Flooding of Creek Doesn’t Change Boundary Line

Question: We own a summer home near Greer in the White Mountains. The legal description for the boundary between our home and our neighbor’s home to the east has always been a creek. Monsoon rains and massive flooding last summer caused the creek to jump its banks and move 30 feet to the east where the creek now flows. Do we now own this additional 30 feet of land between the old creek bed and the new location of the creek?

Answer: Probably not. If there is a change in the location of a creek (or other watercourse) used as a landmark for a boundary line, the change is either classified as accretion or avulsion. Accretion is a gradual change in the location of a creek due to natural deposits like silt and sand. When accretion occurs, the boundary line moves with the creek, and the new location of the creek becomes the new boundary line. On the other hand, avulsion is a sudden and significant change in the location of the creek due to a violent rainstorm or an unusually heavy rainy season. When avulsion of a creek occurs, the boundary line does not move to the new location of the creek.

The movement of the creek by 30 feet to the east is probably classified as avulsion because the change occurred over a single monsoon season. Thus, the boundary line between you and your neighbor did not move to the new location of the creek but instead remains at the the old creek bed.

Note: Property boundary lines that rely on landmarks such as creeks and highways should be updated after any perceived changes to the landmark, e.g. the widening of a highway. These updates should be done by the recording of a new legal description after a survey of the land.