Coastal Louisiana wetlands make up the seventh largest delta on Earth, contain about 37 percent of the estuarine herbaceous marshes in the conterminous United States, and support the largest commercial fishery in the lower 48 States. These wetlands are in peril because Louisiana currently undergoes about 90 percent of the total coastal wetland loss in the continental United States. Documenting and understanding the occurrence and rates of wetland loss are necessary for effective planning, protection, and restoration activities.
USGS land change analyses show that coastal Louisiana has undergone a net change in land area of about -1,883 square miles (mi2) from 1932 to 2010, or an area equivalent to the size the State of Delaware. This net change in land area amounts to a decrease of about 25 percent of the 1932 land area. Trend analyses from 1985 to 2010 show a wetland loss rate of 16.57 mi2 per year. If this loss were to occur at a constant rate, it would equate to Louisiana losing an area the size of one football field per hour, or an area greater than the size of the Island of Manhattan every year.