Environmental Impact Assessment Definitions and Criteria

Environmental Impact Statement and Authority

Impact Statement: This document from the competent environmental authority is determined relative to the predicted environmental effects. It decides whether or not to carry out the planned activity and, if so, must establish conditions in order to ensure adequate environmental protection and the preservation of natural resources.

Classification of Environmental Effects

• Significant effect: A modification of the environment, natural resources, or its core operating processes that produces or can produce an appreciable effect on them.
• Minimum effect: That which can be shown to be unremarkable or negligible.
• Negative effect: That which translates into a loss of naturalistic, aesthetic, cultural, or scenic value, or results in increased pollution, erosion, etc.
• Outcome (Direct effect): That which has an immediate impact on any environmental aspect.
• Indirect or secondary effect: That which implies an interdependence of immediate impact on related environmental sectors.
• Single action: That which appears on only one environmental component.

Temporal and Cumulative Impacts

• Cumulative effect: That which is protracted by the action of the inducing agent, gradually increasing in severity as there are no effective mechanisms of elimination similar to the temporal increase of the harm-causing agent.
• Synergistic effect: That which occurs when the joint effect of the simultaneous presence of several actors poses a greater environmental impact than the sum of individual incidents referred to in isolation.
• Expected short, medium, and long term: Incidences which can manifest, respectively, within the time covered by an annual cycle, a period of up to five years, or five years or more.

Duration and Recovery of Effects

• Permanent effect: That which is an indefinite alteration in time of the predominant factors in the structure or function of the ecological systems and environmental relations at the scene.
• Temporary effect: An alteration that is not permanent in time, with a timeframe for manifestation that can be estimated or determined.
• Reversible effect: An alteration that can be assimilated by the environment in the medium term due to natural processes and mechanisms for environmental purification.