Legal Definitions - alluvion

Alluvion refers to the legal principle concerning the gradual and imperceptible addition of land to a property by natural forces, typically the action of water. Over time, rivers, lakes, or oceans can deposit soil, sand, or other sediments along a shoreline or riverbank, slowly increasing the size of an adjacent property. When this occurs, the owner of the property to which the new land is added legally acquires ownership of that newly formed land.

This process is distinct from sudden, dramatic changes to land caused by events like floods, which are known as avulsion. Alluvion emphasizes the slow, natural accumulation that is often unnoticeable day-to-day but results in a measurable change over years or decades.

Here are some examples illustrating alluvion:

• Riverfront Farm: A family owns a farm situated along the winding banks of a large river. For generations, the river's natural flow has carried silt and soil downstream. Over several decades, this sediment has slowly accumulated along the riverbank adjacent to their property, gradually extending their arable land by a few feet each year. This new, naturally formed strip of land becomes part of their farm.

  This is alluvion because the land was added gradually and imperceptibly by the natural action of the river, and the farmers legally acquire ownership of this newly formed land.

• Lakefront Resort: A resort hotel is built on the shore of a large freshwater lake. The lake experiences consistent, gentle currents that move fine sand and organic matter. Over the course of fifty years, these currents have slowly deposited material along a specific section of the hotel's shoreline, subtly widening the beach area in front of their property.

  This demonstrates alluvion because the increase in the hotel's beachfront property occurred through the slow, natural accumulation of sediment by the lake's water, making the newly formed land legally part of the hotel's estate.

• Coastal Delta Wildlife Preserve: A wildlife preserve is located near the mouth of a major river where it flows into the ocean, forming a delta. Due to the river consistently carrying and depositing sediment into the shallow coastal waters over centuries, new marshland and small islands have slowly formed and expanded at the edge of the preserve, gradually increasing its overall land area.

  This is an example of alluvion because the expansion of the preserve's land occurred through the long-term, gradual deposition of soil and silt by the river's flow, naturally adding to the existing property.