Wetlands on Your Property: What It Means and What to Do

A wetland on your parcel is not automatically a catastrophe, but it is always a constraint — and the gap between "mapped as wetland" and "legally jurisdictional wetland" is where most of the confusion, and most of the expense, lives.

Check the map first

The US Fish and Wildlife Service maintains the National Wetlands Inventory, a free national mapping layer. LandCheck queries it at your point and within roughly 400 metres, so you see both what is on the site and what is next door.

Understand what NWI is — and is not

NWI was produced largely by interpreting aerial photography, at scales around 1:24,000 to 1:58,000, over a period spanning decades. That has two consequences that matter:

• Absence is weak evidence. Small, seasonal, forested and farmed wetlands are routinely missed. A clean NWI result does not mean there is no wetland.
• Presence is not a determination. A mapped polygon does not by itself establish federal jurisdiction. Only the Army Corps of Engineers can do that.

The three criteria

A delineation looks for all three: hydrophytic vegetation (plants adapted to saturated soil), hydric soils, and wetland hydrology (evidence of inundation or saturation during the growing season). All three must generally be present. This is why a consultant walking the site can reach a different conclusion from the map in either direction.

What you can and cannot do

Generally permitted without a federal permit: normal ongoing farming and ranching, forest road maintenance, and many maintenance activities on existing structures. Generally requiring a permit: any discharge of dredged or fill material into waters of the United States — which includes filling, grading and often ditching.

Permits come in two broad flavours. A nationwide permit covers small, routine impacts with a streamlined process. An individual permit is required for larger impacts and involves public notice, agency review and usually compensatory mitigation — buying credits from a mitigation bank or restoring wetland elsewhere. Individual permits take many months and cost real money.

What a delineation costs and involves

A consultant visits the site, samples soil pits, records vegetation, notes hydrology indicators, and flags the boundary with GPS. You receive a report and a map. Prices vary widely with parcel size and complexity; a small residential parcel is usually a modest professional fee, while a large or complex site costs considerably more. For a transaction, the delineation is often paired with a request for an Approved Jurisdictional Determination from the Corps, which is what gives it legal weight.

The practical decision

If a wetland is mapped on the part of the parcel you wanted to build on, you have three options: redesign around it, pursue a permit, or walk. Redesigning is almost always cheaper than permitting. Walk away from any deal where the seller cannot or will not extend the contingency period long enough for a delineation, if the map has flagged something.

State rules can be stricter than federal ones, and several states regulate wetlands the federal government does not. Check the state environmental agency as well as the Corps.

Common questions