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1 Introduction
1.1 Integrated Cook Inlet Environmental Monitoring and
Assessment Program (ICIEMAP)
This report integrates and summarizes data from several studies that were coordinated through a
unique set of partnerships, leading to combined field efforts to survey chemical, biological and
physical parameters in Cook Inlet in 2008 and 2009. Much of the effort was directed to
understanding the diversity of the Inlet, a complex and highly dynamic environment, but also
assessed potential impacts by certain oil production operations in the upper Inlet. These efforts
comprised a unique example of cooperation, coordination and leveraging of resources in forming
an Integrated Cook Inlet Environmental Monitoring and Assessment Program (ICIEMAP).
Sponsors of all four projects uniquely agreed to combine logistics and costs, allowing the sharing
and reporting of the results presented in this report. Components of ICIEMAP include:

Cook Inlet area-wide study based on the national Environmental Monitoring and
Assessment Program (EMAP) to measure water column parameters and benthic health in
Cook Inlet and, separately, in oil-industry-operation areas.

produced-water-discharge study designed to fulfill the requirements of the Environmental
Protection Agency’s (EPA) Cook Inlet Oil and Gas NPDES Permit (AKG-31-5000) that
required certain operators discharging large volumes of produced water to assess the fate
and transport of pollutants in the water column and sediments.

portion of a National Oceanic and Atmospheric Administration (NOAA), National Status
& Trends (NS&T) study to assess measures of water column and benthic health at a
series of deep stations in Kachemak Bay to extend a much more detailed study that had
been conducted in shallow areas of the bay in 2007.

background river study to measure contaminant loads (metals and hydrocarbons) entering
Cook Inlet from the larger freshwater rivers draining watersheds into the larger Cook
Inlet.
ICIEMAP began when Cook Inlet Regional Citizens Advisory Council’s (CIRCAC) developed a
project to survey the benthic and water column environments in Cook Inlet using a stratified
probabilistic survey design that would allow comparisons of oil industry areas with the rest of
Cook Inlet. The plan was to sample using the EMAP protocols so that Cook Inlet data would be
comparable with other Alaskan EMAP program results.
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Shortly after CIRCAC received funding from NOAA’s Office of Restoration & Response for the
EMAP study, EPA released a National Pollution Discharge Elimination System (NPDES) permit
requiring certain oil industry operators to conduct a produced-water, fate-and-transport study of
discharges from their treatment facilities. Since both studies had shared objectives and would be
measuring similar parameters within the same region, CIRCAC worked with Chevron and XTO
Energy through their contractors at Kinnetic Laboratories, Inc. to develop a plan that integrated
and facilitated both studies by leveraging logistical, sampling, and analytical costs. The
cooperative agreement included data sharing to provide a more comprehensive context in which
to interpret the data; a windfall for both studies considering their limited funds.
In the process of developing ICIEMAP, two smaller projects were incorporated into the plan. In
2007, the North Pacific Research Board and NOAA NS&T co-funded a study to assess habitat
conditions that influence biodiversity and distribution of soft-bottom, benthic invertebrate
communities in Kachemak Bay. The study design stratified by depth, as well as from east to
west along the axis of Kachemak Bay. In 2007, all shallow stations were sampled. When the
project lost second-phase (2008) funding, the ICIEMAP incorporated sampling at 5 of their deep
stations in inner Kachemak Bay. Assisting their program benefited ICIEMAP since the
probabilistic site selections for the Cook Inlet EMAP and the NPDES Permit sampling had not
selected any sites for inner Kachemak Bay, although the Bay had been included in the sampling
strata.
The last project incorporated into the ICIEMP was a sampling program to measure contaminant
concentrations in rivers entering the Cook Inlet marine environment from many of the major
river systems. While the sampling for the other programs took place mainly in 2008, the river
sampling was completed during two sampling trips in 2009.
More details for each individual study are provided below and specific methods are outlined in
Chapter 2. The data for all studies are incorporated together in the results chapters. Some
statistical analyses do not incorporate the additional sites (oil facilities and rivers) as they were
systematically selected and not intended for inclusion in the stratified, probabilistic survey
design (described in further detail in Chapter 2).
1.2 Cook Inlet Environmental Monitoring and Assessment Program
(EMAP)
One component of the integrated study, a Cook Inlet Environmental Monitoring and Assessment
Program (EMAP), was designed to compare ecosystem health among Inlet marine waters, Cook
Inlet oil-industry areas, and the largest mixing zones associated with the NPDES-permitted,
large-volume dischargers. The study helps fulfill CIRCAC’s requirements in their founding
legislation, the Oil Pollution Act of 1990 (OPA 90) which tasks them with “devising and
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managing a comprehensive program of monitoring the environmental impacts of the operations
of terminal facilities and of crude oil tankers while operating in Cook Inlet.” A brief history of
CIRCAC contaminants-monitoring projects leading up to the current Cook Inlet EMAP program
follows.
In response to OPA 90, CIRCAC initiated steps to develop and manage a comprehensive
environmental monitoring program for Cook Inlet, beginning in 1991. The goal of the program
was to determine if oil-industry operations in Cook Inlet were having adverse effects on the
surrounding ecosystem and, if so, to document their sources, magnitude, and spatial and
temporal trends. Based on a 1992 model recommended by contractors (MBC 1992), a pilot
study in 1993 provided data to evaluate needs for a longer-term environmental monitoring
program. Additional environmental monitoring studies were conducted in 1994, 1995, 1996, and
1997 (ADL 1995a, 1995b; Kinnetic Laboratories Inc. 1996a, 1996b, 1997, 1998) that used
modified, sediment-quality-triad (SQT) designs to assess sediment contaminants, sediment
toxicity, and biological indicators of stress.
In 1998, CIRCAC contracted with Littoral Ecological and Environmental Services (LEES) to
compile a summary technical report and database that included an evaluation of the monitoring
program to date and recommendations for future environmental monitoring. The resulting
summary report stated that based on the overwhelming weight of evidence from the many
aspects of the sampling program, hydrocarbon contamination was either lacking or, if observed,
occurred at close to background levels or near the levels of detection for the particular method
((Lees et. al. 1999). The bulk of the samples and analyses were for subtidal sediments collected
upstream, nearby, and downstream of oil-industry discharge. The limited number of intertidal
samples collected downstream of the discharges also showed that hydrocarbons were not
accumulating in bivalves living in or on the substrate. A qualitative ecological risk assessment
was used to evaluate and focus the monitoring program. Based on that analysis, it appeared that
dilution by the receiving water brought the concentrations of potential chemical stressors from
daily discharges low enough that the exposure route to organisms is interrupted in areas outside
of the mixing zones. However, the researchers recommended that a combination of periodic
evaluation of benthic subtidal habitats and intertidal baseline data collections will continue to be
necessary both to ensure that future potential impacts would be detected and to alleviate public
perception and concern focused on industry discharges.
In 2002 and 2004, CIRCAC partnered with the Alaska Department of Environmental
Conservation (DEC) to conduct a Coastal Assessment of the Gulf of Alaska’s coastal bays and
estuaries by looking at a suite of contaminants in benthic sediments and organisms. The study
design was based on EMAP’s probabilistic survey design (EPA, 2001) which allows “scalingup” from a suite of 50 sampling sites in the western Gulf of Alaska and 40 sites in Southeast
Alaska. The value of these coastal Gulf of Alaska data to CIRCAC is that they can provide a
context in which to interpret and compare the more focused studies required by OPA 90 by
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providing background signals and providing information for areas “upstream” and “downstream”
of Cook Inlet oil industry operations. The Cook Inlet EMAP study portion of the ICIEMAP used
a similar probabilistic survey design. While the initial 2002 Alaska EMAP program sampled at
several locations within Cook Inlet, the 2008 program was designed to sample only Cook Inlet
and with a more comprehensive effort. As previously mentioned, the current objectives were to
obtain background information about Cook Inlet’s benthic sediment environments while also
evaluating the potential impacts to that environment by oil industry operations in upper Cook
Inlet.
While the national EMAP program was established and funded by the Environmental Protection
Agency (EPA), partnerships have been necessary to carry out projects within each state. The
Alaska component of EMAP is administered by the Alaska Department of Environmental
Conservation (DEC) under their Alaska EMAP (AKMAP). Through a Memorandum of
Agreement with the DEC, Cook Inlet RCAC provided the scientific lead for the development of
the coastal EMAP program in Alaska and provided a Chief Scientist for the field studies
conducted in the Gulf of Alaska in 2002 and 2004, including sites in Cook Inlet (Saupe et. al.
2005).
Basing ICIEMAP on EMAP protocols allows the data to be incorporated into the larger regional
AKMAP efforts, thus providing regional perspectives at various spatial scales. Contaminants
data provided by AKMAP includes metals, hydrocarbons, and persistent organic pollutants for
sediments in the Gulf of Alaska’s coastal bays and estuaries, including Cook Inlet, as well as
measures of water quality. Most prior coastal monitoring efforts in the Gulf of Alaska had been
associated with specific areas or point sources such as NPDES-permitted discharges, assessing
effects of oil spills, or monitoring associated with potential oil and gas activities. Those projectspecific sampling efforts have typically been spatially restricted and, thus, limited in their ability
to interpret the localized results in the context of a broader regional perspective.
1.3 Produced Water Discharge Study
On 2 July 2007, the EPA-issued permit number AKG-31-5000, Authorization to Discharge
Under the NPDES for Oil and Gas Extraction Facilities in Federal and State Waters in Cook
Inlet, became effective. This permit governs the discharge of 19 types of water, wastewater, and
process-related fluids incidental to product extraction, treatment, and conveyance. The permit
stipulates effluent limitations, recording and reporting requirements, monitoring requirements,
and prohibitions, as well as other conditions. Relevant to this project, a new requirement
specifies a study to address the fate and transport of pollutants from large-volume dischargers of
produced water. This new permit requirement is described under section V titled “Produced
Water Discharge Study Requirements” and includes the following specific language:
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A. Produced Water Discharge Study. Operators discharging greater than 100,000
gallons per day of produced water shall plan and conduct a single study that addresses
the fate and transport of pollutants in the water column and sediments.
B. Objectives. The overall objective of the study is to evaluate contaminant fate and
transport from large volume produced water dischargers. This can be accomplished by
statistically comparing contaminant concentrations at the discharge point with
concentrations at distances from the discharge point (transport) and evaluating the
accumulation of contaminants in Cook Inlet’s water column and/or sediments (fate).
C. Schedule. Within six months of the effective date of this permit, permittees shall
submit a study plan to EPA Region 10 for approval. The final report shall be submitted to
EPA within three years after the effective date of the permit.
D. Requirements. The plan must address a monitoring approach that:
1. Can statistically evaluate the potential accumulation of discharge contaminants
in Cook Inlet through a combination of total concentration analysis and
fingerprinting;
2. Includes dissolved and total recoverable metal and hydrocarbon concentration
analyses that can statistically compare discharge concentrations with receiving
water concentrations with distance from the discharge point;
3. Evaluates and provides justification for including or excluding contaminants
measured in the dissolved and/or total recoverable phase; in the water column
and/or benthic sediments; and,
4. May include a phased study design, with detailed analyses of archived samples
following initial screening-level analyses for some or all parameters.
The permit fact sheet described the need for this study as follows:
Because of the data limitations, EPA has historically relied on tools such as dispersion
modeling to analyze the potential effects of discharges to make permitting decisions. To
increase available ambient data and ensure that future permit decisions are based on
more representative information, the Proposed Permit requires new fate and effects
monitoring for large volume produced water discharges.
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By cooperative agreement, the ICIEMAP replaced oil industry’s proposed study submitted to
EPA on 31 December 2007. The ICIEMAP addressed the fate objective through comparisons of
local sediment and water-column metals and hydrocarbons to the produced water source (before
discharge) and by comparing the Mixing Zone area data to the larger industrial area data to the
overall Cook Inlet data (described in Chapter 2). Sediment and water column samples were
taken within the mixing zones and in the areas surrounding the mixing zones to assess pollutant
concentrations as a function of distance from the discharge. A combination of dissolved,
particulate, and total concentrations, in addition to fingerprinting, were utilized for this purpose.
The transport study didn’t occur until 2009, after placement of a diffuser at the end of the
Trading Bay Treatment Facility’s discharge pipe. The results from that component of the study
are not yet finalized and will be described and presented as a separate report to EPA.
1.4 National Status and Trends (NS&T) Bioeffects Study for
Kachemak Bay Deep Stations
In 2007, prior to ICIEMAP, NOAA’s NS&T program conducted a baseline environmental
characterization of inner Kachemak Bay using the sediment-quality-triad approach based on
sediment chemistry, sediment toxicity, and benthic invertebrate, community structure. The study
area was subdivided into 5 strata based on geophysical and hydrodynamic patterns in the Bay,
using a stratified random statistical design approach. In addition, several sites near the village of
Port Graham and in the footprint of a proposed Homer Harbor expansion were also collected for
comparison. Concentrations of over 120 organic and metallic contaminants were analyzed,
ambient toxicity was assessed using two amphipod bioassays, and detailed benthic-communitycondition assessments were performed. Additional habitat parameters (depth, salinity,
temperature, dissolved oxygen, sediment grain size, and organic carbon content) that influence
species and contaminant distribution were also measured.
The 2007 data showed that sediments were mostly mixed silt and sand, characteristic of high
energy habitats, with pockets of muddy habitat. Persistent organic pollutants were detected
throughout the Bay but at relatively low concentrations. With few exceptions, metal
concentrations were relatively low and probably reflect the input of glacial runoff. Homer
Harbor sites were shown to have elevated metal and organic contaminants relative to the rest of
Kachemak Bay, although it is a deeper, lower energy, depositional environment with finer
grained sediments than elsewhere in the study area. Infaunal assessments showed a diverse
assemblage with more than 240 taxa recorded and abundances commonly greater than 3,000
animals m-2. Benthic community assemblages were distributed based on depth and water clarity
while significant toxicity was virtually absent.
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But the 2007 study did not include samples from the deepest areas of Kachemak Bay. When
funding did not come through to sample those deeper stations, ICIEMAP incorporated five deep
Kachemak Bay stations into their sampling plan since most of the parameters measured in the
NS&T study overlapped with those measured by the ICIEMAP. These sites supplement both the
data collected during the 2007 NS&T study and the Cook Inlet area wide EMAP portion of the
ICIEMAP collected during 2008. The five stations sampled were from areas deeper than 10
fathoms in inner Kachemak Bay, but excluded the fjords and embayments on the south side of
the Bay. The results from these five stations are presented and interpreted in the various results
chapters that follow. As well, a separate chapter (Chapter 6) describes the results in the context
of the report on the 2007 data (Hartwell et. al. 2009).
1.5 River Contaminant Sampling Project
The river contaminants project was designed to assess watershed contributions of hydrocarbons
and metals to Cook Inlet via many of the major rivers discharging to Cook Inlet. The sampling
builds on previous studies (Guay 2004, Frenzel 2000) that reported the rivers with varying
concentrations of individual metals. Prior studies of hydrocarbons and metals in the Cook Inlet
and Gulf of Alaska environments also report a range of concentrations, with some metals in
benthic sediments naturally exceeding some defined measures of sediment quality. The results
from ICIEMAP were designed for a more comprehensive understanding of natural metal and
hydrocarbon inputs to Cook Inlet from watershed sources and to provide a context for
interpreting contaminant concentrations measured in Cook Inlet’s marine water column and
benthic environments.
1.6 Coordinating the Integrated Cook Inlet Environmental
Monitoring and Assessment Program (ICIEMAP)
A primary task of the ICIEMAP is to coordinate the efforts of four separate but related studies
such that a comprehensive, relevant, and statistically-valid program is conducted that benefits
each study beyond their own goals. For example, the combined study results will fulfill the
requirements of the Cook Inlet NPDES Permit for large-volume dischargers to Cook Inlet while
also providing CIRCAC with additional information fulfilling their OPA 90 monitoring
mandates.
One of the major strengths of the program is the team of Principal Investigators, many of whom
have worked together on various marine research projects throughout Alaska. As well, each has
significant experience working in Cook Inlet’s marine environment, has worked with Cook Inlet
oil industry and agencies, and has experience conducting monitoring and assessment studies in
the Cook Inlet area. Coordination of the overall ICIEMAP was conducted by CIRCAC and
Kinnetic Laboratories, Inc. Numerous subcontractors (identified in Chapter 2) were integrated
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into the program to lead various aspects of the studies. Funding for the field and sample analysis
portions of the study was provided by the NOAA National Ocean Service’s Office of Restoration
& Response and by Chevron and XTO (the large-volume dischargers required to conduct a fate
and transport study for produced water). They also provided funding for data analysis and report
writing, which was also supplemented by CIRCAC.
Standard sampling, analytical and reporting protocols allow data sharing among the studies,
thereby having reduced costs for each project, minimizing duplication, and maximizing the value
of the data (e.g. each study’s results aids in the comparisons and interpretations of the other
studies).
1.7 Cook Inlet Setting
1.7.1 Cook Inlet Geography and Climate
Cook Inlet is a semi-enclosed 270 km long estuarine embayment that extends northward from the
Gulf of Alaska (Figure 1). It is widest at the mouth (~90km) with a pinch point that narrows to
less than 20 km and “separates” the upper Inlet from the lower Inlet. Cook Inlet includes several
large features that include Kamishak Bay, Kachemak Bay, Redoubt Bay, Trading Bay, and
Turnagain and Knik Arms, as well as many smaller bays and coves on both the east and west
side (Figure 2). Approaching the Inlet, continental shelf bathymetry shoals up to less than 100 m
at the mouth with a deeper channel branching into Kachemak Bay and extending along the axis
of the Inlet and around Kalgin Island. Average depth is 60 m with the basin, ranging from 100 m
near the mouth to 40 m or less at the head of the estuary.
Several major islands occur throughout Cook Inlet and one of them, Augustine Island, is an
active volcano and can be seen as a major feature in Kamishak Bay (Figure 2). Further north and
flat in appearance, Kalgin Island lies in the middle of the central Inlet, while Chisik Island is a
massive, uplifted rock formation tucked into the mouth of Tuxedni Bay on the western side.
Near the Inlet's head, Fire Island can be seen amidst the mud flats just west of Anchorage. Semipermanent sand shoals occur in the central Inlet, south and west of Kalgin Island, and off
Trading Bay in the upper Inlet. The shoals emerge on low tides, appearing as heavily rippled,
almost pure-sand islands actively eroded and rebuilt in the strong currents. Ephemeral, the
shoals are devoid of any resident biota. Quicksand is encountered around the unconsolidated
margins.
The scale and placement of mountain ranges in interior Alaska tends to trap and build significant
weather features. During the summer, low pressure predominates over the inland area, and
storms are relatively infrequent. During the winter, high pressure predominates over central
Alaska, with frequent North Pacific storms (low pressure systems) traveling along the Gulf of
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Alaska from the Aleutians (MMS, 1995 in ADNR 1999). Surface winds are strongest in the
coastal area, averaging between 12 and 18 knots offshore. Winter extremes range from 26 to 39
m/sec, and can be even stronger when channeled by topography, such as in Turnagain Arm or the
Matanuska Valley (AEIDC, 1974 in ADNR, 1999) or by coastal mountain gaps.
Cook Inlet's climate is transitional between a maritime and a continental climate. The areas
nearer to the Gulf of Alaska are more maritime influenced, while the head of the Inlet is more
continental. Some areas of the Kenai Mountains receive over 2.5 m of precipitation per year due
to the combination of elevated peaks and maritime moisture, while the flatlands of upper Cook
Inlet receive less than a meter per year (KPB, 1990 in ADNR 1999). Without the moderating
effects of the Gulf of Alaska, air mass temperatures of the upper Cook Inlet area are more
extreme. Occasionally during the winter months, this area will experience short periods of
extreme cold and/or high winds when strong pressure gradients force cold air southward from
interior Alaska (KPB, 1990). In winter and summer, moderately strong. The Inlet region is also
experiencing rapid climate change. Over the last 50 years, temperatures in Alaska have
increased around 2 degrees Celsius on average, with most of the change occurring in the winter
and spring (ACRC 2008).
-pressure cells develop over the coastal plains of Kenai and Anchorage and the Susitna Valley.
Summer water temperatures in Cook Inlet can reach over 10o C. Sea ice is generally present to
some extent between November and April (LaBelle, et al., 1983 in ADNR, 1999). This ice,
mostly a result of freshwater input from the northern rivers, is concentrated in the upper region
of the Inlet, but occasionally drifts south as far as Anchor Point. Ice concentrations have also
been observed in Kamishak Bay, as well as Chinitna, Tuxedni, and other western Cook Inlet
bays (KPB, 1990 in ADNR, 1999). Sea ice also forms at the protected heads of small bays along
Kachemak Bay where there is relatively little circulation and an abundance of fresh water.
Though sometimes covering a large percentage of upper Cook Inlet, the sea ice readily fractures
from the large tidal exchanges (Hopkins, 2004). A combination of sea ice and strong upper Inlet
currents have proven to be operational hazards to moving or moored vessels.
1.7.2 Cook Inlet Watershed
The Cook Inlet drainage area spans approximately 10,000 km2 of Southcentral Alaska. The
largest river draining into Cook Inlet is the Susitna River, which is the 15th largest river in the
US at an average flow of 1,450 cubic meters per second (USGS, 1990). Other large rivers
draining into the inlet are the Beluga, McArthur, Big, Drift, Tuxedni and McNeil rivers on the
west side, and the Matanuska, Knik, Portage, Kenai, Kasilof, and Fox Rivers on the east side.
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The Cook Inlet drainage basin is surrounded by high mountains. These ranges include the
Chugach, Talkeetna, Kenai, Alaska, Aleutian, and Tordillo mountain ranges. Glaciers cover
about 10 percent of the land area of Cook Inlet basin, and provide a large portion of the input to
these watersheds (Brabets and Whitman, 2004 in ADNR, 2008). Within the Aleutian Range are
five active volcanoes: Mount Spurr, Mount Redoubt, Mount Iliamna, Mount Augustine, and
Mount Douglas. The most recent eruption was from Mount Redoubt, in the spring of 2009,
which endangered the Drift River oil storage facility with lahar flows and flooding. Both Mount
Spurr and Augustine have also been active in recent decades.
Cook Inlet receives large quantities of glacial sediment from the rivers in the watershed.
Following general circulation patterns, sediment is generally transported up the east side of the
Inlet and down the west side, and is moved out of Kamishak, Tuxedni, and Kachemak Bays
(KPB, 1990 in ADNR 1999). Glacial rivers also contribute large amounts of fresh water to the
inlet. Salinity decreases towards the head of the Inlet where the major freshwater inputs occur
but there are pockets of depressed salinity near all rivers mouths.
1.7.3 Cook Inlet Bathymetry, Tides, and Currents
North of the Forelands, Cook Inlet is generally less than 36 m deep, with deeper pockets and
shallow shoals (Figure 3). South of the Forelands, two deeper channels extend on either side of
Kalgin Island, and join together further south. This channel eventually widens to extend across
the mouth of Cook Inlet, and reaches approximately 145 m deep (KPB, 1990 in ADNR 1999).
The bottom sediments range from clay to cobbles, with sediment coarser than sand common
outside protected waters (MSB 1983 in ADNR 1999).
As with the rest of the Gulf of Alaska, Cook Inlet has semi-diurnal tides with the northern Inlet’s
tidal range averaging close to 9 m, and can reach up to 11 m. The shape and bathymetry of the
basin is such that the principal lunar semidiurnal tide (M2 tide factor) resonates and creates some
of the highest tidal amplitudes in the world. The mean tidal range varies from 3.5 m at the
Barren Islands (at the mouth of the Inlet) to more than 8 m at Anchorage (NOAA, 2006). In
general, large tidal exchanges within a basin will create strong tidal currents. Local
constrictions, however, such as that seen between the West and East Forelands (Figure 2), cause
the tidal amplitude and subsequent currents to increase, creating areas of even greater current
velocities, 3.3m/s (6.5 knots). While the Inlet as a whole has an average maximum surface
current of 1.5 m/s (3 knots), local areas can have currents greater than 5 m/s (10 knots) (Li et. al.
2004). In Turnagain Arm at the head of the Inlet, under certain conditions, the rush of the
incoming tide can create a tidal bore (moving wave) over a meter in height travelling up the
Arm.
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Figure 1. Cook Inlet and Gulf of Alaska from SeaWiFS satellite. Image provided by Orbimage.
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Figure 2. Several major features within Cook Inlet. Image provided by Orbimage.
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Figure 3. Cook Inlet bathymetry. Data from NOAA.
Much of our understanding of the circulation of Cook Inlet comes from studies conducted in the
late 1970’s (Burbank 1977, Barrick 1978, Muench et al. 1978, Muench et al. 1981). These
studies cover a similar time frame and describe many of the same patterns (Figure. 4), net
freshwater outflow from the upper Inlet and inundation of the Alaska Coastal Current into lower
Cook Inlet creating a counter-clockwise pattern. More recent studies are refining these models,
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showing that eddies shift or weaken significantly during differing seasons. Not surprizingly, the
influence of currents entering from the Gulf of Alaska also vary significantly by season.
A feature that is quite unique to the Inlet results from the interaction of the bathymetry and the
large tidal flow. Known locally as tidal rips, strong shear and convergence zones form from
changes in tidal flow associated with the changes in bathymetry. These convergent rips have
demonstrated their abilities to accumulate debris, ice, and spilled oil, and may be a barrier to
horizontal mixing. In a strong rip, oil slicks and debris have been observed to be sucked beneath
the surface and pop up further downstream.
Figure 4. Circulation patterns in lower Cook Inlet; left as presented by Burbank (1977) and right
by Muench et. al. (1978).
Three major river systems, the Knik, Matanuska, and Susitna Rivers, and numerous smaller,
freshwater systems drain into the northern Inlet and combined, constitute the largest river
drainage into the Gulf of Alaska. Many of the larger rivers drain glaciers and thus include
ground up glacial flour. The freshwater influx and sediment loads from the rivers have high
seasonal variability with peak flows associated with snowmelt in the spring and summer and
weather (rain) events in the fall. Suspended sediments introduced by the rivers are transported
by the prevailing currents and are either deposited in areas of lower flow or turbulence within
Cook Inlet or are transported out of the Inlet and deposited downstream in Shelikof Strait
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(Boehm, 1998). The lower Inlet is comprised of reworked glacial sediments (mainly sand and
gravel). Large permanent sand waves, megaripples up to 10m high, have been described in the
central lower Inlet, resulting from catastrophic glacial-meltwater flood events (MMS 2003). No
significant accumulation of fine-grained-sediments occur in most of the central Inlet (Hein et al.
1977) due to strong tidal currents and potential deep-impacting winter storms.
Fine sediments that do deposit in Cook Inlet have two primary sources - chlorite-rich Copper
River silt and clay (transported from the eastern Gulf of Alaska via the Alaskan Coastal Current)
and illite-rich silt and clay from several major rivers in upper Cook Inlet (Hein et al. 1979). The
chlorite-rich clays are found on the east side of the Inlet whereas the illite-rich clays are
characteristic of the west side. The two clays mix and are eventually deposited in Shelikof Strait
south of Kamishak Bay (Atlas et al. 1983, Boehm 2002).
1.7.4 Ecology
The circulation regime determines dominant habitats and ecosystems for different parts of the
Inlet. The southern areas of the Inlet, including Kachemak Bay on the east side and parts of
Kamishak Bay on the west side, are highly productive, due partly to both the upwelling of
nutrient-rich waters through Kennedy and Stevenson entrances at the mouth of the Inlet, and to
light penetration in these clear, oceanic waters. In contrast, with little light penetration in its
turbid waters, the west-side is considered to be net-consumptive rather than net-productive.
Along intertidal and subtidal shorezones, sedentary marine fauna occur closely associated with
sediment type and water flow (turbulence). Kelps and macro-alga require a hard substrate upon
which to attach. Providing shelter and productivity to their associated assemblages, a complex
food web is created among its residents. On soft sediments, burrowing organisms are more
likely encountered. The vast mud flats in the upper Inlet and particularly in Tuxedni Bay contain
abundant invertebrate populations (small clams, worms and crustaceans) that are a critical food
source for massive populations of migrant shorebirds. Coarser-grained sands and gravel habitats
provide for larger, longer-lived, hard-shell clams along with various fish, crabs and starfish.
Some species, namely razor clams, cockles, little-neck clams, tanner and dungeness crabs are of
commercial and recreational interest.
Under varying conditions of winter winds and currents, packs of ice will move about the Inlet.
When they encounter the shoreline, ice scour can be a dominant disturbance in the intertidal and
shallow subtidal. In cold years, exposed surfaces may be scraped completely clean of epibiota.
These areas tend to rebound in the spring with ephemeral or opportunistic species such as
barnacles and green alga, with these recruits lasting perhaps for a year or two before being
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removed again in the next scouring event. During extreme cold conditions on upper Inlet mud
flats, shifting ice gouges the ice-glazed sediments and in their wake, provides an exposed feeding
niche for a small population of unique over-wintering rock sandpipers. With sufficient winter
food, they are able to survive the harsh winter conditions and thus, gain a major advantage in the
timing and reduced stress from their otherwise lengthy spring migrations.
All five species of Pacific salmon (Oncorhynchus spp) spawn in the Cook Inlet watershed. The
Inlet is also home to sea otters (Enhydra lutris), harbor seals (Phoca vitulina), harbor porpoise
(Phocoena phocoena), Dall’s porpoise (Phocoenoides dalli), the endangered Steller sea lion
(Eumetopias jubatus), and an endangered, indigenous population of beluga whales
(Delphinapterus leucas). Humpback whale populations (Megaptera novaeangliae) are
increasing in southcentral Alaska and are now commonly seen in Kachemak Bay and along the
outer Kenai coast. Transient killer whale pods (Orcinus orca) are occasionally seen in Kachemak
Bay feeding on marine mammals. Many resident and migratory seabirds and shorebirds use
Cook Inlet, with the wide intertidal mudflats of the upper Inlet and in areas of Kamishak and
Kachemak Bay providing rich seasonal feeding habitat.
1.7.5 Human Activity in Cook Inlet
The relatively mild climate, gentle topography, and easy ocean access of the Cook Inlet basin has
made it the center of human activity in Alaska. Approximately 418,000 people live within the
Cook Inlet watershed, almost two-thirds of the state's population (US Census Bureau, 2010).
The majority of these people, around 280,000, live in the municipality of Anchorage while
approximately 85,000 more live in the Matanuska and Susitna valleys northeast of Anchorage.
Most of the remaining population, around 53,000, is found on the Kenai Peninsula on the eastern
side of the Inlet. The west side of Cook Inlet is sparsely populated, home to only a few small
towns and a smattering of oil and gas infrastructure.
Due to its unique location with extreme tidal flushing, the city of Anchorage uses only primary
wastewater treatment, pumping the remainder of its municipal waste directly into Cook Inlet.
Most other major communities on the Inlet use secondary treatment but a few have tertiary
treatment systems (Boraas, 2009).
Anchorage is the largest port in Cook Inlet, and a major destination for cargo ships bringing
goods into the state. Kenai/Nikiski on the Kenai Peninsula is the second busiest port, primarily
serving the oil industry at the Tesoro refinery, and the ConocoPhillips-Marathon LNG plant.
Smaller ports include Homer, on Kachemak Bay, and Drift River on the western side of the inlet.
16
Major industries in Cook Inlet include oil and gas extraction, fishing, and tourism. Offshore oil
development took off in the 1960s, with production peaking in 1970 at 83 million bbls. Though
production has since declined, the industry is still significant, with annual production of 6 million
bbls of oil and 196 Bcf of gas in 2006. There are currently 14 active offshore platforms in
central Cook Inlet, with many of these concentrated in the Trading Bay area (Figure 5).
Pipelines beneath the Inlet carry product to tank farms, produced water treatment facilities (a
focus of the ICIEMAP) and refineries on shore (Figure 6). Tanker vessels transport crude oil,
refined oil, and liquefied natural gas year round, although unfavorable icing conditions
occasionally limit winter operations.
The salmon fishery is the Inlet's largest commercial fishery with all five species of Pacific
salmon harvested. Drift gillnetting, set gillnetting, and purse seining, mainly in the upper Inlet,
account for about 4% of Alaska's total harvest. Halibut, clams, and other finfish are also
harvested commercially. Sport fishing and subsistence fishing are also important; approximately
half of the state's total sport-fishing effort occurs in Cook Inlet. Personal use and subsistence
salmon fisheries provide many Inlet residents with a valuable food source. Subsistence fisheries
are culturally important in the less-populated areas of the Cook Inlet basin, including the
communities of Nanwalek, Port Graham, Seldovia, Tyonek, Alexander, and Skwentna. Most of
the Inlet is designated as "non-subsistence," but many residents participate in the "personal use"
fisheries on the Kenai and Kasilof rivers. Tourism is also a significant part of the Cook Inlet
economy, with most visitors arriving in the summer. In the summer of 2006, over 800,000
people visited Anchorage and over 400,000 visited the Kenai Peninsula.
All of these human activities represent potential sources of contaminants in the Inlet’s water and
sediments--through municipal wastewater inputs, runoff from urban areas, leaks and spills from
vessel traffic, discharges from onshore- and offshore- oil and gas operations, mining wastes, fishprocessing discharges, as well as numerous smaller industries.
1.8 Report Organization
A decision was made that not only would the sampling and analytical laboratory costs be shared,
but an agreement was struck where the data would be received by all participants and one
integrated report would be produced. Independent quality assurance/quality assessment of data
tables would ensure that data were reported correctly.
This report describes the combined efforts of all four studies described earlier in this chapter.
Components of each study are integrated into each of the other studies. Chapter 2 provides field
and laboratory analytical methods associated with all of the sampling efforts for the ICIEMAP.
Individual results chapters provide methods for specific data analyses procedures that were
unique to that chapter. The results are presented in chapters that are organized around the
17
physical environment (sediments and oceanography in Chapter 3); metals data for rivers, the
water column, and benthic sediments (Chapter 4); organic contaminants for rivers, water column,
and benthic sediments (Chapter 5); benthic invertebrates (Chapter 6); the NS&T deep stations in
Kachemak Bay (Chapter 7); and overall conclusions from each chapter (Chapter 8). References
(Chapter 9) and Appendices (electronic) complete the report.
Some ICIEMAP data is used repeatedly in interpreting various results. For example, sediment
grain size data are presented numerous times throughout the report as it was used to set the stage
and interpret different datasets. Also, although Chapter 7 provides a mechanism for the NS&T
program to describe the data for the five deep Kachemak Bay stations within the context of their
earlier study in 2007, the invertebrate and contaminants data from those stations are also covered
within each of the other result chapters.
Finally, although there have been studies and synthesis of data in the late 1970’s under the
auspices of Minerals Management Service’s (MMS) Outer Continental Shelf Environmental
Assessment Program (OCSEAP) that described the general oceanography, geology and biology
of the Inlet in anticipation of Federal oil leasing, modern surveys using more sensitive measuring
or analytic technology (e.g., oceanography profiling instruments and chemistry lab methods)
were not used much in Inlet studies before the mid 1990’s. Then, various programs of CIRCAC,
MMS, and EMAP began delivering high-quality data relevant to current studies. This report
builds on that legacy and provides a comprehensive, integrated data set and interpretations for
future studies.
18
Figure 5. Cook Inlet oil production platforms showing pipelines that ship oil or produced water to shoreside
treatment, storage, or refining facilities.
19
Figure 6. Cook Inlet oil and gas industry underwater and shore-based pipelines. Red lines represent oil or
produced water pipelines. Green lines represent gas lines. Gray lines represent pipelines that have been
abandoned and are shut-in (graphic provided by Cook Inletkeeper)
20
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