Environmental Impact Statement

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Environmental Impact Statement

Conducting an environmental impact assessment

In the United States, the National Environmental Policy Act of 1969 (NEPA) requires federal agencies to file an Environmental Impact Statement (EIS) for any major project or legislative proposal that may have significant environmental effects. According to the U.S. Environmental Protection Agency (EPA), “NEPA requires federal agencies to integrate environmental values into their decision making processes by considering the environmental impacts of their proposed actions and reasonable alternatives to those actions. To meet this requirement, federal agencies prepare a detailed statement known as an Environmental Impact Statement (EIS).”

An EIS requires a federal agency to consider the environmental consequences of a proposed project, including air, water, and soil pollution; ecosystem disruption; overuse of shared water, fishery, agricultural, mineral, and forest resources; disruption of endangered species’ habitat; and threats to human health. While an EIS prompts an organization to disclose the environmental effects of their project before beginning construction or development, and to suggest ways to avoid adverse impacts, the document does not, in itself, prevent federal agencies from polluting, or otherwise endangering ecological and human health. An EIS is intended to help federal regulators and environmental compliance agencies determine whether the proposed development will violate environmental laws. United States environmental policy does not require corporations or individuals to file EIS documents, but it does expect private sector developments to comply with federal, state and local environmental and public health regulations.

Environmental impact assessment

In order to prepare an EIS, federal agencies must fully assess the environmental setting and potential effects of a project. Corporations and individuals must likewise determine whether their businesses and residences meet the environmental standards required by their national, state and local governments. Environmental impact assessment is a process that can be used to identify and estimate the potential environmental consequences of proposed developments and policies. Environmental impact assessment is a highly interdisciplinary process, involving inputs from many fields in the sciences and social sciences. Environmental impact assessments commonly examine ecological, physical/chemical, sociological, economic, and other environmental effects. Many nations require the equivalent of an EIS for projects proposed by their federal agencies, and almost all countries have environmental laws. Environmental assessment is a tool used by developers and civil planners in the U.S., Europe, and in some other parts of the world. Governmental agencies, like the EPA in the United States, typically provide guidelines for risk assessment procedures and regulations, but the financial and legal responsibility to conduct a thorough environmental assessment rests with the agency, corporation, or individual proposing the project.

Environmental assessments may be conducted to review the potential effects of: (1) individual projects, such as the construction of a particular power plant, incinerator, airport, or housing development; (2) integrated development schemes, or proposals to develop numerous projects in some area. Examples include an industrial park, or an integrated venture to harvest, manage, and process a natural resource, such as a pulp mill with its associated wood-supply and forest-management plans; or (3) government policies that carry a risk of having substantial environmental effects. Examples include decisions to give national priority to the generation of electricity using nuclear reactors, or to clear large areas of natural forest to develop new lands for agricultural use. Government agencies and businesses proposing large projects usually hire an independent environmental consulting firm to conduct environmental risk assessments, and to preview the possible environmental, legal, health, safety, and civil engineering ramifications of their development plan. Environmental consultants also perform scientific environmental monitoring at existing sites, and, if necessary, recommend methods of cleaning up environmental contamination and damage caused by non-compliant projects.

Any project, scheme, or policy can potentially cause an extraordinary variety of environmental and ecological changes. Consequently, it is rarely practical to consider all a proposal’s potential effects in an environmental impact assessment. Usually certain indicators, called “valued ecosystem components” (VECs), are selected for study on the basis of their importance to society. VECs are often identified through consultations with government regulators, scientists, non-governmental organizations, and the public. Commonly examined VECs include: (1) resources that are economically important, such as agricultural or forest productivity, and populations of hunted fish or game; (2) rare or endangered species and natural ecosystems; (3) particular species, communities, or landscapes that are of cultural or aesthetic importance; (4) resources whose quality directly affects human health, including drinking water, urban air, and agricultural soil; and (5) simple indicators of a complex of ecological values. The spotted owl (strix occidentalis ), for example, is an indicator of the integrity of certain types of old-growth coniferforests in western North America. Proposed activities, like commercial forestry, that threaten a population of these birds also imperil the larger, old-growth forest ecosystem. Determination of VECs usually requires a site-specific scientific characterization and survey of the proposed development.

Conducting an environmental impact assessment

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.

KEY TERMS

Environmental impact assessment— A process by which the potential environmental consequences of proposed activities or policies are presented and considered.

Mitigation— This is a strategy intended to reduce the intensity of environmental damages associated with a stressor. Mitigations are the most common mechanisms by which conflicts between stressors and valued ecosystem components are resolved during environmental impact assessments.

(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.

Environmental effects monitoring

Once an environmental assessment has been completed, and federal projects have filed an approved EIS, the project or policy may proceed. When the development is completed, the associated environmental stresses begin to affect species, ecosystems, and socioeconomic systems. The actual effects of a project must then be monitored to ensure compliance with environmental regulations, to observe and mitigate any unforeseen consequences, and to compare real damages to predicted ones. Monitoring might include measuring levels of chemical emissions into the air, water, or soil, observing the response of plants and animals at the site, or surveying the health of employees and nearby residents of the site. Socioeconomic impacts, like increased traffic congestion, or water availability for surrounding agricultural and municipal interests, are also including in appropriate monitoring schemes. Predictions set out in the pre-development environmental impact assessment usually determine the structure of monitoring programs. Monitoring programs must be flexible and adaptive, because “surprises,” or unpredicted environmental changes, often occur. In this sense, environmental impact assessment is an ongoing process that extends over the lifetime of a development.

Resources

BOOKS

Gilpin, Alan. Environmental Impact Assessment. Cambridge, UK: Cambridge University Press, 2006.

Noble, Bram F. Introduction to Environmental Impact Assessment: A Guide to Principles and Practice. New York: Oxford University Press, USA, 2005.

Ramachandra, T. V. Cumulative Environmental Impact Assessment. New York: Nova Science Publishers, 2006.

OTHER

United States Environmental Protection Agency. “Environmental Management.” <http://www.epa.gov/ebtpages/environmentalmanagement.html> (accessed October 30, 2006).

United States Environmental Protection Agency. “National Center for Environmental Assessment.” September 19, 2001. <http://cfpub.epa.gov/ncea/> (accessed October 30, 2006).

Laurie Duncan

The Gale Encyclopedia of Science