United States
Environmental Protection
Agency
Office of Water
4606
EPA816-R-98-017
September 1998
s>EPA Drinking Water and Ground Water
Data Within the 305(b) Program
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Preface
Many of the new initiatives in the Agency in the last couple of years and the requirements
of the SDWA Amendments of 1996 require EPA and the States to use monitoring data for the
support of various programs. These programs may benefit from the use of existing sources of
monitoring data.
. Monitoring data gathered by States under Section 106(e) of the Clean Water Act (CWA)
are submitted to the Administrator in biennial State Water Quality Reports as required under
Section 305(b) of this same act. The National Water Quality Inventory Report to Congress
[305(b) Report] summarizes the water quality information submitted by the 58 States, American
Indian Tribes, Territories, Interstate Water Commissions, and the District of Columbia in their
water quality assessment report. This Report is the primary vehicle for informing Congress and
the public about general water quality conditions in !the United States. The Implementation and
Assistance Division of the Office of Ground Water and Drinking Water has the responsibility for
producing the drinking water and ground water portions of this report.
Since 1982, monitoring data related to drinking water quality and ground water quality
have been included in these biennial submissions, yielding a wealth of data that has applications
to many other programs and initiatives within the Environmental Protection Agency (EPA). The
four reports included in this document analyze the types of data reported by States under the
305(b) program and the relationship of this data to other Office of Water programs and
initiatives.
Contractor support was provided under Contract Number 68-C7-0056 with the Research
Triangle Institute (RTI), Center for Environmental Analysis, Research Triangle Park, NC.
Michael J. McCarthy, Program Manager and Mary T. Siedlecki and Susan B. Goldhaber, Task
Leaders were the key contributors.
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September 15, 1998
Review and Analysis of the 305(b) Ground Water
Data Base to Support the Index of Watershed
Indicators (IWI) Project
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Table of Contents
1.0 Introduction j_j
2.0 305(b) Ground Water Program Development 2-7
3.0 1996 305(b) Guidelines for Assessing Ground Water Quality 3-7
3.1 Aquifer Vulnerability j./
3.2 Ground Water Condition 3.7
3.3 Conclusions Regarding the Data Elements Requested Under 305(b) 3-4
4.0 1996 305(b) Data Set 4.2
4.1 Spatial Display 4.1
4.2 National Coverage 4.2
4.3 Data Sources 4-10
4.4 Conclusions Regarding the Use of the 1996 305(b) Data Set 4-77
5.0 Potential Alternatives 5.7
6.0 Conclusions /c /
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Section 1.0
Introduction
1.0 Introduction
The purpose of .the Index of Watershed Indicators (IWI) Initiative is to develop a more
complete descriptive technique for characterizing the condition and vulnerability of our Nation's
water resources than has been available previously. The IWI is a compilation of data that
characterizes the overall "health" of our Nation's water resources. Characterization is based on
the use of 15 indicator parameters selected to describe whether rivers, lakes, streams, wetlands,
and coastal areas are "well" or "ailing" and whether activities in the vicinity of our Nation's
waters are placing the waters at risk. The indicator, parameters were selected based on their
appropriateness relative to project objectives, their relatively uniform availability across the
Nation, and the ability to depict them at the defined scale. Seven of the indicators characterize
the condition of our Nation's water resources, and eight characterize vulnerability. All 15
indicators are related to surface water resources. There are no indicator parameters to describe
ground water condition or vulnerability. This is due, primarily, to the lack of a data source to
support a ground water indicator.
The condition of our Nation's ground water resources is monitored and assessed under
Section 106(e) of the Clean Water Act (CWA), which requests that each State monitor ground
water quality and report the findings to Congress in their biennial 305(b) State Water Quality
Reports. Ground water quality data, reported by States under the CWA, are compiled and
maintained in a data base. The purpose of developing and maintaining these data is to develop
an accurate representation of our Nation's ground water quality. This purpose is congruent with
that of the IWI. Hence, the question has been raised whether the 305(b) ground water quality
data base could be used to support development of an IWI indicator characterizing ground water
vulnerability and/or condition.
This report analyzes the data collected under Section 305(b) of the CWA and assesses its
appropriateness to support a ground water indicator under the IWI Initiative. This analysis will
be approached as follows:
Review the data elements requested in the 1996 Ground Water Guidelines to assess their
appropriateness for application to the IWI Initiative;
Review the data submitted by States in their 1996 305(b) State Water Quality Reports to
determine if the data reported in the 1996 305(b) cycle is sufficient to develop a ground
water indicator layer characterizing aquifer vulnerability and/or condition;
Evaluate the potential of using State-supplied geographic information system (GIS)
spatial datasets or databases in conjunction with 305(b) data;
• Evaluate the Safe Drinking Water Information System as a supplemental or alternate
source of ground water quality data.
1-1
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Section 1.0
Introduction
Because so much of this analysis depends on the data elements requested under
Section 305(b) of the CWA, a brief history of the 305(b) ground water program development is
included in this memorandum.
1-2
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Section 1.0
Introduction
1.0 Introduction
The purpose of the Index of Watershed Indicators (IWI) Initiative is to develop a more
complete descriptive technique for characterizing the condition and vulnerability of our Nation's
water resources than has been available previously. The IWI is a compilation of data that
characterizes the overall "health" of our Nation's water resources. Characterization is based on
the use of 15 indicator parameters selected to describe whether rivers, lakes, streams, wetlands,
and coastal areas are "well" or "ailing" and whether activities in the vicinity of our Nation's
waters are placing the waters at risk. The indicator parameters were selected based on their
appropriateness relative to project objectives, their relatively uniform availability across the
Nation, and the ability to depict them at the defined scale. Seven of the indicators characterize
the condition of our Nation's water resources, and eight characterize vulnerability. All 15
indicators are related to surface water resources. There are no indicator parameters to describe
ground water condition or vulnerability. This is due, primarily, to the lack of a data source to
support a ground water indicator.
The condition of our Nation's ground water resources is monitored and assessed under
Section 106(e) of the Clean Water Act (CWA), which requests that each State monitor ground
water quality and report the findings to Congress in their biennial 305(b) State Water Quality
Reports. Ground water quality data, reported by States under the CWA, are compiled and
maintained in a data base. The purpose of developing and maintaining these data is to develop
an accurate representation of our Nation's ground water quality. This purpose is congruent with
that of the IWI. Hence, the question has been raised whether the 305(b) ground water quality
data base could be used to support development of an IWI indicator characterizing ground water
vulnerability and/or condition.
This report analyzes the data collected under Section 305(b) of the CWA and assesses its
appropriateness to support a ground water indicator under the IWI Initiative. This analysis will
be approached as follows:
• Review the data elements requested in the 1996 Ground Water Guidelines to assess their
appropriateness for application to the IWI Initiative;
Review the data submitted by States in their 1996 305(b) State Water Quality Reports to
determine if the data reported in the 1996 305(b) cycle is sufficient to develop a ground
water indicator layer characterizing aquifer vulnerability and/or condition;
• Evaluate the potential of using State-supplied geographic information system (GIS)
spatial datasets or databases in conjunction with 305(b) data;
• Evaluate the Safe Drinking Water Information System as a supplemental or alternate
source of ground water quality data.
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Section 2.0
305(b) Ground Water Program Development
that the Nation's ground water resources were "quite good." Similar conclusions were drawn in
subsequent biennial reports.
Broad generalizations concerning the quality of State ground water resources failed to
provide either a complete or an accurate representation of ambient ground water conditions
(i.e., background or baseline water quality conditions). However, assessing the quality of our
Nation's ground water resources is no easy task. An accurate and representative assessment of
ambient ground water conditions ideally requires a well designed and well executed monitoring
plan. Such plans are expensive and may not be compatible with State administrative, technical,
and programmatic initiatives. As a consequence, EPA in partnership with interested States
critiqued the existing guidelines and proposed changes to the guidelines that would improve
assessment of ground water quality within the 305(b) program. The new guidelines were
introduced to States as part of the 1996 305(b) reporting cycle.
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Section 3.0
1996 305(b) Guidelines for Assessing Ground Water Quality
3.0 1996 305(b) Guidelines for Assessing Ground
Water Quality
In the 1996 Ground Water Guidelines, EPA requested that States report data for specific
aquifers or hydrogeologic settings (e.g., watersheds) within the State. The focus on specific
aquifers or hydrogeologic settings provides a more quantitative assessment of ground water
quality than was possible prior to 1996. It is this focus on aquifers/hydrogeologic settings that
make 305(b) ground water quality data suitable for use in supporting the IWI Initiative. Data
related to aquifer vulnerability and condition were reported by States in 1996 using two table
formats specified in the 1996 Guidelines.
3.1 Aquifer Vulnerability
States reported on the type and number of contamination sites per aquifer or
hydrogeologic setting having the potential to adversely impact ground water quality using the
form presented in Table 1 of this report. Specifically, States were asked to identify the type and
number of contaminant source(s) present in the reporting area (e.g., NPL, LUST, RCRA,
Superfund), the number of sites that are listed or have confirmed releases, and the number of
sites with confirmed ground water contamination.
The data reported in Table 1 provide a measure of aquifer vulnerability analogous to
several existing IWI indicators (e.g., Aquatic/Wetland Species at Risk) and could easily be
translated into an IWI indicator of ground water vulnerability. One possible indicator might be
the number of sites having the potential to affect ground water quality for a specified aquifer or
hydrogeologic setting. Another potential indicator is the number of sites with confirmed ground
water contamination for a specified aquifer or hydrogeologic setting. Thus, purely from a data
element point of view, information currently being requested from States under the 305(b)
program could be used to develop an IWI indicator representing ground water vulnerability.
3.2 Ground Water Condition
States reported ground water monitoring data for specified aquifers or hydrogeologic
settings using the form presented in Table 2 of thisxeport. States compared quantitative ground
water monitoring data to water quality standards. Depending upon the results of the comparison,
the data were summarized into major categories, including "not detected at or above the method
detection limit (MDL)," "exceeding the MDL but less than the maximum contaminant level
(MCL) defined under the Safe Drinking Water Act," and "exceeding the MCL." This type of
data provides a measure of the condition of the aquifer and again is analogous to several existing
IWI indicators (e.g., Ambient Water Quality Data — Four Toxic Pollutants).
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Section 3.0
1996 305(b) Guidelines for Assessing Ground Water Quality
The information requested using Table 2 under the 305(b) program can support development of
an IWI indicator depicting ground water condition. One possible example of how this information
could be used is the characterization of aquifers or hydrogeologic settings having constituent
concentrations exceeding MCL values. An example using nitrate follows later in this report.
3.3 Conclusions Regarding the Data Elements Requested Under 305(b)
Information currently being requested from States under the 305(b) program can be used to
develop IWI indicators representing both ground water vulnerability and condition. The data elements
are
• appropriate relative to IWI objectives,
• uniformly available across the Nation, and
• can be depicted in a GIS format of an appropriate scale.
Furthermore, the 305(b) program has by necessity begun the task of developing a database to compile
and maintain the large volume of ambient ground water quality data being collected by State agencies
throughout the Nation. Data elements that can be used to describe aquifer vulnerability and ground
water condition have been defined under the 305(b) program, and the framework for reporting ambient
ground water data on a biennial basis is in place.
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Section 4.0
1996 305(6) Data Set
4.0 1996 305(b) Data Set
Given the suitability of the data elements used to assess ground water quality under the
305(b) program, the next logical question is whether the data set reported in 1996 can be used to
develop ground water layers for GIS coverages. Specifically, is the existing 1996 305(b) data set
sufficient to support development of an IWI ground water layer in terms of spatial display,
national coverage, and data sources? The following sections investigate this question.
4.1 Spatial Display
For surface water data layers within the IWI Initiative, EPA's Office of Water
emphasized the importance of organizing water quality improvement efforts on a consistent basis
and selected the watershed approach for this purpose. The United States Geological Survey
(USGS) developed a Hydrogeologic Unit Classification (HUC) System of watersheds at various
scales and mapped these watersheds. The IWI is depicted at the "eight-digit scale — the smallest
nationally consistent set of watersheds in the HUC system."
Only one of the States reporting ground water quality data for the 1996 305(b) cycle
reported data on a watershed basis. All other reporting entities utilized other reporting units
(e.g., aquifers, hydrogeologic subareas, ground water basins, counties). Although an
inconsistency exists between the units used to report ground water quality and surface water
quality data, this inconsistency does not negate the use of the 305(b) data for developing an IWI
ground water layer.
Due to the disparity between ground water flow systems and watersheds, a methodology
is needed to permit ground water quality data to be spatially displayed jointly with watershed
data under the existing HUC system. A separate and unique data layer must be developed for the
ground water quality data. The ground water data layer must be linked to the HUC system, such
that when a HUC code is selected, the ground water data associated with the selected HUC code
is also displayed. Two options for developing the ground water quality data layer are suggested
here.
One possible option is to use existing digitized maps. One such map is the Nationwide
Map of Principal Aquifers, developed by the USGS. This map depicts the shallowest principal
aquifers in the United States and can provide a solid basis for spatial displays of ground water
quality data. This option requires that map scales and projections used by the USGS be
correlated to those used in the HUC system.
A second possible option is to use the units reported by States in their 305(b) State Water
Quality Reports. Ground water quality data reported by States under the 305(b) program are
directly correlated to the reporting unit. Although map scales and projections used by the States
will need to be correlated to those used in the HUC system, reported ground water quality data
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Section 4.0
1996 305(b) Data Set
are directly linked to the reporting unit, thus requiring little interpretation and reducing the
potential for error. For example, States most frequently identified the location of their reporting
units in 1996 by providing a paper map in conjunction with a written description of the unit. The
use of these maps infers that the boundaries of the aquifers within the State have been mapped
and that the ground water monitoring data have been reviewed and assimilated to conform to the
mapped boundaries. Maps, along with the corresponding data, could be digitized to form a
ground water layer and used in a GIS format. Using state-supplied information, an example is
provided to better illustrate the development of an IWI ground water layer using this option.
Idaho currently uses a GIS dataset and displays the data spatially. The State of Idaho
supplied coverages in the form of hydrogeologic subareas, major aquifer flow systems, and
statewide monitoring well locations. Each of these coverages is presented in Figures 1 through 3.
Nitrate concentrations measured in 1995 and 1996 in monitoring wells comprising the
State monitoring network were also supplied by Idaho. The concentration measured in each of
the wells is presented graphically in Figure 4. This same information was then summarized in
Figure 5 according to the number of wellsJn an aquifer having a certain percentage of nitrate
concentrations exceeding background levels. The USGS HUC system was superimposed on the
data presented in Figure 5 to illustrate how an aquifer flow system could be displayed within the
HUC system (Figure 6).
As shown, it is possible to develop a ground water layer on a State-by-State basis given
that the individual States can provide aquifer coverages and data in a GIS format. If such an
approach were taken, it would be necessary to make inquiries to determine how many States are
using GIS-based systems in their ground water management efforts and to obtain those coverages
to display data in the IWI format. Cooperation between EPA and the States in construction of
each ground water quality layer would provide the highest degree of accuracy and precision.
4.2 National Coverage
Reporting ground water quality data on an aquifer-specific basis was new to the 305(b)
program in 1996. To ease the reporting burden, EPA purposely developed the Guidelines with
sufficient flexibility to encourage all States to respond. Although it was thought important that
the first few 305(b) reporting cycles following release of the new Guidelines be characterized by
a great deal of flexibility, that same flexibility resulted in wide variations in reported data.
Variations were noted in the diversity of the reporting units and the extent of State coverage.
Thirty-three States reported data summarizing ground water quality. Of these 33 States,
16 States reported data for specific or differentiated hydrogeologic units. Figure 7 presents an '
overview of the states that were able to provide ground water quality data for specific or
differentiated hydrogeologic units within the State.
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State of Idaho
Hydrogeologic Subareas
Ground Water QuaMtjMmitormg Data
Compiled & Providedby:
Idaho Division of Emdronaieatal Quality
Idaho Department of Water Resources
USGS
Scale: 1 iach equals 50 sniles
^^s^^Srfft.- f^~' ^^••^^7f--;--^^fM&'S»^^<^^K-'--^^iSSS^^s:^ - .- • ^~*~ ^~'*
. T^l-*^T^S
1 ^iiiiraS^ " f;iS;S;
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State of Idaho
Hydrogeologic Subarea
and Major Aquifers
Legend
I I Hydrogeologic Sub areas
Major Aquifers
Ground Water Quality Monitoring Data
Compiled & Provided by:
Idaho Dwisaon of Emoroitttte
Idaho Department of Water Reas'orces
USGS
Scale: 1 incK eq-oals 50 miles
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- ,* X?
^**& " '^ r rf"^^ 4^ ^M
State of Idaho
Statewide
Monitoring Network
Legend
Hydrogeologic Subareas
Major Aquifers
Ground "Water Quality
Monitoring Well Locations
GstmEd Water Qualit^Moaiiomg Data
Compled & Pic'vMedby:
Idaio Divisibiiof EavijoiimeJilal Quality
Department of Water Kescmiees
USGS
Scate: 1 inclt equals 50 miles
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State of Idaho
Nitrate Concentrations
Statewide Monitoring
Network 1995 & 1996
Legend
Hydrogeologic Subareas
Major Aquifers
® > 10
© 5 -10 Wei Location &
2-5 Concentrations in mg/1
<2
Gxomd Water Qnalii^Momtoriiig Data
Compiled & Pamded'by:
idato Divisioa of Eavizonmeaslal QuaEiy
Idaho DepartmeBt of Water Resomces
USGS
Scale: 1 inch equals 50 milss
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~ _ <.
State of IaHo
Nitrate by Aquifer
Legend
Hydrogeologic Sub areas
0 - 25% Percentage of sites
trate
1995 & 1996
* Nitrate > 10mg/l
Grouzd. Water QualftyMooitori^ Data
Compiled & Piovidedb^:
Idaho
Idako Department of Water Resources
uses
Scale: 1 incli eqiiais 50 jai
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State of Idaho
Nitrate by Aquifer
with HUC's
Legend
/\/ Hydrogeologic Subareas
/\/ HUC Boundaries
I I 0 -25% Percentage of sites
o^ <:rjo/ tested where nitrate
§9 2V 50/° exceeded 2 mg^l
> 50 % j 995 & 199,5
» Nitrate > 10 mg/1
GKjTmdWaterQtjaMtsrMjmteuiBg Data
Compifed & Provided b3?:
Idaiso DBd^KofEffiriiDKmeniaiQ'aaJiij
Iddao Deparfeteat of Water Reso-oxces
USGS
Scate: 1 mcKequals 50 miles
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Section 4.0
1996 3Q5(b) Data Set
Figure 7. Overview of Reporting Units
DC
•o Virgin Islands
Puerto Rico
.Hawaii
American Samoa
1996 305(b) Ground Water Report Not Provided
Differentiated Into Hydrogeologic Units Within the State
Not Differentiated, Reported on a Statewide Basis
Tabulated Ground Water Monitoring Data Not Provided
Hydrogeologic units were defined by the individual State ground water management
programs and included aquifers, hydrogeologic subareas, ground water basins, monitoring areas,
counties, and watersheds. Although the reporting units used by States to organize and manage
ground water quality data vary across the Nation, it is not expected that this would create a
problem in the development of a ground water layer to support the IWI Initiative because the
individual units would not be displayed, but would rather underlie the HUC system.
In addition to variations in the reporting units, Statewide coverages were not achieved in
the 1996 305(b) reporting cycle. The concept of reporting information for specific aquifers
within a State was new in 1996. To ease the State burden, EPA recommended that ground water
quality be assessed incrementally. As a consequence, State-wide coverages were the exception
rather than the norm for the 1996 data set. Most frequently, coverages ranged from specific
monitoring areas of local interest to a small percentage of the State. EPA recognized this would
be the case and welcomed the reporting of more specific information on a larger scale as opposed
to the reporting of general information on a statewide basis as had been done in past 305(b)
reporting cycles.
The lack of Statewide coverages presents a challenge in developing National coverage
using the 1996 305(b) dataset. Ground water quality cannot be inferred on a National basis from
the limited data reported for specific aquifers or hydrogeologic settings in 1996. Portions of the
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Section 4.0
1996 305(b) Data Set
•State for which no data are reported would have to be identified as "having insufficient data to
make an assessment." This procedure is consistent with the methodology already employed to
depict surface water indicators for IWI. The visual identification of areas within a State having
insufficient data to develop a ground water layer may be useful in developing plans for future
monitoring efforts. Implementation of these plans would naturally increase State coverage with
each successive 305(b) reporting cycle, thus benefitting both the 305(b) and the IWI programs.
4.3 Data Sources
A single data source to describe ground water quality does not exist, and for purposes of
the 1996 305(b) program, States were encouraged to use available data that best reflect the
quality of the ground water resource. The exact source(s) of data used by States to assess ground
water quality in 1996 depended on data availability and the judgment of the ground water
professionals. Ambient water quality data from dedicated monitoring wells or networks were the
preferred source of data. However, in the absence of dedicated ground water monitoring wells or
networks, States resorted to using data collected from public water supply systems (PWSs) as
these data are routinely collected under the Safe Drinking Water Act (SDWA) and would not
necessitate a separate and unique monitoring effort.
Analysis of the 1996 data reported by States revealed that a variety of data sources were
used to assess ground water quality. Although there was a strong reliance on finished water
quality data from PWSs, these data were frequently reported in conjunction with other sources of
data. Figure 8 illustrates the variety in reported data.
Figures. Sources of Ground Water Data
O American Samoa
A Finished Water from PWS Wells
• Untreated Water from PWS Wells
• Ambient Monitoring Networks
<• Other Ground Water Monitoring Data
• Untreated Water from Private or Unregulated Wells
* Special Studies
T Facility Monitoring Wells
H 1996 305(b) Ground Water Report Not Provided
•• Tabulated Ground Water Monitoring Data Not Provided
4-10
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Section 4.0
1996 305fb) Data Set
Given the variety of data sources, ground water quality data most closely approximating
actual ground water conditions (i.e., untreated ground water) were given special consideration in
the 7996 Report to Congress. It is assumed that these same data types would be favored in
producing a ground water layer for the IWI Initiative.
Ten States reported ambient monitoring data for selected aquifers or hydrogeologic
settings in 1996. Admittedly, data from ten States is not sufficient to develop a National ground
water layer. However, it is expected that the number of States reporting ambient monitoring data
for selected aquifers/hydrogeologic settings will increase with each successive 305(b) cycle.
The primary basis for assessing ground water quality in the 305(b) program is the
comparison of chemical concentrations measured in ground water to water quality standards.
Because it was not possible for States to sample and analyze ground water for every known
constituent, EPA suggested that ground water quality data be summarized into parameter groups:
volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). In addition
to these two parameter groups, nitrate was given special consideration in the 1996 Ground Water
Guidelines. These two groups and nitrate were suggested as they are generally indicative of
contamination originating as a result of human activities, and thus, provide excellent indicators
of ground water degradation. It is probable that any ground water layer developed for IWI would
likely use similar indicators.
Using available data sources, States provided a wealth of data for volatile organic
compounds (VOCs), semi-volatile organic compounds (SVOCs), and nitrate. In addition to these
three categories, States also reported data for pesticides and metals (both of which are indicators
of anthropogenic impacts). For 1996, States reported the number of wells for which a parameter
or parameter group was "not detected at or above the MDL," "exceeded the MDL but was less
than the MCL" or "exceeded the MCL." This type of data provides a excellent measure of the
condition of the aquifer and again is analogous to several existing IWI indicators (e.g., Ambient
Water Quality Data — Four Toxic Pollutants).
Data reported in 1996 is representative of the type of data needed to develop an IWI
ground water layer. It is both well suited and relevant to evaluating the condition of our Nation's
ground water resources. Still, the fact remains that national coverage was not attained in 1996.
Furthermore, although nitrate data was reported by 32 States, only 15 States reported nitrate data
for ambient monitoring networks. The same holds true for VOCs, SVOCs, pesticides, and
metals.
4.4 Conclusions Regarding the Use of the 1996 305(b) Data Set
The data elements currently requested under the existing 305(b) program are well suited
to provide the necessary information to characterize ground water condition and vulnerability on
a National basis. However, the ground water quality data reported by States in 1996 are too
sparse to be used for this purpose at this time. Still, a framework for reporting ambient ground
water quality data on a biennial basis has been developed under the 305(b) program, and it is
expected that the amount of data reported will increase with each successive 305(b) cycle as the
direction and focus of the program become clearer to both States and EPA. Thus, with additional
4-11
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Section 4.0
1996 305(b) Data Set
305(5) reporting cycles, the data set will achieve the maturity needed to support the IWI
Initiative.
4-12
-------
Section 5.0
Potential Alternatives
5.0 Potential Alternatives
i
Given the present immaturity of the 1996 305(b) ground water data set, the possibility of
using alternative data sources was explored. One data source that was considered was the
Federal Safe Drinking Water Information System (SDWIS/FED).
Under the SDWA, EPA is responsible for regulating more than 170,000 distinct public
water supply systems and the water they supply. In order to best manage these water systems and
their widely different local conditions, the majority of States supervise water systems within their
borders. To do this, States and the systems test for and monitor contaminants in the finished
(treated) water of each water system. The monitoring data are compiled into State computer
systems and a copy of these data is then downloaded to SDWIS/FED on a quarterly basis.
SDWIS/FED contains a wealth of information related to PWS systems and their
compliance with drinking water standards. A series of queries were designed to evaluate whether
SDWIS/FED could be used to develop a ground water layer for the IWI Initiative. Specific
queries included:
1 How many States report to SDWIS/FED
• Are ground water data included in the SDWIS/FED database
• If ground water data are included, are samples analyzed prior to treatment
• Are sample data linked to location
• Are sample data linked to aquifer systems or watersheds.
All States and Territories report data to SDWIS/FED. Sixty-six entities have water
systems data reported in SDWIS/FED. The population of individuals served by water systems in
SDWIS/FED is high and accounts for a large portion of the population of the United States.
Ground water data are included in the SDWIS/FED database. However, this would be
indicated as a source whether it is from a surface water source or a ground water source as "water
type." In addition, it would be difficult to definitively determine whether a sample received
treatment prior to analysis because this type of information is not currently requested under
SDWIS/FED. Revised reporting requirements for treatment data, however, require that the PWS
report a fuller description of treatment practices, and location of sample in relation to the
treatment. Hence, it is likely that this type of information may be available in the future.
Other ground water information necessary for collection of source data are linked to
location. Although States are capable of linking ground water sample results to location, at the
Headquarters level, SDWIS/FED does not require this level of detail. Still, the option exists and
States may provide this information. Furthermore, there is an attribute in SDWIS/FED of the
HUC code, but few States have populated this data element. The latitude and longitude
coordinates are another way to get this locational information, but again, many systems do not
5-1
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Section 5.0
Potential Alternatives
have the locational coordinates input to SDWIS/FED. This condition will greatly improve with
the revised inventory reporting requirements issued in July 1998.
In conclusion, SDWIS/FED consists of a framework that States use to report data related
to PWS systems and their compliance with drinking water standards. SDWIS/FED contains a
wealth of data reported by States and Territories in the Nation, thereby achieving National
coverage. However, the use of this data to develop a National ground water layer for the IWI
Initiative is questionable primarily due to the difficulties associated with determining "water
type," "treatment," and location to aquifers/watersheds.
5-2
-------
Section 6.0
Conclusions
6.0 Conclusions
The condition of our Nation's ground water resources is monitored and assessed under
Section 106(e) of the Clean Water Act (CWA), which requests that each State monitor ground
water quality and report the findings to Congress in their biennial 305(b) State Water Quality
Reports. Data reported by States are used to assess the quality of our Nation's ground water
resources. Assessment of ground water quality on a National basis is congruent with the
objectives defined under the IWI Initiative.
Recognizing the overlap in data needs between the 305(b) program and the IWI Initiative,
ground water quality data collected under the 305(b) program were assessed to determine their
appropriateness for use in developing an IWI GIS layer characterizing ground water vulnerability
and/or condition. In addition to assessing the data collected under the 305(b) program,
alternative sources of data were evaluated for this same purpose. Following are the conclusions
of this assessment.
• IWI indicators representing both ground water vulnerability and condition can be
developed using the data elements currently requested in the 1996 Ground Water
Guidelines. Specifically, the data elements are appropriate relative to IWI objectives,
uniformly available across the Nation, and can be depicted in a GIS format of an
appropriate scale. Little-to-no modifications of the 1996 Guidelines would be required.
• Data elements used to describe aquifer vulnerability and ground water condition have
been defined under the 305(b) program. Data reported by States in their 1996 305(b)
Water Quality Reports have been compiled into a database, establishing a functional
framework for reporting, compiling, and managing ambient ground water data on a
National basis.
• Although the data elements currently requested under the existing 305(b) program are
well suited to characterize ground water condition and vulnerability on a National basis,
the data reported by States in 1996 is too sparse to be used for this purpose at this time.
Still, a framework for reporting ambient ground water quality data on a biennial basis has
been developed under the 305(b) program, and it is expected that data density will
increase with each successive 305(b) cycle. Thus, with additional 305(b) reporting
cycles, the data set will achieve the maturity needed to support the IWI Initiative.
• SDWIS/FED consists of a framework that States use to report data related to PWS
systems and their compliance with drinking water standards. SDWIS/FED contains a
wealth of data reported by States and Territories in the Nation, thereby achieving National
coverage. However, the use of this data to develop a National ground water layer for the
IWI Initiative is questionable primarily due to the difficulties associated with determining
"water type," "treatment," and location to aquifers/watersheds.
6-1
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September 15,1998
Relationship of State Source Water Assessment
and Protection Program Guidance
to 305(b) Process
-------
-------
Table of Contents
1.0 Introduction 1-1
2.0 Source Water Assessment Program 2-1
2-1 State Source Water Assessment and Protection Programs Guidance 2-1
3.0 Clean Water Act, National Water Quality Inventory Program 305(b) 3-1
3.1 Drinking Water 3-1
3.2 Ground Water .' 3-3
4.0 Use of 305(b) Data for SWAPs 4-1
4.1 Drinking Water 4-1
4.2 Groundwater 4-2
5.0 Other EPA Programs That May Be of Use for SWAPs 5-1
6.0 Summary 6-1
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-------
Section 1.0
Introduction
1.0 Introduction
This report examines EPA's guidance for the Source Water Assessment Program
(SWAP), under the 1996 Safe Drinking Water Act Amendments, and discusses its relationship
with EPA's Clean Water Act's Section 305(b) program. The purpose of this report is to examine
whether data being collected for the 305(b) program may be useful for States in preparing
SWAPs.
1-1
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-------
Section 2.0
Source Water Assessment Program
2.0 Source Water Assessment Program
The Safe Drinking Water Act Amendments of 1996 emphasize pollution prevention to
ensure safe drinking water, focusing on the protection of water sources. Section 1453 of the Safe
Drinking Water Act Amendments requires that all States establish SWAPs which will
• set forth the State's strategic approach to conducting assessments
• delineate the boundaries of areas providing source waters for public water supplies
• identify, to the extent practical, the origins of regulated and certain unregulated
contaminants in the delineated area to determine susceptibility of public water supplies to
such contaminants.
States with Public Water Supply Supervision program primacy must submit SWAPs to
EPA for approval no later than February, 1999. A State program is automatically approved 9
months after submittal to EPA unless EPA disapproves the program. The States have up to two
years after EPA program approval, or with an approved time extension, up to no more than three
and one half years, to complete the source water assessments. This timetable means that most
States will be submitting data from the SWAPs beginning in the year 2001.
EPA has set two goals under the Government Performance and Results Act (GPRA) that
emphasize pollution prevention strategies in the office of Ground Water and Drinking Water. By
the year 2005, the following goals to protect drinking water sources are to be met:
(1) Sixty percent of the population served by community water systems will
receive their water from systems with source water protection programs in place
under both wellhead protection and watershed protection programs.
(2) Increase by 50 percent the waters that meet the drinking water use that States
designate under the Clean Water Act [305(b)] Report to Congress.
2.1 State Source Water Assessment And Protection Programs Guidance
EPA published the "State Source Water Assessment and Protection Programs Guidance"
in August 1997 to help States develop SWAP submittals. This guidance describes the required
content of a SWAP submittal, federal funds available for completion of the assessments,
requirements of public participation, and linkages to other federal programs.
The guidance states that one of the first steps in any SWAP needs to be a review of
relevant, available sources of existing data (including susceptibility determinations) at the
Federal, State, and Local levels. Furthermore, States are encouraged to assemble, review, and use
appropriate information from existing sources of information.
2-1
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Section 2.0
Source Water Assessment Program
In order to gain EPA approval of its SWAP program, States need to include in their
submittal:
• A description of the level of exactness and detail that each assessment will achieve once
it is considered by the State to have been completed. A "completed" assessment for a
public water supply must include:
A delineation of the source water protection area
A contamination source inventory for that source water protection area, and
A determination of the public water supply's susceptibility to contamination by
sources inventoried within the source water protection area.
• A description of how each assessment will protect and benefit the public water systems in
the State.
The guidance does not outline a specific approach for State preparation of SWAPs. It
presents guidelines for delineation of source water protection areas for ground water and surface
water systems, addresses what contaminants should be considered of concern, and discusses
approaches for determining which types of sources of contamination are significant.
In regard to the requirement that the assessment will be "for the protection and benefit of
the public water systems" in the State, the guidance states that this description needs to include
the linkage of the SWAP to ongoing or future source water protection effects, and how a SWAP
will link with existing programs such as the Wellhead Protection Program.
2-2
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Section 3.0
Clean Water Act, National Water Quality Inventory ProgramI305(b)J
3.0 Clean Water Act, National Water Quality
Inventory Program [305(b)]
The Clean Water Act, Section 305(b) specifies that States develop and report information
concerning the quality of the nation's water resources to EPA and the U.S. Congress. Each State
must develop a program to monitor the quality of its ground and surface waters and prepare a
report every two years describing the status of water quality. The States assess their water quality
and its ability to meet various designated uses, including supporting aquatic life, fish
consumption, shellfishing, swimming, and drinking water.
3.1 Drinking Water
EPA developed guidelines for use in assessing drinking water use support as part of the
1996 305(b) reporting cycle. Specifically, States were asked to use ambient water quality data,
finished water quality data, and drinking water use restrictions to assess use support for each
waterbody. The guidelines for drinking water use support for the 1998 305(b) cycle were revised
in order to provide more flexibility to the States. These guidelines emphasize that States may
consider prioritizing their water resources and performing drinking water use support
assessments for a limited percentage of their water resources. States are then encouraged to
expand their drinking water assessment efforts to include additional waters each subsequent
reporting cycle.
Limited drinking water data were provided by the States in the 1996 305(b) reporting
cycle. The States rarely addressed the considerations from the guidelines (see above). When most
States addressed one of these issues, it was very brief and did not present enough detail to be
meaningful. For most States, it was not possible to determine their data sources, data quality, and
the linkage of the data to its source area.
However, several States provided much more detail on drinking water in the 1998 305(b)
cycle. A review of the 1998 305(b) reports that have currently been received (ten States or
territories) showed
• Three States had separate drinking water sections providing detailed information on
monitoring results and their criteria for classification of drinking water use
• Three States did not have a separate drinking water section, but discussed drinking water
as a designated use
• Four States did not discuss drinking water in their reports.
3-1
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Section 3.0
Clean Water Act, National Water Quality Inventory Program[305(b)]
The following summarizes the key information provided by the three States with separate
drinking water sections:
• ARKANSAS: Arkansas presented data on analysis from 133 ambient water quality
sampling stations. Elevated levels of some pesticides were found, but none exceeded the
maximum contaminant levels (MCLs). The three pesticides with the highest occurrences
above the detection level were atrazine, metolachlor, and molinate. None of these levels
exceeded the MCLs. Monthly data for nitrate and minerals (chlorides, sulfates, total
dissolved solids) were compared to the MCLs. Of more than 8,500 miles assessed for
drinking water use support, 77.7 miles were not meeting the use and there was concern
for an additional 38.1 miles. Many of the exceedances were from nitrate values greater
than 10 mg/L.
• HAWAII: Hawaii summarized the length of streams used for drinking water and
presented the list of contaminants being monitored: all current MCLs including
bacteriological, organics, inorganics, and pesticides. All streams were found to be fully
supporting drinking water use, but did not present the monitoring results. A summary
table was provided and reported the lengths of streams (in miles) used for drinking water
and it was noted that all streams are considered fully supporting drinking water use.
• MASSACHUSETTS: Massachusetts provided a very detailed drinking water section. Of
231 public water sources (groundwater) closed, 136 were contaminated by volatile
organic chemicals (VOCs), 63 by inorganics, synthetic organic chemicals (SOCs) or
natural causes, and 18 by two or more chemicals. Fifteen sources reported nitrate
detections above the MCL, several had problems with lead and copper action levels, and
several had sodium above Massachusett's recommended guideline level. For
surfacewater, 96% were in full compliance, 28% had non-trihalomethane VOC detects,
and two were threatened by nitrates. Massachusett's criteria for drinking water use are as
follows: full support is monitoring samples that do not exceed the MCL, threatened is
monitoring samples equal to or greater than one-half the MCL, non-support is samples
that exceed the MCL. Annual average levels were not considered. These criteria are very
similar to EPA's criteria for drinking water use; the major difference is that
Massachusetts used one-half the MCL as the criteria to designate "threatened", while
EPA did not specify one-half the MCL or any other level. EPA considered water to be
threatened when contaminants are detected but do not exceed water quality criteria.
Massachusetts also presented information on its Comprehensive Source Water Protection
Program. In 1995, Massachusetts became the first State in the country to receive EPA's
endorsement of this program; a comprehensive, integrated approach to water supply
protection for both ground and surface water sources using a coordinating role of the
Water Resources Commission and Geographic Information System (GIS) mapping of
priority resource areas. Also in 1995, Massachusetts became the fifth State in the country
to receive EPA's endorsement of its Comprehensive State Ground Water Protection
Program which includes locating the recharge area of all sources and establishing water
supply protection areas.
3-2
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Section 3.0
Clean Water Act, National Water Quality Inventory Program!305(1))]
3.2 Groundwater
EPA also developed new guidelines for use in assessing ground water quality as part of
the 1996 305(b) reporting cycle. The new guidelines changed the focus from the qualitative
generalization of ground water quality on a statewide basis to the quantitative assessment of
ground water quality on an aquifer-specific basis. It is this change in focus that makes ground
water information reported under the 305(b) program suitable for use in supporting the SWAPs.
The 7995 Ground Water Guidelines introduced the concept of reporting ground water
information on an aquifer-specific basis using two table formats developed to assess aquifer
vulnerability and condition. In one of the two table formats (Table 1), States are asked to report
on the type and number of contamination sites per aquifer or hydrogeologic setting having the
potential to adversely impact ground water quality. Specifically, States are asked to identify the
type and number of contaminant source(s) present in the reporting area (e.g., NPL, LUST,
RCRA, Superfund), the number of sites that are listed or have confirmed releases, and the
number of sites with confirmed ground water contamination.
The data reported in Table 1 support the first two steps of a complete source water
assessment: (1) delineation of the source water protection area; and (2) inventorying of the
significant potential sources of contamination within the source water protection area. The third
step, understanding the susceptibility of the source waters to contamination, represents an
analysis of steps one and two. An analysis of the data was not requested in Table 1 of the 7995
Ground Water Guidelines.
Reporting contaminant source information for specific aquifers was new to States in
1996. However, 29 out of the 33 States that submitted ground water assessments in accordance
with the new Ground Water Guidelines provided this information in 1996. Twelve out of 14
States provided this information as part of the 1998 305(b) reporting cycle. Although States
were not required to focus on ground water resources used for drinking water purposes, the
importance of ground water as a drinking water source was evident in the aquifers States selected
for assessment.
Hence, as part of the 305(b) program, States have begun the process of delineating ground
water aquifers and inventorying potential sources of contamination within the aquifer area. This
same information supports SWAPs.
3-3
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-------
Section 4.0
Use o/305(b) Data for SWAPs
4.0 Use of 305(b) Data for SWAPs
4.1 Drinking Water
The drinking water data provided by the above States may be useful for preparing
SWAPs. The monitoring data provided by the States could help fulfill the requirements that the
SWAPs include a contamination source inventory for the source water protection area. These
States have provided levels of chemicals detected in public drinking water supplies which are
linked to specific streams or lakes. This information could be used as the basis for determining
the primary sources of contamination in a source area and a determination of the public water
supply's susceptibility to contamination. In addition, the information provided by the State of
Massachusetts on its Source Water Protection Programs could be useful for fulfilling the
requirements for delineation of source water protection areas.
4.2 Groundwater
Data related to ground water vulnerability, as reported under the 305(b) program, will
support the first two steps of a complete source water assessment. Specifically, delineation of the
source water protection area and inventorying of the significant potential sources of
contamination within the source water protection area provide the necessary information for
preparing SWAPs. As evidenced by the positive response of States in the 1996 and 1998 305(b)
reporting cycles, States have already begun the process of compiling and reporting the required
information for selected aquifers and/or hydrogeologic settings within the State. Because the
information requested under these two programs is so complementary in nature, it is likely both
programs will benefit.
4-1
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Section 5.0
Other EPA Programs That May Be of Use for SWAPs
5.0 Other EPA Programs That May Be of Use for
SWAPs
Other EPA programs may be useful for preparing SWAPs. The following is a summary of
the some of the programs that may provide useful information:
• Wellhead Protection Program: A pollution prevention program designed to protect
ground water-based sources of drinking water, under the Safe Drinking Water Act
Amendments of 1986.
> Formal assessments of source water protection areas for ground water have
already been completed under this program.
• Water Quality Standards: EPA has developed water quality criteria levels on individual
pollutants or parameters, or describe conditions of a waterbody that, if met, will generally
protect the designated use of the water. EPA has developed, to date, 103 recommended
aquatic life or wildlife criteria and 191 recommended human health criteria.
> These standards could be used as benchmarks to determine if the water is meeting
its drinking water use, and for establishing the basis for controls on pollutant
discharges or for management actions to ensure that the drinking water use will be
attained.
• Nonpoint Source Program. Clean Water Act, Section 319, specifies that States are to
conduct statewide assessments of their waters to identify those that are either impaired or
threatened because of nonpoint sources and develop management programs.
> The assessments developed for this program may serve as valuable sources of
information about land-based pollution sources which may contribute to the
contamination of drinking water sources.
• Index of Watershed Indicators (IWI): IWT provides a description of the condition and
vulnerability of each of the 2,111 watersheds in the U.S. It is built on 15 different water
resource indicators.
> . IWI uses a drinking water indicator: rivers and lakes supporting State drinking
water designated uses that is based on data provided by the States in the 305(b)
reports.
• National Pollutant Discharge Elimination System (NPDES) Program
> The NPDES program regulates point source discharges to surface waters such as
wetlands, lakes, rivers, and oceans. Point source discharges include wastewater
from industrial processes, effluent from municipal wastewater treatment plants,
5-1
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Section 5.0
Other EPA Programs That May Be of Use for SWAPs
industrial and municipal stormwater, combined sewer overflows, and sanitary
sewer overflows. Permits may contain requirements that would be critical in
identifying the presence and origin of contaminants in a delineated source water
area.
Total Maximum Daily Load Program (TMDL): Clean Water Act, Section 303 (d),
specifies that States are to identify waters that do not meet water quality standards, even
after implementation of nationally required levels of pollution control technology, and to
develop TMDLs for those waters. TMDLs allocate pollutant loadings among pollution
sources in a watershed, and provide a basis for identifying and establishing controls to
reduce both point and nonpoint source pollutant loadings.
> State lists that identify waters needing TMDLs, and TMDLs developed for
specific water bodies, are a useful source of information, providing data about the
sources of pollution and can be used to develop allocation scenarios for pollutant
loadings among pollution sources in a watershed.
5-2
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Section 6.0
Summary
6.0 Summary
The following matrix presents a summary of the SWAP requirements and drinking water
and grouhdwater data available from 305(b) that could be useful for fulfilling these requirements:
SWAP
Requirements:
305(b) drinking
water data
305(b)
groundwater
data
Delineation of
source water
protection area
Not included
X
Contamination
source
inventory
X
, X
Public water
system
susceptibility
X
X
Protection and
benefit of public
water systems
Not included
Not included
In summary, it is evident that the drinking water and groundwater data that is currently
being submitted for 305(b) is valuable information, and should be used in conducting source
water assessments. Furthermore, the 305(b) groundwater data fully complement the first two
steps of a complete source water assessment. The 305(b) drinking water guidelines are constantly
evolving. It may be beneficial to consider revising these guidelines to be more consistent with the
requirements for SWAPs. In time, the two programs could complement each other in a way that
could prove beneficial to both the States and to EPA.
6-1
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September 15,1998
State Drinking Water Data from the
1996 and 1998 305(b) Reports
-------
-------
Table of Contents
1.0 Introduction 1-1
2.0 1996 Drinking Water Guidelines
2.1 Summary of Drinking Water Data Reported by States in 1996
3.0 1998 Drinking Water Guidelines
3.1 Summary of Drinking Water Data Reported by States in 1998
4.0 305(b) Data and the IWI Project
5.0 Conclusions
2-1
2-2
3-1
3-2
4-1
5-1
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Section 1.0
Introduction
1.0 Introduction
The National Water Quality Inventory Report to Congress under the Clean Water Act,
Section 305(b), mandates that States develop and report information concerning the quality of the
nation's water resources to EPA and the U.S. Congress. Each State must develop a program to
monitor the quality of its ground and surface waters and prepare a report every 2 years describing
the status of water quality. The States assess their water quality and its ability to meet various
uses, including supporting aquatic life, fish consumption, shellfishing, swimming, and drinking
water.
EPA prepared Guidelines for the States for the 1996 and 1998 305(b) reporting cycles on
assessing drinking water use support. In this report, RTI examines these Guidelines and the 1996
305(b) reports submitted by 11 States: North Carolina, Vermont, West Virginia, Michigan, New
York, Wyoming, Arkansas, Alabama, Georgia, Delaware, and Arizona (these States were
selected because they tended to report more data on drinking water use than did the other States),
and the data reported to date in the 1998 305(b) reports by 10 States or territories: Arkansas,
Delaware, Guam, Hawaii, Louisiana, Massachusetts, New Hampshire, Northern Marina Islands,
Pennsylvania, and Washington. In addition, RTI discusses the usefulness of the 305(b) data to
support other EPA program office initiatives, such as the Index of Watershed Initiatives (IWI).
1-1
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Section 2.0
1996 Drinking Water Guidelines
2.0 1996 Drinking Water Guidelines
Only a small percentage of river/stream miles and lake/reservoir acres were assessed for
drinking water use in the early 1990s. To counteract this trend, EPA developed guidelines for
States to use in assessing drinking water use support as part of the 1996 305(b) reporting cycle.
The Guidelines provided a framework for performing drinking water assessments that
incorporated the Safe Drinking Water Act (SDWA) reporting requirements and emphasized the
full range of SDWA contaminants. The primary purpose of the Guidelines was to increase the
percentage of miles and acres assessed in each State and to promote a more meaningful
assessment of drinking water use support within the 305(b) program. In the Guidelines, EPA
emphasized the following considerations:
Use of ambient monitoring data or raw intake water quality data
Use of treated water quality data
Drinking water use restrictions imposed on source waters
Data representativeness given spatial and temporal boundaries
Use of the 84 contaminants regulated under the SDWA.
Specifically, States were asked to use ambient water quality data, finished water quality
data, and drinking water use restrictions to assess use support for each waterbody. The
Guidelines provided an assessment framework for drinking water use support, characterizing
drinking water use as
• Fully supporting
• Fully supporting but threatened
• Partially supporting
• Nonsupporting •
• Unassessed.
States were asked to complete a series of tables summarizing drinking water designated
use data. Using Table 7-21 (Summary of Waterbodies Fully Supporting Drinking Water Use),
States were asked to summarize the rivers/streams and lakes/reservoirs that fully supported
drinking water designated use. States used this same table to list the contaminants considered in
the assessment. States summarized the waterbodies that did not fully support drinking water
designated use in Table 7-22 (Summary of Waterbodies Not Fully Supporting Drinking Water
Use). For each waterbody that was fully supporting but threatened, partially supporting, or not
supporting drinking water designated use, States were asked to list the most significant
contaminants contributing to the designation.
2-1
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Section 2.0
1996 Drinking Water Guidelines
Using the information summarized in Tables 7-21 and 7-22, States were asked to provide
the total number of miles (or acres) designated for drinking water use as well as the total miles
(or acres) assessed and calculate the percentage of total miles (or acres) that fully supports, fully
supports but is threatened, partially supports, or does not support drinking water use. States were
asked to summarize the most significant contaminants contributing to each designation (Tables
7-23 and 7-24).
In a separate table (Table 7-3, Individual Uses Support Summary), States were asked to
summarize the same information for all designated uses (e.g., aquatic life, fish consumption,
drinking water, swimming). Table 7-3 did not include information on contaminants contributing
to the designation. In addition, the States were asked to summarize the reasons waterbodies did
not support their designated uses (Table 7-5, Total Sizes of Waters Impaired by Various Cause
Categories).
2.1 Summary of Drinking Water Data Reported by States in 1996
The 1996 Report to Congress included several appendices which summarized drinking
water use support for rivers and streams, lakes, coastal waters, and estuaries for the States,
Tribes, Territories, and/or Commissions. Appendix A, Table A-3e, presents a numerical
summary of the drinking water use support in surveyed rivers and streams. Results are as
follows:
• Fourteen States reported that all of their surveyed rivers and streams fully supported
drinking water use.
• Twenty-four States reported values for two or more of the five categories (fully
supporting, threatened, partially supporting, nonsupporting, and not attainable).
• Thirteen States either did not report the information or reported it in a format that could
not be quantified.
Of the 11 State 305(b) reports examined by RTI, two (Alabama and Michigan) reported
that all of their surveyed rivers and streams were fully supporting of drinking water use; the other
nine States classified their rivers and streams in two or more categories. Michigan did not
provide a reason for classifying all their rivers and streams as being fully supporting. Alabama
reported that
• 98% of community water systems met the turbidity maximum contaminant level (MCL)
• 96% met the trihalomethane MCL
• 100% met inorganic and radiological MCLs.
The information provided by the other nine States varied greatly. However, certain
information was provided by all States. For example, a version of Table 7-3 (Individual Uses
Support Summary) was used by each State to summarize the total number of miles that supports
all designated uses, including drinking water. An example of Table 7-3 follows:
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Section 2.0
1996 Drinking Water Guidelines
Type of
Waterbody
River, streams
(Miles)
Designated Use
Fish, aquatic life and
recreation
Primary contact recreation
Secondary contact recreation
Industrial supply
Public water supply
Fully
supporting
2396.9
1046.9
2505.2
2839.9
295.6
Partially
supporting
35.0
1101.7
334.7
0.0
0.0
Not
supporting
250.0
502.0
0.0
0.0
0.0
Most of the States also provided a version of Table 7-5 (Total Sizes of Waters Impaired
by Various Cause Categories) from the guidelines which summarizes the reasons waterbodies did
not support their designated uses. This table was not broken down by specific use, such as
drinking water and there was no breakdown of specific contaminants. An example of this type of
table follows:
Stressor Category (for Streams)
Metals
Turbidity
Salinity
Pathogens (fecal coliforms)
pH
Low dissolved oxygen
Radiation (gross alpha)
Nutrients
Pesticides
Debris, bottom deposits
Other inorganics
Suspended solids
Miles Impacted
1,963
1,948
1,104
428
385
333 •
161
114
110
106
50
25
No States provided Tables 7-21 through 7-24 from the Guidelines. Only Alabama
explained why they did not provide these tables; they do not usually assess waterbodies for
support of the drinking water use classification.
Only two States provided information on specific contaminants or general categories of
contaminants that were used in the assessment: Wyoming and New York. Wyoming provided a
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Section 2.0
1996 Drinking Water Guidelines
separate table summarizing causes of drinking water use impairment of impacted rivers and
streams as follows:
Unknown toxicity
Pesticides
Priority organics
Metals
Ammonia
Other inorganics
Nutrients
pH
Siltation
Salinity
Flow alterations
Habitat alterations
Pathogens
Radiation
Oil and grease
suspended solids
Filling and draining
Total toxics
Turbidity.
New York did not provide a separate summary table but did provide large tables for every
river basin in the State that summarized the segment type and size, the primary use impaired,
including drinking water, the severity, the primary pollutant, and the primary source. Arizona
provided the same sort of tables for every river basin, but they included information on the
number and type of samples, the standards or criteria exceeded, the range of values, and the'
frequency exceeded. Delaware provided maps for every river basin with detailed information on
water quality assessment, biological monitoring, point sources, nonpoint sources, and percent of
use support per designated use. However, Delaware rarely provided information on drinking
water as a designated use.
Little information was provided by the States explaining how they classified waterbodies
for drinking water use. Vermont was an exception; they explained their classification system for
every use. For drinking water they used the following system:
• Fully supported: No drinking water supply closures or advisories in effect during
reporting period; no treatment necessary beyond "reasonable" levels. '
• Partially supported: One drinking water supply advisory lasting 30 days or less per year,
or problems not requiring closures or advisories but adversely affecting treatment costs
and the quality of treated water, such as taste and odor problems, color, excessive
turbidity, high dissolved solids, and pollutants requiring activated charcoal filters.
• Not supported: One or more drinking water supply advisories lasting more than 30 days
per year, or one or more drinking water supply closures per year.
North Carolina outlined the system they use to determine whether a body of water meets
its intended use, including drinking water. If more than one source of data exists for a stream, the
rating is assigned according to the following hierachy:
• Fish consumption advisories
• Benthic bioclassification/fish community structure
• Chemical/physical data
• Monitored data >5 years old
• Compliance/toxicity data.
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Section 2.0
1996 Drinking Water Guidelines
Several States provided information on the number of MCL violations for public water
systems. West Virginia provided a table with the total number of community public water
systems with MCL violations (for finished/treated ground water) and the population served.
MCL contaminants included
Metals
VOCs, including trichloroethene, tetrachloroethene, and total halomethanes
Pesticides
Nitrates
Bacteria.
Arkansas presented MCL violations for ground water systems with the following MCLs:
Bacteriological
Turbidity :
Organic
Inorganic
Radiochemical
Trihalomethane.
As discussed above, Alabama used their lack of MCL violations to justify their
classification of all rivers and streams meeting the drinking water use classification.
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Section 3.0
1998 Drinking Water Guidelines
3.0 1998 Drinking Water Guidelines
The guidelines for States to use in assessing drinking water use support for the 1998
305(b) cycle were revised in order to provide more flexibility to the States. These guidelines
emphasize that States may consider prioritizing their water resources and performing drinking
water use support assessments for a limited percentage of their water resources. States are then
encouraged to expand their drinking water assessment efforts to include additional waters each
subsequent reporting cycle. The guidelines recommend prioritization based on waters of greatest
drinking water demand, with further prioritization with respect to vulnerability or other State-
priority factors. In addition, the guidelines encourage States to consider using a tiered approach
in the assessment. This tiered approach would accommodate the different types of data currently
available to States and allows for differing levels of assessment. The guidelines encourage States
to use the best available data that reflects the quality of the resource, and does not ask States to
conduct additional monitoring that does not fit in with other State priorities.
The guidelines provide three tables for the States to fill out on drinking water use. Table
4-20 consists of a summary of contaminants used in the assessment, Table 4-21 summarizes the
miles (for lakes and streams): fully supporting drinking water use, fully supporting but threatened
for drinking water use, partially supporting drinking water use, and not supporting drinking water
use, and Table 4-22 is identical to Table 4-21 except it deals with lakes and reservoirs and is
presented in acres, instead of miles.
In addition, the guidelines provide the following assessment framework for determining
the degree of drinking water use support:
Classification
Full support
Full support but
threatened
Partial support
Monitoring Data
Contaminants do not exceed
water quality criteria
Contaminants are detected but
do not exceed water quality
criteria
Contaminants exceed water
quality criteria intermittently
and/or
and/or
and/or
Use Support Restrictions
Drinking water use restrictions
are not in effect
Some drinking water use
restrictions have occurred
and/or the potential for adverse
impacts to source water quality
exists
Drinking water use restrictions
resulted in the need for more
than conventional treatment
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Section 3.0
1998 Drinking Water Guidelines
Classification
Nonsupport
Unassessed
Monitoring Data
Contaminants exceed water
quality criteria consistently
Source water quality has not
been assessed.
and/or
Use Support Restrictions
Drinking water use restrictions
resulted in closures
3.1 Summary of Drinking Water Data Reported by States in 1998
Some States provided much more detail on drinking water use support in the 1998 305(b)
cycle. A review of the 1998 305(b) reports that have currently been received (ten States or
territories) showed
• Three States had separate drinking water sections providing detailed information on
monitoring results and their criteria for classification of drinking water use
• Three States did not have a separate drinking water section but discussed drinking water
as a designated use
• Four States did not discuss drinking water in their reports.
The following summarizes the key information provided by the three States with separate
drinking water sections:
• ARKANSAS: Arkansas presented data on analysis from 133 ambient water quality
sampling stations. Elevated levels of some pesticides were found, but none exceeded the
maximum contaminant levels (MCLs). The three pesticides with the highest occurrences
above the detection level were atrazine, metolachlor, and molinate. Monthly data for
nitrate and minerals (chlorides, sulfates, total dissolved solids) were compared to the
MCLs. Of more than 8500 miles assessed for drinking water use support, 77.7 miles were
not meeting the use and there was concern for an additional 38.1 miles. Many of the
exceedances were from nitrate values greater than 10 mg/L. Arkansas did not prepare
Tables 4-21-23 from the guidance; they did, however, prepare a list of the pesticides for
which they analyzed.
• HAWAII: Hawaii summarized the length of streams used for drinking water and
presented the list of contaminants being monitored: all current MCLs including
bacteriological, organics, inorganics, and pesticides (the same information asked for in
Table 4-20). All streams were found to be fully supporting drinking water use, but Hawaii
did not present the monitoring results. A summary table was provided reporting the
lengths of streams (in miles) used for drinking water and it was noted that all streams are
considered fully supporting drinking water use. They did not prepare Tables 4-21 or 4-22.
• MASSACHUSETTS: Massachusetts provided a very detailed drinking water section.
They did not prepare Table 4-20; however, they did state that they are currently
monitoring for up to 133 contaminants, including the volatile organic compounds
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Section 3.0
1998 Drinking Water Guidelines
(VOCs), inorganic compounds (lOCs), synthetic organic compounds (SOCs),
microbiological contaminants, turbidity, and radionuclides. Of 231 public ground water
sources closed, 136 were contaminated by VOCs, 63 by lOCs, SOCs, or natural causes,
and 18 by two or more chemicals. Fifteen sources reported nitrate detections above the
MCL, several had problems with lead and copper action levels, and several had sodium
above Massachusett's recommended guideline level. For surfacewater, 96% were in full
compliance, 28% had non-trihalomethane VOC detects, and 2 were threatened by nitrates.
The criteria for drinking water use are as follows: full support is monitoring samples that
do not exceed the MCL, threatened is monitoring samples equal to or greater than one-
half the MCL, non-support is samples that exceed the MCL. Annual average levels were
not considered. Massachusetts did not prepare Tables 4-21 or 4-22.
3-3
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Section 4.0
305(b) Data and the IWI Project
4.0 305(b) Data and the IWI Project
The IWT project is a compilation of data that characterizes the overall condition of the
water resources of this country. Characterization is based on the use of 15 indicator parameters
selected to describe whether rivers, streams, lakes, wetlands, and coastal areas are "well" or
"ailing" and whether activities are placing the waters at risk. Seven of the indicators characterize
the condition of the nation's water resources, and eight characterize vulnerability.
There is one indicator which deals with drinking water. It is titled, "Importance of the
Indicators of Source Water Condition for Drinking Water Systems" and uses three surrogate
measures from different data sets to provide a partial picture of the source water condition. The
three indicators used to characterize source water condition are: a) rivers and lakes supporting
State drinking water designated uses, b) two Safe Drinking Water Information System (SDWIS)
surrogate indicators of source water condition, and c) the occurrence of chemicals regulated
under the Safe Drinking Water Act in ambient waters. These indicators are then used to identify
if there is evidence in the watershed of 1) no significant source water impairment, 2) partial
source water impairment, or 3) significant source water impairment.
The first indicator, (rivers and lakes supporting drinking water designated uses) is based
solely on the data provided by the States in the 305(b) reports. Currently, as discussed above, this
assessment is far from comprehensive across the United States. However, as more States report
this information, the IWI will be able to provide a more comprehensive analysis.
The second indicator (SDWIS surrogate indicators) consists of two indicators developed
from SDWIS data: 1) populations served by community water systems that reported one or more
violations of national health-based drinking water standards during 1991-1996 for chemical
contaminants that are source related, and 2) populations served by community water systems that
have treatment in place in 1996 to remove chemical contaminants that are source related.
The third indicator (occurrence of regulated chemicals) uses sampling results in the
STOrage and RETrieval (STORET) national database from both surface water and ground water
for all chemical contaminants regulated under the Safe Drinking Water Act. Observations above
50% of the MCL (1990-1995) were summed for each watershed.
The 305(b) reports have the potential to provide additional information to be useful to
IWI in the future. For example, as more States add information on the causes of water not
meeting drinking water use, this information could be added to IWI as an additional layer
expressing risk for drinking water quality impairment. This information would be helpful in
further characterizing the State of this country's water resources.
4-1
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Section 5.0
Conclusions
5.0 Conclusions
A comparison of the 1996 and 1998 305(b) reports shows an improvement in the amount
and level of detail provided by a number of States concerning drinking water use. The revised
guidelines appear to have been successful in the attempt to encourage more flexibility and
prioritization by the States. It does not appear that major changes are needed to the guidance for
the next 305(b) reporting cycle; the trend appears to be toward States reporting more and better
information in each cycle. Any changes in the guidance should be oriented toward helping those
States who have not yet reported drinking water use data in their 305(b) reports to begin doing
so, perhaps by providing examples of the type of assessments done by a few States who have
reported these data.
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September 15, 1998
The Use of Nitrate as an Indicator
Parameter of Water Quality
-------
-------
Table of Contents
1.0 Introduction 1-1
2.0 Use of Nitrate Within the 305(b) Program 2-1
3.0 Nitrate as an Indicator Parameter 3-1
3.1 Special Studies Involving Nitrate 3-1
3.2 Potential Limitations 3-3
4.0 Conclusions 4-1
5.0 References 5-7
Appendices
Appendix A: Select NAWQA References Appendices-1
Appendix B: Select Water Resources Abstracts Appendices-3
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Section 1.0
Introduction
1.0 Introduction
Obtaining water quality data that are totally appropriate and reliable is problematic. In
response to widespread problems concerning the reliability of water quality databases, an
Intergovernmental Task Force on Monitoring Water Qaulity (TTFM) was formed in 1992. The
purpose of the ITEM was to develop a framework for water quality monitoring and to
recommend environmental indicators of aquatic condition that agencies could use for different
purposes.
In their August 1997 report, the Ground Water Focus Group of the ITFM establishes a
strong framework for developing a monitoring plan for ground-water quality (ITFM, 1997).
Ground-water quality indicators that may be appropriate for monitoring in areas having different
types of land use and sources of contaminants are presented. Nitrate is listed as a potential
indicator of contamination originating from municipal, domestic, commercial, and agricultural
land uses. Specific land uses and sources for nitrate contamination include municipal
sewer/pipeline; municipal and commercial sanitation; irrigation; animal feedlots; and cultivation.
Other potential indicators of ground-water quality are also included in the FTPM report.
Physical parameters, volatile organic compounds, semi-volatile organic compounds, petroleum
hydrocarbon compounds, pesticides, trace metals, biological and inorganic constituents are listed.
Although a broad array of potential indicator parameters exists, their usefulness depends upon
their relevance to the monitoring objectives, analytical methodologies, and land use impacts. In
assessing ground-water quality on a National basis, nitrate meets the objectives of an overall
indicator and has received prominence on both the National and the State levels.
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Section 2.0
Use of Nitrate Within the 305(b) Program
2.0 Use of Nitrate Within the 305(b) Program
Nitrate is well suited for use as a national indicator parameter. Sources of nitrate are
widespread and abundant at the land surface. Nitrate is soluble, relatively persistent, and mobile
in the environment. Its presence in ground-water systems is indicative of anthropogenic
activities and it can be detected at relatively low concentrations through the use of standard,
reliable, and relatively inexpensive analytical methodologies. Thus, the objective of maximizing
the collection of meaningful ground-water quality information while minimizing the cost is met.
Recognizing this, the use of nitrate as a national indicator of ground-water quality was
promoted through the Clean Water Act Section 305(b) program in which States are asked to
monitor and assess the quality of their water resources. As part of this program, EPA developed
a set of guidelines to assist States in reporting ground-water information. In these guidelines,
EPA requested that States assess ground-water .quality for selected aquifers within the State.
Parameters suggested for use in the assessments include volatile organic compounds,
semi-volatile organic compounds, and nitrate. Nitrate was specified due to the existence of
widespread sources, ease of monitoring, relatively inexpensive cost, and environmental mobility.
Ground-water data reported by States for the 1996 and 1998 305(b) cycles clearly shows
that nitrate is already being used by States as an important indicator of ground-water quality and
vulnerability. For example, more data were reported for nitrate for ambient ground-water
monitoring networks than for any other indicator parameter during both 305(b) cycles and States
asked to supply individual ground-water assessments opted to use nitrate in their analyses.
Thirty-three States reported ground-water monitoring data during the 1996 305(b) cycle.
Of these States, 32 provided data for nitrate. More data were reported for nitrate than any other
indicator parameter. States reported nitrate data for ambient ground-water monitoring networks,
untreated and treated samples collected from public water supply systems, untreated water
samples collected from private water supply systems, and special studies. Although the Clean
Water Act Section 305(b) ground-water program does not assign use-support designations,
nitrate was used by States to delimitate ground-water quality in the following categories:
• background ground-water conditions (i.e., nitrate concentrations less than 3 mg/L);
• potentially impacted conditions (i.e., nitrate concentrations ranging from 3 to 5 mg/L);
• marginally impacted conditions (i.e., nitrate concentrations ranging from 5 to 10 mg/L);
and,
• impacted conditions (i.e., nitrate concentrations exceeding the maximum contaminant
level as defined under the Safe Drinking Water Act).
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Section 2.0
Use of Nitrate Within the 305(b) Program
Using nitrate as an indicator of ground-water quality, States reported that they developed
ground-water management strategies and plans.
States continued to use nitrate to report ground-water monitoring data as part of the 1998
305(b) cycle. As of August 1998, a total of 15 States submitted State Water Quality Reports and
12 of the 15 reported monitoring results for nitrate. States reported data for ambient
ground-water monitoring networks, untreated and treated samples collected from public water
supply systems, and untreated water samples collected from private water supply systems. Some
States reported recent monitoring results for the same aquifer systems assessed during the 1996
305(b) cycle (e.g., Idaho, Arkansas). Other States reported monitoring results for new aquifer
systems, thus increasing the number and area of assessed aquifers (e.g., Alabama, Texas).
The predominance of nitrate as an indicator of ground-water quality was further
emphasized during production of the National Water Quality Inventory 1998 Report to Congress,
which relies on 305(b) data reported by States in their State Water Quality Reports. Select States
were contacted and asked to provide ground-water assessments in a geographic information
system (GIS) format. The purpose of this exercise was to highlight examples of State
capabilities and assessment methodologies. As a consequence, assessment parameters were not
specified by EPA, but rather left to the discretion of the individual States. Although assessment
parameters were not specified, it was assumed by EPA that States would likely provide
ground-water assessments using a variety of different analytes (e.g., metals, volatile organic
compounds, pesticides). However, five out of five States opted to provide ground-water
assessments for nitrate, thus emphasizing the importance of nitrate as an indicator parameter on
the State level.
Finally, nitrate was selected for use as an indicator parameter because the Clean Water
Act Section 305(b) program is geared toward developing an accurate representation of our
Nation's ground-water condition. This purpose was congruent with another EPA initiative, the
National Environmental Goals for Water, which selected nitrate as a national indicator of
ground-water quality (EPA, 1996). Data completeness for the national indicator was lacking and
a data source was needed. The 305(b) program had by necessity begun the task of developing a
data base to compile and maintain the large volume of ambient ground-water quality data
reported by States. Thus, a framework for collecting and managing ambient ground-water data
for nitrate on a biennial basis was established and could be used to support EPA's National
Environmental Goals Initiative.
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Section 3.0
Nitrate as an Indicator Parameter
3.0 Nitrate as an Indicator Parameter
Nitrate meets the main requirements for an indicator parameter. Specifically, nitrate is
mobile and persistent in the environment; characterized by widespread and abundant sources at
the land surface; representative of anthropogenic sources of contamination; easily measured by
standard, reliable, and relatively inexpensive analytical methodologies; currently being measured
on national, state, and local scales; and measured data are readily available (e.g., public water
supply system databases). Thus, it is not a coincidence that interest in nitrate as an overall
indicator of ground-water quality evolved over the course of the past decade as interest in
assessing ground-water quality gained momentum.
3.1 Special Studies Involving Nitrate
Nitrate was an important indicator parameter in two national studies of ground-water
quality conducted in the early 1990s. As part of the National Survey of Pesticides in Drinking
Water Wells, EPA sampled approximately 1,300 community water system wells and rural
domestic wells between 1988 and 1990. Samples were analyzed for the presence of
101 pesticides, 25 pesticide degradates, and nitrate. The survey results statistically
represent approximately 94,600 drinking water wells at community water systems and over
10.5 million rural domestic wells throughout the United States.
The second national study incorporating indicator parameters is the U.S. Geological
Survey's (USGS) National Water Quality Assessment (NAWQA) Study that was implemented in
1991. NAWQA was designed to describe the status and trends in the quality of our Nation's
ground water and surface water resources and to provide a sound understanding of the natural
and human factors that affect the quality of these resources. To best accomplish this task, the
USGS sought advice on which contaminants were most important to focus on. There was almost
unanimous agreement that nutrients (i.e., nitrogen and phosphorus) and pesticides were
widespread and longstanding issues of concern. Thus, occurrences of nutrients and pesticides
were selected as the first two issues requiring study by the USGS.
The NAWQA program addresses a broad spectrum of water-quality issues. The National
Synthesis Program aims to synthesize NAWQA results obtained from individual study units
within the United States with information from other programs, agencies, and researchers to
produce regional and national assessments for priority water quality issues. The first topics
addressed by the National Synthesis are pesticides, nutrients, volatile organic compounds, aquatic
biology, and trace elements. The National Synthesis focusing on nutrients aims to understand
how human and natural influences affect the movement of nitrogen and phosphorus through
ground and surface waters. Discussions on these and other water quality topics are published in
periodic summaries of the quality of the Nation's ground and surface water, as the information
becomes available. A listing of currently available reports is provided in Appendix A.
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Section 3.0
Nitrate as an Indicator Parameter
Two data sets are also available from the USGS nutrient study. The data sets are
available online and can be found at http://wwwrvares.er.usgs.gov/nawqa/nutrients/datasets.html.
These datasets include data describing the patterns of risk for nitrate contamination in ground
water and nutrients in ground water and surface water.
In addition to the National studies undertaken by EPA and the USGS, States are
conducting studies to verify the usefulness of nitrate as an indicator parameter of ground-water
condition and vulnerability. One such study was conducted by the State of South Carolina,
which compared nitrate data obtained from public water supply systems to existing databases of
carbon-14 and tritium ground-water quality data. The purpose of the comparison was to
determine if nitrate could be used as a less expensive alternative to the carbon-14 and tritium
indicator parameters. Although the comparison is still in progress, initial results indicate that
nitrate compares favorably and is an excellent indicator of anthropogenic impacts to water
quality. However, because nitrate may be subject to denitrification, the converse cannot be said
(i.e., the absence of nitrate does not implicitly indicate that the ground water aquifer has not been
impacted by anthropogenic activities).
The State of Washington used nitrate to create a ground-water vulnerability map of Puget
Sound Basin. Using logistic regression, the occurrence of elevated nitrate concentrations in
samples from 1,967 public water supply wells was related to natural factors to assess aquifer
susceptibility, and to natural and anthropogenic factors to assess ground-water vulnerability.
Significant factors included well depth, surficial geology, and the percentage of agricultural and
urban land use within a two-mile radius of a well. The vulnerability assessment is used for
planning land use, targeting ground-water monitoring, monitoring changes in risk of nitrate
contamination of ground-water, and evaluating risk from other contaminants. Studies conducted
by the States of South Carolina and Washington are just two such studies among the many that
are currently being undertaken on the State level.
To further evaluate the use of nitrate as an indicator parameter, the Water Resources
Abstract database was searched for references to nitrate in ground-water monitoring studies.
Searches were limited to references published between January 1993 and April 1998. Two
keyword searches were conducted. The first search was conducted using the keywords "nitrate"
and "ground water." A total of 552 references were returned. A second search focused on
"nitrate" and "ground-water quality" and a total of 382 references were returned. Key-phase
searches using "environmental indicator" and "environmental parameter" did not return any
references.
Abstracts for 79 references are contained in Appendix B. Information synthesized from
the abstracts of the 79 references is summarized as follows:
• Many of the studies focusing on assessing the impact of different land use parameters
(e.g., agricultural, animal farming, rural residential, suburban residential) on regional
ground-water quality used nitrate as a measurement of water quality (i.e., nitrate levels in
relation to the maximum contaminant level [MCL]);
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Section 3.0
Nitrate as an Indicator Parameter
• The general theme of most of the papers was the use of nitrate concentrations (often in
comparison to the MCL) and distributions in ground water as a means of studying the
mechanisms and sources of nitrate contamination in ground water;
• Nitrate was only used as a measure of water quality with respect to contaminant sources
containing nitrate or from which nitrate may be derived (mostly fertilizers, animal wastes,
and septic tanks);
• Some of the studies used nitrate in conjunction with other parameters such as pesticides,
bacteria, and trace metals (e.g., lead). However, these parameters were used
independently of each other.
Nitrate was found to be used as an overall indicator of ground-water quality and
concentrations can be related to differences in land-use practices and soil-drainage properties.
Generally, nutrient concentrations are highest in agricultural areas and in areas of well-drained
soils and intensive cultivation. Although other parameters are available for use as possible
indicator parameters (e.g., phosphorus, various trace metals, organic compounds, suspended
sediment, fecal coliform bacteria), nitrate meets the requirements for a general ground-water
quality indicator parameter. The extensive use of nitrate further validates its importance as an
indicator of ground-water quality.
3.2 Potential Limitations
Several limitations to the use of nitrate as a general ground-water indicator parameter
exist. Natural background nitrate concentrations in ground water are generally less than 3 mg/L.
However, elevated concentrations of naturally occurring nitrate may exist locally. Although high
concentrations of naturally occurring nitrate may initially be misleading, competent ground-water
professionals should easily discern the difference between naturally occurring conditions and
actual ground-water contamination problems.
Sources of nitrate occur on the land surface. The risk of ground-water contamination by
nitrate is dependent upon releases to the land surface and the degree to which an aquifer is
vulnerable to nitrate leaching and accumulation. Studies have shown that nitrate contamination
is generally associated with shallow aquifer systems, thereby possibly limiting the use of nitrate
in deep aquifer systems. It is reasonable to assume that the majority of all other potential
indicator parameters would be subject to this same limitation.
Nitrate is subject to reactions reflecting the metabolic activity of bacteria: nitrification
and denitrification. Under aerobic conditions, nitrifying bacteria oxidize ammonium ion to
nitrite, which in turn, is then oxidized to nitrate. Denitrification involves the reduction of nitrate
to nitrogen gas. This process is a form of anaerobic respiration from which denitrifying bacteria
derive oxygen.
Depending upon the conditions of the ground-water system (i.e., aerobic or anaerobic),
nitrate concentrations may be increased or decreased as a result of microbial activity. The degree
to which nitrate concentrations are affected is difficult to quantify. However, these reactions do
not limit the use of nitrate as an indicator parameter. As observed in the South Carolina study,
elevated concentrations of nitrate in ground-water systems can be linked to surface
3-3
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Section 3.0
Nitrate as an Indicator Parameter
contamination. The absence of nitrate, however, does not implicitly imply the absence of surface
contamination.
As shown in the literature review, many of the studies using nitrate as an indicator
parameter are doing so in connection with specific land use concerns (e.g., inorganic fertilizer
applications, animal farming, septic tanks). In a study conducted by the USGS, nitrate was
shown to pose a high risk to ground-water quality in areas having high nitrogen input factors and
high aquifer vulnerability factors (USGS, 1998). The Midwest and parts of western and
northeastern United States were shown to have a high risk of ground-water contamination by
nitrate. Nitrate would especially be a suitable indicator parameter in these areas. However, the
susceptibility of the aquifer decreases in areas having low nitrogen input and low aquifer
vulnerability (e.g., western United States). This does not pose a serious problem because
ground-water professionals indicate that nitrate sources are abundant and ubiquitous throughout
the United States.
Although some limitations to the use of nitrate as an overall indicator of ground-water
quality do exist, none of the limitations pose a serious problem. Furthermore, there are no other
known indicator parameters that would not be similarly affected by these same or other
limitations.
3-4
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Section 4.0
Conclusions
4.0 Conclusions
Nitrate is well suited for use as a national indicator of ground-water quality and
vulnerability. It is evident that nitrate is currently being used for this very purpose on national,
state, and local scales. As an indicator, nitrate meets the necessary requirements that maximize
information while minimizing costs. It is
• mobile and relatively persistent in the environment;
• representative of anthropogenic sources of contamination;
• characterized by widespread and abundant sources at the land surface;
• easily measured by standard, reliable, and relatively inexpensive analytical
methodologies, and
• large accumulations of data on National and State scales are currently being compiled
into databases (NAWQA, CWA 305(b)).
Hence, evidence supports the use of nitrate to assess general ground-water quality and
derive a better understanding of the vulnerability of our Nation's ground water systems.
4-1
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Section 5.0
References
5.0 References
EPA. 1996. Environmental Indicators of Water Quality in the United States. United States
Environmental Protection Agency. Office of Water. EPA 841-R-96-002. June 1996.
UFM. 1997. Conceptual Frameworks for Ground-Water-Quality Monitoring. Ground Water
Focus Group, Intergovernmental Task Force on Monitoring Water Quality. August 1997.
USGS. 1998. A National Look at Nitrate Contamination of Ground-Water. Nolan, B.T.,
B.C. Ruddy, K.J. Hitt, andD.R. Helsel. United States Geological Survey. Water
Condition and Purification Magazine.
5-1
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Appendices
Appendix A: Select NAWQA References
The following reports were prepared by the NAWQA NATIONAL SYNTHESIS
PROJECT:
A National Look at Nitrate Contamination of Ground Water. Bernard T. Nolan, Barbara C.
Ruddy, Kerie J. Hitt, and Dennis R. Helsel. Water Conditioning and Purification, v. 39,
no. 12, pages 76-79. January 1998. This article refines the national risk map presented in
Fact Sheet FS-092-96.
Nitrate in ground waters of the United States—Assessing the risk. Bernard T. Nolan and Barbara
C. Ruddy. United States Geological Survey. Fact Sheet FS-092-96. April 1998. The
map presented in this fact sheet has been refined and is now available in a National Look
at Nitrate Contamination of Groundwater.
Nutrients in the Nation's Waters—Too Much of a Good Thing? David K. Mueller and Dennis R.
Helsel. United States Geological Survey. Circular 1136. http://wwwrvares.er.usgs.gov/
nawqa/CIRC-1136.html.
Nutrients in Ground Water and Surface Water of the United States — a Summary of NAWQA's
Analysis of Data Through 1992. Featured article in National Water Quality Evaluation
Project (NWQEP) Notes. North Carolina State University Water Quality Group
Newsletter. March 1996. Based on United States Geological Survey WRI95-4031.
Nutrients in Ground Water and Surface Water of the United States — a Summary ofNAWQA's
Analysis of Data Through 1992. United States Geological Survey. Water-Resources
Investigations Report 95-4031. Press release August 24, 1995.
Refining 1970's Land-Use Data With 1990 Population Data to Indicate New Residential
Development. Kerie J. Hitt. United States Geological Survey. Water-Resources
Investigations Report 94-4250.
Nonpoint and Point Sources of Nitrogen In Major Watersheds of the United States. Larry J
Puckett. United States Geological Survey. Water-Resources Investigations Report 94-
4001.
The following reports were prepared by the NAWQA STUDY UNITS:
Apalachicola-Chattahoochee-Flint Basin
Hippe, Daniel J., Wangsness, David J., Frick, Elizabeth A., and Garrett, Jerry W. 1994. Are
Farmers Contaminating the Shallow Ground Water! Modified from United States
Geological Survey Investigations Report 94-4183.
Appendices-1
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Appendices
Hippe, Daniel J., Wangsness, David J., Frick, Elizabeth A., and Garrett, Jerry W. 1994.
Suspended Sediment and Agricultural Chemicals in Floodwaters Caused by Tropical
Storm Alberto. Modified from United States Geological Survey Water-Resources
Investigations Report 94-4183.
Wangsness, D.J., Frick, E.A., Buell, G.R., and Devivo, J.C. Effect of the Restricted Use of
Phosphate Detergent and Upgraded Wastewater Treatment Facilities on Water Quality
in the Chattahoochee River near Atlanta, Georgia. Based on United States Geological
Survey Open-File Report 94-99.
Central Columbia Plateau
Greene, K.E., Ebbert, J.C., and Munn, M.D. 1994. Nutrients, Suspended Sediment, and
Pesticides in Streams and Irrigation Systems in the Central Columbia Plateau, in
Washington and Idaho, 1959-1991. United States Geological Survey Water-Resources
Investigations Report 94-4215.
Jones, J.L., and Wagner, RJ. 1995. Ground-water Quality of the Central Columbia Plateau in
Washington and Idaho: Analysis of Available Nutrient and Pesticide Data, 1942-1992.
United States Geological Survey Water-Resources Investigations Report 94-4258.
Ryker, S.J., and Jones, J.L. 1995. Nitrate Concentrations in Ground Water of the Central
Columbia Plateau. United States Geological Survey Open-File Report 95-445. Fact
Sheet.
Georgia-Florida Coastal Plain
Bemdt, M.P. 1994. National Water Quality Assessment Program— Preliminary Assessment of
Nitrate Distribution in Ground Water in the Georgia-florida Coastal Plain Study Unit,
1972-1990. United States Geological Survey Open-File Report 93-478.
Oaksford, E.T. 1994. National Water Quality Assessment Program—Preliminary Results:
Agricultural Chemicals in the Suwannee River Basin, Georgia-florida Coastal Plain
Study Unit. United States Geological Survey Open-File Report 94-103. Water Fact Sheet.
Bemdt, M.P. 1996. Ground-water Quality Assessment of the Georgia-florida Coastal Plain
Study Unit—analysis of Available Information on Nutrients, 1972-1992. United States
Geological Survey Water-Resources Investigations Report 95-4039.
Ozark Plateaus
Davis, J.V., Petersen, J.C., Adamski, J.C., and Freiwald, D.A. 1996. Water-Quality Assessment
of the Ozark Plateaus Study Unit, Arkansas, Kansas, Missouri, and Oklahoma—Analysis
of Information on Nutrients, Suspended Sediment, and Suspended Solids, 1970-1992.
United States Geological Survey Water-Resources Investigations Report 95-4042.
Appendices-2
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Appendices
Appendix B: Select Water Resources Abstracts
Appendices-3
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Record 1 of 79 - Water Resources Abs. 1/93-4/98
TI: Ground water age and nitrate distribution within a glacial aquifer beneath a thick unsaturated
zone.
AU: Johnston,-C.T.; Cook,-P.G.; Frape,-S.K.; Plummer,-L.N.; Busenberg,-E.; Blackport,-R.J.
SO: GROUND-WATER 19980200 vol. 36, no. 1, pp. 171-180
AB: The impact on ground water quality from increasing fertilizer application rates over the past
40 years is evaluated within a glacial aquifer system beneath a thick unsaturated zone. Ground
water ages within the aquifer could not be accurately determined from the measured distribution
of super(3)H and as a result, chlorofluorocarbon (CFC) and super(3)H/ super(3)He dating
techniques were applied. Beneath a 25 m thick unsaturated zone, ground water ages based on
CFC-11 concentrations were greater than super(3)H/ super(3)He ground water ages by 6 to 10
years, due to the time lag associated with the diffusion of CFCs through the unsaturated zone.
Using the corrected CFC-11 and super(3)H/ super(3)He ground water ages and the estimated
travel time of super(3)H within the unsaturated zone, the approximate position of ground water
recharged since the mid-1960s was determined. Nitrate concentrations within post mid-1960s
recharge were generally elevated and near or above the drinking water limit of 10 mg-N/L. In
comparison, pre mid-1960s recharge had nitrate concentrations <2.5 mg-N/L. The elevated NO
sub(3) super(-) concentrations in post mid-1960s recharge are attributed mainly to increasing
fertilizer application rates between 1970 and the mid- to late 1980s. Anaerobic conditions
suitable for denitrification are present within pre mid-1960s recharge indicating that removal of
DO is a slow process taking tens of years. Over the next 10 to 20 years, nitrate concentrations at
municipal'well fields that are currently capturing aerobic ground water recharged near the
mid-1960s are expected to increase because of the higher fertilizer application rates beginning in
the 1970s and 1980s.
AN: 4257230
Record 2 of 79 -Water Resources Abs. 1/93-4/98 •
TI: Effects of fire severity on nitrate mobilization in watersheds subject to chronic atmospheric
deposition.
AU: Riggan,-Ph.J.; Lockwood,-R.N.; Jacks,-P.M.; Colver,-Ch.G.; Weirich,-F.; DeBano,-L.F.;
Brass,-J.A.
SO: ENVIRON.-SCI.-TECHNOL. vol. 28, no. 3, pp. 369-375
AB: Severe fires in chaparral watersheds subject to air pollution from metropolitan Los Angeles
mobilized accumulated nitrogen and caused streamwater to be polluted with nitrate at
concentrations exceeding the Federal Water Quality Standard. Streamwater NO sub(3) superQ
concentrations were elevated during peak flows, the largest of which was a debris flow that
transported NO sub(3) super(-) at concentrations as high as 1.12 mequiv/L. Annual NO sub(3)
super(-) loss from severely burned watersheds, averaging 1.2 kequiv/ha, was 40 times greater
than that from areas that remained unburned. Fires of moderate intensity produced a more
subdued response in stream discharge and soil nitrification and less than one-seventh the NO
sub(3) super(-) loss observed after severe burning. We infer that the combination of atmospheric
deposition with severe wildfires provides a strong and recurrent source of nitrate that could
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contribute to existing groundwater pollution in parts of eastern Los Angeles County. Moderating
the fire regime by prescribed burning could provide substantial mitigation.
AN: 4222380
Record 3 of 79 - Water Resources Abs. 1/93-4/98
TI: Transboundary water resources and public health in the U.S.-Mexico border region.
AU: Varady,-R.G.; Mack,-M.D.
SO: J.-ENVIRON.-HEALTH vol. 57, no. 8, pp. 8-13
AB: The 'Ambos Nogales Water Project1 represents an interdisciplinary study of water
management policy in a community straddling the U.S.-Mexico border. The project was a joint
effort undertaken from 1989 through 1993 by the Udall Center for Studies in Public Policy at the
University of Arizona and El Colegio de la FronteraNorte (COLEF) in Nogales., Sonora.
Funding was provided by the Ford Foundation. Three key water management issues were the
research focus: quantity (water supply), sewerage (water and waste removal), and quality. All
three have inseparable linkages with public health. Regarding quantity, the study revealed that
entire neighborhoods, especially in Nogales, Sonora, are unsupplied or undersupplied with
running water, suggesting negative implications for the health of residents on both sides of the
border. Sewerage systems do not reach many neighborhoods in Nogales, Sonora. Even sewered
areas are problematic due to breaks in poorly maintained systems, resulting in leaks to the aquifer
and threats to groundwater quality. A pilot, water sample survey to assess water quality of area
wells revealed significant bacteriologic contamination due to wastewater, elevated nitrate levels,
and detectable concentrations of volatile organic compounds, all of which have potentially
deleterious health effects. The project database offers an opportunity to analyze
environment-related health problems in Ambos Nogales. The authors were not involved in the
primary water resources research or sampling surveys that are the background of this essay. They
have employed the data generated to discuss previously unaddressed public health aspects of the
work and reviewed some of the project's implications within the larger context of research on
U.S.-Mexico border environmental health. The project itself contributes a model for cooperative,
transboundary research on an important set of factors affecting public health. Project outputs are
particularly valuable given that the newly created North American Development Bank
(NADBank) and its sister institution, the Border Environmental Cooperation Commission
(BECC), have identified water-related problems as their initial priority to improve quality of life
in the border region.
AN: 4222259
Record 4 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrate movement through soil profile and groundwater pollution by nitrogen fertilizer hi
sand dune upland soil.
AU: Nonaka,-M.; Abe,-R.; Kamura,-T.
SO: JAP.-J.-SOIL-SCI.-PLANT-NUTR. 19961200 vol. 67, no. 6, pp. 633-639
AB: The study on relationship between nitrogen fertilizer and accumulated water (precipitation
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and irrigation) and nitrate movement through soil profile on groundwater pollution was carried
out on the experimental field in sandy soil for 1 year. The nitrogen fertilizers were applied to 268
N kg ha super(-l) as chemical fertilizers in autumn radish cropping and 171 N kg ha super(-l) as
organic matters in-summer tobacco cropping. The results were summarized as follows: 1) The
chemical form of leached nitrogen was mostly as nitrate. The nitrate concentration in
groundwater was increased by more than 100 mm accumulated water per month, but was
decreased by below 100 mm accumulated water per month. 2) In the cast of more than 100 mm
accumulated water per month, the maximum peak of nitrate leaching appeared at 3 weeks after
basal application during autumn radish cropping. But, in the drought summer season of 1994, the
nitrate leaching was depressed during summer tabacco cropping.
AN: 4228633
Record 5 of 79.- Water Resources Abs. 1/93-4/98
TI: Predicting the probability of elevated nitrate concentrations in the Puget Sound Basin:
Implications for aquifer susceptibility and vulnerability.
AU: Tesoriero,-A.J.; Voss,-F.D.
SO: GROUND-WATER 19971200 vol. 35, no. 6, pp. 1029-1039
AB: The occurrence and distribution of elevated nitrate concentrations ( greater than or equal to
3 mg/1) in ground water in the Puget Sound Basin, Washington, were determined by examining
existing data from more than 3000 wells. Models that estimate the probability that a well has an
elevated nitrate concentration were constructed by relating the occurrence of elevated nitrate
concentrations to both natural and anthropogenic variables using logistic regression. The
variables that best explain the occurrence of elevated nitrate concentrations were well depth,
surficial geology, and the percentage of urban and agricultural land within a radius of 3.2
kilometers of the well. From these relations, logistic regression models were developed to assess
aquifer susceptibility (relative ease with which contaminants will reach aquifer) and
ground-water vulnerability (relative ease with which contaminants will reach aquifer for a given
set of land-use practices). Both models performed well at predicting the probability of elevated
nitrate concentrations in an independent data set. This approach to assessing aquifer
susceptibility and ground-water vulnerability has the advantages of having both model variables
and coefficient values determined on the basis of existing water quality information and does not
depend on the assignment of variables and weighting factors based on qualitative criteria.
AN: 4228144
Record 6 of 79 - Water Resources Abs. 1/93-4/98
TI: Risk of nitrate in groundwater of the United States - a national perspective.
AU: Nolan,-B.T.; Ruddy,-B.C.; Hitt,-K.J.; Helsel,-D.R.
SO: ENVIRON.-SCI.-TECHNOL. 19970800 vol. 31, no. 8, pp. 2229-2236
AB: Nitrate contamination of groundwater occurs in predictable patterns, based on findings of
the U.S. Geological Survey's (USGS) National Water Quality Assessment (NAWQA) Program.
The NAWQA Program was begun in 1991 to describe the quality of the Nation's water resources,
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using nationally consistent methods. Variables affecting nitrate concentration in ground-water
were grouped as "input" factors (population density and the amount of nitrogen contributed by
fertilizer, manure, and atmospheric sources) and "aquifer vulnerability" factors (soil drainage
characteristic and the ratio of woodland acres to cropland acres in agricultural areas) and
compiled in a national map that shows patterns of risk for nitrate contamination of groundwater.
Areas with high nitrogen input, well-drained soils, and low woodland to cropland ratio have the
highest potential for contamination of shallow groundwater by nitrate. Groundwater nitrate data
collected through 1992 from wells less than 100 ft deep generally verified the risk patterns shown
on the national map. Median nitrate concentration was 0.2 mg/L in wells representing the
low-risk group, and the maximum contaminant level (MCL) was exceeded in 3% of the wells. In
contrast, median nitrate concentration was 4.8 mg/L in wells representing the high-risk group,
and the MCL was exceeded hi 25% of the wells.
AN: 4220944
Record 7 of 79 - Water Resources Abs. 1/93-4/98
H: Atrazine and nitrate transport to the Brazos River floodplain aquifer.
AU: Chakka,-K.B.; Munster,-C.L.
SO: TRANS.-ASAE 19970600 vol. 40, no. 3, pp. 615-621
AB: The potential for contamination of groundwater and surface water from agricultural
chemicals used on river fioodplains is a serious concern in many parts of the United States, An
agricultural research site located near College Station, Texas, was instrumented to determine the
fate of agricultural chemicals typically applied to the Brazos River floodplain. Nine well nests
were installed in a 3x3 grid pattern, parallel and perpendicular to the river. Each well nest has
four monitoring wells screened at various depths throughout the aquifer. Ammonium-nitrate
fertilizer and the herbicide atrazine were applied to this research site at the time a corn crop was
planted in 1994 and 1995. Groundwater and river samples were periodically collected and tested
for nitrate-N, ammonium-N, and atrazine. Increases in nitrate-N in the groundwater were not
observed due to high background concentrations of nitrate-N. Ammonium-N was not detected in
the groundwater above background concentrations (<1 mg/L) due to nitrification of
ammonium-N to nitrate-N hi the clay soil. Atrazine was detected in the groundwater 24 days
after the second application indicating preferential flow through the Ships clay surface layer that
was 6 m thick. A pump test that was conducted at the research site just after the second atrazine
application facilitated the movement of atrazine to a depth of 18 m.
AN: 4219617
Record 8 of 79 - Water Resources Abs. 1/93-4/98
TI: A study of the temporal variability of atrazine in private well water. Part II: Analysis of data.
AU: Pinsky,-P.; Lorber,-M.; Johnson,-K.; Kross,-B.; Burmeister,-L.; Wilkins,-A.; Hallberg,-G.
SO: ENVIRON.-MONIT.-ASSESS. 1997 vol. 47, no. 2, pp. 197-221
AB: In 1988, the Iowa Department of Natural Resources, along with the University of Iowa,
conducted the Statewide Rural Well Water Survey, commonly known as SWRL. A total of 686
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private rural drinking water wells was selected by use of a probability sample and tested for
pesticides and nitrate. A subset of these wells, the 10% repeat wells, were additionally sampled
in October, 1990 and June, 1991. Starting in November, 1991, the University of Iowa, with
sponsorship from the'United States Environmental Protection Agency, revisited the 10% repeat
wells to begin a study of the temporal variability of atrazine and nitrate in wells. Other wells,
which had originally tested positive for atrazine hi SWRL but were not in the 10% population,
were added to the study population. Temporal sampling for a year-long period began in February
of 1992 and concluded in January of 1993. All wells were sampled monthly, a subset was
sampled weekly, and a second subset was sampled for 14 day consecutive periods. Of the 67
wells in the 10% population tested monthly, 7 (10.4%) tested positive for atrazine at least once
during the year, and 3 (4%) were positive each of the 12 months. The average concentration in
the 7 wells was 0.10 mu g/L. For nitrate, 15 (22%) wells in the 10% repeat population monthly
sampling were above the Maximum Contaminant Level of 10 mg/L at least once. This paper, the
second of two papers on this study, describes the analysis of data from the survey. The first paper
(Lorber et al., 1997) reviews the study design, the analytical methodologies, and development of
the data base.
AN: 4215684
Record 9 of 79 - Water Resources Abs. 1/93-4/98
TI: Agricultural land use effects on nitrate concentrations in a mature karst aquifer.
AU: Boyer,-D.G.; Pasquarell,-G.C.
SO: WATER-RESOUR.-BULL. 1996 vol. 32, no. 3, pp. 565-573
AB: The impact on water quality by agricultural activity in karst terrain is an important
consideration for resource management within the Appalachian Region. Karst areas comprise
about 18 percent of the Region's land area. An estimated one-third of the Region's farms, cattle,
and agricultural market value are on karst terrain. Nitrate concentrations were measured hi cave
streams draining two primary land management areas. The first area was pasture serving a beef
cow-calf operation. The second area was a dairy. Nitrate-N concentrations were highest hi cave
streams draining the dairy and a cave stream draining an area of pasture where cattle congregate
for shade and water. The dairy contributed about 60 to 70 percent of the nitrogen load increase in
the study section of the cave system. It was concluded that agriculture was significantly affecting
nitrate concentrations in the karst aquifer. Best management practices may be one way to protect
the ground water resource. (DBO)
AN: 4214529
Record 10 of 79 - Water Resources Abs. 1/93-4/98
TI: Springflow effects on chemical loads in the Snake River, south-central Idaho.
AU: Clark,-G.M.; Ott,-D.S.
SO: WATER-RESOUR.-BULL. 1996 vol. 32, no. 3, pp. 553-563
AB: The 150-kilometer middle reach of the Snake River (middle Snake) in south-central Idaho
receives large quantities of water from springs discharging along the north side of the river from
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the regional Snake River Plain aquifer. Water-quality samples collected from nine north-side
springs in April 1994 indicated that springs in the upstream part of the reach had larger
concentrations of dissolved solids, dissolved nitrate, total nitrogen, tritium, and heavy isotopes of
hydrogen and^oxygen than to springs in the downstream part of the reach. Because the spring
chemistry varies in the reach, discharge from the springs resulted-in a degradation in water
quality in some parts of the middle Snake and improvements in water quality in other parts.
Depending on the annual discharge in the Snake River, the contribution from the north-side
springs represented 33 to 66 percent of the discharge, 32 to 57 percent of the dissolved solids, 26
to 50 percent of the total nitrogen, and 7 to 14 percent of the total phosphorus transported
annually from the middle Snake. Synoptic sampling showed that the north-side springs
contributed 84 percent of the discharge and 35,40, and 10 percent of the dissolved solids, total
nitrogen, and total phosphorus load, respectively, to the Snake River during the peak of the
irrigation season in 1994. (DBO)
AN: 4214528
Record 11 of 79 - Water Resources Abs. 1/93-4/98
TI: The potential risks of giroundwater and surface water contamination by agricultural
chemicals used in vegetable production.
AU: Beach,-E.D.; Fernandez-Cornejo,-J.; Huang,-W.-Y.; Uri,-N.D.
SO:
J.-ENVIRON.-SCL-HEALTH-PART-A-ENVIRON.-SCI.-ENG.-TOXIC-HAZARD.-SUBST-C
ONTROL 1995 vol. A30, no. 6, pp. 1295-1325
AB: This study identifies those agricultural chemicals used in vegetable production in Arizona,
Florida, Michigan, and Texas that are potential contaminants of groundwater and surface water
which, in turn, pose risks to human health. Arizona and Florida are more likely to have nitrate
leaching problems than Michigan or Texas. The potential for pesticide leaching is relatively high
in Arizona head lettuce production and Michigan asparagus production but only moderate in
Florida tomato production and Texas watermelon production. The potential for soil-adsorbed
runoff and solution runoff hi Arizona head lettuce, Florida tomatoes, and Michigan asparagus
production is low to moderate. The potential for these sorts of losses in Texas watermelon
production is relatively high. Vegetable production around Phoenix, Arizona, in southeast Texas,
and in the entire state of Florida is located such that groundwater aquifers which supply drinking
water are vulnerable to contamination.
AN: 4209990
Record 12 of 79 - Water Resources Abs. 1/93-4/98
TI: Assessment of forest management effects on nitrate removal by riparian buffer systems.
AU: Hubbard,-R.K.; Lowrance,-R.
SO: TRANS.-ASAE 1997 vol. 40, no. 2, pp. 383-394
AB: A study was conducted to determine the impact of different forest management techniques
on shallow groundwater quality hi coastal plain riparian zones. Considerable past research had
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shown that riparian zones are effective in removing or assimilating nitrates entering from upslope
agricultural fields via shallow lateral flow, but the impact of different forest management
techniques on this process was unknown. The study was conducted at a site near Tifton, Georgia,
on a second-order coastal plain stream. The riparian buffer system consisted of a grass buffer, a
managed forest zone, and a forest zone adjacent to the stream. Three forest treatments were
studied: mature forest (MF), clearcut (CC), and selective thinning (ST). Following a nine-month
pretreatment period, trees were completely or selectively removed from the CC and ST
treatments, respectively. Shallow groundwater quality was evaluated in networks of wells on
transects extending downslope from the edge of the agricultural field to the stream. Results from
the study showed that all three forest management treatments were effective in assimilating
nitrate-nitrogen (NO sub(3)-N). Significant differences in NO sub(3)-N concentrations in the
shallow groundwater between the three different treatments did not occur. The only statistically
significant effect that was observed on groundwater quality was under the CC treatment, where
solute concentrations (both NO sub(3)-N and chloride [Cl]) decreased after the tree cutting. This
was attributed to a combination of effects including possible increased NO sub(3)-N uptake by
rapidly growing vegetation, dilution associated with less evapotranspiration by young vegetation
as compared to mature forest, and more throughfall of rainfall under the CC than under the other
two treatments. No treatment effects were observed on ammonium-nitrogen (NH sub(4)-N)
concentrations. Overall the study showed that regardless of forest management techniques,
coastal plain riparian forests are effective in assimilating NO sub(3)-N.
AN: 4208139
Record 13 of 79 - Water Resources Abs. 1/93-4/98
TI: Statistical analysis of rural well contamination and effects of well construction.
AU: Glanville,-T.D.; Baker,-J.L.; Newman,-J.K.
SO: TRANS.-ASAE 1997 vol. 40, no. 2, pp. 363-370
AB: A previous statewide survey showed that 14% of rural wells in Iowa contained detectable
concentrations of pesticides. To determine if improved private well construction regulations
should be included in Iowa's State Pesticide Management Plan, a two-year study was undertaken
to determine: the effects of well construction on pesticide, nitrate-nitrogen, and bacterial
contamination of wells; and the possible role of point sources of contamination. Eighty-eight
rural water supply wells in nine Iowa counties were sampled daily for five weeks during late
spring and summer of 1993, and 20% of these were resampled in 1994. Short-term variation in
nitrate-nitrogen concentrations was examined as a possible indicator of rapid inflow of shallow
groundwater associated with well construction defects. Mean total coliform bacteria,
nitrate-nitrogen, chloride, atrazine, alachlor, and metolachlor concentrations were statistically
analyzed to determine if they were correlated, and t-tests also were used to determine if these
water quality parameters were affected significantly by physical well parameters such as depth, •
type of casing, grouting, location within frost pits, and proximity to various potential sources of
contamination. Study results indicate that: short-term water quality fluctuations, by themselves,
were not a reliable indicator of deteriorated or improperly constructed wells; although the
magnitude and frequency of positive total coliform test results was noticeably higher in shallower
wells, a substantial fraction (21%) of wells greater than 30.5 m (100 ft) deep also had positive
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coliform results; t-tests and correlation analysis failed to show significant differences in mean
atrazine or alachlor concentrations when comparing "shallow" and "deep" wells; increased well
depth, by itself did not ensure water supply protection from chemical or biological contaminants;
mean nitrate-nitrogen and mean chloride concentrations had the strongest correlation (R = 0.57, p
= 0.0001) among any of the contaminants tested; and mean atrazine and alachlor concentrations
correlated moderately well with those for the more highly-mobile nitrate-nitrogen and chloride.
AN: 4208136
Record 14 of 79 - Water Resources Abs. 1/93-4/98
Tl: Agricultural chemicals in alluvial aquifers in Missouri after the 1993 flood.
AU: Heimann,-D.C.; Richards,-J.M.; Wilkison,-D.H.
SO: J.-ENVIRON.-QUAL. 1997 vol. 26, no. 2, pp. 361-371
AB: Intense rains produced flooding during the spring and summer of 1993 over much of the
midwestern USA including many agricultural areas of Missouri. Because of potential
contamination from fioodwater, an investigation was conducted to determine the changes in
concentrations of agricultural chemicals in water samples from alluvial wells in Missouri after
the flood. Water samples from 80 alluvial wells with historical data were collected in March,
July, and November 1994, and analyzed for dissolved herbicides, herbicide metabolites, and
nitrate (NO sub(3)). There were no statistically significant differences in the distribution of
alachlor (2,chloro-2'-6'-diethyl-N-[methoxymethyl]-acetanilide), atrazine
(2-chloro-4-ethylamino-6-isopropylamino-l,3,5 triazine), and nitrate concentrations between pre-
and postflood samples ( alpha = 0.05). The detection frequency of alachlor and atrazine in
postflood samples was generally lower than the frequency in preflood samples. Analyses of
agricultural chemicals in water samples from an intensely sampled well field indicate significant
differences between the distribution of dissolved P concentrations in pre- and postflood samples (
alpha = 0.05). However, no significant differences were detected between the pre- and postflood
distributions of NO sub(3) or ammonia concentrations. Because of the numerous sources of
temporal variability and the relatively short record of water-quality data for the study wells, a
cause-and-effect relation between changes in agricultural chemical concentration and a single
factor of the 1993 flood is difficult to determine. Based on the results of this study, the 1993
flood did not cause widespread or long-term significant changes in concentrations of agricultural
chemicals in water from alluvial aquifers in Missouri.
AN: 4113781
Record 15 of 79 - Water Resources Abs. 1/93-4/98
TI: Impact of historical and current farming systems on groundwater nitrate in Northern
Missouri.
AU: Kitchen,-N.R.; Blanchard,-P.E.; Hughes,-D.F.; Lerch,-R.N.
SO: J.-SOIL-WATER-CONSERV. 1997 vol. 52, no. 4, pp. 272-277
AB: A major objective of the Management Systems Evaluation Areas (MSEA) Project has been
to assess farming system impact on NO sub(3)-N concentrations hi shallow aquifers. In Missouri
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our interest was to assess farming systems on the claypan soil/glacial aquifer. Three fields were
selected and instrumented with groundwater wells in the spring of 1991. Wells were sampled
quarterly and analyzed for NO sub(3)-N. Average NO sub(3)-N concentration since 1991 was 7
mg 1 super(-l), but 25% of the wells had NO sub(3)-N in excess of 10 mg 1 super(-l). In one
field, NO sub(3) concentrations were much higher and are still decreasing after apparently
receiving excess nitrogen (N) from manure and N fertilizer before 1980. Long-term N
management has long-term impacts on groundwater quality in this aquifer. Current farming
systems are probably affecting groundwater quality, but, because of the glacial till's apparent
buffer for NO sub(3) storage, groundwater NO sub(3) concentration changes are slow.
AN: 4113201
Record 16 of 79 - Water Resources Abs. 1/93-4/98
TI: Heterogeneities in ground-water geochemistry in a sand aquifer beneath an irrigated field.
AU: Kelly,-W.R.
SO: J.-HYDROL.-AMST. 1997 vol. 198, no. 1-4, pp. 157-176
AB: The contamination of shallow aquifers by elevated nitrate concentrations is a common
problem in many rural regions of the world. Aquifers under irrigated land are especially
susceptible to this type of contamination. An intensive three-dimensional investigation of water
chemistry was undertaken in a shallow unconfined sand aquifer in an area of intensive irrigation
in Mason County, Illinois, in order to investigate processes affecting water quality. Results reveal
considerable heterogeneity in the aqueous chemistry in three spatial dimensions and temporally.
Recharge is rapid in this system and the water chemistry of the recharge water is variable both
spatially and temporally, being especially influenced by agricultural practices. Nitrate
concentrations are elevated in a zone between about 6 and 10 m beneath the surface, although in
certain areas and at certain times this zone was not found. The maximum nitrate concentrations
in this zone were slightly greater than 20 mg 1 super(-l) as N, well above the US Environmental
Protection Agency's maximum contaminant level (MCL) of 10 mg 1 super(-l). Nitrate was
generally absent both above and below this depth in the aquifer. Water relatively depleted in
nitrate recharges the aquifer from the surface at the site, producing a zone of dilute water near the
water table. Beneath the plume, denitrification reactions are responsible for removing nitrate
from solution, probably mainly coupled to oxidation of sulfide minerals; tritium data suggest that
vertical movement of solutes is rapid and thus there has been enough time to transport
surface-applied fertilizer to depths in excess of 30 m in the aquifer. This rapid vertical movement
is almost certainly enhanced by intensive irrigation in the county. A number of aqueous species
and chemical parameters (Ca, Mg, Sr, Fe, Si, dissolved inorganic carbon (DIG), dissolved
oxygen, total dissolved solids, and pH) are correlated with nitrate concentrations, primarily
because, like nitrate, they are either a significant fraction of fertilizers or are redox-sensitive.
Drinking water quality is generally not degraded by fertilizer applications in this area, because
almost all drinking-water wells are screened well below the zone of elevated nitrate
concentrations.
AN: 4108555
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Record 17 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrogen and chloride concentration in deep soil cores related to fertilization.
AU: Salameh-Al-Jamal,-M.; Sammis,-T.W.; Jones,-T.
SO: AGRIC.-WATER-MANAGE. 1997 vol. 34, no. 1, pp. 1-16
AB: Shallow-rooted, high-value vegetable crops are normally heavily fertilized with nitrogen.
Improving farmers' management practices requires a simple method to monitor nitrogen loading
below the root zone, and irrigation efficiency. In fields with low nitrogen and water use
efficiencies, alternative Best Management Practices (BMPs) should be initiated and evaluated to
reduce nitrogen loading to the ground water while maintaining yields. The objective of the study
was to estimate the extent of nitrate-nitrogen leaching below the root zone of shallow-rooted
onions, and deep-rooted chile and alfalfa, using chloride in the irrigation water as a tracer. Soil
samples were taken from seven fields in 15 cm increments to 180 cm at the end of the 1994
growing season. The samples were analyzed for nitrate-nitrogen and chloride. Irrigation
efficiency ranged from 70 to 76% for the chile fields, 77-80% for onions and was 97% for alfalfa.
Nitrogen loading below the root zone of chile fields varied from 290 kg ha-1 per year for sandy
loam soils to 64 kg ha-1 for clay soils. Nitrogen loading below the root zone of onions varied
from 199 kg ha-1 per year for a loamy sand field to 161 kg ha-1 per year for a clay field. The
nitrogen loading below the root zone of a sandy loam alfalfa soil was only 42 kg ha-1 per year
because of the low leaching fraction. Results indicated that irrigation efficiencies are reasonable
but nitrogen applications amounts need to be decreased by using alternative BMPs
AN: 4107169
Record 18 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrogen leaching from forest soil cores after amending organic recycling products and
fertilizers.
AU: Insam,-H.; Merschak,-P.
SO: WASTE-MANAGE.-RES. 1997 vol. 15, no. 3, pp. 277-292
AB: Many alpine forests are severely depleted of nutrients by extensive logging and by grazing
of cattle and wildlife. Fertilization may be a remedy, but nitrate leaching may pose problems for
the groundwater. However, use of slow-release fertilizers may avoid this problem, whilst
improving the Ca, Mg, K, and P status of these soils. Intact soil cores (11 cm diameter, 40 cm
depth) from a mixed forest and a Norway spruce stand in the Northern Calcareous Alps of
Austria were used hi a laboratory experiment to study the effects of adding organic fertilizers and
recycling products on patterns of nitrate and ammonium release. The amended (corresponding to
300 kg N ha super(-l)) and control cores were incubated for 29 weeks at 15 degree C. Soil water
(retrieved 5 cm below the soil surface) and leachate were analysed for nitrate and ammonium in
regular intervals. After the incubation, soil microbial biomass, basal respiration and nitrogen
mineralization were determined. Some of the organic fertilizers, especially those that had
undergone composting processes (compost of organic waste, compost of bark+sewage sludge,
compost of sawdust+sewage sludge, Biovin registered ) and Biosol registered, caused only
minor increases of nitrate and ammonium in the soil water and leachate. Others, like
uncomposted sewage sludge products (Primafert registered and sewage sludge+shale), resulted
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in elevated (up to 150 mg nitrate-N 1 super(-l)) nitrate concentrations in the soil water and in the
leachate. Fertilization with N-rich fertilizers (Biosol registered, Primafert registered , sewage
sludge+shale) resulted in significant decreases in microbial biomass and basal respiration at the
end of the 6-month incubation. Microbial biomass and basal respiration were not affected by the
other organic fertilizers.
AN: 4097633
Record 19 of 79 - Water Resources Abs. 1/93-4/98
TI: The geochemical effects of benzene, toluene, and xylene (BTX) biodegradation.
AU: Kelly,-W.R.; Herman,-J.S.; Mills,-A.L.
SO: APPL.-GEOCHEM. 1997 vol. 12, no. 3, pp. 291-303
Record 20 of 79 - Water Resources Abs. 1/93-4/98
TI: Impact of suburbanization on ground water quality and denitrification in coastal aquifer
sediments.
AU: Aelion,-C.M.; Shaw,-J.N.; Wahl,-M. -
SO: J.-EXP.-MAR.-BIOL.-ECOL. 1997 vol. 213, no. 1, pp. 31-51
AB: The South Carolina coastal plain is currently facing rapid population growth and
suburbanization. Suburbanization brings the potential for surface- and ground water
contamination from the use of nitrogen-based fertilizers, which can render water toxic to humans
and fish, and lead to eutrophication. Additionally, nitrate is highly mobile in sediments and poses
the potential for contamination of receiving waters, downstream areas, and ground water. The
objectives of this study were to evaluate the differences in ground water quality and sediment
denitrification rates at two sites, an undeveloped forested area (Oyster Creek, North Inlet, SC)
and an area which has been developed for residential and commercial use (Dog Creek, Murrells
Inlet, SC). Ground water monitoring wells were installed at the two sites at several sampling
depths ranging from 0.6 m to 5 m. Ground water samples were collected every 4-8 weeks for 16
months, and analyzed in the field for pH, conductivity, temperature, and dissolved oxygen (DO),
and in the laboratory for nitrate, nitrite, ammonia, phosphate and total organic carbon (TOC).
Additionally, sediment samples were collected from two locations in both creek bottoms from
approximately 1.0 m depth, and microbial denitrification was estimated using the acetylene block
technique by measuring the accumulation of nitrous oxide (N sub(2)O). Ground water at both
sites was microaerophilic, ranging from 0.4 to 1 mg O sub(2)/l. Ammonia and TOC
concentrations were significantly higher at the forested site due to higher inputs of organic matter
in the form of leafy vegetation, whereas nitrate concentrations were significantly higher at the
suburban site. Sediments from both sites were able to rapidly convert NO sub(3) to N sub(2)O
with progressive depletion of NO sub(3) in extracted sediments. Both the rate of N sub(2)O
production and the conversion efficiencies were found to increase with increasing nitrate
concentrations from 0.1 to 0.5 mg/g. The smallest nitrate concentration had the lowest N sub(2)O
production and NO sub(3) conversion efficiency. However, for the intermediate treatment (0.25
mg/g) conversion efficiencies were variable. In addition to potential increased NO sub(3) inputs,
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increased drainage for development present at suburban sites may cause aeration of near channel
soils and favor the oxidized, more mobile form of nitrogen. Because the suburban site has steeper
hydraulic gradients, and nitrate is highly mobile, there is potential for both nitrate transport to the
estuary and accumulation in the shallow water-table aquifer at the suburban site. However, it
appears that the microbial communities from both sites were well adapted to denitrifying inputs
of nitrate in the concentration ranges tested.
AN: 4092451
Record 21 of 79 - Water Resources Abs. 1/93-4/98
TI: Domestic well water quality in rural Nebraska: Focus on nitrate-nitrogen, pesticides, and
coliform bacteria.
AU: Gosselin,-D.C.; Headrick,-J.; Tremblay,-R.; Chen,-Xun-Hong; Summerside,-S.
SO: GROUND-WATER-MONIT.-REMEDIAT. 1997 vol. 17, no. 2, pp. 77-87
AB: For this statewide assessment, 1808 wells were sampled and a data base compiled that
included water-quality data (NO sub(3)-N, pesticides, coliform bacteria) and site-specific data
collected at each location. Domestic, rural water quality in Nebraska varies substantially from
one ground water region to another and is a function of well characteristics, distances to potential
contamination sources, and hydrogeologic and site characteristics. The percentage of wells
exceeding the 10 ppm MCL for NO sub(3)-N ranged from 3 to 39 percent, depending on the
ground water region. This large range of values indicates the inadequacy of stating that an
average of 19 percent of domestic wells in Nebraska are contaminated by nitrates. This statistic
does not describe the nature, extent, and variability of the contamination problem. Depending on
the ground water region, the degree of nitrate contamination in rural domestic drinking water
wells has remained generally unchanged or has only slightly increased since the last statewide
assessment conducted from 1985 to 1989. Bacterial contamination has either remained the same
or has decreased. The percentage of wells affected by bacteria ranged from 8 to 26 percent,
depending on the ground water region. Statewide, about 70 wells, or 4 percent of the wells
sampled, had detectable pesticide levels, of which atrazine was the most common. Eighty-two
percent of the detections were in the Platte River Valley or in the South Central Plains, both of
which are characterized by heavily irrigated corn and a statistical association between nitrate and
atrazine contamination. To improve the quality of domestic drinking water will require a
combination of activities, including the application of best management practices specific to a
ground water region and individual action at rural households, such as conducting sanitary
surveys of existing wells before installing new wells.
AN: 4091724
Record 22 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrogenous nutrient sources and sinks in the Juan de Fuca Strait/Strait of Georgia/Puget
Sound Estuarine System: Assessing the potential for eutrophication.
AU: Mackay,-D.L.; Harrison,-P.J.
SO: ESTUAR.-COAST.-SHELF-SCI. 1997 vol. 44, no. l,pp. 1-21
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AB: This paper estimates the overall nitrogenous nutrient budget for the Puget Sound/Strait of
Georgia/Juan de Fuca Strait estuarine ecosystem, and the potential for eutrophication of this
system by anthropogenic nutrient inputs. Large-scale eutrophication is unlikely for two reasons.
First, ambient nitrate + ammonia concentrations are high (2-20 mu M N) over much of the total
area, so that total primary productivity is relatively insensitive to moderate increases or
decreases. Second, exchange of water by estuarine and tidal currents is rapid (c. 1 year turnover
time), and entering water carries naturally high nutrient concentrations. Natural nitrogen inputs
by the estuarine circulation are very much larger than all other sources combined: 2600-2900
tonnes N day super(-l) for the entire system and 1400-1500 tonnes N day super(-l) for the inner
basins (Strait of Georgia and Puget Sound) vs. <100 tonnes N day super(-l) for sewage inputs,
<160 tonnes N day super(-l) for river inputs plus sewage, <15 tonnes N day super(-l) for coastal
groundwater discharge exclusive of sewage, and <10 tonnes N day super(-l) for atmospheric
inputs. The largest loss terms for nutrients are also due to estuarine exchange. Surface-layer
advective export of dissolved inorganic nitrogen is 2100-2400 tonnes N day super(-l) through
Juan de Fuca Strait and about 1000 tonnes N day super(-l) from the inner basins. Advective
export of organic nitrogen can be estimated only roughly, but is probably between 100 and 300
tonnes N day super(-l) as dissolved organics, and 100-200 tonnes N day super(-l) as living and
detrital particulates. Due to the dominant role of estuarine exchange, the overall nutrient budget
is likely to be strongly affected by variations in river discharge (affecting total flow) and offshore
oceanographic conditions (affecting nutrient content of incoming deep water). Sensitivity to
nutrient addition varies with location. The least sensitive sub-regions are the Strait of Juan de
Fuca and the tidally-mixed passages linking it to Puget Sound and the Strait of Georgia. The
most sensitive sub-regions are some tributary inlets and fjords that have low flushing rates and
that adjoin urbanized shorelines.
AN: 4082902
Record 23 of 79 - Water Resources Abs. 1/93-4/98
TI: Effects of artificial recharge on ground water quality and aquifer storage recovery.
AU: Ma,-Li; Spalding,-R.F.
SO: J.-AM.-WATER-RESOUR.-ASSOC. 1997 vol. 33, no. 3, pp. 561-572
AB: Ground water nitrate contamination and water level decline are common concern in
Nebraska. Effects of artificial recharge on ground water quality and aquifer storage recovery
(ASR) were studied with spreading basins constructed in the highly agricultural region of the
Central Platte, Nebraska. A total of 1.10 million m super(3) of Platte River water recharged the
aquifer through 5000 m super(2) of the recharge basins during 1992, 1993, and 1994. This is
equivalent to the quantity needed to completely displace the ground water beneath 34 ha of the
local primary aquifer with 13 m thickness and 0.25 porosity. Successful NO sub(3)-N
remediation was documented beneath and downgradient of the recharge basins, where NO
sub(3)-N declined from 20 to 2 mg L super(-l). Ground water atrazine concentrations at the site
decreased from 2 to 0.2 mg L super(-l) due to recharge. Both NO sub(3)-N and atrazine
contamination dramatically improved from concentrations exceeding the maximum contaminant
levels to those of drinking water quality. The water table at the site rose rapidly in response to
recharge during the early stage then leveled off as infiltration rates declined. At the end of the
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1992 recharge season, the water table 12m downgradient from the basins was elevated 1.36 m
above the preproject level; however, at the end of the 1993 recharge season, any increase in the
water table from artificial recharge was masked by extremely slow infiltration rates and heavy
recharge from precipitation from the wettest growing season in over 100 years. The water table
rose 1.37 m during the 1994 recharge season. Resultant ground water quality and ASR
improvement from the artificial recharge were measured at 1000 m downgradient and 600 m
upgradient from the recharge basins. Constant infiltration rates were not sustained in any of the
three years, and rates always decreased with time presumably because of clogging. Scraping the
basin floor increased infiltration rates. Using a pulsed recharge to create dry and wet cycles and
maintaining low standing water heads in the basins appeared to reduce microbial growth, and
therefore enhanced infiltration.
AN: 4082883
Record 24 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrate leaching under a cereal rye cover crop.
AU: Brandi-Dohm,-F.M.; Dick,-R.P.; Hess,-M.; Kauffman,-S.M.; Hemphill,-D.D., Jr.;
Selker,-J.S.
SO: J.-ENVIRON.-QUAL. 1997 vol. 26, no. l,pp. 181-188
AB: Winter cover crops hold potential to capture excess NO sub(3) super(-) and reduce leaching
by recycling nutrients. The objective of this study was to compare winter NO sub(3)-N leaching
losses under winter-fallow and a winter cereal rye (Secale cereale L.) cover crop following the
harvest of sweet corn (Zea mays L.) or broccoli (Brassica oleracea var. italica Plenck). Leachate
was sampled with passive capillary wick samplers that apply a suction of 0 to 5 kPa to the
soil-pore water and intercept leachate in a pan of known area. Without disturbing the over-laying
soil profile, 32 samplers (0.26 m super(2)) were installed at a depth of 1.2 m in a Willamette
loam (fine-silty mixed mesic Pachic Ultic Argixeroll). The randomized complete-block split plot
design of this cover crop-crop rotation study (initiated in 1989) has cropping system (winter
fallow vs. winter cereal rye) as main plots and three N application rates, ranging from 0 to 280 kg
N ha super(-l) yr super(-l), as subplots. At the recommended N rate for the summer crops, NO
sub(3) leaching losses were 48 kg N ha super(-l) under sweet corn-winter-fallow for winter
1992-1993, 55 kg N ha super(-l) under broccoli-winter-fallow for winter 1993-1994, and 103 kg
N ha super(-l) under sweet corn-winter-fallow for winter 1994-1995, which were reduced to 32,
21, and 69 kg N ha super(-l), respectively, under winter cereal rye. For the first two winters,
most of the variation (61%) in NO sub(3) super(-) leaching was explained by N rate (29%),
cereal rye N uptake (17%), and volume of leachate (15%). Seasonal, flow-weighted
concentrations at the recommended N rate were 13.4 mg N L super(-l) under sweet
corn-winter-fallow (1992-1993), 21.9 mg N L super(-l) under broccoli-winter-fallow, and 17.8
mg N L super(-l) under sweet corn-winter-fallow (1994-1995), which were reduced by 39, 58,
and 22%, respectively, under winter cereal rye.
AN: 4054912
Record 25 of 79 - Water Resources Abs. 1/93-4/98
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TI: Agriculture and nitrate concentrations in Maryland community water system wells.
AU: Lichtenberg,-E.; Shapiro,-L.K.
SO: J.-ENVIRON.-QUAL. 1997 vol. 26, no. l,pp. 145-153
AB: The presence of NO sub(3)-N in well water is a cause of growing concern throughout the
USA. Previous studies indicate that agriculture is a major contributor to this problem. This study
uses data on NO sub(3)-N concentrations in drinking water wells, on hydrological characteristics
of those wells, and on measures of agricultural activity and of the extent of residential land use to
construct statistical relationships between land use and well water quality in Maryland
community water system wells. Tobit regression was used to correct for truncation bias arising
from the fact that NO sub(3)-N was not reported at concentrations below 0.1 mg/L. Exponential
and linear specifications were estimated; non-nested hypothesis tests indicated that the
exponential specification fit the data better than the linear one. Deeper wells appear less
vulnerable to NO sub(3)-N contamination, wells in unconfined aquifers and especially limestone
formations, more so. Broiler and corn (Zea mays L.) production were associated with higher NO
sub(3)-N concentrations in drinking water in both specifications, indicating that
agriculture-oriented efforts aimed at preserving groundwater quality should be concentrated on
corn and broiler production. Septic systems for waste disposal also appear to have a substantial
impact on NO sub(3)-N concentrations in drinking water, suggesting that land use planning
measures such as minimum lot size zoning may be needed to prevent conversion of crop and
livestock production to residential units relying on septic systems from exacerbating groundwater
quality problems.
AN: 4054906
Record 26 of 79 - Water Resources Abs. 1/93-4/98
TI: Release of contaminants from a sewage stabilization pond and its influence on ground water
quality - a case study. • •
AU: Hameed,-A.S.; Madhavan,-K.; Velayudhan,-K.T.; Vasu,-K.
SO: POLLUT.-RES. 1994 vol. 13, no. 2, pp. 125-132
AB: A study was conducted to, find out the migration of pollutants from the sewage treatment
plant of Calicut Medical College to the surrounding areas and their influence on the quality of
ground water in the area. Water samples were drawn from domestic wells distributed around the
stabilization ponds at monthly intervals. Nitrogen and phosphorus were considered as indicative
elements for the pollutants. Soil samples were analysed for the above elements and organic
carbon. The data indicated fairly high level of nitrogen, phosphorus and organic carbon in the
soil profiles around study area upto a depth of 120 cm than the normal average nutrient present in
the local soil. Significant variations in electrical conductivity, nitrate nitrogen, Chloride of water
samples drawn from domestic wells were observed. Among metals, while sodium exhibited
much variation, the concentration of potassium did not vary much. The level of iron and
phosphorus found in the well water is fairly below the tolerance limit which can be due to the
immobile nature of phosphorus in soil and its precipitation as iron and aluminium phosphates.
AN: 4053425
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Record 27 of 79 - Water Resources Abs. 1/93-4/98
TI: The effect of watershed, reservoir volume, and rainfall on nitrate levels in surface drinking
water supplies.
AU: Shamblen,-R.G.; Binder,-D.M.
SO: J.-SOIL-WATER-CONSERV. 1996 vol. 51, no. 6, pp. 457-461
AB: Three separate water sources provide drinking water to about one million people in
Columbus, Ohio. About 80 percent of the city's drinking water is supplied by two surface water
sources, and the remainder by groundwater. Three instream reservoirs, managed by the city,
retain runoff from two separate watersheds. Agricultural production predominates in both
watersheds, yet only one of the two watersheds, the Scioto River watershed, has a history of
exceeding the Safe Drinking Water Act Nitrate-N Maximum Contaminant Level (MCL) standard
of 10 mg/L. We review the trends in nitrate-N concentration and loading in this watershed from
1982 to 1995.
AN: 4040904
Record 28 of 79 - Water Resources Abs. 1/93-4/98
TI: Who is drinking nitrate in their well water? A study conducted in rural northeastern Oregon.
AU: Mitchell,-TJ.; Harding,-A.K.
SO: J.-ENVIRON.-HEALTH 1996 vol. 59, no. 3, pp. 14-19
AB: This study evaluated the health risks for a rural northeastern Oregon population which is
exposed to high nitrate levels in well water. The study also identified possible sources of nitrate
contamination, and investigated measures the residents had taken to reduce their nitrate exposure
from well water. Three data sets were used in the study, including a telephone survey of the
residents, existing information collected by the Oregon Department of Environmental Quality
about well water nitrate concentrations, and demographic information from census records.
Results revealed that 23% of the surveyed population was drinking well water that contained
nitrate hi excess of the 10 ppm nitrate-nitrogen maximum contaminant level adopted by the U.S.
Environmental Protection Agency for drinking water. Seventy-two percent of the households
with nitrate levels exceeding the 10 ppm level did not use devices that effectively remove
nitrates. The population included few women of childbearing age, and was generally older than
other nearby urban or rural populations. Resident infants were not exposed to well water nitrate
in excess of the 10 ppm level, and were therefore not at apparent risk for methemoglobinemia
("blue-baby syndrome"). Although the risk of infant methemoglobinemia was low in this area, it
is recommended that alternative water sources be explored, and that follow-up monitoring be
performed by state and/or local agencies.
AN: 4020257
Record 29 of 79 - Water Resources Abs. 1/93-4/98
TI: Monitoring groundwater for pesticides at selected mixing/loading sites in Arkansas.
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AU: Senseman,-S.A.; Lavy,-T.L.; Daniel,-T.C.
SO: ENVIRON.-SCI.-TECHNOL. 1997 vol. 31, no..1, pp. 283-288
AB: Groundwater monitoring studies have been conducted in recent years to survey
contamination due to pesticides, yet few have addressed wells where pesticides are mixed,
loaded, or rinsed. Beginning in 1990, a monitoring study conducted over a 2-year period included
five collections at each of 16 mixer/loader locations to assess any pesticide and nitrate
contamination. At sites in 11 counties, samples for pesticide analysis were extracted with
solid-phase extraction (SPE) disks. Samples were screened using gas chromatography-electron
capture detection (BCD) and high-performance liquid chromatography-UV detection (LCUV) for
17 pesticides commonly used in Arkansas. Detections were confirmed by gas
chromatography-mass spectroscopy (MS) or co-chromatography. Fourteen samples revealed
atrazine (1 detection), cyanazine (4), parathion-methyl (2), metolachlor (2), norflurazon (1),
pendimethalin (1), propanil (2), or trifluralin (1) at eight locations during the 2-year study. Two
detections of parathion-methyl and one detection of trifluralin were above the Lifetime Health
Advisory Level (LHAL) of 2 mu g L super(-l). Data suggested a high correlation between
pesticide used and pesticide detected at sites sampled. Three wells contained NO sub(3)-N
concentrations of 10 mg L super(-l) or higher, but these did not correlate with pesticide
concentrations. The pesticide's proximity to the wells during mixing, rinsing, or loading was
considered to be a greater influence on temporary contamination of groundwater than chemical or
site-specific characteristics.
AN: 4018084
Record 30 of 79 - Water Resources Abs. 1/93-4/98 :
TI: Analysis of nitrate in near-surface aquifers in the midcontinental United States: An
application of the inverse hyperbolic sine Tobit model.
AU: Yen,-S.T.; Liu,-Shiping; Kolpin,-D.W.
SO: WATER-RESOUR.-RES. 1996 vol. 32, no. 10, pp. 3003-3011
AN: 4015565
Record 31 of 79 - Water Resources Abs. 1/93-4/98
TI: Shallow ground-water quality beneath a major urban center: Denver, Colorado, USA.
AU: Bruce,-B.W.; McMahon,-P.B.
SO: J.-HYDROL.-AMST. 1996 vol. 186, no. 1-4, pp. 129-151
AB: A survey of the chemical quality of ground water in the unconsolidated alluvial aquifer
beneath a major urban center (Denver, Colorado, USA) was performed in 1993 with the
objective of characterizing the quality of shallow ground-water in the urban area and relating
water quality to land use. Thirty randomly selected alluvial wells were each sampled once for a
broad range of dissolved constituents. The urban land use at each well site was sub-classified into
one of three land-use settings: residential, commercial, and industrial. Shallow ground-water
quality was highly variable in the urban area and the variability could be related to these land-use
setting classifications. Sulfate (SO sub(4)) was the predominant anion in most samples from the
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residential and commercial land-use settings, whereas bicarbonate (HCO sub(3)) was the
predominant anion in samples from the industrial land-use setting, indicating a possible shift in
redox conditions associated with land use. Only three of 30 samples had nitrate concentrations
that exceeded the US national drinking-water standard of 10 mg 1 super(-l) as nitrogen,
indicating that nitrate contamination of shallow ground water may not be a serious problem in
this urban area. However, the highest median nitrate concentration (4.2 mg 1 super(-l)) was in
samples from the residential setting, where fertilizer application is assumed to be most intense.
Twenty-seven of 30 samples had detectable pesticides and nine of 82 analyzed pesticide
compounds were detected at low concentrations, indicating that pesticides are widely distributed
in shallow ground water in this urban area. Although the highest median total pesticide
concentration (0.17 mu g 1 super(-l)) was in the commercial setting, the herbicides prometon
and atrazine were found in each land-use setting. Similarly, 25 of 29 samples analyzed had
detectable volatile organic compounds (VOCs) indicating these compounds are also widely
distributed in this urban area. The total VOC concentrations in sampled wells ranged from
nondetectable to 23 442 mu g 1 super(-l). Widespread detections and occasionally high
concentrations point to VOCs as the major anthropogenic ground-water impact in this urban
environment. Generally, the highest VOC concentrations occurred in samples from the industrial
setting. The most frequently detected VOC was the gasoline additive methyl tert-butyl ether
(MTBE, in 23 of 29 wells). Results from this study indicate that the quality of shallow ground
water in major urban areas can be related to land-use settings. Moreover, some VOCs and
pesticides may be widely distributed at low concentrations in shallow ground water throughout
major urban areas. As a result, the differentiation between point and non-point sources for these
compounds in urban areas may be difficult.
AN: 4010047 '
Record 32 of 79 - Water Resources Abs. 1/93-4/98
TI: Denitrification and mixing in a stream-aquifer system: Effects on nitrate loading to surface
water.
AU: McMahon,-P.B.; Boehlke,-J.K.
SO: J.-HYDROL.-AMST. 1996 vol. 186, no. 1-4, pp. 105-128
AB: Ground water in terrace deposits of the South Platte River alluvial aquifer near Greeley,
Colorado, USA, had a median nitrate concentration of 1857 mu mol/1. Median nitrate
concentrations in ground water from adjacent floodplain deposits (468 mu mol/1) and riverbed
sediments (461 mu mol/1), both of which are downgradient from the terrace deposits, were lower
than the median concentration in the terrace deposits. The concentrations and delta super(15)N
values of nitrate and N sub(2) in ground water indicated that denitrifying activity in the
floodplain deposits and riverbed sediments accounted for 15-30% of the difference in nitrate
concentrations. Concentrations of Cl super(-) and SiO sub(2) indicated that mixing between river
water and ground water in the floodplain deposits and riverbed sediments accounted for the
remainder of the difference in nitrate concentrations. River flux measurements indicated that
ground-water discharge in a 7.5 km segment of river had a nitrate load of 1718 kg N/day and
accounted for about 18% of the total nitrate load in the river at the downstream end of that
segment. This nitrate load was 70% less than the load predicted on the basis of the median nitrate
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concentration in the terrace deposits and assuming no denitrification or mixing in the aquifer.
Water exchange between the river and aquifer caused ground water that originally discharged to
the river to reenter denitrifying sediments in the riverbed and floodplain, thereby further
decreasing the nitrate load in this stream-aquifer system. Results from this study indicated that
denitrification and mixing within alluvial aquifer sediments may substantially decrease the nitrate
load added to rivers by discharging ground water.
AN: 4005527
Record 33 of 79 - Water Resources Abs. 1/93-4/98
TI: Hydrologic and microbiological factors affecting persistence and migration of petroleum
hydrocarbons spilled in a continuous-permafrost region.
AU: Braddock,-J.F.; McCarthy,-K.A.
SO: ENVIRON.-SCI.-TECHNOL. 1996 vol. 30, no. 8, pp. 2626-2633
AB: Fuel spills, totaling about 1300 m super(3), occurred between 1976 and 1978 adjacent to
Imikpuk Lake, a drinking water source near Barrow, AK. Substantial contamination of soils and
groundwater near the lake persists. We examined the magnitude and direction of groundwater
flux and the microbial activity at this site to understand the persistence of contamination and its
effect on the lake. We found that groundwater flux is small due to shallow permafrost, which
restricts the cross-sectional area available for flow, and to the short annual thaw season (ca. 90
days). The small flux and limited depth also constrain contaminant transport and dispersion,
resulting in persistent, shallow contamination. The numbers of hydrocarbon-oxidizing
microorganisms and their laboratory mineralization potentials for benzene (at 10 degree C) were
higher in samples from contaminated areas than in reference samples. Benzene mineralization
potentials in groundwater samples were comparable to more temperate systems (0.1-0.5 mg of
benzene mineralized L super(-l) day super(-l)) and were stimulated by nutrient additions. Field
measurements of dissolved oxygen, nitrate, ferrous iron, and sulfide in groundwater provided
evidence that biodegradation of petroleum hydrocarbons is occurring in situ. Despite evidence of
an active microbial population, microbial processes, like contaminant transport, are likely limited
at this site by the short annual thaw season.
AN: 3996184
Record 34 of 79 - Water Resources Abs. 1/93-4/98
TI: Variables indicating nitrate contamination bedrock aquifers, Newark Basin, New Jersey.
AU: Clawges,-R.M.; Vowinkel,-E.F.
SO: WATER-RESOUR.-BULL. 1996 vol. 32, no. 5, pp. 1055-1066
AB: Variables that describe well construction, hydrogeology, and land use were evaluated for
use as possible indicators of the susceptibility of ground water in bedrock aquifers in the Newark
Basin, New Jersey, to contamination by nitrate from.the land surface. Statistical analyses were
performed on data for 132 wells located throughout the Newark Basin. Concentrations of nitrate
(as nitrogen) did not exceed the U.S. Environmental Protection Agency maximum contaminant
level of 10 milligrams per liter (mg/L) in any of the water samples (U.S. Environmental
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Protection Agency, 1991). Variables that describe hydrogeology and well construction were
found not to be statistically significant in relation to concentrations of nitrate. This finding can be
attributed to the complex nature of flow in bedrock aquifers and mixing of water from shallow
and deep water-bearing zones that occurs within these wells, which are constructed with long
open intervals. Distributions of nitrate concentrations were significantly different among land-use
groups on the basis of land use within both a 400- and an 800-m radius zone of the well. The
median concentrations of nitrate (as N) in water from wells in predominantly urban-residential
(2.5 mg/L) and agricultural areas (1.8 mg/L) were greater than the median concentration of
nitrate in water from wells in predominantly undeveloped areas (0.5 mg/L).
AN: 3991123
Record 35 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrogen transport from tallgrass prairie watersheds.
AU: Dodds,-W.K.; Blair,-J.M.; Henebry,-G.M.; Koelliker,-J.K.; Ramundo,-R.; Tate,-C.M.
SO: J.-ENVIRON.-QUAL. 1996 vol. 25, no. 5, pp. 973-981
AB: Discharge and N content of surface water flowing from four Karst watersheds on Konza
Prairie Research Natural Area, Kansas, managed with different burn frequencies, were monitored
from 1986 to 1992. The goal was to establish the influence of natural processes (climate, fire, and
bison grazing) on N transport and concentration in streams. Streams were characterized by
variable flow, under conditions -that included an extreme flood and a drought during which all
channels were dry for over a year. The estimated groundwater/stream water discharge ratio varied
between 0.15 to 6.41. Annual N transport by streams, averaged across all watersheds and years,
was 0.16 kg N/ha/yr. Annual N transport per unit area also increased as the watershed area
increased and as precipitation increased. Total annual transport of N from the prairie via streams
ranged from 0.01 to 6.0% of the N input from precipitation. Nitrate and total N concentrations in
surface water decreased (P < 0.001, r values ranged from 0.14-0.26) as length of time since last
fire increased. Increased watershed area was correlated negatively (P < 0.0001) to stream water
concentrations of NO sub(3) super(-)-N and total N (r values = -0.43 and -0.20, respectively).
Low N concentration is typical of these streams, with NH sub(4) super(+)-N concentrations
below 1.0 mu g/L, NO sub(3) super(-)-N ranging from below 1.4 to 392 mu g/L, and total N
from 3.0 to 714 mu g/L. These data provide an important baseline for evaluating N transport and
stream water quality from unfertilized grasslands.
AN: 3985632
Record 36 of 79 - Water Resources Abs. 1/93-4/98
TI: Movement of nitrate fertilizer to glacial till and runoff from a claypan soil.
AU: Blevins,-D.W.; Wilkison,-D.H.; Kelly,-B.P.; Silva,-S.R.
SO: J.-ENVIRON.-QUAL. 1996 vol. 25, no. 3, pp. 584-593
AB: Although water from 20 to 25% of shallow farmstead wells in northern Missouri has
concentrations of nitrate (NO sub(3) super(-)) exceeding 10 mg L super(-l) as nitrogen (N),
many potential sources for this NO sub(3) super(-) are usually present. A field experiment was
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designed to trace and isolate the amount of a single application of N fertilizer lost to a glacial-till
aquifer and runoff from a 400 m super(2) corn (Zea mays L.) plot with bromide (Br super(-)) and
isotopically labeled ( super(15)N) fertilizer. Soil at the plot is a Albaquic Hapludalf of the Adco
Series containing a 61 cm claypan beneath 41 to 43 cm of topsoil. Groundwater levels ranged
from 0.38 to 2.40 m below the land surface. Transport of water and NO sub(3) super(-) to the
saturated zone was not substantially retarded by the claypan. Labeled-N fertilizer accounted for
as much as 8.6 mg L super(-l) of the NO sub(3) super(-) (as N) in groundwater, but only in the
top 1 to 2 m of the saturated zone. After two growing seasons (16 mo), <2% of the labeled-N
fertilizer was lost to runoff, about 30% was in the saturated zone, 27.3% was removed with the
grain, and about 5% remained in the unsaturated zone. A large part of the remaining labeled N
may have been lost in gaseous N forms. The presence of labeled NO sub(3) super(-) only in the
top 2 m of the aquifer, slow horizontal transport, and winter recharge indicate grass crops such as
wheat (Triticum aestivum L.) or rye (Secale cereale L.) might be used to extract near-surface N
during the winter recharge period. Also, fall fertilizations can be expected to readily leach.
Because groundwater concentrations of labeled NO sub(3) super(-) were still increasing after two
growing seasons, rotation of crops requiring small N inputs could be expected to limit the
cumulative effect of large annual fertilizer applications on groundwater.
AN: 3948855
Record 37 of 79 - Water Resources Abs. 1/93-4/98
TI: The potential impact of soil carbon content on ground water nitrate contamination.
AU: Adelman,-D.D.; Tabidian,-M.A.
CF: 2. IAWQ Int. Specialized Conference and Symposia on Diffuse Pollution, (Czech Rep.)
13-18 Aug 1995
SO: DIFFUSE POLLUTION '95. Straskraba,-M. (ed.) 1996 pp. 227-232.
AB: A potential buildup of nitrate in the ground water resources of the eastern Sandhills.of
Nebraska has been projected to occur due to the intensive use of nitrogen fertilizer on irrigated
cropland. A root-zone nitrate leaching study in this area revealed that soils with a high carbon
concentration had minimal leaching compared to soils with lower concentrations. Soils high in
carbon have an active population of denitrifying bacteria possibly causing denitrification and in
turn reduction of nitrate leaching. Denitrifying bacteria are principally heterotrophic using soil
organic carbon for both an energy and carbon source. The objective of this research was to
interpret how root-zone denitrification affected nitrate leaching and ground water contamination
by nitrate. A modified version of a solute transport model developed for the Eastern Sandhills
was used to assess the risk of nitrate contamination for combinations of fertilizer and irrigation
rates and for various soil carbon levels. The first attempt was to make risk assessment with eight
farm management practices for cells with increasingly greater carbon levels until only those cells
with the greatest carbon level were kept in production. Results of this assessment showed that
even with excessive fertilizer and irrigation rates, risk of nitrate leaching was reduced as the
minimum carbon level was increased. However, since less cropland was leaching nitrate with
each successive risk calculation, the impact that root-zone denitrification had in nitrate leaching
reduction could not be definitively determined. This prompted a model modification of the risk
calculation procedure which kept all cropland in production and computed nitrate leachate risk
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for increasingly higher artificial carbon levels during successive risk calculations. Changing
carbon levels was still more detrimental on nitrate leaching rates than changing farm
management practices.
AN: 3947466
Record 38 of 79 - Water Resources Abs. 1/93-4/98
TI: Effects of agricultural practices and vadose zone stratigraphy on nitrate concentration in
ground water in Kansas, USA.
AU: Townsend,-M.A.; Sleezer,-R.O.; Macko,-S.A.
CF: 2. IAWQ Int. Specialized Conference and Symposia on Diffuse Pollution, (Czech Rep.)
13-18 Aug 1995
SO: DIFFUSE POLLUTION'95. Straskraba,-M. (ed.) 1996 pp. 219-236.
AB: Differences in nitrate-N concentrations in ground water in Kansas can be explained by
variations in agricultural practices and vadose-zone stratigraphy. In northwestern Kansas, past
use of a local stream for tailwater runoff from irrigation and high fertilizer applications for
sugar-beet farming resulted in high nitrate-N enncentrations (12-60 mg L super(-l) in both soil
and ground water. Nitrogen isotope values from the soil and ground water range from +4 to
+8ppt, which is typical for a fertilizer source. In parts of south-central Kansas, the use of crop
rotation and the presence of both continuous fine-textured layers and a reducing ground-water
chemistry resulted in ground-water nitrate-N values of < 3 mg L super(-l). The effects of
denitrification in the vadose zone and ground water are indicated by enriched sigma super(15)N
values of+10 to +15ppt. At a site study, irrigated continuous corn was grown on sandy soils with
discontinuous fine-textured layers. Here, nitrate-N concentrations were often > 10 mg L
super(-l); in both soil and groundwater. Nitrogen isotope values of+3 to +7ppt indicate a
fertilizer source. Crop rotation decreased nitrate-N values in the shallow ground water (9 m).
However, deeper ground water showed increasing nitrate-N concentrations as a result of past
farming practices.
AN: 3947465
Record 39 of 79 - Water Resources Abs. 1/93-4/98
TI: Temporal and spatial variability ha water quality of wetlands in the Minneapolis/St. Paul,
MN metropolitan area: Implications for monitoring strategies and designs.
AU: Detenbeck,-N.E.; Taylor,-D.L.; Lima,-A.; Hagley,-C.
SO: ENVIRON.-MONIT.-ASSESS. 1996 vol. 40, no. 1, pp. 11-40
AB: Temporal and spatial variability in wetland water-quality variables were examined for
twenty-one wetlands in the Minneapolis/St. Paul metropolitan area and eighteen wetlands in
adjacent Wright County. Wetland water quality was significantly affected by contact with the
sediment (surface water vs. groundwater), season, degree of hydrologic isolation, wetland class,
and predominant land-use in the surrounding watershed (p < 0.05). Between years, only nitrate
and particulate nitrogen concentrations varied significantly in Wright County wetland surface
waters. For eight water-quality variables, the power of a paired before-and-after comparison
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design was greater than the power of a completely randomized design. The reverse was true for
four other water-quality variables. The power of statistical tests for different classes of
water-quality variables could be ranked according to the predominant factors influencing these:
climate factors > edaphic factors > detritivory > land-use factors > biotic-redox or other fnultiple
factors. For two wetlands sampled intensively, soluble reactive phosphate and total dissolved
phosphorus were the most spatially variable (c.v. = 76-249%), while temperature, color,
dissolved organic carbon, and DO were least variable (c.v. = 6-43%). Geostatistical analyses
demonstrated that the average distance across which water-quality variables were spatially
correlated (variogram range) was 61-112% of the mean radius of each wetland. Within the
shallower of the two wetlands, nitrogen speciation was explained as a function of dissolved
oxygen, while deeper marsh water-quality variables were explained as a function of water depth
or distance from the wetland edge. Compositing water-quality samples produced unbiased
estimates of individual sample means for all water quality variables examined except for
ammonium.
AN: 3928142
Record 40 of 79 - Water Resources Abs. 1793 -4/98
TI: Ground-water quality and flow in a shallow-glaciofluvial aquifer impacted by agricultural
contamination.
AU: Kehew,-A.E.; Straw,-W.T.; Steinmann,-W.K.; Barrese,-P-G.; Passarella,-G.;
Peng,-Wei-Shyuan
SO: GROUND-WATER 1996 vol. 34, no. 3, pp. 491-500
AB: The Prairie Ronde fan, a discrete glaciofluvial deposit in southwestern Michigan, contains a
productive but highly vulnerable unconfined aquifer used for irrigation, municipal, and domestic
supply. A comprehensive hydrogeological study of the aquifer delineated shallow, local flow
systems that interact with ponds and wetlands on the fan surface, overlying a deeper
intermediate/regional flow system extending to the base of the glacial drift. Ground water within
the shallow flow systems contains tritium concentrations indicative of a post-bomb age and is
heavily impacted by nonpoint source contamination. Nitrate commonly exceeds drinking water
standards in the shallow flow system. Although no continuous physical barrier separates the two
flow systems, the deeper flow system is generally lacking in tritium as well as nonpoint source
contaminants derived from surface land uses. High capacity pumping from the deeper flow
system, however, will likely draw contaminants downward from the shallow flow system.
Background-water quality in the aquifer is controlled by equilibrium with calcite and slight
undersaturation with respect to dolomite. No spatial trends in major ions were observed,
suggesting that carbonate mineral equilibrium is achieved rapidly in the vadose zone and further
chemical evolution along ground-water flow paths is minimal. Iron concentrations are highly
variable in the aquifer and not correlated with depth. Recharge from lakes and wetlands is a
significant cause of elevated iron concentrations in the shallow flow systems.
AN: 3920744
Record 41 of 79 - Water Resources Abs. 1/93-4/98
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TI: Ground water discharge of agricultural pesticides and nutrients to estuarine surface water.
AU: Gallagher,-D.L.; Dietrich,-A.M.; Reay,-W.G.; Hayes,-M.C.; Simmons,-G.M., Jr.
SO: GROUND-WATER-MONIT.-REMEDIAT. 1996 vol. 16, no. l,pp. 118-129
AB: This research investigated the transport of land-applied nutrients and pesticides from
unconfined aquifers to tidal surface waters of Virginia's coastal plain. Ground water, estuarine
surface water, ground water discharge, upland soil, and offshore sediment samples were collected
from May 1992 until February 1993 from four agricultural sites. Samples were analyzed for
inorganic nitrogen and phosphorus and five pesticides: atrazine, cyanazine, alachlor, metolachlor,
and carbofuran. Pesticides from aqueous samples were determined by liquid-solid phase
extraction followed by gas chromatography-electron capture detection (GC-ECD) and/or by
pesticide-specific irnrnunoassay. Soil and sediment samples were analyzed by extraction and gas
cliromatography/mass spectrometry (GC/MS). Nutrient measurements indicated that fertilizer
nitrogen was moving from the ground water to the surface water, and nitrogen fluxes across the
sediment-water interface were correlated with fresh water discharge rates. Mean nitrate-N flux
was 2.48 mg/m super(2)/hr, with a maximum value of 30.98 mg/m super(2)/hr. Pesticides were
detected in more than half of the upland soil samples, in approximately 40 percent of the ground
water samples, and in just under 20 percent of the seepage meter samples. Pesticides were not
detected in any of the offshore sediment samples or surface water samples. Alachlor and
metolachlor were detected in upland soil samples at concentrations ranging from 10 to almost
500 mu g/kg. All five pesticides were found in ground water samples at concentrations generally
below 1 mu g/L, with alachlor, atrazine, and metolachlor most frequently found. Alachlor,
atrazine, cyanazine, and metolachlor were detected in water discharging across the
sediment-water interface and entering estuarine waters at concentrations ranging from 0.05 to 0.5
mu g/L. These levels were generally consistent with the amount of dilution due to the mixing of
fresh ground water and saline pore waters prior to discharge across the sediment-water interface.
Based on all positive detections of pesticides in ground water discharge, which represented
approximately 18 percent of all samples, average flux rates of cyanazine, metolachlor, alachlor,
and atrazine were 0.32, 0.37, 0.80, and 1.12 mu g/m super(2)/hr, respectively. These findings
indicate that submarine ground water transport of both nutrients and pesticides does occur, and
this transport route should be considered when implementing agricultural management practices.
The levels of nitrogen transport to surface water appears significant. The overall levels of
pesticide movement through ground water, although generally quite low, represent a transport
route that is commonly neglected hi watershed management.
AN: 3873465
Record 42 of 79 - Water Resources Abs. 1/93-4/98
TI: Combined use of groundwater dating, chemical, and isotopic analyses to resolve the history
and fate of nitrate contamination in two agricultural watersheds, Atlantic Coastal Plain,
Maryland.
AU: Boehlke,-J.K.; Denver,-J.M.
SO: WATER-RESOUR.-RES. 1995 vol. 31, no. 9, pp. 2319-2339
AN: 3997047
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Record 43 of 79 - Water Resources Abs. 1/93-4/98
TI: The Platte River watershed program.
AU: Lathrop,-B.
SO: J.-SOIL-WATER-CONSERV. 1995 vol. 50, no. 6, pp. 601-604
AB: The Platte River originates in the mountains of Colorado and Wyoming, and its watershed
drains two-thirds of the state of Nebraska. Groundwater is a critical component of this watershed,
as there are extensive wetlands where surface water/groundwater meet. The Platte River alluvial
aquifer provides drinking water for 70 percent of Nebraska's citizens. The U.S. Environmental
Protection Agency and Nebraska Department of Environmental Quality (NDEQ) have initiated a
Platte River Watershed Program to examine and plan for environmental concerns in the area.
These include nonpoint sources of pollution, nitrate and pesticide contamination, wetlands and
habitat destruction and alteration, floodplain development, and hydrologic modification.
AN: 3874574
Record 44 of 79 - Water Resources Abs. 1/93-4/98 ,
TI: Agricultural impacts on bacterial water quality in karst groundwater.
AU: Pasquarell,-G.C.; Boyer,-D.G.
SO: J.-ENVIRON.-QUAL. 1995 vol. 24, no. 5, pp. 959-969
AB: A 2-yr study (1991-1992) was conducted in a karst region in southeast West Virginia to
determine the impact of agriculture on groundwater quality. The primary agriculture is
characterized by seasonal cattle grazing. Fecal coliform densities were measured weekly in the
resurgences of three karst basins possessing different degrees of agricultural intensity (79, 51,
and 16% land use in agriculture). Fecal coliforms were also measured in a creek at sites upstream
and downstream of the known resurgences from the most agriculturally intensive (79%) basin.
The fecal coliform densities in the resurgences peaked in the summer and declined in the fall,
with a recovery in late winter before the introduction of new cattle. The timing of the recovery
indicated that significant storage of fecal material had taken place, which was transported to the
groundwater when soil water conditions permitted. For most of each year, soil water effects
appeared to have a greater bearing on the fecal coliform densities than did the presence or
absence of cattle. The data did not generally support a strong relationship with percent land use
in agriculture. This was attributed to the high variability in the data and to low soil moisture
during periods of recession that inhibited the transport of fecal material to the groundwater. The
karst resurgence springs of.the most intensively agricultural basin were contaminated with fecal
bacteria. Fecal bacteria concentrations were observed to significantly increase, in the receiving
surface stream, from a point upstream of the resurgence springs to a point downstream of the
resurgence springs.
AN: 3843713
Record 45 of 79 - Water Resources Abs. 1/93-4/98
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TI: Wetlands/groundwater quality in agricultural landscapes.
AU: Rickerl,-D.H.; Kringen,-D.R; Machacek,-T.A.
SO: J.-MINN.-ACAD.-SCI. 1995 vol. 59, no. 4, pp. 18-24
AB: In the Prairie Pothole Region (PPR - SD, ND, MN, IA), wetlands classified as
"semi-permanent" or "seasonal" can act as groundwater recharge sites. The nutrient filtering
capacity of wetlands has been investigated for both natural and constructed wetlands linked to
surface water, but there is little information available on their subsequent impact on groundwater
quality. This study investigates four seasonal and two semi-permanent wetlands in the PPR of
eastern South Dakota. Transitional no-till (TNT) and organic farm (ORG) management systems
border the wetlands. The objective is to determine the effects of farm management system on
wetland surface water and groundwater quality. This project is part of a more comprehensive
study including wildlife-habitat investigation and economic analyses. Water quality data include
nitrate (NO sub(3) super(-)-N) and orthophosphate (PO sub(4) super(S-)-P) concentrations from
wetland surface water, groundwater at wetland and upland sites, and run-off water from
surrounding weirs. The results will be used to determine to what extent PPR wetlands act as
sinks for nutrient run-off and establish baseline NO sub(3) super(-)-N and PO sub(4) super(3-)P
data for the development of PPR wetland water quality standards. The results indicate greater
surface water NO sub(3) super(-)-N concentrations in semi-permanent than in seasonal wetlands.
Surface water concentrations of PO sub(4) super(3-)-P, however, were greater in seasonal than
semi-permanent wetlands. Groundwater sampled near the wetland perimeter had greater PO
sub(4) super(3-)-P concentrations than groundwater sampled from nearby upland sites. The
farming system effects were observed in weir data that indicated large concentrations of NO
sub(3) super(-)-N in runoff following nitrogen (N) application in the transitional no-till system.
Large NO sub(3) super(-)-N concentrations were also found in groundwater sampled from the
organic semi-permanent wetland site which is cropped to alfalfa (Medicago sativa L.) and receive
manure application. Orthophosphate concentrations were significantly greater in groundwater
near the seasonal wetland in the ORG (0.68 mg L super(-l)) than the TNT (0.20 mg L super(-l)).
Water quality monitoring will continue in 1995, but preliminary results suggest that both wetland
classification and adjacent farming practices impact wetland and groundwater quality.
AN: 3838180
Record 46 of 79 - Water Resources Abs. 1/93-4/98
TI: Relation of ground-water quality to land use on Long Island, New York.
AU: Eckhardt,-D.A.V.; Stackelberg,-P.E.
SO: GROUND-WATER 1995 vol. 33, no. 6, pp. 1019-1033
AB: Water-quality data from 90 monitoring wells screened within 50 feet of the water table in
the unconiined upper glacial aquifer beneath five areas of differing land use in Nassau and
Suffolk Counties, Long Island, were compared to assess the effects of land use on ground-water
quality. The areas, which range from 22 to 44 square miles, represent suburban land sewered
more than 22 years at the time of the study (long-term sewered), suburban land sewered less than
8 years (recently sewered), suburban land without a regional sewer system, agricultural land, and
undeveloped (forested) land. Comparison of water-quality data from the 90 wells indicated that
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samples from the undeveloped area had the lowest and smallest range in concentrations of
several human-derived constituents, such as nitrate, alkalinity, boron, synthetic solvents, and
pesticides. Concentrations of these constituents in samples from the three suburban areas and the
agricultural area generally were intermediate to high and had the widest variation.
Maximum-likelihood logistic regression analysis of explanatory variables that characterize the
type of land use and population density within a one half-mile radius of each of the 90 wells
was used to develop predictive equations for contaminant occurrence in ground water within 50
feet of the water table. Two logistic regression equations for the 90 monitoring wells were
compared with equations developed independently from ground-water quality data at more than
240 other wells throughout Nassau and Suffolk Counties to evaluate the predictive value of the
land-use variables at the larger two-county scale. The results demonstrate that the population
density and amount of agricultural, commercial, and high- and medium-density residential land
within specified areas around wells can be reliable predictors of contaminant presence. The
strength of the correlations supports the premise that land use affects the quality of water in
water-table aquifers overlain by highly permeable material because land use commonly
determines the types and amounts of chemicals introduced at land surface. When coupled with
GIS technology and accurate, detailed land-use and water-quality information, the methods and
results of this study can be useful to local planning boards in evaluation of potential effects of
development on ground-water quality. The methods can also be useful to hydrologists in the
analysis and design of ground-water-monitoring networks.
AN: 3836943
Record 47 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrate concentrations in karst springs in an extensively grazed area.
AU: Boyer,-D.G.; Pasquarell,-G.C.
SO: WATER-RESOUR.-BULL. 1995 vol. 31, no. 4, pp. 729-736
AB: The impact on water quality by agricultural activity in karst terrain is an.important
consideration for resource management within the Appalachian Region. Karst areas comprise
about 18 percent of the Region's land area. An estimated one-third of the Region's farms, cattle,
and agricultural market value are located on karst terrain. Nitrate concentrations were measured
in several karst springs hi Southeastern West Virginia in order to determine the impact of animal
agriculture on nitrate pollution of the karst ground water system. Karst basins with 79, 51,16,
and 0 percent agriculture had mean nitrate concentrations of 15.8, 12.2, 2.7, and 0.4 mg/1,
respectively. A strong linear relationship between nitrate concentration and percent agricultural
land was shown. Median nitrate concentration increased about 0.19 mg 1 super(-l) per percent
increase in agricultural land. Weather patterns were also found to significantly affect the median
nitrate concentrations and the temporal variability of those concentrations. Lower nitrate
concentrations and lower temporal variability were observed during a severe drought period. It
was concluded that agriculture was significantly affecting nitrate concentrations in the karst
aquifer. Best management practices may be one way to protect the ground water resource.
AN: 3834937
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Record 48 of 79 - Water Resources Abs. 1/93-4/98
TI: Groundwater quality near two cattle feedlots in Texas High Plains: A case study.
AU: Sweeten,-J.M.; Marek,-T.H.; McReynolds,-D.
SO: APPL.-ENG.-AGRIC. 1995 vol. 11, no. 6, pp. 845-850
AB: A groundwater sampling study was conducted at two cattle feedlots with capacities of
45,000 (Feedlot A) and 42,500 head (Feedlot B), respectively, in Castro and Farmer Counties in
the Southern High Plains of Texas. At both feedlots, groundwater was sampled from the Ogallala
Aquifer at four water wells supplying cattle drinking water and from 10 or 11 irrigation wells
within a distance of 1.07 to 1.41 km (0.67 to 0.88 mile) from the feed pens or playa basins
(natural depressions) used for collection of feedlot runoff. Water table depth was 82.3 to 97.5 m
(270 to 320 ft). Nitrate-nitrogen (NO sub(3)N) concentrations averaged less than 1.2 mg/L at
Feedlot A (maximum value of 2.23 mg/L) and 5.21 mg/L at Feedlot B (maximum value of 9.54
mg/L). These are below the USEPA primary drinking water standard of 10.0 mg/L NO sub(3)-N.
Other nutrient and salinity values were low. The well water in all feedlot wells and in farm
irrigation wells appears to be suitable for irrigation, livestock watering, and human consumption.
Minimal differences were found between parameter concentrations in feedlot wells and adjacent
farm irrigation wells. Groundwater quality near these two feedlots met primary and secondary
EPA drinking water standards for those parameters tested.
AN: 3828621
Record 49 of 79 - Water Resources Abs. 1/93-4/98
TI: Pesticides in eastern North Carolina rural supply wells: Land use factors and persistence.
AU: Maas,-R.P.; Kucken,-DJ.; Patch,-S.C.; Peek,-B.T.; Van-Engelen,-D.L.
SO: J.-ENVIRON.-QUAL. 1995 vol. 24, no. 3, pp. 426-431
AB: Water samples were collected from 171 rural domestic well supplies in eastern North
Carolina and analyzed for eight pesticides. Information on borehole depth, well-casing depth,
distance to nearest pesticide mixing area, types of pesticides used, and distance to nearest field
application was obtained for each site. Four herbicides [alachlor, 2-chloro- 2'-6'diethyl-N-
(methoxymethyl)- acetanilide; atrazine, 2-chloro-4- ethylamino-6- isopropylamino-s- triazine;
metolachlor, 2-chloro-N- (2-ethyl-6-methylphenyl) -N-(2-methoxy-l- methylethyl) acetamide;
trifluralin, alpha, alpha, alpha - trifluoro-2,6- dinitro-N,N- dipropyl-p- toluidine] were detected
in the samples, with detection frequencies of 8.8, 8.2, 3.6, and 1.8%, respectively. About 15% of
the samples contained at least one of these herbicides, with resampling indicating persistence
throughout the year. Only alachlor concentrations were in excess of maximum contaminant
levels (MCLs; 2.0 mu g L super(-l)) or Health Advisory Levels (HALs; 0.4 mu g L super(-l))
established by the U.S. Environmental Protection Agency (USEPA). Neither atrazine nor
alachlor detection exhibited statistical correlation with well depth, although both were rarely
detected in wells >100 feet deep. Atrazine concentrations and detection frequencies did not
correlate with distance to nearest application site, while alachlor had a significantly greater
detection frequency for wells further from the nearest application site. For nearly one-half of the
wells with detectable atrazine and alachlor,. there was no reported usage of either herbicide on the
same farm during the previous three years, possibly indicating herbicide transport in groundwater
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or long times before degrading. No statistically significant relationships were observed between
the presence of alachlor or atrazine, and distance from the well to the nearest pesticide handling
and storage area. Although inconclusive by itself, this indicates that at least some contamination
originated from other than point-source spills. Nitrate-N concentrations in well water were poor
predictors for atrazine and alachlor presence in this study.
AN: 3815993
Record 50 of 79 - Water Resources Abs. 1/93-4/98 .
TI: The occurrence of agricultural chemicals in Illinois' rural private wells: Results from the
pilot study.
AU: Mehnert,-E.; Schock,-S.C.; Barnhardt,-M.L.; Caughey,-M.E.; Chou,-S.F.J.; Dey,-W.S.;
Dreher,-G.B.; Ray,-C.
SO: GROUND-WATER-MONIT.-REMEDIAT. 1995 vol. 15, no. l,pp. 142-149
AB: Water samples from 240 private wells in rural Illinois were collected over one year and
analyzed for 39 agricultural chemicals. Sampling was conducted to provide preliminary
information to refine a plan for a statewide survey of the agricultural chemical contamination of
rural private wells. Wells were sampled according to. a stratified random sampling plan that
included four classes of depth to the uppermost aquifer material and two classes of well type.
Depth to uppermost aquifer material was defined as the depth from ground surface to a geologic
material that, if saturated, could be used as an aquifer. Occurrence, defined as the presence of one
or more target analytes in a well water sample above some specified concentration, was shown to
be higher in large-diameter bored or dug wells than in small-diameter drilled wells. For
small-diameter wells, occurrence generally decreased as the depth to the uppermost aquifer
material increased. In addition, depth to the uppermost aquifer material could be used to predict
the occurrence of some individual agricultural chemicals, such as nitrate and atrazine, but could
not be used to predict the occurrence of picloram or pesticides in small-diameter wells. Of the 39
target analytes, 10 were detected at concentrations exceeding their respective minimum reporting
levels. Nitrate and atrazine were the only compounds found at concentrations exceeding their
respective maximum contaminant levels (MCLs) or U.S. EPA lifetime health advisory limits
(HALs). A nonparametric statistical technique, contingency table analysis, identified factors
associated with the occurrence of agricultural chemicals in three of the five study areas. Elevated
specific conductance ( greater than or equal to 500 mu mhos/cm) of the sampled water was
strongly associated with the occurrence of agricultural chemicals. This association was common
to all three study areas analyzed. Identification of the source of the specific conductance could
help identify the dominant pathway for transport of agricultural- chemicals to ground water.
AN: 3815988
Record 51 of 79 - Water Resources Abs. 1/93-4/98
TI: Effects of agriculture on ground-water quality in five regions of the United States.
AU: Hamilton,-P.A.; Helsel,-D.R.
SO: GROUND-WATER 1995 vol. 33, no. 2, pp. 217-226
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AB: Water-quality conditions in surficial unconsolidated aquifers were assessed in five
agricultural regions in the United States. The assessment covers the Delmarva Peninsula, and
parts of Long Island, Connecticut, Kansas, and Nebraska, and is based on water-quality and
ancillary data collected during the 1980s. Concentrations of nitrate in ground water in these areas
have increased because of applications of commercial fertilizers and manure. Nitrate
concentrations exceed the maximum contaminant level (MCL) for drinking water of 10
milligrams per liter as nitrogen established by the U.S. Environmental Protection Agency in 12 to
46 percent of the wells sampled in the agricultural regions. Concentrations of nitrate are elevated
within the upper 100 to 200 feet of the surficial aquifers. Permeable and sandy deposits that
generally underlie the agricultural areas provide favorable conditions for vertical leaching of
nitrate to relatively deep parts of the aquifers. The persistence of nitrate at such depths is
attributed to aerobic conditions along ground-water-flow paths. Concentrations of nitrate are
greatest in areas that are heavily irrigated or areas that are underlain by well-drained sediments;
more fertilizer is typically applied on land with well-drained sediments than on poorly drained
sediments because well-drained sediments have a low organic-matter content and low moisture
capacity. Concentrations of other inorganic constituents related to agriculture, such as potassium
and chloride from potash fertilizers, and calcium and magnesium from liming, also are
significantly elevated in ground water beneath the agricultural areas. These constituents together
impart a distinctive agricultural-chemical trademark to the ground water, different from natural
water.
AN: 3788874
Record 52 of 79 - Water Resources Abs. 1/93-4/98
TI: Survey of nitrate contamination in shallow domestic drinking water wells of the Inner
Coastal Plain of Georgia.
AU: Stuart,-M.A.; Rich,-FJ.; Bishop,-G.A.
SO: GROUND-WATER 1995 vol. 33, no. 2, pp. 284-290
AB: Beginning in 1990,2,588 wells were sampled within the Inner Coastal Plain of Georgia in
an effort to assess the quality of ground water in this major farm belt. The project was one aspect
of an EPA-sponsored program to assess ground-water quality statewide. Several variables were
measured, including pH, specific conductivity, dissolved oxygen, temperature, nitrate, nitrite,
total hardness, calcium, magnesium, and bicarbonate. In some wells sulfate, chloride, potassium,
iron, and manganese contents were also determined. Particular emphasis was placed, however,
on pH, specific conductivity, temperature, and nitrite/nitrate content. Generally, pH was between
6 and 8, and temperatures were within a range of 18 degree and 24 degree Celsius.
Measurements of specific conductivity varied, but averaged 250-275 microsiemens/cm. Nitrite
contamination was negligible, and nitrate contamination of the ground water within the shallow
aquifers did not appear to be significant. In fact, 56% of the wells sampled showed no detectable
signs of nitrate or nitrite contamination. There were, however, a few isolated wells where nitrate
as nitrogen measurements exceeded the EPA's Safe Drinking Water Standard of 10 ppm. The
general lack of contamination may be the result of the nature of the agricultural practices used in
this region and/or the effect of natural denitrification.
AN: 3779002
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Record 53 of 79 - Water Resources Abs. 1/93-4/98
TI: Comparison of shallow ground-water quality between urban and agricultural land-use
settings, South Platte River Basin, Colorado and Nebraska.
AU: Bruce,-B.W.; McMahon,-P.B.
CF: 1994 South Platte Forum, Greeley, CO (USA) 26-27 Oct 1994
SO: INTEGRATED WATERSHED MANAGEMENT IN THE SOUTH PLATTE BASIN:
STATUS AND PRACTICAL IMPLEMENTATION. PROCEEDINGS OF THE 1994 SOUTH
PLATTE FORUM, OCTOBER 26-27,1994, GREELEY, COLORADO. Klein,-K.C.;
Williams,-DJ. (eds.) COLORADO STATE UNIVERSITY, FORT COLLINS, CO 80523 (USA)
COLORADO WATER RESOURCES RESEARCH INSTITUTE. 1994 pp. 23-24.
AB: As part of the National Water-Quality Assessment Program's South Platte River Basin
study, the U.S. Geological Survey has sampled shallow alluvial ground water beneath urban
(Denver, Colo.) andt agricultural (South Platte River alluvium from Brighton, Colo, to North
Platte, Nebr.) land-use settings to determine the effect of land use on water quality. Thirty
randomly distributed wells in each land-use setting were sampled for nutrients, trace elements
and radon, pesticides and volatile organic compounds (VOC's). Nutrient species concentrations
generally were lower in the urban setting than hi the agricultural setting. The median
concentration of dissolved nitrite plus nitrate as nitrogen in the urban setting was 2.1 milligrams
per liter. Preliminary results indicate a median concentration of 7.0 milligrams per liter for nitrite
plus nitrate in the agricultural setting. Trace-element and radon concentrations indicated no
correlation with land-use setting. However, uranium and radon occurred at elevated
concentrations in both land-use settings (median concentrations of uranium and radon were 25
micrograms per liter and 1100 picoCuries per liter). The distribution of uranium and radon in
ground water probably was affected mostly by local geology rather than by land use. Pesticide
compounds detected in ground-water samples from both land-use settings generally occurred at
low concentrations. Prometon, a nonselective herbicide, was the most frequently detected
pesticide in the urban setting and atrazine was the most frequently detected pesticide in the
agricultural setting. However, both of these compounds were detected in each of the land-use
settings. VOC's were detected in 86 percent of the urban wells sampled, and concentrations of
specific compounds frequently exceeded National Drinking Water Standards. Preliminary results
indicate that VOC's are almost nonexistent in alluvial ground water of the agricultural setting.
The presence of VOC's affected redox conditions in the alluvial aquifer in the urban setting and,
consequently, the chemistry of the urban ground water. Data indicated that land use does have a
measurable effect on the quality of ground water in the South Platte River alluvial aquifer and
that ground-water quality differs between urban and agricultural land-use settings!
AN: 3834955
Record 54 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrate contamination from dairy lagoons constructed in coarse alluvial deposits.
AU: Korom,-S.F.; Jeppson,-R.W.
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SO: J.-ENVER.ON.-QUAL. 1994 vol. 23, no. 5, pp. 973-976
AB: In an effort to reduce surface inflows of nutrients to Deer Creek Reservoir in north central
Utah, several dairies hi Heber Valley constructed unlined lagoons to store wastes for later
application onto fields as fertilizer. Previous research indicated that dairy lagoons sealed with use
and were not significant sources of contamination; however, the soils in Heber Valley are coarser
than hi the literature. Therefore, two of Heber Valley's dairy lagoons were studied as sources of
NO super(-) sub(3)-N to the groundwater system. One lagoon was constructed on Holmes
subsoils (loamy-skeletal, mixed, frigid Typin Argixerolls); its seepage rate was estimated at 13 to
91 mm/d, which is as high or higher than any of the rates reported in the literature. The other
lagoon was constructed on Deer Creek subsoils (fine, montmorillonitic, frigid Typic Palexerolls).
Leachate quality from both lagoons typically exceeded the drinking water standard of 10 mg NO
super(-) sub(3)-N/L and sometimes exceeded 100 mg NO super(-) sub(3)-N/L. The likely reason
for the high NO super(-) sub(3)-N concentrations was that the coarse soils in Heber Valley
sometimes permitted the aerobic conditions necessary for nitrification of immobile NH super(+)
sub(4) to mobile NO super(-) sub(3). We concluded that the unlined dairy lagoons were
significant sources of N (as NO superQ sub(3)) contamination to the Heber Valley aquifer.
AN: 3697288
Record 55 of 79 - Water Resources Abs. 1/93-4/98
TI: Contribution of spray irrigation of waste water to groundwater contamination in the karst of
southeastern Minnesota, USA.
AU: Mooers,-H:D.; Alexander,-E.C., Jr.
SO: APPL.-HYDROGEOL. 1994 vol. 2, no. 1, pp. 34-43
AB: A vegetable- and meat-canning facility located in the karst of southeastern Minnesota
disposes approximately 2.85 x 10 super(5) m super(3) yr super(-l) of wastewater by spray
irrigation of an 83.7-ha field located atop the local groundwater divide. Cannery effluent contains
high levels of chloride and nitrogen (organic and ammonia), in excess of 7000 mg/1 and 400
mg/1, respectively. Nitrate-nitrogen concentrations are generally <5 mg/1. Agricultural, domestic,
and municipal sources of chloride and nitrate are common in the region, and water supplies
frequently exceed the drinking-water limit for nitrate-nitrogen of 10 mg/1. Fifty-two area wells
and thirteen surface-water locations were sampled and analyzed for five ionic species, including:
chloride (Cl), nitrate-nitrogen (NO sub(3)-N), sulfate (SO sub(4)), nitrite-nitrogen (NO
sub(2)-N), and phosphate (PO sub(4)). Two distinct chloride plumes flowing outward from the
groundwater divide were identified, and 65% of the wells sampled had nitrate-nitrogen
concentrations hi excess of 10 mg/1. The data were divided into two groups: one group of
samples from wells located near the canning facility and another group from outside that area. A
correlation coefficient of R super(2) = 0.004 for Cl vs. NO sub(3)-N in the vicinity of the
irrigation fields indicates essentially no relationship between the source of Cl and NO sub(3). In
areas of agricultural and domestic activities located away from the cannery, an R super(2) of 0.54
suggests that Cl and NO sub(3) have common sources in these areas.
AN: 3692112
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Record 56 of 79 - Water Resources Abs. 1/93-4/98
TI: Ground-water nitrate contribution to Tampa Bay an investigation of the Lithia/Buckhorn
Springs nitrate problem.
AU: Jones,-G.W.; Upchurch,-S.B.
CF: 14. Annu. International Symposium of the North American Lake Management Society,
Orlando, FL (USA) 31 Oct-5 Nov 1994
SO: LAKE-RESERV.-MANAGE. 1994 vol. 9, no. 2, p. 85
AB: It has been determined that the Alafia River delivers approximately 705 tons of nitrate to
Tampa Bay each year. Lithia and Buckhorn Springs are two of the major sources of nitrate in the
Alafia River, contributing approximately 22 percent (157 tons/yr) of the total. Lithia and
Buckhorn Springs are among the most nitrate-rich springs in Florida with average nitrate as N
concentrations of 3.1 and 2.3 mg/1 respectively. Lithia Springs has experienced a 17-fold increase
in nitrate concentrations since 1923 while concentrations in Buckhorn Springs have increased
9-fold since 1966. Analysis of data collected during a two-year study indicates that water
discharging from the springs first enters the Floridian aquifer in the southern portion of an area
known as the Brandon Karst Terrain (BKT), an internally-drained karst escarpment in central
Hillsborough County. Nitrogen isotopic data from wells in this area and interpretation of
historical aerial photographs indicated that the principal source of nitrate was the concentrated
production of citrus that occurred for over 50 years. Numerous dairy farms in the area also
contributed nitrate albeit to a lesser degree. The citrus and diary farms in the BKT have gradually
been replaced over the last 25 years by suburban development. This suburban development has
resulted in the installation of over 11,000 septic tanks in the BKT. It is anticipated that within the
next 20 years, nitrate from agricultural sources will move out of the flow system and will be
replaced by nitrate from suburban sources that include septic tanks and landscape fertilizers.
AN: 3690133
Record 57 of 79 - Water Resources Abs. 1/93-4/98
TI: N-15 identification of nonpoint sources of nitrate contamination beneath cropland in the
Nebraska Panhandle: Two case studies.
AU: Exner,-M.E.; Spalding,-R.F.
SO: APPL.-GEOCHEM. 1994 vol. 9, no. 1, pp. 73-81
AB: Monitoring of municipal wells near the town of Sidney and domestic wells near Oshkosh in
Nebraska's Panhandle indicated the nitrate-nitrogen (NO sub(3)-N) levels were increasing and
exceeded the maximum contaminant level of 10 mg/1 NO sub(3)-N in several wells. Both areas
are located in narrow stream valleys that are characterized by well-drained soils, highly
permeable intermediate vadose zones, shallow depths to groundwater, and intensive irrigated
corn production. Both areas also have a large confined cattle feeding operation near the suspected
contamination and potentially could be contaminated by more than one nitrate source. At Sidney
NO sub(3)-N concentrations were measured in 13 monitoring wells installed along an east-west
transect in the direction of groundwater flow, 26 private wells, and eight municipal wells.
Nitrate-nitrogen concentrations were homogeneous beneath a 5 km by 1.2 km area and averaged
11.3 plus or minus 1.8 mg/1 NO sub(3)-N. The delta super(15)N-NO sub(3) values in the
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monitoring and municipal wells had a narrow range from +5.8 to +8.8ppt. The isotopic ratios are
indicative of a mixed source of nitrate contamination, which originates from agronomic
(commercial fertilizer N and mineralized N) N and animal waste. Both commercial fertilizer N
and animal wastes are applied to the irrigated fields.
AN: 3666372
Record 58 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrogen and phosphorus in water as related to environmental setting in Nebraska.
AU: Helgesen,-J.O.; Zelt,-R.B.; Stamer,-J.K.
SO: WATER-RESOUR.-BULL. 1994 vol. 30, no. 5, pp. 809-822
AB: Spatial distributions of nitrogen and phosphorus in water were related to environmental
setting as part of a regional water-quality assessment of the Central Nebraska Basins. The
environmental settings (Sandhills, Loess Hills, Glaciated Area, and Platte Valley) were
characterized by different concentrations of nitrogen and phosphorus in ground water and stream
water. Statistically significant differences in nitrate concentrations in both ground-water and
stream-water samples were related to regional distributions of cropland and rangeland. Nitrate
concentrations were larger, especially in shallow ground water, in environmental settings
dominated by cropland and associated fertilizer use than in settings dominated by rangeland.
Similarly, total-nitrogen and nitrate concentrations were relatively large in selected streams
draining primarily cropland. Comparative concentrations of phosphorus in stream water on the
basis of environmental setting were similar to those of nitrogen, although the largest phosphorus
concentrations probably relate to wastewater discharge into small streams. Nitrogen and
phosphorus concentrations in much of the Platte River apparently reflected the quality of water
entering the study unit from upstream and limited base-flow contributions from within the Platte
Valley itself.
AN: 3632977
Record 59 of 79 - Water Resources Abs. 1/93-4/98
TI: Ground water as a source of nutrients and atrazine to streams hi the South Platte River basin.
AU: McMahon,-P.B.; Litke,-D.W.; Paschal,-J.E.; Dennehy,-K.F.
SO: WATER-RESOUR.-BULL. 1994 vol. 30, no. 3, pp. 521-530
AB: Concentrations of nitrite plus nitrate, ammonia, orthophosphate, and atrazine were
measured hi streams and ground water beneath the streams at 23 sites in the South Platte River
basin of Colorado, Nebraska, and Wyoming to assess: (1) the role of ground water as a source of
nutrients and atrazine to streams in the basin, and (2) the effect of land-use setting on this
process. Concentrations of nitrite plus nitrate, ammonia, orthophosphate, and atrazine were
higher hi ground water than in the overlying streams at 2,12,12, and 3 of 19 sites, respectively,
where there was not a measurable hydraulic gradient directed from the stream to the ground
water. Orthophosphate was the only constituent that had a significantly higher (p < 0.05)
concentration hi ground water than in surface water for a given land-use setting (range land).
Redox conditions hi ground water were more important than land-use setting in influencing
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whether ground water was a source of elevated nitrite plus nitrate concentrations to streams in the
basin. The ratios of nitrite plus nitrate in ground water/surface were significantly lower (p < 0.05)
at site having concentrations of dissolved oxygen in ground water < 0.5 mg/L. Elevated
concentrations of ammonia or atrazine in ground water occurred at sites in close proximity to
likely sources of ammonia or atrazine, regardless of land-use setting. These results indicate that
land-use setting is not the only factor that influences whether ground water is a source of elevated
nutrient and atrazine concentrations to streams in the South Platte River Basin
AN: 36153-85
Record 60 of 79 - Water Resources Abs. 1/93-4/98
TI: Chemical use practices and opinions about groundwater contamination in two unsewered
subdivisions.
AU: Mechenich,-C.; Shaw,-B.H.
SO: J.-ENVIRON.-HEALTH 1994 vol. 56, no. 6, pp. 17-22
AB: Residents of two subdivisions with private wells and septic systems in central Wisconsin
were surveyed about use of various household and lawn chemicals and their opinions about
causes and severity of groundwater pollution problems. The overall response rate in the survey
was 78 percent. Of 139 homeowners surveyed, 109 reported fertilizing their lawns an average of
1.8 times per year. Commonly used lawn and garden insecticides included diazinon, malathion
and Sevin. Most commonly used household products were laundry detergent, toilet bowl cleaner,
and tub and tile cleaners. Residents of both subdivisions were fairly accurate in describing the
largest sources of groundwater contamination both in the county and in their own subdivisions.
Their greatest concerns about groundwater quality were nitrate and pesticide contamination.
Overall, 90 percent of participants were aware that individual homeowners may adversely affect
groundwater quality, and 87 percent believed that education is the most effective solution to
groundwater problems. Education needs for groundwater protection in these subdivisions include
regular water testing, record keeping on well depth, the potential interrelationships of wells and
septic systems in shallow groundwater systems, alternatives to hazardous household cleaning
products, and modifications of lawn care practices.
AN: 3588526
Record 61 of 79 - Water Resources Abs. 1/93-4/98
TI: Estimation of nitrate concentrations in groundwater using a whole farm nitrogen budget.
AU: Barry,-D.A.J.; Goorahoo,-D.; Goss,-M.J.
SO: J.-ENVIRON.-QUAL. 1993 vol. 22, no. 4, pp. 767-775
AB: Contamination of groundwater under agricultural land by NO sub(3) is influenced by the
kind of farming system. One possible method of selecting farming systems that result in less NO
sub(3) leaching is to calculate whole farm N budgets, that are simplified by assuming soil-N
remains constant from one cycle of a rotation to the next. This method was applied to two model
crop rotations using average crop yield data for two regions of Ontario, and to a cash-crop farm
and a dairy farm using information on purchases, sales, and crop yields, for these farms. The
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model rotations were corn (Zea mays L.)-soybean [Glycine max (L.) Merr.J-wheat (Triticum
aestivum L.) and corn-soybean-wheat-hay (mixture of timothy, Phleum pratense L. and alfalfa,
Medicago sativa L.)-hay-hay. Atmospheric deposition (18.4 kg N ha super(-l) yr) was obtained
by literature review. Symbiotic N sub(2) fixation by legume crops with different yields was
estimated from regression equations. A net surplus in the N balance was converted to maximum
mean NO sub(3)-N concentration in groundwater by assuming a groundwater recharge rate of
160 mm/yr, and no denitrification. Predicted NO sub(3)-N concentrations in leachate for the
model corn-soybean-wheat rotation were greater for southwestern Ontario (22.4 mg/L) than
western Ontario (8.5 mg/L), probably because more N fertilizer was recommended in the
southwest. Including hay hi the model rotation increased the amount of N leached by a factor of
two in western Ontario, but only by 9% in the southwest. Predicted NO sub(3)/N concentration in
groundwater for the cash crop farm was 6.7 mg/L, compared with an average measured value of
9.5 mg/L in the tile drainage water. For the dairy farm the predicted value was 58 mg L super(-l)
and a measured value was not available. The simplified N balance method provided useful
estimates of potential NO sub(3) leaching losses even though it relied on some major
assumptions. A major uncertainty was atmospheric deposition of ammonia volatilized from
on-farm sources. Denitrification could be as much as 62 kg N ha super(-l) yr super(-l) under
continuous production of grain corn, based on differences between N present after harvest and
amount of N leached.
AN: 3859591
Record 62 of 79 - Water Resources Abs. 1/93-4/98
TI: Hydrologic and land-use factors associated with herbicides and nitrate in near-surface
aquifers.
AU: Burkarts-M.R.; Kolpin,-D.W.
SO: J.-ENVIRON.-QUAL. 1993 vol. 22, no. 4, pp. 646-656
AB: Selected herbicides, atrazine (2-chloro-4-ethylamino- 6-isopropylamino-s-triazine)
metabolites, and NO sub(3) super(-) were examined in near-surface unconsolidated and bedrock
aquifers in the midcontinental USA to study the hydrogeologic, spatial, and seasonal distribution
of these contaminants. Groundwater samples were collected from 303 wells during the spring
and late summer of 1991. At least one herbicide or atrazine metabolite was detected in 24% of
the samples collected for herbicide analysis (reporting limit 0.05 mu g/L). No herbicide
concentration exceeded the USEPA's maximum contaminant level (MCL) or health advisory
level. The most frequently detected compound was the at razine metabolite deethylatrazine
[2-amino-4-chloro- 6-(isopropylamino)-s-triazine] followed by atrazine, deisopropylatrazine
[2-amino-4-chloro- 6-(ethylamhio)-s-triazine], prometon (2,4-bis(isopropylaniino)-
6-methyoxy-s-triazine), metolachlor [2-chloro-N- (2.ethyl-6-methylphenyl)-N-(2-methoxy-l
methylethyl)acetamide], alachlor [2-chloro-N-(2,6-diethylphenyl)-
N-(methoxymethyl)acetamide], metribuzin [4-amino-6-(tert-butyl)-
3-methylthio-as-triazme-5(4H)-one], simazine [2-chloro-4,6-bis(ethylamino)- s-triazine], and
cyanazine [2[[4-chloro-6-(ethylamino)-l,3,5-triazin- 2-yl]amino]-2-methylpropionitrile]. Nitrite
plus nitrate, as nitrogen (N), exceeding 3.0 mg/L (excess NO sub(3) super(-)), was found in 29%
of the samples, and 6% had sub(3) superQ exceeding the MCL of 10 mg/L. Ammonium as N
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was detected in excess of 0.01 mg/L in 78% of the samples. A nonlinear increase in the
frequency of atrazine detection occurred with decreases in reporting limit. The frequency of
atrazine residue detection (atrazine + deethylatrazine + deisopropylatrazine) was 25% greater
than for atrazine alone. Herbicide detections and excess NO sub(3) super(-) were notably lacking
in the eastern part of the study region where it was estimated that herbicide and fertilizer use
were among the largest in the region. Prometon, the second most frequently detected herbicide,
was associated with nonagricultural land use. Herbicide and excess NO sub(3) super(-) were '
more frequent in unconsolidated aquifers than in bedrock aquifers. Aquifer depth, as direct
measurement of proximity to recharge sources, was inversely related to frequency of herbicide
detection and excess NO sub(3) super(-).
AN: 3849070
Record 63 of 79 - Water Resources Abs. 1/93-4/98
TI: Chemical constituents in water from wells in the vicinity of the Naval Reactors Facility,
Idaho National Engineering Laboratory, Idaho, 1990-91.
AU: Bartholomay,-R.C.; Knobel,-L.L.; Tucker,-B J.
CA: Geological Surv., Idaho Falls, ID (USA)
SO: 1993.70pp.
RN: Rept. No: DOEID22106, USGSOFR9334
AB: The US Geological Survey, in response to a request from the US Department of Energy's
Pittsburgh Naval Reactors Office, Idaho Branch Office, sampled 12 wells as part of a long-term
project to monitor water quality of the Snake River Plain aquifer in the vicinity of the Naval
Reactors Facility, Idaho National Engineering Laboratory, Idaho. Water samples were analyzed
for manmade contaminants and naturally occurring constituents. Sixty samples were collected
from eight groundwater monitoring wells and four production wells. Ten quality-assurance
samples also were collected and analyzed. Most of the samples contained concentrations of total
sodium and dissolved anions that exceeded reporting levels. The predominant category of
nitrogen-bearing compounds was nitrite plus nitrate as nitrogen. Concentrations of total organic
carbon ranged from less than 0.1 to 2.2 milligrams per liter. Total phenols in 52 of 69 samples
ranged from 1 to 8 micrograms per liter. Extractable acid and base/neutral organic compounds
were detected in water from 16 of 69 samples. Concentrations of dissolved gross alpha- and
gross beta-particle radioactivity in all samples exceeded the reporting level. Radium-226
concentrations were greater than the reporting level in 63 of 68 samples.
AN: 3743773
Record 64 of 79 - Water Resources Abs. 1/93-4/98
TI: Impact of irrigation water use on water quality in the central Colorado water conservancy
district.
AU: Emond,-H.; Loftis,-J.C.; Podmore,-T.
SO: TECH.-REP.-COLO.-WATER-RESOUR.-RES.-INST. COLORADO STATE
UNIVERSITY, FORT COLLINS, CO 80523 (USA) COLORADO WATER RESOURCES
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RESEARCH INSTITUTE. 1993 22 pp.
RN: COMPLETION REPORT: 179
AB: This paper presents the results of a two year study sponsored by the Colorado Water
Resources Research Institute, the United States Geological Survey, and the United States
Environmental Protection Agency on the impact of irrigation water use on water quality in the
agricultural area near Greeley, Colorado. Data on water management techniques, consumptive
use, irrigation application efficiency, deep percolation, surface runoff and nitrate levels were
collected. Results indicated a wide range of application efficiencies and deep percolation
percentages. Nitrate levels in the pumped ground water often exceeded EPA drinking water
standards, while nitrate levels of water from the South Platte River were generally below the
drinking water standards. There are opportunities for improving irrigation application efficiency
in this area, but there may be repercussions for downstream water users. Decreasing the quantity
of nitrate going into the ground water can occur through increased water conservation and
through reducing the actual amount of nitrates applied in the irrigation water or fertilizers. There
is currently little incentive for farmers to implement these measures.
AN:. 3692807
Record 65 of 79 - Water Resources Abs. 1/93-4/98
TI: Spatial distribution of nitrate leaching "hot spots" and nitrate contributions to the South
Platte River Basin aquifers.
AU: Wylie,-B.K.; Wagner,-D.G.; Hoffer,-R.M.; Maxwell,-S.; Shaffer,-M.J.
SO: TECH.-REP.-COLORADO-WATER-RESOUR.-RES.-INST. COLORADO STATE
UNIVERSITY, FORT COLLINS, CO 80523 (USA) COLORADO WATER RESOURCES
RESEARCH INSTITUTE. 1993 26 pp.
RN: Completion Report: 181
AB: This project specifically addresses the issue of ground water quality in the South Platte
River Basin Aquifer due to nitrate contamination. Areas north and south of Greeley, Colorado,
currently have many wells supplying groundwater containing more than 10 ppm of nitrates. A
numerical model, the Nitrate Leaching and Economic Analysis Package (NLEAP) is used to
estimate nitrates leached (NL) from agricultural crop root zones by simulating weather, fertilizer
inputs, irrigation practices, evapotranspiration, soil types and a variety of other cropping
practices. Combining such a model with the spatial distribution of soils and cropping practices
within a geographic information system (GIS) framework allows the identification of the
geographical extent and spatial distribution of nitrate leaching "hot spots." Model runs were
correlated to groundwater NO sub(3)-N for 37 pumping irrigation wells within the study area for
the 1989-1991 growing seasons. The strongest single nitrate leaching factor correlated to
groundwater NO sub(3)-N concentrations was proximity-to-feedlots. Manuring practices or
inadequate crediting of manure-source nitrogen in determining fertilizer requirements are
possible causes of the importance of proximity-to-feedlots. The reason is unclear at this level of
analysis. Variation in NLEAP NL estimates associated with soil variability was the second
strongest leaching factor related to groundwater NO sub(3)-N concentration. Fertilizer
application rates varied as a function of organic matter in the soil and potential crop yields for
that soil. The combination of two nitrate leaching factors that gave the strongest correlations to
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ground-water NO sub(3)-N concentrations was proximity-to-feedlots and soils. Conclusions
reached from the research suggested that spatial variations in NLEAP simulated NL, associated
with proximity-to-feedlots, was related to groundwater NO sub(3)-N contamination in the study
area.
AN: 3673272
Record 66 of 79 - Water Resources Abs. 1/93-4/98
TI: Evaluation of surface irrigation systems near Greeley, Colorado.
AU: Emond,-H.; LoftisrJ.C.; Podmore,-T.H.; Roberts,-J.; Leaf,-F.
CF: 1993 South Platte Forum, Fort Collins, CO (USA) 27-28 Oct 1993
SO: SEEKING AN INTEGRATED APPROACH TO WATERSHED MANAGEMENT IN
THE SOUTH PLATTE BASIN. Klein,-K.C.; Williams,-D.J. (eds.) COLORADO STATE
UNIVERSITY, FORT COLLINS, CO 80523 (USA) COLORADO WATER RESOURCES
RESEARCH INSTITUTE. 1993 pp. 47-48.
AB: Sustainable agriculture and the minimizing of negative impacts by agriculture on the
environment, has been generating much interest lately. Particularly in northeastern Colorado,
there are concerns that return flows from irrigated agriculture are a source of pollution to ground
water and surface water. Excess irrigation water not stored in the root zone for beneficial crop
use can result in deep percolation below the crop root zone or surface runoff. This excess water is
free to transport fertilizers and pesticides to the ground water and surface water downstream of
the irrigation, possibly contributing to the degradation of water quality. In a study on sustainable
agriculture by the Central Colorado Water Conservancy District of Greeley, Colorado .and funded
by the Environmental Protection Agency, a field team from Colorado State University conducted
on-farm monitoring of irrigation water use and water quality. The monitoring study is helping to
identify the pollution potential of current irrigation practices in the South Platte Basin. The CSU
team intensively monitored three surface fields during the summer of 1992 and 1993. A mass
balance approach was used to quantify the water inputs to selected fields and the amount of water
lost to deep percolation and surface runoff. The amount of water applied to individual fields and
the amount of water running off were monitored. The quantity of water used by the plants was
estimated using a reference evapotranspiration equation and weather data. The relative loss from
deep percolation was calculated. Irrigation application efficiency, tail water ratio and deep
percolation ratio were calculated. The nitrate level, of concern for health considerations, was
regularly tested in the irrigation pump water and surface water. The range of irrigation
application efficiencies measured for the surface irrigated fields was surprisingly wide, ranging
from 7% to 67%. The resulting deep percolation for the three fields indicates how leaching of
nitrates to the ground water might be affected by this wide range of efficiencies. Although low
application efficiencies suggest an opportunity to improve irrigation system performance and
reduce nitrate leaching, downstream users of the South Platte River are dependant upon irrigation
return flows for late season irrigation. Further analyses of water use, water quality and transport
processes of pollutants in the soil are needed to make recommendations regarding measures to
improve ground water quality.
AN: 3661161
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Record 67 of 79 - Water Resources Abs. 1/93-4/98
TI: Regional evaluation of Hie alluvial groundwater quality of the South Platte Basin from
Denver to Greeley, Colorado.
AU: Leaf,-F.A.; Leaf,-C.F.
CF: 1993 South Platte Forum, Fort Collins, CO (USA) 27-28 Oct 1993
SO: SEEKING AN INTEGRATED APPROACH TO WATERSHED MANAGEMENT IN
THE SOUTH PLATTE BASIN. Klein,-K.C.; Williams,-D.J. (eds.) COLORADO STATE
UNIVERSITY, FORT COLLINS, CO 80523 (USA) COLORADO WATER RESOURCES
RESEARCH INSTITUTE. 1993 p. 39.
AB: A regional water balance was simulated for the period 1950-1988 for the reach of the South
Platte River from Denver to Greeley. This area includes a total of 259,100 acres in southeastern
Weld County, of which 150,400 acres is overly alluvial material and 135,400 acres is irrigated
cropland. The average annual inflow for the period simulated totaled 915,000 acre-feet and the
average outflow totaled 922,000 acre-feet. Average precipitation and potential crop
evapotranspiration for the study area totaled 178,000 and 288,00 acre-feet respectively. The
annual crop water requirement for the study area supplied through the conjunctive use of
groundwater and surface water, averaged 190,100 acre-feet. Average alluvial groundwater
storage totaled 2.02 million acre-feet and experienced no appreciable change in storage for the 39
years studied. Average groundwater nitrate - nitrogen (NO sub(3)-N) concentrations have
increased approximately 7.9 milligrams per liter from the mid 1950's to the late 1980's. For the
same period, the area-weighted average increase was 8.2 mg/1 NO sub(3)-N. This increase in NO
sub(3)-N concentration is attributed to agricultural and other land use practices. The net
area-weighted annual impact to the groundwater resource in the study area is 9.14 pounds per
acre nitrate - nitrogen. This corresponds to an average annual increase in groundwater nitrate -
nitrogen concentration of 0.25 milligrams per liter from 1958 -1990.
AN: 3661156
Record 68 of 79 - Water Resources Abs. 1/93-4/98
TI: Origin and fate of high nitrate concentrations in water from the South Platte River alluvial
aquifer-preliminary results.
AU: McMahon,-P.B.; Bruce,-B.; Dennehy,-K.F.
CF: 1993 South Platte Forum, Fort Collins, CO (USA) 27-28 Oct 1993
SO: SEEKING AN INTEGRATED APPROACH TO WATERSHED MANAGEMENT IN
THE SOUTH PLATTE BASIN. Klein,-K.C.; Williams,-D.J. (eds.) COLORADO STATE
UNIVERSITY, FORT COLLINS, CO 80523 (USA) COLORADO WATER RESOURCES
RESEARCH INSTITUTE. 1993 p. 38.
AB: Data for the areal and vertical distribution of dissolved nitrate and related compounds in
water from the South Platte River alluvial aquifer were used to determine the origin and fate of
high nitrate concentrations in water from a part of the aquifer underlying an area of intensive
irrigated agriculture between Platteville and Greeley, Colorado. Nitrate concentrations at the
water table varied areally from < 0.5 to 47 milligrams per liter as nitrogen, and average nitrate
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concentrations were higher in aerobic water underlying agricultural fields (22.6 plus or minus
12.3 milligrams per liter) than in anaerobic water underlying the river (6.2 plus or minus 4.2
mg/L). There was no apparent relation between nitrate concentration and depth. Values of delta
super(15)N for dissolved nitrate in aerobic water underlying fields (11.0 plus or minus 2.3 per
mil) were consistent with an. animal-waste source for the nitrate. Heavier delta super(15)N
values for dissolved nitrate in anaerobic water underlying the river (17.6 plus or minus 2.1 per
mil) and the lower nitrate concentrations in water underlying the river indicate that microbial
denitrification in the anaerobic part of the aquifer lowered nitrate concentrations, leaving the
residual nitrate enriched in super(15)N prior to ground-water discharge to the river. Further
evidence for microbial denitrification in the aquifer included a buildup of N sub(2) and N
sub(2)O gases, both products of dentrification, in anaerobic water from the aquifer. These results
may have important consequences for agricultural nitrate-management practices and aquatic
biological assessments in the study area.
AN: 3661155 .
Record 69 of 79 - Water Resources Abs. 1/93-4/98
TI: Trinity River Basin, Texas.
AU: Ulery,-R.L.; Van-Metre,-P.C.; Crossfield,-A.S.
SO: WATER-RESOUR.-BULL. 1993 vol. 29, no. 4, pp. 685-712
AB: In 1991 the Trinity River Basin National Water-Quality Assessment (NAWQA) was' among
the first 20 study units to begin investigations under full-scale program implementation. The
study-unit investigations will include assessments of surface-water and ground-water quality.
Initial efforts have focused on identifying water-quality issues in the basin and on the
environmental factors underlying those issues. The environmental setting consists of both
physical and cultural factors. Physical characteristics described include climate, geology, soils,
vegetation, physiography, and hydrology. Cultural characteristics discussed include population
distribution, land use and land cover, agricultural practices, water use, and reservoir operations.
Major water-quality categories are identified and some of the implications of the environmental
factors for water quality are presented.
AN: 3509148
Record 70 of 79 - Water Resources Abs, 1/93-4/98
TI: Effect of forested wetlands on nitrate concentrations in ground water and surface water on
the Delmarva Peninsula.
AU: Phillips,-PJ.; Denver,-J.M.; Shedlock,-RJ.; Hamilton,-P.A.
SO: WETLANDS 1993 vol. 13, no. 2, spec, iss., pp. 75-83
AB: The Delmarva Peninsula is an extensively farmed region in which nitrate from commercial
fertilizers and poultry has entered the ground water and streams. The peninsula contains forested
wetlands in a variety of settings, and their size and location are a result of the surrounding
hydrologic and soil conditions. Three regions, here referred to as hydrogeomorphic regions, were
selected for study. Each region has characteristic geologic and geomorphic features, soils,
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drainage patterns, and distribution of farmland, forests, and forested wetlands. In all three
regions, forested wetlands generally occupy poorly drained areas whereas farmlands generally
occupy well-drained areas. The three hydrogeomorphic regions studied are the well-drained
uplands, the poorly drained uplands, and the surficial-confined region. The well-drained uplands
have the largest amount of farmland and the smallest amount of forested wetlands of the three
regions; here the forested wetlands are generally restricted to narrow riparian zones. The poorly
drained uplands contain forested wetlands in headwater depressions and riparian zones that are
interspersed among well-drained farmlands. The surficial-confined region has the smallest
amount of farmland and largest amount of forested wetlands of the three regions studied.
Wetlands in this region occupy the same topographic settings as in the poorly drained uplands.
Much of the farmland in the surficial-confined region was previously wetland. Nitrate
concentrations in ground water and surface water on the peninsula range widely, and their
distribution reflects (1) the interspersion of forests among farmland, (2) hydrogeologic
conditions, (3) types of soils, and (4) the ground-water hydrology of forested wetlands. The
well-drained uplands had higher median nitrate concentrations in ground water than the poorly
drained uplands or the surficial-confined region. The highest nitrate concentrations were in oxic
parts of the aquifer, which are beneath well-drained soils that are farmed, and the lowest were in
anoxic parts of the aquifer, which are beneath poorly drained soils overlain by forested wetlands.
The effect of forested wetlands on water quality depends on the hydrogeologic conditions, extent
of farming, and type of soils. The three regions contain differing combinations of these factors
and thus are useful for isolating the effects of forested wetlands on water quality.
AN: 2995987
Record 71 of 79 - Water Resources Abs. 1/93-4/98
TT: Occurrence of Nitrate in Groundwater A Review.
AU: Spalding,-R.-F.; Exner,-M.-E.
SO: Journal of Environmental Quality JEVQAA,-Vol. 22, No. 3, p 392-402, July/September
1993. 7 fig, 88 ref.
AB: The results of federal, state, and local surveys, which included more than 200,000 NO3-N
data points, are summarized in this review of NO3 in groundwater in the USA. The levels of
NO3-N are associated with source availability and regional environmental factors. In regions
where well-drained soils are dominated by irrigated cropland, there is a strong propensity toward
the development of large areas with groundwater that exceeds the maximum contaminant level of
10 mg/L NO3-N. Most of these areas are west of the Missouri River where irrigation is a
necessity. Aquifers in highly agricultural areas in the southeastern USA reportedly are not
contaminated. Vegetative uptake and denitrification in this warm, wet, C-rich environment are
responsible for the natural remediation of NO3 in shallow aquifers. In the Middle Atlantic states
and the Delmarva Peninsula, localized contamination occurs beneath cropped, well-drained soils
that receive excessive applications of manure and commercial fertilizer. Extensive tile drainage
has for the most part prevented a NO3 problem in the groundwater of the Corn Belt states.
Throughout the USA there are recurring themes. They include a decrease in NO3-N levels with
depth; lower NO3-N levels hi shallow wells (<8 m); and a significant increase in NO3-N in older
wells and in wells with poor construction. The factors affecting the distribution of NO3 in
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aquifers are complex and poorly understood. Interdisciplinary studies using discrete depth
sampling, geohydrological indicators, isotopic tracers, and microbiological techniques are
necessary to unravel the complex dynamics. (Author's abstract) 35 012605040
AN: 9309694
Record 72 of 79 - Water Resources Abs. 1/93-4/98
TI:. Small Treatment Systems and Alternative Sewers.
AU: Jantrania,-A.-R. ;
SO: Water Environment Research, Vol. 65, No. 6, p 349-353, June 1993. 46 ref.
AB: The U.S. Environmental Protection Agency has published a manual that details wastewater
treatment and disposal systems for small communities. Wastewater reuse for non-potable
purposes is also offered as an attractive option for small communities. Septic systems can be
used as a wastewater treatment option in small communities. Different soils, peat and gravel
chambers have been tested for septic systems. Land treatment and spray or drip irrigation systems
have been tried for domestic wastewater treatment. A low-pressure distribution system was
developed for on-site disposal of wastewater. Septic management is often regulated and
monitored in many communities. Groundwater monitoring is done to determine if septage causes
nitrate or bacterial contamination of groundwater. Wetland wastewater treatment allows
management of wastewater in many small communities. Waste stabilization ponds have also
been studied for wastewater treatment in small communities. Sewerage systems for small
communities have been studied in regard to gas and!odor emission, pipe corrosion, vacuum
sewers, and gravity sewers. (Geiger-PTT)
AN: 9309565
Record 73 of 79 - Water Resources Abs. 1/93-4/98
Record 74 of 79 - Water Resources Abs. 1/93-4/98
TI: Nutrient Flux Through Soils and Aquifers to the Coastal Zone of Guam (Mariana Islands).
AU: Matson,-E.-A.
SO: Limnology and Oceanography LIOCAH, Vol. 38, No. 2, p 361-371, March 1993. 10 fig, 5
tab, 33 ref. .
AB: Nitrification enriches terrestrial soil waters with nitrate, and other solutes also leach rapidly
(within hours to days after saturating rain) through Guam's northern karst plateau into a largely
unconfined carbonate aquifer system. Nutrient chemistry and discharge of these enriched aquifer
waters into the inter- and subtidal zone was measured to evaluate the importance of this flux to
the coastal nutrient regime of the island. Aquifer waters mix with seawater in the coastal
transition zone, produce about a 10% seawater mixture, leak year-round through cracks and
fissures and from seeps in beaches around the entire perimeter (57 km) at rates of 2.2-110 cu m
(m of shoreline)/d (avg, 5.1 cu m/m/d). The theoretical maximum rate can average 14 cu m/m/d,
which is equal to net annual aquifer recharge. At the shoreline, the discharged aquifer waters
average 3.14 ppt salinity, 96+/-21 microM NO3(-), 28+/-6.S microM Si, 0.85+/-0.26 microM P,
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and 0.18+/-0.19 microM Fe. Deep seawater under the aquifer averages 33.8 ppm salinity,
8.5+/-2.1 microMNO3(-), 7.2+/-1.8 microM Si, and 0.05+/-0.04 microM Fe. The aquifer system
can potentially discharge 1,340 microM NO3(-)/sq m/d, 390 microM Si/sq m/d, 12 microM P/sq
m/d, and 2.5 microM Fe/sq m/d, out to a distance of 1 km from shore, which enriches surface
seawater by about 20 times the ambient concentration per day. In-general, natural flux of nutrient
in aquifer waters from tropical carbonate islands will increase as a function of island diameter,
aquifer recharge, head, the thickness of the soil layers in which remineralization occurs, and as
the acquisition of solutes from subterranean volcanics above sea level increases. (Author's
abstract)
AN: 9307679
Record 75 of 79 - Water Resources Abs. 1/93-4/98
TI: Physiographic and Land Use Characteristics Associated with Nitrate-Nitrogen in Montana
Groundwater.
AU: Bauder,-J.-W.; Sinclair,-K.-N.; Lund,-R.-E.
SO: Journal of Environmental Quality JEVQAA, Vol. 22, No. 2, p 255-262, April/June 1993. 2
fig, 6 tab, 16 ref.
AB: Occurrence of NO3(-)-N in drinking water at concentrations >10 mg/L is being reported in
the literature with increasing frequency. Some occurrences of high NO3(-)-N concentrations have
been attributed to irrigation and fertilization practices. A private well water testing program in
Montana, involving nearly 3400 well owners, found NO3(-)-N concentrations >10 mg/L in
nearly 6% of all tested wells. Most of the agricultural land in Montana is nonirrigated and is not
subject to high rates of N fertilization. Dryland crop/fallow cereal grain rotations are the main
practices. Well water test results were combined with MAPs, a geographic information system
(GIS), to identify correlations between county average NO3(-)-N concentration in groundwater,
well water sample probability of exceeding 10 mg/LNO3(-)-N, geographic, climatic, and
geologic conditions, and land use practices. From a list of 67 independent variables, county
average well water NO3(-)-N concentration >10 mg/L were correlated with 16 independent
variables, most of which were associated with precipitation, soil properties, and land use
practices. The closest correlations were March 1 through June 30 precipitation, distribution of
dryland crop production and summer fallow, soil water holding capacity, and mapping units of
the general soil map of Montana. Two-, three-, and four-variable, linear, multiple regression
models indicated that 53% to 61% of the variability in county average well sample NO3(-)-N
concentration would be accounted for by these independent variables. Results of these analyses
support the hypothesis that summer fallow practices and associated mineralization of organic
matter may be contributing to regionalized NO3(-)-N contamination of shallow groundwater in
Montana. (Author's abstract) 35 012306044
AN: 9307574
Record 76 of 79 - Water Resources Abs. 1/93-4/98
TI: A Survey of Lead, Nitrate and Radon Contamination of Private Individual Water Systems in
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Pennsylvania.
AU: Swistock,-B.-R.; Sharpe,-W.-K; Robillard,-P.-D.
SO: Journal of Environmental Health JEVHAH, Vol. 55, No. 5, p 6-12, March 1993 8 fig 39
ref.
AB: Private individual water systems throughout Pennsylvania were sampled for dissolved lead,
nitrate-N and radon to determine the prevalence of these primary pollutants. Approximately
1,600 sources were tested for lead and nitrate and 989 were tested for radon. Twenty-eight
percent of sampled homes had lead concentrations above 10 microg/L and 19% were above 15
microg/L. These percentages increased to 50 and 34% respectively when calculated total
(digested) lead data were used, suggesting that total lead analysis may be appropriate even when
dealing with relatively clear, low turbidity samples. Nitrate contamination was less prevalent and
more regional than lead. Nine percent of sampled homes contained nitrate-N above 10 mg/L with
nearly all (96%) of these homes located in the agricultural south-central and southeastern regions
of the state. Nearly 80% of the groundwater wells tested contained radon concentrations above
the proposed maximum contaminant level of 300 pCi/L. Excessive radon concentrations existed
in all regions of the state but were most prevalent in the eastern regions near the Reading Prong
geologic formation. (Author's abstract) 35 009222081
AN: 9306542
Record 77 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrate Contamination of Private Well Water in Iowa.
AU: Kross,-B.-C.; Hallberg.-G.-R.; Bruner,-D.-R.; Cherryholmes,-K.; Johnson,-J.-K.
SO: American Journal of Public Health AJHEAA, Vol. 83, No. 2, p 270-272, February 1993. 1
fig, 2 tab, 21 ref.
AB: The State-Wide Rural Well-Water Survey conducted in Iowa between April 1988 and June
1989 revealed that about 18% of the state's private, rural drinking water wells contain nitrate
above the recommended health advisory level of 10 mg/L. Thirty-seven percent of the wells have
levels greater than 3 mg/L, typically considered indicative of anthropogenic pollution. Thirty-
five percent of wells < 15 m deep exceed the health advisory level, and the mean concentration of
nitrate-nitrogen for these wells exceeds 10 mg/L. The depth of the well was the best predictor of
well water contamination. Individually, NO3-N levels of > 10 mg/L occurred alone in about 4%
of the private wells statewide; pesticides were present alone in about 5%. Total coliform
positives occurred alone at 27% of the sites. In a cumulative sense, nitrates, pesticides, and
coliform positives were detected in nearly 55% of rural private water supplies. High nitrate levels
have been associated with increased risks for birth defects or cancer in humans in several studies.
The high nitrate levels in groundwater in Iowa have been attributed to agricultural runoff in areas
with high fertilizer and manure use. It is recommended that normal prenatal care for rural patients
should include well testing fo r nitrates, and use of safer water for the preparation of infant
formulas where high nitrate levels are detected. Routine monitoring of wells used for drinking
water is also recommended along with the implementation of groundwater protection strategies,
such as sustainable agriculture practices. (Geiger-PTT)
AN: 9306113
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Record 78 of 79 - Water Resources Abs. 1/93-4/98
TI: Nitrogen Isotopes as Indicators of Nitrate Sources in Minnesota Sand-Plain Aquifers.
AU: Komor,-S.-C.; Anderson,-H.-W.
SO: Ground Water GRWAAP, Vol. 31, No. 2, p 260-270, March/April 1993.6 fig, 1 tab, 31 ref.
AB: Nitrate concentrations in excess of national drinking- water standards (10 mg/L as N) are
present in certain sand- plain aquifers in central Minnesota. To investigate nitrate sources in the
aquifers, nitrogen-isotope values of nitrate (delta-15N NO3) were measure d in shallow
groundwater from 51 wells in five land-use settings. The land-use settings and corresponding
average nitrate concentrations (as N) and delta-15N NO3 values were: livestock feedlots, 12.7
mg/L, 21. 3 ppt; cultivated-irrigated fields, 13 mg/L, 7.4 ppt; residential area with septic systems,
8.3 mg/L, 6.0 ppt; non-irrigated cultivated fields, 15.5 mg/L, 3.4 ppt; and natural, undeveloped
areas, 3.8 mg/L, 3.1 ppt. Values of delta-15N NO3 less than 2 ppt suggest that nitrogen from
commercial inorganic fertilizers exists hi groundwater beneath all settings except the feedlots.
Values of delta- 15NNO3 greater than 10 ppt suggest that nitrogen from animal waste is present
in groundwater beneath certain feedlots, cultivated-irrigated fields that are fertilized with manure,
and residential areas with septic systems. Values of delta-15N NO3 between 22 and 43 ppt in
groundwater beneath the feedlots probably result from denitrification. Values of delta-15N NO3
increase with depth in many locations in the sand-plain aquifers. These increases may be caused
by progressive denitrification with depth or by changes with depth in the proportions of nitrate
from different sources. Similarly, variations of delta-15N NO3 values from 1986 to 1987 in
certain locations may be due to temporal variations in the amounts of denitrification or to
changes in the proportions of nitrate from different sources. Ambiguities in the interpretation of
changes in delta-15N NO3 values could be eliminated by increasing the spatial and temporal
frequency of sampling. (Author's abstract)
AN: 9305470
Record 79 of 79 - Water Resources Abs. 1/93-4/98
TI: Stable Isotopes of Oxygen and Nitrogen in Source Identification of Nitrate from Septic
Systems.
AU: Aravena,-R.; Evans,-M.-L.; Cherry,-J.-A.
SO: Ground Water GRWAAP, Vol. 31, No. 2, p 180-186, March/April 1993. 4 fig, 40 ref.
AB: Stable isotopes, 15N and ISO, were used as tracers to differentiate a contaminant nitrate
plume emanating from a single domestic septic system, in a groundwater system characterized by
high and similar nitrate content outside and inside the contaminant plume. A good delineatio n of
the nitrate plume of septic origin was obtained using analysis of 15N in nitrate. The 15N content
of the non-plume nitrate is in agreement with the sources of nitrate (solid cattle manure, synthetic
fertilizer (NH4-NO3), and soil organic nitrogen) at the study site. 18-Oxygen analysis in nitrate
did not provide enough isotopic contrast to permit separation of nitrate derived from the septic
system and that in the surrounding groundwater, derived from agricultural fertilizer sources.
Thus, the ISO data indicated that nitrification of ammonium is the main process responsible for
formation of nitrate at the study site. Nonetheless, the ISO in groundwater clearly delineated the
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groundwater plume associated with the septic system; this suggests that this tracer should be
considered in studies related with contaminant plumes of different origin. (Author's abstract)
AN: 9305461
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