Cumulative Impact vs. Project-by-Project Review

Project-specific review and cumulative-impact analysis answer different questions.

A project-by-project process asks whether a particular proposal satisfies the zoning, environmental, utility, infrastructure, or incentive requirements that apply to that project. Those reviews are important, but they are organized around the individual proposal and the legal authority of the reviewing entity.

A cumulative-impact perspective asks a broader question: what happens when the effects of multiple projects, infrastructure investments and other stressors overlap in the same place over time? EPA defines cumulative impacts in terms of the combined effects of chemical and nonchemical stressors on health, well-being, and quality of life. That concept can include effects arising through water, air, land, infrastructure, and other community conditions.

For Ohio data centers, electricity planning provides one clear example of why aggregation matters. PJM's 2026 load forecast does not plan the regional grid one data center at a time. It incorporates the combined effect of large-load growth across utility zones. Similar cumulative questions can arise around water demand, transmission, natural-gas infrastructure, roads, land use, and public services when many projects locate in the same region.

This Visual does not claim that Ohio has a single mandatory cumulative-impact review for all data centers. It illustrates why the broader regional picture can reveal effects that may not be apparent when projects are considered individually.