Meridian and the Sacramento River Aerial photo, altitude of 1,000 feet, Sutter County, California Nikon 4004, 80 mm — 200 mm zoom lens f/2.8, color January 7, 1997  Rand Schaal Metals Transport in the Sacramento River, California, 1996–1997 Volume 2: Interpretation of Metal Loads Charles N. Alpers, Ronald C. Antweiler, Howard E. Taylor, Peter D. Dileanis, and Joseph L. Domagalski U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 00-4002 In cooperation with Sacramento Regional County Sanitation District California State Water Resources Control Board U.S. Environmental Protection Agency U.S. Department of Commerce, National Marine Fisheries Service 0 1 - 1 1 2 6 Sacramento, California 2000 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey For additional information write to: Copies of this report can be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Branch of Information Services Water Resources Division Box 25286 Placer Hall Denver, CO 80225-0286 6000 J Street Sacramento, California 95819-6129 FOREWORD assessments thereby build local knowledge about water- The U.S. Geological Survey (USGS) is committed to serve the Nation with accurate and timely scientific infor- quality issues and trends in a particular stream or aquifer mation that helps enhance and protect the overall quality of while providing an understanding of how and why water life, and facilitates effective management of water, biologi- quality varies regionally and nationally. The consistent, cal, energy, and mineral resources. (http://www.usgs.gov/). multi-scale approach helps to determine if certain types of Information on the quality of the Nation’s water resources is water-quality issues are isolated or pervasive, and allows of critical interest to the USGS because it is so integrally direct comparisons of how human activities and natural pro- linked to the long-term availability of water that is clean and cesses affect water quality and ecological health in the safe for drinking and recreation and that is suitable for Nation’s diverse geographic and environmental settings. industry, irrigation, and habitat for fish and wildlife. Esca- Comprehensive assessments on pesticides, nutrients, vola- lating population growth and increasing demands for the tile organic compounds, trace metals, and aquatic ecology multiple water uses make water availability, now measured are developed at the national scale through comparative in terms of quantity and quality, even more critical to the analysis of the Study-Unit findings. (http://water.usgs.gov/ long-term sustainability of our communities and ecosys- nawqa/natsyn.html). tems. The USGS implemented the National Water-Quality The USGS places high value on the communication Assessment (NAWQA) Program to support national, and dissemination of credible, timely, and relevant science regional, and local information needs and decisions related so that the most recent and available knowledge about water to water-quality management and policy. (http:// resources can be applied in management and policy deci- water.usgs.gov/nawqa). Shaped by and coordinated with sions. We hope this NAWQA publication will provide you ongoing efforts of other Federal, State, and local agencies, the needed insights and information to meet your needs, and the NAWQA Program is designed to answer: What is the thereby foster increased awareness and involvement in the condition of our Nation’s streams and ground water? How protection and restoration of our Nation’s waters. are the conditions changing over time? How do natural fea- tures and human activities affect the quality of streams and The NAWQA Program recognizes that a national ground water, and where are those effects most pro- assessment by a single program cannot address all water- nounced? By combining information on water chemistry, resource issues of interest. External coordination at all lev- physical characteristics, stream habitat, and aquatic life, the els is critical for a fully integrated understanding of water- NAWQA Program aims to provide science-based insights sheds and for cost-effective management, regulation, and for current and emerging water issues and priorities. conservation of our Nation’s water resources. The Program, NAWQA results can contribute to informed decisions that therefore, depends extensively on the advice, cooperation, result in practical and effective water-resource management and information from other Federal, State, interstate, Tribal, and strategies that protect and restore water quality. and local agencies, non-government organizations, industry, Since 1991, the NAWQA Program has implemented academia, and other stakeholder groups. The assistance and interdisciplinary assessments in more than 50 of the suggestions of all are greatly appreciated. Nation’s most important river basins and aquifers, referred to as Study Units. (http://water.usgs.gov/nawqa/ nawqamap.html). Collectively, these Study Units account for more than 60 percent of the overall water use and popu- lation served by public water supply, and are representative of the Nation’s major hydrologic landscapes, priority eco- logical resources, and agricultural, urban, and natural sources of contamination. Each assessment is guided by a nationally consistent Robert M. Hirsch study design and methods of sampling and analysis. The Associate Director for Water CONTENTS Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Previous Work and Related Ongoing Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Computation of Metal Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Dissolved Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Colloidal Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Transport Plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Total Recoverable Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Colloid Speciation Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Uncertainties in Metal Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Discussion of Spatial and Temporal Variations in Metal Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Temporal Variations in Dissolved and Colloidal Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Cadmium, Copper, and Zinc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Lead, Aluminum, and Iron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Discussion of Transport and Fate of Metals from Various Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Copper-Zinc-Lead Mines in the Shasta Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Mines Draining into Shasta Lake and Its Tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Mines Draining into Keswick Reservoir and Its Tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Mass Balance and Metal Transport in Keswick Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Mass Balance in the Spring Creek Arm of Keswick Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Overall Mass Balance in Keswick Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Metal Sources Downstream of Keswick Dam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Tributaries Between Keswick Dam and Colusa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Tributaries Between Colusa and Freeport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Agricultural Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Urban Runoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Appendix 1. Tables of Data Comparing Metal Loads in Dissolved Form, Colloidal Form, and Whole Water. . . . . . . . . . 57 Appendix 2. Tables of Data Comparing Metal Loads Relative to Loads at Freeport and in the Yolo Bypass. . . . . . . . . . . 73 Appendix 3. Tables of Data Comparing Metal Loads Used in Mass Balance Calculations for the Spring Creek Arm of Keswick Reservoir. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Appendix 4. Tables of Data Comparing Metal Loads Used in Mass Balance Calculations for Keswick Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Appendix 5. Plots of Metal Loads in Dissolved and Colloidal Forms for Miscellaneous Trace Metals in Water . . . . . . . 97 Appendix 6. Hydrographs Showing Daily Mean Discharge and Time of Sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Contents v FIGURES 1.Location map of Sacramento River watershed, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.Location map of West Shasta mining district, Shasta County, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3A. Diagram showing magnitude of mean discharge in the Sacramento River, California, relative to major tributaries and diversions during the July 11–18, 1996 sampling period . . . . . . . . . . . . . . . . . . . . . . . . 10 3B. Diagram showing magnitude of mean discharge in the Sacramento River, California, relative to major tributaries and diversions during the September 18–26, 1996sampling period . . . . . . . . . . . . . . . . . . . . 11 3C. Diagram showing magnitude of mean discharge in the Sacramento River, California, relative to major tributaries and diversions during the November 12–22, 1996 sampling period . . . . . . . . . . . . . . . . . . . . 12 3D. Diagram showing magnitude of mean discharge in the Sacramento River, California, relative to major tributaries and diversions during the December 11–18, 1996 sampling period . . . . . . . . . . . . . . . . . . . 13 3E. Diagrams showing magnitude of mean discharge in the Sacramento River, California, relative to major tributaries and diversions during the January 2–8, 1997 sampling period . . . . . . . . . . . . . . . . . . . . . . . . 14 3F. Diagrams showing magnitude of mean discharge in the Sacramento River, California, relative to major tributaries and diversions during the May 28–June 6, 1997 sampling period . . . . . . . . . . . . . . . . . . . . . 15 4. Plot of dissolved and colloidal aluminum loads, July 1996 to May–June 1997, Sacramento River, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 5. Plot of dissolved and colloidal cadmium loads, July 1996 to May–June 1997, Sacramento River, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 6. Plot of dissolved and colloidal copper loads, July 1996 to May–June 1997, Sacramento River, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7. Plot of dissolved and colloidal iron loads, July 1996 to May–June 1997, Sacramento River, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 8. Plot of dissolved and colloidal lead loads, July 1996 to May–June 1997, Sacramento River, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 9. Plot of dissolved and colloidal zinc loads, July 1996 to May–June 1997, Sacramento River, California . . . . . 21 10. Plots of dissolved and colloidal aluminum loads, colloid concentration, aluminum concentration in colloids, and discharge, Sacramento River, California for A. July 1996, B. September 1996, C. November 1996, D. December 1996, E. January 1997, and F. May–June 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 11. Plots of dissolved and colloidal cadmium loads, colloid concentration, cadmium concentration in colloids, and discharge, Sacramento River, California for A. July 1996, B. September 1996, C. November 1996, D. December 1996, E. January 1997, and F. May–June 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 12. Plots of dissolved and colloidal copper loads, colloid concentration, copper concentration in colloids, and discharge, Sacramento River, California for A. July 1996, B. September 1996, C. November 1996, D. December 1996, E. January 1997, and F. May–June 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 13. Plots of dissolved and colloidal iron loads, colloid concentration, iron concentration in colloids, and discharge, Sacramento River, California for A. July 1996, B. September 1996, C. November 1996, D. December 1996, E. January 1997, and F. May–June 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 14. Plots of dissolved and colloidal lead loads, colloid concentration, lead concentrations in colloids, and discharge, Sacramento River, California for A. July 1996, B. September 1996, C. November 1996, D. December 1996, E. January 1997, and F. May–June 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 15. Plots of dissolved and colloidal zinc loads, colloid concentration, zinc concentrations in colloids, and discharge, Sacramento River, California for A. July 1996, B. September 1996, C. November 1996, D. December 1996, E. January 1997, and F. May–June 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 vi Contents 16A. Distribution and speciation of colloidal cadmium loads during December 1996, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 16B. Distribution and speciation of colloidal copper loads during December 1996, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 16C. Distribution and speciation of colloidal lead loads during December 1996, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 16D. Distribution and speciation of colloidal zinc loads during December 1996, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 17A. Distribution and speciation of colloidal cadmium loads during January 1997, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 17B. Distribution and speciation of colloidal copper loads during January 1997, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 17C. Distribution and speciation of colloidal lead loads during January 1997, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 17D. Distribution and speciation of colloidal zinc loads during January 1997, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 18A. Distribution and speciation of colloidal cadmium loads during May–June 1997, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 18B. Distribution and speciation of colloidal copper loads during May–June 1997, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 18C. Distribution and speciation of colloidal lead loads during May–June 1997, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 18D. Distribution and speciation of colloidal zinc loads during May–June 1997, Sacramento River, California, and selected tributaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 19. Plots of suspended sediment concentration (A) and load (B) versus stream flow at Freeport, California, July 1995 through June 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 20. Graph showing elevation of streambed in relation to distance from river mouth, Keswick Dam to Freeport, Sacramento River, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 21. Probability box illustrations showing distribution of (A) Zn/Cd and (B) Zn/Cu data in dissolved and colloidal samples taken July 1996 through June 1997, Sacramento River, California . . . . . . . . . . . . . . . . . . . . 47 Appendix 5. Plots of metal loads in dissolved and colloidal forms for miscellaneous trace metals in water A5-1. Plot of dissolved and colloidal chromium loads, July 1996 to May–June 1997, Sacramento River, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 A5-2. Plot of dissolved and colloidal cobalt loads, July 1996 to May–June 1997, Sacramento River, California . . . . 99 A5-3. Plot of dissolved and colloidal nickel loads, July 1996 to May–June 1997, Sacramento River, California . . . . 100 A5-4. Plot of dissolved and colloidal yttrium loads, July 1996 to May–June 1997, Sacramento River, California . . . 101 Appendix 6. Hydrographs showing daily mean discharge and time of sampling A6-1. Hydrographs showing daily mean discharge and time of sampling, November 1996, Sacramento River, California for A. Below Keswick Dam, B. Bend Bridge, C. Colusa, D. Yolo Bypass, E. Verona, and F. Freeport. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 A6-2. Hydrographs showing daily mean discharge and time of sampling, December 1996, Sacramento River, California for A. Below Keswick Dam, B. Bend Bridge, C. Colusa, D. Yolo Bypass, E. Verona, and F. Freeport. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Contents vii A6-3. Hydrographs showing daily mean discharge and time of sampling, January 1997, Sacramento River, California for A. Below Keswick Dam, B. Bend Bridge, C. Colusa, D. Yolo Bypass, E. Verona, and F. Freeport. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 TABLES Appendix 1. Tables of Data Comparing Metal Loads in Dissolved Form, Colloidal Form, and Whole Water A1-1. Aluminum loads derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . 58 A1-2. Cadmium loads derived from concentrations in dissolved, colloid, and whole water samples. . . . . . . . . . 60 A1-3. Copper loads derived from concentrations in dissolved, colloid, and whole water samples. . . . . . . . . . . . 62 A1-4. Iron loads derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . . 64 A1-5. Lead loads derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . 66 A1-6. Mercury loads derived from concentrations in dissolved, colloid, and whole water samples. . . . . . . . . . . 68 A1-7. Zinc loads derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . . 70 Appendix 2. Tables of Data Comparing Metal Loads Relative to Loads at Freeport and in the Yolo Bypass A2-1. Aluminum loads divided by sum of loads at Freeport and in Yolo Bypass, derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 A2-2. Cadmium loads divided by sum of loads at Freeport and in Yolo Bypass, derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 A2-3. Copper loads divided by sum of loads at Freeport and in Yolo Bypass, derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 A2-4. Iron loads divided by sum of loads at Freeport and in Yolo Bypass, derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 A2-5. Lead loads divided by sum of loads at Freeport and in Yolo Bypass, derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 A2-6. Mercury loads divided by sum of loads at Freeport and in Yolo Bypass, derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 A2-7. Zinc loads divided by sum of loads at Freeport and in Yolo Bypass, derived from concentrations in dissolved, colloid, and whole water samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Appendix 3. Tables of Data Comparing Metal Loads Used in Mass Balance Calculations for the Spring Creek arm of Keswick Reservoir A3-1. Aluminum loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for the Spring Creek arm of Keswick Reservoir. . . . . . . . . . . . . . . . . . 82 A3-2. Cadmium loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for the Spring Creek arm of Keswick Reservoir. . . . . . . . . . . . . . . . . . 83 A3-3. Copper loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for the Spring Creek arm of Keswick Reservoir . . . . . . . . . . . . . . . . . . . . . . 84 A3-4. Iron loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for the Spring Creek arm of Keswick Reservoir . . . . . . . . . . . . . . . . . . . . . . 85 A3-5. Lead loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for the Spring Creek arm of Keswick Reservoir . . . . . . . . . . . . . . . . . . . . . . 86 A3-6. Mercury loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for the Spring Creek arm of Keswick Reservoir. . . . . . . . . . . . . . . . . . 87 A3-7. Zinc loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for the Spring Creek arm of Keswick Reservoir . . . . . . . . . . . . . . . . . . . . . . 88 viii Contents Appendix 4. Tables of Data Comparing Metal Loads Used in Mass Balance Calculations for Keswick Reservoir A4-1. Aluminum loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for Keswick Reservoir. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 A4-2. Cadmium loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations forKeswick Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 A4-3. Copper loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for Keswick Reservoir. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 A4-4. Iron loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for Keswick Reservoir. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 A4-5. Lead loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for Keswick Reservoir. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 A4-6. Mercury loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for Keswick Reservoir. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 A4-7. Zinc loads derived from concentrations in dissolved, colloid, and whole water samples used in mass balance calculations for Keswick Reservoir. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Contents ix