North Central Puget Sound GRP

  • Interim update: N/A
  • Last full update: 2020
  • Public Comment:

Table of Contents


Site Description

This section provides an overview of the North Central Puget Sound (NCPS) GRP planning area’s physical features, hydrology, climate, winds, tides, and currents. This section also includes an oil spill risk assessment. The NCPS GRP encompasses about 373 square miles. The planning area borders are, approximately, Similk Bay and La Conner to the north, Whidbey Island to the west, Stanwood and Everett to the east, and the Mukilteo-Clinton Ferry to the south. The NCPS GRP includes the marine waters of Deception Pass, Holmes Harbor, Penn Cove, Port Gardner, Port Susan, Possession Sound, Saratoga Pass, Similk Bay, Skagit Bay, and Swinomish Channel. Fully or partially, the cities of Clinton, Coupeville, Everett, La Conner, Langley, Marysville, Mukilteo, Oak Harbor, and Stanwood reside within the planning area. Portions of the Water Resource Inventory Areas Lower Skagit (WRIA 3), Stillaguamish (WRIA 5), Island (WRIA 6), and Snohomish (WRIA 7) are within the NCPS GRP. The planning area falls within the boundaries of Island, Skagit, and Snohomish counties.

Physical Features

North Central Puget Sound is a geographically diverse area. It includes many different types of shorelines, from large marshes and deltas on the mainland to wave cut platforms on Whidbey Island. Much of the land in the area is rural, rural residential, or conservancy. There are seven state parks (link), numerous county and city owned parks, and dozens of boat ramps and marinas throughout the region. Everett is an active port city located to the Southeast of the GRP with an extensive waterfront populated by wood processing facilities, marinas, parks, and vessel repair facilities. Outside of Everett, local economies rely on natural resource use and tourism. Aquaculture, commercial fishing, and recreational fishing are active and important industries throughout the region. The U.S. Navy maintains two bases in the area; Naval Station Everett on Port Gardner Bay and Naval Air Station Whidbey Island near Oak Harbor.

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The North Central Puget Sound GRP area contains marine and estuarine waters that are biologically rich and sensitive. A wide diversity of shoreline and marine habitats (estuaries, eelgrass and kelp beds, rocks, reefs, and islands) and abundant food resources contribute to making the area home to a wide range of fish and wildlife. The region contains nesting colonies for shorebirds and waterfowl; a number of marine mammal haulouts and breeding sites; and rearing and feeding habitat for a large variety of marine and anadromous fish. Shallow intertidal bays at the mouths of the Skagit, Stillaguamish, Snohomish Rivers and Similk Bay are home to vast numbers of bird species. The marsh and tidal flats of the Skagit River are particularly rich and diverse. Port Susan and the Skagit River Delta both contain voluntary or state-owned conservation areas. This GRP area is home to many species of marine mammals, including southern resident killer whales, gray whales, and humpback whales. Refer to the Resources at Risk section for more detailed resource information.

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The North Central Puget Sound GRP area consists of marine waters east of Whidbey Island to the mainland, including Deception Pass, the waters surrounding Camano Island, and the shallow waters between Fidalgo and Whidbey Islands. Deception Pass, Holmes Harbor, Penn Cove, Port Gardner Bay, Port Susan, Possession Sound, Saratoga Pass, Similk Bay, Skagit Bay, and Swinomish Channel reside within the geographic boundaries of this plan.

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The largest sources of fresh surface water from the mainland include the Snohomish River, North and South Forks of the Skagit River, and the Stillaguamish River. The Skagit River is the largest freshwater supply to North Central Puget Sound. This two layer system of buoyant freshwater over a saltwater lens in the Whidbey Basin interiors creates a relatively balanced mixing zone inside the North Central Puget Sound GRP area. Water salinity in this area stays relatively constant with the exception of declining salinity values in Skagit Bay at the Skagit River confluence for a short time during spring snow melt. These lower salinity levels generally last 2 months.

The Snohomish River accounts for about 30 percent of the freshwater discharge to the Whidbey Basin. The Skagit and Stillaguamish Rivers both supply freshwater recharge to Port Susan. Main sources of groundwater recharge in the area reside in Whidbey and Camano Islands sole source aquifers. Surface water runoff during spring and fall winter rain events also contribute to freshwater recharge.

Portions of the Water Resource Inventory Areas for the Lower Skagit (WRIA 3), Stillaguamish (WRIA 5), Island (WRIA 6), and Snohomish (WRIA 7) Watersheds fall within the geographic boundaries of this plan.

Lower Skagit (WRIA 3): The Lower Skagit Watershed is in the northern part of Puget Sound east of the San Juan Islands. It comprises the western part of Skagit County and small portions of Snohomish and Whatcom Counties. Fidalgo, Guemes, Cypress and other smaller offshore islands are also included in the WRIA 3 watershed. In addition to the Skagit River and its delta, the watershed includes Lake Samish and the Samish River watersheds.

Yearly precipitation ranges from as little as 15-20 inches in the coastal area to over 70 inches in the Cultus Mountains. Most of this precipitation arrives during the winter months when water demand is low. During the summer irrigation season, the snowpack is gone and there is little rain. Stream and river flows are dependent on groundwater inflow during the dry summer months.

Stillaguamish (WRIA 5): The Stillaguamish Watershed is in the central part of the Puget Sound and comprises the northwestern part of Snohomish County and the south central part of Skagit County. On its west side it is bounded by Puget Sound and its east side includes portions of the Cascade Mountain range. This watershed is sparsely populated. The watershed includes the Stillaguamish River and its two forks that originate in the Cascade Mountains.

Yearly precipitation ranges from 30 – 35 inches in the coastal area to over 150 inches in the Cascade Mountains. Most of this precipitation arrives during the winter months when water demand is low. During the summer, the snowpack is gone and there is little rain. Stream and river flows are dependent on groundwater flow during the dry summer months.

Island (WRIA 6): The Island Watershed consists of Whidbey and Camano Islands along with several smaller islands. The northern part of Whidbey Island has the largest population density of the area with the city of Oak Harbor and the Naval Air Station. The rest of the islands mainly consist of low-density rural development. There are no major rivers in the watershed, and much of the water availability comes from groundwater, which exclusively recharges from precipitation.

Northern and central Whidbey Island are in the rain shadow of the Olympic Mountains, creating a high variability of rainfall in the watershed, from 18 inches at Coupeville to 42 inches at Goss Lake. Most of this precipitation arrives during the winter months when water demand is low. The Island watershed does not benefit from snow pack; therefore, stream flows are dependent on groundwater inflow during the dry summer months.

Snohomish (WRIA 7): The Snohomish watershed comprises the northeastern portion of King county and south central Snohomish County, including the city of Everett and its adjacent suburban areas. On its west side it is bounded by Puget Sound and its east side includes portions of the Cascade Mountain range. This watershed has significant urban development in its western portion and large areas of agricultural development along the Snohomish River and some of its tributaries. The watershed includes the Snohomish River and its major tributaries, the Snoqualmie and Skykomish Rivers, which originate in the Cascade Mountains.

Average precipitation ranges from 30-35 inches per year in the coastal areas to over 180 inches in some parts of the mountains. Most of this precipitation arrives during the winter months when water demand is low. During the summer, the snowpack is gone and there is little rain. Stream and river flows are dependent on groundwater flow during the dry summer months.

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Climate and Winds

North Central Puget Sound has a maritime climate characterized by cool, dry summers, and mild, wet winters. Temperatures range from 70°F in summer (average maximum) to 35°F in the winter (average minimum). Annual precipitation is highest in December, while annual accumulation varies within the region. Average annual rainfall in Coupeville is 20.22” with December’s average being 2.69”. Average annual precipitation in Everett is higher (35.71”), with the average in December being 4.96”. Snowfall is variable, with most accumulation occurring in January; average annual snowfalls range from 6” – 7” in the region. Foggy conditions are most likely in the summer and early fall. The Western Regional Climate Center (link) maintains this climate data for Coupeville and Everett.

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Prevailing winds are generally from the south or southwest in the late fall and winter, and from the north in the summer. Wind speeds range from 5.8 mph to 7.9 mph in December through April, and 3.6 mph to 6.7 mph in May through November. Whidbey Island affects the prevailing winds near Oak Harbor, which are generally south east in winter and fall and west in the summer; average annual wind speeds for Oak Harbor range from 8.0 mph to 8.6 mph. High winds are typically greatest in November through January. Wind gusts can occasionally reach 50 mph or greater. The Western Regional Climate Center (link) maintains wind data online.

The Puget Sound Convergence Zone, a phenomenon where northwest winds in the upper atmosphere become split by the Olympic Mountains then re-converge over Puget Sound causing updrafts, influences weather in the area. The updrafts can lead to convection and then rain showers or adverse weather conditions. For more information, visit

The visibility in the North Central Puget Sound is generally moderate to good, with occasional conditions of poor visibility in the morning and at night. Dense fog occurs with less regularity than in coastal regions, due to the sheltered nature of the area.

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Tides and Currents

Currents in North Central Puget Sound are generally weak and variable due to the protective nature of the landmass that surrounds the basin interior. The north end of Whidbey Island at Deception Pass is the exception; currents are very strong in this area.

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  • Deception Pass
    Tidal Range: 12.2 ft. to -3.9 ft. (average high and low tidal ranges)
    Current: -8.0 knots on ebb and 8.0 knots during a flood
  • Skagit Bay and Saratoga Passage
    Tidal Range: 13.6 ft. to -3.5 ft.
    Current: -2.2 knots on ebb and 2.9 knots during a flood
  • Possession Sound and Port Susan
    Tidal Range: 13.6 ft. to -3.5 ft. (average high and low tidal ranges)
    Current: -0.6 knots on ebb and 0.5 knots during a flood

Currents in Saratoga Passage generally flow in a southerly direction and tend to be weak and variable, sometimes slightly moderate in more narrow areas south of Penn Cove between Camano and Whidbey Islands. Currents in Port Susan usually flow in a southerly direction towards Possession Sound. They tend to be weak, variable, and influenced by the discharge flow of the Stillaguamish and Snohomish Rivers. Increased surface currents in Hat Slough (south of Stanwood, WA) may be present, but are typically dependent on the flow of the Stillaguamish River.

Tides in this system are diurnal. Tides and currents vary with seasonal runoff and lunar cycles in localized areas. Spill responders should consult tide and current tables (link) for particular locations of interest.

A note about the Swinomish Channel: It connects Padilla Bay and Skagit Bay. Both of these Bays have significant tides, and they are out of sync with each other. The currents in the channel are driven by the difference in the tidal height at the two ends, making it a “progressive wave”, which is not in sync in the usual way with the change in tidal heights. To make things more complicated, it takes a while for the progressive wave to travel the length of the channel. In short, There is little way of predicting the timing or strength of the currents in the channel.

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Risk Assessment

The North Central Puget Sound planning area is plentiful in natural, cultural, and economic resources, all at risk of injury from oil spills.  Potential oil spill risks to these resources include refined and crude oil products, rail transportation, large commercial vessels, barge transits, pipelines, ferries, road transportation, aircraft, recreational boating, and other oil spill risks.  This section briefly discusses these risks and how they could impact the GRP planning area. To find a more detailed study of oil transportation in Washington State, go to Ecology’s Washington State 2014 Marine and Rail Oil Transportation Study (link).

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Oil Types: Both refined petroleum products and crude oils are transported in bulk within this planning area. Crude oil contains a mix of hydrocarbons with a wide range of properties, while a refined product is a single type of oil, such as diesel or gasoline. Depending on the oil and the characteristics of the water the oil is spilled into, some of the oil transported in this planning area may not float.

Different oils will behave differently when spilled to water. Some heavy oils will sink immediately, some oil suspends in the water column, and lighter oils may remain on the surface and evaporate within hours. Over time, oil that initially floats can weather and mix with sediment, causing it to submerge or sink.  Non-floating oils pose a specific risk to the environment because they can harm underwater or bottom-dwelling species that would otherwise be unaffected during an oil spill that remained floating on the water’s surface.

Traditional response strategies, including the booming strategies in this GRP, are designed for floating oil. However, there are steps we can take to plan for and respond to a non-floating oil spill. Section 3 provides an overview of areas where non-floating oil might accumulate if spilled within this planning area, along with information on specific tactics that may be effective during a response. More response options recommended for finding and recovering oil below the water’s surface are in the NWACP Section 9412, Non-Floating Oil Spill Response Tool (link).

Rail Transportation: Rail companies transport oil via both unit trains and manifest trains up stream of this area.  Unit trains include: up to four locomotives, buffer cars, and 118 loaded tank cars transporting oil in 714-barrel (29,998 gallon) capacity USDOT-approved tank cars.  Manifest trains include up to four locomotives, a mix of non-oil merchandise cars, and one or more 714-barrel (29,998 gallon) capacity USDOT-approved tank cars carrying refined oil products, such as diesel, lubrication oil, or gasoline.  These trains may include emptied tank cars, each with residual quantities of up to 1,800 gallons of crude oil or petroleum products.  Every train locomotive typically holds a few hundred gallons of engine lubrication oil, plus saddle tanks that each have an approximate capacity of 5,000 gallons of diesel fuel.  Manifest trains may also transport biological oils and non-petroleum chemicals.

Unit trains carrying crude currently operate on specific routes.  Unit trains carrying crude from the Bakken Formation in North Dakota enter Washington State near Spokane, continue along the Columbia River to Vancouver, and then head north along I-5.  There are approximately five miles of BNSF-owned and operated track along the waterfront of Snohomish County in the southeastern part of the planning area that services both unit and manifest trains.

Passenger trains (Amtrak, Sounder) also transit through the planning area along the water.  The area south of Everett and north of Mukilteo are where the major rail lines run. The Mt. Baker Terminal also serves as a transportation hub for components of airplanes via vessel and rail.

Large Commercial Vessel Traffic: Over one-hundred large commercial vessels carrying cargo and containers arrive in the Port of Everett each year, generally transiting to the east and south of Whidbey Island, passing Mukilteo, into Everett. Additionally, smaller commercial vessels (e.g. logging, fishing) transit the area regularly. These vessels typically use large amounts of heavy and blended fuel oils and other petroleum products, raising the potential for sensitive resource impacts if an oil spill incident (i.e. allisions or groundings) were to occur.

Barge Transits: Naval Air Station Oak Harbor receives fuel shipments by barge. Vessels at Naval Station Everett occasionally receive fuel oil from barges while moored. Oil spill risks from tank barges include accidents or emergencies occurring during transit and incidents occurring during the transfer of fuel from the barge to a vessel or facility.

Pipelines: Large quantities of fuel from refineries in Northern Washington are transported through pipelines to population centers father south. Pipelines in the region are typically located inshore, away from the marine environment, but pose a risk to North Central Puget Sound at points where they cross rivers, creeks, and ditches that drain into the Puget Sound.

Washington State Ferries: Two Issaquah class ferries cross between Clinton and Mukilteo over thirty-five times daily; more than seventy transits combined. Ferries can carry thousands of gallons of diesel fuel and hundreds of gallons of hydraulic fluid, lube and motor oils, as well as other oils or petroleum based products.  Potential risks include spills during bunkering or internal fuel transfers, hydraulic failures, unintentional waste oil discharges, and vessel accidents.   Issaquah class ferries use diesel fuel for propulsion and can carry as many as 124 vehicles.

Road Transportation: Two state highways are present in the planning area; SR-20 (Whidbey and Fidalgo Islands) and SR-532 (Camano Island). I-5 is located to the east and upstream of the planning area, crossing several rivers that flow into the planning area.  Vehicle traffic on roadways pose an oil spill risk in areas where they run adjacent to shorelines, or cross over lakes, rivers, creeks, and ditches that drain into Puget Sound.  A vehicle spill onto a bridge or roadway can cause fuel or oil to flow from hardened surfaces into water.  Commercial trucks can contain hundreds to thousands of gallons of fuel and oil, especially fully loaded tank trucks, and may carry almost any kind of cargo, including hazardous substances or other materials that might injure sensitive resources if spilled.  Smaller vehicle accidents pose a risk as well, a risk commensurate to the volume of fuel and oil they carry.  Vehicle numbers on state highways typically increase in summer months as tourists visit and explore the area.

Aircraft: The Whidbey Naval Air Station and Paine Field (Everett) are the major drivers of air traffic in the planning area, with a number of smaller airports operating on Whidbey and Camano Islands. Coupeville, Langley, and Northern Camano Island all have small airstrips. Recreational aircraft and corporate jets, rather than large commercial airliners, primarily use these airports.  Aircraft failures during inbound or outbound flights could result in oil spills to water.

Recreational Boating: Accidents involving recreational watercraft in the planning area have the potential to result in spills of a few gallons up to hundreds of gallons of various petroleum products (e.g. gasoline, diesel, lubricants).  Examples of such accidents might include vessel collisions, allisions, groundings, fires, sinking, or explosions. The southern entrance of the Swinomish Channel, Skagit and Stillaguamish Bays, Port Gardner (Everett), and Port Susan are all areas where recreational boating incidents are a greater risk due to shallow waterways and high use.

Other Oil Spill Risks: Other potential oil spill risks include fuel storage areas (including waste oil storage), road run-off during rain events, on-shore or near shore activities where heavy equipment is being operated or stored, and the migration of spilled oil through soil on lands adjacent to marine waters, or streams that drain to such waters.

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Resources at Risk

This section provides a summary of natural, cultural, and economic resources at risk in the planning area, including those resources at risk from oils with the potential to sink or submerge. It provides general information on habitat, fish, and wildlife resources, and locations in the area where sensitive natural resource concerns have been identified. It offers a summary of cultural resources that include fundamental procedures for the discovery of cultural artifacts and human skeletal remains. General information about flight restrictions, wildlife deterrence, and oiled wildlife can be found near the end of this section. A list of economic resources in the area is provided in the appendix.

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This material is presented with enough detail to give general information about the area during the first phase of a spill response. During an actual incident, more information about resources at risk will be available from the Environmental Unit in the Planning Section.

Note: specific resource concerns related to areas that already have designated protection strategies may be found in the “Resources At Risk” column of the matrix describing the individual strategies.

The information provided in this section can be used in:

  • Assisting the Environmental Unit (EU) and Operations in developing ad hoc response strategies.
  • Providing resource-at-risk “context” to responders, clean-up workers, and others during the initial phase of a spill response in the GRP area.
  • Briefing responders and incident command staff that may be unfamiliar with sensitive resource concerns in the GRP area.
  • Providing background information for personnel involved in media presentations and public outreach during a spill incident.
  • Providing information on benthic and water column species or cultural resources present to assist in planning for oils with the potential to sink or submerge.

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Natural Resources at Risk – Summary

This area contains a wide variety of aquatic, riparian, and upland habitats. These habitats support many of Washington’s anadromous salmonid species as well as a complex diversity of other wildlife including birds, mammals, fish, and amphibians. Due to their life histories and/or behaviors, some of these species are unlikely to be directly oiled during a spill incident but may be disturbed by other operations such as cleanup, reconnaissance, or fire suppression activities. Some of the bird species are resident throughout the year, but many others seasonally migrate outside the basin.

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A number of the species found in this area are classified as threatened or endangered under the Federal Endangered Species Act or Washington State guidelines.

Classification types are listed below:

  • Federal Endangered (FE)
  • Federal Threatened (FT)
  • Federal Candidate (FC)
  • State Endangered (SE)
  • State Threatened (ST)
  • State Sensitive (SS)

Federal and State Threatened, Endangered, and Sensitive species that may occur within this area, at some time of the year, include:


  • common loon [SS]
  • marbled murrelet [FT/SE]
  • northern spotted owl [FT/SE]
  • yellow-billed cuckoo [FT]


  • gray whale [SS]
  • humpback whale (Central American population) [FE/SE]
  • humpback whale (Mexican population) [FT/SE]
  • killer whale (southern resident) [FE/SE]


  • bocaccio rockfish [FE]
  • bull trout [FT]
  • chinook salmon (Puget Sound) [FT]
  • green sturgeon [FT]
  • steelhead (Puget Sound) [FT]
  • yelloweye rockfish [FT]


  • Oregon spotted frog [FT/SE]


  • Golden paintbrush [FT]

Critical Habitats:

Critical habitats are the specific areas, occupied by an endangered or threatened species at the time it was listed, that contain the physical or biological features that are essential to the conservation of that species – and that may need special management or protection. Critical habitat may also include areas that were not occupied by the species at the time of listing but are essential to its conservation.

The following species have federally designated critical habitats within this area:

  • bocaccio rockfish
  • bull trout
  • canary rockfish
  • chinook salmon (Puget Sound)
  • green sturgeon
  • killer whale (southern resident)
  • steelhead (Puget Sound)
  • Taylor’s checkerspot butterfly
  • yelloweye rockfish

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General Resource Concerns


The North Central Puget Sound planning area provides a wide range of wildlife-habitat types. Areas of particular concern regarding wildlife include:

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  • The rivers and streams of this region provide abundant habitat for spawning salmonids. The extensive sloughs and river deltas of the Skagit, Stillaguamish and Snohomish Rivers provide a variety of key habitats for fish, shellfish, waterfowl, harbor seals, and other species. The associated riparian scrub and woodlands play a crucial role in supporting a large diversity and abundance of songbird species as breeding, migrating, and overwintering habitat.
  • The shallow intertidal and subtidal habitats in bays throughout the region are rearing areas for juvenile salmon, Dungeness crab, clams and other fish and shellfish. These habitats are often important feeding areas for waterfowl, shorebirds, and herons and are used as low tide haulouts by harbor seals. Gray whales use the shallow waters of Port Susan and Saratoga Passage as seasonal feeding areas (spring and summer).
  • Sandy or rocky shorelines can be found throughout the region. These areas support marine mammal haulout and pupping, nesting for birds, spawning habitat for forage fish.
  • Eelgrass beds occur extensively throughout the region, with the largest occurring in Skagit Bay, Similk Bay, Holmes Harbor, Port Susan and Port Gardner. These habitats provide critical nursery areas for fish and shellfish as well as important spawning habitat for herring and feeding areas for waterfowl.
  • Salt marshes and wetlands occur in sheltered areas throughout the region and in association with the larger river deltas. These habitats support a diverse array of fish and wildlife species.
  • The kelp beds present near Deception Pass, the northern part of Skagit Bay, and near Gedney (Hat) Island perform ecological functions similar to eelgrass beds and serve as important fish rearing areas.
  • Human-made structures such as pilings, rock jetties or log rafts may be used as roosting or nesting areas for a variety of birds and as haulout areas for seals.
  • Restoration sites are areas where significant efforts have occurred to restore natural functions in a degraded habitat.
  • A variety of subtidal habitats exists within this area, each of which supports a different assemblage of wildlife species as generally described below:
    • Soft sediment: This category includes areas of clays, mud, sand and gravel, which typically possess relatively low vertical relief. Animals that tend to live on the surface in these habitats can include sea cucumbers, sea stars, crustaceans such as crab and shrimp, and bottom fish such as skate, cod, and the flat fishes. These soft sediment habitats also support shellfish and other invertebrates including bivalves, worms, brittle stars, shrimplike crustaceans whose burrowing or foraging activities can penetrate up to one meter below the subsurface bottom. In deeper waters, this habitat type may also include the deep sand fields that are necessary overwintering habitat for sand lance, an environmentally critical forage fish.
    • Rock reefs: These areas serve as important habitat for a wide range of species including mobile invertebrates (e.g. snails, sea slugs, sea cucumbers, sea stars, etc.) and immobile species (e.g. anemones, barnacles, shellfish, sponges, tubeworms, etc.). Macro algae, including kelps, also widely utilize the structure that this type of habitat provides. The crevices and overhangs associated with these reefs serve as valuable habitat for a wide variety of other species such as crabs, shrimp, octopus, wolf eel, rockfish, cabezon, and lingcod. If located within their capabilities to dive, these areas may also serve as important foraging areas for birds and marine mammals.
    • Boulder and cobble fields: Larger, relatively stable boulders provide many of the same ecological functions described for rock reefs while the spaces between boulders offer enhanced refuge areas for bottom dwelling invertebrates and fish. The relative instability of the smaller cobble makes them less valuable than reefs or boulders to immobile marine life. Nonetheless, many marine organisms may live on or between the cobblestones and predatory species often utilize these habitats as foraging areas. As with the rocky reefs, these habitats may also serve as important foraging areas for birds and marine mammals as well if they are located within a species ability to dive. Depending on how much sediment the currents move through the area, the spaces between the rocks may be filled with sediment that can also support bottom dwelling life forms.
    • Water column: Much of the primary marine productivity in this region occurs in the upper 30 meters of the water column due to limited light penetration and nutrient availability. Because of this, this upper part of the water column tends to concentrate the planktonic larval forms of fish and a wide range of invertebrates, particularly during the spring plankton blooms. The deeper water column also serves as habitat for wide-ranging fish such as salmon, forage fish (herring, smelt, and sandlance), sharks, as well as a wide variety of birds and marine mammals that utilize this habitat as foraging areas.

Fish and Shellfish:

  • All of Washington’s salmonid species occur in this region, with most spawning occurring in the Skagit, Snohomish and Stillaguamish river systems.
  • Forage fish spawning occurs extensively throughout the region. Major herring spawning areas occur in Tulalip Bay, Port Susan, Holmes Harbor and northern Skagit Bay. Surf smelt and sandlance spawning occurs on intertidal gravel beaches throughout the region.
  • Shellfish, including Dungeness crab, clams and shrimp are widely distributed throughout the entire region.


  • Bald eagles and great blue herons nest throughout the region and are present year-round, and one of the largest great blue heron rookeries in western North America (supporting 50% of the breeding great blue herons in the Salish Sea) occurs on the north side of Similk Bay. Peregrine falcons and osprey also nest in this region, with especially high nesting concentrations of osprey at the mouth of the Snohomish River. These species routinely forage in intertidal and nearshore waters.
  • Large concentrations of migratory and wintering waterfowl within this region may exceed 100,000 birds during peak periods, with southern Skagit Bay, Port Susan and the Snohomish River estuary supporting the largest concentrations. Port Susan supports the largest migratory and wintering shorebird concentrations in Washington.
  • Apart from the gull and tern nesting on Jetty Island in Everett, seabird nesting in this region is limited to small, widely scattered nesting sites.
  • Marbled murrelets occur throughout the region, especially near Deception Pass, within Saratoga Passage, and in the southern portion of Port Susan and Port Gardner/Possession Sound.
  • Harbor seal and sea lion haulouts are scattered throughout the region with the largest concentrations occurring off the mouths of the rivers.
  • Small numbers of gray whales are commonly found in Saratoga Passage, Port Susan, Port Gardner, and Possession Sound from spring through late fall. Southern resident and Bigg’s (transient) killer whales (orca) are occasionally present in the area. Other cetaceans including minke and humpback whales, porpoise, and dolphins may also be present. Rare sightings of fin and sperm whales have been recorded west of Whidbey Island.
  • A wide variety of terrestrial and semi-aquatic mammals (e.g. raccoons and river otters) are present throughout this area and forage within the intertidal areas.

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Specific Geographic Areas of Concern – Overview

Areas of concern include shorelines with natural riparian vegetation, islands, wetlands, stream and river mouths, and shallow water areas – especially adjacent to natural shorelines. Public parks, private lands, and recreational areas also surround the planning area. The number that precedes the area name in the list (below) corresponds to the numbered area on the map.

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Northern Section (see Figure 1)

  1. Deception Pass: Wetlands, eelgrass, and kelp habitat. Salmonids. Forage fish spawning. Dungeness crab and shellfish. Waterfowl and marine bird concentrations (including marbled murrelets). Heron and bald eagle nesting. State (and federally) endangered Taylor’s checker spot (butterfly) populations and designated critical habitat along coastline. Deception Pass State Park
  2. Similk Bay: Wetland, eelgrass, intertidal mudflat, and salt marsh habitats. Forage fish spawning. Salmonid spawning and rearing. Dungeness crab and shellfish. Major waterfowl concentration area (fall through spring). Resident bald eagles. Harbor seal haulout area. Tribal lands and resources. Large and regionally significant great blue heron rookery occurs just north of Similk bay.
  3. Hope and Kiket Islands: Eelgrass and kelp habitats. Surf smelt spawning beaches. Waterfowl and marine bird concentrations. Nesting eagles and other birds of prey. Tribal lands and resources. Hope Island and Skagit Island State Parks.
  4. Dugualla Bay: Wetland, eelgrass, saltmarsh and intertidal mudflat habitats. Salmonid spawning and rearing habitat. Spawning habitat for herring, surf smelt and sandlance. Dungeness crab and shellfish. Seasonal waterfowl concentrations (fall through spring).
  5. Skagit River Delta: Extensive wetland, salt marsh and slough habitats. Major salmonid spawning and rearing habitat. Federally threatened Puget Sound steelhead presence and designated critical habitat. Very large wintering concentrations of waterfowl and raptors (fall through spring). Riparian habitat supports high concentrations of passerine birds.

Central Section (see Figure 2)

  1. Crescent Harbor: Wetland and eelgrass habitats. Forage fish spawning. Shellfish. Waterfowl concentrations (fall through spring). Federally threatened golden paintbrush population on adjacent Ebey’s Landing. Federal (US Navy) property.
  2. Penn Cove: Wetland and eelgrass habitats. Forage fish spawning. Shellfish. Waterfowl concentrations (fall through spring). Federally threatened golden paintbrush and state (and federally) endangered Taylor’s checker spot (butterfly) populations and critical habitat, on Smith Prairie and at other locations on adjacent Whidbey Island. Public beaches.
  3. Old Stillaguamish River Channel: Eelgrass, wetland, salt marsh and slough habitats. Salmonid spawning and rearing habitat. Presence of federally threatened bull trout, Puget Sound Chinook, and Puget Sound steelhead. Waterfowl and shorebird concentrations. Harbor seals. Leque Island and zis a ba restoration sites.
  4. Port Susan (north of Kayak Point): Extensive eelgrass, intertidal mudflat, and salt marsh habitats. Salmonid spawning and rearing habitat. Forage fish spawning. Dungeness crab and shellfish. Mudflats in north end of bay support largest shorebird concentration area in Puget Sound. Major waterfowl concentrations (fall through spring). Harbor seal haulouts. Gray whale feeding area (spring through fall). Tribal lands and resources.

Southern Section (see Figure 3)

  1. Holmes Harbor: Wetland and eelgrass habitats. Forage fish spawning. Shellfish and shrimp. Waterfowl and seabirds.
  2. Tulalip Bay: Eelgrass, saltmarsh and intertidal mudflat habitats. Salmonid spawning and rearing habitat. Forage fish spawning. Dungeness crab. Seasonal waterfowl concentrations. Tribal lands and resources.
  3. Port Gardner/Snohomish River Delta: Wetland, eelgrass, saltmarsh and intertidal mudflat habitats. Dungeness crab. Large seasonal waterfowl and shorebird concentrations. Osprey nesting. High concentrations and diversity of passerine birds in riparian habitat. Harbor seal haulouts. Tribal lands and resources.
  4. Possession Sound, Gedney (Hat) Island, and vicinity: Forage fish spawning. Juvenile salmonids and rearing habitat. Dungeness crab and shellfish. Bald eagle nesting and marbled murrelet. Orca, humpback whale, and gray whale feeding area (spring through fall).
  5. Cultus Bay: Eelgrass, saltmarsh and intertidal mudflat habitats. Significant seasonal concentrations of waterfowl and shorebirds. Foraging area for resident nesting eagles and herons. (Admiralty Inlet GRP for more information)

Note: Populations and designated critical habitat of federally listed southern resident killer whale, Puget Sound chinook, and bull trout, are found throughout all of the above areas.

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Specific Geographic Areas of Concern – Maps and Descriptions

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Figure 1: North Central Puget Sound geographic area of concern (north)

Figure 2: North Central Puget Sound geographic area of concern (central)

Figure 3: North Central Puget Sound geographic area of concern (south)

Cultural Resources at Risk – Summary

Culturally significant resources are present within the planning area. The Washington Department of Archeology and Historic Preservation (WDAHP) maintains information regarding the type and location of cultural resources. WDAHP makes this sensitive information available to the Washington Department of Ecology for oil spill preparedness and response planning. The Tribal Historic Preservation Offices (THPOs) or Cultural Resource Departments of local tribes (see Table 6-1) may also be able to provide information on cultural resources at risk in the area and should be contacted, along with WDAHP, through normal trustee notification processes when significant oil spills, or smaller spills above reportable thresholds, occur in the area.

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During a spill response, after the Unified Command is established, information related to specific archeological concerns will be coordinated through the Environmental Unit. Before disturbing any soil or sediment during a response action, consult with WDAHP in order to ensure that tactical response strategies do not inadvertently harm culturally sensitive sites. WDAHP and/or the Tribal governments may assign a person, or provide a contact list of professional archeologists, to monitor response activities and cleanup operations for the protection of cultural resources at risk. Due to the sensitive nature of such information, details regarding the location and type of cultural resources present are not included in this document.

NCPS-GRP Cultural Resources Contacts

Contact Phone Email
Washington Department of Archaeology and Historic Preservation (360) 586-3080
Lummi Nation, THPO (360) 312-2257
(360) 961-7752
Muckleshoot Tribe, Archaeologist (253) 876-3272
Nooksack (360) 592-5176

(360) 305-9126

Samish Nation, THPO (360) 293-6404 x126
Sauk-Suiattle (360) 436-0347
Stillaguamish Tribe of Indians (360) 652-3687 x14
Suquamish Tribe, THPO (360) 394-8529
Swinomish Tribe, THPO (360) 466-7352
Tulalip Tribes (425) 239-0182
Upper Skagit (360) 854-7009

Discovery of Human Skeletal Remains
Any human remains, burial sites, or burial-related materials that are discovered during a spill response must be treated with respect at all times (photographing human remains is prohibited to all except the appropriate authorities). Refer to National Historic Preservation Act Compliance Guidelines (NWACP Section 9403) during an emergency response.

Procedures for the Discovery of Cultural Resources
If any person monitoring work activities or involved in spill response believes that they have encountered cultural resources, all workers must stop immediately and notify the Unified Command and Cultural Resource Specialist. The area of work stoppage must be adequate to provide for the security, protection, and integrity of the material or artifact(s) discovered.

Prehistoric Cultural Resources (May include, but are not limited to, any of the following items):

  • Lithic debitage (stone chips and other tool-making byproducts)
  • Flaked or ground stone tools
  • Exotic rock, minerals, or quarries
  • Concentrations of organically stained sediments, charcoal, or ash
  • Fire-modified rock
  • Rock alignments or rock structures
  • Bone (burned, modified, or in association with other bone, artifacts, or features)
  • Shell or shell fragments
  • Petroglyphs and pictographs
  • Fish weirs, fish traps, and prehistoric water craft
  • Culturally modified trees
  • Physical locations or features (traditional cultural properties)
  • Submerged villages sites or artifacts

Historic Cultural Material (May include any of the following items over 50 years old):

  • Bottles, or other glass
  • Cans
  • Ceramics
  • Milled wood, brick, concrete, metal, or other building material
  • Trash dumps
  • Homesteads, building remains
  • Logging, mining, or railroad features
  • Piers, wharves, docks, bridges, dams, or shipwrecks
  • Shipwrecks or other submerged historical objects

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Economic Resources at Risk – Summary

Socio-economic sensitive resources are facilities or locations that rely on a body of water to be economically viable. Because of their location, they could be severely impacted if an oil spill were to occur. Economically sensitive resources are separated into three categories: critical infrastructure, water dependent commercial areas, and water dependent recreation areas. The appendix provides a list of economic resources for this GRP area.

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General Information

Flight Restriction Zones: Flight restriction zones may be recommended by the Environmental Unit (Planning Section), in consultation with the Wildlife Branch, for the purpose of reducing disturbances that could result in injury to wildlife during an oil spill. By keeping a safe distance or altitude from identified sensitive areas, pilots/operators can lessen the risk of aircraft/bird collisions, prevent the accidental hazing of wildlife into oiled areas, and avoid causing the abandonment of nests.

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Implementation of Flight Restriction Zones will take place within the Air Operations Branch (Operations Section) after the Unified Command is formed. The Planning Section’s Environmental Unit will work with the Air Ops Branch Director to resolve any potential conflicts with flight activities that are essential to the spill response effort. Typically, the area within a 1,500-foot radius and below 1,000 feet in altitude is restricted to flying in areas that have been identified as sensitive; however, some areas have more restrictive zones. In addition to restrictions associated with wildlife, Tribal authorities may also request notification when overflights are likely to affect culturally sensitive areas within reservations. See Oil Spill Best Management Practices (NWACP Section 9301) for more information on the use of aircraft and helicopters in open water and shoreline responses.

Wildlife Deterrence: The Wildlife Branch (Operations Section), in consultation with the appropriate trustee agencies and the Environmental Unit, will evaluate wildlife deterrent options for the purpose of keeping wildlife away from oil and cleanup operations and will manage any such activities during a response. Deterrence options might include the use of acoustic or visual deterrent devices, boats, aircraft or other situation-appropriate tools. For more information see the Northwest Wildlife Response Plan (NWACP Section 9310) and Northwest Area Wildlife Deterrence Resources (NWACP Section 9311).

Oiled Wildlife: Attempting to capture oiled wildlife can be hazardous to both personnel and the affected animals. Response personnel should not approach or attempt to recover oiled wildlife. Responders should report their observations of oiled wildlife to the Wildlife Branch so appropriate action can be taken.
Information provided should include the location, date, and time of the sighting, and the estimated number and kind of animals observed. Early on in the response, before a Unified Command is established, oiled wildlife sightings should be reported to Washington Emergency Management Division. For more information see the Northwest Wildlife Response Plan (NWACP Section 9310).

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