Palouse GRP

Table of Contents


Site Description

This section provides a description of the physical features, hydrology, climate, and winds found within the Palouse GRP planning area, and an oil spill risk assessment in Section 2.6. The Palouse GRP planning area is approximately 253 square miles, and resides within the boundaries of Adams, Franklin, and Whitman Counties. Fully or partially, it includes the towns or cities of Hooper and Benge. Portions of WRIA-34 (Palouse) fall within this planning area, and includes: Palouse River, South Cow Creek, Union Flat Creek, and Willow Creek. No tribal reservations are located within the planning area, but the Coeur D’Alene, Colville, Nez Perce, and Spokane Tribes all have potential interests in this area. Highway 26 is the only major roadway. The Palouse and Coulee City Railroad, Palouse River Railroad, and Union Pacific Railroad are the only companies that own railroad track in the area. No contingency plan holding oil facilities or pipelines are located within the boundaries of this planning area. The Palouse GRP is bordered by the Snake River Lower Monumental GRP to the south.

Physical Features

Volcanic activity built up a stratum of mud, ash, and lava in the geologic column in the area now known as eastern and central Washington and Oregon during the Eocene (55.8-33.9 million years ago), Oligocene (33.9-23 million years ago), and Miocene (23-5.3 million years ago) Epochs (UCMP).  Basalt flows, known as the Columbia River Basalt Group, then covered the area in layers forming a strong foundation of basaltic rock at least one mile thick (IAFA 2008). Subsequent lava and ash eruptions raised the Cascade Mountains during the Miocene Epoch, and the mountains began to lift when hundreds of volcanoes erupted during the Pleistocene Epoch (2.6 million – 11,700 years ago). As the mountains rose, the Columbia and Snake Rivers carved out deep gorges. Towards the end of the Pleistocene (~16,000-14,000 years ago) the Missoula floods battered the area over 100 times when the glacial dam forming Glacial Lake Missoula was repeatedly breached, releasing high velocity debris-filled waters to a height of 900 feet and scouring the landscape with a discharge of 10 million cubic feet per second (Lee 2009). This series of events has been described as one of the greatest flood occurrences in the history of the earth (WEMD).

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As the previous paragraph describes, the geologic history of this area has produced a rather dramatic landscape. This area, sometimes referred to as the scablands, is characterized by elevated tracts of rocky land with little or no soil cover. Large, deep canyons have been formed through the elevated basalt layers. The most significant of these in this GRP planning area is the Palouse River Canyon and the associated Palouse River Falls. Huge pre-flood cracks in the basalt allowed the Glacial Lake Missoula floods to carve the spectacular Palouse River Canyon (IAFA 2008). Near-vertical basalt walls tower over the river. At one point the river flows over a 200-foot cliff, creating the majestic Palouse Falls. Other significant physical features of this planning area include Holiday Coulee, South Cow Creek, Union Flat Creek, Willow Creek, and Winn Lake Canyon. Land use in the area is mostly confined to the river bottoms, where some irrigated farmlands are present. The small towns of Hopper and Benge, and Palouse Falls State Park also fall within this planning area.

This area of the state is rich with cultural history. Thousands of archaeological sites spanning over 13,000 years have been recorded in the Scablands and Plateau region (Stilson, Meatte, and Whitlam 2003). One of the most significant archaeological sites in Washington lies less than 2 miles south of this GRP planning area. The Marmes Rockshelter was home to humans as long as 11,230 years ago, and was inhabited steadily for nearly 8,000 years (Hicks 2004).

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The Palouse River drains the approximately 2,700-square-mile Palouse watershed. The watershed slopes from west to east with several points above 3,000 feet in elevation found along the border with Idaho (Whitman County). The planning area is located in the southwestern part of the watershed, near the point where the Palouse River flows into the Snake River. The area experiences the bulk of its annual precipitation in the fall and winter, but the peak flows are in the winter and spring. There is one USGS station in the planning area tracking velocity and river height, located at the town of Hooper at river mile 19.5. This gage shows that the highest flow is in March, with an average flow from 1,600 cubic feet per second (cfs), and a monthly low of 30 cfs in August (USGS).

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The planning area resides entirely within Water Resource Inventory Area Palouse (WRIA 34).

Palouse (WRIA 34): The Palouse Watershed, also known as Water Resource Inventory Area 34 (WRIA 34), is located in eastern Washington and includes the Palouse River and its numerous tributary creeks and streams. The Palouse River originates in the mountains of Idaho. The annual precipitation in the Palouse Watershed ranges from 10 inches per year near its confluence with the Snake River, to 20 inches in the higher elevations along the Idaho border. Only a fraction of this precipitation becomes groundwater available for human and economic uses. Most of the precipitation arrives during the winter months, when water demands are the lowest. During the summer, the snowpack is gone, there is little rain, and naturally low stream flows are dependent on groundwater inflow. This means that groundwater and surface water are least available when water demands are the highest (WA Dept. of Ecology).

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Climate and Winds

The temperatures in the Palouse River area vary dramatically, with winter lows below freezing, and highs in the low 80s from July to August. The Palouse averages 35 inches of snowfall in the winter months, but six inches of accumulation. Total precipitation averages 17 inches annually (NOAA).

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Wind speed at Pullman-Moscow Airport averages 7.3 mph. Winds in the area tend to blow from the southwest year-round. However, in the summer, the wind can blow from the north at times. Whitman County experiences elevated wind speeds, typically in the fall, with wind gusts reaching 46 mph. In 2016, the highest wind speed was recorded at 37 mph in October (WRCC 2016).

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Tides and Currents

The flow speed on the Palouse River at the Hooper gage (river mile 19.5) is seven mph at the annual mean velocity of 500 cfs. Each portion of the river – and its tributaries Cow and Willow Creeks – will have faster or slower speeds based on a variety of factors, including channel width, channel depth, debris blockages, and elevation change, among others. The Palouse River does not experience any tidal influence.

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Risk Assessment

The Palouse area is plentiful in natural, cultural, and economic resources, all at risk of injury from oil spills. Potential oil spill risks include, but are not limited to, road transportation, rail transportation, aircraft, and other oil spill risks. This section briefly discusses these risks and how they could impact the GRP planning area.

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Oil Types: Both refined petroleum products and crude oil are transported in bulk within this planning area.

Crude oil and refined products contain a mix of hydrocarbons with varying properties; different types of crude oil and refined products will behave differently when spilled. Recent changes in oil production have led to an increase in the movement of Bakken light crude transported through the planning area via rail, and diluted bitumen from Canada transported through the planning area via pipeline and, to a lesser extent, rail.

Crude oil from the Bakken fields in North Dakota has properties similar to gasoline or diesel, and poses a higher risk of fire because much of it will evaporate quickly into flammable vapors. Unlike gasoline, the heavier hydrocarbons in the crude will persist in the environment after the light ends evaporate or burn. Bitumen from the oil sands in Alberta, Canada, is heavy, almost asphalt-like, until it is mixed with lighter oil products known as diluents to create diluted bitumen. Once mixed, the diluted bitumen will initially float on water after being spilled. Environmental conditions, such as the density of the receiving waters and sediment load of the receiving waters, will affect how long diluted bitumen floats. As the light diluents evaporate, the remaining heavy constituents may sink into the water column(NASEM 2013). There are specific response actions recommended for non-floating oils, detailed in the Non-Floating Oil Spill Response Tool in the Northwest Area Contingency Plan (NWACP), Section 9412.

Road Systems: Vehicle traffic on roadways pose an oil spill risk in areas where they run adjacent to the shorelines, or cross over lakes, rivers, creeks, and ditches, that drain into the Palouse River. While there are no federal highways that pass through the planning area, there are two state routes: 26 and 261. State Route 26 runs through the center of the planning area from west to east. The highway mostly parallels the Palouse River until it crosses the river at river mile 25.8 and then follows Willow Creek. Also, State Route 261 passes through the southernmost portion of the planning area before crossing the Snake River.

A vehicle spill onto one of these bridges or roadways can cause fuel or oil to flow from hardened surfaces into the Palouse River or its tributaries. 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 waste 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.

Rail Transportation and Facilities: Rail companies transport oil via both unit trains and manifest trains in 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.Union Pacific (UP) owns nearly all commercial railroad track within the Palouse GRP area. The railroad’s Ayer Subdivision runs from north to south along Cow Creek and the Palouse River before reaching the Snake River. The Palouse River Railroad is the only other operator in the planning area.

Aircraft: There are four state-managed airports within a 15-mile radius of the Palouse GRP area: Lind Field, Little Goose Lock and Dam, Lower Monumental, and Pru Field. All are primarily used for recreational and transportation purposes. The potential exists for aircraft failures during inbound or outbound flights that result in a spill by releasing aviation fuel to the Palouse River or one of its tributary streams (WSDOT).

Other Spill Risks: Other potential oil spill risks in the area include fuel storage areas (including waste oil storage), road run-off during rain events, on-land activities where heavy equipment is being operated or stored, and the migration of spilled oil through soil on lands adjacent to the river or its tributary streams.

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Resources at Risk

This section provides a summary of natural, cultural, and economic resources at risk in the planning area. It provides general information on habitat, fish, and wildlife resources, and locations in the area where sensitive natural resource concerns exist. 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 chapter.

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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 chapter cannot be addressed in Section 4 (Response Strategies and Priorities) because it’s 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.

The information provided in this chapter can be used in:

  • Assisting the Environmental Unit (EU) and Operations in developing additional response strategies beyond those found in Section 4.
  • 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.

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Natural Resources at Risk – Summary

Most biological communities are susceptible to the effects of oil spills. Plant communities on land, aquatic plants; microscopic plants and animals; and larger animals, such as fish, amphibians and reptiles, birds, mammals, and a wide variety of invertebrates, are all potentially at risk from smothering, acute toxicity, and/or the chronic long-term effects that may result from being exposed to spilled oil.

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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 mammals, birds, 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. 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, with the abbreviation of each type provided in the brackets (to the right of the classification).

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

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


  • Common loon [SS]
  • Greater sage-grouse [ST]*
  • Yellow-billed cuckoo [FT]*


  • None


  • Bull trout [FT]
  • Chinook [FT]
  • Steelhead [FT]


  • Spalding’s catchfly [FT]

* Unlikely to be directly oiled during a spill incident.

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General Resource Concerns


  • Rivers and streams are important habitat features throughout in this semi-arid region and support numerous wildlife species including resident fish. Anadromous fish distribution in the Palouse River is limited to below Palouse Falls. Passerine birds commonly nest in riparian habitats during the spring and summer.
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  • Wetlands in this region support a diverse array of birds, insect and fish and wildlife species.
  • Shrub-steppe habitat in this region supports many species of wildlife, including some that can only be found in these semi-arid communities – such as greater sage-grouse, sage sparrow, and sage thrasher.


  • Resident species including trout (cutthroat and rainbow) and various warm water species (bass, walleye, etc.) are also present throughout this area.
  • Anadromous species including Chinook and steelhead can be found below Palouse Falls.


  • Mule deer concentrations typically present from the fall through spring.
  • Washington ground squirrels are present throughout the area.
  • Waterfowl concentrations of various species may be found throughout the region in wetlands and agricultural fields near rivers, creeks, and ponds.
  • Passerine bird commonly nest in riparian habitat during the spring and summer.


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Specific Geographic Areas of Concern – Overview

(Note: May include sensitive sites in bordering GRP regions – see map at end of chapter)

  1. Cow Creek and associated wetlands: Riverine, riparian and wetland habitats. Resident fish. Burrowing owls. Washington ground squirrels. Waterfowl concentration when water present in creek and ponds (primarily during spring).
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  1. Palouse River (near Hooper along Hwy 26): Riverine, riparian, and wetland habitats. Year round waterfowl concentration area with significant increases during winter. Resident fish presence. Winter deer concentration area.
  2. Lyons Ferry/Palouse Falls State Park and associated wetlands: Riverine, riparian, shrub-steppe, and wetland habitat. Salmonid presence (Chinook salmon, bull trout, Dolly Varden, and steelhead trout) below Palouse Falls. Resident fish also present. Important winter deer concentration area. Waterfowl concentration area (nesting and migration). Heron foraging area.


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Specific Geographic Areas of Concern – Maps and Descriptions

Figure 1: Specific geographic areas of concern for the Palouse GRP.


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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. 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. Due to the sensitive nature of such information, details regarding the location and type of cultural resources present are not included in this document.

Contact Phone Email
Washington Department of Archaeology and Historic Preservation (360) 586-3080
Confederated Tribes of the Colville Reservation, THPO (509) 634-2695
Coeur D’Alene Tribe, THPO (208) 686-1572
Nez Perce Tribe, Spill Responder and Water Quality (208) 621-3893
Spokane Tribe of Indians, THPO (509) 258-4315
Confederated Tribes of the Umatilla Indian Reservation (541) 276-4348
Confederated Tribes of the Yakama Indian Nation (509) 865-5121

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 Section 9403 of the Northwest Area Contingency Plan for National Historic Preservation Act Compliance Guidelines 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 work must be stopped immediately and the Incident Commander and Cultural Resource Specialist notified. 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)

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


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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.

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General Information

Flight Restriction Zones: Flight restriction zones may be recommended by the Environmental Unit (Planning Section) 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 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 a 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 Section 9301.3.2 and Section 9301.3.3 of the Northwest Area Contingency Plan for more information on the use of aircraft and helicopters in open water and shoreline responses.

Wildlife Deterrence: After a Unified Command is formed, 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 un-oiled birds away from oil during a spill. The “Bird Deterrence Unit” in the Wildlife Branch would participate in operations. 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 the animal and the person attempting the capture it. 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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