United States 

Department of 

Agriculture

Economic

Research

Service

Glenn D. Schaible and Marcel P. Aillery

Water Conservation in Irrigated 

Agriculture: Trends and Challenges 

in the Face of Emerging Demands

Economic 

Information 

Bulletin 

Number 99

September 2012
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Recommended citation format for this publication:

Schaible, Glenn D., and Marcel P. Aillery. Water Conservation in Irrigated 

Agriculture: Trends and Challenges in the Face of Emerging Demands,

EIB-99, U.S. Department of Agriculture, Economic Research Service, 

September 2012. 
United States

Department

of Agriculture

www.ers.usda.gov

A Report from the Economic Research Service

Abstract

This report relies on fi ndings from several national surveys and current literature to assess 

water resource use and conservation measures within the U.S. irrigated crop sector. U.S. 

agriculture accounts for 80-90 percent of the Nation’s consumptive water use (water lost 

to the environment by evaporation, crop transpiration, or incorporation into products). 

Expanding water demands to support population and economic growth, environmental 

fl ows (water within wetlands, rivers, and groundwater systems needed to maintain natural 

ecosystems), and energy-sector growth, combined with Native American water-right claims 

and supply/demand shifts expected with climate change, will present new challenges for 

agricultural water use and conservation, particularly for the 17 Western States that account 

for nearly three-quarters of U.S. irrigated agriculture. Despite technological innovations, at 

least half of U.S. irrigated cropland acreage is still irrigated with less effi cient, traditional 

irrigation application systems. Sustainability of irrigated agriculture will depend partly 

on whether producers adopt more effi cient irrigation production systems that integrate 

improved onfarm water management practices with effi cient irrigation application systems. 

Keywords: agricultural water conservation, irrigated agriculture, irrigation effi ciency, 

water supply and demand, irrigation technologies, water management practices, water 

conservation policy

Acknowledgments

The authors would like to thank Steve Wallander from USDA’s Economic Research 

Service, Jim Ayars from USDA’s Agricultural Research Service, Raymond J. Supalla from 

the University of Nebraska – Lincoln, Brian Hurd from New Mexico State University, 

Jan Lewandrowski from USDA’s Offi ce of the Chief Economist, and Noel Gollehon 

from USDA’s Natural Resources Conservation Service for their review comments and 

suggestions. The authors also wish to thank Angela Anderson for editorial support and 

Curtia Taylor for production/design support. 

Glenn D. Schaible

Marcel P. Aillery

Water Conservation in Irrigated 

Agriculture: Trends and Challenges 

in the Face of Emerging Demands

Economic 

Information 

Bulletin

Number 99

September 2012
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Contents

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Water Supply and Demand Challenges 

for Irrigated Agriculture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

 Traditional Water Demands: 

 Agriculture Versus Nonagricultural Sectors . . . . . . . . . . . . . . . . . . . . . . . 2

 New Challenges for Irrigated Agriculture. . . . . . . . . . . . . . . . . . . . . . . . . 3

 The Challenge for Agricultural Water Conservation . . . . . . . . . . . . . . . 12

How Important Is Irrigation to U.S. Agriculture? . . . . . . . . . . . . . . . . . 15

 Where Does Irrigation Occur and What Does It Produce?. . . . . . . . . . . 16

 How Much Water Is Applied, What Is Its Source,

 and What Does It Cost?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

How Effi cient Is Irrigated Agriculture?. . . . . . . . . . . . . . . . . . . . . . . . . . 26

Irrigation Investments: Decision Factors, 

Types, Purposes, and Funding Sources . . . . . . . . . . . . . . . . . . . . . . . . . . 39

 Factors Affecting Irrigation Technology 

 Investment Decisions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

 Onfarm Irrigation Investment Expenditures . . . . . . . . . . . . . . . . . . . . . . 43

 Sources of Onfarm Irrigation Investment Funding . . . . . . . . . . . . . . . . . 44

Summary and Policy Implications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
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Summary

What Is the Issue?

Population and economic growth, changing social values about the importance of water quality and the environment, and Native American water-right 

claims will continue to drive growing U.S. demand for water resources. 

Expansion of the U.S. energy sector is expected to further increase regional 

demands for water. At the same time, projected climate change—through 

warming temperatures, shifting precipitation patterns, and reduced snowpack—is expected to reduce water supplies and increase water demand across 

much of the West. 

These trends are placing greater pressure on existing water allocations, 

heightening the importance of water management and conservation for the 

sustainability of irrigated agriculture. How well irrigated agriculture adapts 

to growing constraints on water, particularly by increasing its water-use 

effi ciency, will directly affect the economic health and sustainability of the 

sector. 

What Did the Study Find?

Irrigated agriculture, which accounts for 80-90 percent of consumptive water 

use in the United States, represents a signifi cant share of the value of U.S. 

agricultural production.

• Based on the 2007 Census of Agriculture, irrigated farms accounted 

for roughly 40 percent ($118.5 billion) of the value of U.S. agricultural 

production; nationwide, the average value of production for an irrigated farm was more than three times the average value for a dryland 

farm.

• Irrigated farms accounted for 54.5 percent ($78.3 billion) of the value 

of all crop products sold and contributed to the farm value of livestock 

and poultry production through animal forage and feed production. 

Livestock/poultry products accounted for roughly a third of market 

sales for irrigated farms and 63 percent for nonirrigated (dryland) 

farms. Irrigated forage and feed production contributed to the livestock/poultry market sales for both irrigated and nonirrigated farm 

types.

• Nearly 57 million acres were irrigated across the United States in 

2007, or 7.5 percent of all cropland and pastureland. Roughly threequarters of U.S. irrigated agriculture occurred in the 17 Western 

States, although irrigation has been expanding in the more humid 

Eastern States. 

• Based on the 2008 Farm and Ranch Irrigation Survey (a followup 

to the 2007 Census of Agriculture), irrigated agriculture across the 

Western States applied 74 million acre-feet (24 trillion gallons) of 

water for crop production, with 52 percent originating from surfacewater sources and 48 percent pumped from wells that draw from local 

and regional aquifers.
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Demands on agricultural water supplies are likely to increase over time 

as alternative nonfarm uses of water continue to grow. Potential Native 

American water-right claims have been estimated at nearly 46 million acrefeet annually and could impact the distribution and cost of irrigation water in 

the West. For many States, the scope of water demands for the environment 

have expanded from a minimum instream fl ow to an “environmental-fl ows” 

standard (i.e., a concept requiring water to meet the needs for water quality, 

but to also rehabilitate ecosystem habitats). Energy-sector growth is expected 

to signifi cantly increase water demands for an expanding biofuels sector, utility-scale development of solar power, innovation in thermoelectric generating 

capacity, and commercial oil-shale and deep shale natural gas development. 

Expansion in these competing water demands, especially with water supply/

demand impacts expected with climate change, presents new challenges for 

agricultural water use and conservation, particularly in the arid Western 

States.

While substantial technological innovation has increased the effi ciency of 

irrigated agriculture over the past several decades, signifi cant potential exists 

for continued improvement. At least half of irrigated cropland acreage across 

the United States is still irrigated with less effi cient, traditional irrigation 

application systems. In addition, most irrigators do not make use of the more 

effi cient onfarm water-management practices that conserve the most water.

• Irrigators continue to make signifi cant investments in new and 

improved irrigation systems. Approximately $2.15 billion was invested 

in irrigation systems in 2008, a 92-percent increase over investments 

for 2003.

• Most onfarm irrigation investment is fi nanced privately—less than 10 

percent of farms reported fi nancing irrigation improvements in 2008 

through public fi nancial assistance programs. Nearly 57 percent of 

the farms that received fi nancial assistance for irrigation technology 

adoption did so through USDA’s primary working lands conservation 

program—the Environmental Quality Incentives Program (EQIP). 

Irrigated farms participating in EQIP, however, represented only about 

4 percent of all farms making irrigation investments in 2008.

• Over time, EQIP funding has had an important impact on irrigation investments, amounting to $1.4 billion from 2004 through 2010. 

Nationally, irrigation practices accounted for roughly a quarter of total 

EQIP funding obligations ($5.7 billion) during 2004-10.

• Less than 10 percent of irrigated farms use advanced onfarm water 

management decision tools, such as soil- or plant-moisture sensing 

devices, commercial irrigation-scheduling services, or computer-based 

crop-growth simulation models. The sustainability of irrigated agriculture may depend partly on the willingness and ability of producers to 

adopt irrigation “production systems” that more effectively integrate 

improved water management practices with effi cient irrigation application systems. 

• Agricultural water conservation is both a farm and basin-level resource 

conservation issue. Integrating the use of improved onfarm irrigation effi ciency with State and Federal watershed water-management 
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tools (e.g., conserved water rights, drought water banks, option and 

contingent water markets, reservoir management, irrigated acreage and 

groundwater pumping restrictions, and irrigated acreage retirement) 

encourages producers to recognize and respond to differing values of 

water across competing uses, improving the potential for sustainable 

irrigation while facilitating water reallocation to other uses.

How Was the Study Conducted?

This report draws on several USDA agricultural production and water-use 

analyses and surveys, as well as an extensive literature review, to describe 

the U.S. irrigated agriculture sector, existing and emerging water demands, 

trends in water-use effi ciency in irrigated agriculture, and funding levels 

(private and public) for farm-level irrigation investments. USDA’s Censuses 

of Agriculture (1982-2007) and Farm and Ranch Irrigation Surveys (FRIS) 

for 1984-2008, together with the U.S. Geological Survey’s (USGS) wateruse summaries, were used to assess the demand for U.S. water resources 

and the importance of irrigation to U.S. agriculture—where it occurs, what 

it produces, how much water agriculture uses, the water sources supplying 

irrigation, and the costs of irrigation. FRIS data are also used to analyze the 

effi ciency of irrigated agriculture as of 2008 to demonstrate the potential for 

continued agricultural water conservation as producers more effectively integrate onfarm and off-farm water management practices with improved irrigation production systems. USDA’s FRIS and conservation program contract 

data are used to examine the current status of private and public investments 

in irrigated agriculture. 
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Introduction

Across the United States, human and environmental demands for water 

resources have increased signifi cantly over the last 50 years. Population and 

economic growth, changing social norms regarding the importance of water 

quality and protection of ecosystems, and longstanding Native American 

water-right claims have increased pressures on available water supplies, 

particularly in the arid Western States. Given that agriculture accounts for 

80-90 percent of U.S. consumptive water use, relatively fi xed water supplies 

and growing water demands have heightened confl icts over agricultural allocations in water-short years.

Water confl icts have required a variety of legislative and judicial remedies, 

generally involving reallocation of agricultural water supplies to meet the 

rising needs of competing water users (NRC, 1996; CBO, 1997; Gollehon 

and Quinby, 2006; Schaible et al., 2010). Historically, Federal and State 

programs have focused on agricultural water conservation, mandatory withdrawal restrictions, and the use of water markets to meet the Nation’s various 

water needs. More recently, water demands for an expanding energy sector 

and shifting regional water balances under climate change projections have 

heightened awareness of the importance of water conservation for a sustainable future for irrigated agriculture. Knowledge about the status and the 

social and institutional dimensions of competing uses of water resources 

provides a better understanding of the supply and demand challenges facing 

irrigated agriculture.
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Water Supply and Demand Challenges 

for Irrigated Agriculture

Traditional Water Demands: Agriculture Versus 

Nonagricultural Sectors

The U.S. Geological Survey (USGS) has developed water-use estimates for 

major water demand sectors of the United States, reported every 5 years since 

1950 (fi g. 1). Water withdrawals1 across all sectors—including public use 

(largely municipal), rural/domestic use, livestock use, irrigation, thermoelectric power generation, and all other uses—increased dramatically between 

1950 and 2005. Total water withdrawals, which peaked at about 482 million 

acre-feet (maf)2 in 1980 before declining slightly and then leveling off after 

1985, were estimated at 460 maf in 2005 (or 128 percent higher than in 1950) 

(Kenny et al., 2009). Water withdrawals for irrigated agriculture and the 

thermoelectric power sector—traditionally the dominant sources of water 

demand—have increased the most since 1950. Nationally, water withdrawals 

for thermoelectric power (primarily for cooling purposes) accounted for 49 

percent of total U.S. withdrawals in 2005 (about 225 maf). Thermoelectric 

withdrawals increased 400 percent between 1950 and 2005, with a 4-percent 

decrease from peak demand in 1980. Nearly 98 percent of water withdrawals 

for thermoelectric cooling systems, however, currently return to their source 

1Water withdrawals (one measure 

of water demand) refer to the removal 

of water from streams, rivers, lakes, 

reservoirs, and groundwater aquifers 

for a specifi c use. 

2An acre-foot of water represents the 

quantity required to fl ood 1 acre of land 

at 1 foot in depth, equivalent to 325,851 

gallons.

Note: U.S. Geological Survey water use numbers were converted to million acre-feet units.

Source: Kenny et al., table 14, p. 43, 2009.

Figure 1

Trends in total water withdrawals, by major water-use category, 1950-2005

Withdrawals (million acre-feet per year)

0

100

200

300

400

500

600

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Public supply 

Rural domestic and livestock 

Irrigation 

Thermoelectric power 

Other 

Total withdrawals 
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of origin, where the water can be reused for other purposes, including 

irrigation.

Irrigated agriculture, with withdrawals of about 143 maf, accounted for 31 

percent of the Nation’s total in 2005. Irrigation withdrawals in 2005 were 43 

percent above the level for 1950, though 15 percent below peak demand in 

1980. For the 17 Western States,3 irrigated agriculture accounted for most 

water demand from both surface water and groundwater sources (fi g. 2) 

(Kenny et al., 2009). In 2005, water withdrawals for irrigated agriculture 

in the 17 Western States totaled approximately 122.4 maf, or 64 percent of 

total water withdrawals in the region; irrigated agriculture accounted for 

58 percent of surface water withdrawals and 79 percent of groundwater 

withdrawals.4

New Challenges for Irrigated Agriculture

Competing demands for U.S. water resources have continued to increase and 

are expected to intensify water resource confl icts over the foreseeable future. 

Important sources of expected growth and/or emerging water demands 

include Native American water rights, instream (environmental) fl ow 

3The 17 Western States include 

Arizona, California, Colorado, 

Idaho, Kansas, Montana, Nebraska, 

Nevada, New Mexico, North Dakota, 

Oklahoma, Oregon, South Dakota, 

Texas, Utah, Washington State, and 

Wyoming. All other States within the 

contiguous United States are referred 

to in this report as the 31 Eastern States 

(or Eastern States).

4Water withdrawals as a measure of 

water demand are used here because 

they are the best and most recently 

available data by water-demand sector. 

Some portion of withdrawals returns 

to the hydrologic system, is lost to the 

system, or is otherwise irrecoverable 

after its initial use. Consumptive use 

by sector would provide improved 

estimates of water demand; however, 

the most recent USGS water-use 

estimates do not identify consumptive 

use values. USGS last estimated 

consumptive water use by sector in 

1995. 

Source: USDA, Economic Research Service calculations based on Kenny et al., p. 52, 2009.

Figure 2

Water withdrawals, by water source and water-use category, 2005

Million acre-feet per year

Million acre-feet per year

0

20

40

60

80

100

120

140

160

17 Western States

0

50

100

150

200

250

300

350

400

Surface water

Public

supply

Domestic Irrigation Livestock AquacultureIndustrial Mining Thermoelectric

power

Total

Public

supply

Domestic Irrigation Livestock AquacultureIndustrial Mining Thermoelectric

power

Total

Groundwater

U.S. total

Surface water Groundwater
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requirements, and an expanding energy sector. In addition, climate change is 

expected to affect both the supply of and demand for freshwater.

Native American Water Rights

Native American reservation water rights were established by the U.S. 

Supreme Court in its 1908 Winters v. United States decision. The ruling 

established reserved water rights based on the amount of water necessary 

for Native Americans to maintain and survive on the land granted to the 

reservation by the Government, even if those rights were not explicitly stated 

in the reservation treaty. In subsequent decisions, the U.S. Supreme Court 

quantifi ed those water rights as the water needed to irrigate all “practicably 

irrigable acreage” on the reservation and made such rights generally superior 

to the rights of all other appropriators by vesting them with a “priority” date 

equivalent to the date the reservation was established (Gregory, 2008; Moore, 

1989). In addition, while Winters v. United States applies to surface waters, 

in 1976, the U.S. Supreme Court (Cappaert v. United States) opened the door 

for Native American reserved water-right claims to apply to groundwater. No 

defi nitive decision on Native American reserved groundwater rights has been 

made, but some States recognize these rights (Gregory, 2008).

Potential Native American water-right claims have been estimated at nearly 

46 maf annually (Western States Water Council, 1984). At present, the 

claims for many reservations are under negotiation or remain unresolved 

within settlement disputes or judicial proceedings. Future resolution of these 

water-right claims will undoubtedly affect the water resources available 

for co mpeting uses, including off-reservation irrigated agriculture. Settling 

Native American water-right claims, however, may not result in less water 

for agriculture, but rather a reallocation of existing water rights. While 

water delivered to U.S. Tribes generally originates from existing water-right 

allocations, Tribes are generally allowed to assign, exchange, lease, and 

create options to lease water rights through settlement arrangements. Within 

existing negotiated settlements, some reallocated water supports irrigation 

expansion on reservation lands, but Tribes also may agree to lease water to 

off-reservation agricultural users, to non-Indian lessees on reservation lands, 

and to nonagricultural users, such as municipalities (Claims Resolution Act 

of 2010). 

To the extent that Tribes accept compensation in lieu of wet water, the 

actual reallocation of water from existing agricultural users may be limited. 

However, due to the political and fi nancial challenges in negotiating or adjudicating water rights claims and a lack of ability to fi nance irrigation projects 

and related storage, exercising reservation water rights has moved historically 

at a relatively slow pace. The reality is that, for many reservations, future 

development of these claims will likely continue to progress slowly barring 

an infusion of economic, legal, and technical assistance.5

Instream (Environmental) Flows6

Historically, water resources were managed to fulfi ll the needs of out-ofstream development, such as crop irrigation and municipal or industrial 

expansion. Water not withdrawn from a stream for economic development 

was generally considered wasted water. Water-fl ow needs for fi sh and wildlife 

5Under the U.S. Department of 

the Interior’s Indian Water Rights 

Settlement Program, the Federal 

Government has refocused settlement 

of tribal water-right claims, shifting 

from litigation to negotiated 

settlements (U.S. BoR, 2012). 

Recent congressional hearings on 

“Indian Water Rights: Promoting the 

Negotiation and Implementation of 

Water Settlements in Indian Country” 

indicate that in the last dozen years, 

27 tribal settlements were concluded 

based on this process, compared with 

less than 10 through the litigation 

process (U.S. Senate Committee on 

Indian Affairs, 2012). These settlements 

often involve, via congressional 

approval, allowing Tribes to assign, 

exchange, and lease their water rights 

to non-Indian users both on and off 

the reservation. While many Tribal 

water rights remain unquantifi ed, 

these settlements enhance certainty 

in water-rights allocations and also 

may contribute to new investment in 

improved (more effi cient) irrigation 

systems.

6Flow is generally measured as 

the volume of water per unit of time, 

usually cubic feet per second, and 

represents the amount of water fl owing 

past a point in the river at a given time.
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habitat and other ecosystem benefi ts were not a legally recognized water 

management priority. From the 1970s on, however, changing social values 

with respect to water quality and environmental/ecosystem services have had 

greater infl uence on Federal and State water-resource management institutions and policies. Changing environmental values initially led to the establishment of minimum streamfl ow requirements to meet legally recognized 

instream water needs. Subsequently, watershed/basin-level water management agencies were legally bound to manage water resources consistent with 

maintaining sustainable ecosystems. 

Minimum streamfl ow management focused primarily on the need for a 

minimum amount of water to be left in a stream, generally to maintain fi sh 

habitat (Poff et al., 2003; Zellmer, 2009; MacDonnell, 2009). In basins with 

signifi cant irrigation withdrawals, minimum fl ow provisions often reallocate 

water supplies from agriculture, particularly during low-fl ow (drought) years. 

More recently, the use of fl ow provisions designed to enhance ecosystem 

services has become broader in scope. Often referred to as “environmental 

fl ows,” these fl ow regimes are intended to provide multiple instream benefi ts, 

including enhanced fi ltration, dilution of sewage and other effl uents, fi sh 

and wildlife habitat, recreation (fi shing, hunting, boating, and environmental aesthetics), hydropower, navigation, groundwater recharge,7 riparian 

wetlands, and migratory bird habitat, as well as exotic species control and 

local/regional economic development (Sophocleous, 2007; Zellmer, 2008; 

MacDonnell, 2009). 

Environmental fl ows will likely play an increasingly important role in the 

ongoing struggle among competing water demands. Most Western States have 

adopted some form of legislation establishing minimum instream fl ows, and 

provisions have evolved over time to refl ect the complexities of hydrology and 

a range of instream uses.8 See the box, “Environmental Flows and Increasing 

Demand Pressures,” for examples of the growing pressure that environmental 

fl ows place on limited water supplies. 

Water for Energy Expansion

U.S. energy sector growth, for production of biofuels and other energy 

sources, is expected to place increasing demand on water resources. In the 

Western States, where surface-water systems are already over-appropriated 

and groundwater aquifer levels are generally declining, energy-related water 

demand could directly affect irrigated agriculture. 

An expanding biofuel sector will require water for both processing and feedstock production. Water demand for a biofuel plant with a given processing 

capacity is generally known (an engineering relationship), local (sitespecifi c), and typically managed through market-based permanent lease or 

purchase agreements between local farms and the biofuel fi rm. While total 

withdrawals for biofuel processing are comparatively low, local/regional 

impacts on water resources can be sizable. Water demands for irrigated feedstock production for biofuel production, however, may be more signifi cant. 

While some of this water demand will likely come from existing irrigated 

production, a growing biofuel industry may increase demand for irrigation 

water as producers respond to higher corn and soybean prices by expanding 

7A system of using the hydrologic 

process to refi ll a groundwater aquifer 

by either pumping water back into 

wells or managing surface water to 

increase downward water percolation to 

the groundwater aquifer.

8The evolution and status of 

State-specifi c minimum instreamenvironmental fl ow programs, statutes, 

and policies, which vary widely 

across the Western States, have been 

summarized by MacDonnell (2009).
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Environmental Flows and Increasing Demand Pressures 

Changing societal values have focused greater attention on water resources 

to meet the needs for water quality, fi sh and wildlife habitat, and other 

ecosystem services. These water demands have often exceeded the historical 

“minimum instream-fl ow” requirement. The following examples demonstrate 

how providing water for “environmental fl ows” places increasing pressures on 

limited water supplies.

Stream and river restoration projects have become an important component 

of Federal and State environmental management programs. A recent study, 

based on a review of 37,099 projects in the National River Restoration Science 

Synthesis database, reported that the number of restoration projects has 

increased exponentially since 1990 (Sophocleous, 2007; Bernhardt et al., 2005). 

These restoration projects may be designed to achieve multiple objectives, 

including enhanced water quality; management of riparian zones; improved 

instream habitat for fi sh and other aquatic species; improved fi sh passage; bank 

stabilization; fl ood plain management; river/stream channel reconfi guration; 

and fl ow modifi cation for fi sh, aesthetics, and recreation. The study estimated 

that from 1990 to 2004, more than $14 billion was spent on stream/river 

restoration projects within the continental United States, averaging slightly 

more than $1 billion annually.

In many Western States, water markets are increasingly being used to reallocate 

water from existing uses, particularly from agriculture, to enhance supplies 

for environmental fl ows within fully or over-appropriated basins. Many State 

water laws now recognize environmental fl ows as a benefi cial use and allow 

State and nongovernmental organizations (NGOs), including conservation and 

environmental groups, to lease, purchase, or donate water or water rights to 

enhance river fl ows (Sophocleous, 2007; MacDonnell, 2009). Landry (1998) 

reported that from 1990 to 1997 about 2.4 million acre-feet (maf) of water 

was “leased, purchased, or donated for purposes of enhancing river fl ows in 

the Western United States.” While this does not refl ect the total volume of 

water for instream fl ows (a quantity diffi cult to measure), by comparison, water 

transferred for environmental purposes represented about 5.2 percent of the 

quantity of surface water applied by irrigated agriculture in 1998.

From 2000 to 2005, the Colorado River Basin experienced the worst drought 

conditions in approximately 100 years, with Lake Powell and Lake Mead 

dropping to about 46 percent of combined water storage capacity (Jerla and 

Prairie, 2009). As a result, the Bureau of Reclamation (Reclamation), through 

the National Environmental Policy Act process, developed a management plan 

for the basin that included interim guidelines for coordinated water storage 

operations during Lower Colorado River Basin water shortages (U.S. BoR, 

2007; Jerla and Prairie, 2009). The preferred management alternative for the 

basin included a “Conservation Before Shortage” alternative (developed by a 

consortium of eight environmental NGOs) to allow Reclamation to develop 

and manage voluntary compensated, conservation reduction/water-banking 

programs that would include water for environmental uses. In July 2006, 

these environmental NGOs submitted a new proposal, “Conservation Before 

Shortage II,” encouraging Reclamation to expand its use of voluntary marketbased conservation mechanisms to provide water to protect but also enhance 

fl ow-dependent environmental values within the lower basin (Gillon et al., 

2006). --continued
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Environmental Flows and Increasing Demand Pressures 

(continued)

Over the years, managing water supplies to enhance benefi ts for fi sheries and 

ecosystem values has become an increasingly important focus for the Central 

Valley of California. The Central Valley Project (CVP), initially authorized 

in 1933 and completed in the early 1970s, is comprised of 18 dams and 

reservoirs and over 500 miles of canals and aqueducts. The project conveys 

about 7.4 maf of water annually from the Sacramento, Trinity, American, 

Stanislaus, and San Joaquin Rivers to agricultural users (irrigating more than 

3.0 million acres), municipal users, and wildlife refuges and for recovery of 

endangered fi sh species in the Sacramento and San Joaquin Valleys and the San 

Francisco Bay/Delta Estuary. In 1992, the U.S. Congress adopted the Central 

Valley Project Improvement Act (CVPIA), which formally identifi ed fi sh and 

wildlife protection, restoration, and mitigation as project objectives of equal 

priority with irrigation and other domestic uses, as well as required the CVP 

to contribute to the State’s efforts to protect the Bay/Delta Estuary (U.S. BoR, 

2009). The act also reallocated 800,000 acre-feet of water from existing users 

to fi sh and wildlife annually. 

Since 1992, and after nearly $1 billion had been spent on numerous restoration 

projects throughout the Central Valley, the CVPIA Program Activity Review 

(conducted by the U.S. Bureau of Reclamation) reported that “there is no basis 

to conclude” that the provisions of the CVPIA “have been satisfi ed” (U.S. BoR, 

2009), while an independent review panel concluded that anadromous fi sh 

species had “stayed relatively even or declined from 1992-2005” (Circlepoint, 

2008). Therefore, reallocating water supplies to meet environmental/ecosystem 

concerns within the Central Valley remains a high priority of the State/Federal 

partnership (CALFED), an agreement by 25 State and Federal agencies 

established in 2000 to “work collaboratively toward achieving balanced 

improvements” for the Bay/Delta Estuary (CALFED Bay-Delta Program, 

2010). 

More recently, efforts of the State and CALFED have taken on a larger 

ecosystem sustainability focus. In 2006, California State agencies initiated the 

Bay Delta Conservation Plan, a collaborative effort by State, Federal, and local 

water agencies; State and Federal fi sh agencies; environmental organizations; 

and other interested parties to identify water fl ow and habitat restoration actions 

designed to recover endangered sensitive species and their habitats in the 

Bay-Delta area, while also providing for improved reliability of water supplies 

(U.S. BoR, 2010). Draft habitat conservation plans for the Bay-Delta area are 

expected to be completed in 2012. Meanwhile, due to low reservoir storage 

associated with below-normal precipitation levels and the need to reallocate 

water supplies to protect native fi sh species, the California Department of 

Water Resources reduced 2010 water deliveries (from Northern California) to 

users in the Bay-Delta and Southern California (including agriculture) by some 

800,000 acre-feet, or roughly half of normal allocations. In 2009, due to similar 

conditions, Southern California municipal and agricultural users of State Water 

Project water received only 40 percent of their normal allocations. Over the 

past 10 years, low reservoir storage and environmental fl ow demands across 

the Sacramento/San Joaquin Delta have limited water-supply deliveries to only 

68 percent of normal allocations from the State Water Project, impacting water 

for over 25 million Californians and approximately 750,000 acres of irrigated 

farmland (DWR, 2010a and 2010b).
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irrigated acreage for these crops. Chiu et al. (2009), in estimating the 

“embodied water in ethanol” (i.e., ethanol’s lifecycle water use), revealed that: 

1. More corn production for ethanol was taking place within highly 

irrigated regions, particularly in the northern High Plains (Ogallala 

Aquifer) region; 

2. Consumptive water use for bio-ethanol production in the United States 

increased 246 percent, from 1.54 to 4.95 maf, between 2005 and 2008; 

and 

3. Total consumptive water use for bio-ethanol production (including 

water for irrigation) in the Ogallala Aquifer region increased from 1.95 

maf in 2007 to 3.65 maf in 2008 (about 68 percent was supplied from 

groundwater).9

The National Research Council (2008) estimated that: 

1. Irrigated corn for ethanol (in Nebraska) required about 780 gallons of 

freshwater withdrawals per gallon of ethanol; and 

2. “While irrigation of native grass today would be unusual, this could 

easily change as cellulosic biofuel production gets underway.” 

The U.S. Government Accountability Offi ce (GAO) estimated the average 

water consumed in corn ethanol production (adjusting for irrigation return 

fl ows) for the Northern Plains States at 323.6 gallons of water per gallon of 

ethanol (U.S. GAO, 2009). Nearly 88 percent of this requirement is expected 

to come from groundwater.

The full impact of biofuel expansion on agricultural land and water resources, 

however, is expected to be complex, involving the substitution of land and 

water among crops, cropland expansion, reduced use of idled cropland, 

expanded use of applied inputs, and increased double-cropping (producing 

two crops on the same land within the same year), depending on where 

biofuel development occurs. Wallander et al. (2011) estimate that, since 

2006, corn production expansion to meet biofuel feedstock demand came 

primarily from acreage shifts from soybean farms (53 percent), conversion 

of uncultivated hay and grazing land, and acreage formerly enrolled under 

the USDA Conservation Reserve Program (CRP) (33 percent). Increases in 

corn yields and double-cropping, and decreases in idled cropland, accounted 

for the remainder.10 Production response has varied across regions; shifts in 

crop acreage from soybean to corn acres have been the dominant production response in the Corn Belt and Lake States regions, while expansion in 

harvested cropland from new cultivated land has dominated the Northern and 

Southern Plains and the lower Mississippi River Valley. 

Malcolm et al. (2009) drew similar conclusions regarding the impact of 

biofuel-sector growth on agricultural land-use decisions. Their estimates 

suggest that the substitution of soybean acres for corn acres would dominate 

cropland reallocation decisions across the Corn Belt, while expansion in 

harvested corn acreage (primarily from expired CRP contracts, pastureland, 

and idled cropland) explained a predicted increase in corn production in the 

Northern Plains. Based on a qualitative assessment, this research suggests 

that the expansion of corn acreage to meet biofuel feedstock demand has the 

9Consumptive water-use estimates 

by Chiu et al. (2009) were in trillions 

of liters but are converted here (for 

consistency) to acre-feet units based on 

3.7854 liters = 1 gallon and 325,851 

gallons = 1 acre-foot.

10Acreage shifts from soybean farms 

could have included acres from other 

crops besides soybeans. In addition, 

Wallander et al. (2011) did not evaluate 

irrigated crop and water-use effects.
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“potential for increased reliance on irrigation,” particularly for the Plains 

States. This would likely involve an increase in consumptive water use, both 

due to expanded irrigated corn acres and because water consumption by 

corn plants is greater than that for soybeans, placing additional pressure on 

groundwater resources where withdrawals have generally exceeded natural 

recharge. Increases in water demand for energy feedstock production could 

affect the long-term sustainability of surface and groundwater resources 

where they are currently under stress. 

Water demands are also expected to increase due to growth and technical 

innovation forecast in other energy-related uses, including thermoelectric 

generating capacity, expected development of utility-scale solar power across 

the Southwestern United States, and potential development of a commercial 

oil shale industry in the Upper Colorado River Basin. In addition, expansion 

of hydraulic fracturing (fracking) for deep shale natural gas exploration is 

expected to increase energy sector water demand in the Eastern and Central 

United States. Hydraulic fracking involves pumping water, sand, and chemicals under high pressure into a shale formation to generate fractures or cracks 

that allow natural gas to fl ow out of the rock and into the well. Water demand 

for hydraulic fracking does not represent a long-term water resource commitment, as it occurs only during the drilling and completion phases of each well 

(Chesapeake Energy, 2011). However, the practice has raised public concern 

for groundwater quality.

Increased use of evaporative cooling technology for thermoelectric and 

solar power may signifi cantly increase consumptive water-use requirements for the energy sector in areas where expansion occurs. Water demand 

for the oil shale industry could also be signifi cant; ongoing studies by the 

U.S. Department of the Interior address the uncertainties of water resource 

impacts for this sector. For most new energy development, however, water 

quality and environmental impacts are potentially the more signifi cant policy 

concern. Summarizing these water demands is outside the scope of this 

report due to the unique needs by energy type, the complexities of energy 

forecasts, technological uncertainties, and the lack of aggregate water-use 

estimates for projected energy expansion.11

Climate Change and Water Resources

Substantial evidence demonstrates that the global climate is changing, with 

important implications for agriculture and water resources (IPCC Report, 

2007; U.S. CCSP, 2008). In much of the Western United States, annual 

precipitation is projected to decline, particularly in the warmer summer 

months. Moreover, gradual temperature increases will shift the West’s traditional source of freshwater supplies from winter snowpack to more frequent 

and intense early spring rain (IPCC Report, 2007; Knowles et al., 2006). 

These shifts are expected to alter both the quantity and timing of associated 

streamfl ow, with more fl ow in the early spring, and to reduce late-season 

reservoir storage amounts from precipitation and late-spring and summer 

snowmelt. These streamfl ow and reservoir storage effects are expected to 

reduce water supplies for traditional peak irrigation water demands during 

the summer and fall growing seasons. 

11For more specifi c information on 

these water-use demands, see NETL, 

2008; GWPC and All Consulting, 2009; 

U.S. DOE, 2010; U.S. GAO, 2010; 

Bartis et al., 2005; U.S. BLM, 2011.
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Studies conducted for the Intergovernmental Panel on Climate Change’s 

(IPCC) Fourth Assessment Report (IPCC Report, 2007) revealed that: 

1. The April 1 snow-water equivalent snow cover “has declined 15 to 30 

percent since 1950 in the western mountains of North America” (Mote 

et al., 2003 and 2005; Lemke et al., 2007); and 

2. Streamfl ow over the last century has “decreased by about 2 percent per 

decade” in the Central Rocky Mountain region (Rood et al., 2005).

These studies indicated that these patterns were not uniform across the 

Mountain region and that, while there has been a general downward trend in 

snow-water equivalent snow across the Western States, decreases have been 

relatively larger at lower elevations. In addition, results from various climate 

simulation models or analyses based on multi-century tree-ring reconstruction (1490-1998) indicate that expected warming temperatures and precipitation changes will reduce streamfl ow in the Upper Colorado River Basin 

(UCRB). Streamfl ow could decline by 8-11 percent by the end of the 21st 

century, with declines as high as 25 percent by 2030 and 45 percent by 2060 

(Christensen and Lettenmaier, 2007; Hoerling and Eischeid, 2007; McCabe 

and Wolock, 2007).12

Van Kirk and Naman (2008) estimated that 39 percent of the observed 

decline in the July-October discharge for the Scott River within the Klamath 

Basin could be explained by regional-scale climatic factors. The U.S. Climate 

Change Science Program’s Final Report of Synthesis and Assessment 

Product 4.3 (U.S. CCSP, 2008), drawing on 2007 IPCC climate change 

assessments and other studies, revealed signifi cant regional differences in 

projected streamfl ow effects across the United States. The 2008 CCSP report 

projected that annual runoff would increase across the Eastern United States, 

gradually transition to little change in the Missouri and Lower Mississippi 

basins, and substantially decrease (by up to 20 percent) in the western interior 

(particularly the Colorado and Great Basin areas). Runoff projections for the 

West Coast (Pacifi c Northwest and California) were also negative, but smaller 

than in the western interior basins. The recent Bureau of Reclamation report 

to Congress (Reclamation, 2011) further disaggregated climatic impact and 

hydrologic projections to eight reclamation river basins. This study indicates 

that for the Colorado Basin, southern sub-basins are expected to experience 

greater warming and a decrease in precipitation; portions of the upper basin 

are expected to experience wetter conditions, but warming temperatures will 

dominate expected basin-wide effects. As a result, projected reductions in 

natural runoff and changes in runoff seasonality in the Colorado Basin are 

expected to reduce water supplies given current reservoir system capacity 

and operational regimes, with differences between northern and southern 

sub-basins. In addition, because reservoir storage opportunities are limited by 

fl ood control considerations, increased winter runoff is not expected to translate into increased water storage for the spring season. Reductions in runoff 

during the spring and early summer are expected to reduce reservoir levels 

and water supply deliveries during the irrigation season. 

The 2011 Reclamation report indicates that warming temperatures are 

expected to be relatively uniform over the Columbia River Basin, with generally wetter conditions varying across sub-basins. Decreases in snowpack 

are expected to be more substantial over the western mountain ranges of the 

12For information and maps of the 

major U.S. aquifer and river systems, 

see the U.S. Geological Survey (USGS) 

report for the Groundwater Atlas of the 

United States (USGS, 2011), which 

describes the location, extent, and the 

geologic and hydrologic characteristics 

of the major aquifers of the Nation, and 

the USGS Water Supply Paper 2294, 

Hydrologic Unit Maps (Seaber et al., 

1987), which provides descriptions, 

names, and drainage areas of the major 

U.S. river basin hydrologic units.
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basin and the lower elevations of the basin’s eastern mountain ranges, which 

“contribute signifi cantly to runoff in headwater reaches of major Columbia 

River tributaries.” Snowpack in northern and higher elevations of eastern 

portions of the basin, however, are projected to increase overall. These 

impacts are expected to result in varied annual runoff across sub-basins, 

with changes in the southern and central portions of the basin expected to 

be less than in the northern sub-basins. In addition, the seasonality of runoff 

becomes more important as warming temperatures in the northern sub-basins 

cause more of the runoff to occur during the December-March (cool) season 

and decrease runoff during the April-July (warmer) season. The southern 

and central sub-basins (e.g., the Snake and Yakima Rivers) are expected to 

see little change in April-July runoff as increased precipitation could offset 

the cool-season warming effect. The Reclamation report (2011) recognized 

that, for the Columbia Basin, the impact on water supply and reservoir operations is less obvious because of the anticipated variability in climatic effects 

across sub-basins. The report also recognizes that, based on some studies, the 

general warming effects across the basin appear to have the most infl uence on 

runoff and ultimately on basin water supplies.13

Other climate change studies indicate that, as increasing temperatures thin 

snowpack and raise snowline elevations, mountain recharge rates will decline 

as recharge areas shrink, thereby reducing aquifer recharge and water-table 

levels (Dettinger and Earman, 2007; Hall et al., 2008). For the Ogallala 

Aquifer region, groundwater recharge is expected to decrease by more 

than 20 percent if temperatures increase by 4.5o F (2.4o C) (IPCC Report, 

2007). Aquifer recharge rates could decrease by as much as 25 percent in 

the Ellensburg Basin of the Columbia Basin Plateau (NWAG Report, 2000). 

While these studies provide some initial information on how climate change 

may affect groundwater resources, these effects are not completely understood (USGS, 2009; Green et al., 2007). This uncertainty affects researchers’ 

ability to isolate climate change infl uences on the subsurface hydrologic 

cycle and their effect on such factors as recharge, discharge, and groundwater 

storage. These factors are infl uenced signifi cantly by groundwater-residence 

time—the time it takes climate variability and longrun climate change to 

affect a groundwater resource—which can range from days to tens of thousands of years. The longer the groundwater-residence time, the greater the 

challenge in detecting responses in groundwater supply due to climate variability and change.

Climate-induced declines in snowpack and altered runoff also create uncertainties involving the interactions between evapotranspiration (ET), mountain 

recharge versus alluvial (fan) basin recharge, and their combined effect on 

lower basin groundwater recharge (Dettinger and Earman, 2007). In addition, 

most groundwater systems have been altered substantially by human activities 

(Green et al., 2007). The USGS reports that improved groundwater-monitoring systems and an expanded research focus beyond groundwater-level 

fl uctuations to address groundwater uncertainties and processes occurring over multiple decades will enhance our understanding of groundwater 

response to climate change (USGS, 2009).14

Moderate temperature increases are also expected to increase crop ET for 

the southern-tier Western States, increasing irrigation water demands in the 

region, while enhancing ET effi ciency for many crops in the northern-tier 

13Summarizing results here for the 

Colorado and Columbia River Basins 

was intended to illustrate the variability 

in climate change impacts on surface 

water supply, both across and within 

basins. For more information on how 

projected climate change affects water 

supplies for other river basins, see the 

Reclamation report (U.S. BoR, 2011) at 

http://www.usbr.gov/climate/SECURE/

docs/SECUREWaterReport.pdf.

14The USGS and the U.S. 

Department of Agriculture (USDA), in 

conjunction with the United Nations 

project Groundwater Resources 

Assessment under the Pressures 

of Humanity and Climate Change 

(GRAPHIC), are assessing climate 

change effects on the High Plains 

Ogallala Aquifer (USGS, 2009).
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Western States.15 Even for northern-tier States, however, moderate warming 

conditions will likely still impact irrigation water demands because, with less 

total water supply, the timing of irrigation becomes a more critical onfarm 

water management issue. In the Eastern United States, where precipitation 

is generally suffi cient to support rainfed crop production, climate-induced 

changes in irrigation to meet water demands will depend on shifts in normal 

growing-season rainfall, potential increases in the frequency and severity of 

drought, and relative returns to irrigated and dryland production.

The Challenge for Agricultural Water Conservation

New pressures on regional water budgets, particularly in the Western States, 

have raised important questions concerning the sustainability of water 

resources for irrigated agriculture: 

1. Can irrigated agriculture adapt to climate-adjusted water supplies and 

emerging water demands through conventional means alone (i.e., the 

adoption of more effi cient irrigation technologies, improved water 

management practices, and/or cropland allocation shifts)? 

2. What changes in water institutions may be needed to complement and 

drive water conservation policy to more effectively manage increasingly scarce water supplies for agriculture? 

3. How will these changes impact irrigated agriculture, land and water 

resource use, the environment, and rural economies? 

Sustainability of U.S. Western Irrigated Agriculture

The critical link between climate change vulnerability and sustainability is 

adaptability (Wall and Smit, 2005; Hall et al., 2008; IPCC Report, 2007; 

Brekke et al., 2009).16 Reduced water supplies due to climate change will 

likely further constrain already over-allocated water resources across much 

of the Western United States, while increased water demand from alternative 

user groups, ecological requirements, and Native American claims will put 

additional pressure on water allocations. For agriculture, increased competition underscores the importance of managing irrigation applications (i.e., 

being capable of applying water at the time and in the amount needed to meet 

consumptive use requirements by crop growth stage). In addition, high-pressure sprinkler and traditional gravity irrigation systems will become even less 

effi cient as application losses increase due to higher evaporation rates caused 

by rising temperatures. 

Given current and projected climate changes, the adaptability of western irrigated agriculture to a more sustainable future could involve more widespread 

use of effi cient gravity and pressurized irrigation systems, coupled with intensive fi eld-level water management practices to enhance irrigation effi ciency 

and potential farm water savings. Such practices may include the use of soilor plant-moisture-sensing devices, commercial irrigation-scheduling services, 

and computer-based crop-growth simulation models that help producers 

decide when and how much to irrigate.

Practices that enhance gravity-fl ow systems through improved distributional 

uniformity of fi eld-water advance include fi eld laser leveling, gated pipe 

15Crop evapotranspiration (ET) is 

generally defi ned as the loss of water 

to the atmosphere through evaporation 

(from soil and plant leaf surfaces) 

and transpiration (water from inside 

the plant that vaporizes through plant 

stomata or microscopic pores on plant 

leaf surfaces). Crop ET-effi ciency, 

as used here, refers to the effect that 

rising temperatures have on crop 

yield per unit of water consumed in 

ET, alternatively recognized as crop 

water-use effi ciency (Izaurralde et al., 

2003; Hatfi eld et al., 2008; Bates et 

al., 2008). Rising temperatures are 

expected to reduce crop yield per unit 

of ET in the southern-tier Western 

States, while having a positive effect in 

the northern-tier Western States. 

16The terms “water conservation,” 

“sustainable water use,” and 

“adaptation” have been widely used 

in economic literature, but consistent 

defi nitions are somewhat elusive. For 

the purposes of this report, we defi ne 

sustainable irrigation water use as a 

goal of conservation policy—ensuring 

a viable irrigated agriculture sector and 

adequate agricultural water availability 

for future generations, while also 

protecting offsite environmental 

services. This defi nition is consistent 

with most USDA reports that address 

sustainable agriculture. Adaptation 

strategies involve various mechanisms 

for achieving agricultural water 

conservation and allocation goals.
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systems with surge fl ow/cablegation, shortened furrow lengths, alternate-row 

irrigations, reduced irrigation set times, and polyacrylamide (PAM) applications (a water-soluble soil amendment that stabilizes soil and waterborne 

sediment). Tailwater pits may also be used to capture and reuse irrigation 

drainage from the fi eld. Pressurized system enhancements, including lowenergy precision application/drop-tube systems, micro-irrigation systems, 

and automated nozzle control systems, improve the precision of applied water 

while reducing energy requirements for pressurization.

Under the more effi cient gravity and pressurized irrigation systems, intensive infi eld water management practices can enhance a producer’s ability to 

apply water closer to a crop’s consumptive use requirement. This is especially 

important when defi cit irrigating a crop to maximize profi ts, particularly 

during drought years. Defi cit irrigation is an applied water management 

strategy that concentrates the application of limited seasonal water supplies 

on moisture-sensitive crop growth stages to maximize the productivity of 

applied water. The quantity of water applied provides less than the full crop 

ET requirement, which inevitably results in plant moisture stress and reduced 

crop yield. With defi cit irrigation, however, the farmer’s goal is to maximize 

profi ts (net income) per unit of water used rather than per land unit used 

for production (Fereres and Soriano, 2007; Geerts and Raes, 2009). Thus, 

appropriately integrating water management practices with effi cient irrigation systems improves the adaptability of irrigated agriculture to water-supply 

defi cits, while enhancing longrun sustainability. 

Sustainability of U.S. Eastern Irrigated Agriculture

Conservation also ensures a more sustainable future for irrigated agriculture in the 31 Eastern States. In the more humid East, irrigation generally 

complements growing-season precipitation that normally provides suffi -

cient water to meet crop consumptive use requirements in average rainfall 

years. When precipitation during the crop-growing season falls short, some 

producers supplement with irrigation to meet crop water-use requirements.17

Historically, irrigated production has accounted for a small share of crop 

production in the Eastern States. Since the mid-1990s, however, crop irrigation has expanded signifi cantly across the East, increasing by nearly 20 

percent from 1998 to 2008 and by 15 percent since 2003 (USDA/NASS, 

2010).18 Irrigation has increased in the Eastern States primarily because of 

increases in commodity prices and yields, increased risk avoidance due to 

recurring drought conditions, and access to available groundwater supplies 

at relatively low cost due to shallow aquifer pumping depths (Midwest 

Irrigation, 2010; Fischer Farm Services, 2011; Evett et al., 2003; Vories and 

Evett, 2010). 

In 2008, nearly 79 percent of crop water applied in the Eastern States was 

pumped from shallow aquifers subject to annual recharge that also often 

serve as the primary source for downstream surface-water fl ows for nonagricultural uses (USDA/NASS, 2010; USGS, 2011). Less than 4 percent of the 

water for eastern irrigated agriculture has come from off-farm water sources. 

At the same time, population growth has increased water demand to meet the 

needs of urban/industrial growth and recreation, while changing social values 

have increased pressure for improved water quality and ecosystem services. 

Water supplies also have tightened in many eastern watersheds. Expanded 

17While all irrigation is supplemental 

to rainfed crop production, irrigation 

in humid regions is often referred to 

as supplemental (or complementary) 

within the scientifi c literature (Evans 

and Sadler, 2008; Clemmens et al., 

2008) because irrigation in humid 

regions is understood to be a “tactical 

measure to complement reasonably 

suffi cient rainfall and to stabilize 

production despite short-term droughts” 

(Evans and Sadler, 2008). 

18The largest irrigation increases in 

the East since 1998 have been in the 

Southeast (Georgia at 56 percent and 

Alabama at 60 percent), the Lower 

Mississippi Delta (Missouri at 48 

percent, Arkansas at 11 percent, and 

Mississippi at 31 percent), and the 

Upper Midwest (Minnesota at 57 

percent and Michigan at 45 percent).
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groundwater use for irrigated agriculture has contributed to declining aquifer 

water levels, rising pumping costs, and saltwater intrusion near coastal 

regions. The increasing importance of groundwater resources for nonagriculture uses, the lack of reliable surface-water supplies because of limited 

annual carryover storage capacity, rising irrigation pumping costs, and waterquality concerns from irrigation system losses have all heightened concerns 

for onfarm water conservation as a critical component of a sustainable irrigated agriculture sector in the Eastern States. As a result, advancing onfarm 

water conservation is as important throughout much of the 31 Eastern States 

as it is in the 17 Western States.
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How Important Is Irrigation

to U.S. Agriculture?

Nationwide, irrigated agriculture makes a signifi cant contribution to the 

value of U.S. agricultural production. In 2007, the market value of all agricultural products sold was $297.2 billion, with irrigated farms (farms with at 

least some irrigated cropland) accounting for roughly 40 percent of market 

sales, or $118.5 billion, and nonirrigated farms (farms not irrigating any 

cropland) accounting for the remainder (table 1). While the average per-farm 

value of agricultural products sold by all farms in 2007 was $143,835, the 

average value for irrigated farms was nearly 2.5 times higher, at $344,413. 

The average value of farm products sold by irrigated farms was 3.3 times the 

average value for nonirrigated (dryland) farms. 

Irrigation also contributes to the value of livestock and poultry products via 

irrigated crop production used as animal forage and feed. In 2007, the total 

value of crop products sold (including nursery and greenhouse crops) by irrigated farms was $78.3 billion, representing 54.5 percent of the value of crop 

sales by all farms (table 1). For irrigated farms only, the value of crop products sold accounted for nearly 67.0 percent of their agricultural sales in 2007, 

Table 1

Market value of agricultural products sold and farm production expenses for irrigated and nonirrigated 

farms, 2007

Irrigated farms

Farm characteristic All farms

All irrigated farms

 (mixed irrigated and 

dryland cropland)

Farms with all harvested 

irrigated cropland (no 

dryland cropland)

Dryland farms

(farms with no 

irrigated cropland)

Market value of agricultural 

products sold ($1,000) 297,220,491 118,510,873 65,333,520 178,709,618

Average per farm ($) 143,835 344,413 349,989 103,762

Crops, including nursery and 

greenhouse crops ($1,000)

 

143,657,928 78,297,158 46,872,638 65,360,770

Average per farm ($) 145,686 342,812 333,485 86,264

Livestock, poultry, and their 

products ($1,000) 153,562,563 40,213,715 18,460,881 113,348,848

Average per farm ($) 142,146 347,575 400,288 117,507

Total farm production expenses 

($1,000) 241,113,666 93,256,498 50,648,686 147,857,169

Average per farm ($) 109,359 309,793 309,041 77,666

Energy-related expenses 

(excluding custom work) 

($1,000) 18,829,794 8,145,691 4,500,636 10,684,103

Average per farm ($) 11,376 29,840 30,886 7,485

Source: USDA, National Agricultural Statistics Service, 2007 Census of Agriculture, 2009.
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with livestock products accounting for roughly a third of market sales.19 In 

general, nonirrigated farms were more dependent upon livestock and poultry 

sales; crop sales accounted for 36.6 percent of agricultural product sales in 

2007, while livestock/poultry sales accounted for 63.4 percent.

Where Does Irrigation Occur and What Does 

It Produce?

In 2007, 56.6 million farmland acres were irrigated across the United States 

(51.5 million acres of harvested cropland and 5.1 million acres of pastureland and other cropland), accounting for about 7.5 percent of all cropland 

and pastureland. About 16.6 percent of U.S. harvested cropland acres were 

irrigated, while only 1.2 percent of pastureland acres were irrigated (USDA/

NASS, 2009). Nearly three-quarters of U.S. irrigated agriculture occurred 

in the 17 contiguous Western States, including 73.0 percent of harvested irrigated cropland and 94.0 percent of irrigated pastureland. 

For 2007, 12 leading irrigation States accounted for 77.3 percent of all irrigated acres, including harvested cropland, pasture, and other lands (fi g. 3). 

Nebraska’s 8.6 million irrigated acres led all other States (15.1 percent of the 

U.S. total), followed by California with 8.0 million acres (14.2 percent), and 

Texas with 5.0 million acres (8.9 percent). Two Eastern States—Arkansas and 

Florida—were among the 12 leading irrigation States. Arkansas accounted 

for 4.5 million acres (7.9 percent) and Florida for 1.6 million acres (2.7 

percent) of total U.S. irrigated acres.

19The relative importance of irrigated 

forage and feed production varies 

across States. In California, irrigated 

forage acres (mostly alfalfa and hay) 

account for nearly 90 percent of acres 

devoted to irrigated forage and corn for 

grain production. In the Plains States, 

however, irrigated corn for grain acres 

dominate production acres for irrigated 

forage and corn for grain, ranging 

from 67 percent in Texas to 85 and 

92 percent in Kansas and Nebraska, 

respectively. We computed these 

statistics based on data from the 2007 

Census of Agriculture (USDA/NASS, 

2009).

Note: Twelve leading irrigation States (10 from the West, and Arkansas and Florida from 

the East) accounted for 77.3 percent of U.S. irrigated acres, including harvested cropland, 

pasture, and other lands.

Source: USDA, National Agricultural Statistics Service, 2007 Census of Agriculture, State 

data, 2009.

Figure 3

State shares of total U.S. irrigated acres, 2007

Nebraska

15.1%

California

14.2%

Texas

8.9%

Arkansas

Idaho 7.9%

5.8%

Colorado, 5.1%

Kansas, 4.9%

Montana, 3.6%

Oregon, 3.3%

Washington State, 3.1%

Florida, 2.7%

Wyoming, 2.7%

All other States

22.8 %
17

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Figure 4 illustrates the spatial distribution of irrigated acres in 2007, with 

each dot representing 10,000 acres (fi g. 5 identifi es States by USDA farm 

production region). Irrigated agriculture and water use are not static; some 

areas of use grow and some decline over time, infl uencing regional demands 

for water, energy, and other inputs. From 2002 to 2007, agricultural water 

use refl ected a net increase of nearly 1.3 million irrigated acres across the 

United States. Nebraska accounted for nearly a million of those additional 

acres, with lesser increases in Arkansas, Colorado, Mississippi, Missouri, and 

Georgia. Irrigated acreage expansion in these States was attributed to availability of water supplies, improved irrigation economics (partly due to higher 

crop yields and reduced water costs associated with more effi cient irrigation 

systems (USDA/NRCS, 2006)), increased biofuel demand for corn, recurring 

regional drought conditions, and the prospect of future restrictions on new 

irrigation development (at least for Nebraska).20 California and Florida led 

20Personal communication with 

Raymond J. Supalla, University of 

Nebraska – Lincoln, Agricultural 

Economics Department.

Source: USDA, National Agricultural Statistics Service, map # 07-M080, www.agcensus.usda.gov/Publications/2007/Online_Highlights/

Ag_Atlas_Maps/Farms/Land_in_Farms_and_Land_Use/07-M080-RGBDot1-largetext.pdf.

Figure 4

Acres of irrigated land, 2007

1 dot = 10,000 acres 

United States total

56,599,305

0 100

Miles 0 100

Miles

0 200

Miles
18

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among States where irrigated acres fell from 2002 to 2007, with declines of 

nearly 0.7 million acres and 0.3 million acres, respectively.21, 22

Figures 6 and 7 illustrate the longer term changes that have taken place since 

the early 1980s in irrigated acres and agricultural water applied, respectively, 

by farm production region. From 1982 to 1997, irrigated acres increased for 

most farm regions. Since 1997, however, most regions saw either a decline in 

irrigated acres or a slowing of irrigated expansion. The largest growth in irrigated acres since 1997 was concentrated in the Northern Plains, Delta, and 

Corn Belt regions, with more moderate expansion across the Eastern United 

States (except Florida). Growth rates in the Northern Plains (primarily 

Nebraska) pushed irrigated acreage (at 11.9 million acres in 2007) above 

acreage irrigated in the Pacifi c region (at 11.6 million acres). Similarly, since 

1997, irrigated acres in the Delta region surpassed acres irrigated in the 

Southern Plains. Over the same period, irrigated acres contracted in the relatively arid Mountain, Pacifi c, and Southern Plains regions. 

Agriculture in the Pacifi c region depended the most on irrigation, with more 

than half (53 percent) of cropland acreage irrigated in 2007. Other arid 

western regions with sizable concentrations of irrigated cropland include the 

Mountain (30 percent), Northern Plains (12 percent), and Southern Plains 

(12 percent) regions. In the Eastern States, irrigated acreage accounted for 

36 and 22 percent of cropland in the warmer Delta and Southeast regions, 

respectively, but less than 4 percent of cropland acreage in the middle- and 

northern-tier regions.

Although more acres were irrigated in the Mountain States than in the Pacifi c 

or Northern Plains States, agriculture in the Pacifi c region uses signifi cantly 

21Florida’s irrigated acres have been 

decreasing for a variety of reasons, 

including: (1) loss of irrigated acreages 

due to the reallocation of water supplies 

to restore the Florida Everglades 

ecosystem; (2) declining groundwater 

aquifer levels and saltwater intrusion; 

(3) loss of competitive markets; (4) 

urbanization; and (5) crop diseases 

(Aillery et al., 2001; USGS, 2008; 

Florida DEP, 2010).

22In California, irrigated acres 

have been declining due to: (1) 

increased use of pumping restrictions 

on water supplies from the San 

Francisco Bay-Delta Estuary to meet 

environmental regulations imposed 

to protect endangered species; (2) 

continued urban growth (although more 

recently at a slower pace due to current 

economic conditions); and (3) reduced 

soil productivity due to increasing 

salinity (particularly in the Imperial 

and San Joaquin Valleys). Recurring 

droughts have heightened water-supply 

pressures in California, resulting in 

signifi cantly increased Delta pumping 

restrictions and subsequent reductions 

in crop irrigated acres (Ayars, 2010; 

California Department of Conservation, 

2011).

1

The 17 Western States include those within the Northern Plains, Southern Plains, 

Mountain, and Pacific regions. The 31 Eastern States include those within the Lake, 

Corn Belt, Northeast, Appalachia, Delta, and Southeast regions.

Figure 5

USDA farm production regions1

Pacific Lake

Delta

Corn Belt

Mountain

Southeast

Northeast

Appalachia

Northern

Plains

Southern

Plains
19

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more water overall due to higher application rates (fi g. 7). Average per-acre 

fi eld-level water use for agriculture in the Pacifi c region was 2.76 acre-feet, 

compared with 1.85 acre-feet in the Mountain States. Differences refl ect 

regional variation in crop consumptive use requirements associated with 

climate and cropping pattern choices, as well as variation in the contribution of natural precipitation. Applied water rates are likely also infl uenced 

by differences in irrigation effi ciencies, water prices, and energy costs for 

irrigation pumping. Irrigated agriculture within the Pacifi c and Mountain 

States accounted for the largest share (65.0 percent) of total agricultural water 

applied across the United States.

What does irrigated agriculture produce? Irrigated agriculture accounts for 

a share of harvested acreage for most U.S. crops. For example, vegetable, 

orchard, and rice crops had the dominant share of their harvested acres irrigated in 2007: 70 percent of vegetable acres, 79 percent of orchards, and 100 

percent of rice (fi g. 8). For all other crops, irrigated acreage accounted for 

less than half of U.S. harvested acreage by crop, with shares ranging from 39 

percent for cotton to 5 percent for oats. 

Source: USDA, Economic Research Service calculations based on data from USDA, 

National Agricultural Statistics Service, 1982-2007 Censuses of Agriculture.

Total-Continental U.S. (1,000 acres) 

48,854

Figure 6

Irrigated acres by farm production region, 1982-2007

Acres (1,000)

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

Mountain

Pacific

Northern Plains

Delta

Cornbelt Lake States

Southern Plains

Northeast/Appalachia

Southeast

1982 1987 1992 1997 2002 2007

46,238 49,268 56,209 55,244 56,537
20

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Irrigated cropping patterns differ regionally across the United States. For the 

West, the cliché that “if a crop is not irrigated, it is not grown” is not universally true. For rice, peanuts, vegetables, and orchard crops, more than 80 

percent of each of their harvested cropland acres were irrigated in 2007 (fi g. 

9). Other crops grown in the West that relied heavily on irrigation included 

forage crops (31 percent of harvested acres), corn for grain (41 percent), 

cotton (43 percent), and sugarbeets (63 percent). As much as 75-95 percent of 

the harvested cropland acres for sorghum, soybeans, wheat, oats, and barley 

in the West were farmed using dryland production practices.

Figure 10 illustrates the relative distribution of 2007 harvested irrigated acres 

in the West by major crop category. Corn for grain and forage crops (hay, 

haylage, grass silage, and greenchop) accounted for about 52 percent of all 

harvested irrigated crop acres across the 17 Western States. Figure 11 shows 

the relative distribution of harvested irrigated acres for the 31 Eastern States 

in 2007. Corn for grain, soybeans, rice, and cotton accounted for 76 percent 

of all harvested irrigated crop acres in the East. Vegetables, along with 

orchards, vineyards, and nut trees, accounted for an additional 11 percent of 

Source: USDA, Economic Research Service calculations based on data from USDA, 

National Agricultural Statistics Service, 1984-2008 Farm and Ranch Irrigation Surveys.

Total-Continental U.S. (1,000 acre-feet) 

74,276

Figure 7

Agricultural water applied by farm production region, 1984-2008

Acre-feet (1,000) per year

Lake States

Northeast/

Appalachia

79,547 76,167 89,893 86,588 90,781

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

1984 1988 1994 1998 2003 2008

Mountain

Pacific

Northern Plains

Southern Plains

Southeast

Delta

Cornbelt
21

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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Source: USDA, National Agricultural Statistics Service, 2007 Census of Agriculture.

Figure 8

Share of U.S. total harvested cropland acres irrigated, all crops and by major crop category, 2007

Percent

Harvested

cropland

(all crops)

Sorghum

(for grain)

Wheat

(all)

Cotton

(all)

Sugarbeets

(for sugar)

Peanuts Orchards Forage

 (hay, haylage, 

grass silage, 

and greenchop)

Rice

Oats Vegetables All other

crops

Corn Barley

(for grain)

Soybeans

0

10

20

30

40

50

60

70

80

90

100

Source: USDA, National Agricultural Statistics Service, 2007 Census of Agriculture.

Figure 9

Share of total harvested cropland acres irrigated, by major crop category, for 17 Western States, 2007

Percent

Harvested

cropland

(all crops)

Sorghum

(for grain)

Wheat

(all)

Cotton

(all)

Sugarbeets

(for sugar)

Peanuts Orchards Forage

 (hay, haylage, 

grass silage, 

and greenchop)

Rice

Oats Vegetables All other

crops

Corn Barley

(for grain)

Soybeans

0

10

20

30

40

50

60

70

80

90

100
22

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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Source: USDA, National Agricultural Statistics Service, 2007 Census of Agriculture.

Figure 10

Distribution of harvested irrigated acres, by major crop category, 

for 17 Western States, 2007

Sorghum 

(for grain)

1.9%

Wheat (all)

8.4%

Cotton (all)

6.4%

Sugarbeets

(for sugar)

1.0% Peanuts

0.5%

Orchards

8.6%

Rice

1.8%

Oats

0.2%

Vegetables

5.9%

All other crops

6.2%

Barley

2.0%

Corn (for grain)

25.6%

Soybeans

5.1%

Forage (hay, haylage, 

grass silage, and 

greenchop)

26.5%

Source: USDA, National Agricultural Statistics Service, 2007 Census of Agriculture.

Figure 11

Distribution of harvested irrigated acres, by major crop category, 

for 31 Eastern States, 2007

Sorghum 

(for grain)

0.9%

Wheat (all)

1.6%

Peanuts

1.7%

Orchards, vineyards,

and nut trees

5.2%

Forage 

(hay, haylage, 

grass silage, 

and greenchop)

2.2%

Corn (for grain)

25.3%

Soybeans

23.7% Rice

14.9%

Cotton

11.8%

Vegetables

6.2%

All other 

crops

6.3%
23

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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irrigated harvested acreage. Relative to the Western States, the irrigated cropping pattern in the Eastern States refl ects a smaller share of irrigated acres for 

forage crops and wheat, and a larger share of irrigated acres devoted to rice 

and soybeans. 

How Much Water Is Applied, What Is Its Source, and 

What Does It Cost?

In 2008, irrigators across the Western States applied nearly 74.2 maf of 

water for irrigated cropland production, averaging about 2.1 acre-feet per 

irrigated acre overall (table 2). Much of this water (52.4 percent) originated 

from surface-water sources, with the remainder (47.7 percent) supplied from 

wells used to pump groundwater from local and regional aquifers. Surface 

water originates from both onfarm and off-farm sources.23 Onfarm surface 

water comes from onfarm ponds, lakes, or streams and rivers, accounting 

for roughly 15 percent of total agricultural water applied in the West, while 

off-farm water sources account for nearly 38 percent of total water applied. 

Water from off-farm sources is generally supplied to the farm through local 

irrigation districts; mutual, private, cooperative, or neighborhood waterdelivery “ditch” companies; or from commercial or municipal water systems. 

Applied water from groundwater sources in the West averaged about 1.4 acrefeet per irrigated acre in 2008 (table 2). In contrast, applied water averaged 

1.7 acre-feet per acre for onfarm surface water and 2.2 acre-feet per acre for 

off-farm surface water over the same period. These application differences 

likely refl ect the generally higher cost of groundwater and the fact that more 

off-farm surface water is applied to higher valued, more water-intensive 

crops. In addition, more effi cient systems are more likely to be used where 

23USDA’s 2008 Farm and Ranch 

Irrigation Survey (FRIS) is the most 

comprehensive source of nationally 

consistent information on irrigation 

water use and cost by water source 

(surface or groundwater). FRIS cost 

data include information on energy 

costs, irrigation repair and labor costs, 

and purchased water costs.

Table 2

Water application statistics for the 17 Western States, by type of irrigation and water source, 2008

Type of irrigation1

Total water 

applied 

(acre-feet)

Gravity 

systems 

(acre-feet)

Percent 

gravity

Sprinkler/driptrickle (pressure) 

systems 

(acre-feet)

Percent 

pressure

Other systems 

(sub-irrigation, 

miscellaneous, 

etc.) (acre-feet)

Percent 

other

Water applied 74,199,593 35,646,167 48.0 38,187,806 51.5 365,620 0.5

Average application 

(acre-feet/acre) 2.05 2.37 1.38

Water source1

Wells Surface water sources

Groundwater 

(wells) 

(acre-feet)

Percent 

groundwater

Onfarm surface 

water

(acre-feet)

Percent 

onfarm 

surface

Off-farm 

surface water 

(acre-feet)

Percent 

off-farm 

surface

Water applied 74,199,593 35,364,408 47.7 10,800,252 14.6 28,034,933 37.8

Average application 

(acre-feet/acre) 2.05 1.42 1.71 2.24 

1USDA, Economic Research Service calculations based on data from the USDA, National Agricultural Statistics Service, 2008 

Farm and Ranch Irrigation Survey.

Source: USDA, National Agricultural Statistics Service, 2008 Farm and Ranch Irrigation Survey, 2010.
24

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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groundwater is the primary water source. Center-pivot systems, for example, 

tend to be the more cost-effective system when drawing on groundwater. 

More than half (51.5 percent) of agricultural water for crop production in 

the Western States was applied using pressure-irrigation (sprinkler or driptrickle) systems, with the remainder applied with gravity irrigation systems.24

Application rates using gravity systems, which are generally less water-use 

effi cient and more likely associated with lower cost surface water, averaged 

about 2.4 acre-feet per acre, while rates for sprinkler/drip-trickle systems 

averaged about 1.4 acre-feet per irrigated acre.

With irrigated production, water is pumped from groundwater wells, surfacewater sources, or from water-delivery ditches (canals). Pumps are also used 

to pressurize fi eld-level sprinkler or drip/trickle irrigation systems. As a 

result, producers typically incur signifi cant expenses over and above normal 

crop production costs under nonirrigation production. Both capital (irrigation 

conveyance and distribution systems) and variable irrigation costs (depending 

on the quantity of water used) vary signifi cantly by region and across irrigated crops. These cost differences impact irrigation profi tability, which will 

fl uctuate based on available water sources, type of irrigation system used, 

crops irrigated, energy source used to power irrigation pumps, and water 

costs charged for off-farm water supplies.

In 2008, irrigated agriculture in the Western States incurred over $2.3 billion 

in energy expenses for onfarm pumping of irrigation water (table 3). Costs 

for pumping water from wells and for pressurizing irrigation systems averaged about $76 per irrigated acre, compared with about $38 per irrigated acre 

24For more information on gravity 

and pressure (sprinkler) irrigation 

systems, see Irrigation Systems and 

Land Treatment Practices at http://

www.ers.usda.gov/Briefi ng/WaterUse/

glossary.htm. 

Table 3

Irrigation cost statistics for the 17 Western States, by type of irrigation expense, 20081

Energy expenses for onfarm pumping

of irrigation water, by water source2

Total pumping expenditures Expenses per irrigated acre Irrigation maintenance and repair expenses

Water from 

wells

Surface 

water

Water from 

wells

Surface 

water Total expenditures Average cost per irrigated acre

$1,000 dollars Dollars per acre $1,000 dollars Dollars per acre

1,954,797 350,824 75.79 37.83 659,575 19.69

Irrigation labor costs by type (hired and contract labor) Purchased water costs for off-farm water supplies

Total expenses Average cost per 

irrigated acre Average cost

Hired labor Contract labor Hired labor Contract labor Total purchased water 

expenditures Per acre Per acre-foot

$1,000 dollars Dollars per acre $1,000 dollars Dollars per acre

748,620 121,384 33.26 20.16 671,491 66.28 23.95

1USDA, Economic Research Service calculations based on USDA, National Agricultural Statistics Service, 2008 Farm and 

Ranch Irrigation Survey.

2Includes expenditures for all energy sources (electric, natural gas, LP gas, propane, butane, diesel fuel, gasoline and gasohol), 

except for solar.

Source: USDA, National Agricultural Statistics Service, 2008 Farm and Ranch Irrigation Survey, 2010.
25

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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for water supplied from a surface source. Maintenance and repair costs for 

onfarm irrigation systems in the West totaled nearly $660 million (or $20 per 

irrigated acre). Irrigation labor costs totaled about $870 million ($749 million 

for hired labor and $121 million for contract labor). Hired labor averaged 

about $33 per irrigated acre, while contract labor averaged $20 per acre. In 

addition, irrigators using off-farm water supplies paid over $671 million for 

purchased water from irrigation districts and other off-farm water suppliers. 

Purchased water costs across the West averaged about $66 per irrigated acre, 

or $24 per acre-foot of water. However, total variable irrigation costs can vary 

signifi cantly across water sources. In 2008, variable irrigation costs across 

the West averaged about $91 per acre for a farm using onfarm surface water, 

$129 per acre for a farm pumping groundwater, and $144 per acre for a farm 

pumping purchased surface water and using contract labor. In the 31 Eastern 

States, average variable irrigation costs ranged from $65 to $75 per acre. 

Average costs were lower in Eastern States because groundwater pumping 

depths are generally shallower and purchased-water costs averaged less than 

$10 per acre, compared with $66 per acre in the West (purchased water from 

off-farm sources account for less than 4 percent of irrigation water supplies in 

Eastern States). 
26

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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How Effi cient Is Irrigated Agriculture?

Prior to the 1970s, gravity-fed furrow and fl ood irrigation systems were 

the dominant production systems for irrigated crop agriculture. By 1978, 

sprinkler irrigation, including center-pivot systems, accounted for about 35 

percent of crop irrigation in the Western States. Virtually all of this transition 

involved adoption of high-pressure sprinkler irrigation. While the center-pivot 

system improved fi eld irrigation effi ciency, water conservation was not the 

primary motivation for its widespread adoption. Other factors, such as yield 

enhancement from uniform water application and irrigation’s expansion into 

productive lands that were not suitable for a gravity system due to topography, 

soils, or distance from traditional riparian boundaries, were the primary 

drivers behind the early transition from gravity-fl ow irrigation to center-pivot 

sprinkler irrigation. 

The expansion of irrigated crop agriculture, along with increasing water 

demands from nonagricultural users, signifi cantly intensifi ed the competition for available water resources. At the same time, large-scale water supply 

enhancement was becoming more restricted for fi scal and environmental 

reasons. Water conservation in irrigated agriculture became an increasingly 

important focus of water policy to address water allocation concerns. Various 

water policy analyses as early as the late 1960s recognized the merits of new 

regulatory, conservation, and water market policies designed to mitigate water 

resource allocation confl icts (Gardner and Fullerton, 1968; Hamilton et al., 

1989; Hornbaker and Mapp, 1988; Howe, 1985; Martin, 1986; Moore, 1991; 

Schaible, 1997 and 2000; Peterson et al., 2003; Kim et al., 1989; Schaible and 

Aillery 2003). At the same time, producers receiving assistance from Federal 

and State resource conservation programs adopted more effi cient irrigation 

systems to improve irrigation returns, enhance the health and productivity of 

their resource base, and ensure a more sustainable future for their livelihoods.

Adoption of more effi cient irrigation systems and water management practices has been examined extensively, particularly within the 17 Western States 

(Schaible and Aillery, 2006; Schaible, 2004; Schaible et al., 2010). Figure 12 

illustrates that between 1984 and 2008 a substantial shift has occurred across 

the Western States away from gravity irrigation to pressure irrigation systems. 

In 1984, for example, 71 percent of all crop agricultural water in the West 

was applied using gravity irrigation systems. By 2008, operators used gravity 

systems to apply just 48 percent of water for crop production, while pressure 

irrigation systems accounted for 51.5 percent, or an increase of 23 percentage 

points from 1984. By 2008, much of the acreage in more effi cient pressure 

irrigation systems included drip, low-pressure sprinkler, or low-energy precision application systems. Improved pressure systems contributed to reduced 

agricultural water use, as fewer acre-feet were required to irrigate a greater 

number of acres using these systems. From 1984 to 2008, total irrigated acres 

across the West increased by 2.1 million acres, while total agricultural water 

applied declined by nearly 100,000 acre-feet.

Onfarm crop irrigation effi ciency is measured as the fraction of applied water 

benefi cially used by the crop, including the quantity of water required for 

crop ET (consumptive use) and water to leach salts from the crop root zone 

(Howell, 2003; Burt et al., 1997).25 Water applied to crops but not used for 

25This defi nition of crop irrigation 

effi ciency is conceptually consistent 

with Howell’s (2003) “seasonal 

irrigation effi ciency” and the “irrigation 

effi ciency” (IE) performance 

indicator presented by Burt et al. 

(1997). Depending upon the crop 

and region (and consistent with both 

references cited), crop benefi cial use 

may also include water for cooling 

or frost protection of plants, seed 

bed preparation, enhancement of 

seed germination, and to meet ET 

requirements for plants benefi cial 

to the crop, such as for herbaceous 

windbreaks and cover crops.
27

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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benefi cial purposes is generally regarded as fi eld loss, including water lost 

through excess evaporation and transpiration by noncropped biomass as well 

as surface runoff and percolation below the crop-root zone. Some portion of 

water loss to surface runoff and deep percolation may eventually return to the 

hydrologic system through surface return fl ow and/or aquifer recharge and 

may be available for other economic and environmental uses.

Improving onfarm irrigation effi ciency, while generally recognized as 

conserving water on the farm, may or may not conserve water within the 

watershed or river basin. What happens to irrigation water that leaves the 

farm (i.e., water not benefi cially consumed through crop production) and 

its ultimate impact on local or regional water supplies depend on the many 

factors that infl uence the hydrologic water balance for the watershed or river 

basin. Water balance accounts for where all the water within a watershed 

(or river basin) comes from and where it goes (fi g. 13) and is signifi cantly 

infl uenced by soils, plants, climate, water source, topography, and hydrologic characteristics both on and off the farm. The literature indicates that if 

conserved water at the watershed or river basin level is the important policy 

issue, then water conservation programs that emphasize onfarm irrigation 

effi ciency must consider the fate of applied irrigation water in a regional 

water-balance context. 

Several recent research papers discuss situations where improved onfarm 

irrigation effi ciency may or may not contribute to watershed or river basin 

water conservation (Clemmens et al., 2008; Evans and Sadler, 2008; Sadler 

et al., 2005; Fereres and Soriano, 2007; Geerts and Raes, 2009; CIT, 2011). 

The conservation potential of improved irrigation effi ciency refl ects the 

share of fi eld losses that are “irrecoverable” for additional uses in the basin 

Source: USDA, Economic Research Service calculations based on USDA, National Agricultural Statistics Service,1984, 1988, 

1994, 1998, 2003, and 2008 Farm and Ranch Irrigation Survey data.

Figure 12

Trends in irrigated acres and water applied, for Western States, 1984-2008

Million (acre-feet/acres)

0

20

40

60

80

1984 1988 1994 1998 2003 2008

Irrigated acres (gravity) Irrigated acres—pressure (sprinkler and drip/trickle)

Total water use

Gravity irrigation 

Pressure irrigation
28

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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(e.g., agricultural and nonagricultural diversions and environmental fl ows) 

or otherwise unusable (or detrimental) due to impaired water quality. These 

studies suggest that improved onfarm irrigation can conserve water beyond 

the farm by: 

1. Reducing unnecessary evaporation and unwanted transpiration, particularly by weeds and other noncropped biomass within waterlogged 

parts of irrigated fi elds, along water supply ditches and canals, and 

within and along irrigation drainage pathways; 

2. Improving rainfall use with precipitation capture and moisture retention techniques (e.g., land grading, snow fences, plant-row mulches, 

and furrow diking techniques); 

3. Reducing deep percolation water that becomes severely degraded in 

quality or is uneconomic to recover; 

4. Reducing fi eld runoff that is lost to the hydrologic system (i.e., runoff 

water that is not reusable because of salinization or entry to a saline 

body); 

5. Reducing crop ET requirements associated with downstream irrigated 

agriculture (i.e., by reducing saline return fl ows, which allows downstream irrigators to reduce their salt leaching requirements); and 

6. Reducing normal crop ET associated with crop stress under defi cit 

irrigation (i.e., the irrigator intentionally provides the crop with less 

than its full ET requirement, resulting in reduced yield but higher net 

economic returns). 

The research also indicates that, in many cases, conserved water to augment 

water supply in the watershed or river basin may not be the primary policy 

concern. Water conservation programs may also focus on enhancing the 

Source: Raymond J. Supalla, University of Nebraska – Lincoln, Agricultural 

Economics Department.

Figure 13

Fate of irrigation water

Upward flow

Rain Transpiration

Irrigation

Yield

Runoff

Evaporation

Deep percolation or drainage

Root

depth

Stored 

soil water

Groundwater
29

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viability and sustainability of the regional agricultural economy, improving 

the quality and availability of water supplies locally, improving the quality 

of return fl ows, and reducing environmental degradation of existing regional 

supplies. Numerous USGS National Water-Quality Assessment studies have 

identifi ed irrigated agriculture as a key contributor to many of the Nation’s 

degraded surface water bodies and groundwater aquifers because irrigation 

often makes heavier use of agricultural chemicals and because excess irrigation increases the hydrologic transport of agricultural chemicals, salts, and 

other soil-based chemicals potentially detrimental to water-based ecosystems (USGS, 2011). Thus, without adding to regional water supplies, water 

conservation programs encouraging improved onfarm irrigation effi ciency 

may purposefully serve local and regional economic, water-quality, and environmental goals that contribute to farmer and societal welfare, improve fi sh 

and wildlife habitat, and reduce ecosystem and human health risks associated 

with environmental pollution.

The potential for continued improvement in onfarm irrigation effi ciency to 

contribute to water-conservation program goals relies a great deal on how 

effi cient U.S. irrigated agriculture is today. Because actual irrigation water 

use is rarely measured and actual consumptive use can vary signifi cantly 

depending on agri-climatic conditions, the effi ciency of irrigated agriculture (based on the irrigation effi ciency defi nition discussed earlier) cannot 

be readily measured. An alternative measure of the relative effi ciency of 

irrigated agriculture demonstrated in Schaible (2004) is based on the relative shares of irrigated acres where water is applied using more effi cient 

(improved) irrigation systems, determined separately for gravity and pressure-sprinkler systems. 

Using farm-level data from USDA’s Farm and Ranch Irrigation Survey 

(FRIS) (USDA/NASS, 1994-2008), we categorized irrigated acres as either 

“traditional” or “more effi cient” irrigation. More effi cient gravity irrigation 

includes furrow gravity irrigated acres using an above- or below-ground pipe 

or a lined open-ditch fi eld water-delivery system, plus acres in fl ood irrigation (between borders or within basins) on farms using laser-leveling and pipe 

or lined open-ditch fi eld water-delivery systems. More-effi cient (improved) 

pressure-sprinkler irrigation includes acres irrigated using either drip/trickle 

systems or lower pressure-sprinkler systems (pressure per square-inch (PSI) 

<30). Both improved gravity and pressure-sprinkler irrigation systems 

increase the uniformity of water distribution across a fi eld, reduce fi eld runoff 

and aquifer-seepage losses, reduce evaporation losses, and enhance crop 

yields.

Figure 14 illustrates the use of more effi cient irrigation (separately for gravity 

and pressure-sprinkler systems) as a percent of total acres irrigated for the 

17 Western States for 1994, 1998, 2003, and 2008. Between 1994 and 1998, 

the share of Western irrigated acres using improved gravity-fl ow systems 

increased from 21 to 25 percent. During the same time period, the share of 

irrigated acres using improved pressure-sprinkler irrigation also increased 

and accounted for about 23 percent of total irrigated acres in 1998. Thus, 

more effi cient irrigation in 1998 (based on a physical system-based defi nition, 

unadjusted for levels of onfarm water management) accounted for about 49 

percent of irrigation in the West. From 1998 to 2008, however, the share of 

gravity-fl ow irrigated acres using improved gravity systems declined. At the 
30

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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same time, improved pressure-sprinkler irrigated acres continued to increase, 

although at a slower rate than in the earlier period. These shifts likely suggest 

that a slowing of the transition from traditional gravity-fl ow irrigation to 

improved pressure-sprinkler irrigation may be attributable to thresholds 

beyond which conservation policy incentives for gravity-to-sprinkler system 

transfers may be less effective.26 While substantial technological innovation 

has already occurred in western irrigated agriculture, signifi cant room for 

improvement in farm irrigation effi ciency still exists; traditional gravity or 

less effi cient pressure-sprinkler systems still account for over 50 percent of 

irrigated acres. The historical transitions suggest that, while western irrigated 

agriculture is on a path toward greater sustainability, further progress will 

likely be needed as water demand and supply conditions change. 

Similar conditions exist for irrigated agriculture across the 31 Eastern States. 

More effi cient pressure (sprinkler) and gravity systems account for 52 percent 

of total farm irrigated acres in the Eastern States. But the remaining 48 

percent of eastern irrigated acres are irrigated with traditional, less effi cient 

systems. For the 31 Eastern States, however, improved gravity systems (at 32 

percent of total irrigated acres) play the dominant role among more effi cient 

irrigation systems relative to the West, where improved pressure (sprinkler) 

systems account for more than 30 percent of irrigated acres. This regional 

difference should not be surprising given the predominance of gravity irrigation across the Eastern States.27

Despite the increased use of more effi cient irrigation systems, pressures to 

reallocate agricultural water supplies among competing demands continue 

to impact the sector. Adopting more effi cient physical systems alone may 

26For some producers, irrigation 

technology is considered a quasifi xed input because various barriers 

(e.g., limited producer management 

skills, lack of fi nancial resources, 

producer age, farm size, unique soil 

or agri-environmental conditions, or 

other reasons) discourage adoption 

of improved irrigation technologies. 

For example, high mountain-meadow 

pastures are often irrigated with 

gravity-based, unlined ditch waterdelivery systems. With a high-priority 

water right and relatively low water 

costs, such producers are unlikely to 

alter their irrigation technology without 

increased incentive to do so (Schaible 

et al., 2010).

27While irrigation with gravity 

systems occurs in most Eastern States, 

5 States (Arkansas, Florida, Louisiana, 

Mississippi, and Missouri) account 

for 98 percent of all gravity-irrigated 

acres within the 31 Eastern States. 

Arkansas alone accounts for 53 percent 

of gravity-irrigated acres in the Eastern 

States. These 5 States account for 69 

percent of total irrigated acres for the 

Eastern States.

Notes: More efficient gravity irrigation includes furrow irrigated acres using above- or 

below-ground pipe or a lined open-ditch field water-delivery system, plus acres in flood 

irrigation (between borders or within basins) on farms using laser-leveling and pipe or lined 

open-ditch field water-delivery systems. More efficient pressure-sprinkler irrigation includes 

acres using either drip/trickle systems or lower pressure-sprinkler systems (pressure per 

square-inch (PSI) < 30). The remaining irrigated acres were categorized as using 

"traditional" irrigation systems.

Source: USDA, National Agricultural Statistics Service, 1994, 1998, 2003, and 2008 Farm 

and Ranch Irrigation Survey.

Figure 14

Share of irrigated acres in the 17 Western States, by system type, 

1994-2008

Percent of total irrigated acres

0

10

20

30

40

50

60

70

80

90

100

1994 1998 2003 2008

Efficient gravity 

irrigated acres

Efficient sprinkler and 

drip/trickle irrigated acres

Traditional

irrigated acres
31

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not be enough in the face of greater demands placed on increasingly scarce 

water resources, especially with new demands from climate change and 

an expanding energy sector. The sustainability of irrigated agriculture 

may depend increasingly on expanded adoption of more effi cient irrigation 

“production systems” (Evans and Sadler, 2008; Sadler et al., 2005; Clemmens 

et al., 2008). These production systems could involve a continued shift from 

traditional, less effi cient gravity/sprinkler irrigation to the more effi cient 

irrigation application systems, but with greater reliance on “within-system” 

water management improvements that increase overall production effi ciency 

beyond that attainable with an improved gravity or pressure-sprinkler application system alone.28

To increase the effi cient use of water resources, irrigation production systems 

could incorporate more intensive use of infi eld water management practices 

(e.g., soil- or plant-moisture sensing devices, commercial irrigation scheduling services, or computer-based crop-growth simulation models) that help 

farmers decide when to irrigate and how much water to use by crop growth 

stage (Schaible et al., 2010). Improved water management practices can 

help producers maximize the economic effi ciency of their irrigation systems 

and the potential for real water savings through reduced system losses and 

managed reductions in crop consumptive use.

For irrigated agriculture, in general, and for gravity irrigation, in particular, 

survey data suggest that producers do not make widespread use of less waterintensive infi eld water management practices. Across the West, producers 

using gravity-fl ow irrigation tend to give more emphasis to such practices as 

reduced irrigation set times, alternate furrow irrigation (for row crops), and 

end-of-fi eld dikes to restrict fi eld runoff (table 4). Other less water-use intensive management practices for gravity systems have declined in use or have 

received little producer attention. Use of tailwater pits for onfarm water reuse 

(reducing the need for additional withdrawals) has declined across gravity 

irrigation, from 22 percent in 1994 to 8 percent in 2008, partly in response to 

irrigation application improvements that limit fi eld runoff. Laser-leveled acres 

on gravity irrigated fi elds declined from 27 percent of acreage in 1998 to 16 

percent in 2008. 

By 2008, less water-intensive gravity-management practices, such as special 

furrowing techniques, shortened furrow lengths, and polyacrylamide (PAM), 

were applied on a relatively small portion of gravity-irrigated agriculture in 

the West. Less interest in these practices may refl ect their expected economic 

impact at the farm level, either through increased costs for land preparation 

or for specialized furrow-management equipment, particularly when expected 

profi t margins are low. Across the Eastern States, however, producers tend 

to give more emphasis to alternate row irrigation and laser-leveling of fi elds 

to improve water management on gravity-irrigated acres (accounting for 11 

and 22 percent of gravity irrigated acres, respectively). As in the West, use of 

effi ciency-enhancing gravity water management practices accounts for a relatively small portion of gravity irrigated acres.

 Despite technological advances in crop and soil moisture sensing, irrigators 

across the United States continue to depend heavily on traditional decisionmaking methods in deciding when to irrigate a crop and by how much. In 

the West, most producers generally irrigate based on the visible “condition 

28The sustainability of irrigated 

agriculture also could be enhanced 

through continued research and 

development of crop cultivars with 

improved tolerance to drought, heat, 

and salts, as well as shorter growing 

seasons. This particular issue is beyond 

the focus of this report.
32

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Table 4

Water management practices in the 17 Western States, 1984-2008

Methods/practices 1984 1988 1994 1998 2003 2008

Total number of irrigated farms 179,473 180,525 149,351 147,090 174,936 169,985

Total gravity irrigated acres 24,084,966 22,731,136 20,344,444 19,164,703 16,491,380 15,023,307

Methods used in deciding when to irrigate: Percent of irrigated farms

Use of any method (including one or more 

of the decision methods below): 0.96 0.94 0.96 0.99 1.00 1.00

Condition of the crop 0.26 0.69 0.66 0.70 0.77 0.84

Feel of the soil1 0.40 0.36 0.37 0.40 0.34 0.42

Use of soil moisture sensing devices 0.08 0.08 0.09 0.08 0.07 0.09

Use of commercial scheduling services 0.03 0.05 0.03 0.04 0.07 0.09

Use of media reports on daily 

crop ET 0.04 0.04 0.03 0.05 0.08 0.10

Based on scheduled water delivery 

“in turn” to the farm 0.13 0.13 0.18 0.12 0.15 0.14

Based on a calendar schedule 0.18 0.18 0.20 0.20 0.21 0.27

Use of computer simulation models NA NA 0.03 0.01 0.00 0.01

Use of plant moisture sensing devices NA NA NA NA 0.02 0.02

Irrigate when the neighbors do NA NA NA NA 0.07 0.07

Water management practices used with 

gravity-fl ow irrigation systems: Percent of gravity-irrigated acres

Tailwater pits NA 0.20 0.22 0.12 0.08 0.08

Surgefl ow/cablegation irrigation2 NA 0.05 0.04 0.04 0.02 0.02

Special furrowing techniques3 NA 0.12 0.12 0.06 0.06 0.05

Reducing irrigation set times or number 

of irrigations NA NA 0.13 0.13 0.15 0.15

Using alternate row irrigations NA NA 0.17 0.15 0.12 0.10

Use of polyacrylamide (PAM) NA NA NA 0.02 0.02 0.02

Restricting runoff by diking end of fi eld NA NA NA NA 0.13 0.15

Use of mulch or other type of row cover NA NA NA NA 0.01 0.01

Laser-leveled acres NA 0.10 0.21 0.27 0.16 0.16

ET=Evapotranspiration.

NA = Not Available. FRIS surveys did not collect data for all decision methods or water management practices for all years.

1The practice of evaluating when to irrigate by physically feeling the soil to estimate its moisture content.

2Surge fl ow is an adaptation of gated-pipe systems whereby water is delivered to the furrow in timed releases controlled by a valve. Furrows 

are alternately wetted and allowed to dry. As the soil dries, the soil surface forms a water seal permitting the next surge of water to travel further down the furrow with less upslope deep percolation. Cablegation is a gated-pipe system in which a moveable plug is allowed to slowly pass 

through a long section of gated pipe, with the rate of movement controlled by a cable and brake. The system is designed such that water fl ow 

will gradually cease fl owing into the fi rst rows irrigated after the plug has progressed suffi ciently far down the pipe. Improved water management 

is achieved by varying the speed of the plug, which controls the timing of water fl ows into each furrow.

3Special furrowing techniques may include using wide-spaced bed furrows, compact furrowing, furrow diking, or shortening of the furrow length.

Source: USDA, National Agricultural Statistics Service, 1984, 1988, 1994, 1998, 2003, and 2008 Farm and Ranch Irrigation Survey. 
33

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of the crop” or by “feeling the soil” for soil-moisture content, or irrigation 

may be based on a calendar schedule (which can be infl uenced by labor availability from local labor markets) or an “in-turn” (fi xed rotation) delivery 

schedule for water supplied to the farm (see table 4). For 2008, fewer than 10 

percent of irrigators throughout the West used soil- or plant-moisture sensing 

devices or commercial irrigation scheduling services. Fewer than 2 percent 

of irrigators used computer-based simulation models to evaluate crop irrigation requirements based on consumptive use needs by crop-growth stage and 

local weather conditions. Low adoption rates may be due to the fact that these 

practices are much more human-capital and management intensive than traditional water-application decision tools. These more sophisticated tools may 

require more extensive technical training and support to increase adoption 

rates.

Similar relationships exist for the Eastern States, except that irrigation decisions generally are not based on water delivered within a fi xed rotation to the 

farm. While 14 percent of irrigators in the West reported that water delivered 

within a fi xed farm rotation infl uenced their decisions on when to irrigate, 

less than 1 percent of irrigators in the Eastern States relied on this arrangement. The decisionmaking process varies by region and refl ects the fact that, 

in the West, 33 percent of irrigated acres used water from off-farm sources, 

generally from irrigation districts, while in the East, less than 4 percent of 

irrigated acres used off-farm water sources.

According to the 2008 FRIS, at least half of irrigated crop acreage across 

the United States continues to be irrigated with less effi cient irrigation application systems and most irrigators do not make use of less water-intensive 

onfarm water management practices. Our fi ndings suggest that, particularly 

for the West, given the increasing water demand pressures from competing 

uses, the potential for reduced water supplies and increased evaporation 

losses associated with climate change, a sustainable future for irrigated agriculture may require wider adoption of more effi cient irrigation practices. 

According to the National Research Council report, Toward Sustainable 

Agricultural Systems in the 21st Century (NRC, 2010), and the recent USDA 

Research, Education, and Economics Action Plan (USDA/REE, 2012),29

achieving a more sustainable future for irrigated agriculture through agricultural water conservation involves three elements:

• Continue to encourage adoption of high-effi ciency irrigation application systems; 

• Place greater emphasis on adoption of more effi cient irrigation production systems (a farming systems approach) that better manage when 

and how much water is applied at the fi eld level, enhancing producer 

ability to respond to water shortages as well as promote agricultural 

water conservation through defi cit irrigation while improving farm 

profi ts; and 

• Better integrate onfarm water conservation with watershed-level 

water management mechanisms that help facilitate optimal allocation of limited water supplies among competing demands (e.g., use 

of conserved water rights, drought-year water banks, water-option 

markets, contingent water markets, reservoir management, irrigated 

29“Sustainable agriculture” as a 

USDA policy goal was initiated with 

the Food, Agriculture, Conservation, 

and Trade Act of 1990, with the key 

objective to “protect and enhance 

America’s water resources.” USDA’s 

Strategic Plan for FY 2010-15 

highlights the importance of using 

farm-level, watershed, and institutional 

measures as a strategic means to meet 

this goal (USDA, 2012).
34

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acreage and groundwater pumping restrictions, and irrigated acreage 

retirement).

The box “Irrigation Production Systems and Agricultural Water 

Conservation” expands upon the concept of accounting for basin-level water 

balance by considering the fate of farm-level water savings/losses and strategies underway to improve onfarm irrigation water-use effi ciency and integrate 

water conservation and watershed water-management tools.

Watershed-level water management tools can create more effi cient water 

allocations by encouraging water-resource stakeholders to recognize the 

opportunity value of water across competing uses and by facilitating water 

transfers through varying degrees of market-based trading and reallocation schemes. USDA presently participates in watershed-scale agricultural 

water conservation and water-management activities through Federal, State, 

and local partnership agreements established under its Agricultural Water 

Enhancement Program (AWEP). With the 2008 Food, Conservation, and 

Energy Act’s establishment of AWEP, USDA’s water conservation program 

was effectively extended to embody a focus on farms as well as on a watershed/regional/institutional conservation. Since 2009, USDA’s Natural 

Resources Conservation Service, (NRCS) has entered into 101 AWEP partnership agreements designed to enhance agricultural water conservation.30

AWEP allows USDA to integrate onfarm water conservation with institutional and watershed water-management tools to enhance water conservation 

objectives at a “landscape scale,” while leveraging fi nancial support from 

other Federal, State, and local organizations. The box, “Institutional Tools for 

Water Management,” presents examples of policy approaches being used to 

encourage and enhance agricultural water conservation. 

30With the AWEP, under the 

Environmental Quality Incentives 

Program (EQIP), USDA’s NRCS 

presently manages multi-year 

watershed-level water conservation 

partnership agreements with State, 

local, irrigation district, federally 

recognized Indian Tribes, and 

nongovernmental organizations. The 

complexity of these partnerships 

can range from providing producers 

fi nancial assistance to convert from 

gravity irrigation to low-pressure 

sprinkler irrigation, to using irrigated 

acreage and water-use restrictions 

and conserved water for instream 

fl ow uses and managed drought-year 

water banks. NRCS partnership 

agreements and water management 

mechanisms can vary signifi cantly 

across watersheds and States. For 

a description of AWEP partnership 

agreements, see http://www.nrcs.usda.

gov/wps/portal/nrcs/detailfull/national/

programs/?&cid=nrcs143_008334. 
35

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Irrigation Production Systems and Agricultural 

Water Conservation

Agricultural water conservation has long been recognized as key to providing 

water resources to meet the increasing demands of competing uses. Historically, 

promoting producer adoption of irrigation technologies that increase farmlevel irrigation effi ciency has been a principal policy focus. Through the 

use of conservation-incentive programs, Federal and State agencies have 

funded improvements in irrigation system effi ciency to help meet the needs 

of competing water demands. In recent years, however, the appropriateness of 

this policy approach has been challenged. Concerns have been raised about the 

effect of irrigation technology adoption on irrigation consumptive water use 

and the amount of water actually “conserved.” 

Researchers believe that public promotion of more effi cient irrigation 

technologies can unintentionally increase irrigated crop consumptive water 

use at the basin level by encouraging wider adoption of crop irrigation and/or 

the production of more water-intensive crops (Whittlesey and Huffaker, 1995; 

Huffaker and Whittlesey, 2003; Ward and Pulido, 2008; Clemmens et al., 

2008; Evans and Sadler, 2008). This policy concern suggests that improving 

irrigation effi ciency may not always “conserve” water for off-farm uses. The 

potential of irrigation effi ciency improvements to achieve water savings within 

a basin depends partly on the nature of irrigation system losses and rates of 

irrigation return fl ow to surface streams and aquifers. Potential water savings 

also depend on whether water-use effi ciency gains are offset by increases 

in crop consumptive water use. Where return fl ows are high from irrigation 

systems, real water conservation may require reduced crop consumptive water 

use within the basin.

Improved Technology Alone May Not Be Enough. Producer adoption of more 

effi cient irrigation technology may increase agricultural water consumption in 

several ways. 

1. More effi cient irrigation systems allow the producer to reduce the quantity of water applied to a fi eld, often through improved uniformity of 

fi eld-water distribution and timing of water applications to meet crop 

growth-stage requirements. These improvements may also result in 

higher crop yields, which generally increase crop consumptive water use. 

2. In the absence of defi ned “conserved” water rights, water savings from 

irrigation effi ciency improvements on one fi eld may be applied to additional crop acreage under irrigation. Unless restricted, “water spreading” 

over an expanded acreage base generally increases aggregate agricultural water consumption. 

3. Improved irrigation technologies can alter the economics of irrigation enough to entice producers to adjust traditional cropping patterns, 

potentially shifting to more water-intensive irrigated crops. In the High 

Plains, for example, higher yields and reduced irrigation pumping costs 

with improved irrigation effi ciency have prompted a shift from irrigated 

wheat and sorghum production to increased acreage in irrigated corn. 

These types of cropping pattern adjustments may increase aggregate 

crop consumptive water use. 

Improved irrigation effi ciency can also have off-farm implications. Specifi cally, 

upstream water savings may be claimed by downstream (junior water-right) 

irrigators, increasing basin-wide agricultural consumptive water use. Where

--continued
36

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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Irrigation Production Systems and Agricultural 

Water Conservation (continued)

seasonal instream water fl ows are limiting, increases in crop consumptive 

water use may adversely impact water allocation objectives for environmental 

and other purposes at the basin level. Similarly, groundwater savings from 

reduced irrigation pumping requirements under high-effi ciency systems may 

be offset by expanded aquifer withdrawals for additional irrigated acreage and 

other purposes off the farm.

Benefi ts of Technological Improvements. While the effects of irrigation 

effi ciency on crop consumptive use and net water savings are an important 

policy concern, investment in more effi cient onfarm irrigation technologies has 

additional benefi ts. 

1. Improved irrigation technologies are generally productivity enhancing, 

requiring less land and water inputs for a given level of yield. 

2. Enhanced irrigation effi ciency produces onfarm water savings through 

reduced applications that also reduce farm water costs (Evans and Sadler, 

2008; Sadler et al., 2005; Fereres and Soriano, 2007; Geerts and Raes, 

2009). Higher productivity and reduced water costs are important to the 

economic viability of a sustainable irrigated agriculture sector over the 

long term. 

3. Improved onfarm irrigation effi ciency generally results in signifi cant 

water quality and environmental benefi ts (Huffaker, 2010; Kim et al., 

2000; Schaible and Aillery, 2003; Weinberg et al., 1993). Effi cient irrigation “production systems” allow producers to improve their nutrient 

management practices through chemical application effi ciencies, reduced 

soil erosion runoff, improved salinity control, and improved drainage 

water quality. Improving onfarm irrigation effi ciency also reduces nutrient 

loads, pesticides, and trace elements in irrigation runoff to surface waters, 

as well as leaching of agrichemicals into groundwater supplies, producing 

off-farm benefi ts for ecosystem habitats, endangered species recovery, 

biodiversity, and human health.

Broadening Policy Focus To Achieve Conservation Goals. Public water 

conservation programs that encourage producer adoption of effi cient “irrigation 

production systems,” integrated within basin-level institutional water 

management initiatives (e.g., conserved water-right provisions, groundwater 

withdrawal restrictions, water banks, and option and contingent water markets), 

could enhance the potential for real agricultural water conservation. Integrated 

farm and basin-level institutional conservation initiatives could encourage 

both irrigators and conservation program managers to consider the alternative 

opportunity values of water across competing demands, improving allocation 

of scarce water resources. In doing so, irrigation effi ciency improvements, 

as part of a broader basin-level conservation plan, may be combined with 

other practices, such as defi cit irrigation, acreage idling, and off-farm water 

transfers, that reduce crop water consumption in water-defi cit years while 

allowing producers to maximize farm income. Through the adoption of highly 

effi cient irrigation production systems, in combination with water allocation 

frameworks that encourage producers and program managers to jointly 

consider the opportunity values of water within the basin, the overall effi ciency 

in water allocations can be improved while enhancing real agricultural water 

conservation. 
37

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Institutional Tools for Water Management

Agricultural water conservation can enhance crop production and farm 

income, as well as water resources for competing demands, where institutional 

provisions provide appropriate incentives for the allocation of conserved water. 

USDA’s Agricultural Water Enhancement Program—under the Environmental 

Quality Incentive Program (EQIP)—is one approach within a broader 

partnership-based institutional framework that provides fi nancial assistance to 

agricultural producers to implement agricultural water enhancement activities 

on agricultural land to conserve surface and groundwater and to improve water 

quality. Various institutional provisions at the Federal and State level help 

promote potential water savings from onfarm investments in improved irrigation 

production systems. Integrating onfarm water conservation programs with 

institutional water management mechanisms can encourage the reallocation 

of conserved water to meet off-farm uses for environmental fl ows and other 

higher valued water demands, both agricultural and nonagricultural. Examples 

of how onfarm water conservation has been integrated with institutional water 

management measures include: 

• EQIP fi nancial assistance provisions. By allocating Federal funds for 

irrigation technology investments, EQIP program managers at the State 

(or sub-State) level may assign priority to contract offers demonstrating 

net water savings at the farm level. Financial assistance for irrigation 

technology improvements may also be combined with environmental 

measures that limit agricultural water withdrawals. For example, in a 

special EQIP project in south-central Nebraska where groundwater 

pumping has affected Platte River fl ows for endangered species, fi nancial assistance for conversion to high-effi ciency sprinkler systems was 

tied to restrictions on irrigated acreage expansion. 

• Groundwater management. States may enact groundwater management 

regulations that promote adoption of improved irrigation technology. In 

Arizona, where groundwater withdrawals for agricultural production 

have resulted in signifi cant water-table declines, groundwater management areas have been established to limit groundwater overdraft. Under 

the groundwater management provisions, agricultural water conservation programs were established for designated groundwater management areas. Irrigation withdrawals for farms within these areas are tied 

to successively higher irrigation effi ciency levels. Compliance with an 

approved set of best management practices for irrigated production may 

be accepted in lieu of fi xed groundwater withdrawals.

• Environmental fl ow regulations. Federal and State regulatory requirements for environmental fl ows may be combined with policy initiatives for water conservation. The Central Valley Project Improvement 

Act (CVPIA) of 1992, which reallocated farm water deliveries to meet 

instream fl ow requirements, mandated water conservation programs at 

the irrigation district level. In 2001, severe drought in the Klamath River 

Basin (California and Oregon) prompted Federal regulatory restrictions 

on agricultural water diversions to ensure fl ows for endangered fi sh 

species. The Federal action resulted in a special USDA EQIP funding 

allocation to support improved irrigation systems in the Klamath River 

Basin under the 2002 Farm Act. 

--continued
38

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Institutional Tools for Water Management

(continued)

• Incentive pricing for surface water. Current prices for surface irrigation water may not refl ect the market value of water. In many cases, 

water charges are tied to some portion of the capital and maintenance costs of the delivery system and often do not refl ect the value 

of water in irrigation or its opportunity cost in other uses. With 

tiered pricing for surface water deliveries, per-unit costs increase (in 

a stepped fashion) with the volume of water delivered. The CVPIA 

established tiered water pricing for agricultural diversions at the irrigation district level in California’s Central Valley Project. Individual 

irrigation districts may decide whether or not to implement tiered 

pricing (using a modifi ed schedule or alternative rate to cover the 

increased costs of water they receive from the Bureau of Reclamation 

project) for their respective producers (CBO, 1997). Producers may 

lessen their average per-unit water charge by adopting higher effi -

ciency irrigation systems that reduce total farm water diversions. 

• Water markets. Water markets can improve the allocation of water 

among competing economic uses by facilitating the voluntary transfer 

of water to higher valued uses under sale or lease agreements. Water 

markets can encourage investment in more effi cient irrigation technologies through improved market signals on the value of water. Water 

savings through irrigation system upgrades at the farm level may be 

available for transfer off the farm. Similarly, farmers investing in 

irrigation improvements may value the additional certainty of water 

supplies available through the market. States can help protect environmental services through laws governing water transfers. In Oregon, for 

example, irrigators may transfer water made available through conservation as long as 25 percent of water conserved is reserved for instream 

uses.

• CREP land retirement. Under USDA’s Conservation Reserve 

Enhancement Program (CREP), the Federal Government may partner 

with States, tribes, local governments and private entities to idle irrigated cropland under long-term lease agreements. CREP partnerships 

provide greater enrollment incentives than what currently exists under 

a Conservation Reserve Program (CRP) general signup—USDA’s 

primary land retirement program. Under CREP contracts, USDA offers 

higher payments tied to irrigated rental rates, while partners provide 

funding for additional expenses, such as permanent easements or retirement of water rights. Today, CREP projects in several Western States 

(Nebraska, Colorado, Idaho, and Kansas) target agricultural water 

conservation in critical watersheds. The projects are designed to reduce 

consumptive use of surface and groundwater through retirement of irrigated land and accompanying restrictions on water withdrawals, and 

they are intended to lessen the effect of water-supply shortfalls on water 

users and natural systems during periods of sustained drought. Related 

project goals involve enhanced water quality and terrestrial habitat 

through establishment of vegetative cover and restoration of aquatic 

systems through reestablishment of fl ow volumes in river systems and 

adjoining wetlands. 
39

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Irrigation Investments: Decision Factors, 

Types, Purposes, and Funding Sources

While the need for continued improvements in water-conserving production 

systems in U.S. irrigated agriculture is well established, water-use effi ciency 

gains depend on irrigation investment decisions in the private farm sector. 

Various factors infl uence the adoption of more effi cient irrigation systems and 

water management practices, and their relative importance in the technology 

selection decision varies across locations and farm types, ultimately affecting 

investment expenditures and funding sources in the U.S. irrigated sector. 

Factors Affecting Irrigation Technology 

Investment Decisions

Potential gains in onfarm water-use effi ciency, and resulting crop yield and/

or input use benefi ts, vary across systems and resource settings. Survey data 

suggest that resulting income gains from irrigation technology adoption drive 

most investment decisions. According to the 2008 FRIS, 59 percent of U.S. 

survey respondents who invested in system upgrades reported reductions 

in applied water, and 60 percent reported improvements in crop yield and 

quality as a direct result of making recent irrigation investment decisions 

(table 5). Reductions in irrigation-related energy and labor costs were identifi ed by 46 and 41 percent of respondents, respectively. Other reported investment benefi ts included reductions in soil erosion, fertilizer and pesticide loss, 

and drainage runoff. Most farmers across the United States seemed to be 

similarly motivated when making irrigation investment decisions, although 

farms in the Eastern States placed a slightly higher emphasis on improving 

irrigated crop yield and quality.

The suitability of irrigation system investments often depends on the physical 

characteristics of the land (Caswell and Zilberman, 1985; Negri and Brooks, 

1990). Improved gravity-fl ow systems perform best on fi elds with low slope 

and higher quality soils with low water-infi ltration rates. Sprinkler systems 

have an advantage for use on nonuniform-shaped fi elds with greater slope and 

soils with higher infi ltration rates. Land quality considerations can have an 

impact on potential effi ciency gains in water use and related energy and labor 

requirements. 

Expanding irrigated acreage on a farm will likely involve new investment in 

high-effi ciency irrigation systems. Similarly, a farm that reduces irrigated 

acreage is more likely to discontinue irrigation on acres with lower effi ciency 

systems. Cropping decisions may also affect the types of system innovations considered. Costly irrigation innovations are less likely to be applied 

for lower valued hay and pasture crops. Water-use effi ciency gains may be 

greater for crops with relatively higher water needs, such as corn, relative 

to less water-intensive crops, such as wheat. A crop’s cultural requirements 

may also affect irrigation system improvement choices. Special furrow techniques that modify soil-moisture infi ltration, for example, and improve the 

uniformity of applied water across a fi eld are best suited to row crops, such 

as corn and cotton. Of survey respondents indicating barriers to practice 

adoption in 2008, 16 percent identifi ed physical fi eld conditions and cropping 
40

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considerations as barriers (17 percent in the West and 10 percent in the East) 

(table 5).

The cost of irrigation system upgrades can be an important limiting factor 

in irrigation investment decisions. While new technologies offer potential 

long-term gains, installation of irrigation equipment often requires large 

capital investment as well as more onfarm management. Producers’ decisions 

Table 5

Results of irrigation system improvements and key barriers to 

making system improvements, 2003-08

17 Western 

States

31 Eastern 

States

United 

States

Farms implementing irrigation system 

improvements (since 2003) 62,189 11,926 74,846

Percent

Effect of system improvements:1

Improved crop yield/quality 58.7 67.6 60.2

Reduced energy costs 43.6 56.5 45.6

Reduced water applied 60.6 54.1 59.4

Reduced labor costs 42.6 34.7 41.2

Reduced fertilizer/pesticide loss 18.3 16.1 17.9

Reduced soil erosion 29.8 25.9 29.1

Reduced tailwater runoff 23.6 11.5 21.5

Farms identifying barriers to 

energy and/or water conservation 

improvements (since 2003)

107,796 22,626 131,988

Barriers to making irrigation system Percent

improvements:1

Investigating improvements was not 

a priority 34.6 39.6 35.5

Risk of reduced yield or poorer crop 

quality 14.2 13.5 14.1

Physical fi eld/crop conditions limit 

system improvements 17.0 10.4 15.8

Improvements will not reduce costs 

enough to cover installation costs 26.3 2.2 25.6

Cannot fi nance improvements 29.6 23.1 28.4

Landlord will not share costs of 

improvements 4.5 8.0 5.2

Uncertainty about future availability 

of water 17.0 4.8 14.8

Will not be farming long enough to 

justify new improvements 13.4 11.3 13.1

1For each issue, farm respondents were allowed to select multiple response categories.

Source: USDA, National Agricultural Statistics Service, 2008 Farm and Ranch Irrigation 

Survey, Vol. 3, Special Studies, Part 1, AC-07-SS-1, 2010,http://www.agcensus.usda.gov.
41

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to invest depend on whether the expected benefi ts of adoption outweigh 

expected costs, relative to production systems currently in use. According to 

the 2008 FRIS, 28 percent of respondents identifying barriers to conservation indicated an inability to fi nance improvements as a barrier to change 

(30 percent in the West and 23 percent in the East) (table 5). Many respondents believed that system improvements would not lower production costs 

suffi ciently to cover costs (26 percent of all respondents). For some of these 

producers, long-term investment paybacks may also be viewed as overly 

speculative. Public fi nancial assistance programs that support the adoption of more effi cient irrigation practices reduce the effective cost borne by 

producers. 

For some irrigators, the cost of water supplies plays a larger role in irrigation 

investment decisions. Incentives for water-use effi ciency gains are greatest 

where water costs are high. High-effi ciency pressurized systems, for example, 

are predominant in the Plains States where deep-well groundwater irrigation 

is predominant. In surface water supply areas, irrigators may be reluctant to 

invest in improved irrigation technologies where the price per unit of water 

is low or water is charged on a per-acre basis.31 Water pricing policies have 

been implemented for public surface-water supplies to capture capital and 

operation costs of the off-farm delivery system while also promoting onfarm 

water conservation. Under the Central Valley Project Improvement Act of 

1992, for example, tiered (block-rate) pricing structures are applied to water 

deliveries for project contractors (irrigation districts).32 However, districts 

may elect to use a modifi ed rate schedule or an alternative average rate when 

pricing water deliveries to farmers (CBO, 1997). 

Adoption of improved irrigation systems may also occur in response to 

restricted water supplies. Reduced water losses under more effi cient systems 

are intended to offset water-supply shortfalls. In California, surface water 

delivery restrictions under sustained drought conditions in the early 1990s 

prompted improvements in irrigation water-use effi ciency as well as institutional adaptations in water resource allocation (Zilberman et al., 1998; CBO, 

1997). In some cases, public fi nancial support for improved irrigation practices has been contingent upon water-supply restrictions. In the Central Platte 

Natural Resource District of Nebraska, for example, irrigation expansion was 

limited under an Environmental Quality Incentives Program (EQIP) special 

project to support conversion from gravity to sprinkler irrigation systems 

(SWCS and ED, 2007). 

Farmers also may be reluctant to invest in improved technologies if access 

to future water supplies is uncertain. In the 2008 FRIS survey, uncertainty 

about future water availability was identifi ed as a barrier to technology adoption by 17 percent of irrigators in the Western States and 5 percent of irrigators in the Eastern States (table 5). Water-supply uncertainty is a particular 

concern for junior holders33 of surface water rights, whose water supply 

fl uctuates more signifi cantly with annual variability in precipitation. These 

water-rights holders may face irrigation delivery cutbacks when water supply 

conditions fall below levels required to meet the needs of senior water right 

holders. 

The technology adoption decisions of senior versus junior appropriators vary 

depending on differences in land quality and operator management skills, 

31Schuck et al. (2005) indicated that 

other factors, such as recurring drought 

conditions, could motivate irrigators to 

adopt improved irrigation technologies 

even under low water prices.

32For the fi rst rate tier, a district 

is charged the applicable contract 

(subsidized) rate for the fi rst 80 percent 

of water delivery, then an average of 

the contract and full-cost rates for water 

quantities between 80 and 90 percent of 

water delivery, and a district full-cost 

rate for the last 10 percent of water 

delivery to the district.

33Under the "prior appropriation 

system," the dominant water-rights 

legal institution in the Western States, 

water allocations are based on the 

"priority date" of the water right, a 

principle generally characterized as 

"fi rst in time, fi rst in right." Each 

water right has a specifi c annual 

quantity with an assigned appropriation 

date. Water-right holders with the 

earliest appropriation dates (senior 

appropriators) generally receive their 

full appropriation, provided there is 

adequate water supply. In water-short 

years, users holding water rights 

with later appropriation dates (junior 

appropriators) may not receive their full 

appropriation or even any water at all.
42

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uncertainty over future water prices, the level of the farm’s water allocation, perceived water-supply risk, whether water markets exist, and access 

to market-based information among water-right holders. For example, Carey 

and Zilberman (2002) revealed that water markets may decrease technology 

adoption incentives for some farms. For farms with abundant water supplies 

(i.e., senior appropriators), water markets are likely to increase incentives 

to invest in improved irrigation systems in anticipation of marketing water 

savings; but for farms with scarce supplies (i.e., junior appropriators), a water 

market may cause a postponement of irrigation technology investments as 

they have the option to purchase water in the market.

In the absence of a water market, however, Carey and Zilberman determined 

that a farm’s willingness to invest in improved technology is infl uenced by 

the size of the farm’s water allocation. The authors concluded that senior 

appropriators without a means to market water have less incentive to adopt 

improved technology, while junior appropriators with reduced supply recognize that they may need to produce at reduced acreage or lower yields (defi cit 

irrigate) with the traditional technology, prompting them to adopt more effi -

cient systems.34 This effect is likely infl uenced by how junior the water right 

and the perceived magnitude of the water-supply risk relative to the potential 

onfarm effi ciency gain. For example, junior appropriators facing signifi -

cant water-supply risk may have less incentive to adopt improved irrigation 

systems because the investment may too often sit idle in water-short years.

Inadequate off-farm water storage and delivery infrastructure also can 

represent a signifi cant barrier to achieving maximum irrigation effi ciencies 

through improved onfarm technologies (USDA/REE, 2004). Investment may 

be needed to enhance the capacity of an off-farm delivery system to supply 

onfarm water requirements on a more timely basis. For 2008, FRIS results 

indicated that 14 percent of irrigators had no choice in scheduling their irrigation because water was delivered to the farm on a fi xed rotation basis via their 

water-delivery organization.

Irrigators also may be reluctant to adopt new technologies due to risk of 

unsuccessful outcomes, particularly in the short term (Harwood et al., 1999). 

Irrigation system upgrades are often part of a broader change in production 

systems. New irrigation technologies often require higher levels of information and management to achieve potential yield gains and input use effi -

ciencies. Increased adoption of improved irrigation systems may require a 

commitment of public funding for technical support, demonstration projects, 

and information transfer. 

Farm size and structure as well as demographic factors also infl uence 

farm-level irrigation system improvements. Larger farms that benefi t from 

a stronger capital base and scale economies may be better positioned to 

adopt system improvements. Schaible (2004) and Schaible and Aillery 

(2006) reported that farm size infl uenced how effectively water conservation programs serve both USDA conservation and small-farm policy goals. 

Schaible (2004) notes that the largest 10 percent of irrigated farms in the 

West (farms with more than $500,000 in sales) accounted for nearly 50 

percent of total farm water applied. While relative irrigation improvement 

potential—the percent of irrigated acres still irrigated with traditional, lesseffi cient systems—is generally greater for smaller irrigated farms, larger 

34This would imply that, for some 

watersheds, a cut in irrigation water 

allocations may result in reduced 

supplies to producers using more 

effi cient systems.
43

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farms irrigate many more acres and account for most agricultural water use, 

implying a greater conservation-gain potential to meet environmental and 

other farm-policy goals. In addition, owner-operators may be more likely 

than renters to make the large capital investments necessary for improved 

systems. Younger farmers are more likely to recoup irrigation investments 

than aging farmers facing retirement. The overall health of the farm economy 

may also infl uence irrigation investments—“good times” are generally better 

for investments than “bad times.”

Onfarm Irrigation Investment Expenditures

The 2008 FRIS indicated a signifi cant increase in onfarm irrigation investment expenditures relative to the 2003 survey year. Approximately $2.15 

billion was invested in irrigation systems in 2008 (beyond expenditures for 

maintenance and repair of $820 million), compared with $1.12 billion in 

2003. Higher investment expenditures refl ect both an increase in the number 

of farms reporting irrigation investments (up 22 percent) and higher average 

expenditures per farm (up 73 percent). Investment in irrigation system 

upgrades, where water conservation was identifi ed as the principal purpose, 

totaled $323 million in 2008—up by nearly 90 percent from 2003. 

Table 6 shows 2008 expenditures for onfarm irrigation facilities and equipment by primary purpose for the 17 Western States, as well as totals for the 

Eastern States and the entire United States. New equipment for irrigation 

expansion accounted for about 35 percent of expenditures nationwide. New 

equipment expenditures accounted for a somewhat higher share in Eastern 

States, refl ecting expansion in irrigated acreage. More than half of onfarm 

investment expenditures in the West was made to replace existing equipment 

and machinery. Farmers nationwide upgraded their irrigation facilities and 

equipment to improve water conservation, accounting for roughly 17 percent 

of onfarm irrigation investment expenditures in the West and 9 percent in the 

East. 

Onfarm irrigation investments focus on more precise water application that 

satisfi es crop requirements, while minimizing fi eld losses. Upgrades in application equipment and machinery accounted for 65 percent of investment 

expenditures made to improve onfarm water conservation in Western States. 

Land leveling to improve the uniformity of applied water in gravity-fl ow 

systems accounted for an additional 21 percent of conservation expenditures. 

Improved onfarm water storage and conveyance systems are also important, 

reducing storage and conveyance losses and improving effi ciency potentials 

for onfarm water-delivery systems. Onfarm water storage and conveyance 

upgrades accounted for roughly 9 percent of water conservation expenditures 

in the West. Computers and information systems for irrigation management represented 5 percent of water conservation expenditures. While well 

expenditures are not directly related to conservation, groundwater access is 

an important adaptation to drought risk. Well construction, including replacement and new wells, represents a signifi cant portion of total onfarm irrigation 

investment expenditures. In the Eastern States, irrigators devoted nearly 67 

percent of their 2008 irrigation investments to new or replacement equipment 

and machinery. While water conservation is important in these States, past 

irrigation investments in the Eastern States were generally made to maintain 
44

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crop irrigation during periods of below-normal rainfall and to expand irrigation capacity.

Sources of Onfarm Irrigation Investment Funding

Most onfarm irrigation investment in the United States is fi nanced privately. 

Of farms reporting irrigation improvements in 2008, 6 percent received 

public fi nancial assistance. High levels of private investment refl ect both the 

magnitude of expenditures on replacement equipment and irrigation expansion that typically do not qualify for public assistance, and the private gains 

associated with irrigation investment (e.g., higher yields and input-use effi -

ciency). Participation in public funding programs may also be limited by 

program funding allocations, administrative requirements for program enrollment, and payment limits to farm operators. For many irrigators, however, 

public programs represent an important source of funding to support adoption 

of more effi cient irrigation systems. 

Table 6

Expenditures for irrigation facilities and equipment, 2008

Purpose of expenditure Source of funding assistance

Total 

expenditures

Average 

per 

farm

Replacement

Water 

conservation

New 

equipment

No 

funding 

assistanceUSDA's 

EQIP

Other 

USDA 

cost-share 

programs

Non-USDA 

cost-share 

programs

Types of investment: 

(17 Western States) $1,000 Dollars $1,000 Number of farms

New/replacement 

irrigation equipment 

and machinery

1,098,826 18,155 629,381 175,520 293,925 60,769 2,326 864 666

New well or 

deepening of 

existing well

261,954 43,871 153,520 NA 108,434 5,913 29 30 101

New/improvement 

of storage and 

distribution systems

85,030 12,111 28,587 25,172 31,271 7,113 292 144 37

Land clearing and 

leveling for irrigation 

purposes

91,824 12,520 NA 56,499 35,325 7,520 139 125 15

Computers, control 

panels, and software 

for irrigation water 

management

37,451 6,262 12,183 12,295 12,973 5,973 148 103 35 

All investment types;

17 Western States 1,575,085 23,336 823,671 269,486 481,928 87,288 2,934 1,266 854

31 Eastern States 494,063 27,369 203,554 46,247 244,261 23,528 1,304 612 489

U.S. total1 2,149,007 23,628 1,077,192 323,083 748,732 111,317 4,240 1,878 1,343

EQIP=Environmental Quality Incentives Program, and NA = not applicable.

1U.S totals include statistics for Hawaii and Alaska. 

Source: USDA, National Agricultural Statistics Service, 2008 Farm and Ranch Irrigation Survey, Vol. 3, Special Studies, Part 1, AC-07-SS-1, 

2010,http://www.agcensus.usda.gov/.
45

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The EQIP, administered by USDA’s NRCS, is the Nation’s primary agricultural conservation program for working farms and ranches. EQIP provides 

technical and fi nancial assistance for eligible conservation practices under 

short-term contracts (1-10 years). Financial support for installation of structural and vegetative practices range from 50 to 75 percent of typical costs 

established at the county level, with rates of up to 90 percent for beginning, 

resource-limited, and socially disadvantaged farmers. Annual payments 

are also offered for the adoption of conservation-compatible management 

practices, including irrigation water management. In 2008, EQIP accounted 

for 58 and 54 percent of farms reporting public fi nancial assistance for 

irrigation investments across Western and Eastern States, respectively 

(table 6).35 Other USDA fi nancial assistance programs (e.g., Conservation 

Stewardship Program, Wetlands Reserve Program) accounted for 25 percent 

of farms reporting assistance, with the remaining funding provided by nonUSDA programs (e.g., U.S. Environmental Protection Agency, Bureau of 

Reclamation, as well as State and local water management and supply district 

programs). 

Figure 15 shows EQIP expenditures for irrigation practices as a share of total 

program outlays, by region, for 2004-10.36 Nationally, irrigation practices 

accounted for $1.4 billion in program expenditures over this period (USDA/

NRCS, 2004-10), or roughly a quarter of total EQIP fi nancial assistance. 

The magnitude of public irrigation investment under EQIP varied across 

the United States, partly refl ecting the relative importance of irrigation to 

the agricultural economy.37 In Western States, EQIP funding of irrigation 

practices (as a share of total program outlays) ranged from 13.0 percent in 

the Northern Plains to 57.7 percent in Southern Mountain States. Irrigation 

35Farms reporting EQIP funding 

assistance represented 4 percent of all 

U.S. irrigated farms making irrigation 

investments in 2008. The statistics 

here represent only a snapshot of EQIP 

participants for the 2008 production 

year and do not refl ect program 

participation over time.

36Funding levels reported here 

represent fi scal year dollars obligated. 

37The conservation of ground and 

surface water resources is one of 

several priority resource concerns used 

to set State funding allocations and to 

rank local contract offers under EQIP.

NE=Northeast; AP=Appalachia; SE=Southeast; LK=Lake States; CB=Cornbelt; DL=Delta; 

NP=Northern Plains; SP=Southern Plains; NM=Northern Mountain; SM=Southern Mountain; 

NW=Northwest; CA=California.

Source: USDA, Economic Research Service calculations based on USDA’s Natural 

Resource Conservation Service, Environmental Quality Incentives Program data, 2004-10.

Figure 15

Environmental Quality Incentives Program funding for irrigation 

practices, by region, 2004-10

Total program outlays (million dollars)

0

100

200

300

400

500

600

700

800

NE AP SE LK CB DL NP SP NM SM NW CA

Nonirrigated Irrigated
46

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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practices accounted for a relatively small share of program expenditures in 

the Corn Belt, Lake States, Appalachian, and Northeast regions. Since 2004, 

however, the shares of EQIP funding for irrigation practices generally have 

increased in Eastern States while they have declined across the West. 

A wide range of irrigation-related practices are eligible for fi nancial assistance under EQIP. More than half (55.8 percent) of EQIP irrigation funding 

was devoted to upgrades in onfarm water application systems (USDA/NRCS, 

2004-10). Approximately 34.7 percent of funding was allocated to improved 

onfarm water conveyance. Water supply practices represented a relatively 

small portion (9.4 percent) of total irrigation expenditures under EQIP, 

refl ecting program emphasis on enhancing producer adoption of improved 

onfarm irrigation practices for existing irrigation. In a recent report, USDA’s 

NRCS estimated that, as of 2007, the EQIP program treated about 4.0 million 

irrigated acres and, by the end of 2012, EQIP is expected to treat an additional 2.0 million irrigated acres with water-conserving irrigation practices 

(USDA/NRCS, 2010). The study estimated benefi ts for irrigation conservation funding at $10.30 per acre. This measure is considered conservative 

because not all benefi ts could be taken into account.38 38The NRCS evaluation of EQIP 

funding for irrigation conservation, 

conducted consistent with Offi ce of 

Management and Budget guidelines as 

part of an offi cial rule-making process, 

did not include benefi ts for productivity 

changes, input-cost savings, water 

quality and environmental impacts, 

or a measure of the nonagricultural 

market value of saved water. The 

study also assumed that water saved on 

the farm would be available for other 

agricultural activities, other competing 

uses (municipal, power, or fi sh habitat), 

or sold locally via irrigation rental 

markets, but did not account for these 

adjustments within the benefi t/cost 

analysis (USDA/NRCS, 2010).
47

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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Summary and Policy Implications

Irrigated agriculture makes a signifi cant contribution to the value of U.S. 

agricultural production. Based on 2007 Census of Agriculture data, irrigated 

farms accounted for $118.5 billion in sales, or roughly 40 percent of the value 

of U.S. agricultural production, with the national average value of production 

for irrigated farms 3.3 times the average value for nonirrigated farms (farms 

not irrigating any land). Irrigated farms accounted for 54.5 percent ($78.3 

billion) of the value of all crop products sold, while also contributing signifi -

cantly to the value of livestock and poultry production through animal forage 

and feed production.

In 2007, nearly 57 million U.S. acres were irrigated, representing 7.5 percent 

of all cropland and pastureland. The 12 leading irrigation States accounted 

for 77.2 percent of all irrigated acres, with Nebraska, California, and Texas 

leading all other States with 8.6, 8.0, and 5.0 million irrigated acres, respectively. Two States among the 31 Eastern States—Arkansas and Florida—were 

among the 12 leading irrigation States, with 4.5 and 1.6 million acres, respectively. Nearly three-quarters of U.S. irrigated agriculture occurred in the 17 

Western States, including 73 percent of harvested irrigated cropland and 94 

percent of irrigated pastureland. Farm and Ranch Irrigation Survey data for 

2008 indicated that U.S. irrigated agriculture used nearly 91 maf of water. 

Irrigators across the Western States applied nearly 74.2 maf of water for irrigated cropland production, with 52.4 percent originating from surface-water 

sources and the remaining 47.7 percent pumped from wells drawing water 

from regional and local aquifers. 

Population and economic growth, changing social values with respect to 

water quality and the environment, and Native American water-right claims 

have been and will continue to be forces driving demand for water resources 

within the United States. Resolving Native American water-right claims, 

once estimated at nearly 46 maf annually, could have a signifi cant impact on 

future surface/groundwater supplies for agriculture. As more States move 

beyond the minimum instream-fl ow concept to formally recognize environmental fl ows—instream fl ows required to maintain sustainable fi sh and 

wildlife habitats or to re-establish natural habitats—the volume of water reallocated from agriculture to meet environmental needs likely will increase. 

More recently, emerging demands for water resources have heightened water 

scarcity concerns, particularly across the Western States. Biofuel development, whether through corn-based ethanol or cellulosic feedstock sources, 

may increase demand for water resources in some regions. Over time, climate 

change impacts are expected to alter both water supplies and water demands 

across and within regions. Warming temperatures, changing precipitation patterns, and reduced snowpack are expected to signifi cantly reduce 

late spring/summer streamfl ows (fl ows that historically were available for 

reservoir storage to meet peak irrigation water demands) and groundwater 

recharge across much of the West. In addition, higher temperatures are 

expected to increase crop-water demands via reduced crop ET effi ciency. 

Competing demands for U.S. water resources will continue to grow, while 

the potential for new, large-scale water-supply projects is fairly limited. 

Agriculture accounts for more than 80 percent of U.S. consumptive water use 
48

Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands / EIB-99

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and, with the lowest marginal value of water among competing out-of-stream 

uses, will be the likely water source to meet future water demands. Emerging 

demands already are placing new pressures on existing water allocations, 

particularly across the West, heightening the importance of water conservation for irrigated agriculture sustainability. The future sustainability of the 

irrigated agriculture sector will depend a great deal on a variety factors, such 

as water-use effi ciency, conservation policies that encourage more effi cient 

onfarm water management, and how and when increasingly scarce water 

supplies are reallocated among competing demands.

Since the 1970s, data reveal a substantial and sustained shift across the 

Western States from traditional gravity-fed and fl ood irrigation to more effi -

cient gravity and pressure/sprinkler irrigation systems. In 2008, about $2.15 

billion was invested in U.S. irrigation systems, with the majority ($1.6 billion) 

invested in Western States. Most irrigation investment was fi nanced privately, 

with less than 10 percent of farms reporting irrigation improvements in 2008 

using public fi nancial assistance for irrigation upgrades. The data indicate 

that, while substantial technological innovation has already occurred in U.S. 

irrigated agriculture, signifi cant room for improvement exists. At least half of 

irrigated cropland acreage across both Western and Eastern States is still irrigated with traditional (less effi cient) irrigation application systems. In addition, survey data indicate that most irrigators do not implement more effi cient 

onfarm water management practices. Fewer than 10 percent used soil- or 

plant-moisture sensing devices or commercial irrigation scheduling services. 

Less than 2 percent of irrigators used computer-based simulation models to 

evaluate crop irrigation requirements based on consumptive-use needs and 

local weather conditions. 

Adoption of more effi cient irrigation application systems has been and will 

be an important component of agricultural water conservation efforts. During 

2004-10, most of USDA’s EQIP irrigation funding was devoted to upgrades 

in onfarm water application and onfarm water conveyance systems. The 

sustainability of irrigated agriculture, however, could be enhanced further 

if producers combined improved onfarm water management practices with 

high-effi ciency irrigation application systems. In addition, through collaborative Federal, State, and local partnerships under USDA’s Agricultural Water 

Enhancement Program, integration of onfarm conservation efforts with 

watershed-level water management tools could further encourage increased 

conservation of water resources for current, alternative, and future uses. 

Integrating irrigation effi ciency improvements with other practices, such as 

defi cit irrigation, acreage idling, and off-farm water transfers that compensate 

agricultural producers for water conservation gains, may allow producers to 

balance the drop in yields that often accompanies efforts to reduce irrigation water use with potentially improved profi tability through reduced costs 

of applying water and related inputs and increased water-related revenue. 

Integrating onfarm conservation and Federal/State institutional mechanisms 

also may encourage producers and other stakeholders to interact jointly in 

determining market-based water reallocations.

Designing agricultural water conservation policies that promote a more 

sustainable future for irrigated agriculture depends a great deal on improving 

the economic analysis of adaptation options within the irrigated farm sector. 

While previous economic studies of agricultural water-conservation issues 
49

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have been helpful, these studies were limited in their ability to handle the 

broad range of “production system” adaptation strategies that will help irrigated agriculture adjust to a future of increasing competition for a stable or 

declining supply of water. This reduced-supply, rising-demand environment 

will place increased pressures on producers to adopt production systems that 

simultaneously reduce crop consumptive water use while maintaining farm 

profi ts. Managing water on the farm, whether applied by gravity or by highor low-pressure sprinkler irrigation, will become an increasingly important 

part of the farm’s irrigation production system technology. 

In an increasingly water-scarce world, production system adaptation strategies are likely to involve complex production decisions on crop choice, 

water application rates, and adopting effi cient irrigation technology and 

water management practices that adjust to changing water-supply conditions 

over time. Economic analyses from a production system perspective could 

simultaneously consider all the components of a producer’s production decisions—crop choice, crop yield target, irrigation system type, and onfarm 

water management regime—combined with fi eld-level physical/environmental characteristics and water-supply conditions. As competing demands 

and climate change increasingly strain the water supply/demand environment 

for agriculture, economic analysis of water conservation policy issues and 

their impact on agricultural production and regional resource use and quality 

will become more complex. Such analyses, however, could also enhance the 

quality and reliability of information on irrigation choices, improving our 

understanding of irrigated agriculture’s adaptability toward a more sustainable future. 
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