Most erosion repair projects in the United States are trying to fit within Nationwide Permit 13. It is the general permit written for bank stabilization, and where a project fits, the path to authorisation is dramatically shorter than an individual permit.
Not legal advice, and the specific limits are deliberately not quoted here. The reason for that is the most important thing in this article.
How nationwide permits work
The Corps periodically issues a set of nationwide permits: pre-authorised categories of activity determined to have minimal individual and cumulative adverse environmental effects. Rather than reviewing each project from scratch, the Corps authorises the category in advance, subject to limits and conditions.
Each NWP carries:
- Activity limits — what the permit covers and the thresholds beyond which it does not
- General conditions applying across all NWPs, covering things like navigation, water quality, endangered species, historic properties, and migratory birds
- Regional conditions added by each Corps district for its area
- State conditions, added through the Section 401 certification process
That layering matters: the national text is the starting point, and your district and state add to it. A project that fits the national limits can still fail a regional condition.
Why the numbers are not in this article
NWP 13’s limits — on the length of bank treated, the volume of fill per running foot, and related thresholds — change at reissuance. The nationwide permits are reissued periodically, and the terms are revised in the process.
Quoting a number here would produce a page that is accurate today and quietly wrong later, on a topic where being quietly wrong means someone designs to a threshold that no longer exists. That is the same reasoning behind the no-invented-numbers position on our engineering data, applied to regulatory content.
Get the current text. It is published by the Corps, and your district’s regional conditions with it. Then design to that.
What is stable is the shape: NWP 13 limits how much bank you treat, how much material you place, and requires that the work be the minimum necessary and properly designed.
What it is structured to allow
Consistently across issuances, NWP 13 is aimed at bank stabilization to prevent erosion, and the conditions push toward:
- Work that is necessary for erosion prevention, not for creating new upland or extending a property line
- Minimum footprint for the purpose
- Stabilization that does not extend further into the water than needed
- Materials that are appropriate and stable, and not made of unsuitable material such as construction debris
- No significant impact to the aquatic environment
- Consistency with the general, regional, and state conditions
Notice how much of that is a minimisation test. The same avoid-minimise-mitigate logic from Section 404 is embedded in the general permit’s conditions.
Pre-construction notification
Many NWP activities require a pre-construction notification to the district before work starts. The district then has a defined period to respond, and it may:
- Confirm the activity is authorised
- Add conditions
- Determine that it does not qualify and require an individual permit
The PCN is not a formality. It is the point at which the district applies the general conditions to your specific project, and it is where endangered species and historic properties issues surface.
Whether a PCN is required depends on the activity, the thresholds, and regional conditions. Check.
Designing to fit
Since fitting is worth a great deal of time, it influences design:
Keep the treated length within the limit. Where a longer reach is failing, phasing can help, but be careful — the Corps looks at single and complete projects and will not usually accept a real single project split into pieces to fit a general permit.
Keep the fill volume down. Systems differ in how much material they place per foot of bank for equivalent protection. A section that achieves the protection with less fill is both a permitting advantage and usually a cost advantage.
Stay close to the existing bank line. Protection that projects into the channel raises hydraulic and habitat questions, and in a bridge opening it also worsens the contraction. The answer bank covers protecting an abutment toe without unnecessarily narrowing the waterway.
Avoid dewatering where the method allows, removing a temporary impact and an approval.
Include a bioengineered or vegetated component where the site allows. It reads well against the conditions and is often genuinely better. See rock bags vs turf reinforcement mats for where the boundary between armor and vegetation falls.
When it does not fit
Options, roughly in order of preference:
- Redesign to fit. Frequently possible, and worth real effort given the time difference.
- Check other NWPs. Other categories cover maintenance, emergency work, utility lines, and other activities, and some projects fit better elsewhere.
- Regional general permits. Many districts have their own, tailored to local conditions, and they sometimes allow more than a nationwide permit.
- Individual permit. The full process. Plan the schedule around it rather than hoping.
The mistake worth avoiding
Assuming that because a previous project on the same water was covered by NWP 13, yours is. Between then and now the permit may have been reissued with different limits, the regional conditions may have changed, the state 401 conditions may have changed, and the species listings may have changed.
Check current, every time.
Where to go next
- Permitting in-water erosion work for the overview
- Section 404 for the underlying authority
- Endangered Species Act consultation, which the PCN often triggers
- In-water work windows for the scheduling constraint
- Assembling the submittal package
- The permitting hub for the rest