Accretion in real estate is the slow, natural buildup of soil, sand, or sediment along the edge of a waterfront parcel, gradually adding new land to the property. Under long-standing common law, that new land generally belongs to you automatically: your boundary follows the water’s edge, and when the edge moves outward, your boundary moves with it. The catches are in what “gradual” means, whether the water is navigable, whether the buildup is natural, and what you’re allowed to do with the new ground once it exists.
How the Buildup Happens
Rivers, lakes, ocean currents, and tidal action carry particles of soil, sand, and rock. When those particles settle along a shoreline or riverbank, they add to the existing landmass one thin layer at a time. Week to week, you wouldn’t notice. Aerial photos taken decades apart can show a shoreline that has moved by yards.
Gentle slopes toward the water accumulate sediment faster than steep banks. Upstream conditions matter too, because construction, deforestation, or agricultural runoff miles away can increase the sediment a river carries and speed deposition on your bank while eroding someone else’s.
Who Owns Land Added by Accretion
The default rule is simple. Land added to your parcel through accretion is yours, and you don’t need to file a claim or get government approval for the ownership itself to transfer.1Cornell Law School. Accretion The rule applies to riparian owners along rivers and streams and to littoral owners along lakes and oceans.
The change has to be gradual and imperceptible. Courts read “imperceptible” to mean you can’t watch it happen in real time. If you can stand on your porch after a single storm and see that the land has grown, that isn’t accretion, and a different set of ownership rules takes over.
Navigable Waters
Ownership is less clean along navigable waterways. Under the public trust doctrine, states generally hold title to the beds of navigable rivers, lakes, and tidal waters for the benefit of the public. Whether accreted land belongs to you or to the state usually turns on where the sediment settles relative to the ordinary high-water mark. In many jurisdictions, accretion above that line belongs to the adjacent private owner, and anything below it stays state property. If your parcel sits on a navigable body of water, a survey and legal advice are worth the money.
Natural vs. Artificial Buildup
The automatic-ownership rule assumes natural forces caused the accretion. When humans caused it, through jetties, seawalls, dredging, or upstream construction, many courts will not grant the adjacent landowner title to the new ground, particularly when the buildup came from government infrastructure such as breakwaters or navigation channels. Some jurisdictions allow ownership of artificially accreted land in certain circumstances, but you can’t count on it. If your lot is growing because of a nearby Army Corps of Engineers project rather than natural currents, confirm the ownership question before treating the ground as yours.
Accretion vs. Avulsion, Reliction, and Erosion
Accretion is one of four natural processes that move waterfront boundaries, and each has its own ownership consequence.
Avulsion
Avulsion is the sudden, visible removal or addition of land, typically from a flood, storm, or abrupt change in a river’s course. The line dividing it from accretion is speed. When a flood tears a chunk of your riverbank away and deposits it on someone else’s property downstream, you technically still own the displaced soil, and the original property boundaries hold.2Legal Information Institute (LII) / Cornell Law School. Avulsion Recovering the soil is usually impractical, but the rule protects owners from losing title through sudden events they can’t control.
Reliction
Reliction happens when a body of water permanently recedes and exposes land that had been underwater. No new sediment is deposited; the existing bed simply becomes dry. The adjacent owner gains title to the newly dry land, but only if the recession is permanent.3Legal Information Institute (LII) / Cornell Law School. Reliction Seasonal fluctuations and temporary drought don’t count.
Erosion
Erosion is the mirror of accretion. Water gradually wears the shoreline away, and just as you gain title to accreted land, you lose title to eroded land. Once the water has claimed it, it’s gone from your deed. There is no recourse against nature and no compensation. It’s an inherent risk of owning waterfront property.
What You Can Actually Do With Accreted Land
Owning accreted land and being allowed to build on it are two different things. Newly formed waterfront ground often falls inside federally protected zones, and developing it without permits can carry serious fines.
The main hurdle is Section 404 of the Clean Water Act. Placing fill material in waters of the United States, including wetlands, requires a permit from the Army Corps of Engineers.4Office of the Law Revision Counsel. 33 USC 1344 – Permits for Dredged or Fill Material Accreted land at or near the waterline frequently qualifies as wetland, which can mean federal approval before you pour a foundation, build a retaining wall, or even grade the surface. State and local wetland rules often stack additional requirements on top. Before touching accreted ground, check with your local Army Corps district office and state environmental agency.
Taxes When the Lot Grows
Accreted land affects your finances in two main ways.
County assessors can reassess your property when its physical footprint changes. If accretion adds meaningful acreage, expect the assessed value and your tax bill to eventually reflect the larger lot. How quickly this shows up depends on your jurisdiction’s reassessment cycle and on when updated survey data or aerial imagery reaches the assessor.
Capital gains are trickier. Tax basis is generally what you paid for a property.5Internal Revenue Service. Topic No. 703, Basis of Assets You paid nothing for accreted land, so the portion of your parcel created by accretion likely carries a zero cost basis. When you sell, the sale proceeds attributable to that portion would be taxable gain. On a lot that has grown substantially over decades, that can be a meaningful tax hit that’s easy to overlook. A tax professional who handles real property transactions can help you allocate basis between the original lot and the accreted area.
Getting the New Boundary Onto Paper
You own accreted land the moment it forms, but your deed and the public records won’t reflect it automatically. To sell, refinance, or develop the new area, you’ll need to formalize the boundary.
Updated Survey
Hire a licensed surveyor to map the current shoreline and establish where your boundary now sits. Waterfront surveys cost more than standard lot surveys because the surveyor has to account for irregular, shifting boundaries rather than fixed corner pins. The price depends on the property’s size, its terrain, and how much the shoreline has moved.
Quiet Title Action
If anyone disputes the ownership, or if you want a court order confirming it for title insurance purposes, you can file a quiet title action. This is a lawsuit that asks a court to formally declare you the owner and eliminate competing claims.6Legal Information Institute (LII) / Cornell Law School. Quiet Title Action Once judgment enters in your favor, no one else can later challenge your title to that ground. It’s especially useful when the accretion is large enough that neighbors or the state might assert competing claims.
Title Insurance
Standard title policies typically exclude coverage for boundary changes caused by accretion or erosion. If a dispute arises over accreted land after you buy, your title insurer may not cover your legal costs or losses. If you’re buying waterfront property where accretion is a factor, ask your title company whether an endorsement covering water-boundary changes is available. It’s a small addition that can close an expensive gap.