LAKE UNION/SHIP CANAL/SHILSHOLE BAY
WATER QUALITY MANAGEMENT PROGRAM
DATA SUMMARY REPORT ADDENDUM
City of Seattle
Office for Long-range Planning
Room 200, Municipal Building
Seattle, Washington 98104
May, 1987
This project has been funded wholly or in part by the United States
Environmental Protection Agency under assistance agreement #0X813649-01-0 to the
City of Seattle. The contents of this document do not necessarily reflect the
views and policies of the EPA.
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TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY
I. INTRODUCTION 5
II. ONGOING WATER QUALITY MONITORING 5
Saltwater Intrusion
Dissolved Oxygen
Fecal Coliforms
III. OFFSHORE GAS WORKS PARK SEDIMENT QUALITY 9
Sediment Chemistry
Sediment Toxicity
Benthic Infauna
IV. SOUTH LAKE UNION PILOT PROJECT ADDENDUM 13
Interpretation of Sediment Chemical Oxygen Demand Values
Crayfish Tissue Analyses
Benthic Infauna Survey
V. RELATED PROJECTS 26
Lake Union and Ship Canal Storm Drain Sediment and
Analysis Program (Seattle Engineering Department)
Lake Union and Ship Canal Outfall Survey (Environmental
Intern Program and Seattle Engineering Department)
Combined Sewer Overflow (CSO) Abatement
Planning (Seattle Engineering Department)
University Regulator CSO Control Project (Metro)
Gas Works Park Groundwater Analysis Program
(Seattle Parks Department and U.S. Geological Survey)
Literature Cited 51
Glossary 53
Acknowledgements 56
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LIST OF FIGURES
Figure Page
1. Additional Sampling Sites in Lake Union 6
2. Storm Drain Sediment and Stormwater Sampling 27
Sites in Lake Union
3. Storm Drain Sediment and Stormwater Sampling Sites 28
in the Ship Canal
4. Lake Union and Ship Canal Drainage Basins 29
5. Location of Outfalls Observed in Lake Union 39
6. Location of Outfalls Observed in the Ship Canal 40
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LIST OF TABLES
Table Page
1. Dissolved Oxygen, Conductivity, Turbidity and Fecal 7
Coliforms in Lake Union
2. Organics Levels in Lake Union (Offshore Gas Works Park) 10
and Chester Morse Lake Sediments
3. Metal Levels in Lake Union (Offshore Gas Works Park) 11
and Chester Morse Lake Sediments
4. Bioassay Results of Amphipod (Hyalella azteca) Sediment 12
in Lake Union (Offshore Gas Works Park) and Chester Morse
Lake Sediments
5. Benthic Infauna in Lake Union (Offshore Gas Works Park) 14
and Chester Morse Lake Sediments
6. Metal and PCB levels in Crayfish Tail Tissue 15
7. Lake Union Sediment Conditions 19
8. Grain Size Analysis of Lake Union Sediment Samples 21
9. Lake Union Benthic Infauna Sampling Results 23
10. Metal and Organics Levels in South Lake Union Sediment Samples 24
11. Conventional Sediment Quality Parameters and Metal Levels 31
Lake Union and Ship Canal Storm Drain Sediments
12. Conventional Water Quality Parameters and Metal Levels in 35
Stormwater Discharged to Lake Union and the Ship Canal
13. Estimated Total Loadings from Stormwater Discharge (All 36
Outfalls) to Lake Union and the Ship Canal
14. Estimated Annual Loadings from Monitored Basin Outfalls 37
to Lake Union and the Ship Canal
15. Ranking of Storm Drain Basins by Percent of Total 41
Annual Runoff and by Pollutant Loading
16. Water Quality Parameters and Metal Levels in Portage Bay, 44
North Lake Union and the Ship Canal
17. Conventional Sediment Quality Parameters and Sediment 45
Toxicant Levels in Portage Bay, North Lake Union and the
Ship Canal
18. Benthic Infauna Data in Portage Bay, North Lake Union and 50
the Ship Canal
i ii
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EXECUTIVE SUMMARY
Introduction
This report summarizes new information (obtained since spring 1986) on water
quality, sediment quality, crayfish contamination and benthic (bottom-dwelling)
infauna in selected areas of Lake Union. Water quality parameters were compared
with existing water quality standards and criteria. In the absence of
freshwater sediment quality criteria, toxicant levels in Lake Union sediments
were compared with interim sediment quality values proposed for Puget Sound
sediments. Updates are also presented for five projects that are related to the
overall Lake Union and Ship Canal Water Quality Management Program: (1) Seattle
Engineering Department's Storm Drain Sediment Sampling and Analysis Study,
(2) the related outfall survey conducted by the Environmental Intern Program,
(3) Seattle Engineering Department's Combined Sewer Overflow Abatement Planning,
(4) Metro's University Regulator CSO Control Project, and (5) Seattle Parks
Department and U.S. Geological Survey's Gas Works Park Groundwater Analysis
Program.
Water Quality
Metro's semimonthly monitoring of the Lake Union water column during July-
December 1986 showed high conductivity in the Lake bottom during the summer and
early fall, which reflects saltwater intrusion from the Locks. Dissolved oxygen
levels were correspondingly low in the Lake bottom at that time, i.e., below the
5 mg/liter water quality criterion for protection of aquatic life. Fecal
coliform counts exceeded the state water quality standard (> 50 organisms/ml
water) during rainy periods in September-December.
Offshore Gas Works Park Sediment Quality
The triad approach (sediment chemistry analysis, sediment toxicity analysis and
benthic infauna surveys) was applied to compare sediments from an offshore Gas
Works Park (GWP) site in Lake Union and a reference site in pristine Chester
Morse Lake (CML) (Yake et al., 1986). Offshore GWP sediment was contaminated
with high levels of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated
biphenyls (PCBs); no PAHs or PCBs were detected in CML sediment. Six metals
(cadmium, chromium, lead, mercury, nickel and zinc) were found at higher
concentrations in GWP than in CML sediments. GWP sediment was significantly
more toxic to the freshwater amphipod Hyalella azteca than CML sediment, i.e.,
95% Hyalella mortality compared to 8% mortality. The abundance and diversity of
benthic infauna in GWP sediment were significantly lower than in CML sediment.
South Lake Union Pilot Project Addendum
As part of the South Lake Union Pilot Project, sediments were collected from
fifteen sites in south Lake Union in spring 1986 and were analyzed for several
sediment quality parameters including chemical oxygen demand (COD). Five of
these sampling sites had sediment COD levels that were near or above 50 ppt,
a concentration that has been associated with dissolved oxygen depletion and
paucity of benthic infauna in Great Lakes sediments. It is likely that DO
levels were low in these South Lake Union sediments, creating inhospitable
conditions for benthic infauna.
Metal and PCB levels were measured in raw and cooked tail tissue of crayfish
harvested from south Lake Union. The metal levels were within the range
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expected for crustaceans from urban waters and were not of concern to the
Seattle-King County Health Department. The reported PCB levels were below the
Food and Drug Administration tolerance standard of 2 ppm. However, this may be
too liberal since it does not reflect the risk associated with consuming fish on
a regular basis. The Seattle-King County Health Department has recommended
further PCB analyses with replicate samples at each location and establishment
of comparability between uncooked and cooked tissue.
In November 1986, the EPA Dive Team conducted a visual inventory of the bottom
of Lake Union and collected sediment samples for benthic infauna and sediment
grain size analyses from fifteen sites in south Lake Union and three additional
sites on an east-west transect across the Lake. There was considerable
variation among the 18 sampling sites with respect to depth, sediment
conditions, consistency and percentage gravel, sand, silt and clay in the
sediments. Benthic infauna were low in both abundance and diversity.
Oligochaetes were found in 80% of the samples. Chironomid larvae were found in
50% of the samples. Clams, snails and copepods were found in either one or two
samples. Four sites were completely devoid of animal life. Metal and organics
analyses at five of the 18 sampling sites showed comparatively high levels of at
least some toxic chemicals at each site, i.e., levels exceeding EPA's proposed
interim benthic apparent effects threshold (AET) values for Puget Sound
sediments. Quality assurance/quality control (QA/QC) data are being reviewed at
present. Factors that may contribute to the observed paucity of benthic infauna
are high toxicant levels in the sediments, saltwater intrusion, the accompanying
low DO levels in the interstitial water in the sediments, and the high
percentage of fine grains in many sediment samples.
Lalce Union and Ship Canal Storm Drain Sediment and Analysis Program
(Seattle Engineering Department)
The purpose of this study was to evaluate the pollutant input to Lake Union/Ship
Canal caused by stormwater runoff from the surrounding urban watershed.
Sediment samples were collected from eleven Lake Union/Ship Canal storm drainage
basins. Stormwater samples were collected from four of these basins. Arsenic,
cadmium, chromium, copper, lead, mercury, nickel, zinc and silver were found in
all sediment samples. Sulfides were detected in only two sediment samples.
Oil and grease, total organic carbon (TOC), and biological oxygen demand (BOD)
concentrations exceeded concentrations measured in bottom sediments of Lake
Union and the Ship Canal. The same was true for most of the metals especially
lead, nickel, cadmium, copper and zinc.
Stormwater analyses showed that pollutant loading from first flush storms
exceeds that from typical winter storms. Stormwater entering Lake Union/Ship
Canal is generally less contaminated than stormwater in other cities with
populations similar to Seattle. Basin 1 (Seaview) exhibited generally lower
concentrations of pollutants in stormwater than Basins 5, 6 and 9. Based on
comparisons of Lake Union/Ship Canal stormwater metal levels with acute water
quality criteria, it appears that lead and copper are the contaminants of
concern for long-term degradation of lake quality and impact on aquatic biota.
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Mass loadings of stormwater pollutants to Lake Union and the Ship Canal were
estimated, including total loadings from all storm drain outfalls for both the
10-year storm and average annual discharges and annual pollutant loadings from
the four basins where stormwater was collected. Basin 6 is estimated to
discharge the highest loading per acre of heavy metals, Basin 9 the highest
loading per acre of total dissolved solids.
The storm drain basins were ranked based on their relative contributions of
stormwater flow and pollutant loadings to Lake Union/Ship Canal. It appears
that efforts to control stormwater volumes and pollutant loading would be most
effective in the larger basins and in the medium-sized basins which exhibited
the highest pollutant concentrations.
A followup source evaluation is currently underway to determine from which
industrial or other shoreline uses the storm drain contaminants have come.
Potential source control measures have been proposed.
Lake Union and Ship Canal Outfall Survey (Environmental Intern Program (EIP) and
Seattle Engineering Department)
In summer-fall 1986, EIP volunteers identified 150 outfalls that discharge into
Lake Union and the Ship Canal, classified these outfalls as storm drains, sewer
drains, seeps or "other, unidentified", and identified owners/occupants of land
near the outfalls.
Combined Sewer Overflow Abatement Planning (Seattle Engineering Department)
By 'January 1, 1988, the City of Seattle will have prepared a plan for "greatest
reasonable reduction" of combined sewer overflow discharges in accordance with
the requirements of a bill passed by the state legislature in 1985. The plan
will focus on Lake Union, the Ship Canal, Elliott Bay and the Duwamish Waterway.
Criteria are currently being developed to rank alternatives (e.g., complete
separation, partial separation, storage) and to establish priorities for their
implementation.
University Regulator CSO Control Project (Metro)
In order to assess potential impacts of alternatives for diverting stormwater
from the Greenlake/I-5 University Regulator CSO, Metro collected baseline data
on water quality, sediment quality and benthic infauna in Portage Bay, north
Lake Union and the Ship Canal (at the Fremont Bridge). All six Portage Bay/Lake
Union/Ship Canal water sampling sites were low in algae abundance and exhibited
moderate to good water clarity. Washington State fecal coliform criteria were
exceeded on at least some sampling dates at all sites. There was an increase in
fecal coliform counts in a westward direction. Silver levels in the water
column exceeded acute toxicity criteria on one sampling date at the University
Regulator CSO sampling site, and exceeded chronic toxicity criteria on all
sampling dates at all sampling sites. Zinc levels also exceeded chronic
toxicity water quality criteria at the Lake Union/Gas Works Park site on two out
of the eleven sampling dates. Nickel levels exceeded human health criteria at
the 1-5 bridge site on one sampling date. Arsenic levels exceeded these
criteria at all sampling sites and on all sampling dates.
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Sediments were sampled for conventional sediment quality parameters, metals and
trace organics at eight sites. The University Regulator CSO site ranked lower
in concentration than most other sites for most parameters. The 1-5 bridge site
had consistently higher concentrations for most parameters. The mid-Lake Union
site had generally the highest concentrations for most metals; interim benthic
AET values for Puget Sound sediments were exceeded here for silver, chromium,
copper, nickel, lead and zinc. All Portage Bay sampling sites had lower
concentrations of trace organics than Lake Union and downstream Ship Canal
sampling sites. Twelve out of sixteen PAHs were found at the Ship Canal/Fremont
Bridge site at levels exceeding benthic AETs for Puget Sound sediments. By
contrast, no PAHs were found at levels exceeding benthic AETs at any of the
Portage Bay sampling sites.
The University Regulator CSO site and the South Portage Bay site had the highest
abundance of benthic infauna; the mid-Lake and Ship Canal/Fremont Bridge sites
had the lowest abundance. More taxonomic groups were found in Portage Bay
sediments than in Lake Union or Ship Canal sediments.
Gas Works Park Grpundwater Analysis Program (Seattle Parks Department and U.S.
Geological Survey)
This program was designed to determine if groundwater under and around Gas Works
Park is contaminated with toxic chemicals and is migrating into Lake Union.
Work performed thus far is: 1) seismic refraction survey to determine where to
drill test wells; 2) drilling 16 test wells and 3) collection of groundwater
samples. Results of the groundwater analyses (water temperature, pH, dissolved
oxygen, conductivity, toxic chemicals) will be available in spring 1987.
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I. INTRODUCTION
The Lake Union and Ship Canal Water Quality Management Program Data Summary
Report presented available data (as of June, 1986) on water quality, sediment
quality and biota in Lake Union and the Ship Canal, and discussed data gaps. In
December 1986, the City released the final draft of the South Lake Union Pilot
Project Report which compiled and analyzed 1986 data on water quality and
sediment quality in south Lake Union, and implications for a proposed City park
at the south end of the Lake.
In continuation of the South Lake Union Pilot Project, the City's Office for
Long-range Planning (OLP) has conducted studies on crayfish contamination and
benthic infauna (animals that live in the bottom sediments) in south Lake Union.
OLP has also reviewed Lake Union water quality data from the second half of 1986
and synoptic data on Gas Works Park sediment quality, from a recently conducted
study by the Washington Department of Ecology. Information from these new
studies is presented in this Data Summary Report Addendum. As was the case for
the original Data Summary Report, water quality data was compared with existing
federal and state water quality standards and criteria. In the absence of
freshwater sediment quality criteria, toxicant levels in Lake Union sediments
were compared with interim sediment quality values proposed for Puget Sound
sediments, i.e., benthic apparent effects threshold (AET) values.
This Data Summary Report Addendum also presents updates for five projects that
are related to the overall Lake Union and Ship Canal Water Quality Management
Program: (1) Seattle Engineering Department's Storm Drain Sediment and Analysis
Program, (2) the related outfall survey conducted by the Environmental Intern
Program, (3) Seattle Engineering Department's Combined Sewer Overflow Abatement
Planning, (4) Metro's University Regulator CSO Control Project, and (5) Seattle
Parks Department and U.S. Geological Survey's Gas Works Park Groundwater
Analysis Program. Raw data from these ongoing studies is documented where
available. Although there are still many gaps in what is known about
environmental conditions in Lake Union and the Ship Canal, the new data
presented in this report will be useful in prioritizing problem areas for source
control and remedial actions.
II. ONGOING WATER QUALITY MONITORING
Metro continues to monitor the Lake Union water column on a semimonthly basis
for conventional water quality parameters (see Figure 1 for location of Metro
sampling site on the west side of the Lake). Major findings during July-
December 1986 (Freshwater Assessment Reports, 1986) are summarized below for
three of these water quality parameters that indicate water quality problems in
the Lake (Table 1).
Saltwater Intrusion
Saltwater intrusion from Shilshole Bay into the Ship Canal and Lake Union,
resulting from heavy usage of the Chittenden Locks during the summer months, is
reflected in high conductivity and high turbidity in the Lake bottom from July-
October. Conductivity in the Lake bottom returned to low values in November and
December. This change reflects decreased saltwater intrusion and the mixing of
the water column that occurs when Lake Union overturns in the fall.
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DATE
12/02/86
12/16/86
TABLE 1 Cont.
DISSOLVED OXYGEN, CONDUCTIVITY, TURBIDITY AND
FECAL COLIFORMS IN LAKE UNION
July - December 1986
DEPTH
METERS
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
DO
COND.,
;umh/cm
10.1
9.9
9.9
9.9
9.8
9.0
10.3
9.8
102
102
101
100
100
100
100
100
TURB.,
NTU
0.7
0.8
0.8
FEC. COL.,
Organisms/lOOml^
61**
87
**
0.7
* DO Levels do not meet water quality criteria for protection of aquatic life.
**Fecal coliform levels do not meet water quality criteria for protection of
human health.
umh/cm = micromohs/centimeter
NTU = nephelometric turbidity units
Source: Freshwater Assessment Reports. 1986.
(209)792.T1
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TABLE 1
DISSOLVED OXYGEN, CONDUCTIVITY, TURBIDITY AND
FECAL COLIFORMS IN LAKE UNION
July - December 1986
DATE
7/08/86
7/22/86
8/05/86
8/19/86
9/08/86
9/23/86
10/07/86
10/21/86
11/03/86
11/19/86
DEPTH
(meters)
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
1.0
5.0
10.0
14.0
DO
(ma/i)
9.7
9.3
7.2
1.1*
9.1
8.9
6.5
0.8*
9.6
10.1
8.0
1.2*
8.6
9.4
4.7*
1.2*
8.7
7.7
4.7*
1.7*
7.9
5.5
3.9*
2.9*
8.0
6.1
5.7
4.4*
8.7
10.5
9.6
4.9*
8.7
8.4
8.6
7.9
9.3
7.5
7.5
7.8
CO NO.,
Cumh/cm)
140
155
300
2000
151
155
198
750*
141
143
201
915
131
132
230
840
150
154
310
900
250
250
255
1040
230
220
240
290
210
205
210
800
180
185
175
171
126
125
126
126
TURBIDITY
(NTU)
0.7
0.9
0.8
9.5
2.1
1.4
1.1
3.5
0.6
0.8
0.8
5.4
0
0
0,
5.2
0.8
1.2
0.8
3.5
1.2
.3
.7
.7
.7
1.
1.1
4.2
0.7
0.7
0.7
1.2
0.7
0.8
0.7
1.2
0.9
1.1
0.9
0.8
0.9
0.9
1.0
0.9
FECAL COLIFORMS
(organisms/100ml)
31
17
39
12
,**
60
91**
23
73*^
44
98
!**
(209)792:T1
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Hnn
r
Additional Sampling Sites in Lake Union
Benthic Infauna Sampling Site (University
Regulator CSO Control Project)
Benthic Infauna Sampling Site (Other
Studies)
Crayfish Sampling Site
Ongoing Water Quality Monitoring Site (Metro)
Water Column Sampling Site (University
Regulator CSO Control Project)
Sediment Chemistry Sampling Site (University
Regulator CSO Control Project)
Sediment Chemistry Sampling Site (South Lake
Union Pilot Project)
1, 2, 3, 4, 5, Iw, 1m, le, Sediment Sampling
Station Numbers
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Water Column
Dissolved oxygen (DO) levels were correspondingly low in the Lake bottom from
July - October, i.e. below the 5 mg/1 water quality criterion for protection of
aquatic life. In November and December, when the Lake bottom was less saline
and water temperatures were lower, DO levels met the water quality criterion
throughout the water column.
Fecal Coliforms
Fecal coliform counts met state water quality standards (^50 organisms/ml)
during July and August. This means that the counts were not high enough to
threaten the health of people engaged in water contact sports. Fecal coliform
counts did exceed the water quality standard during rainy periods in September-
December.
III. OFFSHORE GAS WORKS PARK SEDIMENT QUALITY
The triad approach (sediment chemistry analysis, sediment toxicity analysis and
benthic infauna surveys) was applied to compare sediments from an offshore Gas
Works Park (GWP) site in Lake Union (Figure 1) and a reference site in pristine
Chester Morse Lake (Yake et al., 1986). Chester Morse Lake (CML) was chosen as
a reference site because it is located within the protected watershed of the
Seattle Water Department. Human activities that could contribute contamination
to the waters and sediments of Chester Morse Lake are therefore minimized.
Sediment Chemistry
Table 2 compares levels of polycyclic aromatic hydrocarbons (PAHs) and
polychlorinated biphenyls (PCBs) in offshore GWP and in CML sediments. Offshore
GWP sediment was contaminated with high levels of PAHs (ranging from 40 ppm for
naphthalene and fluorene to 750 ppm for pyrene) and PCBs (4.3 ppm). These PAH
and PCB levels exceeded the Environmental Protection Agency's proposed interim
benthic apparent effects threshold (AET) values for Puget Sound sediments. By
contrast, no PAHs or PCBs were detected in CML sediment.
Table 3 compares levels of metals in offshore GWP and in CML sediments. The
following six metals were found at higher concentrations at the GWP site:
cadmium (4X as high), chromium (2X as high), lead (22X as high), mercury (9X as
high), nickel (9X as high) and zinc (4X as high). Lead, nickel and zinc levels
in the GWP sediment sample exceeded interim benthic AET values for Puget Sound
sediments.
Sediment Toxicity
Sediment toxicity was determined by a bioassay, using the freshwater amphipod
Hyalella azteca_. This amphipod was exposed to various concentrations of GWP and
CML sediments for ten days. GWP sediment was significantly more toxic to
Hyalella than CML sediment, with toxicity generally increasing as the GWP
content of the sediment increased (Table 4). Hyalella mortality was 95 percent
when exposed to undiluted GWP sediment compared to 8 percent when exposed to
undiluted CML sediment.
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TABLE 2
ORGANIC LEVELS IN LAKE UNION
(OFFSHORE GAS WORKS PARK)
AND CHESTER MORSE LAKE SEDIMENTS
Organic Chemical Gas Works Park Chester Morse Lake
(ppm dry weight) (ppm dry weight)
Polycyclic Aromatic Hydrocarbons
Naphthalene 40J lOOu
Acenaphthylene 92 lOOu
Fluorene 40J lOOu
Phenanthrene 410 lOOu
Anthracene 120 lOOu
Fluoranthene 570 lOOu
Pyrene 750 lOOu
Benzo(a)anthracene 170 lOOu
Chrysene 170 lOOu
Benzo(k)fluoranthene 240 lOOu
Benzo(a)pyrene 220 lOOu
Indeno(l,2,3-cd)pyrene 120 lOOu
Benzo(g,h,i)perylene 190 lOOu
Benzo(a)pyrene 280 lOOu
Pesticides/PCBs
PCB-1242 4.3 60u
u = Not detected at detection limit specified
J = Estimated value.
Source: Yake et al. 1986
(209)792.T2
10
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TABLE 3
METAL LEVELS IN LAKE UNION
(OFFSHORE GAS WORKS PARK)
AND CHESTER MORSE LAKE SEDIMENTS
Metals Gas Works Park Chester Morse Lake
(ppm dry weight) (ppm dry weight)
Cadmium 1.98 0.46
Chromium 20 10
Copper 156 160
Lead 300 13.9
Mercury 0.173 0.019
Nickel 88.3 9.8
Zinc 320 84
Source: Yake et al . 1986
(209)792.T3
11
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TABLE 4
RESULTS OF AMPHIPOD (HyaleUaazeteca)
SEDIMENT BIOASSAY IN LAKt UNION "
(OFFSHORE GAS WORKS PARK)
AND CHESTER MORSE LAKE SEDIMENTS
Percent* Gas Works Park Percent Chester Morse Average Mortality
Sediment Lake Sediment (percent, 3 replicates)
0 100 8.3
1 99 6.7
3.3 96.7 13.3
10 90 13.3
33 67 20
100 0 95
*Percent determined on a weight basis.
Source: Yake et al. 1986.
(209)792.T4
12
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Benthic Infauna
Table 5 compares numbers of animals found in major taxonomic groups in both GWP
and CML sediments and compares diversity of taxonomic groups, as indicated by
Brillouin's Diversity Index and the Shannon-Weaver Diversity Index. The
abundance and diversity of benthic infauna in offshore GWP sediment were
significantly lower than in CML sediment. Diversity was almost twice as high in
sediment from the reference site as in sediment from the offshore GWP site.
IV. SOUTH LAKE UNION PILOT PROJECT ADDENDUM
Interpretation of Sediment Chemical Oxygen Demand Values
As part of OLP's South Lake Union Pilot Project, sediments were collected from
five areas in south Lake Union in spring 1986 (see Figure 1 for location of
areas), at distances of 50', 150' and 300' from the shoreline within each area.
In this report, the sampling sites will be referred to as 1-50, 1-150, 1-300
(also called 1-Drydock), 2-50, 2-150, 2-300, etc. Sediments from the fifteen
sites were analyzed for several sediment quality parameters including chemical
oxygen demand (COD). This parameter is a measure of the amount of oxygen in a
sediment sample that is consumed by the chemicals present in that sample. COD
levels in the tested Lake Union sediments ranged from 2 parts per thousand (ppt)
at site 4-50 to 71 parts per thousand (ppt) at site 4-300 (South Lake Union
Pilot Project Report, 1986).
High COD levels are usually correlated with low DO levels. Field investigations
of GOD values in Lake Michigan sediments have provided a yardstick for judging
how high is high. Gardiner et al. (1985) found that regions of Green Bay (a
large gulf in the northwest corner of Lake Michigan) with sediment COD > 50 mg
02/gram dry weight (>50 ppt) exhibited DO depletion and were poorly colonized by
benthic infauna. Auer and Auer (1986) found that regions of Fox River (Green
Bay's major tributary) with sediment COD > 50 ppt exhibited DO depletion and had
levels of hydrogen sulfide and ammonia-nitrogen that are potentially toxic to
aquatic life.
Two sampling sites in south Lake Union had sediment COD levels that exceeded
50 ppt (68 ppt at 3-300 and 71 ppt at 4-300). Three other sampling sites had
sediment COD levels of 50 ppt (5-150) or close to 50 ppt (48 ppt at 1-150 and
5-50). It is likely that DO levels were low in these sediments, creating
inhospitable conditions for benthic infauna. For more information on this
subject, see the discussion in this report on the benthic infauna survey
conducted in the vicinity of the South Lake Union pilot project sampling sites.
Crayfish Tissue Analyses
Metal and PCB levels were measured in raw and cooked edible (tail) tissue of
crayfish harvested in summer - fall 1986 from south Lake Union near the City
Light Steam Plant (30 crayfish) and near the proposed new City park (22
crayfish) (see Figure 1 for harvest locations). The crayfish were frozen and
divided into two groups: one for metal analyses and one for PCB analyses.
Thawing took place on the day that the analyses were performed.
13
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TABLE 5
BENTHIC INFAUNA1 IN LAKE UNION
(OFFSHORE GAS WORKS PARK)
AND CHESTER MORSE LAKE SEDIMENTS
Taxonomic Groups Lake Union Chester Morse Lake
Unsegmented worms 3 0
Nematodes 3 31
Oligochaetes 208 184
Other segmented worms 0 15
Snails 0 7
Clams 18 41
Hydra 1 0
Bryozoa 1 0
Amphipods 0 24
Other Arthropods 1 5
Chironomids 7 372
Other insects 0 2
Brillouin's Diversity Index 1.69 2.95
Shannon-Weaver Diversity Index 1.79 " 3.04
Each number is the total for four replicate sampling sites and represents the
number of animals found per 0.0232 m2 grab.
Source: Yake et al. 1986.
(209)792.T5
14
-------
For measuring metal levels, the tails were removed from each crayfish. The tail
samples from half of the crayfish were boiled in distilled, deionized water in a
Pyrex glass container until the shells turned red in color; tail meat was
dissected from the shells in both cooked and uncooked samples. The cooked meat
was treated as one composite sample; the uncooked meat was treated as another
composite sample. Each composite sample (10 grams of tail meat) was digested
with concentrated nitric acid and hydrogen peroxide and analyzed for nine heavy
metals in accordance with EPA Method 600/4-79-020. Arsenic, chromium and silver
levels were determined by graphite furnace atomic absorption; all matrix
interferences were determined and corrected. Mercury levels were determined by
cold vapor; cadmium, copper, lead, nickel and zinc levels were determined by
flame atomic absorption. An extraction blank was analyzed with every heavy
metal determination for quality assurance/quality control. Analyses of blanks
demostrated that there was no contamination from the laboratory procedures above
the minimum detection limits.
For measuring PCB levels, half of the total number of crayfish were boiled whole
for 5 minutes in tap water in a Pyrex glass container. Tail meat was dissected
from both cooked and uncooked fish. The cooked meat was treated as one
composite sample; the uncooked meat was treated as another composite sample.
Each composite sample (20-30 grams of tail meat) was analyzed for PCBs by gas
chromatography in accordance with EPA Method 8080. Two extraction blanks and
one spike were run for quality assurance/quality control. Analyses of blanks
demonstrated that there was no contamination from the laboratory procedures
above the minimum detection limits. The spike recovery rate of 115 percent also
indicated no significant contamination from the laboratory procedures.
Metals. Table 6 presents heavy metal levels found in raw and cooked tail meat
of crayfish harvested from south Lake Union, and compares this data with data
obtained for crayfish harvested from three other sites: 1) Lake Union off Gas
Works Park, 2) the Montlake Cut and 3) the Ship Canal (Frost et al., 1984).
Metal levels in raw and cooked crayfish tail tissue were within the range
expected for crustaceans from urban waters and were not of concern to the
Seattle-King County Health Department. The U.S. Food and Drug Administration
(FDA) has established tolerance standards for mercury (0.5 ppm) and cadmium (1
ppm) in shellfish and fish. Mercury levels (<0.1 ppm) and cadmium levels (0.08
- 0.39 ppm) in both raw and cooked tail tissue of crayfish harvested from south
Lake Union did not exceed the tolerance standards. With the exception of
arsenic, all metal levels are consistent with previous studies conducted on Lake
Union crayfish and other crustacean and clam samples collected around Puget
Sound. Arsenic levels (1.9-5.1 ppm raw, 3.8-9.9 ppm cooked) were higher than in
crayfish harvested in 1984 (Frost et al., 1984) from offshore Gas Works Park,
the Montlake Cut and the Ship Canal, but were still within the range reported in
shellfish from other studies (e.g., comparable levels found in littleneck clams
harvested at the ferry dock at Tahlequah on Vashon Island) (Price, 1978).
Furthermore, most of the arsenic absorbed by seafood is in protein-bound,
non-toxic forms which are readily excreted, unchanged, by humans.
15
-------
METAL AND PCB LEVELS IN CRAYFISH TAIL TISSUE (ppm wet weight)
Metal/PCBs Station 2 Station 5 Montiake Cut* Gas Works Park* Ship Canal*
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury'
Nickel
Silver
Zinc
Total PCBs?/
Raw
5.1
0.12
<0.01
3.4
0.06
<0.1
0.92
0.15
10
0.09
Cooked
9
0
0
9
1
<0
0
0
21
0
.9
.39
.05
.7
.1
.1
.64
.35
.66
Raw
1.9
0.09
<0.01
1.6
0.51
<0.1
0.37
0.25
8.6
<0.04
Cooked
3.8
0.08
0.05
8.9
1.0
<0.1
0.41
0.30
17
0.06
Cooked, 9/84
0.
0.
NA
18.
1.
0.
NA
NA
NA
0.
22
05
8
5
24
01
Cooked, 9/84
0.
0.
NA
ND
0.
0.
NA
NA
NA
0.
34
03
Cooked, 9/84
0.
0.
62
44/0.62
NA
41
21
17
20.
0.
0.
NA
NA
NA
0.
6/25.4
83/0.75
18
11
These values are from: Frost, et al. 1984. Duplicate values were obtained in a few cases. In the study
by Frost et al., whole crayfish were cooked, and tail meat was dissected out.
ND = not detected.
NA = not applicable. This means that the particular metal was not analyzed in crayfish at that station.
U = Food and Drug Administration standard for mercury in fish and shellfish is 0.5 ppm and for cadmium in
fish and shellfish is 1 ppm.
2/ = Food and Drug Administration standard for PCBs in fish and shellfish is 2 ppm.
(209)792.T6
-------
PCBs. Table 6 presents PCB levels found in raw and cooked tail tissue of
crayfish harvested from south Lake Union, and compares this data with data
obtained for crayfish harvested from three other sites in Lake Union/Ship Canal.
The reported PCB level of 0.66 ppm in cooked tail tissue of crayfish harvested
near the City Light Steam Plant was 4-6 times as high as the PCB levels measured
in crayfish harvested from offshore Gas Works Park and the Ship Canal in 1984.
This concentration is still well below the FDA tolerance standard for PCBs in
shellfish and fish (2 ppm). However, FDA tolerance standards are aimed at
regulating toxicants in shellfish and fish in interstate commerce for which a
national market exists and for which it is appropriate to use national
consumption figures. More conservative values may be needed to protect local
populations consuming large quantitites of shellfish and fish from local waters.
Therefore, the standard for PCBs may be too lenient for protecting the health of
people who consume large quantities of crayfish from Lake Union.
The reported PCB level in cooked tail tissue of crayfish harvested near the City
Light Steam Plant was 7 times as high as the reported PCB level (0.09 ppm) in
raw tail tissue of crayfish harvested from the same area. The raw tissue weight
of 30 grams compared to the cooked tissue weight of 20 grams suggests the
evaporation of water during the cooking process may have concentrated PCBs in
the cooked tissue. Migration of PCBs from the hepatopancreas to the muscle
tissue during the cooking process is another plausible explanation. However, we
lack data to determine if the two samples were equivalent in total fish weight,
age distribution (older crayfish could pick up more PCBs from their environment
than younger fish) and percent lipids in tail tissue (which would affect uptake
of PCBs). The Seattle-King County Health Department has recommended further PCB
analyses with replicate samples at each location and establishment of
comparability between cooked and uncooked tissue.
Benthic Infauna Survey. The purpose of this survey was to obtain a general idea
of what 'animals, if any, were living beneath the sediments in some areas of Lake
Union. The survey was not intended to be a comprehensive assessment of the Lake
Union benthic community.
In November 1986, the EPA Dive Team conducted a visual inventory of the bottom
of Lake Union and collected sediment samples for benthic infauna and sediment
grain size analyses from fifteen sites in the south end of the lake and three
additional sites on an east-west transect across the lake (see Figure 1 for
location of sampling sites). Diver-held cores (area of cylinder face =
21.36 cm2, collection depth = 10 cm beneath surface) were used for sediment
sampling at all sites except four (1-150, 1-Drydock, 2-50, 3-300) where the
sediments were too soft to be contained in the cores and the mid-lake site (1-M)
where diving was considered unsafe. Core subsamples of Van Veen grabs were
taken at these five sites, using the diver-held cores and collecting 10 cm
beneath the surface.
For each sampling site, sediment samples for benthic infauna analysis and for
grain size analysis were placed in separate, labelled plastic bags which were
stored outdoors (air temperature = 35°-40°F) until the end of the two day
sampling period. Each sample consisted of the entire contents of one core
rather than a composite of several cores. One set of samples was delivered to
Laucks Testing Laboratories (Seattle, WA) for grain size analysis of the
sediments using the pi pet modification of ASTM Method D-422. The other set of
samples was processed for benthic infauna analysis by Invert-Aid (Tacome, WA).
17
-------
The samples were fixed in 7 percent buffered formalin and, after a minimum of
two days fixation, were washed in tap water, screened through a 0.5 mm mesh and
preserved in 70 percent ethanol. Samples were examined through a binocular
microscope at lOx to 30x. Notes were made on sediment characteristics, and
unusual odors and sheens detected during the washing process. Benthic infauna
were removed from the sediments, identified by major taxonomic groups and
counted. Residues were retained; residues and benthic infauna are archived at
the Invert-Aid laboratories. In order to check the consistency of quality, six
of the samples (30% of the samples) were resorted. No previously undetected
specimens were found during this procedure.
In addition to collecting sediment samples for benthic infauna and sediment
grain size analyses, the EPA Dive Team took Van Veen grabs at 1-Drydock, 2-50,
3-300, 4-300 and 5-50 for analyses of metal, PCB and PAH levels in the sedi-
ments. These sites were selected for sediment chemistry testing because they
were the most heavily contaminated (1-Drydock, 2-50, 3-300, 5-50) at four
sampling areas and the least contaminated at one sampling area (4-300) in the
South Lake Union Pilot Project. The sediment samples were placed in clean glass
jars for transportation to the EPA Laboratory (Manchester, WA) for sediment che-
mistry analyses. Recommended protocols of the Puget Sound Estuary Program were
followed in collecting these samples (Tetra Tech, 1986b).
Results. There was considerable variation among the 18 sampling sites with
respect to depth, sediment conditions, consistency and particle size (percentage
gravel, sand, silt and clay in the sediments) (Tables 7-8). Sediments were
fine-grained and soft in many places, oily in others, gelatinous in others. The
EPA divers observed crayfish at two stations (1-50 and 4-150) and some plant
life (Elodea, a filamentous green alga) at a few other stations (3-150, 3-300,
5-50, 1-E) but no other animal life was apparent during their visual inventory
of the Lake bottom.
Table 9 presents the results of the benthic infauna survey. Two sets of numbers
are given for each group: the actual number of specimens found in the sample,
and an estimated number of individuals that would be found in one square meter
(m2) of sediment if the animals were uniformly distributed throughout the
sediment (uniform distribution may or may not be the case). The latter numbers
were obtained with a formula used in Metro benthic infauna surveys: N = s x
105/2136 where s = the number of specimens in the sample and 2136 = the surface
area of the sampler face in square millimeters (mm2). For comparative purposes,
benthic infauna analysis data from Gas Works Park offshore sediments and from
Chester Morse Lake sediments (Yake et al, 1986) are also presented in Table 9.
Numbers are not presented for two samples (5-150 and 5-300) because these
samples were inadvertently misplaced for two weeks, hence precluding accurate
analyses.
Benthic infauna were low in both abundance and diversity. Oligochaetes, a group
of segmented worms which inhabit clean areas and also tolerate highly organic,
low oxygen conditions, were found in 80% of the samples (3 to 300 animals per
sample). Chironomid (midge) larvae, which can also tolerate anaerobic
conditions, were found in 50% of the samples (1 to 3 animals per sample). Three
clams were found in one sample, one snail was found in a different sample and
four amphipods were found in yet another sample. Four sites (1-Drydock, 2-300,
4-300 and 1-M) were completely devoid of animal life. A paucity of benthic
infauna means a paucity of food for resident fish.
18
-------
STATION
TABLE 7
LAKE UNION SEDIMENT CONDITIONS
CONDITION _L/
DEPTH2/
SAMPLE TYPES
1-50
1-150
1-Drydock
2-50
2-150
2-300
3-50
3-150
3-300
4-50
4-150
4-300*
5-50A*
5-50B
5-50C
5-150
5-300
very oily, detritus, black mud
with white fungus
oily, bits of plastic, mud,
wood debris
fine detritus
grey clay with greenish tinge,
thick layer with organic debris and
gelatinous consistency
grey clay, no residue, thick layer
with organic debris as in 2-50
clay, no residue, thick layer
with organic debris as in 2-50
black sand, detritus
rock, gravel, lots of plant material
(e.g. Elodea)
sand, gravel, plant detritus,
Elodea
wood debris, sand, fine gravel
wood debris, sand, fine gravel
blue clay, some gravel
wood debris, Elodea
wood debris
wood debris
wood debris, oily smell and sheen
wood debris, oily smell and sheen
(meters)
7.2
10.8
12.8
9.5
11.1
8.9
5.0
5.1
10.4
3.2
8.3
6.6
6.5
6.5
6.5
6.0
8.1
Cores
Van Veen
Van Veen
Van Veen
Cores
Cores
Cores
Cores
Van Veen
Cores
Cores
Cores,
Van Veen
Cores,
Van Veen
Cores
Cores
Cores
Cores
(209)792.T7
19
-------
TABLE 7 (Cont.)
LAKE UNION SEDIMENT CONDITIONS
STATION CONDITION DEPTH SAMPLE TYPES
(meters)
1-W grey clay, detritus (fibrous), small N/A Cores
wood particles
1-M some detritus, clay, small particles N/A Van Veen
1-E oil, wood debris, Elodea, grey N/A Cores
sediments with brown streaks
JL/ Descriptions of sediment conditions are based on visual observation of
sediments and photographs taken.
JL/ For each sampling site, the sediment sample was collected at the same
depth as in the South Lake Union Pilot Project.
N/A = data not available for this station.
* = At these stations, diver held cores were used to collect sediment for
benthic infauna and grain size analyses. The Van Veen grab sampler was
used to collect sediment for sediment chemistry analysis.
(209)792.T7
20
-------
TABLE 8
GRAIN SIZE ANALYSIS
OF LAKE UNION SEDIMENT SAMPLES
PERCENT SEDIMENTS (dry weight)
STATION
1-50
1-150
2-50
1-Drydock
2-150
2-300
3-50
3-150
3-300
4-50
4-150
4-300
5-50
5-150
5-300
1-W
1-M
1-E
Gas Works
offshore
GRAVEL
(> 2mm)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
23.0
18.0
20.0
0.0
54.0
0.0
0.0
18.0
0.0
0.0
0.0
Park,
5.1
SAND
T>6ir urn
-<2mm)
71.0
67.0
2.5
53.7
2.2
1.9
69.2
59.5
64.8
78.3
49.8
43.6
47.9
53.3
58.9
8.1
13.8
30.0
45.9
SILT
(>4 urn
-<62um)
13.3
14.2
70.1
29.8
73.6
67.3
26.8
15.1
14.3
1.5
38.6
1.1
45.4
40.6
17.5
54.7
37.2
42.2
36.9
CLAY
(< 4um)
12.7
18.8
27.4
16.5
24.2
30.8
0.0
2.4
2.9
0.2
9.6
1.3
6.7
6.1
5.6
37.2
49.0
23.8
12.1
MISCELLANEOUS*
3.0
0.0
0.0
0.0
0.0
0.0
4.0
0.0
0.0
0.0
2.0
0.0
0.0
0.0
0.0
0.0
0.0
4.0
0.0
Organic matter retained on 2 mm sieve
(209)792.T8
21
-------
Two caveats must be considered in analyzing the benthic infauna data. Since
there was scant prior information on benthic infauna in Lake Union and since the
City's sampling funds were limited, EPA and other agencies recommended taking
one sample at each site rather than three replicates at each site. Therefore,
the benthic infauna found in each sample are not necessarily representative of
the benthic infauna in the adjacent areas. At the one site (5-50) where three
replicates were taken, diversity varied among the replicates. Sample 5-50A
contained oligochaetes, chironomids and amphipods (the only amphipods found in
this survey). This sample also contained Elodea with which the amphipods are
probably associated. Sample 5-50B contained only oligochaetes. Sample 5-50C
contained oligochaetes and chironomids.
A second caveat is that core subsamples taken from Van Veen grabs at five sites
may not have been representative samples because the sampling process may
disrupt the natural spatial distribution of motile animals. For example,
surface-dwelling animals may move to the edges of the sample as the grab is
being retrieved. The number and type of animals identified may have been
different if it had been possible to collect sediment with diver-held cores at
those sites.
Table 10 presents data on metal and organics levels in the five sediment
samples where sediment chemistry testing was performed. The review of the
quality assurance/quality control (QA/QC) data is forthcoming. As was the case
in the South Lake Union Pilot Project, 1-Drydock was the site with the highest
metal levels and 2-50 was the site with the highest PCB levels. Each site had
comparatively high levels of at least some toxic chemicals, i.e., levels
exceeding EPA's proposed interim benthic apparent effects threshold (AET) values
for, Puget Sound sediments. These values are sediment toxicant levels that, when
present, are associated with a decrease in the number and types of benthic
infauna in Puget Sound sediments (Tetra Tech, 1986a). Benthic AET values have
not been proposed for freshwater sediments. The Puget Sound numbers may or may
not be applicable to Lake Union benthic infauna; the numbers are used here for
comparative purposes because they are the best yardsticks available at present.
Given these caveats, the sediment chemistry analyses showed that zinc levels
were elevated in sediments from all five sites; nickel levels were high at all
sites except 4-300, and lead levels were high at all sites except 3-300 and
4-300. Arsenic and cadmium levels were also particularly high at the 1-Drydock
site. Total PCBs exceeded the benthic AET value for Puget Sound sediments at
2-50. Some PAHs were also found at levels exceeding benthic AETs for Puget
Sound sediments at some of the sampling sites.
22
-------
TABLE 9
LAKE UNION BENTHIC INFAUNA SAMPLING RESULTS
''I
NATION
if!
1
OLIGOCHAETA
(worms)
CHIRONOMID
LARVAE
(insects)
PELECYPODA
(clams)
GASTROPODA
(snails)
AMPHIPODA
(crustacea)
NEMA-
TODES
OTHER
»t-50 51:23,876
*-150 70:32,771
-Drydock 0:0
2:936
Si-50
-150
-300
t
j
-50
i>150
-300
-50
:-150
"5-300
-50A
H-50B
,^50C
:-M
>E
-W
6:2,808
3:1404
0:0
142:66,479
300:140,449
61:28,558
58:27,153
16:7,490*
6:2808
0:0
14:6554
8:3745
. 6:2808
0:0
10:4681
4:1872
2:936
3:1404
1:468
3:1404
3:1404
1:468
1:468
3:1404
1:468
as Works
iff shore 19:8,895
Chester
torse
take!/
1:468
3:1404
2:936
2:936
1:468
1:458
4:1872
1:468
17:7,956 34:15,912 4:1,872 1:468 2:936 3:1,404 2:936
2
umbers indicate individuals per sample: followed by estimated numbers/m .
Oligochaete cocoons (Barnes, 1980).
These numbers are from Yake, et al. (1986). The sampling device used in their study had
surface area of 232 cm2. The original numbers obtained were therefore corrected for
he surface area of the sampling device (21.36 cm2) used in the benthic infauna study
onducted by the Office for Long-range Planning, i.e., the numbers from Yake, et al
1986) are divided by 11.
209)792.T9
23
-------
Chemical Level,
ppm dry weight
Arsenic (85)*
Cadmium (5.8)
Chromium (59)
Copper (310)
Lead (300)
Nickel (49)
Silver (5.2)
Zinc (260)
Mercury (0.88)
PCB-1260
PCB-1254
PCB-1221
PCB-1232
PCB-1248
PCB-1016
PCB-1242
TOTAL PCBs (1.10)
TABLE 10
METAL AND ORGANICS LEVELS IN
SOUTH LAKE UNION SEDIMENT SAMPLES
Sample Site
-Drydock
1470**
5.12
108.5**
2177**
2394**
54.9**
3.55
6060**
2.3**
0.29
0.61
ND
ND
ND
ND
ND
0.90
2-50
41
3.86
64.8**
724**
1025**
83.8**
4.39
880**
0.20
0.36
1.20
ND
ND,
ND
ND
ND
1.56**
3-300
7.3
1.7
38.8
99.2
289
50**
0.46
300**
0.14
0.062
0.18
ND
ND
ND
ND
ND
0.242
4-300
0.48
1.76
29.2
195.7
242
34.9
1.70
670**
0.066
ND
0.21
ND
ND
ND
ND
ND
0.21
5-50
20.3
4.09
42.5
232.3
1216**
50.9**
1.85
650**
0.12
0.23
0.50
ND
ND
ND
ND
ND
0.73
209-792.T10
24
-------
TABLE 10 Continued
METAL AND ORGANICS LEVELS IN
SOUTH LAKE UNION SEDIMENT SAMPLES
Sample Site
Chemical Level,
ppm dry weight 1-Drydock
Benzo(a)pyrene (6.80)
Dibenzo(a,h)anthracene
(1.20)
Benzo(a)anthracene (4.50)
Acenaphthene (0.50)
Phenanthrene (3.20)
Fluorene (6.40)
Naphthalene (2.10)
Anthracene (1.30)
Pyrene (7.30)
Benzo(ghi )perylene(5.40)
Indeno(l,2,3-cd)pyrene
(8.00)
Benzo(b)fluoranthene (6.30)
Fluoranthene (6.30)
Benzo(k)fluoranthene(0.64)
Acenaphthylene (0.64)
Chrysene (6.70)
1.2
NO
1.3
ND
1.8
ND
ND
0.4
0.3
2.2
0.8
1.7
2.4
0.7
ND
1.3
2-50
3.7
2.3**
2.6
ND
4.5**
ND
ND
1.1
1.3
6.2**
2.4
4.9
5.3
1.7
ND
3.7
3-300
1.1
0.9
1.1
ND
2.2
ND
ND
0.3
0.6
2.1
0.8
1.5
2.2
0.6
ND
1.4
4-300
2.3
1.0
3.0
ND
11
ND
ND
1.6**
0.5
4.2
0.8
3.0
8.4**
1.3
ND
2.6
5-50
2.1
1.6**
1.7
ND
4.1**
ND
ND
0.06
1.0
3.5
1.2
2.9
3.7
1.0
ND
2.5
* The number in parentheses after the name of each chemical is the benthic
apparent effects threshold (A.E.T.) value, in ppm, for Puget Sound
sediments.
** These levels exceed benthic A.E.T. values for Puget Sound sediments.
ND = not detected
209-792.TlOa
25
-------
High toxicant levels may be partly responsible for the observed paucity of
benthic infauna. Other likely contributing factors are the saline content of
the sediments due to saltwater intrusion from the Locks, the accompanying low DO
levels in the interstitial water in the sediments, and the high percentage of
fine grains in many sediment samples. In general, more animals were found in
the shallowest sites (< 6 meters) where the sediments would be less saline and
more oxygenated than in the deepest sites (> 10.5 meters). No animals were
found in sediments at the two deepest sites (1-Drydock and 1-M). In addition,
sediments at 1-Drydock were contaminated with high levels of several metals and
contained 50 percent fine-grained particles (silt and clay). Sediments at 1-M
contained 86% silt and clay. By contract, animals were comparatively numerous
at 3-300 and diverse at 5-50. Both these sites were shallower and less
contaminated than 1-Drydock; 3-300 contained a high percentage of sand and low
percentages of fine grains. In order to perform an accurate analysis of factors
responsible for low abundance and diversity of benthic infauna, it would be
necessary to have synoptic data including sediment chemistry, benthic infauna
(mean and standard deviation for three replicates), DO and salinity for each
sampling site. Although synoptic data is lacking, the information that is
available on sediment chemistry and benthic infauna indicates that the lake
ecosystem is not healthy, at least in South Lake Union.
V. RELATED PROJECTS
Lake Union and Ship Canal Storm Drain Sediment and Analysis Program
(Seattle Engineering Department).
The purpose of this study was to evaluate the pollutant input to Lake Union/Ship
Canal caused by stormwater runoff from the surrounding urban watershed. To
distinctly identify stormwater contributions to pollutant input, the separate
storm drainage system was studied rather than the combined sanitary and
stormwater system. The study scope and results are summarized below from
Kennedy/Jenks/Chilton (1987).
Sediments were collected from eleven of the twenty major Lake Union/Ship Canal
storm drainage basins (see Figures 2-4 for sampling locations). Four other
basins were examined, but insufficient amounts of sediment were present to
warrant sampling. The remaining basins have smaller drainage areas and were not
examined for sediment during the course of this study. To collect a sediment
sarnie representative of the whole drainage basin, sediments were collected from
either the terminal manhole or from the lowest dry manhole in each collection
system. Each sediment sample was analyzed for total organic carbon and total
sulfides. The results from those tests provide a general indication of
pollutant loadings. Depending on the quantity of the remaining sample, analyses
were performed for various metals. Arsenic, cadmium, chromium, copper and lead
were analyzed as a minimum group because of their high toxicity and/or suspected
presence in the sediments. Where enough sediment was available, testing was
also performed for beryllium, mercury, nickel, zinc, silver, selenium,
biological oxygen demand (DOD), and oil and grease.
26
-------
Portage \ [l ] L_
Bay N U
i
CM
1/2 mi
Figure 2:
Storm Drain Sediment and Stormwater
Sampling Sites in Lake Union
Legend
Storm Drain Sediment Sampling Site
* Stormwater Sampling Site
l°l Drainage Basin Number
303 Drainage Area in Acres
-------
Figure 3:
Storm Drain Sediment and Stormwater Sampling Sites
in the Ship Canal
Salmon Bay
Waterway
\\_JL_
Legend
* Storm Drain Sediment Sampling Site
* Stormwater Sampling Site
0 Drainage Basin Number
303 Drainage Area in Acres
00
1/2 mi
-------
Figure 4
Lake Union and Ship Canal Drainage Basins
LEGEND
IDENTIFIED DRAINAGE
BASIN & NUMBER
A STORM DRAIN
FREEWAY DRAIN
Source: Kennedy/Jenks/Chilton (1987)
CT>
OJ
-------
Four basins (Basins 1, 5, 6 and 9 - see Figures 2-4) were monitored for
stormwater flow. These basins are representative of the area that contributes
runoff to Lake Union and the Ship Canal; various land uses are found. Composite
stormwater samples were collected during eight storm events, two storms per
drainage basin. In Basin 6, one stormwater sample was collected during a first
flush event (10/25/86 - a rainstorm following long periods of dry weather) and
the other was collected during a "typical" winter storm event, i.e., during a
nearly continuous wet period. Samples from the other three basins were
collected during two "typical" winter storms. Stormwater samples were analyzed
for the same eleven metals as the storm drain sediments, conventional water
quality parameters, total phenols, oil and grease, cyanides and base/neutral
organic priority pollutants. In cases where not enough stormwater was available
to conduct all analyses, priority was given to metals and nutrients analyses
since these parameters were expected to be encountered in the greatest
concentrations.
Storm Drain Sediment Analyses. Storm drain sediment sampling data is presented
in Table 11. Arsenic, cadmium, chromium, copper, lead, mercury, nickel, zinc
and silver were found in sediments from all drainage basins. Metals
concentrations in storm drain sediments generally exceeded concentrations in
sediments from the bottom of Lake Union and the Ship Canal. This was especiall;
true for lead, nickel, cadmium, copper and zinc.
Sulfide content in sediments has been used as an indicator of conventional
pollutant contamination in Puget Sound studies. Sulfides were detected in only
two sediment samples (Basins 7 and 14) at levels just above detection limits.
Although detection limits varied, it appears that conventional pollutant
problems in storm drains may be limited when compared with concerns about toxic
chemicals.
Oil and grease is an indicator of organic compounds, primarily heavy oils,
animal and vegetable fats and greases; concentrations in the storm drain
sediments ranged from 500 - 28,000 ppm. Samples exhibiting high oil and grease
levels (Basins 2,6,7,14,15) were also analyzed for total petroleum hydrocarbons
to assess the likely sources of the oil and grease. The total petroleum
hydrocarbon analyses showed that the high oil and grease readings were obtained
from long chain hydrocarbons, fats and greases, and/or heavier organic priority
pollutants (e.g., PCBs).
Total organic carbon (TOC) is an indicator of organic compounds including heavy
and lighter oils, organic priority pollutants and soils with organic materials.
TOC concentrations ranged from 1,600 - 89,700 ppm, with only four of the eleven
locations showing concentrations below 10,000 ppm. Both oil and grease and TOC
ranges exceeded concentrations measured in bottom sediments of Lake Union and
the Ship Canal.
Biological oxygen demand (BOD) is an indicator of microbial activity which may
reduce oxygen content of waters and thus affect aquatic life due to oxygen
depletion. BOD concentrations ranged from 220-7600 ppm, exceeding BOD
concentrations in south Lake Union sediment samples at four of the six basins
sampled.
30
-------
TABLE 11
OQNVENTIOWL SEDIMENT QUALITY PAR/DETERS AND MZTAL LEVELS «
IN LAKE UNION AND SHIP CANAL STCRM DRAIN SEDMNTS
BASIN BOD TOC Oil & Gr Tot. S- Arsenic Beryllium Cadmium Ctronium Copper Lead Mercury Nickel Zinc Silver Selenium
NUr-BER LOCATION tig/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg ng/Kg mg/Kg mg/Kg ng/Kg mg/Kg mg/kg
1 N.W. 60th and N\ 20000 M\
-------
BASIN
NUMBER LOCATION
15 9th Ave NW &
NW Fern PL
16 Eastlake Ave
NE & NE Boat
St
19 Broad St &
Hestlake Ave
N
AVERAGES
Storm Drain Sites
S. Lake Union*
Lake Washington2
L. Union/Slip Cnl2
O
Ship Canal
Diwamish River3
McAllister Creek3
BOO TOO Oil & Gr Tot. S-
mg/Kg mg/Kg mg/Kg mg/Kg
5000 29000 24000
1040 6500
223 ]600
500
640
33.8
84
N\
rA
rA
N\
N\
<2.5
<2.5
<1
3843 25232 13518 3.1
2448 98 160 N\
0.69 39.6
1.3 49
fA N\
Arsenic
mg/Kg
66
ID
42
Beryllium Cadmium Chrorrium Copper bead Mercury Nickel Zinc Silver Selenium
mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/k.g
<0.4
0.15
1.7
3.3
0.13 0.42
270 1300 2D 0.32 370 BOO 1.9 <0.4
31 80 450 0.165 ID 350 1.5 <0.6
28 68 340 0.035 21 280 0.54 <0.3
207
30
35.7
124
PA
w\
N\
2.0
tA
137.2
334
0.4
0.8
!A
8.2
0.8
NA
IA
5.6
9.0
<0.1
96
12
34.2
54
48
42.0
13.4
358
85
131.7
343
50.5
95.8
9.2
B52
B6
0.38
2.2
60.9
B7.0
38
0.71
7.6
IA
N\
0.4
0.3
0.02
193
12
fA
[A
46.7
31.9
rA
193 F63 2.4
2D 0.37
IA
2
2.2
IA
2.0
N\
IA
IA
IA
(209)792.T1]A
CO
-------
TABLE 11CONTINJED
INTERIM SEDIMENT BOO TX Oil & Gr Tot. S- Arsenic Beryllium Cadmium Chromium Copper Lead Mercury Nickel Zinc Silver Selenium
QUALITY VALUES mg/Kg mg/Kg mg/Kg rrg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg
Great Lakes ^ ^ N\ ^ ]0 N\ 1.0 DO DO 50 0.1 DO DO N\ N\
Dredged Sediments^
Puget Sound Benthic NA BOCOO M\ N\ 85 >0.5 5.8 59 3D 300 0.88 49 250 5.2 >63
Apparent Effects
Threshold5
N\ = Not Available
Source: Kennedy/Jenks/Chi 1ton. 1987
Sources of comparative data for this table are:
1South Lake Union Pilot Project Report. 1986.
2Galvin, et al. 1984.
^Cain, et al. 1982.
4
Report of the Technical SubcamTittee on Petennination
of Dredge Material Suitability for In-Uater Disposal. 1985.
5Tetra Tech, Inc. 1986.
oo
CO
-------
Stormwater Analyses. Stormwater sampling data is presented in Table 12.
There is higher pollutant loading during a first flush storm than during a
typical winter storm event. For example, conventional pollutant concentrations
were up to six times greater for the first flush event in Basin 6. Metals
concentrations were one to three orders of magnitude greater for the first flush
event when compared with typical winter storm events.
Lake Union drainage basin Stormwater is generally less contaminated than
Stormwater in other cities with populations similar to Seattle. However, as
shown in Table 12, lead and copper concentrations in Stormwater entering Lake
Union and the Ship Canal exceeded acute water quality criteria (for protection
of aquatic life) for all storms. Arsenic, cadmium, zinc and cyanide levels
exceeded acute water quality criteria to a lesser degree, but the first flush
storm accounted for the majority of these exceedances. Therefore, it appears
that lead and copper are the contaminants of concern for long-term degradation
of lake quality and impact on aquatic biota.
Basin 1 (Seaview N.W.) generally exhibited lower concentrations of pollutants in
Stormwater (except for arsenic, cadmium and total dissolved solids) than the
other three basins. Low concentrations of most pollutants may be due to the
lack of industrial sources upstream of the sampling location or because roadways
are not heavily travelled. Pollutant concentrations in Stormwater from Basin 5
(Minor Avenue N.) were similar to other basins. Concentrations of zinc and
total phenols were slightly higher compared with other basins, possibly due to
highway runoff and industrial sources within the basin. Total phosphorus and
lead concentrations were slightly higher in Basin 6 (3rd Avenue N.W.) than in
other basins. Upstream residential sources may account for the elevated levels
of, total phosphorus. High industrial use and heavy vehicle use roads near the
sampling location may account for higher lead levels. Most pollutant parameters
in Basin 9 (Brooklyn Avenue N.E.) were similar to winter storms from other
basins.
Estimates of Mass Loadings. Mass loadings of Stormwater pollutants to Lake
Union and the Ship Canal were estimated, using runoff volumes generated with a
computer model and average concentrations of pollutants in Stormwater samples
obtained during this study. Table 13 presents estimates of total loadings from
all storm drain outfalls in the study area for several water quality parameters,
for both the 10-year storm and average annual discharges. Estimated annual
pollutant loadings from the four basins in which flow monitoring and sampling
were conducted are presented in Table 14. Basin 6 is estimated to discharge the
highest loading per acre of heavy metals; Basin 9 is estimated to contribute the
highest loading per acre of total dissolved solids.
In general, metals concentrations in storm drain sediments were elevated
compared with interim criteria for freshwater and salwater environments
(see Table 11). Although heavy metals from sediments may be continuing to
degrade Lake Union, the relative contribution of storm drain sediments to Lake
Union sediments appears minor. Most basins where sediments were sampled
contained relatively low volumes of sediments which would be available for
transport into the Lake. In addition, Stormwater quality data obtained during
this study indicate low solids concentrations in Stormwater runoff from both the
first flush winter storm and average winter storm.
34
-------
TABLE 12
CONVENTIONAL WVTER QUALITY PAR/METERS AND METAL LEVELS IN
STCRMWVTER DISCHARGED TO LAKE UNION AND THE SHIP
LO
oo
\SIN
JMBEF
1
5
6
9
~eslv/
-eslv/
Col i forms BOD
\ LOCATION r^N/lOOnl mg/1
N.W 60th &
Seaview N.W.
Minor Ave. 1600 22
N. & Fairview
Ave.
3rd Ave.
and N. 36th
St.
Brooklyn Ave.
N.E. & Boat 1600 26
St.
ater Acute Criteria
ater Chronic Criteria
TSS
mg/1
7.3
8.3
150
220
220
51
120
TDS
mg/1
54
230
63
50
76
79
604
Oil &
Grease
mg/1
<2
<2
5.9
7
2.1
3.2
6.8
TKN
mg/l
0.84
0.63
1.9
1.8
1.8
2.9
1.2
3.3
Total P
mg/1
0.14
0.1
0.06
0.04
0.21
0.11
0.01
Arsenic
mg/1
0.01
<0.01
<0.01
<0.01
0.54
0.006
0.002
<0.01
0.36
O.L9
Cadmium
mg/1
0.003
<0.002
<0.0064
0.002
0.13
<0.01
<0.01
<0.0024
0.004
0.001
Chronium
mg/1
0.002
0.005
0.021
0.02
0.11
<0.02
<0.02
0.03
1.70
0.21
Copper
mg/1
0.01
<0.01
0.07
0.09
1.4
0.06
0.02
0.05
0.018
0.012
Lead Mercury
mg/1 mg/1
0.01 <0.0002
<0.01 <0.0002
0.1 0.0006
0.08 0.0003
6 0.0004
0.2 <0.0001
<0.1 <0.001
0.15 0.0004
0.082 0.002
0.003 .000012
Nickel
mg/1
<0.01
0.01
<0.01
<0.01
0.42
<0.05
<0.05
<0.05
1.8
0.096
Zinc
mg/1
0.1
0.04
0.3
0.49
D.I
0.27
0.19
0.31
0.32
0.047
BOD = biological oxygen demand
TSS = total suspended solids
TDS = total dissolved solids
TKN = total Kjeldahl nitrogen
Total P = total phosphorus
] Stomwater samples were collected during two storms per drainage basin; hence two numbers are shown for nust parameters per basin.
Source: Kennedy/Jenks/Chilton. 1987.
209-792.T12
-------
TABLE 13
ESTIMATED TOTAL LOADINGS
FROM STORMWATER DISCHARGE (ALL OUTFALLS)
TO LAKE UNION AND THE SHIP CANAL
Water Quality
Parameter
Halogens
Total Phenols
Average
Concentration
(mg/1)
Total Discharge
(mil lion gallons)
Biological Oxygen
Demand
Total Suspended
Solids
Total Dissolved
Solids
Oil and Grease
Total Kjeldahl
Nitrogen
Total Phosphorus
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Zinc
Total Metals
Total Organic
not applicabli
24
111
165
5.0
1.8
0.10
0.14
0.05
0.03
0.24
1.09
0.0004
0.22
1.47
2.77
0.04
Estimated Total Loading (kg)
10-Year Storm
107.3
9,750
45,100
67,000
2,030
731
41
57
20
12
98
443
0.2
89
597
1,130
16
Medi an Year
1,434
130,300
602,500
895,600
27,150
9,770
543
760
271
163
1,300
5,920
2
1,090
7,979
15 ,040
217
0.009
49
209-792 .T13
36
-------
TABLE 14
ESTIMATED ANNUAL LOADINGS
FROM MONITORED BASIN OUTFALLS
TO LAKE UNION AND THE SHIP CANAL
Water Quality
Parameter
Estimated Total Annual Loading (kg/ac/yr)
Basin 1 Basin 6 Basin 5 Basin 9
(Snip Canal) (Ship Canal) (Lake Union) (Portage Cut)
Total Discharge
(million gallons/
acre/year)
Biological Oxygen
Demand
Total Suspended
Solids
Total Dissolved
Solids
Oil and Grease
Total Nitrogen
Total Phosphorus
Total Heavy
Metals
Total Organic
Halogens
Total Phenols
0.65
0.50
0.54
0.54
NA
19.2
350
NO
1.8
0.29
0.29
NO
0.004
NA
258
14.8
4.0
4.5
0.06
18.2
NA
0.02
45.3
381
117
13.4
3.9
0.06
1.2
0.10
0.03
53.6
247
1,250
0.89
4.7
0.12
0.78
0.02
0.01
Note: ND = Parameter not detected in stormwater from that basin.
NA = Data not available for that basin.
2 09-7 92 .T14
37
-------
Ranking of Basins. In order to establish priorities for future action, the
storm drain basins were ranked based on their relative contributions of
stormwater flow and pollutant loadings to Lake Union and the Ship Canal.
Table 15 indicates the rankings according to percent of annual runoff and
pollutant loading. Based on this data, it appears that efforts to control
stormwater volumes and pollutant loading would be most effective in the larger
basins such as Basins 3 and 5, and in the medium-sized basins which exhibited
the highest pollutant concentrations, including Basins 2, 6, 7 and 9.
Basins 13, 14 and 15 are also good candidates for investigation of source
control actions. Although these basins do not contribute large volumes of
runoff, the sediments from these basins indicate potentially highly concentrated
sources of pollutants.
Followup Source Evaluation/Potential Source Control Measures. A followup source
evaluation is currently underway to determine from which industrial or other
shoreline uses the storm drain contaminants have come. Potential source control
measures that may be feasible for implementation within one or more of the
sub-basins draining into Lake Union and the Ship Canal include: street
sweeping, public education (about potential environmental hazards of disposal of
household chemicals to storm drains), National Pollutant Discharge Elimination
System (NPDES) permits for industrial discharges to storm drains, stormwater
collection system maintenance measures, vigorous enforcement of erosion control
regulations, and surface runoff control measures (e.g., grass swales, ponding
basins).
Lake Union and Ship Canal Outfall Survey (Environmental Intern Program and
Seattle Engineering Department)
In summer - fall 1986, Environmental Intern Program (EIP) volunteers conducted a
boat survey of outfalls discharging into the north end of Lake Union, the north
end of Portage Bay, and the Ship Canal (Figures 5 and 6). One hundred fifty
outfalls were identified and classified by the EIP volunteers as storm drains,
sewer drains, seeps or "other, unidentified". Owners/occupants of land near the
outfalls included the City of Seattle, University of Washington, Seattle Pacific
University, houseboat owners, other home owners, yacht clubs, marinas, shoreline
industries and commercial establishments. The data from the outfall survey will
be evaluated by SED to track sources of runoff into Lake Union and the Ship
Canal. The data will also be included in maps in the application materials for
NPDES storm drain permits.
Combined Sewer Overflow Abatement Planning (Seattle Engineering Department)
In 1985 the Washington state legislature passed a bill requiring dischargers to
prepare and submit by January 1, 1988, plans for achieving "...the greatest
reasonable reduction in combined sewer overflows at the earliest possible
date...". The City has already developed plans for reducing combined sewer
overflows (CSOs) which discharge into Longfellow Creek, Lake Washington and the
recreational saltwater beaches around Alki and Magnolia. The main focus of the
current City CSO planning effort will be on Lake Union and the Ship Canal
(as well as Elliott Bay and the Duwamish).
38
-------
Location of Outfalls Observed
in Lake Union
1/2
-------
Figure 6:
Location of Outfalls Observed in the Ship Canal
Salmon Bay
Waterway
\\
1/2 mi
-------
TABLE 15
RANKING OF STORM DRAIN BASINS BY PERCENT OF
TOTAL ANNUAL RUNOFF AND BY POLLUTANT LOADING
Basin Number
3
5
2
8
9
6
7
10
4 .
11
Connected
Drainage
Area (acres)
635.3
555.4
234.2
230.5
212.4
190
170
104
61
36.5
Percent of
Total Annual
Runoff
22.5
21.0
9.4
8.6
8.1
6.7
6.1
4.7
2.6
2.0
Parameter
Highest Concentrations in Sediments
Metals (lead, nickel,
zinc, arsenic, cadmium) Basins 1, 2, 3, 13, 15
Oil and Grease
TOC
BOD
Basins 7, 14, 15, 2, 6
Basins 6, 7, 14, 15
Basins 6, 14, 15, 2
TDS
Metals
TOX, phenols
Highest concentrations in Stormwater
Basins 1, 9
Basin 1 (arsenic, cadmium)
Basin 5 (zinc)
Basin 6 (lead)
Basin 5
2 09-7 92 .T15
41
-------
The Seattle Engineering Department is developing criteria that will be used in
ranking alternatives for reducing CSO discharges, e.g., complete separation of
sanitary sewage and stormwater, partial separation, storage, transfer, drainage
ordinance modifications, operational modifications, best management practices,
and on-site treatment and discharge. In addition to analyzing costs and bene-
fits of the various CSO reduction alternatives, net pollutant loading and
receiving water sensitivity to CSOs will also be analyzed. Sediment samples
have been taken near several CSO outfalls in Lake Union. The samples are
currently being analyzed for conventional sediment quality parameters (e.g., oil
and grease, total organic carbon), metals and organic priority pollutants. Data
is forthcoming from this task and other tasks that comprise the development of
the City's plan for reducing CSO discharges. For more information on the scope
of the planning effort see Combined Sewer Overflow Plan (1986).
University Regulator CSO Control Project (Metro)
The Greenlake/I-5 University Regulator CSO discharges the largest annual volume
of combined sewage and stormwater to fresh water (Portage Bay) in the Seattle
area. Metro is currently evaluating alternatives for diverting stormwater from
the combined sewer system including: 1) a new storm drain discharging into the
University Slough at Union Bay, and 2) a new storm drain discharging into the
Ship Canal near the 1-5 Bridge. Both of these would involve a significant
reduction in combined sewer overflows at the University Regulator CSO.
Potential water quality impacts as a result of sewer separation include:
1) eutrophication impacts such as changes to algal abundance and effects on
water clarity, 2) microbiological impacts such as changes in indicator organisms
(fecal coliforms) and potential human health effects, and 3) toxicant impacts
such as changes in the concentration of toxic chemicals and potential aquatic
organism effects.
Definition of existing water quality conditions is necessary for impact
assessment with respect to the three types of water quality impacts. Water
quality was sampled biweekly (eleven times) at six sites in the Ship Canal, Lake
Union, and Portage Bays from June through November, 1986. Water was tested for
eutrophication indicators (nutrients, chlorophyll-A, water clarity), the
microbiological indicator (fecal coliforms) and toxicant indicators (metals).
Sediment samples were collected in November, 1986 from eight sites. Sediments
were tested for toxicants (metals and trace organics) and benthic invertebrates.
Summarized below are water quality, sediment chemistry and benthic infauna data
obtained from the sampling sites (see Figure 1 for location of sampling sites).
Water Quality. All six Portage Bay/Lake Union/Ship Canal sites were low in
algae abundance and exhibited moderate to good water clarity (Table 16). All
sites were considered oligo-mesotrophic with respect to chlorophyll-A and
mesotrpphic with respect to Secchi disk transparency.
42
-------
Washington State fecal coliform criteria (50 organisms/100 ml) were exceeded on
at least some sampling dates at all six sites (Table 16), ranging from two out
of eleven sampling dates at the University Regulator CSO site in Portage Bay to
all eleven sampling dates at the Ship Canal site near the Fremont Bridge.
There was an increase in the fecal coliform count in a westward direction.
Since fecal coliform counts at the most downstream sites (Stone Way and Ship
Canal, near Fremont Bridge) were consistently high throughout the summer,
sources other than stormwater or combined sewer overflows might be suspect
(possibly discharge of sewage and bilge from summer boat traffic).
Metal levels were compared with the most recent (1986) EPA water quality
criteria for protection of aquatic life (Table 16). These criteria are defined
for acute toxicity (levels not to be exceeded at any time) and chronic toxicity
(average concentration limits not to be exceeded over a 24 hour period). None
of the metal levels exceeded acute toxicity criteria with the exception of
silver on one sampling date at the University Regulator CSO sampling site.
Silver levels (0.3-4.2 ppb) exceeded chronic toxicity criteria (0.12 ppb) on all
sampling dates at all six sampling sites. This means that silver levels were
high enough to cause long-term adverse health effects to aquatic biota at these
six locations. Zinc levels also exceeded chronic toxicity water quality
criteria (47 ppb) at the Lake Union/Gas Works Park site (64 ppb) on two out of
the eleven sampling dates.
Metal levels were also compared with the most recent (1986) EPA water quality
criteria for protection of human health (Table 16). These criteria are based on
daily drinking of two liters of surface water from a river or stream (minimally
treated non-municipal supply). The nickel level in the water column at the 1-5
Bridge site (15 ppb) exceeded human health criteria (13.4 ppb) on one sampling
date. Arsenic levels (1-6 ppb) exceeded these criteria (0.0022 ppb) at all
sampling sites and on all sampling dates. The human health criteria value
presents the 1 in 1,000,000 risk level for arsenic as a carcinogen; i.e., for
every 1,000,000 people who drink two liters of water daily throughout their
lives with arsenic levels of at least 0.0022 ppb, one person could get cancer.
The 0.0022 ppb level is based on a "standard" human weight of 70 kilograms
(154 Ibs.) and a "standard" human life span of 70 years.
Sediment Chemistry. Conventional sediment quality parameters are presented in
Table 17. All eight sediment sampling sites had total phosphorus values (676.2
- 1176.9 ppm) indicative of "heavily polluted sediments" based on criteria by
Engler (1980). Oil and grease levels (ranging from 2.59 - 4311 ppm) were
highest in the sediment samples from south Portage Bay, Portage Bay near the
Queen City Yacht Club, and Lake Union near the City Light Steam Plant. These
levels were compared with interim criteria developed by the Puget Sound Dredged
Disposal Analysis (PSDDA) Program for unconfined open water disposal of dredged
material in saltwater. Levels at six of the eight sampling sites exceeded the
500 ppm PSDDA "precaution level". At five of these six sites, oil and grease
levels exceeded 1000 ppm, which is the level that requires analysis of dredged
materials for priority pollutants before the materials are approved for
disposal. Total organic carbon (TOC) levels ranged from 2.6 percent at the
University Regulator CSO site to 13.3 percent at the Portage Bay site near the
Yacht Club. TOC levels in sediment samples from all eight sites were below the
15 percent AET value established for Puget Sound sediments.
43
-------
TABLE 16
WATER QUALITY PARAMETERS AND METAL LEVELS!/ IN
PORTAGE BAY, NORTH LAKE UNION AND THE SHIP CANAL
Lake .Union/
Parameter/Metal
Dissolved Oxygen
Surface
10 meters
Conductivity
(umho/cm)
Surface
10 meters
Turbidity (NTU)
r* j? '"' » '
Surface
10 meters
Fecal Coli forms
Surface
Arsenic
(360/190/0.0022)
Cadmium
(3.9/1.1/10)
Chromium
(16/11/50)
Copper
(18/12/NA)
Lead
(82/3.2/50)
Nickel
(1800/96/13.4)
f " T
Sil ver
(4.1/0.12/50)
Zinc
(320/47/5000)
Portage Bay
9.2
(8.7,10.4)
?8,10.4)
94.2
(86,100)
93.6
(87,100)
1.1
(0.9,1.4)
1.4
(1,2.4)
75.1
(2,540)
1.5
(1,3)
0.11
(0.1,0.2)
fa?S,B.B)
?6)
to)
1.8
(1,5)
(6.3,0.6)
J2
(10,22)
uw
Regulator
8.9
(7.7,9.8)
Q Q
O O
7 o o 1 C\ \
(85,100)
?5 8
85,120)
1.1
(1,1.2)
1.1
(0.1,1.4)
28.2
(2,110)
1.3
(1,3)
0.21
(0.1,1.2)
fa!5,4.4)
to.
to)
1.1
(1,2)
(0.3,4.2)
ftfo)
15 Bridge
8.5
(7.9,9.3)
?5?9,9.5)
108.2
(84,180)
116.7
(90.180)
1.1
(0.1,1.6)
1.5
(1.2,1.8)
52.3
(7,240)
1.7
(1,3)
0.16
(0.1,0.7)
(6.5,4.3)
(1,3)
h!i6)
2.4
(1,15)
0.4
(0.3,0.9)
14.5
(10,32)
Gas Works
Park
8.6
(7.2,9.4)
6.6
(1.4,9.9)
158.4
(90,315)
292.8
(96,560)
1.0
(0.1,1.3)
1.4
(1.2,1.8)
170.5
(17,920)
1.6
(1,3)
0.14
(0.1,0.4)
fo.5,4.4)
3.9
(1,10)
h!l2)
1.6
(1,7)
0.4
(0.3,1.1)
24.5
(10,64)
Stone Way
8.4
(7,10)
^2,10.1)
178.3
(91,360)
327.3
(100,640)
1.2
(0.9,1.6)
1.4
(1,1.9)
674.6
(8,2400)
1.8
(1,6)
0.1
(0.1,0.1)
?6?5,2.5)
2.4
(1,3)
to,
1.1
(1,2)
?o!3,1.5)
16.9
(10,35)
Ship
Frem
Bn
8.3
(6.8,
(A,
189.9
(94,3
324.4
(94,8
1.2
(0.9,
1.4
(1.1,
591.8
(70,1
1.75
(1,3.
0.1
(0.1,
$5,
(U)
fa! 10
3.4
(1,13
0.7
(0.3,
14.3
(10,3
All values are expressed as mg/1(ppm) unless otherwise indicated.
NA = not available.
iNumbers in parentheses after each metal represent freshwater criteria for acute
toxicity to aquatic life, chronic toxicity to aquatic life, and human health
protection. For each site, average value is given for July-November 1986 with
the range of observed values in parentheses.
Source: Anderson, et al. 1987-
209-7 92 .T16
44
-------
CONVENTIONAL
TABLE 17
SEDIMENT QUALITY PARAMETERS AND SEDIMENT TOXICANT LEVELS1'2 IN PORTAGE BAY,
NORTH LAKE UNION AND THE SHIP CANAL
Sampling SIte
Parameter
Depth (meters)
Appearance (grain
type, color,
presence of plants,
presence of odor)
Total Phosphorus
Total Oil & Grease
Hydrocarbon Oil
South
Portage
Bay
1.5
silt/mud
grey,
plants
961.5
2969
1246
Portage
Bay near
Yacht Club
7
silt/mud
black,
natural
odor
845.5
3509
1336
University
Regulator
CSO
5
Sand/silt
mud, grey,
plants,
slight
H2S odor
1124.2
329
313
Portage
Bay off
park
4
Silt/mud/
sand, black
1176.9
1492
1492
North
Lake
Union
8
silt/mud/
sand, brown
676.2
886
781
Lake Union
near Steam
Power Plant
6
silt/mud,
black,
petroleum
odor
1133.3
4311
3978
Mid
Lake
Union
12
silt/mud,
black,
natural
odor
1146.7
1213
1213
Ship Canal
at Fremont
12
sand/silt/
mud, black,
slight H2S
odor
841.5
259
259
and Grease
Total Organic
Carbon (%)
Metals
7.6
13.3
2.6
11.6
6.0
4.7
5.5
3.1
Silver (5.2)
Aluminum (NA)
Arsenic (85)
Cadmium (5.8)
Chromium (59)
Copper (310)
Iron (37000)
Manganese(lOOO)
NO
21307.7
12.3
3.1
65.4*
112.3
23076.9
273.8
ND
12727.3
5.5
3.6
39.1
83.6
16363.6
322.7
ND
8032.3
2.4
0.5
25.8
42.7
10387.1
160.3
ND
13076.9
3.8
3.1
46.9
110.8
17538.5
314.6
ND
12619.0
ND
ND
39.0
107.6
17714.3
349.0
ND
13888.9
22.2
3.1
60.0*
280.0
36444.4
477.8
6.7*
27600.0
40.0
4.0
82.7*
346.0*
39866.7
439.3
1.5
17707
51.2
2.2
57.1
199.3
27804.
300.0
.3
9
-------
Sampling Site
Parameter/Toxicant
Metals
Nickel (49)
Lead (300)
Tin (NA)
Zinc (260)
Polycyclic
Aromatic
Hydrocarbons
Fluorene (6.40)
Naphthalene (2.10)
Acenaphthene (0.50)
Acenaphthylene (0.64)
Anthracene (1.30)
Phenanthrene (3.20)
Fluoranthene (6.30)
Pyrene (7.30)
Chrysene (6.70)
Benzo (a) anthracene
South
Portage
Bay
69.2*
230.8
ND
334.6*
ND
ND
ND
ND
ND
0.37
0.61
0.72
0.31
0.21
Portage
Bay near
Yacht Club
45.5
254.5
ND
187.3
0.04
ND
ND
ND
ND
0.43
0.77
0.90
0.34
0.32
University
Regulator
CSO
30.6
122.6
ND
86.3
0.03
ND
0.03
ND
0.06
0.26
0.36
0.36
0.18
0.14
Portage
Bay off
park
46.2
423.1*
ND
273.1*
ND
ND
0.11
ND
0.30
1.5
2.7
2.6
1.1
0.83
North
Lake
Union
(near 15)
42.9
261.9
ND
227.1
2.5
ND
1.7*
1.1*
8.4*
15.9*
1.9
19.7*
8.4*
6.8*
Lake Union
near Steam
Plant
208.9*
1108.9*
ND
822.2*
0.77
0.77
ND
ND
1.2
5.1*
7.2*
6.9
3.3
2.3
Mid
Lake
Union
80.0*
680.0*
ND
572.7*
0.45
0.82
0.70*
0.73*
0.77
2.3
5.8
6.9
2.5
2.0
Ship Canal
at Fremont
B ri d ge
51.2*
414.6*
ND
358.5*
11.1*
11.6* *
18.1*
0.78*
6.5*
23.4*
20.6*
18.7*
7.2*
6.1*
(4.50)
209-792.T17A
-------
TABLE 17 (CONTINUED)
Sampling Site
Polycyclic
Aromatic
Hydrocarbons
Benzo(a)pyrene
(6.80)
Benzo(b)fluoranthene
(8.00)
Benzo(k)fluoranthene
(8.00)
lndeno-1,2,3-
CD-pyrene (5.20)
Dibenzo(a,h)-
anthracene (1.20)
Benzo(g,h,i)perylene
(5.40)
Polychlorinated
South
Portage
Bay
ND
ND
ND
ND
ND
ND
ND
Portage
Bay near
Yacht Club
0.38
0.27
0.39
ND
ND
ND
ND
University
Regulator
CSO
0.15
0.12
0.16
0.13
0.03
0.14
0.44
Portage
Bay off
park
1.1
1.2
1.1
1.1
0.23
1.1
0.09
North
Lake
Union
6.6
10.3*
5.9
3.1
0.72
4.7
ND
Lake Union
near Steam
Plant
2.4
3.3
3.5
ND
0.68
2.0
ND
Mid
Lake
Union
3.3
2.7
2.9
2.2
0.73
3.1
ND
Ship Canal
at Fremont
B ri d ge
5.5
7.4
8.3*
4.8
0.46
6.1*
ND
i
Biphenyls (total)
(1.10)
Three replicates from each sampling site were composited, completely mixed, subsampled and analyzed.
^Levels are expressed as mg/kg (ppm) dry weight unless otherwise noted. ND = Not Detected. NA = Not Available.
^Interim benthic apparent effects threshold (AET) values for Puget Sound sediments are given in parentheses for
each toxicant. Asterisked numbers are those that exceed benthic AETs.
Source: Anderson, et al. 1987.
-------
Results of sediment metals analyses are shown in Table 17. Twelve metals were
tested; aluminum, arsenic, cadmium, chromium, copper, iron, manganese, nickel,
lead and zinc were found consistently in most samples. Tin was not detected in
any of the samples; silver was not detected in 85% of the samples.
Sediment sites ranged from relatively clean to heavily contaminated. The
existing University Regulator CSO site ranked lower in concentration than most
other sites for most parameters. In comparison, the potential stormwater
discharge site in the Ship Canal at the 1-5 bridge had consistently higher
concentrations for most parameters. The mid-Lake Union site was generally the
highest in concentration for most metals; interim benthic AET values for Puget
Sound sediments were exceeded here for silver, chromium, copper, nickel, lead
and zinc. Nickel, lead and zinc levels exceeded benthic AETs for Puget Sound
sediments in samples from the Ship Canal near the Fremont Bridge and Lake Union
near the City Light Steam Plant. Chromium levels also exceeded the benthic AET
at the City Light Steam Plant site. None of the metal levels exceeded benthic
AETs at any of the Portage Bay sites (with the sole exception of chromium levels
in south Portage Bay sediments).
Results of trace organics analyses are also shown in Table 17. Thirty trace
organic compounds were found, primarily PAHs, PCBs and phthlalate esters
(plasticizers). Portage Bay sampling sites (including the University Regulator
CSO site) had lower concentrations of trace organics than Lake Union and
downstream Ship Canal sampling sites. The sampling site in the Ship Canal at
the Fremont Bridge had the largest number of organic compounds and generally the
highest concentrations. Twelve out of sixteen PAHs were found here at levels
exceeding benthic AETs for Puget Sound sediments. The potential new storm drain
discharge site near the 1-5 bridge also had high concentrations of PAHs, in some
cases similar to those at the Ship Canal/Fremont Bridge site. Nine out of
twelve PAHs were found here at levels exceeding benthic AETs for Puget Sound
sediments. No PAHs were found at levels exceeding benthic AETs at any of the
Portage -Bay sampling sites. Since PAHs are formed by incomplete combustion of
fossil fuels, (e.g., coal used in the gasification process at the former Seattle
Gas Plant), it is not surprising to find higher levels of PAHs in areas
downstream from Gas Works Park.
In the absence of established criteria for health hazards in freshwater caused
by contact with polluted sediments, it is difficult to interpret the meaning of
the sediment chemistry data other than that there are relatively clean sediments
in Portage Bay and heavily contaminated sediments in the tested areas in Lake
Union and the Ship Canal. EPA's proposed benthic AET values for Puget Sound
sediments were used for comparative purposes to determine which sediment sites
were heavily contaminated. Benthic AET values have not been proposed for
fresh-water sediments. The Puget Sound numbers may or may not be applicable to
Lake Union benthic infauna. Furthermore, sediment toxicant levels below the
Puget Sound benthic AET values are not necessarily "safe" for Lake Union benthic
infauna.
As indicated in an earlier section of this report, Yake et al. (1986) found that
heavily contaminated sediments from Lake Union were toxic to a freshwater
amphipod species. Sediment metal concentrations documented for the University
Regulator CSO Control Project are similar to the concentrations found by Yake,
et al., but PAH concentrations reported by Yake et al. were two to three orders
of magnitude higher than detected in the University Regulator CSO Control
Project sediment samples.
48
-------
Benthic Infauna. Table 18 presents mean total abundance (animals/m2 of sediment
from three replicates) and species richness (number of taxonomic groups/sampling
site) of benthic infauna at each of the eight sediment sampling sites, and the
ten most abundant taxonomic groups for all sampling sites. The University
Regulator CSO outfall site and the south Portage Bay site had the highest
abundance of benthic infauna (12,613 and 46,884 animals respectively); the
mid-Lake and Ship Canal/Fremont Bridge sites had the lowest abundance (588 and
1319 animals respectively). Possible factors contributing to the greater
abundance of animals in Portage Bay sediments are relatively low sediment
toxicant levels and shallow sampling sites (Table 17). There may be less
saltwater intrusion and higher DO levels at shallow sites (Table 13).
Conversely, possible factors contributing to the relative paucity of animals in
mid-Lake and Ship Canal sediments are: relatively high sediment toxicant levels
and deep sampling sites (Table 17); there may be greater saltwater intrusion and
lower DO levels at the deeper sites (Table 16).
Species richness showed the same trend as total abundance, i.e., more taxonomic
groups were found in Portage Bay sediments than in Lake Union or Ship Canal
sediments. Average species richness ranged from 3.7 groups at the Ship
Canal/Fremont Bridge site to 22.3 groups at the Portage Bay/Yacht Club site
(Table 18). In addition to members of taxonomic groups, types of animals also
varied among sampling sites: Lake Union and Ship Canal sites were dominated by
oligochaetes as was the case with the south Lake Union sites described earlier
in this report. Taxonomic group differences were apparent between the existing
CSO site and the potential stormwater discharge site at the 1-5 Bridge. The
existing CSO site tended to have more pollutant-tolerant groups.
Gas Works Park Groundwater Analysis Program (Seattle Parks Department and U.S.
Geological Survey)
This program was designed to determine if groundwater under and around Gas Works
Park is contaminated with toxic chemicals (from the former Seattle Gas Plant)
and is migrating into Lake Union. In summer 1986, a seismic refraction survey
was conducted to obtain data on the geohydrologic setting of the park, e.g.,
soil types and water table location. This data was used to determine where to
drill test wells. In fall 1986, sixteen test wells were drilled (fifteen wells
in Gas Works Park and one well outside the Park boundary) and groundwater
samples were collected. Results of the groundwater analyses will be available
in spring 1987. Parameters measured at all wells include: water temperature,
pH, DO, conductivity, and levels of cyanide, PAHs and metals (arsenic,
beryllium, boron, cadmium, chromium, copper, lead, mercury, nickel, selenium,
silver, zinc). Groundwater samples obtained from six of the wells inside the
Park and the one well outside the park will also be analyzed for pesticides,
PCBs and volatiles (monoaromatic hydrocarbons such as benzene).
209-792.1-.23
49
-------
Sampling Site
Total Abundance
(animals/m2)
Species Richness
(number of taxonomic
groups)
South
Portage
Bay
46,884
17.33
Portage
Bay near
Yacht Club
7,410
22.33
University
Regulator
CSO
12,613
14.67
Portage
Bay off
park
6,364
17.67
North
Lake
Union
3,827
15.33
Lake Union
near Steam
Plant
5,805
9.67
Mid
Lake
Union
588
3.67
Ship Canal
at Fremont
B ri d ge
1,319
7.33
Ten most abundant taxonomic groups (all sites combined):
Rank Taxonomic groups
1. Nematoda
2. Ostracoda
3. Oligochaetes
(immature with bifids)
4. Pisidium
5. Chironomus
6. Procladius
7. Asellus racovitzai
8. Hyatella azteca
9. Oligochaetes (immature
with hairs and pectinates)
10. Limnofrilus hoffmeisteri
Other Names
Nematode, roundworm
Water "flea"
Aquatic earthworm
Freshwater clam, pelecypod
Two-winged fly, chironomid
Two-winged fly, chironomid
Isopod
Amphipod, shrimp
Aquatic earthworm
Aquatic earthworm, tubificid
ifienthic infauna values represent means of three replicates. Samples were sieved through a 0.25mm sieve.
Source: Anderson, et al. 1987.
209-792.T18
o
tn
-------
LITERATURE CITED
Anderson Dale, Tom Belnick, Andrea Copping, Deedee Kathman and Steve Cross.
I987- University Regulator CSO Control Predesign. Technical Memorandum No.
204-1 (Draft). Prepared for Metro and Seattle Parks Department, Seattle,
Washington.
Auer, Nancy A. and Martin T. Auer. 1986. An in-site and laboratory evaluation
of barriers to walleye egg and larva survival in the lower Fox River, Wisconsin.
Transactions of the American Fisheries Society (in press).
Barnes, Robert D. 1980. Invertebrate Zoology. W. B. Saunders Company,
Philadelphia, Pennsylvania.
Combined Sewer Overflow Plan. 1986. Prepared for the City of Seattle by Brown
and Caldwell.Agreement No. 586-110.
Engler, C.M. 1980. Prediction of Pollution Potential Through Geochemical and
Biological Procedures. In: R. Baker (ed.), Contamination and Sediments, Vol.
I, Ann Arbor Science, Ann Arbor, Michigan.
Freshwater Assessment Reports. 1986. Municipality of Metropolitan Seattle,
Seattle, Washington.
Frost Floyd, Jane Lee and Mary McCallum. 1985. Analysis of Chemical
Contaminants in Lake Union and Lake Washington Crayfish.Report to the
Seattle-King County Health Department, Seattle, Washington.
Galvin, David V., G. Patrick Romberg, Douglas R. Houck and John H. Lesniak.
1984. Toxicant Pretreatment Planning Study Summary Report. Municipality of
Metropolitan Seattle, Seattle, Washington.
Gardiner, Robert D., Martin T. Auer and Raymond P. Canale. 1984. Sediment
oxygen demand in Green Bay (Lake Michigan). In: M. Pirbazari and J.S. Devinny
(eds.), Proceedings of the 1984 Specialty Conference on Environmental Engineers,
American Society of Civil Engineering, New York, New York.
Kennedy/Jenks/Chilton. 1987. Lake Union and Ship Canal Storm Drain Sediment and
Analysis Program. Prepard for Seattle Engineering Department (Draft Report).
McCain, Bruce B., Mark S. Myers, Usha Varanasi et al. 1982. Pathology of Two
Sjecies of Flatfish from Urban Estuaries in Puget Sound. National Marine
Fisheries Service, National Oceanic and Atmospheric Administration, Seattle,
Washington (includes Lake Washington Ship Canal).
Price, Michael. 1978. The Role of South-Central Puget Sound as a Public Food
Source: Impact of Heavy Metals.Final Technical Report.National Science
Foundation Student Originated Studies Grant #SM177-05257. Evergreen State
College, Lacey, Washington.
Report of the Technical Subcommittee on Determination of Dredge Material
Suitability for In-Water Disposal. 1985. Wisconsin Department of Natural
Resources, Madison, Wisconsin.
51
-------
South Lake Union Pilot Project Report. 1986. Land Use and Transportation
Project, City of Seattle Executive Department, Seattle, Washington.
Tetra Tech, Inc. 1986a. Application of Selected Sediment Quality Value
Approaches to Puget Sound Data. Prepared for Resource Planning Associates for
U.S. Army Corps of Engineers, Seattle District (Draft Report).
Tetra Tech, Inc. 1986b. Recommended Protocols for Sampling and Analyzing
Subtidal Benthic Macroinvertebrate Assemblages in Puget Sound. Prepared for
U.S. Environmental Protection Agency, Seattle, Washington.
Yake, Bill, Dale Norton and Margaret Stinson. 1986. Application of the Triad
Approach to Freshwater Sediment Assessment: An Initial Investigation of
Sediment Quality Near Gas Works Park, Lake Union. Washington Department of
Ecology, Olympia, Washington.
52
-------
GLOSSARY
Algae Aquatic, nonflowering plants that lack roots and use light energy to
convert inorganic nutrients such as nitrogen and phosphorus into organic matter
by photosynthesis. Algal bloom can occur when excessive nutrient levels and
other water conditions enable the algae to reproduce rapidly.
Amphipod Mortality Test A bioassay procedure in which amphipods (a large
group of crustaceans composed of sand fleas and other related forms of animals)
are exposed to various concentrations of sediments and percent mortality is
measured.
Apparent Effects Threshold The concentration of a toxicant above which
statistically significant biological effects are observed, based on synoptic
field data.
Benthic Infauna The benthic invertebrates that live beneath the sediments.
Bioassay A laboratory test using a response of a test plant or animal (e.g.,
its growth or death) to measure the effect of a physical, chemical or biological
variable.
Biota The animal and plant life of a particula region.
Chemical Oxygen Demand (COD) The quantity of oxygen-demanding chemical
materials present in a sample as measured by a specific test. COD is defined as
a conventional pollutant under the Federal Clean Water Act.
Coliform Bacteria ~ A type of bacteria which includes many species. Fecal
coliform bacteria are those col i form bacteria which are found in the intestinal
tracts of warm-blooded animals. The presence of high numbers of fecal coliform
bacteria in a water body can indicate the release of untreated sewage, and/or
the presence of animals, and may indicate the presence of pathogens.
Combined Sewer Overflow (CSO) A pipe that discharges untreated wastewater
during storms, from a sewer system that carries both sewage and stormwater. The
overflow occurs because the system does not have the capacity to transport and
treat the increased flow caused by stormwater runoff.
Conductivity The property of conducting (transmitting) electricity. In the
case of Lake Union, there is a positive correlation between conductivity and
salinity of the Lake bottom. Hence, high conductivity reflects high saltwater
intrusion into the Lake.
Conventional Pollutant -- One of the pollutants specified under the Federal
Clean Water Act. The list includes total suspended solids, coliform bacteria,
BOD, COD, pH, and oil and grease.
Dissolved Oxygen (DO) -- Oxygen which is present (dissolved) in water and
therefore available for fish and other aquatic animals to use. If the amount of
dissolved oxygen in the water is too low or zero, then exposed aquatic animals
will die.
Gram A unit of weight in the metric system, 454 grams = 1 pound and 28.4
grams = 1 ounce.
53
-------
Groundwater -- Underground water supplies, created by rain which' soaks into the
ground and flows down until it is collected at a point where the ground is not
permeable. Groundwater then usually flows laterally toward a lake, river or the
ocean.
Interstitial Water Water that is found in between sediment particles.
Mesotrophic Moderately transparent, with moderate levels of algae and algal
nutrients. This term is used in reference to lakes.
Microgram -- One-one millionth (1/1,000,000) of a gram.
Milligram One-one thousandth (1/1,000) of a gram.
Organic Chemical A chemical that contains carbon.
Polychlorinated Biphenyls (PCBs) -- A group of ubiquitous, environmentally
persistent chlorinated hydrocarbons (between 12% - 68% chlorine). PCBs were
formerly used in insulating fluids in capacitors and transformers, in the
plastics industry, and in hydraulic fluids and lubricants. PCBs can cause
cancer. They have caused birth defects in laboratory animals and are believed
to be capable of causing birth defects in humans also.
Polycyclic Aromatic Hydrocarbons (PAHs) (sometimes called polynuclear aromatics
or PNAs) -- Many-ringed organic chemicals containing carbon and hydrogen. They
are formed as a result of incomplete combustion of organic materials, e.g.,
coal, coke, wood, tobacco. Some PAHs can cause cancer.
r
ppm Parts per million; 1 ppm of a chemical means 1 gram of that chemical in
every 1,000,000 grams (1,000 liters) of water.
ppt Parts per thousand; 1 ppt salinity means 1 gram salt in every 1,000 grams
(1 liter) of water. The concentration of dissolved salt in seawater is 35 ppt.
Priority Water Pollutants -- 126 toxic water pollutants so designated by EPA
under the Federal Clean Water Act because they have several of the following
properties: 1) demonstrated ability to kill aquatic organisms; 2) cause cancer;
3) ability to bioconcentrate; 4) environmentally persistent; 5) ubiquitous;
6) volume of production or use by industry; 7) capability of analytical
detection. The list includes metals, asbestos, cyanide, and organic
(carbon-based) chemicals such as PCBs, PAHs, and pesticides.
Reference Site A "control site" in an environmental study. The reference
site (e.g., a pristine lake) has similar characteristics to the test site but
has not been subjected to human activities that cause water pollution.
Sediment -- Material suspended in or settling to the bottom of a liquid. As
used here, it refers to the sand and mud that makes up much of the shorelines
and bottom of Lake Union/Ship Canal.
54
-------
Specie^ Diversity A measure of the number and types of species found in a
particular community of plants and animals, e.g., a benthic community. Species
diversity can be an indicator of pollution. Benthic communities in highly
polluted sediments may show less species diversity than benthic communities in
nonpolluted sediments.
Storm Drain A system of gutters, pipes, or ditches used to carry stormwater
from surrounding lands to streams, lakes, or Puget Sound. Often carries a
variety of substances such as oil and antifreeze which enter the system through
runoff, deliberate dumping, or spills. This term also refers to the end of the
pipe where the stormwater is discharged.
Stormwater Water that is generated by rainfall and is often routed into drain
systems in order to prevent flooding.
Synoptic Presenting or involving data from the same point of view. In this
study it refers to chemical and biological data from the same sediment sample.
Taxonomic Group A group of plants or animals with common structural features
and biological characteristics.
Toxicant -- A chemical that poses a risk of producing an adverse biological
effect or in some way damaging a living organism.
Turbidity A measure of the amount of material suspended in the water.
Increasing the turbidity of the water decreases the amount of light that
penetrates the water column. High levels of turbidity are harmful to aquatic
life.
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ACKNOWLEDGEMENTS
CITY OF SEATTLE
Charles Royer, Mayor
OFFICE FOR LONG-RANGE PLANNING
Richard Yukubousky, Director
PARTICIPATING STAFF
Clifford Marks
Frances Solomon
GRAPHIC DESIGN AND PRODUCTION
Joan Schlichting
Steve Walker
ADMINISTRATIVE SUPPORT
Bonita Chinn
Heather Ruck
Mary Simmons
209-792.27
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