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USGS Staff -- Published Research US Geological Survey
2008
Comparative Study of Transport Processes of Nitrogen, Comparative Study of Transport Processes of Nitrogen,
Phosphorus, and Herbicides to Streams in Five Agricultural Phosphorus, and Herbicides to Streams in Five Agricultural
Basins, USA Basins, USA
Joseph L. Domagalski
USGS
, joed@usgs.gov
Scott Ator
USGS
Richard Coupe
USGS
Kathleen McCarthy
USGS
David Lampe
USGS
See next page for additional authors
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Domagalski, Joseph L.; Ator, Scott; Coupe, Richard; McCarthy, Kathleen; Lampe, David; Sandstrom, Mark;
and Baker, Nancy, "Comparative Study of Transport Processes of Nitrogen, Phosphorus, and Herbicides to
Streams in Five Agricultural Basins, USA" (2008).
USGS Staff -- Published Research
. 26.
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TECHNICAL REPORTS
1158
Agricultural chemical transport to surface water and the
linkage to other hydrological compartments, principally
ground water, was investigated at fi ve watersheds in semiarid
to humid climatic settings. Chemical transport was aff ected
by storm water runoff , soil drainage, irrigation, and how
streams were linked to shallow ground water systems. Irrigation
practices and timing of chemical use greatly aff ected nutrient
and pesticide transport in the semiarid basins. Irrigation with
imported water tended to increase ground water and chemical
transport, whereas the use of locally pumped irrigation water
may eliminate connections between streams and ground
water, resulting in lower annual loads. Drainage pathways in
humid environments are important because the loads may be
transported in tile drains, or through varying combinations
of ground water discharge, and overland fl ow. In most cases,
overland fl ow contributed the greatest loads, but a signifi cant
portion of the annual load of nitrate and some pesticide
degradates can be transported under base-fl ow conditions. e
highest basin yields for nitrate were measured in a semiarid
irrigated system that used imported water and in a stream
dominated by tile drainage in a humid environment. Pesticide
loads, as a percent of actual use (LAPU), showed the eff ects of
climate and geohydrologic conditions. e LAPU values in the
semiarid study basin in Washington were generally low because
most of the load was transported in ground water discharge
to the stream. When herbicides are applied during the rainy
season in a semiarid setting, such as simazine in the California
basin, LAPU values are similar to those in the Midwest basins.
Comparative Study of Transport Processes of Nitrogen, Phosphorus, and Herbicides to
Streams in Five Agricultural Basins, USA
Joseph L. Domagalski,* Scott Ator, Richard Coupe, Kathleen McCarthy, David Lampe, Mark Sandstrom, and Nancy Baker USGS
A
activities can contribute residues of applied
chemicals to rivers and streams. Nutrient enrichment of
streams from agricultural activities is one of the most fundamental
problems aff ecting the management of river basins on a worldwide
basis (Salvia-Castellvi et al., 2005). Nitrogen enrichment is
partially attributable to the increase in use over the last half century.
Estimates of nitrogen use in the Mississippi Basin suggest a 600%
increase since the 1950s (Donner et al., 2002). is increase in
use and other factors resulted in a tripling of nitrate export from
the Mississippi Basin to the Gulf of Mexico over that time period
(Goolsby et al., 2000). Nutrient enrichment of aquifer systems
can also aff ect drinking water supplies and can be a major source
of nitrate to the base fl ow of streams (Spalding and Exner, 1993).
Pesticides entering surface water systems are a concern for ecological
and human health (Solomon et al., 1996; Giddings et al., 2000).
Although it is commonly assumed that rainfall- or irrigation-in-
duced runoff from fi elds in proximity to streams is the primary trans-
port route of agricultural chemicals to streams, eff ective management
requires insight into how these chemicals move through the various
hydrological compartments of the watersheds during annual cycles
and what types of transformation processes are important. Under-
standing the detailed hydrological mechanisms of chemical movement
may best be accomplished in small basins. By choosing representative
basins, eff ective management decisions based on the results of these
studies might be achieved by gaining knowledge of the role of precipi-
tation or irrigation, the unsaturated zone, and ground water transport
with respect to stream loads. Although signifi cant amounts of nitrate
might be transported through the unsaturated zone and remain un-
altered in ground water, denitrifi cation along fl ow paths might aff ect
the nitrate load when the water discharges into a stream.
To better understand the fate and transport of agricultural chemi-
cals in the hydrological cycle, a study was conducted at a diverse group
of fi ve small- to intermediate-sized watersheds in representative agri-
cultural settings of the USA. Capel et al. (2008) described the design
of the overall study. e study design was to complete a mass balance
of water and agricultural chemicals from rain and irrigation, losses of
Abbreviations: DEA, deethylatrazine; ESA, ethane-sulfonic acid; LAPU, load as a
percent of use; OXA, oxanilic acid.
J.L. Domagalski, U.S. Geological Survey, 6000 J St., Sacramento, CA 95819. S. Ator,
U.S. Geological Survey, 8987 Yellow Brick Rd., Baltimore, MD 21237. R. Coupe, U.S.
Geological Survey, 308 South Airport Rd., Jackson, MS 39208. K. McCarthy, U.S.
Geological Survey, 10615 S.E. Cherry Blossom Dr., Portland, OR 97216. D. Lampe
and N. Baker, U.S. Geological Survey, 5957 Lakeside Blvd., Indianapolis, IN 46278. M.
Sandstrom, U.S. Geological Survey, National Water Quality Lab., Denver Federal Center,
Building 95, Lakewood, CO 80225.
Copyright © 2008 by the American Society of Agronomy, Crop Science
Society of America, and Soil Science Society of America. All rights
reserved. No part of this periodical may be reproduced or transmitted
in any form or by any means, electronic or mechanical, including pho-
tocopying, recording, or any information storage and retrieval system,
without permission in writing from the publisher.
Published in J. Environ. Qual. 37:1158–1169 (2008).
doi:10.2134/jeq2007.0408
Received 2 Aug. 2007.
*Corresponding author (joed@usgs.gov).
© ASA, CSSA, SSSA
677 S. Segoe Rd., Madison, WI 53711 USA
SPECIAL SUBMISSIONS
Domagalski et al.: Transport Processes in Five Agricultural Basins 1159
water from evapotranspiration, subsequent movement of water
and chemicals to recharge shallow ground water, and all processes,
including chemical transformations, contributing to stream fl ow,
and loading of agricultural chemicals to those streams. ese basins
were chosen in major agricultural settings across a range of climatic,
land-use, and irrigated settings. e western basins (California and
Washington) used irrigation. Sites were chosen such that imported
water was the source of irrigation water in one and locally pumped
ground water in the other. A Nebraska basin was typical of corn–
soybean rotation in the mid-west, and an Indiana basin allowed
for a comparison of processes in a tile-drainage system. A Mary-
land basin was chosen because of the major role of ground water
discharge in regard to stream fl ow and chemical transport. Stream
hydrology and connections to other environmental compartments,
especially ground water and the relationships between discharge
and chemical loads in the streams, were the major considerations
for this portion of the overall study. e specifi c goals were to
measure the total annual stream discharge and to collect a suffi cient
number of water samples to characterize the annual mass load of
nutrients and selected herbicides and to use the data collected from
other portions of the overall study to interpret transport processes
to the streams.
is paper describes loads of nutrients and organonitrogen
herbicides in fi ve streams; the hydrologic linkages
of the streams to other environmental compart-
ments (especially ground water); the dominant
transport processes aff ecting transport; and the
relative importance of ground water, overland fl ow,
or tile drainage. ese streams are then compared
to determine similarities and diff erences based on
crop types, chemical usage, hydrology, climate, and
types of irrigation methods with respect to trans-
port processes.
Descriptions of Study Areas
Five watersheds—one each in California,
Washington, Nebraska, Indiana, and Mary-
land—were chosen for study. A map showing
the locations of these basins, sampling sites, and
a more detailed description of each basin appears
in a separate article (Capel et al., 2008). ese watersheds en-
compass a variety of cropping patterns and irrigation require-
ments, which are described here briefl y. Basin characteristics
such as area, annual discharge during the period of study,
crops, and soil types are given in Table 1. e use of nitrogen,
phosphorus, and selected herbicides is given in Table 2.
e Mustang Creek watershed is typical of California Cen-
tral Valley agriculture, with orchards, vineyards, row crops, and
animal operations. Mustang Creek is ephemeral, with virtually
all fl ow occurring after winter rains. Irrigation return fl ows are
minor within the lower Merced River basin, of which Mustang
Creek is nested (Domagalski and Munday, 2003), and overland
runoff from storms occurs mainly in the winter. e crops grown
within the Mustang Creek basin are entirely dependent on irriga-
tion because little to no rain falls during the growing season. e
source of irrigation water is locally pumped ground water. Inten-
sive ground water use in this region has resulted in a long-term
decline in water levels. e depth to water below land surface
increased by 24 m from 1975 to 2001. ere is virtually no con-
nection of the stream with the underlying ground water system
because the present-day depth to water is about 53 m below land
surface, although some leakage from the streambed does infi ltrate
into the unsaturated zone.
Table 1. Basin characteristics, discharge, and agricultural practices in the basins studied. Data are for Water Year 2004, 1 Oct. 2003 through 30
Sept. 2004.
State
Basin characteristic
California Washington Nebraska Indiana Maryland
Site Mustang Creek DR2 Drain Maple Creek Leary Weber Morgan Creek
Area, km
2
17.5 5.5 950 7.5 31
Discharge, m
3
193,370† 4,414,500† 62,814,460† 3,095,120† 15,622,720†
Stream ow ephemeral continuous continuous ephemeral continuous
Precipitation, mm 272 187 708 1109 1000
Tile drains no no no yes no
Irrigated land, % >95 >95 30 0 10
Crops almonds, vineyards, row crops
(corn, grain and other)
row crops, vineyards,
orchards, dairies
corn and soybeans corn and soybeans corn and soybeans
Soils sands, silts, clays, hardpans well drained sands
to clays
aeolian sand, silt,
and loess
poorly drained
glacial till
le silt loams
† USGS (2006).
Table 2. Nitrogen, phosphorus, and pesticide use. Pesticide use statistics for California
are from the California Department of Pesticide Regulation (2004). Pesticide use
statistics for other basins are from Capel et al. (2008).
Basin Total N Total P Atrazine Metolachlor Simazine
–––––––––––––––––––––––kg––––––––––––––––––––––––
Mustang Creek, California 209,078† 9650‡ NA§ NA 174
DR2, Washington 62,237¶ 29,452¶ 47 115 26
Maple Creek, Nebraska 4,666,160# 1,536,650# 36,425 37,108 NA
Leary Weber Ditch, Indiana 47,627 8300†† 243†† 36 NA
Morgan Creek, Maryland 226,300‡‡ 145,000 ‡‡ 3463 1997 2162
† Use statistics obtained from local growers or University of California estimates.
‡ Use estimated from land-use (crop map) data compiled by California Department of
Water Resources (1997, 1999, 2003).
§ NA: Data not available, or pesticide not reported, or use was very low.
¶ Estimates based on crop types.
# USDA (2003).
†† Indiana Agricultural Statistics Service (2004).
‡‡ University of Maryland Cooperative Extension and the USDA (2002).
1160 Journal of Environmental Quality • Volume 37 • May–June 2008
e DR2 Drain is located within the Yakima River Basin of
Eastern Washington. is agricultural region is also dependent on
irrigation water. Because of a long history of irrigation with surface
water imported via canal from upland reservoirs, ground water
discharge provides base fl ow to the drain on a year-round basis.
Soils are generally well drained, sandy to clayey in texture, with
depths ranging from shallow to deep. Irrigated agriculture—mainly
orchards, row crops, and vineyards—greatly infl uences the hydrol-
ogy. ere was no evidence of a stream network before agricultural
development, and substantial rises in the water table were noticed
as early as the 1900s (K.L. Payne, U.S. Geological Survey, written
communication, 2006); because of this and locally poor drainage,
the U.S. Bureau of Reclamation designed drainage systems. Under
the current irrigation system, a shallow ground water fl ow system is
responsible for perennial fl ow in the DR2 Drain.
e major crops grown in the Maple Creek watershed (a
tributary to Elkhorn River) of eastern Nebraska are corn and soy-
beans, and most water requirements are met by rainfall. Where
available, irrigation water supplements water requirements. Ma-
ple Creek fl ow is perennial. Ground water infl ux constitutes most
of the stream fl ow during the late growing season and through
the winter. Rainfall-induced runoff , primarily during spring to
summer, contributes fl ow, sometimes at high discharge levels.
e Leary Weber Ditch, a small ephemeral drainage, is within
an agricultural land use planted in corn and soybeans, nested with-
in the Sugar Creek watershed of Indiana. Soils were derived from
glacial tills, and because of poor drainage, tile drains were installed.
Edge-of-fi eld ditches collect the tile-drain discharge, which is then
directed to other local drains and to the Ditch. Direct rainfall con-
tributes little fl ow to Leary Weber Ditch, and there is no ground
water infl ow. Overland fl ow and tile-drain discharge contribute
almost all of the water to Leary Weber Ditch. During storms both
of these sources contribute to the fl ow of the ditch, and between
storms the tile drains fl ow until all of the available water in the soils
above the elevation of the drains is removed (Baker et al., 2006).
e Morgan Creek watershed in eastern Maryland is nested
within the Chester Branch, a tributary to Chesapeake Bay. Climate
in the Morgan Creek watershed is humid and subtropical. Precipi-
tation is relatively evenly distributed throughout the year but may
be more intense during warmer months because of thunderstorms.
Natural precipitation is generally suffi cient to support agriculture,
and crops (mainly corn and soybeans) are irrigated only where soils
are well drained. Slightly more than half (59%) of the fl ow of Mor-
gan Creek is contributed by ground water; the remainder is derived
from overland runoff during and after precipitation (Böhlke and
Denver, 1995; Hancock and Brayton, 2006). Ground water dis-
charges directly through the streambed in the upper part of the wa-
tershed but likely reaches the stream primarily via fl oodplain seeps
farther downstream, where the fl oodplain is wider and streambed
sediments are less permeable (Hancock and Brayton, 2006).
Annual rainfall amounts among the fi ve basins are highly vari-
able (Table 1), and the within-year distribution diff ers among the
basins. Most of the precipitation in the California basin occurs in
the winter, whereas spring to fall thunderstorms contribute most
of the precipitation in Nebraska, Indiana, and Maryland. e
lowest measured precipitation was recorded for the DR2 basin.
A cumulative fl ow frequency plot for the DR2 Drain (Fig.
1) is relatively uniform through the range of fl ow because of the
managed application of irrigation water and very little rainfall.
Stream fl ow at the other two basins that have continuous dis-
charge (Maple Creek and Morgan Creek) has the typical pattern
of base fl ow with infrequent spikes in discharge as a result of
storm water runoff . As a result of the combination of base fl ow
and infrequent runoff events, a cumulative fl ow frequency curve
for Morgan Creek is highly skewed (Fig. 2). e discharge at
Leary Weber discharge is mainly the result of tile drainage with a
small component from overland fl ow. Cumulative fl ow frequency
for Mustang Creek, Maple Creek, and Leary Weber Ditch are
skewed similarly to that of Morgan Creek.
Materials and Methods
Stream discharge was measured using standard USGS tech-
niques (Buchanan and Somers, 1969; Kennedy, 1984). Continu-
ous discharge was recorded at all sites. Water samples were collected
manually, using methods that ensured the samples were width- and
depth-integrated (Wilde et al., 1999), or by an automatic sam-
Fig. 1. Cumulative frequency plot of discharge for the DR2 Drain,
Washington. Period of record, 1 Oct. 2003 through 30 Sept. 2004.
Fig. 2. Cumulative frequency plot of discharge for Morgan Creek,
Maryland. Period of record, 1 Oct. 2003 through 30 Sept. 2004.
