Mitigation Hierarchy

The idea of biodiversity offsets is controversial to some in the conservation community; the fear is that that the use of offsets could encourage regulators to allow projects with severe impacts on biodiversity to go ahead as long as they offered offsets to compensate, and allow companies to leave significant impacts in areas affected by projects as long as they undertook conservation work elsewhere.

BBOP addresses this concern by advocating for strict adherence to the "mitigation hierarchy", which views the role of biodiversity offsets as a "last resort", after all reasonable measures have been taken first to avoid and minimize the impact of a development project and then to restore biodiversity on-site.  Conformance to the mitigation hierarchy is the first of the ten best practice Principles established by BBOP, and a fundamental part of the Standard on Biodiversity Offsets.


This simple graphic depicts the steps of the mitigation hierarchy, (avoid, mitigate, restore or rehabilitate and offset).  This approach enables an infrastructure development project to work towards “no net loss” of biodiversity, and ideally, a net gain.  The application of the mitigation hierarchy, and how far each step should be pursued before turning to the next, is one of the key issues for consideration in biodiversity offset design.

The mitigation hierarchy is defined as:

  • Avoidance: measures taken to avoid creating impacts from the outset, such as careful spatial or temporal placement of elements of infrastructure, in order to completely avoid impacts on certain components of biodiversity.
  • Minimisation: measures taken to reduce the duration, intensity and / or extent of impacts (including direct, indirect and cumulative impacts, as appropriate) that cannot be completely avoided, as far as is practically feasible.
  • Rehabilitation/restoration: measures taken to rehabilitate degraded ecosystems or restore cleared ecosystems following exposure to impacts that cannot be completely avoided and/ or minimised.
  • Offset: measures taken to compensate for any residual significant, adverse impacts that cannot be avoided, minimised and / or rehabilitated or restored, in order to achieve no net loss or a net gain of biodiversity.  Offsets can take the form of positive management interventions such as restoration of degraded habitat, arrested degradation or averted risk, protecting areas where there is imminent or projected loss of biodiversity.

"Biodiversity offsets only come into play once rigorous steps have been taken first to avoid and minimize impacts. Far better to avoid harm to vulnerable and irreplaceable biodiversity to the extent possible, than to make good on damage later."

Kerry ten Kate, BBOP Director