Can You Build on a Wetland? Section 404 Permits and Penalties

You can build on a wetland, but only after working through a layered permit system that starts with figuring out whether the wetland on your property is even regulated. Since the Supreme Court’s 2023 decision in Sackett v. EPA, fewer wetlands fall under federal Clean Water Act jurisdiction, but state and local rules often pick up where federal protection stops. Where a permit is required, expect a wetland delineation, months of review, compensatory mitigation for any unavoidable loss, and costs running into the thousands. Skipping the permit is the expensive path: civil penalties can exceed $50,000 per day, and enforcement typically ends with a restoration order that undoes whatever you built.

Figuring Out Whether Your Wetland Is Regulated

Wetland status is not about how the land looks in July. A wetland is land where water sits at or near the surface long enough to produce hydric soil and hydrophytic vegetation, and a property can look dry for months and still qualify. The exact boundaries are set by a formal process called delineation, in which an environmental consultant samples soil, inventories plant species, looks for signs of water presence, and maps the wetland’s edges. A few feet of difference in that map can decide whether your building footprint triggers a permit at all.

Federal Jurisdiction After Sackett

Federal protection is narrower than it used to be. In Sackett v. EPA, the Supreme Court held that the Clean Water Act covers only wetlands with a “continuous surface connection” to a relatively permanent body of water that itself connects to traditional interstate navigable waters, so indistinct that it is difficult to tell where the wetland ends and the water begins.¹ Isolated wetlands, seasonal wetlands, and wetlands linked to navigable waters only through underground flow or intermittent channels generally fall outside that test.

If your wetland lacks that continuous surface connection, federal permitting probably does not apply. That is not the end of the analysis, though.

State and Local Rules Are the Second Layer

Many states and localities regulate wetlands independently, and some rules are stricter than the federal ones. Local ordinances impose buffer zones around wetlands ranging anywhere from 25 feet to over 100 feet from the wetland edge, with some jurisdictions banning any soil disturbance in the buffer and some layering an additional building setback on top of the nondisturbance zone. Others require a separate state permit whether or not the Corps is involved.

The Sackett ruling made this layer more important. Many states had relied on federal jurisdiction as their primary wetland protection tool, and after Sackett some have moved to fill the gap while others have not. A wetland that lost federal protection could still be tightly regulated by the state, or it could be unregulated entirely. Check with your state environmental agency and your local planning office before assuming any wetland is fair game.

Which Federal Permit You’ll Need

If your project puts fill material into a federally regulated wetland, you need a permit under Section 404 of the Clean Water Act. Fill material is defined broadly: dirt, sand, rock, concrete, and building foundations all count. The U.S. Army Corps of Engineers runs the day-to-day permitting; the EPA sets the environmental criteria and retains a rarely used veto.²

Both agencies apply a strict sequence. You must first show you have avoided wetland impacts where possible, then minimized what you cannot avoid, and only then propose compensation for what remains.³ Jumping straight to mitigation is a common way to get a permit denied.

Nationwide Permit vs. Individual Permit

Which permit you need turns mostly on how much wetland your project affects. Nationwide permits are pre-authorized general permits for smaller impacts. For residential construction, Nationwide Permit 29 covers single homes, multi-unit developments, and subdivisions in non-tidal waters, as long as the total wetland loss stays under half an acre.⁴ For subdivisions, that half-acre cap applies to the whole development, not per lot. Commercial and institutional projects face the same half-acre limit under Nationwide Permit 39.⁵

Even under a nationwide permit, you generally have to submit a pre-construction notification to the local Corps district engineer, and if your project touches more than one-tenth of an acre of wetlands, compensatory mitigation is required. Endangered species habitat or historic properties trigger additional consultations. In fiscal year 2024, the average processing time for a nationwide permit notification was 55 days.⁵

Projects that exceed those thresholds need an individual permit. That means a full application with detailed plans, an alternatives analysis showing why less damaging options are impractical, a mitigation proposal, and a public notice comment period. In fiscal year 2024, individual permits averaged 253 days after the Corps received a complete application.⁵ Complex or controversial projects run longer.

What the Permit Process Actually Looks Like

Delineation and Jurisdictional Determination

The first practical step is hiring an environmental consultant to delineate the wetlands on your property. Costs range from around $2,000 for a small, simple parcel to $10,000 or more for large or complex sites.

With the delineation in hand, you can ask the Corps for a jurisdictional determination. An approved jurisdictional determination is a formal, legally binding opinion on whether your wetlands are federally regulated. It stays valid for five years and can be administratively appealed if you disagree.⁶ A preliminary jurisdictional determination is faster because it simply assumes jurisdiction rather than deciding the question, but accepting one waives your right to challenge jurisdiction later.

Pre-Application Meeting and Filing

A pre-application meeting with the Corps district office and any relevant state agencies is worth the time. You can present the project concept, learn which permits apply, and get early feedback on whether your avoidance and minimization measures are likely to hold up. Redesigns at this stage save months later.

The formal application bundles the delineation report, project plans showing wetland impacts, an alternatives analysis for individual permits, and your mitigation proposal. For individual permits, the Corps then issues a public notice with a comment period before making a decision.

Compensatory Mitigation

When wetland loss is unavoidable, you have to offset it.⁷ Three options exist:

Buying credits from an approved mitigation bank that has already restored or created wetlands. This is the Corps’ preferred approach, and credits typically run between $50,000 and $100,000 per acre, with wide regional variation.
Paying into an in-lieu fee program, where a government or nonprofit sponsor pools contributions to run larger mitigation projects.
Doing the mitigation yourself, on-site or at an approved off-site location. You get the most control and carry the long-term success risk.

The Corps generally prefers banks and in-lieu fees over do-it-yourself mitigation because established wetlands come with less uncertainty and no gap between destruction and replacement.⁷

Activities That Don’t Need a Section 404 Permit

A handful of activities are exempt: normal farming, forestry, and ranching operations, plus maintenance of existing structures like dikes, dams, and levees.⁸ The exemption applies only to established, ongoing operations, so clearing a wetland with plans to start farming does not qualify.

Even a genuine exemption disappears under the “recapture provision” if the activity converts the wetland to a new use and impairs the flow or circulation of waters.⁸ Both conditions have to be met. Turning a farm with an exempt pond into a residential subdivision changes the use and alters water flow, so the exemption drops away and a permit is required.⁹

What Building Without a Permit Costs You

Unauthorized wetland fill is actively enforced. Civil penalties under the Clean Water Act reach $50,000 per day for knowing violations and $25,000 per day for negligent ones, with those figures adjusted upward for inflation. Criminal exposure runs from up to one year in prison and $2,500 to $25,000 per day for a negligent violation to up to three years and $5,000 to $50,000 per day for a knowing one. Second convictions double both the prison maximums and the fine maximums.¹⁰

The bigger financial hit is usually the restoration order. The EPA’s first enforcement priority is removing the fill and restoring the wetland to its original condition.¹¹ That means tearing out whatever you built, hauling away the fill, replanting native vegetation, and monitoring the site for years. Restoration costs routinely exceed what the permitted project would have cost in the first place.

Before You Buy Wetland Property

Check the U.S. Fish and Wildlife Service’s National Wetlands Inventory, a free online mapping tool that shows the approximate location and type of wetlands nationwide. Treat it as a screening tool, not a final answer. NWI maps are based on a biological definition and aerial imagery, they carry an inherent margin of error, and they are not regulatory determinations. A parcel that looks clear on the map can still contain wetlands that a field delineation would identify, and Corps regulatory boundaries may differ from what the NWI shows.¹²

If wetlands are even a possibility, build a contingency into the purchase contract that gives you time for a professional delineation. If regulated wetlands would make your project infeasible or much more expensive, the contingency lets you walk away. Seller disclosure laws in most states cover known physical defects, but many sellers do not know their land contains jurisdictional wetlands, so the burden of finding out falls on you.

1
Supreme Court of the United States. Sackett v. EPA, No. 21-454
2
US EPA. Permit Program Under CWA Section 404
3
eCFR. 40 CFR Part 230 – Section 404(b)(1) Guidelines for Specification of Disposal Sites for Dredged or Fill Material
4
U.S. Army Corps of Engineers. Nationwide Permit 29 – Residential Developments
5
Federal Register. Reissuance and Modification of Nationwide Permits
6
U.S. Army Corps of Engineers. Regulatory Guidance Letter 16-01
7
eCFR. 33 CFR Part 332 – Compensatory Mitigation for Losses of Aquatic Resources
8
eCFR. 40 CFR Part 232 – 404 Program Definitions; Exempt Activities Not Requiring 404 Permits
9
U.S. Army Corps of Engineers. Information Regarding Compliance with the Federal Clean Water Act Section 404(f)(1) Provisions
10
Office of the Law Revision Counsel. 33 USC 1319 – Enforcement
11
US EPA. How Enforcement Actions Protect Wetlands Under CWA Section 404
12
U.S. Fish & Wildlife Service. Wetlands Mapper Documentation and Instructions Manual