Legal Definitions - decrementum maris

Decrementum maris refers to the natural process where the sea permanently withdraws from the land, exposing areas that were previously submerged.

• Consider a coastal homeowner whose property line was originally defined by the high-water mark of the ocean. Over many years, due to a combination of geological uplift and sediment accumulation, the average high-tide line has gradually shifted seaward, revealing a new strip of dry land in front of their existing property. This expansion of land due to the sea's retreat is an example of decrementum maris, which could potentially result in the homeowner acquiring title to this newly exposed land through the legal principle of accretion.

• A state environmental agency is conducting a comprehensive survey of its coastline to update property maps and assess changes in land use. They observe a specific estuary where, over the past fifty years, the water line has consistently receded, transforming what was once a shallow, marshy area into stable, dry ground now supporting terrestrial vegetation. This long-term, observable retreat of the water's edge, creating new land, is a clear manifestation of decrementum maris, impacting the legal boundaries and potential uses of the affected parcels.