Habitat HomeHabitat ProtectionCoastal WetlandsImpacts

Impacts

What's Happening to Our Coastal Wetlands?

Coastal wetlands currently make up about 40 percent of the wetlands in the lower 48 states, or approximately 40 million acres. Since the 1700s, more than half of all the wetlands in the lower 48 states have been lost. California, a large coastal state, has lost more than 90 percent of its wetlands. Florida and Louisiana, two coastal states with the greatest acreage of wetlands, have lost about half of their original wetland areas. And states along the Gulf of Mexico have the highest sustained wetland loss rate in the country.

Why Are Coastal Wetlands Disappearing?

Living on the edge – Coastal wetland losses can be directly traced to population pressures and other human changes occurring along the coast. Coastal populations have increased steadily since 1970. Currently, more than half the population of the United States lives in coastal counties.

Invasion – In the early part of this century, coastal wetlands were drained and used for farming or grazing. More recently, coastal wetlands have been filled or dredged for roads, houses, golf courses, marinas, and other development. In Louisiana, wetlands are being lost to open water due to a combination of factors including canals dredged through the marshes, dams and levees on the Mississippi River reducing sediment to the marshes, sinking land, and sea level rise. Even wetlands that are not actually filled or dredged are becoming degraded due to pollution, changes in water flows, and invasion by non-native plants and animals.

Rising above – In addition, the stress on coastal wetlands is magnified by global effects such as a rise in sea level. Sea level is rising at a rate of a few inches to a foot or more per century. Although that might not seem like much, if the land is fairly flat a rise in sea level of just a few inches can move the coastline hundreds of feet inland. In many places, artificial seawalls keep rising water levels back for a time and coastal wetlands become submerged, eventually dying and eroding away.

How We Protect Coastal Wetlands

NOAA provides technical advice to government agencies and the public on proposed actions that could have a negative effect on living marine resources, including coastal wetlands. Based on extensive scientific and management expertise, NOAA provides recommendations on ways to avoid, minimize, and mitigate the adverse effects of a project. Since many coastal wetlands have been identified as “essential fish habitat,” there is an increased urgency and value in the protection of these areas.

NOAA continues to research the importance of wetlands to fish, the success of coastal wetland restoration efforts, the effects of development on coastal wetlands and their watersheds, trends in coastal wetland loss, and related topics.