Nationwide Permit 18 authorizes minor discharges of dredged or fill material into all waters of the United States. This permit is intended for small-scale projects where the total quantity of discharge does not exceed 25 cubic yards and the resulting loss of waters remains very low. The scope of this permit covers both Section 404 Clean Water Act activities and Section 10 Rivers and Harbors Act work. It is often used for miscellaneous minor fill activities that do not fall under more specific nationwide permits, provided they meet the strict volume and acreage constraints.
The 2026 reissuance of NWP 18 did not include any substantive changes to the permit's national terms, volume limits, or acreage thresholds compared to the 2021 version. The Corps reevaluated the permit's individual and cumulative effects and determined that the existing limits remain sufficient to ensure only minimal adverse environmental impacts. While the regulatory text remains unchanged, the supporting decision document was updated with the most recent environmental baseline data. This includes results from newer national assessments like the 2022 National Lakes Assessment and the 2021 National Wetland Condition Assessment to ensure the cumulative impact analysis is grounded in current data.
Compliance managers, private landowners, and small-scale contractors typically use this permit for miscellaneous minor fill activities. It is ideal for industries and individuals needing to perform minor grading, small repairs, or incidental fill tasks that do not fit into other specialized permits but stay within the 25 cubic yard limit.
The Corps determined that reissuing NWP 18 has 'no effect' on federally-listed endangered or threatened species or their critical habitat. This finding is based on General Condition 18, which requires project-specific ESA Section 7 consultation for any activity that 'might affect' listed resources; no activity is authorized until that process is complete. Compliance with Section 106 of the National Historic Preservation Act is maintained through General Condition 20, which triggers a mandatory pre-construction notification if an activity has the potential to affect historic properties. For Essential Fish Habitat, the Corps found that district engineers can apply regional or activity-specific conditions to ensure impacts remain no more than minimal.
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