WRIA 7 Snohomish/Skykomish Rivers GRP

  • Open for full review: 2020
  • Tentative publish date: June 2021
  • Interim update: N/A
  • Last full updated: 2013
  • Public Comment: GRPs@ecy.wa.gov
  • Contact: Nora Haider

Table of Contents


Site Description

This section provides a description of the area’s physical features, hydrology, climate and winds, and an oil spill risk assessment for the area. This GRP comprises the northeastern portion of King County and the south central portion of Snohomish County. The WRIA 7 GRP is bordered by the North Central Puget Sound GRP and WRIA 6 to the west, WRIA 4 and 5 to the North, WRIA 8 to the South and WRIA 39 and 45 to the East.

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WRIA 7 is located north and east of the Seattle metropolitan area. The basin is 1,978 square miles in size. Population density is greatest in the western portion of the GRP near the Puget Sound. The major cities within this GRP area are Everett and North Bend. Smaller cities include Arlington, Carnation, Duvall, Granite Falls, Gold Bar, Index, Lake Stevens, Marysville, Monroe, Mukilteo, Sammamish, Skykomish, Snohomish and Sultan.

 Although this GRP encompasses the Snohomish River and its two major tributaries, the Snoqualmie and Skykomish Rivers, response strategies have only been developed for the Snohomish and Skykomish Rivers. Response strategies for the Snoqualmie River will be developed at a later date.

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Physical Features

WRIA 7 is a diverse area that includes many types of habitat, from lowlands on the western portion to mountainous terrain on the eastern edge. Much of the land in the eastern portion of this GRP is rural. Everett, a port historically influenced by the logging trade is located in the far western portion of this geographic response plan. Land use activities within WRIA 7 include mining, agriculture, forestry, manufacturing, and commercial and urban development.

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This geographic response plan area contains lakes and river systems that are biologically rich and sensitive. A wide diversity of bird, fish and mammal species inhabit this area. (Details can be found in Section 6)

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This watershed includes the Snohomish River and its major tributaries; the Snoqualmie and Skykomish Rivers which originate in the Cascade Mountains. The watershed includes various smaller streams such as the Pilchuck, Sultan, Raging, and Tolt Rivers. The South Fork of the Tolt River provides about 30% of the drinking water for the greater Seattle area. The Spada Lake Reservoir on the Sultan River supplies drinking water and electricity to the city of Everett.

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Precipitation is strongly influenced by the Cascade Mountains and is therefore highly variable, ranging from 30 inches per year near Puget Sound, to more than 185 inches per year at the crest of the Cascade Mountains on the eastern edge of the GRP area. Most of this precipitation arrives as snow during the winter months when water demands are the lowest, and only a fraction becomes available for human and economic uses. During the summer when the snowpack is gone there is little rain, so low stream flows are dependent on groundwater inflow. This means that groundwater and surface water are least available when water demands are the highest.

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Climate and Winds

WRIA 7 has a mild maritime influenced climate with cool, wet winters and mild summers. Winds are variable throughout the area with the western portion being affected by marine winds from Puget Sound. Wind speeds often vary by season, with the highest winds generally occurring from November through January. Wind gusts can occasionally reach 50 mph or greater.

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Tides and Currents

The Snohomish River, to at least river mile 16, and the nearby sloughs are affected by the diurnal tidal cycle of Puget Sound. Tides and currents vary with seasonal runoff and lunar cycles in localized areas. Spill responders should consult tide and current tables for particular locations of interest.

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Risk Assessment

WRIA 7 is plentiful in natural, cultural, and economic resources, all at risk of injury from oil spills. Potential risks to these resources include oil pipelines, railroad corridors, and road transportation. Pipelines that transport large quantities of fuel from refineries in Northern Washington to population centers further south are a spill risk within this GRP. One large pipeline passes through the western portion of this GRP and transports refined petroleum products, mainly diesel and gasoline. This pipeline passes under many rivers, creeks, and wetlands and poses a major spill risk to the waterways in this GRP.

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In somewhat the same fashion as pipelines, railroad and truck traffic pose a spill risk within WRIA 7. One of the main east–west transportation routes in Washington bisects WRIA 7. This route goes from Everett to the top of the Cascades at Stevens Pass and facilitates transportation on Highway 2 and the BNSF rail corridor. This rail line and Highway 2 cross waterways and run along the banks of waterways for the entire east-west length of the GRP. Train locomotives typically hold several thousand gallons of diesel fuel plus large quantities of lube and motor oils.  Loaded train tank cars can contain tens of thousands of gallons of crude oil, other petroleum products, or hazardous materials. Presently the volume of oil transported by rail is increasing in the state of Washington, with this increased volume resulting in increased spill risk. Commercial trucks can contain hundreds to thousands of gallons of fuel and oil, especially fully loaded tank trucks.

Other potential risks include vessel incidents in the Snohomish River or Sloughs along the western edge of WRIA 7. These could involve marinas or vessels moored at marinas, including fishing, excursion, and recreational boat refueling incidents; boat or vessel groundings, allisions, or collisions. There are two dams and three hydroelectric generating facilities within this GRP. All of these facilities pose a possible oil spill risk. Land-based spills could also impact resources on or near sensitive shorelines.

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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 section is purposely broad in scope and should not be considered comprehensive. Some of the sensitive resources described in this section cannot be addressed in Response Strategies and Priorities because it is not possible to conduct effective response activities in these locations. Additional information from private organizations or federal, state, tribal, and local government agencies should also be sought during spills.

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, including several islands and a limited amount of nearshore marine area. These habitats support many of Washington’s anadromous salmonid species as well as a complex diversity of other wildlife including mammals, birds, and amphibians. Due to their life histories and/or behaviors, some of these species are unlikely to become directly oiled during a spill incident but may be disturbed by other response operations such as cleanup and reconnaissance. Some of the bird species are resident throughout the year, but many others seasonally migrate through the area.

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Several the species found in this area have been classified under the Federal Endangered Species Act or by the Washington State Fish and Wildlife commission.

Classification types are:

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

Federal and State listed species that may occur within this area include:

  • common loon [SS]
  • marbled murrelet [FT/SE]
  • northern spotted owl [FT/SE]
  • yellow-billed cuckoo [FT/SE]
  • fisher [FC/SE]
  • gray whale (eastern north Pacific) [SS]
  • gray wolf [FE/SE]
  • humpback whale (Central American DPS) [FE/SE]
  • humpback whale (Mexican DPS) [FT/SE]
  • killer whale (southern resident) [FE/SE]
  • wolverine [FC]
  • Bull trout [FT]
  • Chinook salmon (Puget Sound) [FT]
  • green sturgeon [FT]
  • steelhead (Puget Sound) [FT]
  • Oregon spotted frog [FT/SE]
  • whitebark pine [FC]

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:

  • bull trout
  • chinook salmon (Puget Sound)
  • killer whale (southern resident)
  • marbled murrelet
  • northern spotted owl
  • steelhead (Puget Sound)
  • streaked horned lark
  • yellow-billed cuckoo

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General Resource Concerns


  • Salt marshes occur in the sheltered tidal areas throughout the lower Snohomish River. These habitats support a diverse array of fish and wildlife species.
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  • Brackish sloughs and backwater channels provide feeding and resting areas for waterfowl and herons and are rearing areas for juvenile fish.
  • Islands provide important nesting habitat for various bird species, as well as habitat for a variety of mammals. Gravel bars provide spawning habitat for Chinook salmon.
  • Wetlands in this region range from freshwater emergent, freshwater forested, freshwater ponds and lakes. All wetland types support a diverse array of bird, insect and fish and wildlife species.
  • The rivers and streams throughout this region provide spawning and rearing habitat for various salmonid species. The sloughs and delta of the Snohomish River 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.
  • Sandy/rocky shorelines can also be found near the mouth of the Snohomish River. These areas support marine mammal haulout and pupping, nesting for birds, spawning habitat for forage fish.
  • Eelgrass is present in the shallow areas off the mouth of the Snohomish River. Eelgrass serves as important nursery and foraging areas for crab, salmonids, other fishes, and waterfowl.
  • 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.
  • Subtidal Habitats – marine

The shallow intertidal and subtidal habitats occurring at the mouth of the Snohomish River serve as rearing areas for juvenile salmon, Dungeness crab, hardshell clams and other fish and shellfish. These habitats are also often important feeding areas for marine birds, shorebirds, and herons.

  • Soft sediments constitute most of these subtidal marine habitats and include clays, mud, sand, and gravel, typically possessing 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.
  • 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.
  • Subtidal/Subsurface Habitats – brackish/fresh water

Shallow intertidal and subsurface habitats occur in this region, extending from the brackish delta of the Snohomish River to the Cascade crest via the Skykomish River and its tributaries.

  • Fine sediments (mud/silt/sand) – Associated with slow/still water flows. May have aquatic vegetation present. Animals associated with these areas may be salmonid and resident fishes;  birds (dabbling ducks); semi-aquatic mammals (muskrat, beaver, etc.); shellfish (freshwater clams); amphibians and reptiles (frogs, newts, salamanders, turtles, etc.); insects caddis flies, mayflies, dragonflies, and stoneflies). Many other animals also utilize these areas for foraging.
  • Coarse sediments (gravel/cobble) – Associated with moderate water flow. May have aquatic vegetation present. Animals associated with these areas may be salmonid and resident fishes; birds (dippers, harlequin ducks); semi-aquatic mammals (muskrat, beaver, etc.); shellfish (pearlshell mussels, crayfish); amphibians and reptiles (tailed frogs, torrent salamanders; insects caddis flies, stoneflies). Many other animals also utilize these areas for foraging.
  • Bedrock – Associated with fast water with little or no deposition of loose bed materials. Aquatic vegetation not present. Animals associated with these areas tend to be mostly cold-water (salmonid) fishes, birds (dippers, harlequin ducks), and amphibians (torrent salamanders).


  • All Northwest salmonid species are present in this region (including the listed chinook and Coho salmon, bull trout, and steelhead). Spawning occurring throughout the rivers (Snohomish, Skykomish, and Snoqualmie) and the numerous tributaries. Several species of juvenile salmonids use the lower river and shallow nearshore areas extensively for feeding and rearing.
  • Sand lance and surf smelt (aka “forage fish”) spawning occurs on the sand and gravel beaches along the marine margin of this area.
  • Dungeness crab are present off the mouth of the Snohomish River, with shallow subtidal habitats providing critical habitat for all life stages of this species.


  • Bald eagles and great blue herons are nesting residents and may be found year-round throughout the region. A large nesting colony is present in the vicinity of Priest Point. There are also several peregrine falcon nests in the region; this species is more commonly found as a winter and spring visitor to the lower estuary but is also present in the upper Skykomish basin.
  • The lower reach of Snohomish River (in vicinity of Ebey Island) supports significant waterfowl concentrations from fall through spring. Tens of thousands of geese, swans and dabbling ducks may occupy this region during this period. Both resident and migratory waterfowl heavily utilize the islands, sloughs, wetlands and adjacent uplands of the region. The islands in this sub-region also provide nesting habitat for waterfowl.
  • The Snohomish River estuary supports migrating shorebirds such as dunlin and sandpipers during migration periods (April-October).
  • The upper reaches of the Skykomish River and its tributaries provide breeding habitat during the winter and spring months for harlequin ducks. Osprey and northern spotted owl are also found in this same general area.
  • Resident and migratory songbirds heavily utilize riparian habitats year-round and are susceptible to response activities in riparian vegetation, as well as oiling or oil ingestion if riparian vegetation and shorelines become contaminated.
  • Mammals common to the region include deer, elk, and semi-aquatic species (beaver, river otter, mink and raccoon). All these animals are vulnerable to contact with spilled oil. Wolverine, fisher, and mountain goat are also present in the upper Skykomish basin.
  • Harbor seals are common around the mouth of the Snohomish River, with haulout areas located along the southern shoreline. These areas may also be used occasionally by sea lions.
  • Southern resident killer whales may be present in the nearshore areas of this region, especially from October through January. Harbor porpoises are also common in this area. Gray and humpback whales may also be present near the mouth of the Snohomish, feeding in the shallow waters off the mouth of the Snohomish River.

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Specific Geographic Areas of Concern – Overview

  1. Jetty Island. Eelgrass and estuarine wetland habitats. Dungeness crab. Shorebird and waterfowl concentrations (fall through spring). Harbor seal haulouts. Feeding area for gray whales (spring through summer).
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  1. Snohomish Delta. Eelgrass and estuarine wetland habitats. Shorebird and waterfowl concentrations (fall through spring). Great blue heron nesting and foraging area. Harbor seal haulouts. Feeding area for gray whales (spring through summer). Tribal lands and resources.
  2. Qwuloolt Estuary. Salt marsh habitat. Off-channel salmonid rearing habitat restoration. Tribal resources.
  3. Spencer Island. Salt marsh and wetland habitat. Several habitat restoration projects to enhance off channel salmonid habitat. Waterfowl foraging area. Raptors. County park and state wildlife area.
  4. Ebey Island. Slough and wetland habitat. Mixed upland agriculture, shrub and forest vegetation. Salmon spawning and rearing habitat. Waterfowl nesting and rearing habitat. Raptors. State wildlife area.
  5. Fiddler’s Bluff/Bob Heirman Wildlife Park and vicinity. Island, slough and wetland habitats. Mixed upland agriculture, shrub and forest vegetation. Salmon spawning and rearing habitat. Raptors. Waterfowl winter foraging area. Mammals likely present include deer, beaver, otter, etc. County park and state water access site.
  6. Crescent Lake. Slough and wetland habitat. Mixed upland agriculture, shrub and forest vegetation. Salmon spawning and rearing habitat. Waterfowl winter foraging area. Mammals likely present include deer, beaver, otter, etc. State wildlife area.
  7. Cherry Valley Wildlife Area. Riverine and wetland habitat. Mixed upland agriculture, shrub and forest vegetation. Salmon spawning and rearing habitat. Waterfowl winter foraging area. Mammals likely present include deer, beaver, otter, etc. State wildlife area.
  8. Stillwater Wildlife Area. Riverine and wetland habitat. Mixed upland agriculture, shrub and forest vegetation. Salmon spawning and rearing habitat. Waterfowl foraging area. Mammals likely present include deer, beaver, otter, etc. State wildlife area.
  9. Chinook Bend Natural Area. Riverine and wetland habitat. Mixed upland grassland, shrub and forest vegetation. Salmon spawning and rearing habitat. Restoration sites. County Park.

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Specific Geographic Areas of Concern – Maps and Descriptions

Figure 1: Areas of concern within the WRIA 7 GRP area (see text for details).

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Figure 2: Areas of concern within the WRIA 7 GRP area (see text for details).

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Cultural Resources at Risk – Summary

Culturally significant resources are present within the planning area. Information regarding the type and location of cultural resources is maintained by the Washington Department of Archeology and Historic Preservation (WDAHP). This sensitive information is made 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.  In order to ensure that tactical response strategies do not inadvertently harm culturally sensitive sites, WDAHP should be consulted before disturbing any soil or sediment during a response action, including submerged soils or sediments.  WDAHP and/or the Tribal governments may assign a person, or provide a list of professional archeologists that can be contracted, 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.

Table 6-1: WRIA 7-GRP Cultural Resources Contacts

Contact Phone Email
 Washington Department of   Archeology and Historic   Preservation (WDAHP)  360-384-1489  Rob.Whitlam@dahp.wa.gov
 Muckleshoot Indian Tribe  253-939-3311


 Samish Indian Nation  360-293-6404

360-293-6404   ext. 126

 Sauk-Suiattle Indian   Tribe  360-436-0131


 Snoqualmie Tribe  425-888-6551  Steve@snoqualmietribe.us
 Squaxin Island Tribe
 Stillaguamish Tribe of   Indians  360-652-7362


 Suquamish Tribe  360-598-3311


 Swinomish Indian Tribal   Community  360-466-3163


 Tulalip Tribes  1-800-869-8287




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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Fish hatcheries and infrastructure

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General Information

Flight restriction zones: The Environmental Unit (Planning Section) may recommend flight restriction zones to minimize disturbance or injury to wildlife during an oil spill. Pilots/operators can decrease the risk of aircraft/bird collisions, prevent the accidental driving of wildlife into oiled areas, and minimize abandonment of nests by keeping a safe distance and altitude from these identified sensitive areas.

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The Air Operations Branch (Operations Section) will manage all aircraft operations related to a response and will coordinate the establishment of any Flight Restriction Zones as appropriate. Environmental Unit staff will work with the Air Operations Branch Director to resolve any conflicts that arise between flight activities and sensitive resources.

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 Deterrence Unit within the Wildlife Branch (Operations Section) manages wildlife deterrence operations. These are actions intended to minimize injuries to wildlife by keeping animals away from the oil and cleanup operations. Deterrence activities may include using acoustic or visual deterrent devices, boats, aircraft or other tools. The Wildlife Branch works with state and federal agencies, and the Environmental Unit (Planning Section), to develop deterrence plans as appropriate.

For more information see the Northwest Wildlife Response Plan (NWACP Section 9310) and Northwest Area Wildlife Deterrence Resources (NWACP Section 9311).

Oiled Wildlife: Capturing oiled wildlife may be hazardous to both personnel and the affected animals. Incident personnel should not try to approach or capture oiled wildlife but should report any observations of oiled wildlife to the Wildlife Branch (Operations Section).

For more information see the Northwest Wildlife Response Plan (NWACP Section 9310).

Wildlife Refuges and Wilderness Areas: There are three federally designated wilderness areas present in the vicinity of this GRP region including the Wild Sky Wilderness, Henry M. Jackson Wilderness, and Alpine Lakes Wilderness.

Aquatic Invasive Species: The waters of this region may contain aquatic invasive species (AIS) – species of plants and/or animals that are not native to an area and that can be harmful to an area’s ecosystem. If so, preventative actions may be required to prevent the spread of these species as a result of spill response activities and the Environmental Unit is able to recommend operational techniques and strategies to assist with this issue.

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