Water-Quality Trends in the Nation's Rivers and Streams, 1972–2012—Data Preparation

158 Pages·2017·9.88 MB·English

National Water-Quality Assessment Project of the U.S. Geological Survey’s
National Water-Quality Program
Water-Quality Trends in the Nation’s Rivers and Streams,
1972–2012—Data Preparation, Statistical Methods,
and Trend Results
Scientific Investigations Report 2017–5006
U.S. Department of the Interior
U.S. Geological Survey
1 2
3
Cover.
Background. Dismal River near Thedford, Nebraska (site 06775900), August 16, 2016. Photograph by Robert E. Zuellig, U.S. Geological Survey (USGS).
1. Water-quality sampling from the Colorado River near the Colorado-Utah State line. Photograph by Nancy Bauch, USGS.
2. Vallecito Creek near Bayfield, Colorado (site 09352900), August 25, 2016. Photograph by Robert E. Zuellig, USGS.
3. Riverweed darter (Etheostoma podostemone) found in the Roanoke River, Roanoke County, Virginia. Photograph by Robert E. Zuellig, USGS.
Water-Quality Trends in the Nation’s
Rivers and Streams, 1972–2012—Data
Preparation, Statistical Methods, and Trend
Results
By Gretchen P. Oelsner, Lori A. Sprague, Jennifer C. Murphy,
Robert E. Zuellig, Henry M. Johnson, Karen R. Ryberg, James A. Falcone,
Edward G. Stets, Aldo V. Vecchia, Melissa L. Riskin, Laura A. De Cicco,
Taylor J. Mills, and William H. Farmer
National Water-Quality Assessment Project of the U.S. Geological Survey’s
National Water-Quality Program
Scientific Investigations Report 2017–5006
U.S. Department of the Interior
U.S. Geological Survey
U.S. Department of the Interior
RYAN K. ZINKE, Secretary
U.S. Geological Survey
William H. Werkheiser, Acting Director
U.S. Geological Survey, Reston, Virginia: 2017
For more information on the USGS—the Federal source for science about the Earth, its natural and living
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Suggested citation:
Oelsner, G.P., Sprague, L.A., Murphy, J.C., Zuellig, R.E., Johnson, H.M., Ryberg, K.R., Falcone, J.A., Stets, E.G., Vec-
chia, A.V., Riskin, M.L., De Cicco, L.A., Mills, T.J., and Farmer, W.H., 2017, Water-quality trends in the Nation’s rivers
and streams, 1972–2012—Data preparation, statistical methods, and trend results: U.S. Geological Survey Scientific
Investigations Report 2017–5006, 136 p., https://doi.org/10.3133/sir20175006.
ISSN 2328-0328 (online)
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Foreword
Sustaining the quality of the Nation’s water resources and the health of our diverse ecosystems
depends on the availability of sound water-resources data and information to develop effective,
science-based policies. Effective management of water resources also brings more certainty and
efficiency to important economic sectors. Taken together, these actions lead to immediate and
long-term economic, social, and environmental benefits that make a difference to the lives of
the almost 400 million people projected to live in the United States by 2050. (http://water.usgs.
gov/nawqa/applications/).
In 1991, Congress established the National Water-Quality Assessment (NAWQA) to address
where, when, why, and how the Nation’s water quality has changed, or is likely to change in
the future, in response to human activities and natural factors. Since then, NAWQA has been
a leading source of scientific data and knowledge used by national, regional, State, and local
agencies to develop science-based policies and management strategies to improve and pro-
tect water resources used for drinking water, recreation, irrigation, energy development, and
ecosystem needs. Plans for the third decade of NAWQA (2013–23) address priority water-quality
issues and science needs identified by NAWQA stakeholders, such as the Advisory Committee
on Water Information, and the National Research Council as the Nation faces increasing chal-
lenges related to population growth, increasing needs for clean water, and changing land-use
and weather patterns.
Federal, State, and local agencies have invested billions of dollars to reduce the amount of
pollution entering rivers and streams that millions of Americans rely on for drinking water,
recreation, and irrigation. Tracking changes in the quality of these waterways over multiple
decades is crucial for evaluating the effectiveness of pollution control efforts and protecting the
Nation’s water resources into the future. This report combines monitoring data collected by 74
organizations at almost 1,400 sites to provide a nationwide look at changes in the quality of our
rivers and streams from 1972 to 2012—the 40 years since passage of the Clean Water Act. All
NAWQA reports are available online (https://water.usgs.gov/nawqa/bib/).
We hope this publication will provide you with insights and information to meet your water
resource needs and will foster increased citizen awareness and involvement in the protection
and restoration of our Nation’s waters. The information in this report is intended primarily for
those interested or involved in resource management and protection, conservation, regulation,
and policymaking at the regional and national level.
Dr. Gary L. Rowe
Program Coordinator, National Water Quality Program
U.S. Geological Survey
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Contents
Foreword ........................................................................................................................................................iii
Abstract ...........................................................................................................................................................1
Introduction.....................................................................................................................................................1
Objectives and Scope ...................................................................................................................................2
Methods...........................................................................................................................................................2
Water-Quality, Pesticide, and Ecology Data Compilation ..............................................................2
Streamflow Data Compilation .............................................................................................................3
Streamgage Matching .........................................................................................................................3
Indexing Water-Quality Sites and Streamgages to the National
Hydrography Dataset Network ..................................................................................17
Identifying Groups of Near-Colocated Sites .........................................................................18
Streamgage Selection ..............................................................................................................18
Initial Streamgage Match and Compilation of Water-Quality
Site-Streamgage Combinations .......................................................................18
Evaluating Intervening Influences Between Water-Quality
Site-Streamgage Combinations ........................................................................19
Screening Streamflow Record for Streamflow Continuity ........................................19
Selecting the Preferred Water-Quality Site-Streamgage Combinations ................20
Variations in Streamgage Selection Process for Pesticide
and Ecology Sites ................................................................................................20
Scaling Streamflow Records .........................................................................................21
Water-Quality Data Preparation .......................................................................................................22
Paired Sample Evaluation ........................................................................................................23
Ammonia.............................................................................................................................26
Kjeldahl Nitrogen ..............................................................................................................26
Nitrate .................................................................................................................................26
Nitrite ..................................................................................................................................27
Nitrite Plus Nitrate ............................................................................................................27
Orthophosphate ................................................................................................................28
Total Phosphorus ..............................................................................................................28
Suspended Sediment .......................................................................................................28
Chloride...............................................................................................................................28
Sulfate ................................................................................................................................29
Alkalinity .............................................................................................................................29
Replicate Evaluation .........................................................................................................30
Nutrient Parameters of Interest and Harmonization ...........................................................30
Nutrient Data Processing ................................................................................................32
Unfiltered and Filtered Fractions ...........................................................................32
Discrete Samples .....................................................................................................33
Samples Analyzed in the Field ...............................................................................33
Remark Code Harmonization ............................................................ 33
Adjustments to U.S. Geological Survey Data Based on Historical
Memorandums and Reports .....................................................................34
Recensoring U.S. Geological Survey Data ..........................................................34
Duplicate Samples ..................................................................................................35
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Zero, Negative, and Missing Concentration Values ..........................................35
Calculation of Target Parameters .........................................................................36
Identification of a Colocated or Nearby Streamgage .......................................37
Merging Colocated or Neighboring Water-Quality Sites ..................................37
Degree of Censoring ...............................................................................................37
Outliers ......................................................................................................................37
Data Thinning ...........................................................................................................38
Final Screening for Data Coverage ................................................................................38
Coverage Throughout Target Trend Periods .......................................................38
Coverage of Changing Seasons ............................................................................38
Coverage of Changing Streamflow .......................................................................39
Data Used in Model Calibration .....................................................................................39
Sediment Parameters of Interest and Harmonization .........................................................39
Sediment Data Processing .............................................................................................41
Discrete Samples .....................................................................................................41
Samples Analyzed in the Field ...............................................................................41
Remark Code Harmonization .................................................................................41
Duplicate Samples ..................................................................................................41
Zero, Negative, and Missing Concentration Values ..........................................42
Identification of a Colocated or Nearby Streamgage .......................................42
Merging Colocated or Neighboring Water-Quality Sites ..................................42
Degree of Censoring ...............................................................................................42
Outliers ......................................................................................................................43
Data Thinning ...........................................................................................................43
Final Screening for Data Coverage ................................................................................43
Coverage Throughout Target Trend Periods .......................................................43
Coverage of Changing Seasons ............................................................................44
Coverage of Changing Streamflow .......................................................................44
Data Used in Model Calibration .....................................................................................44
Major Ion and Salinity Parameters of Interest and Harmonization ...................................44
Major Ion and Salinity Data Processing ......................................................................45
Unfiltered and Filtered Fractions ...........................................................................45
Discrete Samples .....................................................................................................45
Samples Analyzed in the Field ...............................................................................46
Remark Code Harmonization .................................................................................46
Recensoring U.S. Geological Survey Data ..........................................................46
Duplicate Samples ..................................................................................................47
Zero, Negative, and Missing Concentration Values ..........................................47
Identification of a Colocated or Nearby Streamgage .......................................47
Merging Colocated or Neighboring Water-Quality Sites ..................................47
Degree of Censoring ...............................................................................................48
Outliers ......................................................................................................................48
Data Thinning ...........................................................................................................48
Final Screening for Data Coverage ................................................................................48
Coverage Throughout Target Trend Periods .......................................................48
Coverage of Changing Seasons ............................................................................49
Coverage of Changing Streamflow .......................................................................49
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Data Used in Model Calibration .....................................................................................50
Carbon Parameters of Interest and Harmonization .............................................................50
Carbon Data Processing .................................................................................................51
Unfiltered and Filtered Fractions ...........................................................................51
Discrete Samples .....................................................................................................51
Samples Analyzed in the Field ...............................................................................51
Remark Code Harmonization .................................................................................51
Recensoring U.S. Geological Survey Data ..........................................................52
Duplicate Samples ..................................................................................................52
Zero, Negative, and Missing Concentration Values ..........................................53
Calculation of Target Parameters .........................................................................53
Identification of a Colocated or Nearby Streamgage .......................................53
Merging Colocated or Neighboring Water-Quality Sites ..................................53
Degree of Censoring ...............................................................................................54
Outliers ......................................................................................................................54
Data Thinning ...........................................................................................................54
Final Screening for Data Coverage ................................................................................54
Coverage Throughout Target Trend Periods .......................................................54
Coverage of Changing Seasons ............................................................................55
Coverage of Changing Streamflow .......................................................................55
Data Used in Model Calibration .....................................................................................55
Pesticide Data Preparation and Parameters of Interest ..............................................................56
Pesticide Data Processing .......................................................................................................58
Recensoring National Water Quality Laboratory Data and
Preparation of Data for Trend Analysis ...........................................................58
Degree of Censoring ........................................................................................................58
Data Thinning ....................................................................................................................58
Final Screening for Data Coverage .........................................................................................58
Coverage Throughout Target Trend Periods ................................................................58
Coverage of Changing Seasons .....................................................................................59
Coverage of Changing Streamflow ................................................................................59
Identification of a Colocated or Nearby Streamgage ................................................59
Merging Colocated or Neighboring Sites .....................................................................59
Zero and Missing Streamflows ......................................................................................59
Data Used in Model Calibration ..............................................................................................60
Ecology Data Preparation .................................................................................................................60
Data and Trend Screening for Site and Sample Selection .................................................60
Ecology Data Processing ........................................................................................................60
Taxonomic Harmonization and Resolving Ambiguous Taxa ......................................60
Fish .............................................................................................................................60
Invertebrates ............................................................................................................61
Algae ..........................................................................................................................61
Ecological Endpoints .......................................................................................................61
Fish Endpoints ..........................................................................................................61
Invertebrate Endpoints ...........................................................................................63
Diatom Endpoints .....................................................................................................64
Associated Environmental Variables ......................................................................................64
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Antecedent Hydrology .....................................................................................................65
Day of the Year ..................................................................................................................65
Trend Analysis Methods ....................................................................................................................66
Nutrient, Sediment, Major Ion, Salinity, and Carbon Trend Analysis Method ................66
Pesticide Trend Method ............................................................................................................68
Ecology Trend Method .............................................................................................................71
Limitations on Trend Analysis and Effects on the Weighted Regressions
on Time, Discharge, and Season (WRTDS) Model Estimates ........................................71
Storm Sampling ..........................................................................................................................71
Sampling Frequency ..................................................................................................................77
Rounding of Water-Quality Data .............................................................................................87
Influence of New Data on Trend Estimates ...........................................................................87
Limitations on Trend Analysis with the Seasonal Wave (SEAWAVE–Q) Model ......................96
Limitations of the Ecology Trend Method .......................................................................................96
Laboratory Method and Performance Considerations for Trend Interpretation ......................96
National Water Quality Laboratory Method and Procedure Changes ..............................96
Changes in Laboratory Analysis and Sample Collection Methods ...................................96
Laboratory Performance Bias Evaluation .............................................................................97
Site-Specific Considerations when Modeling Trends with the Weighted
Regressions on Time, Discharge, and Season (WRTDS) Model ..................................98
Step Changes in Water-Quality Data ......................................................................................98
Trends in Streamflow ................................................................................................................98
Gradual Changes in Streamflow ....................................................................................99
Abrupt Changes in Streamflow ....................................................................................102
Trend Results ..............................................................................................................................................103
Nutrient, Sediment, Major Ion, Salinity, and Carbon Results ....................................................103
Pesticide Results...............................................................................................................................124
Ecology Results .................................................................................................................................124
Diatom Trend Result Example ................................................................................................126
Fish Trend Result Example ......................................................................................................128
Summary......................................................................................................................................................128
Acknowledgments.. ...................................................................................................................................130
References ..................................................................................................................................................130
Appendixes [available at https://doi.org/10.3133/sir20175006]
1. Streamflow, Water–Quality, and Ecology Sites Included in Trend Analysis
2. Variations in Parameter Reporting for Selected Parameters
3. Laboratory Method and Change Timeline
4. Step-Trend Analysis of Changes in Laboratory Analysis and
Sample Collection Methods
5. Laboratory Performance Bias Evaluation Using Percent Recovery in U.S. Geological
Survey Branch of Quality Systems Double-Blind Reference Samples over Time
6. Analysis of Trends in Annual Streamflow
7. Trend Results
8. Comparison of Trends Determined Using the Seasonal Kendall Test and the
Weighted Regressions on Time, Discharge, and Season Model