U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 049-99

January 2000

Washington

Geologic and Hydrologic Hazards

U.S. Geological Survey (USGS)

activities in Washington have increasingly focused on threats from geologic and hydrologic hazards in the

rapidly growing urban area in northwestern Washington. Volcanic

mudflows, landslides, earthquakes,

and floods may have significant

impacts on the region. The USGS is

developing information for emergency-management agencies, city

planners, and private industry for use

in reduction of human and economic

risks associated with these hazards.

Volcanic Hazards

Mount Rainier poses severe volcanic

hazards to communities as far away

as the Puget Sound, principally in the

forms of volcanic mudflows and

other debris flows that can sweep

down the valleys draining the volcano. Geologic studies (http://

vulcan.wr.usgs.gov/home.html) show

that, during the past few thousand

years, mudflows spanned valley

floors well into the Puget Lowland

about every 500 to 1,000 years. The

USGS addresses these hazards

through projects that determine the

inundation area, frequency and origin

of these flows, and through studies

that investigate the eruptive style and

stability of the volcano.

The USGS, in cooperation with

Pierce County and the University of

Washington, has undertaken a 2-year

pilot project to develop a warning

system to detect mudflows before

they reach threatened communities.

This warning system employs a

network of monitors that measure

high-frequency ground motion

associated with the flows. Upon

detection, the system is intended to

notify emergency-management

officials who then initiate preplanned

emergency responses.

Landslide Hazards

The USGS, the City of Seattle, and a

geotechnical consulting firm under

contract to the city are collaborating

to produce a landslide-hazards map of

Seattle and to establish rainfall

thresholds for predicting the onset of

landslides during storms. Susceptibility to, and potential hazards from,

landslides will be determined using

geological, topographic and materialproperties data.

Earthquake Hazards

The densely populated Puget Lowland faces significant earthquake

hazards. Large tremors have shaken

the area since prehistoric times.

Geologic investigations on southern

Bainbridge Island, for example,

indicate that a magnitude-7 earthquake occurred about 1,100 years ago

on the Seattle Fault. The effects of

that earthquake include 16 to 23 feet

of uplift on the south side of the fault,

subsidence north of the fault in the

Seattle Basin, widespread liquefaction and development of a tsunami.

In 1998, the USGS conducted the

SHIPS (Seismic Hazards in Puget

Sound) experiment (fig. 1) in collaboration with several universities and

Figure 2. Map of active and potentially

active faults in the central Puget

Sound area.

Kitsap

Peninsula Island

Bainbridge ?

Seattle

?

? Elliott

Bay

? ? ?

Vashon Is.

?

? ?

? ?

?

Lake Washington

Puget Sound

0 5 MI

0 5 KM

? Inferred fault

122° 30' 122° 15'

47°

45'

47°

30'

Figure 1. Research vessel Tommy Thompson, collecting seismic-reflection data

in Elliott Bay (Seattle in background) for the SHIPS experiment.
science for a changing world

the Geological Survey of Canada to

reveal the Earth’s structure and faults

(fig. 2) to depths of about 15 miles

below land surface. The USGS is

incorporating information on active

faults and crustal structure, earthquake recurrence, and earthquake-site

response into new seismic-hazard

maps that illustrate the probability of

strong earthquake-induced ground

motions. These maps provide critical

input to the engineering community

for building-code development and

infrastructure design.

Flood Hazards—New Flood-Mapping

Technique

The USGS has developed a new, less

labor-intensive method of producing

flood maps that reduces map-production time while generating maps of

greater detail and comparable accuracy (http://wa.water.usgs.gov/

reports/floodgis). The new method

utilizes geographic information

system (GIS) technology and newly

available high-resolution digitalelevation information. GIS allows

new types of maps to be generated,

such as depth-of-flood maps (fig. 3),

and provides the capability to overlay

other information, such as roads and

land use.

Real-Time Flood Alert and Simulation in

Puyallup River Basin

Pierce County and the USGS have

partnered to develop a streamflow

network and computer model that

alerts the county of impending floods

in the Puyallup River Basin. This

model provides much more detailed

results than those provided by the

existing National Weather Service

(NWS) River Forecast Center model.

Two-day flood forecasts are made

using precipitation and temperature

forecasts from the NWS. A customized user interface provides a graphical display of gage locations where

flood-alert threshold values have been

exceeded.

Environmental Issues

Nutrient Transport to Puget Sound

The USGS, as part of the National

Water-Quality Assessment (NAWQA)

Program (http://wa.water.usgs.gov/

ps.nawqa.html), estimated the annual

nutrient yields for each of the 16

major rivers that drain into Puget

Sound. Yields from rivers draining

the intensive agricultural and populous eastern part of the Puget Sound

Basin are about three times larger

than those from rivers draining the

forested western part of the Basin.

Excess nutrients in Puget Sound can

lead to low dissolved-oxygen concentrations that can adversely affect the

health of fish and other aquatic life.

Contaminants in Fish Tissue and

Streambed Sediments in Streams That

Drain into Puget Sound

An investigation of the occurrence of

organic compounds and trace elements in streambed sediment and fish

tissue and their relation to land use

was a part of the USGS NAWQA

Program. These contaminants accumulate over time in fish tissues and in

fine-grained streambed sediments.

Elevated levels of these contaminants,

many of which are toxic or carcinogenic, were found primarily in

samples obtained from urban streams.

Nitrate Contamination of Central

Columbia Plateau Ground Water

More than 80 percent of the drinking

water in the Central Columbia

Plateau comes from ground water. A

USGS NAWQA study of that area

(http://wa.water.usgs.gov/ccpt)

indicates that nearly 20 percent of the

wells sampled had nitrate concentrations that exceed EPA guidelines.

Nitrogen fertilizers applied to agricultural fields are the primary source of

elevated nitrate concentrations in

shallow ground water. The presence

of elevated concentrations indicates

that pesticides used along with

fertilizers also may be present in the

ground water. In February 1998, the

Columbia Basin Ground Water

Management Area was established

partly to work towards reducing

nitrate concentrations in ground water

(http://wa.water.usgs.gov/colgwma).

Declining Amphibian Populations

Amphibian populations are reported

to be declining worldwide during the

last few decades. Increased mortality

rates among many species are thought

to be the result of their breeding in

open water, where eggs, larvae and

adults are directly exposed to pesticides, herbicides, acidification and

ultraviolet radiation.

In Washington, however, a declining

population of salamanders may be the

result of man’s effort to develop

recreational fisheries. The practice of

stocking fish in several Cascade

Range lakes from the late 1800’s

through the mid-1970’s resulted in

significant reductions in the salamander populations of those lakes.

The fish ingested some of the resident

salamanders, and both species

Figure 3. Digital flood map of Nisqually

River at Interstate 5.

Depth of 100 Year Flood

1 foot deep

2 feet deep

3 feet deep

4 feet deep

5 or more feet deep

EXPLANATION
Washington

competed for the same food supply.

During the last 3 years, salamander

populations have greatly increased at

three lakes on the slopes of Mount

Rainier, where more than 1,500 trout

have been removed by the USGS and

Oregon State University.

Salmon Issues

The USGS Western Fisheries Research Center in Seattle studies fish

and aquatic resources to fulfill the

science-information needs of naturalresource managers throughout the

West. Established in the early 1930’s,

the center is nationally and internationally recognized for research on

fish health, fish ecology, aquatic

contaminants and aquatic ecosystems.

Proposed Strategy for Restoration of

Snake River Fall Chinook Salmon

Fall chinook salmon in the Snake

River are listed as threatened under

the Endangered Species Act. Hells

Canyon, a 100-mile free-flowing

reach of the Snake River, supports

the largest remaining population of

fall chinook salmon in the river. One

strategy for salmon recovery is to

supplement the natural population by

releasing juvenile hatchery fish in

rearing areas. When hatchery fish

return as adults, they spawn naturally, thereby increasing in-river

production. The USGS, in cooperation with the U.S. Fish and Wildlife

Service and the Idaho Fishery

Resource Office, is estimating travel

rates and survival of both hatchery

and wild fall chinook salmon through

the lower Snake River hydropower

system.

Marine Mammal and Salmon

Interactions

Increasing numbers of harbor seals

are feeding on imperiled runs of

chum and chinook salmon in Hood

Canal (fig. 4), a large natural inlet

forming the western portion of Puget

Sound. The USGS Washington

Cooperative Fish and Wildlife

Research Unit, in collaboration with

the Washington State Department of

Fish and Wildlife, is studying seal

foraging at the mouths of five rivers

that flow into Hood Canal. Each river

supports significant salmon runs, and

each has large numbers of harbor

seals near its mouth. Researchers are

trying to determine which categories

of seals (age, gender, etc.) are most

responsible for salmon mortalities.

The results of this research will help

fishery managers devise plans for

reducing seal predation to improve

chances for long-term survival of

salmon stocks.

Restoration of Elwha River Native

Salmon Fisheries:

The Elwha River once was famous

for its salmon and steelhead runs.

Most of these runs ceased to exist

after construction of the Elwha

(1910) and Glines Canyon (1925)

dams. Congress, through passage of

the Elwha Restoration Act, mandated

restoration of these salmon runs. The

Secretary of the Interior, after considering several alternatives, determined

that removal of both dams was the

only alternative that had the potential

to restore the native fisheries.

Samples collected in 1997 by the

USGS, in cooperation with the Lower

Elwha Klallam Tribe and the National

Park Service, indicate that the concentrations of nutrients in the mainstem of the Elwha River, where the

greatest potential for restoration

exists, generally are very low. However, based on predictions that

removal of both dams would significantly increase the available habitat

and the influx of salmon, large

increases in nutrients, sufficient to

support a healthy fishery, would be

expected from decomposing

spawned-out salmon.

Habitat Potential for Endangered Yakima

River Basin Fisheries

Development of management plans

for the recovery of endangered and

threatened fish stocks requires,

among other things, a sound understanding of the hydrology of a river

basin. The hydrology of the Yakima

River Basin (fig. 5) is being studied

as part of the Watershed and River

Systems Management Program, a

collaborative effort between the

USGS and the Bureau of Reclamation

(http://wa.water.usgs.gov/warsmp/

warsmp.html). As part of that project,

preliminary estimates of streamflow

in 59 subbasins have been made to

help determine the distribution of

fish-habitat potential under predevelopment-type conditions

throughout the basin.

Figure 4. A chum salmon glides over the clean gravel bed of Muck Creek in Roy,

Wash., which resulted from a habitat restoration project. Photo: Peter Haley, The

News Tribune.
Printed on recycled paper

USGS office locations USGS State Representative

1201 Pacific Ave., Suite 600

Tacoma, WA 98402

(253) 428-3600, ext. 2602

FAX (253) 428-3614

USGS Home Page

http://www.usgs.gov

Reports and products

1-888-ASK-USGS

Map Products

Ten-Meter Digital-Elevation Models

Topographic data are the foundation

for many water, geological and fish

habitat studies. In 1993, a partnership

was formed among the USGS, the

Washington Department of Natural

Resources (DNR), the USDA Forest

Service and local governments to

complete a statewide coverage of 30-

meter-resolution digital-elevation

data (called Digital-Elevation Models

or DEM’s). More recently, watershedplanning efforts and fish-habitat

studies are increasing the need for

higher-resolution digital representations of terrain data. As a result, new

partnerships have been formed to

create a 10-meter-resolution digitalelevation data base for the State. Tenmeter DEM’s are already available

for parts of western Washington and

are planned to be completed for the

Cascade Range and parts of eastern

Washington by the end of 1999.

Single-Edition Topographic Maps

The USGS and the Forest Service are

cooperatively producing 540

1:24,000-scale single-edition topographic maps that cover National

Forest lands throughout Washington.

USGS and Forest Service base-map

data will be combined to create maps

that contain more detailed landownership and road information than

is present on standard USGS topographic maps. The Forest Service will

assemble, and update as needed, the

various map-data layers, and the

USGS will print and distribute the

resulting maps. Single-edition maps,

like standard USGS products, are

available from map dealers, USGS

Earth Science Information Centers

(http://www-nmd.usgs.gov/esic), and

National Forest Visitor Centers.

Digital Orthophotos

The USGS manages the National

Aerial Photography Program and the

National Digital Orthophoto Program

to ensure the availability of digital

orthophotos. Two other agencies have

participated in the production of

digital orthophotos for Washington

State. The DNR, designated as the

State mapping agency, acquires aerial

photos and produces digital orthophotos for State and private lands in

Washington. The Forest Service

acquires aerial photos and produces

digital orthophotos for National

Forest lands in Washington. To

eliminate duplication of effort,

coordination of these programs began

Figure 5. Fish habitat potential in the

Yakima River Basin.

0 10 20 30 MI

0 10 20 30 KM

CANADA

UNITED STATES

WASHINGTON

EXPLANATION

River miles within basin which

 meet fish habitat criteria 

0

1 – 5

6 – 25

30 – 70

90 – 120

46°

47°30'

121°22'30" 119°15' in 1996. Cooperative programs have

been established to incorporate Forest

Service digital orthophotos into the

USGS national data base and to

convert DNR digital orthophotos to

USGS specifications. Descriptions

and ordering information for aerial

photographs and digital orthophotos

are available through the USGS Earth

Science Information Offices and the

Global Land Information System

(http://edcwww.cr.usgs.gov/webglis/).

Water Resources Data

The USGS, in cooperation with local,

State, and other Federal agencies,

collects and disseminates such water

data as streamflow, reservoir and lake

stage, ground-water levels, water

quality and precipitation. Current and

historical data for Washington are

available at http://wa.water.usgs.gov.

River-stage and flow-rate data are

updated about every 4 hours for more

than 150 streamflow-gaging sites.

During floods, river-stage and flowrate data for over 70 of these sites are

updated every 15 minutes. These data

are used by the NWS, the U.S. Army

Corps of Engineers, and State and

local emergency-management

agencies for forecasting and managing flood fighting, evacuation and

rescue operations.

The USGS has 323

employees in Washington

Port

Angeles

Vancouver

Sedro Woolley

Spokane

Pasco

Tacoma

Seattle

Nordland

Cook