APPENDIXES



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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program APPENDIXES

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program This page in the original is blank.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program Appendix A Extracts from Study-Unit Design Guidelines for Cycle II of the National Water Quality Assessment (NAWQA)1,2 NAWQA CYCLE II IMPLEMENTATION TEAM DRAFT FOR INTERNAL REVIEW—11/22/20003 Ken Bencala Wade Bryant Carol A. Couch Neil M. Dubrovsky Lehn Franke Bob Gilliom (Chair) Dennis Helsel Ivan James Wayne W. Lapham Dave Mueller Jeffrey Stoner Marc A. Sylvester William G. Wilber David M. Wolock John Zogorski   1   Gilliom et al., 2000b. 2   Extract prepared in cooperation with NAWQA/Cycle II Implementation Team (NIT) staff for exclusive use in this report. Since the structure of much of this National Research Council report (especially Chapters 3 to 5) evolved to be consistent with several iterations of the NIT report that were provided throughout the study, the committee deemed it appropriate to provide an extract of it. However, in preparing this extract, detailed budgetary information and several sections, figures, and tables of the NIT report were purposefully omitted in order to conserve space (e.g., the November 22, 2000, version was 179 pages, excluding appendixes) and editorial changes were minimal. 3   It is also important to note that subsquent versions of this report were prepared by the NIT after the November 22, 2000, version (i.e., 06/22/01 and 06/28/01).

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program NIT REPORT TABLE OF CONTENTS     INTRODUCTION         Themes for Cycle II Investigations         Scope of Cycle II Design Guidelines         Overview of Design and Organization of Report         I. ENVIRONMENTAL FRAMEWORK FOR DESIGN         Natural Factors         Hydroclimate         Soils         Aquifers         Anthropogenic Factors         General Land Use         Urban         Water Use         II. NATIONAL TREND NETWORKS         Overview         Themes and Objectives         Approach and Emphasis         Implementation Strategy         Trend Network for Streams         Types of Stream Sites         Overview of Sampling Strategy         Site Allocation and Selection         Trend Network for Contaminants in Sediment         Overview of Sampling Strategy         Types of Reservoir and Lake Sites         Cycle I Studies of Lake-Sediment Cores         Site Allocation and Selection         Trend Network for Ground Water         Types of Ground-Water Studies         Overview of Sampling Strategy         Study Allocation and Selection         Sub-Unit Surveys         Agricultural Land-Use Studies         Urban Land-Use Studies         Factors Still to Be Considered That May Change Final Selections for All Land-Use Studies in the Trends Network         Analysis of Reference Conditions near Land-Use Studies    

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program     III. NEW STATUS ASSESSMENTS         Overview         Themes and Objectives         Approach and Allocation of Effort         Implementation Strategy         New Status Assessments for Streams         Agricultural Sites         Urban Sites         Reference Sites         New Status Assessments for Ground Water         Types of Ground-Water Studies         Overview of Sampling Strategy         Study-Component Allocation and Selection         New Status Assessments for Contaminants Not Previously Sampled by NAWQA         Mercury         New Pesticides and Degradation Products         Pathogens         Drinking-Water Source Assessments         Streams         Ground Water         IV. SPATIAL STUDIES OF EFFECTS OF LAND-USE CHANGE ON WATER QUALITY         Overview         Themes and Objectives         Approach and Allocation of Effort         Streams         Objectives for Streams         Study Design for Streams         Ground Water         Study Design for Ground Water         V. TARGETED STUDIES OF FACTORS THAT GOVERN WATER QUALITY         Overview         Themes and Objectives         Implementation Strategy         Targeted Water-Quality Studies         Selection and Prioritization of Topics for Targeted Studies         Topical Study Teams         Hydrologic Systems Analysis and Modeling         Hydrologic Systems Team         Modeling and Analysis Tools         Modeling and Analysis Resources    

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program     Example Designs         Sources and Transport of Agricultural Chemicals         Nutrient Enrichment of Streams         REFERENCES         APPENDIXES         A.Evaluation of Cycle II Themes and Objectives     B.Glossary     C.Classification of Agricultural Land by Crop Groups     D.Evaluation of Hydrologic Landscapes     E.Analysis of Stream Networks     F.Analysis of Ground Water Networks INTRODUCTION Cycle II of the U.S. Geological Survey’s National Water Quality Assessment Program (NAWQA) will be the second decade of NAWQA in which 42 study units are revisited in three groups of 14 on a rotational schedule (Gilliom et al., 2000a). Similar to Cycle I, each group will be intensively studied for three years, followed by six years of low-intensity assessment. The primary emphasis of Cycle II (2001-2011) is to assess long-term trends in water quality and to improve our understanding of the factors and processes that govern water quality. The third priority is to fill critical remaining gaps in the status assessment, which was the main focus of Cycle I (1991-2001). This balance of priorities follows the recommendation of the NAWQA Planning Team (Mallard et al., 1999), which concluded: The primary goals of NAWQA during its first decade continue to be appropriate as the program begins Cycle II. These goals are: Provide a nationally consistent description of current water-quality conditions for a large part of the nation’s water resources. [status] Define long-term trends (or lack of trends) in water quality. [trends] Identify, describe, and explain, as possible, the major factors that affect observed water-quality conditions and trends. [understanding] To be successful NAWQA must continue to focus on all of these goals. However, there should be a shift in the relative emphasis and resources given to the three goals as the program moves into its second decade. Relative to the first Cycle, the first goal, occurrence and distribution, should receive less emphasis in Cycle II. The third goal, explanation, should receive greater emphasis. The relative emphasis given to trends should increase in Cycle II because low-intensity phase (LIP) sampling, a key component for trends analysis, was not fully implemented during Cycle I.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program The purpose of this report is to describe the design and implementation strategy for Cycle II investigations in NAWQA study units. Themes for Cycle II Investigations The design of Cycle II of NAWQA is guided by 12 major water-quality themes (Table 1), which are organized according to the three major goals of NAWQA water-quality assessment: (1) status, (2) trends, and (3) understanding TABLE 1 Themes for Cycle II NAWQA Studies and Preliminary Allocation of Study Effort.a Theme Question Status Themes   Resources not previously sampled What is the quality of the most important streams and ground-water resources not sampled during Cycle I? Drinking water resources What are the concentrations and frequencies of occurrence of NAWQA target constituents in streams and ground water resources used as sources of drinking water? Contaminants not previously sampled What is the occurrence and distribution of contaminants not yet measured by NAWQA, such as pathogens, new pesticides, pharmaceutical products, high production volume industrial chemicals and others? Trend Themes   Trends and changes in status of resource What are the trends and changes in the status of water quality since the NAWQA Cycle I status assessment and before? Response to urbanization How has water quality changed in response to urbanization? Response to agricultural management practices How has water quality changed in response to long-term changes in agricultural management practices such as tillage methods, chemical use, and crop patterns? Understanding Themes   Sources of contaminants Identify and quantify the natural and anthropogenic sources of contaminants to surface and ground waters. Transport Processes: Land surface to and within ground water What is the relative importance of biogeochemical and physical processes in influencing the transport and transformation of surface- and in-situ-derived contaminants in the unsaturated zone and ground water as they are transported from land surface to shallow ground water and to underlying aquifers? Transport Processes; Land surface to and within streams How are contaminants transported--and with what losses and transformations—from land surfaces to streams and downstream to rivers, reservoirs, and coastal water? Transport Processes: Ground-water/surface-water interactions What is the role of exchanges and interactions between ground water and surface water in determining the degree and timing of contaminant levels? Effects on aquatic biota and stream ecosystems What are the effects on stream biota and ecosystems of contaminants, contaminant mixtures, habitat modifications, and other stressors, and what are the relative roles of the different stressors? Extrapolation and forecasting How can we best extrapolate (spatial dimension) or forecast (temporal dimension) water-quality conditions for unmeasured geographic areas and future conditions (after management changes), based on knowledge of land use and contaminant sources, natural characteristics of the land and hydrologic system, and our understanding of governing processes? aPreliminary allocation of Cycle II resources information removed from table.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program governing factors. In describing themes and related objectives, the term “water quality” is used according to its broad definition, which includes consideration of the chemical and physical nature of water and associated particles, habitat conditions, and the composition and health of aquatic biota. Thus, for example, the factors that govern water quality include effects of contaminants on biota as well as the sources and transport of contaminants. Cycle II themes related to the goal of understanding governing factors, which encompass the most complex and difficult objectives to address, are further organized according to a conceptual source-transport-receptor model. Sources → Transport → Receptors (of contaminants and (pathways and processes) (exposure and effects) other stressors) Questions organized according to this concept may involve factors in all, some, or parts of the three model components. For example, exposure may be well characterized, but effects are unknown. Or, sources may be well characterized, but factors governing transport are not. The focus of NAWQA regarding receptors is primarily on drinking water for both ground water and streams, and on aquatic biota and ecosystems for streams. The emphasis for drinking water is to characterize potential exposure, with no direct investigation of effects on humans, whereas the emphasis for aquatic biota and ecosystems is on understanding both exposure and effects. The 12 Cycle II themes summarized in Table 1 are based on national and study-unit priorities derived from results of Cycle I studies and priorities of cooperating agencies. The themes are variably overlapping and integrated. For each theme, specific objectives have been developed that will guide Cycle II design decisions. Within each group of Cycle II study units, however, the distribution of effort among some of the Cycle II themes and objectives, particularly for the themes related to understanding the factors that govern water quality, will vary substantially and objectives will be further refined depending on the characteristics of the study units and national priorities. Certainly other organizational frameworks for the Cycle II themes are relevant, such as by land use, drinking water and ecological effects, surface water and ground water, and so forth. There is, in fact, no single framework that can incorporate all of the different water-quality issues and scientific problems that arise. The choice of organizing themes by major program goals emphasizes the continuity of the program design from Cycle I to Cycle II and the logical progression toward better addressing the long-term goals. Interwoven with the 12 Cycle II themes are additional, sometimes overarching, water-quality issues that cut across multiple goals and themes even though they are explicitly emphasized in one. Examples of such issues are drinking-water quality and the condition of stream ecosystems. These cross-

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program cutting issues are partially incorporated into one or more of the 12 primary themes, but some issues will also require separate design consideration and special attention to integration across all three program goals. Depending on the issue and its priority and characteristics, each will be addressed in somewhat different ways by Cycle II investigations. Scope of Cycle II Design Guidelines The Cycle II design guidelines described in this report are intended as a national framework for designing study unit investigations and related national synthesis activities. Study designs for status and trend assessment are mainly based on the application of relatively standardized sampling components that were developed and tested during Cycle I. In general, Cycle II status objectives will be addressed by applying the same approaches used in Cycle I to new sites and study areas, or with new types of chemical and biological analyses. Cycle II trend assessment objectives will largely be addressed by resampling selected Cycle I sites and study areas to evaluate change. In general, the guidelines are quite specific in terms of site selection and sampling design for status and trend assessment, even though careful review and analysis by study unit teams is essential and will change some selections of study sites and sampling strategies. Guidance is less specific for studies aimed at understanding factors that govern water quality. Generally, stream sites and ground water study areas selected for trend assessment also form a foundation for studies that are designed to assess governing factors and ecological effects. The detailed studies aimed at governing factors, however, also require extensive additional data collection and analysis, including a wide range of modeling approaches. For these studies, the design guidelines focus on the implementation strategy for choosing priority topics and forming topical study teams of national, study-unit, and research scientists. These topical study teams will then develop the details of study design. The design guidelines focus mostly on the 3-year High Intensity Period (HIP) for study units, but also include consideration of the 6-year Low Intensity Period (LIP) for the trend assessment design. Each of the three groups of 14 study units that will be studied in Cycle II will have one HIP, with the balance of the decade in the LIP. Overview of Design and Organization of Report The report is organized by five main chapters that explain and document the Cycle II design and implementation strategy. The organization of the chapters maintains a close correspondence to NAWQA program goals, but the order of explanation has been adapted to allow an efficient explanation of study approaches. In particular, the National Trend Networks are presented before the New Status Assessments because much of the ground work for explaining priori-

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program ties for New Status Assessments is laid in the Trend Network design. Each chapter is briefly described below by chapter number and title: I. Environmental Framework: This chapter is an overview of the concept and selected key elements of the environmental framework used in developing the Cycle II design. The environmental framework is the systematically characterized set of natural and anthropogenic characteristics of the national landscape that geographically define the factors that we expect to influence water quality and how it varies throughout the nation. The distribution of factors such as land use and hydrologic characteristics are used throughout the design guidelines for status, trends, and understanding studies to prioritize and select study locations and topics. II. National Trend Networks: National sampling networks designed to assess long-term trends for streams, ground water, and sediment contaminants are comprised of sites distributed among a wide range of environmental settings of the nation, which are systematically sampled over time to evaluate trends and change. In addition to meeting trend assessment objectives, these sites form the foundation of data collection for other studies with additional objectives, and the design considerations for the national trend networks define some of the most critical needs for further status assessment. III. New Status Assessments: New status assessments are designed to fill the most critical gaps remaining after Cycle I studies. The three types of new status assessments in the Cycle II design are: (1) those designed to fill geographic gaps in the status assessment and trend network design, (2) assessments of contaminants in drinking-water supply sources, and (3) selective assessments of contaminants that were not extensively assessed in Cycle I. IV. Spatial Studies of Effects of Land-Use Change on Water Quality: Changes in water quality that are caused by urbanization and changes in agricultural development and management, particularly the status of aquatic biota and stream ecosystems, will be evaluated by gradient studies and other spatial synoptic studies in addition to the national trends network. Gradient studies and similar synoptic studies for streams take a “space-for-time” approach to assessing change, which relies on assessment of a large number of streams with different degrees of watershed urbanization or agriculture to estimate trends likely to occur in individual streams that undergo land-use changes. Space-for-time studies will also be used to assess effects of land-use change on ground water quality, but these studies will focus on evaluating changes in water quality along ground water flowpaths at various points in relation to the times that land-use changes have occurred. The spatial studies of effects of land-use change will be closely integrated with targeted studies of governing factors.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program V. Targeted Studies of Factors That Govern Water-Quality: The complete set of Cycle II themes and objectives for understanding factors that control water quality define a broad range of scientific and management-related issues that can only partially be addressed by Cycle II investigations, even in all three groups of study units. The approach taken in the Cycle II design is to focus studies of governing factors on a limited set of the most important water quality topics within the scope of the priority themes, and to link these studies closely to related studies and data that will be collected for other parts of the Cycle II design. These carefully targeted studies will be designed and executed by topical teams formed from national synthesis teams, study units, and other scientists. I. ENVIRONMENTAL FRAMEWORK FOR DESIGN The environmental framework is the systematically characterized set of natural and anthropogenic characteristics of the landscape that geographically define the factors that we expect to influence water quality, including the significance of water quality to natural systems and the uses of water by humans. Many factors that affect the sources, behavior, and effects of contaminants and water-quality conditions are common to most hydrologic systems, although in widely varying degrees of importance. These common natural and human-related factors, such as soil characteristics and land use, provide a unifying framework for making comparative assessments of water quality within and among hydrologic systems at a wide range of scales and characteristics in different parts of the Nation. Characterizing this environmental framework was an essential element of the Cycle I status assessment that cut across all individual water-quality issues and components of Study-Unit and National-Synthesis studies (Gilliom et al., 1995). Specific factors included in the environmental framework are used to compare and contrast findings on water quality within and among NAWQA Study Units in relation to causative factors and, ultimately, to develop inferences about water quality in areas that have not been sampled. Cycle I results, for example, have enabled the development of predictive relations between estimated pesticide use on agricultural land and natural hydrologic characteristics so that pesticide concentrations can be estimated for unmeasured streams. For Cycle II design, experiences from Cycle I, improvements in national data for some natural and anthropogenic factors, and the necessity of systematically evaluating the influence of factors controlling water quality in order to meet Cycle II objectives, have placed even greater emphasis on the environmental framework to guide NAWQA studies.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program II. NATIONAL TREND NETWORKS Overview The primary goals of the National Trends Networks are to systematically assess long-term trends and changes in the quality of the nation’s streams and ground water and to relate observed trends and changes to probable causes. The three National Trends Networks are: (1) Trend Network for Streams, which focuses on the chemical and physical quality of water and stream ecosystems, (2) Trend Network for Contaminants in Sediment, which focuses on particle-associated trace elements and organic contaminants, and (3) Trend Network for Ground Water, which focuses on the chemical and physical quality of ground water. In addition to addressing trend assessment goals, the intensive, long-term data collection at the sites and study areas of the trend networks form the foundation for spatial studies of the effects of land-use change on water quality and for targeted studies of factors that govern water quality, which are a major emphasis of Cycle II. Because of this foundational role that the trend networks play in the Cycle II design, the requirements for these related studies are an important consideration in design of the trend networks. Themes and Objectives The themes and specific objectives addressed to substantial but variable degrees by the trends networks are listed below, including planning estimates of the percentage of Cycle II HIP budget to be allocated to each theme. Trends and changes in status of resource —What are the trends and changes in the status of water quality since the NAWQA Cycle I status assessment and before? Objective (T1) Determine long-term trends and changes in the concentrations of NAWQA target constituents in (a) the most important principal aquifers used for drinking-water supply and (b) recently recharged ground water upgradient of these principal aquifers in a nationally representative range of hydrologic and land use settings. Objective (T2) Determine long-term trends and changes in concentrations and loads of NAWQA target constituents, and the condition of aquatic biota and stream ecosystems for (a) streams and watersheds representative of the primary hydrologic landscape and ecoregion settings present in the study units, (b) a diversity of important stream ecosystems present in study units, (c) streams and watersheds representative of agricultural, urban, reference,

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program transitional or mixed land-use settings in the Nation, and (d) the most important streams used for drinking-water supply. Response to urbanization—How has water quality changed in response to urbanization? Objective (T3) Determine the effects of urbanization on the concentrations and distributions of NAWQA target constituents in ground water. Objective (T4) Determine the effects of urbanization on the concentrations and distributions of NAWQA target constituents in streams and watersheds and on stream ecosystems. Response to agricultural management practices—How has water quality changed in response to long-term changes in agricultural management practices such as tillage methods, chemical use, and crop patterns? Objective (T5) Determine the effects of long-term changes in agricultural management practices on the concentrations and distributions of NAWQA target constituents in ground water. Objective (T6) Determine the effects of long-term changes in agricultural management practices on the concentrations and distributions of NAWQA target constituents in streams and watersheds and on stream ecosystems. III. NEW STATUS ASSESSMENTS Overview The primary goals of Cycle II status assessments are to complete essential unfinished status assessment from Cycle I and selectively expand into new status-assessment issues that become high national priorities. The main components of the Cycle II design for new status assessment are: (1) New Stream Monitoring Sites, (2) New Ground Water Surveys, (3) New Contaminant Surveys, which focus on analyses of selected contaminants not extensively assessed in Cycle I, and (4) Drinking-Water Source Assessments. The New Stream Monitoring Sites and Ground-Water Surveys primarily target water resources in environmental settings not adequately represented in Cycle I. In most cases, these studies are also candidates for addition to the National Trends Network and many will be an integral part of data collection for topical studies of factors that govern water quality.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program Themes and Objectives Resources not previously sampled—What is the quality of the most important stream and ground-water resources not sampled during Cycle I? Objective (S1) Characterize the concentrations and distributions of NAWQA target constituents in principal aquifers and selected rivers and streams that were not characterized during Cycle I. Objective (S2) Characterize the concentrations of NAWQA target constituents in downgradient shallow ground water and streams for: (a) residential/ commercial development in large metropolitan areas, and (b) the most extensive agricultural settings in the Nation. Drinking-water sources—What are the concentrations and frequencies of occurrence of NAWQA target constituents in aquifers and streams used as sources of drinking water? Objective (S3) Characterize the concentrations and distributions of NAWQA target constituents in aquifers and streams that have the greatest withdrawals of drinking water. Objective (S4) Improve the reporting and explanation of the potential risk to human health due to the presence of contaminant mixtures that are frequently found in current or potential sources of drinking water. Contaminants not previously sampled—What is the occurrence and distribution of contaminants not yet measured by NAWQA, such as pathogens, new pesticides, pharmaceutical products, high production volume industrial chemicals and others? Objective (S5) Characterize the frequencies of occurrence and concentrations of emerging contaminants in streams and aquifers that are sources of drinking water and in streams representative of the potential ecological effects from urban and agricultural land uses. Objective (S6) Characterize the concentrations and distributions of total and methyl mercury in streams that have the greatest potential for human exposure to mercury through consumption of drinking water or fish.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program IV. SPATIAL STUDIES OF EFFECTS OF LAND-USE CHANGE ON WATER QUALITY4 Overview The NAWQA trend networks for streams and ground water monitor trends by systematic sampling over time at carefully selected sites and study areas that represent key water resources and land uses. Although the trend networks are the only approach in the NAWQA design to assessing trends in major aquifers and rivers, they only partially address trend issues related to changes in urban and agricultural areas. In particular, effects of urban and agricultural land use on aquatic biota and stream ecosystems are not possible to adequately assess, and interpretive analysis of the causes of water-quality trends in urban and agricultural settings is generally not possible from results of the trend network alone. In order to address Cycle II trend themes aimed at water-quality changes due to urbanization and changes in agricultural land and management practices, studies of a range of spatial studies are necessary, which are closely integrated with the trend networks and the topical studies undertaken to examine the factors that govern water quality. These studies use interpretation of spatial patterns to evaluate temporal changes in water-quality factors of interest. V. TARGETED STUDIES OF FACTORS THAT GOVERN WATER QUALITY Overview A principal goal of Cycle II is to improve explanation and understanding of the sources of contaminants, their transport through the hydrologic system, the effects of contaminants and physical alterations on stream biota and ecosystems, and implications for the quality of drinking water. Furthermore, this understanding will be the basis for predicting water-quality conditions for unsampled geographic areas (extrapolate) and future conditions (forecast). The potential scope of this explanation and understanding goal is very broad and NAWQA contributions will have to be carefully targeted to specific questions that make important contributions to the field, address the most important problems, reasonably fit within the objectives and of NAWQA, and build on Cycle I results. The approach to addressing this goal in Cycle II has two main components: (1) targeted studies of carefully chosen topics that directly relate to factors that govern water quality, and (2) the formation of a national study team focused on hydrologic systems 4   Subsequent to the November 2000 version of this report, the ground water part of this section was moved to ground water trends section and the surface water part was planned to be moved to targeted studies section.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program analysis which will be integrally involved with the topical study teams and national synthesis teams. Themes and Objectives Themes and objectives for understanding sources and transport of contaminants and their effects on stream ecosystems and drinking water sources comprise a complex and highly interrelated set of study requirements. The four major topical areas are sources, transport processes, ecological effects, and extrapolation and forecasting. Sources of contaminants—Identify and quantify the natural and anthropogenic sources of contaminants to surface and ground waters. Objective (U1) Large-scale sources: Identify and quantify the most important large-scale natural and anthropogenic sources of selected contaminants to major streams and aquifers with mixed land use influences and contaminant sources. Objective (U2) Urban and agricultural sources: Identify and quantify the most important sources of selected contaminants to recently recharged ground water and to streams within urban and agricultural settings. Objective (U3) Spatial and temporal aspects of sources: Characterize and determine the relative importance of spatial, seasonal, and short- and long-term inter-annual variability of natural and anthropogenic sources of contaminants to surface and ground waters. Objective (U4) Mobilizing and metabolizing sources: Determine the relative influence of natural processes and human activities in creating contaminants or mobilizing naturally occurring contaminants. Transport processes: Contaminant movement from land surface to ground water—What is the relative importance of biogeochemical and physical processes in influencing the transport and transformation of surface- and in-situ derived contaminants in the unsaturated zone and ground water as they are transported from land surface to shallow ground water to underlying aquifers? Objective (U5) Saturated zone transport: Examine the extent to which the concentrations of specific contaminants in surficial aquifers are related to (a) types and distributions of land use in their recharge areas, (b) distributions of ground-water residence times, and (c) physical and biogeochemical processes in the saturated zone.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program Objective (U6) Unsaturated zone transport: Examine the influence of natural and anthropogenic factors on the concentrations and transformations of specific contaminants in the unsaturated zone, and on their flux through the unsaturated zone to shallow ground water. Transport processes: Contaminant movement from land surface to surface water and downstream—How are contaminants transported—and with what losses and transformations—from land surfaces to streams and downstream to rivers, reservoirs, and coastal water? Objective (U7) Land surface to stream transport: Determine how differences in watershed characteristics (e.g. soils, terrain, climate, geology) affect the transport of contaminants from watershed land surfaces into streams. Objective (U8) Within-stream transport: Determine how differences in characteristics of the stream within its catchment (e.g. terrain, climate) affect the transport of contaminants along streams. Transport processes: Ground-water/surface-water interactions—What is the role of exchanges and interactions between ground water and surface water in determining the degree and timing of contaminant levels and their effects on water quality? Objective (U9) Large-scale ground-water/surface-water interactions: Determine the influence of ground-water quality on stream quality and the influence of stream quality on ground-water quality at stream-reach and larger scales in a broad range of environmental settings. Objective (U10) Small scale ground-water/surface-water interactions: Evaluate the effects of the riparian zone, including near-stream wetlands, various land uses/land covers, and land-management practices, on exchanges of water and associated chemicals in all directions between the land surface, shallow ground water, hyporheic zone, and streams. Objective (U11) Hyporheic zone ground-water/surface-water interactions: Increase understanding of the role of the hyporheic zone on the transport and fate of contaminants in both ground water and surface water. Effects on stream ecosystems—What are the effects on stream biota and ecosystems of contaminants, contaminant mixtures, habitat modification or alteration, and other stressors? Objective (U12) Ecological effects of contaminants: Evaluate sediment or

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program water toxicity at sites representing the range of environmental concentrations and mixtures of contaminants. At sites found to be toxic, determine concentrations and mixtures present in sediment and/or water and screen selected biota for physiological indicators of exposure such as biomarkers, as appropriate based on contaminants present. Objective (U13) Ecological effects of nutrient enrichment: Evaluate the relation between community structure and trophic dynamics among streams receiving varying levels of enrichment from allochthonous C, N, and P. Objective (U14) Ecological effects of habitat modification: Characterize and evaluate the relation between stream flow characteristics, physical habitat and community structure. Extrapolation and forecasting—How can we best extrapolate (spatial dimension) or forecast (temporal dimension) water-quality conditions for unmeasured geographic areas and future conditions (after management changes), based on knowledge of land use and contaminant sources, natural characteristics of the land and hydrologic system, and our understanding of governing processes? Objective (U15) Evaluation of empirical extrapolation and forecasting models: Develop, evaluate, and improve empirical models for spatial extrapolation and forecasting using statistically based methods such as regression analysis. Objective (U16) Evaluation of deterministic extrapolation and forecasting models: Systematically evaluate and test selected existing simulation models for their potential value in extrapolation and forecasting of water quality in streams and ground water. Objective (U17) Application of extrapolation and forecasting models: Apply the most appropriate empirical and deterministic models to specific extrapolation and forecasting objectives. REFERENCES Gilliom, R. J., W. M. Alley, and M. E. Gurtz. 1995. Design of the National Water Quality Assessment Program—Occurrence and Distribution of Water-Quality Conditions. U.S. Geological Survey Circular 1112. Sacramento, Calif.: U.S. Geological Survey. Gilliom, R. J., K. Bencala, W. Bryant, C. A. Couch, N. M. Dubrovsky, D. Helsel, I. James, W. W. Lapham, M. A. Sylvester, J. Stoner, W. G. Wilber, D. M. Wolock, and J. Zogorski. 2000a. Prioritization and Selection of Study Units for Cycle II of NAWQA. U.S. Geological Survey NAWQA Cycle II Implementation Team. Draft for internal review (1/12/2000). Sacramento, Calif.: U.S. Geological Survey.

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Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program Gilliom, R. J., K. Bencala, W. Bryant, C. A. Couch, N. M. Dubrovsky, L. Franke, D. Helsel, I. James, W. W. Lapham, D. Mueller, J. Stoner, M. A. Sylvester, W. G. Wilber, D. M. Wolock, and J. Zogorski. 2000b. Study-Unit Design Guidelines for Cycle II of the National Water Quality Assessment (NAWQA). U.S. Geological Survey NAWQA Cycle II Implementation Team. Draft for internal review (11/22/2000). Sacramento, Calif.: U.S. Geological Survey. Mallard, G. E., J. T. Armbruster, R. E. Broshears, E. J. Evenson, S. N. Luoma, P. J. Phillips, and K. R. Prince. 1999. Recommendations for Cycle II of National Water-Quality Assessment (NAWQA) Program . U.S. Geological Survey NAWQA Planning Team. U.S. Geological Survey Open-File Report 99-470. Reston, Va.: U.S. Geological Survey.