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Wetlands

Losses in the United States

1780's to 1980's

Executive Summary


In 1989, the Congress directed the Secretary of the Interior to assess the estimated total number of wetland acres as of the 1780's and the 1980's in the areas that now comprise each state. Congress also required an assessment of the estimated percentage of loss of wetlands in each state during this 200-year timespan. This report has been prepared to fulfill those requirements.

In compiling the information in this report, an attempt has been made to present the most reliable data on wetland acreage. Information has been taken from a variety of sources and different types of data sets to generate these acreage estimates. The user is encouraged to refer to the source materials presented documenting acreage estimates for the time frames for each state.

At the time of Colonial America, the area that now constitutes the 50 United States contained an estimated 392 million acres of wetlands. Of this total, 221 million acres were located in the lower 48 states. Another 170 million acres occurred in Alaska. Hawaii contained an estimated 59,000 acres.

Over a period of 200 years, the lower 48 states lost an estimated 53 percent of their original wetlands. Alaska has lost a fraction of one percent while Hawaii has lost an estimated 12 percent of its original wetland areas. On average, this means that the lower 48 states have lost over 60 acres of wetlands for every hour between the 1780's and the 1980's.

The data presented in this report indicate that 22 states have lost 50 percent or more of their original wetlands. California has lost the largest percentage of original wetlands within the state (91%). Florida has lost the most acreage (9.3 million acres). The data presented in this report should be interpreted in context. The estimated percent of wetlands loss for an individual state must be examined in context to the total estimated surface acreage of the state, the 1780's total estimated wetland acreage of the state, and the current 1980's estimated wetland acreage. For instance, the State of California has a total surface area of approximately 101 million acres and it is estimated that in the 1780's California had 5 million acres of wetlands, or approximately 5 percent of California's total acreage was considered wetlands. It is now estimated that California has less than 500,000 wetland acres remaining. This estimate represents a wetlands loss of 91 percent of the 1780's estimated acreage, but also means that currently less than one-half of 1 percent of California's total acreage is wetlands.

Wetland acreage data, by state, has been tabulated for the 200-year timespan.


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