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2
NAWQA Design Evaluation
INTRODUCTION
As discussed in the previous chapter, the scope of a truly na-
tional water quality assessment is enormous, both in scale and
complexity. Hence, it is essential that the scope of NAWQA be
defined judiciously in recognition of the overall budgetary con-
straints, the organizational strength of the USGS, and the salient
characteristics of the physical and cultural systems that define
water quality. This chapter contains an evaluation of the design
of the NAWQA program components, including integration of the
surface water and ground water study units, how study units were
selected, the general exclusion of lakes and estuaries from the
study plan, the sampling design program, data collection methods,
the choice of chemical and biological constituents, quality as-
surance/quality control aspects, data management, the analytical
framework of the program, and products of the NAWQA program.
Integration of Ground Water and
Surface Water Description
The original concept specified 123 separate surface water and
ground water study units: 69 surface water and 54 ground water.
A major difficulty with the "separate" approach is that it had the
potential for missing the important linkages between surface water
and ground water systems--linkages that can have profound effects
on the water quality of both systems. As the pilot programs pro-
ceeded, it became apparent to the committee and to the USGS that
the integrated approach was more beneficial. Some of the pilot
programs provide good examples of the importance of incorpora-
ting surface water and ground water interactions into water qual-
ity studies.
26
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NAWQA Design Evaluation
27
For example, in the Delmarva Peninsula pilot project--a ground
water investigation--pesticides have caused some contamination of
surface water and shallow ground waters. The pilot project used
transects of shallow wells installed adjacent to streams to track the
infiltration of pesticides from agricultural lands down to the water
table and from there into streams. The pilot project in the lower
Kansas River basin--a surface water investigation--perhaps best
exemplifies the importance of the integrated approach. Along the
Kansas River, considerable interchange of water occurs between
the river and its alluvial aquifer. During high flows, the river re-
charges the aquifer, during low flows, base flow from the aquifer
contributes an estimated 1 to 4 cubic feet per second of flow per
river mile (Fader, 1974~. The exchange of water probably has a
significant effect on ground water and surface water quality,
although the effects were not known at the inception of the study.
In the Blue River basin near the Kansas-Nebraska state line,
streamflow depletion by wells is about two orders of magnitude
greater than that predicted by an analog model in the early 1960s
(Alley and Emery, MY. in the nor~nwes~ern per o~ `~; Buy
unit (the upper Big Blue River and Little Blue River in Nebraska),
the interaction between the streams and the aquifers is great. In
dry periods, discharge from the High Plains aquifer sustains these
streams. Irrigation return flow from the extensive croplands
undoubtedly contributes to the relatively high specific conductance
found downstream in the Kansas River; the sulfate ion is a major
offender. Similarly, the use of nitrogen fertilizers may contribute
to the upward trend in nitrite and nitrate levels in the Big Blue
River; a major pathway could be base flow to the river.
Ground water and surface water interaction is also important
in some portions of the Central Oklahoma aquifer study unit; this
was known prior to the inception of the pilot project. However,
the spatial distribution of this interaction was different from that
which was previously believed. Prior to the onset of the pilot
project, the USGS team thought that most interaction occurred near
the major streams, the Canadian and Cimarron Rivers. The pilot
project team discovered that the major interaction occurred along
two smaller streams, the Deep Fork and Little Rivers, which served
as the major ground water sinks instead of the aforementioned
larger streams. This surprising result could have important ramifi-
cations for water quality, especially for the four streams involved.
Certain other pilot projects might also benefit from an in-
tegrated approach. The Yakima River basin pilot project--a sur-
face water investigation--is one such example. Interchange between
surface water and ground water is probably important in the
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NAWQA Pilot Program
upper, forested reaches of the watershed. In the lower portion of
the basin, over 400,000 acres are under irrigation. Subsurface
irrigation return flow could affect stream water quality, as the
potential exists for water quality degradation arising from irriga-
tion (NRC, 1989~.
Critique
The original NAWQA plan to keep surface water and ground
water study units separate had the potential for missing or mini-
mizing important water quality linkages between these two systems.
Therefore, in recognition of the important water quality implica-
tions of surface water and ground water interactions and the
committee's concern that the original NAWQA concept downplayed
these implications, the USGS decided in March 1989 to redefine
the study units. Instead of the original 123 separate study units, 60
integrated surface water/ground water study units now exist;
selection of these new units will be discussed in another section.
The study units are shown in Figure 2.1 and listed in Table 2.1.
Summary
The emphasis on integrated study units will result in an im-
proved program since it will now examine the water quality of an
integrates! hydrologic system. Flow paths between aquifers and
streams will be delineated so that the investigators will be able to
quantify the effects of one component (i.e., surface water or
ground water) of the system on the water quality of the other
component. The integrated approach will also allow the investi-
gators to ascertain the physics of the system to a greater extent
than before, thus enabling them to understand the cause and effect
relationships, which could be extended to other parts of the coun-
try. One of the important aspects of the NAWQA program is an
understanding of water quality cause and effect relationships,
and the committee believes that the integrated approach will
enhance such understanding. The USGS plans to use teams of
surface water and ground water specialists to review study unit
findings in an effort to develop a basic understanding of the
interrelationships among surface waters, ground waters, and the
water quality constituents carried by those waters. To the extent
that these reviews are successful, they should enable better plan-
ning of new projects as they come on-line.
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NAWQA Design Evaluation
:__
· . .
r
29
FIGURE 2.1 Proposed NAWQA study units in the United States.
SOURCE: Leahy et al, 1990.
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30
NAPTHA Pilot Program
TABLE 2.1 Proposed Study Units for a Full-Scale National Water Quality Annulment
Program
USGS Northeastern Region
1. New Hampshire-Southern Maine Basins
2. Southeastern New England
3. Connecticut Valley Drainage
4. Hudson River Basin
6. Long Island
6. Delaware River Basin
7. Lower Su~quehanna River Basin
8. Delman~a Peninsula
9. Potomac River Basin
10. Allegheny and Monongahela River Basins
11. Kanawha River Basin
12. Lake Ene-Lake Saint Claire Drainage
13. Great and Little Miami River Basins
14. White River Basin
15. Upper Illinois River Basin
16. Lower Illinois River Basin
17. Westem Lake Michigan Drainage
18. Minneapolis-St. Paul Basin
19. Red River of the North
USGS Southeastern Region
20. Albemarle-Pamlico Drainage
21. Upper Tennessee River Basin
22. Santee Basin and Coastal Drainage
23. Apalachicola-Chattahoochee Basin
24. Georgia-Florida Coastal Plain
25. Southern Florida
26. Kentucky River Basin
27. Mobile River and Tributaries
28. Mi~i~ippi Delta
29. Chicot-Evangeline
30. Lower Tennessee River Basin
USGS Central Region
31. Eastern Iowa Basins
32. Ozark Plateau
33. Central Oklahoma
84. Trinity River Basin
35. Balcones Fault Zone
36. Central Nebraska
37. Kansas River Basin
38. Upper Arkansas River Basin
39. Central High Plains
40. Southern High Plains
41. South Platte River Basin
42. North Platte River Basin
43. Cheyenne and Belle Fourche Basins
44. Yellowstone Basin
45. Upper Colorado Basin
46. Rio Grande Valley
47. Northern Rockies Intermontane Basins
48. Great Salt Lake Basin
USGS Western Region
49. Upper Snake River Basin
50. Southern Arizona
51. Mid-Columbia Basin
52. Yakima River Basin
5S. Puget Sound Drainages
54. Willamette Basin
55. Sacramento Basin
56. Western Great Basin
57. San Josquin-Tulare
58. Santa Ana Basin
59. Oahu
60. Cook Inlet Basin
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NAWQA Design Evaluation 31
Lakes and Estuaries
Description
In the NAWQA program the term "surface water" is virtually
synonymous with "stream." Estuaries will not be considered in the
program. Lakes (including impoundments) will only be considered
if they significantly affect downstream water quality. However,
the extent of this consideration is not clear, nor is the manner in
which the significance of individual lakes will be evaluated. The
exclusion of lakes has been justified by the USGS on the basis of
cost.
Critique
Estuaries and lakes (including impoundments) are critical
components of the nations water resources. Much of the surface
water supply of the nation is drawn from lakes (either natural or
engineered). Lakes and estuaries support rich and diverse ecosys-
tems, which provide the basis of an extensive seafood industry and
abundant recreational opportunities. Lakes also interact with other
freshwater components of the hydrologic cycle, in that they act as
both sources and sinks of various water quality constituents. Thus
they can significantly affect downstream surface water or down-
gradient ground water quality. It is clearly in the nation's interest
to monitor, assess, and understand the water quality of both lakes
and estuaries.
With respect to the major estuaries and lakes in the nation,
extensive assessment programs already exist. Notable examples
include the Chesapeake Bay, San Francisco Bay, and the Great
Lakes. In general, the level of activity in these large systems is
much greater than could be supported under the NAWQA program.
At best, NAWQA can provide additional information regarding
loadings of various water quality constituents. However, NAWQA
can and should benefit from the modeling techniques that have
been developed during the intensive investigations of these major
lake and estuary systems.
In the aggregate, the smaller lakes and estuaries in the nation
constitute a very important resource. While the committee believes
that this resource deserves attention, it supports the decision of the
USGS at this time to exclude estuaries from NAWQA and to
consider lakes only insofar as they affect downstream surface
water quality and downgradient ground water quality. This
support is based on our recognition that the USGS, while
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NAWQA Pilot Program
traditionally strong in mathematical modeling of estuaries and
lakes, has relatively little experience or capability in biological ant}
chemical modeling.
The committee, however, believes strongly that the USGS must
include in NAWQA consideration of those lakes that significantly
affect downstream or downgraclient water quality. This considera-
tion should involve more than just upstream ant! downstream
monitoring of water quality, and should include some degree of
mathematical modeling. If developed in the early stages of a study
unit, a preliminary model can be used to establish the potential
significance of existing lakes, and to guide the monitoring pro-
gram. Once collected, monitoring data can be user! to evaluate the
moclel, and if warranted, to guide its improvement. This in turn
may lead to adciitional monitoring requirements. This iterative use
of models is an essential element of a process-oriented assessment,
and is discussed further in the Analytical Framework section later
in this report.
Summary
The committee believes that an assessment of the long-term
trends in the water quality of lakes (including impoundments) and
estuaries should be part of any long-term national water quality
assessment. At some point, the water quality of lakes should
receive the same level of attention in the NAWQA program as that
of streams and ground water. However, given the present lack of
personnel in the USGS with expertise in the biological and chemi-
cal modeling of lakes and estuaries, we believe that the NAWQA
program should not be expanded at this juncture to include es-
tuaries. However, we recommend that initially lakes should be
considered but only as they affect downstream surface water
quality or downgradient ground water quality.
The committee further recommends that the first set of inves-
tigations in the NAWQA program include one or more study units
in which lakes are likely to be significant contributors to down-
stream and/or downgradient water quality. This will give the
USGS an opportunity to enhance its capabilities with respect to
lakes. Additionally, we recommend that mathematical models be
developed at the initial stages of each study unit investigation
involving lakes.
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NAWQA Design Evaluation
Introduction
Selection of Study Units
The selection of study units is described in Hirsch et al., 198S,
which is the source for much of the discussion in this section.
Some changes in the study unit selection process, as described in
Hirsch et al., 198S, were dictated by the decision to designate
combined surface water-ground water study units; these changes
are included in the discussion herein. Since the selection of study
units is based largely upon the USGS's hydrologic unit classifica-
tion system, a brief description of that system, taken from Seaber
and others (1986), is warranted.
Description
The USGS divides the United States into 21 major geographic
regions and 222 hydrologic subregions. The regions contain either
the drainage area of a major river, such as the Missouri region, or
the combined drainage area of a series of rivers, such as the Texas-
Gulf region, which includes a number of rivers draining into the
Gulf of Mexico. Eighteen regions comprise the conterminous
United States, with individual regions specified for Alaska, the
Hawaiian Islands, and Puerto Rico and other Caribbean areas. A
hydrologic subregion includes the area drained by a river system, a
reach of a river and its tributaries in that reach, a closed basils),
or a group of streams forming a coastal drainage area. These
subregions are further subdivided into 352 accounting units that
nest within, or are equivalent to, the subregions. The accounting
units are used by the USGS in designing and managing the
National Water Data Network.
A set of 200 surface water candidate study units (CSUs) were
identified, based primarily on the hydrologic subregions described
in Seaber and others (1986~. When a given subregion was too large,
it was subdivided to form a number of CSUs. In other cases,
subregions were combined into a single CSU or a particular ac-
counting unit from one subregion was added to another. In the
selection of the surface water CSUs, attempts were macle to select
ones having similar areas. Modifications were sometimes made to
ensure that all sources to a major lake or estuary were contained
within the same CSU. An attempt was also made to select CSUs
that had relatively homogeneous land use and environmental
characteristics. A set of 116 ground water CSUs were also iden-
tified. The boundaries of these CSUs were less well defined than
~ _ _
33
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34
NAWQA Pilot Program
those of the surface water CSUs; in some cases, ground water CSU
boundaries coincided with those of surface water CSUs.
Each set of CSUs was screened using a modified linear pro-
gramming model (Fox and Scudder, 1986~. The objective function
of the linear program minimized the number of study units se-
lected, given certain constraints: (1) the study units account for
about 60 percent of the nation's water use, as measured by popula-
tion served by public water supplies and by total withdrawals
excluding thermal and hydropower uses; and (2) each state contains
at least one study unit having at least 30 percent of its area within
that state. This exercise yielded two maps: one of surface water
study units and one of ground water study units. Next, a few
study units that were downstream of major river basins (e.g., the
Colorado and Ohio rivers) were deleted; the rationale for these
deletions was that these basins integrate water quality conditions
for many upstream basins (Hirsch et al., 1988~. The two sets of
study units were then merged and reviewed by all USGS district
and regional offices to provide study unit boundaries that ac-
counted for both surface water and ground water boundaries.
Some study unit boundaries may be refined once the full-scale
program gets under way. Finally, study units were specified for
Hawaii and Alaska. The 60 study units encompass about 40 per-
cent of the land area of the conterminous United States and incor-
porate about 60 to 70 percent of the nation's water use (fresh
surface water withdrawals excluding thermal and hydropower
uses). It should be noted that in selecting the study units, emphasis
was placed on "key river basins" and ground water units that
corresponded somewhat to the USGS Regional Aquifer Systems
Analysis (RASA) program. Essentially, the purpose of the RASA
program is to emphasize the physical hydrogeology of certain
regional aquifers. By attempting to coordinate NAWQA study
units with RASA efforts, the USGS will take advantage of infor-
mation already being generated. The RASA program emphasizes
the physics of the ground water systems, something that must be
understood to undertake a water quality assessment that seeks to
identify cause and effect relationships. The coordination of RASA
and NAWQA, where possible, will result in an improved NAWQA
product.
Critique
The geographic coverage of the study units is good, considering
that only 40 percent of the continental United States is included.
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NAWQA Design Evaluation
35
The variation in size is substantial: the smallest study unit, Long
island (number 5 in Figure 2.1 and Table 2.1), is about 1,300 square
miles, and the largest is the Ozark Plateau (number 32), which is
over 60,000 square miles. The pilot project study units are rela-
tively small--3,000 to 15,000 square miles. Given the large size of
approximately eight study units, the combined ground water-sur-
face water nature of these study units, and the USGS's lack of
experience in a large study unit, the committee is concerned that
NAWQA objectives may not be met in some of the larger units.
Summary
Study unit selection is generally good; the coverage is broad
and represents a variety of hydrologic regions. Coordination of
study units with RASA study areas is an approach that should
result in some degree of synergism and aid in delineating cause
and effect relationships. Some of the study units are quite large,
much larger than any of the seven pilot project study units. To see
how well the NAWQA program can accommodate a large study
unit, the committee recommends that early in the full-scale
NAWQA program, the U.S. Geological Survey select two large study
units for investigation.
SAMPLING DESIGN
Sampling Approach
Introduction
The NAWQA pilot program originally consisted of separate
surface- and ground-water study units with separate sampling
designs. The committee's evaluation therefore considers the sur-
face- and ground-water sampling designs separately. The full-
scale NAWQA will be based on combined surface- and ground-
water study units; however, a combined sampling design has not
yet been developed. Hence, the committee also points out some
issues that need to be considered in designing a sampling program
for the combined surface- and ground-water study units.
Ground Water
Description The major objectives of the ground water investiga-
tions (Hirsch et al., 1988) are to (1) describe ground water quality
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NAUSEA Pilot Program
conditions for major hydrogeologic settings; (2) describe the geo-
graphic distributions within the study units of selected water
quality constituents and problem areas; (3) define long-term trends
in ground water quality; and (4) identify, describe, and explain, if
possible, the major factors that affect observed current conditions
and trends in ground water quality. To attain these objectives,
NAWQA projects will conduct three different types of ground
water sampling activities: (1) regional, (2) targeted, and (3) long
term.
Regional sampling will be conducted throughout each major
hydrogeologic setting within a study unit. All of the national
target variables for chemistry and physics will be measured in an
effort to provide descriptive statistics and to form an initial basis
for describing the geographic distribution of water quality vari-
ables within the study unit. Sampling will be done in three dimen-
sions and will be designed to be unbiased with respect to particular
"problem areas."
Targeted sampling will occur in selected locations for specific
groups of water quality constituents; it will focus on "problem
areas" but will not be a "plume chasing" exercise. As an example,
in the Central Oklahoma aquifer pilot project, targeted sampling
variables are (1) naturally occurring trace substances (NOTS) such
as arsenic, selenium, chromium, uranium and gross-alpha radio-
activity and (2) organics (especially pesticides) beneath central
Oklahoma City. Problem areas for targeted sampling will be
identified from the regional sampling results, knowledge of the
hydrogeologic and land-use factors that contribute to water quality,
and consultation with local agencies and individuals involved with
ground water quality. Three targeted sampling approaches will be
used: (1) search-oriented sampling, (2) statistical hypothesis testing,
and (3) local-scale transects (Hirsch et al., 1988~.
Local-scale transects will involve high-density sampling of one
or more wells per square mile to characterize representative set-
tings that commonly occur throughout large parts of the study unit.
These local-scale studies should be useful for examining the inter-
relationship between surface water and ground water quality.
Transects provide very good information about a study unit's
physical hydrogeology. The Delmarva Peninsula pilot project has
used transects of shallow wells installed adjacent to streams to
follow the infiltration of pesticides from agricultural lands down
to the shallow aquifer and from there into streams. Local-scale
transects have also been used in the Carson basin pilot project.
Search-oriented sampling will involve sampling for constituents
within particular settings in which they are most expected. The
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NAWQA Pilot Program
completeness and conformance to information management guide-
lines. Laboratory QA samples were checked against NAWQA
minimum standards and for proper review and (if needed) action.
Critique
The USGS appears to be committed to ~ sound practice of
quality assurance and quality control. The QA program assures
that technically sound procedures will be used in the NAWQA
program.
The reviews demonstrated that the proposed QA/QC program is
working in the study units. The review process provided a com-
plete examination of the QA/QC program in the study unit. It
identified deficiencies and actions to correct them. In addition,
the reviews identified areas where additional national guidance
should be considered to aid the study units. The following were
items mentioned in more than one study unit review:
1. concerns with aspects of low-level trace organic analyses;
2. the need for national archival guidelines; and
3. more guidance on how to evaluate the QA laboratory
samples. The site review program is an effective process for
assuring the integrity of the NAWQA quality assurance program.
Summary
The proposed QA plan is a sound approach for managing the
NAWQA data bases to ensure utility and longevity beyond the first
rotation of sites. In the full NAWQA program, periodic data base
reviews will need to be continued to ensure completeness and
accuracy of data. The results of all the pilot project audits should
be reviewed for recurring areas of concern--particularly with
monitoring for low-level organic compounds. The committee be-
lieves that the QA program is a strong component of the NAWQA
program. For the program's stated purposes it is desirable to have
one agency, preferably a nonregulatory agency, responsible for a
program of this scale. Consistency of sampling protocols and data
collection will aid in analysis and be essential for timely and
meaningful interpretation and synthesis. It is important that the
headquarters person in charge of QA be in regular communication
with the four regional NAWQA QA personnel to coordinate their
activities closely, thereby ensuring that comparable standards and
practices are being employed across the full NAWQA network of
sites.
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63
There is a lack of consistency in terms of water quality data
collected by federal agencies. In the EPA 305(b) program, each
state defines its water quality issues (USEPA, 1989~. The com-
mittee would like to see more coordination of the NAWQA program
with other agencies, especially in such areas as uniformity of water
quality parameters monitored and more consistent sampling and
analytical techniques. The NAWQA program has the advantage
over EPA's 305(b) program owing to its coordinated effort among
the four USGS regions in terms of data collection protocols and
methods. While local issues are important, the committee believes
that the national synthesis planned in NAWQA will be a contribu-
tion. In time, after a full NAWQA has been operational, it would
be desirable for the USGS to determine how much overlap exists
between the two programs, NAWQA and 305(b) to avoid costly
duplication of effort. At the very least, both agencies should have
access to the data from both programs.
Data Management
Description
For data management (i.e., data documentation, collection,
archiving, and retrieval), the pilot studies have used the USGS
National Water Data Storage Retrieval System (WATSTORE) and
the National Water Information System (NWIS) data bases, which
are periodically transferred to EPA's STORET system. For the full
NAWQA program, a new system, NWIS-2, is being designed and is
targeted for operation in FY 1992. The development of this system
is currently under way as part of the upgrading of computer
resources for the Water Resources Division of the USGS.
Critique
WATSTORE is on a 15-year-old Amdah} Computer, which uses
outdated computer technology from the 1960s and 70s (W. Wilber,
personal communication 1989~. People unfamiliar with
WATSTORE have great difficulty using the system. As part of the
computer upgrade mentioned above, the USGS is developing speci-
fications for a new water quality information system. Eventually,
NWIS-2 will replace WATSTORE (W. Wilber, personal communica-
tion 1989~. Currently, state data bases are on Prime computers that
are uploaded to the national WATSTORE system and are periodi-
cally transferred to EPA's STORET system. It is not clear whether
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NAWQA Pilot Program
the new system will handle the Geographical Information System
(GIS) data any differently from what was done in the pilot studies.
The committee endorses the revamping of WATSTORE and en-
courages the USGS to work quickly to develop and implement
NWIS-2.
The NAWQA criterion for acceptable storage and documenta-
tion is to ensure that the data records and documentation will be
useful to a succeeding project team 6 or more years after comple-
tion of the initial investigative phase (i.e., beyond the first cycle of
activity). In addition to the sanitary water quality data, the
ecological survey is documenting the current status of the biologi-
cal community (fish and invertebrate distribution data and tissue
sampling for bioaccumulation) at each NAWQA site to provide a
basis of the spatial variation and assess long-term changes in the
biological community. The data management plan for the Ecologi-
cal Survey is currently being revised.
Sharing information and data files with the USGS within the
scientific community is not easy because very few of the USGS
personnel are connected to the Internet, a collection of local net-
works (campus, governmental, and industrial) linked together by
regional networks and attached to a national backbone (NSF Net).
The purpose of the Internet is to provide high-speed communica-
tion among members of the scientific community and to provide
access to remote computing resources. Linking the USGS scientists
to the scientific community via Internet would facilitate greater
collaboration and coordination.
Summary
The committee believes it would be much easier to communicate
with the USGS if their personnel and their computers had access
to the Internet system. This would facilitate better coordination
with universities and other research facilities and agencies. The
committee endorses the revamping of WATSTORE and encourages
the USGS to work quickly to develop and implement their new
national water information system.
ANALYTICAL FRAMEWORK
Description
For reasons discussed in Chapter 1, the committee firmly
believes that a national assessment of our nation's waters must take
a strong process-oriented approach. Such an approach improves
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65
basic understanding of the physical, chemical, and biological
processes that contribute to water quality and is essential to intel-
ligent water-resource management. The committee further believes
that the basic design of NAWQA is strongly process-oriented, and
that the USGS is well suited to execute such a design.
Much of the NAWQA design reflects an emphasis on hydrologi-
cal processes. Study units are based on hydrological boundaries.
Monitoring locations will be determined based on understanding of
the relevant flow system. Synoptic surface water surveys provide
opportunities to sample distinct hydrological events. Reach studies
~ ~ . . ~ ~ ~ . ~ . ~ ~
and local-scale transects enable aetallea analysis OI lmpOrlalll
subsystems. The integration of surface water and ground water
studies provides sorely needed opportunities to understand the
important interactions between surface and ground waters.
The USGS is ideally suited to conduct a process-oriented assess-
ment of our nation's waters. The overall mission of the USGS is to
provide information that will assist resource managers and policy-
makers at the federal, state, and local levels in making sound
decisions. This information is generated through assessments of
the quantity and quality of the nation's natural resources, in-
cluding minerals, energy resources, and water. In the case of water
resources, the USGS has collected and interpreted data on water
quantity and quality for more than 100 years. While many of
these investigations have been relatively small in scale, a signifi-
cant number have been comparable to a NAWQA study unit. A
notable example is the ongoing study of selenium in the San
Joaquin Valley in California (Gilliom, et al., 1989.) The committee
reviewed the activities of the USGS in this study and was favor-
ably impressed with the scientific understanding that has resulted.
Furthermore, it is clear to the committee that without such under-
standing, management strategies in the region would be poorly
grounded.
The strength of the USGS in conducting a process-oriented
assessment of our nation's waters lies in the fact that it has well-
trained, personnel representing a variety of disciplines dispersed
throughout the nation. This means that a particular study-unit
investigation will not be starting from scratch, since it will have
access to personnel who understand the local and regional hydrol-
ogy. Given the enormous variation of the hydrologic processes
through the nation, such expertise is critical.
Therefore, the committee believes that the NAWQA design has
a strong process orientation, and that the USGS is well suited to
execute the design. However, in the course of evaluating the
NAWQA program, the committee also concluded that the ability of
NAWQA to elucidate hydrologic processes should be strengthened
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NAWQA Pilot Program
by a greater reliance on mathematical modeling. This issue is
discussed in the subsequent sections.
Critique
An important feature that appears to be lacking from the
overall NAWQA program, particularly the regional pilot studies, is
the quantitative and analytical framework that identifies the
principal cause and effect relationships. While this issue has been
qualitatively addressed in NAWQA documents and in comments by
USGS personnel, its quantitative definition, which is essential for
decisionmaking, appears to be inadequate at this stage. The link
between sources, both point and distributed, and the water quality
response of a particular system, can be provided by a mathematical
model that defines the spatial and temporal distribution of the
concentration of relevant water quality constituents. The formula-
tion of such a model should be an integral part of the individual
studies. Although it has been stated or suggested that some kind of
modeling would follow the data collection, there remains a reason-
able question that this task may not be effectively realized. More
importantly, the structuring of a quantitative model should be
incorporated in the early phase of each project, to whatever degree
is possible given the nature of the problem and available data.
The use of models can serve many purposes in NAWQA. First,
a model provides a tool for organizing what is known about a
given system, at the scale of interest. Consequently, a model also
serves to reveal gaps in knowledge. A model can be used to pre-
dict what should be the critical factors affecting water quality
(e.g., point versus nonpoint sources). This information can be used
in designing the sampling strategy. Once data have been collected,
they in turn can be used to refine the model. A model provides a
way to account explicitly for meteorologic and hydrologic varia-
tions. This makes it much easier to resolve water quality impacts
caused by other factors, such as human activities. It also makes it
possible to extrapolate for conditions other than those observed
during the sampling period. A model can be used to simulate
water quality for different scenarios of human activity. Such a
capability is essential for evaluating hypothetical management
options and is also useful in evaluating the impact of past manage-
ment practices.
Thus, water quality modeling can be used in all phases of water
quality assessment, including design of the monitoring program,
analysis of data, and evaluation of past and potential management
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NAWQA Design Evaluation
options. Of particular importance is the interactive nature of
modeling and data collection. These activities are mutually sup-
portive, and each should evolve throughout the assessment process.
This will lead to a better assessment, as well as to an improved
understanding of the relevant physical, chemical, and biological
processes.
67
Just as we recognize the necessity for using models in NAWQA,
we also realize that the state-of-the-art in water quality modeling
may have to be improved if models are to be used effectively in
support of NAWQA. While a number of excellent surface water
quality models are widely used for management purposes, most
notably those supported by EPA, the applicability of these models
to large spatial scale water quality assessment is unclear. Existing
surface water models were designed to be used at relatively small
scales and are most commonly applied to evaluate compliance with
standards under hypothetical flow conditions (such as the 7-day,
10-year low flow). In comparison, NAWQA study-unit investiga-
tions will be conducted! at enormous scales and will involve a very
large suite of water quality constituents over a wide range of flow
conditions. With respect to ground water, the USGS has played a
leading role in developing models of both flow and quality. Of
particular importance is the large-scale flow modeling that was
undertaken by the USGS in the RASA program. These models
should provide a framework for ground water modeling in many
of the NAWQA study units (and in fact, have been used this way
to some extent in the pilot studies). What remains, of course, is the
incorporation of water quality into these models. A more difficult
challenge is the integration of surface water and ground water
_.__ ^ and_ arm_. ~In,. . _^ ~
modeling.
Given the lack of appropriate existing models in some cases, the
USGSts inexperience in most cases, and the considerable difficulty
of the task, some models will prove inadequate or infeasible.
Therefore, a midcourse model evaluation should be built into the
assessment cycle so that corrections can be made in sufficient time.
Summary
Water quality modeling should be an essential component of
NAWQA. In the short term, the USGS should make use of
existing models. Because the USGS has relatively little experience
with existing surface water quality models, it will need to begin
~ :~ A ~ ~ : :- ~ ~ There is
also a critical need to determine the data required by these models,
since the current NAWQA design may not include collection of
immenlatelv to nrov~de Or nDtaln the necessary tralDlnE.
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NAWQA Pilot Program
necessary data. (For example, there is no plan to collect meteoro-
logical data, which will be essential for watershed models of water
quality.) During the first round of intensive monitoring, the
leading water quality models should be applied over a wide range
of situations. This would not only enhance the assessment effort,
but would also provide valuable information on the capabilities of
the models. A midcourse mode' evaluation should be built into the
assessment cycle so that corrections can be made in sufficient time.
Over the long term, the USGS should be developing a coherent
strategy for water quality modeling in the context of a large
spatial scale assessment, addressing such issues as scale, model
complexity, and surface and ground water interactions. To the
fullest extent possible, this should be done in cooperation with
other federal agencies, particularly the Environmental Protection
Agency.
PRODUCTS
Description
The goals of NAWQA are to "describe the status and trends in
the quality of the nation's surface and ground water resources and
to provide a sound, scientific understanding of the primary natural
and human factors affecting the quality of these resources" (Ap-
pendix B. #36) in order to "provide an improved scientific basis
for evaluating the effectiveness of water quality management
programs and for predicting the likely effects of contemplated
changes in land and water management practices" (Appendix B.
#38~. Essential to achieving this goal of improving the evaluation
and prediction of the consequences of management practices is the
dissemination of the results of NAWQA to the appropriate audi-
ences.
The USGS has proposed three broad classes of report topics to
be prepared under NAWQA (Appendix B. #38~:
1. statistical descriptions of water quality conditions and
changes over time,
2. information on the geographic distribution of contaminants
across the United States, and
3. information on key factors that affect water quality.
It is the committee's understanding that this information will be
provided in USGS water-supply papers, open-file reports, water
resources investigations reports, yearbook articles, and other publi-
cations, as well as in scholarly journal articles. For example, each
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69
pilot project has been assigned a Water-Supply Paper number. The
"A" chapter of each will be a project summary, the "Be chapter will
be a retrospective report (see below), and later chapters will be
specific to each study unit (Appendix B. #37~. Presentation
methods in these reports will include tables, graphs, maps, and
supporting text. Raw data will be available via a single, consistent
computer data base. Similar products are to be prepared for both
the study-unit investigations and the issue-based and national
synthesis team studies.
Unfortunately, because of the timing of the committee's review,
no NAWQA reports presenting results at either the study-unit or
synthesis level were available for review, with the exception of
retrospective reports for 5 of the pilot projects (Appendix B. #62,
70, 79, 83, 89~. Therefore, our evaluation of NAWQA products is
necessarily broad and general for the most part. The retrospective
reports available for review focus on compiling available existing
data from federal, state, and local agencies, evaluating the suit-
ability of these data for NAWQA study unit activities, and pre-
senting a preliminary spatial analysis of water quality conditions
in the study unit via mapping, summary statistics, and descriptive
text. They also contain background material of the study unit, its
natural and cultural features, and its hydrologic systems.
Critique
The retrospective reports available for review have been pre-
pared and designed well, and should serve the purpose for which
they were intended. During their visits to the pilot projects,
committee members were frequently told that the compilation of
all available data into one documented source and data base was
by itself a significant contribution to local decisionmaking. The
reports do exhibit some unevenness in the quality of their analyses,
with some study-unit teams apparently being more capable and
creative than others in extracting and presenting useful informa-
tion from the available data.
After examining the more general aspects of the planned
products of NAWQA, the committee first noted that the maps and
reports at the USGS are in general highly respected among the
potential users of NAWQA. Potential users interviewed by the
committee were practically unanimous in that opinion. In fact,
some local and state users made the point that data and informa-
tion provided by the USGS will be far more helpful to them in
their water quality management responsibilities than data and
information acquired by the users themselves because local and
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NAWQA Pilot Program
state governmental authorities have such high regard for the
integrity of the USGS.
One concern brought to the attention of the committee during
its evaluation is the timeliness of USGS reporting. A number of
potential users expressed frustration at the time required for
publication of USGS reports, especially those containing data. The
committee commends the USGS for its decision to publish the
Water-Supply Papers for the pilot projects initially as open-file
reports in order to accelerate the availability of this information.
However, the committee would like to encourage the USGS to be
vigilant and creative in seeking out ways to minimize the time
required to publish NAWQA findings.
In considering the three broad classes of report topics en-
visioned by the USGS for NAWQA, the committee noted that the
first two classes will be of greatest interest in support of policy
formulation and resource allocation at fairly high levels of deci-
sionmaking, while the third class will be of greatest interest to
water quality management decisionmaking at the implementation
level. It was also noted that the first two classes of reports will in
many ways be the easiest to produce. The committee urges the
USGS to strike an appropriate balance and assure that adequate
resources are directed toward reports describing the results of
cause and effect analyses, even if those are more difficult to
produce. Many of the potential users of NAWQA with whom the
committee spoke, especially on the local and state levels, em-
phasized the value they would place on reports bettering their
understanding of processes.
The committee is most concerned, however, with the relatively
narrow scope of the retrospective studies. While the study-unit
teams appear to have been thorough in identifying and acquiring
available data, the extent of their investigations was quite limited.
In particular, the investigations focused almost exclusively on
ambient water quality data in streams and aquifers. Data on
sources of contamination were not collected and analyzed, in spite
of the availability of extensive data bases (e.g., EPA's Permit
Compliance System and Industrial Facility Reports). In addition.
the retrospective reports make no attempt to identify and assess
available studies of water quality processes in the study units or
available water quality models that have been developed for all
portions of the study units. If the goal of NAWQA is indeed to
improve our understanding of water quality processes on the study-
unit, regional, and national scales, it is imperative that information
on sources and previous investigations of processes be included
within the concept of a retrospective report.
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NAWQA Design Evaluation
Summary
The committee recommends that the concept of a retrospective
report be expanded to include data on known sources of water
quality constituents, existing studies of water quality processes
within the study unit, and previously developed conceptual and
mathomat;ral mn~l~lc of the nhvsical. chemical. and biological
71
.~ . ., _ ~ ~ .~ ~ , ~ , _
processes influencing water quality in the study unit.
The committee encourages the USGS to be vigilant and creative
in seeking ways to minimize the time required to publish the
findings from the National Water Quality Assessment program. In
addition, the committee urges the USGS to ensure that adequate
resources~are directed toward reports describing the results of cause
and effect analyses, even if those are more difficult to produce.
Committee-Initiated Case Study
Description
In order to obtain a sharper focus on how a cause and effect
analysis would be conducted under the NAWQA program, the
committee recommended that the USGS conduct a special study of
the effect of changes in wastewater treatment on trends in the
downstream water quality of the Illinois River. Wastewater treat-
ment was selected as the problem area owing to the large federal
investment in these facilities
The Illinois River Basin was selected
as the study area because ~t Is relatively simple from a hydrologic
point of view and an extensive long-term data base already exists.
As a result of this request, NAWQA personnel conducted a
detailed inventory of past and present wastewater treatment data
in this area. Their study focused on the ava~lan~ty and su~t-
ability of municipal wastewater treatment information. Their
results, indicating several areas where significant improvements are
needed, are being featured in a series of three articles in Water
Environment and Technology, the journal of the water Pollution
Control Federation (Appendix B. #46) and in a USGS Open File
Report (Appendix B. #57~.
. · . . · . ~ . . · .
Critique
Although the NAWQA personnel did a very thorough evalua-
tion of quality control problems with the existing data, they have
not yet completed the originally requested analysis of cause and
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NAWQA Pilot Program
effect relationships for this test study area. Thus the committee
cannot evaluate how cause-and effect analysis is to be ac-
complished under the NAWQA program. While it is understand-
able that the USGS is more comfortable monitoring since it is their
traclitional forte, NAWQA needs to be a first-class assessment
activity if it is to serve its intended! purpose.
Summary
The USGS should immediately intensify its cause and effect
assessment activities and provide complete case studies and a
coherent national methodology for doing cause and effect assess-
ments. This initial effort should utilize all available data and not
be restricted to data generated by the NAWQA monitoring pro-
gram. The results of this effort should be reviewed by an external
science advisory committee.
Representative terms from entire chapter:
ground water
