addressing agricultural water resources issues in north ... · on water measurement and canal...

Tri-National Initiative; Research of 27

Addressing Agricultural Water Resources Issues in North America:

The Role of Research and Education

Michael P. O’Neill1, Richard Butts

2, Dale A. Bucks

3, Mark A. Weltz

3, Kenneth R. Hinga

4

1U.S. Department of Agriculture, Cooperative State Research, Education, and Extension Service

2Agriculture and Agri-Food Canada, Environmental Health

3U.S. Department of Agriculture, Agricultural Research Service

4U.S. Department of Agriculture, Foreign Agricultural Service

This paper is a contribution of the Tri-National Initiative on Environmentally Sustainable Agriculture

and Water Quality. The Initiative is an informal working group of Canada, the U.S. and Mexico.

Introduction

There is no substitute for fresh water nor are there

replacements for its essential role in maintaining human health,

agriculture, industry, recreation, and ecosystem integrity.

Throughout history, a key measure of civilization’s success has

been the degree to which human ingenuity has harnessed

freshwater resources for the public good.

As we begin the 21st century, water availability and

quality are becoming critical in the United States, Canada and

Mexico; indeed, for the world. Recent estimates indicate that

approximately two-thirds of the world’s population will live in

water-stressed environments by the year 2020 (Gleick, 2002).

Climate variability, mining of ground water, and degraded

water quality are dramatically changing the amount of

freshwater available to us at different times and in different

locales. In short, our shared inheritance of useable freshwater

is growing smaller and more variable. Allocations of our

freshwater resources are also shifting among different users

and different needs: e.g., from agricultural use to consumption

by cities, from storing water supplies in reservoirs to

maintaining in-stream flows to support healthy aquatic

ecosystems, from industrial and energy production to

recreation. Moreover, our increasing populations will require

more water in the future.

In order to meet the increasing demands for clean,

safe water supplies, we must continue to search for appropriate

practices and technologies to protect existing clean water

resources and improve degraded water resources. To that end,

the goal of water resources research and education in North

America is to create and disseminate the necessary knowledge

to develop, implement, and maintain appropriate conservation

practices and technologies that protect or enhance water

quality. Over the past century, research and education efforts

have addressed both the availability of water for agriculture

and the quality of that water. In this paper, we provide a brief

overview of water resources research and education and

identify possible future areas for tri-national cooperation in

research and education to address agricultural water resources

issues.

Along with our recognition that we need additional

information to manage our water resources, we have a new

perspective on the science and education needed to address

water resources issues. In the past, hydrology, soil science,

chemistry, geology, and engineering formed a core of physical

sciences that dealt with water resources issues. Similarly,

aquatic and riparian ecology, microbiology, and forestry were

typical of sciences that addressed biological concerns of water

resources. Finally, economics, political science, and sociology

have formed the cornerstone of research on the “human

dimensions” of water resources. A new, more holistic

approach is needed to resolve difficult water resource

management issues (see U.S. EPA, 1999). This new, holistic

approach to water resources management brings together the

typically disparate approaches of physical, biological, and

social science approaches to provide comprehensive solutions

to water resource management issues (see Figure 1).

.Many nations have similar water issues. Many of the

key water issues to be addressed around the globe are relevant

and of concern to researchers and educators in North America.

In this paper, we attempt to highlight some key

accomplishments of research and education programs

developed across North America. We also attempt to identify

some critical water resources issues that pose formidable

challenges to research and education among the three nations

represented here. Comprehensive literature surveys of

research, policies, and conservation practices and technologies

are available for more in-depth study (see Gagnon et al., 2004;

Makuch et al., 2004a; Sherman et al., 2004; and Makuch et al.,

2004b).

This paper summarizes the current state of knowledge

with respect to practices and technologies used to protect and

improve water resources by evaluating our current

understanding of these practices and technologies at various

spatial and temporal scales. In particular, we consider the state

of knowledge for water resources protection and improvement

at the lab-plot, field, and watershed scale. For simplicity, our


focus is on water resources management for agriculture.

However, we recognize that agriculture represents only one of

many critical water uses and that these complex and often

conflicting water uses must be addressed jointly to achieve

sustainable solutions to water management issues. Although

the focus of this paper is on water quality, we also recognize

the inseparable importance of water availability to water

quality.

Water Availability

Allocations of freshwater resources are shifting

among different users and different needs: e.g., from

agricultural use to consumption by cities, from storing water

supplies in reservoirs to maintaining in-stream flows to support

healthy aquatic ecosystems, from industrial and energy

production to recreation (Figure 2). In Canada agriculture

competes with many other users where thermal electric

(64 percent), manufacturing (14 percent), municipal

(12 percent), agriculture (9 percent), and mining (1 percent)

are the primary water users. Moreover, our increasing

populations are requiring more and more water (Figure 3) (see

Keinholz et al. 2000). In Mexico, water for agricultural

irrigation is the largest use for water withdrawals (Figure 4).

Today, North America faces new challenges:

increasing demand for water for our cities, farms, and aquatic

ecosystems; changing supplies due to ground water mining;

and changing supplies due to climate variability and change.

For example globally, water withdrawals from water bodies

have risen from 250 cubic meters/person/year in 1900 to over

700 meters/person/year (Environment Canada 2005). These

challenges are not insurmountable. The nature of these water

issues has evolved in response to growing populations, greater

dependence on irrigated agriculture, urbanization, and

changing climate. Thus, the water science and technology

portfolio must encompass research that produces short-term

solutions as well as fundamental knowledge advances that will

address tomorrow’s problems.

A recent report published by the United States

government (SWAQ, 2004) poses the rhetorical question “Do

we have enough water?” This report underlines the importance

of the role of research, development, and education in

providing science-based information for managing water

resources across the nation and throughout North America.

The report presents a clear case for expanding research and

development for improving water resources management. In

particular, the report focuses on the need for improved data

and information on water availability to assist water

management decision-making. In line with this thinking and

recognizing that Canadians are the second largest users per-

capita users of water in the world, the Canadian Water

Resources Journal published a recent issue on Economic

instruments for water demand management in Canada (see

Can. W. Res. Jour. 2005 Vol. 30, issue1).

In 2004, the U.S. Department of Agriculture hosted a listening

session to identify key knowledge gaps in the effort to address

agricultural water management issues (Dobrowolski and

O’Neill, 2005). Through this listening session, six key topical

areas were identified that will require additional research and

education efforts to meet the increasing demands for water in

agricultural, rural, and urbanizing watersheds. These six areas

are: irrigation technology, water reuse, plant biotechnology,

general water conservation, drought preparedness, and water

marketing and economics. Table 1 provides an overall

assessment of current North American knowledge on these six

topical areas at three spatial scales – the laboratory or plot

scale, the field scale, and the watershed scale.

Clearly, a great deal of knowledge exists regarding

irrigation technologies particularly at the plot and field scale.

Irrigation technologies research in the U.S and Canada has

improved sprinkler methods with center pivots, greatly

improved micro-irrigation methods such as water treatment

methods, buried drip systems and micro spray, and has

introduced more modern surface irrigation methods (e.g., level

basins, tailwater recovery, surge irrigation, precision-graded

systems for rice). Irrigation efficiency research is trying to

raise the bar on production per unit of water use through

precision irrigation at the field scale, though few research

projects involve improved irrigation practices on water

availability at the watershed scale. Advances in irrigation

management have improved our ability to determine crop

water requirements resulting in major impacts on water rights

and allocations by states and the federal government. Weather

station networks are expanding to provide near real-time data

on crop water needs. Unfortunately, the use of these methods

by growers for scheduling irrigations has been disappointing,

despite major extension efforts by both state and federal

agencies. Water delivery research showed that constraints in

water delivery from large projects cause on-farm irrigation

systems to perform below potential, to spill excess water and

to not be able to utilize modern scheduling methods. Research

on water measurement and canal automation is providing new

tools to reduce these limitations. Water reuse research has

expanded groundwater recharge to bank water for later use,

expanded wastewater reuse with Soil-Aquifer-Treatment

technologies and the examination of water quality/human

health implications for reuse of wastewater for irrigation.

Where general water conservation in agricultural

settings is reasonably well known for irrigation practices (see

Fangmeier et al., 1999; Hunsaker et al., 1999), much less is

known about how “agricultural” technologies are being used in

urban and urbanizing watersheds (Dobrowolski and O’Neill,

2005, Cohen et al. 2004). With the continued loss of

agricultural land and the expansion of urban and suburban

environments, it is critical for research and education efforts to

improve our understanding of water use in these more

urbanized environments.

At present, there is little or no information on how

improved drought preparedness can affect water availability at

the watershed scale. Likewise, water markets and trading may

provide powerful tools to reallocate water resources to

alternative uses. However, while research into water markets

and trading has progressed (see Colby et al., 2000, Zilberman

and Schoengold 2005); little scientific information exists

regarding the impacts of these options on water resources

management – particularly at the watershed (or basin level)

scale. The lack of information often is the result of lack of

implementation of new or innovative efforts available in water


marketing and trading (Huffaker and Whittlesey, 2003,

Horbulyk 2005).

Water Quality

Even where water is not scarce, it is often

contaminated. Globally, only about 10 percent of all

wastewater is treated before it enters rivers and other bodies of

water. Poor water and environmental quality is already

estimated to be directly responsible for about 25 percent of all

preventable ill health in the world today, with diarrhea and

acute respiratory infections heading the list (WHO, 1997). On

every continent, groundwater, as well as surface water, is being

contaminated and rising sea levels from global warming

threaten contamination in some coastal areas. One-fifth of

freshwater fish stocks are still considered vulnerable or

endangered because of pollution or habitat disruption (Postel,

1996).

Perhaps the most serious problem is groundwater

contamination which can be impaired by nitrates, pesticides,

petrochemicals, chlorinated solvents, radioactive wastes,

saltwater, and heavy metals. Groundwater that becomes

polluted tends to stay polluted for a very long time; the average

residence time for groundwater is 1,400 years, as opposed to

16 days for river water. The seriousness of this situation is

demonstrated by the fact that over 10 million Canadians rely

on groundwater for their drinking water supply and all

Canadians rely indirectly since it is the primary source for

livestock water and irrigation (Rivera et al. 2003)

A wide array of pollutants exists in water bodies

across North America (U.S. EPA, 2000a, b). In the U.S.,

agriculture is the leading source of pollution in rivers and

streams contributing to 48% of the reported river and 41% of

the lake problems. (U.S. EPA, 2002). Five leading agricultural

water pollutants provide the greatest challenges to future water

quality, namely: sediment, nutrients, pesticides, salinity,

pathogens (e.g., Mueller, 1995; Spalding and Exner, 1993;

Larson et al., 1999, Fairchild et al 2000, Olson et al. 2005,

Chambers et al. 2006). Agricultural pharmaceuticals are

widely suspected to be a problem; however, more work is

needed to demonstrate that they have a significant impact on

the environment

Reducing pollution, especially the agricultural runoff

from erosion, over fertilization, manure applications and heavy

use of pesticides, is a major requirement for preserving water

quality. Research into agricultural practices has shown that

there is often considerable potential to reduce the impacts of

agriculture on water quality. Table 2 lists a few examples of

the reduction in movements of agricultural contaminants into

surface waters that can be made by adjustments in agricultural

practices. Many of these practices may make major reductions

on the impact of agriculture yet not have significant reductions

in agricultural productivity. Just as it is important that

agriculture have low impacts on the environment, it is

important that agriculture have high productivity. High

productivity agriculture is important to farmers incomes, food

prices, food security, and to reduce the need to expand

agricultural areas into native woodlands and other ecosystems.

(See Figure 5 for an example of an irrigation water pumping

and streambank erosion protection practice.)

It should be recognized that the examples given in

Table 2 are intended to show that changes in practices can

often make an important difference of the impacts of

agriculture on water quality. But all farming is subject to local

conditions. Application of techniques must be suitable for, or

modified to fit, local conditions, It is not safe to conclude that

reductions in agricultural impacts can be automatically

achieved by application of a technique that is successful

elsewhere.

The example practices listed in Table 2 take place on

farm fields themselves. A second general category of practices

are land set-asides for buffer zones, diversions or wetlands to

process (i.e. capture or degrade contaminants) runoff from

croplands or pastures (See Figures 6 and 7). These practices

are especially important where rain-fed agriculture systems

experience overland water flow which tends to move

fertilizers, pesticides, and organic matter (especially manure

with indicator bacteria) into surface waters. Research into

vegetated buffer zones along indicates that such systems, when

managed properly can significantly reduce contaminant runoff

from farm fields (see examples in Table 3.)

Riparian buffer practices will likely remove some

productive area from field crops that may be grown. However

these zones do not need to represent a complete loss. A

properly managed buffer can support tree crops for timber or

fruit or nut production. This can provide some diversity to the

farmer’s income. The outer zones of the buffer zoned may be

used for grazing.

Riparian buffer zones require water to flow off fields

in a uniform or sheet flow in order to operate efficiently. In

some farming areas, it is necessary to deliberately drain lands

through buried tiles in order to be able to work the soils. This

artificial drainage can facilitate the loss of nutrients from the

fields. In such cases, wetlands can be constructed to catch and

temporarily hold the water from the tile drains. This will allow

for nitrogen (primarily) and phosphorus removal. Nitrogen is

removed much more efficiently because in wetland conditions

bacteria are effective in converting through denitrification the

primary form of nitrogen (nitrate) in agricultural runoff into

unreactive nitrogen gas which is released to the atmosphere.

The performance of wetlands depends significantly upon the

length of time the water sits in the wetland before it flows out.

Overall, the performance of wetlands averages about 60-70 %

removal of total nitrogen (Peterson, 1998). As with the on-

field practices, the buffer and wetland practices require local

adaptation and constructed wetlands and buffer zones,

especially the wooded portions, may require a number of

seasons to become established and effective.

It should also be recognized that studies at field scale

provided in Tables 2 and 3 do not automatically translate to

what can be achieved at a watershed scale. First, it would be

unrealistic to expect universal farmer adoption of good

practices. The amount of adoption will depend upon the

amount of education, incentive, and regulation programs that

are applied. Second, implementation of the practices on

individual farms may not be effective as those achieved under

careful study conditions.


A comprehensive review of the impacts of

agricultural pollutants on surface and ground water quality is

beyond the scope of this paper. Here, in Table 4, we attempt to

characterize, the state of knowledge of each of the leading

agricultural pollutants at the three key spatial scales. Readers

are directed to Makuch et al. (2004a) for an annotated

bibliography of papers relating to agricultural pollutants and

associated conservation practices and technologies.

Clearly, our knowledge is greatest regarding the

movement and effects of sediment on water bodies (see Uri,

2001; Yoder et al., 1998; O’Connell and Todini, 1996; Church,

2002; Chow et al. 2000; Madsen et al. 2001). Much of the

knowledge gained regarding sediment movement and impacts

was a direct response to soil losses during the Dust Bowl years

and involved considerable plot and field based research on

sediment movement. More recent investigations have explored

how stream bank erosion and hillslope erosion contribute to

sediment inputs in stream systems and across watersheds (e.g.,

Sheilds et al., 2003,). This work has led to improvements in

our understanding of sources and movement of sediment

through watersheds as well as the storage of that sediment on

hillslopes, in stream channels, and in lakes and reservoirs.

Our knowledge of nutrients (primarily nitrogen and

phosphorous) as pollutants is considerable at the lab and field

scale but not well defined at the watershed scale (see Puckett,

1994; Howarth et al., 1996; Lowery et al., 1998; Spalding and

Exner, 1993; Sharpley et al., 2003). Clearly, there is a need to

expand research efforts to better understand nutrient dynamics

at the watershed scale (see Sogbedji, and McIsaac, 2002a , b;

Royer, et al., 2004; Carpenter et al., 1998, Chambers et al.

2006). Recent work at the watershed scale has focused on the

role of riparian corridors to buffer streams, rivers, and other

water bodies from nitrogen fluxes off agricultural fields (see

Gold et al., 2001; Lowrance, 1992; Nelson et al., 1995). This

research indicates that physical site conditions

(geomorphology, soil moisture content) can affect nutrient

fluxes entering streams and rivers. Interestingly, management

practices – such as drainage or irrigation – also can play a

substantial role in affecting the amount and timing of nutrient

delivery from agricultural fields to water bodies (Zucker and

Brown, 1998; Sogbedi and McIssac, 2002a, b; Royer et al.,

2004).

Considerable progress also has been made regarding

pesticide fate and transport at the lab and field scale (see Smith

et al., 1999, Elliott, et al.1998, 2000). However, less is known

regarding pesticide movement and impacts at the watershed

scale (Gilliom, 2001, Cessna et al 2001). Further, downstream

organisms may be simultaneously exposed to multiple

pesticides, originating from different areas. The cumulative

toxic effects from exposure to multiple pesticides on aquatic

organisms remain a concern for environmental quality. Much

research is needed to explore how cumulative effects of

pesticide application impact aquatic or estuarine systems in

receiving waters downstream of agricultural watersheds.

More recent research efforts have focused on the

source and movement of pathogens and pharmaceutical

compounds in streams, rivers, and ground water bodies (see

Dyer et al., 2001; Hanselman et al., 2003; Tyrell and Quinton,

2003, Raman et al., 2001, Lu et al., 2005, Van Herk et al.

2004). The human health hazards of pathogens have been

documented. However, little information exists regarding the

impacts of pharmaceutical products used in agricultural on soil

or aquatic ecosystems (Cha et al., 2005, Lorenzen et al., 2005).

Clearly, the widespread use of pharmaceuticals in society and

for animal agriculture points to a great need for improved

monitoring and research regarding the impacts of these

products on the environment.

The Natural Resources Conservation Service of the

U.S. Department of Agriculture (USDA/NRCS) has developed

a planning process that addresses the dominant concerns of

natural resource planners. They have summarized this

knowledge into the Conservation Physical Practice Effects

(CPPE) matrix. This material has been translated into an

interactive spreadsheet that addresses the perceived impact of

these conservation practices on key natural resources (soil,

water, air, plant, and animal). The matrix was developed

through interaction with field personnel and represents an

expert opinion of the impact and benefits of these field

conservation practices. Table 5 lists the 160 conservation

practices that NRCS has developed standards for and are

available in the CPPE matrix software. In Table 6,

conservation practices for soil erosion protection are

highlighted for the CPPE matrix. The estimated impacts on

reducing all forms of soil erosion are shown. The Soil and

Water Conservation Society and the USDA have joined forces

with University partners to take this information and develop a

synthesis review of what can be scientifically documented

about the impact and benefits of conservation practices for

improving water quality. This book will be available be early

summer 2006 through the Soil and Water Conservation

Society.

Source, Fate, and Transport of Pollutants and

Agricultural Water Quality Modeling

In North America, as is elsewhere, watershed

conditions vary greatly across space and through time. These

different and changing conditions pose a considerable

challenge to addressing agricultural water resources issues.

Each unique combination of soil, climate, vegetation,

hydrology, and management factors can have a tremendous

impact on the quality and quantity of surface and ground water

available in a watershed. The lists of possible management

actions given in Tables 5 and 6 illustrate the wide number of

actions that may be utilized in different situations. How is one

to select actions which will achieve improvements or assure

protection of water quality from farming operations? How is

one to know the actual benefit that will be achieved by an

individual practice if applied to a particular farm and setting?

It is clearly not practical to conduct experiments and runoff

measurements on each unique farm and setting. In order to

answer these important questions, models are developed,

which, by knowing the conditions on a particular farm (e.g.

soil properties, surface slope, typical rainfall, irrigation

practices, etc,) the model can be used to determine the benefits

of different management actions on the farm.


The major pathways for movement of pollutants

applied to the soil or foliage are through surface runoff and

movement through the profile via leaching. The processes that

govern the transport of pollutants are strongly influenced by

the movement of water. Other important factors governing the

fate of a pollutant is the solubility of the compound in water

and its rate of degradation (especially for pesticides) or

transformation into alternative compounds (e.g. for ammonia

to nitrate or nitrite). The movement of a pollutant from the

point where it was applied to some offsite location (vadose

zone, surface or ground water, or the atmosphere) represents a

complex interaction between the source (type of compound

and rate of application), fate (rate of degradation in the

environment and change to alternative compounds), and

transport (movement with water flow across or through the soil

profile or volatilization into the atmosphere). There have been

excellent reviews prepared on these topics that serve as

valuable references (e.g., Hatfield et al., 1999; Carpenter et al.,

1998; Sharpley et al., 2003, Hinga et al., 2005.

There are two critical components in the science-

based approaches that are used to study fate and transport.

These components are the spatial and temporal scales. The

spatial and temporal boundaries of different experimental

approaches that are used to develop more complete

understanding of the processes need to be understood. This is

important for the valid extension of these basic studies into

either physical or empirical models that are used to evaluate

the potential environmental quality impact of pollutants.

There are a variety of approaches to developing

models, and models are often developed for specific purposes.

These include from empirical models that relate fate or

transport to observed parameters, e.g., soil water content, soil

organic matter content, or depth of incorporation of a pesticide.

An example of an empirical model (based upon a statistical

correlation between factors) for a watershed scale is the

estimation of NO3-N concentration in the Raccoon River using

a four-factor (streamflow from the previous seven days, soil

moisture condition, and the cosine of the day of year and sin of

the day of the year) was developed by Lucey and Goolsby,

(1993). This model explained 70% of the variation in the NO3-

N concentrations. Physical models (those that describe the

physical processes that occur in the environment) tend to be

more complex. An example of this type of model is the Root

Zone Water Quality Model (RZWQM) as described by Ahuja

et al. (1999). Examples of the physical processes addressed

within the model include the water and chemical transport in

the soil matrix and macropores using transport grids with

hydraulic properties and estimated soil water content for each

grid. More complex models require the measurement or

estimation of more parameters. However, application of

RZWQM to a field scale within a watershed provided an

accurate estimate of the movement of herbicides into

subsurface drainage water (Bakhsh et al., 2004).

. Modeling agricultural watersheds is also needed to

capture and predict the effects of climatic differences among

watersheds. Models allow for the prediction of changes in

response to land management changes. The appendix to this

paper provides a more detailed discussion of some of the

models in use and being further refined for use in management

of agriculture to improve and protect water quality.

The Importance of Outreach and

Education

Development of technologies and practices through

sound-science represents a critical first step in the transfer of

knowledge from the science community to practitioners.

However, considerable evidence now exists that shows that

education and outreach to farmers and ranchers also is critical

to successful land management practices (e.g., Wuest et al.,

1999; Anciso et al., 2001; Mitchell et al., 2001; Marra et al.,

2003).

Acceptance of new technologies or practices often

lags well behind the development of these practices. Weise et

al. (1999) found that it took approximately four years for

grower education programs to produce measurable impacts in

nitrogen management. Mitchell et al., (2001) found that

expanding the number of demonstration sites for conservation

tillage increased farmer interest in practicing conservation

tillage. Farmer trust also is a critical issue in the adoption of

conservation practices (Anciso et al., 2001).

Education also is critical to farmers and ranchers

understanding the nature of risks involved with various

conservation practices (Marra et al., 2003). Risks to farmers

often involve economic impacts that must be evaluated prior to

their acceptance. Limited understanding of the economic

“costs” of environmental impacts often means that these

impacts are undervalued when considering adoption of

practices (see Schiffries and Brewster, 2004; Yiridoe and

Weersink, 1997).

Along with adoption of practices and technologies,

recent work has shown the importance of maintenance on the

long-term performance of conservation practices (Bracmort et

al. 2004; Mitchell et al., 2005). These studies highlight the

need for research to consider a longer life-span of conservation

technologies that includes performance of technologies long

after their implementation. In general, the diminished

performance of management practices after implementation

suggests that maintenance of practices and technologies is

critical to the long-term protection or improvement of water

quality.

Finally, farmers and ranchers are embracing the

concept of adaptive management in an effort to protect and

improve soil and water resources. This concept recognizes that

all practices do not work with the same effectiveness in all

locations (Jiggins and Roling, 2000; Nichols et al., 1995).

Therefore, new practices must be incorporated into existing

management plans to meet economic or environmental goals.

Where do we go from here?

Through this Tri-National Cooperation, we have

identified six key areas of future research and education for

agricultural water resources. These six areas transcend national

boundaries and represent research and education issues where


international cooperation holds considerable promise for

achieving needed progress.

1) Connecting Water Quantity and Quality – For much of the

past century, the science devoted to water quantity and

water quality has developed independently. This approach

has fostered a conceptual framework that allowed water

quality to be considered in the absence of water quantity.

Future research and education must re-connect these two

components of water as a resource – embracing a holistic

approach to water resource management. At the core of

this issue, we must recognize how, when, and where to

monitor water quality/quantity to more effectively manage

water resources.

2) Reducing the Pool of Reactive Nitrogen – Across North

America, the total pool of reactive nitrogen continues to

increase – degrading our air, soil, and water resources.

Future efforts in research and education must adopt a

“whole-systems approach” to nitrogen management. This

approach combines movement and storage of nitrogen in

feed, fertilizer, buffers, water bodies, and across the

landscape in an effort to control and ultimately decrease

the impacts of nitrogen pollution on the environment.

Ultimately, this will require coordination of research and

education programs that address water, soil, and air

quality so that nitrogen impacts on the environment can be

assessed and remedied in a coordinated fashion.

3) Human dimensions of management – Our understanding

of physical and chemical processes has progressed a great

deal over the past 50 years. Likewise, biological systems

(aquatic and estuarine ecosystems) have been the focus of

much recent research. However, we need to greatly

expand research and education on the social, economic,

and behavioral considerations that impact water resources

management. These human dimensions reflect the rich and

diverse cultures that exist in the three nations. Improved

understanding of human behavior (social, cultural, and

economic) ultimately will provide the key to expanded

adoption of best management practices.

4) The Unique Character of Large River Systems and their

Water Resources – Many large river systems cross or form

the boundaries of our three nations. It is essential that our

best science and education be directed at understanding

and managing these rivers. These large watersheds often

represent unique physical, biological, and social-economic

situations where difficult trade-offs must be made between

human and ecological needs and uses of water resources.

The unique character of these watersheds will require

close coordination and collaboration among our three

nations to effectively manage water resources.

5) Defining the limits of conservation practices – Many

conservation practices developed in one of our nations

have been adapted to new geographic locations across

North America. There is a need to explore the efficiencies

of these practices in a wide array of geographic settings. In

essence, we must ask ourselves “How far can we go with

conservation practices?” Are new conservation practices

needed? Sharing information among nations is the first

critical step in the process of fully evaluating and

understanding the limits of conservation practices.

6) Unraveling the cumulative impacts of land uses – Our

combined knowledge of the impacts of land uses in the

three nations has grown considerably over the past 50

years. However, we still lack a great deal of knowledge on

interactions among land uses at the watershed scale.

Addressing this issue involves a commitment to detailed

field-based and modeling efforts to investigate how

adjacent or “upstream” land uses impact the overall

quality of our water resources.

Take Home Message: Research and

Education

Tri-National cooperation creates an opportunity for

knowledge to be shared across international boundaries –

expanding what we know and how we use research

information in the three countries. Through our tri-national

cooperation, we have learned that we have common interests in

agricultural water resources research problems and we share

interests in taking actions to solve these problems at the

watershed scale.

Across North America, we have created a

considerable knowledge base on conservation management

practices (BMPs) to protect and improve water quality and

secure appropriate water resources. Our knowledge base is

strongest and most complete at the laboratory and plot scale.

However, the impact of conservation management practices is

more difficult to follow or trace at the watershed level.

Therefore, there is a critical need to “scale-up” from the

laboratory or plot scale to the watershed or larger scale.

Research has identified many improved farming

practices which have the potential to reduce the impact of

agriculture on water quality relative to common farm practice.

However, the achievement of improved water quality at the

watershed level, depends and upon proper adaptation of the

techniques to local conditions and upon wide acceptance of the

techniques. Good execution of the techniques requires

expertise and in bringing a knowledge and understanding of

the techniques to the farmer through agricultural extension and

support networks. Incentive programs to achieve adoption of

practices are discussed in a companion paper.

We recognize the need to develop appropriate

educational materials that complement science-based BMPs to

affect greater adoption and maintenance of these BMPs at the

watershed scale. Opportunities exist to take our best

educational programs and materials and explore options to

share these across international boundaries. We recognize the

challenges we face to ensure that educational programs and

information are suitable for the physical, biological, and

cultural context of a particular watershed.

Each of the three nations has developed a large body

of research on physical and biological aspects of agricultural

water quality and quantity. However, we have much less

information on how social and economic sciences fit into the

holistic approach of watershed based research and education

(see Figure 1). Future research and education programs should

be directed at the intersection of these three scientific

disciplinary areas.


Table 1. Current Status of Research Knowledge for Selected Agricultural Water Management Practices.

Spatial ScaleWater Management

Practice Lab-Plot Field Watershed

Irrigation Technology H H M

Water Reuse M M L

Plant Water Use /

Biotechnology

H L --

General Water

Conservation

M M L

Drought Preparedness and

Assessment

N/A L --

Water Markets and

Trading

N/A -- --

H – high, M – moderate, L – low, N/A – not applicable, -- information not available


Table 2. Examples of the magnitude of benefit of different on-field agricultural practices.

Practice Contaminant Example Reduction in

runoff or

inputs

Citation

In-season

optimization of

nitrogen

application

nitrogen North Carolina

wheat fields.

Nitrogen needs

evaluated on

fields or sub-

fields based

upon plant

growth

properties

Average 15%

(range 0 to 51%)

Flowers et al.,

2004

Polymer use in

furrow irrigation

systems

Sediments,

phosphorus

Pacific

Northwest

wheat and bean

fields. Added

supplents to

irrigation water

to bind

sediments &

phosphorus.

90% for

sediments,

50% for

phosphorus

Lentz and

Sojka, 1994,

Lentz et al.,

1998

Changing

chemical form of

fertilizer

phosphorus Fertilized New

Zealand pasture,

slow release

fertilizer vs.

single

superphosphate

Arkansas

pasture, organic

vs inorganic

fertilizer

90%

41%

Nguyen et al.,

1999, 2002

Nichols et al.,

1994, Hart et

al., 2004

Pesticide

resistant crop

varieties

pesticides Cotton, US

average

Reduction of 2

to 3 sprays per

year (or about

50%)

Marra et al.,

2002

Optimization of

applied irrigation

water

nitrate Lettuce

irrigation,

Salinas Valley

75% for nitrate Tanji et al.,

1994

Budgeting to

reduce excess

fertilizer

application

nitrogen

phosphorus

Netherlands 25% for

nitrogen

15% for

phosphorus

Oenema et al.,

2005

Controlled

drainage in tile-

drained fields

nitrogen Ohio

Ontario, maze

with ryegrass

45% for nitrate

46% for

nitrogen

Fausey, 2005

Drury et al.,

1996


intercrop

Ontario, maze

49% when used

with

conservation

tillage

36% for nitrate Ng et al., 2002

Hay Mulching sediments,

nitrogen,

phosphorous,

Potassium,

Calcium,

Magnesium

New

Brunswick,

Potato field

86-98% for

sediments

72-82% for

nutrients

Rees et al.,

2002


Table 3 Examples of the magnitude of the benefit of different off-field management practices.

Type of Control Runoff reduction Citation

Vegetated Buffer

7m grass buffer

7 meter grass buffer plus 9

meter wooded riparian zone

Iowa,

95% sediment

60% nitrogen and

phosphorus

97% sediment

80% nitrogen and

phosphorus

Schultz, 2004

Three-zone buffer grass to

wooded riparian zone,

Georgia,

78% nitrate

52% ammonium

66% phosphorus

Vellidis et al., 2003

Constructed wetlands to

receive water from tile-

drained fields

Illinois,

3 to 6% of drained area

46% nitrogen,

2% phosphorus

Kovacic et al., 2000

Diversion terraces/ grassed

waterway system

New Brunswick

95% sediments Chow et al., 1999


Table 4. Current Status of Research Knowledge for Selected Agricultural Contaminants

Spatial ScaleContaminant Developed

Management

practice

Lab-Plot Field Watershed

Sediment H H H M

Nitrogen H H M-H L-M

Phosphorous M M L --

Pesticides H H H L

Pathogens L L -- --

Salinity H M L --

Pharmaceuticals -- -- -- --

H – high, M – moderate, L – low, -- information not available


Table 5. List of Conservation Practices Established by the Natural Resources Conservation Service

Conservation PracticePractice

Code PracticePractice




CodeAccess Road (ft) 560 Contour Buffer Strips (ac) 332 Firebreak (ft) 394 Irrigation Storage

Reservoir (no & ac-ft)436 Land Reclamation, Toxic

Discharge Control (no)455

Alley Cropping (ac) 311 Contour Farming (ac) 330 Fish Passage (no) 396 Irrigation System,Sprinkler (no & ac)

442 Land Reconstruction,Abandoned Mined Land(ac)

543

Anaerobic Digester,Ambient Temperature (no)

365 Contour Orchard andOther Fruit Areas (ac)

331 Fish Raceway or Tank 398 Irrigation System, Surface& Subsurface (no & ac)

443 Land Reconstruction,Currently Mined Land (ac)

544

Anaerobic Digester,Controlled Temperature(no)

366 Cover Crop (ac) 340 Fishpond Management(no)

399 Irrigation System,Microirrigation (no & ac)

441 Land Smoothing (ac) 466

Animal Mortality Facility(no)

316 Critical Area Planting (ac) 342 Forage HarvestManagement (ac)

511 Irrigation System,Tailwater Recovery (no)

447 Lined Waterway or Outlet(ft)

468

Animal Trails andWalkways (ft)

575 Cross Wind Ridges (ac) 589A Forest Site Preparation(ac)

490 Irr. Water Conveyance,Ditch and Canal Lining,Plain Concrete (ft)

428A Manure Transfer (no) 634

Anionic Polyacrylamide(PAM) Erosion Control(ac)

450 Cross Wind Trap Strips(ac)

589C Forest StandImprovement (ac)

666 Irr. Water Conveyance,Ditch and Canal Lining,Flex. Membrane (ft)

428B Mine Shaft & Adit Closing(no)

457

Aquaculture Ponds (ac) 397 Dam, Diversion (no) 348 Forest Trails andLandings (ac)

655 Irr. Water Conveyance,Ditch and Canal Lining,Galvanized Steel (ft)

428C Mole Drain (ft) 482

Atmospheric ResourcesQuality Management (ac)

370 Dam (no & ac-ft) 402 Grade StabilizationStructure (no)

410 Irr. Water Conveyance,Pipeline, AluminumTubing (ft)

430AA Monitoring Well (ea) 353

Bedding (ac) 310 Deep Tillage (ac) 324 Grassed Waterway (ac) 412 Irr. Water Conveyance,Pipeline, Asbestos-Cement (ft)

430BB Mulching (ac) 484

Brush Management (ac) 314 Dike (ft) 356 Grazing Land MechanicalTreatment (ac)

548 Irr. Water Conveyance,Pipeline, NonreinforcedConcrete (ft)

430CC Nutrient Management,Excess Precondition (ac)

590

Channel Stabilization (ft) 584 Diversion (ft) 362 Heavy Use AreaProtection (ac)

561 Irr. Water Conveyance,Pipeline, High-pres.,Undergrd, Plastic (ft)

430DD Nutrient Management,Deficient Precondition (ac)

590

Channel Bank Vegetation(ac)

322 Drainage WaterManagement (ac)

554 Hedgerow Planting (ft) 422 Irr. Water Conveyance,Pipeline, Low-pres.,Undergrd, Plastic (ft)

430EE Obstruction Removal (ac) 500

Clearing & Snagging (ft) 326 Dry Hydrant (no) 432 Herbaceous WindBarriers (ft)

603 Irr. Water Conveyance,Pipeline, Steel (ft)

430FF Open Channel (ft) 582







CodeClosure of WasteImpoundments (no)

360 Early Successional HabitatDevelopment/Mgt. (ac)

647 Hillside Ditch (ft) 423 Irr. Water Conveyance,Pipeline, ReinforcedPlastic Mortar (ft)

430GG Pasture & Hay Planting(ac)

512

Composting Facility (no) 317 Feed Management (no &au)

592 Irrigation Canal or Lateral(ft)

320 Irr. Water Conveyance,Pipeline, Rigid GatedPipeline (ft)

430HH Pest Management,Chemical (ac)

595

Conservation Cover (ac) 327 Fence (ft) 382 Irrigation Field Ditch (ft) 388 Irrigation WaterManagement (ac)

449 Pest Management, Cultural(ac)

595

Conservation CropRotation (ac)

328 Field Border (ft) 386 Irrigation Land Leveling(ac)

464 Land Clearing (ac) 460 Pest Management,Biological (ac)

595

Constructed Wetland (no) 656 Filter Strip (ac) 393 Irrigation RegulatingReservoir (no)

552 Land Reclamation,Landslide Treatment (no& ac)

453 Pipeline (ft) 516

Pond (no) 378 Residue Management,Mulch Till (ac)

329B Shallow WaterManagement for Wildlife(ac)

646 Tree/Shrub Pruning (ac) 660 Water and SedimentControl Basin (no)

638

Pond Sealing or Lining,Flexible Membrane (no)

521A Residue Management,Ridge Till (ac)

329C Spoil Spreading (ac) 572 Underground Outlet (ft) 620 Waterspreading (ac) 640

Pond Sealing or Lining,Soil Dispersant (no)

521B Residue Management,Seasonal (ac)

344 Spring Development (no) 574 Upland Wildlife HabitatManagement (ac)

645 Wildlife Watering Facility(no)

648

Pond Sealing or Lining,Bentonite Sealant (no)

521C Restoration andManagement of DecliningHabitats (ac)

643 Streambank and ShorelineProtection (ft)

580 Use Exclusion (ac) 472 Windbreak/ShelterbeltEstablishment (ft)

380

Precision Land Forming(ac)

462 Riparian Forest Buffer (ac) 391 Stream HabitatImprovement andManagement (ac)

395 Vegetative Barrier (ft) 601 Windbreak/ShelterbeltRenovation (ft)

650

Prescribed Burning (ac) 338 Riparian HerbaceousCover (ac)

390 Stripcropping (ac) 585 Vertical Drain (no) 630 Water Well (no) 642

Prescribed Grazing (ac) 528 Rock Barrier (ft) 555 Structure for WaterControl (no)

587 Waste Facility Cover (no) 367 Well Decommissioning(no)

351

Pumping Plant (no) 533 Roof Runoff Structure (no) 558 Subsurface Drain (ft) 606 Waste Storage Facility(no)

313 Wetland Creation (ac) 658

Range Planting (ac) 550 Row Arrangement (ac) 557 Surface Drainage, FieldDitch (ft)

607 Waste Treatment Lagoon(no)

359 Wetland Enhancement (ac) 659

Recreation AreaImprovement (ac)

562 Runoff ManagementSystem (no & ac)

570 Surface Drainage, Mainor Lateral (ft)

608 Waste Utilization (ac) 633 Wetland Restoration (ac) 657







CodeRecreation Land Gradingand Shaping (ac)

566 Salinity and Sodic SoilManagement (ac)

610 Surface Roughening (ac) 609 Wastewater TreatmentStrip (ac)

635 Wetland Wildlife HabitatManagement (ac)

644

Recreation Trail andWalkway (ft)

568 Sediment Basin (no) 350 Terrace (ft, m) 600 Water HarvestingCatchment (no)

636

Residue Management, NoTill/Strip Till (ac)

329A Silvopasture Establishment(ac)

381 Tree/Shrub Establishment(ac)

612 Watering Facility (no) 614


Table 6. Example of Natural Resources Conservation Service Spreadsheet Describing the Conservation Practice Effects As They Are LikelyTo Impact Soil Erosion Processes.

PracticePractice

Code

Soil Erosion -Sheet and Rill

(Effect)Soil Erosion -Wind (Effect)

Soil Erosion -Ephemeral

Gully (Effect)

Soil Erosion -Classic Gully

(Effect)

Soil Erosion -Streambank

(Effect)

Soil Erosion -Shoreline(Effect)

Soil Erosion –Irrigation-induced

(Effect)

Soil Erosion -Mass

Movement(Effect)

Soil Erosion –Road, road sidesand Construction

Sites (Effect)Alley Cropping (ac) 311 Substantial

DecreaseSubstantialDecrease

SubstantialDecrease

ModerateDecrease

Not Applicable NotApplicable

SubstantialDecrease

ModerateDecrease

Not Applicable

Animal Trails and Walkways(ft)

575 Slight toSubstantialDecrease

Slight toSubstantialDecrease


Moderate toSubstantialDecrease



Not Applicable SlightDecrease


Brush Management (ac) 314 Slight toSubstantial

Increase




SlightDecrease

SlightDecrease

Not Applicable Slight toModerateIncrease

Not Applicable

Cover Crop (ac) 340 Slight toModerateDecrease

Slight toModerateDecrease


SlightDecrease

NA NotApplicable


No Effect Slight toSubstantialDecrease

Grassed Waterway (ac) 412 No Effect No Effect SubstantialDecrease

Slight toSubstantial

Increase

SlightDecrease

SlightDecrease

Not Applicable No Effect No Effect

Residue Management, NoTill/Strip Till (ac)

329A Slight toSubstantialDecrease



SlightDecrease



SlightIncrease

NA

Residue Management, MulchTill (ac)

329B Slight toModerateDecrease



SlightDecrease



SlightIncrease

NA

Residue Management, RidgeTill (ac)

329C Slight toModerateDecrease



SlightDecrease



SlightIncrease

NA

Riparian Forest Buffer (ac) 391 SubstantialDecrease

SubstantialDecrease

SubstantialDecrease

ModerateDecrease

ModerateDecrease

ModerateDecrease

Not Applicable ModerateDecrease

Not Applicable

Riparian Herbaceous Cover(ac)

390 SubstantialDecrease

Moderate toSubstantial

Increase

SubstantialDecrease




Not Applicable SlightDecrease

Not Applicable

Windbreak/ShelterbeltEstablishment (ft)

380 Slight toSubstantialDecrease

SubstantialDecrease





ModerateDecrease

Not Applicable


Figure 1. Relationship between physical-chemical, biological, and social sciences in holistic watershed

approach.

Figure 2. Total Water Withdrawals for various water use sectors in the United States, 2000 (USGS,

2004).

Thermoelectric

48%

Irrigation

34%

Industrial

5%

Public

Supply

11%

Domestic < 1%

Mining <1%

Aquaculture <1%

Livestock <1%

Water Withdrawals in the United States in

2000

Source: USGS (2004)

Physic

al

–Che

i l

Biologi

cal

Scienc

SocialSciences

HolisticWatershed


Figure 3. Water use in Canada over time by sector.

Figure 4. Percent of water withdrawals by sector in Mexico. (Data from Gleick, 2002)

Water Use in Mexico

0

10

20

30

40

50

60

70

80

90

Agriculture Domestic Use Industry

Percen

t o

f w

ate

r w

ith

draw

als


Figure 5. Farmers along Missouri River are using floating pumps to collect irrigation water and toreduce streambank erosion. A web site is available to evaluate stream bank stability:http://msa.ars.gov/ms/oxford/nsl/cwp_unit/Montana_Report.html.

Figure 6. Conservation forested buffers like the one shown below provide protection from manurenutrients running-off farmer fields into ponds and downstream streams in South Georgia. .


Figure 7. The Mahantango Creek Watershed near Klingerstown, Pennsylvania, shows forest, farmland,and other land uses typical of watersheds. ARS scientists at University Park, Pennsylvania, and CornellUniversity at Ithaca, New York are applying lessons learned from this watershed to their CEAP studiesin New York's Town Brook Watershed.


Appendix. Models for predicting effects

of agricultural practices on water

quality.

The USDA - Agricultural Research Service (ARS) has

developed a series of natural resource models that span the

scale from field to watershed to basin. Each of these

models was designed to address a specific suite of water

quality problems. Examples of models that are available to

the public and are listed in Table 7.

Table 7. Examples of USDA Agricultural Research Service

Natural Resource Models for Predicting the Impact of

Conservation Practices on Water Quality

Model Scale Water Quality

Concern

RUSLE Field Soil Erosion

WEPP Field & Small

Watershed

Soil Erosion

RZQWM Field Nutrients &

Pesticides

AnnAGNPS Watershed Erosion,

Nutrients,

Pesticides

SWAT Watershed &

Basin

Erosion,

Nutrients,

Pesticides,

Pathogens

The NRCS and other State and Federal Action

Agencies have a critical need for a computer program thatcan estimate interrill and rill erosion for farm planning

purposes for a wide range of soil, weather, topography, and

agricultural conditions and practices. ARS and NRCS have

led this effort since July 1998, in cooperation with the

University of Tennessee and the NRCS, to update the

Revised Universal Soil Loss Equation (RUSLE2). RUSLE2

is a land use independent management tool. Prior to the

existing CRIS project, the Development Team developed

and assisted in: (1) improving scientific relationships in

selected areas including the desegregation of monthly

weather values into bimonthly and daily values; (2)formulating new equations for temporally variable soil

erodibility factors; (3) developing new relationships for the

effect of ridges on soil loss and decay of ridges with time;

(4) developing new relationships for surface cover, land

management, and use; (5) using new relationships for

computing particle distributions where deposition occurs;

and (6) developing a new routing procedure for strip

cropping and terraces. During the current CRIS project,

some 70 major RUSLE2 science improvements were

introduced. These improvements have substantially

broadened the usefulness, versatility, and accuracy of

RUSLE2 as a soil erosion prediction and soil erosioncontrol management tool. Development of RUSLE2 as an

independent land use conservation planning tool for erosion

by water has been one of the most significant

accomplishments of a practical nature in erosion prediction.

RUSLE2 has been implemented in all NRCS field offices

and has been adopted by the USDI Office of Surface

Mining (OSM) and USDI Bureau of Land Management(BLM). It is also the key component in the AnnAGNPS

watershed prediction model. The model and documentation

can be downloaded at

http://fargo.nserl.purdue.edu/rusle2_dataweb/RUSLE2_Ind

ex.htm.

ARS scientists have also worked together to

develop new technology to assist the U.S. Forest Service

(USFS) in predicting surface runoff and soil erosion rates

that results from both wild and prescribed fires in western

ecosystems. This research is now helping the USFS Burn

Areas Emergency Rehabilitation teams on how best to

decide where and when emergency funding is needed toreestablish vegetation or install physical structures needed

to protect the environment, streams, human life, property,

or infrastructure from the ravages that are caused from

flooding or soil erosion on public and private lands. The

enhanced Water Erosion Prediction Project (WEPP) tool is

available to U.S. Forest Service and other land managers

via an interactive internet-based decision support system

maintained by the U.S. Forest Service in Moscow, Idaho.

This model and all supporting documentation with an index

to over 200 publications documenting the science and

application of the WEPP model and supporting databasesfor cropland and pastureland applications can be

downloaded at

http://topsoil.nserl.purdue.edu/nserlweb/weppmain/. The

forest application version can be downloaded at

http://forest.moscowfsl.wsu.edu/engr/wepp0.html.

Root Zone Water Quality Model (RZWQM)

focuses on management effects on crop production, soil,

and water quality. Root Zone Water Quality Model

simulates major physical, chemical, and biological

processes in an agricultural crop production system.

RZWQM is a one-dimensional (vertical in the soil profile)

process-based model that simulates the growth of the plantand the movement of water, nutrients and agro-chemicals

over, within and below the crop root zone of a unit area of

an agricultural cropping system under a range of common

management practices. The model includes simulation of a

tile drainage system. The primary use of RZWQM will be

as a tool for assessing the environmental impact of

alternative agricultural management strategies on the

subsurface environment. These alternatives may include:

conservation plans on field-by- filed basis; tillage and

residue practices; crop rotations; planting date and density;

and irrigation, fertilizer, and pesticide-scheduling (methodof application, amounts and timing). The model predicts the

effects of these management practices on the movement of

nitrate and pesticides to runoff and deep percolation below

the root zone. That is, the model predicts the potential for

pollutant loadings to the groundwater thus allowing an

assessment of nonpoint-source pollutant impacts on surface


and ground water quality. This model and supporting

documentation can be downloaded at

http://gpsr.ars.usda.gov/products/rzwqm.htm.

The focus on sediment pollution criteria has been

fueled by a renewed effort for states to identify pollution-

impaired water bodies and develop plans for meeting TotalMaximum Daily Loads (TMDLs) as specified by the Clean

Water Act of 1972. Current estimates are that physical,

chemical, and biological damage associated with sediment

flow costs about $16 billion annually in North America.

ARS scientists in Oxford, Mississippi, have recently

developed a two-pronged modeling approach to identify

sediment movement in streams and other water bodies. The

Annualized Agricultural Non-Point Source Pollutant

(AnnAGNPS) watershed model first evaluates loadings

within a watershed and the effect farming and other

activities have on pollution control. Then, the

Conservational Channel Evolution and Pollutant TransportSystems (CONCEPTS) model predicts how channel

evolution and pollutant loadings will be affected by bank

erosion and failures, streambed buildup and degradation,

and streamside riparian vegetation. By combining the field

measurements, geomorphic analysis, and the numerical

models, agricultural specialists are now able to make

effective recommendations on the type and placement of

conservation practices either in the watershed or the stream

channel that will provide the greatest benefits. New to

AnnAGNPS Version 3.51 includes an aquaculture feature

and more input and output options. The capabilities ofRUSLE, used by USDA-NRCS to evaluate the degree of

erosion on agricultural fields and to guide development of

conservation plans to control erosion, have been

incorporated into AnnAGNPS. This provides a watershed

scale aspect to conservation planning. The channel network

evolution model has been updated and enhanced as

CCHE1D, and the stream corridor model CONCEPTS, has

been developed for analysis of reaches within a stream

network, for watersheds that require a more comprehensive

evaluation of the stream system, when channel evolution,

erosion, or in-stream structures produce problems that the

simplified channel system of AnnAGNPS is not designedfor. Detailed descriptions of the components, with example

datasets, and the programs can be download page at

http://www.ars.usda.gov/Research/docs.htm?docid=5199.

Vegetative, or conservation, buffers that include

trees or forests can serve many different purposes all aimed

at the same goal – cleaner water. ARS scientists in Tifton,

Georgia, in partnership with the University of Georgia,

have recently completed a 9-year study to determine

whether restored conservation buffer zones in wetlands next

to agricultural fields can reduce the amounts of phosphorus

and nitrogen that reach streams (see Figure 6). Thesestudies showed that the restored riparian wetland buffer

retained or removed at least 60 percent of the nitrogen and

65 percent of the phosphorus that entered from the adjacent

manure application site. Although conservation buffers are

not a magic bullet, it has become clear that trees or forests

must be part of the conservation buffer system if nitrogen

and phosphorus and other pollutants are going to be

effectively removed. Novel research being conducted by

ARS scientists in the southeastern U.S. has demonstrated

that forested areas can be managed with long-term

strategies to provide wood products or biofuels while

maintaining water quality. Nutrient total maximum dailyload (TMDL) assessments of the Suwannee River Basin of

Georgia and Florida have indicated a need for nitrogen

nonpoint source pollution reduction from agriculture.

Forested lands adjacent to agricultural fields have been

shown to reduce nitrogen concentration of water moving

from the fields to adjacent streams and waterways

(Lowrance et al 1997, Lowrance et 1998a, Lowrance and

Leonard 1998, Lowrance et al 2000, and Lowrance and

Sheridan 2005).

Lowrance et al. (2000) and his colleagues have

determined that forested zones bordering agricultural fields

can be harvested for lumber, fuel wood or pulpwood andstill function as filters for groundwater nitrate reduction.

Based on these and other field experiments ARS scientists

developed the Riparian Ecosystem Management Model

(REMM) to help design and predict the water quality

benefits of both grass and forested riparian and wetland

areas. Conservation or riparian buffers are effective in

mitigating nonpoint source pollution and have been

recommended as a best management practice (BMP). The

REMM decision support system has been developed for

researchers and natural resource agencies as a modeling

tool that can help quantify the water quality benefits ofriparian buffers under varying site conditions. Processes

simulated in REMM include surface and subsurface

hydrology; sediment transport and deposition; carbon,

nitrogen, and phosphorus transport, removal, and cycling;

and vegetation growth. Management options, such as

vegetation type, size of the buffer zone, and biomass

harvesting also can be simulated. REMM can be used in

conjunction with upland models, empirical data, or

estimated loadings to examine scenarios of buffer zone

design for a hillslope. Evaluation of REMM simulations

with field observations shows generally good agreement

between simulated and observed data for groundwaternitrate concentrations and water table depths in a mature

riparian forest buffer. Sensitivity analysis showed that

changes that influenced the water balance or soil moisture

storage affected the streamflow output. Parameter changes

that influence either hydrology or rates of nutrient cycling

affected total N transport and plant N uptake.

SWAT, which stands for Soil and Water

Assessment Tool, was developed over the past 30 years by

a team of ARS researchers at Temple, Texas, in cooperation

with other ARS scientists in Bushland, TX, El Reno, OK,

Tucson, AZ, Ft. Collins, CO, Miami, FL, Ames, IA, andTifton, GA. Over the past 4 years, the U.S. Environmental

Protection Agency and ARS have made SWAT available to

State agencies and consultants throughout the nation to

evaluate and assess water quality impairments and to assist

in developing watershed plans for addressing specific

problems. The Natural Resources Conservation Service


used the SWAT model in its 1997 Resource Conservation

Appraisal, in which the first national assessment of

agricultural water use, tillage systems and fertilizer

management was made. In 2004, NRCS and ARS are again

using SWAT to work together to quantify the

environmental benefits of conservation practices at thenational scale and the watershed scale for the Conservation

Effects Assessment Project (CEAP). The newest version of

SWAT has been distributed to hundreds of scientists and

engineers at universities, government agencies, and

consulting firms throughout the world and several

international training conferences have been held over the

past 2 years and is used as the standard method to address

Total Daily Maximum Load calculating required to meet

water quality standards with the United States. The SWAT

model and documentation can be downloaded at

http://www.brc.tamus.edu/swat/index.html or from the US

Environmental Protection Agency through their BASINSweb site (http://www.epa.gov/OST/BASINS/).

The NRCS and the ARS are working together on

the Conservation Effects Assessment Project (CEAP) to

quantify the environmental benefits of conservation

practices at the national level and at watershed-scales.

CEAP is an on-going mix of data collection, model

development, model application, and research. One of the

goals is to develop the appropriate databases and model

applications over the course of the project. CEAP is a

multi-agency effort that will also include involvement from

groups outside of the Federal government. USDAcollaborators include the Farm Service Agency (FSA),

Cooperative State Research, Education, and Extension

Service (CSREES), the National Agricultural Statistics

Service (NASS), and the Office of Risk Assessment and

Cost Benefit Analysis (ORACBA).

There are two main components of CEAP, the

national assessment and the watershed assessment

(Mausbach and Dedrick 2004). The national assessment

component will provide modeled estimates of conservation

benefits for annual reporting. The purpose of the national

assessment is to provide an accounting of the environmental

benefits obtained from USDA conservation programs. At a

finer scale the watershed assessment component will

provide detailed, landscape-specific assessments ofenvironmental benefits that are not possible at the national

scale. A framework for evaluating and improving the

performance of the national assessment models and

research on conservation practices and their expected

effects at the watershed scale will also be developed. The

watershed assessment studies component of CEAP

complements the national assessment by providing more in-

depth assessment of water quality and other benefits at a

finer scale of resolution than is possible for the national

assessment (see Figure 7). An extensive body of literature

exists that describes plot or field-scale conservation

practices aimed at protecting water quality, and in somecases, improving soil quality or enhancing water

conservation [Hapeman et al. (2003), Hatfield et al. (2001),

Howell (2001), and Sharpley et al. (2003)]. However,

research results from plot- and field-scale studies are

limited in that they cannot capture the complexities and

interactions of conservation practices within a watershed.

Only 28 watersheds have been selected for study. No

attempt will be made to aggregate estimates of benefits for

the watershed studies to represent national-level estimates,

since too many watersheds would be needed to properly

represent the various environmental and resource-basedcharacteristics in the country. The objective is to select

watersheds where there is on-going work (either monitoring

or modeling or both) in agricultural areas with databases

and resource. Results from the CEAP research project

should be available in 2007. Details of the CEAP project

can be found on the NRCS web site

http://www.nrcs.usda.gov/technical/NRI/ceap/.


Literature Cited

Ahuja, L.R., K.W. Rojas, J.D. Hanson, M.J. Shaffer, and

L. Ma. (editors) 1999. Root Zone Water Quality

Model. Water Resources Publications LLC.

Highlands Ranch, CO. 360 pp.

Anciso, J.R., G.E. Trevino, and N. Torres, 2001. IPM

implementation and acceptance by cucurbitgrowers over a 5 year period in the Lower Rio

Grande Valley, Texas, Subtropical Plant Science,

v. 53, p. 40-43.

Bakhsh, A., L. Ma, L.R. Ahuja, J.L. Hatfield, and R.S.

Kanwar. 2004. Using RZWQM to predict

herbicide losses in subsurface drainage water.

Trans. ASAE. 47:1415-1426.

Bracmort, K.S., B.A. Engel, J.R. Frankenberger. 2004.

Evaluation of structural best management

practices 20 years after installation: Black Creek

Watershed, Indiana. Journal of Soil and WaterConservation 59(5):191-196.

Carpenter, S.R., N.F. Caraco, D.L. Correll, R.W. Howarth,

A.N. Sharpley, and V.H. Smith, 1998. Nonpoint

pollution of surface waters with phosphorous and

nitrogen, Ecological Applications, v. 8, p. 559-

568.

Cessna, A. J., J. A. Elliott, L. Tollefson, W. Nicholaichuk.

2001. Herbicide and nutrient transport from an

irrigation district into the South Saskatchewan

River. J. Environ. Qual. 30:1796-1807.

Cha, J.M., Yang, S., Carlson, K.H., 2005. Rapid analysis

of trace levels of antibiotic polyether ionophoresin surface water by solid-phase extraction and

liquid chromatography with ion trap tandem mass

spectrometric detection. Journal of

Chromatography. A, v.1062 p. 531.

Chambers, P. A., R. Meissner, F. J. Wrona, H. Rupp, H.

Guhr, J. Seeger, J. M. Culp, R. B. Brua. 2006.

Changes in nutrient loading in an agricultural

watershed and its effects on water quality and

stream biota. Hydrobiologia 556: 399-415.

Chow, T. L. H. W. Rees, J. L. Daigle 1999. Effectiveness

of terraces/grassed waterway systems for soil andwater conservation: A field evaluation. J. Soil

and Water Conserv. 54: 577-583.

Chow, T. L., H. W. Rees. J. Monteith. 2000. Seasonal

distribution of runoff and soil loss under four

tillage treatments in upper St. John River valley

New Brunswick, Canada. Can. J. Soil. Sci. 80:

649-660.

. Church, M., 2002. Geomorphic thresholds in riverine

landscapes, Freshwater Biology, v. 47, p. 541-

557.

Cohen, S., D. Neilsen, R. Welbourn.(eds.) 2004.

Expanding the dialogue on Climate Change &

Water Management in the Okanagan Basin,

British Columbia.. Final report Climate Change

Action Fund A463/433, Natural Resources

Canada, 230pp.

Colby, B. G. and T.P. dEstree., 2000. Evaluating Market

Transactions, Litigation and Regulation as Tools

for Implementing Environmental Restoration,

Arizona Law Review 42:381-394.

Dobrowolski, J.P. and M.P. O’Neill, 2005. Agricultural

Water Security Listening Session: Final Report,United States Department of Agriculture,

Washington, D.C., 52 pp.

Drury, C.C, Tan, C.S., Gaynor, J.D., Oloya, T.O.,

Welacky, T.W. 1996 Influence of controlled

drainage-subirrigation on surface and tile

drainage nitrate loss, Journal of environmental

Quality 25:317-324

Dyer, A. R., D. R. Raman, M. D. Mullen, R. T. Burns, L.

B. Moody, A. C. Layton, and G. S. Sayler. 2001.

Determination of 17beta-estradiol concentrations

in runoff from plots receiving dairy manure.ASAE Paper No. 012107. ASAE, St. Joseph, MI.

Elliott, J. A., A. J. Cessna, K. B. Best, W. Nicholaichuk.,

L. C. Tollefson. 1998. Leaching and preferential

flow of clopyralid under irrigation: Field

observations and simulation modeling. J.

Environ. Qual. 27:124-131.

Elliott, J. A., A. J. Cessna W. Nicholaichuk, L. C.

Tollefson. 2000. Leaching rates and preferential

flow of selected herbicides through tilled and

untilled soil. J. Environ. Qual. 29: 1650-1656.

Environment Canada. 2005. Quickfacts website

http://www.ec.gc.ca/water/en/e_quickfacts.htm

Fairchild, G. L., D. A. J. Barry, M. J. Goss, A. S. Hamill,

P. Lafrance, P. H. Milburn, R. R. Simard and B. J.

Zebarth. 2000. Groundwater Quality. pgs 61-74,

In: D. R. Coote and L. J. Gregorich (eds). The

Health of our Water: Towards Sustainable

Agriculture in Canada. Agriculture and

Agriculture Canada Pub 2020E, 173 pp.

Fangmeier, D.D., A. J. Clemmens, M. El-Ansary, T. S.

Strelkoff, H. E. Osman, 1999. Influence of land

leveling precision on level-basin advance and

performance, Transactions, ASAE, v. 42, p. 1019-1025.

Flowers, M., Weisz, R., Heiniger, R., Osmond, D., Crozier, C.,

2004. In-season optimization and site-specific nitrogen

management for soft red winter wheat. Agronomy Journal

96: 124-134.

Fausey, N. 2005 Drainage management for humid regions,

International Agricultural Engineering Journal

14:209-214.


Gagnon, S.R., J.R. Makuch, and T.J. Sherman, 2004.

Environmental Effects of U.S. Department of

Agriculture Conservation Programs: A

Conservation Effects Assessment bibliography,

Special Reference Brief 2004-01, U.S.

Department of Agriculture, Washington, D.C.,138 pp.

Gilliom, R.J., 2001. Pesticides in the hydrologic system:

what do we know and what’s next?, Hydrological

Processes, v. 15, p. 3197-3201.

Gleick, P.H., 2002. The World’s Water – The Biennial

Report on Freshwater Resources, Island Press,

334 p.

Gold, A.J. P.M Groffman, K. Addy, D.Q. Kellogg, M.

Stolt, and A.E. Rosenblatt, 2001. Landscape

attributes as controls on ground water nitrate

removal capacity of riparian zones, Journal of the

American Water Resources Association, v. 37, p.1457-1464.

Hanselman, T.A., D.A. Graetz, and A.C. Wilkie, 2003.

Fate of poultry manure estrogens in soils: a

review, Soil and Crop Science Society of Florida,

Proceedings, v. 62, p. 8-12.

Hart, M.R., Quinn, B.F., Nguyen, M.L., 2004. Phosphorus

runoff from agricultural land and direct fertilizer

effects: a review. Journal of Environmental

Quality 33, 1954-1972.

Hatfield, J.L., D.B. Jaynes, M.R. Burkart, C.A.

Cambardella, T.B. Moorman, J.H. Prueger, J.H.and M.A. Smith. 1999. Water Quality in Walnut

Creek Watershed: Setting and Farming Practices.

J. Environ. Qual. 28:11-24.

Hinga, K.R., Batchelor, A., Ahmed, M.T., Osibanjo, O., Lewis, N.,

M.Pilson, 2006. Waste processing and detoxification,

Chapter 15. In: Hassan, R., Scholes, R., Ash, N. (Eds.),

Ecosystems and Human Well-Being: Current State and

Trends. Isand Press, Washington, DC, pp. 417-439.

Horbulyk, T. M. 2005. Markets, Policy and the

Allocation of water resources among sectors:

constraints and opportunities. Can. Water Res. J.

30: 55-64.Hapeman, C. J., McConnell, L. L., Rice, C. P., Sadeghi,

A.M., Schmidt, W. F., McCarty, G. W., Starr, J.

L., Rice, P. J., Angier, J. T., and Harman-Fetcho,

J.A. (2003) Current United States Department of

Agriculture - Agricultural Research Service

Research on Understanding Agrochemical Fate

and Transport to Prevent and Mitigate Adverse

Environmental Impacts, Pest Management

Science 59 (6-7): 681-690.

Hatfield, J.L., Sauer, T. J., and Prueger, J. H. (2001)

Managing Soils to Achieve Gretaer Water UseEfficiency: A Review, Agronomy Journal 93(2)

271-280.

Hatfield, J.L., Bucks, D.A., and Horton, M.L. (2000) The

Midwest Water Quality Initiative: Research

Experiences at Multiple Scales. In: Agrochemical

Fate and Movement: Perspective and Scale of

Study (Steinheimer, T.R., L.J. Ross, and T.D.

Spittler eds.) American Chemical Society,

Washington, DC., p. 232-247.

Hatfield, J.L., D.B. Jaynes, M.R. Burkart, C.A.

Cambardella, T.B. Moorman, J.H. Prueger, J.H.

and M.A. Smith. 1999. Water Quality in WalnutCreek Watershed: Setting and Farming Practices.

J. Environ. Qual. 28:11-24.

Howarth, R.W., G. Billen, D. Swaney, A. Townsend, N.

Jaworski, and K. Lathja 1996. Regional nitrogen

budgets and riverine N & P fluxes for the

drainages to the North Atlantic Ocean: natural

and human influences, Biogeochemistry, v. 35, p.

75-139.

Howell, T.A. (2001) Enhancing Water Use Efficiency in

Irrigated Agriculture. Agronomy Journal 93(2)

281-289.

Huffaker, R.G., and N. Whittlesey. 2003. A TheoreticalAnalysis of Economic Incentive Policies

Encouraging Agricultural Water Conservation.

International Journal of Water Resources

Development, p. 37-53.

Hunsaker, D.J., A. J. Clemmens, D. D. Fangmeier, 1999.

Cultural and irrigation management effects on

infiltration, soil roughness, and advance in

furrowed level basins, Transactions of the ASAE,

1999, v. 42, p. 1753-1762.

Jiggins, J. and N. Roling, 2000. Adaptive management:

potential and limitations for ecologicalgovernance, International Journal of Agricultural

Resources, Governance, and Ecology, v. 1, p. 28-

42.

Keinholz, E., F. Croteau, G. I. Fairchild, G. K. Guzzwell,

D. I. Massé and T. W. Van der Gulik. 2000. pgs

15-26, In: D. R. Coote and L. J. Gregorich (eds).

The Health of our Water: Towards Sustainable

Agriculture in Canada. Agriculture and

Agriculture Canada Pub 2020E, 173 pp.

Kovacic, D.A., David, M.B., gentry, L.E., Starks, K.M., Cooke,

R.A., 2000. Effectiveness of constructed wetlands in

reducing nitrogen and phosphorus export from agriculturaltile drainage Journal of Environmental Quality 29, 1262-

1274.

Larson, S.J., R.J. Gillom, and P. Capel, 1999. Pesticides in

streams of the United States: Initial results from

the National Water-Quality Assessment Program,

U.S. Geological Survey, 92 pp.

Lentz, R.D., Sojka, R.E., 1994. Field results using polyacrylamide

to manage furrow erosion and infiltration. Soil Science

158, 274-282.

Lentz, R.D., Sojka, R.E., Robbins, C.W., 1998. Reducingphosphorus losses from surface-irrigated fields: emerging

polyacrylamide technology. Journal of Environmental

Quality 27, 305-312.

Lorenzen, A, R, Chapman, J. G. Hendel, E. Topp.

Persistence and pathways of testosterone


dissipation in agricultural soil. J. Environ Qual.

34: 854-860.

Lowery, B., R.C. Hartwig, D.E. Stoltenberg, K.J.

Fermanich, and K. McSweeney, 1998.

Groundwater quality and crop-yield responses to

tillage management on a Sparta sand, Soil andTillage Research, v. 48, p. 225-237.

Lowrance, R. 1992, Groundwater nitrate and

denitrification in a coastal plain riparian forest,

Journal of Environmental Quality, v. 21, p. 401-

405.

Lowrance, R., L.S. Altier, J.D. Newbold, R.R. Schnabel,

P.M. Groffman, J.M. Denver, J.W. Gilliam, and

J.L. Robinson. 1997. Water quality functions of

riparian forest buffers in Chesapeake Bay

watersheds. Environmental Management 21:687-

712.

Lowrance, R. ; Altier, L.S. ; Williams, R.G. ; Inamdar, S.P.; Sheridan, J.M. ; Bosch, D.D. ; Hubbard, R.K. ;

Thomas, D.L. 2000. REMM: The Riparian

Ecosystem Management Model 2000. Journal of

Soil and Water Conservation. 55:200-211.

Lowrance, R. and R. A. Leonard. 1988. Streamflow

nutrient dynamics in coastal plain watersheds.

Journal of Environmental Quality 17:734-740.

Lowrance, R., R.K. Hubbard, and R.G. Williams. 2000.

Effects of a managed three-zone riparian buffer

system on shallow groundwater quality in the

southeastern coastal plain. Journal of Soil and

Water Conservation 55:212-220.

Lowrance, R. S. McIntyre, and C. Lance. 1988. Erosion

and deposition in a field/forest system estimated using

cesium-137 activity. Journal of Soil and Water

Conservation 43:195-199.

Lowrance, R. and J.M. Sheridan. 2005. Surface runoff

water quality in a managed three zone riparian

buffer. Journal of Environmental Quality

34(5):1851-1859.

Lu, Z. X., D. Lapen, A. Scott, A. Dang, E. Topp. 2005.

Identifying host sources of fecal pollution:

Diversity of Escherichia coli in confined dairyand swine production systems. Appl. And

Environ. Microbiol. 71: 5992-5998.

Lucey, K.J. and D.A. Goolsby. 1993. Effects of climatic

variations over 11 years on nitrate-nitrogen

concentrations in the Raccoon River, Iowa. J.

Environ. Qual. 22:38-46.

Madsen, J. D., P. A. Chambers, W. F. James, E. W. Koch,

D. F. Westlake. 2001. The interaction between

water movment, sediment dynamics and

submersed macrophytes. Hdrobiologia 444: 71-

84.Makuch, J.R., S.R. Gagnon, and T.J. Sherman, 2004a.

Agricultural Conservation Practices and Related

Issues: Reviews and the State of the Art and

Research Needs: A Conservation Effects

Assessment bibliography, Special Reference Brief

2004-04, U.S. Department of Agriculture,

Washington, D.C., 398 pp.

Makuch, J.R., S.R. Gagnon, and T.J. Sherman, 2004b.

Implementing Agricultural Conservation

Practices: Barriers and Incentives: A

Conservation Effects Assessment bibliography,Special Reference Brief 2004-02, U.S.

Department of Agriculture, Washington, D.C.,

107 pp.

Marra, M.C., Pardey, P.G., Alston, J.M., 2002. The Payoffs to

Agricultural Biotechnology: An Assessment of the

Evidence, EPTD Discussion Paper. International Food

Policy Research Institute, Washington, DC.

Marra, M., D.J. Pannell, and A.A. Ghadim, 2003. The

economics of risk, uncertainty and learning in the

adoption of new agricultural technologies: where

are we on the learning curve?, Agricultural

Systems, v, 75, p. 215-234.Mausbach, M.J. and A.R. Dedrick. The Length W Go.

2004. Soil and Water Conservation Journal. 59:1-

6.

Mitchell, J.P., E.M. Miyao, M. McGiffen, and M.D. Cahn,

2001. Conservation tillage research and extension

education in California, HortScience, v. 36, p.

472.

Mitchell Adeuya, R. K., K. J. Lim, B. A. Engel, M. A.

Thomas. 2005. Modeling the average annual

nutrient losses of two watersheds in Indiana using

GLEAMS-NAPRA. Transactions of the ASAEVol. 48(5): 1739_1749.

Mueller, D.K., P.A. Hamilton, D.R. Helsel, K.J. Hitt, and

B.C. Ruddy, 1995. Nutrients in ground and

surface water of the United States – An analysis

of data through 1992, U.S. Geological Survey

Water-Resources Investigations Report 95-4031,

74 p.

National Science and Technology Council (NSTC), 2004.

Science and Technology to Support Fresh Water

Availability in the United States, Report of the

Subcommittee on Water Availability and Quality,

Washington, D.C., 19 pp.Nelson, W.M., A.J. Gold, and P.M. Groffman, 1995.

Spatial and temporal variation in groundwater

nitrate removal in a riparian forest, Journal of

Environmental Quality, v. 24, p 691-699.

Ng, H.Y.F., Tan, C.s., Drury, C.F., Gaynor, J.D. 2002

Controlled drainage and subirrigation influences

tile nitrate loss and corn yields in a sandy loam

soil in Southwestern Ontario, Agriculture,

Ecosystems, and Environment 90:81-88.

Nguyen, M.L., Quinn, B.F., Sukias, J.P.S., 2002. Potential losses of

phosphorus and nitrogen in runoff and drainage frompastoral soils applied with superphospjhate and reactive

phosphate rock. In: Currie, L.D., Loganathan, P. (Eds.),

Dairy Farm Soil Management. Fertilizer and Lime Res.

Centre., Massey Univ., Palmerston North, New Zealand,

pp. 137-153.

Nichols, D.J., Daniel, T.C., Edwards, D.R., 1994. Nutrient runoff


from pasture after incorporation of poultry liter or

inorganic fertilizer. Soil Science Society of America

Journal 58, 1224-1228.

Nichols, J.D., F.A. Johnson, and B.K. Williams, 1995.

Managing North American waterfowl in the face

of uncertainty, Annual Review of Ecology andSystematics, v. 26, p. 177-199.

O’Connell, P.E. and E. Todini, 1996. Modelling of rainfall,

flow and mass transport in hydrological systems:

an overview, Journal of Hydrology, v. 175, p. 3-

16.

Oenema, O., van Liere, L., Schoumans, O., 2005. Effects of

lowering nitrogen and phosphorus surpluses in agriculture

on the quality of groundwater and surface water in the

Netherlands. Journal of Hydrology 304, 289-301.

Olson, B. M., J. J. Miller, S. J. Rodvang, L. J. Yanke.

2005. Soil and groundwater quality under a cattle

feedlot in southern Alberta Water Qual. Res. J.Can. 40: 131-144.

Peterson, H.G., 1998. Use of constructed wetlands to process

agricultural wastewater. Canadian Journal of Plant Science

78, 199-210.

Postel, S. 1996. “Forging a Sustainable Water Strategy,” in

State of the World 1996. Washington, D.C.:

Worldwatch Institute, p.40-59.

Puckett, L.J., 1994. Nonpoint and point sources of nitrogen

in major watersheds of the United States: USGS

Water Resources Investigations Report 94-4001.

Raman, D.R., A. C. Layton, L. B. Moody, J. P. Easter, G.S. Sayler, R. T. Burns, M. D. Mullen, 2001.

Degradation of estrogens in dairy waste solids:

effects of acidification and temperature,

Transactions of the ASAE, V. 44, p. 1181-1888.

Rees, H. W., T. L. Chow, R. J. Long, J. Lavoie, J. O.

Monteith. 2002. Hay mulching to reduce hay

mulching and soil loss under intensive potato

production in northwestern New Brunswick,

Canada. Can. J. Soil Sci. 82: 249-258.

Rivera , A., A. Crowe, A. Kohut, D. Rudolph, A. Baker, D.

Pupek, N. Shaheen, M. Lewis, K. Parks. 2003.

Canadian Framework for collaboration ongroundwater. Geological Survey of Canada,

M40-62/2003E-PDF.

Royer, T.V., Tank, J.L. and David, M.B. 2004. Transport

and fate of nitrate in headwater agricultural

streams in Illinois. J. Environ. Qual. 33:1296-

1304.

Schiffries, C.M. and A. Brewster, 2004. Water for a

Sustainable and Secure Future, National Council

for Science and the Environment, Washington,

D.C., 83 pp.

Schultz, R.C., Colletti, J.P., Isenhart, T.M., Marquez, C.O.,Simpkins, W.W., Ball, C.J., 2000. Riparian Forest Buffer

Practices. In: Garrett, H.E., Rietveld, W.J., Fisher, R.F.

(Eds.), North American Agroforestry: An Integrated

Science and Practice. American Society of Agronomy,

Inc., Madison, Wisconson, pp. 189-281.

Sharpley, A. N., Daniel, T., Sims, T., Lemunyon, J.,

Stevens, R., and Parry, R. (2003) Agricultural

Phosphorus and Eutrophication - Second Edition,

United States Department of Agriculture,

Agricultural Research Service, ARS-129,

September 2003.Sharpley, A.N., J.L. Weld, D.B. Beegle, P.J. Kleinman,

W.J. Gburek, P.A. Moore, and G. Mullins, 2003.

Development of phosphorous indices for nutrient

management planning strategies in the United

States, Journal of Soil and Water Conservation, v.

58, p. 137-151.

Sherman, T.J., S.R. Gagnon, and J.R. Makuch, 2004. Data

and Modeling for Environmental Credit Trading:

A Conservation Effects Assessment bibliography,

Special Reference Brief 2004-03, U.S.

Department of Agriculture, Washington, D.C., 53

pp.Shields, F.D., R.R. Copeland, P.C. Klingeman, M.W.

Doyle, and A. Simon, 2003. Design for stream

restoration, Journal of Hydraulic Engineering, v.

129, p. 575-584.

Smith, M.B., P.E. Blanchard, W.G. Johnson, and G.S.

Smith, 1999. Atrazine management and water

quality, University of Missouri-Columbia,

Extension Publication 167.

Sogbedji, M. and McIsaac, G.F. 2002a. Evaluation of the

ADAPT model for simulating water outflow from

agricultural watersheds with extensive tiledrainage. Transactions of the American Society of

Agricultural Engineers 45:649-659.

Sogbedji, M. and McIsaac, G.F. 2002b. Modeling

streamflow from artificially drained agricultural

watersheds in Illinois. Journal of American Water

Resources Association, v.38, p. 1753-1765.

Spalding, R.F. and M.E. Exner, 1993. Occurrence of

nitrate in groundwater: a review, Journal of

Environmental Quality, v. 22, p. 392-402.

SWAQ (Subcommittee on Water Availability and

Quality), 2004, Science and Technology to

Support Fresh Water Availability in the UnitedStates, National Science and Technology Council,

Committee on Environment and Natural

Resources, Washington, DC, November, 2004, 32

pages.

Tanji, K. K., G. Helfand, and D. M. Larson, 1994, BMP

Assessment Model for Agricultural NPS

Pollution, Hydrologic Science Paper, Davis,

California, University of California, Davis, p. 99.

Tyrrel, S.F. and J.N. Quinton, 2003. Overland flow

transport of pathogens from agricultural land

receiving fecal wastes, Journal of AppliedMicrobiology, v. 94, p. 87-93.

Uri, N.D., 2001. The environmental implications of soil

erosion in the United States, Environmental

Monitoring and Assessment, v. 66, p. 293-312.


U.S. Environmental Protection Agency, 1999.

Proceedings: 1999 Water and Watersheds

Program Review, 117 p.

U.S. Environmental Protection Agency, 2000. TMDL,

National Section 303(d) List Fact Sheet.

(http://oaspub.epa.gov/waters/national_rept.control)

U.S. EPA., 2002. National Water Quality Inventory: 2000 Report,

EPA-841-R-02-001, United States Environmental

Protection Agency, Washington, DC.

U.S. Geological Survey, 2004. Estimated Use of Water in

the United States in 2000, U.S. Geological Survey

Circular 1268.

Van Herk, F. H., T. A. McAllister, C. L. Cockwill, N.

Guselle, F. J. Larney, J. J. Miller, M. E. Olson.

2004. Inactivation of Giardia cysts and

Cryptosporidium oocysts in beef feedlot manure

by thermophilic windrow composting. CompostSci. and Util. 12: 235-241.

Weise, R.A., Flowerday, A.D., and Power, J.F., 1999.

Reducing nitrate in water resources with modern

farming systems, Management Systems

Evaluation Areas, IDEA 12, 18 pp.

Vellidis, G., R. Lowrance, P. Gay, and R. K. Hubbard,

2003, Nutrient transport in a restored riparian

wetland: Journal of Environmental Quality, v. 32,

p. 711-726.

WHO, 1997. Health and the Environment in sustainable

Development – Five Years After the Earth

Summit, World Health Organization, Geneva.

Wuest, S.B., D.K. McCool, B.C. Miller, and R.J. Veseth,1999. Development of more effective

conservation farming systems through

participatory on-farm research, American Journal

of Alternative Agriculture, v. 14, p. 98-102.

Yiridoe, E.K. and A. Weersink 1997. A review and

evaluation of agroecosystem health analysis: the

role of economics, Agricultural Systems, v. 55, p.

601-626.

Yoder, D.C., G.R. Foster, G.A. Weesies, K.G. Renard,

D.K. McCool, and J.B. Lown, 1998. Evaluation

of the RUSLE soil erosion model, American

Society of Agricultural Engineers, St. Joseph’s,MI.

Zilberman, D. and K. Schoengold. 2005. The use of

pricing and markets for water allocation. Can.

Water Res. J. 30: 47-54.

Zucker, L.A. and L. Brown, 1998. Agricultural drainage:

Water quality impacts and subsurface drainage

studies in the Midwest, Ohio State University

Extension Bulletin 871.

addressing agricultural water resources issues in north ... · on water measurement and canal...

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