Environmental Impact Statement

Risk assessment is the first phase of an environmental impact assessment. Environmental risk characterization is accomplished by predicting a proposed development's potential stressors at the site over time, and comparing these effects with the known boundaries of VECs. This is a preliminary reconnaissance exercise that may require environmental scientists to judge the severity and importance of potential interactions between stressors and VECs. It is highly desirable to undertake field, laboratory, or simulation research to determine the risks of interactions identified during preliminary screening. However, even the most thorough environmental assessments usually present an incomplete characterization of a site's VECs and potential impacts. Inadequate time and funds often further constrain impact assessments.

Once potentially important risks to VECs are identified and studied, it is possible to consider various planning options. EIS documentation requires both environmental assessment and an explanation of planned responses to environmental impacts. During the planning stage of the impact assessment, environmental specialists provide objective information and professional opinions to project managers. There are three broad types of planning responses to environmental impacts:

1. The predicted damages can be avoided by halting the development, or by modifying its structure. Avoidance is often disfavored by proponents of a development because irreconcilable conflicts with environmental quality can result in substantial costs, including canceled projects. Regulators and politicians also tend to have an aversion to this option, as lost socioeconomic opportunities and unfinished projects are generally unpopular.
2. Mitigations can be designed and implemented to prevent or significantly reduce damages to VECs. For examples, acidification of a lake by industrial dumping could be mitigated by adding carbonate to the lake, a development that threatens the habitat of an endangered species could suggest moving the population to another site, or a proposed coal-fired generating station could offset its carbon dioxide emissions by planting trees. Mitigations are popular ways of resolving conflicts between project-related stressors and VECs. However, mitigations are risky because ecological and environmental knowledge is inherently incomplete, and many mitigation schemes fail to properly protect the VEC. Moving a population of animals from its home habit, for instance, usually results in mortality of the animals.
3. A third planning response is to allow the projected environmental damages to occur, and to accept the degradation as an unfortunate cost of achieving the project's perceived socioeconomic benefits. This choice is common, because not all environmental damages can be avoided or mitigated, and many damaging activities can yield large, short-term profits.

It is nearly impossible to carry out large industrial or economic developments without causing some environmental damage. However, a properly conducted impact assessment can help decision makers understand the dimensions and importance of that damage, and to decide whether they are acceptable.