FY 2008 ANNUAL REPORT

NATIONAL PROGRAM – 211

WATER AVAILABILITY AND WATERSHED MANAGEMENT

Water is fundamental to life and a basic requirement for virtually all of our agricultural, industrial, urban, and recreational activities, as well as for the sustained health of our natural ecosystems. As Earth’s human population tripled during the last century, demand for Earth’s finite supply of

available fresh water increased six­fold. The United Nations estimates that more than a billion

people live without access to clean water, and more than 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. Shortages 

of fresh water—already evident in the drought­ridden western United States—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 the USDA/ARS Water Availability and Watershed Management National Program is 

to effectively and safely manage water resources, 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) 

the 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 research on the processes that

control water availability and quantity for the health and economic growth of U.S. citizens; and

apply the new knowledge (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, the Cooperative State

Research, Extension, and Education Service, the Environmental Protection Agency, US 

Geological Survey and other Federal and State agencies, has developed a watershed research

program 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, and develop management

options to achieve maximum benefit from those expenditures. CEAP cropland assessments have

been expanded to the assessment of grazinglands and wetlands. ARS accomplishments related

to the CEAP assessment for croplands were published in a special issue of the Journal of Soil

and Water Conservation in 2008. Also published in 2008 with the help of the National Agricultural

Library, was a CEAP bibliography, “Effects of Agricultural Conservation Practices on Fish and

Wildlife” 

Interdisciplinary research across natural and social sciences to address challenges in water 

resource management requires comprehensive and long­term data. As part of CEAP, a

database called STEWARDS (Sustaining the Earth’s Watersheds, Agricultural Research Data

System) was developed to compile, document, and provide access to data from ARS research

watersheds. These data represent one of the largest research watershed data collections in the
world, with many of the watersheds offering decades of data required to address issues of climate

variability and global change. STEWARDS represents an advance for hydrologic and

environmental research by providing access to a multitude of data needed to support complex 

analyses. Anticipated impacts better data sets against which to test, validate and perfect models 

which can be utilized in water and land planning and environmental resource protection. These

data sets wil also provide a baseline against which new practices and implementation scenerios 

can be tested and measured by individual scientists, watershed teams, and the ARS water 

resources program.

The Clean Water Act of 1972 is the cornerstone of surface water quality in the United States;

however, water quality and distribution regulation is a complex myriad consisting of a multitude of

federal, state and local agencies. Significant coordination with planning, regulatory, environmental and action groups is required to address the needs of the agricultural and public 

sectors. ARS coordinates with other government agencies to leverage agency resources through

its active participation in a variety of intergovernmental committees including: (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, a draft of which is currently being circulated for public comment

(4) the Advisory Committee on Water Information (ACWI) Subcommittee on Sedimentation; (5) 

the USDA Drought Team and the USDA Working Group on Water Resources;(6) the

Conservation Effects Assessment Project Steering; The Subcommittee on Sedimentation, part of

the US Department of Interior, Advisory Committee on Water Information; the Ecosystems 

Working Group of the US Climate Change Science Program, and several others.

Selected Accomplishments

Effectiveness of Conservation Practices

Agricultural conservation practices ensure the sustainability and preservation of our nation’s 

natural resource base, which includes water, soil, and air. ARS has conducted research to

develop and improve these conservation practices and to provide environmental benefits in the

form of soil and water quality. Crop rotations, contour farming, conservation tillage, cover crops, stripcropping, conservation buffers, residue management, site specific nutrient and water 

application technologies, and salinity and drainage control practices have played a broad role in

increasing crop productivity, maintaining soil organic matter and fertility, and controlling water and

wind erosion processes. Implementation of some practices is associated with costs and tradeoffs 

between maximum productivity and preservation of natural resources. Thus, the implementations 

of some practices are encouraged through subsidies, which raise the question concerning the

value of the practices. Research conducted under this problem component focus on

development of improved practices and methods to quantify their effectiveness and value.

Cover crops can effectively reduce residual nitrogen loads. The primary role of ARS’s in the

interagency CEAP is to develop methods that can be used to assess and quantify the

environmental benefits of best conservation management practices at the watershed scale. The

Annualized AGricultural Non­Point Source (AnnAGNPS) model was tested as a tool to predict the

effectiveness of cover crops and drainage control structures in protecting water quality at the

Choptank River Watershed in Maryland. Preliminary model simulations for fifteen sub­basins 

within the non­tidal zone of the watershed revealed significant nitrogen load reductions due to
increases in cover crop acreage. Simulations with increased cover crop implementations from 40

to 70 percent showed nearly 58% N reduction. Such large amount of N load reductions 

suggested by the model must be validated with data collected in the watershed. The ultimate goal

is to develop enough confidence in AnnAGNPS and other models to support decisions faced by 

land managers and policy makers in selecting conservation practices and incentives to reduce

nutrient loads into the Choptank River and ultimately the Chesapeake Bay watershed.

Combining erosion control structures with reduced crop acreages eliminates most sediment flows 

to streams. Scientists in Oxford, MS evaluated in­stream grade stabilization structures on the

2,132 ha Goodwin Creek Experimental Watershed in north Mississippi. Measured rainfall, runoff, and sediment concentration data were applied to model simulations to demonstrate that the

combined effect of grade control structures and conversion of croplands into the Conservation

Reserve Program (CRP) (reducing cultivated land from 26 to 8%) was to reduce sediment yields 

by 78% near the outlet of the watershed. The evaluation was a successful real­world test of

watershed simulation models that are intended to help watershed managers choose

combinations of practices to increase environmental benefits.

Radar aids mapping of hard­to­find forested wetlands. Wetlands have the potential to remove

agrochemicals before they enter streams and degrade the biological health of estuaries. However, the majority of wetlands in the Chesapeake Bay Watershed are forested, and this type

of wetland is difficult to map and monitor using existing methodologies. ARS scientists developed

a new methodology to map forested wetland hydrology at a watershed scale using satellite­borne

radar data. Forested wetland hydrology maps produced using radar data were well correlated

with in­situ measurements of soil moisture and inundation. Next­generation wetland maps 

produced by radar will provide a water quality management tool that can be used to quantify the

proportionate contributions of various types of land uses to nutrient, and sediment loads in the

environment. These types of assessments are critical in the calibration of models that can be

used by land managers and regulators in their efforts to improve the health of the Chesapeake

Bay.

RZWQM Model confirms effectiveness of cover crops to reduce nitrate leaching. Additional field­  scale model evaluation is needed to quantify the effects of cover cropping, water table and

nitrogen management, and other management practices under tile drainage conditions to further 

support regionalized watershed model development for Midwest conditions. ARS scientists 

measured nitrate reduction in tile drainage with a rye winter cover crop in a corn­soybean rotation

when different levels of nitrogen fertilizer were applied in the corn year. A calibrated model

developed by combining the Root Zone Water Quality Model (RZWQM) and the Decision

Support System for Agrotechnology Transfer (DSSAT), a model developed for 

analysis of precision agriculture datasets, was modified to simulate a rye winter cover in a

corn­soybean rotation. Simulation results were verified against field measurements. When

simulations were run at various nitrogen­fertilizer application rates, using a long­term climate

record, results showed that percentage reduction of nitrate in tile drainage due to the cover crop

remained relatively constant over a wide range of applied nitrogen rates. This indicates that rye

winter cover crops will reduce nitrate in tile drainage water even at relatively low nitrogen

application rates.

ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) 

Model adapted for grasses. Simulation of growth and yield of grasses for conservation

assessment requires an accurate, realistic model that describes various grass types as well as 

competition among species in complex grass mixtures. ARS scientists in Temple, TX, parameterized the ALMANAC model for the major improved grass species and several common

native grasses, as well as for switchgrass cultivars (a promising biofuels crop) in Texas and in the

Upper Midwest. Parameters derived for these important grass species, when incorporated into

the ALMANAC model, provided simulations of grass growth and productivity in a wide range of

soils and climatic conditions. Model results were validated with NRCS data for ecological sites in

diverse regions and using measured data at a wide range of latitudes, from Texas to North
Dakota and Wisconsin. The model will be useful for assessing the impacts of biofuels production

on the management of natural resources in grasslands 

Successful conservation planning more likely with improvements made in method that enables 

model combinations  Improved plant growth modeling is needed to better assess the impacts of

implementing conservation practices at field to watershed scales. PhenologyMMS Version 1.2.2

was released and can be used as a stand­alone tool or incorporated into existing crop simulation

models and decision support tools to simulate changes in multi­crop phenology due to varying

levels of soil water availability. Version 1.2.2 provides the complete developmental sequences of

the shoot apex correlated with different developmental events for winter and spring wheat, winter 

and spring barley, maize, proso millet, hay millet, and sorghum. The Unified Plant Growth Model

(UPGM) has been developed and tested for corn and wheat across a range of environments and

successfully merges different versions of the EPIC­based plant growth model that exist in many 

agricultural system simulation models (e.g., GPFARM, WEPP, WEPS, SWAT, and ALMANAC).

Improvements in simulating plant growth have been made using this stand­alone foundation, giving it a higher degree of utility (more crops) and portability (can be incorporated as a modular 

component in other models).

Successful conservation planning more likely with improvements made in method that enables 

model combinations. A modular simulation framework is greatly needed to facilitate the

development of the regionalized watershed models for CEAP (Conservation Evaluation

Assessment Project). ARS scientists at Ft. Collins, CO enhanced the Object Modeling System 

(OMS) development framework to allow flexible simulation management, self­contained model

run­time execution, and improved data file handling for input parameter sets and simulation

output. The OMS was also extended to transfer and retrieve science modules to and from a

USDA CoLab­based component library. A prototype OMS component for visualization and

manipulation of geospatial data was developed using NASA World Wind geospatial technology. NRCS has agreed to use the OMS to streamline development of customized field to watershed

agricultural system models that address regional soil and water conservation and water quality 

needs. The ability to easily combine or substitute models under OMS will provide a foundation for 

improved conservation planning through future addition of customized science

Extensive data set for semi­arid rangelands made available . Short and long­term predictions of

climate change effects are dependent upon models, which are dependent for validation ondata

sets. ARS scientists in Tucson, AZ completed a multi­year project with the goal to improve data

access to promote analyses and interpretations of historic and current data on the Walnut Gulch

Experimental Watershed. Although current data is being collected in easily –retrievable form, the

historic data set required extensive transcription and compilation. The collection of geo­spatial

referenced data describing rain, run­off, sedimentation, meterology, soil hydrology, and

vegetation changes is the most extensive data set in the world for a semi­arid area in a

watershed greater than 10 Km2. A special section of the Journal Water Resources Research and

the associated Web site (http://www.tucson.ars.ag.gov/dap/) describe 50 years of data collection

and the most recent research results. These data will be invaluable for developing and testing

rangeland erosion and sediment yield models and assessment tools.

Problem Area 2—Irrigation Water Management

Development of a process­based model for contaminant transport. Process­based computer 

models are important tools for studying and predicting the fate and transport of agricultural

contaminants in soils and groundwater, and for designing optimal soil, water or crop management

practices. Scientists at Riverside CA released a new version that of the HYDRUS­1D software

package that includes new or improved capabilities for simulating: vapor flow; coupled water,

vapor, and energy transport; dual­permeability type water flow and solute transport;

evapotranspiration, transpiration, and precipitation; and biogeochemical reactions and transport.
The new features make the software more suitable for application to a broad range of agricultural

and industrial subsurface pollution problems.

New guide to sensing soil water content will improve water management. Accurate knowledge of

soil water content is key to efficient water management in both irrigated and dryland agriculture, but existing soil water sensors do not work well under all conditions. ARS scientists in Bushland, TX, led an international team convened by the International Atomic Energy Agency to assess the

accuracy and utility of the major types of sensors and to produce a book 'Field Estimation of Soil

Water Content: A Practical Guide to Methods, Instrumentation, and Sensor Technology’ for use

by irrigation and natural resource managers, scientists and engineers. The guide indicates which

sensors are useful under which soil conditions. New knowledge about sensor problems in

common soil conditions is being used to develop improved sensors and was transmitted to the

Irrigation Association to guide sensor evaluation in the Smart Water Application Technologies 

program approved by EPA. Sensor manufacturers have requested assistance in solving problems 

with the sensors. Efficient water management can save irrigation costs and conserve valuable

groundwater resources without putting crop yields and profits at risk.

Unmanned aerial vehicles used to improve crop water management. Thermal infrared (TIR) 

emittance has been well­correlated with canopy temperature and often used as a measure of

dissipation of excess energy from plants. However, until recently, field­scale estimates of TIR

emittance have been too expensive, lacking inf temporal resolution, and generally impractical. Recent advancements in TIR cameras mounted in small, unmanned aerial systems have allowed

researchers to assess crop response to irrigation and winter cover crop management at the field

scale. TIR data acquired in this way by ARS scientists at Tifton, GA were more sensitive to crop

response to microclimate conditions compared to traditional, and more time intensive, methods of

assessment. Practical implications of this tool include in­season mitigation of crop stress,

improved irrigation strategies, and an assessment of landscape level effects on crop productivity. This leads to lower risk for the grower, potential savings in water, and reduction in nitrogen loss 

from fields.

New irrigation management software helps conserve water. Performance of gravity (surface) 

irrigation, the prevalent method of on­farm water application in the U.S. and worldwide, typically is 

low (as measured by water used by the crop as a ratio of that delivered to the field). ARS 

researchers at Maricopa, AZ, have released Version 3 of WinSRFR, a surface­irrigation software

program that substantially improves irrigation system design and operation based on hydraulic 

engineering principles. The program can analyze field evaluation data, estimate field infiltration

properties from this data, analyze design alternatives, optimize operations, and conduct

simulation studies. The new release includes new design and operations analysis procedures for 

irrigation system types that were not included in previous versions of the software (open­ and

closed­ended furrows, close­ended borders). Intended users include university extension agents,

farm advisors, irrigation consultants, and irrigation specialists. Previous versions of the software

have been used throughout the U.S. by NRCS.

Both yield and water use are important considerations in selecting a crop to grow. Changing

cropping systems to improve profit and/or conserve water. Rising energy costs for pumping the

diminishing water resources of the Ogallala Aquifer is a major concern of agricultural producers in

south­central regions of the U.S. Crop simulations show that switching from corn to early­ 

maturing cotton varieties would save water and energy costs and improve chances of higher 

economic returns in 91 out of 131 counties in the panhandle regions of Texas and Oklahoma and

southwest Kansas. In other experiments by ARS researchers in Bushland, TX, in­season yield of

forage sorghum (1,700 g per sq m) was less than corn for silage (2,400 g per sq m), but sorghum 

had 27 percent lower evapotranspiration per unit production. As pumping costs escalate and

aquifer water availability decreases, sorghum is an attractive alternative to corn for silage

production in the Southern High Plains. However, corn yields and respective economic returns 

increase at a higher rate than with sorghum, therefore corn would be preferred if water is not a
limiting factor. This kind of research information allows growers to make informed decisions as 

they weigh options between risk and profitability.

Wireless technology facilitates automatic irrigation scheduling . Infrared thermocouples (IRTs) 

have proven reliable for remote measurement of crop canopy temperature as an indicator of crop

water stress. However, wired IRTs would be cumbersome for the grower to set up, maintain, and

dismantle each irrigation season in a commercial system. ARS scientists at Bushland TX, have

developed a prototype wireless sensor device that interfaces an off­the­shelf IRT with an off­the­  shelf radio frequency module to sample, average and send data to an embedded computer at the

irrigation center pivot. This technology will improve automatic irrigation scheduling using sensor 

network systems resulting in more reliability, more accurate and efficient site­specific water 

application and greater savings in water 

Breeding lines of short­season, stress tolerant corn save the stressed Ogallala Aquifer. Plant

breeders and Texas A&M University have developed drought­ and high temperature­tolerant corn

germplasm that requires less water to produce equal yields, and value­added germplasm 

(supersweet corn) to increase crop value. The shrunken (sh2) gene was stacked into drought­  and heat­tolerant and insect­resistant lines, and four supersweet corn inbred lines adapted to the

High Plains also were developed. Multiple­stress­tolerant corn hybrids yielded well under full­  and limited­irrigation conditions. The average silage yield of 20 corn hybrids at two locations in

the Texas High Plains was 26.84 tons/acre under 75% evapotranspiration (ET) irrigation, not

significantly different from 27.49 tons/acre under 100% ET irrigation. A significant amount of

Ogallala Aquifer water can be saved by using new stress­tolerant corn germplasm and adopting

modifications to irrigation recommendations.

Animal wastes a valuable nutrient source for forage crop via subsurface drip irrigation. Land

application of animal waste from livestock treatment systems is an environmental and social

concern in the eastern US. ARS scientists in Florence, SC evaluated the potential of using a

subsurface drip irrigation (SDI) system for application of animal waste effluent to bermudagrass 

hay. Plots receiving treated effluent had significantly greater hay yields than plots supplied with

recommended levels of inorganic fertilizer. Moreover, effluent­treated plots had significantly 

greater nutrient biomass removal than the commercial fertilizer plots. The plant nutrient removal

prevented adverse impacts on soil or water quality.

Salt tolerant plants improve quality of drainage water for reuse. High salinity and selenium (Se) 

contents are major concerns for drainage water reuse in the west side of the San Joaquin Valley 

of California (SJV). ARS scientists in Parlier, CA identified plant species and poplar tree clones 

that were well adapted to sustainable drainage­water reuse strategies and for growing in areas 

with underlying poor quality waters in the west side of the SJV. Seed yields for oil crops ranged

between 1.0 and 1.5 tons/acre, while poplar trees were annually cut and cuttings were considered

for gasification uses. Over 6 years, salt­tolerant plants lowered total soil Se via plant

accumulation and volatilization; however, some leaching of newly deposited extractable Se also

occurred. Improved options for sustainably using an agronomic­based system for drainage water 

reuse strategies can encourage more widespread usage in the regions of central California.

Saline water acceptable for reuse on some floriculture crops. Water reuse can extend available

fresh water supply and decrease drainage disposal requirements. Whereas many floral and

ornamental crops are susceptible to salinity and specific ion toxicity and do not grow well using

saline recycled waters, opportunities exist to use such degraded waters on tolerant species or 

during more tolerant growth stages. ARS researchers at Riverside, CA produced premium stems 

of snapdragon with moderately saline waters and commercially acceptable stems of marigold with

waters of low salinity. Three marigold cultivars maintained high aesthetic value and are

appropriate for salt­affected landscapes. Drainage water releases are prohibited in nursery crop

production areas. These findings provide a method to economically re­use drainage water and

thereby reduce the disposable volume.
Problem Area 3—Drainage Water Management Systems 

Bioreactors developed for improved water quality. Loss of nutrients from heavily fertilized or 

manured fields can lead to water quality degradation and hypoxia in waterways. Nutrient

contamination is a major water quality concern and its remediation a national priority. A novel

approach to drainage water management is to filter the runoff in areas where diffuse flow is 

concentrated through low­cost materials such as industrial byproducts and agricultural waste

products. ARS scientists at Columbus, OH have screened 55 industrial byproducts and found five

that hold promise for removing nitrate, phosphate and atrazine from drainage waters. ARS 

scientists at University Park, PA have evaluated filter designs and materials for phosphorus 

removal, and in Florence, SC, ARS researchers have denitrified drainage waters by directing flow

through biofilters filled with immobilized sludge. In field tests, the immobilized sludge removed 50

percent of the nitrate­nitrogen from drainage water. The calculated removal rate was 94 g nitrate

per day per square meter, which is significantly greater than treatment wetlands.

Problem Area 4—Integrated Soil Erosion and Sedimentation Technologies

Modelling of land cover change can be used as a management tool to reduce erosion. Growth

and development in environmentally sensitive areas can lead to high rates of erosion. ARS 

scientists in Tucson, AZ used landscape metrics (soil type, elevation, and contour detail) in

conjunction with hydrological process models to predict effects of land use/land cover changes to

water and sediment yield. Sub­watersheds in the Willamette River Basin OR were modeled

based on three possible future growth and development scenarios to the year 2050. Variables 

included differences related to conservation, planning, and open development as compared to

1990 land cover. Results identified potential water quality problems that would result from land

cover changes in sensitive environmental areas. Such analyses could be applied to both urban

and agricultural development in a large river basin.

Erosion prediction technology improved for frozen soils. Erosion prediction has consistently 

performed poorly for areas dominated by frozen soil conditions, in which processes including

freezing, thawing, snow accumulation and snow melting significantly affect soil loss. Scientists at

West Lafayette, IN and Pullman, OR have collaborated to release of an updated version of the

Water Erosion Prediction Project (WEPP) model with improved winter hydrology/erosion code, providing the many users of this technology with better predictions of soil freezing, thawing, and

snow melt driven runoff and erosion, which are very important in more northern latitudes. Energy­ 

based winter routines reproduced with reasonable accuracy snow, frost and thaw depths, and

runoff from two widely different treatments.

Starch/polyacrylamide can be used as an amendment to prevent erosion.. Water flowing in

irrigation furrows can erode soil and transport sediment and associated nutrients off the field. A 

new starch/polyacrylamide amendment was compared against polyacrylamide­treated and

untreated furrows in a field test in Kimberly, ID. The new amendment, which is a blend of potato

starch and polyacrylamide (PAM), increased infiltration 20% and reduced soil erosion 65%

compared to untreated furrows. When applied at the same rate, PAM treatment increased

infiltration 13% and reduced erosion 98% compared to untreated furrows. The new

polysaccharide/PAM amendment can be used as an alternative to PAM for improving infiltration

on furrow­irrigated fields, although greater application rates will be needed to provide erosion

control as effectively as PAM.

Sediment retention ponds provide added insurance against erosion losses. Conservation tillage, vegetative buffers and controlled irrigation offer effective measures for reducing erosion losses 

and maintaining high soil productivity. But these systems are somewhat ‘leaky’, especially on

highly erodible soils. Additionally, high rainfall events can bypass these systems and deliver
substantial sediment load to surface waters. The Upper Snake­Rock (USR) Conservation Effects 

Assessment Project (CEAP) was initiated in 2005 to determine the effectiveness of conservation

practices in an irrigated watershed. Water flowing back to the Snake River from the 200,000­acre

watershed is being monitored by ARS researchers in Kimberly, ID. Sediment retention ponds 

have been found to be an effective conservation method. Suspended sediment loss decreased

from 400 lb/acre in 1971 to 50 lb/acre in 2005. Sediment retention ponds installed in 2006 on one

return flow stream reduced annual average sediment concentration from 400 mg/L in 2005 to 70

mg/L in 2007 and reduced sediment load by 5500 tons. This work provides much­needed

quantification of the value of retential ponds to control sediment loading.

Sediment identification techniques provide an effective tool for targeting conservation practices.. Sediment is a major pollutant in many watershed streams, and identification of sediment sources 

is critical to provide cost effective management to these watersheds and reduce sediment

pollution. Using sediment identification techniques, ARS scientists in Tucson, AZ determined that

three subwatersheds on Walnut Gulch Experimental Watershed were contributing 86% of the

sediment load from the watershed and that 65% of the stable carbon isotope leaving the

watershed was from shrub plants that dominate the vegetation on the three subwatersheds. Land managers and landowners using the sediment identification techniques can now determine

areas where they should focus their limited resources to produce the greatest reduction in

sediment loads.

Paper mill sludge enhances surface­mine reclamation. Paper mills generate a large amount of

byproduct that consists of, clay, lime, and fibers too short to make paper. Paper mill sludge (PMS) 

can improve reclamation of surface­coal mines where low pH and organic­carbon levels in the

spoil cover material can inhibit revegetation. However, PMS may adversely impact the water 

quality when used at high rates. Scientists at Coshocton, OH found that rates as high as 672

Mg/ha drastically reduced runoff and erosion and improved soil quality and plant growth

compared to standard reclamation practices, while not increasing the load of other pollutants to

runoff. These results will aid in establishing regulatory guidelines for PMS use and potentially 

increase applications of this byproduct.

Increasing the flow capacity of small watershed flood control dams. The USDA­NRCS provided

technical and financial assistance on design and construction of nearly 11,000 flood control

dams, installed in 47 states since 1947, and half of these will reach their planned service life by 

2018. Stepped spillways offer a cost savings relative to other rehabilitation methods, but there are

design issues that need resolution. Convergent stepped spillways are one potential configuration

but result in increased flow depth near the training wall, so the height of the training walls to retain

the flow in the spillway chute must be determined. ARS engineers at Stillwater, OK developed an

equation for designing the dimension criteria of converging vertical sidewalls. The training wall

height equation for converging spillways will provide design guidance so that the spillway 

adequately operates and protects the remainder of the embankment. Stepped spillways will be

placed over about 10% of the existing dam embankments as a solution to rehabilitation and

safety needs.

Bank­Stability and Toe­Erosion Model (BSTEM) improved. Suspended sediment is one of the

leading causes of surface water­quality impairment, and recent studies have shown that stream 

banks are often the major sediment source in disturbed systems. ARS scientists at Oxford, MS 

enhanced BSTEM to predict sediment loadings from stream banks in a variety of environmental

conditions by conducting simulations under existing and mitigated conditions. Using the model’s 

improved root­reinforcement algorithms that account for plant species, vegetation types, and

plant ages and distributions, riparian buffers that maximize bank stability can be designed and

evaluated before they are actually built. Sedimentload reductions of 50­85% to the streams were

predicted in different environments. BSTEM has been distributed to stakeholders in state and

federal agencies and is taught in workshops at academic institutions and at national technical

meetings.
Problem Area 5—Watershed Management, Water Availability, and Ecosystem 

Restoration

Irrigation scheduling through remote sensing from aircraft. The ability to map evapotranspiration

(ET) and soil moisture availability via satellite has broad applications in monitoring drought and

consumptive water use, administering irrigation projects, predicting local and regional water 

demand, and in providing important boundary conditions to hydrological and weather forecast

models. ARS scientists in Beltsville, MD, and Tifton, GA, have developed algorthims that relate

real­time thermal measurements acquired from saltellite and unmanned aircraft to crop water 

need and crop production projections in both irrigated and rain­fed agricultural landscapes. Thermal infrared data acquired from unmanned aircraft are more sensitive to crop response to

micro­climate conditions compared to traditional, and more time intensive, methods of

assessment. Practical implications of this tool include in­season mitigation of crop stress,

improved irrigation strategies, and an assessment of landscape level effects on crop productivity.

Satellite data used to assess adoption of conservation practices. Conservation tillage is a

commonly adopted best management practice for improving soil quality and reducing erosion;

however, there are currently no methods in place to monitor conservation tillage adoption at the

watershed scale. A mapping algorithm, using commonly available satellite imagery, has been

developed to depict conservation tillage adoption within the Little River Experimental Watershed

in Georgia. The resulting map identified farm sites using conservation tillage with 71­78 %

confidence. Results suggest that currently available satellite imagery can be used to map

conservation tillage adoption with a minimum amount of ground truth collection. The effectiveness 

of conservation practices can be better correlated with changes in water quality and sediment

within watersheds.

Airborne measurements successfully used to classify riparian vegetation. Better methods are

needed for estimating water use in semiarid riparian systems so that regional water balances can

be monitored and healthy riparian flows maintained. Airborne and ground based LIDAR (LIght

Detecting And Ranging) technology was used by ARS scientists in Tucson working with the

Universities of Arizona and Florida. LIDAR­derived estimates of canopy height, crown and trunk 

diameters, and canopy cover were used quickly and accurately to differentiate age classes of

cottonwood trees for riparian areas in the San Pedro River Basin near Benson, AZ. The mean

intensity of return laser pulses from the canopy surface was well correlated with ground

measurements. The LIDAR­derived canopy information has the potential to improve riparian

corridor water use estimates for the Upper San Pedro Basin and other semiarid riparian systems. Accurate water use information is valuable to regional water districts so that efficient and timely 

releases of water can be made for urban, agricultural and ecosystems purposes..

carbon dioxide over large areas can be monitored by satellite. There is a need for techniques to

quantify accurately carbon dioxide (CO2) sources and sinks over large areas because of the

importance of atmospheric CO2 levels on the climate. ARS scientists in Tucson, AZ developed

an approach for producing estimates of daily net CO2 flux using a combination of satellite

imagery, the Water Deficit Index, and Bowen ratio energy balance measurements. This approach

can be used to map daily net CO2 flux at the landscape scale for a better understanding of the

role semiarid grasslands play in the carbon cycle. The information is valuable in monitoring

carbon sequestration in grasslands and evaluating the effects of global climate change.

Natural river wetlands help control pollution. Natural wetlands occurring in the flood plain near 

rivers can be modified and used as management practices to improve and sustain river water 

quality. Studies conducted at Oxford, MS by ARS researchers in a modified natural wetland near 

the Coldwater River in northern Mississippi demonstrated how effectively a wetland could trap

three commonly used agricultural pesticides (atrazine, metolachlor and fipronil) and prevent them
from entering the river. Such an approach may represent an additional tool to improve and

sustain river water quality and overall environmental quality.

Model developed to evaluate overtopping potential in dams.. ARS scientists at Stillwater, OK, have collaborated with NRCS and Kansas State University to complete the alpha test version of

the computer engineering application tool WinDAMa+. Enhancements to the application software

WinDAM,, Windows Dam Analysis Model, allow users to evaluate overtopping limits of vegetated

embankments and to evaluate the integrity of the earthen spillway in one computational package. The software will determine the amount of flow through the principal spillway(s), auxiliary 

spillway(s), over the vegetated or rock rip­rap­protected earthen embankment and erosion of the

auxiliary spillway. This computer tool will be important in evaluating existing structures, with

potential of reducing costs associated with rehabilitation. Dam and levee models help to predict breaching and improve dam design. Most global climate

change predictions agree that floods and droughts will increase in severity. The potential for 

increased flooding places great emphasis on predicting and managing dam­break and levee

breeching events..The original CCHE1D and CCHE2D Free Surface Flow Models were

developed for unsteady turbulent flow, but not for rapidly varying surface flows, which require a

significant advancement of the numerical methods. The National Center for Computational

Hydroscience and Engineering, working with ARS at Oxford MS, and other world organizations,

recently have developed, verified and validated advanced numerical solution methodologies that

have been incorporated into CCHE1D and CCHE2D. The free surface flow models are now

capable of simulating the rapidly varying unsteady flows. This effort shall enable better decisions 

in planning of dam/levee designs and managing dam­break/levee­breaching events. Economic models are being developed to assess the socio­economic impacts of depleting

groundwater from the Ogallala Aquifer. Economic analysis indicates that water costs per acre

using conventional irrigation systems and techniques range from $11.70 to $13.40, whereas the

costs using sprinkler systems range from $12.53 to $15.47. However, pumping costs, due to high

pumping rates under conventional irrigation systems, are higher ($345 to $243 per acre) than for 

sprinkler systems ($158 to $120). Pumping costs decrease from $38 to $102 per acre from 

conventional irrigation systems if Low­Energy Precision Application ( LEPA) techniques are

adopted, while saving ranges for Subsurface Drip Irrigation (SDI) save $10 to $82 per acre. Comparison of irrigation systems indicates that sprinkler systems have advantages over drip

irrigation systems. However, the trade­off between water use efficiency and potential water 

conservation needs to be thoroughly evaluated before suggesting irrigation technology as one of

the policy options for water conservation purposes. Optimization models serve as a valuable tool

to analyze alternative water management strategies. Optimization models are improved for socio­economic decision making in the Southern Ogallala

Aquifer Sub­region. Baseline socioeconomic IMPLAN models were modified and validated for the

Northern, Central, and Southern sub­regions of the Southern Ogallala Aquifer Region. The results 

of optimization models, along with other county­level economic data, are used to compute

projections of the effects of the decline of water in the Ogallala Aquifer on the regional economy 

with respect to industry output, employment, and value added. Baseline regional economic 

impacts with respect to industry output over 60 years for three sub­regions of the Southern

Ogallala are $2.1 billion for the northern region, $929 million for the central region, and $3.1

billion for the southern region. The results reflect more accurate estimates of the economic 

impacts from the natural decline in the Ogallala Aquifer and can help regional water managers 

and government leaders make informed decisions.

Best Management Practices (BMP) are promoted to conserve Ogallala Aquifer water. Ogallala

Aquifer Program participants are required by Congress to transfer technology developments to

the public and to eductate the public on needs to conserve valuable ground water resources. The

participants have worked together to develop reports, technical papers, and journal articles 

describing research results, new developments, and recommendations for practices that support

water conservation. Some products and resources are being adapted for general audiences and
converted to electronic format through the Ogallala Aquifer web site and other electronic media

resources. Materials include a new comprehensive agricultural irrigation curriculum, training

manual and workshop series. Information on management practices for soil water conservation,

tillage and residue management, and irrigation (system efficiencies, evapotranspiration, water 

balance methods) have been presented at workshops reaching about 125 consultants and

producers, 500 Master Gardeners, lawn and tree care professionals, homeowners, 5400 K­12

students, and 200 K­12 teachers. This effort involved more than 40 undergraduate and graduate

students. In addition, Dr. Dirt’s K­12 Teacher Activities website was developed to assist teachers 

with instruction material for soil and water management concepts. Dr. Dirt’s K­12 Teaching

Activities website materials were used by teachers in Illinois, Indiana, Texas, Alaska and New

York. Others users include: The Globe Project at NASA Goddard Space Flight Center­Biospheric 

Sciences Unit, environmental science departments at University of California Berkeley and the

University of San Francisco, and a multitude of other groups at universities, colleges, and

miscellaneous private and public entities.

Problem Area 6—Water Quality Protection Systems

Microbes responsible for Bt endotoxin degradation in soils. The use of genetically­modified crops 

that contain the gene that produces Bacillus thuringiensis (Bt) insecticidal endotoxins has raised

the concern that the endotoxin may persist in the environment. In soil, there is conflicting

information on persistence that is partly due to methodological limitations. ARS scientists at St

Paul, MN, used labelled endotoxin to study its mineralization in soil incubated under controlled

conditions. Fifty­nine percent of the label was recovered as 14 CO2 at the end of the 20­day 

incubation period, indicating a significant degree of degradation of the toxin. Corn residues added

to the soil further stimulated mineralization of the toxin. Since low mineralization (approximately 

6%) of the toxin was observed in autoclaved soil, the findings indicate that microbial processes 

play a major role in the dissipation of the Cry1Ac endotoxin in soil.

DNA­based fecal test may be inaccurate. Fecal contamination in streams and water bodies is 

routinely tested, and DNA primers have been used to identify sources of fecal contamination. The results of the tests can be the basis for important management decisions. Although the

accuracy of a set of Bacteroides­specific primers currently used to distinguish human and non­  human fecal contamination in the environment was previously tested and validated using multiple

fecal sources, ARS scientists in Maricopa found that the human primers cross­amplified with fish

fecal DNA. The primers in question have been used in dozens of fecal source tracking studies, many performed in natural waters where fish could potentially contribute significantly to fecal

contamination. These studies point to the need for additional testing of the primers and will be

useful information for researchers, fish farmers, and public health managers 

Vegetative buffers reduce herbicides in soil and groundwater. Vegetative buffers can be used to

sequester and degrade deposited herbicides, but information is lacking on effective buffer design. Results with five forage species in Columbia MO indicated that the majority of applied atrazine

remained in the soil, and only a relatively small fraction of herbicide leached to shallow

groundwater (<15%) or was taken up by plants (<4%). The grasses enhanced atrazine

degradation in soil through their ability to increase microbial growth and activity in surface soil. Because of its ability to tolerate high levels of exposure to atrazine, switchgrass is recommended

for use in vegetative buffers designed to reduce atrazine transport to surface or ground waters. ARS research in Miami demonstrated that switchgrass buffers effectively stopped endosulfan and

its major degradation products from moving down a 5 percent slope. This research benefits 

conservation agencies, such as NRCS and state conservation departments, since it provides the

needed science for improving vegetative buffer designs for improved protection of water 

resources impacted by row crop production.
Species selection in conservation buffers improves phosphorus removal. Uptake of phosphorus 

(P) in vegetative buffers varies by grass species and phosphorus availability. Harvesting of buffer 

vegetation offers the opportunity to increase supply of harvested biomass and remove nutrients 

that accumulate in buffers. Researchers found that reed canarygrass and switchgrass are better 

choices than smooth brome for P removal through biomass harvest. Switchgrass takes up more

P from soil solutions initially high in P, but reed canarygrass performs best when low P solutions 

receive added P (simulating P inputs from runoff). Results support other recent evidence that

species selection can be critical in determining the effectiveness of conservation practices. This is 

of interest to agricultural producers, conservation planners, and policy makers seeking to improve

buffer design and considering biomass harvest from conservation plantings.