Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

October 2017

Alternative Formats Available

Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Prepared for: King County Department of Natural Resources and Parks Wastewater Treatment Division

Submitted by: Chris Magan, Timothy Clark, Kate Macneale, Martin Grassley, Bob Bernhard, and Dean Wilson King County Water and Land Resources Division Department of Natural Resources and Parks

Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Acknowledgements

The authors would like to thank for following people for their contributions to this report:  Dawn Duddleson (King County) for her help in completing the literature review.  The King County Water Quality and Quantity Group for their insights and guidance.  King County project team members: Judy Pickar (project manager), Dean Wilson (science lead), Bob Bernhard, Mark Buscher, Timothy Clark, Betsy Cooper, Wendy Eash‐Loucks, Elizabeth Gaskill, Martin Grassley, Erica Jacobs, Susan Kaufman‐Una, Deborah Lester, Kate Macneale, Chris Magan, Bruce Nairn, Sarah Ogier, Erika Peterson, John Phillips, Cathie Scott, Jim Simmonds, Jeff Stern, Dave White, Mary Wohleb, and Olivia Wright.  The project’s Science and Technical Review Team members—Virgil Adderley, Mike Brett, Jay Davis, Ken Schiff, and John Stark—for guidance and review of this report.

Citation

King County. 2017. Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary. Prepared by Chris Magan, Timothy Clark, Kate Macneale, Martin Grassley, Bob Bernhard, and Dean Wilson, Water and Land Resources Division. Seattle, Washington.

King County i October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table of Contents

1.1 King County Wastewater System ...... 1‐1 1.2 CSO Control Program ...... 1‐3 1.3 Water Quality Assessment and Monitoring Study ...... 1‐3 1.4 Scope and Content of this Report ...... 1‐6 Geographic Limits ...... 1‐6 Approaches to Data Analysis ...... 1‐6 Interpreting Box Plots...... 1‐8

2.1 Green‐Duwamish River Watershed ...... 2‐1 2.2 Characteristics ...... 2‐4 Historical and Current Configurations ...... 2‐4 Physical Characteristics of the Duwamish Estuary ...... 2‐5 Hydrology of the Duwamish Estuary ...... 2‐6 2.3 Historical and Current Uses ...... 2‐8 Commercial and Industrial Uses ...... 2‐8 Other Human Uses ...... 2‐9 Animals and Their Habitats ...... 2‐9 2.4 Contaminant Sources and Pathways ...... 2‐10 2.5 King County CSO Discharge Sites ...... 2‐14 Discharge Site Descriptions ...... 2‐14 Average Annual Discharge Frequencies and Volumes ...... 2‐16 2.6 Historical Contamination Cleanup Sites ...... 2‐17 Harbor Island ...... 2‐17 Lockheed West Seattle ...... 2‐20 Lower Duwamish Waterway ...... 2‐21 2.7 EPA‐Approved Listed Impairments ...... 2‐22

King County ii October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

3.1 Sampling Sites and Parameters ...... 3‐1 3.2 Sampling and Analysis Methodologies ...... 3‐4 3.3 Bacteria ...... 3‐5 Current Conditions ...... 3‐6 Comparison to Criteria ...... 3‐7 Long‐term Trends ...... 3‐10 Discussion ...... 3‐13 3.4 Physical Parameters ...... 3‐13 Temperature ...... 3‐13 Dissolved Oxygen ...... 3‐23 Salinity ...... 3‐31 Conductivity ...... 3‐35 pH ...... 3‐39 Alkalinity ...... 3‐44 Total Suspended Solids ...... 3‐45 Turbidity ...... 3‐48 3.5 Nutrients ...... 3‐51 Nitrogen ...... 3‐51 Phosphorus ...... 3‐60 3.6 Metals ...... 3‐65 Current Conditions ...... 3‐66 Comparison to Criteria ...... 3‐67 3.7 Organic Compounds...... 3‐70 Current Conditions ...... 3‐70 Comparison to Water Quality Criteria ...... 3‐72

4.1 Data Evaluated ...... 4‐1 4.2 Duwamish Estuary ...... 4‐2 Physical Structure ...... 4‐2 Sediment Chemistry ...... 4‐4 4.3 Green River Watershed ...... 4‐8 4.4 Sediment Toxicity ...... 4‐9

King County iii October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

4.5 Benthic Invertebrates ...... 4‐9

5.1 Data Sources and Limitations ...... 5‐1 5.2 Polychlorinated Biphenyls ...... 5‐2 5.3 Dioxin and Furans ...... 5‐4 5.4 Carcinogenic Polycyclic Aromatic Hydrocarbons ...... 5‐5 5.5 Arsenic ...... 5‐5 5.6 Tributyltin ...... 5‐6

6.1 Data Sources ...... 6‐1 6.2 Human Health Risk ...... 6‐1 6.3 Ecological Risk ...... 6‐3 Benthic Community ...... 6‐3 Fish and Wildlife Communities ...... 6‐4

7.1 Water Quality ...... 7‐1 7.2 Sediment Quality ...... 7‐2 7.3 Tissue Chemistry ...... 7‐3

King County iv October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figures

Figure 1‐1. King County’s wastewater service area and facilities...... 1‐2 Figure 1‐2. Reports and study questions answered as part of the Water Quality Assessment and Monitoring Study...... 1‐5 Figure 1‐3. Duwamish Estuary study area...... 1‐7 Figure 1‐4. Explanation of parts of a typical box plot...... 1‐8 Figure 2‐1. Green‐Duwamish River watershed...... 2‐2 Figure 2‐2. Green‐Duwamish area and study sections...... 2‐3 Figure 2‐3. Changes in land use and habitat in the Duwamish Estuary over time ...... 2‐5 Figure 2‐4. Levels of development in 2011 in land use areas surrounding the Duwamish Estuary study area...... 2‐7 Figure 2‐5. Turbulence created at toe (leading edge) of salt water moving upriver under tidal force...... 2‐8 Figure 2‐6. Conceptual site model for the Duwamish Estuary showing major sources, pathways, and fates of contamination...... 2‐11 Figure 2‐7. CSO and surface water outfalls in the Duwamish Estuary...... 2‐13 Figure 2‐8. Sediment cleanup and early action areas in the Duwamish Estuary...... 2‐19 Figure 3‐1. Long‐term monitoring sampling sites in the Green‐Duwamish area...... 3‐1 Figure 3‐2. Long‐term monitoring sites and CSO locations in the Duwmaish Estuary...... 3‐2 Figure 3‐3. Comparision of ranges of fecal coliform bacteria concentrations at sampling sites upstream and downstream of CSO locations in the Green‐Duwamish area (2004–2013)...... 3‐7 Figure 3‐4. Long‐term trends in the Green‐Duwamish area in fecal coliform bacteria as annual geometric means (1970−2013)...... 3‐11 Figure 3‐5. Comaprison of fecal coliform baceria concentrations in paired samples collected from the upper and lower depths at three sites in the Duwamish Estuary (2004–2013)...... 3‐12 Figure 3‐6. Ranges of annual surface water (0–1 m) temperatures at sites in the Duwamish Estuary and Green River (2009–2013)...... 3‐15 Figure 3‐7. Ranges of winter surface water (0–1 m) temperatures at sites in the Duwamish Estuary and Green River (2009–2013)...... 3‐15 Figure 3‐8. Ranges of summer surface water (0–1 m) temperatures at sites in the Duwamish Estuary and Green River (2009–2013)...... 3‐16 Figure 3‐9. Time‐depth isopleths of median monthly temperatures at site WW‐a in the West Waterway (2009–2013)...... 3‐17

King County v October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3‐10. Time‐depth isopleths of median monthly temperatures at site LDW‐3.3 in the Lower Duwamish Waterway (2009–2013)...... 3‐17 Figure 3‐11. Range of monthly surface water (0–1 m) temperatures at sites EW, WW‐a, LDW‐3.3, and LDW‐4.8 in the Duwamish Estuary (2009–2013)...... 3‐19 Figure 3‐12. Range of monthly temperatures at sites GR‐11.1 and GR‐11.6 in the Lower Green River (2009–2013)...... 3‐19 Figure 3‐13. Range of monthly temperatures at sites GR‐32.8, GR‐40.6, and GR‐42.0 in the Lower‐Middle Green River (2009–2013)...... 3‐20 Figure 3‐14. Range of monthly temperatures at site GR‐56.9 in the Middle‐Upper Green River (2009–2013)...... 3‐20 Figure 3‐15. Continuous 7‐DADMax temperature at site GR‐56.9 in the Upper‐Middle Green River (2009–2013)...... 3‐21 Figure 3‐16. Ranges of surface water (0–1 m) dissoved oxygen concentrations in the Duwamish Estuary and Green River (2009–2013)...... 3‐25 Figure 3‐17. Time‐depth isopleths of median dissoved oxygen concentrations at site WW‐a in the West Waterway (2009–2013)...... 3‐26 Figure 3‐18. Time‐depth isopleths of median dissoved oxygen concentrations at site LDW‐3.3 in the Lower Duwmaish Waterway (2009–2013)...... 3‐26 Figure 3‐19. Ranges of monthly dissolved oxygen concentrations at sites GR‐11.1 and GR‐11.6 in the Lower Green River (2009–2013)...... 3‐27 Figure 3‐20. Ranges of monthly dissolved oxygen concentrations at sites GR‐32.8, GR‐40.6, and GR‐42.0 in the Lower‐Middle Green River (2009–2013)...... 3‐27 Figure 3‐21. Ranges of monthly dissolved oxygen concentrations at site GR‐56.9 in the Upper‐Middle Green River (2009–2013)...... 3‐28 Figure 3‐22. Ranges of monthly dissolved oxygen concentrations at sites EW, WW‐a, LDW‐3.3, and LDW‐4.8 in the Duwamish Estuary (2009–2013)...... 3‐28 Figure 3‐23. Trends in median annual dissolved oxygen concentrations in the Green‐ Duwamish area (1975─2013)...... 3‐30 Figure 3‐24. Saltwater wedge variation between tides in the Duwamish Estuary...... 3‐32 Figure 3‐25. Saltwater wedge in the Duwamish Estuary during high freshwater inflow of 8,870 m3/min (5,200 cfs). (Source: Dawson and Tilley, 1972.) ...... 3‐32 Figure 3‐26. Ranges of surface water (0–1 m) salinity at sites in the Duwamish Estuary (2009–2013)...... 3‐34 Figure 3‐27. Time‐depth isopleths of median salinty for entire water column at site WW‐ a in the West Waterway (2011–2013)...... 3‐35 Figure 3‐28. Time‐depth isopleths of median salinty for entire water column at site LDW‐3.3 in the Lower Duwamish Waterway (2011–2013)...... 3‐35

King County vi October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3‐29. Ranges of surface water (0–1 m) conductivity at four sites in the Green River (2009–2013)...... 3‐36 Figure 3‐30. Ranges of monthly conductivity values at sites GR‐11.1 and GR‐11.6 in the Lower Green River (2009–2013)...... 3‐37 Figure 3‐31. Ranges of monthly conductivity values at site GR‐40.6 in the Lower‐Middle Green River (2009–2013)...... 3‐37 Figure 3‐32. Ranges of monthly conductivity values at site GR‐56.9 in the Upper‐ Middle Green River (2009–2013)...... 3‐38 Figure 3‐33. Ranges of annual surface water (0–1 m) pH at sites in the Duwamish Estuary and Green River (2009–2013)...... 3‐40 Figure 3‐34. Ranges of monthly pH in the Duwamish Estuary (2011–2012)...... 3‐41 Figure 3‐35. Ranges of monthly pH at Lower Green River sites GR‐11.1 and GR‐11.6 (2009–2013)...... 3‐42 Figure 3‐36. Ranges of monthly pH at Lower‐Middle Green River sites GR‐32.8, GR‐40.6, and GR‐42.0 (2009–2013)...... 3‐42 Figure 3‐37. Ranges of monthly pH at Upper‐Middle Green River site GR‐56.9 (2009–2013)...... 3‐43 Figure 3‐38. Ranges of monthly alkalinity at sites GR‐11.1 (grey) and GR‐40.6 (white) in the Lower and Middle‐Lower Green River (2009–2013)...... 3‐45 Figure 3‐39. Ranges of annual surface water (0–1m) total suspended solids concentrations in the Duwamish Estuary and Green River (2009–2013). .... 3‐47 Figure 3‐40. Ranges of monthly total suspended solids concentrations in the Duwamish Estuary and Green River (2009–2013)...... 3‐47 Figure 3‐41. Ranges of annual surface water (0–1m) turbidity values at four sites in the Green River (2009–2013)...... 3‐49 Figure 3‐42. Ranges of monthly turbidity values at four sites in the Green River (2009– 2013)...... 3‐50 Figure 3‐43. General nitrogen cycle for streams and riverine ecosystems...... 3‐52 Figure 3‐44. Ranges of median surface water (0–1 m) nitrate + nitrite‐N concentrations at sites in the Green‐Duwamish area (2007–2013)...... 3‐54 Figure 3‐45. Ranges of median surface water (0–1 m) ammonia concentrations at sites in the Green‐Duwamish area (2007–2013)...... 3‐56 Figure 3‐46. Ranges of median surface water (0–1 m) total nitrogen concentrations in the Duwamish and Green rivers (2007–2013)...... 3‐59 Figure 3‐47. Ranges of median surface water (0–1 m) orthophosphate concentrations at sites in the Green‐Duwamish area (2007–2013)...... 3‐62

King County vii October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3‐48. Ranges of median total phosphorus concentrations at sites in the Green‐ Duwamish area (2007–2013)...... 3‐64 Figure 4‐1. Exceedances of the Sediment Management Standards chemistry and toxicity criteria in Duwamish Estuary surface sediments (1991–2013)...... 4‐3 Figure 5‐1. Mean concentrations of PCB Aroclors by tissue type in fish tissue in the Lower Duwamish, West, and East waterways...... 5‐4

Tables

Table 1‐1. Elements of the Water Quality Assessment and Monitoring Study...... 1‐5 Table 2‐1. Species in the Duwamish Estuary listed under the Endangered Species Act or by the Washington State Department of Fish and Wildlife...... 2‐10 Table 2‐2. Average annual discharge frequencies and volumes of King County CSOs in the Duwamish Estuary (2009–2013)...... 2‐17 Table 2‐3. Water, Tissue, and Sedimnt Quality Impairments in the Duwamish Estuary, Duwamish River, and Green River (2012) ...... 2‐23 Table 3‐1. Long‐term ambient water quality monitoring sites in the Green‐Duwamish area...... 3‐3 Table 3‐2. Fecal coliform bacteria concentrations (CFU/100 mL) in the Green‐ Duwamish area (2004–2013)...... 3‐6 Table 3‐3. Water quality criteria for fecal coliform bacteria associated with each sampling site in the Green‐Duwamish area...... 3‐8 Table 3‐4. Comparision of fecal coliform bacteria concentrations to water quality criteria at sites in the Green‐Duwamish area (2004–2013)...... 3‐9 Table 3‐5. Spearman Rank Order correlations of fecal coliform bacteria concentrations in the Green‐Duwamish area and percipitation three days prior to sample collection...... 3‐10 Table 3‐6. Long‐term trends in fecal coliform bacteria concentrations in the Green‐ Duwamish area (1970–2013)...... 3‐11 Table 3‐7. Water temperatures (°C) in the Duwmaish Estuary and Green River (2009– 2013)...... 3‐14 Table 3‐8. Temperature and dissolved oxygen criteria for the Green‐Duwamish area. 3‐18 Table 3‐9. Exceedances of June 15–September 15 core rearing and migration temperature criterion (16 °C) at site GR‐56.9 in the Upper‐Middle Green River (2009–2013)...... 3‐22

King County viii October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3‐10. Exceedances of September 15–July 1 spawning and incubation temperature criterion (13°C) at site GR‐56.9 in the Upper‐Middle Green River (2009– 2013)...... 3‐22 Table 3‐11. Long‐term trends for temperature in the Green‐Duwamish area (1970– 2013)...... 3‐23 Table 3‐12. Concentrations of dissolved oxygen (mg/L) in the Duwamish Estuary and Green River (2009–2013)...... 3‐24 Table 3‐13. Long‐term trends for dissolved oxygen in the Green‐Duwamish area (1975–2013)...... 3‐30 Table 3‐14. Salinity values (ppt) in the Duwamish Estuary (2009–2013)...... 3‐33 Table 3‐15. Conductivity (µS/cm) values at four sites in the Green River (2009–2013). 3‐36 Table 3‐16. Long‐term conductivity trends in the Green‐Duwamish area (1975–2013). 3‐39 Table 3‐17. pH values in the Duwamish Estuary and Green River (2009–2013)...... 3‐39 Table 3‐18. Long‐term pH trends in the Green‐Duwamish area (1975–2013)...... 3‐44 Table 3‐19. Alkalinity (mg CaCO3/L) in the Lower and Middle‐Lower Green River (2009–2013)...... 3‐44 Table 3‐20. Long‐term alkalinity trends in the Green River (1997–2013)...... 3‐45 Table 3‐21. Total suspended solids (mg/L) in the Duwmaish Estuary and Green River (2009–2013)...... 3‐46 Table 3‐22. Long‐term total suspended solids trends in the Green‐Duwamish area (1976–2013)...... 3‐48 Table 3‐23. Turbidity values (NTUs) for four sites in the Green River (2009–2013)...... 3‐48 Table 3‐24. Long‐term turbidity trends for the Green‐Duwmaish area (1976–2013)...... 3‐50 Table 3‐25. Nitrite + nitrite‐N concentrations (mg/L) in the Green‐Duwamish area (2007–2013)...... 3‐53 Table 3‐26 Mann‐Whitney rank‐sum test of median nitrate + nitrite‐N concentrations between depths at three sample locations in the Duwamish Estuary...... 3‐53 Table 3‐27. Long‐term nitrate + nitrite‐N trends in the Green‐Duwamish area (1970– 2013)...... 3‐55 Table 3‐28. Ammonia concentrations (mg/L) in the Green‐Duwamish area (2007– 2013)...... 3‐55 Table 3‐29. Mann‐Whitney rank‐sum test for median ammonia concentrations between depths at three sample locations in the Duwamish Estuary (2007–2013). ... 3‐56 Table 3‐30. Freshwater and marine acute and chronic water quality criteria for ammonia (mg/L as nitrogen)...... 3‐57 Table 3‐31. Long‐term ammonia trends in the Green‐Duwamish area (1970–2013)...... 3‐57

King County ix October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3‐32. Total nitrogen concentrations (mg/L) in the Duwamish and Green rivers (2007–2013)...... 3‐58 Table 3‐33. Long‐term total nitrogen trends in the Duwamish and Green rivers (1993– 2013)...... 3‐59 Table 3‐34. Orthophosphate concentrations (mg/L) in the Green‐Duwamish area (2007–2013)...... 3‐61 Table 3‐35. Mann‐Whitney rank‐sum test of median concentrations of orthophosphate between depths at three locations in the Duwamish Estuary (2010–2013). 3‐61 Table 3‐36. Long‐term orthophosphate trends in the Green‐Duwamish area (1975– 2013)...... 3‐62 Table 3‐37. Total phosphorus concentrations (mg/L) in the Green‐Duwamish area (2007–2013)...... 3‐63 Table 3‐38. Mann‐Whitney rank‐sum test of median concentrations of total phosphorus between depths at three locations in the Duwamish Estuary (2007–2013). 3‐64 Table 3‐39. Long‐term total phosphorus trends in the Green‐Duwammish area (1970– 2013)...... 3‐65 Table 3‐40. Total metals and dissolved metals concentrations (μg/L) for all sites sampled in the Green‐Duwamish area (2000–2013)...... 3‐67 Table 3‐41. Detection frequency and maximum concentrations (µg/L) of metals inthe Duwamish Estuary compared to water quality criteria...... 3‐69 Table 3‐42. Detection frequency and maximum concentrations (µg/L unless otherwise noted) of organic compounds in the Duwamish Estuary and Green River compared to water quality criteria (2001–2012)...... 3‐74 Table 6‐1. Excess cancer risk and non‐cancer hazards in humans from consumption of seafood from the Lower Duwamish and East waterways...... 6‐2 Table 6‐2. Receptors of concern in the Lower Duwamish and East waterways...... 6‐4 Table 6‐3. Ecological risk drivers for receptors of concern in the Lower Duwamish and East waterways...... 6‐5

King County x October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

EXECUTIVE SUMMARY King County completed a study of the Duwamish Estuary. The study examined data previously collected from a variety of monitoring programs to characterize existing water quality and other indicators of the estuary’s environmental health, evaluate long‐term trends, describe potential pathways of pollution, and identify limitations in current data. Limited data on the Duwamish and Green rivers were included to the extent they inform conditions in the Duwamish Estuary.

The study was completed as part of a Water Quality Assessment and Monitoring Study, undertaken to explore ways to optimize water quality improvements in the three waterbodies where the County is planning combined sewer overflow (CSO) control projects—Elliott Bay, Lake Union/Ship Canal, and the Duwamish Estuary.

Background King County updates its CSO control plan about every five years. Before each update, the County reviews its entire CSO Control Program against conditions that have changed since the last update. In September 2012, the King County Council passed Ordinance 17413 approving an amendment to the long‐term CSO control plan. The plan includes nine projects to control the County’s remaining 14 uncontrolled CSOs by 2030 to meet the Washington State standard of no more than one CSO event per year on a 20‐year moving average. The recommended projects involve construction of underground storage tanks, green stormwater infrastructure, wet weather treatment facilities, or a combination of approaches.

Ordinance 17413 also calls for completion of a Water Quality Assessment and Monitoring Study (referred to as the assessment) to inform the next plan update due to the Washington State Department of Ecology (Ecology) in 2019. As a part of the assessment, this study of the Duwamish Estuary compiles existing information on water quality to address one of the assessment’s study questions: “What are the existing and projected water quality impairments in receiving waters (waterbodies) where King County CSOs discharge?” Similar studies are being completed for Elliott Bay and Lake Union/Ship Canal. The final product of the assessment will be a synthesis report that summarizes the results of these studies and of other studies conducted to improve understanding of existing conditions and analyze pollutant loadings to the three waterbodies.

Study Area The Duwamish Estuary study area comprises the lowest 6.4 miles of the Green‐Duwamish River watershed. The 484‐square‐mile watershed extends from the crest of the Cascade Mountains at the headwaters of the Green River and west through the Duwamish River to where the Duwamish Estuary empties into Puget Sound’s Elliott Bay in Seattle.

The study area is located in the City of Seattle, City of Tukwila, and a small area of unincorporated King County. It is divided into three sections: East Waterway, West

King County xi October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Waterway, and Lower Duwamish Waterway (Figure ES‐1). The East and West waterways border two sides of Harbor Island. In its modern configuration, the estuary is a highly engineered remnant of the original mouth of the Duwamish River. Maintained as a federal navigation channel, the waterways support considerable commercial navigation and remain one of the City of Seattle’s primary industrial zones. Two city neighborhoods are located along the Lower Duwamish Waterway. Both neighborhoods include a mixture of residential, recreational, commercial, and industrial land uses.

Although the Duwamish Estuary is mostly devoid of natural habitat, some shallow intertidal benches remain in the nearshore, intertidal, and shallow subtidal zones outside the navigation channel. Intertidal habitats are dispersed in relatively small patches—with the exception of Kellogg Island, which represents the largest contiguous area of intertidal habitat in the estuary. The lowlands are dominated by urban and suburban areas, crossed by roads, and fragmented into patches of residential, commercial, and industrial areas.

Many species of invertebrates, reptiles, fish, birds, and mammals are still found in the Duwamish Estuary. Some populations are resident (shellfish, benthic invertebrates, fish), while others use the waterways periodically (seasonal migration, daily foraging, breeding, or juvenile rearing). Seventeen species have been identified that are listed with federal or state protection status.

Sources and Pathways of Contamination Humans, threatened and endangered species, and other species that use the waters of the Duwamish Estuary remain at risk from historical and ongoing sources of contamination. Common sources and pathways of pollution from the past, such as mining, logging, shipping, untreated sewage, industrial wastes, pesticides, and fertilizers, continue to be a concern. Ongoing sources and pathways include atmospheric deposition, nutrient runoff from agricultural lands, food additives and drugs, stormwater, and CSOs. The estuary has been subjected to years of these types of discharges, as evidenced by accumulations of contaminants in its sediments. Several Superfund sediment cleanup projects have been or will be completed in the area.

The majority of the land surrounding the Duwamish Estuary is served by either combined or partially separated sewer systems (Figure ES‐2). In partially separated systems, rooftop gutters drain to the sanitary sewer and street runoff flows to storm drains that discharge directly to the estuary. In combined systems, pipes carry both wastewater and stormwater. Most of the combined flows are treated before being discharged to Puget Sound. During heavy rain when volumes exceed the capacity of the combined sewers and treatment plants, excess flow discharges directly into the estuary as CSOs.

Seventeen CSO outfalls discharge to the Duwamish Estuary (Figure ES‐2). King County operates five controlled and nine uncontrolled CSO outfalls. (One of the nine uncontrolled CSOs, the Harbor Ave CSO, is nearly controlled.) The City of Seattle operates three uncontrolled CSO outfalls. Numerous city‐owned and private surface water outfalls discharge to the estuary. The principal pollutants in surface water and CSO discharges

King County xii October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary include pathogens, organic matter that depleted oxygen when it decays, suspended solids, toxics, and nutrients.

King County xiii October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure ES-1. Duwamish Estuary study area.

King County xiv October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure ES-2. Locations of CSO and surface water outfalls in the Duwamish Estuary.

King County xv October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Findings General findings of current water, sediment, and fish/shellfish tissue quality and on long‐ term water quality trends in the Duwamish Estuary are as follows:  Water quality concerns in the Duwamish Estuary include high bacteria concentrations and high temperatures in some surface waters in the summer. Dissolved oxygen levels have increased over time, with some potential issues in the Lower Green River. No samples exceeded the aquatic life water quality criteria for metals and semivolatile organic compounds. Polychlorinated biphenyl (PCB) congeners were the only compounds that exceeded the U.S. Environmental Protection Agency (EPA) Ambient Water Quality Criteria for the protection of Human Health. There is insufficient data on the seasonal and spatial variability of these compounds in the study area to fully evaluate their impact on water quality.  Sediments in the Duwamish Estuary are contaminated as the result of historical and current industrial, commercial, public, and private activities. In the Duwamish Estuary, the EPA designated Superfund cleanup sites at Harbor Island, Lockheed West, and the Lower Duwamish Waterway.  Most contaminants commonly identified in water and sediments of the Duwamish Estuary are also found in resident fish and shellfish tissue. Because of elevated contaminants found in fish and shellfish tissue from the Lower Duwamish and East waterways, the Washington State Department of Health has issued fish consumption advisories for the Duwamish Estuary. Monitoring of fish and shellfish tissue will occur as part of the Superfund cleanup process for these waterways. The following sections provide more detail on these findings.

Water Quality Current water quality conditions were evaluated using the most recent monthly and bi‐ monthly data from King County and Ecology long‐term monitoring programs. When more than 20 years of data were available, trends were evaluated. The analysis was based on data from discrete samples. Little or no continuous data were available. Upstream data collected from the Duwamish and Green rivers as far as the Howard A. Hanson Dam about 64 miles upstream of the mouth of the system were included to the extent they inform conditions in the Duwamish Estuary. The entire area, including the estuary, is called the Green‐Duwamish area.

Major findings are as follows:  Bacteria. Elevated bacteria concentrations (as measured by fecal coliform bacteria) are a persistent water quality concern in the Green‐Duwamish area. Concentrations were typically highest in the Lower Duwamish Waterway and decreased moving upstream. Frequent exceedances of water quality criteria upstream and downstream of CSOs have occurred. Despite exceedances, it appears that bacteria concentrations have declined in the last 20 to 30 years. CSO control and improved stormwater management may have contributed to this decline. Additional

King County xvi October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

mitigation of bacteria sources and pathways is needed to further enhance water quality and protect human health.  Temperature. The analysis indicates that the lower and middle sections of the Green River are more likely to exceed temperature standards for salmonids than downstream and upstream locations. The Duwamish Estuary remains relatively cool because of the influence of Puget Sound, and reaches of the Green River farther upstream are cooler because land cover is predominantly forest. Analysis showed significant increasing long‐term temperature trends in the West Waterway.  Dissolved oxygen. Generally, dissolved oxygen concentrations have increased in the Duwamish Estuary and the lower Green River in the last 40 years, yet these reaches are more likely to violate the dissolved oxygen standards for salmonids than upstream reaches of the Green River. No significant trends were observed for upstream sites in the Green River.  Nutrients. Nutrient concentrations in the Duwamish Estuary are affected by inputs from CSOs, stormwater, upstream locations, and internal cycling (nutrients becoming attached to sediments and then being released from sediments during annual seasonal cycles). Trend analysis found that phosphorus, nitrogen, and ammonia concentrations have generally decreased or remained stable in the last 20 to 30 years, indicating that loading has decreased or stayed the same. For ammonia, orthophosphate, and total phosphorus, greater rates of decrease in the Duwamish Estuary suggest less importance of internal cycling.  Metals. Overall, ambient water in the Green‐Duwamish area did not exceed the Washington State water quality criteria for aquatic life or EPA’s recommended Human Health Criteria for metals. Total metals concentrations varied. The metals with the highest detection frequencies were aluminum, arsenic, barium, calcium, copper, magnesium, manganese, nickel, sodium, vanadium, and zinc. Dissolved metals were detected at a lower frequency than total metals. Metal concentrations in the Duwamish Estuary are affected by inputs from stormwater, upstream locations, leaching from antifouling vessel paint, and to a lesser extent, from CSO discharges.  Organic compounds. No organophosphorus pesticides were detected. One chlorinated herbicide (triclopyr) was detected in a single sample. Polycyclic aromatic hydrocarbons (PAHs) were detected frequently. Various other organic compounds were detected infrequently. PCB congeners were detected from all samples taken. Total PCB concentrations measured by congener analysis exceeded the Human Health Criteria in 66 of 72 samples. Two samples exceeded the Human Health Criteria for bis(2‐ethylhexyl)phthalate: one collected in the East Waterway and one collected at the downstream end of the Lower Duwamish Waterway. Most of the older samples typically had detection limits above many of the chronic water quality criteria for the protection of aquatic life or the recommend Human Health Criteria and had higher frequencies of blank contamination. Organic chemicals in the Duwamish Estuary water column are primarily affected by stormwater, upstream locations, internal cycling from sediments, leaching from creosote‐treated pilings, and to a lesser extent, from CSO discharges.

King County xvii October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Sediment Quality Localized areas in the Lower Duwamish and East waterways exceeded the marine benthic sediment standards for metals (arsenic, copper, lead, and zinc), PAHs, and phthalates (bis[2‐ethylhexyl] phthalate and butyl benzyl phthalate). Most exceedances occurred within 50 m of the shoreline. Phthalates, in particular bis(2‐ethylhexyl) phthalate, also exceeded standards near the Duwamish/Diagonal early action cleanup area, just upstream and downstream of Slip 27 in the East Waterway and between river mile (RM) 4.8 and RM 5.0 in the Lower Duwamish Waterway. Another organic chemical, 1,4‐dichlorobenzene, was detected in numerous samples in the East Waterway and exceeded standards just upstream of Slip 27.

Mercury and total PCBs exceeded the marine benthic sediment standards throughout the Lower Duwamish and East waterways. The East Waterway had a higher frequency of mercury exceedances than the Lower Duwamish Waterway. Even though the production of PCBs has been banned in the United States since 1979, the wide use of PCBs or PCB‐ containing products in the past has caused much contamination in the two waterways.

Tissue Quality Major findings in regard to tissue quality are as follows:  In the Lower Duwamish and East waterways, PCBs, PAHs, and metals were the most frequently measured contaminants in tissue. PAHs were highest in clams, mussels, and benthic invertebrates from numerous locations. Total arsenic was detected in all tissue samples; inorganic arsenic concentrations were highest in clams. Total PCB concentrations were highest in Dungeness crab hepatopancreas, English sole, and shiner surfperch; low concentrations were found in clams and mussels. The West Waterway had the lowest total PCB concentrations of all locations sampled.  Most other organic chemicals were infrequently detected in tissue from the Lower Duwamish and East waterways. In the East Waterway, concentrations of dioxins and furans were higher in fish and crab hepatopancreas and lower in crab muscle, clams, and geoducks. Dioxins and furans were not sampled in Lower Duwamish Waterway locations.

Other Assessment Reports This report is one of several reports that have been prepared as part of King County’s Water Quality Assessment and Monitoring Study. Other reports are as follows:  Two reports describe existing conditions and long‐term trends in two other study areas—Lake Union/Ship Canal and Elliott Bay.  A report documents the process used to assess identified data gaps for the study areas and select studies to fill prioritized gaps.  Three reports discuss the methodology and results of selected new studies to improve understanding of existing conditions: a study of bacteria in wet and dry

King County xviii October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

weather, a survey of contaminants of emerging concern, and a literature review of potential conservative sewage tracers.  A loadings report discusses present‐day contributions of pollutants from various pathways, including stormwater runoff and CSOs, into the study areas.  A future loadings report assesses the potential of planned actions such as CSO control to improve water quality.  A final report summarizes these analyses and implications. King County will use the information from the Water Quality Assessment and Monitoring Study to inform the next CSO control plan update, including looking for opportunities to improve water quality outcomes, possibly reduce costs of CSO control projects, establish baseline conditions for post‐construction monitoring of CSO control projects, and decide whether to pursue an integrated CSO control plan. The information from the assessment can also be used to inform regional efforts to continue to improve water and sediment quality.

King County xix October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

ACRONYMS AND ABBREVIATIONS ANC acid neutralizing capacity ATP adenosine triphosphate CEC chemical of emerging concern CFU colony forming unit COC contaminant of concern COPC contaminant of potential concern cPAH carcinogenic polycyclic aromatic hydrocarbon CSL Cleanup Screening Level CSO combined sewer overflow CTD conductivity‐temperature‐dissolved oxygen DIN dissolved inorganic nitrogen DO dissolved oxygen DON dissolved inorganic nitrogen EAA early action area EDC endocrine disrupting compound EPA Environmental Protection Agency ERA ecological risk assessment EW East Waterway FOD frequency of detection FS feasibility study HHRA human health risk assessment HPAH high molecular weight polycyclic aromatic hydrocarbon HQ hazard quotient ICP‐MS Inductively Coupled Plasma Mass Spectrometry KCEL King County Environmental Laboratory KCIA King County International Airport LAET lowest apparent effects threshold LDW Lower Duwamish Waterway LPAH low molecular weight polycyclic aromatic hydrocarbon MDL method detection limit MLLW mean lower low water MTCA Model Toxics Control Act NPL National Priorities List NTU nephelometric turbidity units OU operable unit PAH polycyclic aromatic hydrocarbon PBDE polybrominated diphenyl ether

King County xx October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

PCB polychlorinated biphenyl PPCP pharmaceuticals and personal care products PSU practical salinity unit RD risk driver RI remedial investigation RM river mile RME reasonable maximum exposure ROD record of decision SCAP source control action plan SCO Sediment Cleanup Objective SMS Sediment Management Standards SQS Sediment Quality Standard SVOC semivolatile organic compound TBT tributyltin TEF toxic equivalency factor TEQ toxic equivalent TMDL total maximum daily load TOC total organic carbon TSS total suspended solids USACE U.S. Army Corps of Engineers VOC volatile organic compound WRIA water resource inventory area WTD King County Wastewater Treatment Division ww wet weight

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King County xxii October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

1.0 INTRODUCTION This report summarizes existing information on water quality and other indicators of the environmental conditions in the Duwamish Estuary in Seattle. The report was prepared as part of King County’s Water Quality Assessment and Monitoring Study. The study was undertaken to explore ways to optimize water quality improvements in waterbodies where the County is planning combined sewer overflow control projects.

The following sections describe King County’s wastewater system, its Combined Sewer Overflow Control Program, the Water Quality Assessment and Monitoring Study, and the scope and content of this report. 1.1 King County Wastewater System King County owns and operates a regional wastewater system that serves 1.7 million people in a 420‐square‐mile area in Washington state (Figure 1‐1). The area covers most of urban King County including Seattle, south Snohomish County, and a small portion of Pierce County.

The wastewater system is the largest in the Puget Sound region. It includes over 350 miles of pipelines that collect wastewater from 34 local sewer utilities. The pipelines carry the wastewater to three regional treatment plants—West Point Treatment Plant in the City of Seattle, South Treatment Plant in the City of Renton, and Brightwater Treatment Plant in south Snohomish County—that treat and disinfect the wastewater before discharging it to Puget Sound. The County also owns two local treatment plants in the City of Carnation and on Vashon Island.

Up through the early 20th century, most cities constructed combined sewers to collect both wastewater and stormwater in the same pipes. The combined sewers carried untreated wastewater directly to waterbodies. Today, combined flows are sent to treatment plants for treatment before being discharged to waterbodies. Untreated overflows occur only at designated locations during heavy storms when flows exceed the capacity of sewers and treatment plants. These combined sewer overflows (CSOs) serve as constructed relief points to prevent sewer backups into homes and streets.

In King County’s regional wastewater system, combined sewers are located in Seattle only. Figure 1‐1 shows the combined sewer area. Portions of this area contain separated and partially separated sewers. King County owns and operates 39, and the City of Seattle 87 CSO locations in the city limits. The outfall pipes at these locations discharge wastewater diluted with stormwater to Puget Sound, the Duwamish Estuary, Lake Union/Ship Canal, and Lake Washington during large storms. On average over the long term, about 350 CSOs occur from King County locations each year. Average annual volumes at these locations can be as low as zero at one location to over 200 million gallons at another; the total average annual volume discharged from all county locations is about 800 million gallons.

King County 1‐1 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 1-1. King County’s wastewater service area and facilities.

King County 1‐2 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

1.2 CSO Control Program CSO control is required by Washington state and federal law. “Control” means reducing the number of untreated overflows from each location to once per year on a 20‐year moving average. Controlling CSOs protects public health and the environment. CSO discharges contain harmful disease‐causing organisms and a large number of chemicals.

Since the regional wastewater system began operating in the 1960s, the County and City have reduced the volume of untreated wastewater discharges by around 28 billion gallons a year. King County alone has invested $389 million to reduce its CSO volumes from 2.3 billion gallons in the 1980s to about 1 billion gallons today. It is investing another $117 million on projects that are under way. Only 14 of the County’s and about half of the City’s locations still require control. The County’s uncontrolled sites are located in the Duwamish Estuary, Elliott Bay, and Lake Union/Ship Canal.

King County updates its CSO control plan about every five years. Before each update, the County’s Wastewater Treatment Division (WTD) reviews its entire CSO Control Program against conditions that have changed since the last update—conditions such as population and flow, scientific developments, regulations, new technologies, and public priorities. The latest CSO Control Program review and plan update were completed in 2012. As a result, the King County Council approved an amendment in September 2012 to the County’s long‐term CSO control plan through Ordinance 17413. The U.S. Environmental Protection Agency (EPA) also approved the plan in 2013, and the plan is incorporated into the consent decree that the County entered into with the U.S. Department of Justice, EPA, and Washington State Department of Ecology (Ecology) in 2013.

The CSO control plan includes nine projects to control the remaining 14 uncontrolled CSOs by 2030. The recommended projects involve construction of underground storage tanks, green stormwater infrastructure, and/or wet weather treatment facilities. Four projects are in the Lake Union/Ship Canal area and five in the Duwamish Estuary and Elliott Bay areas. Ordinance 17413, approving the plan, also calls for completion of a Water Quality Assessment and Monitoring Study to inform the next plan update, which is due to regulators in 2018. In September 2013, the County Council approved the assessment’s scope of work through Motion 13966.

1.3 Water Quality Assessment and Monitoring Study

Work began in 2013 on the Water Quality Assessment and Monitoring Study. The objective of the assessment is to help ensure that investments in CSO control optimize water quality improvements in CSO subbasins. It includes a scientific and technical analysis of existing water quality of the receiving waters where uncontrolled county CSOs discharge (Elliott Bay, Lake Union/Ship Canal, and the Duwamish Estuary), identification of water quality impairments, trends in water quality, assessment of sources contributing to impairments, and review of ongoing and planned activities to improve water quality. WTD will use the

King County 1‐3 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

information to inform the 2018 CSO control plan update, prioritize and sequence CSO control projects, establish baseline conditions for post‐construction monitoring of CSO control projects, and decide whether to pursue an integrated plan based on EPA guidelines.

An integrated planning process has the potential to identify efficiencies in implementing competing requirements that arise from separate wastewater and stormwater projects, including capital investments and operation and maintenance requirements. This approach can build partnerships among agencies and jurisdictions and can lead to more sustainable and comprehensive solutions, such as green stormwater infrastructure, that improve water quality and support other attributes that enhance the vitality of communities.

The Water Quality Assessment and Monitoring Study set out to generate information that will help answer the following study questions: 1. What are the existing and projected water quality impairments in receiving waters (waterbodies) where King County CSOs discharge?1 2. How do county CSOs contribute to the identified impairments? 3. How do other sources contribute to the identified impairments? 4. What activities are planned through 2030 that could affect water quality in the receiving waters? 5. How can CSO control projects and other planned or potential corrective actions be most effective in addressing the impairments? 6. How do various alternative sequences of CSO control projects integrated with other corrective actions compare in terms of cost, schedule, and effectiveness in addressing impairments? 7. What other possible actions, such as coordinating projects with the City of Seattle and altering the design of planned CSO control projects, could make CSO control projects more effective and/or help reduce the costs to WTD and the region of completing all CSO control projects by 2030? An external Scientific and Technical Review Team has been assembled to review the methodology and results of the assessment. Depending on assessment findings, the King County Council may decide to approve formation of an Executive's Advisory Panel of approximately 10 regional leaders. The panel would develop independent recommendations to the King County Executive on how planned county CSO control projects can best be sequenced and integrated with other projects in order to maximize water quality gains and minimize costs to ratepayers.

Table 1‐1 shows elements of the assessment and their associated study questions, deliverables, and estimated timeframes. As shown in the table, 10 studies and reports address Study Questions 1−4; the CSO Control Program will use the information in the

1 The federal Clean Water Act, adopted in 1972, requires that all states restore their waters to be “fishable and swimmable.” Washington's Water Quality Assessment lists the water quality status for waterbodies in the state (http://www.ecy.wa.gov/programs/wq/303d/index.html).

King County 1‐4 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary reports to address Study Questions 5−7 (Figure 1‐2). More information on the assessment is available at http://www.kingcounty.gov/environment/wastewater/CSO/WQstudy.aspx.

Table 1-1. Elements of the Water Quality Assessment and Monitoring Study. Element Applicable Deliverable Timeframe Study Question Review and analyze existing scientific and 1 Area reports: 2013–2017 technical data on impairments in Lake  Elliott Bay Union/Ship Canal, Duwamish Estuary, and  Lake Union/Ship Elliott Bay. Canal  Duwamish Estuary Conduct targeted data gathering and 2,3 Data gap study selection 2014–2017 monitoring to fill some of the identified gaps in report scientific data on water quality in these receiving waters. Data gap study reports:  Bacteria  Contaminants of emerging concern  Literature review of conservative sewage tracers Identify and quantify current (2015) pathways 2,3 Loadings Report 2015–2017 of contaminants into the receiving waters. Identify changes in contaminant loadings 1,2,3,4 Future Loadings Report 2015–2017 between 2015 and 2030, including the potential impact of planned corrective actions on identified impairments in the waterbodies. Summarize scientific and technical data 1,2,3,4 Synthesis Report 2015–2017 collected and reviewed during the assessment.

Report on process Study Questions 1- 4: How county to select Study • Three CSOs and other additional studies Questions 1-4: reports on sources contribute • CSO • Reports on three existing to impairments, Control new studies: data: and planned Program • Lake corrective activities • Bacteria Sources • Synthesis review Union/Ship • Contaminants of Report process Canal Emerging • Summary • Elliott Bay • Loadings Concern and Study • Duwamish Reports • Method to Trace Analysis Questions 5-7: Estuary Sewage Effective CSO sequences Study Question 1: Study Questions 2-3: Existing How county CSOs impairments and other sources contribute to impairments

Figure 1-2. Reports and study questions answered as part of the Water Quality Assessment and Monitoring Study.

King County 1‐5 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

1.4 Scope and Content of this Report

This “area” report documents existing information on water quality in the Duwamish Estuary. It answers one of the assessment’s study questions: “What are the existing and projected water quality impairments in receiving waters (waterbodies) where King County CSOs discharge?” Similar reports are being produced for Elliott Bay and Lake Union/Ship Canal.

Geographic Limits The study area includes Harbor Island, the East and West waterways adjacent to Harbor Island, and the upstream Lower Duwamish Waterway. Together, these areas are referred to as the Duwamish Estuary (Figure 1‐3). The estuary includes all surface waters associated with the 14 CSOs operated by King County south of Elliott Bay and is part of the Green‐Duwamish River watershed that includes the Duwamish and Green rivers upstream. Limited data on the Duwamish and Green rivers are also included to the extent they inform conditions in the Duwamish Estuary.

Approaches to Data Analysis King County and other entities have collected data on water quality, sediment chemistry, and fish, shellfish, and invertebrate tissue chemistry in the Green‐Duwamish River watershed. These data were evaluated and summarized as a part of this assessment in order to describe recent conditions, identify long‐term trends, and review exceedances of Washington State water quality standards for the protection of aquatic life and EPA’s Human Health Criteria. Data include physical parameters of the water column (temperature, dissolved oxygen, salinity, conductivity, pH, alkalinity, turbidity and total suspended solids), nutrients (phosphorus and nitrogen), fecal coliform bacteria, metals, and various groups of organic compounds. Data on metals and organic compounds in sediments and fish/shellfish tissue were also analyzed as part of Superfund studies in the estuary and are summarized in this report.2

Current conditions for water quality were assessed using the most recent data for each parameter to capture inter‐annual variability while avoiding data that may not reflect the current state. Long‐term trend analyses were conducted over different timeframes because of changes in the location of sites monitored and lack of sufficient data at some sites to confidently detect trends. As a rule, sites with more than 20 years of data were used for evaluating long‐term trends.

2 Superfund is the name given to the federal environmental program established to address hazardous waste sites. It is also the name of the fund established by the Comprehensive Environmental Response, Compensation and Liability Act of 1980, as amended.

King County 1‐6 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 1-3. Duwamish Estuary study area.

King County 1‐7 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

To account for inconsistencies in the data, media‐ or parameter‐specific considerations are discussed and data collection dates are given prior to presentation of results. Some parameters have been consistently monitored over the years as part of the County’s routine monitoring program. Other parameters were monitored as part of short‐term projects with different sample collection techniques, analytical methods, and overall data quality. Detection limits for parameters may vary substantially based on changes in analytical techniques and instrumentation between sampling events. In addition, the number of samples analyzed may vary for each study and parameter.

Interpreting Box Plots Much of the data in this report are displayed in box plots, which show the spread of data for a parameter and differences at various locations. Figure 1‐3 describes each part of a typical plot. Letters above the boxes denote the statistical differences between sites; sites sharing the same letter are not statistically distinguishable at the alpha = 0.05 level of significance. Sites that do not share a letter are significantly different at the alpha = 0.05 level of significance.

7

Samples with the same letter are not significantly different 6 from one another at alpha = 0.05 BC C 95th Percentile BC 5 90th Percentile AB 75th Percentile A 4 Median

3 25th Percentile

2 10th Percentile 5th Percentile Concentration of Parameter (units) of Parameter Concentration

1 Samples with different letters are significantly different from one another at alpha = 0.05 0

Site 1 Site 2 Site 3 Site 4 Site 5 Site Figure 1-4. Explanation of parts of a typical box plot.

King County 1‐8 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

2.0 STUDY AREA The Duwamish Estuary study area encompasses the lowest 6.4 miles of the Green‐ Duwamish River watershed. The area is located in the City of Seattle, City of Tukwila, and a small area of unincorporated King County. It includes all of Harbor Island (an approximately 0.62‐square‐mile manmade industrial area) that fronts Elliott Bay, the East and West waterways of the Duwamish Estuary that bound Harbor Island, and the Lower Duwamish Waterway that includes 5 miles of cut channel upstream of the southern tip of Harbor Island.

This chapter describes the Green‐Duwamish River watershed and portions of the watershed included in this analysis. It then describes historical and current uses, contaminant sources and pathways, King County CSO locations, and historical contamination cleanup areas of the study area.

2.1 Green-Duwamish River Watershed

The Green‐Duwamish River watershed (Water Resource Inventory Area 9) includes 484 square miles of Puget Lowland and Cascade ecoregions (Ecology, 1995; King County, 2002) entirely located in King County (Figure 2‐1). The watershed extends from the crest of the Cascade Mountains at the headwaters of the Green River west to the mouth of the Duwamish Estuary where the East and West Waterways empty into Elliott Bay and then Puget Sound. The average annual precipitation in the watershed is 59 inches per year (Ecology, 1995).

Although this report focuses on the Duwamish Estuary (East, West, and Lower Duwamish waterways), data from the Green and Duwamish rivers are included to provide information on the various contaminant inputs into the Estuary. This “Green‐Duwamish area” is 264 square miles, extending from the Howard Hanson Dam to the East and West waterways as they empty into Elliott Bay. Land uses range from forested/undeveloped areas in the upstream portions near the Green River to high‐intensity developed areas near the Duwamish Estuary. The area includes six major cities—Seattle, Renton, Kent, Auburn, Tukwila, and Enumclaw—and four large tributary streams to the Green River—Soos, Newaukum, Mill (Hill), and Springbrook creeks. The Upper Green River above Howard A. Hanson Dam (220 square miles) is not included in this analysis.

Identification of river miles in this report conforms to the convention used in the remedial investigation/feasibility study prepared for the Lower Duwamish Waterway Superfund site (Windward, 2010). This convention designates the southern tip of Harbor Island as river mile (RM) 0 even though this location is about 1.6 miles upriver of Elliott Bay. Thus, the Duwamish Estuary, starting at the northern tip of Harbor Island, is 6.4 miles long but ends at RM 4.8.

King County 2‐1 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 2-1. Green-Duwamish River watershed.

King County 2‐2 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

The referenced areas in this report are shown in Figure 2‐2 and described below:  Green‐Duwamish area. Extends from the mouth of the system at Elliott Bay (northern tip of Harbor Island) to RM 63.1 and includes three subareas: Duwamish Estuary, Duwamish River, and Green River up to Howard A. Hanson Dam.  Duwamish Estuary (study area). Extends from the mouth of the system to RM 4.8 and includes the East Waterway, West Waterway, and Lower Duwamish Waterway up to the South 102nd Street Bridge (150 m above the Norfolk CSO).  Duwamish River. Extends from RM 4.8 just above the Upper Turning Basin (South 102nd Street Bridge) to RM 9.8 at the confluence of the Green and Black rivers.  Green River. Extends from RM 9.8 at the confluence of the Green and Black rivers to RM 63.1 near the Howard A. Hanson Dam. It is divided into three subareas: o Lower Green River from RM 9.8 to RM 22.8 o Lower‐Middle Green River from RM 22.8 to RM 42.0 o Upper‐Middle Green River from RM 42.0 to RM 63.1

Figure 2-2. Green-Duwamish area and study sections.

King County 2‐3 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

2.2 Characteristics

This section describes the historical and current configurations of the Green‐Duwamish area and the physical characteristics and hydrology of the Duwamish Estuary.

Historical and Current Configurations Before 1906, the Duwamish River received flow from a diverse system of lakes, rivers, streams, floodplains, wetlands, and tidal marshes that were subject to frequent flooding. The river was the primary receiving waterbody for flows exiting Lake Washington through the Black River. The Cedar River, White River (including flows from the Emmons Glacier on the northeast slope of Mount Rainer), and Green River were also tributary to the Duwamish River. These drainages totaled approximately 1,640 square miles (Blomberg et al., 1988).

A series of alterations associated with urbanization early in the 20th century greatly reduced the flow of water moving through the Duwamish Estuary. The changes, described below, reduced the drainage area of the Duwamish River by approximately 70 percent (Kerwin and Nelson, 2000).  In 1906, the White River, which flowed to the Green River, was diverted to the Stuck River and on to Commencement Bay in Tacoma to control flooding (Harper‐Owes, 1983).  In 1911, the Cedar River, which flowed directly into the Black River, was diverted into Lake Washington. Lake Washington and the Cedar River continued to drain to the Black River (and the Duwamish River) for another five years.  In 1917, the opening of the Lake Washington Ship Canal drained Lake Washington and the Cedar River to Puget Sound at Shilshole Bay, lowered the lake level by more than 2 m, and dramatically reduced Black River flow volumes.

Other important changes that occurred in the early 20th century included the elimination of natural meanders of the lower portion of the Duwamish River by dredging a straight channel in 1903–1905 to improve navigation and using the dredged material to create Harbor Island at the mouth of the estuary (Weston, 1993). By 1916, the modern shape of the dredged channel (to just above the Upper Turning Basin at RM 5.0) was established. Elsewhere in the estuary, streams were diverted and wetlands drained to facilitate the development of roads, residential lots, and commercial properties.

By the middle of the 20th century, periodic flooding and wetlands in the lowlands of the watershed were viewed as impedances to continued urbanization and economic development. Support for levee programs, wetlands development, and dams were driven by population growth, agriculture, and an accommodating regulatory framework. In 1961, the U.S. Army Corps of Engineers constructed the Howard A. Hanson Dam to decrease peak river flows and enhance summer water quality for fish. Prior to dam construction, large flood events of 15,000 cfs to 30,000 cfs were common; after construction, flows rarely have exceeded 12,000 cfs.

King County 2‐4 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Changes to surface waterways and flow dynamics are most noticeable in the Duwamish Estuary. These changes represent the transformation of unaltered native habitat into a highly engineered canal that is managed to serve the needs of high‐density industrial and urban activity (Figure 2‐3).

Figure 2-3. Changes in land use and habitat in the Duwamish Estuary over time (Source: King County, 1999).

Physical Characteristics of the Duwamish Estuary In its modern configuration, the Duwamish Estuary is a highly engineered remnant of the original mouth of the Duwamish River. Maintained as a federal navigation channel by the U.S. Army Corps of Engineers, the East, West, and Lower Duwamish waterways support considerable commercial navigation and remain one of the City of Seattle’s primary industrial zones. Two city neighborhoods, South Park and Georgetown, are located along the Lower Duwamish Waterway. Both neighborhoods include a mixture of residential, recreational, commercial, and industrial land uses.

The authorized depth of the navigation channel varies from approximately 17 m below mean lower low water (MLLW) along Harbor Island to 5 m below MLLW at the Upper Turning Basin at the top of the Lower Duwamish Waterway. Widths range from 60 m to 275 m; the average width is 134 m. Seven principal lateral slips exist along the Lower Duwamish Waterway, most of which originate as remnant meanders of the original Duwamish River channel (Appendix B).

King County 2‐5 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

The Upper Turning Basin serves as a trap for sediment carried downstream (Appendix B). This basin and portions of the navigation channel just downstream are dredged periodically to remove accumulated sediment and reduce sediment transport into the lower reaches of the waterways.

The shoreline along the majority of the Duwamish Estuary includes constructed bulkheads, piers, wharves, sheet piling walls, buildings that extend over the water, and steeply sloped banks armored with riprap, sheet pile, or other fill material (Weston, 1999). Shoreline constructions, dams, and other modifications cause changes in hydrologic flow patterns and produce scour, sedimentation, and erosion.

Although the estuary is mostly devoid of natural habitat, some shallow intertidal benches remain in the nearshore, intertidal, and shallow sub‐tidal zones outside the navigation channel. The benches are of various dimensions and elevations, with minimum elevations of less than 1 m above MLLW (Windward and QEA, 2008). For decades, intertidal habitats have been dispersed in relatively small patches, with the exception of Kellogg Island (26 acres), which remains the largest contiguous undeveloped intertidal zone in the estuary (Tanner, 1991). Shoreline habitat restoration projects have been completed in recent decades. The largest restoration effort (5 acres) was completed by The Boeing Company in 2013 as part of ongoing contaminant remediation efforts.

Hydrology of the Duwamish Estuary The Duwamish Estuary drains approximately 484 square miles of the central Puget Trough, Western Cascade Lowlands, mountain highlands, and alpine areas (King County, 2002). The lowlands are dominated by urban and suburban areas, crossed by roads, and fragmented into patches of residential, commercial, and industrial uses (Figure 2‐4). These urbanized areas contain high fractions of impervious surfaces and associated stormwater drainage systems that discharge urban pollutants into local waterways.

Current management practices at the Howard A. Hanson Dam moderate flows by reducing winter peak flows and increasing summer flows. As a result, the Duwamish Estuary rarely exceeds 12,000 cfs flow annually (Windward, 2010).

The Duwamish Estuary is influenced by freshwater flows from the Duwamish and Green rivers and by the tidal flux of salt water in Elliott Bay. The mean tide stage is 2.1 m above MLLW, and maximum and minimum stages are 4.6 m above and 1.3 m below MLLW (Windward, 2010). The interface of fresh and salt waters is in constant motion and sometimes takes the form of a saltwater wedge between RM 2.8 and RM 4.8 (Windward, 2010). Saltwater wedges can cause increased resuspension of sediments (and associated contaminants) as the result of the higher rates of turbulence at the advancing or retreating upriver extremity of the saline layer (Figure 2‐5) (Kostachuk and Luternauer, 1989).

King County 2‐6 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 2-4. Levels of development in 2011 in land use areas surrounding the Duwamish Estuary study area.

King County 2‐7 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 2-5. Turbulence created at toe (leading edge) of salt water moving upriver under tidal force.

2.3 Historical and Current Uses

This section summarizes human and animal uses of the Duwamish Estuary.

Commercial and Industrial Uses In 1874, Seattle’s first railroad began attracting marine industrial activities near the current location of the Lower Duwamish Waterway. All major rail connections to Seattle from the south ran through the Georgetown neighborhood. Early railroad tracks crossed above the intertidal mudflats on pilings. By using the material dredged from the mouth of the Duwamish Estuary during the creation of the Lower Duwamish Waterway, the surrounding mudflats were filled and new railyards were built atop the new dry land.

By 1928, Seattle’s first municipal airport (Boeing Field) was built within a quarter mile of the Lower Duwamish Waterway. A few years later, Boeing opened its aircraft manufacturing plant (Plant 2) on the shores of the Lower Duwamish Waterway (Wilma, 2001).

The Port of Seattle is ranked as one of the busiest ports in the nation and supports a diverse range of commercial and industrial maritime activity in the East, West, and Lower Duwamish waterways. The Port uses the East and West waterways for container loading and transport, petroleum product transport, container storage, rail access, and intermodal transfer. In addition to ship traffic, tugboats, barges, and small craft use the waterways.

The Lower Duwamish Waterway hosts 5 miles of heavy and light industrial operations, including cargo handling and storage, marine construction, boat manufacturing, marina operations, concrete manufacturing, paper and metals fabrication, food processing, and airplane parts manufacturing.

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Other Human Uses Boating, fishing, and recreational use of waterside parks and restoration sites in the Duwamish Estuary is becoming more common but is still restricted by industrial activity, fish consumption advisories, and limited public access to shorelines. Fishing for migratory salmon is common. The Washington State Department of Health has issued advisories against the consumption of crab, shellfish, or fish (other than salmon) taken from the Lower Duwamish Waterway (WDOH, 2006). Despite such advisories, fishing and crabbing in the estuary occur along wharfs, piers, docks, and bridges that provide easy access to deep waters (King County, 1999).

Two Seattle neighborhoods—South Park and Georgetown—are located adjacent to the Lower Duwamish Waterway. These communities provide housing and services to employees of local businesses and industries. The South Park neighborhood is on the west side of the waterway near the southern border of Seattle city limits. A portion of the residential area abuts the Lower Duwamish Waterway, and several houses are located along the shoreline. The Georgetown neighborhood is east of the waterway and East Marginal Way South.

The Duwamish Estuary remains a usual and accustomed harvest area for both the Muckleshoot and Suquamish Indian tribes. These groups maintain rights for fishing in the waterways and for traditional ritual and cultural practices associated with various locations in the watershed. They fish, hunt, and gather in the area. Fishing of non‐resident migratory salmon constitutes an important part of tribal life. The Muckleshoot Tribe maintains a commercial net fishery for salmon in the estuary, and both the Muckleshoot and Suquamish tribes harvest seafood for cultural and ceremonial purposes.

Animals and Their Habitats EPA’s National Estuary Program has identified key water management issues that pose the greatest risk to estuaries, including forestry, development, alterations to water flow, upriver agriculture, shipping, dredging, fishing, and encroachment by invasive species. Habitats and wildlife in the Duwamish Estuary face these risks.

Before channelization and industrialization, the habitat associated with the estuary’s mouth was predominantly an intertidal, shallow sub‐tidal estuarine mudflat supporting a high diversity of wildlife. Today, nearly all the original habitat in the Duwamish Estuary has been filled, dredged, channelized, converted to bulkheads, and stabilized with riprap, sheet pile, and other armoring methods (AECOM, 2012). Wharfs, piers, and docks are common along the waterways and have prevented the growth of aquatic plants in some areas (Battelle et al., 2001).

Little tidal marsh, mudflats, or intertidal areas remain to support local wildlife. Areas of quality habitat that do exist are of limited size and are isolated from each other. However, the total acreage of restored habitat is expected to increase as the result of growing interest

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in improving subtidal, intertidal, and nearshore habitat quality through Superfund and other programs.

Many species of invertebrates, reptiles, fish, birds, and mammals are still found in the Duwamish Estuary (AECOM, 2012). Some populations are resident (shellfish, benthic invertebrates, fish), while others use the waterways periodically (seasonal migration, daily foraging, breeding, or juvenile rearing). Seventeen species have been identified that are listed with federal or state protection status (Table 2‐1) (Windward, 2010; AECOM, 2012).

Table 2-1. Species in the Duwamish Estuary listed under the Endangered Species Act or by the Washington State Department of Fish and Wildlife. Common Name Scientific Name Federal Status State Status Bald eagle Haliaeetus leucocephalus FSC SSS Brown rockfish Sebastes auriculatus FSC SCS Bull trout Salvelinus confluentes FTS SCS Chinook salmon Oncorhynchus tshawytscha FTS SCS Coho salmon Oncorhynchus kisutch FCS ─ ─ Common loon Gavia immer ─ ─ SSS Common murre Uria aalge ─ ─ SCS Killer whale (orca)a Orcinus orca FES SES Merlin Falco columbarius ─ ─ SCS Pacific cod Gadus macrocephalus FSC SCS Pacific herring Clupea herengus pallasi FCS SCS Peregrine falcon Falco peregrinus FSC SSS Puget Sound steelhead Oncorhynchus mykiss FTS ─ ─ River lamprey Lampetra ayresi FSC SCS Rockfish species Sebastes spp. ─ ─ SCS Walleye Pollock Theragra chalcogrammus FSC SCS Western grebe Aechmophorus occidentalis ─ ─ SCS Abbreviations are as follows: FCS = federal candidate species, FSC = federal species of concern, FES = federal endangered species, FTS = federal threatened species, SCS = state candidate species, SES = state endangered species, and SSS = state sensitive species. a Status Puget Sound southern resident orca do not use the Duwamish Estuary but may occasionally be present in Elliott Bay and, thus, exposed to contaminants from the estuary.

2.4 Contaminant Sources and Pathways

Chemicals originating from human activity are constantly moving toward the waters and sediments of the Duwamish Estuary. These chemicals enter the environment during manufacture, use, and disposal and become associated with air, water, and soil. Because these environmental media are in constant motion, contaminants associated with them are also in motion. Transport mechanisms in an urban and industrial environment are complex and include stormwater flow, groundwater movement, air deposition, soil erosion, leaching, diffusion, and volatilization.

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Figure 2‐6 shows a conceptual site model that identifies the major sources, pathways, and fates of contaminants in the Duwamish Estuary (Ecology, 2014). The estuary has been subject to years of discharges and spills originating from multiple urban and industrial sources. Some sources and pathways (logging, industrial manufacturing) have played a greater role in the 20th century than they do now while others are associated with current high levels of urbanization. This section describes general sources and pathways identified in the Superfund documentation for the East, West, and Lower Duwamish waterways (AECOM, 2012; Windward and Anchor QEA, 2014).

Figure 2-6. Conceptual site model for the Duwamish Estuary showing major sources, pathways, and fates of contamination. Major sources and pathways are as follows:  Industrial byproducts and wastes. Industrial sources of contaminants have historically included some of the most toxic and persistent compounds to enter the Duwamish Estuary, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), dioxins, arsenic, and mercury (Windward 2010; Windward & Anchor QEA, 2014).  Vessels. Sources of contamination related to shipping include paint and coatings on ship hulls (copper, tributyltin) and fuels and oils often released or spilled (gray water and bilge) from commercial and recreational vessels. Propeller wash of large vessels and tug boats can re‐suspend contaminated sediments (Windward, 2010).  Local dredging operations. Dredging of sediments can also resuspend contaminants and make them susceptible to surface water flow, leaching, and other pathways.

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 Atmospheric deposition. Contaminants associated with fine particulate matter (factory exhausts, transportation‐related exhausts, degrading construction materials) can be transported by winds. Volatile organic contaminants, including PCBs, PBDEs, and PAHs, can also move in the atmosphere in a gaseous state, even in the absence of wind. Airborne contaminants can be deposited back to land or water (and submerged sediments) by gravity, rain, or the precipitation of volatilized contaminants.  Leaching of contaminants. Contaminants associated with soils, sediments, industrial waste deposits, and construction materials can become dissolved in water (rain, snow, surface water, and groundwater) and be transported to waterbodies and their sediments. Construction materials can leach contaminates by rain and snow while above ground, by groundwater while underground, or by surface waters while submerged (pilings, bulkheads, piers, wharfs, and docks). Dissolved contaminants are transported by water movement until local water chemistry partitions them into other phases. Once partitioning occurs, most contaminants become adsorbed to organic material and become incorporated into sediments.  Spills and illicit dumping. Accidental and intentional discharges of industrial and household products into sewers, storm drains, and directly into the Duwamish Estuary are common, especially in small quantities (Windward, 2010).  CSO and stormwater discharges. CSO and stormwater discharges carry contaminants from sewage, domestic and industrial waste, fertilizers, pesticides, and other sources. Point source discharges are regulated through National Pollutant Discharge Elimination System (NPDES) permits issued to public agencies (such as King County and the City of Seattle) and private entities.3 County and city CSO outfall locations and public and private surface water outfalls in the study area are shown in Figure 2‐7.

3 "Point source" means any discernible, confined, and discrete conveyance, including treatment plant, CSO, and stormwater outfalls. Nonpoint source pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage, or hydrologic modification.

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Figure 2-7. CSO and surface water outfalls in the Duwamish Estuary.

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2.5 King County CSO Discharge Sites

In much of Seattle, including the majority of the land surrounding the Duwamish Estuary, sewer infrastructure is part of a combined sewer system that collects both stormwater and sewage in the same pipes. Some of the land is on a completely separated system or on a partially separated system, where home gutters drain to the treatment plant and stormwater from the streets is sent to a storm drain that discharges directly to the estuary (Figure 2‐7).

Although CSOs contribute only a portion of the pollution that enters Duwamish Estuary, CSOs may potentially harm aquatic ecosystems, impact human use, and pose other public health and environmental concerns. The following constituents may be found in CSOs:  Pathogens (disease‐causing bacteria, viruses, and parasites)  Oxygen‐depleting material (organic matter)  Suspended solids, which can hamper sight‐feeding fish and bury habitat  Toxins, including copper, endocrine‐disrupting compounds, and pesticides  Nutrients (phosphorus and nitrogen), which may cause eutrophication and toxic algal blooms Of the 17 CSO outfalls located in the Duwamish Estuary, 3 are maintained by the City of Seattle and 14 by King County (Figure 2‐7). The three Seattle CSOs are uncontrolled. Five county CSOs are controlled, and nine are uncontrolled. (One of the nine uncontrolled CSOs, the Harbor Ave CSO, is nearly controlled.) In the past, the County’s South Treatment Plant, located in Renton, released its treated effluent into the Green River (RM 10.5). The effluent discharge was rerouted to Puget Sound in the late 1980s. The Green River outfall was retained for emergency discharge of untreated wastewater, but emergency release to the Green River has never occurred.

King County plans to bring all its CSOs into control by 2030 through storage, green stormwater infrastructure, treatment, and improved conveyance. The City of Seattle is implementing an integrated plan. Projects to control the largest, most frequent city CSO discharges and projects to manage stormwater in identified areas will be built by 2025; smaller CSO control projects will be built by 2030.

Discharge Site Descriptions This section describes the current status of King County CSOs in the Duwamish Estuary and their locations as background information to aid this Water Quality Assessment and Monitoring Study in examining water quality and guiding decisions for subbasins where uncontrolled county CSOs discharge. The CSOs from north to south are as follows:  Lander St. The Lander Street Regulator Station sends wastewater flows from the Lander Street Trunk to the Elliott Bay Interceptor and on to the West Point Treatment Plant. The area is served by separated sewers. Stormwater from the Lander St storm drain is sent to West Point during low stormwater flow periods.

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During high flows, stormwater discharges directly to the East Waterway and wastewater is stored in upstream pipes. When wastewater flow exceeds storage capacity, the regulator station diverts excess flow to the Lander St storm drain for discharge to the waterway. This CSO location will be controlled by 2030 through construction of a new 151‐MG CSO wet weather treatment facility to control the King St and Kingdome CSOs into Elliott Bay along with the Lander St and Hanford #2 CSOs into the East Waterway. The facility’s outfall will likely be located in either Elliott Bay or the waterway.  Hanford #2. The Hanford Street Regulator Station sends combined sewage flow from the Hanford Trunk to the Elliott Bay Interceptor for conveyance to West Point. The station directs excess flows to the Hanford #2 outfall for discharge to the East Waterway. This CSO location will be controlled through the project described for the Lander St CSO.  Harbor Ave. The Harbor Avenue Regulator Station sends combined flows from the north and northeast areas of West Seattle to the Delridge Trunk. The station diverts excess flow to a City of Seattle storm drain that discharges to the West Duwamish Waterway. This Harbor Ave CSO location is nearly controlled. It is currently being monitored to ensure that changes made to the system have achieved control.  Chelan Ave. the Chelan Avenue Regulator Station receives combined flows from the Delridge Trunk in West Seattle and sends them via the West Duwamish Interceptor east of the waterway to the Duwamish Pump Station, Elliott Bay Interceptor, and West Point. The station diverts excess flows through a City of Seattle storm drain to the Chelan Ave CSO location in the West Waterway. The CSO control plan calls for construction of a 3.85‐MG storage tank and modifications to an existing pipeline by 2025 to bring this location into control.  W Duwamish. The W Duwamish CSO location is located at the forebay of the Duwamish Siphon, which carries combined flows from the Chelan Avenue Regulator Station under the Lower Duwamish Waterway east to the Duwamish Pump Station. A gate at the forebay opens to allow excess combined flows to discharge via an outfall to the west side of the waterway. This CSO location is controlled.  E Duwamish. The E Duwamish CSO location is at the aftbay to the Duwamish Siphon on the east side of the Lower Duwamish Waterway. A gate opens to allow for overflows above the capacity of the Duwamish Pump Station. This CSO location is controlled.  Hanford #1. CSOs from three regulated CSO locations in the Rainier Valley and one regulated CSO in the SoDo area of Seattle discharge through a City of Seattle storm drain to the east side of the Lower Duwamish Waterway near the E Duwamish CSO outfall (shown as Hanford #1 on Figure 2‐7). A project to control the Rainier Valley CSO locations is under way. The project, scheduled for completion in 2017, will include new storage and conveyance facilities. The SoDo CSO location is controlled.  Brandon St. The Brandon Street Regulator Station sends flows from the Brandon Street Trunk to the Elliott Bay Interceptor. Excess flows discharge to the east side of the Lower Duwamish Waterway. The Brandon St and S Michigan CSO locations will

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be controlled through construction of a 66‐mgd wet weather treatment facility (Georgetown Wet Weather Treatment Station) scheduled for completion in 2022. The new outfall for the facility will be located at the S Michigan CSO in the Lower Duwamish waterway.  Terminal 115. A flap gate in the West Duwamish Interceptor, which travels north along the west side of the Lower Duwamish Waterway, allows excess flows to empty into a local storm drain that discharges to the Terminal 115 CSO location on the waterway. The CSO control plan includes new conveyance and a 0.32‐MG storage pipe to control this location and the W Michigan CSO location by 2025. The project will include green stormwater infrastructure to help reduce the required capacities of the new facilities.  S Michigan. The South Michigan Street Regulator Station in south Seattle directs combined flow from the Michigan Street Trunk to the Elliott Bay Interceptor. Excess flow is diverted to the S Michigan CSO location on the east side of the Lower Duwamish Waterway. This location will be controlled through the project described for the Brandon St CSO location.  W Michigan. The West Michigan Street Regulator Station directs combined flow from the Highland Park area of Seattle to the West Duwamish Interceptor during normal flows and directs excess flow to the W Michigan CSO outfall on the west side of the Lower Duwamish Waterway below the First Avenue South Bridge. This location will be controlled as part of the Terminal 115 CSO control project described above.  E Marginal. The East Marginal Way Pump Station pumps combined flows along the Elliott Bay Interceptor, including flows from the Norfolk Regulator Station to the south. The station serves an area that includes the Boeing industrial complex. Excess flows discharge through the E Marginal CSO outfall on the east side of the Lower Duwamish Waterway. This CSO location is controlled.  8th Ave S. The 8th Avenue South Regulator Station sends flows from the Highland Park area of Seattle (Rainier Vista Interceptor) to the West Duwamish Interceptor. The station diverts excess flows to the 8th Ave S CSO outfall on the west side of the Lower Duwamish Waterway. This CSO location is controlled.  Norfolk. The Norfolk Street Regulator Station regulates flow from the Henderson Street Trunk into the Elliott Bay Interceptor and on to the East Marginal Way Pump Station. The station directs excess flow to the Norfolk CSO outfall on the east side of the Lower Duwamish Waterway just upstream of the Upper Turning Basin. This CSO location is controlled.

Average Annual Discharge Frequencies and Volumes Table 2‐2 shows average annual volumes and frequencies of discharges from King County CSO locations in the Duwamish Estuary from 2009 through 2013.

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Table 2-2. Average annual discharge frequencies and volumes of King County CSOs in the Duwamish Estuary (2009–2013). CSO Name Location Average Annual Average Annual Control Frequency Volume (MG) Statusa Lander St East Waterway 16.8 337 Uncontrolled Hanford #2 East Waterway 16.4 165 Uncontrolled Chelan Ave West Waterway 4.8 7.02 Uncontrolled Harbor Ave West Waterway 1.4 9.24 Nearb Lower Duwamish Hanford #1 18.9 56.8 Uncontrolled Waterway Lower Duwamish E Duwamish < 1 1.21 Controlled Waterway Lower Duwamish W Duwamish < 1 < 0.1 Controlled Waterway Lower Duwamish Terminal 115 1.6 1.40 Uncontrolled Waterway Lower Duwamish S Michigan 12 53.9 Uncontrolled Waterway Lower Duwamish 8th Ave S < 1 < 0.1 Controlled Waterway Lower Duwamish Brandon St 10.6 26.9 Uncontrolled Waterway Lower Duwamish W Michigan 5.8 1.62 Uncontrolled Waterway Lower Duwamish E Marginal 0 0 Controlled Waterway Lower Duwamish Norfolk 0 0 Controlled Waterway a Control status is determined through calculation of a 20‐year moving average. b The Harbor Ave CSO is being monitored to ensure that changes made in the system have achieved full control.

2.6 Historical Contamination Cleanup Sites

Three EPA designated Superfund sites are located in the Duwamish Estuary: Harbor Island, Lockheed West Seattle, and Lower Duwamish Waterway. The following sections describe completed and planned remediation of contaminated areas in these sites. Figure 2‐8 shows their locations.

Harbor Island The Harbor Island Superfund site includes both the industrialized upland area of the island and offshore sediment. An EPA inspection in 1982 of the lead smelter facility formerly located on Harbor Island identified lead-contaminated soil. The inspection resulted in the listing of the site on the National Priorities List (NPL) in 1983. The soils on Harbor Island were investigated by Ecology in 1985 and were determined to be contaminated with metals, PCBs, and PAHs. Between 1988 and 1995, a series of investigations were conducted of the upland areas and marine sediments surrounding the island. EPA issued a Record of Decision (ROD) in 1996 summarizing the contamination and the steps needed to clean up

King County 2‐17 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary the upland areas and several areas of marine sediments including parts of the West and East waterways.

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Figure 2-8. Sediment cleanup and early action areas in the Duwamish Estuary.

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The Superfund site comprises seven operable units (OUs) that include a mix of upland soil, marine sediment, and groundwater contamination (EPA, 2010). Four of the OUs—the West Waterway, East Waterway, Lockheed Shipyard, and Todd Shipyard—are in the study area for this report:  Studies begun in 1985 found that sediments in the West Waterway were contaminated with PCBs, lead, mercury, and tributyltin (TBT). In 2003, a “no action” ROD for the West Waterway OU was issued based on the determination that public health and the welfare of the environment were not at risk from contaminants identified in the waterway (EPA, 2003).  The Todd Shipyards OU is located on the north end of Harbor Island. The former shipyard site was contaminated by petroleum, PCBs, PAHs, and marine paint additives, which contributed to high metals concentrations in the sediments. Various dredging and capping projects have been completed at the site, which is now undergoing long‐term monitoring (EPA, 2010).  The Lockheed Shipyard OU is divided into the upland and sediment OUs. The upland OU, owned by Lockheed Martin, has since been remediated and removed from the NPL in 1996. Lockheed sold the upland property to the Port of Seattle in April 1997. Lockheed continued to lease the submerged lands between the inner and outer harbor line until arrangements were made for the lease to be held by the Port. Remediation of the sediment OU, consisting primarily of dredging and capping, was completed in 2005. Contaminants of concern include metals, low molecular weight polycyclic aromatic hydrocarbons (LPAHs), PCBs, and TBT.  The sediments, waters, and tissues of fish and shellfish inhabiting the East Waterway OU have been the subject of multiple investigations and cleanup actions. Contaminants of concern include PCBs, arsenic, PAHs, TBT, and dioxins/furans (Windward and Anchor QEA, 2014). In 2005, as part of a federally authorized navigation channel deepening project, the Port of Seattle removed over 200,000 cubic yards of contaminated sediment from the waterway. A layer of sand was placed over remaining contaminated sediments to protect benthic marine life. The Port and U.S. Coast Guard continue to do routine maintenance dredging in the waterway. The supplemental remedial investigation documenting the nature and extent of contamination and human health and ecological risks was completed in 2014 (Windward and Anchor QEA, 2014). A feasibility study (FS) for alternatives to clean up contaminated sediments was completed in late 2016. Following the FS, EPA will issue an ROD for cleanup of the sediments.

Lockheed West Seattle The Lockheed West Seattle Superfund site is located west of the West Waterway. The former shipyard property was sold to the Port of Seattle in 1992. Paint, metal scrapings, and sandblast grit from boat refurbishing activities were discharged directly to Elliott Bay, resulting in contamination of the sediments. Contaminants include metals, PCBs, TBT, and petroleum products (Tetra Tech, 2012). While the majority of the site is located in Elliott Bay, a small section lies in the West Waterway.

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The site was added to the NPL and designated a Superfund site because of contamination in the upland areas and adjacent sediments. The uplands portion was remediated under state authority and is now part of Terminal 5, one of the Port's container shipping facilities. The aquatic area has not yet been remediated. The remedial investigation (RI) report and cleanup FS were submitted to EPA and finalized in 2012 (Tetra Tech, 2012), and an ROD was issued in 2013 (EPA, 2013). Sediment cleanup is expected to begin in 2018.

Lower Duwamish Waterway In the late 1990s NOAA and EPA investigated sediment contamination in the Lower Duwamish Waterway from south of Harbor Island to the south end of the King County International Airport (KCIA) (RM 3.8).4 The studies found that the sediments were contaminated with semivolatile organic compounds, PCBs, and inorganic compounds that were considered a risk to human health and the environment.

In 2000, the City of Seattle, King County, Port of Seattle, and The Boeing Company formed the Lower Duwamish Waterway Group and signed an Administrative Order on Consent to conduct an RI/FS, with oversight by EPA and Ecology, in the Lower Duwamish Waterway. In September 2001, a 5‐mile stretch of the Lower Duwamish Waterway was formally listed on the NPL to address the sediment contamination and, in 2002, as a Washington Model Toxics Control Act (MTCA) site (Windward, 2010).

In 2003, the Phase 1 RI was completed. Seven sites along the main waterway channel (RM 0.0 to RM 5.0) were identified as the most contaminated areas in the waterway (Figure 2‐ 8). These sites were designated as cleanup early action areas (EAAs) and scheduled for remediation prior to the larger Superfund cleanup effort. The EAAs and their status are as follows:  Duwamish/Diagonal. An outfall at this site discharges both stormwater flow and wastewater flow from four King County CSO diversion sites. The sediments in the EAA contained high levels of PCBs, mercury, and phthalates. King County and the City of Seattle completed sediment cleanup of the site in 2005. The cleanup consisted of dredging and capping sediments in the area.  Trotsky Inlet. The Trotsky Inlet site is under an MTCA order to conduct an RI/FS and develop a cleanup action plan. Contaminants include PCBs, PAHs, pesticides, and metals including arsenic and copper.  Slip 4. The City of Seattle completed the sediment cleanup of the Slip 4 EAA in 2012. The sediments contained high levels of PCBs and carcinogenic PAHs (cPAHs).  Boeing Plant 2/Jorgensen Forge (BP2/JF). Sediment cleanup alongside the BP2 facility was completed in early 2015. Concurrently, the Jorgensen Forge facility received an Enforcement Order from Ecology to conduct an RI/FS and prepare a

4 NOAA = National Oceanographic and Atmospheric Administration.

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sediment cleanup plan. Sediments in the BP2/JF‐EAA were contaminated with metals (chromium, copper, cadmium), PCBs, cPAHs, and phthalates.  Terminal 117 (T117). Sediment cleanup of the T117 EAA was completed by the Port of Seattle and City of Seattle in early 2015. Contaminants of concern in sediments included PCBs, dioxin/furans, total petroleum hydrocarbons, and metals (arsenic, copper, lead, zinc).  Norfolk. The Norfolk CSO site is located at this EAA. King County and the City of Seattle completed cleanup of historical sediment contamination in 1999. The sediments were dredged and backfilled. Boeing conducted additional cleanup in 2003. The sediments contained high levels of mercury, phthalates, and PCBs.

For the Lower Duwamish Waterway, the RI was completed in 2010 and the FS in 2012 (AECOM, 2012). In November 2014, the final ROD was issued (EPA, 2014). Future cleanup measures will include 105 acres of dredging, 24 acres of sediment capping, and 48 acres of enhanced natural recovery. These measures seek to reduce health risks to people and aquatic life.

Ecology issued a source control strategy for the Lower Duwamish Waterway in 2004. Area‐ specific Source Control Action Plans (SCAPs) were developed to address ongoing sources of contaminants. These plans were designed to reduce inputs prior to cleanup and prevent recontamination of cleaned sediments.

2.7 EPA-Approved Listed Impairments

The federal Clean Water Act, adopted in 1972, requires that all states restore their waters to be “fishable and swimmable.” Section 303(d) of the Clean Water Act established a process to identify and clean up polluted waters. Every two years, all states are required to assess the quality of their surface waters, including all rivers, lakes, and marine waters where data are available.

Waters whose beneficial uses (such as drinking, recreational, aquatic habitat, and industrial uses) are impaired by pollutants are placed in the polluted water category in the water quality assessment. These waterbodies fall short of state surface water quality standards and are not expected to improve in the next two years. The “303(d) list” comprises waters in the polluted water category. The current (2012) EPA‐approved 303(d) listing of impairments in the Duwamish Estuary, Duwamish River, and Green River is presented in Table 2‐3.

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Table 2-3. Water, Tissue, and Sedimnt Quality Impairments in the Duwamish Estuary, Duwamish River, and Green River (2012) Waterbody Medium Parameter Listing ID Bacteria 13150, 13151 Watera Dissolved oxygen 12702, 12703 Arsenic, inorganic 64734, 64735, 64736, 64738 Benzo(a)anthracene 64354 64084, 64172, 64216, Benzo(a)pyrene 64261, 64309, 64355 64085, 64173, 64217, Benzo(b)fluoranthene 64262, 64310, 64356 64086, 64174, 64218, Benzo(k)fluoranthene 64263, 64311, 64357 64090, 64178, 64222, Tissue Chrysene 64267, 64315, 64361 64091, 64179, 64268, Dibenzo(a,h)anthracene 64316, 64362 64105, 64193, 64238, Indeno(1,2,3-cd)pyrene 64283, 64331, 64376 High molecular weight polycyclic 36171 aromatic hydrocarbons (HPAHs) Dieldrin 35595 Polychlorinated biphenyls (PCBs) 33698, 63653, 8192 Duwamish 2,3,7,8-TCDD 64297 Estuary Bis(2-ethylhexyl)phthalate 64133, 64360 507652, 507660, 508305, 603503, 605242, 605433, 605677, 607316, 607351, 608158, 610786, 611290, 613359, 611904, 614728, Sediment bioassay 615720, 618387, 620983, 622723, 623743, 624091, 624887, 625339, 625340, 625341, 625342, 625372, 625373, 625401, 622318 Arsenic 611979, 625344, 625375 507023, 611982, 625347, Cadmium Sediment 625378 Chromium 611983, 625348, 625379 Copper 611985, 625350, 625381 Lead 611990, 625357, 625385 507037, 611991, 625358, Mercury 625386 Silver 611996, 625362, 625391 Zinc 611997, 625363, 625392 2-methylnaphthalene 612000 Acenaphthene 612001, 625366 Anthracene 611978, 625343, 625374 Benzo(a)anthracene 611998, 625364

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Waterbody Medium Parameter Listing ID Benzo(a)pyrene 611980, 625345, 625376 Benzo(g,h,i)perylene 612002, 625367, 625395 Benzofluoranthenes, total (b+k+j) 612003, 625368, 625396 Chrysene 611984, 625349, 625380 611986, 625352, Dibenzo(a,h)anthracene 625382 Fluoranthene 611987, 625354, 625383 Fluorene 611988, 625355 Indeno(1,2,3-cd)pyrene 611989, 625356, 625384 Naphthalene 612005 Phenanthrene 612006, 625371, 625400 Pyrene 611995, 625361, 625390 Low molecular weight polycyclic 611999, 625365, 625393 aromatic hydrocarbons (LPAHs) HPAHs 611992, 625359, 625387 PCBs 611993, 625360, 625388 4-methylphenol 625394 Phenol 611994, 625389 Benzoic acid 625397 Bis(2-ethylhexyl)phthalate 611981, 625346, 625377 Butyl benzyl phthalate 625369, 625398 Di-n-butyl phthalate 625351 Dimethyl phthalate 625353 Di-n-octyl phthalate 626399 Dibenzofuran 612004, 625370 Watera pH 7474, 7475 4,4’ DDD 14087 Duwamish 4,4’ DDE 14088 River Tissue 4,4’ DDT 14086 Alpha-BHC 14089 PCBs 14090 Bacteria 12569, 13159 Green River Waterb 10812, 10824, 47547, Dissolved oxygen 47551, 48004 a Temperature is included in draft 2014 Water Quality Assessment and Candidate 303(d) list submitted to EPA. b The Green River has an approved total maximum daily load (TMDL) for temperature that is actively being implemented (listing IDs: 6574, 7037, 7043, 7479, 7480, 7482, 7483, 48622, 48625).

King County 2‐24 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

3.0 WATER QUALITY King County and Ecology have collected water quality data from the water column in the Green‐Duwamish area as part of long‐term monitoring programs. Short‐term programs have also collected data on trace metals and organic compounds. This chapter analyzes datasets from these efforts to characterize current conditions, identify long‐term trends, and discuss potential human health and ecological concerns. The data are presented under the following categories: bacteria, physical parameters, nutrients, metals, and organics.

3.1 Sampling Sites and Parameters

Long‐term King County and Ecology monitoring programs have sampled water quality in the Green‐Duwamish area since the mid‐1970s. The programs collect monthly samples for analysis of fecal coliform bacteria, physical parameters (temperature, conductivity, dissolved oxygen, turbidity, total suspended solids, pH, and total alkalinity, and nutrients (ammonia, nitrate + nitrite‐N, total nitrogen, total phosphorus, and orthophosphate).

Long‐term monitoring sites in the Green‐Duwamish area are shown in Figure 3‐1; sampling sites in the Duwamish Estuary in relation to CSO locations are shown in Figure 3‐2; and information on each site, including sampling depth and timeframes, is given in Table 3‐1. King County’s 15 sampling sites span the whole area; Ecology collects samples from two sites in the Green River. See http://green2.kingcounty.gov/streamsdata/Default.aspx for King County data and http://www.ecy.wa.gov/eim/ for Ecology data.

Figure 3-1. Long-term monitoring sampling sites in the Green-Duwamish area.

King County 3‐1 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-2. Long-term monitoring sites and CSO locations in the Duwmaish Estuary.

King County 3‐2 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-1. Long-term ambient water quality monitoring sites in the Green-Duwamish area. River Depths Years Site ID Locator Agency Description Easting Northing Milea Sampled Sampled Below 1 m 1996–1997 EW lower HNFD01 King County East Waterway – Near South Hanford Street 1267486 214139 – 2008–2013 Above 1 m 1996–1997 EW upper HNFD01 King County East Waterway – Near South Hanford Street 1267486 214139 – 2008–2013 West Waterway – Upstream of the Spokane Street Bridge, Below 1 m WW-a lower LTKE03 King County 1265871 211418 – 2005–2013 middle of the channel West Waterway – Upstream of the Spokane Street Bridge, Above 1 m WW-a upper LTKE03 King County 1265871 211418 – 2005–2013 middle of the channel West Waterway – Upstream of the Spokane Street Bridge, on Below 1 m WW-b lower 0305 King County 1265729 211346 – 1970–2004 west side of channel West Waterway – Upstream of the Spokane Street Bridge, on Above 1 m WW-b upper 0305 King County 1265729 211346 – 1970–2004 west side of channel LDW-0.1 LTLF04 King County Lower Duwamish Waterway – At the south end of Harbor Island 1266494 210509 0.1 Above 1 m 2003–2004 LDW-3.0 LTTL02 King County Lower Duwamish Waterway – Duwamish Waterway Park 1273214 197412 3 Above 1 m 2007–2010 0307, Below 1 m LDW-3.3 lower King County Lower Duwamish Waterway – 16th Ave. S Bridge 1274591 196629 3.3 1970–2013 LTUM03 0307, Above 1 m LDW-3.3 upper King County Lower Duwamish Waterway – 16th Ave. S Bridge 1274591 196629 3.3 1970–2013 LTUM03 Lower Duwamish Waterway – Upstream side of Boeing Above 1 m LDW-4.8 LTXQ01 King County 1278053 190313 4.8 2009–2013 pedestrian bridge, mid span DR-6.3 0309 King County Duwamish River – East Marginal Way Bridge at S 115th Street 1280823 186038 6.3 Above 1 m 1970–2008 Duwamish River – Foster Links Golf Course, downstream of Above 1 m DR-9.8 FL319 King County 1288012 177997 9.8 2011–2012 confluence with Black River Lower Green River – Bridge at Fort Dent Park upstream of Black Above 1 m GR-11.1 3106,A310 King County 1290289 173862 11.1 1970–2013 River 0311, King County, Lower Green River – Renton Junction Bridge on West Valley Above 1 m GR-11.6 1290528 173007 11.6 1970–2013 09A080 Ecology Road at Highway 1 Lower-Middle Green River – Bridge on SE Auburn-Black Above 1 m GR-32.8 A319 King County 1307302 113108 32.8 1972–2012 Diamond Road, upstream of Soos Creek Lower-Middle Green River – Bridge on 212th Ave SE, upstream Above 1 m GR-40.6 B319 King County 1337103 105406 40.6 1993–2013 of Newaukum Creek Lower-Middle Green River– Bridge at SE Flaming Geyser Road Above 1 m GR-42.0 FG319 King County 1341097 104038 42 2011–2012 in Flaming Geyser State Park Upper-Middle Green River– Bridge on Cumberland-Palmer Road Above 1 m GR-56.9 09A190 Ecology 1377404 118271 56.9 1977–2012 at Kanaskat Upper-Middle Green River – Below Howard A. Hanson Dam, at Above 1 m GR-63.1 E319 King County 1401243 104678 63.1 2001–2003 USGS gage 12105900 a River miles conform to the convention used in the Remedial Investigation/Feasibility Study for the Lower Duwamish Waterway Superfund site. The starting point of RM 0 is at the southern tip of Harbor Island (Windward, 2010).

King County 3‐3 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Short‐term King County and Ecology programs have monitored additional parameters in the water column including metals and organic compounds. Additionally, samples were collected in 2008 and 2009 from the surface water of the East Waterway and analyzed for metals and organic compounds as part of the Harbor Island Superfund East Waterway Operable Unit Supplemental Remedial Investigation (SRI) (Windward, 2009). Four to five locations were sampled over five events. Sampling was conducted during an ebbtide (outgoing tide) during the three hours before low tide, except at a location in Slip 27, which was sampled during the slack tide. During the fourth sampling event, samples were also collected during a floodtide (incoming tide) at the three locations in the main channel of the waterway. See Appendix C for a map of the sampling locations for the study and Windward (2009) for further information.

3.2 Sampling and Analysis Methodologies

Grab samples for lab analysis were collected at each site and from various depths in the water column when possible. Samples from King County marine sites (sites in the Duwamish Estuary) were collected with an oceanographic rosette and a Seabird conductivity‐temperature‐dissolved oxygen depth (CTD) sampler. All sampling followed established equipment guidelines and King County standard operating procedures for water quality sampling.

Conductivity, temperature, pH, and dissolved oxygen (DO) were measured in the field using calibrated handheld units equipped with electronic sensors that were lowered into the water.

Parameters such as nutrients, alkalinity, metals, and fecal coliform bacteria were analyzed at the King County Environmental Laboratory (KCEL) or Ecology’s Manchester Environmental Laboratory in Manchester, Washington. Only KCEL methods are described here. Quality assurance/quality control procedures included the use of blanks, duplicates, and spikes where appropriate. All data were reviewed by KCEL staff before entry into the Laboratory Information Management System (LIMS) database.

Samples at most sites were taken from the surface (above 1 m). Samples at four marine sites in the East, West, and Lower Duwamish waterways were collected from the upper and lower depths of the water column. The sample depths varied with each sampling event depending on the tide at the time of sampling. Upper depth samples were taken from the same mixing zone as all other upper depth samples. Similarly, all lower depth samples were taken from the same mixing zone. For this report, concentrations from samples taken at multiple depths in the same mixing zone at the same site were grouped to describe a parameter. For example, nutrient concentrations observed from samples taken at 10‐ and 14.5‐m depths at the same site were grouped into the lower depth or subsurface category because both depths are near the bottom.

For the East Waterway SRI study, samples were collected by pumping water to the surface using a peristaltic pump and decanting directly into sample containers. Each location was

King County 3‐4 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary sampled at two depths in the water column, 1 m below the surface and 1 m above the bottom. Samples were collected September 11−12 and 25−27 to represent the dry season, December 9−11 and February 21−23 to represent the wet season, and January 7−9 to represent storm events.

A conservative approach was used for analyzing data:  If samples were qualified with an “H” and analyzed past their hold times, the data were not used.  Samples were qualified with a “B” when contamination was detected in analytical method blanks. If the sample concentration was within five times the concentration of the sample blank, the sample results were considered non‐detects.  Samples qualified with a “U” were considered non‐detects.  Minimums, maximums, and medians were calculated using only qualified detected values.  Medians were compared between sites and depths (when possible) using the nonparametric Kruskal‐Wallis and Mann‐Whitney tests. Concentrations below the method detection limit (MDL) were regularly observed for some parameters, including ammonia, metals, and organic compounds. These non‐detects are considered censored. The Kaplan‐Meier (KM) method was used to estimate the population mean for left‐censored data sets because it does not require an assumption for the distribution of the parameter (Kaplan and Meier, 1958; Betchal Jacobs Company, 2000; Helsel, 2005a; Helsel, 2005b).

Seasonal Mann‐Kendall tests with three‐day cumulative precipitation as a covariate were used for long‐term trend analysis of parameters with few or no censored data points (bacteria, conductivity, DO, pH, alkalinity, and nutrients). The Mann‐Kendall test is rank‐ based and thus can tolerate a small percentage of censored data. A multivariate linear regression was used to determine temperature trends.

3.3 Bacteria

Fecal coliform bacteria are generally found in the intestinal tracts and feces of humans and other warm‐blooded animals. They may enter the Green‐Duwamish area through both point (CSO and stormwater outfalls) and non‐point (surface runoff) sources. Although these bacteria are typically not directly pathogenic for humans, they may co‐occur with pathogens and thereby are used as a water quality indicator.

King County takes monthly samples for fecal coliforms at four sites in the Duwamish Estuary (EW, WW‐a, LDW‐3.3, LDW‐4.8) and two sites in the main stem of the Green River (GR‐11.1 and GR‐11.6) (Table 3‐2). Ecology collects monthly bacteria samples from two sites in the Green River (GR‐11.6 and GR‐56.9). Data from King County sites that were sampled in the past but are no longer sampled were included in the analysis if they provide relevant information for assessing current conditions or long‐term trends.

King County 3‐5 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Current Conditions In the last 10 years, fecal coliform concentrations were the lowest at the site farthest downstream (EW) and highest at a site over 3 miles upstream (LDW‐3.0) (Table 3‐2 and Figure 3‐3). Concentrations were relatively high in the freshwater layer in the Duwamish Estuary and the downstream reaches of the Green River, with similar median concentrations from RM 3.0 to RM 11.6.

The analyses found no clear increase in ambient concentrations of fecal coliform bacteria downstream of CSO outfalls (Figure 3‐3).5 As discussed in the next sections, the ambient concentrations across the study area may be affected more by factors such as salinity, which reduces fecal coliform bacteria survivorship, and dilution than by the frequency or magnitude of CSO discharges. The low concentrations in the East Waterway, in particular, suggest ambient concentrations are less than what would be expected based on CSO discharges and transport from upstream.

Table 3-2. Fecal coliform bacteria concentrations (CFU/100 mL) in the Green-Duwamish area (2004–2013).

Years Standard Geometric Site FODa Mean Median Min. Max. Evaluated Deviation Mean EW lower 2008–2013 67/71 2.4 5.1 1 0.6 0 26 EW upper 2008–2013 49/71 6.5 12.5 3 2.5 0 88 WW-a lower 2005–2013 99/108 4.8 6.6 3 2.3 0 38 WW-a upper 2005–2013 107/108 36.3 75.6 16 16 0 660 WW-b lower 2004 11/12 31.3 94.2 3 3.6 0 330 WW-b upper 2004 12/12 67.8 119.0 33 36 6 440 LDW-3.0 2007–2010 48/48 134.7 246.9 54 55 1 1,400 LDW-3.3 lower 2004–2013 118/120 19.6 44.2 9 8.9 0 450 LDW-3.3 upper 2004–2013 119/120 64.5 113.8 28.5 27 0 830 LDW-4.8 2009–2013 56/56 66.8 100.7 34 32 4 600 DR-6.3 2004–2008 58/58 63.1 84.5 33.5 39 5 460 GR-11.1 2004–2013 120/120 62.8 146.6 27 28 2 1,400 GR-11.6b 2004–2013 178/178 65.3 117.2 26 29 1 1,100 GR-32.8 2004–2008 58/58 34.6 47.1 14 17 1 230 GR-40.6 2004–2013 112/120 8.3 9.1 5 4.1 0 45 GR-56.9c 2004–2013 119/119 9.9 14.0 5 5.0 1 84 a FOD = frequency of detection. b Both Ecology and King County data. c Ecology data.

5 Differences among sites were compared using a non‐parametric Kruskal‐Wallis ANOVA (analysis of variance) with a post‐hoc gao test (R package: nparcomp). If more than one depth was sampled at a site, data from the upper depth were used for variance analysis.

King County 3‐6 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-3. Comparision of ranges of fecal coliform bacteria concentrations at sampling sites upstream and downstream of CSO locations in the Green-Duwamish area (2004– 2013).

Comparison to Criteria Several segments in the green‐Duwamish area are listed on Ecology’s 303(d) list of impaired waterbodies because of persistently high counts of fecal coliform bacteria. Water quality criteria vary across the study area depending on whether the segment is considered marine or fresh water and on likely recreational uses (WAC‐173‐201A‐210) (Table 3‐3). Ambient fecal coliform concentrations at one site therefore may meet criteria while the same concentrations at another site may exceed criteria.

Segments listed by Ecology as impaired include waters influenced by CSOs (West Waterway and portions of the Lower Duwamish Waterway) and waters upstream of CSOs (the Duwamish River and several sections of the Green River) (Ecology, 2013b). Fecal coliform concentrations in several tributaries of the Green River also exceed criteria, including Newaukum Creek more than 40 miles upstream of Elliott Bay. The impairment of multiple river segments suggests that fecal contamination may be extensive and ongoing throughout the watershed, although the listings do not help determine where and when criteria are exceeded and what the sources may be.

King County 3‐7 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-3. Water quality criteria for fecal coliform bacteria associated with each sampling site in the Green-Duwamish area. Geometric Mean Water Designated Peak Criterion Site Criterion Classification Recreational Use (CFU/100 mL)a (CFU/100 mL)b EW Marine Primary contact 43 14 WW-a Marine Primary contact 43 14 WW-b Marine Primary contact 43 14 LDW-3.0 Marine Primary contact 43 14 LDW-3.3 Marine Primary contact 43 14 LDW-4.8 Marine Primary contact 43 14 DR-6.3 Fresh Secondary contact 400 200 GR-11.1 Fresh Primary contact 200 100 GR-11.6 Fresh Primary contact 200 100 GR-32.8 Fresh Primary contact 200 100 GR-40.6 Fresh Primary contact 200 100 Extraordinary primary GR-56.9 Fresh 100 50 contact a No more than 10 percent of sample concentrations must be greater than the value listed. b Concentrations must not exceed the values listed.

Table 3‐4 illustrates how monthly fecal coliform concentrations at sampling sites over the last 10 years compared to peak and geometric mean water quality criteria. The geometric mean for each month was calculated using data from that month and the 11 preceding months. Samples collected from the upper portion of the water column were used because of the greater likelihood for human contact.

Fecal coliform concentrations routinely exceeded one or both criteria at 6 of the 11 sites. Exceedances occurred in the lower 12 miles of the system, which is consistent with the listing of several of these river segments as impaired. Fecal coliform concentrations at sites in the Duwamish Estuary often exceeded the peak criteria or contributed to a high geometric mean. Concentrations at sites upstream of CSOs were below the geometric mean criteria. Concentrations at two sites (GR‐11.1 and GR‐11.6) exceeded the peak standard.

One site in the estuary that previously failed to meet criteria is now meeting them. Samples collected from the upper depth at the East Waterway site in 1996 and 1997 had a mean concentration of 140 CFU/100 mL (median = 44 CFU/mL) and exceeded both peak and geometric mean criteria. After sampling resumed at the site in 2008, the mean concentration from the upper depth was 6.45 CFU/100 mL (median = 6.0 CFU/100 mL) and the site has been meeting criteria ever since. The reductions in fecal coliform concentrations between these two time periods were significant for both the lower and upper depths (Mann‐Whitney rank sum test; p < 0.001 for both depths).

King County 3‐8 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-4. Comparision of fecal coliform bacteria concentrations to water quality criteria at sites in the Green-Duwamish area (2004–2013).

2004 2005 2006 2007 2008 Site J F MAM J J A S ON D J F MAM J J A S ON D J F MAM J J A S ON D J F MAM J J A S ON D J F MAM J J A S ON D EW ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ WW‐a ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ XXXXXX X X X X X LDW‐3.0 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐X X XXX LDW‐3.3 X X XX X XXXX XXX X XXXXX XXX XXXXX X X X X X LDW‐4.8 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ DR‐6.3 X GR‐11.1 XXXX XXX X X GR‐11.6 XXX X XXX XX GR‐32.8 GR‐40.6 GR‐56.9 2009 2010 2011 2012 2013 Site JFMAMJJASONDJFMAMJJASONDJFMAMJJASONDJFMAMJJASONDJFMAMJJASOND EW XX WW‐a X X X X XXX X LDW‐3.0 XXXXXX XX XXXXX‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐‐‐‐‐‐‐‐‐ LDW‐3.3 X X X XXXXX X X XXXX X X LDW‐4.8 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ X XX X X XX XX XXXXXX X XXX X DR‐6.3 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ GR‐11.1 XX XX XX GR‐11.6 XXXX GR‐32.8 ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐ ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ GR‐40.6 GR‐56.9

-- = Insufficient data to calculate Geometric Mean = Pass Both Standards X = Sample exceeds peak value = Fail Peak Standard = Fail Geometric Mean Standard = Fail Geometric Mean Standard and Peak Standards

King County 3‐9 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Long-term Trends Long‐term trends in fecal coliform concentrations were analyzed using a seasonal Mann‐ Kendall test, which tests for trends while taking into consideration seasonal (monthly) variability. Because of the correlation of fecal coliform concentrations with rainfall, the amount of precipitation that fell during the three days prior to sampling was used as a covariate (Table 3‐5).6

Table 3-5. Spearman Rank Order correlations of fecal coliform bacteria concentrations in the Green-Duwamish area and percipitation three days prior to sample collection.

Number of Correlation Site p-value Significance Samples Coefficient EW lower 103 0.61 < 0.001 *** EW upper 103 0.55 < 0.001 *** WW-a lower 108 0.18 0.060 *** WW-a upper 108 0.32 < 0.001 *** WW-b lower 79 0.18 0.117 n.s. WW-b upper 280 0.40 < 0.001 *** LDW-3.0 48 0.30 0.042 *** LDW-3.3 lower 186 0.17 0.022 *** LDW-3.3 upper 391 0.20 < 0.001 *** LDW-4.8 56 0.28 0.037 *** LDW-6.3 323 0.23 < 0.001 *** GR-11.1 581 0.15 < 0.001 *** GR-11.6 1010 0.22 < 0.001 *** GR-32.8 325 0.28 < 0.001 *** GR-40.6 398 0.03 0.507 n.s. GR-56.9 452 0.01 0.807 n.s. *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

For the two Ecology sites, data are available dating back to 1970 (GR‐11.6) and 1975 (GR‐56.9). Because KCEL detection limits were higher than KCEL data until 1980, only King County data collected in 1980 and later are included. Trends were not analyzed for sites with less than 10 years of continuous monthly data. The direction of significant trends, Theil‐Sen’s slopes, and adjusted p‐values (corrected for inter‐block covariance) for each site are presented in Table 3‐6. Annual geometric means for each monitoring location are presented in Figure 3‐4.

With the exception of the lower depth at site LDW‐3.3 and the site farthest upstream (GR‐56.9), all sites evaluated showed significant decreasing trends in fecal coliform

6 All precipitation data were recorded at the Seattle‐Tacoma International Airport weather station: http://www.ncdc.noaa.gov/cdo‐web/datasets/GHCND/stations/GHCND:USW00024233/detail.

King County 3‐10 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary concentrations. The small slope for the lower depth of site LDW‐3.3 indicates that concentrations in the saltwater wedge have remained constant relative to concentrations in the freshwater layer above. Upstream at site GR‐56.9 where land cover is predominantly forest, fecal coliform concentrations have remained consistently low over time.

Table 3-6. Long-term trends in fecal coliform bacteria concentrations in the Green-Duwamish area (1970–2013).

Years No. of Slope Site Direction Significance p-value Evaluated Samples (CFU /mL/ yr) WW-b upper 1980–2004 280 ↓ *** < 0.001 –3.03 LDW-3.3 lower 1998–2013 186 -- n.s. 0.158 –0.33 LDW-3.3 upper 1980–2013 391 ↓ *** < 0.001 –4.19 DR-6.3 1980–2008 323 ↓ *** < 0.001 –5.67 GR-11.1 1980–2013 581 ↓ *** < 0.001 –3.50 GR-11.6 1970–2013 1010 ↓ *** < 0.001 –1.89 GR-32.8 1980–2008 325 ↓ *** 0.012 –0.47 GR-40.6 1980–2013 398 ↓ *** < 0.001 –0.08 GR-56.9 1975–2013 452 -- n.s. 0.496 0.00 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

Figure 3-4. Long-term trends in the Green-Duwamish area in fecal coliform bacteria as annual geometric means (1970−2013).

King County 3‐11 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Tidal cycles and associated fluctuating salinity have long been recognized as key factors affecting the persistence of fecal coliform bacteria in the water column in the Duwamish Estuary (Santos and Stoner, 1972; Haushild and Prych, 1976). As fresh water from the river mixes with the dense salt water from Elliott Bay, bacteria concentrations are affected by both dilution and the increase in salinity. This effect is apparent when comparing samples taken at upper and lower depths in the estuary (Figure 3‐5). Fecal coliform concentrations are significantly and consistently higher in the upper sample at each site (Wilcoxon signed rank test; p < 0.001 for each upper and lower comparison).

Regardless of whether fecal coliforms are transported from the Green River or are discharged directly into the estuary, research suggests that a reduction in bacteria occurs quickly once they reach the salt water (for example, Haushild and Prych, 1976, and Anderson et al., 2005). Early experiments in the Lower Duwamish Waterway found counts of fecal coliform bacteria decreased by 72 percent in 6.5 hours when placed in open‐ mouthed bags suspended near the 16th Avenue South Bridge (Haushild and Prych, 1976). Likewise, in Florida, Anderson et al. (2005) found that 98.5 percent of the fecal coliforms taken from wastewater samples were dead after one day in salt water, whereas it took over two weeks for concentrations to drop that low when exposed to fresh water. These data also help explain how the most saline site in the East Waterway can have the lowest concentrations of fecal coliform bacteria even though the largest CSO volumes in the waterways are currently discharged from the Lander St CSO in the East Waterway.

Figure 3-5. Comaprison of fecal coliform baceria concentrations in paired samples collected from the upper and lower depths at three sites in the Duwamish Estuary (2004– 2013). The mean salinity (PSU) when samples were collected is noted in parentheses.

King County 3‐12 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Discussion Fecal coliform bacteria concentrations have decreased but remain an issue in the Green‐ Duwamish area. CSO control may help reduce concentrations and the frequency of exceedances of water quality criteria in the Duwamish Estuary, but additional reductions in the estuary and upstream of the estuary will likely be needed to improve conditions sufficiently to meet the criteria.

The decline in concentrations over time has likely resulted from a variety of changes in the watershed. The similar rates of decline at sites both at and upstream of CSO outfalls indicate long‐term reductions in inputs throughout the lower 12 miles of the system. For sites downstream of CSOs, reductions may be due to changes in volumes of CSOs. Other explanations are needed to understand patterns at the upstream sites. Factors to be considered may include improvements to sewer and stormwater infrastructure, conversion of septic systems to sewer systems, changes in agricultural practices, and reduction in the abundances or changes in the distributions of wildlife populations.

The sources of bacteria into these systems must be determined to adequately address their abatement. Tracers, which may include pharmaceuticals, personal care products, and artificial sweeteners, might be used to determine if sources of fecal contamination are sewage related or from other sources such as dogs or waterfowl. The presence and concentration of tracers in various waterbodies could be used to prioritize CSO control and would be a useful post‐construction monitoring tool that would allow King County to document the reduction of sewage in receiving waters.

3.4 Physical Parameters

This section presents water quality data for temperature, salinity, conductivity, DO, turbidity, total suspended solids, pH, and alkalinity in the Green‐Duwamish area. These physical parameters are measured as part of the King County and Ecology routine monitoring programs. Some sites may not have recent data for all eight of these parameters.

Temperature Water temperature in rivers is important for metabolic and chemical activity. Excessive water temperature can impair biota. Water temperature is largely influenced by the absorption of solar radiation, although thermal pollution from surface runoff and CSOs can also affect a river’s temperature.

The Green‐Duwamish area serves as an important migration corridor and spawning and rearing habitat for several salmon species, including Puget Sound Chinook, dolly varden/bull trout, coho, chum, pink, sockeye, steelhead/rainbow, and cutthroat trout. These species need cold water for optimum health during various life stages.

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Ecology has implemented a temperature total maximum daily load (TMDL) for the Green River from RM 12.4 in Tukwila to RM 64.5 at the Howard A. Hanson Dam. The river’s temperatures typically exceed the water quality criterion in the summer when precipitation is low and solar irradiance is high. Ecology noted in its TMDL report that shade deficiency is the major factor causing elevated water temperatures in the Green River (not enough trees shading the river from solar radiation) (Ecology, 2011). Another factor is the higher temperatures of tributaries flowing into the river. Newaukum and Soos creeks, major tributaries of the Green River, also have temperature TMDLs. Current Conditions Over the past five years (2009–2013), nine sites in the Duwamish Estuary and Green River were sampled monthly for temperature. LDW‐3.0 was sampled in 2009 and 2010 only; the lower depth at this site was not sampled. No sites were sampled in the Duwamish River during this period. The temperature data for these sites are presented in Table 3‐7.

Table 3-7. Water temperatures (°C) in the Duwmaish Estuary and Green River (2009–2013). Number Site Depth of Mean Median Minimum Maximum Samples Upper 60 10.51 10.43 7.48 14.74 EW Lower 60 10.18 10.13 7.52 12.72 Upper 60 10.44 10.17 5.78 15.63 WW-a Lower 60 10.30 10.25 7.46 12.9 LDW-3.0a Upper 23 11.44 11.4 3.8 20.4 Upper 60 10.32 10.45 4.44 16.76 LDW-3.3 Lower 60 10.42 10.26 6.73 16.58 LDW-4.8 Upper 56 11.05 10.66 3.6 19.5 GR-11.1 Upper 60 10.37 9.69 2.38 20.54 GR-11.6 Upper 57 10.50 9.30 2.80 20.10 GR-40.6 Upper 60 9.07 8.20 1.29 17.81 GR-56.9 Upper 56 8.28 7.45 2.20 15.80 a Sampled in 2009 and 2010 only.

Figure 3‐6 shows the range of surface water (0–1 m) temperatures from 2009 through 2013 for each site. Annual and seasonal findings were as follows:  In the winter, temperatures increase moving downstream (Figure 3‐7). A clear pattern is not visible in summer (Figure 3‐8).  In the summer, temperatures in the Lower Duwamish Waterway and Green River (sites LDW‐3.0, LDW‐4.8, GR‐11.1, and GR‐11.6) were statistically greater than at the mouth of the system and the sites farther upstream (sites EW, WW‐a, GR‐40.6, and GR‐56.9).  In the fall, temperatures were not statistically different between sites, except that temperatures at site GR‐56.9 were significantly lower than temperatures in the East Waterway.

King County 3‐14 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-6. Ranges of annual surface water (0–1 m) temperatures at sites in the Duwamish Estuary and Green River (2009–2013).

Figure 3-7. Ranges of winter surface water (0–1 m) temperatures at sites in the Duwamish Estuary and Green River (2009–2013).

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Figure 3-8. Ranges of summer surface water (0–1 m) temperatures at sites in the Duwamish Estuary and Green River (2009–2013). In general, temperatures at all sites peak in August and are at their lowest in December and January, coinciding with general climate conditions. (See “Comparison to Criteria” below for the monthly ranges of temperatures over the course of the year.)

Time‐depth isoplaths, denoting temperature regimes throughout the water column over the course of the year, are presented in Figures 3‐9 and 3‐10 for sites WW‐a and LDW‐3.3 in the Duwamish Estuary. Generally, temperatures are consistent throughout the water profile. During the summer, however, surface temperatures are 1 to 2°C greater than at lower depths. In the late fall and winter, the surface temperature is cooler than at lower depths by approximately 2°C, which indicates the presence of a cool freshwater lens on top of a warmer saltwater wedge.

King County 3‐16 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-9. Time-depth isopleths of median monthly temperatures at site WW-a in the West Waterway (2009–2013).

Figure 3-10. Time-depth isopleths of median monthly temperatures at site LDW-3.3 in the Lower Duwamish Waterway (2009–2013). Comparison to Criteria The Green‐Duwamish area is included in Ecology’s 2012 303(d) list of impaired waters for temperature (http://www.ecy.wa.gov/programs/wq/303d/index.html).

In 2003, Washington State water quality criteria were substantially restructured from the 1997 class‐based systems to a use‐based system. Use designations are based on a variety of beneficial uses and include aquatic life, recreational, water supply, and miscellaneous uses.

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Table 3‐8 presents the use designations, sampling sites, temperature and DO criteria, and applicable time period for reaches in the Green‐Duwamish area. (DO criteria are discussed later in this chapter.)

Table 3-8. Temperature and dissolved oxygen criteria for the Green-Duwamish area. Begin End Sampling 7- DO 1-Day Use Time Reach River River Sites in DADMax Minimum Designation Periodb Mile Mile Reach (°C)a (mg/L) Duwamish – – EW Salmon/trout 17.5 6.5 Year- Estuary: WW-a rearing and round confluence with WW-b migration Elliott Bay to the only Upper Turning 0 4.8 LDW-0.1 Basin LDW-3.0 LDW-3.3 LDW-4.8

Duwamish 4.8 9.8 DR-6.3 River: mouth to DR-9.8 Black River Lower Green 9.8 22.8 GR-11.1 Salmonid 17.5 8.0 Year- River: Black GR-11.6 spawning, round River to Mill rearing, and Creek migration Lower-Middle 22.8 42.0 GR-32.8 Summer 16 9.5 June 15– Green River: GR-40.6 core Sept. 15 Mill Creek to GR-42.0 salmon/trout Flaming Geyser rearing and State Park migration Spawning & 13 NA Sept. 15 Incubation July 1

Upper-Middle 42.0 57.9 GR-56.9 Summer 16 9.5 June 15– Green River: core Sept. 15 Flaming Geyser salmon/trout State Park to rearing and RM 57.9 migration Spawning & 13 NA Sept. 15– Incubation July 1 Upper-Middle 57.9 63.1 GR-63.1 Summer 16 9.5 June 15– Green River: core Sept. 15 RM 57.9 to salmon/trout Howard A. rearing & Hanson Dam migration a Seven-day average of the daily maximum temperature. b In cases where two times periods overlap, the lower temperature criterion is used. DO = dissolved oxygen.

It is not possible to calculate the seven‐day average of the daily maximum temperature (7‐DADMax) because sites are sampled monthly. Instead, the range of monthly temperatures is shown for sampling sites in the Duwamish Estuary, Lower Green River, Lower‐Middle Green River, and Upper‐Middle Green River (Figures 3‐11, 3‐12, 3‐13, and

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3‐14) to indicate whether temperatures have likely exceeded the applicable temperature criteria (shown as red lines on these figures). (No recent data are available for the uppermost sampling location on the Green River at site GR‐63.1.)

Figure 3-11. Range of monthly surface water (0–1 m) temperatures at sites EW, WW-a, LDW-3.3, and LDW-4.8 in the Duwamish Estuary (2009–2013). Ecology’s 7-DADMax criterion for salmon/trout rearing and migration is shown in red.

Figure 3-12. Range of monthly temperatures at sites GR-11.1 and GR-11.6 in the Lower Green River (2009–2013). Ecology’s 7-DADMax criterion for salmon/trout rearing and migration is shown in red.

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Figure 3-13. Range of monthly temperatures at sites GR-32.8, GR-40.6, and GR-42.0 in the Lower-Middle Green River (2009–2013). Ecology’s 7-DADMax criteria for salmon/trout rearing and migration (July 2–September 14) and for spawning and incubation (September 15–July 1) are shown in red.

Figure 3-14. Range of monthly temperatures at site GR-56.9 in the Middle-Upper Green River (2009–2013). Ecology’s 7-DADMax criteria for salmon/trout rearing and migration (July 2–September 14) and for spawning and incubation (September 15–July 1) are shown in red.

In 2001, Ecology starting taking continuous temperature measurements at site GR‐56.9 at 30‐mintute intervals in the summer, from June or July through September. Starting in summer 2011, continuous data are collected year‐round.

Figure 3‐15 presents the 7‐DADMax for continuous temperature data from site GR‐56.9. These data are better suited for comparison to the water quality criteria for temperature

King County 3‐20 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary than are the grab samples presented in the previous figures. A significant constraint on the ability to compare the discrete samples to the criteria is that the sample will likely underestimate the maximum daily temperature because of the variation in temperature throughout the day.

Figure 3-15. Continuous 7-DADMax temperature at site GR-56.9 in the Upper-Middle Green River (2009–2013). Ecology’s 7-DADMax criteria for summer core salmon/trout rearing and migration (July 2–September 14) and for spawning and incubation (September 15–July 1) are shown in red. (Source: Ecology, unpublished data).

Monthly data indicate that the Lower Green River and Lower‐Middle Green River are more likely than the Duwamish Estuary and the Upper‐Middle Green River to exceed temperature criteria for salmonids. Continuous temperature monitoring at site GR‐56.9 in the Upper‐Middle Green River, however, indicates that this area may pose a threat to salmonids The Duwamish Estuary remains relatively cool because of the influence of Puget Sound waters, although temperatures at sites LDW‐3.0, LDW‐3.3, and LDW‐4.8 do exceed criteria in summer months.

In general, a comparison of 2009 through 2013 temperatures in segments of the Green‐ Duwamish area with water quality criteria for temperature found the following:  Duwamish Estuary. Temperatures in 5 of the 66 samples collected in July, August, and September were greater than 17.5°C. Four of the five samples were collected at site LDW‐4.8. Exceedances occurred in four of the five years sampled. While surface temperatures in the Duwamish Estuary may exceed the criteria, temperatures at depth remain cooler (see Figures 3‐9 and 3‐10) and may provide a refuge for migrating salmonids.  Lower Green River. Of the 27 samples collected in July, August, and September, 9 had temperatures greater than 17.5°C. Exceedances occurred in all five years.

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 Lower‐Middle Green River. Temperatures exceeded the criterion of 13°C in the month of October in three of the five years sampled. Summer temperatures exceeded the criterion of 16°C in August and once in September in three of the five years sampled.  Upper‐Middle Green River at site GR‐56.9. Continuous temperature data showed that exceedances of the core summer habitat criterion of 16°C occurred commonly (Table 3‐9). Summer water temperatures reached and remained high, at levels that may stress salmonids. Exceedances of the spawning and incubation criterion of 13°C occurred regularly in September and October and less commonly in June (Table 3‐ 10). From November to May, no 7‐DADMax values greater than 13°C were recorded in the years when water temperatures were measured during times of the year in addition to the summer (2011, 2012, and 2013). In October, water temperatures dropped to below 10°C, where they remained until May or June of the following year.

Table 3-9. Exceedances of June 15–September 15 core rearing and migration temperature criterion (16 °C) at site GR-56.9 in the Upper-Middle Green River (2009–2013). Days Measured Days in Year Collection Period (June 15–Sept. 15) Exceedance 2009 83 57 June 25—September 24 2010 77 18 July 1—September 29 2011 73 23 July 5—December 31 2012 93 40 Year round 2013 93 58 Year round

Table 3-10. Exceedances of September 15–July 1 spawning and incubation temperature criterion (13°C) at site GR-56.9 in the Upper-Middle Green River (2009–2013). Days Measured Days in Year Collection Period (Sept. 15–July 1) Exceedance 2009 17 16 June 25—September 24 2010 16 15 July 1—September 29 2011 108 28 July 5—December 31 2012 291 33 Year round 2013 290 22 Year round Long-term Trends A multivariate regression equation was used for determining long‐term temperature trends in the Green‐Duwamish area. The sine and cosine functions allow for the seasonality of air temperature and solar angle (Helsel and Hirsh, 1992). The equation is as follows: sin 2 cos 2 12 12 Where: is the monthly average temperature is the monthly average cumulative three‐day rainfall before sampling is the intercept are the regression coefficients

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The significance and magnitude of the statistic were used to determine the trend. The regression was corrected for autocorrelation.

Long‐term temperature trends, shown in Table 3‐11, are as follows:  Significant increasing trends were detected from 1970 through 2004 for both the upper and lower depths at site WW‐b. The rates of increase were 0.0267 and 0.0317°C per year at the upper and lower depths, respectively. These rates are similar to the increasing trend of 0.0267°C per year observed from 1981 through 2010 at the Elliott Bay beach monitoring site north of the East Waterway (King County, 2017).  A significant decreasing trend of 0.0944°C per year was detected from 1998 through 2013 at the lower depth of site LDW‐3.3. This is similar to trends found in Elliott Bay during the same time period. These trends may reflect the “global warming hiatus” observed from 1997 through 2013 (Tollefson, 2014). A more robust data set of 20 years or more would be needed to reliably assess temperature trends and the global warming hiatus.

Table 3-11. Long-term trends for temperature in the Green-Duwamish area (1970–2013). Years Slope Site Depth Direction Significance p-value Evaluated (°C/year) Upper 1996–2013 -- n.s. 0.901 –0.003 EW Lower 1996–2013 -- n.s. 0.739 –0.006 Upper 1970–2004 ↑ *** 0.001 0.027 WW-b Lower 1970–2004 ↑ *** < 0.001 0.032 Upper 1970–2013 -- n.s. 0.605 –0.005 LDW-3.3 Lower 1998–2013 ↓ *** < 0.001 –0.094 DR-6.3 Upper 1972–2008 -- n.s. 0.111 0.015 GR-11.1 Upper 1970–2013 -- n.s. 0.301 0.008 GR-11.6 Upper 1970–2013 -- n.s. 0.186 0.010 GR-32.8 Upper 1976–2008 -- n.s. 0.417 –0.009 GR-40.6 Upper 1976–2012 -- n.s. 0.250 –0.011 GR-56.9 Upper 1975–2013 -- n.s. 0.211 –0.012 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

Dissolved Oxygen In the Duwamish‐Green area, DO is a function of temperature, primary productivity of aquatic plants and phytoplankton, physical turbulence, and biochemical oxygen demand. Of these factors, temperature plays the primary role in determining DO concentrations because cool water holds more oxygen than warm water.

The instability of the surface water layer caused by the discharge and tidal influences inherent of the Duwamish Estuary and the Duwamish and Green rivers discourages the accumulation of phytoplankton and resulting blooms. Blooms were observed in the Duwamish Estuary upstream at about RM 6 in August in the late 1960s during periods of low discharge and low tidal variability (Welch, 1969). It is not possible to determine whether late summer phytoplankton blooms have continued because chlorophyll a is not

King County 3‐23 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary measured in the Green‐Duwamish area. No blooms have been observed in the estuary in recent years (Budka, personal communication, 2014).

Blooms would result in increased DO concentrations at the surface but decreased concentrations deeper in the water column as decaying phytoplankton are oxidized. The blooms in the 1960s and the hypoxia at depth observed in the 1970s were likely influenced by treated effluent discharged from the South Treatment Plant before the effluent was rerouted to Puget Sound in the late 1980s (Ecology, 1992).

Because of the incongruence of DO measurements taken in the field using the Seabird CTD sampler and those in the laboratory using the Winkler method, field DO measurements were used to characterize current conditions and laboratory DO measurements were used for assessing long‐term trends. Current Conditions From 2009 through 2013, nine sites in the Duwamish Estuary and Green River were sampled monthly for DO (Table 3‐12). LDW‐3.0 was not included in the analysis because it was sampled in 2009 and 2010 only. Two of the sites, GR‐11.6 and GR‐56.9, were sampled using the Winkler method only.

Table 3-12. Concentrations of dissolved oxygen (mg/L) in the Duwamish Estuary and Green River (2009–2013). Number of Site Depth Mean Median Minimum Maximum Samples Upper 60 7.66 7.60 5.3 10.8 EW Lower 60 7.31 7.55 5.3 9.3 Upper 60 7.89 7.85 4.9 11.1 WW-a Lower 60 7.53 7.70 5.3 10.0 Upper 58 7.22 6.70 3.6 11.6 LDW-3.3 Lower 58 6.56 6.75 4.7 9.9 LDW-4.8 Upper 54 9.59 9.85 6.3 12.2 GR-11.1 Upper 60 9.45 10.3 6.7 12.5 GR-11.6a Upper 57 10.6 10.9 7.4 13.1 GR-40.6 Upper 61 11.6 11.6 9.5 14.3 GR-56.9a Upper 54 11.7 12.0 9.5 13.4 a Winkler titration method. Measurements at all other sites were taken in the field.

DO measurements taken at the surface (0–1 m) from 2009 through 2013 show that concentrations generally increase moving upstream (Figure 3‐16). Similar spatial trends were observed for individual seasons. Cooler upstream temperatures and more turbulent flow may facilitate the ability of oxygen to dissolve in the water. In addition, the presence of more organic material in the downstream reaches may decrease levels of DO as the material degrades and consumes oxygen in the process.

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Figure 3-16. Ranges of surface water (0–1 m) dissoved oxygen concentrations in the Duwamish Estuary and Green River (2009–2013). Median DO concentrations from 2009 through 2013 for sites WW‐a and LDW‐3.3 in the Duwamish Estuary were used to denote DO regimes throughout the water column over the course of a year (Figures 3‐17 and 3‐18). DO concentrations are typically greatest at the surface and in the winter and early spring, coinciding with increased freshwater flow and lower water temperatures. In September and October, deep water upwelled from the Pacific Ocean enters Puget Sound and Elliott Bay and forces de‐stratification and the release of colder, less‐oxygenated deep water to the surface. This effect is seen in the Duwamish Estuary where DO concentrations reach a mimimum beneath the surface in late summer and fall.

The DO concentrations in the Duwamish Estuary saltwater wedge do not reach the minimum concentrations found by Welch (1969), which were caused by surface phytoplankton blooms. Welch observed concentrations between 3 mg/L and 4 mg/L in August and September at 1 m above the river bottom. From 2009 through 2013, DO values near the river bottom were 5.5 mg/L and above. This suggests that phytoplankton blooms did not occur at the same magnitude observed in the late 1960s.

King County 3‐25 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-17. Time-depth isopleths of median dissoved oxygen concentrations at site WW-a in the West Waterway (2009–2013).

Figure 3-18. Time-depth isopleths of median dissoved oxygen concentrations at site LDW-3.3 in the Lower Duwmaish Waterway (2009–2013). The Lower, Lower‐Middle, and Upper‐Middle Green River sites show similar monthly patterns in DO as in the Duwamish Estuary, peaking in winter and reaching a minimum in

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the summer (Figures 3‐19, 3‐20, and 3‐21). However, the fall, winter, and spring concentrations in the Duwamish Estuary are much more variable than during the same seasons in the other reaches of the system (Figure 3‐22). This variability is likely influenced by whether the saltwater wedge or the freshwater lens was sampled. As seen in Figures 3‐17 and 3‐18, DO may drop substantially over small changes in depth near the surface. Salinity and DO at the surface in the Duwamish Estuary are significantly negatively correllated (Pearson’s correllation coefficient = ‐0.4537, p < 0.0001).

Figure 3-19. Ranges of monthly dissolved oxygen concentrations at sites GR-11.1 and GR-11.6 in the Lower Green River (2009–2013). The red line shows Ecology’s minimum daily criterion.

Figure 3-20. Ranges of monthly dissolved oxygen concentrations at sites GR-32.8, GR-40.6, and GR-42.0 in the Lower-Middle Green River (2009–2013). The red line shows Ecology’s minimum daily criterion.

King County 3‐27 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-21. Ranges of monthly dissolved oxygen concentrations at site GR-56.9 in the Upper- Middle Green River (2009–2013). The red line shows Ecology’s minimum daily criterion.

Figure 3-22. Ranges of monthly dissolved oxygen concentrations at sites EW, WW-a, LDW-3.3, and LDW-4.8 in the Duwamish Estuary (2009–2013). The red line shows Ecology’s minimum daily criterion. Comparison to Criteria Ecology has assigned criteria for DO levels in waterbodies for the protection and preservation of salmonids. The criteria for segments of the Green‐Duwamish area are presented in Table 3‐8, shown earlier in the temperature discussion. Each criterion is the minimum DO concentration over the course of the day; however, it is not possible to

King County 3‐28 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary determine the daily minimum DO concentration because DO is not continuously measured at the sampling sites. The discrete samples may overestimate the minimum daily DO concentration at each site because the lowest concentrations occur in the evening hours when productivity is absent.

The Duwamish Estuary, Duwamish River, and Green River appear on Ecology’s 303(d) list for impaired waters because of low DO. Newaukum and Soos creeks, major tributaries to the Green River, also appear on the 303(d) list. To date, no actions have been taken, such as establishing a TMDL, to address the impairments (Ecology, 2011).

Figures 3‐19, 3‐20, 3‐21, and 3‐22 compare the applicable Ecology DO criterion with the monthly range of DO concentrations in 2009–2013 for each reach sampled in the Duwamish Estuary and Green River. The comparison shows the following:  Duwamish Estuary. Concentrations occasionally fell below the minimum DO criterion of 6.5 mg/L during the year, most commonly in late summer and early fall; no violations were observed in April and May. Unlike upstream sites, the Duwamish Estuary was often sampled in the afternoon when phytoplankton productivity has peaked. The DO concentrations observed, therefore, may not represent the daily minimum DO level.  Lower Green River. Concentrations occasionally fell below the minimum DO criterion of 8.0 mg/L in the summer. The criterion was met during the rest of the year.  Lower‐Middle Green River. The summer DO criterion of 9.5 mg/L was met; a minimum concentration of 9.7 mg/L was observed.  Upper‐Middle Green River. During the summer, the criterion of 9.5 mg/L was met; a minimum concentration of 9.5 mg/L was observed. The only site sampled for DO from 2009 through 2013 in this reach was the Ecology site (GR‐56.9). Because the DO samples were taken at 11:00 a.m. or earlier, the concentrations may closely reflect the minimum level reached during the prior night. Long-term Trends DO trend significance and magnitude for the Green‐Duwamish area were calculated using the seasonal Mann‐Kendall test with a three‐day rainfall used as a covariate. Because of the incongruence between concentrations measured using the Winkler method and those collected via a probe, only Winkler DO concentrations were used for trend analysis. Table 3‐13 and Figure 3‐23 present the results of this analysis for each site with sufficient years of data.

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Table 3-13. Long-term trends for dissolved oxygen in the Green-Duwamish area (1975–2013). Years Slope Site Direction Significance p-value Evaluated (mg/L/year) WW-b 1976–2004 ↑ *** 0.039 0.018 LDW-3.3 1976–2012 ‐‐ n.s. 0.532 0.003 DR-6.3 1976–1997 ↑ *** < 0.001 0.056 GR-11.1 1976–1997 ‐‐ n.s. 0.331 0.006 GR-11.6 1976–2013 ↑ *** < 0.001 0.018 GR-32.8 1976–1997 ‐‐ n.s. 0.813 0 GR-40.6 1976–1997 ‐‐ n.s. 0.222 –0.006 GR-56.9 1975–2013 -- n.s. 0.509 0 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

Generally, DO concentrations increased in the Duwamish Estuary, Duwamish River, and Lower Green River sites from the mid‐1970s through 2013. Statistically significant increases were observed at sites WW‐b, DR‐6.3, and GR‐11.6. The lack of a significant trend at site GR‐11.1, just 0.5 river mile downstream of GR‐11.6, is likely because the evaluation period is almost 20 years shorter than at GR‐11.6. No significant or substantial DO trends were seen at the Lower‐Middle and Upper‐Middle Green River sites.

Figure 3-23. Trends in median annual dissolved oxygen concentrations in the Green-Duwamish area (1975─2013).

King County 3‐30 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Salinity Salinity is a measure of the dissolved salt content in water; it impacts chemistry, density, and the biological processes in the water. The typical salinity of seawater and fresh water are 35 ppt and 0–0.5 ppt, respectively.

Dense salt water from Elliott Bay enters the Duwamish Estuary and travels upstream. The cross‐channel salinity distribution in the estuary is generally uniform for a given location and depth (Parametrix, 1999). The upstream extent of the saltwater wedge depends on freshwater inflow and tide height. However, flows greater than 1,000 cfs will prevent intrusion of the wedge beyond RM 7.9 (12.7 river km) regardless of tide height. At a freshwater inflow of less than 600 cfs and at tide heights greater than 10 feet above MLLW, the saltwater wedge will extend upstream approximately to RM 10 (16.1 river km). Figures 3‐24 and 3‐25 depict the saltwater wedge during various tidal and freshwater flow conditions (Dawson and Tilley, 1972).

Dye studies indicate that downward vertical mixing over the length of the saltwater wedge rarely occurs (Santos and Stoner, 1972; King County & Parametrix, 1999). As the overriding upper layer erodes the surface of the saltwater wedge, the wedge contributes salt to the river water above but is not significantly diluted in return (Dawson and Tilley, 1972). During low river flow, the vertical salinity gradient is diffuse and a higher concentration of salt is present in the upper layer of water in the estuary.

Laboratory salinity measurements were used to characterize current conditions because of the incongruence of salinity measurements taken in the field using the Seabird CTD and in measurements taken in the laboratory using the Electric Conductivity method (SM2520‐B). The laboratory method detection limit was 2 ppt. There were insufficient data to perform long‐term trend analysis for salinity.

King County 3‐31 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

a

b

Figure 3-24. Saltwater wedge variation between tides in the Duwamish Estuary. The wedge reaches substantially farther upstream during high tide (a) than low tide (b). Freshwater inflow: 300–400 m3/min (180–235 cfs). (Source: Dawson and Tilley, 1972.)

Figure 3-25. Saltwater wedge in the Duwamish Estuary during high freshwater inflow of 8,870 m3/min (5,200 cfs). (Source: Dawson and Tilley, 1972.)

King County 3‐32 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Current Conditions From 2009 through 2013, five sites in the Duwamish Estuary were monitored for salinity: EW, WW‐a, LDW‐3.0, LDW‐3.3, and LDW‐4.8. LDW‐3.0 was monitored in 2009 and 2010 only. Table 3‐14 presents salinity values for these sites.

Table 3-14. Salinity values (ppt) in the Duwamish Estuary (2009–2013). Number Site Depth of Mean Median Minimum Maximum Samples Upper 60 27.6 28.1 17.2 30.0 EW Lower 60 29.4 29.3 28.3 30.6 Upper 60 19.2 20.0 4.6 29.8 WW-a Lower 60 28.8 29.1 23.8 30.4 LDW-3.0a Upper 24 3.8 2.4 < 2 16.5 Upper 60 10.4 8.0 < 2 28.1 LDW-3.3 Lower 60 22.2 27.1 < 2 29.6 LDW-4.8 Upper 72 4.33 < 2 < 2 29.6 a Sampled in 2009 and 2010 only.

Surface water (0–1 m) salinity at each site was found to be significantly distinguishable from the salinity at other sites except for sites LDW‐3.0 and LDW‐4.8, which were statistically indistinguishable (Figure 3‐26). Salinity decreased moving upstream. Findings are as follows:  In the East Waterway (site EW), salinity closely resembled that of Elliott Bay.  In the south end of the West Waterway (site WW‐a), the influence of incoming fresh water and the tides is clearly evident in the variation in salinity.  Variability is even higher at site LDW‐3.3 in the Lower Duwamish Waterway, although most salinity values are lower than at site WW‐a.  Values at site LDW‐3.0 are significantly lower than the values at site LDW‐3.3 upstream and similar to the values at site LDW‐4.8 even farther upstream. This anomaly is likely because site LDW‐3.0 is located along the beach at the Duwamish Waterway Park and samples were taken from the very surface of the water.  Salinity at site LDW‐4.8 may sometimes reach values comparable to site LDW‐3.3 downstream, but most of the time the values are lower.

King County 3‐33 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-26. Ranges of surface water (0–1 m) salinity at sites in the Duwamish Estuary (2009– 2013). Monthly salinity profile data collected at sites WW‐a and LDW‐3.3 in the Duwamish Estuary were used to construct time‐depth isopleths denoting salinty regimes throughout the water column over the course of the year (Figures 3‐27 and 3‐28). Only data from 2011 through 2013 were used because of maintenance and calibration issues with the Seabird CTD in 2009 and 2010. Surface salinity concentrations are lowest in the the winter and spring, coinciding with increased freshwater flow. Surface salinity increases in the summer during low‐flow conditions. With the upwelling in September and October, the colder, less‐ oxygenated, higher salinity deep water reaches the surface of Elliott Bay. These waters are seen in the Duwamish Estuary in late summer and fall when salinity increases at depth beneath the freshwater lens.

King County 3‐34 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-27. Time-depth isopleths of median salinty for entire water column at site WW-a in the West Waterway (2011–2013).

Figure 3-28. Time-depth isopleths of median salinty for entire water column at site LDW-3.3 in the Lower Duwamish Waterway (2011–2013).

Conductivity Specific conductance (conductivity) is a measure of the capacity of water to conduct an electric current standardized at 25°C, which allows for comparison of waters with different temperatures. Temperature and the concentration of major dissolved ions in water determine conductivity.

King County 3‐35 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Current Conditions In 2009 through 2013, conductivity was measured in the field using a Hydrolab® sonde at four sites in the Green River. Table 3‐15 presents the mean, median, and range of conductivity at these four sites.

Table 3-15. Conductivity (µS/cm) values at four sites in the Green River (2009–2013). Number Site of Mean Median Minimum Maximum Samples GR-11.1 60 94.4 88.0 38.6 194 GR-11.6 57 97.9 92.0 44.0 189 GR-40.6 61 53.3 50.8 32.8 103 GR-56.9 56 43.2 43.5 30.0 60

Figure 3‐29 presents the ranges of surface water (0–1 m) conductivity at the monitored sites. Conductivity appears to decrease moving upstream. Values at sites GR‐11.1 and GR‐11.6 were not statistically distinguishable. Both sites were statistically greater than upstream sites GR‐40.6 and GR‐56.9. Values at site GR‐40.6 were significantly greater than at site GR‐56.9.

Figure 3-29. Ranges of surface water (0–1 m) conductivity at four sites in the Green River (2009–2013). Figures 3‐30, 3‐31, and 3‐32 present monthly 2009–2013 conductivity values measured at sites GR‐11.1 and GR‐11.6 (combined), GR‐40.6, and GR‐56.9. (The scale for the y‐axis of

King County 3‐36 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3‐30 is roughly double that of Figures 3‐31 and 3‐32.) Conductivity peaks in the summer during low flows, which suggests a diluting effect throughout the rest of the year.

Figure 3-30. Ranges of monthly conductivity values at sites GR-11.1 and GR-11.6 in the Lower Green River (2009–2013).

Figure 3-31. Ranges of monthly conductivity values at site GR-40.6 in the Lower-Middle Green River (2009–2013).

King County 3‐37 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-32. Ranges of monthly conductivity values at site GR-56.9 in the Upper-Middle Green River (2009–2013). Long-term Trends Long‐term trends for conductivity in the Green‐Duwamish area were calculated using the seasonal Mann‐Kendall test, with three‐day rainfall as a covariate. Table 3‐16 presents the results of this analysis. Significant negative trends were detected at all Green River sites except site GR‐32.8 in Auburn. Positive trends were detected in the Duwamish Estuary at sites WW‐b (significant) and LDW‐3.3. Conductivity at these sites is affected by the presence of the saltwater wedge.

Instrument functionality at high salinity may have underestimated conductivity in the 1970s and 1980s. From 1976 to 1985, conductivity appeared to peak at 20,000 µS/cm. At 10°C, this value corresponds to a salinity of approximately 17 ppt, which is well below the maximum salinity value (29.8 ppt) detected at the surface of site WW‐a in 2009–2013. The observed trends for sites WW‐b and LDW‐3.3 therefore are likely biased. From 1987 forward, the apparent direction is negative at these two sites and no significant trends are found.

King County 3‐38 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-16. Long-term conductivity trends in the Green-Duwamish area (1975–2013). Years Slope Site Direction Significance p-value Evaluated (µS/cm/year) 1976–2003 ↑ *** 0.063 165 WW-ba 1987–2003 -- n.s. 0.947 0 1976–2005 -- n.s. 0.490 21.4 LDW-3.3a 1987–2005 -- n.s. 0.113 –103 DR-6.3 1976–2008 ↓ *** 0.028 –0.958 GR-11.1 1976–2013 ↓ *** 0.001 –0.675 GR-11.6 1976–2013 ↓ *** 0.099 –0.250 GR-32.8 1976–2008 -- n.s. 0.179 –0.117 GR-40.6 1976–2013 ↓ *** 0.004 –0.188 GR-56.9 1975–2013 ↓ *** 0.002 –0.194 *** = significant (p < 0.10); n.s. = not significant (p > 0.10). a The 1976–1985 high conductivity values were underestimated, resulting in a negative skew.

pH pH is the –log10 transformation of the activity of hydrogen ions in solution. pH values less than 7 are acidic; values greater than 7 are basic. pH influences the chemical state of metals and other constituents. Some organisms may have a narrow range of optimal pH and may be negatively impacted at high and low pH values. Current Conditions pH was sampled monthly in the Duwamish Estuary and Green River from 2009 through 2013. It was measured in the field using a Hydrolab sonde at the freshwater sites and a Seabird CTD at the marine sites. Sites EW, WW‐a, and LDW‐3.3 were sampled in 2011 only. Values at site LDW‐4.8 are not representative of annual pH. The site was sampled in July– December 2011 and in July–August and December 2012 only. Sampling was done on multiple days during these periods. pH values are shown in Table 3‐17. Measured pH values were transformed into hydrogen activity values to calculate mean and median values, which were then back‐transformed to pH (APHA‐AWWA‐WEF and Eaton, 2005) In general, the Duwamish Estuary is slightly basic, with values above 7 and below 8. Minimum values at site LDW‐4.8 and all Green River sites and the mean value at site GR‐11.1 indicate acidic conditions.

Table 3-17. pH values in the Duwamish Estuary and Green River (2009–2013). Number Site Depth of Mean Median Minimum Maximum Samples Upper 12 7.62 7.70 7.40 7.80 EWa Lower 12 7.59 7.60 7.40 7.80 Upper 11 7.62 7.60 7.40 7.90 WW-aa Lower 12 7.61 7.65 7.40 7.80 Upper 11 7.50 7.50 7.30 7.80 LDW-3.3a Lower 12 7.25 7.30 7.00 7.70 LDW-4.8b Upper 16 7.09 7.14 6.58 7.27 GR-11.1 Upper 60 6.91 7.00 6.26 7.53 GR-11.6 Upper 56 7.18 7.18 6.93 7.42

King County 3‐39 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Number Site Depth of Mean Median Minimum Maximum Samples GR-40.6 Upper 61 7.42 7.45 6.97 8.06 GR-56.9 Upper 54 7.32 7.35 6.91 7.90 a Sampled in 2011 only (monthly). b Sampled only in July and December 2011 and in July–August and December 2012.

Figure 3‐33 shows the annual range of surface water (0–1 m) pH values for 2009–2013 at monitored sites. The data show the following:  Lower Green River sites are more acidic than upstream and downstream sites.  No annual temporal trend in pH is evident in the lower reaches of the system.  In the Lower‐Middle and Upper‐Middle Green River, pH values appear to increase over the spring. They peak at above 7.5 in the summer and then quickly decrease to less than 7.5 in the fall relative to the rate of increase in the spring.  The seasonal variation of pH suggests a dilution effect, where pH is lower during high‐flow periods when freshwater influence is greatest. During low‐flow periods when input is dominated by alkaline groundwater and/or marine waters and when phytoplankton populations are consuming dissolved CO2 (H2CO3), pH increases as acid is neutralized or removed.7

Figure 3-33. Ranges of annual surface water (0–1 m) pH at sites in the Duwamish Estuary and Green River (2009–2013). Sites EW, WW-a, and LDW-3.3 were sampled in 2011 only.

7 CO2 = carbon dioxide; H2CO3 = carbonic acid.

King County 3‐40 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Comparison to Criteria Ecology has established pH criteria for aquatic life in the Green‐Duwamish area. pH should be within a range of 6.5 to 8.5 during salmon use all year from the mouth of the system to RM 22.8 and in the summer from RM 22.8 to RM 63.1.

Figures 3‐34, 3‐35, 3‐36, and 3‐37 present the monthly ranges of pH for sampling sites in the Duwamish Estuary, Lower Green River, Lower‐Middle Green River, and Upper‐Middle Green River. The Ecology pH criterion range, shown with red lines in each figure, was exceeded only in the Lower Green River (Figure 3‐35). The two violations occurred at site GR‐11.1 in March 2010 (pH value of 6.42) and in January 2011 (pH value of 6.26).

Figure 3-34. Ranges of monthly pH in the Duwamish Estuary (2011–2012). Ecology’s criterion range is shown between the red lines.

King County 3‐41 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-35. Ranges of monthly pH at Lower Green River sites GR-11.1 and GR-11.6 (2009– 2013). Ecology’s criterion range is shown between the red lines.

Figure 3-36. Ranges of monthly pH at Lower-Middle Green River sites GR-32.8, GR-40.6, and GR-42.0 (2009–2013). Ecology’s criterion range is shown between the red lines.

King County 3‐42 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-37. Ranges of monthly pH at Upper-Middle Green River site GR-56.9 (2009–2013). Ecology’s criterion range is shown between the red lines. Long-term Trends pH trend significance and magnitude for the Green‐Duwamish area were calculated using the seasonal Mann‐Kendall test with three‐day rainfall as a covariate (Table 3‐18). Findings were as follows:  In general, pH has increased since 1976 and waters have become more basic.  Significant upward trends were observed at sites WW‐b, LDW‐3.3, GR‐11.6, and GR‐ 56.9 in the Duwamish Estuary.  Slight increasing trends were detected at sites DR‐6.3 and GR‐11.6 in the Duwamish River and Lower Green River; the trend was not significant at DR‐6.3. Nearby site GR‐11.1 did not reveal a similar trend.  No significant trends were detected in the Lower‐Middle Green River at sites GR‐ 32.8 and GR‐40.6.

King County 3‐43 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-18. Long-term pH trends in the Green-Duwamish area (1975–2013). Years Slope Site Direction Significance p-value Evaluated (units/year) WW-b 1976–2003 ↑ *** < 0.001 0.019 LDW-3.3 1976–2003 ↑ *** < 0.001 0.014 DR-6.3 1976–2008 -- n.s. 0.134 0.003 GR-11.1 1976–2013 -- n.s. 0.272 –0.002 GR-11.6 1976–2013 ↑ *** 0.008 0.004 GR-32.8 1976–2008 -- n.s. 0.829 0 GR-40.6 1976–2013 -- n.s. 0.871 0 GR-56.9 1975–2013 ↑ *** 0.077 0.004 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

Alkalinity Total alkalinity, also known as acid neutralizing capacity (ANC), is a measure of the ability a body of water to resist a decrease in pH by the addition of an acid (buffering capacity). Alkalinity is reported as mg CaCO3/L because of the importance of bicarbonate concentrations in freshwater systems. Current Conditions Site GR‐11.1 in the Lower Green River and site GR‐40.6 in the Middle‐Lower Green River were tested monthly for alkalinity from 2009 through 2013 (Table 3‐19). Alkalinity at site GR‐11.1 was significantly and substantially greater than at site GR‐40.6 (Wilcoxon rank sum test p‐value < 0.0001).

Table 3-19. Alkalinity (mg CaCO3/L) in the Lower and Middle-Lower Green River (2009–2013). Number of Site Depth Mean Median Minimum Maximum Samples GR-11.1 Upper 61 34.2 33.2 14.6 58.0 GR-40.6 Upper 61 22.3 21.5 10.3 31.8

Figure 3‐38 shows the monthly range of alkalinity values at GR‐11.1 and GR‐40.6 for 2009– 2013. Values peak in the summer (> 50 mg CaCO3/L at GR‐11.1 and ~30 mg CaCO3/L at GR‐ 40.6); the increase begins in July. Throughout the rest of the year, values remain relatively stable with the exception of a spike that occurs at both sites in late February and early March 2009, 2010, and 2011. The seasonal variation in alkalinity suggests a dilution effect. Alkalinity values are lower during high‐flow periods. Alkalinity increases during low‐flow periods when input is dominated by alkaline groundwater and when phytoplankton populations are consuming dissolved CO2 (H2CO3).

King County 3‐44 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-38. Ranges of monthly alkalinity at sites GR-11.1 (grey) and GR-40.6 (white) in the Lower and Middle-Lower Green River (2009–2013). Long-term Trends The significance and magnitude of trends in alkalinity for four sites in the Green River were calculated using the seasonal Mann‐Kendall test with three‐day rainfall as a covariate. Four Green River sites allowed for meaningful trend analysis: GR‐11.1, GR‐11.6, GR‐32.8, and GR‐40.6. Monitoring began in 1997 at each site. No substantial or significant trend was detected at any of these sites (Table 3‐20).

Table 3-20. Long-term alkalinity trends in the Green River (1997–2013). Years Slope Site Direction Significance p-value Evaluated (mg CaCO3 /L/year) GR-11.1 1997–2013 -- n.s. 0.341 –0.13 GR-11.6 1997–2008 -- n.s. 0.554 0.06 GR-32.8 1997–2008 -- n.s. 0.817 0.04 GR-40.6 1997–2013 -- n.s. 0.202 –0.10 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

Total Suspended Solids Total suspended solids (TSS) is a measure of the mass of particles greater than 1.5 microns in diameter in a sample of water, usually measured by dry weight after filtration. From 2009 through 2013, MDLs ranged from 0.5 mg/L to 2.5 mg/L. TSS measured by Ecology at sites GR‐11.6 and GR‐56.9 may not be comparable with TSS concentrations at the other sites because of different analytical methods.

King County 3‐45 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Current Conditions From 2009 through 2013, eight sites in the Duwamish Estuary and Green River were monitored monthly for TSS. Table 3‐21 shows the mean, median, and range of concentrations at each site and depth.

Table 3-21. Total suspended solids (mg/L) in the Duwmaish Estuary and Green River (2009– 2013). Number Site Depth of Mean Median Minimum Maximum Samples Upper 59 4.8 3.4 1.0 39.6 EW Lower 60 4.1 2.9 0.5 20.0 Upper 59 6.3 4.1 1.4 86.0 WW-a Lower 60 5.3 3.5 <1.0 18.0 Upper 59 10.2 5.5 2.0 159 LDW-3.3 Lower 59 13.6 8.2 2.3 185 LDW-4.8 Upper 53 11.6 5.9 1.1 116 GR-11.1 Upper 61 10.8 6.7 1.8 82.0 GR-11.6 Upper 57 17.6 10.0 3.0 216 GR-40.6 Upper 61 6.4 2.8 <0.5 59.8 GR-56.9 Upper 56 7.7 2.0 1.0 217

Figure 3‐39 shows the annual range of TSS in surface water (0–1 m) at each monitored site from 2009 through 2013. Observations were as follows:  TSS was greatest at site GR‐11.6.  Mean concentrations at sites EW and WW‐a in the Duwamish Estuary were similar to sites GR‐40.6 and GR‐56.9 far upstream in the Green River.  Concentrations remained elevated from site GR‐11.6 downstream until site LDW‐3.3.  Despite their proximity to each other, site GR‐11.6 had greater TSS concentrations than site GR‐11.1. This discrepancy may be caused by an oxbow located downstream of site GR‐11.6 and upstream of site GR‐11.1. The oxbow may allow the settling of large suspended particles as flow velocities slow moving through the turns. Figure 3‐40 shows the range of monthly TSS values at all monitored sites from 2009 through 2013. TSS is lowest in the summer, coinciding with low flow and low levels of precipitation. Concentrations are highly variable throughout the rest of the year and likely depend on the timing of rain events relative to sampling events. TSS and three‐day rainfall are significantly, positively correlated (Pearson coefficient = 0.3287; p‐value < 0.0001).

King County 3‐46 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-39. Ranges of annual surface water (0–1m) total suspended solids concentrations in the Duwamish Estuary and Green River (2009–2013).

Figure 3-40. Ranges of monthly total suspended solids concentrations in the Duwamish Estuary and Green River (2009–2013). The 95th percentile values for January (61.1 mg/L) and December (109 mg/L) are not shown.

King County 3‐47 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Long-term Trends The significance and magnitude of long‐term TSS trends in the Green‐Duwamish area were calculated using the seasonal Mann‐Kendall test with three‐day rainfall as a covariate. Only King County data for site GR‐11.6 were analyzed because King County and Ecology used different field sampling methodologies.

TSS concentrations in the Green‐Duwamish area have significantly declined since 1976 (Table 3‐22). The greatest decline was detected at site WW‐b, where TSS has decreased at a rate of 0.17 mg/L per year. The smallest decline was at site GR‐56.9 (0.001 mg/L per year).

Table 3-22. Long-term total suspended solids trends in the Green-Duwamish area (1976–2013). Years Slope Site Direction Significance p-value Evaluated (mg/L/year) WW-b 1976–2013 ↓ *** < 0.001 –0.170 LDW-3.3 1976–2013 ↓ *** 0.011 –0.053 DR-6.3 1976–2008 ↓ *** 0.002 –0.129 GR-11.1 1976–2013 ↓ *** 0.016 –0.071 GR-11.6 1976–2008 ↓ *** 0.049 –0.075 GR-32.8 1976–2008 ↓ *** 0.002 –0.053 GR-40.6 1976–2013 ↓ *** 0.013 –0.028 GR-56.9 1978–2013 ↓ *** 0.004 –0.001 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

Turbidity Turbidity is a measure of the cloudiness of water and is quantified by determining the scattering of light by particles in a sample. Particles in turbid water often are not visible to the naked eye and may not be captured by filtration in TSS analysis.

From 2009 through 2013, the MDL for turbidity was 0.2 nephelometric turbidity units (NTUs). Current Conditions From 2009 through 2013, four sites in the Green River were tested monthly for turbidity. Sites GR‐11.1 and GR‐40.6 were not measured between January 2009 and November 2011. Table 3‐23 shows the mean, median, and range of turbidity for the four sites sampled.

Table 3-23. Turbidity values (NTUs) for four sites in the Green River (2009–2013). Number of Site Mean Median Minimum Maximum Samples GR-11.1a 26 7.36 3.52 1.67 71.6 GR-11.6 57 7.98 4.20 1.80 120 GR-40.6a 26 3.31 1.40 0.53 30.4 GR-56.9 56 4.23 1.15 0.50 110 a No measurements were taken between January 2009 and November 2011.

Figure 3‐41 presents the annual range of surface water (0–1 m) turbidity values for each monitored site. Turbidity was significantly greater at the two downstream sites. Figure 3‐

King County 3‐48 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

42 presents the monthly turbidity values at all monitored sites. Values are lowest in the summer, coinciding with low flow and low levels of precipitation. Values are highly variable throughout the rest of the year and likely depend on the timing of rain events relative to sampling events. Turbidity and three‐day rainfall are significantly, positively correlated (Pearson coefficient = 0.5790; p‐value < 0.0001).

Figure 3-41. Ranges of annual surface water (0–1m) turbidity values at four sites in the Green River (2009–2013).

King County 3‐49 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-42. Ranges of monthly turbidity values at four sites in the Green River (2009–2013). The 90th (98.5 NTUs) and 95th (113 NTUs) percentiles for December are not shown. Long-term Trends The significance and magnitude of long‐term trends in turbidity for the Green‐Duwamish area were calculated using the seasonal Mann‐Kendall test with three‐day rainfall as a covariate. The trend for Ecology site GR‐56.9 was evaluated for 1989 through 2013 because of the high MDL of 1 NTU in effect from 1975 through 1988. Using data from this period would have biased the trend. Only King County data from Ecology site GR‐11.6 were analyzed because King County and Ecology used different field sampling methodologies.

Turbidity has significantly declined since 1976 at sites WW‐b, DR‐6.3, GR‐32.8, and GR‐40.6 (Table 3‐24). The greatest decline was detected at DR‐6.3 where TSS has decreased at a rate of 0.033 NTU per year.

Table 3-24. Long-term turbidity trends for the Green-Duwmaish area (1976–2013). Years Slope Site Direction Significance p-value Evaluated (NTU/year) WW-b 1976–2003 ↓ *** 0.031 –0.029 LDW-3.3 1976–2006 -- n.s. 0.035 –0.013 DR-6.3 1976–2008 ↓ *** 0.008 –0.033 GR-11.1 1976–2013 -- n.s. 0.156 –0.020 GR-11.6 1976–2008 -- n.s. 0.347 –0.017 GR-32.8 1976–2008 ↓ *** 0.040 –0.015 GR-40.6 1976–2013 ↓ *** 0.003 –0.019 GR-56.9 1989–2013 -- n.s. 0.236 –0.005 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

King County 3‐50 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

3.5 Nutrients

Nutrient water quality data discussed in this section include nitrate+ nitrite‐N, ammonia, total nitrogen, orthophosphate, and total phosphorus. These nutrients are measured monthly as part of King County’s routine monitoring program in the Green‐Duwamish area. They are currently sampled from one site in the East Waterway, one in the West Waterway, two in the Lower Duwamish Waterway, and two in the mainstem of the Green River. For some marine sites, samples are collected from the upper and lower depths of the water column; most other sites are collected from the upper (0–1 m) depths only. Ecology collects monthly nutrient samples from the upper depths at two sites in the Green River. Data from King County sites that were sampled in the past and are no longer sampled are included in the analysis if they provide relevant information.

Nitrogen Nitrogen is a major factor in the productivity of freshwater systems. The major sources of nitrogen are loading from surface water and groundwater and nitrogen‐fixation by bacteria. In fresh water, nitrogen‐fixation is far less significant than in terrestrial soils, unless the waterbody is under nitrogen‐limited conditions and provides nutrients to nitrogen‐fixing bacteria such as cyanobacteria.

In stream systems, the distribution of nitrogen largely depends on (1) the import of nitrogen from the atmosphere, sewage, stormwater, and agricultural runoff to the system and (2) the reduction‐oxidation by bacteria and assimilation and excretion by algae and aquatic plants within the system (Figure 3‐43).  In aerobic conditions, nitrogen gas is fixed by bacteria and is incorporated into cellular tissue. Bacteria decompose the organic nitrogen that is excreted as ammonium (NH4+). Ammonia can be further oxidized to nitrate and nitrite (nitrification) or nitrous oxide (N2O). (N2O rapidly reduces to N2 and leaves the system.) Organisms can assimilate and reduce nitrate and nitrite, which requires the energy generated via photosynthesis; ammonia does not require such reduction and is readily assimilated without energy expense.  In anaerobic environments such as in deep sediments or oxygen‐depleted streams, nitrate is reduced to nitrite and then into nitrogen gas by anaerobic bacteria.

King County 3‐51 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-43. General nitrogen cycle for streams and riverine ecosystems. (Image source: http://www.waterontheweb.org/under/streamecology/14_nutrientdynamics- draft.html.) Nitrate + Nitrite-N Nitrate and nitrite ions are dissolved, inorganic forms of nitrogen. Organisms assimilate nitrate and nitrite into their structures and use the nitrogen as a building block for amino acids, nucleotides, and other organic compounds. The organisms excrete inorganic ammonia and organic nitrogen compounds during their lifetimes and through decay after death.

King County analyzes nitrate and nitrite together and reports concentrations as a single value of nitrogen contained in nitrate + nitrite‐N.

Current Conditions In the past seven years (2007–2013), sampling occurred monthly for nitrate + nitrite‐N at five sites in the Duwamish Estuary, one site in the Duwamish River, and five sites in the Green River. Sites DR‐6.3 and GR‐32.8 were sampled in 2007 and 2008 only; site LDW‐3.0 was sampled from 2007 through 2010 only.

Nitrate + nitrite‐N concentrations ranged from 0.014 mg/L to 1.34 mg/L (Table 3‐25). The highest concentration was measured at site LDW‐3.0. Overall, mean concentrations were consistent between most sites, with some concentrations decreasing at the uppermost sites GR‐40.6 and GR‐56.9. Concentrations tended to decrease moving upstream. At the three sites in the Duwamish Estuary where more than one depth was sampled, concentrations

King County 3‐52 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary did not vary between depths. Median concentrations from lower depths were not significantly greater than those in upper depths (p‐value ≥ 0.451 to 0.918) (Table 3‐26).

Table 3-25. Nitrite + nitrite-N concentrations (mg/L) in the Green-Duwamish area (2007–2013).

Years Maximum Site FOD Minimum Maximum Median Mean Evaluated MDL

EW lower 2008–2013 70/70 0.178 0.478 0.357 0.341 0.02 EW upper 2008–2013 70/70 0.090 0.853 0.343 0.336 0.02 WW a lower 2008–2013 71/71 0.163 0.518 0.349 0.335 0.02 WW a upper 2008–2013 72/72 0.115 0.524 0.339 0.336 0.02 LDW-3.0a 2007–2010 36/36 0.107 1.34 0.34 0.419 0.02 LDW-3.3 lower 2008–2013 71/71 0.1 0.551 0.341 0.333 0.02 LDW-3.3 upper 2008–2013 72/72 0.0999 0.738 0.333 0.356 0.02 LDW-4.8 2009–2013 55/55 0.125 0.696 0.331 0.35 0.01 DR-6.3b 2007–2008 25/25 0.0846 0.716 0.35 0.36 0.02 GR-11.1 2008–2013 73/73 0.0868 0.737 0.35 0.363 0.02 GR-11.6 2008–2013 81/81 0.092 0.74 0.355 0.366 0.02 GR-32.8b 2007–2008 24/24 0.054 0.656 0.274 0.297 0.02 GR-40.6 2008–2013 73/73 0.031 0.383 0.195 0.19 0.02 GR-56.9 2008–2013 80/80 0.014 0.35 0.0985 0.109 0.01 FOD = frequency of detection; MDL = method detection limit. a Sampled in from 2007 through 2010 only. b Sampled in 2007 and 2008 only.

Table 3-26 Mann-Whitney rank-sum test of median nitrate + nitrite-N concentrations between depths at three sample locations in the Duwamish Estuary.

Number Median Standard Site of Concentration p-value Significance Deviation Samples (mg/L)

EW lower 70 0.357 0.091 0.644 n.s EW upper 70 0.343 0.12 WW-a lower 71 0.349 0.10 0.918 n.s. WW-a upper 72 0.339 0.11 LDW-3.3 lower 71 0.341 0.11 0.451 n.s. LDW-3.3 upper 72 0.333 0.14 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

From 2007 through 2013, the median concentrations of nitrate + nitrite‐N at the Duwamish Estuary monitoring sites were not significantly different (Kruskal‐Wallis analysis of variance on ranks) (Figure 3‐44). The distribution of nitrate +nitrite‐N was slightly higher at site LDW‐3.0 than at the other sites in the Green‐Duwamish area, likely because of low sample numbers and one elevated concentration of 1.34 (mg/L). Median concentrations for the Duwamish and Green rivers varied very little between sites. The relatively lower

King County 3‐53 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

concentrations at sites GR‐42.0 and GR‐56.9 may reflect fewer sources of discharge of nitrate + nitrite‐N into the system as human activity becomes sparser in the upper regions of the watershed.

Figure 3-44. Ranges of median surface water (0–1 m) nitrate + nitrite-N concentrations at sites in the Green-Duwamish area (2007–2013).

Long‐term Trends The Seasonal Mann‐Kendall test was run with three‐day rainfall as a covariate to calculate long‐term trends in nitrate + nitrite‐N.

Nitrate + nitrite‐N concentrations are decreasing at most sites at an average rate of 0.0031 mg/L per year, which reflects an overall trend of decreased nutrient loading (Table 3‐27). Sites WW‐b, LDW‐3.3, and DR‐6.3 showed significant downward annual nitrate + nitrite‐N trends. The magnitudes of the slopes for concentrations at these sites were comparable. Sites GR‐11.6 and GR‐32.8, however, showed moderate to high significant upward trends with slopes showing rates of increase of 0.0014 mg/L to 0.0019 mg/L per year, respectively; these trends were not detected at nearby sites (GR‐11.1 and GR‐40.6).

King County 3‐54 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-27. Long-term nitrate + nitrite-N trends in the Green-Duwamish area (1970–2013).

Sample Years Slope Direction Significance p-value Location Evaluated (mg/L/year)

WW-b upper 1970–2004 ↓ *** –0.003 < 0.001 LDW-3.3 upper 1975–2010 ↓ *** –0.003 < 0.001 DR-6.3 1970–2008 ↓ *** –0.003 0.006 GR-11.1 1970–2013 −− n.s. –0.001 0.617 GR-11.6 1970–2008 ↑ *** 0.001 0.025 GR-32.8 1976–2008 ↑ *** 0.002 < 0.001 GR-40.6 1972–2013 −− n.s. 0.0004 0.331 *** = significant (p < 0.10); n.s. = not significant (p > 0.10). Ammonia Ammonia in fresh water is found predominately ionized as ammonium, a readily assimilated form of inorganic nitrogen. Unlike nitrate and nitrite, ammonia does not require organisms to expend energy to reduce and assimilate the compound. Plants will preferentially take up nitrogen in the reduced ammonia form.

Current Conditions From 2007 through 2013, concentrations of ammonia ranged from less than the MDL to 0.316 mg/L (Table 3‐28). Median concentrations in the upper and lower depths were significantly different at site WW‐a (Table 3‐29). Overall, most sites had fairly low ammonia concentrations with no significant difference between sites (Kruskal‐Wallis analysis of variance on ranks “Dunn’s method”) (Figure 3‐45).

Table 3-28. Ammonia concentrations (mg/L) in the Green-Duwamish area (2007–2013). Years Minimum Maximum Site FOD Minimum Maximum Median Meana Evaluated MDL MDL EW lower 2008-2013 55/70 < MDL 0.123 0.025 0.028 0.005 0.01 EW upper 2008-2013 59/59 0.005 0.092 0.018 0.023 0.005 0.01 WW-a lower 2008-2013 52/71 0.004 0.093 0.019 0.021 0.002 0.01 WW-a upper 2008-2013 69/72 0.009 0.095 0.027 0.030 0.005 0.01 LDW-3.0 2007-2009 34/36 < MDL 0.21 0.031 0.043 0.01 0.01 LDW-3.3 lower 2007-2013 71/71 0.008 0.150 0.038 0.046 0.005 0.01 LDW-3.3 upper 2007-2013 71/72 < MDL 0.162 0.035 0.040 0.01 0.01 LDW-4.8 2009-2013 55/55 0.005 0.207 0.023 0.036 0.005 0.01 DR-6.3 2007-2008 20/25 < MDL 0.059 0.026 0.025 0.01 0.01 GR-11.1 2008-2013 66/72 < MDL 0.152 0.024 0.030 0.005 0.01 GR-11.6 2008-2013 55/72 < MDL 0.316 0.027 0.032 0.01 0.01 GR-32.8 2007-2008 13/24

King County 3‐55 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-29. Mann-Whitney rank-sum test for median ammonia concentrations between depths at three sample locations in the Duwamish Estuary (2007–2013).

Number Median Standard Site of Concentration p-value Significance Deviation Samples (mg/L) EW lower 70 0.018 0.028 0.719 n.s. EW upper 59 0.015 0.023 WW a lower 71 0.015 0.020 < 0.001 *** WW a upper 72 0.026 0.018 LDW-3.3 lower 71 0.038 0.042 0.236 n.s. LDW-3.3 upper 72 0.034 0.042 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

Figure 3-45. Ranges of median surface water (0–1 m) ammonia concentrations at sites in the Green-Duwamish area (2007–2013).

Comparison to Criteria The Green‐Duwamish river system serves as an important migration corridor and spawning and rearing habitat for several salmonid species. These species can be affected by high levels of ammonia during various life stages. Ecology published a TMDL for ammonia in 1992 for the Duwamish and Green rivers from RM 9.6 to RM 40.9 (Ecology, 1992), and the Green‐Duwamish area is included in Ecology’s 2012 Water Quality Assessment and 3030(d) list as Category 4a for having an approved TMDL in place.

King County 3‐56 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Ecology has established acute and chronic criteria for un‐ionized ammonia (NH3) based on pH, temperature, and presence of salmonids in freshwater and marine systems (WAC 173‐ 201A‐240). Un‐ionized ammonia can be toxic to aquatic species. The activity of un‐ionized ammonia depends on pH and ionic strength (conductivity); toxicity increases with increasing pH and decreases with increasing conductivity (Bower and Bidwell, 1978; Alabaster et al., 1979; Harader and Allen, 1983).

No exceedance of the acute and chronic criteria for ammonia occurred from 2007 through 2013 in any of the locations sampled in the Green‐Duwamish area. The criteria are shown in Table 3‐30.

Table 3-30. Freshwater and marine acute and chronic water quality criteria for ammonia (mg/L as nitrogen). Fresh Watera,c,d Marine Waterb,c,e Acute Criterion Chronic Criterion Acute Criterion Chronic Criterion 19.30 1.23 229.66 34.50 The marine water acute criterion was converted from un‐ionozed 0.233 mg/lL to total ammonia as nitrogen. The marine water chronic criterion was converted from un‐ionized 0.035 mg/L to total ammonia as nitrogen. a Based on pH 7 and 20°C. b Based on pH 7, 20°C, 10 ppt salinity, and pressure of 1 standard atmosphere. c WAC 173‐201A‐240. d 1984, EPA 440/5‐85‐001. e 1989, EPA 440/5‐88‐004.

Long‐term Trends Seasonal Mann‐Kendall tests with a three‐day rainfall covariate were run to calculate long‐ term trends in ammonia. All sites, except the two most upstream sites, had significant downward trends, with ammonia concentrations decreasing at an average rate of 0.0055 mg/L per year (Table 3‐31). The two upstream sites (GR‐32.8 and GR‐40.6) demonstrated very little or no change. One possible explanation for the decreasing ammonia concentrations over time is the rerouting in the 1980s of the discharge of South Treatment Plant effluent from RM 10.5 in the Green River to Puget Sound (Ecology, 1992).

Table 3-31. Long-term ammonia trends in the Green-Duwamish area (1970–2013).

Sample Years Slope Direction Significance p-value Location Evaluated (mg/L/year) WW-b upper 1970–2004 ↓ *** –0.007 < 0.001 LDW-3.3 1975–2010 ↓ *** –0.007 < 0.001 DR-6.3 1970–2008 ↓ *** –0.009 < 0.001 GR-11.1 1970–2013 ↓ *** –0.006 < 0.001 GR-11.6 1970–2008 ↓ *** –0.001 < 0.001 GR-32.8 1976–2008 -- n.s. 0 0.878 GR-40.6 1972–2013 -- n.s. 0 0.454 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

King County 3‐57 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Total Nitrogen Total nitrogen is a measure of all nitrogen in ambient water, whether it is a soluble ion, bound to sediment, in phytoplankton, or in any other form. Total nitrogen concentrations provide insight into the total amount of nitrogen currently suspended in the water column.

Current Conditions Recent total nitrogen data are available for six sites in the Duwamish River and Green River. Three of the sites were sampled in 2007 and 2008 only (DR‐6.3, GR‐32.8, and GR‐ 40.6). Concentrations of total nitrogen were generally low, ranging from 0.0.029 mg/L to 1.04 mg/L, with decreasing mean concentrations moving upstream (Table 3‐32). Site DR‐ 6.3, the most downstream site evaluated, had the highest mean concentration (0.542 mg/L); site GR‐56.9, the most upstream site, had the lowest mean concentration (0.144 mg/L).

Table 3-32. Total nitrogen concentrations (mg/L) in the Duwamish and Green rivers (2007– 2013).

Years Minimum Maximum Site FOD Minimum Maximum Median Mean Evaluated MDL MDL

DR-6.3 2007–2008 24/24 0.167 0.878 0.505 0.542 0.05 0.05 GR-11.1 2007–2013 73/73 0.157 0.933 0.519 0.522 0.05 0.05 GR-11.6 2007–2013 81/81 0.12 0.918 0.453 0.462 0.005 0.05 GR-32.8 2007–2008 24/24 0.145 0.823 0.416 0.418 0.05 0.05 GR-40.6 2007–2008 73/73 0.059 1.04 0.267 0.266 0.05 0.05 GR-56.9 2007–2013 79/80 0.029 0.331 0.134 0.144 0.005 0.005 FOD = frequency of detection; MDL = method detection limit.

Median concentrations of total nitrogen for sites DR‐6.3, GR‐11.1, GR‐11.6, and GR‐32.8 were not significantly different from each other (Kruskal‐Wallis analysis of variance on ranks “Dunn’s method”) (Figure 3‐46). Median concentrations for sites GR‐42.0 and GR‐ 56.9 varied from downstream locations and had significantly lower median concentrations overall. The variation at sites lower in the watershed from sites higher in the watershed may be due to the greater potential for urban inputs of nitrogen downstream.

King County 3‐58 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-46. Ranges of median surface water (0–1 m) total nitrogen concentrations in the Duwamish and Green rivers (2007–2013). Long‐term Trends Seasonal Mann‐Kendall tests using three‐day rainfall as a covariate were run to calculate long‐term trends at sites sampled for total nitrogen in the Duwamish and Green rivers. Table 3‐33 shows the annualized results. Overall, the total nitrogen values have stayed constant, with significant decreases at only two sites (GR‐11.1 and GR‐40.6). The slope for site GR‐40.6 is less steep and less significant than the slope for site GR‐11.1. The magnitude and significance of the trends at these two sites are lower than for nitrate + nitrite‐N and ammonia trends.

Table 3-33. Long-term total nitrogen trends in the Duwamish and Green rivers (1993–2013).

Years Slope Site Direction Significance p-value Evaluated (mg/L/year) DR-6.3 1993–2008 -- n.s. 0.001 0.100 GR-11.1 1993–2013 -- n.s. –0.001 0.561 GR-11.6 1993–2012 ↓ *** –0.082 0.007 GR-32.8 1993–2008 -- n.s. 0.002 0.466 GR-40.6 1993–2013 ↓ *** –0.002 0.073 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

King County 3‐59 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Phosphorus Similar to nitrogen, phosphorus is a crucial nutrient for primary productivity. Its limited abundance in fresh water often makes it the limiting nutrient for growth of freshwater phytoplankton. Phosphorus is necessary for many critical biological structures, including nucleotides, phospholipids, and adenosine triphosphate (ATP).

Total phosphorus represents both organic and inorganic phosphorus in particulate and dissolved forms.8 Orthophosphate (PO43‐) is the only significant form of inorganic phosphorus found in lakes and rivers. Particulate phosphorus is found in organisms and in, or strongly adsorbed to, mineral complexes such as ferric hydroxide. Dissolved phosphorus is composed primarily of ionic orthophosphate, synthetic polyphosphates, and low‐ molecular weight organic phosphates. Both orthophosphates and polyphosphates were former components of cleaning detergents. Orthophosphate is also present in animal waste, fertilizers, and other organic detritus. Phosphorus may also reenter the water column through internal loading when phosphorus that is bound to sediments is released and recirculated.

The adsorption of orthophosphate to mineral complexes is driven by pH and reduction‐ oxidation. Under aerobic conditions, some metal ions, such as aluminum and iron, form amorphous hydroxide complexes with water and settle to the sediment surface; dissolved, inorganic phosphorus binds to these complexes and becomes unavailable for biologic assimilation. Under anaerobic conditions, these metal hydroxides are reduced by anaerobic bacteria and orthophosphate is released into the system. Orthophosphate Orthophosphate, also known as soluble reactive phosphorus, is readily available for biologic uptake. During periods of algal growth, ambient orthophosphate is seldom observed above MDLs because of its rapid assimilation.

Current Conditions Concentrations of orthophosphate from 2007 through 2013 in the Green‐Duwamish area ranged from ≤ 0.002 mg/L to 0.164 mg/L (Table 3‐34). The highest concentration was measured at site GR‐11.1. Overall concentrations decrease as samples moved upstream, with some variability in the Duwamish Estuary. Variance between depths was significant at sites WW‐a and LDW‐3.3 (Table 3‐35).

Median concentrations of orthophosphate at sites LDW‐3.0 and LDW‐4.8 were significantly lower than at other sites in the Duwamish Estuary (Kruskal‐Wallis analysis of variance on ranks “Dunn’s method”) (Figure 3‐47). Sites in the Duwamish and Green rivers showed little variation in median concentrations. The lowest concentrations occurred at the two most upstream locations.

8 “Dissolved” means that it can be passed through a 0.45‐micron membrane filter.

King County 3‐60 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-34. Orthophosphate concentrations (mg/L) in the Green-Duwamish area (2007–2013).

Years Minimum Maximum Site FOD Minimum Maximum Median Mean Evaluated MDL MDL

EW lower 2010–2013 43/43 0.048 0.087 0.070 0.068 0.002 0.005 EW upper 2010–2013 43/43 0.031 0.082 0.066 0.063 0.002 0.005 WW-a lower 2010–2013 43/43 0.042 0.081 0.063 0.063 0.002 0.005 WW a upper 2010–2013 43/43 0.021 0.076 0.048 0.049 0.002 0.01 LDW-3.0 2010 7/7 0.015 0.027 0.016 0.018 0.002 0.002 LDW-3.3 lower 2010–2013 43/43 0.013 0.080 0.057 0.052 0.002 0.01 LDW-3.3 upper 2010–2013 43/43 0.011 0.067 0.027 0.031 0.002 0.01 LDW-4.8 2010–2013 39/39 0.008 0.036 0.015 0.016 0.002 0.005 DR-6.3 2007–2008 25/25 0.008 0.030 0.016 0.016 0.002 0.002 GR-11.1 2008–2013 70/70 0.006 0.164 0.015 0.018 0.0005 0.002 GR-11.6 2008–2012 80/80 0.007 0.048 0.012 0.013 0.002 0.003 GR-32.8 2007–2008 24/24 0.003 0.021 0.0068 0.008 0.002 0.002 GR-40.6 2008–2013 61/70 0.002 0.011 0.004 0.005 0.0005 0.002 GR-56.9 2008–2013 69/70 0.003 0.012 0.008 0.008 0.003 0.003 FOD = frequency of detection; MDL = method detection limit.

Table 3-35. Mann-Whitney rank-sum test of median concentrations of orthophosphate between depths at three locations in the Duwamish Estuary (2010–2013).

Number Median Standard Site of Concentration p-value Significance Deviation Samples (mg/L)

EW lower 43 0.070 0.011 0.122 n.s. EW upper 43 0.066 0.013 WW-a lower 43 0.063 0.012 < 0.001 *** WW-a upper 43 0.048 0.016 LDW-3.3 lower 43 0.057 0.022 < 0.001 *** LDW-3.3 upper 43 0.027 0.015 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

King County 3‐61 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure 3-47. Ranges of median surface water (0–1 m) orthophosphate concentrations at sites in the Green-Duwamish area (2007–2013).

Long‐term Trends Seasonal Mann‐Kendall tests using three‐day rainfall as a covariate indicate that orthophosphate concentrations on an annual basis have been significantly decreasing over time (Table 3‐36). The greatest significant decreases were seen at sites WW‐b upper and LDW‐3.3 upper, ranging from 0.0019 mg/L to 0.0040 mg/L per year.

Table 3-36. Long-term orthophosphate trends in the Green-Duwamish area (1975–2013).

Sample Years Slope Direction Significance p-value Location Evaluated (mg/L-year)

WW-b upper 1975–2010 ↓ *** –0.004 < 0.001 LDW-3.3 upper 1980–2008 ↓ *** –0.002 < 0.001 DR-6.3 1980–2013 ↓ *** –0.001 < 0.001 GR-11.1 1980–2008 ↓ *** –0.001 < 0.001 GR-11.6 1980–2013 ↓ *** –0.0002 < 0.001 GR-32.8 1980–2013 ↓ *** –0.0001 < 0.001 GR-40.6 1975–2010 ↓ *** –0.0004 < 0.001 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

King County 3‐62 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Total Phosphorus Total phosphorus represents both organic and inorganic phosphorus in particulate and dissolved forms. The majority of total phosphorus is found in organic forms; however, inorganic orthophosphate may become dominant downstream toward the marine environment because of stratification of fresh and marine waters.

Current Conditions From 2007 through 2013, total phosphorus concentrations in the Green‐Duwamish area ranged from 0.005 mg/L to 0.223 mg/L (Table 3‐37). Concentrations were greatest at site GR‐11.6 and decreased moving upstream. The lowest concentrations occurred at the three most upstream sampling locations. Variance between depths in the Duwamish Estuary was significant at sites WW‐a and LDW‐3.3 (Table 3‐38). Median concentrations varied little between sites; site GR‐40.6 had the lowest median (Figure 3‐48).

Table 3-37. Total phosphorus concentrations (mg/L) in the Green-Duwamish area (2007–2013).

Years Minimum Maximum Site FOD Minimum Maximum Median Mean Evaluated MDL MDL

EW lower 2007–2008 28/28 0.062 0.099 0.084 0.081 0.005 0.005 EW upper 2008–2010 28/28 0.053 0.095 0.080 0.077 0.005 0.005 WW-a lower 2008–2010 29/29 0.057 0.090 0.081 0.078 0.005 0.005 WW-a upper 2008–2010 29/29 0.034 0.094 0.062 0.063 0.005 0.005 LDW-3.0 2008–2010 29/29 0.022 0.076 0.046 0.045 0.005 0.005 LDW-3.3 lower 2008–2010 29/29 0.063 0.154 0.086 0.086 0.005 0.005 LDW-3.3 upper 2008–2010 29/29 0.020 0.094 0.060 0.057 0.005 0.005 LDW-4.8 2009–2010 16/16 0.022 0.070 0.045 0.045 0.005 0.005 DR-6.3 2007–2008 24/24 0.015 0.063 0.041 0.040 0.005 0.005 GR-11.1 2007–2013 72/72 0.017 0.196 0.039 0.042 0.05 0.05 GR-11.6 2007–2013 71/71 0.009 0.223 0.037 0.045 0.005 0.05 GR-32.8 2007–2008 24/24 0.007 0.045 0.018 0.019 0.005 0.005 GR-40.6 2007–2013 69/72 0.005 0.12 0.010 0.014 0.005 0.005 GR-56.9 2007–2013 71/71 0.005 0.176 0.011 0.016 0.005 0.005 FOD = frequency of detection; MDL = method detection limit.

King County 3‐63 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-38. Mann-Whitney rank-sum test of median concentrations of total phosphorus between depths at three locations in the Duwamish Estuary (2007–2013).

Number Median Standard Site of Concentration p-value Significance Deviation Samples (mg/L)

EW lower 28 0.084 0.006 0.105 n.s. EW upper 28 0.080 0.010 WW-a lower 29 0.081 0.0097 < 0.001 *** WW-a upper 29 0.062 0.015 LDW-3.3 lower 29 0.086 0.016 < 0.001 *** LDW-3.3 upper 29 0.060 0.019 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

Figure 3-48. Ranges of median total phosphorus concentrations at sites in the Green- Duwamish area (2007–2013).

Long‐term Trends Seasonal Mann‐Kendall tests with three day rainfall as a covariate found that total phosphorus concentrations in the Green‐Duwamish area have significantly decreased over

King County 3‐64 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

time (Table 3‐39). The downward slopes ranged from 0.0002 mg/L to 0.0047 mg/L per year. The decrease is most noticeable downstream from site GR‐11.6.

Table 3-39. Long-term total phosphorus trends in the Green-Duwammish area (1970–2013).

Years Slope Site Direction Significance p-value Evaluated (mg/L/year)

WW-a upper 2005–2013 Not enough data to calculate trend. WW-b upper 1970–2004 ↓ *** –0.005 < 0.001 LDW-3.3 1975–2010 ↓ *** –0.004 < 0.001 DR-6.3 1975–2008 ↓ *** –0.005 < 0.001 GR-11.1 1975–2013 ↓ *** –0.004 < 0.001 GR-11.6 1975–2008 ↓ *** –0.001 < 0.001 GR-32.8 1976–2008 ↓ *** –0.0002 0.018 GR-40.6 1970–2013 ↓ *** –0.0002 0.001 *** = significant (p < 0.10); n.s. = not significant (p > 0.10).

3.6 Metals

Surface water metals were not consistently part of King County’s early monitoring program in the Green‐Duwamish area, and long‐term trend analysis was not possible. The East Waterway SRI collected 59 water samples in the East Waterway between 2008 and 2009; these samples were analyzed for total and dissolved metals. (See Appendix C for sampling locations.)

Trace metals data are available for 14 sites sampled from 2000 through 2013. With the exception of East Waterway sites, samples were collected from single depths only. The samples were collected during a variety of flow regimes, and datasets therefore were grouped into a single analysis for total concentrations and for dissolved fractions from both baseflow and targeted storm event samples. However, East Waterway sampling events for sites SW‐1, SW‐2, and SW‐6 during incoming flood tides were analyzed separately. Because of very limited data for metals during rain events, an analysis of storm events versus baseflow conditions was not conducted.

The dissolved fractions (< 0.45 µm) and total concentrations of metals were analyzed by accredited laboratories using EPA methodologies for ICP and ICP‐MS depending on the sampling date and location.9 EPA ICP‐MS 1640 (marine), ICP 200.7 (fresh water), and ICP‐ MS 200.8 (fresh water) were used for trace metals analysis, except for mercury. Total and dissolved mercury were analyzed using Cold Vapor Atomic Fluorescence Spectrometry (EPA 1631[E]) for marine and freshwater samples and Cold Vapor Atomic Absorption (EPA 245.2) for freshwater samples only.

9 ICP = inductively coupled plasma; ICP‐MS = inductively coupled plasma mass spectrometry.

King County 3‐65 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Metals tested include total and dissolved aluminum, antimony, arsenic, barium, beryllium, cadmium, calcium, chromium, cobalt, copper, iron, lead, manganese, magnesium, mercury, molybdenum, nickel, potassium, selenium, silver, sodium, strontium, thallium, vanadium, and zinc. Mean values with the presence of non‐detects were calculated using the Kaplan‐ Meier estimation method. Metals concentrations were not compared between sites because of the sparsity of data. Number of detections, range of detected metal concentrations, median and mean values, and MDLs are presented.

Current Conditions The limited data available indicate that metals concentrations in the Green‐Duwamish area are low. The following sections provide supporting detail for this finding. Total Metals Concentrations at Each Site Appendix C shows total metals concentrations for 2000 through 2013 by sampling site. Observations are as follows:  The East Waterway samples collected for the SRI typically had lower detection limits and more detections than those collected by King County in the Lower Duwamish Waterway and the Duwamish and Green rivers.  The metals with the highest detection frequencies were aluminum, arsenic, barium, calcium, copper, magnesium, manganese, sodium, vanadium, zinc, and nickel.  Selenium was not detected in any of the samples collected by the County (MDL = 0.5 µg/L to 1.5 µg/L). Selenium was detected in all East Waterway samples with a maximum of 0.44 µg/L (MDL = 0.05 µg/L).  Total beryllium and silver had the lowest detection frequencies. Dissolved Metals Concentrations at Each Site Appendix C shows dissolved metals concentrations for 2000 through 2013 by sampling site. Observations are as follows:  Detections of the dissolved fraction of metals in the water column were not similar to those of total metals. Dissolved metals were detected at a lower frequency (from 0 percent to 71.3 percent) depending on the metal and sampling site.  The dissolved metals with the highest detection frequencies were arsenic, barium, copper, nickel, vanadium and, zinc.  Dissolved beryllium was not detected in any of the samples (MDL = 0.01 µg/L to 0.2 µg/L).  Dissolved silver was detected in only 4 of 226 samples, with a maximum concentration of 0.022 µg/L (MDL = 0.008 µg/L to 0.2 µg/L). Total and Dissolved Metals Concentrations across All Sites Table 3‐42 presents metals concentrations (total and dissolved) for all sites assessed for the Green‐Duwamish area.

King County 3‐66 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-40. Total metals and dissolved metals concentrations (μg/L) for all sites sampled in the Green-Duwamish area (2000–2013). Minimum Maximum Parameter FOD Minimum Maximum MDL MDL Antimony, dissolved 53/187 0.035 0.153 0.005 0.5 Antimony, total 56/190 0.034 0.15 0.005 0.5 Arsenic, dissolved 176/230 0.43 1.41 0.5 0.5 Arsenic, total 229/253 0.7325 6.58 0.5 0.5 Beryllium, dissolved 0/124 NA NA 0.01 0.2 Beryllium, total 1/124 0.094 0.094 0.01 0.2 Cadmium, dissolved 57/230 0.009 37.8a 0.005 0.1 Cadmium, total 67/234 0.023 1.45 0.005 0.1 Chromium, dissolved 78/230 0.11 1.15 0.05 0.79 Chromium, total 153/238 0.22 10.8 0.2 0.79 Cobalt, dissolved 29/183 0.026 3.46 0.01 0.2 Cobalt, total 74/193 0.5 4.08 0.02 0.2 Copper, dissolved 172/233 0.27 2.94 0.4 0.4 Copper, total 215/243 0.36 30.7 0.4 0.4 Lead, dissolved 26/230 0.029 0.45 0.005 2.3 Lead, total 142/243 0.054 6.72 0.025 2.3 Mercury, dissolved 49/195 0.00044 0.0058 0.00015 0.2 Mercury, total 113/232 0.00063 0.0835 0.00015 0.2 Nickel, dissolved 116/230 0.28 7.79 0.03 0.34 Nickel, total 162/238 0.4 9.82 0.03 0.34 Selenium, dissolved 56/189 0.08 0.38 0.05 1.5 Selenium, total 54/192 0.14 0.44 0.5 1.5 Silver, dissolved 4/226 0.019 0.022 0.008 0.2 Silver, total 11/234 0.0524 0.0524 0.008 0.2 Thallium, dissolved 36/184 0.004 0.012 0.003 0.2 Thallium, total 40/193 0.008 0.026 0.005 0.2 Vanadium, dissolved 183/184 0.029 1.68 0.3 0.3 Vanadium, total 189/191 0.029 17.3 0.024 0.3 Zinc, dissolved 161/240 0.68 16.9 0.08 0.5 Zinc, total 195/240 0.72 42.4 0.08 0.5 FOD = frequency of detection; MDL = method detection limit. a Anomalous sample with dissolved concentration greater than total concentration (1.45 µg/l).

Comparison to Criteria Washington State has promulgated acute and chronic water quality criteria for 10 of the metals analyzed (Chapter 173‐201A WAC). Additionally, EPA has established recommended Human Health Criteria for nine metals, although the inorganic fraction of arsenic has not been measured in the Duwamish Estuary and the Green River. The EPA criteria for the consumption of organisms are aimed to prevent adverse effects on humans

King County 3‐67 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary and are based on body weight, fish consumption rate, bioaccumulation factors, health toxicity values, and relative source contributions.

Concentrations observed at sites GR‐11, GR‐11.6, GR‐40.6, and GR‐63.1 were compared to the freshwater water quality criteria for metals. The criteria for cadmium, chromium‐tri, copper, lead, nickel, silver, and zinc established in WAC 173‐201A‐240 are based on hardness of fresh water. The median hardness value for the freshwater sites (34.8 mg CaCO3/L) was used for comparison. For the marine sites in the East Waterway and Lower Duwamish Waterway (LDW‐4.8), data were available for comparison to the marine water quality criteria for metals. These criteria were not hardness adjusted.

For most metals, dissolved metals concentrations were compared to the criteria (Table 3‐43). The total amount present rather than the dissolved fraction was used to compare to the acute and chronic criteria for chromium and the chronic criterion for mercury. One marine sample exceeded the chronic criterion for mercury. Five freshwater samples exceeded the chronic criterion for total mercury. No other exceedances of water quality criteria were detected.

King County 3‐68 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-41. Detection frequency and maximum concentrations (µg/L) of metals inthe Duwamish Estuary compared to water quality criteria. Where Washington State criteria were calculated based on hardness, criteria associated with median hardness are presented. Exceedances of EPA Human Health Criteria are highlighted in yellow and of Washington State criteria are in bold. WA State EPA Human WA State Marine Highest Freshwater Maximum Minimum Maximum Health Criteria Aquatic Life Analyte FOD Site/Depth Aquatic Life Detect MDL MDL (Consumption of Criteria Mean Criteria Organism Only) Acute Chronic Acute Chronic Antimony, dissolved 53/187 0.153 0.117 0.005 0.5 4,300. Arsenic, dissolved 176/230 1.41 1.19 0.5 0.5 — 69 36 360 190 Arsenic, inorganic 0.14a Cadmium, dissolvedc 57/230 1.45 0.071 0.005 0.1 — 42 9.3 1.25 b 0.115 b Chromium (iii) — 11,000 50 234.5 b 30.5 b Chromium (vi) — 15. 10. Chromium, total 153/238 10.8 0.85 0.2 0.79 — Copper, dissolved 172/233 2.94 1.44 0.4 0.4 — 4.8 3.1 6.3 b 4.5 b Cyanide 220,000 9.1 2.8 Lead, dissolved 26/230 0.45 0.0702 0.005 2.3 — 210 8.1 14 b 0.815 b Mercury, dissolved 49/195 0.0058 0.00069 0.00015 0.2 0.15 1.8 2.1 Mercury, total 113/232 0.0835 0.00501 0.00015 0.2 — 0.025 0.012 Nickel, dissolved 116/230 7.79 0.425 0.03 0.34 4,600 74 8.2 188 b 20.9 b Selenium, dissolved 56/189 0.38 0.188 0.05 1.5 — 290 71. 20. 5. Silver, dissolved 4/226 0.022 0.0198 0.008 0.2 — 1.9 0.675 b Zinc, dissolved 161/240 16.9 6.16 0.08 0.5 — 90 81 47 b 43 b a This criterion is based on carcinogenicity of 10‐6 risk. Alternative risk levels may be obtained by moving the decimal point (for example, for a risk level of 10‐5, the decimal point would be moved in the recommended criterion one place to the right). This recommended water quality criterion for arsenic refers to the inorganic form only. b Hardness‐based criterion. Calculated based on median hardness of 34.8 mg CaCO3/L. c Outlier of 37.8 µg/L dissolved cadmium was removed. The dissolved fraction was more than 10 times the total cadmium detected in the sample.

King County 3‐69 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

3.7 Organic Compounds

King County’s routine monitoring program in the Green‐Duwamish area does not include sampling for organic compounds in the water column. Organics data are sporadic, and long‐term trend analysis was not possible. The East Waterway SRI collected 59 water samples in the East Waterway between 2008 and 2009; these samples were analyzed for total and dissolved metals, PCB congeners, semivolatile organic compounds (SVOCs), TBT, nutrients, and physical parameters (Windward and Anchor QEA, 2014).

Many chemicals likely to be present were not monitored. For example, little is known in the Green‐Duwamish area about chemicals of emerging concern (CECs), including current‐use pharmaceuticals, personal care products, pesticides, and flame‐retardants. CECs have been detected at low levels in surface water, but more information is needed on their risk to human health and the environment, frequency of occurrence, and sources.

Current Conditions Data from 2001 through 2012 from six King County sites and the five East Waterway SRI sites were used to assess current conditions. All sites except LDW‐0.1, WW‐a, and the East Waterway sites were considered freshwater sampling locations for comparison with water quality criteria. During this time, 135 organic compounds were sampled at varying frequencies (monthly, quarterly, or yearly). Because of the limited data available for samples at depth, concentrations were not compared between sites and depths. Summary results by site are provided in Appendix C.

General findings are as follows:  No chlorinated pesticides, one chlorinated herbicide, no organophosphorus pesticides, and no PCB Aroclors were detected.  PCBs were always detected by congener analysis.  PAHs were commonly detected in surface waters. Phthalates Phthalates are plasticizers and potential endocrine disruptors. Because of their ubiquitous nature, phthalates are troublesome in laboratory analysis. Although care was taken to minimize contamination, phthalates were regularly detected in method blanks. Of the five phthalates analyzed, all were detected with blank contamination in one or more samples. Endocrine Disrupting Compounds Endocrine disrupting compounds have recently become chemicals of concern because of their potential to affect reproductive success. While there are many organic compounds that have the potential to mimic the hormones in animals, KCEL has been able to test for a group of seven compounds referred to here as endocrine disrupting compounds:  Bis(2‐ethylhexyl) adipate

King County 3‐70 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

 Total 4‐nonylphenol  Bisphenol A  Ethynyl estradiol  Methyltestosterone  Progesterone  Vinclozolin Bis(2‐ethylhexyl) adipate and total 4‐nonylphenol were the only endocrine disrupting compounds that were reliably detected in some samples. Bisphenol A, ethynyl estradiol, methyltestosterone, progesterone, and vinclozolin all were difficult to analyze because samples were commonly found with interferences and blank contamination. Polycyclic Aromatic Hydrocarbons PAHs are byproducts of fossil‐fuel combustion. They are constituents in creosote (wood preservative) and asphalt sealants, are associated with urbanization, and are transported to receiving waters through runoff, atmospheric deposition, and leaching or abrasion from creosote‐treated pilings. The most frequently detected PAHs were acenaphthene, flouranthene, and pyrene. Acid/Alcohol/Phenolic Compounds Benzoic acid and benzyl alcohol were detected at sites GR‐11.1 and GR‐40.6. The analytical method for benzoic acid is problematic because samples often contain blank contamination. Additionally, benzoic acid and benzyl alcohol are naturally present in many plants or as a metabolic byproduct in some organisms.

Phenol is a precursor to some household products including cough and cold medicines, herbicides, plastics, and cleaning products. It was detected in 2 of 14 samples from site GR‐63.1. It was not detected at other sites. Pharmaceuticals and Personal Care Products The occurrence of pharmaceuticals and personal care products (PPCPs) in surface waters has been reported nationwide. These contaminants may enter the aquatic environment through multiple pathways, including wastewater treatment discharges. Because of this potential link to wastewater treatment discharges, some PPCPs have been used in recent years as tracers for wastewater discharge into aquatic environments.

Two PPCPs (estrone and isophorone) were detected in samples in the Green‐Duwamish area. Estrone was analyzed 36 times and was detected 3 times. Isophorone was detected in 1 of 89 samples (at site GR‐11.1 [1/20]). It should be noted that the detection limits for PPCPs varied greatly between sampling years, and it was the much lower detection limits that allowed for a few more positive detections.

King County 3‐71 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Polychlorinated Biphenyls PCBs in the form of total PCB Aroclors were analyzed as part of King County’s 2003–2004 Green‐Duwamish River Water Quality Assessment.10 The assessment yielded no detections with detection limits ranging from 0.047 µg/L to 0.057 µg/L.

Another King County study sampled sites DR‐9.8 and GR‐42.0 in the Duwamish and Green rivers in 2011–2012. The study targeted and detected PCB congeners by using a different analytical method with lower detection limits than in the 2003–2004 assessment. Total PCBs (congeners) were detected at both locations during storm and baseflow sampling events. The mean total PCB concentrations for baseflow samples ranged from 118 pg/L at site GR‐42.0 to 146 pg/L at site DR‐9.8; concentrations for storm flow samples ranged from 577 pg/L at site GR‐42.0 to 829 pg/L at site DR‐9.8 (King County, 2014a).

Surface water grab samples were collected from the Lower Duwamish Waterway on four sampling dates between August and December 2005 from two locations (one near Harbor Island at RM 0.0 and the other near the South Park Bridge at RM 3.3) as part of the remedial investigation for the Lower Duwamish Waterway Superfund site. Total PCB concentrations ranged from 132 pg/L to 3,211 pg/L with a mean concentration of 1,277 pg/L. Concentrations were lowest for both locations in the November samples when flow rates were the highest (Windward, 2010). In the East Waterway, PCB concentrations ranged from 67.7 pg/L to 5,838 pg/L, with a grouped mean concentration of 1,310 pg/L.

Comparison to Water Quality Criteria With the exception of PCBs, there are no Washington State water quality criteria for the organic compounds detected in the Green‐Duwamish area. Table 3‐44 shows the Washington State aquatic life water quality criteria for organic compounds and indicates that the frequency of detection for each compound in samples from the Green‐Duwamish area was zero except for total PCBs (congeners).

From 2001 through 2012, no organic compounds were detected at levels above the aquatic life criteria. The detection limit, however, was greater than the chronic criteria for aldrin, Dieldrin, chlordane, alpha‐chlordane, trans‐chlordane, dichlorodiphenyltrichloroethane (DDT) and its metabolites, endrin, heptachlor, parathion‐ethyl and ‐methyl, toxaphene, and total Aroclors (PCBs). Congener analysis detected PCBs at levels below the state criteria, but these concentrations exceeded the EPA recommended Human Health Criteria.

Total PCB concentrations measured by congener analysis exceeded the EPA Human Health Criteria in 66 of 72 samples. Two samples exceeded the Human Health Criteria for bis(2‐ ethylhexyl)phthalate: one collected in the East Waterway and one collected at the downstream end of the Lower Duwamish Waterway.

10 See http://www.kingcounty.gov/services/environment/watersheds/green‐river/watershed‐quality‐ assessment.aspx.

King County 3‐72 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Monitoring data indicate that most organic compound concentrations do not exceed water quality criteria with the exception of total PCBs. However, the analytical techniques used produced samples with blank contamination and the MDLs for regulated compounds were high and above the acute, chronic, and/or both criteria for most compounds. Improved analytical methods with lower detection limits would yield more reliable and informative data for samples collected in the future.

King County 3‐73 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table 3-42. Detection frequency and maximum concentrations (µg/L unless otherwise noted) of organic compounds in the Duwamish Estuary and Green River compared to water quality criteria (2001–2012). The highest mean for a monitoring site is also provided. Exceedances of EPA Human Health Criteria are highlighted in red and of Washington State criteria are in bold. Method detection limits above the state chronic criteria are in bold, and limits above Human Health Criteria are highlighted in yellow. EPA Human WA State Highest WA State Marine Health Criteria Freshwater Maximum Site/ Minimum Maximum Aquatic Life Analyte FOD for Aquatic Life Detect Depth MDL MDL Criteria Consumption of Criteria Mean Organisms Only Acute Chronic Acute Chronic Chlorinated Herbicides and Pesticides 2,4-D 0/42 NA < MDL 0.015 0.51 2,4-DB 0/42 NA < MDL 0.022 0.51 2,4,5-T 0/42 NA < MDL 0.016 0.51 2,4,5-TP (silvex) 0/42 NA < MDL 0.016 0.51 4,4'-DDD 0/34 NA < MDL 0.0047 0.0057 0.00084a 0.13 0.001 1.1 0.001 4,4'-DDE 0/34 NA < MDL 0.0047 0.0057 0.00059a 0.13 0.001 1.1 0.001 4,4'-DDT 0/34 NA < MDL 0.0047 0.0057 0.00059a 0.13 0.001 1.1 0.001 Aldrin 0/34 NA < MDL 0.0047 0.0057 0.00014a 0.71 0.0019 2.5 0.0019 Alpha-BHC 0/34 NA < MDL 0.0047 0.0057 0.013 Alpha-chlordane 0/13 NA < MDL 0.0047 0.0056 2.4 0.0043 Beta-BHC 0/34 NA < MDL 0.0047 0.0057 0.046a Chlordane 0/21 NA < MDL 0.024 0.028 0.00059a 0.09 0.004 2.4 0.0043 Dalapon 0/26 NA < MDL 0.012 0.052 Delta-BHC 0/34 NA < MDL 0.0047 0.0057 Dicamba 0/26 NA < MDL 0.02 0.042 Dichloroprop 0/42 NA < MDL 0.011 0.51 Dieldrin 0/34 NA < MDL 0.0047 0.0057 0.00014a 0.71 0.0019 2.5 0.0019 Dinoseb 0/42 NA < MDL 0.027 0.51 Endosulfan I 0/34 NA < MDL 0.0047 0.0057 2 0.034 0.0087 0.22 0.056 Endosulfan II 0/34 NA < MDL 0.0047 0.0057 2 0.034 0.0087 0.22 0.056

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EPA Human WA State Highest WA State Marine Health Criteria Freshwater Maximum Site/ Minimum Maximum Aquatic Life Analyte FOD for Aquatic Life Detect Depth MDL MDL Criteria Consumption of Criteria Mean Organisms Only Acute Chronic Acute Chronic Endosulfan sulfate 0/34 NA < MDL 0.0047 0.0057 2 Endrin aldehyde 0/34 NA < MDL 0.0047 0.0057 0.81 Endrin 0/34 NA < MDL 0.0047 0.0057 0.81 0.037 0.0023 0.18 0.0023

Gamma-BHC (lindane) 0/34 NA < MDL 0.0047 0.0057 0.063a 0.16 2. 0.08

Heptachlor epoxide 0/34 NA < MDL 0.0047 0.0057 0.00021a 0.52 0.0038 Heptachlor 0/34 NA < MDL 0.0047 0.0057 0.00011a 0.053 0.0036 0.52 0.0038 Hexachlorocyclopentadie 0/70 NA < MDL 0.24 2.9 17,000 a ne MCPA 0/41 NA < MDL 0.011 0.51 MCPP 0/42 NA < MDL 0.013 0.51 Methoxychlor 0/34 NA < MDL 0.024 0.028 Toxaphene 0/34 NA < MDL 0.047 0.057 0.00075a 0.21 0.0002 0.73 0.0002 Trans-chlordane 0/13 NA < MDL 0.0047 0.0056 2.4 0.0043 Triclopyr 1/4 1.01 < MDL 0.49 0.49 Organophosphate Pesticides Chlorpyrifos 0/26 NA < MDL 0.032 0.067 0.011 0.0056 0.083 0.041 Diazinon 0/26 NA < MDL 0.041 0.084 Disulfoton 0/26 NA < MDL 0.026 0.053 Malathion 0/27 NA < MDL 0.046 0.094 Parathion-ethyl 0/27 NA < MDL 0.043 0.088 0.065 0.013 Parathion-methyl 0/26 NA < MDL 0.034 0.071 0.065 0.013 Phorate 0/26 NA < MDL 0.031 0.065 Endocrine Disrupting Compounds (EDCs) Atrazine 0/15 NA < MDL 0.047 0.1 Bis(2-ethylhexyl)adipateb 4/10 0.67 0.107 0.0094 0.1

King County 3‐75 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

EPA Human WA State Highest WA State Marine Health Criteria Freshwater Maximum Site/ Minimum Maximum Aquatic Life Analyte FOD for Aquatic Life Detect Depth MDL MDL Criteria Consumption of Criteria Mean Organisms Only Acute Chronic Acute Chronic Bisphenol A 0/6 NA < MDL 0.094 0.1 Estradiol 0/32 NA < MDL 0.00048 0.011 Estrone 3/32 0.0016 < MDL 0.00029 0.011 Ethynyl estradiol 0/32 NA < MDL 0.00048 0.011 Methyltestosterone 0/16 NA < MDL 0.0094 0.011 Progesterone 0/16 NA < MDL 0.0094 0.011 Testosterone 0/16 NA < MDL 0.0094 0.011 Total 4-nonylphenolb 1/11 0.27 < MDL 0.019 0.1 Vinclozolin 0/16 NA < MDL 0.0094 0.011 Low Molecular Weight PAHs (LPAHs) 2-chloronaphthalene 0/104 NA < MDL 0.0094 0.7 2-methylnaphthalene 6/104 1 < MDL 0.003 0.11 Acenaphthene 40/129 0.2 0.0625 0.005 0.011 Acenaphthylene 21/140 0.002 0.000813 0.00024 0.011 Anthracene 14/141 0.057 0.000408 0.00024 0.011 110,000 Fluorene 20/120 0.16 0.000836 0.003 0.011 14,000 Naphthalene 44/120 12 0.0499 0.004 0.028 Phenanthreneb 25/106 0.9 0.0146 0.004 0.011 High Molecular Weight PAHs (HPAHs) Benzo(a)anthracene 15/138 0.02 0.000755 0.00024 0.028 0.031a Benzo(a)pyrene 14/142 0.00543 0.0013 0.00047 0.2 0.031a Benzo(b)fluoranthene 11/121 0.00339 0.00121 0.0005 0.011 0.031a Benzo(g,h,i)perylene 20/144 0.0059 0.00164 0.00028 0.1 Benzo(k)fluoranthene 8/121 0.00275 0.00103 0.0005 0.011 0.031a Dibenzo(a,h)anthracene 5/141 0.0013 0.000531 0.00033 0.1 0.031a

King County 3‐76 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

EPA Human WA State Highest WA State Marine Health Criteria Freshwater Maximum Site/ Minimum Maximum Aquatic Life Analyte FOD for Aquatic Life Detect Depth MDL MDL Criteria Consumption of Criteria Mean Organisms Only Acute Chronic Acute Chronic Chrysene 16/116 0.024 0.00152 0.0005 0.028 0.031a Fluoranthene 42/123 0.19 0.0632 0.001 0.011 370 Indeno(1,2,3-CD)Pyrene 15/142 0.0043125 0.00103 0.00024 0.1 0.031a Pyrene 40/124 0.132 0.0408 0.001 0.011 11,000 Polychlorinated Biphenyls (PCBs) Aroclor 1016 0/34 NA < MDL 0.047 0.057 Aroclor 1221 0/34 NA < MDL 0.047 0.057 Aroclor 1232 0/34 NA < MDL 0.047 0.057 Aroclor 1242 0/34 NA < MDL 0.047 0.057 Aroclor 1248 0/34 NA < MDL 0.047 0.057 Aroclor 1254 0/34 NA < MDL 0.047 0.057 Aroclor 1260 0/34 NA < MDL 0.047 0.057 Total Aroclors 0/84 NA < MDL 0.047 0.057 0.00017a 10 0.03 2 0.014 Total PCBs (pg/L) 72/72 5,838 2,780 170a 10^7 3*10^4 2*10^6 1.4*10^4 Semivolatile Organic Compounds (SVOCs) 1,2-dichlorobenzene 0/103 NA < MDL 0.024 0.6 17,000 1,2,4-trichlorobenzene 0/89 NA < MDL 0.0095 0.6 1,3-dichlorobenzene 0/103 NA < MDL 0.024 0.7 2,600 1,4-dichlorobenzene 1/103 3.1 < MDL 0.024 0.6 2,600 2-chlorophenol 0/89 NA < MDL 0.024 0.3 2-methylphenol 0/88 NA < MDL 0.024 0.3 2-nitroaniline 0/89 NA < MDL 0.095 1.2 2-nitrophenol 0/88 NA < MDL 0.048 1.6 2,4-dichlorophenol 0/104 NA < MDL 0.047 1.7 790a 2,4-dimethylphenol 0/88 NA < MDL 0.024 1.7

King County 3‐77 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

EPA Human WA State Highest WA State Marine Health Criteria Freshwater Maximum Site/ Minimum Maximum Aquatic Life Analyte FOD for Aquatic Life Detect Depth MDL MDL Criteria Consumption of Criteria Mean Organisms Only Acute Chronic Acute Chronic 2,4-dinitrophenol 0/89 NA < MDL 0.24 5.6 14,000 2,4-dinitrotoluene 0/88 NA < MDL 0.048 3.5 9.1a 2,4,5-trichlorophenol 0/89 NA < MDL 0.12 1.8 2,4,6-trichlorophenol 0/103 NA < MDL 0.048 1.6 6.5a 2,6-dinitrotoluene 0/88 NA < MDL 0.048 4.7 3-nitroaniline 0/88 NA < MDL 0.24 3.5 3,3'-dichlorobenzidine 0/90 NA < MDL 0.094 1.8 4-bromophenyl phenyl 0/88 NA < MDL 0.024 0.7 ether 4-chloro-3-methylphenol 0/88 NA < MDL 0.094 1.9 4-chloroaniline 0/88 NA < MDL 0.047 1.5 4-chlorophenyl phenyl 0/88 NA < MDL 0.024 0.6 ether 4-methylphenol 0/88 NA < MDL 0.047 0.3 4-nitroaniline 0/88 NA < MDL 0.24 1.3 4-nitrophenol 0/88 NA < MDL 0.24 1 4,6-dinitro-o-cresol 0/89 NA < MDL 0.24 4.6 Aniline 8/70 NA < MDL 0.024 0.2 Benzidine #N/A #N/A #N/A #N/A #N/A 0.00054 Benzoic acid 8/70 2.65 1.07 0.24 3.1 Benzyl alcohol 2/70 1.16 < MDL 0.094 1 Butyl benzyl phthalateb 4/62 0.201 0.141 0.047 0.6 Bis(2- 0/89 NA < MDL 0.0095 0.7 chloroethoxy)methane Bis(2-chloroethyl)ether 0/89 NA < MDL 0.0095 0.6 1.4a Bis(2- 0/89 NA < MDL 0.0095 0.6 170,000 chloroisopropyl)ether

King County 3‐78 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

EPA Human WA State Highest WA State Marine Health Criteria Freshwater Maximum Site/ Minimum Maximum Aquatic Life Analyte FOD for Aquatic Life Detect Depth MDL MDL Criteria Consumption of Criteria Mean Organisms Only Acute Chronic Acute Chronic Bis(2- 9/61 12.7 < MDL 0.2 0.7 5.9a ethylhexyl)phthalateb Caffeineb 11/49 0.641 0.0776 0.0094 0.025 Carbazole 0/100 NA < MDL 0.024 0.7 Coprostanol 0/16 NA < MDL 0.47 0.49 Di-n-butyl phthalateb 7/64 0.12 0.0552 0.024 0.7 12,000 Di-n-octyl phthalate 2/89 0.113 < MDL 0.0095 0.7 Dibenzofuran 1/104 0.13 < MDL 0.002 0.025 Diethyl phthalateb 6/71 1.8 0.051 0.01 0.7 120,000 Dimethyl phthalateb 2/89 0.362 < MDL 0.0095 0.7 2,900,000 Hexachlorobenzene 0/100 NA < MDL 0.024 0.9 0.00077a Hexachlorobutadiene 0/88 NA < MDL 0.047 0.6 50a Hexachloroethane 0/88 NA < MDL 0.024 0.6 8.9a Isophorone 1/89 0.026 < MDL 0.0095 0.7 600a N-nitrosodi-n- 0/89 NA < MDL 0.047 2.8 0.51a propylamine N-nitrosodimethylamine 7/88 NA < MDL 0.024 1.6 8.1 N-nitrosodiphenylamine 0/88 NA < MDL 0.024 0.5 16a Nitrobenzene 0/89 NA < MDL 0.0095 0.7 1,900 Pentachlorophenol 0/104 NA < MDL 0.12 1.8 8.2 13 7.9 3.32 2.1 Phenolb 2/104 0.67 < MDL 0.024 0.5 4,600,000 FOD = frequency of detection; MDL = method detection limit. #NA = A standard exists for this compound but it was not analyzed for. a This criterion is based on carcinogenicity of 10‐6 risk. Alternative risk levels may be obtained by moving the decimal point (for example, for a risk level of 10‐5, the decimal point in the recommended criterion would be moved one place to the right). b Blank contamination present in a least one sample. EPA National Functional Guidelines were followed.

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King County 3‐80 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

4.0 SEDIMENT QUALITY Sediment contamination in the Duwamish Estuary is mostly the result of historical industrial, land use, and management practices. Current pathways of contamination include surface runoff, stormwater and CSO outfalls, atmospheric deposition, groundwater discharges, and erosion and leaching of contaminated soils.

A number of sediment quality studies have been conducted in the Duwamish Estuary because of the historical and current land uses in the area. This chapter summarizes surface sediment quality data from these studies in relation to Washington State’s Sediment Management Standards and gives the distribution of exceedances. It also summarizes the results of a sediment quality study in the Green River watershed.

4.1 Data Evaluated

This analysis looked at sediment quality data from the following investigations and studies conducted in the Duwamish Estuary and Green River between 1991 through 2013:  The feasibility study for Lower Duwamish Waterway Superfund site, which gathered surface sediment data (15 cm or less) and analyzed data from 10 cm or less during 76 sampling events from 1991 through 2009 (AECOM, 2012).  The supplemental remedial investigation for the East Waterway Operable Unit of the Harbor Island Superfund site, which collected surface sediment data during 17 sampling events from 1995 through 2009 (Windward and Anchor QEA, 2014).  The remedial investigation and feasibility study for the Lockheed West Seattle Superfund site, which collected surface sediment data for the remaining sediment cleanup in the West Waterway from 2006 through 2008 (Tetra Tech, 2012).  King County data from sediments sampled near the Chelan Ave CSO, located near the head of the West Waterway, on four separate occasions from 1995 through 2013.11  King County’s characterization of sediment quality in the Green River watershed and the pathways of upstream contaminants that enter the Duwamish Estuary (2008 through 2012).  Ecology’s Puget Sound Assessment and Monitoring Program: spatial/temporal monitoring 2002–present. Data were downloaded from Ecology's Environmental Information Management (EIM) system (https://fortress.wa.gov/ecy/eimreporting/Eim/EIMSearch.aspx?SearchType=AllEI M&State=newsearch&Section=location).

11 See the following websites for information on King County’s assessment of sediments near CSO sites in the Duwamish Estuary: http://your.kingcounty.gov/dnrp/library/wastewater/sedman/smp/SMP_199808.pdf and http://your.kingcounty.gov/dnrp/library/2012/kcr2683.pdf.

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 Ecology’s Urban Waters Initiative, 2007: Sediment Quality in Elliott Bay (https://fortress.wa.gov/ecy/publications/summarypages/0903014.html).  Waterway Sediment Operable Unit Harbor Island Superfund Site. Tributyltin in Marine Sediments and the Bioaccumulation of Tributyltin: Combined Data Report (EVS, 1999).  2007 Long Term Monitoring Pacific Sound Resources Superfund Site (Science Applications International Corporation, 2008).  U.S. Army Corps of Engineers Dredged Material Management Program: Tiered‐ Partial Monitoring of Elliott Bay (USACE, 2008).

4.2 Duwamish Estuary

The following sections summarize the physical structure and chemistry of the sediments in the Duwamish Estuary. Figure 4‐1 shows the locations of areas described in the sections.

Physical Structure The physical structure of marine sediments affects the distribution and concentrations of metals and organic chemicals. For example, chemical concentrations are often expected to be higher at sites with more fine particles because of the increased surface area for chemicals to bind to. In addition, higher concentrations of total organic carbon (TOC) can increase binding of some organic compounds (Wenning et al., 2005). Lower Duwamish Waterway The physical structure of surface sediments in the Lower Duwamish Waterway varies from largely sands near the upper turning basin (RM 4.5) to mud near the mouth of the waterway. The 10th and 90th percentile fines (silt + clay) content is 29 percent and 82 percent in the navigation channel and 13 percent and 87 percent outside the channel (excluding the slips). The mean percent fines in the navigation channel (62 percent) is greater than the mean for the entire Superfund site (53 percent). Some of the greatest percent fines relative to the site‐wide average are in three of the five slips (Slips 1, 3, and 6). The sediments above the turning basin have the lowest percent fines.

The site‐wide mean TOC is 1.9 percent, with 10th and 90th percentiles of 1.2 percent and 2.6 percent in the navigation channel and 0.8 percent and 2.9 percent outside of the channel. The concentrations of TOC correspond well with the percent fines distributions.

The distribution of higher chemical concentrations does not correspond well with sediments of higher percent fines. Elevated concentrations of contamination were detected more often along the river banks where the percent fines are lower than in the navigation channel. Depending on the sediment makeup, the sources of contamination may be more of a controlling factor than percent fines for sediments closer to the shoreline.

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Figure 4-1. Exceedances of the Sediment Management Standards chemistry and toxicity criteria in Duwamish Estuary surface sediments (1991–2013). East Waterway Surface sediments in the East Waterway are composed of silty sands and sandy silts. Silty sands are classified as having 50 percent or more sand by mass, with 20 percent to 30 percent of silts. Sandy silts are classified as having 50 percent or more silt by mass, with 20 percent to 35 percent of sand. The percent fines ranged from 0.8 percent to 92 percent with

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a site‐wide mean of 40 percent. The higher percent fines were detected in the slips, in sections of the navigation channel that were not dredged in the early 2000s, and along the west bank of the East Waterway beneath the West Seattle and Spokane Street bridges. The greatest percent fines (> 80 percent) were detected in the southern quarter of the navigation channel.

The TOC concentrations range from 0.14 percent to 10.1 percent with a mean of 1.6 percent. The higher TOC concentrations correspond well with higher percent fines.

As is the case with the Lower Duwamish Waterway, the distribution of higher chemical concentrations does not correspond well with the distribution of the higher percent fines. The sediments in the upper portion of the East Waterway had some of the highest percent fines but showed some of the lowest occurrences of exceedances of standards in the entire waterway. The majority of the exceedances occurred just upstream of Slip 27 in the midsection of the waterway, an area where half of the surface sediments have been dredged in the past 10 years. West Waterway Sediments in the West Waterway adjacent to Harbor Island have higher concentrations of organic material and finer grained sand than sediments collected from middle or east channel locations. The percent fines in the whole West Waterway range from 10.16 percent to 77.19 percent and concentrations of TOC (percent of dry weight) range from 0.5 percent to 4.24 percent, with a decreasing trend as the samples move closer to the mouth of the waterway (EVS, 1999).

Sediment Chemistry Where applicable, concentrations of contaminants in surface sediments in the Duwamish Estuary were compared to marine sediment chemical criteria from Tables I and III in the Washington State Sediment Management Standards (SMS) of Chapter 173‐204 WAC (Ecology, 2013a). Concentrations for some contaminants, such as metals, were dry‐weight‐ normalized; others, such as PAHs, were organic carbon normalized.

The SMS establishes two criteria for each contaminant based on its potential to adversely affect the benthic community:  The sediment quality standards (SQS) are a “no adverse effects” level (WAC 173‐ 204‐320), meaning sediment concentrations below this level are expected to have no adverse effects on the benthic community. These criteria are also known as the benthic Sediment Cleanup Objective (SCO) (WAC 173‐204‐562), which is used as a sediment quality goal for Washington state sediments.  The Cleanup Screening Level (CSL) is the “minor adverse effects” level (WAC 173‐ 204‐562), which is used as an upper regulatory level for source control and cleanup decision making.  If a sediment sample receives both chemical and toxicological analysis, the results of the toxicological analysis (high or low) supersede those of the chemical analysis and

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will determine whether or not the sample exceeds SMS criteria. If a sediment sample receives only one type of analysis, chemical or toxicological, the sample is compared to the SMS criteria based on the results of the one analysis. Appendix D shows the distribution of the 39 contaminants detected in the Duwamish Estuary whose concentrations exceed SMS benthic criteria and compares contaminant concentrations and detection frequencies in the East and Lower Duwamish waterways.

The locations of surface sediment samples in the Duwamish Estuary that exceed SMS chemical and toxicity criteria are shown in Figure 4‐1. The figure shows the exceedances before remediation of cleanup and Early Action Areas in the Duwamish Estuary. Data from six organic compounds, including all phenolic compounds, benzyl alcohol, and benzoic acid, are included in the data tables in Appendix D. They are not shown on maps that compare sites with SMS and are not discussed below because of their ubiquity throughout Puget Sound, transitory nature, natural sources, and/or the lack of confidence in analytical precision and laboratory detection limits (Ecology, 2009). Metals Eight metals exceeded the CSL in the East or Lower Duwamish Waterways (Appendix D): arsenic, cadmium, chromium, copper, lead, mercury, silver, and zinc. Specific findings are as follows:  The majority of the exceedances were north of RM 1.3 in the Lower Duwamish Waterway.  Several metals exceeded the CSL at two additional locations in the Lower Duwamish Waterway, the west inlet at RM 2.2 and south of the Jorgensen Forge cleanup area between RM 3.7 and RM 3.9.  Half of the metals (arsenic, chromium, copper, and lead) were detected in only a few locations in the Lower Duwamish Waterway, all of which were within 50 m of the shoreline.  Other metals (mercury and zinc) were detected both near and away from the shoreline in the Lower Duwamish Waterway  Cadmium exceeded the CSL approximately 50 m southwest of the Duwamish/Diagonal cleanup area and in the west inlet located at RM 2.2 in the Lower Duwamish Waterway.  Mercury was widely dispersed and exceeded the CSL throughout the East Waterway, in the Lower Duwamish Waterway between RM 0.0 and RM 1.3 (exceedances were detected between RM 0.2 and RM 0.6 and RM 0.9 and RM 1.2), throughout the west inlet of the Lower Duwamish Waterway at RM 2.2, south of the Jorgensen Forge cleanup area (RM 3.7 to RM 3.9), and in the Lower Duwamish Waterway near the head of Slip 6.  The distribution of zinc CSL exceedances was similar to those of arsenic, chromium, copper, and lead.

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The surface sediments at the Lockheed West Seattle Superfund site, located at the northwest corner of the West Waterway, exceeded the CSL for arsenic, chromium, copper, lead, mercury, and zinc. The exceedances were localized to two areas: the former shipway along the western border of the site (in Elliott Bay) and the former dry docks located along the eastern border adjacent to the navigation channel in the West Waterway. Organics Polycyclic Aromatic Hydrocarbons Total high molecular weight PAHs (HPAHs) and total LPAHs exceeded the CSL in the Lower Duwamish and East waterways (Appendix D). In addition to total HPAHs and total LPAHs, 16 PAHs exceeded the CSL in these waterways:  Acenaphthene  Anthracene  Benzo(a)anthracene  Benzo(a)pyrene  Benzo(g,h,i)perylene  Total benzofluoranthenes  Chrysene  Dibenzo(a,h)anthracene  Dibenzofuran  Fluoranthene  Fluorene  Indeno(1,2,3‐cd)pyrene  2‐methylnaphthalene  Naphthalene  Phenanthrene  Pyrene SQS exceedances were dispersed throughout both waterways. CSL exceedances were generally localized. More than one PAH exceeded the CSL at seven locations:  Just south of Slip 36 in the East Waterway near the former GATX and Rabanco properties  In the East Waterway near a large aggregation of treated wood pilings at Terminal 25  Along the west bank of the Lower Duwamish Waterway north of Kellogg Island (RM 0.5 to RM 0.6)  In the Lower Duwamish Waterway between RM 1.0 and RM 1.1  In the west inlet of the Lower Duwamish Waterway at RM 2.2  In the Lower Duwamish Waterway between RM 2.6 and RM 2.8

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 South of the Jorgensen Forge cleanup area in the Lower Duwamish Waterway (RM 3.7 to RM 3.8) The majority of the PAH exceedances were detected within 50 m from the shoreline. Three stretches of the Lower Duwamish Waterway did not have any exceedances (CSL or SQS): RM 1.6 to RM 2.1, RM 2.8 to RM 3.7, and RM 4.4 to RM 4.7.

The Lockheed West Seattle site in Elliott Bay and the West Waterway exceeded the CSLs for total LPAHs and 9 PAHs:  Acenaphthene  Acenaphthylene  Benzo(a)anthracene  Benzo(a)pyrene  Total benzofluoranthenes  Benzo(g,h,i)perylene  Chrysene  Dibenzo(a,h)anthracene  Indeno(1,2,3‐cd)pyrene CSLs were exceeded in the former dry docks in the West Waterway, approximately 75 m to 150 m north of the shoreline. Sediments exceeded the SQS in the former shipway, dry docks, and along the West Waterway navigation channel.

Phthalates Four phthalates exceeded the CSL in the Lower Duwamish and East waterways (Appendix D):  Bis(2‐ethylhexyl)phthalate. At several locations in the East Waterway along the northwest shore west‐southwest of the inlet of Slip 27 and in the head end of Slip 27. In the West Waterway, in a surface sediment sample collected 0.5 km upstream of the Lockheed Shipyard cleanup area during a 2011 sampling event and at the Lockheed West Seattle site near the former dry docks. In the Lower Duwamish Waterway, at the following locations:  RM 0.0 to RM 0.1 along the eastside of the waterway  Around the periphery of the Duwamish/Diagonal cleanup area  Near Terminal 115 (RM 1.8 to 1.9)  In and near the west inlet at RM 2.2  Between RM 2.7 and RM 2.8  South of the Jorgensen Forge cleanup area on the east side of the waterway (RM 3.7 to RM 3.9)  Between RM 4.9 and RM 5.0

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 Butyl benzyl phthalate. In the East Waterway near the former Rabanco property and across the navigation channel from the Rabanco property. In the Lower Duwamish Waterway at the west inlet at RM 2.2 and south of the Jorgensen Forge cleanup area (RM 3.7 to RM 3.9).  Dimethyl phthalate. In the west inlet of the Lower Duwamish Waterway at RM 2.2.  Di‐n‐butyl phthalate. Underneath the Spokane Street Bridge in the East Waterway. Bis(2‐ethylhexyl)phthalate had the second most frequent exceedances of the CSLs in the Lower Duwamish Waterway. PCBs had the most exceedances (see below).

Scattered detections of SQS exceedances for bis(2‐ethylhexyl)phthalate and butyl benzyl phthalate occurred in the Lower Duwamish Waterway from RM 0.3 to RM 1.8 and in the East Waterway 0.3 km upstream of Slip 27.

Chlorobenzenes Four chlorobenzenes exceeded the CSL in the Lower Duwamish and East waterways (Appendix D): 1,2‐dichlorobenzene, 1,4‐dichlorobenzene, hexachlorobenzene, and 1,2,4‐ trichlorobenzene. The distribution of each chlorobenzene was localized. Only 1,4‐ dichlorobenzene exceeded the CSL in the East Waterway (0.3 km upstream of Slip 27). SQS exceedances were detected closer to Slip 27. In the Lower Duwamish Waterway, 1,2‐ dichlorobenzene, 1,4‐dichlorobenzene, and 1,2,4‐trichlorobenzene exceeded the CSLs in the west inlet at RM 2.2 and hexachlorobenzene exceeded the CSL south of Slip 4 from RM 3.0 to RM 3.1.

Polychlorinated Biphenyls Total PCBs had the most SMS exceedances of any chemical in both the Lower Duwamish and East waterways. Exceedances of the CSL occurred throughout these two waterways (Appendix D). Only four sections of the Lower Duwamish Waterway did not have an SMS exceedance: RM 1.5 to RM 1.6, RM 3.3 to RM 3.4, RM 4.0 to RM 4.1, and RM 4.3 to RM 4.5.

Total PCBs exceeded the CSL at the Lockheed West Seattle site. The exceedances were detected 75 m to 250 m northeast of the corner shoreline in the area of the former dry docks and West Waterway navigation channel. Exceedances of the SQS were detected along the eastern border of the site between land and the navigation channel.

4.3 Green River Watershed

From 2008 through 2012, King County collected 58 samples to characterize sediment chemical concentrations in small, wadeable tributary streams in the Green River watershed. This assessment was designed to investigate the relative differences of sediment quality between tributary basins and the Green River and the potential contaminant loading into the Duwamish River (King County, 2014b). Sediment chemistry concentrations were compared to freshwater SCO criteria in the SMS, Chapter 173‐204 WAC (Ecology, 2013a).

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Of the 58 samples collected, 24 exceeded the SCO for one or more contaminants but never exceeded the CSL. Six contaminants exceeded the SCO: bis(2‐ethylhexyl) phthalate in 16 samples, arsenic in 13 samples, nickel in 7 samples, cadmium in 4 samples, di‐n‐octyl phthalate in 3 samples, and total PCBs in 2 samples. There were no exceedances in the Green River main stem.

In general, the more urbanized tributary basins (Springbrook Creek, Mill Creek in Kent, and Mill Creek in Auburn) had higher concentrations of metals and organics and SMS exceedances compared to the lesser developed tributary basins and the Green River main stem (King County, 2014b).

4.4 Sediment Toxicity

Surface sediments (0 cm to 10 cm) were collected for toxicity analysis at 48 locations in the East Waterway during the East Waterway SRI (Windward and Anchor QEA, 2014) and 48 locations in the Lower Duwamish Waterway during the Lower Duwamish RI (Windward 2010). Three toxicity tests were conducted on each sediment sample:  Acute 10‐day amphipod (Eohaustorius estuarius) survival test  Acute 48‐hour bivalve larvae (Mytilus galloprovincialis) normal survival test  Chronic 20‐day juvenile polychaete (Neanthes arenaceodentata) survival and growth test Biological responses from these site‐specific sediment toxicity tests were compared to the SMS:  In the Lower Duwamish Waterway, 18 of the 48 sediment samples (37.5 percent) did not exceed the SQS biological effects criteria, 11 sediment samples (22.9 percent) exceeded the SQS biological effects criteria but not the CSL biological effects criteria, and 19 samples (39.6 percent) exceeded the CSL biological effects criteria (Windward, 2010).  In the East Waterway, 40 percent of the area did not exceed the SQS. Adverse effects were predicted (exceeded the CSL) for 21 percent of the area. The remaining 39 percent of the area exceeded the SQS but not the CSL, indicating the potential for minor adverse effects to the benthic community (Windward and Anchor QEA, 2014).

4.5 Benthic Invertebrates

Benthic Invertebrates were monitored in the Duwamish Estuary in 1994, 1996, and 1999 (Cordell et al., 1994 and 1996; King County, 1999). The three studies collected samples near Kellogg Island and compared benthic community results to other areas in the estuary. In addition, Cordell et al. (1994 and 1996) collected samples from the turning basin and King County (1999) also collected samples near the Duwamish/Diagonal CSO‐storm drain. Samples near the Duwamish/Diagonal CSO‐stormdrain were collected in the area that was subsequently dredged and capped as part of the Duwamish/Diagonal sediment remediation project.

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Results from Cordell et al. (1994 and 1996) showed that Kellogg Island sites had high numbers of species, high abundances, and high diversity as compared to the turning basin sites. These results prompted researchers to use the Kellogg Island site as a reference when assessing benthic invertebrates in the estuary.

King County used Kellogg Island as a reference in 1999, which also showed high numbers of species, high abundances, and high species diversity in comparison to the samples collected near the Duwamish/Diagonal CSO‐stormdrain prior to the sediment remediation project. These results indicate that Kellogg Island serves as an important benthic habitat in the Duwamish Estuary.

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5.0 TISSUE QUALITY Animal tissue contamination in the Duwamish Estuary results from exposure to contaminated water and sediment or through consumption of contaminated prey. While much of the contamination originates from historical industrial uses of the estuary, multiple sources of urban pollutants remain. This chapter summarizes tissue contamination data for organic compounds and select metals that were identified as risk drivers in the human health and ecological risk assessments for the Lower Duwamish and East waterways (see Chapter 6).

5.1 Data Sources and Limitations

The characterization of tissue contamination is limited to fish and shellfish tissue data from Superfund cleanup areas in the Lower Duwamish, East, and West waterways. Only limited data are available for the West Waterway. Tissue contamination data collected from the Duwamish River and Green River are too limited to include in the characterization.

Data sources are as follows:  Final Lower Duwamish Waterway remedial investigation report (Windward, 2010).  Final supplemental remedial investigation report for the East Waterway Operable Unit (Windward and Anchor QEA, 2014).  Waterway Sediment Operable Unit Harbor Island Superfund Site. Tributyltin in Marine Sediments and the Bioaccumulation of Tributyltin: Combined Data Report (EVS. 1999).

The sources include tissue contamination data for multiple resident species including fish, crab, bivalves, and other benthic invertebrates. The data represent the integration of 9 sampling years across 16 total years (1992 through 2007) and include the analysis of tissues from 14 different species, each represented by one or more of three different tissue types. Analyzed contaminants include PCBs (Aroclors and congeners), arsenic (total and inorganic), 8 metals, 21 organochlorine pesticides, 30 SVOCs, and 7 volatile organic compounds (VOCs).

All data underwent systematic data quality assessments prior to inclusion. Although extensive and comprehensive, these data do not reflective current conditions. The majority of the data were collected from 2004 through 2007. No additional studies have reported newer tissue contaminant data.

The following sections summarize data for PCBs, dioxins and furans, cPAHs, arsenic, and TBT. In order to compare across all species, tissue types, and contaminants, mean tissue contaminant concentrations are reported across multiple collection efforts, methods, and years.

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5.2 Polychlorinated Biphenyls

PCBs were detected in most tissue samples in both the Lower Duwamish and East waterways. All samples were analyzed for PCB Aroclors. A subset of samples was analyzed for PCB congeners. Total Aroclor and congener concentrations were higher in 2004 than in 2005–2007. Higher PCB congener levels were reported in the later years. Reductions in total concentrations coincident with increases in congener levels may indicate PCB weathering but could also result from exposure of fish and other mobile species to different areas with different PCB mixtures over the years.

High variance in PCB concentrations was observed in species with a small or fixed home range (rockfish, clams, benthic invertebrates) compared to species with large home ranges (English sole, perch, crab). This variation is thought to be linked predominantly to spatial variation in sediment contamination levels, especially in the Lower Duwamish Waterway where localized areas of high contaminant concentrations are more common. In the East Waterway where PCBs are more evenly distributed, clams and mussels had lower mean total PCB Aroclor concentrations than in the Lower Duwamish Waterway. The West Waterway had the lowest PCB concentrations for all species sampled.

In both the Lower Duwamish and East waterways, juvenile Chinook salmon showed low concentrations of total PCB Aroclors compared to other fish. Juvenile Chinook are a migratory species and are not expected to contain PCBs at levels as high as in resident fish because of the short exposure period. They spend only a few weeks to a few months of their lives migrating through the Duwamish Estuary to Puget Sound and the Pacific Ocean.

The highest observed mean concentration of total PCB Aroclors for an individual species was seen in East Waterway English sole whole body (3,200 µg/kg wet weight [ww]; n = 13) (Table 5‐1). Concentrations in East Waterway brown rockfish whole body and Lower Duwamish Waterway Dungeness crab hepatopancreas were also high (2,000 µg/kg ww; n = 15 and 11, respectively). The lowest mean total PCB Aroclor concentrations were in East Waterway geoduck (24 µg/kg ww) and Lower Duwamish Waterway mussels (27 µg/kg ww).

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Table 5-1. Total PCB Aroclor concentrations (µg/kg wet weight) by tissue type in fish tissue from the Lower Duwamish, West, and East waterways (2004–2007).

Fish Species Tissue Type FOD Minimum Maximum Mean West Waterway Striped perch Fish filet (with skin) 3/3 72 184 136 Striped perch Fish filet (without skin) 3/3 65.5 121 94 English sole Fish filet (without skin) 3/3 263 462 336 Red rock crab Crab edible meat 3/3 35 63 51 East Waterway Brown rockfish Fish whole body 15/15 400 J 6,200 2,000 English sole Fish whole body 13/13 1,460 7,900 J 3,200 Juvenile Chinook salmon Fish whole body 12/12 7.4 91.5 59 Sand sole Fish whole body 5/6 167 1,310 540 B Shiner surfperch Fish whole body 11/11 380 J 5,400 1,500 English sole Fish fillet (with skin) 20/20 409 5,700 1,700 Striped perch Fish fillet (with skin) 6/6 104 203 J 155 Dungeness crab Crab edible meat 12/12 48 J 210 J 130 Dungeness crab Crab hepatopancreas 9/9 310 J 1,900 590 Intertidal clam Clam whole body 11/11 4.7 J 82 56 Mussel Whole body 14/17 19 J 26 44 J Shrimpa Whole body 1/1 460 J na 460 J Geoduck clam Edible meat 6/6 14 19 24 J Geoduck clam Gutball 3/3 51 J 66 78 Benthic invertebrates Whole body 13/13 93 210 380 Lower Duwamish Waterway Juvenile Chinook salmon Fish whole body 24/24 6.9 1,200 140 English sole Fish whole body 67/67b 300 4,700 1,700 Shiner surfperch Fish whole body 78/78 200 J 18,400 J 1,300 Starry flounder Fish whole body 6/6 156 660 380 Pacific staghorn sculpin Fish whole body 28/28 430 2,800 900 English sole Fish fillet (with skin) 26/26 170 2,010 860 English sole Fish fillet (no skin) 15/15 79 530 230 Starry flounder Fish fillet (with skin) 2/2 63 450 260 Striped perch Fish fillet (with skin) 3/3 164 J 630 J 320 Pile perch Fish fillet (with skin) 1/1 300 300 300 Dungeness crab Crab edible meat 14/17 15 300 130 Red rock crab Crab edible meat 2/2 85 J 164 J 120 Red rock/Dungeness crab Crab edible meat 1/1 60 J 60 J 60 Slender crab Crab edible meat 19/19 27 390 150 Dungeness crab Crab hepatopancreas 11/11 280 5,500 2,000 Slender crab Crab hepatopancreas 11/11 250 2,190 J 940 Clams (non-depurated) Clam whole body 20/20 15 J 580 J 130 Clams (depurated) Clam whole body 6/6 14 J 270 98 Mussels (wild) Clam whole body 18/22 16 60 34 Mussels (transplanted) Clam whole body 13/32 25.9 73.1 27 Amphipods Whole body 4/4 106 410 230 Benthic invertebrates Whole body 19/20 60 J 1,400 270 FOD = frequency of detection; J = estimated concentration. a A shrimp sample is one composite of 26 individuals collected from multiple shrimp traps. b Number of samples includes 32 whole‐body samples and 10 calculated whole‐body samples. Concentrations in whole‐body samples were estimated using results from separate analyses of fillet and remainder composite samples (all remaining tissue and fluids after fillets were removed from the specimens). The estimated English sole whole‐body concentrations were based on the relative weights and total PCB concentrations in skin‐on fillet and remainder tissues collected in 2005.

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When grouped by tissue type and waterway, East Waterway fish whole body tissues were highest in mean concentration of total PCB Aroclors (1,690 µg/kg ww), followed by Lower Duwamish Waterway crab hepatopancreas (1,470 µg/kg ww) (Figure 5‐1). Lower Duwamish Waterway fish whole body and all fish fillet tissues were intermediate in mean total PCB Aroclors (394 µg/kg ww to 928 µg/kg ww). Crab edible meat and clam whole body were lowest in mean total PCB Aroclors in both waterways (35 µg/kg ww to 130 µg/kg ww).

2000

Lower Duwamish Waterway 1500 East Waterway

1000 West Waterway

500

0 Fish Crab Fish Benthic Crab Clam Whole Body Hepatopancreas Fillet Invertebrates Edible Meat Whole Body

Figure 5-1. Mean concentrations of PCB Aroclors by tissue type in fish tissue in the Lower Duwamish, West, and East waterways. Mean total PCB Aroclor contamination levels in benthic invertebrate tissues were similar between the Lower Duwamish Waterway (250 µg/kg ww) and East Waterway (210 µg/kg ww). Benthic invertebrates play an important role in the mobility of PCBs across trophic levels. They are vital prey for many other species and inhabit, forage in, and, in some cases, directly consume contaminated sediments in the waterways.

In both waterways, fish whole body tissues were most highly contaminated with PCBs. Crab hepatopancreas tissues also had high concentrations. Concentrations in fish fillet tissues were generally half the concentrations in whole body tissues. Crab edible meat tissues had half to one‐tenth the concentrations of crab hepatopancreas tissues. In terms of variability between the Lower Duwamish and East waterways, concentrations of PCBs in fish whole body, fish fillet, and crab hepatopancreas tissues varied more between the waterways than did concentrations in benthic invertebrates, edible crab meat, and clam whole body.

5.3 Dioxin and Furans

Dioxins and furans were not analyzed in the Lower Duwamish Waterway. In the East Waterway, dioxins and furans were analyzed in super‐composite tissue samples created by

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combining all existing samples for a given species across all locations. Mean dioxin and furan toxicity equivalents (TEQs) were highest for fish and crab hepatopancreas, intermediate for crab whole body and edible meat, and low for clam and geoduck.

5.4 Carcinogenic Polycyclic Aromatic Hydrocarbons

At least one cPAH was detected in most samples analyzed from the Lower Duwamish and East waterways. cPAH concentrations ranged from 0.35 µgTEQ/kg ww to 130 µgTEQ/kg ww in the Lower Duwamish Waterway and from 0.29 µgTEQ/kg ww to 170 µgTEQ/kg ww in the East Waterway. In both waterways, cPAHs were found at higher levels in benthic invertebrates and bivalves than in fish and crab. Concentrations in fish and crab were more variable than in the other species. Although a single Pacific staghorn sculpin represented the highest observed cPAH value, this detection was unusual (frequency of detection = 1/24). Lower contamination levels in fish and crab tissue may be the result of their greater ability to metabolize cPAHs more quickly than bivalves and benthic invertebrates (Varanasi and Gmur, 1980).

5.5 Arsenic

Total arsenic was detected in all tissue samples. Mean total arsenic concentrations ranged from 0.99 mg/kg ww to 6.803 mg/kg ww in the Lower Duwamish Waterway and from 0.44 mg/kg ww to 5.24 mg/kg ww in the East Waterway. Elevated arsenic levels were variable and not associated with a specific group such as fish, bivalves, crab, or benthic invertebrates.

Inorganic arsenic, which is the most toxic form of arsenic to humans and a known carcinogen, was measured on a subset of tissue samples. In both the Lower Duwamish and East waterways, inorganic arsenic concentrations in most tissues were very low, with the exception of clams in the Lower Duwamish Waterway (up to 3.37 mg/kg ww). With the exception of eastern softshell clams from the Lower Duwamish Waterway, inorganic arsenic concentrations in Lower Duwamish and East waterway tissue samples were similar to or lower than those in samples collected from Puget Sound reference areas (Windward, 2010; Windward and Anchor QEA, 2014)

Clams had the highest ratio of inorganic‐to‐total arsenic of all tissues analyzed (55 percent in the Lower Duwamish Waterway and 11 percent in the East Waterway). In Puget Sound, ratios in clams are typically 1.2 percent and lower (Ecology, 2002).

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5.6 Tributyltin

TBT was detected in most tissue samples collected in the Lower Duwamish, East, and West waterways:  In the Lower Duwamish Waterway, concentrations were highest in soft shelled clams (mean of 0.32 mg/kg ww) and lowest in crab and fish fillet tissues.  In the East Waterway, TBT was not detected in half the English sole fillet samples, one crab hepatopancreas sample, all crab edible meat, and all juvenile Chinook; concentrations were highest in brown rockfish and benthic invertebrate tissue (mean of 0.160 mg/kg ww and 0.110 mg/kg ww, respectively), and lowest in crab hepatopancreas, English sole, striped perch fillet, and geoduck.  In the West Waterway, mean concentrations were highest in striped perch fillets (0.01 mg/kg ww) and lowest in crab tissue samples (0.001 mg/kg ww).

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6.0 HUMAN HEALTH AND ECOLOGICAL RISKS This chapter summarizes the results of human health and ecological risk assessments conducted for Superfund sites in the Lower Duwamish Waterway and East Waterway. No risk assessments were summarized for the West Waterway because the data do not reflect current conditions.

6.1 Data Sources

Data sources for the risk assessment summary in this chapter are as follows:  Final remedial investigation report for the Lower Duwamish Waterway (Windward, 2010).  Final feasibility study report for the Lower Duwamish Waterway (AECOM, 2012).  Final supplemental remedial investigation report for the East Waterway Operable Unit (Windward and Anchor QEA, 2014).

6.2 Human Health Risk

The baseline human health risk assessments estimated the risks of cancer and non‐cancer to people exposed to contaminants in water, sediment, and seafood tissue in the Lower Duwamish and East waterways.12 Multiple exposure scenarios were investigated including water contact (swimming), sediment contact (net fishing, clamming, habitat restoration, and beach play), and seafood consumption.

The seafood consumption models are the most diverse. They address multiple populations with different consumption rates and different approaches to risk calculation (reasonable maximum exposure, central tendency, and unit exposure):  Reasonable maximum exposure (RME) models use high but plausible consumption rates that tend to overestimate risks for most people. These models are favored in regulatory decision‐making (EPA, 1989).  Central tendency models use typical consumption levels that characterize the average risk. These models do not take into account that a substantial number of people will consume more than average amounts of contaminated seafood.  Unit exposure models calculate risks for a single seafood meal, allowing individuals to estimate personal risk based on a number of seafood meals consumed per month.

12 Non‐cancer risks refer to impacts to the immunological, neurological, integumentary, or other systems. The integumentary system consists of the skin, hair, nails, glands, and nerves. Its main function is to act as a barrier to protect the body from the outside world. It also functions to retain body fluids, protect against disease, eliminate waste products, and regulate body temperature.

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These models are useful in cases where sub‐populations with different consumption rates obtain seafood from the same source. The sub‐populations for the Lower Duwamish and East waterways include adults, children, Asian Pacific Islanders, and American Indian tribal members. The following summary of human health risks focuses on RME scenarios because they are conservative and commonly used for regulatory decision‐making. RME models produce high estimates of excess cancer risk based on exposure point concentrations set to 95 percent upper confidence limits of observed mean water, sediment, and tissue contamination levels. The calculated impact represents the integration of the consumption of multiple species over a fixed interval of time.

Estimated excess cancer risks and non‐cancer hazards in the Lower Duwamish and East waterways from seafood consumption are shown in Table 6‐1. The cumulative excess cancer risk for all RME seafood consumption rates for all sub‐populations ranges from 7 in 10,000 to 3 in 1,000 in the Lower Duwamish Waterway and 4 in 10,000 to 1 in 1,000 in the East Waterway. Unit exposure models (based on one meal a month) identified fish and clam (Lower Duwamish Waterway) and rockfish (East Waterway) consumption as having the highest risk potential; crab has the lowest. The evaluation of non‐cancer effects indicates the potential for adverse effects in humans, particularly for PCBs.

Table 6-1. Excess cancer risk and non-cancer hazards in humans from consumption of seafood from the Lower Duwamish and East waterways.

Ingestion Exposure Excess Non-Cancer RME Model Meals per Age Rate Duration Cancer Hazard Type Month (grams/day) (years) Risk (HQ = 1)b

Lower Duwamish Waterway Adult Tribala 97.5 13.1 70 3 in 1,000 40 Child Tulalip Tribe 39.0 5.2 6 7 in 10,000 86 Asian Pacific 29 Adult 51.5 6.9 30 1 in 1,000 Islander East Waterway Adult Tulalip Tribe 97.5 13.1 70 1 in 1,000 17 Child Tulalip Tribe 39.0 5.2 6 4 in 10,000 7.8 Asian Pacific 24 Adult 51.5 6.9 30 6 in 10,000 Islander RME = reasonable maximum exposure. HQ = hazard quotient; an HQ equal to or great than 1 indicates a potential risk for non-cancer effects. a Tribal RME was based on Tulalip tribal seafood consumption information. b Non-cancer hazard for PCBs only.

The following excess cancer human‐health risks were identified for the Lower Duwamish Waterway:

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 The majority of risks are from consumption of PCBs in resident fish, crabs, and clams and from inorganic arsenic in clams. Lower risks were found for cPAHs from consumption of clams.  No seafood consumption risks were calculated for dioxins and furans because these compounds were not analyzed in tissues from the Lower Duwamish Waterway. However, the risk assessment assumed there would be unacceptable risk from dioxins and furans.  Risks associated with direct contact with sediment (both incidental ingestion and skin contact) are lower compared to those from consumption of resident seafood. The risks are associated with activities such as tribal clamming, child beach play, and tribal net fishing.  Most of the direct contact risks during tribal clamming or net‐fishing are from dioxins and furans.  The majority of risks to young children during beach play were from cPAHs, mainly because they are more toxic to young children than to adults. The following human‐health risks were identified for the East Waterway:  The majority of risks are from consumption of PCBs in resident fish, crabs, and clams. Lower risks were found for inorganic arsenic and cPAHs from the consumption of clams and for dioxins and furans from the consumption of clams, crabs, and, to a lesser extent, resident fish.  Risks associated with direct contact with sediment (both incidental ingestion and skin contact) are lower compared to those from consumption of resident seafood. Risks are associated with activities such as tribal clamming and net fishing. Most of the risks are from contact with arsenic and cPAHs.

6.3 Ecological Risk

Benthic Community The SMS SQS were used in the ecological risk assessments to identify contaminants of concern (COC) for the benthic invertebrate community in the Lower Duwamish and East waterways. Contaminants with concentrations that exceeded the SQS in one or more surface sediment samples were identified as COCs for each waterway. (See Chapter 4 and Appendix D for areas with SQS exceedances.)

For the Lower Duwamish Waterway, 41 contaminants exceeded the SQS and were selected as COCs for benthic invertebrates. The potential for adverse effects to benthic invertebrates in areas of the Lower Duwamish Waterway are as follows (AECOM, 2012):  Minor adverse effects could occur in approximately 18 percent (80 acres) of the waterway where SQS were exceeded.  The CSL was exceeded in 16 acres of the total 80 acres (approximately 4 percent of the waterway), also indicating minor adverse effects.

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 Adverse effects are not expected in the remaining area (approximately 82 percent of the waterway). Contaminants in surface sediments were below the SQS. For the East Waterway, 30 COCs were identified for benthic invertebrates. The potential for adverse effects to benthic invertebrates in areas of the East Waterway are as follows:  Adverse effects are not expected in approximately 40 percent of the East Waterway (69 acres). Concentrations of COCs in surface sediments were less than the SQS and showed no adverse effects during bioassay toxicity testing.  Minor adverse effects are predicted in approximately 21 percent of the East Waterway (36 acres), which had contaminant concentrations in excess of the CSL or biological effects during toxicity testing.  Potential minor adverse effects are also expected in the remaining 39 percent of the East Waterway (67 acres) where contaminant concentrations or biological effects were between the SQS and CSL.  Tissue‐residue results indicate there is a potential risk from TBT to benthic invertebrates in two areas of the East Waterway because tissue concentrations were above toxicity reference values for tissue. Based on this assessment, TBT was identified as a COC.

Fish and Wildlife Communities A risk‐based screening process was used to identify the chemicals most likely to impact receptors of concern in the Lower Duwamish and East waterways. Receptors of concern are a limited set of species chosen to indicate ecological risk to all species in the waterways and to help determine the remediation criteria for specific contaminants (Table 6‐2).

Table 6-2. Receptors of concern in the Lower Duwamish and East waterways.

Trophic Level Lower Duwamish Waterway East Waterway

Base level Benthic invertebrates Benthic invertebrates (decomposers and herbivores) Juvenile Chinook Juvenile Chinook Crab Crab Intermediate level English sole English sole (omnivores and carnivores) Pacific staghorn sculpin Brown rockfish Spotted sandpiper Pigeon guillemot Osprey Osprey Top level Great blue heron River otter (top carnivores) River otter Harbor seal Harbor seal

The ecological risk associated with the consumption of contaminated tissues was assessed independently for each receptor of concern against individual chemicals of potential

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concern (COPCs) based on tissue residue or dietary exposure models.13 Tissue residue models predict adverse effects by measuring chemical concentrations in receptor tissues; dietary exposure models predict adverse effects by estimating receptor consumption of contaminated tissues. While tissue residue evaluation can identify contaminants in tissues at levels that may result in adverse effects (identification of risk drivers), this method differs from dietary models in that the significant route of exposure leading to the observed tissue residue is unspecified. Dietary based risk drivers implicate contamination in prey consumed; tissue residue risk drivers leave uncertain the significant route of exposure.

Ecological risk to benthic invertebrates through exposure to contaminated sediments in the Lower Duwamish Waterway was assessed for all COPCs except TBT. TBT was assessed using both tissue residue and direct measure of gastropods in the field. Seven chemicals were identified as COCs for the Lower Duwamish Waterway because of their potential to produce adverse impacts in at least one receptor of concern: cadmium, chromium, copper, lead, mercury, PCBs, and vanadium. The level of ecological risk from dioxins and furans is unknown because these compounds were not analyzed in tissues from the Lower Duwamish Waterway. Only PCBs were identified as a risk driver (Table 6‐3), with potential adverse effects to river otters through dietary exposure. The risk potential for crab, fish, and birds was considered similar to background and more uncertain when compared to that for river otters.

Seven chemicals were identified as COCs for the East Waterway: cadmium, copper, naphthalene, PCBs, TBT, vanadium, and zinc. Based on tissue residue assessment, total PCBs were selected as a risk driver for English sole and brown rockfish and TBT was selected as a risk driver for benthic invertebrates (Table 6‐3). No COCs were identified for birds and mammals; COCs identified for fish (except PCBs) and crab were not classified as risk drivers.

Table 6-3. Ecological risk drivers for receptors of concern in the Lower Duwamish and East waterways. Risk Driver Evaluation Receptor of Concern Lower Duwamish Model East Waterway Waterway Benthic Invertebrates Tissue residue None Tributyltin (TBT) Crab Tissue residue None None Fish Tissue residue None PCBs Fish Dietary exposure None None Birds Dietary exposure None None Polychlorinated Mammals (river otter) Dietary exposure None biphenyls (PCBs)

13 COPCs are constituents detected in environmental media (soil, groundwater, air, sediment) at concentrations above risk‐based screening levels and background. Nondetected constituents that have detection limits higher than the screening values may also be considered as COPCs.

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7.0 FINDINGS The findings of this analysis are intended to provide useful scientific information on most recent water, sediment, and aquatic species tissue quality conditions and long‐term water quality trends in the Green‐Duwamish area. General findings are as follows:  The main water quality issues in the Duwamish Estuary are high bacteria concentrations and high temperatures in some surface waters in the summer. Dissolved oxygen levels have increased over time, with some potential issues in the Lower Green River. No samples exceeded the aquatic life water quality criteria for metals and semivolatile organic compounds. PCB congeners were the only compounds that exceeded EPA’s Ambient Water Quality Criteria for the protection of Human Health. More data are needed on the seasonal and spatial variability of these compounds in the study area in order to fully evaluate their impact.  Sediments in the Duwamish Estuary are contaminated as the result of historical and current industrial, commercial, and private activities. The majority of the SMS exceedances occur in the Lower Duwamish and East waterways and in an isolated area in the West Waterway at the Lockheed West Seattle site.  Most contaminants commonly identified in water and sediments of the Duwamish Estuary are also found in resident fish and shellfish tissue. Because of elevated contaminants found in fish and shellfish tissue from the Lower Duwamish and East waterways, the Washington State Department of Health has issued fish consumption advisories for the Duwamish Estuary. Monitoring of fish and shellfish tissue will occur as part of the Superfund cleanup process for these waterways. The following sections provide more detail on these findings.

7.1 Water Quality

Current water quality conditions were evaluated using the most recent monthly and bi‐ monthly data from King County and Ecology long‐term monitoring programs. When more than 20 years of data were available, trends were evaluated. The analysis was based on data from discrete samples. Little or no continuous data were available. Upstream data collected from the Duwamish and Green rivers as far as the Howard A. Hanson Dam about 64 miles upstream of the mouth of the system were included to the extent they inform conditions in the Duwamish Estuary. The entire area, including the estuary, is called the Green‐Duwamish area.

Major water quality findings are as follows:  Bacteria. Elevated bacteria concentrations (as measured by fecal coliforms) are a persistent water quality concern in the Green‐Duwamish area. Concentrations were typically highest in the Lower Duwamish Waterway and decreased moving upstream. Frequent exceedances of water quality criteria upstream and downstream of CSOs have occurred. Despite exceedances, it appears that bacteria concentrations have declined in the last 20 to 30 years. CSO control and improved

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stormwater management may have contributed to this decline. Other sources of bacteria need to be identified and mitigated in order to further enhance water quality and protect human health.  Temperature. The analysis indicates that the lower and middle sections of the Green River are more likely to exceed temperature standards for salmonids than downstream and upstream locations. The Duwamish Estuary remains relatively cool because of the influence of Puget Sound, and reaches of the Green River farther upstream are cooler because land cover is predominantly forest. Trend analysis showed significant increasing long‐term temperature trends in the West Waterway. No significant trends were observed at other sampling locations.  Dissolved oxygen. Generally, DO concentrations have increased in the Duwamish Estuary and the lower Green River in the last 40 years, yet these reaches are more likely to violate DO criteria for salmonids than upstream reaches of the Green River. No significant or substantial trends were observed for upstream sites in the Green River.  Nutrients. Nutrient concentrations in the Duwamish Estuary are affected by inputs from CSOs, stormwater, upstream locations, and internal cycling. Trend analysis found that phosphorus, nitrogen, and ammonia concentrations have generally decreased or remained stable in the last 20 to 30 years, indicating that loading has decreased or stayed the same. For ammonia, orthophosphate, and total phosphorus, greater rates of decrease in the Duwamish Estuary suggest decreased internal loading.  Metals. Overall, ambient water in the Green‐Duwamish area did not exceed the Washington State water quality criteria for aquatic life or EPA’s recommended Human Health Criteria for metals. Total metals concentrations varied. The metals with the highest detection frequencies were aluminum, arsenic, barium, calcium, copper, magnesium, manganese, nickel, sodium, vanadium, and zinc. Dissolved metals were detected at a lower frequency than total metals.  Organic compounds. No organophosphorus pesticides were detected. One chlorinated herbicide (triclopyr) was detected in a single sample. PAHs were detected frequently. Various other organic compounds were detected infrequently. PCB congeners were detected from all samples taken. Total PCB concentrations measured by congener analysis exceeded the Human Health Criteria in 66 of 72 samples. Two samples exceeded the Human Health Criteria for bis(2‐ ethylhexyl)phthalate: one collected in the East Waterway and one collected at the downstream end of the Lower Duwamish Waterway. Most of the older samples typically had detection limits above many of the chronic water quality criteria for the protection of aquatic life or the recommend Human Health Criteria and had higher frequencies of blank contamination.

7.2 Sediment Quality

Localized areas in the Lower Duwamish and East waterways exceeded the marine benthic sediment standards for metals including arsenic, copper, lead, and zinc; PAHs; and

King County 7‐2 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary phthalates (bis[2‐ethylhexyl] phthalate and butyl benzyl phthalate). Most exceedances occurred within 50 m of the shoreline. Phthalates, in particular bis(2‐ethylhexyl) phthalate, also exceeded standards north and south of the inlet of Slip 27 in the East Waterway and between RM 4.8 and RM 5.0 in the Lower Duwamish Waterway. Another organic chemical, 1,4‐dichlorobenzene, was detected in a number of samples in the East Waterway and exceeded standards just upstream of Slip 27.

Mercury and total PCBs exceeded the marine benthic sediment standards throughout the Lower Duwamish and East waterways The East Waterway had a higher frequency of mercury exceedances than the Lower Duwamish Waterway. Even though the production of PCBs has been banned in the United States since 1979, the wide use of PCBs or PCB‐ containing products in the past has caused much contamination in the two waterways.

7.3 Tissue Chemistry

Major tissue chemistry findings are as follows:  In the Lower Duwamish and East waterways, PCBs, PAHs, and metals were the most abundant contaminants measured in tissue. PAHs were highest in clams, mussels, and benthic invertebrates from numerous locations. Total arsenic was detected in all tissue samples; inorganic arsenic concentrations were highest in clams. Total PCB concentrations were highest in Dungeness crab hepatopancreas, English sole, and shiner surfperch; low concentrations were found in clams and mussels. The West Waterway had the lowest total PCB concentrations of all locations sampled.  Most other organic chemicals were infrequently detected from the Lower Duwamish and East waterways. In the East Waterway, concentrations of dioxins and furans were higher in fish and crab hepatopancreas and lower in crab muscle, clams, and geoducks. Dioxins and furans were not sampled in Lower Duwamish Waterway locations.

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8.0 LITERATURE CITED

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Tanner, C.D. 1991. Potential intertidal habitat restoration sites in the Duwamish River Estuary. EPA 910/9‐91‐050. U.S. Environmental Protection Agency, Region 10, Seattle, WA.

Tetra Tech. 2012. Final RI/FS for the Lockheed West Superfund Site. Seattle, Washington.

Tollefson, J. 2014. Climate change: The case of the missing heat. Nature 505:276–278.

Varanasi, U., and D.J. Gmur. 1980. Metabolic activation and covalent binding of benzo(a)pyrene to deoxyribonucleic acid catalyzed by liver enzymes of marine fish. Biochem. Pharmacol. 29:753–761.

WDOH. 2006. Human health evaluation of contaminants in Puget Sound fish. Publication No. 334‐104. Washington State Department of Health, Division of Environmental Health, Olympia, WA.

Welch, E.B. 1969. Factors Initiating phytoplankton blooms and the resulting effects on dissolved oxygen in the Duwamish River Estuary Seattle, Washington. U.S. Department of Interior, Geological Survey. Washington, DC.

Wenning, R.J., G.E. Batley, C.G. Ingersoll, and D.W. Moore (eds.). 2005. Use of sediment quality guidelines and related tools for the assessment of contaminated sediments. Setac Press.

Weston. 1993. Harbor Island remedial investigation report. Prepared for U.S. Environmental Protection Agency, Region 10. Roy F. Weston, Inc., Seattle, WA.

Weston. 1999. Site inspection report, Lower Duwamish River (RK 2.5‐11.5), Seattle, Washington. Volume 1 ‐ Report and appendices. Prepared for U.S. Environmental Protection Agency, Region 10. Roy F. Weston, Inc., Seattle, WA.

Wilma, David (2001‐01‐29). Descendants of pioneers reverse the stand of their ancestors and support federal recognition of the Duwamish tribe on June 18, 1988. HistoryLink.org Essay 2956. Retrieved 7‐21‐2006.

Windward. 2008. East Waterway human access survey report. Windward Environmental, LLC, Seattle, WA.

Windward. 2009. East Waterway Operable Unit Supplemental Remedial Investigation/ Feasibility Study Final Surface Water Data Report. Seattle, WA.

Windward and QEA. 2008. Lower Duwamish Waterway sediment transport analysis report. Final. Prepared for Lower Duwamish Waterway Group. Quantitative Environmental Analysis, LLC, Montvale, NJ.

Windward. 2010. Lower Duwamish Waterway remedial investigation report. Final. Prepared

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for Lower Duwamish Waterway Group for submittal to U.S. Environmental Protection Agency, Region 10, Seattle, WA. http://ldwg.org/rifs_docs8.htm.

Windward and Anchor QEA. 2014. East Waterway Operable Unit: Supplemental remedial investigation/feasibility study. Final supplemental remedial investigation report. Prepared for East Waterway Group for submittal to U.S. Environmental Protection Agency, Region 10, Seattle, WA.

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APPENDIX A: GLOSSARY aerobic Living in the presence of oxygen. algae Mostly aquatic, non-vascular organisms (eukaryotes and cyanobacteria) that float in the water or attach to larger plants, rocks, and other substrates. Also called phytoplankton when floating In the water, these individuals are usually visible only with a microscope. They are a normal and necessary component of aquatic life, but excessive numbers can make the water appear cloudy and colored, which may discourage human use. algal bloom Heavy growth of algae or cyanobacteria in and on a body of water, often a result of high nutrient concentrations when occurring frequently but blooms can also be a normal occurrence. Decomposition of algae following blooms can cause reductions in oxygen that may threaten fish and other aquatic animals. alkalinity Acid-neutralizing or buffering capacity of water. It is primarily a function of the carbonate, bicarbonate, and hydroxide content in water. The lower the alkalinity, the less capacity the water has to neutralize acids without lowering pH and becoming more acidic. ammonia (NH3) A nitrogen-containing substance that may indicate recently decomposed plant or animal material. anaerobic Living in the absence of oxygen. anoxic No oxygen present in the system; see anaerobic.

Aroclors One of the most commonly known trade names for PCB mixtures. benthic Associated with the sediments of a waterbody; often used to describe the community of organisms (benthos) that live in or on the sediment. benthic See Invertebrates. invertebrates benthos The communities of aquatic life that dwell in or on the bottom sediments of a waterbody. bioaccumulation Accumulation of chemicals in the tissue of organisms through any route, including respiration, ingestion, and direct contact with contaminated water, sediment, and pore water in the sediment. blank Artificially introduced contamination. Blank contamination (chemical demonstrated contamination as present when it should not be) of a sample indicates that other samples analyzed in the same batch may possess false positives. censoring In statistics, a condition in which the value of a measurement or observation is only partially known.

King County A‐1 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary chlorophyll A green pigment found in organisms that make their own food, including algae. It plays an important part in the chemical reactions of photosynthesis. A measurement of chlorophyll a (one form of chlorophyll) is commonly used to estimate the abundance of phytoplankton in water. combined sewer Discharges of combined sewage and stormwater into waterbodies from regulated overflow (CSO) locations as the result of heavy storms. These discharges are designed to relieve the sewer system as it becomes overloaded with normal sewer flow and increased stormwater runoff. concentration The amount of one substance in a given amount of another substance, such as the mass of a chemical in a liter of water. conductivity A measure of water's capacity to convey an electric current. It is related to the total amount of dissolved charged substances (ions) in the water. It can be used as one general indicator of water quality. It is often used as a surrogate for salinity measurements. congener Chemical substances (constituents) related to each other by origin, structure, or function. dissolved oxygen Oxygen that is dissolved in the water. Certain concentrations are necessary for (DO) the life processes of aquatic animals. The oxygen is supplied by the photosynthesis of plants, including algae, and by aeration through contact and mixing of the surface water with the atmosphere. Oxygen is consumed by aerobic organisms during respiration and by the oxidation of chemicals. eelgrass A vascular, flowering plant found in shallow muddy or sandy habitats that spreads by an underground stem. ecosystem Any complex of living organisms, along with the non-living factors that affect them and are affected by them. Includes plants, animals, the nutrients that sustain them, and all of the other environmental conditions necessary for successful maturation and reproduction. effluent Liquids discharged from sewage treatment plants, septic systems, industries, or stormwater sources to surface waters. endocrine Chemicals that may interfere with an animal’s endocrine system and produce disrupting adverse developmental, reproductive, neurological, and immune effects. A wide compounds (EDCs) range of substances, both natural and manmade, are thought to cause endocrine disruption, including pharmaceuticals, dioxins and dioxin-like compounds, PCBs, pesticides, and plasticizers. Endocrine disruptors may be found in many everyday products, including plastic bottles, metal food cans, detergents, flame retardants, food, toys, and cosmetics. epilimnion Top-most layer in a thermally stratified lake. estuary A partly enclosed coastal body of brackish water with one or more rivers or streams flowing into it and with a free connection to the open sea/ocean. fecal coliform A group of bacteria from the intestines of warm-blooded animals. Most of the bacteria bacteria are not harmful, but they are measured or counted as indicators of the possible presence of harmful bacteria. freshwater lens A convex layer of fresh water floating on top of a denser layer of salt water.

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groundwater Water located and moving beneath the surface of the earth. The water in the ground is supplied by the seepage (percolation) of rainwater, snowmelt, and other surface water into the soil. Some groundwater may be found far beneath the earth’s surface; other groundwater may be only a few inches from the surface. hepatopancreas An organ of the digestive tract of arthropods, mollusks, and fish. It provides the functions that in mammals are provided separately by the liver and pancreas, including the production of digestive enzymes and absorption of digested food.

Hydrolab® A handheld instrument for monitoring multiple water quality parameters. intertidal zone The area between the high tide and low tide marks. infauna Aquatic animals living in the sediments of the sea floor. invertebrates Animals without internal skeletons including insects, crabs, bivalves, and worms. Benthic invertebrates are an important link in the food chain for fish and can be used as an indicator of sediment quality. left-censored A dataset with data points below known values, but it is unknown by how much. limiting nutrient The nutrient that is in lowest supply relative to demand. The limiting nutrient will be the one that is exhausted first by algae/phytoplankton growth. Increasing the amount of the limiting nutrient will result in increased algal production; once the limiting nutrient is exhausted, growth stops. lipid Any of a class of organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents. They include many natural oils, waxes, and steroids. loading The total amount of material (sediments, nutrients, chemicals) entering a waterbody via streams, overland flow, precipitation, direct discharge, or other means over time (usually considered annually). method detection The minimum concentration that can be measured and reported with 99 percent limit (MDL) confidence that the concentration is greater than zero. nephelometric A unit measuring the clarity of water. turbidity unit (NTU) nitrate, nitrite (NO3, Two types of nitrogen compounds. These nutrients are forms of nitrogen that NO2) algae may use for growth. nitrogen One of the elements essential for the growth of organisms. Nitrogen is most abundant on the earth in the form of N2 (nitrogen gas), comprising nearly 80 percent of the atmosphere, but this inert gas is not bioavailable to most organisms. Nitrogen is usually taken up by plants in the forms NO3, NO2, and NH3 (ammonia). non-ionized/ Electrically neutral atoms or molecules that have not been converted to electrically un-ionized charged atoms or molecules (ions).

King County A‐3 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary nonpoint source Pollution from diverse sources that are difficult to pinpoint as separate sources pollution and thus are more complicated to control or manage. Examples include area-wide erosion (as opposed to landslides or mass wasting), widespread failure of septic systems, certain farming practices or forestry practices, and residential/urban land uses (such as fertilizing lawns or landscaping). nutrient A chemical element, ion, or compound required by an organism for growth and reproduction. oceanographic A framework with 12 to 36 sampling bottles clustered around a central cylinder, rosette where a CTD (conductivity, temperature, and depth) or other sensor package can be attached. outfall A pipe that discharges effluent, CSOs, stormwater, and other substances to a receiving waterbody. pathogen A microorganism that can cause disease in other organisms. Pathogens include bacteria, viruses, fungi, and parasites found in sewage, in runoff from farms or city streets, and in water used for swimming. They can be present in municipal, industrial, and nonpoint source discharges. pH The log10- transformation of the activity of the hydrogen ion in solution. pH values less than 7 are acidic; values greater than 7 are basic. pH influences the speciation of metals and other constituents. Biota may be negatively impacted at very high and low pH values. phthalates A group of chemicals used to make plastics more flexible and harder to break. (plasticizers) They are often called plasticizers. Some phthalates are used as solvents (dissolving agents) for other materials. They are used in hundreds of products, such as vinyl flooring, adhesives, detergents, lubricating oils, automotive plastics, plastic clothes (raincoats), and personal-care products (soaps, shampoos, hair sprays, and nail polishes). Phthalates are used widely in polyvinyl chloride plastics, which are used to make products such as plastic packaging film and sheets, garden hoses, inflatable toys, blood-storage containers, medical tubing, and some children's toys. phosphorus One of the essential nutrients for the growth of organisms. Phosphorus occurs naturally in soils and in organic material. photosynthesis The production of organic matter from inorganic carbon and water using the energy of light. In general, plants are equipped to carry out this process, while animals cannot. phytoplankton Free-floating microscopic organisms that photosynthesize (includes both algae and cyanobacteria). point source An input of pollutants into a waterbody from discrete sources, such as municipal pollution or industrial outfall pipes. polybrominated A class of persistent and bioaccumulative halogenated compounds that have diphenyl ethers emerged as a major environmental pollutant. PBDEs are used as flame-retardants (PBDEs) and are found in consumer goods such as electrical equipment, construction materials, coatings, textiles, and polyurethane foam (furniture padding). Similar in structure to polychlorinated biphenyls (PCBs), PBDEs resist degradation in the environment.

King County A‐4 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary polychlorinated Part of a broad family of manmade organic chemicals known as chlorinated biphenyls (PCBs) hydrocarbons. PCBs were domestically manufactured from 1929 until their manufacture was banned in 1979. They have a range of toxicity and vary in consistency from thin light-colored liquids to yellow or black waxy solids. Because of their non-flammability, chemical stability, high boiling point, and electrical insulating properties, PCBs were used in hundreds of industrial and commercial applications including electrical, heat transfer, and hydraulic equipment; as plasticizers in paints, plastics, and rubber products; and in pigments, dyes, and carbonless copy paper. polycyclic aromatic A group of over 100 different chemicals that are formed during the incomplete hydrocarbons burning of coal, oil, gas, garbage, and other organic substances like tobacco or (PAHs) charbroiled meat. PAHs are usually found as a mixture containing two or more of these compounds, such as soot. Some PAHs are manufactured. These pure PAHs usually exist as colorless, white, or pale yellow-green solids. PAHs are found in coal tar, crude oil, creosote, and roofing tar, but a few are used in medicines or to make dyes, plastics, and pesticides. primary treatment The first stage of wastewater treatment involving removal of debris and solids by screening and settling. precursor A chemical compound that participates in the chemical reaction that produces another compound. regulator station Regulator stations manage flow from trunks into interceptors in combined sewer systems. Under normal conditions, the regulator gate is open and the outfall gate is closed. When levels in the interceptor reach a set point, the regulator gate closes, providing some storage, and then the outfall gate opens to allow the release of excess flow as a CSOs. riprap A foundation or sustaining wall of stones or chunks of concrete thrown together without order (as in deep water) or a layer of this or similar material on an embankment slope to prevent erosion. salinity Saltiness or dissolved salt content of a body of water. salmonids Fish belonging to the taxonomic family Salmonidae, including multiple species of salmon, trout, char, and whitefish. saltwater wedge A wedge-shaped intrusion of salty ocean water into a freshwater estuary or tidal river; it slopes downward in the upstream direction, and salinity increases with depth. secondary Following primary treatment, bacteria are used to consume organic wastes in treatment sewage. The treated sewage is then disinfected and discharged through an outfall. Nutrient concentrations are not decreased with secondary treatment. sediment Solid material deposited in the bottom of a waterbody over time, carried in by wind and water, or produced by plants and animals. separated sewer Sewer systems designed and constructed to convey only stormwater to the system waterbodies and only sanitary waste to a treatment plant. stormwater Water that is generated by rainfall and is often routed into municipal drain systems in urban environments.

King County A‐5 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary stratification A layering effect produced by the warming of the surface in many waterbodies during summer. Upper waters are progressively warmed by the sun, and the deeper waters remain cold. Because of the difference in density (warmer water is lighter), the two layers remain separate from each other. Upper waters "float" on deeper waters and wind-induced mixing occurs only in the upper waters. Oxygen in the bottom waters may become depleted. substrate A surface on which an organism grows or is attached. subtidal zone The area that is submerged most of the time and exposed briefly during extreme low tides around full and new moon events. This zone provides habitat to a large diversity of plants and animals in contrast to the other tidal zones. surface water Water located near the interface of water and air. For this assessment, waters to 1-m depth were considered “surface.”

Superfund The name given to the federal environmental program established to address abandoned hazardous waste sites. It is also the name of the fund established by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended (CERCLA). It allows the U.S. Environmental Protection Agency (EPA) to clean up such sites and to compel responsible parties to perform cleanups or reimburse the government for EPA-lead cleanups. thermal A distinction in the layers of a waterbody caused by the change in water's density stratification with temperature total maximum A calculation of the maximum amount of a pollutant that a waterbody can receive daily load (TMDL) and still meet water quality standards, and an allocation of that load among the various sources of that pollutant. total suspended Particles, both mineral (clay and sand) and organic (algae and small pieces of solids (TSS) decomposed plant and animal material), that are suspended in water. toxic Causing death, disease, cancer, genetic mutations, or physical deformations in any organism or its offspring upon exposure, ingestion, inhalation, or assimilation. trophic level The feeding position in a food chain. Primary producers such as photosynthetic organisms like phytoplankton form the first trophic level; herbivores form the second trophic level; and carnivores form the third and fourth trophic levels. turbidity Cloudiness in water caused by the suspension of tiny particles (algae or detritus), commonly measured in NTUs. usual and Each Indian tribe in Washington state has a “usual and accustomed” harvest area accustomed (U&A) that reflects the historical region in which finfish, shellfish, and other natural harvest area resources were collected. All tidelands in Puget Sound are within the usual and accustomed harvest areas of one or more tribe. Tribal members are allowed to exercise their treaty-protected harvest rights only within their tribe’s U&A. wastewater Water from sinks, toilets, and other sources in homes, industries, and businesses that is conveyed to wastewater treatment plants. Also called sewage. water column Water between the surface and the bottom sediments. Multiple depths at a given site are often sampled so that conditions can be described across the vertical distance between the surface and bottom.

King County A‐6 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary watershed The surrounding geographical area that contributes surface water and groundwater flow to a stream, lake, or other body of water. Also referred to as a “catchment basin” or “drainage basin.”

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APPENDIX B: BATHYMETRY OF DUWAMISH ESTUARY

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Figure B-1. Bathymetry and slip locations in the East, West, and Lower Duwamish waterways.

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Figure B-2. Bathymetry and slip locations in mid Lower Duwamish Waterway.

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Figure B-3. Bathymetry and slip locations in upper Lower Duwamish Waterway.

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Figure B-4. The Duwamish Estuary navigation channel.

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APPENDIX C: DATA FOR METALS AND ORGANIC COMPOUNDS

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Figure C-1. Location of East Waterway Operational Unit Supplemental Remedial Investigation sampling stations (2008-2009) (Windward, 2009).

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Total Metals

Table C-1. Concentrations of total metals (µg/L) at each sampling in the Green-Duwamish Area site split by depth (2000-2013).

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL GR-11.1 Surface 46/46 35.6 1,750 298 368 NA NA Aluminum, GR-40.6 total Surface 11/11 30.7 6,980 110 727 NA NA GR-63.1 Surface 32/32 23.4 3,850 140 488 NA NA Surface 0/5 < MDL < MDL < MDL NA 0.005 0.026 EW-SW-1 At depth 3/6 0.065 0.143 0.065 0.087 0.005 0.026 EW-SW-1 - Surface 0/1 < MDL < MDL < MDL NA 0.005 0.005 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.005 0.005 Surface 2/5 0.0795 0.098 0.0795 NA 0.005 0.026 EW-SW-2 At depth 3/5 0.105 0.135 0.105 0.112 0.005 0.022 EW-SW-2 - Surface 1/1 0.092 0.092 0.092 NA NA NA Flood tide At depth 1/1 0.088 0.088 0.088 NA NA NA Surface 1/5 0.067 0.067 < MDL NA 0.005 0.026 EW-SW-3 At depth 2/5 0.091 0.094 0.091 NA 0.005 0.026 Antimony, Surface 1/1 0.141 0.141 0.141 NA NA NA EW-SW-4 total At depth 0/1 < MDL < MDL < MDL NA 0.026 0.026 Surface 2/4 0.071 0.108 0.071 NA 0.005 0.022 EW-SW-5 At depth 2/4 0.103 0.119 0.103 NA 0.005 0.022 Surface 2/4 0.081 0.092 0.081 NA 0.005 0.026 EW-SW-6 At depth 2/4 0.086 0.116 0.086 NA 0.005 0.022 EW-SW-6 - Surface 1/1 0.15 0.15 0.15 NA NA NA Flood tide At depth 1/1 0.12 0.12 0.12 NA NA NA LDW-4.8 Surface 3/3 0.0362 0.062 0.0367 0.045 NA NA GR-11.1 Surface 8/63 0.025 0.0842 0.038 0.0499 0.5 0.5 GR-11.6 Surface 0/2 < MDL < MDL < MDL NA 0.5 0.5 GR-40.6 Surface 11/29 0.016 0.079 0.023 0.0281 0.5 0.5

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Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL GR-63.1 Surface 10/38 0.017 0.034 0.021 0.0235 0.5 0.5 Surface 5/5 0.77 1.5 1.08 1.05 NA NA EW-SW-1 At depth 5/5 1.01 1.89 1.25 1.33 NA NA EW-SW-1 - Surface 1/1 1.47 1.47 1.47 NA NA NA Flood tide At depth 1/1 1.49 1.49 1.49 NA NA NA Surface 5/5 0.23 1.61 1.17 1.01 NA NA EW-SW-2 At depth 5/5 0.97 1.54 1.29 1.27 NA NA EW-SW-2 - Surface 1/1 1.48 1.48 1.48 NA NA NA Flood tide At depth 1/1 1.53 1.53 1.53 NA NA NA Surface 5/5 1.01 1.24 1.19 1.15 NA NA EW-SW-3 At depth 5/5 1.19 1.57 1.37 1.37 NA NA Surface 1/1 1.04 1.04 1.04 NA NA NA EW-SW-4 At depth 1/1 0.79 0.79 0.79 NA NA NA Arsenic, total Surface 4/4 0.69 1.15 1.14 1.03 NA NA EW-SW-5 At depth 4/4 0.945 1.38 1.16 1.19 NA NA Surface 4/4 0.64 1.21 1.02 0.992 NA NA EW-SW-6 At depth 4/4 0.9 1.42 1.16 1.2 NA NA EW-SW-6 - Surface 1/1 1.26 1.26 1.26 NA NA NA Flood tide At depth 1/1 1.21 1.21 1.21 NA NA NA LDW-4.8 Surface 12/12 0.474 0.83 0.596 0.626 NA NA DR-9.8 Surface 11/11 0.591 1.71 0.896 0.932 NA NA GR-11.1 Surface 80/82 0.526 4.16 0.77 0.905 0.5 0.5 GR-11.6 Surface 2/2 0.68 0.7325 0.70625 NA NA NA GR-40.6 Surface 40/44 0.34 6.58 0.66 0.923 0.5 0.5 GR-42.0 Surface 9/9 0.42 0.871 0.556 0.63 NA NA GR-63.1 Surface 21/39 0.28 1.5 0.35 0.523 0.5 0.5 GR-11.1 Surface 62/62 2.35 16.5 4.37 5.24 NA NA Barium, total GR-11.6 Surface 2/2 2.81 3.1675 2.98875 NA NA NA

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Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL GR-40.6 Surface 30/30 1.39 48.5 2.29 6.51 NA NA GR-63.1 Surface 30/31 0.47 29.3 1.13 3.42 0.2 0.2 GR-11.1 Surface 0/61 < MDL < MDL < MDL NA 0.05 0.2 Beryllium, GR-11.6 Surface 0/2 < MDL < MDL < MDL NA 0.2 0.2 total GR-40.6 Surface 1/29 0.094 0.094 < MDL NA 0.01 0.2 GR-63.1 Surface 0/32 < MDL < MDL < MDL NA 0.05 0.2 Surface 5/5 0.048 0.152 0.056 0.076 NA NA EW-SW-1 At depth 7/7 0.062 1.45 0.078 0.274 NA NA EW-SW-1 - Surface 1/1 0.047 0.047 0.047 NA NA NA Flood tide At depth 1/1 0.084 0.084 0.084 NA NA NA Surface 4/5 0.046 0.117 0.0555 0.0662 0.029 0.029 EW-SW-2 At depth 4/5 0.055 0.087 0.071 0.0738 0.029 0.029 EW-SW-2 - Surface 1/1 0.06 0.06 0.06 NA NA NA Flood tide At depth 1/1 0.088 0.088 0.088 NA NA NA Surface 5/5 0.057 0.087 0.061 0.0662 NA NA EW-SW-3 At depth 5/5 0.073 0.1 0.082 0.083 NA NA Cadmium, Surface 1/1 0.087 0.087 0.087 NA NA NA EW-SW-4 total At depth 0/1 < MDL < MDL < MDL NA 0.029 0.029 Surface 4/4 0.044 0.071 0.054 0.058 NA NA EW-SW-5 At depth 4/4 0.062 0.084 0.066 0.0738 NA NA Surface 4/4 0.038 0.077 0.05 0.055 NA NA EW-SW-6 At depth 4/4 0.059 0.088 0.065 0.073 NA NA EW-SW-6 - Surface 1/1 0.072 0.072 0.072 NA NA NA Flood tide At depth 1/1 0.076 0.076 0.076 NA NA NA LDW-4.8 Surface 11/12 0.0052 0.023 0.0095 0.0111 0.005 0.005 GR-11.1 Surface 2/81 0.011 0.38 < MDL NA 0.01 0.1 GR-11.6 Surface 0/2 < MDL < MDL < MDL NA 0.1 0.1 GR-40.6 Surface 1/44 0.029 0.029 < MDL NA 0.01 0.1

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Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL GR-63.1 Surface 0/39 < MDL < MDL < MDL NA 0.01 0.1 LDW-4.8 Surface 56/56 5,340 214,000 12,300 35800 NA NA Calcium, GR-11.1 Surface 74/74 5,480 13,100 8,400 8,690 NA NA total GR-40.6 Surface 44/44 4,500 11,400 6,060 6,260 NA NA GR-63.1 Surface 32/32 3,970 6,430 4,720 4,990 NA NA Surface 3/5 0.26 2.66 0.45 0.816 0.24 0.79 EW-SW-1 At depth 3/5 0.24 2.76 0.25 0.748 0.24 0.79 EW-SW-1 - Surface 1/1 3.61 3.61 3.61 NA NA NA Flood tide At depth 1/1 1.94 1.94 1.94 NA NA NA Surface 3/5 0.15 3.22 0.365 0.85 0.24 0.79 EW-SW-2 At depth 3/5 0.17 0.71 0.18 0.309 0.24 0.79 EW-SW-2 - Surface 1/1 2.03 2.03 2.03 NA NA NA Flood tide At depth 1/1 0.77 0.77 0.77 NA NA NA Surface 3/5 0.16 0.59 0.27 0.34 0.24 0.79 EW-SW-3 At depth 3/5 0.16 0.38 0.32 0.287 0.24 0.79 Surface 0/1 < MDL < MDL < MDL NA 0.79 0.79 Chromium, EW-SW-4 total At depth 0/1 < MDL < MDL < MDL NA 0.79 0.79 Surface 3/4 0.17 0.89 0.2 0.361 0.24 0.24 EW-SW-5 At depth 3/4 0.18 0.22 0.2 0.2 0.24 0.24 Surface 3/4 0.19 0.73 0.2 0.373 0.79 0.79 EW-SW-6 At depth 3/4 0.16 0.27 0.27 0.233 0.24 0.24 EW-SW-6 - Surface 1/1 1.67 1.67 1.67 NA NA NA Flood tide At depth 1/1 0.24 0.24 0.24 NA NA NA LDW-4.8 Surface 12/12 0.11 0.22 0.17 0.169 NA NA GR-11.1 Surface 62/84 0.15 8.49 0.47 0.691 0.4 0.4 GR-11.6 Surface 2/3 0.41 0.7 0.41 NA 0.4 0.4 GR-40.6 Surface 24/45 0.073 10.8 0.13 0.745 0.2 0.4 GR-63.1 Surface 17/40 0.082 2.09 0.16 0.302 0.4 0.4

King County C‐6 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL Surface 1/5 1.64 1.64 < MDL NA 0.02 0.06 EW-SW-1 At depth 1/5 1.49 1.49 < MDL NA 0.02 0.06 EW-SW-1 - Surface 1/1 2.13 2.13 2.13 NA NA NA Flood tide At depth 1/1 1.02 1.02 1.02 NA NA NA Surface 1/5 1.35 1.35 < MDL NA 0.02 0.06 EW-SW-2 At depth 0/5 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-2 - Surface 1/1 0.91 0.91 0.91 NA NA NA Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.02 0.02 Surface 1/5 0.5 0.5 < MDL NA 0.02 0.06 EW-SW-3 At depth 0/5 < MDL < MDL < MDL NA 0.02 0.06 Surface 0/1 < MDL < MDL < MDL NA 0.05 0.05 Cobalt, total EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.05 0.05 Surface 0/4 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-5 At depth 0/4 < MDL < MDL < MDL NA 0.02 0.06 Surface 0/4 < MDL < MDL < MDL NA 0.02 0.05 EW-SW-6 At depth 0/4 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-6 - Surface 1/1 0.55 0.55 0.55 NA NA NA Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.02 0.02 GR-11.1 Surface 33/70 0.0921 1.63 0.155 0.269 0.2 0.2 GR-11.6 Surface 0/2 < MDL < MDL < MDL NA 0.2 0.2 GR-40.6 Surface 16/27 0.028 3.57 0.045 0.412 0.2 0.2 GR-63.1 Surface 17/40 0.032 4.08 0.0788 0.304 0.2 0.2 Surface 5/5 1.03 6.65 1.81 2.68 NA NA EW-SW-1 At depth 5/5 0.53 5.34 0.795 1.64 NA NA EW-SW-1 - Surface 1/1 8.11 8.11 8.11 NA NA NA Copper, total Flood tide At depth 1/1 3.69 3.69 3.69 NA NA NA Surface 5/5 0.9 5.84 1.5 2.18 NA NA EW-SW-2 At depth 5/5 0.44 1.3 0.54 0.664 NA NA

King County C‐7 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL EW-SW-2 – Surface 1/1 4.31 4.31 4.31 NA NA NA Flood tide At depth 1/1 1.52 1.52 1.52 NA NA NA Surface 5/5 0.6 2.65 1.22 1.32 NA NA EW-SW-3 At depth 5/5 0.48 0.97 0.87 0.818 NA NA Surface 1/1 1.57 1.57 1.57 NA NA NA EW-SW-4 At depth 1/1 0.36 0.36 0.36 NA NA NA Surface 4/4 1.21 2.38 1.24 1.79 NA NA EW-SW-5 At depth 4/4 0.34 0.63 0.38 0.482 NA NA Surface 4/4 1.1 1.66 1.25 1.37 NA NA EW-SW-6 At depth 4/4 0.26 0.81 0.3 0.462 NA NA EW-SW-6 - Surface 1/1 4.42 4.42 4.42 NA NA NA Flood tide At depth 1/1 0.43 0.43 0.43 NA NA NA LDW-4.8 Surface 12/12 0.613 1.37 0.817 0.889 NA NA GR-11.1 Surface 88/89 0.49 17.9 1.4 1.85 0.4 0.4 GR-11.6 Surface 3/3 0.64 4.29 1.04 1.99 NA NA GR-40.6 Surface 33/46 0.13 30.7 0.42 1.79 0.4 0.4 GR-63.1 Surface 25/39 0.18 6.84 0.32 0.775 0.4 0.4 GR-11.1 Surface 64/64 346 15400 756 1100 NA NA Iron, total GR-40.6 Surface 24/24 54 30100 240 2500 NA NA GR-63.1 Surface 30/32 51 3280 180 446 50 50 Surface 4/5 0.135 1.5 0.136 0.61 2.3 2.3 EW-SW-1 At depth 4/6 0.137 1.08 0.178 0.348 0.036 2.3 EW-SW-1 - Surface 1/1 1.95 1.95 1.95 NA NA NA Flood tide At depth 1/1 0.779 0.779 0.779 NA NA NA Lead, total Surface 3/5 0.128 1.29 0.128 0.476 0.036 2.3 EW-SW-2 At depth 3/5 0.165 0.397 0.165 0.254 0.036 2.3 EW-SW-2 - Surface 1/1 0.794 0.794 0.794 NA NA NA Flood tide At depth 1/1 0.393 0.393 0.393 NA NA NA

King County C‐8 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL Surface 3/5 0.064 0.391 0.064 0.205 0.036 2.3 EW-SW-3 At depth 3/5 0.232 0.65 0.232 0.39 0.036 2.3 Surface 0/1 < MDL < MDL < MDL NA 2.3 2.3 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 2.3 2.3 Surface 3/4 0.055 0.555 0.055 0.21 0.036 0.036 EW-SW-5 At depth 3/4 0.124 0.166 0.126 0.135 0.036 0.036 Surface 2/4 0.108 0.585 0.108 NA 0.036 2.3 EW-SW-6 At depth 3/4 0.055 0.275 0.103 0.128 0.036 0.036 EW-SW-6 - Surface 1/1 2.39 2.39 2.39 NA NA NA Flood tide At depth 1/1 0.054 0.054 0.054 NA NA NA LDW-4.8 Surface 12/12 0.0481 0.327 0.092 0.133 NA NA GR-11.1 Surface 65/89 0.056 4.24 0.42 0.651 0.2 0.2 GR-11.6 Surface 2/4 0.39 1.29 < MDL NA 0.2 0.2 GR-40.6 Surface 16/44 0.036 6.72 0.037 0.414 0.025 0.2 GR-63.1 Surface 10/39 0.027 1.45 0.027 0.124 0.025 0.2 LDW-4.8 Surface 56/56 2,430 608,000 15,300 88,000 NA NA Magnesium, GR-11.1 Surface 74/74 1,530 4,860 2,590 2,830 NA NA total GR-40.6 Surface 44/44 877 7150 1,380 1,550 NA NA GR-63.1 Surface 32/32 646 1425 892 907 NA NA Manganese, GR-11.1 Surface 42/42 19 159 49.1 57.5 NA NA total GR-63.1 Surface 33/33 19.8 139.05 40.3 52.1 NA NA Surface 3/5 0.00081 0.0207 0.00081 0.00484 0.00015 0.00015 EW-SW-1 At depth 4/5 0.00066 0.0116 0.00092 0.0031 0.00015 0.00015 EW-SW-1 - Surface 1/1 0.0228 0.0228 0.0228 NA NA NA Mercury, Flood tide total At depth 1/1 0.0277 0.0277 0.0277 NA NA NA Surface 4/5 0.00048 0.0221 7.00E-04 0.00501 0.00015 0.00015 EW-SW-2 At depth 5/5 0.00049 0.00551 0.00188 0.00214 NA NA EW-SW-2 - Surface 1/1 0.00688 0.00688 0.00688 NA NA NA

King County C‐9 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL Flood tide At depth 1/1 0.00425 0.00425 0.00425 NA NA NA Surface 4/5 0.00041 0.00474 0.00044 0.00152 0.00015 0.00015 EW-SW-3 At depth 5/5 6.00E-04 0.00413 0.00133 0.00176 NA NA Surface 0/1 < MDL < MDL < MDL NA 0.00015 0.00015 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.00015 0.00015 Surface 3/4 3.00E-04 0.00433 3.00E-04 0.00139 0.00015 0.00015 EW-SW-5 At depth 3/4 0.00039 7.00E-04 0.00039 0.000525 0.00015 0.00015 Surface 3/4 0.00048 0.00246 0.00048 0.00107 0.00021 0.00021 EW-SW-6 At depth 3/4 0.00036 0.00119 0.00036 0.000639 0.00015 0.00015 EW-SW-6 - Surface 1/1 0.0102 0.0102 0.0102 NA NA NA Flood tide At depth 1/1 0.00063 0.00063 0.00063 NA NA NA LDW-4.8 Surface 13/13 0.000584 0.00192 0.00125 0.00123 NA NA GR-11.1 Surface 22/81 0.000699 0.014 0.00191 0.00248 0.005 0.2 GR-11.6 Surface 0/2 < MDL < MDL < MDL NA 0.2 0.2 GR-40.6 Surface 22/45 0.00022 0.0835 0.000573 0.00402 0.005 0.2 GR-63.1 Surface 13/37 0.00046 0.042 0.00101 0.00382 0.005 0.005 GR-11.1 Surface 10/69 0.103 1.126667 0.166 0.186 0.5 0.5 Molybdenum, GR-11.6 Surface 0/2 < MDL < MDL < MDL NA 0.5 0.5 total GR-40.6 Surface 11/30 0.0693 0.133 0.104 0.104 0.5 0.5 GR-63.1 Surface 10/39 0.0665 0.143 0.0933 0.0973 0.5 0.5 Surface 2/5 0.4 2.6 0.4 NA 0.05 0.34 EW-SW-1 At depth 2/5 0.33 2.44 0.33 NA 0.05 0.34 EW-SW-1 - Surface 1/1 3.37 3.37 3.37 NA NA NA Flood tide At depth 1/1 1.39 1.39 1.39 NA NA NA Nickel, total Surface 2/5 0.35 3.29 0.35 NA 0.05 0.34 EW-SW-2 At depth 2/5 0.55 0.68 < MDL NA 0.05 0.34 EW-SW-2 - Surface 1/1 1.97 1.97 1.97 NA NA NA Flood tide At depth 1/1 0.54 0.54 0.54 NA NA NA

King County C‐10 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL Surface 2/5 0.34 0.66 0.34 NA 0.05 0.34 EW-SW-3 At depth 2/5 0.39 0.48 0.39 NA 0.05 0.34 Surface 0/1 < MDL < MDL < MDL NA 0.34 0.34 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.34 0.34 Surface 2/4 0.25 1.1 0.25 NA 0.05 0.05 EW-SW-5 At depth 2/4 0.285 0.4 0.285 NA 0.05 0.05 Surface 1/4 0.74 0.74 < MDL NA 0.03 0.34 EW-SW-6 At depth 1/5 0.42 0.42 < MDL NA 0.03 0.05 EW-SW-6 - Surface 1/1 1 1 1 NA NA NA Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.03 0.03 LDW-4.8 Surface 13/13 0.242 0.9855 0.421 0.532 NA NA GR-11.1 Surface 80/83 0.34 8.18 0.61 0.87 0.3 0.3 GR-11.6 Surface 2/2 0.45 0.5125 0.48125 NA NA NA GR-40.6 Surface 28/45 0.052 9.82 0.14 0.922 0.05 0.3 GR-63.1 Surface 16/40 0.11 2.32 0.15 0.306 0.3 0.3 GR-11.1 Surface 10/51 431 1260 911 940 2000 2000 Potassium, GR-40.6 total Surface 13/13 200 370 300 296 NA NA GR-63.1 Surface 0/32 < MDL < MDL < MDL NA 2000 2000 Surface 5/5 0.06 0.26 0.17 0.156 NA NA EW-SW-1 At depth 5/5 0.1 0.44 0.15 0.197 NA NA EW-SW-1 - Surface 1/1 0.22 0.22 0.22 NA NA NA Flood tide At depth 1/1 0.36 0.36 0.36 NA NA NA Selenium, Surface 5/5 0.06 0.38 0.15 0.179 NA NA EW-SW-2 total At depth 5/5 0.09 0.27 0.16 0.172 NA NA EW-SW-2 - Surface 1/1 0.28 0.28 0.28 NA NA NA Flood tide At depth 1/1 0.22 0.22 0.22 NA NA NA Surface 5/5 0.08 0.29 0.17 0.162 NA NA EW-SW-3 At depth 5/5 0.1 0.25 0.17 0.174 NA NA

King County C‐11 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL Surface 1/1 0.17 0.17 0.17 NA NA NA EW-SW-4 At depth 1/1 0.14 0.14 0.14 NA NA NA Surface 4/4 0.07 0.31 0.08 0.165 NA NA EW-SW-5 At depth 4/4 0.09 0.28 0.095 0.164 NA NA Surface 4/4 0.07 0.3 0.08 0.155 NA NA EW-SW-6 At depth 4/4 0.07 0.27 0.08 0.155 NA NA EW-SW-6 - Surface 1/1 0.27 0.27 0.27 NA NA NA Flood tide At depth 1/1 0.22 0.22 0.22 NA NA NA GR-11.1 Surface 0/67 < MDL < MDL < MDL NA 0.5 1.5 GR-11.6 Surface 0/2 < MDL < MDL < MDL NA 1.5 1.5 GR-40.6 Surface 0/30 < MDL < MDL < MDL NA 0.5 1.5 GR-63.1 Surface 0/39 < MDL < MDL < MDL NA 0.5 1.5 Surface 0/5 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-1 At depth 0/5 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-1 - Surface 0/1 < MDL < MDL < MDL NA 0.01 0.01 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.01 0.01 Surface 0/5 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-2 At depth 0/5 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-2 - Surface 0/1 < MDL < MDL < MDL NA 0.01 0.01 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.01 0.01 Silver, total Surface 0/5 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-3 At depth 0/5 < MDL < MDL < MDL NA 0.008 0.012 Surface 0/1 < MDL < MDL < MDL NA 0.012 0.012 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.012 0.012 Surface 0/4 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-5 At depth 0/4 < MDL < MDL < MDL NA 0.008 0.012 Surface 0/4 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-6 At depth 0/4 < MDL < MDL < MDL NA 0.008 0.012

King County C‐12 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL EW-SW-6 - Surface 0/1 < MDL < MDL < MDL NA 0.01 0.01 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.01 0.01 LDW-4.8 Surface 11/13 0.01 0.0524 0.013 0.0217 0.01 0.01 GR-11.1 Surface 0/81 < MDL < MDL < MDL NA 0.025 0.2 GR-11.6 Surface 0/2 < MDL < MDL < MDL NA 0.2 0.2 GR-40.6 Surface 0/44 < MDL < MDL < MDL NA 0.01 0.2 GR-63.1 Surface 0/40 < MDL < MDL < MDL NA 0.025 0.2 GR-11.1 Surface 51/51 3110 16000 5330 7160 NA NA Sodium, total GR-40.6 Surface 13/13 2460 4050 3340 3250 NA NA GR-63.1 Surface 34/34 2100 3450 2620 2710 NA NA Strontium, GR-11.1 Surface 2/2 20.2 21.25 20.725 NA NA NA total GR-63.1 Surface 1/1 8.855 8.855 8.855 NA NA NA Surface 3/5 0.007 0.017 0.009 0.0098 0.005 0.005 EW-SW-1 At depth 3/5 0.011 0.021 0.011 0.013 0.005 0.005 EW-SW-1 - Surface 1/1 0.018 0.018 0.018 NA NA NA Flood tide At depth 1/1 0.018 0.018 0.018 NA NA NA Surface 3/5 0.008 0.018 0.009 0.0104 0.005 0.005 EW-SW-2 At depth 3/5 0.011 0.012 0.011 0.0113 0.005 0.005 EW-SW-2 - Surface 1/1 0.014 0.014 0.014 NA NA NA Thallium, Flood tide At depth 1/1 0.013 0.013 0.013 NA NA NA total Surface 3/5 0.008 0.012 0.01 0.01 0.005 0.005 EW-SW-3 At depth 3/5 0.01 0.012 0.011 0.011 0.005 0.005 Surface 0/1 < MDL < MDL < MDL NA 0.005 0.005 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.005 0.005 Surface 3/4 0.008 0.009 0.009 0.00867 0.005 0.005 EW-SW-5 At depth 3/4 0.011 0.0115 0.011 0.0112 0.005 0.005 Surface 3/4 0.007 0.008 0.008 0.00767 0.005 0.005 EW-SW-6 At depth 4/5 0.01 0.012 0.011 0.011 0.005 0.005

King County C‐13 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL EW-SW-6 - Surface 1/1 0.01 0.01 0.01 NA NA NA Flood tide At depth 1/1 0.01 0.01 0.01 NA NA NA GR-11.1 Surface 1/67 0.01 0.01 < MDL NA 0.01 0.2 GR-11.6 Surface 0/2 < MDL < MDL < MDL NA 0.2 0.2 GR-40.6 Surface 1/30 0.026 0.026 < MDL NA 0.01 0.2 GR-63.1 Surface 1/39 0.01 0.01 < MDL NA 0.01 0.2 Surface 5/5 0.976 7.22 1.42 2.42 NA NA EW-SW-1 At depth 5/5 1.345 7.36 1.61 2.74 NA NA EW-SW-1 - Surface 1/1 9.29 9.29 9.29 NA NA NA Flood tide At depth 1/1 4.84 4.84 4.84 NA NA NA Surface 4/5 0.982 6.33 1.51 2.31 0.024 0.024 EW-SW-2 At depth 5/5 1.22 2.37 1.54 1.67 NA NA EW-SW-2 - Surface 1/1 4.46 4.46 4.46 NA NA NA Flood tide At depth 1/1 2.48 2.48 2.48 NA NA NA Surface 5/5 1.01 2.04 1.4 1.44 NA NA EW-SW-3 At depth 5/5 1.4 2.16 1.73 1.76 NA NA Vanadium, Surface 1/1 1.28 1.28 1.28 NA NA NA EW-SW-4 total At depth 1/1 0.029 0.029 0.029 NA NA NA Surface 4/4 0.912 2.08 1.42 1.46 NA NA EW-SW-5 At depth 4/4 1.415 1.84 1.46 1.55 NA NA Surface 4/4 0.686 1.95 1.4 1.37 NA NA EW-SW-6 At depth 4/4 1.37 1.93 1.49 1.58 NA NA EW-SW-6 - Surface 1/1 3.34 3.34 3.34 NA NA NA Flood tide At depth 1/1 1.55 1.55 1.55 NA NA NA GR-11.1 Surface 68/68 0.51 6.45 1.2 1.58 NA NA GR-11.6 Surface 2/2 1.0175 1.035 1.02625 NA NA NA GR-40.6 Surface 29/29 0.555 17.3 0.924 2.39 NA NA GR-63.1 Surface 37/38 0.68 11.4 0.95 1.66 0.3 0.3

King County C‐14 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL Surface 3/5 2.99 10.4 2.99 5.62 0.08 0.08 EW-SW-1 At depth 3/5 1.26 7.9 1.33 2.62 0.08 0.08 EW-SW-1 - Surface 1/1 13.8 13.8 13.8 NA NA NA Flood tide At depth 1/1 5.32 5.32 5.32 NA NA NA Surface 3/5 3.545 10.3 3.54 5.53 0.08 0.08 EW-SW-2 At depth 3/5 0.78 2.59 1.35 1.57 0.08 0.08 EW-SW-2 - Surface 1/1 5.98 5.98 5.98 NA NA NA Flood tide At depth 1/1 2.45 2.45 2.45 NA NA NA Surface 3/5 1.99 3.43 1.99 2.69 0.08 0.08 EW-SW-3 At depth 3/5 1.43 1.75 1.62 1.6 0.08 0.08 Surface 0/1 < MDL < MDL < MDL NA 0.08 0.08 EW-SW-4 Zinc, total At depth 0/1 < MDL < MDL < MDL NA 0.08 0.08 Surface 3/4 5.44 9.29 5.44 7.03 0.08 0.08 EW-SW-5 At depth 3/4 0.995 1.57 1.09 1.22 0.08 0.08 Surface 3/4 2.27 5.63 2.27 3.64 0.08 0.08 EW-SW-6 At depth 3/4 0.63 0.99 0.96 0.86 0.08 0.08 EW-SW-6 - Surface 1/1 15.8 15.8 15.8 NA NA NA Flood tide At depth 1/1 0.72 0.72 0.72 NA NA NA LDW-4.8 Surface 12/12 0.711 2.16 1.2 1.28 NA NA GR-11.1 Surface 87/87 0.5 27.8 3.03 4.51 NA NA GR-11.6 Surface 3/3 0.99 9.25 1.95 4.06 NA NA GR-40.6 Surface 24/45 0.52 42.4 0.54 2.95 0.5 0.5 GR-63.1 Surface 33/39 0.16 10.4 0.74 1.3 0.5 0.5 FOD = frequency of detection; MDL = method detection limit. a Means were calculated using the Kaplan‐Meier methodology.

King County C‐15 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Dissolved Metals

Table C-2. Concentrations of dissolved metals (µg/L) in the Green-Duwamish Area at each sampling site split by depth (2000-2013).

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL GR-11.1 Surface 6/42 2.2 27.1 5.3 7.8 2 2 Aluminum, GR-40.6 dissolved Surface 2/2 6.6 7.4 7 NA NA NA GR-63.1 Surface 32/33 2.1 46 7.9 12.8 2 2 Surface 0/5 < MDL < MDL < MDL NA 0.005 0.026 EW-SW-1 At depth 3/6 0.097 0.153 0.097 0.117 0.005 0.026 EW-SW-1 - Surface 0/1 < MDL < MDL < MDL NA 0.005 0.005 Flood tide At depth 1/1 0.079 0.079 0.079 NA NA NA Surface 1/5 0.105 0.105 < MDL NA 0.005 0.026 EW-SW-2 At depth 2/5 0.096 0.118 0.096 NA 0.005 0.026 EW-SW-2 - Surface 1/1 0.101 0.101 0.101 NA NA NA Flood tide At depth 1/1 0.137 0.137 0.137 NA NA NA Surface 2/5 0.074 0.138 < MDL NA 0.005 0.022 EW-SW-3 At depth 2/5 0.097 0.109 0.097 NA 0.005 0.026 Antimony, Surface 0/1 < MDL < MDL < MDL NA 0.026 0.026 EW-SW-4 dissolved At depth 0/1 < MDL < MDL < MDL NA 0.026 0.026 Surface 2/4 0.111 0.134 0.111 NA 0.005 0.022 EW-SW-5 At depth 3/5 0.06 0.125 0.06 0.0892 0.005 0.022 Surface 1/4 0.093 0.093 < MDL NA 0.005 0.022 EW-SW-6 At depth 2/4 0.102 0.1415 0.102 NA 0.005 0.022 EW-SW-6 - Surface 1/1 0.13 0.13 0.13 NA NA NA Flood tide At depth 1/1 0.106 0.106 0.106 NA NA NA LDW-4.8 Surface 2/2 0.0342 0.0584 0.0463 NA NA NA GR-11.1 Surface 8/62 0.024 0.0789 0.035 0.0432 0.5 0.5 GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 0.5 0.5 GR-40.6 Surface 10/28 0.018 0.035 0.023 0.024 0.5 0.5

King County C‐16 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL GR-63.1 Surface 10/38 0.016 0.038 0.019 0.021 0.5 0.5 Surface 5/5 0.44 1.07 0.92 0.804 NA NA EW-SW-1 At depth 5/5 0.89 1.36 1.06 1.07 NA NA EW-SW-1 - Surface 1/1 0.43 0.43 0.43 NA NA NA Flood tide At depth 1/1 0.88 0.88 0.88 NA NA NA Surface 5/5 0.74 1.08 0.91 0.898 NA NA EW-SW-2 At depth 5/5 1.14 1.29 1.17 1.19 NA NA EW-SW-2 - Surface 1/1 0.93 0.93 0.93 NA NA NA Flood tide At depth 1/1 1.03 1.03 1.03 NA NA NA Surface 5/5 0.77 1.28 1.06 1.07 NA NA EW-SW-3 At depth 5/5 1.07 1.23 1.11 1.14 NA NA Surface 1/1 0.98 0.98 0.98 NA NA NA Arsenic, EW-SW-4 dissolved At depth 1/1 0.81 0.81 0.81 NA NA NA Surface 4/4 0.64 1.17 0.94 0.95 NA NA EW-SW-5 At depth 4/4 0.935 1.41 1.16 1.17 NA NA Surface 4/4 0.52 1.17 0.96 0.928 NA NA EW-SW-6 At depth 4/4 0.95 1.34 1.1 1.14 NA NA EW-SW-6 - Surface 1/1 0.83 0.83 0.83 NA NA NA Flood tide At depth 1/1 0.84 0.84 0.84 NA NA NA LDW-4.8 Surface 12/12 0.391 0.568 0.426 0.453 NA NA GR-11.1 Surface 60/80 0.38 0.842 0.53 0.558 0.5 0.5 GR-11.6 Surface 1/2 0.53 0.53 < MDL NA 0.5 0.5 GR-40.6 Surface 32/43 0.3 0.835 0.525 0.537 0.5 0.5 GR-63.1 Surface 17/39 0.24 0.867 0.3 0.375 0.5 0.5 GR-11.1 Surface 9/59 1.07 4.295 2.3 2.38 NA NA Barium, GR-11.6 Surface 1/1 1.8725 1.8725 1.8725 NA NA NA dissolved GR-40.6 Surface 28/28 0.735 2.965 1.15 1.31 NA NA GR-63.1 Surface 32/32 0.33 0.68 0.445 0.463 NA NA

King County C‐17 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL GR-11.1 Surface 0/60 < MDL < MDL < MDL NA 0.05 0.2 Beryllium, GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 0.2 0.2 dissolved GR-40.6 Surface 0/26 < MDL < MDL < MDL NA 0.01 0.2 GR-63.1 Surface 0/37 < MDL < MDL < MDL NA 0.05 0.2 Surface 5/5 0.02 0.068 0.052 0.0502 NA NA EW-SW-1 At depth 6/6 0.06 37.8 0.076 6.36 NA NA EW-SW-1 - Surface 1/1 0.009 0.009 0.009 NA NA NA Flood tide At depth 1/1 0.07 0.07 0.07 NA NA NA Surface 4/5 0.042 0.059 0.043 0.0489 0.029 0.029 EW-SW-2 At depth 4/5 0.064 0.078 0.074 0.0728 0.029 0.029 EW-SW-2 - Surface 1/1 0.055 0.055 0.055 NA NA NA Flood tide At depth 1/1 0.067 0.067 0.067 NA NA NA Surface 5/5 0.038 0.082 0.059 0.0608 NA NA EW-SW-3 At depth 5/5 0.065 0.079 0.073 0.072 NA NA Surface 0/1 < MDL < MDL < MDL NA 0.029 0.029 Cadmium, EW-SW-4 dissolved At depth 0/1 < MDL < MDL < MDL NA 0.029 0.029 Surface 4/4 0.045 0.071 0.047 0.0558 NA NA EW-SW-5 At depth 4/4 0.059 0.091 0.069 0.0753 NA NA Surface 4/4 0.035 0.075 0.05 0.055 NA NA EW-SW-6 At depth 4/4 0.063 0.076 0.065 0.0691 NA NA EW-SW-6 - Surface 1/1 0.041 0.041 0.041 NA NA NA Flood tide At depth 1/1 0.055 0.055 0.055 NA NA NA LDW-4.8 Surface 5/12 0.0065 0.022 < MDL 0.01 0.005 0.005 GR-11.1 Surface 0/79 < MDL < MDL < MDL NA 0.01 0.1 GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 0.1 0.1 GR-40.6 Surface 1/44 0.23 0.23 < MDL NA 0.01 0.1 GR-63.1 Surface 0/39 < MDL < MDL < MDL NA 0.01 0.1 Calcium, GR-11.1 Surface 8/68 4380 13300 8210 8400 NA NA

King County C‐18 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL dissolved GR-40.6 Surface 8/28 3060 14400 5670 6040 NA NA GR-63.1 Surface 2/32 3240 6520 4510 4780 NA NA Surface 3/5 0.14 0.17 0.15 0.153 0.24 0.79 EW-SW-1 At depth 3/5 0.13 0.2 0.13 0.153 0.24 0.79 EW-SW-1 - Surface 1/1 0.17 0.17 0.17 NA NA NA Flood tide At depth 1/1 0.16 0.16 0.16 NA NA NA Surface 3/5 0.11 0.2 0.145 0.152 0.24 0.79 EW-SW-2 At depth 3/5 0.11 0.23 0.13 0.157 0.24 0.79 EW-SW-2 - Surface 1/1 0.23 0.23 0.23 NA NA NA Flood tide At depth 1/1 0.19 0.19 0.19 NA NA NA Surface 3/5 0.12 0.19 0.15 0.153 0.24 0.79 EW-SW-3 At depth 3/5 0.12 1.15 0.13 0.381 0.24 0.79 Surface 0/1 < MDL < MDL < MDL NA 0.79 0.79 Chromium, EW-SW-4 dissolved At depth 0/1 < MDL < MDL < MDL NA 0.79 0.79 Surface 3/4 0.12 0.4 0.14 0.22 0.24 0.24 EW-SW-5 At depth 3/4 0.12 0.22 0.12 0.153 0.24 0.24 Surface 3/4 0.1 0.42 0.14 0.22 0.24 0.24 EW-SW-6 At depth 3/4 0.13 0.185 0.14 0.152 0.24 0.24 EW-SW-6 - Surface 1/1 0.31 0.31 0.31 NA NA NA Flood tide At depth 1/1 0.35 0.35 0.35 NA NA NA LDW-4.8 Surface 2/13 0.058 0.11 0.071 0.0733 0.05 0.05 GR-11.1 Surface 1/80 0.055 0.475 0.095 0.117 0.05 0.4 GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 0.4 0.4 GR-40.6 Surface 0/43 0.053 0.21 0.082 0.0907 0.2 0.4 GR-63.1 Surface 9/39 0.052 0.13 0.072 0.0767 0.05 0.4 Surface 0/5 < MDL < MDL < MDL NA 0.02 0.06 Cobalt, EW-SW-1 dissolved At depth 0/5 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-1 - Surface 0/1 < MDL < MDL < MDL NA 0.02 0.02

King County C‐19 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.02 0.02 Surface 0/5 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-2 At depth 0/5 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-2 - Surface 0/1 < MDL < MDL < MDL NA 0.02 0.02 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.02 0.02 Surface 0/5 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-3 At depth 0/5 < MDL < MDL < MDL NA 0.02 0.06 Surface 0/1 < MDL < MDL < MDL NA 0.05 0.05 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.05 0.05 Surface 0/4 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-5 At depth 1/4 0.4 0.4 < MDL NA 0.02 0.06 Surface 0/4 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-6 At depth 0/4 < MDL < MDL < MDL NA 0.02 0.06 EW-SW-6 - Surface 0/1 < MDL < MDL < MDL NA 0.02 0.02 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.02 0.02 GR-11.1 Surface 10/64 0.026 1.12 0.0539 0.0771 0.2 0.2 GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 0.2 0.2 GR-40.6 Surface 6/25 0.01 0.026 0.012 0.0141 0.01 0.2 GR-63.1 Surface 2/39 0.02 3.46 0.031 0.124 0.2 0.2 Surface 5/5 0.98 2.44 1.08 1.35 NA NA EW-SW-1 At depth 5/5 0.35 0.88 0.48 0.545 NA NA EW-SW-1 - Surface 1/1 0.74 0.74 0.74 NA NA NA Flood tide At depth 1/1 0.52 0.52 0.52 NA NA NA Copper, Surface 5/5 0.68 1.96 1.16 1.19 NA NA dissolved EW-SW-2 At depth 5/5 0.28 0.58 0.38 0.404 NA NA EW-SW-2 - Surface 1/1 1.14 1.14 1.14 NA NA NA Flood tide At depth 1/1 0.44 0.44 0.44 NA NA NA EW-SW-3 Surface 5/5 0.52 0.79 0.69 0.684 NA NA

King County C‐20 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL At depth 5/5 0.24 0.4 0.36 0.346 NA NA Surface 1/1 1.35 1.35 1.35 NA NA NA EW-SW-4 At depth 1/1 0.38 0.38 0.38 NA NA NA Surface 4/4 0.9 2.27 1.09 1.44 NA NA EW-SW-5 At depth 4/4 0.24 0.49 0.295 0.361 NA NA Surface 4/4 0.8 1.15 0.96 1.01 NA NA EW-SW-6 At depth 4/4 0.23 0.46 0.32 0.342 NA NA EW-SW-6 - Surface 1/1 0.86 0.86 0.86 NA NA NA Flood tide At depth 1/1 0.27 0.27 0.27 NA NA NA LDW-4.8 Surface 2/12 0.328 0.637 0.44 0.443 NA NA GR-11.1 Surface 4/81 0.21 2.94 0.64 0.746 0.4 0.4 GR-11.6 Surface 2/3 0.715 2.29 0.715 NA 0.4 0.4 GR-40.6 Surface 9/44 0.14 0.87 0.27 0.295 0.4 0.4 GR-63.1 Surface 1/39 0.11 0.62 0.2 0.22 0.4 0.4 GR-11.1 Surface 0/62 61 474 115 162 50 50 Iron, GR-40.6 dissolved Surface 2/20 59 86 < MDL NA 50 50 GR-63.1 Surface 3/33 62.5 88 < MDL 63.3 50 50 Surface 0/5 < MDL < MDL < MDL NA 0.036 2.3 EW-SW-1 At depth 0/5 < MDL < MDL < MDL NA 0.036 2.3 EW-SW-1 - Surface 0/1 < MDL < MDL < MDL NA 0.036 0.036 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.036 0.036 Surface 0/5 < MDL < MDL < MDL NA 0.036 2.3 Lead, EW-SW-2 dissolved At depth 1/5 0.051 0.051 0.051 NA 0.036 2.29 EW-SW-2 - Surface 0/1 < MDL < MDL < MDL NA 0.036 0.036 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.036 0.036 Surface 0/5 < MDL < MDL < MDL NA 0.036 2.3 EW-SW-3 At depth 1/5 0.047 0.047 0.047 NA 0.036 2.3 EW-SW-4 Surface 0/1 < MDL < MDL < MDL NA 2.3 2.3

King County C‐21 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL At depth 0/1 < MDL < MDL < MDL NA 2.29 2.29 Surface 2/4 0.067 0.182 0.067 NA 0.036 0.036 EW-SW-5 At depth 0/4 < MDL < MDL < MDL NA 0.036 0.036 Surface 2/4 0.04 0.229 0.04 NA 0.036 0.036 EW-SW-6 At depth 0/4 < MDL < MDL < MDL NA 0.036 0.036 EW-SW-6 - Surface 1/1 0.098 0.098 0.098 NA NA NA Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.036 0.036 LDW-4.8 Surface 10/12 0.0089 0.029 0.017 0.0172 0.005 0.005 GR-11.1 Surface 8/80 0.051 0.45 < MDL 0.0702 0.025 0.2 GR-11.6 Surface 1/2 0.2 0.2 < MDL NA 0.2 0.2 GR-40.6 Surface 0/43 < MDL < MDL < MDL NA 0.025 0.2 GR-63.1 Surface 0/39 < MDL < MDL < MDL NA 0.025 0.2 GR-11.1 Surface 68/68 1140 4940 2400 2670 NA NA Magnesium, GR-40.6 dissolved Surface 28/28 588 4700 1190 1360 NA NA GR-63.1 Surface 32/32 568 1120 776 819 NA NA GR-11.1 Surface 42/42 7.52 111 17.6 29.6 NA NA Manganese, GR-11.6 dissolved Surface 1/1 28 28 28 NA NA NA GR-63.1 Surface 36/36 7.9 101.45 21.9 28.3 NA NA Surface 2/5 0.00016 0.00146 0.00016 NA 0.00015 0.00015 EW-SW-1 At depth 2/6 0.00035 0.00084 0.00035 NA 0.00015 2.00E-04 EW-SW-1 - Surface 1/1 0.00066 0.00066 0.00066 NA NA NA Flood tide At depth 1/1 0.0011 0.0011 0.0011 NA NA NA Mercury, Surface 2/6 0.00017 0.00086 0.00017 NA 0.00015 0.00015 EW-SW-2 dissolved At depth 0/5 < MDL < MDL < MDL NA 0.00015 0.00015 EW-SW-2 - Surface 1/1 0.00082 0.00082 0.00082 NA NA NA Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.00015 0.00015 Surface 1/5 0.00081 0.00081 < MDL NA 0.00015 0.00015 EW-SW-3 At depth 1/5 0.00044 0.00044 < MDL NA 0.00015 2.00E-04

King County C‐22 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL Surface 0/1 < MDL < MDL < MDL NA 0.00015 0.00015 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.00015 0.00015 Surface 1/4 0.00063 0.00063 < MDL NA 0.00015 0.00015 EW-SW-5 At depth 0/4 < MDL < MDL < MDL NA 0.00015 0.00015 Surface 2/4 0.00018 0.00049 0.00018 NA 0.00015 0.00015 EW-SW-6 At depth 0/4 < MDL < MDL < MDL NA 0.00015 0.00015 EW-SW-6 - Surface 1/1 0.00047 0.00047 0.00047 NA NA NA Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.00015 0.00015 LDW-4.8 Surface 3/13 0.00024 0.000884 0.00035 0.000452 NA NA GR-11.1 Surface 0/67 0.00033 0.000908 0.000597 0.000633 0.005 0.2 GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 0.2 0.2 GR-40.6 Surface 1/21 0.0057 0.0057 < MDL NA 0.005 0.2 GR-63.1 Surface 0/37 0.00023 0.0058 0.00048 0.00069 0.005 0.005 GR-11.1 Surface 9/65 0.107 0.57 0.145 0.168 0.5 0.5 Molybdenum, GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 0.5 0.5 dissolved GR-40.6 Surface 10/28 0.0754 0.588 0.1 0.118 0.5 0.5 GR-63.1 Surface 10/39 0.0603 0.14 0.09 0.0987 0.5 0.5 Surface 1/5 0.28 0.28 < MDL NA 0.03 0.34 EW-SW-1 At depth 1/5 0.44 0.44 < MDL NA 0.03 0.34 EW-SW-1 - Surface 0/1 < MDL < MDL < MDL NA 0.03 0.03 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.03 0.03 Surface 3/5 0.37 0.53 0.37 0.425 0.05 0.34 Nickel, EW-SW-2 dissolved At depth 2/5 0.34 0.37 0.34 NA 0.05 0.34 EW-SW-2 - Surface 1/1 0.53 0.53 0.53 NA NA NA Flood tide At depth 1/1 0.38 0.38 0.38 NA NA NA Surface 1/5 0.53 0.53 < MDL NA 0.03 0.34 EW-SW-3 At depth 2/5 0.4 0.85 0.4 NA 0.05 0.34 EW-SW-4 Surface 0/1 < MDL < MDL < MDL NA 0.34 0.34

King County C‐23 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL At depth 0/1 < MDL < MDL < MDL NA 0.34 0.34 Surface 2/4 0.41 0.58 0.41 NA 0.03 0.05 EW-SW-5 At depth 1/4 0.28 0.28 0.28 NA 0.03 0.05 Surface 1/4 0.53 0.53 < MDL NA 0.03 0.05 EW-SW-6 At depth 2/4 0.27 0.375 0.27 NA 0.05 0.05 EW-SW-6 - Surface 0/1 < MDL < MDL < MDL NA 0.03 0.03 Flood tide At depth 1/1 0.5 0.5 0.5 NA NA NA LDW-4.8 Surface 12/12 0.156 1.09 0.26 0.419 NA NA GR-11.1 Surface 66/80 0.14 1.5 0.34 0.373 0.3 0.3 GR-11.6 Surface 1/2 0.315 0.315 < MDL NA 0.3 0.3 GR-40.6 Surface 7/43 0.054 7.79 < MDL 0.263 0.05 0.3 GR-63.1 Surface 11/39 0.071 1.89 0.093 0.15 0.3 0.3 GR-11.1 Surface 8/48 440 1210 837 917 2000 2000 Potassium, GR-40.6 dissolved Surface 8/8 190 370 240 268 NA NA GR-63.1 Surface 0/32 < MDL < MDL < MDL NA 2000 2000 Surface 5/5 0.07 0.17 0.1 0.112 NA NA EW-SW-1 At depth 7/7 0.08 0.25 0.19 0.176 NA NA EW-SW-1 - Surface 1/1 0.08 0.08 0.08 NA NA NA Flood tide At depth 1/1 0.37 0.37 0.37 NA NA NA Surface 5/6 0.06 0.35 0.18 0.165 0.05 0.05 EW-SW-2 At depth 5/5 0.1 0.26 0.19 0.18 NA NA Selenium, dissolved EW-SW-2 - Surface 1/1 0.38 0.38 0.38 NA NA NA Flood tide At depth 1/1 0.19 0.19 0.19 NA NA NA Surface 5/5 0.08 0.35 0.14 0.17 NA NA EW-SW-3 At depth 5/5 0.06 0.28 0.19 0.188 NA NA Surface 1/1 0.15 0.15 0.15 NA NA NA EW-SW-4 At depth 1/1 0.14 0.14 0.14 NA NA NA EW-SW-5 Surface 4/4 0.08 0.2 0.12 0.132 NA NA

King County C‐24 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL At depth 4/4 0.095 0.27 0.1 0.169 NA NA Surface 4/4 0.07 0.3 0.08 0.16 NA NA EW-SW-6 At depth 4/4 0.08 0.26 < MDL 0.17 NA NA EW-SW-6 - Surface 1/1 0.23 0.23 0.23 NA NA NA Flood tide At depth 1/1 0.2 0.2 0.2 NA NA NA GR-11.1 Surface 0/64 < MDL < MDL < MDL NA 0.5 1.5 GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 1.5 1.5 GR-40.6 Surface 0/28 < MDL < MDL < MDL NA 0.5 1.5 GR-63.1 Surface 0/39 < MDL < MDL < MDL NA 0.5 1.5 Surface 0/5 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-1 At depth 0/5 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-1 - Surface 0/1 < MDL < MDL < MDL NA 0.01 0.01 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.01 0.01 Surface 1/5 0.019 0.019 0.019 NA 0.008 0.012 EW-SW-2 At depth 0/5 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-2 - Surface 0/1 < MDL < MDL < MDL NA 0.01 0.01 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.01 0.01 Surface 0/5 < MDL < MDL < MDL NA 0.008 0.012 Silver, EW-SW-3 dissolved At depth 0/5 < MDL < MDL < MDL NA 0.008 0.012 Surface 0/1 < MDL < MDL < MDL NA 0.012 0.012 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.012 0.012 Surface 0/4 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-5 At depth 0/4 < MDL < MDL < MDL NA 0.008 0.012 Surface 0/4 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-6 At depth 0/4 < MDL < MDL < MDL NA 0.008 0.012 EW-SW-6 - Surface 0/1 < MDL < MDL < MDL NA 0.01 0.01 Flood tide At depth 0/1 < MDL < MDL < MDL NA 0.01 0.01 LDW-4.8 Surface 3/12 0.0195 0.022 < MDL 0.0198 0.01 0.01

King County C‐25 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL GR-11.1 Surface 0/78 < MDL < MDL < MDL NA 0.025 0.2 GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 0.2 0.2 GR-40.6 Surface 0/42 < MDL < MDL < MDL NA 0.01 0.2 GR-63.1 Surface 0/39 < MDL < MDL < MDL NA 0.025 0.2 GR-11.1 Surface 48/48 2690 16300 5500 6950 NA NA Sodium, GR-40.6 dissolved Surface 8/8 2430 3650 3080 3100 NA NA GR-63.1 Surface 33/33 2100 3460 2660 2690 NA NA Strontium, GR-11.1 Surface 2/2 18.9 19.4 19.15 NA NA NA dissolved GR-63.1 Surface 1/1 8.4 8.4 8.4 NA NA NA Surface 3/5 0.005 0.009 0.007 0.007 0.005 0.005 EW-SW-1 At depth 3/5 0.01 0.011 0.011 0.0107 0.005 0.005 EW-SW-1 - Surface 0/1 < MDL < MDL < MDL NA 0.003 0.003 Flood tide At depth 1/1 0.011 0.011 0.011 NA NA NA Surface 3/5 0.007 0.008 0.0075 0.0075 0.005 0.005 EW-SW-2 At depth 3/5 0.009 0.01 0.01 0.00967 0.005 0.005 EW-SW-2 - Surface 1/1 0.008 0.008 0.008 NA NA NA Flood tide At depth 1/1 0.008 0.008 0.008 NA NA NA Surface 3/5 0.007 0.011 0.009 0.009 0.005 0.005 Thallium, EW-SW-3 dissolved At depth 3/5 0.009 0.011 0.009 0.00967 0.005 0.005 Surface 0/1 < MDL < MDL < MDL NA 0.005 0.005 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.005 0.005 Surface 3/4 0.008 0.009 0.008 0.00833 0.005 0.005 EW-SW-5 At depth 4/5 0.009 0.012 0.01 0.0105 0.005 0.005 Surface 3/4 0.007 0.009 0.007 0.00767 0.005 0.005 EW-SW-6 At depth 3/4 0.0095 0.011 0.01 0.0102 0.005 0.005 EW-SW-6 - Surface 1/1 0.004 0.004 0.004 NA NA NA Flood tide At depth 1/1 0.007 0.007 0.007 NA NA NA GR-11.1 Surface 0/63 < MDL < MDL < MDL NA 0.01 0.2

King County C‐26 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL GR-11.6 Surface 0/1 < MDL < MDL < MDL NA 0.2 0.2 GR-40.6 Surface 0/26 < MDL < MDL < MDL NA 0.01 0.2 GR-63.1 Surface 0/39 < MDL < MDL < MDL NA 0.01 0.2 Surface 5/5 0.473 1.29 1.05 0.924 NA NA EW-SW-1 At depth 5/5 1.01 1.68 1.38 1.35 NA NA EW-SW-1 - Surface 1/1 0.628 0.628 0.628 NA NA NA Flood tide At depth 1/1 0.833 0.833 0.833 NA NA NA Surface 5/5 0.822 1.39 1.14 1.11 NA NA EW-SW-2 At depth 5/5 1.27 1.55 1.37 1.4 NA NA EW-SW-2 - Surface 1/1 1.17 1.17 1.17 NA NA NA Flood tide At depth 1/1 1.39 1.39 1.39 NA NA NA Surface 5/5 0.967 1.48 1.28 1.29 NA NA EW-SW-3 At depth 5/5 1.24 1.54 1.33 1.35 NA NA Vanadium, Surface 1/1 1.17 1.17 1.17 NA NA NA EW-SW-4 dissolved At depth 1/1 0.029 0.029 0.029 NA NA NA Surface 4/4 0.755 1.37 1.28 1.18 NA NA EW-SW-5 At depth 4/4 1.25 1.63 1.44 1.44 NA NA Surface 4/4 0.5 1.45 1.31 1.17 NA NA EW-SW-6 At depth 4/4 1.37 1.62 1.41 1.46 NA NA EW-SW-6 - Surface 1/1 1.09 1.09 1.09 NA NA NA Flood tide At depth 1/1 1.29 1.29 1.29 NA NA NA GR-11.1 Surface 62/63 0.281 0.88 0.55 0.554 0.3 0.3 GR-11.6 Surface 1/1 0.53 0.53 0.53 NA NA NA GR-40.6 Surface 28/28 0.445 1 0.595 0.622 NA NA GR-63.1 Surface 38/38 0.5 1.1 0.67 0.679 NA NA Surface 3/5 0.79 6.77 2.44 2.9 0.08 0.08 Zinc, EW-SW-1 dissolved At depth 3/5 0.78 1.08 0.84 0.9 0.08 0.08 EW-SW-1 - Surface 1/1 0.9 0.9 0.9 NA NA NA

King County C‐27 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Meana MDL MDL Flood tide At depth 1/1 1.04 1.04 1.04 NA NA NA Surface 3/5 1.65 4.62 2.28 2.85 0.08 0.08 EW-SW-2 At depth 3/5 0.6 1.25 1.22 1.02 0.08 0.08 EW-SW-2 - Surface 1/1 1.69 1.69 1.69 NA NA NA Flood tide At depth 1/1 1.04 1.04 1.04 NA NA NA Surface 3/5 1.95 2.26 2.02 2.08 0.08 0.08 EW-SW-3 At depth 3/5 1.08 1.43 1.43 1.31 0.08 0.08 Surface 0/1 < MDL < MDL < MDL NA 0.08 0.08 EW-SW-4 At depth 0/1 < MDL < MDL < MDL NA 0.08 0.08 Surface 3/4 4.69 7.79 4.69 6.16 0.08 0.08 EW-SW-5 At depth 3/4 0.87 1.5 0.925 1.1 0.08 0.08 Surface 3/4 2.2 4.03 2.2 2.96 0.08 0.08 EW-SW-6 At depth 3/4 0.66 0.865 0.79 0.772 0.08 0.08 EW-SW-6 - Surface 1/1 4.84 4.84 4.84 NA NA NA Flood tide At depth 1/1 0.68 0.68 0.68 NA NA NA LDW-4.8 Surface 14/14 0.46 1.27 0.628 0.764 NA NA GR-11.1 Surface 71/86 0.4 16.9 1.16 2.02 0.5 0.5 GR-11.6 Surface 2/2 1.095 6.44 3.7675 NA NA NA GR-40.6 Surface 13/45 0.22 15.1 0.22 0.771 0.5 0.5 GR-63.1 Surface 25/39 0.23 1.45 0.39 0.499 0.5 0.5 FOD = frequency of detection; MDL = method detection limit. a Means were calculated using the Kaplan‐Meier methodology.

King County C‐28 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Organic Compounds

Table C-3. Concentrations of organic compounds (µg/L) at each sampling site in the Green-Duwamish Area split by depth. Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 0/5

Surface 0/5

At depth 0/5

EW-SW-6 Surface 0/4

King County C‐29 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 1/5 0.015 0.015

King County C‐30 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 0/1

King County C‐31 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL EW-SW-6 - Surface 0/1

King County C‐32 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL DR-6.3 Surface 4/7 0.00066 0.00117 0.000655 0.00081 0.0005 0.0005 DR-9.8 Surface 9/11 0.00033 0.00082 0.00038 0.00049 0.00024 0.00024 GR-11.1 Surface 5/30 0.0006 0.002 0.000595 0.00079 0.0005 0.011 GR-40.6 Surface 0/8

King County C‐33 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL EW-SW-1 - Surface 0/1

King County C‐34 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL At depth 0/5

King County C‐35 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 0/5

King County C‐36 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL At depth 0/1

King County C‐37 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL EW-SW-6 - Surface 0/1

King County C‐38 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL GR-63.1 Surface 0/14

King County C‐39 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 0/5

King County C‐40 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 0/4

King County C‐41 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Flood Tide At depth 0/1

King County C‐42 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL LDW-0.1 Surface 2/6 0.012 0.037 0.012 NA 0.0094 0.024 GR-11.1 Surface 9/21 0.017 0.641

King County C‐43 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL At depth 0/5

King County C‐44 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 0/5

King County C‐45 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 0/1

King County C‐46 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 0/5

King County C‐47 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Flood Tide At depth 0/1

King County C‐48 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL At depth 0/4

King County C‐49 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL LDW-0.1 Surface 7/8 0.012 0.0307 0.015 0.0175 0.0094 0.0094 DR-6.3 Surface 5/7 0.00145 0.00308 0.00165 0.00201 0.001 0.001 DR-9.8 Surface 2/2 0.00353 0.00891 0.0062188 NA NA NA

GR-11.1 Surface 13/30 0.00105 0.0232 0.0018 0.00546 0.001 0.011 GR-40.6 Surface 0/8

King County C‐50 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL GR-40.6 Surface 0/8

King County C‐51 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Surface 0/5

King County C‐52 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Flood Tide At depth 0/1

King County C‐53 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL Flood Tide At depth 0/1

King County C‐54 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL GR-63.1 Surface 0/9

King County C‐55 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL At depth 0/5

King County C‐56 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL At depth 0/1

GR-11.1 Surface 13/31 0.001 0.132 0.0018 0.00967 0.001 0.011 GR-40.6 Surface 1/8 0.012 0.012

King County C‐57 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL At depth 5/5 82.4 551.4 289 289 NA NA Surface 4/4 255.1 910.6 621 654 NA NA EW-SW-6 At depth 4/4 67.7 1655 389 652 NA NA EW-SW-6 - Surface 1/1 5838 5838 5838 NA NA NA Flood Tide At depth 1/1 168.7 168.7 168.7 NA NA NA Surface 4/4 590.8 1947.3 1020 1340 NA NA WW-a At depth 3/3 250.1 1813.7 547 870 NA NA Surface 4/4 398.4 1521.45 1070 1030 NA NA LDW-3.3 At depth 4/4 131.8 3211 1340 1640 NA NA Surface 0/5

King County C‐58 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Minimum Maximum Parameter Site Depth FOD Minimum Maximum Median Mean MDL MDL GR-11.1 Surface 1/2 1.01 1.01

King County C‐59 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

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King County C‐60 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

APPENDIX D: SEDIMENT CHEMISTRY

King County D‐1 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure D-1. Concentrations (µg/Kg-dw) of the human health risk driver total PCBs along the East, West, and Lower Duwamish waterways. Sources: Lower Duwamish Waterway Feasibility Study (AECOM, 2012), East Waterway Supplemental Remedial Investigation (Windward and Anchor QEA, 2014), Urban Waters Initiative (Ecology, 2007), and PSEMP Data Base (Ecology, 2015).

King County D‐2 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure D-2 Concentrations of the human health risk driver arsenic (mg/kg dw) along the East West, and Lower Duwamish waterways. Sources: (Windward, 2010; Windward and Anchor QEA, 2014; Urban Waters Initiative (Ecology, 2007); and PSEMP database (Ecology, 2015).

King County D‐3 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure D-3. Concentrations of the human health risk driver cPAHs (µg TEQ/kg dw) along the East, West, and Lower Duwamish waterways. Sources: AECOM, 2012; Windward and Anchor QEA, 2014; Urban Waters Initiative (Ecology, 2007); and PSEMP database (Ecology, 2015).

King County D‐4 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Figure D-4. Concentrations of dioxins and furans (ng TEQ/kg dw) in the East, West, and Lower Duwamish waterways. Sources: AECOM, 2012; Windward and Anchor QEA, 2014; Urban Waters Initiative (Ecology, 2007); and PSEMP database (Ecology, 2015).

King County D‐5 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

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King County D‐6 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table D-1. East Waterway and Lower Duwamish Waterway sediment management standards (SMS) benthic exceedances and levels of human health risk drivers (East Waterway – Lower Duwamish Waterway river mile 2.0)

d ERA Contaminants of Concerna (SMS exceedances) HHRA Risk Driverb,c

Metals Polycyclic Aromatic Hydrocarbons Bases, Neutrals, Acids Phthalates Chlorobenzenes e

j r

i i

g h

k and

f l e e te te ne ne es River Miles 2,4- 1,2- 1,4- Zinc cPAHs Arsenic Arsenic Lead Lead mine 1,2,4- Silver acene acene Phenol Pyrene Copper Copper Arsenic Arsenic Mercury Mercury Total PCBs Total PCBs Fluorene Fluorene 2-Methyl- phthalate phthalate phthalate Cadmium Cadmium Chrysene Chrysene Di-n-butyl Di-n-butyl cd)pyrene cd)pyrene Chromium Chromium Anthracene Anthracene Dioxins/furans Total LPAH naphthalene naphthalene Total HPAH Butyl benzyl Naphthalene Benzoic acid acid Benzoic Indeno(1,2,3- Fluoranthene Fluoranthene Dibenzofuran Dibenzofuran Phenanthrene Phenanthrene Acenaphthene Acenaphthene Benzyl alcohol 4-Methylphenol 4-Methylphenol Benzo(a)pyrene Dimethylphenol Dichlorobenzene Dichlorobenzene Nitrosodiphenyla East Waterway Segments East Waterway Trichlorobenzene Benzofluoranthen Dibenzo(a,h)anth Benzo(g,h,i)peryle Pentachloropheno ethylhexyl)phthala Hexachlorobenzen Dimethyl phthalate Dimethyl Lower Duwamish Waterway Duwamish Waterway Lower Benzo(a)anthracen EW 1 C C C C C C S C C C C C C C C C C C C C S C X X X EW 2 C C S S S S S C S S S S C C C X X EW 3 S C C C S S C C C S C S C C X X EW 4 C C S C S S S S S S C S C C S C S C C X X EW 5 S C S X X 0.0 - 0.1 C C C C S S S S C C C X X X 0.1 - 0.2 S S S S S S S S S S S X 0.2 - 0.3 C S S 0.3 - 0.4 C S S S S S C C S S C X X 0.4 - 0.5 C S S C S S C C S C S C X X X 0.5 - 0.6 C C C C C C C C C C C C C C C C C S C X X X 0.6 - 0.7 C S S S S X X 0.7 - 0.8 S S 0.8 - 0.9 S S S C 0.9 - 1.0 C S S 1.0 - 1.1 C C C C C S S S S S S C C C S C C C C C C S S C X X X X 1.1 - 1.2 C C 1.2 - 1.3 S C S S S 1.3 - 1.4 C C C C C S S S S S S S S C X 1.4 - 1.5 S S S C X X 1.5 - 1.6 C S S S X 1.6 - 1.7 C 1.7 - 1.8 S S 1.8 - 1.9 C C C 1.9 - 2.0 C S

King County D‐7 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table D-1. East Waterway and Lower Duwamish Waterway sediment management standards (SMS) benthic exceedances and levels of human health risk drivers (East Waterway – Lower Duwamish Waterway river mile 2.0) (continued)

d ERA Contaminants of Concerna (SMS exceedances) HHRA Risk Driverb,c

Metals Polycyclic Aromatic Hydrocarbons Bases, Neutrals, Acids Phthalates Chlorobenzenes e

j r

i i

g h

k and

f l e e te te ne ne es River Miles 2,4- 1,2- 1,4- Zinc cPAHs Arsenic Arsenic mine mine Lead Lead 1,2,4- Silver acene acene Pyrene Phenol Copper Copper Arsenic Arsenic Mercury Mercury Total PCBs Total PCBs Fluorene Fluorene 2-Methyl- phthalate phthalate phthalate Cadmium Cadmium Chrysene Chrysene Di-n-butyl Di-n-butyl cd)pyrene cd)pyrene Chromium Chromium Anthracene Anthracene Dioxins/furans Total LPAH Butyl benzyl naphthalene naphthalene Total HPAH Naphthalene Benzoic acid acid Benzoic Indeno(1,2,3- Fluoranthene Fluoranthene Dibenzofuran Dibenzofuran Phenanthrene Phenanthrene Acenaphthene Acenaphthene Benzyl alcohol 4-Methylphenol 4-Methylphenol Benzo(a)pyrene Benzo(a)pyrene Dimethylphenol Dichlorobenzene Dichlorobenzene Dichlorobenzene Nitrosodiphenyla Trichlorobenzene Trichlorobenzene East Waterway Segments East Waterway Benzofluoranthen Dibenzo(a,h)anth Benzo(g,h,i)peryle Pentachloropheno ethylhexyl)phthala Hexachlorobenzen Dimethyl phthalate Dimethyl Lower Duwamish Waterway Duwamish Waterway Lower Benzo(a)anthracen 2.0 - 2.1 S 2.1 - 2.2 S S S S X 2.2 - 2.3 C C C C C C C C C C C C C C C C C C C S C C C C C C C X X X 2.3 - 2.4 S S S S 2.4 - 2.5 S S 2.5 - 2.6 C S S S S S C 2.6 - 2.7 C S S C S S C S S S C S S S S C S S X 2.7 - 2.8 C S S S C S C S C S C C C S X 2.8 - 2.9 S C 2.9 - 3.0 S 3.0 - 3.1 C S 3.1 - 3.2 S 3.2 - 3.3 S S 3.3 - 3.4 3.4 - 3.5 S 3.5 - 3.6 S X 3.6 - 3.7 S S 3.7 - 3.8 C S S S C C C C C S C S C S S S S S C S C X X 3.8 - 3.9 C C C C S C C 3.9 - 4.0 S S S S 4.0 - 4.1 S S S C 4.1 - 4.2 C S S S S S C C S C X 4.2 - 4.3 S S S S S 4.3 - 4.4 S S S S 4.4 - 4.5

King County D‐8 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table D-1. East Waterway and Lower Duwamish Waterway sediment management standards (SMS) benthic exceedances and levels of human health risk drivers (East Waterway – Lower Duwamish Waterway river mile 2.0) (continued)

e ERA Contaminants of Concerna (SMS exceedances) HHRA Risk Driverb,c Metals Polycyclic Aromatic Hydrocarbons Bases, Neutrals, Acids Phthalates Chlorobenzenes d

f

j

i i

g h

k and Zinc cPAHs Arsenic Arsenic Lead Lead Silver Pyrene Phenol Copper Copper Arsenic Arsenic Mercury Mercury Total PCBs Total PCBs Fluorene Fluorene Cadmium Cadmium Chrysene Chromium Chromium Anthracene Anthracene Dioxins/furans Total LPAH Total HPAH Naphthalene Benzoic acid acid Benzoic Fluoranthene Fluoranthene Dibenzofuran Dibenzofuran Phenanthrene Phenanthrene Acenaphthene Acenaphthene Benzyl alcohol 4-Methylphenol 4-Methylphenol Benzo(a)pyrene Benzo(a)pyrene East Waterway Segments East Waterway Dimethyl phthalate Dimethyl Pentachlorophenol Pentachlorophenol 2,4-Dimethylphenol 2,4-Dimethylphenol Di-n-butyl phthalate phthalate Di-n-butyl Hexachlorobenzene Benzo(a)anthracene Benzo(a)anthracene 1,2-Dichlorobenzene 1,2-Dichlorobenzene 1,4-Dichlorobenzene Benzo(g,h,i)perylene Benzo(g,h,i)perylene 2-Methyl-naphthalene 2-Methyl-naphthalene Butyl benzyl phthalate 1,2,4-Trichlorobenzene 1,2,4-Trichlorobenzene Indeno(1,2,3-cd)pyrene Indeno(1,2,3-cd)pyrene Dibenzo(a,h)anthracene Dibenzo(a,h)anthracene n-Nitrosodiphenylamine n-Nitrosodiphenylamine Bis(2-ethylhexyl)phthalate Bis(2-ethylhexyl)phthalate Total Benzofluoranthenes Lower Duwamish Waterway River Miles River Duwamish Waterway Lower 4.5 - 4.6 S 4.6 - 4.7 S 4.7 - 4.8 C S S C 4.8 - 4.9 C C X 4.9 - 5.0 S S S S C S C C Sources: East Waterway Operable Unit Supplemental Remedial Investigation (Windward and Anchor QEA, 2014) and the Lower Duwamish Waterway Final Feasibility Study (AECOM, 2012). Notes: a. ERA contaminants of concern identifed as contaminants exceeding SQS or CSL limits. b. HHRA risk drivers identified from seafood consumption and/or direct sediment exposure scenarios. c. The EW segments and LDW river mile sections demarcated with an X have surface sediment sample(s) with elevated levels of a risk driver that have been identified through human health risk assessment. d. East Waterway segments: EW 1 = Mouth of East Waterway to former GATX property, EW 2 = Lander St. CSO/SD to former GATX property, EW 3 = Handford #2 CSO to Lander St. CSO/SD, EW 4 = SW Hinds St. CSO/SD to Hanford #2 CSO, EW 5 = Head of East Waterway to SW Hinds St. CSO/SD. e. Lower Duwamish Waterway river miles start at the south end of Harbor Island f. Total benzofluoranthenes were calculated as the sum of benzo(b)fluoranthene and benzo(k)fluoranthene. g. Total HPAHs were calculated as the sum of benzo(a)anthracene, benzo(a)pyrene, benzo(g,h,i)perylene, total benzofluoranthenes, chrysene, dibenzo(a,h)anthracene, fluoranthene, indeon(1,2,3‐cd)pyrene, and pyrene. h. Total LPAHs were calculated as the sum of acenaphthene, acenaphthylene, anthracene, fluorine, naphthalene, and phenathrene. i. Total PCBs represents the sum of the detected concentration of the individual Aroclors. If none of the individual Aroclors were detected in a given sample, the non‐detect value represents the highest reporting limit. j. Dioxin and furan TEQs were calculated using TEFs for mammals. k. cPAH TEQ calculated using compound‐specific potency equivalency factors.

C = exceeds SMS cleanup screening levels, cPAH = carcinogenic polycyclic aromatic hydrocarbons, CSL = cleanup screening level, ERA = ecological risk assessment, EW = East Waterway, HHRA = human health risk assessment, LDW = Lower Duwamish Waterway, PCBs = polychlorinated biphenyls, S = exceeds SMS sediment cleanup objective, SCO = sediment cleanup objective, SMS = Sediment Management Standards (WAC Chapter 173‐204)

King County D‐9 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

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King County D‐10 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table D-2. Metals analyses of the East Waterway and Lower Duwamish Waterway surface sediment samples.

Detected/ SMS >SQS/SCO, Water- Total Min Max SQS/ SMS < CSL, > CSL, HHRA ERA Chemical way sa mple s detect detect Meana Unit SCO CSL Unit detected detected RD RD EW 162/231 2.3 241 9.0mg/kg mg/kg 0 2 Yes Yes Arsenic 57 93 LDW 857/916 1.2 1,100 17dw dw 5 9 Yes Yes EW 155/231 0.126 6.76 0.70mg/kg mg/kg 1 1 No Yes Cadmium 5.1 6.7 LDW 632/894 0.03 120 1.0dw dw 2 12 No Yes EW 231/231 8 82 J 30mg/kg mg/kg 0 0 No No Chromium 260 270 LDW 906/906 4.8 1,680 42dw dw 1 10 No Yes EW 231/231 11.3 272 J 59mg/kg mg/kg 0 0 No No Copper 390 390 LDW 908/908 5.0 12,000 106dw dw 0 13 No Yes EW 228/231 3 208 50mg/kg mg/kg 0 0 No No Lead 450 530 LDW 908/908 2.0 23,000 139dw dw 2 23 No Yes EW 233/239 0.02 J 1.07 J 0.30mg/kg mg/kg 36 10 No Yes Mercury 0.41 0.59 LDW 813/927 0.015 247 0.53dw dw 20 30 No Yes EW 219/220 7.0 56 20mg/kg mg/kg n/a n/a No No Nickel n/a n/a LDW 836/836 5.0 910 28dw dw n/a n/a No No EW 97/231 0.110 6 0.60mg/kg mg/kg 0 0 No No Silver 6.1 6.1 LDW 537/875 0.018 270 1.0dw dw 0 10 No Yes EW 231/231 25.3 J 1,230 J 100mg/kg mg/kg 4 1 No Yes Zinc 410 960 LDW 905/905 16 9,700 194dw dw 26 19 No Yes Tributyltin EW 60/67 1.6 J 6,000 180mg/kg mg/kg n/a n/a No No n/a n/a (as ion) dw dw LDW 178/189 0.28 3,000 90 n/a n/a No No Sources: East Waterway Operable Unit Supplemental Remedial Investigation/ Feasibility Study (Port of Seattle, 2014) and the Lower Duwamish Waterway Final Feasibility Study (AECOM, 2012).

Notes: a The calculated mean concentrations were based on detected concentrations and one‐half reporting limits for non‐detected results.

COC = contaminant of concern; CSL = cleanup screening level; dw = dry weight; ERA = ecological risk assessment (contaminant of concern); EW = East Waterway; HHRA = human health risk assessment (risk driver); J = estimated concentration; kg = kilograms; LDW = Lower Duwamish Waterway; mg = milligrams; n/a = not applicable; RD = risk driver; SMS = sediment management standards; SCO = sediment cleanup objective

King County D‐11 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table D-3. PAH analyses of East Waterway and Lower Duwamish Waterway surface sediments

De te cte d/ SMS >SQS/SCO, Water- Total Min Max SQS/S SMS < CSL, > CSL, HHRA ERA Chemical way samplesa detect detect Meanb Unit COc CSLc Unit detected detected RD RD EW 237/240 3.0 J 148,000 J 4,200mg/kg 8 1 No Yes Total HPAHd µg/kg dw 960 5,300 LDW 873/891 20 85,000 3809oc 25 6 No Yes EW 226/240 9.8 J 9,000 330mg/kg 6 1 No Yes Benzo(a)anthracene µg/kg dw 110 270 LDW 821/891 7.3 J 8,400 322oc 10 6 No Yes EW 225/240 15 J 7,800 320mg/kg 6 1 No Yes Benzo(a)pyrene µg/kg dw 99 210 LDW 819/886 6.5 7,900 309oc 7 5 No Yes EW 212/240 10 J 1800 110mg/kg 4 0 No Yes Benzo(g,h,i)perylene µg/kg dw 31 78 LDW 763/891 6.1 3,800 165oc 10 12 No Yes Total EW 228/240 14 J 10,800 750mg/kg 6 1 No Yes µg/kg dw 230 450 benzofluoranthenesf LDW 829/885 6.6 J 17,000 732oc 6 6 No Yes EW 230/240 12 J 13,000 520mg/kg 7 1 No Yes Chrysene µg/kg dw 110 460 LDW 846/891 12 7,700 474oc 29 3 No Yes EW 156/240 3.0 J 690 39mg/kg 4 0 No Yes Dibenzo(a,h)anthracene µg/kg dw 12 33 LDW 498/891 1.6 J 1,500 63oc 18 6 No Yes EW 233/240 12 J 75,000 1,100mg/kg 12 2 No Yes Fluoranthene µg/kg dw 160 1,200 LDW 868/891 18 24,000 889oc 35 12 No Yes EW 210/240 11 J 1,800 120mg/kg 6 0 No Yes Indeno(1,2,3-cd)pyrene µg/kg dw 34 88 LDW 801/891 6.4 4,300 180oc 16 13 No Yes EW 235/240 18 J 41,000 900mg/kg 0 1 No Yes Pyrene µg/kg dw 1,000 1,400 LDW 860/891 19 16,000 723oc 2 6 No Yes EW 230/240 12 J 41,000 960mg/kg 5 3 No Yes Total LPAHg µg/kg dw 370 780 LDW 835/891 9.1 44,000 696oc 4 3 No Yes EW 126/240 10 J 3,000 97mg/kg 10 6h No Yes Acenaphthene µg/kg dw 16 57 LDW 352/891 1.0 J 5,200 65oc 16 4 No Yes EW 109/240 4.4 J 630 35mg/kg 0 0 No No Acenaphthylene µg/kg dw 66 66 LDW 128/818 1.3 J 500 31oc 0 0 No No EW 209/240 10 J 6,500 200mg/kg 1 0 No Yes Anthracene µg/kg dw 220 1,200 LDW 647/891 1.3 10,000 134oc 2 0 No Yes EW 144/240 8.6 J 3,800 94mg/kg 9 3i No Yes Fluorene µg/kg dw 23 79 LDW 431/891 0.68 J 6,800 78oc 11 3 No Yes EW 118/240 9.5 J 3,000 52mg/kg 0 0 No No Naphthalene µg/kg dw 99 170 LDW 183/882 3.0 J 5,300 49oc 0 2 No Yes EW 230/240 12 J 24,000 520mg/kg 12 3 No Yes Phenanthrene µg/kg dw 100 480 LDW 832/891 7.1 28,000 429oc 27 3 No Yes EW 87/240 9.7 J 2,800 38mg/kg 0 1 No Yes 2-Methylnaphthalene µg/kg dw 38 64 LDW 169/882 0.38 J 3,300 42oc 1 4 No Yes EW 107/240 7.1 J 1,700 57mg/kg 6 2 No Yes Dibenzofuran µg/kg dw 15 58 LDW 276/889 1.0 J 4,200 54oc 7 3 No Yes Sources: East Waterway Operable Unit Supplemental Remedial Investigation/ Feasibility Study (Windward and Anchor QEA, 2014) and the Lower Duwamish Waterway Final Feasibility Study (AECOM, 2012).

Notes: a. A calculated total concentration result was considered detected if one or more of the components of the sum were detected. If none of the components of the sum were detected, the calculated total concentration was considered non‐detected. b. The calculated mean concentrations were based on detected concentrations and one‐half reporting limits for non‐detected results. c. Comparisons to SQS and CSL were made using organic carbon‐normalized concentrations for non‐polar organic compounds. If TOC in the sample was >4% or <0.5%, dry weight concentrations were compared to the LAET and 2LAET. d. Total HPAHs were calculated as the sum of benzo(a)anthracene, benzo(a)pyrene, benzo(g,h,i)perylene, total benzofluoranthenes, chrysene, dibenzo(a,h)anthracene, fluoranthene, indeon(1,2,3‐cd)pyrene, and pyrene. e. CPAH TEQ calculated using compound‐specific potency equivalency factors.

King County D‐12 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary f. Total benzofluoranthenes were calculated as the sum of benzo(b)fluoranthene and benzo(k)fluoranthene. g. Total LPAHs were calculated as the sum of acenaphthene, acenaphthylene, anthracene, fluorine, naphthalene, and phenathrene. h. One of the six samples could not be OC‐normalized because the TOC was outside of the appropriate range; the exceedance was based on a comparison with the 2LAET. i. One of the three samples could not be OC‐normalized because the TOC was outside of the appropriate range; the exceedance was based on a comparison with the 2LAET.

COC = contaminant of concern; CSL = cleanup screening level; dw = dry weight; ERA = ecological risk assessment; EW = East Waterway; HHRA = human health risk assessment (risk driver); J = estimated concentration; kg = kilograms; LDW = Lower Duwamish Waterway; LAET = lowest apparent effects threshold; 2LAET = second lowest apparent effects threshold; µg = micrograms; mg = milligrams; oc = organic carbon; RD = risk driver; SMS = sediment management standards; SCO = sediment cleanup objective; TOC = total organic carbon

King County D‐13 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table D-4. Base, neutral, acids analyses of the East Waterway and Lower Duwamish Waterway surface sediment samples

Detected/ SMS >SQS/SCO, Water- Total Min Max SQS/ SMS < CSL, > CSL, HHRA ERA Chemical way sa m ple s detect detect Meana Unit SCOb CSLb Unit detected detected RD RD EW 3/231 230 340 J 160µg/kg ug/kg 0 0 No No Benzoic acid 650 650 LDW 111/876 54 4,500 238dw dw 0 9 No Yes EW 2/220 19 J 38 J 14µg/kg ug/kg 0 0 No No Benzyl alcohol 57 73 LDW 30/867 8.2 670 49dw dw 9 7 No Yes Pentachloro- EW 10/231 59 110 J 49µg/kg ug/kg 0 0 No No 360 690 phenol LDW 30/840 14 14,000 122dw dw 1 1 No Yes EW 94/231 13 J 630 55µg/kg ug/kg 5 0 No Yes Phenol 420 1200 LDW 282/886 10 2,800 91dw dw 19 6 No Yes 2,4-Dimethyl- EW 14/231 6.1 90 J 13µg/kg ug/kg 0 1 No Yes 29 29 phenol LDW 29/869 6.1 290 44dw dw 0 25 No Yes EW 6/231 3.7 J 38 J 8.4µg/kg ug/kg 0 0 No No 2-Methylphenol 63 63 LDW 7/821 8.6 58 J 28dw dw 0 0 No No EW 48/231 9.6 J 200 24µg/kg ug/kg 0 0 No No 4-Methylphenol 670 670 LDW 116/883 4.8 4,600 44dw dw 0 4 No Yes n-Nitrosodiphenyl- EW 2/231 160 J 180 9.8µg/kg mg/kg 0 1c No Yes 11 11 amine dw oc LDW 24/871 6.5 230 27 0 2 No Yes Sources: East Waterway Operable Unit Supplemental Remedial Investigation/ Feasibility Study (Windward and Anchor QEA, 2014) and the Lower Duwamish Waterway Final Feasibility Study (AECOM, 2012).

Notes: a. The calculated mean concentrations were based on detected concentrations and one‐half reporting limits for non‐detected results. b. Comparisons to SCO and CSL were made using organic carbon‐normalized concentrations for non‐polar organic compounds. If TOC in the sample was >4% or <0.5%, dry weight concentrations were compared to the LAET and 2LAET. c. The sample could not be OC‐normalized because the TOC was outside of the appropriate range; the exceedance was based on a comparison with the 2LAET.

COC = contaminant of concern; CSL = cleanup screening level; dw = dry weight; ERA = ecological risk assessment; EW = East Waterway; HHRA = human health risk assessment (risk driver); J = estimated concentration; kg = kilograms; LDW = Lower Duwamish Waterway; LAET = lowest apparent effects threshold; 2LAET = second lowest apparent effects threshold; µg = micrograms; mg = milligrams; oc = organic carbon; RD = risk driver; SMS = sediment management standards; SCO = sediment cleanup objective; TOC = total organic carbon

King County D‐14 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table D-5. Phthalates analyses of the East Waterway and Lower Duwamish Waterway surface sediment samples

Detected/ SMS >SQS/SCO, Water- Total Min Max SQS/ SMS < CSL, > CSL, HHRA ERA Chemical way sa mpl e s detect detect Meana Unit SCOb CSLb Unit detected detected RD RD Bis(2-ethylhexyl) EW 207/231 18 J 37,000 410µg/kg mg/kg 4 5 No Yes 47 78 phthalate LDW 704/886 5.4 17,000 590dw oc 46 58 No Yes Benzyl butyl EW 101/231 4.8 J 290 26µg/kg mg/kg 9 0 No Yes 4.9 64 phthalate LDW 478/878 2.0 7,100 87dw oc 80 10 No Yes Diethyl EW 19/231 17 J 74 16µg/kg mg/kg 0 0 No No 61 110 phthalate LDW 41/832 2.0 J 150 30dw oc 0 0 No No Dimethyl EW 15/231 3.1 J 73 12µg/kg mg/kg 0 0 No No 53 53 phthalate LDW 186/878 2.0 J 440 25dw oc 0 2 No Yes Di-n-butyl EW 32/231 11 J 48,000 230µg/kg mg/kg 0 1 No Yes 220 1700 phthalate LDW 189/822 3.0 J 3,800 60dw oc 0 0 No No Di-n-octyl EW 9/231 14 J 83 16µg/kg mg/kg 0 0 No No 58 4500 phthalate dw oc LDW 49/832 1.8 1,000 38 0 0 No No Sources: East Waterway Operable Unit Supplemental Remedial Investigation/ Feasibility Study (Windward and Anchor QEA, 2014) and the Lower Duwamish Waterway Final Feasibility Study (AECOM, 2012).

Notes: a. The calculated mean concentrations were based on detected concentrations and one‐half reporting limits for non‐detected results. b. Comparisons to SCO and CSL were made using organic carbon‐normalized concentrations for non‐polar organic compounds. If TOC in the sample was >4% or <0.5%, dry weight concentrations were compared to the LAET and 2LAET.

COC = contaminant of concern; CSL = cleanup screening level; dw = dry weight; ERA = ecological risk assessment; EW = East Waterway; HHRA = human health risk assessment (risk driver); J = estimated concentration; kg = kilograms; LDW = Lower Duwamish Waterway; LAET = lowest apparent effects threshold; 2LAET = second lowest apparent effects threshold; µg = micrograms; mg = milligrams; oc = organic carbon; RD = risk driver; SMS = sediment management standards; SCO = sediment cleanup objective; TOC = total organic carbon

King County D‐15 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table D-6. Chlorobenzene analyses of the East Waterway and Lower Duwamish Waterway surface sediment samples.

Detected/ SMS >SQS/SCO, Water- Total Min Max SQS/ SMS < CSL, > CSL, HHRA ERA Chemical way sa mpl e s detect detect Meana Unit SCOb CSLb Unit detected detected RD RD 1,2,4-Trichloro- EW 7/231 4.3 J 9.3 4.8µg/kg mg/kg 0 0 No No 0.81 1.8 benzene LDW 6/871 1.6 J 940 19dw oc 0 2 No Yes 1,2-Dichloro- EW 2/231 6.2 11 4.2µg/kg mg/kg 0 0 No No 2.3 2.3 benzene LDW 19/871 1.3 J 670 J 19dw oc 0 4 No Yes 1,4-Dichloro- EW 146/231 1.9 15,000 120µg/kg mg/kg 20 9 No Yes 3.1 9 benzene LDW 50/871 1.5 J 1,600 J 23dw oc 0 4 No Yes Hexachloro- EW 0/232 nd nd ndµg/kg mg/kg 0 0 No No 0.38 2.3 benzene dw oc LDW 46/874 0.4 J 95 17 4 2 No Yes Sources: East Waterway Operable Unit Supplemental Remedial Investigation/ Feasibility Study (Windward and Anchor QEA, 2014) and the Lower Duwamish Waterway Final Feasibility Study (AECOM, 2012).

Notes: a. The calculated mean concentrations were based on detected concentrations and one‐half reporting limits for non‐detected results. b. Comparisons to SCO and CSL were made using organic carbon‐normalized concentrations for non‐polar organic compounds. If TOC in the sample was >4% or <0.5%, dry weight concentrations were compared to the LAET and 2LAET.

COC = contaminant of concern; CSL = cleanup screening level; dw = dry weight; ERA = ecological risk assessment; EW = East Waterway; J = estimated concentration; kg = kilograms; LDW = Lower Duwamish Waterway; LAET = lowest apparent effects threshold; 2LAET = second lowest apparent effects threshold; µg = micrograms; mg = milligrams; nd = non‐detected; oc = organic carbon; RD = risk driver; SMS = sediment management standards; SCO = sediment cleanup objective; TOC = total organic carbon

King County D‐16 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Table D-7. Analyses of human health risk assessment risk drivers in the East Waterway and Lower Duwamish Waterway surface sediment samples.

Detected/ SMS >SQS/SCO, Water- Total Min Max SQS/ SMS < CSL, > CSL, HHRA ERA Chemical way sa mpl e s detect detect Meana Unit SCOb CSLb Unit detected detected RD RD EW 227/240 6.0 8,400 490mg/kg 134 23 Yes Yes Total PCBs c µg/kg dw 12 65 LDW 1309/1390d 2.2 223,000d 1,136d OC 336 179 Yes Yes EW 162/231 2.3 241 9.0mg/kg 0 2 Yes Yes Arsenic mg/kg dw 57 93 LDW 857/916 1.2 1,100 17dw 5 9 Yes Yes EW 233/240 15 J 10,000 460µg TEQ/kg n/a n/a Yes No cPAHe n/a n/a n/a LDW 852/893 9.7 11,000 459dw n/a n/a Yes No EW 13/13 4.02 J 30.6 15.7ng TEQ/kg n/a n/a Yes No Dioxins/furansf,g n/a n/a n/a LDW 119/123 0.25 2,100 42dw n/a n/a Yes No Sources: East Waterway Operable Unit Supplemental Remedial Investigation/ Feasibility Study (Windward and Anchor QEA, 2014) and the Lower Duwamish Waterway Final Feasibility Study (AECOM, 2012).

Notes: a. The calculated mean concentrations were based on detected concentrations and one‐half reporting limits for non‐detected results. b. Comparisons to SCO and CSL were made using organic carbon‐normalized concentrations for non‐polar organic compounds. If TOC in the sample was >4% or <0.5%, dry weight concentrations were compared to the LAET and 2LAET. c. Total PCBs represents the sum of the detected concentration of the individual Aroclors. If none of the individual Aroclors were detected in a given sample, the non‐detect value represents the highest reporting limit. d. LDW Total PCB statistics and counts were generated with two outliers (2,900,000 and 230,000 µg/kg dw in Trotsky inlet) excluded. e. CPAH TEQ calculated using compound‐specific potency equivalency factors. f. A calculated dioxin and furan TEQ value was considered detected if one or more of the components of the sum were detected. If none of the components of the sum were detected, the calculated dioxin and furan TEQ value was considered non‐detected. g. Dioxin and furan TEQs were calculated using TEFs for mammals.

King County D‐17 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

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King County D‐18 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

APPENDIX E: BIBLIOGRAPHY

Study Area Characteristics and Uses

Blomberg, G., C. Simenstad, and P. Hickey. 1988. Changes in Duwamish River estuary habitat over 125 years. In: Proceedings of the First Annual Meeting on Puget Sound Reseach. Volume II. Puget Sound Water Quality Authority, Seattle, WA.

City of Seattle. 2009. Shoreline characterization report. City of Seattle, Department of Planning and Development, Seattle, WA.

Durgan, J.E., L. Airoldi, M.G. Chapman, S.J. Walker, and T. Schlacher. 2011. Estuarine and coastal structures: Environmental effects, a focus on shore and nearshore structures. Treatise on Estuarine and Coastal Science 8:17‐41.

Judd, N.L., W.C. Griffith, G.M. Ylitalo, and E.M. Faustman. 2002. Alternative strategies for PCB risk reduction from contaminated seafood: Options for children as susceptible populations. Bulletin of Environmental Contamination and Toxicology 69(6):847‐ 854.

Khangaonkar, T., Z. Yang, K. Taeyun, and M. Roberts. 2011. Tidally averaged circulation in Puget Sound sub‐basins: Comparison of historical data, analytical model, and numerical model. Estuarine, Coastal and Shelf Science 93(4):305‐319.

King County. 2001. Reconnaissance assessment of the state of the nearshore ecosystem: Eastern shore of Central Puget Sound including Vashon and Maury Islands. King County, Department of Natural Resources, Seattle, WA.

Kreitler J., M. Papenfus, K. Byrd, and W. Labiosa. 2013. Interacting coastal based ecosystem services: recreation and water quality in Puget Sound, WA. PLoS ONE 8(2): e56670. doi:10.1371/journal.pone.0056670.

MacDonald, K., D. Simpson, B. Paulsen, J. Cox, and J. Gendron. 1994. Shoreline armoring effects on physical coastal processes in Puget Sound, Washington: Coastal erosion management studies. Volume 5. DOE Report 94‐78. Washington State Department of Ecology, Shorelands Program, Olympia, WA.

Miller, B.S. and S.F. Borton. 1980. Geographical distribution of Puget Sound fishes: maps and data source sheets (3 volumes). Fisheries Research Institute, College of Fisheries, University of Washington, Seattle, WA.

Morley, S.A., J.D. Toft, and K.M. Hanson. 2012. Ecological effects of shoreline armoring on intertidal habitats of a Puget Sound urban estuary. Estuaries and Coasts 35:774‐784.

King County E‐1 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

NOAA. 2013. Coastal services center: Data. National Oceanic and Atmospheric Administration, Coastal Services Center, Charleston, SC. Accessed 7/1/2013. https://coast.noaa.gov/digitalcoast/data/home.html

Shipman, H., M.N. Dethier, G. Gelfenbaum, K.L. Fresh, and R.S. Dinicola (eds). 2010. Puget Sound shorelines and the impacts of armoring ‐ Proceedings of a state of the science workshop, May 2009. U.S. Geological Survey Scientific Investigations Report 2010– 5254, 262 p.

Water Quality

Ackerman, D., and S.B. Weisberg. 2003. Relationships between rainfall and beach bacterial concentrations on Santa Monica Bay beaches. Journal of Water and Health 1:85‐89.

Bates, S.T., P.P. Murphy, H.C. Curl, and R.A. Feely. 1987. Hydrocarbon distributions and transport in an urban estuary. Environmental Science and Technology, 21(2):193‐ 198.

Ecology. 1992. Marine water column ambient monitoring plan. Publication No. 92‐23. Washington Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA.

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Ecology. 1993. Marine water column ambient monitoring program: Annual report for wateryear 1991. Publication No. 93‐13. Washington Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA.

Ecology. 1994. Marine water column ambient monitoring program: Wateryear 1993 data report. Publication No. 94‐210. Washington State Department of Ecology, Ambient Monitoring Program, Olympia, WA.

Ecology. 1995. Marine water column ambient monitoring wateryear 1995 long‐term monitoring implementation plan. Publication No. 95‐324. Washington State Department of Ecology, Olympia, WA.

Ecology. 1997. Washington state marine quality in 1994 and 1995. Publication No. 97‐316. Washington State Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA.

Ecology. 1998. Washington State marine water quality in 1996 and 1997. Publication No. 98‐338. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

King County E‐2 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Ecology. 2002. Draft: beach environmental assessment communication and health ‐ BEACH program guidance. Publication No. 02‐03‐050. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

Ecology. 2002. Washington State marine water quality, 1998 through 2000. Publication No. 02‐03‐056. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

Ecology. 2007. Condition of coastal waters of Washington State, 2000‐2003: A statistical summary. Publication No. 07‐03‐051. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

Ecology. 2011. Puget Sound dissolved oxygen model: Nutrient load summary for 1999‐ 2008. Publication No. 11‐03‐057. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

EVS Environmental Consultants. 2003. Status, trends and effects of toxic contaminants in the Puget Sound environment. Prepared for the Puget Sound Action Team, Olympia, WA.

Gao, X., M. Alvo, and G. Li. 2008. Nonparametric multiple comparison procedures for unbalanced one‐way factorial designs. Journal of Statistical Planning and Inference 138:2574‐2591.

Gruber, N. 2008. The marine nitrogen cycle: overview and challenges. In: Capone, D.G., D.A. Bronk, M.R. Mulholland, and E.J. Carpenter (eds.) Nitrogen in the Marine Environment. Academic Press, Burlington, MA. 1757 pp.

Khangaonkar, T., B. Sackmann, W. Long, T. Mohamedali, and M. Roberts. 2012. Simulation of annual biogeochemical cycles of nutrient balance, phytoplankton bloom(s), and DO in Puget Sound using an unstructured grid model. Ocean Dynamics 62:1353‐ 1359.

Khangaonkar, T., B. Sackmann, W. Long, T. Mohamedali, and M. Roberts. 2012. Puget Sound dissolved oxygen modeling study: Development of an intermediate scale water quality model. Publication No. 12‐03‐049. Prepared by Washington State Department of Ecology for U.S. Department of Energy, Pacific Northwest National Laboratory, Richland, WA.

King County. 1994. Water quality status report for marine waters, 1993. King County Department of Natural Resources, Seattle, WA.

King County. 1998. Water quality status report for marine waters, 1996. King County Department of Natural Resources, Seattle, WA.

King County E‐3 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

King County. 1999. King County combined sewer overflow water quality assessment for the Duwamish River and Elliott Bay. King County, Department of Natural Resources, Wastewater Treatment Division, Seattle, WA.

King County. 1999. Marine water quality status report 1997. King County, Department of Natural Resources, Water and Land Division, Seattle, WA.

King County. 2000. Water quality status report for marine waters 1998. King County, Department of Natural Resources, Water and Land Division, Seattle, WA.

King County. 2001. Water quality status report for marine waters, 1999 and 2000. King County, Department of Natural Resource, Marine Monitoring and Assessment Group, Seattle, WA.

King County. 2002. Water quality status report for marine waters, 2001. King County, Department of Natural Resources and Parks, Marine and Sediment Assessment Group, Seattle, WA.

King County. 2003. Puget Sound water column endocrine disrupting compounds survey: Sampling and analysis plan. King County Department of Natural Resources and Parks, Wastewater Treatment Division, Seattle, WA.

King County. 2005. Water quality status report for marine waters, 2002 and 2003. King County, Department of Natural Resources and Parks, Marine and Sediment Assessment Group, Seattle, WA.

King County. 2005. Water column PCB congener survey ‐ sampling and analysis plan, Duwamish River/Elliott Bay/Green River. King County, Department of Natural Resources and Parks, Marine and Sediment Assessment Group, Seattle, WA.

King County. 2006. Technical memorandum: Duwamish River/Elliott Bay/Green River water column PCB congener survey transmittal of data quality assurance documentation. King County, Department of Natural Resources, Seattle, WA.

King County. 2006. Water quality status report for marine waters, 2004. King County, Department of Natural Resources and Parks Marine and Sediment Assessment Group, Seattle, WA.

King County. 2007. Survey of Endocrine Disrupting Compounds in King County Surface Waters. King County, Department of Natural Resources and Parks, Water and Land Resources Division. Seattle, WA.

King County. 2007. Water quality status report for marine waters, 2005‐2007. King County, Department of Natural Resources and Parks, Marine and Sediment Assessment Group, Seattle, WA.

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King County. 2010. Receiving water characterization study, King County NPDES monitoring program: Final sampling and analysis plan and quality assurance project plan. King County Department of Natural Resources and Parks, Marine and Sediment Assessment Group, Seattle, WA.

King County. 2013. Lower Duwamish Waterway source control: Bulk atmospheric deposition study final‐data report. King County Department of Natural Resources and Parks, Science and Technical Support Section, Seattle, WA.

King County. 2014. Groundwater Well Viewer. King County Water and Land Services, Groundwater Protection Program. http://green.kingcounty.gov/groundwater/map.aspx

Lessard, E.G. and J.McN., Siebuth. 1983. Survival of natural sewage populations of enteric bacteria in diffusion of batch chambers in the marine environment. Applied Environmental Microbiology 45:950‐959.

Lopaka, L. (2013). NADA: Nondetects and data analysis for environmental data. R package version 1.5‐6. https://cran.r‐project.org/package=NADA.

Mahler, B.J., P.C.V. Metre, J.L. Crane, A.W. Watts, M. Scoggins, and E.S Williams. 2012. Coal‐ tar‐based pavement sealcoat and PAHs: implications for the environment, human health, and stormwater management. Environmental Science and Technology 46: 3039‐3045.

METRO (Municipality of Metropolitan Seattle). 1989. Water quality status report for marine waters, 1988. Municipality of Metropolitan Seattle, Seattle, WA.

METRO (Municipality of Metropolitan Seattle). 1990. Water quality status report for marine waters, 1989. Municipality of Metropolitan Seattle, Seattle, WA.

NOAA. 1982. Suspended particulate matter in Elliott Bay. NOAA Technical Report ERL 417‐ PMEL 34. National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Boulder, CO.

NOAA. 1998. Contaminant transport from Elliott and Commencement Bays. NOAA Technical Memorandum: ERL PMEL‐78. National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Boulder, CO.

NOAA. 2013. Puget Sound marine waters: 2012 Overview. National Oceanic and Atmospheric Administration, Marine Waters Workgroup. Seattle, WA.

PSEP (Puget Sound Estuary Program). 1997. Recommended guidelines for sampling marine sediment, water column, and tissue in Puget Sound. U.S. Environmental Protection Agency, Region 10, Office of Puget Sound, Seattle, WA.

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PSEMP Marine Waters Workgroup. 2014. Puget Sound Marine Waters Overview. National Oceanic and Atmospheric Administration, Northwest Fisheries Science Center for the Puget Sound Ecosystem Monitoring Program, Seattle, WA.

Puget Sound Partnership. 2012. 2012 State of the sound ‐ A biannual report on the recovery of Puget Sound. Puget Sound Partnership, Tacoma, Washington.

Puget Sound Partnership. 2013. 2013 State of the sound – A biannual report on the recovery of Puget Sound. Puget Sound Partnership, Tacoma, Washington.

Reynolds, G.L. and J. Hamilton‐Taylor. 1992. The role of planktonic algae in the cycling of Zn and Cu in a productive soft‐water lake. Limnology and Oceanography 37:1759‐1769.

Ross, P.S. 2006. Fireproof killer whales (Orcinus orca): Flame‐retardant chemicals and the conservation imperative in the charismatic icon of British Columbia, Canada. Canadian Journal of Fisheries and Aquatic Science 63:224‐234.

Siegel, E., S.L. Albertson, and J.A. Newton. 2003. Oceanographic changes in Puget Sound and the Strait of Juan de Fuca during the 2000‐01 drought. Canadian Water Resources Journal 28(4):715‐728.

Sylvester, R.O., G.T. Orlob, A. Young, W. Montgomery, and L. Orlob. 1949. A survey of Puget Sound pollution: Seattle Metropolitan Area. Washington State Pollution Control Commission, Olympia, Washington.

Treguer, P.J. and C.L. De La Rocha. 2012. The world ocean silica cycle. Annual Review of Marine Science 5:477‐501.

Voss, M. 2011. Nitrogen processes in coastal and marine ecosystems. In: Sutton, M.A., C.M. Howard, J.W. Erisman, G. Billen, A. Bleeker, P. Grennfelt, H. van Grinsven, and B. Grizzetti (eds.). The European Nitrogen Assessment. Cambridge University Press, Cambridge, United Kingdome. 664 pp.

Washington State Blue Ribbon Panel on Ocean Acidification. 2012. Ocean acidification: from knowledge to action, Washington State’s strategic response. Pub. No. 12‐01‐ 015. Washington Department of Ecology, Olympia, Washington.

Sediment Quality/Benthos

Bates, T.S., P.P. Murphy, H.C. Curl, and R.A. Feely. 1987. Hydrocarbon distributions and transport in an urban estuary. Environmental Science and Technology 21:193‐198.

Chapman, P.M. and R. Fink. 1984. Effects of Puget Sound sediments and their elutriates on the life cycle of Capitella capitata. Bulletin of Environmental Contamination and Toxicology 33(1):451‐459.

King County E‐6 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Ecology. 1990. Puget Sound ambient monitoring program 1989: Marine sediment monitoring. Publication No. 90‐e76. Prepared by Tetra Tech, Inc, Bellevue, WA.

Ecology. 1992. Puget Sound ambient monitoring program marine sediment monitoring program: Annual report 1990. Publication No. 92‐47. Washington State Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA.

Ecology. 1992. Technical information memorandum, organic carbon normalization of sediment data. Washington State Department of Ecology, Sediment Management Unit, Olympia, WA.

Ecology. 1993. Puget Sound ambient monitoring program 1992: Marine sediment monitoring task. Publication No. 93‐87. Washington State Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA.

Ecology. 1994. Marine sediment monitoring program progress report. Publication No. 94‐ e28. Washington State Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA.

Ecology. 1994. Puget Sound ambient monitoring program marine sediment monitoring program annual report 1991. Publication No. 94‐93. Washington State Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA.

Ecology. 1994. Elliott Bay action program: Environmental clean‐up activities in Elliott Bay and the Duwamish Waterway. Publication No. 95‐603. Washington State Department of Ecology, Elliott Bay Action Team, Olympia, WA.

Ecology. 1995. Elliott Bay waterfront recontamination study. Volume 1: Field investigation report. Publication No. 95‐335. Washington State Department of Ecology, Elliott Bay/Duwamish Restoration Panel, Seattle, WA.

Ecology. 1995. Elliott Bay waterfront recontamination study. Volume 2: Data evaluation and remedial design recommendations report. Publication No. 95‐607. Prepared by Aura Nova Consultants, Inc., Olympia, WA.

Ecology. 1998. Marine sediment monitoring program. I. Chemistry and toxicity testing 1989‐1995. Publication No. 98‐323. Washington State Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA.

Ecology. 1998. Marine sediment monitoring program. II. Distribution and structure of benthic communities in Puget Sound 1989‐1993. Publication No. 98‐328. Washington State Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA.

King County E‐7 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Ecology. 2000. Sediment quality in Puget Sound. Year 2 – Central Puget Sound. Publication No. 00‐03‐055. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

Ecology. 2003. Washington State mercury chemical action plan. Publication No. 03‐03‐001. Washington State Department of Ecology and Department of Health, Olympia, WA.

Ecology. 2003. Chemical contamination, acute toxicity in laboratory tests, and benthic impacts in sediments of Puget Sound: A summary of results of the joint 1997‐1999 Ecology/NOAA Survey. Publication No. 03‐03‐049. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

Ecology. 2008. Dioxins, furans, and other contaminants in surface sediment and English Sole collected from Greater Elliott Bay (Seattle). Publication No.08‐03‐017. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

Ecology. 2009. Urban waters initiative, 2007: Sediment quality in Elliott Bay. Publication No. 09‐03‐014. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

Ecology and King County. 2011. Control of toxic chemicals in Puget Sound: assessment of selected toxic chemicals in the Puget Sound Basin, 2007‐2011. Publication No. 11‐ 03‐012. Washington State Department of Ecology, Olympia, WA and King County , Department of Natural Resources and Parks, Seattle, WA.

Ecology. 2012. Draft sediment cleanup user’s manual II. Publication No. 12‐09‐057. Washington State Department of Ecology, Toxics Cleanup Program, Olympia, WA.

Ecology. 2013. Sediment Management Standards. Chapter 173‐204 WAC. Pub. No. 13‐09‐ 055. Washington State Department of Ecology, Toxics Cleanup Program, Olympia, WA.

Ecology. 2013. Sediment quality in Central Puget Sound, changes over a ten‐year period. Publication No. 13‐03‐021. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

Ecology. 2013. Development of Puget Sound benthic indicators. Publication No. 13‐03‐035. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

EPA. 1988. Sediment quality values refinement, 1988 update and evaluation of Puget Sound AETs. Volume I. U.S. Environmental Protection Agency, Region 10, Seattle, WA.

King County E‐8 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

EPA. 1992. Sediment classification methods compendium. EPA 823‐R‐92‐006. U.S. Environmental Protection Agency, Office of Science and Technology, Washington, D.C.

EPA. 2009. Second five‐year review report for the Pacific Sound Resources superfund site, City of Seattle, King County, WA. U.S. Environmental Protection Agency, Region 10, Seattle, WA.

EPA. 2010. Third five‐year review report: Harbor Island superfund site, Seattle, WA. U.S. Environmental Protection Agency, Region 10, Seattle, WA.

EPA. 2013. Record of Decision: Lockheed West Seattle superfund site, Seattle, WA. U.S. Environmental Protection Agency, Region 10, Seattle, WA.

Essington, T., T. Klinger, T. Conway‐Cranos, J. Buchanan, A. James, J. Kershner, I. Logan, and J. West. 2011. Puget Sound science review. The biophysical condition of Puget Sound: Chemistry. Puget Sound Institute, University of Washington Tacoma Center for Urban Waters, Tacoma, WA.

EVS Environmental Consultants. 1998. Port of Seattle Terminal 18 sediment characterization sampling and analysis results. Prepared for the Port of Seattle, Seattle, WA.

GeoSea Consulting (Canada) Ltd. 1994. Sediment transport in Elliott Bay and the Duwamish River, Seattle: Implications to estuarine management. Prepared for Washington Department of Ecology; Toxics Cleanup Program, Olympia, WA.

King County. 1998. CSO sampling and monitoring data inventory. Task 5 report: Sediment management plan. King County Department of Natural Resources, Sediment Management Plan Project Team, Seattle, WA.

King County. 1998. King County’s sediment management plan. Final Task Report: Identification of nearby contaminated sites. King County Department of Natural Resources, Facility Planning Section, Seattle, WA.

King County. 1999. Preliminary final: Year 2000 CSO plan update project, sediment management plan literature and project review. King County Department of Natural Resources, Sediment Management Program, Seattle, WA.

King County. 1999. Year 2000 plan update project, sediment management plan. Task 1400 Technical memorandum. King County Department of Natural Resources, Seattle, WA.

King County. 2009. Comprehensive sediment quality summary report for CSO discharge locations. King County Department of Natural Resources and Parks, Wastewater Treatment Division, Seattle, WA.

King County E‐9 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

King County. 2010. Intertidal sediment monitoring 2010 sampling event. Sampling and analysis plan. King County, Department of Natural Resources and Parks, Marine and Sediment Assessment Group, Seattle, WA.

King County. 2011. 2011 Subtidal sediment sampling event: Final sampling and analysis plan. King County, Department of Natural Resources and Parks, Marine and Sediment Assessment Group, Seattle, WA.

King County. 2011. CSO Sediment quality characterization final sampling and analysis plan. King County, Department of Natural Resources and Parks, Wastewater Treatment Division, Seattle, WA.

Lower Duwamish Waterway Group. 2010. Remedial investigation report. Prepared by WindWard Environmental LLC, Seattle, WA.

McCain, B.B., D.W. Brown, M.M. Krahn, M.S. Myers, R.C. Clark, S.‐L. Chan, and D.C. Malins. 1988. Marine pollution problems. North American West Coast. Aquatic Toxicology 11(1988):143‐162.

Mearns, A.J. 2001. Long‐term Contaminant Trends and Patterns in Puget Sound, the Straits of Juan de Fuca, and the Pacific Coast. Proceedings of Puget Sound Research 2001.

METRO (Municipality of Metropolitan Seattle). 1984. Toxicant pretreatment planning study: Presence, distribution and fate of toxicants in Puget Sound and Lake Washington. TPPS Technical Report C1. Municipality of Metropolitan Seattle, Seattle, WA.

METRO (Municipality of Metropolitan Seattle). 1987. Duwamish Head baseline study. Municipality of Metropolitan Seattle, Seattle, WA.

NOAA. 1981. A Summary of knowledge of Puget Sound related to chemical contaminants. NOAA Technical Memorandum OMPA‐13. National Oceanic and Atmospheric Administration, Office of Marine Pollution Assessment, Boulder, CO.

NOAA. 1982. Survey of biological effects of toxicants upon Puget Sound biota. I. Broad‐scale toxicity survey. NOAA Technical Memorandum OMPA‐25. National Oceanic and Atmospheric Administration, Office of Marine Pollution Assessment, Boulder, CO.

NOAA. 1983. Survey of biological effects of toxicants upon Puget Sound biota. II. Tests of reproductive impairment. NOAA Technical Report NOS 102 OMS 1. National Oceanic and Atmospheric Administration, Rockville, MD.

NOAA. 1984. Survey of biological effects of toxicants upon Puget Sound biota. IV. Interrelationships of infauna, sediment bioassay and sediment chemistry data.

King County E‐10 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

NOAA Technical Memorandum NOS OMA 9. National Oceanic and Atmospheric Administration, Office of Oceanography and Marine Assessment, Rockville, MD.

NOAA. 1997. Historical trends in the accumulation of chemicals in Puget Sound. NOAA Technical Memorandum NOS ORCA 111. National Oceanic and Atmospheric Administration, Coastal Monitoring and Bioeffects Assessment Division, Silver Spring, MD.

NOAA. 2000. National benthic surveillance project: Pacific Coast. Organic chemical contaminants, cycle I to VII (1984‐90). NOAA Technical Memorandum NMFSNWFSC‐40. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Seattle, WA.

Pastorok, R.A. and D.S. Becker. 1990. Comparative sensitivity of sediment toxicity bioassays at three superfund sites in Puget Sound. In: Landis, W.G. and W.H. Van der Schalie (eds). Aquatic Toxicology and Risk Assessment, Thirteenth Volume, SPT 1096. American Society for Testing and Materials, Philadelphia, PA. pp 123‐129.

Port of Seattle. 2014. East Waterway operable unit supplemental remediation investigation/feasibility study – final supplemental remedial investigation report. Produced for the US Environmental Protection Agency, Region 10, Seattle, WA.

Port of Seattle. 2014. 2013 Port of Seattle foreign waterborne trade report. Port of Seattle, Seattle, WA.

PSEP (Puget Sound Estuary Program). 1997. Recommended guidelines for sampling marine sediment, water column, and tissue in Puget Sound. U.S. Environmental Protection Agency, Region 10, Office of Puget Sound, Seattle, WA.

Puget Sound Partnership. 2011. Setting targets for dashboard indicators. Indicator: Toxics in sediments. Puget Sound Partnership, Olympia, WA.

SCCWRP (Southern California Coastal Water Research Project). 2013. Development of Puget Sound benthic indicators. Technical Report # 755. Washington State Department of Ecology, Environmental Assessment Program, Olympia, WA.

Striplin, P.L. 1988. Puget Sound ambient monitoring program marine sediment quality implementation plan. Publication No. 88‐e37. Washington State Department of Ecology, Water Quality Programs Section, Olympia, WA.

Tetra Tech, Inc. 1986. Elliott Bay toxics action program: Initial data summaries and problem identification. Prepared for U.S. Environmental Protection Agency, Region 10 Office of Puget Sound, Seattle, WA.

King County E‐11 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

True, C.J. and A.A. Heyward. 2006. Relationships between microtox test results, extraction methods, and physical and chemical compositions of marine sediment samples. Environmental Toxicology 5(1): 29‐45.

USGS. 2014. Data compilation for assessing sediment and toxic chemical loads from the Green River to the lower Duwamish Waterway, Washington. U.S. Geological Survey Data Series 880, 46 p.

Habitat and Wildlife

Baldwin, D.H., J.A. Spromberg, T.K. Collier, and N.L. Scholz. 2009. A fish of many scales: Extrapolating sublethal pesticide exposures to the productivity of wild salmon populations. Ecological Applications 19(8):2004‐2015.

Bash, J., C. Berman, and S. Bolton. 2001. Effects of turbidity and suspended solids on salmonids. University of Washington, Washington State Transportation Center, Seattle, WA.

Berg, L. and T.G. Northcote. 1985. Changes in territorial, gill‐flaring, and feeding behavior in Juvenile Coho Salmon (Oncorhynchus kisutch) following short‐term pulses of suspended sediment. Canadian Journal of Fisheries and Aquatic Sciences 42:1410‐ 1417.

Bisson, P.A. and R.E. Bilby. 1982. Avoidance of suspended sediment by juvenile coho salmon. North American Journal of Fisheries Management 2(4):371‐374.

Casillas, E., M.S. Myers, L.D. Rhodes, and B.B. McCain. 2006. Serum chemistry of diseased English Sole, Parophrys vetulus Girard, from polluted areas in Puget Sound, Washington. Journal of Fish Disease 8(5):437‐449.

City of Seattle. 2004. Marine shoreline inventory report: WRIA 9. City of Seattle, Seattle Public Utilities, Seattle, WA.

City of Seattle. 2012. Seattle biological evaluation (revised). City of Seattle, Seattle Public Utilities, Seattle, WA.

Collins, B.D. and A.J. Sheikh. 2005. Historical reconstruction, classification, and change analysis of Puget sound tidal marshes. Prepared for Washington Department of Natural Resources, Aquatic Resources Division, Olympia, WA.

Duncan, P.B., K.A. Rose, Salazar, M.H., and S.M. Salazar. 1995. In‐situ bioassays using transplanted mussels: II. Assessing contaminated sediment at a superfund site in Puget Sound. In: Hughes, J.S., G.R. Biddinger, and E. Mones (eds). Environmental Toxicology and Risk Assessment, Third Volume, STP1218. American Society for Testing and Materials, Philadelphia, PA. pp. 242‐263.

King County E‐12 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Ecology. 2002. Seasonal patterns and controlling factors of primary production in Puget Sound’s Central Basin and Possession Sound. Publication No. 02‐03‐059.Washington Department of Ecology, Environmental Assessment Program, Olympia, WA.

EPA. 2004. Appendix A: Suspended sediment effects on fish: A literature review. In: Milltown Reservoir Biological Opinion. U.S. Environmental Protection Agency, Montana Ecological Services Field Office, Helena, MT, pp. A1‐A13.

Evans‐Hamilton Inc. 1987. Puget Sound environmental atlas. Volume 1. Prepared for U.S. Environmental Protection Agency by Evans‐Hamilton, Inc., Seattle, WA.

Evans‐Hamilton, Inc. 1987. Puget Sound environmental atlas. Volume 2. Prepared for U.S. Environmental Protection Agency by Evans‐Hamilton, Inc., Seattle, WA.

FAO. 1999. The effects of sediment on fish and their habitats. Fisheries and Oceans Canada, Science Branch, Vancouver, B.C.

Fisher, W and D. Velasquez, 2008. Management recommendations for Washington’s priority habitats and species: Dungeness crab, Cancer magister. Washington Department of Fish and Wildlife, Olympia, WA.

Friedenberg, L., J. Bos, S. Albertson, M. Keyzers, C. Maloy, B. Sackman, and C. Krembs. 2013. Increasing nutrients, changes in algal biomass, and large Noctiluca blooms in Puget Sound: Is eutrophication fueling the microbial food web? (Poster). Publication No. 13‐03‐019. Washington State Department of Ecology, Olympia, WA.

Fuerstenburg, R. R., K. Nelson, and R. Blomquist. 1996. Ecological conditions and limitations to salmonid diversity in the Green River, Washington, USA. King County, Surface Water Management, Bellevue, WA.

Gaeckle, J., P. Dowty, H. Berry, L. Ferrier, A. Schanz, T. Mumford, and S. Wyllie‐Echeverria. 2009. Eelgrass (Zostera marina L.) monitoring in greater Puget Sound: the value in tracking an indicator species. In: Proceedings of the 2009 Puget Sound Georgia Basin Ecology Conference, February 2009, Seattle, WA. 21 pp.

Henny, C.J., J.L. Kaiser, R.A. Grove, B.L. Johnson, and R.J. Letcher. 2009. Polybrominated diphenyl ether flame retardants in eggs may reduce reproductive success of ospreys in Oregon and Washington, USA. Ecotoxicology 18(7): 802‐813.

Holsman, K.K. and J. Willig, 2007. Large‐scale patterns in large woody debris and upland vegetation among armored and unarmored shorelines of Puget Sound, WA. Prepared for People for Puget Sound, Seattle, WA.

Johnson, L.L. and J.T. Landahl. 1994. Chemical contaminants, liver disease, and mortality rates in English Sole (Pleuronectes vetulus). Ecological Applications 4(1):59‐68.

King County E‐13 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Johnson, L.L., D.P. Lomax, M.S. Myers, O.P. Olson, S.Y. Sol, S.M. O’Neill, J. West, and T.K. Collier. 2008. Xenoestrogen exposure and effects in English Sole (Paraphrys vetulus) from Puget Sound, WA. Aquatic Toxicology 88:29‐38.

Kagley, A.N., R.G. Snider, P.K. Krishnakumar, and E. Casillas, 2003. Assessment of seasonal variability of cytochemical responses to contaminant exposure in the blue mussel Mytilus edulis (Complex). Archives of Environmental Contamination and Toxicology 44(1):43‐52.

Kimbrough, K.L., W.E. Johnson, G.G. Lauenstein, J.D. Christensen, and D.A. Apeti. 2009. An assessment of polybrominated diphenyl ethers (PBDEs) in sediments and bivalves of the U.S. coastal zone. NOAA Technical Memorandum NOS NCCOS 94. NOAA. National Oceanic and Atmospheric Administration, Center for Coastal Monitoring and Assessment, Silver Springs, MD.

King County. 2001. Reconnaissance assessment of the state of the nearshore ecosystem: Eastern shore of Central Puget Sound, including Vashon and Maury Islands. King County, Department of Natural Resources and Parks, Seattle, WA.

King County. 2004. Juvenile Chinook migration, growth and habitat use in the Lower Green River, Duwamish River and nearshore of Elliott Bay 2001‐2003, draft report. King County Department of Natural Resources and Parks, Water and Land Resources Division, Seattle, WA.

King County. 2004. Juvenile salmon composition, timing, distribution, and diet in marine nearshore waters of Central Puget Sound in 2001‐2002. King County Department of Natural Resources and Parks, Water and Land Resources Division, Seattle, WA.

Laurenstein, G.G. and A.Y. Cantillo, Eds. 1993. Sampling and analytical methods of the National Status and Trends Program National Benthic Surveillance and Mussel Watch Projects 1984‐1992. National Oceanic and Atmospheric Administration, Silver Spring, MD.

Lin, H.‐P., G. Charmantier, P. Thuet, and J.‐P. Trilles. 1992. Effects of turbidity on survival, osmoregulation and gill Na+ ‐K+ ATPase in juvenile shrimp Penaeus japonicus. Marine Ecology Progress Series 90:31‐37.

Malins, D.C. 1989. Sediment contamination and marine ecosystems: Potential risks to human health. In: Committee on contaminated marine sediments. Contaminated Marine Sediments: Assessment and Remediation. National Academy Press, Washington, D.C. pp. 155‐164.

Malins, D.C., B.B. McCain, M.S. Myers, D.W. Brown, M.M. Krahn, W.T. Roubal, M.H. Schiewe, J.T. Landahl, and S.‐L. Chan. 1987. Field and laboratory studies of the etiology of liver neoplasms in marine fish from Puget Sound. Environmental Health Perspectives 71:5‐16.

King County E‐14 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Mantua, N.J., S.R. Hare, Y. Zhang, J.M. Wallace, and R.C. Francis. 1997. A Pacific interdecadal climate oscillation with impacts on salmon production. Bulletin of the American Meteorological Society 78:1069‐1079.

Martin, M., M.D. Stephenson, D.R. Smith, E.A. Gutierrez‐Galindo, and G. Flores Munoz. 1988. Use of silver in mussels as a tracer of domestic wastewater discharge. Marine Pollution Bulletin 19(10):512‐520.

Myers, M.S., C.M. Stehr, O.P. Olson, L.L. Johnson, B.B. McCain, S.‐L. Chan, and U. Varanasi. 1994. Relationship between toxicopathic hepatic lesions and exposure to chemical contaminants in English sole (Pleuronectes vetulus), starry flounder (Platichthys stellatus), and white croaker (Genyonemus lineatus) from Selected Marine Sites on the Pacific Coast, USA. Environmental Health Perspectives 102(2):200‐215.

Natural Resources Consultants, Inc. 2004. Final WRIA 9 Chinook salmon research framework: Identifying key research questions about Chinook salmon life histories and habitat use in the Middle and Lower Green River, Duwamish Waterway, and marine nearshore areas. Prepared for WRIA 9 Steering Committee, Seattle, WA.

Natural Resources Consultants, Inc. 2004. Residence time and growth of natural and hatchery Chinook salmon in the Duwamish estuary and Elliott Bay, Washington, based on otolith chemical and structural attributes. Prepared for U.S. Army Corps of Engineers, Seattle District, Seattle, WA.

NOAA. 1982. Chemical contaminants and abnormalities in fish and invertebrates from Puget Sound. NOAA Technical Memorandum OMPA‐19. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Seattle, WA.

NOAA. 1983. Organic and inorganic toxicants in sediment and marine birds from Puget Sound. NOAA Technical Memorandum NOS OMS 1. National Oceanic and Atmospheric Administration, Ocean Assessment Division, Rockville, MD.

NOAA. 1987. Potential toxicant exposure among Consumers of Recreationally Caught Fish from Urban embayments of Puget Sound: Final report. NOAA Technical Memorandum NOS OMA 33. National Oceanic and Atmospheric Administration, Rockville, MD.

O'Neill, S.M., J.E. West, and S. Quinnell. 1995. Contaminant monitoring in fish: Overview of the Puget Sound ambient monitoring program fish task. In: E. Robichaud, editor, Puget Sound Research 1995 Proceedings. Puget Sound Water Quality Authority, Olympia, WA. pp 35‐50.

O’Neill, S.M. and J.E. West. 2001. Exposure of Pacific herring (Clupea pallasii) to persistent organic pollutants in Puget Sound and the Georgia Basin. In: Droscher, T. (ed). Proceedings of the 2001 Puget Sound Research Conference.

King County E‐15 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Peck, K.A., D.P. Lomax, O.P. Olson, S.Y. Sol, P. Swanson, and L.L. Johnson. 2010. Development of an enzyme‐linked immunosorbent assay for quantifying vitellogenin in Pacific salmon and assessment of field exposure to environmental estrogens. Environmental Toxicology and Chemistry 30(2):477‐486.

PSEP (Puget Sound Estuary Program). 1997. Recommended guidelines for sampling marine sediment, water column, and tissue in Puget Sound. U.S. Environmental Protection Agency, Region 10, Office of Puget Sound, Seattle, WA.

Puget Sound Water Quality Authority. 1992. The 1992 Puget Sound environmental atlas update. Prepared for the Puget Sound Estuary Program, by the Puget Sound Water Quality Authority, Olympia, WA.

Ross, P.S. 2006. Fireproof killer whales (Orcinus orca): Flame‐retardant chemicals and the conservation imperative in the charismatic icon of British Columbia, Canada. Canadian Journal of Fisheries and Aquatic Science 63:224‐234.

Ross, P.S., S.J. Jeffries, M.B. Yunker, R.F. Addison, M.G. Ikonomou, and J.C. Calambokidis. 2004. Harbor seals (Phoca vitulina) in British Columbia, Canada, and Washington State, USA, reveal a combination of local and global polychlorinated biphenyl, dioxin, and furan signals. Environmental Toxicology and Chemistry 23(1):157‐165.

Servizi, J.A. and D.W. Martens. 1991. Effect of temperature, season, and fish size on acute lethality of suspended sediments to Coho Salmon (Oncorhynchus kisutch). Canadian Journal of Fisheries and Aquatic Sciences 48:493‐497.

Shaw, E.A. and J.S. Richardson. 2001. Direct and indirect effects of sediment pulse duration on stream invertebrate assemblages and rainbow trout (Oncorhynchus mykiss) growth and survival. Canadian Journal of Fisheries and Aquatic Sciences 58:2213‐ 2221.

Stern, J.H. and B. Nairn. 2010. Temporal effects of cleanup remedy‐related releases on fish tissue concentrations – implications to achieving net risk reduction goals using different cleanup approaches. (Poster) Proceedings of the 2011 Salish Sea Ecosystem Conference, Vancouver, B.C.

Thom, R.M. and L. Hallumm. 1990. Long‐term changes in the areal extent of tidal marshes, eelgrass meadows and kelp forests of Puget Sound. Prepared for U.S. Environmental Protection Agency, Office of Puget Sound Region 10, Seattle, WA.

Toft, J.D., A.S. Ogston, S.M. Heerhartz, J.R. Cordell, and E.E. Flemer. 2013. Ecological response and physical stability of habitat enhancements along an urban armored shoreline. Ecological Engineering 57: 97‐108.

King County E‐16 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

USFW. 2010. Biological effects of sediment on bull trout and their habitat – guidance for evaluating Effects. U.S. Fish and Wildlife Service, Washington Fish and Wildlife Office, Lacey, WA.

WDFW. 2001. Exposure of Pacific herring (Clupea pallasii) to persistent organic pollutants in Puget Sound and the Georgia Basin. Puget Sound Research 2001 Conference Proceedings. Puget Sound Water Quality Action Team. Olympia, WA.

WDFW. 2001. Toxics contaminants in marine and anadromous fish from Puget Sound, Washington: Results from the Puget Sound Ambient Monitoring Program Fish Component, 1989‐1999. Washington Department of Fish and Wildlife, Olympia, WA.

WDFW. 2004. Concentrations of polybrominated diphenyl ethers (PBDEs) in fish from Puget Sound, WA, USA. Poster presentation: SETAC World Congress and 25th Annual Meeting in North America Society of Environmental Toxicology and Chemistry. Portland, OR.

WDFW. 2007. Thirty years of persistent bioaccumulative toxics in Puget Sound: Time trends of PCBs and PBDE flame retardants in three fish species. Washington Department of Fish and Wildlife, Olympia, WA.

WDFW. 2011. Control of toxic chemicals in Puget Sound phase 3: Persistent bioaccumulation and toxic contaminants in pelagic marine fish species from Puget Sound. Publication No. 11‐10‐003. Prepared for Washington State Department of Ecology, Olympia, WA.

WDFW. 2011. Current conditions, time trends and recovery targets for toxic contaminants in Puget Sound fish: the toxics in fish dashboard indicator. Washington Department of Fish and Wildlife, Olympia, WA. WDFW. 2014. Toxic contaminants in Puget Sound’s nearshore biota: a large‐scale synoptic survey using transplanted mussels (Mytilus trossulus). Washington Department of Fish and Wildlife, Olympia, WA.

WDFW. 2014. Toxic contaminants in Dungeness crab (Metacarcarinus magister) and spot prawn (Pandalus platyceros) from Puget Sound, Washington, USA. Washington Department of Fish and Wildlife, Olympia, WA.

WDOH. 2006. Human health evaluation of contaminants in Puget Sound fish. Publication No. 334‐104. Washington State Department of Health, Division of Environmental Health, Olympia, WA.

WDOH. 2009. Letter health consultation: greater Elliott Bay sediment and English Sole, Seattle, King County, Washington. Publication No. 334‐213. Washington State Department of Health, Division of Environmental Health, Olympia, WA.

King County E‐17 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

WDOH. 2009. Greater Elliott Bay sediment and English sole, Seattle, King County, Washington. Washington State Department of Health, Olympia, WA.

WDOH. 2013. Washington State Fish Consumption Advisories. Washington State Department of Health, Fish Advisories Program, Olympia, WA. Accessed 7/1/2013.

West, J., S. O’Neill, D. Lomax, and L. Johnson. 2001. Implications for reproductive health in rockfish (Sebastes spp.) from Puget Sound exposed to polychlorinated biphenyls. In: Droscher, T. (ed). Proceedings of the 2001 Puget Sound Research Conference.

West, J.E. and S.M. O’Neill. 1998. Persistent pollutants and factors affecting their accumulation in rockfish (Sebastes spp.) from Puget Sound, Washington. Puget Sound Water Quality Action Team, Olympia, WA.

WRIA 9 Implementation Technical Committee. 2012. WRIA 9 status and trends monitoring report: 2005‐2010. Prepared for the WRIA 9 Watershed Ecosystem Forum, Seattle, WA.

Sources of Water Quality Concern and Corrective Actions

APHA‐AWWA‐WEF and Eaton, A. D. 2005. Standard methods for the examination of water and wastewater (21st ed). American Public Health Association, Water Environment Federation American, and Water Works Association, Washington, D. C.

City of Seattle. 2000. Seattle public utilities CSO characterization project. City of Seattle, Seattle Public Utilities, Seattle, WA.

City of Seattle. 2005. Discipline report: Water quality. Draft EIS: Magnolia Bridge replacement. City of Seattle, Department of Transportation, Seattle, WA.

City of Seattle. 2009. Green stormwater operations and maintenance manual. City of Seattle, Seattle Public Utilities, Seattle, WA.

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King County E‐21 October 2017 Water Quality Assessment and Monitoring Study: Analysis of Existing Data on the Duwamish Estuary

Pavlou, S.P., W. Horn, R.N. Dexter, D.E. Anderson, and E.A. Quinlan. 1982. Release, distribution, and impacts of polychlorinated biphenyls (PCB) induced by dredged material disposal activities at a deep‐water estuarine site. Environmental International 7(2):99‐117.

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