Wayne Lapham, U.S. Geological Survey Presentation given during the USGS/IAEA/IW:LEARN groundwater learning exchange in the US April 14-26, 2007.

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GROUND-WATER QUALITY STUDIES:GROUND-WATER QUALITY STUDIES:
U.S. EXAMPLEU.S. EXAMPLE
Wayne Lapham, U.S. Geological SurveyWayne Lapham, U.S. Geological Survey

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USGS National Water-QualityUSGS National Water-Quality
Assessment (NAWQA)Assessment (NAWQA)
Program ExampleProgram Example

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National Water-Quality AssessmentNational Water-Quality Assessment
Program Ground-Water StudyProgram Ground-Water Study
ObjectivesObjectives
(1)(1) Ground-Water Quality: OccurrenceGround-Water Quality: Occurrence
and Distribution.and Distribution.
(2) Trends in Ground-Water Quality.(2) Trends in Ground-Water Quality.
(3) Understanding of Occurrence &(3) Understanding of Occurrence &
Distribution and of Trends inDistribution and of Trends in
Ground-Water Quality.Ground-Water Quality.

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4 Examples of Occurrence &4 Examples of Occurrence &
Distribution QuestionsDistribution Questions
• What compounds are present & not present inWhat compounds are present & not present in
ground water?ground water?
• Where are compounds found & not found?Where are compounds found & not found?
• At what concentrations & frequencies ofAt what concentrations & frequencies of
detection?detection?
• What types of mixtures of compounds areWhat types of mixtures of compounds are
found?found?

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3 Examples of Trends Questions3 Examples of Trends Questions
• What are the long-term changes and trends inWhat are the long-term changes and trends in
ground-water quality and why?ground-water quality and why?
- What have been the historic trends?What have been the historic trends?
- What are the current trends?What are the current trends?
- What will be future trends under variousWhat will be future trends under various
management scenarios ?management scenarios ?

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1 Example of Understanding1 Example of Understanding
QuestionsQuestions
• What are the factors that govern ground-What are the factors that govern ground-
water quality?water quality?
• Hydrogeologic factors (confined vs unconfined,Hydrogeologic factors (confined vs unconfined,
etc).etc).
• Land-use factors (agriculture, urbanization, etc).Land-use factors (agriculture, urbanization, etc).
• Natural factors (aquifer mineralogy, etc).Natural factors (aquifer mineralogy, etc).
• Geochemical conditions (percent organic carbon,Geochemical conditions (percent organic carbon,
dissolved oxygen concentrations, redox, etc).dissolved oxygen concentrations, redox, etc).
• Climatic factors (precipitationClimatic factors (precipitation  aquifer recharge,aquifer recharge,
etc).etc).

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National Water-Quality AssessmentNational Water-Quality Assessment
Program Ground-Water StudyProgram Ground-Water Study
ApproachApproach
3 Design Concepts used to meet3 Design Concepts used to meet
the 3 objectives at multiplethe 3 objectives at multiple
scales (Local, Regional &scales (Local, Regional &
National)National)

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3 Design Concepts Applied to NAWQA3 Design Concepts Applied to NAWQA
Water-Quality AssessmentsWater-Quality Assessments
1. Local multiple-scale, nested
studies.
2. Consistent design of all local-
scale studies.
3. Consistent approaches to
conducting local-scale studies.

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Main MessageMain Message
These 3 design concepts (multi-scale, nested
studies, consistent designs, consistent approaches) enable
(1) Local assessments of Ground-Water
Quality.
(2) Ability to combine local findings (or
data) into Regional & National Water-
Quality Assessments.

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What Aquifers To Study & Where?

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Aquifers Studied – Selection CriteriaAquifers Studied – Selection Criteria
• Select from 62 Principal Aquifers.
• Select Principal Aquifers with largest withdrawals for
drinking-water.
• Include representation of all major aquifer lithologies.
• Ensure geographic distribution across the U.S.
• Include Principal Aquifers with largest areal extents.

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Aquifers Studied – Results of Selection Given FundsAquifers Studied – Results of Selection Given Funds
AvailableAvailable
• About 1/3 of the 62 Principal Aquifers currently being studied.
• Provides a framework for regional studies.
• Each regional assessment focuses on specific issue(s) of concern.
• Local multi-scale, nested studies in each Principal Aquifer.

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3 Design Concepts for Multi-Scale3 Design Concepts for Multi-Scale
QW AssessmentQW Assessment
1. Local multiple-scale, nested
studies.
2. Consistent design of local studies.
3. Consistent approaches to
conducting local studies.

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Key Design Element: Nested, Multiple-Scale
Studies – Example: High Plains aquifer

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Key Design Element: Nested, Multiple-Scale
Studies – Example: High Plains aquifer
Each scale of studyEach scale of study
has a differenthas a different
objective.objective.
Multiple, nestedMultiple, nested
studies in an aquiferstudies in an aquifer
provide findings thatprovide findings that
can be collectivelycan be collectively
used to characterizeused to characterize
and understandand understand
Ground-WaterGround-Water
Quality in an aquifer.Quality in an aquifer.

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Three design concepts for multi-Three design concepts for multi-
scale QW assessmentscale QW assessment
1. Local multiple-scale, nested
studies.
2. Consistent design of local studies.
3. Consistent approaches to
conducting local studies.

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Consistent Design of Nested, Multiple-Scale
Studies in Each Principal Aquifer
Similar studiesSimilar studies
are done inare done in
each of the ~20each of the ~20
PrincipalPrincipal
AquifersAquifers
across the U.S.across the U.S.

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Consistent Study DesignsConsistent Study Designs
Local scale: Aquifer
studies in about 40 areas
(called “study units”).
Regional scale: Summaries
in ~20 principal aquifers.
National scale: National
summaries using all
studies from all Principal
Aquifers.

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Three design concepts for multi-Three design concepts for multi-
scale QW assessmentscale QW assessment
1. Local multiple-scale, nested
studies.
2. Consistent design of local studies.
3. Consistent approaches to
conducting local studies.

20. Consistent approaches to conductingConsistent approaches to conducting
these studiesthese studies
• Water-quality constituents measured.
• Sample collection procedures and
laboratory analyses.
• Laboratory & field quality assurance.
• Ancillary data collected.
• Data in one common data base.
• Analysis procedures.

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Consistent approachesConsistent approaches
• The same water-quality constituents
measured
• For example, NAWQA measures the following in
its studies . . .
– Temp, Specific Conductance, Dissolved Oxygen, pH,
Turbidity
– Major inorganics
– Nutrients
– Pesticides
– Volatile Orgainc Compounds
– Trace Elements
– Microbial indicators (coliform, E coli)

22. Consistent approachesConsistent approaches
• Sample collection procedures are the
same
– All sampling crews receive training in
QW sampling.
– All sampling crews are taught the same
sampling procedures.
– National Field Manual used by all
sampling crews.
– QC samples collected when sampling.

23. Consistent approachesConsistent approaches
• Common Laboratory & Field Quality
Assurance are applied
– One laboratory used for analyses.
– Same laboratory methods applied.
– Standard laboratory Quality Assurance -
Quality Control procedures.
– Testing of field office lab performance using
blind sample testing.
– Headquarters staff visits to field laboratories.
– etc.

24. Consistent approachesConsistent approaches
• National-scale ancillary data
compiled from national coverages
– Population served.
– Climatic data.
– Soil characteristics.
– etc
• Consistent local-scale ancillary data also
collected
– Land-use & land-cover around wells.
– County-level pesticide and fertilizer application rates.
– Septic tank density.
– etc

25. Consistent approachesConsistent approaches
• Data stored in a National Data Base (U.S.
Geological Survey National Water
Information System)
– QWDATA (QW analyses, etc )
– GROUND-WATER SITE INVENTORY
(well-characteristics information, etc )
– WATER USE (water withdrawals, population
served, inter-basin water transfers, etc)

26. Consistent approachesConsistent approaches
• Common analyses and interpretation
techniques are applied
– Same approaches to check & verify water-
quality data.
– Same approaches to censor water-quality data
during analysis & interpretation.
– Similar statistical approaches.
– Similar graphical and tabular displays of data
& results.
– Etc.

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SUMMARY: National Water-QualitySUMMARY: National Water-Quality
Assessment Program Ground-WaterAssessment Program Ground-Water
Study ObjectivesStudy Objectives
(1)(1) Ground-Water Quality: OccurrenceGround-Water Quality: Occurrence
and Distribution.and Distribution.
(2) Trends in Ground-Water Quality.(2) Trends in Ground-Water Quality.
(3) Understanding of Occurrence &(3) Understanding of Occurrence &
Distribution and of Trends inDistribution and of Trends in
Ground-Water Quality.Ground-Water Quality.

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SUMMARY: Main MessageSUMMARY: Main Message
3 design concepts -> multi-scale, nested studies;
consistent designs; & consistent approaches
(1) Local assessments of Ground-Water Quality.
(2) Ability to combine local findings (or data) into
Regional & National Assessments.