Abstract—Almost half of all wetlands in
the 48 contiguous States have been drained since colonial settlement—nearly
85 percent for agricultural use. Public policies that encourage wetland preservation
began to emerge in the 1970s. The United States now appears to be achieving a
goal of "no net loss" due, in part, to the conversion of some agricultural
lands back to wetlands.
Introduction Wetlands today
cover over 7 percent of the nonfederal land area of the 48 States. Most wetlands
occur on forest land, while 15 percent—about 16.6 million acres—occur
on lands associated with crop production and pasture. Despite having a relatively
small portion of total wetland acres, agriculture has played and is likely to
continue to play a significant role in wetland policy (USDA, NRCS, 2004). For
example, much of the past losses in wetlands are attributable to agriculture.
Between 1954 and 2002, 66 percent of total wetland losses (24.2 million acres)
were from converting to agricultural uses. Furthermore, future gains in wetlands
will likely draw from agricultural lands. Between 1974 and 2002, over 50 percent
of all lands converted to wetlands had been in agricultural use. With the continuation
of private and public initiatives to restore wetlands, agricultural lands are
likely to continue to be converted to wetlands because the conversion of agricultural
lands is often less costly than conversion from other uses (like urban ones) (Heimlich
et al., 1998).
Wetlands are a productive medium for forests, provide habitat
for fish and wildlife, preserve water quality(see AREI Chapter 2.2),
reduce flood damage, provide open spaces and recreational sites, and enhance wildlife
diversity (table 2.3.1).
Table 2.3.1 Wetland functions,
services, and values
Wetland
Function
Service
Economic values
Private
values
Forest
Tree growth medium
Commercial
timber harvest
Net economic
value of timber
Fisheries
Fish habitat
Commercial fish harvest
Net economic value of commercial catch
Mixed values
Recreation
Wildlife habitat
Recreational fishing and waterfowl
harvest
Net economic
value of hunting and fishing experience
Public values
Flood
control
Flood retention
Reduced flood flows/peak
Net economic value of reduced damages
Water quality
Water filtration
Cleaner
waters
Net economic value of
reduced damages
Endangered species
Endangered species
Biodiversity
Net option and existence values
Source:
Adapted from Bergstrom and Brazee (1991).
For these reasons, society values
wetlands. However, since most wetland benefits occur offsite, private owners usually
cannot benefit economically from wetlands.
Society's awareness of the value
of wetlands has grown only in the last several decades. Wetlands were once seen
as "wasted" land that should be exploited. When colonists first set
foot in America, there were 221-224 million acres of wetlands in what was to become
the contiguous United States (there were another 170 million acres in Alaska and
Hawaii, not discussed further here). Most of those wetlands were in three regions:
the Midwestern States (27 percent), the Southeastern States (24 percent), and
the Delta and Gulf States (24 percent). As settlement spread, wetlands were converted
for other uses, with the pace increasing as available nonwetlands diminished and
drainage technology improved (Heimlich et al., 1998).
Wetlands Exploitation:
Settlement to 1954
Between the start of European settlement and 1954,
40-44 percent of original wetlands were drained or filled.1
Most of this activity probably occurred after 1885, with as many as 80 million
acres of wetlands and other areas drained by 1930 and, with a slowdown in conversions during
the Depression and World War II, another 10-11 million acres drained between 1930
and 1954 (fig. 2.3.1).
With the explicit encouragement of Federal policies and local cooperative efforts,
wetlands were converted to agricultural and other uses at an average net rate
of 814,000 to 887,000 acres per year between 1885 and 1954.
Almost 30 percent
of net wetland conversion during this period was in the Midwest, 22-24 percent in the Delta
and Gulf region, and 14-16 percent in the Southeast (USDA, ERS, 2000). Data are
insufficient to reveal gross changes from dryland to wetland, but some wetlands
were probably restored or created as lands once converted were abandoned, drainage
failed, and reservoirs or other impoundments saturated formerly dry land.
Moderate
Wetlands Conversion: 1954-74
The pace of net wetland conversion in 1954-74
was about half that of the long-term rate since settlement, dropping to an average
of 458,000 acres per year (fig. 2.3.2).
Gross conversion to agriculture
averaged 593,000 acres per year, while urban development, conversion to other
uses, and water impoundments increased the total to 730,000 acres. Restoration
of dryland and deep water to wetlands averaged 273,000 acres per year, about 1
acre restored for every 3 acres converted.
During this period, drainage
shifted from the Midwest to the Delta and Gulf region (53 percent of all net
conversion) and the Southeast (30 percent) (USDA, ERS, 2000). In the Delta, expansion
for agricultural production in Louisiana, Mississippi, and Arkansas was probably
the largest contributor to wetland conversion, although changes to coastal wetlands
on the Louisiana gulf coast were also significant. In the Southeast, both urban
and agricultural expansion in Florida and North Carolina were contributors. Net
wetland acreage increased slightly in the Central Plains, Prairie
Potholes, and Northeast, due to farmers' abandoning some agricultural land,
increased rainfall expanding wetland area, and farmers' developing ponds and reservoirs
on wetland fringes.
Wetland Policy Transition: 1974-82
Growing
public interest in wetland benefits during the 1970s resulted in Federal policy
changes, such as the Clean Water Act's Section 404 and Executive Order 11990,
which began to reduce wetland conversions. Section 404 (see AREI Chapter 5.7)
established a program to regulate the discharge of dredged and fill material into
waters of the United States, including wetlands. Landowners are required to obtain
a permit from the Army Corps of Engineers to begin work in wetlands. The permit
process involves a public review in which all interested parties can comment on
potential adverse impacts from the proposed wetland conversion (Alvayay and Baen,
1990; USEPA, 1993). Section 404(f) exempts some ongoing activities—including
many farming, ranching, and forestry practices—when wetland impacts are expected
to be minimal.
Executive Order 11990, signed by President Carter in 1977,
directed Federal agencies to minimize the loss and degradation of wetlands and,
instead, to improve the health of wetlands. As a result, the 1974-82 rate of net
wetland conversions dropped by 37 percent, to 290,000 acres per year, despite
higher market prices for crops and greater economic incentives for agricultural
conversion. Gross conversion for agriculture dropped to 235,000 acres per year,
but a large increase in conversions to other uses left total gross conversion
at 446,000 acres (fig. 2.3.2). Over this period, gross increases in wetlands fell
to 156,000 acres per year, with agricultural lands accounting for more than half.
Wetland was converted primarily in the Southeast,
which had more than 60 percent of net conversion in 1974-82, and the Delta and
Gulf region, which had 30 percent (USDA, ERS, 2000). Three-fourths of Southeast
conversions were North Carolina wetlands converted to agricultural land, while
lost wetlands in coastal Louisiana and agricultural conversion in Mississippi
and Texas contributed to net changes in the Delta region.
No Net Loss:
1982-2002 The downward trend in the rate of wetland conversions continued
in 1982-2002 due to several factors: swampbuster (see AREI Chapter 5.3)
provisions of the 1985 Food Security Act, more rigorous enforcement of Section
404 permitting, changes in income tax treatment of conversion investments, additional
State regulations, and falling agricultural prices. The Wetland Reserve Program
(WRP)—authorized in the 1990 Food, Agriculture, and Trade Act—has
further reinforced wetland conservation (see AREI Chapter 5.2).
The WRP provides an easement payment and helps cover wetland restoration costs
for cropland permanently converted back to a wetland.
Furthermore, a policy
goal of "no net loss" of wetlands is also affecting changes in wetland losses, preservation,
and restoration (White House, 1991; 1993). To date, the "no net loss"
goal has been interpreted to mean wetlands should be conserved wherever possible,
and that acres of wetlands converted to other uses must be offset through restoration
and creation of wetlands, maintaining or increasing the wetland resource base
(USDA, NRCS, 1995).
The antecedent of the "no net loss" goal
in Federal wetlands policy was the National Wetland Policy Forum. The Forum's
blue-ribbon panel of environmental, agricultural, business, academic, and government
leaders concluded that "no net loss" was a reasonable goal:
Although calling for a stable and eventually increasing inventory of wetlands,
the goal does not imply that individual wetlands will in every instance be untouchable
or that the "no net loss" standard should be applied on an individual
permit basis—only that the nation's overall wetlands base reach equilibrium
between losses and gains in the short run and increase in the long term. The public
must share with the private sector the cost of restoring and creating wetlands
to achieve this goal (Conservation Foundation, 1988).
Since
initiation of no net loss, wetland area has begun to stabilize at around 134 million
acres (fig. 2.3.1).
In 1982-92, net wetland losses fell to 79,000 acres
per year—about 25 percent of the 1974-82 rate—and fell even further
to 9,300 acres per year in 1992-2002 (fig. 2.3.2).
In 1982-92, wetland
losses due to agriculture—at 31,000 acres per year—were only 20 percent
of total gross conversions. Losses to agriculture fell to 19,000 acres per year
in 1992-2002—about 25 percent of the total losses. In 1982-92, 57 percent
of all wetland losses were due to urban development. The building boom of the
1980s may explain the urban conversion rate of 89,000 acres per year, which is
seven times the 1974-82 rate.
Agriculture's role in wetland restoration
appears to be growing. In 1982-92, agriculture supplied 10 percent (8,000 acres
per year) of the restored wetland acreage. However, in 1992-2002, agriculture's
contribution more than tripled to 28,000 acres per year—40 percent of the
restored acreage.
The Nation may be reaching its goal of no net loss. The most
recent data—1997 to 2002—show a net increase in wetlands of 13,800
acres per year, along with a 45-percent drop in wetland conversions relative to
1992-97.
Beyond "No Net Loss" On Earth Day 2004, the
White
House announced a new national goal—moving beyond "no net loss"
of wetlands to an overall increase in wetlands and wetland quality. Specifically,
the goal is to create, improve, and protect at least 3 million wetland acres over
the next 5 years.
Costs and Benefits of "No Net Loss"
The "no net loss" policy has preserved wetland functions when a wetland
is left unchanged and increased functions when a wetland is restored. Both public
programs (e.g., Water Bank, swampbuster, and Wetland Reserve Program) 2
and private organizations (e.g., the Nature Conservancy and the North American
Wetland Conservation Fund) have successfully secured these benefits. The economic
benefits of a wetland are difficult to measure because the number, type, and
quality of functions vary, as does the number of people affected across wetland
sites. As a result, per-acre values of wetland
benefits range from a few dollars to $300,000 or more (USDA, ERS, 2001a).
Note that the value of a wetland can be high when many people are affected,
even though the value to each individual is relatively low.
The cost of "no
net loss" is the opportunity cost of preserving or restoring a wetland. This
cost equals the amount a firm or individual would pay for the right to convert
a wetland—or the amount a landowner forgoes by not being able to sell the
wetland for an alternative use. Swampbuster provisions (see AREI Chapter 5.3)
limit farmers' ability to convert wetlands for agricultural uses, at an estimated
average opportunity cost of $2,200
per acre—assuming that farmers are unable to sell wetlands for alternative
uses and that swampbuster provisions will not expire (USDA, ERS, 2001b).
In
recent years, the public sector (primarily through the WRP) and private organizations
have purchased development rights to protect wetlands. Purchase costs range
from several dollars per acre for wetlands with little potential for conversion
to hundreds of thousands of dollars for wetlands near urban development (USDA,
ERS, 2001b).
Acquiring rights to and restoring former wetlands can be less
expensive than preserving a wetland. This is especially so when former wetland
sites are marginally suited to economic uses—so that acquisition costs are
low—and relatively easily restored. The acquisition costs associated with
wetland restoration have averaged less than $800
per acre (USDA, ERS, 2001b).
Wetland Acres and Wetland Functions
Net increases in wetland acres do not ensure increases in wetland functions. Functions
lost when a mature wetland is drained can be greater than those gained when a
similar type of wetland is restored. The grassy depressional wetlands of the Northern
Plains—the Prairie Potholes—can reach maturity within 5 years. Conversely,
hardwood wetlands can take 30 years or more to mature. Some restored wetlands
may never provide functions that match those provided before conversion. Reasons
include the impact of historic and current land use activities in the surrounding
landscape, lack of appropriate restoration techniques, landowner preferences for
establishing a wetland subclass other than the one fitting the landscape, and
site modifications to address adjacent landowner concerns with hydrologic restoration
(USDA, NRCS, 2002).
USDA's NRCS initiated a National Wetlands Functional
Assessment Pilot in March 1998. The model used in the pilot addressed the relative
capacity of wetlands to perform various ecosystem functions (see box "Wetland
Functions Tracked in the NRCS Pilot Study").
Wetland Functions Tracked in the NRCS Pilot Study
—Static surface-water storage
—Dynamic surface-water storage —Temporary surface-water storage
—Maintain characteristic static or dynamic storage, soil moisture, and
groundwater interactions —Provide environment for
characteristic plant community —Habitat structure within the wetland
—Habitat interspersion and connectivity among wetlands —Nutrient
cycling —Removal of imported elements and compounds —Retention
of particulates —Organic carbon export.
Source: Adapted from USDA,
NRCS, 2002.
The
models were able to register a modest increase in mean levels of wetland functions
of restored USDA program wetlands versus their former state as drained and cropped.
However, the pilot was not intended as a comprehensive assessment of the functional
condition of USDA conservation program wetlands (USDA, NRCS, 2002). Successes
of the pilot study suggest that continued NRCS research is likely to produce better
models of wetland functions that can aid future policy analyses and program design.
Endnotes 1 Because we are
not certain of the total wetland acreage prior to settlement, we provide range
estimates of probable changes in wetland acres.
2
In 1970, the Water Bank program became the first USDA program designed to temporarily
protect wetlands.
References Alvayay,
J., and J.S. Baen (1990). Wetland Regulation in the Real World. Washington,
DC: Beveridge and Diamond, P.C.
Bergstrom, J., and R. Brazee (1991).
"Benefit Estimation," No Net Loss of Wetlands: What do Agricultural
Economists have to Contribute? R.E. Heimlich (ed.), Staff Report No.
AGES 9149, U.S. Dept. Agr., Econ. Res. Serv.
The Conservation Foundation
(1988). "Protecting America's Wetlands: An Action Agenda," FinalReport of The National Wetlands Policy Forum. Washington, DC.
Smith, R.D., A. Ammann, C. Bartoldus, and
M.M. Brinson (1995). An approach for assessing wetland functions using hydro
geomorphic classification, reference wetlands, and functional indices. Technical
Report WRP-DE-9, U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg,
MS.
U.S. Department of Agriculture, Natural Resources
Conservation Service (1995). Wetlands
Values and Trends. RCA Issue Brief #4, Nov.
U.S. Department of Interior, Fish and Wildlife Service. 2000. "Status and Trends of Wetlands in Conterminous United States 1986 to 1997." by T.E. Dahl, Washington, D.C. 82 pp.
