Wetlands on your parcel: what the inventory does and does not settle

There is a difference between a wetland that is mapped and a wetland that is regulated, and almost every expensive surprise on a vacant lot in West Michigan lives in the gap between the two.

Two inventories cover Michigan. The federal National Wetlands Inventory, produced by the US Fish and Wildlife Service, and Michigan's own Part 303 screening layer. Both were produced largely by interpreting aerial photography, sometimes decades old, at a scale suited to regional planning.

They are excellent at one job: telling you where to look. They are not a delineation, they do not carry a legal boundary, and they miss small wetlands and wooded wetlands routinely: a forested wetland under a closed canopy is nearly invisible from the air, which is precisely why the inventory is least reliable on exactly the wooded lots people most want to build on.

The inverse error happens too. The inventory sometimes shows wetland where there is none, because a photograph caught a wet spring or a farmed field holding water. A mapped polygon is a question, not an answer.

Part 303 of the Natural Resources and Environmental Protection Act regulates wetlands in Michigan, and the trigger is the physical characteristics of the ground (hydrology, hydric soils and wetland vegetation), not whether an inventory happened to draw it. A wetland that no map shows is still a wetland. Fill it and the enforcement is the same as if it had been drawn in red.

Michigan is one of only three states with delegated authority to administer the federal Clean Water Act Section 404 programme, which means EGLE, not the Army Corps of Engineers, is the permitting agency for most wetland work here. That is a practical advantage: it is one agency, in-state, rather than two.

Whether a given wetland is regulated depends on three things:

• Contiguity. A wetland connected to a lake, stream, river or the Great Lakes is regulated regardless of its size.
• Size. An isolated wetland larger than five acres is regulated statewide.
• County population. Below five acres and isolated, regulation depends on the county: in counties above a population threshold, EGLE has determined the wetland is essential to the protection of natural resources and regulates it. Kent and Ottawa are among the counties where smaller isolated wetlands are in play.

The consequence of that structure is that "it's only half an acre" is not the reassurance it sounds like. Half an acre touching a drain that reaches a creek is regulated.

There are two documents that carry weight, and they are different things.

A wetland determination from EGLE is the agency's own statement about whether wetland is present on a parcel and whether it is regulated. You request it, the agency visits or reviews, and it issues. It is the authoritative answer and it is inexpensive relative to what it settles.

A wetland delineation is a consultant's field survey establishing where the boundary actually runs, flagged on the ground and mapped. It is what you need if the answer is yes and the question becomes where, because the difference between a wetland covering the back third of a lot and one covering the middle of it is the difference between a buildable parcel and a nature preserve.

Both take weeks, and the growing season matters: a delineation done in February on frozen ground is a harder job than one done in June, and some consultants will not do one at all outside the growing season.

• Run the lookup. If either inventory shows wetland on or beside the parcel, that is a strong signal and the timeline just got longer.
• Look at the soil finding in the same report. Poorly drained soil with a seasonal water table close to the surface is the physical profile a wetland determination looks for, and it can flag ground the inventory missed.
• If the plan is to build, request the determination from EGLE, or hire a consultant for a delineation. Do it inside the inspection period, and negotiate an inspection period long enough to allow it.
• If wetland is confirmed and it is in the way, ask about the permit before assuming the answer is no. Minor impacts are permitted routinely, often with mitigation.

The report on this site reports both inventories and says plainly which one, if either, shows wetland at the coordinate. It also says the thing most tools leave out: a clean result on a wooded lot is the weakest kind of good news available, because the inventory is least accurate exactly there.

Filling or draining a regulated wetland without a permit is enforceable against the current owner, not the one who did it. Restoration orders follow the land. This is a reason to establish the answer before closing rather than to assume the seller's silence means anything.