Cumulative impact assessment (CIA) is the process of assessing a proposed action’s cumulative
environmental effects in the context of other past, present, and future actions, regardless of who
undertakes such other actions (CEQ, 1978). The National Environmental Policy Act (NEPA) is
generally acknowledged as the first legislative impetus behind CIA. It established a framework
under which federal agencies are required to consider project-specific and cumulative
environmental impacts of proposed projects prior to their undertaking. NEPA applies to federal
actions, but many projects occur as a result of non-federal actions and are subject to formal
environmental review administered by state governments. In contrast to the rich literature on
federal efforts, little is known about state environmental review and CIA policies and practices.
Through a review of state environmental laws, rules and agency-prepared materials, this report
identifies 37 states with formal environmental review processes. It further describes the
landscape of state efforts, and establishes and applies a two-tier framework to characterize state
policies and procedures. A national mail survey of state environmental review program
administrators was then conducted. Twenty-nine programs across the country were identified
with CIA requirements. More than half of these programs have adopted various documentations,
scales, baselines, criteria, methods, and coordination practices for assessing cumulative impacts.
The findings further suggest that a program with comprehensive and consistent environmental
review policies and procedures does not necessarily imply extensive CIA requirements and
In addition, this report discusses the barriers to and opportunities for effective CIA. Program
administrators across the country are facing similar challenges regarding the inability of existing
state environmental review frameworks to favorably structure CIA implementation and the
technical difficulties associated with conducting CIA. Ideas were proposed for overcoming CIA
barriers, including developing explicit procedural guidelines and increasing collaboration among
government agencies. However, regardless the nature and characteristics of their programs, the
administrators generally feel unsuccessful improving CIA practices.
Finally, this report discusses the policy implications for assessing cumulative impacts within the
context of state environmental review. It also suggests that future research is needed for
exploring alternative frameworks under which cumulative impacts may be more effectively
Ma, Zhao; Becker, Dennis R.; Kilgore, Michael A..
The Integration of Cumulative Environmental Impact Assessments and State Environmental Review Frameworks.
University of Minnesota.
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