WETLANDS LOSS DUE TO AGRICULTURAL CONVERSION:
A SURVEY OF RECENT DATA
February 1990
United States Environmental Protection Agency
Office of Policy, Planning, and Evaluation
Washington, D.C. 20460

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WETLANDS LOSS DUE TO AGRICULTURAL CONVERSION:
A SURVEY OF RECENT DATA
February 1990
U.S. Environmental Protection Agency
Region IU Information Resource
Center (3PM52)
341 Chc-sinai Street
Philadelphia, PA 19107
United States Environmental Protection Agency
Office of Policy, Planning, and Evaluation
Washington, D.C. 20460

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ACKNOWLEDGEMENTS
This document was orepared by the Environmental Law Institute for
the U.S. Environme .ul Protection Agency's Office of Policy, Planning,
and Evaluation under Cooperative Agreement No. CR-815623.
Ken Adler served as EPA Project Manager
ELI staff preparing this report were:
Megan Lewis
Ethan Shenkman
Nicole Veilleux

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TABLE OF CONTENTS
INTRODUCTION 		1
PART I: Agricultural Conversion		3
PART II: Conversion Potential 		13
PART III: Agricultural Indicators 			22
PART IV: Other Indicators 		29
APPENDIX A: Comparison of Wetlands Acreage Studies 		35
APPENDIX B: Bibliography	 	

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LIST OF FIGURES
1.1	Acres of Wetlands Converted Since
December 23, 1985 		5
1.2	Causes of Wetlands Loss:
Mid-1950s to Mid-1970s 		8
1.3	Palustrine Wetlands Lost:
Mid-1950s to Mid-1970s 		9
1.4	Regional Pattern of Wetlands Lost to All
Causes: Mid-1950s to Mid-1970s	- 10
1.5	Percentage of Wetland Loss Due to
Agriculture, By Region: Mid-1950s to
Mid-1970s 		11
2.1	Nonfederal Palustrine Wetlands with High or
Medium Potential for Conversion by Region	 15
2.2	Nonfederal Palustrine Wetlands with High or
Medium Potential for Conversion by State	 16
2.3	Critical Wetland Areas with High or Medium
Potential for Conversion 		17
2.4	Swampbuster Effectiveness for Wetlands
in Selected States 		21
3.1	Season Average Price Received by
Farmers per Bushel 				23
3.2	Acres Planted in the United States		24
3.3	Total Acres Planted in the United States		25
3.4	Projection of Price per Bushel		26
3.5	Projection of Acres Planted - FAPRI 		27
3.6	Projection of Acres Planted - CARD 		28
4.1	Land Drained on U.S. Farms: 1900-1985 	 30
4.2	Uses of Drained Rural Lands: 1982 	 32
4.3	Duck Breeding Populations in North
America: 1955 to 1989 	 33
A. 1	Comparison of Wetlands Acreage Studies 	 35
ii

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LIST OF TABLES
1.1	Food Security Act Progress Report,
October 16, 1989 		6
1.2	Acres of Wetlands Lost to Agricultural, Urban,
and Other Uses: Mid-1950s to Mid-1970s	 7
2.1	Estimated Potentials for Conversion of
Wetlands to Agriculture and the Effort
Required to Convert 		14
2.2	Nonfederal Palustrine Wetlands with High
or Medium Potential for Conversion by Region	 15
2.3	Conversion Potential of Wetlands in Tiner's
Critical Problem Areas 		18
2.4	Estimated Acres of Profitable Wetlands
If Converted for Program Crops 	 19
2.5	Estimated Acres of Profitable Wetlands
in 12 Critical Areas 		20
4.1	Rate of Farmland Drainage in the United
States: 1950-1985 		31
iii

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WETLANDS LOSS DUE TO AGRICULTURAL CONVERSION:
A SURVEY OF RECENT DATA
Introduction
This report surveys currently available sources of data on the conversion of wetlands
to agriculture in the United States. Unfortunately, relatively few sources provide a direct
indication of the rate of conversion or the total number of wetlands converted. The only
complete set of data currently available on the loss of U.S. wetlands to agriculture is the
National Wetlands Inventory (NWI), conducted by the U.S. Fish and Wildlife Service. The
NWI provides statistical estimates of wetland acreage for the lower 48 states between the
mid-1950s and the mid-1970s. The NWI data show that nearly 12 million acres of wetlands
had been converted to agricultural use during that 20-year period (Frayer et al. 1983).
These conversions represented 87 percent of all wetlands lost in that time frame (Tiner
1984). The Office of Technology Assessment analyzed the NWI data and reported that
agricultural conversions accounted for 98 percent of the net losses from all causes suffered
by freshwater wetlands (OTA 1984).
The only source of national data regarding wetlands converted to agriculture since
the mid-1970s is that produced by the U.S. Department of Agriculture's (USDA) Soil Con-
servation Service (SCS) in it$ administration of the Food Security Act of 1985. The data
reported by the SCS include the number and acres of remaining wetlands and converted
wetlands on farms participating in USDA benefit programs. As of October 16, 1989, SCS
had made wetland determinations on a limited number of farms and had identified
approximately 77,000 acres of wetlands converted for agricultural use on these farms since
December 23, 1985. This figure represents an unknown fraction of the total conversions
since 1985 as SCS determinations are not yet complete. The SCS data also do not include
conversions on non-participant farms or lawful conversions pursuant to some exemptions
under the Food Security Act.
In addition to these sources of data on actual conversions, there is information
available on the potential for the conversion of remaining wetlands in the 1982 National
Resources Inventory (NRI), conducted by the SCS. The NRI estimates that of the 78.4
million acres of nonfederal wetlands existing in the United States in 1982, 5.1 million acres
of wetlands have a high or medium potential for conversion and an additional 28 million
acres have a low potential for conversion. The NRI rated a wetland's potential for con-
version based mainly upon the use of similar lands in surrounding areas. Another means
of estimating conversion potential is to look at economic incentives for conversion. One
study estimates that 16 million acres of the wetlands remaining in 1982 would be profitable
if converted at 1985 crop prices (Heimlich 1986). At the end of 1989, the SCS completed
an update of the NRI with data from 1987. These wetlands data, however, have not yet
been analyzed.
1

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Overview
Part One of this report presents the best available sources of data on wetlands losses
due to agricultural conversion. This section includes the SCS determinations of farm
wetland acreage and conversions; the estimates made by the NWI of conversions from the
mid-1950s to the mid-1970s; regional analyses of this aspect of the NWI data; and other
related regional studies.
Pan Two describes the data available regarding the potential for agricultural con-
version of the remaining wetlands in the United States. This section presents various esti-
mates of the percentage of wetlands likely to be converted in the near future. The data
are compiled regionally as well as for critical wetland areas. This section also reviews an
economic analysis of the profitability of agricultural conversion and an analysis of the
effectiveness of Swampbuster sanctions in deterring conversions.
Parts Three and Four examine several types of data that might indicate indirectly
either the extent of recent conversions or the likelihood of future conversions. Part Three
includes a consideration of the recent trends in crop prices and agricultural land use, and
examines projections of future crop prices and demand for farmland. Part Four consid-
ers historical trends in agricultural drainage and reviews recent waterfowl population
inclines and declines.
2

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PART I
AGRICULTURAL CONVERSION
Introduction
The Food Security Act (FSA) Progress Reports, published quarterly by the USD A
Soil Conservation Service (SCS), are the only available sources of data concerning the
conversion of wetlands in the late 1980s. As part of the administration of the
"Swampbuster" program, SCS technicians assess participating farms for the number and
acreage of remaining wetlands and wetlands converted since the inception of the program
in 1985. The SCS assessments are not complete for many states and regions, however, and
do not provide the basis for a reasonable estimate of the total number of recent
conversions. Part One includes a further explanation of the assessment process and a
breakdown of the data from the Progress Report of October 16, 1989.
The only complete source of data on wetlands conversions is the National Wetlands
Inventory (NWT), which covers the period between the mid-1950s and the mid-1970s. Con-
ducted by the U.S. Fish and Wildlife Service, the NWI is intended to provide estimates of
wetland acreage, wetland loss, and causes and rates of wetland loss in the lower 48 states
during that 20-year period (see Appendix A for information on the survey methods and
parameters). TTie Fish and Wildlife Service is required to produce an update of the NWI
data by September 30, 1990, and at 10-year intervals thereafter.
Part One of this report includes the results of the NWI as interpreted and reported
in three major sources. Frayer et al. (1983) reports that a total of 13.6 million acres of
wetlands were lost, of which 11.85 million acres (87 percent of the total losses) were
converted to agriculture. Tiner (1984) reports that an average net loss, due to all causes
of 458,000 acres of wetlands occurred each year in the 20-year period. The Office of
Technology Assessment (OTA 1984) reinterpreted the same data and estimated that
wetlands suffered an annual average net loss of 550,000 acres, 80 percent of which was
attributed to agriculture. OTA further estimated that the rate of wetlands loss has
decreased by approximately 50 percent since 1975. Part One also includes data on the
acute losses of inland, freshwater wetlands (also referred to as palustrine vegetated).
According to the data in Frayer et al. (1983), 99 percent of the 11.85 million acres of
wetlands lost to agriculture were classified as palustrine vegetated.
Finally, Part One reviews several sources of regional information, including OTA's
breakdown of the NWI data into 13 physiogeographic regions. NWI data were designed
to be reliable at the national level only, however, and few comparable statistics exist on the
state or regional level. The final section of Part One cites several sources of regional data,
other than the NWI, which may be referred to for further information.
3

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U.S.DA- FOOD SECURITY ACT PROGRESS REPORTS
The U.S. Department of Agriculture's (USDA) Food Security Act Progress Reports
present the most current data regarding wetlands acreage on agricultural lands and wetlands
converted to agriculture. The USDA collects quarterly reports that document the Soil
Conservation Service's (SCS) determination of the number of wetlands converted since
December 23, 1985; their cumulative acreage; and the number of farms and acres for which
positive wetland and highly erodible land determinations have been made.
Of those lands evaluated as of October 16, 1989, the USDA reports that 6,647,815
acres of wetlands exist on farms, and 77,260 acres of wetlands have been converted to
agriculture since December 23, 1985. It is impossible to estimate from these data the total
number or acres of wetlands converted since 1985 for three reasons. First, the SCS data
accounts for only those farms covered by the Swampbuster Program. Conversions on non-
participant farms are not counted.
Second, the USDA reports that at the present time it is impossible to determine
what percentage of USDA program participant farms have been assessed. Farmers are
allowed to register their lands with the SCS as single farms or in multiple tracts. The SCS
data do not distinguish farms from tracts, making it impossible to determine what percent-
age of farms have been assessed to date.
Third, even if the percentage of program participant farms assessed were known, a
straight-line extrapolation of the wetlands acreage and conversions could not be made
accurately due to a sampling bias. Rather than sampling U.S. farms randomly, the SCS
began by looking at those areas with high potentials for conversion and those farms for
which, during any crop year, the producer indicated on form AD-1026 that he or she
intended to produce crops on "wet areas." Consequently, the completed wetland and
converted wetland determinations do not comprise a representative sample.
4

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FIGURE 1.1
ACRES OF WETLANDS REPORTED CONVERTED SINCE DECEMBER 23, 1985
Converted Well "jnd?
i n a o re
~ 0 to 1000
1001 to 5000
 600 l to 1200':
Based upon data from U.S. Department of Agriculture. (1989). Food Security Act Progress Report of October 16, 1989. Washington.
D.C.: USDA, Soil Conservation Service.
 This map illustrates the acreage of converted wetlands, by state, according to Soil
Conservation Service (SCS) determinations made thus far on program participant
lands. Nationally, a total of 77,260 acres of wetland conversions have been reported,
plus 2,648 acres converted pursuant to the "minimal effects" exemption to the Food
Security Act Swampbuster Program.
	The data illustrated above account only for wetlands on program participant farms
that have been assessed by the SCS since December 23, 1985.
	The data do not account for wetlands on non-program farms; wetlands converted
before December 23, 1985; wetlands converted after December 23, 1985, where the
conversion commenced before that date; or wetlands converted on farms that have
not been assessed.
 Table 1.1 on the following page presents the full set of data on wetland con-
versions from the October 16, 1989, Food Security Act Progress Report. The table
includes the number and acres of program participant farms or tracts with wetlands
that have been assessed in each state to date; the number and acres of wetlands
converted on those farms or tracts since December 1985; the number and acres of
wetlands that were lawfully converted under the "minimal effects" exemption; and
the number of farms or tracts on which no wetlands were found ("negative wetland
determinations").
5

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TABLE 1.1
FOOD SECURITY ACT PROGRESS REPORT, OCTOBER 16, 1989
Farms w/ Wetlands Converted Wetlands Minimal Effect Determ. Nea. wet.
number acres number acres number acres	number
ALABAMA
70
1355
5
57
0
0
609
ALASKA
0
0
0
0
0
0
41
ARIZONA
25
149
0
0
0
0
1418
ARKANSAS
1212
91630
45
1662
2
19
1401
CALIFORNIA
1992
110378
5
840
0
0
6323
COLORADO
1589
55280
11
2245
4
30
9847
CONNECTICUT
401
3249
2
22
0
0
582
DELAWARE
180
1046
2
5
0
0
987
FLORIDA
4390
271628
14
117
0
0
4466
GEORGIA
13271
377604
201
2858
2
29
23531
HAWAII
0
0
0
0
0
0
139
IDAHO
1416
89380
2
18
2
6
4962
ILLINOIS
2253
19036
151
2300
0
0
0
INDIANA
1848
14950
57
323
0
0
1072
IOWA
6923
53990
212
2857
7
104
41577
KANSAS
4946
151501
5
254
0
0
91436
KENTUCKY
1136
28174
104
1989
0
0
4830
LOUISIANA
11008
687540
26
922
0
0
41812
MAINE
432
11891
6
111
0
0
128
MARYLAND
1835
8162
99
6179
0
0
2400
MASSACHUSETTS
258
3099
0
0
0
0
2674
MICHIGAN
14172
292712
214
2087
0
0
13244
MINNESOTA
42586
542771
950
11445
27
970
27573
MISSISSIPPI
2420
214105
45
6943
40
478
1128
MISSOURI
2019
291540
70
2048
31
502
15549
MONTANA
6500
404747
65
3749
0
0
2137
NEBRASKA
2037
16498
37
477
2
13
126
NEVADA
156
56327
4
99
0
0
162
NEW HAMPSHIRE
127
1470
4
27
0
0
497
NEW JERSEY
302
1508
5
181
0
0
42
NEW MEXICO
194
2189
1
454
0
0
7905
NEW YORK
22520
175109
68
1422
5
12
13407
NORTH CAROLINA
3371
111159
258
11625
4
37
9203
NORTH DAKOTA
53186
1780854
155
1018
19
94
11752
OHIO
701
13229
69
1233
1
45
1309
OKLAHOMA
172
4734
2
300
1
20
3775
OREGON
2983
50429
214
3373
0
0
249
PENNSYLVANIA
1582
16963
17
485
0
0
47717
RHODE ISLAND
44
400
0
0
0
0
85
SOUTH CAROLINA
107
1542
5
98
0
0
3639
SOUTH DAKOTA
2512
31809
108
604
18
251
37
TENNESSEE
4515
152261
30
442
0
0
37000
TEXAS
7506
168361
25
676
0
0
80089
UTAH
1158
30545
45
1732
1
23
8944
VERMONT
710
19339
5
67
0
0
1372
VIRGINIA
654
6374
4
115
0
0
8565
WASHINGTON
1892
40330
28
1237
0
0
4939
WEST VIRGINIA
291
1380
17
132
0
0
2733
WISCONSIN
8274
210502
347
2385
5
15
9973
WYOMING
399
28548
4
47
0
0
3554
PUERTO RICO
1
38
0
0
0
0
1
TOTAL
238276
6647815
3743
77260
171
2648
556941
6

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TABLE 1.2
ACRES OF WETLANDS LOST TO
AGRICULTURAL, URBAN, AND OTHER USES:
MID-1950S TO MID-1970S

Acres
Acres

LOSSES
DUE
TQ:


mid-
mid-
Net



Total
Wetland Type
1950s
1970s
Change
Agriculture
Urban
Other
Losses1




(x 1,000 acres)


PALUST. NON-VEG.
2,704.4
4,970.5
+ 2,266.1
125.7
34.7
60.4
220.8
PALUST. VEGETATED
99,818.2
88,765.9
-11,052.3
11,719.9
925.2
617.0
13,262.1
Forested
55,707.4
49,713.4
-5,994.0
6,241.5
372.9
243.9
6,831.3
Scrub-Shrub
10,998.2
10,611.1
-387.1
952.6
128.0
49.5
1,130.1
Emergent
33,112.6
28,441.4
-4,671.2
4,552.8
424.3
323.6
5,300.7
ALL PALUSTRINE
102,522.6
93,736.4
-8,786.2
11,845.6
959.9
677.4
13,482.9
ALL ESTUARINE
5,609.2
5,242.3
-366.9
9.52
127.3
14.9
151.7
TOTAL ESTUARINE &







PALUSTRINE
108,131.8
98,978.7
-9,153.1
11,855.1
1,087.2
6923
13,634.6
Based on National Wetlands Inventory (NWI) data as reported in Frayer et al. (1983). Status and Trends of Wetlands and Deepwater
Habitats. Fort Collins, CO: Colorado State University, Department of Forest and Wood Science*.
	NWI data show that approximately 11.85 million acres of wetlands were converted to
agricultural use betwen the mid-1950s and the mid-1970s. Agricultural conversions represent
87 percent of all wetlands lost in that period. Palustrine vegetated wetlands suffered the
greatest loss to agriculture: 11.7 million acres.
	The average net loss of wetlands each year due to all causes was 458,000 acres (Tiner 1984).
	The Office of Technology Assessment (OTA) reprocessed the NWI data and reported the
results in slightly different form (OTA 1984). OTA considered additional types of wetland
losses, including the conversion of wetlands into deep water, open water, or unconsolidated
shore lands, and therefore arrived at a larger estimate of total losses. OTA also calculated a
net loss figure for each use category. OTA's findings include:
	A total of approximately 14.6 million acres of freshwater (palustrine vegetated)
wetlands were lost during the 20 year period. 80 percent of these losses were attributed
to agricultural use.
	There was a net loss of approximately 11 million acres of freshwater wetlands; 98
percent of the net loss was due to agricultural use.
	There was an average net loss each year of about 550,000 acres of freshwater
wetlands. (Note: OTA estimated that this annual net loss rate was reduced by 50
percent since 1975.)
1	Total losses are mote than net change due to gains in acreage of some types of wetlands over the twenty-year period.
2
This figure has a standard error that makes it about one-half as reliable as any other estimate in this table.

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FIGURE 1.2
CAUSES OF WETLANDS LOSS:
MID-1950S TO MID-1970S
Tiner. Ralph W. (19841 Wetlands of the United States: Current Status and Recent Trends. Newton Comer, MA: U.S. Fish and Wildlife
Service.
	Total wetlands lost were 13.6 million acres (Frayer et al., 1983).
	11.85 million acres of wetlands were converted to agriculture. (Frayer et
al., 1983). Virtually all of these were freshwater wetlands.
8

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FIGURE 1.3
PALUSTRINE WETLANDS LOST:
MID-1950S TO MID-1970S
M
i
1
I
i
o
n
ft
c
p
e
s
0. 0


L^_
62
IZ
| j Lost to Agriculture
Ev3 Lost to Oth#r
SJJTffSS
4.3

	
.V10.61V
0.9
En*rsr*n t
S c PubShrub
PALUSTRINE UETLAND TYPES
Based on National Wetlands Inventory (NWI) data as reported in Frayer et al. (1983). Status and Trends of Wetlands and Deepwater
Habitats. Fort Collins, CO: Colorado State University, Department of Forest and Wood Sciences.
	Of all wetland types, palustrine vegetated wetlands suffered the most signifi-
cant losses due to agriculture: 99 percent of the 11.85 million acres of wet-
lands converted to agriculture were palustrine vegetated. Forested wetlands
made up 53 percent of the palustrine wetland lost to agriculture, followed by
emergent (39%) and scrub-shrub (8%).
	Urban development leads the causes listed as "other."
	The Office of Technology Assessment (OTA 1984), using the NWI data,
found that of all causes, agricultural conversion was the predominant reason
for losses suffered by freshwater wetlands (essentially the same category as
palustrine vegetated). OTA reports that agriculture accounted for 98 percent
of the net losses to all causes of freshwater wetlands.
9

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FIGURE 1.4
REGIONAL PATTERN OF WETLANDS LOST TO ALL CAUSES:
MID-1950S TO MID-1970S
REGION
1-Atlantic	Coastal Zone
2-Gulf	Coastal Zone
3-Atlantic	Coastal Flats
4-Gulf	Coastal Flats
5-Gulf-Atlantic	Rolling
Plain
6-Lower	Mississippi
Alluvial Plain
WETLANDS LOST
TO ALL CAUSES
(x 1000 acres)
84
371
1274
1872
2310
3749
REGION
WETLANDS LOST
TO ALL CAUSES
7-Eastern	Highlands
8-Dakota-Minnesota	Draft
and Lake Bed Flats
9-Upper	Midwest
10-Central
11-Rocky	Mountains
12-Intermontane
13-Pacific	Mountains
(x 1000 acres)
322
816
2286
763
125
685
473
Office of Technology Assessment. (1984). Wetlands: Their Use and Regulation. Washington, D.C: U.S. Congress, OTA.
No OTA-0-206.
Report
	The Office of Technology Assessment (OTA) produced the results of the National
Wetlands Inventory (NWI) for the 13 physiographic regions represented on the map
above. The Lower Mississippi, Gulf-Atlantic, and Upper Midwest regions suffered
the greatest number of acres of freshwater wetlands lost to all causes. Figure 1.5,
on the following page, illustrates the percentage of total losses in each region that
were due to agricultural conversion.
	Problems with regional data: Very large standard errors are associated with NWI
data on a regional level. Furthermore, the geographical subdivisions used by OTA
are based upon similar physical characteristics and not upon land use.
10

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FIGURE 1.5
PERCENTAGE OF WETLAND LOSS DUE TO AGRICULTURE,
BY REGION: MID-1950S TO iVIID-1970s
100 -
1 2 3 4 *> 6 7 8 9 10 11 12 13
REGIONS
Based upon data from Office of Technology. (1984). Wetlands: Their Ute and Regulation. Washington, D.C: U.S. Congress, OTA.
Report No. OTA-O-206.
	This graph presents the percentages of wetlands acres in each region lost
to all causes that were used for agriculture. The Office of Technology
Assessment (OTA) used National Wetlands Inventory data for its study.1
	The actual losses of freshwater vegetated wetlands to agriculture range
from 1 to 90 percent of total losses in the 13 regions. However, agriculture
was the greatest cause of loss of freshwater vegetated wetlands in every
region. The percentage of losses to all causes attributed to agricultural
conversion was greater than the national average listed by OTA as 80
percent (see p. 7) in six regions.
For actual region names see Figure 1.4.
11

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OTHER REGIONAL STUDIES OF WETLANDS LOSS
DUE TO AGRICULTURAL CONVERSION
	Goldman-Carter, Janice, et al. (1989). Statement of the National Wildlife Federation
Before the House Committee on Agriculture, July 13, 1989.
This testimony provides a useful overview of several sources of data pertaining to
wetland trends in the six critical wetland areas, identified in Tiner (1984), where agricultural
conversion is a major threat.
	Goldstein, Jon. (19881. The Impact of Federal Programs on Wetlands. Volume One:
The Lower Mississippi Alluvial Plain and the Prairie Pothole Region. Washington,
D.C.: U.S. Department of the Interior.
Includes a detailed analysis of wetland trends, including agricultural conversions and
the effect of federal programs, in the Lower Mississippi Alluvial Plain and the Prairie
Pothole Region.
	Office of Technology Assessment. (1984). Wetlands: Their Use and Regulation.
Washington, D.C.: U.S. Congress, OTA. Report No. OTA-O-206.
This report includes information from 10 case studies. It discusses wetland trends,
including conversions to agriculture, in 21 states. The case studies drew from a limited
number of local sources of wetland trend information (other than the NWI); general data
compiled by Section 404 or state permit programs, where available; and a variety of
interviews.
	Tiner, Ralph W. (1987). Mid-Atlantic Wetlands: A Disappearing Natural Treasure.
Newton Corner, MA: U.S. Fish and Wildlife Service.
This document contains information on the percentage of wetlands lost to agriculture
in Delaware, Maryland, Pennsylvania, Virginia, West Virginia, and the Chesapeake Bay
Watershed. The data were drawn from the National Wetlands Inventory (NWI) which
estimated changes in wetland acreage between the mid-1950s and the mid-1970s.
	Tiner, Ralph W. (1984). Wetlands of the United States: Current Status and Recent
Trends. Newton Comer, MA: U.S. Fish and Wildlife Service.
In addition to summarizing the national data produced by the NWQ, this report cites
26 state or regional studies (pp. 34-35) conducted between 1976 and 1983 that estimate
percentages of wetlands lost to agricultural conversions and other causes. It also discusses
recent wetland trends in the nine critical wetland areas that are identified by Tiner. These
areas and their threatened wetland types are: 1) estuarine wetlands of the U.S. coastal
zone, 2) Louisiana's coastal marshes, 3) Chesapeake Bay's submerged aquatic beds, 4) South
Florida's palustrine wetlands, 5) the Prairie Pothole Region's emergent wetlands, 6)
wetlands of the Nebraska Sandhills and Rainwater Basin, 7) forested wetlands of the Lower
Mississippi Alluvial Plain, 8) North Carolina's pocosins, and 9) western riparian wetlands.
12

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PART II
CONVERSION POTENTIAL
Although the Soil Conservation Service's (SCS) 1982 National Resources Inventory
(NRI) does not contain information on wetland losses due to agriculture, it does provide
estimates of the potential for remaining nonfederal wetlands to be converted in the near
future. The NRI estimated that, as of 1982, there were approximately 78.4 million acres
of nonfederal wetlands remaining in the conterminous United Stated, Hawaii, and Puerto
Rico (for an explanation of the study methods and parameters, see Appendix A). SCS tech-
nicians rated the inventoried lands' potentials for conversion to cropland within the next
10-15 years and the type of effort required for conversion. The potential for conversion was
rated as "zero," "unlikely," "medium," or "high," according to land use trends in the region.
"High potential," for example, means that "similar land has been converted to cropland
during the last three years." (For further information on the inventory methodology, see
Instructions for the SCS-Multiresource Inventory 1981-82. USDA Soil Conservation Service,
May 1980.)
Of the lands rated by SCS technicians as having a high or medium potential for
conversion to cropland, 5.1 million acres were wetlands (Figure 2.1). About 85 percent (4.3
million acres) of the high and medium potential wetlands could be brought into production
with little or no effort on the farm. Slightly more than 3 million of the 4.3 million acres
would require drainage. The remaining 15 percent (.8 million acres) would require action
by several farms or a special district. An additional 28 million acres of wetlands had a low
potential for conversion (rated as "unlikely"). The reports surveyed in this section analyze
NRI estimates of the conversion potentials of U.S. wetlands nationally, regionally, and for
critical wetland areas. The 14 critical areas where agricultural conversion is a primary
threat contain over 80 percent of all the wetland areas rated by the NRI as having a high
or medium cropland potential (Figure 2.3 and Table 2.3).
One source not reviewed in this section (Pavelis 1987) analyzed the NRI data and
reported a lower estimate of 2.5 million acres of wetlands with a high or medium potential
for conversion. Pavelis' estimate is lower than the 5.1 million acre estimate mentioned
above partially because Pavelis limits his analysis to privately owned, partially vegetated
palustrine wetlands not currently cropped or grazed (Pavelis therefore excludes about 35
million acres of wetlands from his analysis, including almost 13 million acres owned by state
or local governments).
While the NRI estimates the conversion potentials of wetlands based mainly on
physical characteristics, other studies based upon economic incentives have arrived at higher
estimates of the number of wetlands likely to be converted. One study surveyed here
(Heimlich and Langner, July-August 1986) estimates that approximately 16 million acres of
remaining nonfederal wetlands would have been profitable if planted at 1985 commodity
prices (Table 2.4). This section of the report also presents the results of one study
(Heimlich 1989) which estimates that of about 17 million acres of wetlands with some
potential for conversion, only about 6 million acres are likely to be protected by
Swampbuster sanctions (Figure 2.4).
13

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TABLE 2.1
ESTIMATED POTENTIALS FOR CONVERSION OF WETLANDS1
TO AGRICULTURE AND THE EFFORT REQUIRED TO CONVERT
(Million Acres)
Not
Conversion
No
On-farm
Multifarm
appli-

Potential
effort
effort
or Droiect2
cable
Total
High or medium
0.5
3.8
0.7
*
5.1
Unlikely
0.8
16.0
9.4
1.9
28.0
Zero
0.3
4.3
4.8
8.9
18.3
Other
0
0
0
19.2
19.2
Total3
1.6
24.1
14.9
30.0
. 70.7
Based on data from the 1982 National Resources Inventory as reported in Heimlich, Ralph E, and Linda L. Langner (1986).
Swampbusting Wetlands Conversion and Farm Programs. Washington, D.G. U.S. Department of Agriculture, Economic Research Service
* Fewer than 100,000 acres
	Palustrine wetlands are the wetland type most frequently converted to agriculture
(see Figure 1.3). Of the 70.7 million acres of nonfederal palustrine wetlands existing
in the U.S. in 1982, only 5.1 million acres (7%) were rated by SCS technicians as
having "high or medium" potential for conversion; 19.2 million (27%) were already
in cropland or in an irreversible use ("other"); 18.3 million (26%) were rated as
having "zero" potential for conversion; and 28.0 million (40%) were considered
"unlikely" to be converted soon.
	Almost 85 percent (4.3 million acres) of high- and medium-potential palustrine
wetlands could be brought into production with no effort or with minor work on the
farm (columns labeled "No effort" and On-farm effort"). Heimlich and Langner also
report that slightly more than 3 million of the 4.3 million acres would require some
form of drainage.
	Those wetland acres with a high- or medium-potential for conversion are further
broken down in the study cited according to the reason preventing their conversion:
about 78 percent of the 5.1 million acres are too wet; 10 percent have restrictive soil
conditions, such as low fertility, high erosion potential, alkalinity, salinity, or
restrictive root zones; and 12 percent have no reasons preventing their conversion.
Includes only nonfederal palustrine wetlands.
Conversion requires action by several farms or a special district.
Detail may not add to totals due to rounding.
14

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NONFEDERAL PALUSTRINE WETLANDS WITH
HIGH OR MEDIUM POTENTIAL FOR CONVERSION BY REGION
FIGURE 2.1
 The USDA Second RCA Appraisal (1987) contains wetlands data from the 1982
National Resources Inventory (NRI) broken down into the above regions. The table below
lists, by region, the total palustrine wetlands acreage, along with the acreage of palustrine
wetlands rated by the NRI as having a medium or high potential for conversion to
agriculture in the near future.
TABLE 22

Total
Wetlands with High
Percent of Total

Palustrine Wetlands
or Medium Potential
Palustrine Wetlands

Acres fxlOOOl
Acres CxlOOOt
in the Remon
Northeast
7,571
469
6
Appalachia
5,077
567
11
Southeast
18,416
1,288
7
Lake States
16,783
742
4
Com Belt
2,180
371
17
Delta States
7,381
546
7
Northern Plains
5,489
553
10
Southern Plains
2,578
124
5
Mountain
2.841
205
7
Pacific
2334
320
14
Total
7050
5.18S
7
Based on U.S. Deoartnient of Asnculture. (19871. The Second RCA Aooraisal: Soil. Water, and Related Resources
on Nonfederal Land
in the United States.
Analysis of Condition and Trends.
Washington, D.C.: USDA, Soil
Conservation Service.


15

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FIGURE 2.2
NONFEDERAL PALUSTRINE WETLANDS WITH
HIGH OR MEDIUM POTENTIAL FOR CONVERSION BY STATE
Heimlich, Ralph E, and Linda L. Langner. (1986). Swamobusting Wetlands Conversion and Farm Program*. Washington. D.C.: U.S.
Department of Agriculture, Economic Research Service.
	This map illustrates the state-by-state distribution of nonfederal palustrine wetlands
that were determined to have high or medium potential for conversion to agriculture
by the 1982 National Resources Inventory (NRI).
	Many areas that had large losses of wetlands due to agricultural conversion during
the 1960s and 1970s have relatively few remaining wetlands with high or medium
cropland potential. Louisiana and Arkansas, for example, have only 144,000 and
121,000 acres of potentially convertible bottomlands, respectively, a fraction of the
1.7 million acres that each state lost between the mid-1950s and the mid-1970s.
Conversely, Alabama and North Dakota had small or no net losses of wetlands
between the mid-1950s and mid-1970s and had 401,000 and 298,000 of high and
medium potential wetlands remaining in 1982. Florida and Minnesota had relatively
high losses through the 1970s and still have more than 500,000 acres of wetlands with
high or medium cropland potential.
16

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FIGURE 2.3
CRITICAL WETLAND AREAS WITH
HIGH OR MEDIUM POTENTIAL FOR CONVERSION
9	Kentucky Tennessee
9	Appaiacftia Southern Piedmont
'0	Southern Coutai Ptam
' 1	HuCWi Atver vly
<2	Northern Minnesota
13	Washington Oregon
Heimlich. Ralph E.. and Linda L. Langner. (1986). Swamobustinr Wetlands Conversion and Farm Programs. Washington, D.C.. U S.
Department of Agriculture. Economic Research Service.
	This map represents 14 wetland areas where agricultural conversion is a primary
threat. Areas one through six (clear on the map) are wetland areas identified in
Tiner (1984). Heimlich and Langner matched Tiner's six problem areas as closely
as possible with Major Land Resource Areas (MLRA's) in order to determine how
many wetland areas with high or medium conversion potential fell into those six
areas. The remaining eight regions (shaded on the map) are identified by Heimlich
and Langner and represent all other MLRA's with substantial wetlands of high and
medium potential for conversion.
	Taken together, these 14 wetland areas contain 57 percent of nonfederal wetland
acres and 82 percent of all wetlands with high conversion potential (for data, see
Table 2.3).
17

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TABLE 2.3


CONVERSION POTENTIAL OF WETLANDS
IN TINER S CRITICAL PROBLEM AREAS
(xl,000 acres)




High
Medium
Unlikelv
Other
Total
1.
South Florida
62
321
1,566
1,455
4,470
2.
Prairie Pothole
98
472
1,540
2,103
4,888
3.
Nebraska Sandhills
and Rainwater Basin 26
105
479
173
859
4.
Lower Mississippi
96
302
302
1,724
1,415
5.
Coastal Pocosins
18
271
2,578
3,183
7,754
6.
Western Riparian
2
33
166
1,125
1,441

SUBTOTAL
302
1,504
8,053
9,454
23,676

CONVERSION
POTENTIAL OF WETLANDS IN OTHER PROBLEM AREAS
(x 1,000 acres)



High
Medium
Unlikelv
Othfr
Total
7.
Cora Belt States
63
169
500
556
1,471
8.
Kentucky/T ennessee
49
86
163
181
551
9.
Appalachia/Southern
Piedmont
57
228
1,073
139
1,810
10.
Southern Coastal Plain 123
509
4,762
11,080
9,328
11.
Hudson River Valley
9
30
472
480
1,317
12.
Northern Minnesota
13
52
644
1,728
3,449
13.
Washington/Oregon
19
55
121
84
335
14.
Lake States
32
138
1,418
378
2^20

SUBTOTAL
365
1,267
9,153
4,626
20,781

TOTAL-CRITICAL
AREAS
TOTAL-
NONFEDERAL
PERCENT OF
667
813
82%
2,771
4,371
63%
17,206
28,467
60%
14,080
25,986
54%
44,457
78,384
57%
NONFEDERAL
Based on data from the 1982 National Resources Inventory as reported in Heimlich, Ralph E., and Linda L Langner. (1986).
Swampbusting Wetlands Conversion and Farm Programs. Washington, D.C.: U.S. Department of Agriculture, Economic Research
Service.
18

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TABLE 2.4
ESTIMATED ACRES OF PROFITABLE WETLANDS,
IF CONVERTED FOR PROGRAM CROPS
Short-Run
Season-average
Target
1985 Program
Returns at:
Prices
Prices
Participation1


(Million acres)

Positive
13.8
22.7
15.9
Negative
25.1
16.2
23.0
Without Yields
39.5
39.5
39.5
TOTAL NONFEDERAL


WETLAND ACRES
78.4
78.4
78.4
Heimlich. Ralph E, and Linda L Langner. (July/August, 1986). 'Swampbusung in Perspective." Journal of Soil and Water Conservation.
Volume 41, No. 4.
	This study estimates the number of acres of nonfederal wetlands remaining in the
United States (reported in the 1982 National Resources Inventory (NRI)) that would
have earned positive, negative, or zero short-run returns in 1985 if converted for
the production of program crops. The calculations were based on 1985 commodity
prices. The study concludes that about 16 million acres of wetlands remaining in
1982 would have earned positive, short-run returns if converted at 1985 program
participation rates.
	Short-run returns were considered "positive" if estimated crop yields multiplied
by crop prices were greater than production costs. Estimated crop yields were
obtained from the Soil Conservation Service's (SCS) Soil Interpretation Data (SOILS
5) for each point inventoried by the 1982 NRI. Estimated production costs were
derived from crop budgets supplied by the Federal Enterprise Data System and
direct costs of clearing and drainage supplied by SCS.
	This study does not account for many of the factors considered by the 1982 NRI
to limit potential productivity, such as an area's size, accessibility, and ownership.
The NRI estimated 5.1 million acres of wetlands to have a high or medium potential
for conversion and 28 million acres to have a low potential for conversion, (see
Figure 2.1).
Profitable acres at season-average and target prices weighted by state program participation rates.
19

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TABLE 2.5
ESTIMATED ACRES OF PROFITABLE
WETLANDS IN 12 CRITICAL AREAS
Acres of Wetlands with Positive,
Short-run Returns if Converted at:
Season-Average	Target
Area	Prices	Prices
1,000 Acres
1.
South Florida



Palustrine Wetlands
0
29
2.
Prairie Potholes
64
47
3.
Nebraska Sandhills and



Rainwater Basin
142
143
4.
Lower Mississippi



Alluvial Plain
1,889
3,792
5.
Coastal Pocosins
635
2,740
6.
Western Riparian
0
22

SUBTOTAL (1-6)
2,730
6,771
7.
Corn Belt
290
409
8.
Kentucky/Tennessee
106
160
9.
Appalachia/Southern



Piedmont
829
1,258
10.
Southern Coastal Plain
4,392
7,086
11.
Washington/Oregon
50
61
12.
Lake States
29
315

SUBTOTAL (7-12)
6,236
9,289
Heimlich. Ralph E, and Linda L Langner. (July/August, 1986). "Swampbusting in Perspective." Journal of Soil and Water Conservation.
Volume 41, No. 4.
	This study estimates the number of acres of wetlands in each of 12 critical
wetland areas that would earn positive short-run returns if converted for the
production of program crops. The first group consists of six critical wetland areas
identified by Tiner (1984) where agricultural conversion is considered a major threat.
The second group consists of six critical wetland regions identified by Heimlich and
Langner (see map in Figure 2.3).
	These 12 critical areas contain about 70 percent of the total U.S. wetlands
estimated to be profitable if converted at target prices, and about 65 percent of the
total U.S. wetlands estimated to be profitable if converted at season-acreage prices
(for national data, see Table 2.4).
20

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FIGURE 2.4
SWAMPBUSTER EFFECTIVENESS FOR
WETLANDS IN SELECTED STATES1
Heimlich. Ralph E (1989). "The Swampbuster Provision: An A Prion Evaluation of Effectiveness." Wetlands: Concerns and Successes.
American Water Resources Association.
	Heimlich analyzes wetland location and likelihood of conversion to cropland
(based on data from the 1982 NRI) in relation to the profitability of local agriculture
and its dependence on agricultural program payments. This analysis assumes that
Swampbuster is fully implemented and that commodity prices will remain relatively
constant over the next several years.
	Of the 78.4 million acres of nonfederal wetlands remaining in the U.S. in 1982,
Heimlich estimates that about 17 million acres have some probability of being con-
verted to cropland. Of these acres, he estimates that the Swampbuster provisions
will likely retard the conversion of only about 6 million ("Effective" plus "Moderately
Effective"). The remaining 11 million acres probably will not be affected by Swamp-
buster ("Moderately Ineffective" plus "Ineffective") either because crops grown in
those areas are not subject to government programs and/or because farm operators
do not depend on government payments to a significant extent.
	This study produced data for 19 selected states on the estimated effectiveness of
Swampbuster provisions in retarding the conversion of vulnerable wetlands.
Swampbuster is predicted to be least effective in Florida, central Alabama, the
Atlantic Coastal Plain, Wisconsin and Upper Michigan, part of the Klamath Basin,
and coastal Massachussets and Maine.
The data presented in this table accounts only for the 17 million acres of wetlands considered by Heimlich to have some
probability of conversion to agriculture.
21

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PART III
AGRICULTURAL INDICATORS
Agricultural land use trends may indicate, whether the conversion of wetlands to
agriculture can be expected to increase or decrease in the short term. This section contains
data on crop prices and planted acres from 1973 to the present, as well as data on projected
agricultural trends. Due to the magnitude of factors influencing both crop prices and a pro-
ducer's decision regarding each year's planted acres, however, any conclusions drawn about
wetland conversion from these isolated components must be tentative.
Current
Based only upoa the historical data provided in this section, current pressures to
convert wetlands do not appear to be severe. In comparison to annual averages since the
early 1970s, the recent seasonal average prices per bushel received by farmers for wheat,
corn, and soy have generally been in decline, despite a modest rise in 1987 (Figure 3.1).
The amount of acres planted in 1987 and 1988 for all three crops are also well below the
historic trend (Figures 3.2,3.3). The decrease in both prices and acres planted may indicate
that current pressure to convert wetlands to agricultural land is lower than in the past.
Short Term
When observing short term trends in acres planted, an important factor to consider
is the Conservation Reserve Program (CRP). The aggregate farmland currently idled bv
the CRP accounts for approximately 28 million acres to date. Land enrolled in the CRP
accounts for some, but not all, of the decline in planted acreage (Figure 3.3). It is
reasonable to expect that the relative pressure to convert wetlands will increase in the short
term as acreage is idled by the CRP.
Forecasting data indicate both a modest rise in corn, wheat, and soy prices over the
1987/88 projections (Figure 3.4) and a substantial rise in the number of acres planted for
corn and wheat within the next decade (Figure 3.5). If prices and planted acreage increase
during the near term as forecast, the ensuing demand for cropland acreage, coupled with
the abundance of land currently restricted under the CRP, may intensify the pressure to
convert wetlands to agriculture during the early and mid-1990s. Some relief can be
expected, however, during the late 1990s when CRP contracts expire and currently idled
land is again available for production.
Long Term
Projections drawn from the Center for Agricultural and Rural Development (CARD)
model, estimating the planted acres of soy, wheat, and corn for the years 1990, 2000, and
2030, indicate a substantial rise in acreage planted for soy and wheat between 2000 and
2030 (Figure 3.6). If this expected increase occurs, those wetlands easily and inexpensively
converted to agriculture for these crops may become threatened.
22

-------
FIGURE 3.1
SEASON AVERAGE PRICE RECEIVED
BY FARMERS PER BUSHEL1
n
u
13
1 >
i i
10
9
8
7
6
5
4
3
2
1
0
13 36
12 3-v
12 03
10 54
90
10
9\16
g \y
8 64
- 8:3
7.38
5 53
155 1-3
1973	1975	1977	1979	1981	1983 i 1985	1987
1974	1976	1978	1980	1982	1984	1986
YEAR
3 WHEAT * CORN o SOY
United States Department of Agriculture, f 19881. Agricultural Statistic* 1988. Washington, D.C: USDA, National Agricultural Statistics
Service. (Figures for 1987 are preliminary).
 The prices for all three crops have been on a strong downward trend since
1974 and appear to be at their lowest during the late 1980s. If this trend
continues, it appears that demand for additional cropland will not be rising
greatly in the near future. Estimates concerning price projections into the
future are in Figure 3.4.
Prices given have been adjusted for inflation and are in terms of 1986 dollars. All prices include allowance for loans outstanding
and purchases by the government valued at the average loan and purchase rate, by States, where applicable.
23

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FIGURE 3.2
ACRES PLANTED IN THE UNITED STATES1
95
90
00
75
70 r
65 -
60
\	i
9 \\ / A
\
v<
\V/
y

" r
50
1973 i 1975 i 1977 ' 1979 i 1901 1983 i 1985 j 1987
1974 1976 1978 1980 1982 1984 1986 1988
Q WHEAT
YEAR
CORN
SOY
Compilations from United States Department of Agriculture. (1980-1988). Crop Production. Annual Reports. Washington. D C.
National Agricultural Statistics Service.
 The number of acres planted seems to have been on a downward trend
since the mid-1980s. Except for the extreme swing in acres planted for corn
in 1983, the number of acres planted for all the crops in 1988 is approxi-
mately equal to the amount planted in 1973. Correlating this Figure with the
decline in prices shown in Figure 3.1, the apparent trend that demand for new
cropland in the future will be decreasing appears to be reinforced. Estimates
concerning acreage projections into the future are in Figures 3.5 and 3.6.
Figures were obtained by the USDA from yield surveys, including mailed reports from farmers for all crop6 and actual field
observations and measurements for corn, soybeans, and wheat.
24

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FIGURE 3.3
TOTAL ACRES PLANTED IN THE UNITED STATES1
250 r-
n
z
240
;jo -
220 r
210
200
190
9239.1
234 8
. 3
224.2
/
18s*?
yi5.3
^08 3
212 4
201 3
/
/
186 0
200 4
180
1973 I 1975 I 1977 | 1979 I 1981 ! 1983 | 1985 I 1987 |
1974 1976 1978 1980 1982 1984 1986 1988
YEAR
~ ACRES PLANTED
PLUS CRP LANDS
Data regarding planted acres compiled from: United States Department-of Agriculture. (198
-------
FIGURE 3.4
PROJECTION OF PRICE PER BUSHEL
ta 	
7 56
$7 -
i
11 '	:	1	1	1	1	1	1		
87/88	88/89	89/90	90/91	91/92	92/93	93/97
YFjvR
Q WHEAT	CORN	SOY
Food and Agricultural Policy Research Institute. (1989). U.S. and World Agricultural Outlook: Summary and Tables. Iowa State
University, University of Missouri-Columbia.
	The Food and Agricultural Policy Research Institute (FAPRI) projections
assume that the Food Security Act of 1985, as amended, will remain in effect
until it expires in 1990, and that the new farm bill will hold target prices
constant at the 1990 level.
	In contrast to the downward trend in crop prices shown in Figure 3.1,
FAPRI predicts an increase in prices for all three crops to around 1983-1984
prices by the end of the 1990s. Such a rise may indicate an increase in
demand for these crops and an increase in cropland planted in the 1990s.
Estimates concerning acreage projections into the future are in Figure 3.5 and
3.6.
26

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FIGURE 3.5
PROJECTION OF ACRES PLANTED - FAPRI
65 8
64
07/88
65 5
88/89
89/90	90/91
YEAR
91/92
92/93
CORN o SOY
63 2
93/97
~ WHEAT
Food and Agricultural Policy Research Institute (1989). U.S. and World Agricultural Outlook: Summary and Tables. Iowa State
University, University of Missouri-Columbia.
	The Food and Agricultural Policy Research Institute (FAPRI) projections
assume that the Food Security Act (FSA) of 1985, as amended, will remain
in effect until it expires in 1990, a&d that the new farm bill will hold target
prices constant at the 1990 level.
	According to FAPRI, the acreage planted to major U.S. crops has been
declining since the implementation of the FSA due to the large amount of
acreage idled by government programs. As the acreage reduction program
(ARP) is cut back in response to the 1988 drought, planted acreage is
expected to increase by more than 20 million acres in 1989/90, and to remain
fairly stable at that level for the next few years. Growth in planted acreage
is expected to resume in the latter half of the decade, as export-led price
increases bring more land into production.
	Considering the projected increase in acres shown here and the projected
price increase shown in Figure 3.4, the demand for cropland may rise in the
near future. For long-term predictions concerning acreage, see Figure 3.6.
Higher prices and the reduction in the ARP rate from 27-5 percent to 10 percent is projected to result in a 10 million acre
increase in wheat plantings in 1989/90, to 75 million acres. For 1990/91 and beyond, the ARP rate is assumed to be 5 percent, and
wheat planted area fluctuates at about 78-80 million acres.
27

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FIGURE 3.6
PROJECTION OF ACRES PLANTED - CARD1
?3 ~
- 70 2:
1982
1990
2000
2030
YEAR
WHEAT	CORN o SOY
United States Department of Agriculture. (1987). The Second RCA Appraisal: Soil. Water, and Related Resources on Nonfederal Land
in the United States. Analysis of Condition artd Trends. Review Draft. Washington, D.C.. USDA. Soil Conservation Service. Reprinted
in U.S. Environmental Protection Agency. (1989). Natural Resources for the 21st Century An Evaluation of the Effects of Land Use
on Environmental Quality. Washington, D C.: EPA, Office of Policy Planning & Evaluation.
 The projections, based upon figures from the USDA, are drawn from the
Center for Agricultural and Rural Development (CARD) model. Used pri-
marily to determine whether the United States has adequate resources to
provide for future agricultural demands, the CARD model uses linear pro-
gramming to project cropland required, acreage planted by crop, and crop
production for the United States to the year 2030.
The projections are determined by estimating the minimum costs of production subject to three constraints: linear descriptions
of production functions, resource availability, and demand for food and fiber commodities. The demand estimates are supplied by the
Department of Commerce, Bureau of Economic Analysis (domestic demand), and by the USDA Economic Research Service (export
demand). The CARD model produces a 'most likely situation' scenario that is characterized by moderate growth in exports and in
productivity.
28

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PART IV
OTHER INDICATORS: TRENDS IN FARM DRAINAGE AND
WATERFOWL POPULATION
Farm Drainage
By 1985, farmers had drained nearly 110 million acres of land in the United States
(Figure 4.1). Although the rate of drainage has slowed since the 1950s, the number of acres
drained was still significant in the early 1980s, averaging over 600,000 acres per year (Table
4.1). Such drainage does not necessarily indicate drainage of wetlands, however, because
not all wet soils are classified as wetlands. For instance, on nonfederal lands, the 1982
National Resources Inventory found 78 million acres of wetlands and a total of 126 million
acres of undrained wet soils (Pavelis 1987). Therefore, there must be at least 48 million
acres of undrained wet soils on these lands that are not counted as wetlands.
Trends in farmland drainage may provide an indirect indication of trends in wetland
drainage. The Office of Technology Assessment (OTA 1984), for instance, estimated the
rate of wetland conversions from 1975 to 1980 based upon the percentage of surface-
drained farmlands that were wetlands in the two decades prior to 1975. This section of the
report includes OTA's findings, as well as an estimate of the rate of wetland conversions
from 1975 to 1985 based upon more recent drainage data. National trends in farmland
drainage must be interpreted with caution, however, as intensive drainage in certain states
and regions may continue even as the national rate declines.
It is also important to note that more than 70 percent of the farmland drained in the
nation is used for crops (other uses include pastureland, rangeland, and forestland; see
Table 4.2). Furthermore, in the 23 states that use drainage extensively, an average of 25
percent of the cropland consisted of drained wet soils in 1985 (Pavelis 1987). Future
demand for expanded cropland acreage, therefore, may be followed by an increase in
drainage and an accompanying increase in pressure for wetland conversion.
Waterfowl Populations
Migrating waterfowl populations depend upon wetland areas for nesting, resting, and
breeding in many agricultural regions, such as the prairie pothole area in the north-central
United States. To the extent that fluctuations in waterfowl population figures reflect either
the scarcity or abundance of wetland habitat, increases or declines in waterfowl populations
may be an indirect indicator of trends in the agricultural conversion of wetlands.
Figure 4.2 represents fluctuations in duck breeding populations in North America
from 1955 to 1989. The population in the mid to late 1980s was the lowest in 20 years and
significantly less than the cumulative average for the 44 year period. The recent downward
trend may be attributed to many factors, including loss of wetland habitat, drought, and
other unfavorable conditions.
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FIGURE 4.1
LAND DRAINED ON U.S. FARMS: 1900-19851

1900	I 9~0	1940	1960	1980
Year
Surface Drainage - Subsurface Drainage - Total Land Drained
Adapted from Pavelis. George A., ed. (1987). Farm Drainage in the United States: History. Status, and Prospects. Washington. D C.
U S. Department of Agriculture, Economic Research Service.
	Although the rate of farmland drainage in the U.S. has been greatly reduced over
the past 40 years, farmland continued to be drained at an average rate of over
600,000 acres per year from 1980 to 1985 (see Table 4.1). By 1985, nearly 110
million acres of farmland had been drained. It appears that most of the drainage
since 1975 was accomplished through subsurface systems, as the amount of surface
drainage remained fairly constant during that period.2
	National drainage trends may be misleading, however, since drainage activity may
be intense in some states and regions. For instance, significant drainage activity is
still taking place in the Lower Mississippi River Valley, Florida, and the Southeast
in general (OTA 1984). In 1985, five states (Arkansas, Louisiana, Mississippi,
Indiana, and Ohio) had drained at least 50 percent of their cropland (Pavelis 1987).
Pavelis' drainage data is based on agricultural census information, supplemented with recent data from USDA agencies,
including the National Resources Inventory.
The recent increase in the use of subsurface drainage systems can be attributed to improved equipment and matenal. lower
maintenance costs, and minimal damage to the land (Pavelis 1987).
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TABLE 4.1
RATE OF FARMLAND DRAINAGE IN THE UNITED STATES: 1950-1985

Cumulative
Marginal

Cumulative
Marginal

Acres
Change in

Acres
Change in
Year
Drained
Acres Drained
Year
Drained
Acres Drained

(million acres)

(million acres)
1950
69.9
	
1981
106.7
.4
1955
78.9
9.0
1982
107.2
.5
1960
86.6
7.7
1983
108.1
.9
1965
93.6
7.0
1984
109.0
.9
1970
99.1
5.4
1985
109.7
.7
1975
103.4
4.3



1980
106.3
2.9



Adapted from Pavelis. George A., ed. (1987). Farm Drainage in the United States: History. Status, and Prospects. Washington. D.C.
U.S. Department of Agriculture. Economic Research Service.
	Based upon preliminary drainage data in an earlier draft of Pavelis' report, the
Office of Technology Assessment (OTA 1984) estimated the rate of wetland
conversions from 1975 to 1980 to be 250,000 acres per year, about half of the
estimated 550,000 acres converted per year from 1955 to 1975.1 OTA derived the
percentage of farmland drained that were wetlands by comparing surface drainage
data2 from 1955 to 1975 with estimates from the NW1 on wetlands lost to agriculture
during roughly the same period. OTA found that approximately 65 percent of the
farmland surface-drained between 1955 and 1975 were wetlands, and applied the
same percentage to farmland surface-drained between 1975 and 1980.
	Since OTA's report in 1984, Pavelis has revised his data on drainage from 1955
to 1980 and provided new data for drainage in the 1980s (see Table 4.1 above). As
reported in Pavelis (1987), the area of surface-drained farmland has actually
decreased slightly from 1975 to 1985. Therefore, trends in surface drainage may no
longer be a reliable indication of trends in wetland conversions. However, we can
find the percentage of total farmland drained (both surface and subsurface) that were
wetlands and derive a new estimate. Based upon data from 1955 to 1975, about 45
percent of the total area drained was wetlands. Applying this percentage to the 6.3
million acres of farmland drained from 1975 to 1985, we can estimate that about 2.8
million acres, or 280,000 acres per year, of wetlands were converted during that
period.

2
Wetland loss rate estimated in National Wetlands Inventory (NWT).
OTA assumed that most wetland conversions involved surface, not subsurface, drainage.
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FIGURE 42
USES OF DRAINED RURAL LANDS: 19821
OTHER (15*)
Pavelis. George A., ed. (1987). Farm Drainage in the United States: History. Status, and Prospect*. Washington, D.C.: U.S. Department
of Agriculture, Economic Research Service.
 Out of a total of about 107 million acres of rural land that was drained as
of 1982, approximately 70 percent was used for cropland in production. How-
ever, the potential may exist for the other 30 percent to be converted to crop-
land at a later time.
i
Data is based upon the results of the 1982 National Resources Inventory.
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FIGURE 4.3
DUCK BREEDING POPULATIONS
IN NORTH AMERICA: 1955 TO 19891
YEAR
U S Fish and Wildlife Service and Canadian Wildlife Service. (1989). Status of Waterfowl & Fall Flight Forecast. Washington. D.C .
U S. Fish and Wildlife Service.
	The total duck population for 1989, estimated at 30.9 million, decreased 8 percent
from the 1988 estimate of 33.6 million, and is 24 percent below the 1955-88 average.
	The duck population of the mid to late-1980s is at the lowest recorded number
in 20 years.
	According to the report, the downward trend in the duck population can only be
reversed if a return to more normal weather patterns is accompanied by a significant
reduction in the impacts of agricultural activities on wetland areas important to
breeding waterfowl.
The duck breeding population survey is initiated in early May and ends in mid-June of each year. Its purpose is to
determine the species and number of potential breeding ducks in the principal nesting areas of North America. Aerial counts of ducks
are corrected with "visibility rates' derived from sample transects that are censused from both the air and the ground. Figures exclude
scoters, elders, oldsquaws, and mergansers.
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APPENDIX A
COMPARISON OF WETLANDS ACREAGE STUDIES

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FIGURE A.1
COMPARISON OF WETLANDS ACREAGE STUDIES
120
NTTI 1950s	N1 1970s	NRI 1982	NRI 1982 * Federal
STUDIES
Basd on Heimlich, Ralph E, and Linda L Langner. (1986). Swamobusting Wetlands Conversion and Farm Programs. Washington.
D.C.: U S. Department of Agriculture, Economic Research Service.
	This graph illustrates recent estimates of total wetland acreage in the United States as
determined by the National Wetlands Inventory (NWI) for both the mid-1950s and the mid-
1970s; the 1982 National Resources Inventory (NRI), which surveyed nonfederal wetlands only;
and the sum of the NRI nonfederal wetlands estimate and an estimate of federal wetland
acreage cited in Heimlich and Langner (1986).
	"NWI 1950s" (108.1 million) and "NWI 1970s" (99.0 million) represent the total wetland
acreages estimated by the National Wetlands Inventory to exist in the lower 48 states during the
mid-1950s and the mid-1970s. The inventory was conducted by the U.S. Fish and Wildlife
Service (see Frayer et al, 1983). The inventory compared black and white aerial photographs
from the mid-1950s with photographs from the mid-1970s and estimated wetland acreage,
changes in wetlands, and causes of change. The conclusions were extrapolated from a random
sample of 3,635 4-square-mile units. The NWI uses the wetland classification system found in
Cowardin (1979).
(CONTINUED ON NEXT PAGE)
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	The NWI is designed to produce national statistics that, on average, have a probability of 90
percent that estimated totals for each wetland category are within 10 percent of the true figure.
The standard errors of each individual estimate vary widely and were not meant to be relied
on for state or regional analyses.
	"NRI 1982" (78.4 million) represents the total wetland acreage estimated by the 1982 National
Resources Inventory to exist on nonfederal lands in the conterminous United States, plus
Hawaii and Puerto Rico, as of 1982. The t^RI was conducted by the USDA Soil Conservation
Service for nonfederal lands only, including land owned by state, county, municipal, and Indian
governments. Data were collected and extrapolated from field observations of 841,860 sample
points in nearly 350,000 primary sampling units of approximately 160 acres each. The NT^I
classifies wetlands according to both the Circular 39 system (Shaw and Fredine, 1956) and the
five major classes (Marine, Estuarine, Riverine, Lacustrine, and Palustrine) found in Cowardin
(1956).
	The NRI is designed to achieve a 95 percent confidence interval around estimates of acreages
comprising at least 10 percent of a major land resource area (MLRA).
	Possible explanations for the 20.6 million acre difference between the NWI and the NRI
include: 1) the NRI does not include federal lands; 2) the NRI may fail to account for some
intermittent wetlands; and 3) the loss of wetlands between the mid-1970s and 1982 (Heimlich
and Langner, 1986).
	"NRI 1982 + Federal" (90.9 million) represents the NRI estimate of nonfederal wetland
acreage as of 1982 plus an estimate of 12J million acres of federally held wetlands as of 1985
produced by Dale Pierce, Department of the Interior (cited in Heimlich and Langner, 1986).
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APPENDIX B
BIBLIOGRAPHY

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BIBLIOGRAPHY
Clark, Edwin H. II. (1989). "Market and Intervention Failures in the Management of
Wetlands: Case Study on the United States (Draft)." Paris, France: Organization
for Economic Co-operation and Development.
Cowardin, L.M., V. Carter, F.C. Gobet, and E.T. LaRoe. (1979). Classification of
Wetlands and Deepwater Habitats of the United States. Washington, D.C.: U.S.
Fish and Wildlife Service.
Dahl, Thomas E., and H. Ross Pywell. (1989). "National Status and Trends Study:
Estimating Wetland Resources in the 1980's." Wetlands: Concerns and Successes.
American Water Resources Association.
Food and Agriculture Policy Research Institute. (1989). U.S. and World Agricultural
Outlook: Summary of Tables. Iowa State University, University of Missouri-
Columbia.
Frayer, W.E., TJ. Monahan, D.C. Bowden, and F. A. Graybill. (1983). Status and Trends
of Wetlands and Deepwater Habitats in the Conterminous United States. 1950s to
1970s. Ft. Collins, CO: Colorado State University, Department of Forest and Wood
Sciences.
Goldman-Carter, Janice, et al. (1989). Statement of the National Wildlife Federation
before the House Committee on Agriculture, July 13, 1989.
Goldstein, Jon. (1988V The Impact of Federal Programs on Wetlands. Volume One: The
Lower Mississippi Alluvial Plain and the Prairie Pothole Region. Washington, D.C.:
U.S. Department of the Interior.
Heimlich, Ralph E. (1989). "The Swampbuster Provision: An A Priori Evaluation of
Effectiveness." Wetlands: Concerns and Successes. American Water Resources
Association.
Heimlich, Ralph E., and Linda L Langner. (July/August 1986). "Swampbusting in
Perspective." Journal of Soil and Water Conservation. Volume 41, No. 4.
Heimlich, Ralph E., and Linda L. Langner. (1986). Swampbusting: Wetlands Conversion
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Research Service.
Office of Technology Assessment. (1984). Wetlands: Their Use and Regulation.
Washington, D.C.: U.S. Congress, OTA. Report No. OTA-0-206.
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Pavelis, George, ed. (1987). Farm Drainage in the United States: History. Status, and
Prospects. Washington, D.C.: U.S. Department of Agriculture, Economic Research
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Shaw, S.P., and C.G. Fredine. (1956). Wetlands of the United States: Their Extent and
Their Value to Waterfowl and Other Wildlife. Washington, D.C.: U.S. Fish and
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Teels, Billy, David Davis, Bill Wilen, and Harvey Nelson. (1988). "Status and Trends of
America's Wetlands." Washington, D.C.: USDA, Soil Conservation Service.
Tiner, Ralph W. (1987). Mid-Atlantic Wetlands: A Disappearing Natural Treasure.
Newton Corner, MA: U.S. Fish and Wildlife Service.
Tiner, Ralph W. (1984). Wetlands of the United States: Current Status and Trends.
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U.S. Department of Agriculture. (1988). Agricultural Statistics 1988. Washington, D.C.:
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U.S. Department of Agriculture. (1987). Basic Statistics: 1982 National Resources
Inventory. Washington, D.C.: USDA, Soil Conservation Service. Statistical Bulletin
Number 756.
U.S. Department of Agriculture. (1980-1988). Crop Production. Annual Reports.
Washington, D.C.: USDA, National Agricultural Statistics Service.
U.S. Department of Agriculture. (1989). Food Security Act Progress Report, October 16,
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U.S. Department of Agriculture. (1980). Instructions for the SCS-Multiresource Inventory.
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U.S. Department of Agriculture. (1987). The Second RCA Appraisal: Soil. Water, and
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and Trends. Washington, D.C.: USDA.
U.S. Environmental Protection Agency (1989). Natural Resources for the 21st Century:
An Evaluation of the Effects of Land Use on Environmental Quality. Washington,
D.C.: U.S. EPA, Office of Policy, Planning, and Evaluation.
U.S. Fish and Wildlife Service. (1988). Proceedings of the National Symposium on
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and Fall Flight Forecast. Washington, D.C.: U.S. Fish and Wildlife Service.
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