Mitigation Hierarchy 

The mitigation hierarchy is a sequential approach to addressing potential negative project impacts. The hierarchy prioritises impact avoidance first, followed by impact minimisation, then impact mitigation, and lastly, compensation for residual impacts. 

HydroSelect’s ESG Risk analysis can be viewed as a way of identifying potential risks that can be largely, or only, addressed through “avoid.” 

  1. Impact avoidance seeks to prevent or reduce negative impacts. Avoidance is prioritised as the initial step in the mitigation hierarchy, as it is often the most cost-effective and efficient way to guarantee reducing potential negative impacts. For hydropower project options, it is often achieved through site selection and establishment of overall operational objectives, as well as through the selection of best available technologies. An Extreme Risk rating on any of HydroSelect’s ESG Risks seeks to inform this initial step of the mitigation hierarchy. 

  2. Impact minimisation seeks to reduce the area and/or extent of impacts when outright avoidance is not feasible. For hydropower project options, impact minimisation is often achieved through choices in lay-out and design, and planned operational strategies, as well as through the selection of best available technologies. HydroSelect’s ESG Risk ratings of High or Moderate Risk can promote revisions of project options to try to low the initial ESG Risk ratings. 

  3. Impact mitigation seeks to reduce the duration, intensity, and/or extent of residual impacts that cannot be avoided and are still present after minimisation measures have been fully implemented. For hydropower project options, impact minimisation measures such as downstream flow releases, fish passage structures and sediment through-flow features will never fully avoid impacts, although if designed and operated well they can achieve some impact minimisation. Impact mitigation will still always be required and typically involves implementation of carefully researched and designed impact management plans that have clear objectives, processes, resources, monitoring, evaluation, and allowance for follow-up and possibly adaptative measures. HydroSelect’s ESG Risk ratings help inform that impact mitigation measures should be identified and evaluated for those project aspects rated, after avoidance and minimisation measures have been applied, as Moderate Risk or Low Risk.

  4. Impact compensation addresses the residual, unavoidable impacts after all avoidance, minimisation and mitigation measures have been implemented. Compensation involves commitments and actions to protect, enhance, restore or otherwise improve similar resources to those that have been impacted, referred to as ‘offsets’. Further information on biodiversity offsets is set out here. ‘Offsetting’ quantifies how much compensation is required for a residual impact. Ideally, offsets should be located and/or implemented close to the point of impact as possible and be “like-for-like”.