Cumulative impact assessment: evaluating the environmental effects of multiple human developments. [IMPACT]

Cumulative impact assessment is required under several federal laws, regulations, and court rulings. However, comprehensive analyses of the impacts of multiple human developments on the environment have been limited. The methodology proposed consists of three phases: analysis, evaluation, and documentation. In the analysis phase, matrices are used to organize data and compute relative levels of cumulative impact on affected components of the environment. The impact of a configuration (i.e., combination of development projects) is computed as the sum of all project-specific impacts, adjusted for the effect of impact interactions among the projects. The analysis phase results in a list of values representing the relative cumulative impact of every possible configuration of the proposed projects on each target resource. Such results tend to be voluminous and incommensurable, and frequently support conflicting environmental objectives. Therefore, in the evaluation phase, a computer screening program is used to identify configurations meeting the maximum cumulative impact criteria for all target resources. Iterations of this screening process can assist multidisciplinary teams in reaching agreement on a final set of cumulative impact criteria and on one or more configurations to be recommended. The documentation phase includes a concise summary of the anticipated environmental impacts of each recommendation.