SUMMARY OF ATRAZINE IN EPA REGION 6
SURFACE WATERS
August 2002
U.S. Environmental Protection Agency, Region 6
1445 Ross Avenue
Dallas, Texas 75202-2733

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SUMMARY OF ATRAZINE IN EPA REGION 6
SURFACE WATERS
August 2002
Philip Crocker1, Carl Young2, Mike Bechdol3, Randall Rush4,
Van Kozak2, Sylvia Ritzky4 and Kenneth Williams3
'Ecosystems Protection Branch
2Pesticides Section
3Source Water Protection Branch
4Assistance Program Branch
U.S. Environmental Protection Agency, Region 6
1445 Ross Avenue
Dallas, Texas 75202-2733

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TABLE OF CONTENTS
PREFACE		3
EXE CUT IVE S UMM ARY		4
BACKGROUND		6
Introduction		6
MCL Violations Nationwide and in Region 6		7
Clean Water Act 3 03(d) Listings		7
Concerns about Atrazine in Drinking Water		9
Ecological Concerns		9
DRIN KING W ATER DAT A		10
Texas Data		10
Other States'Data		10
AMBIENT SUR FACE W ATER DAT A		11
Upp er Terrebonne Basin Study		11
Review of LDAF, USGS and EPA Ambient Data		11
Review o f Ambient D ata in EPA STO RET D atabase		12
NRC S MO DEL FOR ATR AZINE RUN OFF		13
EPA R EGIO N 6 - FUN DED ATRA ZINE P ROJE CTS		13
DATA GAPS		14
CONCLUSIONS		14
RECOMMENDATIONS		15
REFERENCES		16
TABLES		19
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Table 1 . Atrazine MCL Violations from the EPA SDWIS Database, 199 3-20 00		20
Table 2. Waterbodies in Texas Included in the State's Clean Water Act Section
303 (d) List Due to Atrazine		21
Table 3. Acute and Chronic Toxicity Values for Selected Freshwater and Estuarine
Species		22
Table 4. Texas Public Water Systems Using Surface Water Only Detecting Atrazine,
1995-1999		23
Table 5. Mean Concentrations of Atrazine Contained in the EPA STORET Database for
Region 6 States of Arkansas, Louisiana, New Mexico, Oklahoma and Texas		25
FIGURES		29
Figure 1. Waters on the Texas Clean Water Act Section 3 03(d) List due to Atrazine		30
Figure 2. Texas Public Water Systems using only Surface Water with Atrazine
Detections		31
Figure 3. Potential for Atrazine Runoffat the Edge ofthe Field to Exceed EPA's
MCL (3 ppb)		32
Figure 4. Monitoring Events with Atrazine Detects in Region 6 States using
STORET Data		33
APPENDICES		34
Appendix A. EPA Preliminary Sampling for Atrazine in North Texas		35
Appendix B. EPA Region 6 - Funded Atrazine Projects		36
Appendix C. Po ssible Monitoring Projects for Investigation of Atrazine in Region 6		40
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PREFACE
In February ofl999 a cross program EPA Region 6 work group was formed to address an issue that was highlighted
by EPA management: atrazine in surface waters. Work group members included Mike Bechdol, Jerry Collins, Philip
Crocker, Brad Lamb, Van Kozak, Omar Martinez, Sharon Parrish, Sylvia Ritzky, Randall Rush, Ken Williams and
Carl Young. In resp onse to the need to better understand atrazine's effects on surface water in Region 6and to
better coordinate between the water and pesticide programs, a Memorandum ofUnderstanding was established
between the Water Quality Protection and Multi-media Planning and Permitting Divisions. The MOA, which was
signed in July 19 99, established a framework for programmatic coordination. The work group met on a quarterly
basis for a three year period and also interfaced with the Texas Watershed Protection Committee, a committee
represented by state and Federal agencies in Texas with the focus being on atrazine. The Region 6 work group
decided that a summary report of atrazine in Region 6 surface waters would b e useful in the coordination process.
This report was prepared by a subgroup to document available information on the nature of the atrazine problem,
including areas of concern, data gaps, and activities underway by EPA and the states which are related to this
pesticide.
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SUMMARY OF ATRAZINE IN EPA REGION 6 SURFACE WATERS
EXECUTIVE SUMMARY
This report serves to summarize information and data on atrazine, a broadleaf herbicide. It represents a product of a
work group formed at EPA Region 6, comp osed of representatives from the Source Water Protection Branch, the
Ecosystems Protection Branch, Assistance Programs Branch, and the Pesticides Section. The mission ofthe work
group is to more effectively addres s the occurrence of atrazine in surface waters of Region 6 and to determine if it
constitutes a s ignificant risk to hum an health and the environm ent. The wo rk group was estab lished in resp onse to
the findings of elevated levels of atrazine in s elected water supp lies in Texas and Louisiana.
Atrazine is the most widely used agricultural pesticide in the United States and is applied as a pre- and post-
emergent herbicide particularly for corn and sorghum production. It is also used on sugarcane and wheat, and for
treating turf and lawns. Atrazine enters lakes and streams through non-point source pathways. Atrazine has the
potential to persist in the water column and bottom sediments. Available information suggests that the water bodies
most vulnerable to atrazine contamination are within watersheds with a high proportion of agricultural land use.
In some source waters atrazine represent a possible risk to human health. Under the Safe Drinking Water Act
(SDW A), EPA has established a Maximum C ontaminant Level (MCL) of 3 micrograms per liter (ug/1) for atrazine
which is applied as an annual average. This MCL is utilized for asse ssing compliance of drinking water systems.
Under Section 303 (d) of the Clean Water Act (CWA), the Texas Natural Resource Conservation Commission
(TNRCC) assesses both ambient and finished drinking water data to determine whether the water supply use
designated in the state surface water quality standards is attained. The TNRCC has identified Lake Aquilla as not
attaining the water supplyuse due to violations ofthe MCL for finished drinking water. Nine additional water
bodies were identified as threatened, having finished drinking water concentrations greater than one-half ofthe
MCL. All of these water bodies are located in the north central Texas region.
Atrazine also represents a potential ecological concern as it is moderately toxic to fish and invertebrates. Adverse
aquatic ecosystem structural and functional effects may occur at atrazine concentrations of 15 ug/1 and above. EPA
has established draft acute and chronic water quality criteria of 350 ug/1 and 12 ug/1 for freshwater, and 760 ug/1 and
26 ug/1 (acute and chronic) for saltwater. Atrazine does not readilybioaccumulate in aquatic organisms. EPA's
CWA Section 30 5(b) guidelines recommend that partial support of the aquatic life use be assigned where acute or
chronic criteria are exceeded more than once within a 3-year period, and non-support be assigned where these
criteria are exceeded in more than 10% of the samples. Available information and data suggest a strong seasonal
pattern of atrazine concentrations in ambient water, corresponding to application of the herbicide within the
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watershed. In watersheds with a high proportion of agricultural land use, chronic criteria exceedances have the
potential to occur during or following spring rainfall events. Recent information suggestthat atrazine may act as an
endocrine disrupter, which couldaffect sexual development in frogs at very low concentrations (<0.1 ug/1).
The watersheds identified as threatened correspond closely to a Natural Resources Conservation Service (NRCS)
relative ranking risk analysis which indicates that watersheds in north central Texas represent a higher risk for
atrazine than other areas of Region 6. In general, there is a paucity of data for atrazine in ambient waters in Region
6. None of the Region 6 states routinely monitor atrazine as part of their fixed station amb ient monitoring program.
However, some states (e.g., Arkansas and Texas) monitor it periodically in certain waters or as part of special
studies. Other data were collected by the U.S. Geological Survey (USGS) under the National Water Quality
Assessment (NAWQA) Program. The USGS has found elevated atrazine concentrations in the Mississippi River,
and the Louisiana Department of Environmental Quality (LDEQ) has found high concentrations in Terrebonne
Parish, Louisiana. Recent monitoring byUSGS and EPA found a watershed in the Ouachita basin, Louisiana, which
did not meet the draft chronic national criterion of 12 ug/1.
Ambient data for atrazine is lacking for the majority ofsurface waters in Region 6. Most of the available data for
Region 6 states was collected by the USGS. Monitoring in Texas is primarily focused on impaired and threatened
waters. The Louisiana Department of Agriculture and Forestry conducts ongoing pesticide monitoring at selected
ambient water quality stations throughout the state. Arkansas periodically monitors for atrazine (and other
pesticides) as part of its ambient monitoring program. Additional monitoring programs and/or geographically
focused studies would be useful to more clearly define the risk of atrazine to human health and the environment.
Such monitoring should be designed to assess long-term concentrations and seasonal patterns of atrazine in ambient
and finished drinking water. Data retrieved from STO RET indicate that certain watersheds represent a higher risk to
human health and the environment than others, particularly in the states of Louisiana and Texas.
EPA e ncourage s the states an d other org anizations to inte grate atraz ine and other currently used p esticides into the ir
existing monitoring and non-point source programs. These activities could include routinely reviewing drinking
water data generated by the water supplies and implementing Best Management Practices (BMPs) through the
Nonpoint Source Water Pollution Program to prevent impairment and to restore impaired watersheds. Special
studies in higher risk watersheds would help to evaluate whether atrazine and other currentlyused pesticides
represent a water quality problem.
BACKGROUND
Introduction
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Atrazine, (CAS number 191 2-24 -9), is an herbicide widely used to control broadleaf weeds. It is the mo st widely
used agricultural pesticide in the U.S. In the U.S., most atrazine is used for corn and sorghum production. It was
first marketed to U.S. firms in 1959 and is still widely used today because it economically and effectivelyreduces
crop losses due to weed competition. In 1991, nationwide, 51 million pounds of active ingredient of atrazine were
applied to 40 million corn acres for an average rate of 1.3 pounds per acre (TSSWCB 200 1). It is also used on
sugarcane, wheat, and turf and lawns. Novartis Crop Protection is the major manufacturer of atrazine (EPA 1999).
Pesticides such as atrazine are regulated under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).
Before a pesticide may be sold or used in the U.S., EPA evaluates information on the pesticide to ensure that it will
not cause "unreasonable adverse effects" to human health or the environment. Pesticides that pass this evaluation
are granted a license or "registration" that permits their sale and use according to requirements set by EPA.
In Texas, atrazine is the pesticide most frequently detected in tap water provided from public drinking water supply
systems. Atrazine can reach water supplies through run-off from fields and other application areas around lakes,
streams or rivers. For the most part, atrazine is not removed from the water by conventional drinking water
treatment systems. To remove atrazine from the water supply, a system would have to use powdered or granulated
activated carbon filtration, at considerable expense (Texas Center for Policy Studies 19 99).
In a national study of streams in the U.S., atrazine (or its degradation product, deethylatrazine or DEA) was among
the herbicides detected more frequently (-80%) than other herbicides, with relatively high levels occurring as
seasonal pulses in corn-growing areas. Average annual concentrations of atrazine were below 3 ug/1 in all but one
site (Larson et al. 1999; USGS 1 999). In the Mississippi Embayment (which includes portions of Arkansas and
Louisiana) study conducted by the USGS, the highest concentration ofpre-emergent atrazine was frequently found
early in the growing season (April-May) prior to planting grain and sorghum (Kleiss et al. 2000). Atrazine was
detected in every sample collected from the Mississippi River and its major tributaries in April through June 1991 at
concentrations ranging from 0.29 and 3.2 ug/1. Seasonal herbicide pulses occurred in response to rainlall after
herbicides were applied to cropland. Atrazine exceeded the MCL concentration for one sample in Baton Rouge,
Louisiana (Goolsby etal. 1991). In south-central Texas, atrazine and deethylatrazine were among the most
commonly detected pesticides in agriculturally influenced, urban and "integrator" watersheds, although
concentrations were relatively low, ranging from 0.0026 to 0.75 ug/1 (Gin 1999; Bush et al. 2000). Seasonal pulses
were apparent in agriculturally influenced streams, with peak levels in the spring (Ging 1 999).
USGS found that among the pesticides monitored in groundwater, atrazine and deethylatrazine were the pesticides
most frequently detected in various studies throughout the nation. In some watersheds groundwater flow may serve
as a significant source of atrazine to surface waters (Barbash et al. 199 9).
The purpose of this report is to summarize information and data on atrazine in surface waters in EPA Region 6
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(Arkansas, Louisiana, New Mexico, Oklahoma and Texas). The report assesses data, highlights areas of concern,
data gaps, and describes EPA-funded atrazine projects related to atrazine.
MCL Violations Nationwide and in Region 6
Under the Safe Drinking Water Act (SDWA), EPA establishes Maximum Contaminant Levels (MCLs) for pollutants
that may be found in drinking water. The MCL for atrazine is 3 micrograms per liter (ug/1) for one year of quarterly
samples (40 CFR 141.61). Water systems are responsible for monitoring finished drinking water to determine
compliance with MCLs. If atrazine (or other organic contaminants regulated under the SDW A) is detected in
finished drinking water, the system is required to monitor on a quarterly basis. The sampling frequency can be
reduced if the system is consistently below the MCL (40 CFR 141.24).
According to the EPA Safe Drinking Water Information System (SDWIS) database, 109 public water systems in ten
States have violated the maximum contaminant level (MCL) for atrazine from 1993 to 2000 (Table 1). Ofthese, 13
were ground water systems and 96 were surface water systems. Five systems in Texas violated the MCL. These
systems received their water from Lake Aquilla, near Hillsboro, Texas.
Clean Water Act Section 303(d) Listings
Under Section 303(d) of the Clean Water Act (CWA), states are required to identify waters notmeeting water
quality standards utilizing available data and information. The Texas Natural Resource Conservation Commission
(TNRCC) includes finished drinking water data into its routine 303 (d) water quality assessment. Texas is the only
Region 6 state whichhas included waterbodies on its 303(d) listdue specifically to atrazine. Ten waterbodies were
listed as threatened or impaired due to atrazine in finished drinking water (TNRCC 2000) (see Figure 1 and Table 2).
These waterbodies are all located in the north central Texas area. In Texas, surface waters are categorized as
impaired when the annual average atrazine concentration in finished water exceeds the MCL. Waters are
categorized as threatened when detections in finished drinking water are above 50 percent of the MCL. For drinking
water systems with nine or fewer samples, two or more must exceed 50 percent of the MCL to be considered
threatened. For systems with more than nine finished water samples, 11 percent or more ofthe samples must exceed
50 percent of the MCL to be considered threatened (TNRCC 200 2).
The state ofTexas delisted segment 1242A, Marlin City Lake, the water supply for the city of Marlin. This lake was
identified as threatened by atrazine on the 1998 303(d) list. The drinking water use is no longer threatened and
instream data show a low probability of fixture atrazine exceedances. Best Management Practices (BMPs), including
education, demonstration and training programs, are in place to reduce future runoff (TNRCC 2000). The Texas
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State Soil and Water Conservation Board (TSSWCB) and the TNRCC have developed a Total Maximum Daily
Load (TMDL) and Implementation Plan for atrazine in Lake Aquilla, which is the primary drinking water source for
Hill County (TN RCC 2 001; 200 2). The annual running average atrazine c oncentration has exceeded 3 ug/1, thus, it
is categorized as use-impaired. (TSSWCB 2001). Monitoring of water qualitywas conducted to assess non-point
source contributions by subwatershed in Lake Aquilla and Marlin City Lake, although drought conditions
considerably limited the quantity of data collected. The TSSWCB has also initiated "Atrazine Remediation
Projects" utilizing Section 319 funding to implement BMPs for reservoirs threatened by atrazine, to reduce the
likelihood for atrazine loads to result in actual use impairments. Finally, the TNRCC initiated a three-year
monitoring project to assess atrazine levels over time in the threatened reservoirs in cooperation with the drinking
water supplies. This monitoring program should aid in evaluating seasonal patterns and the overall effectiveness of
BMP efforts which are underway in those reservoirs.
Other Region 6 states assess available atrazine data and information as part ofthe 303(d) listing process, although
none have identified waters not meeting standards due to atrazine specifically. The states of Louisiana and
Oklahoma have listed waters impaired due to pesticides, thus have the potential to include atrazine as a pollutant of
concern In response to these "generic" pesticide listings, EPA Region 6, through an Interagency Agreement (IAG)
with the USGS, conducted ambient water column sampling for atrazine and numerous other pesticides in
waterbodies listed for pesticides in the Ouachita basin, Louisiana. Atrazine was found to be a pollutant of concern in
one water body in that basin, Big Creek. EPA drafted a TMDL for atrazine utilizing the draft national atrazine water
quality criterion as the target. For other generic pesticides listings, review of existing data and/or ambient
monitoring of appropriate pesticide compounds will be needed to determine which pesticides, if any, are not meeting
narrative or numeric water quality standards, and therefore require development ofTMDLs.
Concerns about Atrazine in Drinking Water
EPA has found atrazine to potentially cause a variety of health effects from exposures at levels above the MCL.
These effects include: adverse effects on the heart, lungs and kidneys; hypotension; antidiuresis; muscle spasms; and
weight loss. Atrazine has the potential to cause weight loss, cardiovascular damage, retinal and muscle
degeneration, and mammary tumors from a lifetime exposure at levels above the MCL. There is also some evidence
that atrazine may have the potential to cause cancer from a lifetime exposure at levels ab ove the MCL (EPA 199 5).
However, EPA recently classified atrazine as "not likely to be carcinogenic to humans" (EPA 2001).
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Ecological Concerns
Atrazineis relatively non-toxic to birds. The dose that is lethal to half of the exposed organisms (LD50) for mallard
ducks is greater than 2,000 milligrams p er kilogram (mg/kg) and at doses o f 5,000 mg/kg no effect was observed in
bobwhite quail and ring-necked pheasants (EXTOXNET 1996).
Atrazine is moderately to slightly toxic to fish and invertebrates. Table 3 lists acute and chronic toxicity values for
selected freshwater andestuarine species. Chronic effect values for freshwater fish species range from 88.3 to 430
micrograms per liter (ug/1), with salmonids being most sensitive. The sheepshead minnow (an estuarine fish species)
had a chronic effect value of2,542 ug/1. Chronic effect values for freshwater invertebrates ranged from 159 to 3,500
ug/1, with the midge (Chironomus tentans) being most sensitive. Chronic effect values for estuarine invertebrates
ranged from 123 to 20,900 ug/1, with mysids beingmost sensitive (EPA 2001).
Based on measured bioconcentration factors (BCFs) and values predicted from the soil adsorption coefficient,
atrazine has a limited tendencyto bioaccumulate in tissues ofaquatic plants and animals (Howard 1991). BCFs
ranged from <0.27 to 8.5 in three species of fish, and the BCF for Dap hnia magna was <5 (EPA 200 1).
Adverse aquatic ecosystem structural and functional effects have most frequently been observed at atrazine
concentrations of 15 ug/1 and above. However, adverse effects have been observed at lower exposure levels. Such
effects have been on both the plant and animal communities, with the effects upon the animal community being
secondary in nature as a result mainly of decreased availability of shelter and plant matter for food. The lowest
reporte d EC5 0 for plants was for the unic ellular alga, Selenastrum capriconutum (4 ug/1) and the lowest value for a
vascular plant (duckweed, Lemnagibba) was 3 7 ug/1 (U.S. EPA 2001). Ecological effects such as reduction in
biomass and inhibition ofphotosynthesis have beenfound at concentrations as low as 0.1 ug/L Levelsof 20 ppb
significantly affect the diet and reproductive success of bluegill and results in adverse effects on several species of
insects, including reductions in species richness, total abundance of several species, and number of herbivorous
insects (Uhler 1992).
The August 2001 draft EPA national criteria document fcr atrazine lists freshwater acute and chronic criteria for
protecting aquatic life of350 ug/1 and 12 ug/1, respectively, and acute and chronic criteria fcr saltwater organisms of
760 ug/1 and 26 ug/1 ( EPA 2001). EPA acute and chronic criteria represent one hour and four day average
concentrations not to be exceeded more than once every three years. These criteria should be protective of both
animals (invertebrates and fish) and plants (EPA 2001). The EPA Office of Water is coordinating with the Office of
Pesticides on revisions to the document, which is expected to be finalized in the fall of 2002 (Frank Gostomski,
EPA, personal communication).
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New data suggest that atrazine may represent a serious ecological concern due to its endocrine disruptor
characteristics. Hayes etal. (2002) found that African clawed frogs (Xenopus laevis) exposed to concentrations of
atrazine>0.1 ug/1 inducedhermaphrodism. Exposure to higher concentrations (> 1 ug/1) demasculinized the
larynges of exposed males, and testosterone levels decreased when exposed to 25 ug/1 atrazine. These studies
indicate that atrazine could have endocrine disruptor effects on native frog populations.
DRINKING WATER DATA
Texas D ata
Texas Drinking Water System data from 1995 to 1999 was obtained from the TNRCC. Atrazine was detected in 85
of 1,162 (7.3%) Texas public water systems with surface water as the onlysource of water. Fifty four of the surface
water systems with atrazine detections sold water to 353 other systems. Maximum atrazine concentrations for these
systems ranged from 0.11 to 10.5 ug/1, with seven ofthe systems with detections at or above the MCL. Figure 2 is a
map of the system locations in Texas. Table 4 lists the surface water systems with atrazine detections. Atrazine
was detected in finished water in only 8 of the 5,500 (0.15%) Texas public water systems with groundwater as the
only source of water. One of the groundwater systems with atrazine detections sold water to one other public water
system. Maximum atrazine concentrations ranged from 0.18 to 3.30 ug/1 with only one system with a detection at or
above the MCL. The population served b y these public water sup ply systems with the p otential for expo sure to
atrazine at or above the detectable limit is greater than 6.3 million.
Other S tates' D ata
Atrazine analysis of finished drinking water is conducted in the other Region 6 states. However, this data is not
currently available in an electronic format to EPA.
AMBIENT SURFACE WATER DATA
Upper T errebonne Basin Study. Louisiana
In 1998 the Louisiana Department ofEnvironmental Quality (LDEQ) and the Louisiana Department of Agriculture
and Forestry (LDAF) undertook a joint atrazine sampling project in the Upper Terrebonne Basin because of
concerns that atrazine could impact the drinking water oflberville, Louisiana (LDEQ 1 998). In 199 8 sugarcane and
corn crops comprised areas of 21,00 0 and 41,00 0 acres, respectively, within this 450,000 acre watershed. A total of
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181 amb ient samples were collected from 31 sample locations. Eighty-two (45.3%) of these samples exceeded the
MCL of 3 ug/1 atrazine. The highest concentration of 21 6.2 ug/1 was collected in mid-April in Bayou Maringouin.
Average atrazine concentrations for 21 of the 31 stations exceeded the MCL, seven of the sites never exceeded the
MCL and, for three stations, atrazine was not found at or above the detection level of 1.0 ug/1. For numerous sites
the data displayed a temporal pattern, with the highest concentrations being in March and April, and much lower
concentrations being in May and June.
Bottom sediment samples were also collected at 30 sites on one date (April or June). Fourteen of the stations
reported detectable concentrations of atrazine, while the remaining stations were below the minimum detection limit.
Sediment levels ranged from 2.2 ug/kg (Bayou Stumpy) to 68.2 ug/kg (Bayou Maringouin), with an average
concentration of 5.9 ug/kg. The project also included collection of effluent samples from seven municipal
dischargers in the basin during the month of March. Atrazine was not detected in concentrations at or above the
minimum detection level of 1.0 ug/1 from any ofthe seven facilities.
Review of LDAF. USGS and EPA Ambient Data
EPA reviewed available ambient water pesticide monitoring data collected by the LDAF and the USGS for the
Mermentau and Vermilion-Teche basins to determine where TMDLs were necessary. TMDLs are necessary where
waters are not meeting narrative or numeric water quality standards. No exceedances ofthe draft atrazine water
criteria for protection of aquatic life were found. The LDAF also routinely monitors ambient concentrations of a
suite of pesticides in other basins in Louisiana. Several waterbodies within the Upper T errebone Basin were found
to have exceedances of the draft EPA chronic criterion of 12 ug/1. Data demonstrated that atrazine concentrations
peaked in late March through mid-April. The more stringent MCL (3 ug/1) was not applicable to the assessment of
ambient data since the waters sampled were not designated in the water quality standards as drinking water supplies.
In the spring and summer of 200 1, EPA established an interagency agreement with the USGS-Louisiana District to
collect samples from eighteen subsegments in the Ouachita basin identified as having pesticides concerns on the
CWA Section 303(d) list of impaired waters. Because no specific pesticide compounds were identified the samples
were analyzedby the EPA Houston Laboratory tor a suite of compounds including atrazine. Atrazine exceedances
were found in one subsegment (detected concentrations 15.1 and 21.3 ug/1), Big Creek. Based on these results of
this monitoring, a Total Maximum Daily Load (TMD L) for this waterb ody was developed for this waterbody.
EPA conducted preliminary sampling for atrazine in the north Texas area utilizing two different laboratory methods
(GC/MS and immunoassay). These results are presented in Appendix A. The values ranged from <0.1 to 0.41 ug/1
(GC/MS) and 0.03 to 0.97 ug/1 (immunoassay). Slightly higher levels utilizing the immunoassay protocol may be
explained since the method analyzes atrazine and other structurally-related triazines additively.
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Review of Ambient Data in the EPA STORET D atabase
Ambient water quality data contained in the STORET database were retrieved. Most data consisted of low or non-
detected concentrations. The data where concentrations were >0.1 ug/1 are presented in Table 5. The data retrieved
were collected between 1995 (the beginning date specified) and 1998 (when Legacy STORET stopped receiving
data). In most instances, sampling was very limited (one or two sampling events per station), and relatively
extensive for a few stations in Louisiana and Texas.
In Arkansas, levels were relatively low, with the highest concentration being 0.87 ug/L In Louisiana, several sites
appeared to be problematic-waterbodies with average concentrations >1.0 ug/1 included the Tensas River at Tendal
(6.0 ug/1), the Red River at Alexandria (1.41 ug/1), and the Mississippi River at St. Francisville (1.03 ug/1). No
stations in New Mexico reported values >0.1 ug/1, and in Oklahoma, only one station had a value >0.1 ug/1. In
Texas, several waters had concentrations >1.0 ug/1, including Plum Creek near Lockhart (10.0 ug/1), Arroyo
Colorado atHarlingen (1.45 ug/1), Big Onion Creek south ofBardwell (7.1 ug/1), Chambers Creek (two sites, 1.84
and 3.0 1 ug/1), Richland-Chambers Reservoir (three sites, 1.57 - 2.60 ug/1), Mill Creek at the Ellis/Navarro County
Line (4.50 ug/1), and at Odem Ranch (2.3 5 ug/1).
Overall, the STORET data indicated that certain watersheds are a greater concern, probably those with a high
agricultural influence. These waters include creeks, a reservoir and larger rivers, with the greatest prevalence in
Louisiana and Texas.
NRCS MODEL FOR ATRAZINE RUNOFF
Usingland use and soil data the USD A Natural Resource Conservation Service (NRCS) compare datrazine runoff
risk among watersheds (Kellogg et al. 1998). NRCS constructed maps to show which watersheds had the greatest
potential for the concentration of atrazine at the edge of the field to exceed the MCL of 3 ug/1. The report notes that
the analysis does not show which watersheds are likely to exceed water quality standards. However, the analysis
serves to p rovide a re lative ranking of risk among w atersheds .
Figure 3, which is derived from the NRCS analysis, shows the relative risk for atrazine in watersheds in Region 6.
Watershed risk was estimated by calculating Threshold Exceedence Units (TEUs). The higher the TEU, the more
risk for a watershed. Figure 3 indicates that the watersheds of central Texas which includes the reservoirs listed on
the 2000 Texas 303(d) list are ofhigher risk for atrazine than other areas in Region 6.
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EPA REGION 6 - FUNDED PROJECTS
A tabulation of EPA Region 6 - funded atrazine projects is presented in Appendix B. The state of Texas, through the
TSSWC B and the TNRCC, Louisiana through the LDEQ, and Oklahoma through O ffice ofthe Secretary of the
Environment to the Oklahoma Conservation Commission (OCC), have dedicated CWA Section 31 9 funds to
quantify and remediate atrazine. Texas has implemented several projects designed to provide both financial and
technical assistance to producers in the impacted watersheds through the development ofwater quality management
plans (WQMPs). There are several recommended best management practices (BMPs) that are being identified for
implementation through these WQMP s: contour firming, grass waterways, grass filter strips, strip cropping, terraces,
incorporate atrazine, rotary hoe and cultivation for weed control, crop rotation, setback areas, no-till farming, split
applications, focus on post-emergence application, band app lication, avoid wet soil application, no application in
high-risk situations.
EPA's primary grantees for funding to control atraz ine have b een the TS SWC B, TNRCC, O CC, and the LDEQ.
Presently in Texas, the TSSWCB has used $4,255,675 of its Section 319 funding to address atrazine through studies
and implementation of WQMPs, while TNRCC has used $157,150 to studythe prevalence ofnumerous chemicals,
including atrazine, in the groundwater of the Edwards Aquifer. LDEQ has dedicated $ 170,0 31 of its federal funds
to improve water quality in the Upper Terrebonne basin from atrazine due to farm practices and compare
concentration of atrazine in surface water runoff from sugarcane. OCC has used $ 280,441 of its federal funds to
sample for several parameters, including pesticides and herbicides such as atrazine in the many seeps of Oklahoma's
western central region. This has meant a total state match of $2,536,067 has been contributed by these states, for a
total of $7,399,364 being spent on federal and state funds to manage atrazine. TSSWCB has submitted preliminary
draft workplans for further atrazine work for fiscal year 2002 Section 319 funding. Their proposed amount for
atrazine management in 2002 is $108,000 federal, but expect to put together a final workplan that would use
$55 0,000 federal, $330,000 as match, for a total of $880,000. This will be targeted for the Little River watershed.
The proposed work has not been included in Appendix B .
DATA GAPS
Data gaps are apparent from both spacial and temporal standpoints. The states do not conduct routine ambient
surface monitoring for atrazine. States should consider incorporating atrazine into their ambient monitoring
programs in urban and agricultural watersheds. Routine monitoring over time will provide some indication of
seasonal variation. However, even limited baseline monitoring in the spring season would aid in assessing potential
risks and for deciding where more intensive sampling may be appropriate. This type of sampling has been
conducted to varying degrees in all five Region 6 states, primarily by state water resource agencies or the USGS..
Page 13

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Periodic monitoring in high risk watersheds is advisable.
Data gaps also exist for finished drinking water. States need to consider data collected by the individual water
supplies in their water qualitymanagementprograms. Texas' ambient data assessment procedures (TNRCC 2002)
include guidelines for assessing finished drinking water data and the state makes use impairment determinations
based on the data. This is facilitated through the use of an electronic finished drinking water database. Most larger
water sup plies mon itor atrazine q uarterly, howev er, data gap s exist for the sm aller water supply systems, and data
collected on a frequent basis to assess concentration patterns are lacking. Possible studies to improve assessment of
risks related to atrazine and which may aid one or more water supplies or states are provided in Appendix B.
CONCLUSIONS
An EPA Region 6 work group was formed consisting of staff from the Ecosystems Protection Branch, Source Water
Protection Branch, Assistance Programs Branch, and the Pesticides Section. The work group served to improve the
Region's understanding of water quality issues related to atrazine, in which cross -program coordination was needed.
This rep ort, in an encapsulated form, presents the results o f a review of data and information related to atrazine in
Region 6. One such water quality problem which demonstrated a need for cross program involvement was Lake
Aquilla, located in north central Texas. The TNRCC has identified this reservoir as having the drinking water use
impaired and nine other water bodies with the drinking water use threatened under Section 303(d) of the Clean
Water Act. The occurrence of atrazine in drinking waters corresponds with a risk analysis of surface water
conducted by NRCS which identifies north central Texas as having a higher potential for atrazine contamination
than other areas within Region 6. The NRCS model utilizes land use and soil type to establish relative risk.
Atrazine is relatively persistent and, due to it's slow breakdown, water column concentrations may become elevated
in lakes, particularly those with watersheds having a high proportion of agricultural corn production. It does not
strongly associate with soil or sediment particles which likely facilitates loading through nonpoint source pathways.
Atrazine is utilized as a pre- and post-emergent pesticide. Applications in this Region begin in late February and
continue into May. Ambient water data indicate a widespread occurrence of atrazine at relatively low
concentrations, with strong seasonal peaks in agriculturally influenced lakes and streams in response to Spring
rainfall. These p eaks may po se a risk to aquatic life residing in these lakes and streams. Risk to human health is
more reflective of temporal average concentrations of atrazine. Other than quarterly monitoring bymunicipal water
supplies, and a special monitoring study presently underway in Texas, temporal data for finished and ambient waters
are lacking.
In addition to corn and sorghum, atrazine is also utilized on sugarcane and residential lawns as a weed control agent.
Thus, watersheds influenced by the production of sugarcane and highly populated watersheds may be at higher risk.
Page 14

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Data for Terrebonne Basin, Louisiana collected by the Louisiana Department of Environmental Quality supports the
association in surface water with sugarcane production. While this review focused on surface water, groundwater
contamination, particularly in Louisiana may be a concern for drinking water supplies relying on groundwater, as
well as where groundwater may serve as a conduit to surface water. This review points out the need for the States
and EPA to ensure that atrazine is being applied properly, to protect water quality and prevent impairment It also
stresses the need to adequately monitor atrazine levels in high risk watersheds, and to develop TMDLs and
implement BMPs in watersheds demonstrating elevated concentrations.
RECOMMENDATIONS
The findings of this review support the following recommendations:
1.	EPA and the states are encouraged to coordinate on a cross-program basis to address atrazine, particularly as it
relates to the p otential for water quality impairm ent. Coordin ation is neede d in the develop ment of water q uality
standards, the development of TMDLs and the implementation of BMPs to restore water quality, and prevent
impairment.
2.	EPA and the states are encouraged to increase the level of monitoring conducted in the Region, particularly in
agricultural and urban areas of higher relative risk. This could include adding atrazine (and other p esticides in
current use) in state ambient monitoring programs, and/or conducting screening level (baseline) monitoring studies.
Monitoring water supplies and finished drinking water are important to assess possible risks to human health.
Monitoring other types ofwaterbodies in agriculturally influenced watersheds is advisable to assess ecological risks
to aquatic life, particularly during the Spring season when applications of atrazine and runoff are expected to be
highest.
3.	EPA and the states should evaluate the adequacyof existing FIFRA regulations applicable to atrazine to assure
protection ofwater quality, and implement Best Management Practices (BMPs) through the Nonpoint Source
Program to addres s loading in high risk watersheds.
4.	EPA and the states are encouraged to share atrazine and other data for raw and finished drinking water. The states
should develop electronic protoc ols to facilitate acces s to electronic sources o f drinking water data. The data should
be reviewed by the states and EPA Region 6 to identify water bodies where the drinking water use maybe impaired
or threatened to determine ifparticular management actions are appropriate.
Page 15

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REFERENCES
Barbash, Jack E., Gail P. Thelin, Dana W. Koplin and Robert J. Gilliom. 1999. Distribution of Major Herbicides in
Groundwater of the United States. U.S. Geological Survey, Sacramento, CA. Water Investigations Report 98-
4245.
Bush, Peter W., Ann F. Ardis, Lynne Fahlquist, Patricia B . Ging, C. Evan Hornig and Jennifer Lanning-Rush. 2000 .
Water Quality in South-Central Texas, 1996-98. U.S. Geological Survey Circular 1213, Austin, TX.
EPA. 1995. National Primary Drinking Water Regulations, Technical Version ofthe Atrazine Fact Sheet. EPA811-
F-95-003, October 1995. U.S. Environmental Protection Agency, Washington, D.C.
(http://www.epa.gov/ogwdwOOO/dwh/t-soc/atrazine.html).
EPA. 2001. Draft Ambient Aquatic Life Water Quality Criteria for Atrazine. Office of Water, U.S. Environmental
Protection Agency, Washington, D.C. January 2001.
EPA. 1999. The Triazine Pesticides: Atrazine, Cyanazine, Simazine, and Propazine. Office ofPesticide Programs
Fact Sheet, August 1999. U.S. Environmental Protection Agency, Washington, D.C.
(www.epa.gov/oppOOOOl/citizens/triazine.htm).
EPA. 2001. Revised Preliminary Human Health Risk Asses sment for Atrazine. Office of Pesticide Programs,
Environmental Protection Agency, Washington, D.C, January 2001.
(www.epa.gov/pesticides/reregistration/atrazine/revsd_pra.pdf).
EXTOXNET. 1996. Atrazine. Extension Toxicology Network, Pesticide Information Profiles. June 1996. Web
site: http://www.ace.orst.edu/info/extoxnet/pips/atrazine.htm.
Ging, Patricia B. 1999. Water-Quality Assessment of South-Central Texas-Descriptions and Comparisons of
Nutrients, Pesticides and Volatile Compounds at Three Intensive Fixed Sites, 1996-98. U ,S. Ge olo gic al S urvey,
Austin, TX.
Goolsby, D.A., R.C. Coupe and D.J. Markovchick. 199 1. Distribution of Selected Herbicides and Nitrate in the
Mississippi River and its Major Tributaries, April Through June 1991. U.S. Geological Survey, Water Resources
Investigations Report 91-4163.
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Hayes, Tyrone BAtif Collins, Melissa Lee, Magdelena Mendoza, Nigel Noriega, A. Ali Stuart, and Aaron Vonk.
2002. Hermaphroditic, demasculinized frogs alter exposure to the herbicide atrazine at low ecologically relevant
doses Proceedings National Academy ofSciences 99: 5476-5480.
Howard, P. H. (Editor). 1991. Handbook of Environmental Fate and Exposure Data for Organic Chemicals,
Volume III, Pesticides. Lewis Publishers, Chelsea, MI. 684 pp.
Larson, Steven J., Robert J. Gilliom and Paul D. Capel. 1999. U.S. Geological Survey Water Resources
Investigations Report 98-4222, Pesticides in Streams of the United States - Initial Results from the National Water-
Quality Assessment Program. U.S. Geological Survey, Sacramento, CA.
LDEQ. 199 8. 1998 Atrazine Activities for the Upper Terrebonne Basin. Office of Water Resources, Louisiana
Department of Environmental Quality, Baton Rouge, LA. December 1998.
Kellogg, Robert L., Joe Bagdon, Susan Wallace, Don W. Goss and Joaquin Sanabria, 199 8. An Information Aid for
Assessing Possible NRCS Involvement in the State Management Plan Process for Regulation of Pesticides. Natural
Resource Conservation Service, Resource As sessment and Strategic Planning Working Paper 98-2, February 199 8.
(www.nhq.nrcs.usda.gov/land/pubs/pestsmp.html).
Kleiss, Barbara A, Richard H. Coupe, Gerard J. Gonthier and Billy Justus. 2000. Water Quality in the Mississippi
Embayment, Mississippi, Louisiana, Arkansas, Missouri, Tennessee and Kentucky, 1995-98. U.S. Geological
SurveyCircular 1208,Pearl, MS.
Texas Center for Policy Studies. 1999. Atrazine Contamination of Texas Drinking Water: Your Right-to-Know
(FactSheet). Texas Center for Policy Studies, Austin, TX.
TNRCC. 2000. 2000 Clean Water Act Section 303(d) List and Schedule for Developing Total Maximum Daily
Loads. Texas Natural Resource Conservation Commission, Austin, Texas.
TNRCC. 2002. Guidance for Screening and Assessing Texas Surface and Finished Drinking Water Quality Data.
Texas Natural Resource Conservation Commission, Austin, TX. February 11,2002.
TSSWCB. 2001. Final Report, Lake Aquilla and Marlin City Lake System: Water Quality Action Plan. Texas
State Soil and Water Conservation Board, Blacklands Research and Extension Center, Temple, TX. February 15,
2001. BRC #01-04.
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Uhler, B . 1992. Atrazine. Web site: http//www .pesticide.org/atrazine .html.
USGS. 199 9. The Quality of Our Nation's Waters-Nutrients and Pesticides. U.S. Geological Survey Circular
1225. 82 pp.
Page 18

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Tables
Page 19

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Table 1. Atrazine MCL Violations from the EPA SDWIS Database, 1993-2000.
STATE
Ground
Water
Systems
Ground Water
Violations
Surface Water
Systems
Surface
Water
Violations
Total
Systems
Total
Violations
Iowa
0
0
1
1
1
1
New York
1
1
0
0
1
1
Wisconsin
1
5
0
0
1
5
Ohio
0
0
2
2
2
2
Pennsylvania
2
2
0
0
2
2
Texas
0
0
5
5
5
5
Indiana
0
0
6
10
6
10
Kansas
1
1
7
7
8
8
Missouri
0
0
11
20
11
20
Illinois
8
27
64
226
72
253
TOTALS
13
36
96
271
109
307
Page 20

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Table 2. Waterbodies in Texas Included in the State's 2000 Clean Water Act Section 303(d) List Due to Atrazine.
Segment No. WaterbodyName	Type of Use Impairment
0303A
Big Creek Lake
Threatened
0507
Lake Tawakoni
Threatened
0815
Bardwell Reservoir
Threatened
0816
Lake Waxahatchie
Threatened
0817
Navarro Mills Reservoir
Threatened
0821
Lake Lavon
Threatened
0836
Richland- Chamb ers Res ervoir
Threatened
0838
Joe Pool Lake
Threatened
1213
Little River
Threatened
1254
Aquilla Reservoir
Impaired*
*This waterbodyis also listed for alachlor (threatened).
Page 21

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Table 3. Acuteand Chronic Toxicity Valuesfor Selected Freshwater andEstuarineSpecies (from EPA 2001).
Concentration in ug/1
		Acute to
Species	Acute Value Chronic Value	Chronic Ratio
Cladoceran	30,000	3,500	>8.571
fCeriodaphnia dubia)
Fathead Minnow	15,000	430	34.88
fPimep hales promelas)
Copepod	13,200	5,010	2.635
fEurvtemora affinis)
Bluegill	>8,000	218	>36.7
(Lepomis macrochirus)
Cladoceran	6,900	187	36.9
fDap hnia magna)
Sheepshead Minnow	5,660	2,542	2.226
fCyprinodon variegatus)
Midge	720	159	4.528
fChironomus tentans)
Page 22

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Table 4. Texas Public Water Systems Using Surfece Water Only Detecting Atrazine, 1995-1999.
SYSTEM NAME
PWS ID
MAXIMUM

NUMBER
LEVEL (PPB)
AQUILLA WATER SUPPLY DISTRICT
1090068
10.50
MARLIN CITY OF
0730002
9.60
CORSICANA CITY OF
1750002
8.40
TAYLOR CITY OF
2460004
5.40
COMBINED WATER SUPPLY CORP, QUINLAN
1160052
4.00
FT WORTH CITY OF
2200012
3.10
COOPER CITY OF
0600001
3.00
WAXAHACHIE CITY OF
0700008
2.90
MANSFIELD CITY OF
2200018
2.60
NORTH TEXAS MUNICIPAL WATER DIST
0430044
2.50
ENNIS CITY OF
0700001
2.40
CAMERON CITY OF
1660001
2.20
WEST TAWAKONICITY OF
1160012
2.00
ARLINGTON CITY OF
2200001
1.80
POINT CITY OF
1900004
1.53
LEWISVILLE CITY OF
0610004
1.50
GROESBECK CITY OF
1470002
1.36
LIVINGSTON REGIONAL WATER SUPPLY
1870129
1.20
STERLING CHEMICALS INC-TX CITY PLA
0840019
1.20
TARRANT REGIONAL WATER DISTRICT
0810035
1.20
DALLAS WATER UTILITY
0570004
1.14
GULF COAST WTR AUTHORITY- TX CITY
0840153
1.13
BRAZOSPORT WATER AUTHORITY
0200497
1.04
INTERNATIONAL PAPER COMPANY, TEXARKANA
0340005
0.92
S L C WATER SUPPLY CORP, GROESBECK
1470031
0.84
CAS H WA TER SUPPLY CORPO RAT ION, GRE EN VILLE
1160018
0.80
DALLAS COUNTY PARK CITIES MUD
0570078
0.80
EMORY CITY OF
1900001
0.80
GREENVILLE CITY OF
1160004
0.78
MAC BEE WATER SUPPLY CORP, WILLS POINT
2340012
0.72
PARIS CITY OF
1390002
0.69
WACO CITY OF
1550008
0.65
ANAHUAC CITY OF
0360001
0.60
BAYTANK HOUSTON INCORPORATED
1012008
0.60
DIANAL AMERICA INCORPORATED, PASADENA
1012841
0.60
MONTELL POLYOLEFINS-BAYPORTPLANT
1011568
0.60
TRA-HUNTS VILLE
2360058
0.60
WILLS POINT CITY OF
2340005
0.60
SULPHUR SPRINGS CITY OF
1120002
0.59
TRA-TARRANT CO WATER PROJECT
2200199
0.56
SOUTH TAWAKONI WATER SUPPLY CORP
2340019
0.51
GRAPEVINE CITY OF
2200013
0.50
WHITE RIVER MUNICIPAL WATER DIST, SPUR
0540015
0.50
Table 4 (continued).
Page 23

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SYSTEM NAME
PWS ID
MAXIMUM

NUMBER
LEVEL (PPB)
LYFORD CITY OF
2450003
0.41
BAYTOWN AREA WATER AUTHORITY
1011742
0.40
GATESVILLE CITY OF
0500002
0.40
TEMPLE CITY OF
0140005
0.40
BELL COUNTY WCID NO 1
0140016
0.39
BLU EBO NN ET W ATE R SU PPLY CO RP, T EM PLE
0140162
0.38
TBCD - OAK ISLAND & DOUBLE BAYOU, ANAHUAC
0360018
0.35
SOLUTTA INC-CHOCOLATE BAYOU PLANT
0200049
0.34
PRESTON SHORES WATER SYSTEM, GRAYSON CO.
0910037
0.33
MABANK CITY OF
1290005
0.30
TEXARKANA WATER UTILITIES
0190004
0.30
WORTHAM CITY OF
0810003
0.30
WEST CEDAR CREEK MUNICIPAL UTILITY
1070190
0.29
ARROYO WATER SUPPLY CORPORATION, RIO HONDO
0310031
0.28
GBRA - PORT LAVACA
0290005
0.28
MACKENZIE MUNICIPAL WATER AUTH
0230004
0.28
POINT COMFORT CITY OF
0290001
0.25
KEMP CITY OF
1290004
0.24
BROWNSVILLE PUBLIC UTILITY BOARD
0310001
0.23
WEST JEFFERSON COUNTY MWD
1230021
0.23
US DENRO STEELS INC, BAYTOWN
0360040
0.22
EAST CEDAR CRK FWSD - BROOKSHIRE
1070167
0.19
UNION CARBIDE - SEADRIFT PLANT
0290003
0.19
VALLEY MUD NO 2 RAN CHO VIEJO
0310059
0.19
LONGVTEW CITY OF
0920004
0.18
STAR HARBOR CITY OF
1070150
0.18
TBCD -HEW, ANAHUAC
0360030
0.18
THREE RIVERS CITY OF
1490002
0.18
BONHAM CITY OF
0740001
0.17
EAST CEDAR CREEK FWSD - B A MCKAY, MAB ANK
1070019
0.17
EAST RIO HONDO WATER SUPPLY CORP
0310096
0.17
SAN PATRICIO MUNICIPAL WATER DIST
2050011
0.17
CAROLYNN ESTATES, HENDERSON CO.
1070106
0.16
HUXLEY CITY OF
2100019
0.16
SEADRIFT COKE LP
0290054
0.16
TERRELL CITY OF
1290006
0.16
UPPER LEON R MUNICIPAL WATER DIST
0470015
0.16
BP CHEMICALS IN CORP - GREENLAKE
0290051
0.13
LA VILLA CITY OF
1080023
0.13
RIO HONDO CITY OF
0310006
0.13
NUECES COUNTY WCID NO 3
1780005
0.12
ALICE CITY OF
1250001
0.11
Table 5. Ambient Monitoring Stations with Mean Concentrations ofAtrazine >0.1 Contained in the EPA STORET
Database for the Region 6 states of Arkansas, Louisiana, New Mexico, Oklahoma and Texas (1995-98).
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Station No.
Location
Mean
Cone.
(ug/1)
No. of
Samples
Arkansas
050083
05UWS042
050126
050120
05UWS040
050125
050128
05UWS009
05UWS009
0UWS023
050102
050079
050080
05UWS051
050122
050137
050284
050024
050123
050114
050166
050127
050183
Arkansas R. at Lock & Dam No. 2	0.40
Little Lagrue B. at Hwy 1 near Dewitt	0.25
Arkansas R. at Lock & Dam No. 9 near. Opello	0.46
St. Francis R. at Lake City 0.30
Bayou Bartholomew at Hwy. 4 near McGee	0.12
Arkansas River at Lock & Dam No. 8	0.44
Arkansas River at Ozark Lockand Dam	0.37
Cache R. at Hwy. 18 near. Gruggs	0.19
Village Creek at Hwy 37, 3 Miles east of Tucker	0.14
Village Creek at Hwy 224 Nr. Newport	0.18
Bayou Meto n ear Bayou M eto	0.14
Arkans as River at Lock & Dam No .4	0.39
Arkansas R. at Lock & Dam No. 5	0.43
Plum Bayou 1 Mi. west ofHwy 15 near Tucker	0.44
L'Anguille R. near Marianna	0.28
Red R. south ofForeman	0.23
Bayou Two Prairie at Hwy 13 south of Carlisle	0.47
Sulphur R. south of Texarkana	0.60
Days Creek southeast of Texarkana 0.11
Cache Creek at Brasfield	0.22
Little Missouri R. near Boughton	0.11
Arkansas R. near Dardanelle	0.42
Des Arc Bayou near Mouth	0.15
Table 5 (Continued)
Station No.
Location
Mean
Cone, fug/1)
No. of
Samples
07263620
Arkansas R.at David D. Terry Lock & Dam
0.30
1
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050124	Arkansas R. at Murray Lock & Dam	0.31	1
050056	Arkansas R. at David T. Terry Lock & Dam	0.37	1
050218	St. Francis R. at Madison	0.87	1
050132	Arkansas R. at Van Buren	0.40	1
05UWS004	Bayou Des Arc County Rd. above Cypress Bayou	0.15	1
05UWS006	Bayou Deview at Hwy. 64 east of McCroy	0.27	1
05UWS007	Cache R. at Hwy. 64 near Patterson	0.26	2
Louisiana
07380500	Bayou LaFourche at Nap oleonville	0.19	1
293848090321200	Bayou LaFourche near Norah	0.24	1
293418090225400	Bayou LaFourche near Cutoff	0.25	1
293408090230300	ICWW west of Larose	0.65	1
293414090225100	Bayou LaFourche below Larose	0.69	1
293439090225500	ICWW east of Larose	0.66	1
294800090490600	Bayou LaFource at Thibidaux	0.65	1
07369500	Tensas River at Tendal	6.00	8
050092	Boeuf River near Arkansas State Line	0.78	1
07374550	Mississippi River at Venice	0.43	11
07381495	Atchafalaya River at Melville	0.92	20
07355000	Red River at Alexandria	1.41	2
07374400	Mississippi River at Luling	0.48	10
07381590	Wax Lake Outlet at Calumet	0.36	14
07381600	Lower Atchafalaya River at Morgan city	0.36	14
07373420	Mississippi River at St. Francisville	1.03	22
Table 5 (Continued)
Station No.	Location
New Mexico
Mean No. of
Cone, fug/1)	Samples
Page 26

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No stations with concentrations >0 .1 ug/1
Oklahoma
07241520
North Canadian River at Britton Rd., OKC
0.13
Texas
08172500
08470400
08057410
08057200
321313096415201
321441096442601
315807096054899
08074500
08075500
08076000
08075770
08212900
08212600
08202790
08202900
08064100
315801096282999
315815096114399
315821096152299
320228096122999
321017096420099
Plumb Creek near Lockhart
Arroyo Colorado at Harlingen
Trinity River below Dallas
White Rock Creek at Greenville Ave., Dallas
Big Onion Creek on FM 98 5 south of Bardwell
Chambers Creek on FM 876
Richland-Chambers Reservoir at Dam
Whiteoak Bayou at Houston
Sims Bayou at Houston
Greens Bayou near Houston
Hunting Bayou atIH610
Tunas Creek near Kingsville
Upp er Chiltipin Canal near Kingsville
Parkers Creek Reservoir inflow near Dhanis
Seco Creek near Yancey
Chambers Creek
Richland Creek on Gravel road near Richland
Richland-Chambers Reservoir-Confl. of arms
Richland-Chambers Reservoir-Richland arm
Richland-Chambers Reservoir-Chambers arm
Mill Creek at Ellis/Navarro County line
0.54
10.0
1.45
0.52
7.1
1.84
1.8
0.72
0.33
0.40
0.24
0.32
0.93
0.15
0.10
3.01
1.89
2.60
1.76
1.57
4.50
1
11
8
7
6
7
2
6
4
5
5
1
1
Table 5 (Continued)
Station No.
Location
Mean
Cone, fug/1)
No. of
Samples
275707097430500
Odem Ranch site 1
0.29
Page 27

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275845097424300	Odem Ranch site 2	2.35	2
08048542	Sycamore Creek at Sycamore Park	0.29	7
324007097110199	Kee Branch at Bardin Road, Arlington	0.30	1
324407097052499	Johnson Creek at Abrams St., Arlington	0.23	8
325114097092199	Sulphur Branch at Harwood Rd„ Bedford	0.59	1
08155240	Barton Creek at Lost Creek Blvd. near Austin	0.10	1
Page 28

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Figures
Page 29

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Figure 1. Waters on the Texas Clean Water Act Section 303(d) List Due to Atrazine.
Page 30

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Page 31

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Figure 2, Texas Public Water Systems Using only Surface Water with Atrazine Detections.
Degas * *
-i * '
*	City
Maximum Level
(parts per billion)
. 0.11-0.41
0.41 -1.04
. 1.04-2.2
2.2-5.4
•	5.4-10.5
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Figure 3. Potential for Atrazine Runoff at the Edge of the Field to Exceed EPA's MCL (3 ppb).*
* Based on NRCS Assessment of
Atrazine Use in Corn and Sorghum
NRCS Threshold Exceedence
Units per Watershed
| Insufficient Data
0
1	- 50000
50001 -100000
100001 -500000
500001 -1000000
| 1000001 -5000000
I 5000001 - 6000000
Page 33

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Figure 4: Monitoring Events with Atrazine Detects in Region 6 States Using STORET Data (Maximum Values Shown).
Concentration
3-47 ppb
1.5 - 2.9 ppb
+ < 1.5 ppb
States
STORET data retrieved from 1/1/95 to 9/29/98
Page 34

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Appendices
Page 35

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Appendix A
EPA Preliminary Sampling for Atrazine in North Texas
On April 24, 2000, EPA did some initial exploratory sampling for atrazine in conjunction with sampling work being
done by the University of North Texas. Single sampling events were conducted for the Elm Fork below Lake Ray
Roberts, Lake Ray Roberts at the dam, Indian Creek below Lake Kiowa, Elm Fork below Lake Ray Roberts and
Spring Creek at 135. These samp les were analyzed by the EPA Regional Laboratory in Houston by GC/MS, Method
525.2 and/or Immunoassay, Method 4670. The results obtained were as follows:
Site Location	Atrazine C oncentration fug/1)
Method 5 25.2 Method4670*
Elm Fork below Lake Ray Roberts	0.41	0.56
Lake Ray Roberts at Dam	0.40	0.97
Elm Creek above Lake Ray Roberts	NA*	0.03
Indian Creekbelow Lake Kiowa	<0.1	0.06
spring Creek at 135 in Valley View	NA	0.36
*NA - not analyzed
These results indicate the presence ofatrazine at low levels (<1 ug/1) at several locations within the Lake Ray
Roberts watershed. The immunoassay method results showed higher results than the GC/MS results for two of the
three sites where side-by-side analyses were conducted. This likely reflects the fact that the immunoassay method
analyzes atrazine and other structurally-related triazines, thus producing an additive concentration (Musick et al.
2000).
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Appendix B
EPA Region 6 - Funded Atrazine Projects
Information on EPA Region 6 - funded projects is presented in the table below. The table, which is accurate through
December 2001, includes various project titles, local project leads, project goals, effected watersheds, funding
summary, and the number of water quality management plans (WQMPs) developed, certified by an agency engineer,
and minimum amount to be developed according to the approved workplan. Several of these projects do not have
numbers attached as of yet since many of these are just getting underway. Under the funding column, the symbols
used are defined as F=federal, M=match, T=total.
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TEXAS ATRAZINE PROJECTS
Project Title
Project Goals
Fundinq
WQMPs*
The North Texas Atrazine
Remediation Project
Lead - Limestone Falls
SWCD*
Submitted by the TSSWCB - This project will provide corn and
sorghum producers in the Richland Chambers Reservoir with
financial/technical assistance for BMP implementatbn aimed at
reducing atrazine runoff, and will provide water quaity educational
activities.
F-$130,849
M-$87,232
T-$218,081
Dev - 9
Cert-5
Min - 5
The North Central Texas
Atraziie Remediatbn
Project
Lead - Hill, Blackland,
and Johnson SWCDs
Submitted by the TSSWCB - This project will provide corn and
sorghum producers ii the Aquilla and Richland Chambers Reservoir
watersheds with financial/technical assistance for BMP
implementation aimed at reducing atrazine runoff, and wil provide
water quality educational activities.
F-$1,440,600
M-$960,400
T-$2,401,000
Dev- 44
Cert-25
Min -70
The North Central Texas
Atraziie Remediatbn
project
Lead - Navarro SWCD
Submitted by the TSSWCB - This project will provide corn and
sorghum producers ii the Richland-Chambers Reservoir watershed
with financial/technical assistance for BMP implementation ained at
reducing atrazine runoff, and will provide water qualiy educational
activities.
F-$404,200
M-$269,467
T-$673,667
Dev-13
Cert - 2
Min - 25
The North Central Texas
Atrazine Remediatbn
project
Lead - Dalworth SWCD
Submitted by the TSSWCB - This project wil provide corn and
sorghum producers in the Joe Pool Lake Reservoir watershed with
financial/technbal assistance for BMP implementation aimed at
reducing atrazine runoff, and will provide water quality educational
activities.
F-$93,849
M-$62,566
T-$156,415
Dev - 4
Cert - 1
Min - 5
The North Central Texas
Atraziie Remediatbn
project
Lead - Ellis - Prairie
SWCD
Submitted by the TSSWCB - This project wil provide corn and
sorghum producers ii the Joe Pool Lake, Lake Waxahachie, and
Bard well Reservoir watersheds with financial/technical assistance for
BMP implementation ained at reducing atrazine runoff, and will
provide water quaity educatbnal activiies.
F-$456,700
M-$304,467
T-$761,167
Dev -
Cert -
Min -30
The North Texas Atrazine
Remediation project
Lead - Collin Co. SWCD
Submitted by the TSSWCB - This project will provide corn and
sorghum producers in the Lake Lavon, Lake Tawakoni, and Big
Creek Lake watersheds with financial/technical assistance for BMP
implementation aimed at reducing atrazine runoff, and wil provide
water quality educational activities.
F-$404,200
M-$89,583
T-$493,783
Dev -
Cert -
Min - 25
The North Texas Atraziie
Remediation project
Lead-Hunt Co. SWCD
Submitted by the TSSWCB - This project wil provide corn and
sorghum producers ii the Lake Lavon, Lake Tawakoni, and Big
Creek Lake watershed with financial/technical assistance for BMP
implementation aimed at reduciig atraziie runoff, and wil provide
water quality educationalactivities.
F-$540,700
M-$136,166
T-$676,866
Dev -
Cert -
Min - 35
The North Texas Atraziie
Remediation project
Lead - Kaufman Van-
Zandt SWCD
Submitted by the TSSWCB - This project will provide corn and
sorghum producers in the Lake Lavon, Lake Tawakoni, and Big
Creek Lake watersheds fiiancialAechnical assistance for BMP
implementation aimed at reducing atrazine runoff, and will provide
water quality educationalactivities.
F-$93,849
M-$17,916
T-$111,765
Dev -
Cert-
Min - 5
The North Texas Atrazine
Remediation project
Lead - Fannin SWCD
Submitted by the TSSWCB - This project will provide corn and
sorghum producers ii the Lake Lavon, Lake Tawakoni, and Big
Creek Lake watersheds with financial/technical assistance for BMP
implementation aimed at reducing atrazine runoff, and will provide
water quality educational activities.
F-$246,700
M-$35,833
T-$282,533
Dev -
Cert-
Min -10
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The North Texas Atrazine
Remediation project
Lead - Upper Elm-Red
SWCD
Submitted by the TSSWCB - This project will provide corn and
sorghum producers in the Lake Lavon, Lake Tawakoni, and Big
Creek Lake watersheds with financialAechnical assistance for BMP
implementation aimed at reduciig atraziie runoff, and wil provide
water quality educationalactivities.
F-$246,700
M-$35,833
T-$282,533
Dev -
Cert-
Min -10
Lake Aquilla & Marlin City
Lakes System-WQAP
Lead-TAES-Blackland
Research & Extension
Center
Submitted by the Texas Agricultural Experiment Statbn through the
TSSWCB - This project provided water quality educational activities,
implemented best management practices (BMPs),and monitoied the
major tributaries and reservoirs for atrazine contamination.
F-$197,328
M-$131,522
T-$328,850
(Completed)
N/A
Water Quality & Flow Loss
Study, Edwards Aquifer
Lead - Barton Springs/
Edwards Aquifer
Conservation District
Submitted by TNRCC - Many land use changes are occuiring ii the
Barton Springs portbn of the Edwards aquifer. This study is to
provide a comprehensive groundwater baseline of the area to see if
these land use changes are having a detrimental impact on the
aquifer. Numerous constituents are being monitored, including
atrazine.
F-$157,150
M-$104,767
T- $261,917
N/A
Total for Texas

F-$4,412,825
M-2,235,752
T-$6,648,577
Dev - 70
Cert-33
Min-220
LOUISIANA ATRAZINE PROJECTS
Proie ct Title
Proie ct Go als
Funding
WQMPs
Fate of Atrazine Herbicide
in Soils as Affected by
Suga r Can e Ma nag erne nt-
LSU-Ag Experiment
Statbn
Submitted by LDEQ to fund Louisiana State University's (LSU)
Agriculture Experiment Station. This project takes place in the
Upper Terrebonne River Watershed. Its objectives are to improve
water qualify in the Upper Terrebonne Parish from atrazine due to
farm practbes; compare concentration of atrazine in surface water
runoff from sugarcane grown under conventional methods; obtain
quantifiable surface water data on concentration of atrazine and
metribuzine present in Surface runoff when BMPs are used; make
recommendation on BMP that is effective at reducing atrazine runoff;
education and outreach.
F-$170,031
M-$113,354
T-$283,385
N/A
Total for Louisiana

F-$170,031
M-$113,354
T-$283,385

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OKLAHOMA ATRAZINE PROJECTS
Project Title
Proiect Goals
Fundinq
WQMPs
Technical Assistance to
Improve the Quality of
Ground Water-Surface
Water Interactions
Lead - Oklahoma
Conservatbn Commission
(OCC)and Oklahoma
State University
Cooperative Extensbn
Service (OCES)
Submitted by the Oklahoma Office of the Secretary of Environment -
This project had a sampling component (OCC) which sampled for
several parameters, including pesticides and herbicides such as
atrazine in the many seeps of the area. It also included an
educational component (OCES) demonstrating to producers
Integrated Pest Management techniques, proper pesticide sprayer
use and calibration, and alternative herbbide application routines.
F-$280,441
M-$186,961
T-$467,402
NA
TotalforOklahoma

F-$280,441
M~$186,961
T-$467,402



Fundinq
WQMPs
Total for Region 6

F-$4,863,297
M-$2,536,067
T-$7,399,364
Dev - 70
Cert-33
Min-220
* Defining Abbreviations:
SWCD - Soil & Water Conservation District.
WO MPs - Water Quality Management Plans. Theseplans are written an/or certified bypersonnel ofthe TSSWCB
and accepted by the local SWCD. These plans include a comprehensive plan to remediate all potential sources of
pollution an individual farm mayhave.
Dev - The number of WQMPs that have been developed as a part ofthe project
Cert- The number of WQMPs that have been certified by a TSSWCB staff engineer
Min - The minimum number of WQMPs that are to be developed in the approved grant workplan submitted from the
State to EPA.
F - Federal funding amount
M - Match funding (State and in-kind sources) committed
T— Total project amount combining federal and match figures
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Appendix C
Possible Monitoring Projects for
Investigation of Atrazine in Region 6
1.	Sampling of of Atrazine Raw and Finished Drinking Water for Selected Municipal Drinking Water
Supplies in North Central Texas - This possible study would involve the cooperation of one or a limited
number of cities located in a high risk watershed. Raw and finished drinking water could be collected on a
frequent basis (e.g., daily, 5 days/week) for one year to assess temporal patterns in concentrations of
atrazine, and risk to human health and the environment. The study would be coordinated by Region 6
staff Sampling would be conducted by one or more cities interested in participating at no cost. Analyses
would be conducted bythe EPA Houston Lab using immunoassaymethods. Additional methods (e.g., gas
chromatography) could be carried out to supplement and/or confirm immunoassay results. The intent of the
study would be to answer the question: "How does atrazine concentration change in raw and finished
drinking water over time, and is existing monitoring adequate to characterize seasonal atrazine
concentrations ?"
	Estimated cost The only costs incurred would be existing Regional Office and Lab staff time, and inkind
cooperation from one or more cities.
2.	Sampling of Atrazine in Drinking Water Supply Reservoirs in High Risk Watershedfs) - This possible study
would involve collection ofambient water near selected water supply reservoirs located in "high risk"
watersheds. The study would be coordinated by Region 6 staff Sampling would be conducted
approximately monthly for one year in the vicinity of the water supply intake structure. Sampling would be
carried out by one or two states, orthe USGS. This study could include a broad spectrum ofmodern
pesticides using gas chromatography or other methodology. Analyses could potentially be conducted by
the EPA Regional Lab, or the USGS Laboratory. The intent of the study would be to answer the question:
"Is atrazine present at deleterious concentrations in previously unsampled reservoirs in agricultural and/or
urban "high risk" watersheds?
	Estimated cost Level of effort could be adjusted to budget. Proposed budget:$75K for sample collection
and analysis bystates or USGS.
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