Nationwide Permit 46 authorizes the discharge of dredged or fill material into certain non-tidal ditches that have been determined to be waters of the United States. To qualify, the ditch must have been originally constructed in uplands, received water from a jurisdictional waterbody prior to construction, and diverted that water to another jurisdictional waterbody. This permit provides a streamlined path for projects that require filling or modifying these specific types of man-made water conveyances. The permit is strictly limited to non-tidal ditches and cannot be used for activities in ditches constructed in streams or other jurisdictional waters, nor can it be used in non-tidal wetlands adjacent to tidal waters. The primary intent is to allow for the maintenance or modification of upland-constructed ditches while ensuring the total loss of jurisdictional waters does not exceed one acre.
The 2026 reissuance of NWP 46 maintains the same national terms and conditions as the 2021 version, including the one-acre acreage limit and the mandatory pre-construction notification (PCN) requirement. The Corps reevaluated the permit’s impact thresholds and determined they remain appropriate for ensuring that authorized activities result in no more than minimal individual and cumulative adverse environmental effects. While the regulatory text is unchanged, the supporting decision document has been updated with the most recent environmental baseline data. This includes data from the 2022 National Lakes Assessment and the 2021 National Wetland Condition Assessment, ensuring that the Corps' cumulative impact analysis for ditch-related discharges is based on the latest available ecological science.
Compliance managers for agricultural operations, irrigation districts, and land developers typically use this permit. It is specifically for those needing to fill or modify man-made ditches that, while constructed in uplands, are regulated because of their connection to the larger jurisdictional tributary system.
The Corps determined that the reissuance of NWP 46 results in a 'no effect' finding for federally-listed endangered or threatened species and designated critical habitat. This is maintained through 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 completed. Compliance with Section 106 of the National Historic Preservation Act is ensured through General Condition 20. Because every project under NWP 46 requires a PCN, district engineers are able to review each proposal for potential impacts to historic properties. For Essential Fish Habitat (EFH), district engineers apply regional or case-specific conditions to ensure that discharges in ditches do not cause more than minimal adverse effects on sensitive aquatic environments.
Stay current on NWP 46 updates
Get notified when regulations change — no spam, just updates that matter.