• CEs account for 88% of projects but only 5% of total pages — the vast majority of NEPA activity is routine and low-documentation by design.
• EIS reviews are ~7% of projects but generate 88% of all pages — each EIS produces an average of ~1,480 total pages, compared to ~152 for EAs and ~7 for CEs.

• Decarbonization-related projects use Categorical Exclusions at higher rates than fossil fuel or other project types, likely reflecting smaller average project footprints.
• Fossil fuel projects show higher EA/EIS rates, consistent with larger environmental footprints requiring more detailed review.
• CE is the dominant NEPA pathway for decarbonization-related projects across all technology types.

• Utilities and Electricity Transmission dominate, possibly reflecting the infrastructure build required to connect renewable energy generation.
  
• While most projects are granted “Categorical Exclusion (CE)” status, Hydropower, Nuclear, and Wind have notably higher rates of EA/EIS reviews, reflecting larger potential environmental footprints than many of the other types of projects.

• DOE accounts for 81% of all decarbonization-related projects — and processes 97% of those through Categorical Exclusions
• BLM shows a more varied process mix, consistent with its land-management mandate for large-scale renewables on federal lands.
• See Appendix for detailed coverage note: Only DOE and BLM have comprehensive CE, EA and EIS data so the second figure limits to those departments/agencies for a clearer picture.
• Key department deep dive analysis →

• Western states dominate renewable-driven activity: Washington, California, Idaho, and Colorado together account for a large share of transmission, solar, wind, and hydropower projects.
• South Carolina leads with 2,000+ projects — largely driven by DOE’s Savannah River Site nuclear facility.

• Decarbonization-related projects across all three review types are predominately located in western counties of the United States, consistent with the concentration of public lands managed by BLM, Forest Service, and DOE in the West.
• Electricity Transmission and solar projects dominate EAs and EIS in the southwest (see project deep dive)

• Standard review is the overwhelming norm — Almost 90% of projects use the standalone standard review process.
• Tiered reviews are more rare

• The Nuclear Regulatory Commission and BLM drive Other Independent Agencies and Department of Interior non-standard review use – check out our analysis on the website
• Non-standard reviews are not evenly distributed: they concentrate in western states and large-scale land-use actions where BLM and Forest Service manage extensive federal acreage.

Tiered EAs take longer than standard EAs on average — but they are substantially shorter than a full EIS, suggesting the real efficiency gain from tiering is when it allows an agency to avoid a full EIS altogether rather than just shortening an EA.

Tiered EISs take less time than standard and programmatic EISs, though distributions substantially overlap and sample sizes are small.

WORD OF CAUTION: Small sample for non-standard reviews is still quite small to draw strong conclusions here.

• The CE→EA→EIS duration gradient is steep: median durations range from ~1 month (CE) to ~14 months (EA) to ~34 months (EIS) — a rather large difference.
• The long tail drives NEPA’s reputation: 10% of EIS reviews exceed 7.5 years, but this is not typical — the median is 3 years.
• Timeline completeness is partial: only 30% of CEs have extractable dates; EA (62%) and EIS (48%) are better but not complete, so medians likely undercount the slowest cases.

• CE peaked in 2010, could be due to the American Recovery and Reinvestment Act (ARRA) stimulus
• CE again peaked in 2022 and 2023, likely resulting from the Inflation Reduction Act (IRA)/ Bipartisan Infrastructure Law (BIL) investment surge

• CE projects are largely small and medium-scale projects; utility-scale projects mostly EIS, and EA having a balanced mixture
• CE median: 1.2 MW | EA median: 60 MW | EIS median: 538 MW — Review intensity is broadly proportional to project scale, consistent with NEPA’s risk-proportional design.

• Multi-state projects are predominantly CE or EIS-level, whereas Multi-department projects are predominantly EIS-level.

• Western states dominate multi-state activity
• Top corridors: connecting renewable-rich areas to load centers in California and the Pacific Northwest, main exceptions being CO-NM and NE-MO

• Department of Energy (DOE) dominates multi-department projects (9 partner agencies)
• Department of Energy and Department of Interior partner together the most

Slight decline right FRA but then an uptick. EA mean fell ~22% and EIS fell ~25% post-FRA, but then the rolling average trends up afterwards — causation is uncertain.

Small post-FRA sample: only 33 EAs and 42 EISs completed after June 2023.

• EAs are largely compliant: ~70% of post-FRA EAs meet the 75-page limit — a strong signal that the rule is working for shorter reviews.
• EIS compliance is more mixed: Only 29% of EIS documents meet the 150-page limit outright; but another 29% fall in the 150–300 “extraordinary complexity” range and are compliant — a total of 57% compliant under the full standard.

Mixed results: No strong statistical relationship between line length and review duration.

• Median length is 8 miles and most (55%) under 10 miles
• Very long lines (≥100 miles) take ~6× longer, but with small N.

914 NEPA actions | 5 phases | A single geothermal project may require multiple sequential NEPA reviews — the total permitting burden is the sum of all phases, not just one review.

6,133 total pipeline NEPA actions | Natural gas provides the most reliable baseline | Carbon and hydrogen samples are very small — treat as exploratory findings only.

Coverage note: Only DOE and BLM have comprehensive CE, EA and EIS data so the second figure limits to those departments/agencies for a clearer picture.

• CE is dominated by utilities/transmission and nuclear — reflecting DOE’s vast categorical exclusion program for grid and facility upgrades.
• EA reviews show more technology diversity: solar, wind, and geothermal appear prominently alongside transmission, suggesting EAs are triggered by larger renewable buildouts.
• EIS reviews concentrate on high-impact technologies: large transmission, wind, and hydro projects — the ones most likely to require full environmental impact analysis due to scale or site sensitivity.

• Upgrades dominate — most transmission NEPA activity is replacements and upgrades, not greenfield construction.
• New builds are relatively rare but tend toward longer lines.