Section 6.4: Mitigation Hierarchy

The mitigation hierarchy (MH) is a framework that seeks to reduce harm to environmental biodiversity. The framework uses a set of prioritized steps to alleviate biodiversity harm via (i) avoidance, (ii) minimization (or reduction), and (iii) restoration. These three steps must be taking in sequence, whereby the goal is first and foremost to avoid. After these three steps have been taken, companies can take a fourth step as a last resort to mitigate impact of its operations on biodiversity via (iv) offsets.

Companies start off by estimating their impact on biodiversity, and then develop a plan to mitigate that impact using the mitigation hierarchy. The ultimate goal is for “no net loss” of biodiversity, and ideally, a “net positive impact”.

In addition, some companies add a fifth step known as additional conservation actions (ACAs). These actions are typically not related to the biodiversity loss of business activities.

There are many different ways in which companies can achieve a net positive impact.

The Mitigation Hierarchy Process

MH alleviates environmental harm by encouraging avoidance, minimization (reduction) and the restoration of detrimentally affected environments/ecosystems. It achieves this promoting the systematic consideration of all actions to:

1. Consciously plan to avoid environmental impacts.
2. Actively minimize any detrimental environmental impacts that occur.
3. Undertake necessary actions to restore and rehabilitate to counter any impacts.
4. Offset the residual impacts, after all other actions have been applied.

Source: CSBI 2015

Access these tabs to learn more about each of these steps within the Mitigation Hierarchy process:

Avoidance, encompasses measures taken to anticipate and prevent adverse impacts on biodiversity. It is a precursor to engaging in actions or decisions that could lead to such impacts. Avoidance is the most effective way to reducing potential negative impacts.

The principle of avoidance requires environmental aspects to be considered during the pre-planning stages of a project. If avoidance is considered too, cost-effective options can easily be missed.

An example of an avoidance action a company can take for avoidance includes careful spatial and temporal placement of infrastructure built.

Minimization, refers to measures undertaken to reduce the duration, intensity, significance and/or extent of impacts that cannot be completely avoided.  Well-planned and implemented minimization efforts can be effective in limiting any adverse impacts to below significance limits.

Restoration defines actions pursued to repair features of the natural environment that have been degraded by human activities. It attempts to re-establish, as close as possible, the conditions and environmental health that existed during the original “pre-disturbance” state. By doing so it attempts to restore ecological function and productivity.

Offsetting is the final step in mitigation hierarchy. Offsets are measurable conservation outcomes that result from actions designed to compensate for the adverse impacts that cannot be avoided, minimized and/or rehabilitated/restored. Offsets are effectively a last resort measure, after all other components of the mitigation hierarchy have been applied.

Focus Box: No Net Loss and Net Positive Impact

A) No Net Loss (NNL). To avoid a net loss in biodiversity or ecosystem services, negative impacts must be balanced against equivalent gains in other areas. No net loss (NNL) is achieved when gains from the combination of MH steps, results in no overall reduction of the type, condition and amount of biodiversity over time.

B) Net positive impact (NNI) or “net gain” is when biodiversity gains, as a result of applying the MH, exceed the biodiversity losses incurred due to adverse impacts.

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