Environmental Assessments

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Environmental Assessments


An environmental assessment (also known as an environmental impact assessment) is a process that gauges the potential environmental impact of a project before it is begun. The purpose of the assessment is to identify possible environmental effects, suggest remedies to deal with adverse effects, and to predict if these remedies will be successful.

An assessment that indicates a potential for substantial and/or long-lasting environmental damage can lead to modifications of the proposed project or its outright cancellation. A successful environmental assessment produces a project that has been conceived and implemented considering the environment, and so which results in minimal environmental impact or impacts that can be remediated or anticipated.

Historical Background and Scientific Foundations

Following World War II (1939–1945), large-scale development of natural resources began in many countries including the United States. Initially, little consideration was given to the environmental consequences of mega-projects, although as time went on, the degradation of wildlife habitats, air, and water began to be apparent.

The 1962 publication of Rachel Carson’s book Silent Spring, which chronicled the widespread and extensive use of chemicals like DDT and the possible adverse consequences on the natural environment and humans, made many people aware of anthropogenic (human-caused) environmental degradation. By the late 1960s, the growing public concern about the environment led to legislation such the U.S. National Environmental Policy Act. By the mid-1970s, environmental assessments of government projects were mandatory in the United States, Canada, and Europe.

Environmental assessments are best accomplished as early in the planning stages of a project as possible. This allows any project changes to be incorporated into the project smoothly and helps ensure that the environmental safeguards will be fully and properly implemented. This also allows for public input into the project.

The assessment process is a multi-step effort, which begins with the decision that an assessment is necessary. Sometimes this decision is automatic; for example, federal government projects require an environmental assessment, and many state and local governments have instituted requirements for assessment by private planners in the development approval process. Next, the environmental assessment is planned with respect to its scope of activity and time deadlines. The various environmental analyses are then done, and based on these, an environmental assessment report is written. The responsible authority reads the report and makes a decision as to the whether the project can proceed as planned or whether modifications are required. If the project proceeds, its progress will be monitored to ensure adherence to the requirements of the assessment and to also ensure that little if any environmental damage occurs. If the project is modified as a result of the environmental assessment, the revised project will be assessed before approval is granted. Once the project begins, environmental monitoring also begins.

An environmental assessment typically first involves an overview of the project. This phase, which is called a screening, helps identify areas of concern and parts of the project that warrant more in-depth analysis. For example, a screen of a construction project may reveal a proposed watercourse modification. A more in-depth look at the consequences of the alteration on the water flow and the potential for water-related damage downriver could then be undertaken.


ANTHROPOGENIC: Made by humans or resulting from human activities.

ENVIRONMENTAL IMPACT STATEMENT: A document outlining the potential environmental impact of any new federal project, required by the U.S. National Environmental Policy Act.

REMEDIATION: A remedy. In the case of the environment, remediation seeks to restore an area to its unpolluted condition, or at least to remove the contaminants from the soil and/or water.

An environmental assessment that recommends modifications can also involve a third party who tries to mediate an agreement between the agency conducting the assessment and the project organizers. Alternately, an assessment may involve the input of a selected panel of experts. Typically such a review panel is authorized by the government agency that is involved in the project (such as the U.S. Environmental Protection Agency), and the panel reports its findings and recommendations to the authorizing agency.

Impacts and Issues

Environmental assessments are fundamentally important in minimizing adverse environmental impacts of development. The need for an assessment for large-scale projects, as well as small projects (such as an apartment building that borders a watercourse) helps ensure that the planning and execution of projects are subject to environmental and public scrutiny.

Improperly prepared or conducted environmental assessments can result in a legal challenge or blockage of a project. One example from the mid-1980s was the halting of a proposed landfill and highway bordering the Hudson River in New York City. More recently, the widening of U.S. Highway 95 through Las Vegas was temporarily blocked in 2003 due to concerns about generated air pollution that has not been adequately addressed in the assessment. The project eventually resumed following modifications to better safeguard air quality.

The approval of a project following an environmental assessment is no guarantee that the project will not be harmful to the environment. For example, approval for the development of the Alberta oil sands—a massive project that is extracting oil from the sandy material underlying thousands of square miles in the Canadian province of Alberta—was given by the federal and provincial environment departments with the knowledge of the project’s environmental degradation. Approval was contingent on the restoration of the affected areas once the extraction had been complete, although whether these measures were stringent enough has become debatable.

See Also Agricultural Practice Impacts; Bioremediation; Human Impacts; Oil Spills; Toxic Waste



Atlas, Ronald M., and Jim Philip. Bioremediation: Applied Microbial Solutions for Real-World Environment Cleanup. Washington: ASM Press, 2005.

Kidd, J. S., and R. A. Kidd. Air Pollution: Problems and Solutions. New York: Facts on File, 2005.

Web Sites

Canadian Environmental Assessment Agency. “Basics of Environmental Assessment.” March 16, 2007. http://www.ceaa.gc.ca/010/basics_e.htm (accessed May 1, 2008).

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