What Is Accretion in Real Estate? Boundaries, Permits, and Title

Accretion in real estate is the gradual, natural buildup of soil, sand, or sediment along a waterfront property, and the law treats the new ground as an automatic extension of the land it attaches to. If a river, lake, or ocean slowly deposits material on your bank over months or years, your property line moves outward with the shoreline, and the added ground becomes yours without a deed, a purchase, or a government grant.¹ Owning it, though, is not the same as being free to do what you want with it. Public rights, federal permits, and the need to update your title all affect what accreted land is actually worth to you.

How Waterfront Land Grows

Two different natural processes can expand a waterfront parcel. Both produce the same legal result, but they work by opposite physical mechanisms.

Alluvion is the deposit of solid material. Silt, sand, gravel, or soil washes up along your bank and, over time, accumulates into stable dry ground that attaches to your lot. This is the common form of accretion along rivers and streams that carry sediment.

Reliction is the permanent withdrawal of the water itself. A lake level drops and stays down, or a river channel shifts and leaves part of its old bed dry. The exposed ground connected to your parcel becomes yours. Seasonal rises and falls do not count. The water has to leave for good.

The Supreme Court has long recognized both mechanisms as paths to expanding waterfront ownership.¹ In both cases, your boundary is ambulatory. It walks with the water, so your property stays connected to the shoreline instead of being cut off by a strip of newly formed ground owned by somebody else.

The Change Must Be Gradual and Natural

Not every shoreline change gives you more land. For a change to qualify as accretion, two things have to be true.

First, the growth has to be gradual and imperceptible. You might notice over time that your yard is larger than it used to be, but you could not have watched it happen on any particular day. The Supreme Court described this as a situation where “the witnesses may see from time to time that progress has been made” but “could not perceive it while the process was going on.”¹

Second, the growth has to come from natural causes. Dredging, pumping in sand, building a jetty that traps sediment, or filling along the shoreline does not count. If you expand your shoreline artificially, you do not gain ownership of the new area under accretion principles, and the construction itself may require federal permits.

Accretion vs. Avulsion

Avulsion is the sudden counterpart to accretion, and the distinction matters because it controls whether your boundary moves at all. If a storm or flood rips land away from one bank and deposits it elsewhere, or a river carves a new channel overnight, property lines do not change. Accretion moves your boundary. Avulsion does not.¹

The logic is practical. Slow changes are impossible to track in real time, so letting the boundary follow the water is fair to everyone. Sudden changes are visible and dramatic, and allowing them to shift ownership instantly would strip people of land they could identify as theirs the day before.

If a river abruptly abandons its old channel and cuts a new one, the property boundary stays in the middle of the old channel even after the water is gone.¹ Land torn away by a sudden event generally still belongs to the original owner, and the person whose bank happens to catch a sudden deposit of soil does not gain title to it.

Where the New Boundary Sits

On most waterfront parcels, the property line runs along the ordinary high water mark. Federal regulations identify this mark by physical signs on the shore: a natural line on the bank, changes in soil character, the point where terrestrial vegetation stops, or debris left by the water.² On tidal waters, the boundary is calculated as the mean of all high tides.

When accretion extends your shoreline, the ordinary high water mark moves with it, and your legal boundary follows. Pinning down exactly where that mark sits today usually requires a licensed land surveyor who works on waterfront parcels, because the line is based on the land itself rather than on a fixed point in an old plat. The mark reflects the water’s ordinary behavior, not storm surges, floods, or seasonal extremes.

What You Actually Own

Title to accreted ground vests automatically in the owner of the adjacent upland. You do not file a claim, apply for a grant, or wait for government action. The rule applies whether you are a riparian owner (along a river) or a littoral owner (along a lake or ocean), and the reason is simple: if the state kept every new strip that formed, waterfront owners would gradually lose their access to the water, and the parcel’s waterfront character would be destroyed.¹

Automatic ownership is not unrestricted ownership, though. Several government interests sit on top of your title.

The public trust doctrine. The state owns the beds of navigable waters in trust for public uses like navigation, fishing, and recreation. If accretion creates new ground between your old boundary and the water, your ownership is still subject to whatever public trust rights apply, and courts have consistently held that public interests prevail when the two conflict. You may own the land and still not be able to block public access to the water.

Federal navigation servitude. On navigable interstate waterways, the federal government has a superior right to regulate and maintain navigability. That power overrides private interests below the ordinary high water mark. The government can alter water levels or remove structures to protect navigation without paying you for the effect on your land, and accreted ground near the waterline is particularly exposed because a small change in water management could put it back under water.

State rights to fill submerged land. The Supreme Court has held that a state, as owner of the submerged land next to littoral property, can fill its own seabed, and when the resulting change is sudden it counts as avulsion. The newly exposed ground belongs to the state, not to the adjacent private owner. A littoral owner’s right to future accretions does not override the state’s right to fill its own submerged land.³

Permits Before You Build on Accreted Land

Owning the new ground does not mean you can start construction. If the land lies near wetlands or navigable waters, federal law requires a permit from the U.S. Army Corps of Engineers before you discharge dredged or fill material. That includes placing fill for construction, building a seawall, installing riprap, or putting in any other structure, whether permanent or temporary.⁴

The Corps’ jurisdiction reaches the ordinary high water mark on non-tidal waters and the mean high water mark on tidal waters. Where adjacent wetlands exist, jurisdiction extends past the ordinary high water mark to the outer edge of the wetlands.² Accreted ground often sits inside those boundaries, especially if it was underwater recently or supports wetland vegetation. Check with the Corps district office that covers your area before starting any work.

State and local rules apply on top of the federal permit. Coastal zone management laws, shoreline setbacks, and local zoning cover accreted land the same as any other parcel, and if the land supports habitat for protected species, environmental review may also be required.

Updating Title So You Can Sell or Borrow

Even though the law gives you the accreted ground automatically, your existing deed still describes the original parcel. It says nothing about the new land. That gap in the public record causes problems when you try to sell, mortgage, or insure the property. Buyers and lenders expect a clean chain of title, and a deed that covers less ground than you claim raises questions.

The usual fix is a quiet title action, where you ask a court to formally declare that you own the accreted land. The steps typically run as follows:

A licensed land surveyor measures the accreted area, establishes the current ordinary high water mark, and prepares a plat showing the expanded boundary.
You gather historical evidence (aerial photos, satellite images, older surveys) to show the change was gradual, not sudden.
You file the quiet title complaint in the local court and name anyone who might claim an interest, which usually includes the state because it owns the beds of navigable waters.
Known claimants are served personally; unknown claimants are reached by publication in a local newspaper.
If you prevail, the court issues a decree confirming your ownership, and a new deed or plat is recorded in the county land records.

Standard title insurance policies may not cover accreted land, because the recorded deed does not describe it. Until an updated plat or deed is recorded after a successful quiet title action, a title company has nothing to insure the expanded boundary against. Handling this before you list the property avoids trouble at closing.

Property Tax Effects

Added land means a larger parcel, and a larger parcel often means a higher assessment. Assessors catch changes through aerial photography, satellite imagery, field inspections, and the recording of new plats or deeds after a quiet title judgment. Once the extra acreage is identified, the parcel may be reappraised for size and fair market value. Some jurisdictions reassess only when a new document is recorded or ownership changes; others review imagery routinely and may notice the change on their own. Declining to update your deed does not keep the land off the tax rolls.

When Erosion Goes the Other Way

The same principle that gives you ground through accretion takes it away through erosion. If the water gradually wears your bank down, your boundary retreats to the new ordinary high water mark and you lose title to whatever washes away. Erosion losses are generally not compensable; you have no claim against the government or a neighbor just because the water ate into your shoreline over time.

Seawalls, riprap, and vegetation plantings can slow the loss, but installing them near navigable waters or wetlands may require the same Army Corps permits as building on accreted land.⁴ Unauthorized erosion-control structures can lead to fines and removal orders. If you are losing land, talk to a surveyor and an environmental attorney before you build anything.

1
Justia US Supreme Court. Nebraska v Iowa, 143 US 359 (1892)
2
eCFR. 33 CFR Part 328 – Definition of Waters of the United States
3
Justia US Supreme Court. Stop the Beach Renourishment Inc v Florida Dept of Environmental Protection, 560 US 702 (2010)
4
Office of the Law Revision Counsel. 33 US Code 1344 – Permits for Dredged or Fill Material