the new requirements.
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Biodiversity Net Gain (BNG) in England is founded on the mitigation hierarchy, which is detailed in the National Planning Policy Framework. Natural England has said that its objective with the entire BNG policy was to reinforce and complement the mitigation hierarchy. From start to end, the mitigation hierarchy underpins every aspect of the new BNG regime. Understanding the hierarchy is key to successfully complying with the new requirements. 

What is the mitigation hierarchy?

In a nutshell, the hierarchy presents a sequential approach to addressing potential harm to biodiversity when determining planning applications. It emphasises the prioritisation of avoidance first, followed by mitigation measures, and lastly, compensation. By following the mitigation hierarchy, developers can adopt a 'nature first' approach, working alongside existing natural features on-site, and resorting to offsetting only when absolutely necessary.

The mitigation hierarchy plays a vital role in supporting global biodiversity goals, such as the United Nations Convention on Biological Diversity (CBD) and the Sustainable Development Goals (SDGs). By guiding responsible development practices that minimise harm to biodiversity, the mitigation hierarchy supports the achievement of several key targets

The mitigation hierarchy has been applied in various countries to guide sustainable development practices and reduce the impact of human activities on biodiversity. Here are some examples: 

  • Australia: the mitigation hierarchy is applied in the context of the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The Australian government promotes the use of the mitigation hierarchy to minimise the impact of development on Matters of National Environmental Significance (MNES) and the environment in general. 
  • United States: The United States has adopted the mitigation hierarchy within the context of the Clean Water Act and the Endangered Species Act. The U.S. Army Corps of Engineers and the U.S. Environmental Protection Agency (EPA) use the mitigation hierarchy for wetland and stream projects, while the U.S. Fish and Wildlife Service applies it in consultations for threatened and endangered species. 
  • European Union: The European Union (EU) incorporates the mitigation hierarchy into the Environmental Impact Assessment (EIA) Directive and the Habitats Directive. The EU member states are required to apply the mitigation hierarchy when evaluating the environmental impact of projects and the effects on protected species and habitats. 
  • South Africa: South Africa has adopted the mitigation hierarchy within its environmental impact assessment process. The country’s National Environmental Management Act (NEMA) requires the application of the mitigation hierarchy for any development that could have a significant impact on the environment, including biodiversity. 

How does the mitigation hierarchy work?

There are four steps: Avoidance, Minimisation, Restoration and Offsetting. Let’s take these in turn: 

  • Avoidance: Prevent or reduce biodiversity impacts through site selection and layout. This is the initial step in the mitigation hierarchy and is often the most cost-effective and efficient way of reducing potential impacts. It requires developers to consider biodiversity in the early stages of a project. Effective avoidance mechanisms can be achieved by engaging with local stakeholders (including the local planning authority) to identify steps that can be taken to prevent doing damage to rich local habitats. 
  • Minimisation: Implement measures to decrease the duration, intensity, and/or extent of impacts to biodiversity. By reducing impact when outright avoidance is not feasible, it is possible to minimise potential negative impacts by modifying the project design and strategy to the fullest extent possible. This can be achieved by following sensitive landscape design practices in line with industry best practices. 
  • Compensation: Compensate for any residual, unavoidable impacts after implementing avoidance and minimisation measures, preferably as close to the point of impact as possible. This should only be considered after the other options have been exhausted as it is the most expensive, complex, and high-risk approach. 
  • Offsetting: Where it is not possible to secure compensation on site, offsite solutions should be sought, with a premium on finding solutions as close to the impact as possible. We have covered this in a previous blog but, in short, it involves the use of biodiversity net gain offsetting mechanisms, such as the creation or enhancement of off-site habitats, purchasing biodiversity units on the market, or acquiring statutory credits. 

Challenges and Opportunities in Implementing the Mitigation Hierarchy 

Despite its widespread adoption and recognition as a best practice, the implementation of the mitigation hierarchy can be challenging. Some of the difficulties in different areas include the lack of clarity in regulations (regulations often do not provide clear guidance on how to apply the mitigation hierarchy, leading to inconsistencies in its implementation); insufficient data and monitoring (a lack of comprehensive data on biodiversity and ecosystem services can hinder the effective application of the mitigation hierarchy); and limited capacity and resources (especially where specific types of development lack the necessary technical capacity and resources to apply the mitigation hierarchy effectively). 

However, these challenges also present opportunities for improvement. And the new Biodiversity Net Gain system has been designed to build on the best practices.

Following the Mitigation Hierarchy in Biodiversity Net Gain

As noted above, the Migitation Hierarchy is an essential component of the BNG system.

When preparing a Biodiversity Gain Plan, developers must demonstrate how they have complied with the mitigation hierarchy by adapting their project designs to avoid damage to biodiversity and maximise gains. The plan must include evidence of the steps taken to avoid and/or minimise adverse biodiversity impacts, and financial cost should not be an excuse for failing to avoid or minimise negative effects. 

Remember that the mitigation hierarchy applies to all aspects of ecology, and that - beyond the requirements set out in the BNG regime - the potential for avoidance, minimisation, mitigation, and offsetting impacts on species will also need to be considered outside of a BNG approach. 

How Joe’s Blooms helps

Complying with the mitigation hierarchy is not a simple ‘step’ to take in the planning process - it is an approach, an attitude towards development that needs to be demonstrated at every step in the planning applicant’s journey. Our technology is able to help integrate this into every step of the planning application process, and help steer a development towards new approaches that drastically reduce the negative impact on the environment. 

Wherever possible we will recommend avoiding and minimising the impact of developments on priority habitats. We then bring this data out in the way required in the new BNG regulations. Over time we will develop further tools that will help the developer demonstrate BNG at every step of the application and demonstrate this to local stakeholders and the LPA.


The mitigation hierarchy is a fundamental principle in achieving Biodiversity Net Gain in England. By prioritising avoidance, minimising losses, and resorting to compensation only when necessary, developers can help protect and enhance biodiversity. Adhering to the mitigation hierarchy throughout the planning process not only ensures responsible development but also contributes to the long-term sustainability of our natural environment.

Oliver Lewis

Oliver Lewis

Founder of Joe’s Blooms
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Oliver Lewis is the founder of Joe’s Blooms, providing end-to-end digital solutions to help you create best-in-class Biodiversity Gain Plans. Expert in this field, he shares his knowledge on the Environment Bill.

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