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Wetlands of the United States

Their Extent and Their Value To Waterfowl and Other Wildlife

A Century of Wetland Exploitation

Some understanding of what is likely to happen to the wetlands in the next hundred years can be gained by looking at changes during the past century. Reviewed here are some of the highlights of national legislation affecting the status of wetlands and the results of some previous wetland surveys. Land-use activities resulting in wetland reclamation or modification (principally through drainage) are also evaluated.

SWAMP LAND ACTS OF 1849, 1850, AND 1860

The sentiment in Congress during the middle of the 19th century was that public domain had little value until it became settled, thereby ceasing to be public domain. Wetlands were actually considered a menace and hindrance to land development.

As first passed (1849), the Swamp Land Act granted to Louisiana all swamp and overflow lands then unfit for cultivation, the object being to help in controlling floods in the Mississippi River Valley. In 1850, the act was made applicable to the other 12 public-domain States. In 1860, its provisions were extended to Minnesota and Oregon.

A crane digging a drainage ditch

The original purpose of the grants was to enable the States to reclaim their wetlands by the construction of levees and drains. The States were supposed to carry out a program of reclamation that not only would lessen destruction caused by extensive inundations but also would eliminate mosquito-breeding swamps. As of June 30, 1954, a total of 64,895,415 acres of wetlands had been patented to the 15 States affected (table 1). Minor adjustments are still going on, although it is unlikely that the figure will ever reach 65 million acres. Swamplands never were ceded to the other 19 public-land States.

The 13 original States retained all unsold land within their boundaries when the Federal Government was first organized; Texas retained all its unsold land at the time of annexation. The extensive coastal marshes of these 14 States, therefore, were never owned by the Federal Government.

Table l. -- Acreage granted to States for swamp reclamation
[Action authorized by Swamp Land Acts of 1849, 1850, and 1860]

It would be pointless to trace in detail the use and misuse of lands granted to the 15 States under the Swamp Land Acts. A few examples from Iowa may suffice. In this State the land was turned over to the counties. It was bartered for all sorts of considerations, such as public buildings, bridges, and like purposes foreign to the intent of the acts granting the land. Some counties went beyond this and bargained with immigration companies, selling the land to a company for 25 to 75 cents an acre, with the provision that the company put settlers on the land. In other cases, the land was sold by the county commissioners to themselves for nominal considerations. Other counties gave their wetlands to railroad companies [6].

Of approximately 65 million acres of wetlands given to the States, nearly all are now in private ownership. The landowners can do with them as they wish. It is unfortunate that water-conservation and waterfowl-protection areas were not selected and set aside for public benefit at numerous locations before the lands were transferred from Federal ownership. If this had been the case, the Government would not now be in the position of buying these "wastelands" at high prices.


The first attempt at a national inventory of remaining wetlands was made in 1906. The U. S. Department of Agriculture was requested by the Congress to seek information on the extent, character, and agricultural potentialities of the wetlands of the nation. To supplement and verify existing data on the subject, a questionnaire was sent to one or more persons in each county in States east of the 115th meridian. In his letter requesting the information, the Chief of Irrigation and Drainage Investigations of the Office of Experiment Stations stated:

This office is being called upon by Members of Congress and others interested in the matter for information as to the amount and location of swamp and overflowed lands in the United States that can be reclaimed for agriculture. These frequent inquiries, together with the fact that numerous bills were introduced in both Houses of the last Congress for the drainage of swamp lands, show that the reclamation of these lands is fast becoming a matter of national importance. [17]

Eight of the public-land States in the arid West were excluded from the inventory, as were all coastal lands overflowed daily by tidewater. Obviously, the inventory was not a complete picture of wetlands existing at that time. Rather it was an inventory of wetlands that probably could be easily reclaimed. It was estimated at the time that 79 million acres of swamp and overflowed land could be made fit for profitable agriculture. This was broken down into categories arranged according to agricultural capabilities under existing conditions as follows:

1. Permanently wet and not fit for cultivation, even in
      favorable years, unless cleared or protected
2. Wet pasture for livestock, though forage often of inferior
3. Subject to periodic overflow by streams, but at times
      produce crops
4. Too wet for profitable crops during above-normal rainfall
       periods, but usable during seasons of light or medium

Most drainage projects since that time have reclaimed lands in the last three categories. Although some attempts have been made to drain wetlands in the first category, such projects have generally been the least successful from the agricultural standpoint.

The second inventory of wetlands, conducted in 1922, was recorded in the 1923 Yearbook of Agriculture [5]. It was conducted by the Bureau of Agricultural Economics of the U. S. Department of Agriculture and was based on data furnished by the U. S. Bureau of Public Roads, on soil-survey reports, on topographic maps of the U. S. Geological Survey, on various State reports, and on results of the 1920 census of drainage. This inventory is the most complete nationwide survey of wetlands ever conducted and is the basis, even today, of most reclaimable wetland estimates.

The 1922 inventory showed 91,543,000 acres, of which 7,363,000 acres were listed as tidal marsh and the remainder as inland marsh, swamp, and overflow land. After subtracting 16 million acres of very deep peat and some coastal-marsh areas, the investigators believed that 75 million acres of wetlands would be suitable for crops after drainage. Of this amount, about two-thirds would have to be both drained and cleared of trees or brush (swamps and timbered overflow lands), and one-third required only drainage (herbaceous marshes).

Two recent estimates of wetland acreage appear in publications of the U. S. Department of Agriculture. From a drainage reconnaissance survey, technicians of the Soil Conservation Service estimated that in 1940 there were 97,332,000 acres of "wet, swampy and overflow land outside organized drainage enterprises." [16]

In the latest (1953) U. S. Department of Agriculture publication on the subject, the statement is made:

Our country includes within its boundaries 125 million acres of undeveloped wet and swamp lands which are subject to overflow. With proper drainage and protection, an estimated two-fifths of this area, or 50 million acres, would be physically suitable for crop or pasture use. [15]

The several wetland inventories just referred to are not directly comparable. Acreages granted to the States under the Swamp Land Acts apply to only 15 States. The inventory of 1906 excluded eight States in the West as well as tidewater marshes. The 1922 inventory was the most complete and no doubt represents areas of natural marsh, swamp, and overflow lands which, at that time, had been little changed by drainage or by flood-control projects.

The two recent reconnaissance surveys by the U. S. Department of Agriculture represent many millions of acres not ordinarily thought of as wetlands--such as crop and pasture lands that can be made more productive by removing waterlogged tracts.

It is difficult, therefore, to arrive at reliable figures representing the actual reduction in original wetlands through drainage and flood-control activities since this country first started its agricultural and industrial expansion. Table 2 attempts to do this for seven selected States, where data from three previous wetland summaries and the current inventory by the Fish and Wildlife Service appear comparable. These same States were particularly active with wetland-reclamation projects, inasmuch as they include nearly 40 percent of all land in drainage enterprises today; yet they contain only 16 percent of the land area of the United States.

Table 2 suggests that 17 million acres of original wetlands have been lost in only seven States. The U. S. Department of Agriculture estimates [15] that, in the country as a whole, 45 million acres were reclaimed by a combination of clearing, drainage, and flood control on land in publicly organized drainage and flood-control enterprises. Forty million acres more are listed as reclaimed by drainage and flood protection alone, although admittedly there was considerable duplication in the areas measured. Also, some of this land reported as "improved" for cropland and pasture was probably suited to such purposes before the advent of the reclamation projects. However, it seems reasonably safe to state that at least 45 million acres of our primitive marshes, swamps, and seasonally flooded bottomlands are now devoted to crops, pasture, and other dry-land uses.

Table 2. -- Change in wetland acreage since 1850
Swamplands patented to States since 1850
USDA inventory of 1906
USDA inventory of 1922
Current FWS inventory 1
Percent reduction since 1850 
1Figures in this column do not agree with State-total figures in table 6 because acreages of open-water types are excluded in order to represent coverage similar to the 1850,1906, and 1922 inventories.

The Soil Conservation Service has estimated the original, natural wetlands of this country at 127 million acres. Assuming a minimum loss of 45 million acres, we now have in this country about 82 million acres of land that is too wet for crop or pasture use -- lands on which drainage or flood-control operations so far have had little effect on their original wet condition. This figure corresponds to information gathered during the current inventory by the Fish and Wildlife Service, in which 74.4 million acres were delineated and an estimated 5 to 7 million acres were bypassed.


Spokesmen for the preservation of waterfowl habitat have often turned to acreage figures of drainage enterprises as a good source of information on the loss of waterfowl wetlands. Drainage, it is true, has been and will probably continue to be the greatest single destroyer of duck habitat. However, not all improved land in present drainage enterprises represents former marshes and swamps. Much of it was essentially dry land to begin with. Also, much land now in drainage enterprises is still in its original wet condition.

In 30 States where 50,655,190 acres are listed as "land drained," 12,400,059 acres of this total are classed as unfit for cultivation because of poor drainage. Losses to crops occur frequently on an additional 9,176,046 acres classed as having only fair drainage. Thus, there appear to be good opportunities to preserve and develop waterfowl habitat by working in cooperation with active drainage enterprises which still have vast acreages of natural marshes and swamps within their districts.

In connection with the 1930 census of drainage, which listed a countrywide total of about 84 million acres in organized drainage enterprises, the statement is made that of this amount 31,600,000 acres had been fit to raise a normal crop prior to drainage and 19,100,000 acres fit to raise a partial crop [1]. Thus, more than 50 million of the 84 million acres, or about 60 percent of the land then in organized drainage enterprises, could be classed as "fair" to "good" for agriculture before any drainage improvements were undertaken. Obviously, we cannot use drainage-enterprise figures to show the extent of waterfowl-habitat losses unless we take into account these before-and-after conditions.

More than one-fifth of this country's cropland is in drainage enterprises. Farmers in the humid parts, and in some of the semihumid parts, of the United States (including the two Dakotas) drain to take surplus rainfall off some of their lands. Most of this is gravity drainage, although pumps are sometimes used. In the Western States where irrigation is practiced, drainage is mainly for the purpose of taking seepage water off irrigated lands and carrying away alkali salts.

Figure 1 shows the location and relative abundance of agricultural land in drainage enterprises in 1950. In addition to the acreage depicted there, approximately 50 million acres outside organized districts have been improved by farm drainage [15]. There is no indication of how much of this acreage was essentially dry land before drainage improvements.

Table 3 gives drainage-enterprise statistics for certain years when census figures were available. Forty States now have organized drainage enterprises.1 Because of differences in organization and management, it was necessary in the 1950 census to arbitrarily divide the 40 States into two groups: the 10 "county-drain" States 2 and the 30 "drainage-district" States.

Table 3.-- Growth and condition of land in drainage enterprises for specified years

[In acres. Data from publications by Miller, 1950; U.S. Bureau of the Census, 1950; and Wooten, 1953. See under List of References]
Kind of land
All drainage States:    
    Land in
    Improved land 144,288,00063,514,00067,514,00082,138,000
    Land available for
( 2 )
Thirty drainage-district States:    
    Land in
    Good Drainage
    (no loss of
     cultivated crops)
( 2 )
    Fair drainage
    (frequent loss of
    cultivated crops)
( 2 )
    Poor drainage
    (unfit for     cultivation)
( 2 )
    Land improved or
    reclaimed by
( 2 )
    Land protected     against overflow
( 2 )
    Land improved by
    removal of alkali     or seepage
( 2 )
1Improved lands are regularly tilled or mowed, cleared for pasture, or used for farm sites, ditches, or roads. Much of this land was essentially dry before drainage.
2Not available.

Of the total acreage in the 30 drainage-district States, 31 percent was organized between 1940 and 1949, 7 percent between 1930 and 1939, 14 percent between 1920 and 1929, 33 percent between 1910 and 1919, 10 percent between 1900 and 1909, and 5 percent before 1900.


Agricultural drainage and flood control have doubtless been the greatest destroyers of wetland habitat in the country as a whole, but other factors, operative particularly in coastal marshes, have significantly reduced both the quantity and the quality of wetlands useful to wildlife.

A system of intracoastal canals and connecting waterways to oil fields has eliminated thousands of acres of marshes. Inlets cut to the Atlantic Ocean and the Gulf allow salt water to invade fresh lagoons and marshes, thereby reducing their wildlife value. At low tides, the marshes traversed by these canals suffer from abnormally low water tables, the full effects of which occur during periods of extreme drought. As Cottam and Bourn point out, "Such extremes and not the means in water relations determine ecological trends and wildlife values of a particular marsh area" [4].

Ditches for mosquito control and for production of saltmarsh hay along the Atlantic Coast from Maine to Virginia have affected 90 percent of this region's total original acreage of tidewater marshlands. Such projects remove many of the open-water areas that are of particular value to waterfowl. Shrubby growths of groundselbush and marsh elder largely replace the marshes' natural grass associations, and invertebrate animals that are important food items for waterfowl, shore birds, and fish are drastically reduced [3].

Both coastal marshes and interior marshes and swamps are being dissected by more and more roads that drain or fill wetlands and induce further exploitation of adjacent areas. Expansion of cities, industrial sites, and resorts is often accomplished at the expense of good wetland-wildlife habitat. Wetlands are often filled in to allow development of airports and beach properties; such developments received tremendous impetus immediately after the end of World War II. Some types of pollution also take a toll of wetlands habitat by adversely affecting vegetation. In the case of oil pollution, waterfowl are directly affected.

It must be kept in mind that as human populations continue to expand, the total wetland acreages will become smaller, and the job of preserving and developing wetlands for wildlife will become correspondingly bigger and more expensive. Never before in the Nation's history has it been so necessary to plan for the setting aside of land and water areas to serve the future needs of fish and wildlife, as well as to provide for the recreational needs of people who depend on these resources.

1States with no organized drainage enterprises are the six New England States, Pennsylvania, and West Virginia.
2The county-drain States are Delaware, Indiana, Iowa, Kentucky, Michigan, Minnesota, North Dakota, Ohio, Oklahoma, and South Dakota.
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