FY 2006 Annual Report for National Program 201 - Water Resource Management 

Introduction 

Water is fundamental to life and is a basic requirement for virtually all of our agricultural, 

industrial, urban, and recreational activities, as well as the sustained health of the natural 

environment. As the world’s population tripled during the last century, demand for the 

finite amount of Earth’s fresh water resources increased by six-fold. The United Nations 

estimates that over 1 billion people live without access to clean water, and over 2.4 

billion people lack the basic sanitation needed for human health. The U.S. 

Environmental Protection Agency has estimated that it will cost in excess of $150 billion 

to provide clean and safe water to the Nation. Fresh water supply shortages—already 

evident in the drought-ridden western United States—annually cost the Nation in excess 

of $8 billion per year in addition to untold environmental impacts. When only freshwater 

withdrawals are considered, agriculture is clearly the largest user of water in the United 

States; thus agriculture has the greatest opportunity to conserve water supplies and 

improve water quality through scientific discovery. 

The goal of USDA/ARS Water Availability and Watershed Management National 

Program is to manage water resources effectively and safely while protecting the 

environment and human and animal health. This goal will be achieved by characterizing 

potential hazards, developing management practices, strategies and systems to alleviate 

problems, and providing practices, technologies and decision support tools for the benefit 

of customers, stakeholders, partners, and product users. Research in this National 

Program addresses six component problem areas: (1) effectiveness of conservation 

practices; (2) irrigation water management; (3) drainage water management systems; (4) 

integrated soil erosion and sedimentation technologies; (5) watershed management, water 

availability, and ecosystem restoration; and (6) water quality protection systems. 

The mission of this National Program is twofold: (1) to conduct fundamental and applied 

research on the processes that control water availability and quantity for the health and 

economic growth of U.S. citizens; and (2) to develop new and improved technologies for 

managing the Nation’s agricultural and water resources. Advances in knowledge and 

technologies provide producers, action agencies, local communities, and resource 

advisors with the practices, tools, models, and decision support systems they need to 

improve water conservation and water use efficiency in agriculture, enhance water 

quality, protect rural and urban communities from the ravages of drought and floods, 

improve agricultural and urban watersheds, and prevent the degradation of riparian areas, 

wetlands, and stream corridors. 

ARS, in cooperation with the Natural Resources Conservation Service (NRCS), the 

Cooperative Research Extension and Education Service, the Environmental Protection 

Agency, and other Federal and State agencies, has developed a watershed assessment 

project called the Conservation Effects Assessment Project (CEAP). The purpose of 

CEAP is to provide a methodology for documenting the national and regional 
environmental effects and benefits obtained from USDA conservation program 

expenditures. 

The National Agricultural Library (NAL), Beltsville, MD, has developed a series of 6 

CEAP-related bibliographic databases that are available to the public through the NAL 

web site: http://www.nal.usda.gov/wqic/. This dynamic relational database offers more 

than 5,200 citations of current research findings from around the globe to help scientists 

and the public understand the environmental effects and benefits of conservation 

practices implemented through various USDA conservation programs. 

National Program Staff continue to coordinate ARS water resource related activities with 

regional, national, and international partners. Outreach activities during FY2006 

included sponsorship of national and international conferences to address the availability 

and quality of recycled water for use in agricultural sectors in association with the 

WaterReuse Association and the Council on Agricultural Sustainable Technology 

(CAST). A milestone of CEAP activities during FY2006 was the workshop, “Managing 

Agricultural Landscapes for Environmental Quality,” organized by the Soil and Water 

Conservation Society in support of USDA’s Conservation Effects Assessment Project, 

held Oct. 11-13, 2006, in Kansas City, MO. The workshop featured 114 contributed 

papers and 72 poster presentations describing the results of CEAP-related research by 

ARS and affiliated scientists. The proceedings of this workshop are available through the 

Soil and Water Conservation Society web site: http://www.swcs.org/. 

The National Program Staff coordinates with other government agencies to leverage 

agency resources through its active participation in the following intergovernmental 

committees: (1) the Committee on Environment and Natural Resources (CENR) (the 

relevant National Science and Technology Council committee for water research) 

Subcommittee on Water Availability and Quality (SWAQ), a subcommittee within 

CENR devoted to water issues that serves as a forum for agency representatives to share 

information about their respective programs ; (2) the National Agricultural Research, 

Extension, Education and Economics (NAREEE) Advisory Board, which evaluates 

USDA Research and Development Programs and provides recommendations to the 

Secretary and REE Undersecretaries; (3) the Mississippi River/Gulf of Mexico 

Watershed Nutrient Task Force, charged by Congress with conducting a reassessment of 

(i) nutrient load reductions and the response of the hypoxic zone, (ii) water quality 

throughout the Mississippi River Basin, and (iii) economic and social effects, that is 

scheduled to be completed in November 2007; (4) the Scientific Assessment of 

Freshwater Harmful Algal Blooms; (5) the Federal Principals’ Meeting on Chesapeake 

Bay Protection and Restoration and various activities related to water quality in 

Chesapeake Bay; and (6) the Conservation Effects Assessment Project Steering 

Committee and a variety of other CEAP-related activities, to name just a few. 
Selected Accomplishments: 

1. Effectiveness of Conservation Practices 

Minimizing erosion and sediment loss. Agricultural practices can be a significant 

source of sediment in a watershed. Modern agriculture uses conservation practices to 

minimize erosion and sediment loss, while other land uses (e.g., urban and suburban 

development) can also represent significant sources of sediment. Until recently, there 

have been no readily available techniques for determining the primary sources of 

sediment in a watershed. ARS scientists at the National Sedimentation Laboratory in 

Oxford, MS, compared the physical and chemical properties of suspended sediments in 

the stream at the mouth of a watershed to soil characteristics of discrete areas within that 

watershed. The physical, chemical, and isotopic signatures of the suspended sediment 

collected at the six subwatersheds were used in a mathematical model to identify the 

primary contributing source within the watershed. Based on this analysis, subwatersheds 

with the lowest Aggregation Index (a measure of soil structure) contributed the largest 

amounts of sediment exported. In a complementary study, ARS scientists in Tucson, AZ, 

developed methodologies for using tracers to quantify sediment detachment, transport, 

and deposition in rangeland landscapes. As a result of these studies, it is now possible to 

estimate source, fate, and transport of carbon and sediment transport based on soil 

properties in agricultural watersheds. 

Summer land management practices impact runoff and water quality. Scientists 

from ARS’ Grazinglands Research Laboratory in El Reno, OK, used rainfall simulators 

to show that runoff, sediment, nitrate, and phosphorus (P) levels were higher from winter 

wheat followed by summer fallow (WWF) than for winter wheat followed by summer 

legumes. They found that the worst case scenario was grazed WWF pastures, where 71% 

of applied rainfall was lost as runoff, accompanied by the greatest losses of sediment, 

nitrate, bio-available and water soluble phosphorus. Understanding how alternative 

summer management practices interact with late summer storms will help producers 

reduce soil erosion, enhance the capture of water resources, and increase production in 

these water limited agricultural landscapes. 

A model for predicting non-point source pollution in agricultural watersheds. The 

AGricultural Non-Point Source Pollution Model (AGNPS) is a joint USDA-ARS and -

NRCS system of computer models developed to predict non-point source pollutant 

loadings within agricultural watersheds. It contains a continuous simulation, surface 

runoff model designed to assist with determining BMPs, the setting of TMDLs, and for 

risk & cost/benefit analyses. Within the USDA Conservation Effects Assessment Project 

(CEAP), the National Sedimentation Laboratory in Oxford, MS, is using CEAP to assess 

the effects and benefits on agriculture and in-stream conservation practices. Subsurface 

hydrologic components have been incorporated into the AGNPS system to describe tile 

drainage and lateral subsurface flow processes within individual fields draining to 

downstream channels. Earlier, aquaculture, stream erosion, stream channel restoration, 

and in-stream structures features along with RUSLE2, used by NRCS to evaluate the 
degree of erosion on agricultural fields, were incorporated into AGNPS. Summaries of 

AGNPS capabilities can be found at 

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

stories include working with the State of Mississippi and Louisiana to conduct TMDL 

assessments; working with the NRCS Special Emphasis CEAP Stemple Creek watershed 

in California to develop watershed management plans on how best to reduce sediment 

and nutrients that would otherwise travel directly into the Pacific Ocean; and working 

with the State of Arkansas to evaluate irrigation technologies and intense poultry farming 

practices that are presenting unique water quality problems. ARS scientists at Oxford 

are continuing to partner with the USACE, USEPA, NRCS, ARS, and Ohio state 

agencies to integrate watershed technologies into the USDA conservation programs and 

to develop potential water quality trading applications within the Ohio River Basin. The 

AGNPS system has been or continues to be used on over 500 watersheds throughout the 

United States 

Minimizing the effects of agriculture on Chesapeake Bay water quality. ARS 

scientists are actively engaged in research to minimize the effects of agricultural practices 

on nutrient export to Chesapeake Bay. Scientists at the Beltsville Agricultural Research 

Center (BARC) are examining the effectiveness of conservation practices on water 

quality at the watershed scale, as part of CEAP. BARC scientists are using the AGNPS 

watershed model to evaluate the effects of various management decisions/options on 

water, sediment, and chemical transport to Chesapeake Bay from the Choptank watershed 

on Maryland’s Eastern Shore. ARS scientists are working with the Maryland Department 

of Natural Resources to provide this tool to producers for use in evaluating management 

decisions regarding poultry litter applications and various cover crop management 

practices on water quality in this portion of the Chesapeake Bay watershed. 

Improving water quality within the Chesapeake Bay. ARS scientists at University 

Park, PA, examined within-field spatial variability in crop nitrogen (N) requirements in 

two fields—one in Pennsylvania’s Ridge and Valley Region (PRVR), and the second on 

Maryland’s Eastern Shore (MES). The MES field did not show significant differences in 

corn response to increasing N fertilizer applications among selected field locations, but N 

requirements varied by more than 100 lbs. per acre between toe and head slope positions 

in the PRVR field. Thus in some physiographic regions within the Chesapeake Bay 

watershed, there can be sufficient spatial variability in N requirements to warrant varying 

fertilizer application rates. Based on these studies, adopting precision agricultural 

techniques in these physiographic regions will help reduce N transport to the Chesapeake 

Bay, thus improving Bay water quality. 

2. Irrigation Water Management 

Adopting crop water use estimates nation-wide. ARS scientists at the Water 

Management Research Unit in Parlier, CA, have developed methods to predict crop water 

use and irrigation scheduling that can be generalized to a wide range of horticultural 

crops. They used sophisticated weighing lysimeter and multi-spectral photography to 

show that the water use of lettuce, peppers, and garlic were all closely related to plant 
canopy cover and the percent of light that the plants intercepted. In a complementary 

study, the Soil and Water Management Research Unit in Bushland, TX, in collaboration 

with university scientists and private consultants, released new sets of standardized 

equations for crop water use. These improvements are being used by the Texas 

Cooperative Extension (TCE) AgriPartner program, the Panhandle Water District, the 

North Plains ET Network, numerous Federal and state Agencies, producers, professional 

societies, and the international community via the United Nations; and a web site 

(http://txhighplainset.tamu.edu/) provides current information to producers and the 

general public worldwide. These results have significant impact on irrigation 

management to increase agricultural water use efficiency. According to NRCS data, 

USDA conservation programs provided cost sharing incentives for total irrigation water 

management, which increased irrigation scheduling in combination with some irrigation 

practice improvements, on nearly 4 million acres in 2005 and 2006. The associated water 

and pumping cost savings from primarily improved irrigation scheduling should exceed 

many tens of millions of dollars per year. 

Improving irrigation efficiency based on remote sensing technologies. Increasing 

irrigation efficiency in arid environments in the western US requires the identification of 

sensitive spectral indices associated with salinity and water deficit. ARS scientists at the 

George E. Brown, Jr., Salinity Laboratory at Riverside, CA, conducted lysimeter studies 

using two forage crops (‘Salado’ alfalfa and ‘Jose’ tall wheatgrass) to show that 

remotely-sensed crop response offers growers, irrigation managers, and extension 

specialists a reliable tool for detecting plant stress prior to the onset of visual signs of 

crop injury and for preventing irreversible stress-induced changes that reduce crop yields. 

In a complementary study, ARS researchers at the Arid Land Agricultural Research 

Center in Maricopa, AZ, developed wheat crop coefficients (Kc) via remote sensing for 

accurate determinations of crop water use during the growing season. According to the 

NRCS Performance Result System, remote sensing and/or plant stress detection practices 

similar to these are currently used on about 2000 acres, with the goal of optimizing 

irrigation scheduling and reducing irrigation water application amounts by at least 10 

percent. Use of these practices is projected to exceed one million acres by 2010. 

 

Improving surface irrigation practices based on new decision methods. Engineers at 

the U.S. Arid-Land Agricultural Research Center, Maricopa, AZ, in cooperation with 

researchers from Delft University of Technology, developed and applied Model 

Predictive Control (MPC) to canal operations at the Maricopa Stanfield Irrigation and 

Drainage District in central Arizona. MPC regulates the delivery of water through 

irrigation canals, so that only the precise amount of irrigation water needed is delivered to 

the surfaces of irrigated fields in a timely manner. Another decision tool developed by 

scientists at Maricopa is the comprehensive surface irrigation software product, 

winSRFR, which consolidates the surface irrigation programs SRFR, BORDER, and 

BASIN, and routines for analyzing surface irrigation evaluation data, into a single 

Windows-based, user-friendly application and is available free to the public at 

http://www.ars.usda.gov/services/software/download.htm?softwareid=146. The 

combined usage of automated irrigation canals along with on-farm improvements based 

on the latest irrigation software product will improve surface irrigation deliver and 
application efficiencies by as much as 5 percent beyond the current 55 percent throughout 

the western United States. NRCS alone provided irrigation design and other on-farm 

improvements for surface irrigation practices on some 130,000 acres in FY 2006 using 

ARS based technology. 

Economic evaluation of irrigated agriculture in the Ogallala Aquifer region. ARS 

scientists at Bushland, TX, developed Groundwater Availability Models (GAMs), for 

each county of the southern Ogallala Aquifer region, with the overall goal of maximizing 

the net income from crop production. Results from the 60-year analysis involving 9 major 

crop species, indicated a significant transition from irrigated agriculture to dryland 

farming. Using the Panhandle sub-region as an example, total irrigated crop acres in the 

study area decreased by approximately 83% from 1.79 million acres to 0.30 million acres 

while total dryland crop acres increased by about 125% from 1.20 million acres to 2.69 

million acres. Total groundwater use in the study area declined by 71%, from 2.16 

million acre-feet to 0.63 million acre-feet, and the average saturated thickness of the 

Ogallala Aquifer in the 23 counties showed a 21% decline over the planning period. 

Similar results were found for the other sub-regions when no water-use policy changes 

were anticipated. In 2006, ARS scientists incorporated crop and animal data, well 

locations, bed rock geology from agricultural statistics reports, long-term climatic 

datasets, and more recent information from other state and Federal agencies into a 

Geographic Information System (GIS), and a preliminary analysis was conducted to 

estimate potential reduction in agricultural water use with alternative crops such as cotton 

and sorghum. Future plans are to use this GIS database in combination with a GAM, to 

evaluate five alternative economic scenarios or water-use policy changes. At the same 

time, ARS scientists in Lubbock, TX, showed that their BIOTIC system (which 

continuously measures canopy temperatures) is a visible approach for producing 

profitable cotton yields under a high level of water use efficiency where the crop remains 

in a water deficit throughout the growing season. ARS is providing leadership by 

identifying: 1) opportunities for reducing irrigated acreages; 2) alternative economic 

scenarios for the continuation of highly-efficient irrigation technologies; and 3) deficit 

irrigation practices that can successfully be implemented throughout most of the southern 

Ogallala Aquifer region. A new web site (www.ogallala.tamu.edu) has been developed 

to distribute fact sheets, published materials, and specific information about this project. 

3. Drainage Water Management Systems 

Managing water quality and nutrients using surface drainage systems. ARS 

scientists at University Park, PA, are working closely with faculty at the University of 

Maryland Eastern Shore (UMES) to expand basic science and cutting-edge research 

capabilities of UMES, and train UMES students. Their studies have shown that surface 

drainage water management practices can reduce dissolved reactive phosphorus (DRP) 

loadings to the Chesapeake Bay by 30 to 50 percent. In a complementary study, ARS 

scientists at Oxford, MS, conducted a two-year study of ditches draining no-till cotton 

fields, monitoring nutrient flux along both spatial and temporal gradients and found that 

managed drainage ditches retained 22-64% of nitrate and ammonium, and 31-60% of 

DRP and particulate phosphorus (PP), carried in stormflow nutrient loads, but that 
nutrient retention was governed by hydrologic variations. Similarly, ARS scientists at the 

National Soil Erosion Research Laboratory in West Lafayette, IN, examined whether the 

sediments in tile-fed surface drainage ditches served as a sink for P by adsorbing P from 

the water column, or as a source of P to the water column. As the area drained by the 

ditch increased, the amount of organic matter, clay and silt decreased in the ditch 

sediments. They found that land use also has an impact on P dynamics--the greatest 

increase in P in the water column, and decrease in P buffering capacity, were noted 

between two sites upstream and downstream of an animal feeding operation. These three 

studies showed that surface drainage water management systems can improve 

downstream water quality with very little cost (estimated at > $5 per acre) to the farmer. 

The Chesapeake Bay Foundation, the Agricultural Drainage Management Systems 

(ADMS)Task Force, the Hypoxia Task Force for the Northern Gulf of Mexico, and 

NRCS have all expanded their efforts to apply surface drainage technologies based on 

these and other ARS and university research. According to NRCS, the use of surface 

drainage ditches improved 12,000 acres of agricultural lands in 2005 and 2006, 

principally in the Midwest. 

Surface and subsurface drainage management systems provide ecological benefits. 

In 2005, ARS’ Soil Drainage Research Unit in Columbus, OH, initiated research to 

determine the influence of grassed buffers and farming practices on the physical habitat 

and aquatic communities within agricultural drainage ditches. Initial results indicate that 

drainage ditches are important habitats for fish within agricultural watersheds, and 

suggest that incorporation of environmental considerations into the management of 

ditches will benefit the fish within these systems. Additionally, these findings suggest 

that those conservation practices that alter the hydrological characteristics of drainage 

ditches will have the most impact on fish and other aquatic animals living within ditches. 

Improvements in surface and subsurface drainage management systems have been 

showcased at a number of field days, conferences, and professional meetings attended by 

farmers, technical agency employees, administrators, elected officials, and other 

scientists; and the web site (http://extension.osu.edu/~usdasdru/ADMS/ADMSindex.htm) 

for the Agricultural Drainage Management Systems(ADMS)Task Force is maintained by 

ARS in Columbus, OH. Surface and subsurface drainage ditches, as reported in the 

NRCS Performance Result System, were improved on nearly 40,000 acres in 2005 and 

2006. 

Quantifying the economic benefits of improved drainage water management 

systems. ARS scientists from the Midwest (Ames, IA), Pacific West (Tucson, AZ), and 

Northern Plains (Fort Collins, CO) regions have been collaborating on quantifying the 

effects of tillage, crop rotation, N management (application method, timing, and rate), 

and winter cover crops along with controlled subsurface drainage, as part of a drainage 

water management systems, to determine their combined and individual effects on N 

loading, corn and soybean yields, and economic returns. Various management 

systems/options are being simulated using a suite of models developed by ARS 

(RZWQM, RZWQM-DSSAT, and APSIM); with model results then being compared to 

observed data from ARS field studies and the scientific literature. During testing of 

RZWQM-SWAW, ARS scientists found that a plant’s response to water stress varied 
from crop to crop, requiring slightly different water stress indices. This knowledge is 

now included in crop growth models. The collaborative effort received the Federal 

Laboratory Technology Transfer Award for FY 2006. 

4. Integrated Soil Erosion and Sedimentation Technologies 

Rapid assessment of sediment accumulation in water reservoirs. As dams and 

reservoirs reach the end of their life expectancy, their state and performance must be 

assessed, and decisions made regarding their future. The traditional approach for 

determining accumulated sediment volumes and sediment characteristics is sediment 

coring, which is both time-consuming and expensive. ARS scientists at Oxford, MS, 

developed a prototype acoustic sediment probe to complement current methods of 

assessing sediment accumulation in reservoirs. This probe was used in three small 

reservoir sites in conjunction with the extraction of physical core samples. Preliminary 

analysis indicates a good correlation between the bulk density profile of the core samples 

and the acoustic speed profile measured at the same location, which could lead to the 

development of acoustic measurement and monitoring technologies for characterizing the 

relationships between acoustic attributes (e.g., acoustic velocity) and sediment physical 

properties (e.g., bulk density). The acoustic method is preferable because it is both fast 

and non-invasive, thus reducing the time and cost of measurements. 

Using reservoir sediments as long-term pollution indicators. Concentrations of 

chemical contaminants in reservoir sediments provide a record of pollution, but because 

most chemicals are adsorbed to and transported with the sediment clay fractions, 

comparisons of pre- and post-impoundment sediment chemical composition cannot be 

made directly without normalizing these two sample sources for clay content. Otherwise, 

the higher clay concentrations associated with the post-impoundment sediments would 

falsely suggest greater chemical transport and reservoir contamination in the years since 

construction. ARS scientists from Oxford, MS, analyzed sediment cores from Grenada 

Lake for aluminum, arsenic, chromium, copper, mercury, lead, and zinc. When 

concentrations of these elements were normalized for clay contents, post-impoundment 

sediments had lower concentrations than pre-impoundment sediments, suggesting that 

agricultural activities in the watershed have not impacted sediment chemistry in the 

reservoir. These findings are useful to environmental scientists charged with monitoring 

and assessing long-term water and sediment pollution trends in water reservoirs. 

Managing soil erosion near structures in streams and rivers. Managing local erosion 

in streams and rivers is important to protect key infrastructure (e.g., road bridge supports, 

pipelines, and other utility crossings) that can be seriously damaged or destroyed during 

flooding events. ARS scientists at the National Sedimentation Laboratory in Oxford, 

MS, with the Dept. of Civil Engineering at Michigan Technological University, used 

laboratory flume channels to develop techniques to limit erosion near structures in 

streams and rivers. They developed and published standard protocols for the use of these 

techniques. These new tools provide cost-effective options to aid watershed managers 

and engineers reduce the impact of erosion on the Nation’s transportation infrastructure. 
A new rangeland erosion model released in 2006. Four computer-implemented erosion 

prediction models were combined and improved: the Water Erosion Prediction Project 

(WEPP), the Revised Universal Soil Loss Equation (RUSLE), the Kinematic Runoff and 

Erosion Model (KINEROS), and the internet-based Hillslope Erosion Model (HEM). 

Development and application of these models were major accomplishments achieved by 

ARS scientists at numerous locations since 1995, including West Lafayette, IN, Oxford, 

MS, Boise, ID, and Tucson, AZ. ARS scientists at the Southwest Watershed Research 

Center in Tucson, AZ, assembled the world's largest rangeland rainfall simulator 

database, including over 2000 rainfall simulator events from experimental sites 

throughout the West. These data were collected, analyzed, and then modeled using the 

new HEM. The use of this new model, and the rangeland databases upon which they are 

based, is having a major impact on the economic survival of rural America and 

agricultural sustainability. This new rangeland erosion prediction tool is available at 

http://eisnr.tucson.ars.ag.gov . The new HEM will be used to administer national policy 

through the implementation of the Farm Bill, Emergency Watershed Protection programs, 

management of public lands, and provide technical assistance to cooperators and 

stakeholders on western rangelands. 

5. Watershed Management, Water Availability, and Ecosystem Restoration 

Conserving phosphorus under no-till and conventional-till systems. The advent of 

phosphorus-based management plans has resulted in conflicting recommendations 

regarding surface application of manures in no-till systems, which can cause stratification 

of P in soil profiles, exacerbating dissolved P losses in runoff waters. ARS scientists at 

University Park, PA compared surface application of dairy manure with incorporation of 

dairy manure by plowing. While plowing manure into the soil significantly lowered 

losses of dissolved P in runoff, an increase in erosion following plowing caused total P 

losses to be roughly equivalent to those observed under surface application of manure. 

However, leaching losses of phosphorus from surface applied manure were 1.3 times 

greater than those of incorporated manure, likely due to preferential transport along intact 

cracks that are disrupted by plowing. These results indicate that incorporation of manure 

into soil by plowing has mixed benefits to the conservation of P compared to no-till 

systems, particularly under conditions of high erosion. No-till is still the preferred 

strategy, with the caveat that some additional P leaching to ground waters may eventually 

occur. Over the years, ARS scientists have transferred numerous research findings to 

NRCS, leading to the delivery of nutrient management plans on over 8.7 million acres of 

farmlands in 2005 and 2006. 

Estimating watershed hydrology and hydraulic properties using remote sensing 

techniques. Fluctuations in soil moisture and flooding, especially in wetlands, affect 

biogeochemical processes governing vegetation conditions and the fate of agrochemicals. 

ARS scientists in Beltsville, MD used synthetic aperture radar backscatter images 

collected by the ENVISAT satellite over the Choptank Watershed, MD, to map the 

surface hydrology of forested areas within the watershed. Results demonstrate the utility 

of satellite radar for mapping surface hydrology in complex landscapes. Resulting maps 

are useful in water quality management for providing a better understanding of the 
impact of select agrochemicals on Chesapeake Bay, contributing to Federal interagency 

efforts to restore the health of the Bay ecosystem. 

Large-scale monitoring of drought and crop water stress. Data from the 

Geostationary Operational Environmental Satellites (GOES) operated by NOAA to 

support weather forecasting, were used in a model by ARS scientists in Beltsville, MD to 

map evapotranspiration and moisture stress across the continental United States for 2002-

2004. The resulting stress maps correlated well with maps of antecedent precipitation 

and standard Palmer drought indices. However, the GOES-based stress maps have a 

higher spatial resolution (5-10 km) and do not depend on precipitation data, making this 

technology particularly promising for developing regions/countries that lack intensive 

precipitation measurement networks. The algorithm and data ingestion infrastructure has 

been automated, paving the way for daily operational moisture stress assessments across 

the U.S. that could be incorporated into the national drought monitoring program. 

Stream restoration in agricultural landscapes. Ecosystems in agricultural watershed 

streams throughout the US have been degraded by severe erosion, but the links between 

ecological damage and erosion are often unclear, complicating restoration planning. 

ARS scientists at Oxford, MS, studied one form of erosion-related stream damage, 

examining streambed carbon concentrations and fish communities in four streams in 

northern MS with varying degrees of channel erosion. In general, lightly degraded 

streams had higher carbon concentrations and more natural, diverse fish communities, 

suggesting that rehabilitation of stream ecosystems requires restoring riparian vegetation 

and in-channel features that retain carbon-rich debris and sediments. These findings will 

be directly useful to planning and designing stream channel restoration and management. 

A powerful watershed assessment tool developed and released. The PC-based 

Automated Geospatial Watershed Assessment (AGWA) tool provides rapid qualitative 

estimates of runoff and erosion relative to land use change. AGWA is multi-purpose 

environmental analysis system that integrates a geographical information system (GIS), 

national watershed data, and state-of-the-art environmental assessment and modeling 

tools into one convenient package. Full documentation and tutorials was released in 

April, 2006, by the Southwest Watershed Research Center at Tucson, AZ, and can be 

downloaded at http://www.tucson.ars.ag.gov/agwa. AGWA currently has over 1200 

users from local, state and federal agencies; universities; environmental groups; and, 

consulting firms, and over 75 countries are using this decision support tool. The decision 

aid is available through the U.S. EPA Better Assessment Science Integrating Point and 

Nonpoint Sources (BASINS) water quality website: 

http://www.epa.gov/waterscience/BASINS/. 

6. Water Quality Protection Systems 

Improving Mississippi River water quality. ARS scientists in St. Paul, MN, developed 

a new approach to reducing nitrate losses from subsurface tile-drained fields, involving 

the planting of cool-season perennial forages, such as alfalfa or grass, directly over 

subsurface tile drains. Plants remove nitrate from the water table before it enters the tiles, 
improving the quality of water that eventually enters the Mississippi River. The strips 

can be harvested for forage or left as wildlife feed and habitat. 

Matrix fertilizer reduces leaching losses. Leaching and transport of plant nutrients 

from agricultural soils to surface waters are linked to eutrophication of fresh water bodies 

and estuaries downstream. Reducing leaching losses has the potential to increase the 

protection of off-site water bodies from nitrogen and phosphorus eutrophication and 

increase fertilizer plant use-efficiencies. ARS scientists from Kimberly, ID, evaluated the 

effectiveness of several combinations of an aluminum and iron sulfate-starch-chitosanlignin matrix as a fertilizer additive to reduce nutrient losses from agricultural fields. 

When the designed chemical matrix was added to a slow release N+P fertilizer, 

ammonium, and soluble and total phosphorus leaching losses were reduced 75% to 82%. 

Benchmark developed for documenting improvement in water quality. ARS 

scientists in Beltsville, MD, compared the use of best management practices with the 

frequency and amount of herbicides and pesticides measured in receiving streams in the 

Choptank watershed. Samples were obtained from 14 subwatersheds at 4 equally-spaced 

time intervals over a year; concentrations of parent compounds and their major 

degradates were compared across each subwatershed, and plotted versus the percent of 

agricultural usage within each watershed. Concentrations of atrazine and its major 

degradate, desethyl atrazine (DEA), were most strongly correlated with percent 

agriculture (varying from 0.37 to 0.54), with DEA being consistently the most strongly 

correlated. These data provide baseline values for discerning differences between tillage 

and cover crop rotations and are essential information for documenting the environmental 

impacts of conservation practices. 

Wetlands improve water quality. Wetland Reservoir Subirrigation Systems (WRSIS) 

use wetlands to partially remove nutrients and sediment from surface runoff and 

subsurface drainage. In order to improve quantification of this benefit, ARS scientists in 

Columbus, OH, have been monitoring all waters entering and leaving the constructed 

wetland at the Defiance County WRSIS site since 2003. Based on data from 2003 

through 2005, average nutrient (nitrate-N and total P) and sediment concentrations in 

water discharged from the wetland are significantly less than concentrations in runoff and 

subsurface drainage routed into the wetland. Average nitrate-N concentration leaving the 

wetland is only 18% of that for the subsurface drainage routed into wetland. Based on its 

research findings, ARS assisted NRCS in creating over 12.1 million acres of new 

wetlands in 2005 and 2006. 

Wetlands reduce impacts of pesticides. ARS scientists at Oxford, MS, applied a 

mixture of two synthetic pyrethroid insecticides, cyfluthrin and lambda-cyhalothrin, to a 

constructed wetland designed to mitigate runoff from an agricultural field. Populations 

of an aquatic invertebrate, Hyallela azteca, were exposed to samples of water, sediment, 

and leaf litter collected from the wetland 0 (pre-treatment), 1, 7, 13, 27, 42, and 61 days 

after pesticide mixture application. Examination of water, detritus, and sediment 

contamination showed movement of pyrethroids through the wetland cells, and toxicity 

assessments revealed that H. azteca toxicity was greater for water and leaf litter than for 
sediment. This research introduces a novel technique for assessing toxicity in the often 

overlooked environmental component (plants) of constructed wetlands. 

Vegetative buffers reduce nutrient losses associated with sediment transport. ARS 

scientists in Ames, IA, evaluated changes in the P content of plant roots and shoots 

growing in multi-species vs. single species riparian buffers, as an index of P capture 

potential. Switchgrass, a mixture of alfalfa and smooth brome, or fast growing superior 

cottonwood were planted in a riparian buffer. Cottonwood accumulated the greatest 

amount of P compared to the smooth brome control. Estimates of potential P export via 

biomass harvest from a mixed buffer over a four year interval a 63% increase in export 

capacity due largely to the inclusion of cottonwood. Addition of a fast growing woody 

species combined with periodic biomass harvests would help reduce P movement to 

surface waters. NRCS planted over 172,000 acres of forested riparian buffers in 2005 

and 2006, as compared to less than 160 acres of herbaceous buffers based in part on the 

research findings developed by the ARS. 

A new approach to improve groundwater quality in agricultural landscapes. ARS 

scientists in Beltsville, MD developed an innovative chemical transport model that 

quantifies the complete spectrum of soil pores without combining the contributions of 

various pore diameters. This approach was used to improve our ability to model and 

predict the impact of agricultural practices on groundwater quality. Scientists utilized 

this information to develop a software package to estimate soil water retention and 

hydraulic conductivity, and how these properties will change under various agricultural 

management scenarios. This software has been incorporated into a hydrologic model 

(Soil - Plant - Atmosphere - Water Field & Pond Hydrology - SPAW) which has been 

adopted by NRCS and is used across the Nation to help improve water management. 

This model is available to the public through the ARS Hydrology and Remote Sensing 

web site: http://hydrolab.arsusda.gov/SPAW/Index.htm.