The Wasted Potential of Cumulative Effects Assessments

There are many different considerations that are required to be included within an Environmental Impact Assessment (EIA).  One of those considerations is the inclusion of a Cumulative Effects Assessment (CEA).  The requirement for CEAs can be found in the Canadian Environmental Assessment Act section 16(1a) (Government of Canada 2012).  The role of a CEA is to determine the contributions that a proposed project will have on the overall environmental impact in the context of past, present and future developments.  Some contributions, like the pumping of waste into a fluvial system resulting in overall higher effluent levels, are fairly obvious and measurable.  Others, such as the contribution of an individual project towards the overarching impacts of climate change, can be more difficult to ascertain.  An effective way to identify changes within an ecosystem is through the use of Valuable Ecosystem Components (VECs).  VECs are certain aspects of a natural system that are important to the fundamental nature of the system and can be used as a proxy to gauge changes in the system as a whole.  By monitoring these VECs, the impacts of certain projects on the system can be extrapolated to a certain extent.  The VECs can also be used to help understand if a system is moving towards an ecological threshold.  Huggett (2005) gives several definitions of an ecological threshold in his paper.  Essentially, ecological thresholds are levels or conditions that when met result in a rapid change to an alternate ecological condition or state.  It is possible that a population may not be able to recover and the altered state is irreversible.  The process of chopping down a tree with an axe can be used as an analogy for an ecological threshold.  As the tree is in the process of being cut down it remains standing upright, to an observer the process would not look to be affecting the tree as it is still behaving in the manner in which you would expect it to.  However, once the final blow is struck and the tree falls to the ground, there is no way of returning the tree to its original state and it is has very obviously been affected.  Crossing an ecological threshold can sometimes be like that final blow, resulting in a rapid change of state that may not be reversible.

Even though a proponent is required to include a section discussing cumulative impacts within an EIA it is often a section that does not get enough attention from proponents.  A major reason for this is the economic burden and extended time frame required to complete a rigorous CEA.  This means that many proponents will simply be unwilling or unable to undertake a comprehensive CEA. Duinker and Grieg (2006) propose that CEAs should no longer be the responsibility of project proponents, but instead they should be under the jurisdiction of an overarching government body.  A centralized government body would be able to acquire data from numerous proponents within an area in order to have access to the required information to create a useful CEA for a certain region.  A possible method for doing this would start with the government body identifying the relevant VECs in the region of interest.  The list of these VECs would then be provided to proponents in order for them to identify the specific impacts of their project on those specific VECs.  Once this information is returned to the government body they would be able to amalgamate data from a variety of proponents in order to develop an effective CEA on a regional scale.  This would be much more effective than the current project based paradigm that is being followed within EIA.  The reality of implementing a radical change like that is complicated and will have many hurdles to overcome.  The potential contribution that a comprehensive CEA can provide to the knowledge and prediction of impacts within a region means that these hurdles need to be overcome in order to improve the quality of environmental management that is the current practice within EIA.

The cumulative effects of pollution take their toll...


Duinker, Peter, and Lorne Grieg. “The impotence of Cumulative Effects Assessment in Canada: Ailments and Ideas for Redeploymentulative Effects Assessment.” Environmental Management. 37.2 (2006): 153-161.

Government of Canada. Canadian Environmental Assessment Agency. Canadian Environmental Assessment Act. 2012. Print. <;.

Huggett, Andrew. “The concept and utility of ‘ecological thresholds’ in biodiversity conservation.” Biological Conservation. 124. (2005): 301-310.

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