Appendix K

Catastrophic Risk Assessment of Lower Columbia and Willamette River ESUs
for Endangered and Threatened Pacific Salmon

***Thomas P. Good and Juliet Fabbri***

***National Marine Fisheries Service, Northwest Fisheries Science
Center***

Introduction

Catastrophic events are among the factors, along with long-term
demographic processes and evolutionary potential, that need to be
considered when relating viable salmonid populations (VSPs) to viable
evolutionarily significant units (ESUs). Catastrophes are sudden
(within-season) events that eliminate or severely reduce (by up to 75%)
adult populations (McElhany et al. 2000). A variety of natural and
anthropogenic catastrophic events occurring intermittently over
evolutionary time scales can have long-term consequences. If preceded by
gradual climatic change or overfishing, these events may result in
ecosystem shifts (Scheffer et al. 2001). Natural catastrophes include
volcanoes, earthquakes, floods, landslides, extreme weather (droughts),
unusual fires, and disease epidemics. Anthropogenic catastrophic events
include oil/chemical spills, dam construction or diversion/dam failure,
floods, disease epidemics from hatcheries, and major miscalculations in
harvest. Some catastrophic events can also result from the interaction
of natural and anthropogenic factors.

The number of threats facing salmonid populations suggests that
catastrophes may have a substantial influence on extinction risk. Salmon
have enhanced their long-term stability in the face of ice ages,
continental uplifts, and volcanic eruptions by maintaining diverse
populations, habitats, and life-history diversity, thus spreading risk
and providing redundancy (Levin and Schiewe 2001). The risk of
extinction posed by catastrophic events for an entire ESU can be
estimated by evaluating risk for separate populations (McElhany et al.
2000) as well as for nearby populations (correlated risks).

Catastrophic events are not commonly considered a part of species
listing or recovery plans. Of 181 recovery plans reviewed by a National
Center for Ecological Analysis and Synthesis (NCEAS) working group, 13
(≈ 7%) cited catastrophes/stochastic events as a factor in the listing
decision, and 57 (≈ 31%) cited catastrophes/stochastic events as a
factor in the recovery plan. (www.nceas.ucsb.edu/recovery/data). Only 31
(≈ 17%) listed catastrophes/ stochastic events as a major threat;
however, 51% of those plans assigned the highest implementation priority
to tasks that address these factors. Catastrophic events are of primary
importance in a small number of cases; for example, the recovery plan
for the federally listed sea otter in California identified catastrophic
oil spills as the primary risk to population viability, with
quantitative estimates of risks from oil spills forming the basis of the
recovery goals (Ralls et al. 1996).

While catastrophic events vary in frequency, scope, and impact, they
share features that make them amenable to quantification and of
potential importance for salmon populations. This document investigates
a variety of natural and anthropogenic catastrophes in order to make
quantitative and qualitative assessments of catastrophic risk for
threatened and endangered Pacific salmonid ESUs in the Lower Columbia
and Upper Willamette Rivers, specifically chinook salmon (*Oncorhynchus
tshawytscha*), steelhead trout (*O. mykiss*), and chum salmon (*O.
keta*). Herein, we analyze catastrophic risks from volcanoes, glacial
outbursts, earthquakes, landslides, disease epidemics from hatchery
operations, and transportation oil/chemical spills. Risks from floods,
fire, pollution from oil/chemical storage, and from land use (industrial
zoning, pesticide use) are being analyzed to more fully understand the
suite of catastrophic risks that exist for these endangered Pacific
salmonid ESUs in the Lower Columbia and Upper Willamette Rivers.

Volcanoes and Glacial Outbursts

Volcanoes

Volcanoes and flows of water, mud, and debris associated with glaciers
pose a considerable risk to populations in watersheds that emanate from
the chain of volcanic mountains in the Cascade Mountains. In fact, Mount
Rainier is considered an extremely dangerous volcano (Perkins 2001).
Volcanic activity epitomizes extreme unpredictability--- catastrophic
events that may be statistically predictable, but only in time intervals
much longer than the generation time of salmonids (Thorpe 1994). These
catastrophic risks have an occurrence interval of 100--1,000 years
(Bisson et al. 1997), and they can have devastating consequences for
salmonids, especially in watersheds close to an eruption. Volcanism can
result a variety of chemical and physical alterations, including
increased delivery of fine sediments and organic matter, scouring of
channels from mudflows, formation of mudflow terraces along rivers,
destruction of riparian vegetation, damming of streams, and the
potential creation of new lakes (NRC 1996). The effects on the salmon's
habitat include sedimentation of spawning gravels, loss of pool habitats
from mudflows, short-term lethal levels of sediment and temperature
during eruptions, and formation of migration blockages. Potential
positive effects include creation of pool habitat in areas with tree
blowdowns, creation of new overwintering habitat and side channels along
mudflow terraces, and long-term benefits to lake-dwelling species (NRC
1996). Physical, biological, and chemical changes resulting from even
modest volcanic eruptions can be extreme (Dorava and Milner 1999).

The 18 May 1980 eruption of Mount St. Helens in 1980 provides examples
of the potential short and long-term consequences of volcanic activity.
The effects of the Mount St. Helens eruption were dramatic and variable.
The eruption damaged over 500 km^2^ of forest and riparian vegetation,
sending water temperatures soaring to 26˚C on some streams (Lucas 1986),
and increasing hillside erosion, due to a lack of groundcover,
contributed to stream bedloads. The resultant debris flow extended 24 km
down the North Fork Toutle River, and mudflows buried stream channels in
the North and South Fork Toutle Rivers, eliminating fish habitat (Lucas
1986). With the North Fork Toutle River buried to an average depth of 47
m (maximum 183 m), and smaller mudflows in the South Fork Toutle River
and parts of the upper Lewis River and Kalama River, increased water
levels flooded the Toutle and Cowlitz River Basins. Mudflow deposits
that clogged the channels of the Cowlitz River also led to water
temperatures in the lower reaches exceeding 32˚C. Lahars reduced the
flood-stage capacity at Castle Rock on the Cowlitz River from 76,000
cubic feet per second (cfs) to less than 15,000 cfs, and reduced channel
depth on the Columbia River (12 to 4.25 m), stranding 31 ships in
upstream ports (Leider 1989).

Effects of the Mount St. Helens eruptions on salmonids were dramatic and
variable; recovery of salmonid populations after volcanic eruptions can
potentially be relatively quick due to temporary food abundances,
recolonization potential, and relative scarcity of predators and
competitors (Bisson et al. 1997). However, the majority of aquatic life
in the Toutle River watershed was probably eliminated immediately
(Leider 1989). Additional fatalities included approximately 12 million
salmon fingerlings in hatcheries (Brantley and Myers 2000) as well as
increased summer and winter mortality of stocked juvenile coho salmon
related to high stream temperatures and the lack of large organic
debris, respectively (Martin et al. 1986). Production of stocked
juvenile coho in three impacted third-order streams increased annually,
peaked six years after the eruption, and declined to normal thereafter
(Bisson et al. 1988, 1997). Reduced invertebrate communities resulted in
food impacts for subyearling chinook in the Columbia River estuary in
1980 and 1981, although effects on food resources were believed to be
short-term (Kirn et al. 1986). Increased straying of fish to unaffected
streams and rivers can result from blocked access to spawning grounds;
many fish initially avoided the Toutle River and strayed extensively
into other Columbia River tributaries (Lucas 1986), and the percentage
of nonnatal steelhead in unaffected Columbia River tributaries increased
from 16% to 45% (both winter and summer runs) (Leider 1989). Straying to
the Kalama River and the North Fork Lewis River was also extensive, and
the decline in fish numbers in the Cowlitz River continued to 1983--1984
before reverting to pre-eruption levels (Leider 1989).

Recent eruptions in a chain of volcanoes west of Cook Inlet, Alaska,
further exemplify the direct and indirect effects on salmonids,
including changes to water quality, channel geometry, and riparian
vegetation (Dorava and Milner 1999). During the 1989--1990 Redoubt
Volcano eruption, the riparian zone was removed or killed in place by
lahars, which reduced allochthonous input and, subsequently, primary and
secondary production. Such habitat decreases or degradation can persist
for years, and subsequent effects include initial migratory impediments
from lahar deposits, unstable streambeds, and silt in spawning gravel
beds (Dorava and Milner 1999). Salmon populations were likely seriously
affected due to changes to fish access. Thick deposits of fine sediment
modified large channels and spawning sites, and food sources were
eliminated for rearing fish. Being washed out by mud and debris flows
likely immediately killed juveniles and affected future spawning
activities. Food sources were subsequently eliminated for rearing fish.
Although macroinvertebrate communities can recover as early as five
years after a major volcanic eruption, it is not clear whether these are
stable communities. Upstream sources of macroinvertebrates can hasten a
return to normalcy as well, but comparison among volcanoes is
problematic---macroinvertebrate recolonization at Mount St. Helens began
rapidly but took place over a long time.

Glacial Outbursts

Glacial outbursts, from the sudden release of water stored within or at
the base of glaciers, pose a serious hazard in river valleys on
volcanoes. Glacial outbursts at Mount Rainier can be unrelated to
volcanic activity, and the peak discharge of outbursts may be greater
than

that of extreme meteorological floods. At least 36 outburst floods have
been recorded from the Kautz, Nisqually, South Tahoma, and Winthrop
Glaciers on Mount Rainier during the twenthieth century, destroying
bridges, roads, and Mt. Rainier National Park visitor facilities 10
times since 1926. Well-studied outbursts---from South Tahoma
Glacier---are correlated with periods of unusually high temperatures or
heavy rain in summer or early autumn (Hoblitt 1998). Many of these
glacial outburst floods transform to lahars by incorporating large
quantities of sediment from channel walls and beds; consequently, they
are included with lahars for purposes of hazard zonation (Hoblitt 1998).
Discharges of water and debris have also occurred at Mount Hood,
resulting in significant losses of salmonid spawning and rearing habitat
on the East Fork of the Hood River (Kostow et al. 2000).

Earthquakes

Earthquakes, and secondary landslide hazards associated with ground
motion, pose a risk to populations in watersheds associated with the
offshore Cascadia subduction zone and to some extent with the Cascade
Range volcanoes. Little literature exists on direct or indirect effects
of earthquakes on Pacific salmonids. The hazard posed by ground shaking
and related secondary damage to watersheds, and the fish habitat
contained therein, has been estimated and can be used as a proxy for
damage to fish resources.

Each year more than 1,000 earthquakes are recorded in Washington State,
with 15 to 20 causing substantial ground shaking. Destructive
earthquakes occur much less often; the last earthquake to cause
widespread damage in Washington occurred in 1965. Larger earthquakes may
have occurred every several hundred or thousand years in the Pacific
Northwest; the most recent such earthquake occurred about 300 years ago
(Noson et al. 1988). The effects of earthquakes include burial of nearby
valley floors; such an avalanche was triggered by a moderate (magnitude
5) earthquake, which followed eight weeks of intense seismic activity
beneath Mount St. Helens during the 18 May 1980 volcanic eruption (Noson
et al. 1988).

Earthquakes may result in secondary damage from landslides (see
"Landslides" below), such as the 14 earthquakes large enough to trigger
landslides in Washington from 1872 to 1980. Earthquakes on Mount
Rainier, Mount St. Helens, and around Puget Sound have been known to
trigger landslides, and ground shaking produced by earthquakes can
weaken and collapse bluffs. Future earthquakes in Washington are
expected to generate more landslides and greater habitat changes than
those reported for past earthquakes (Noson et al. 1988).

Earthquakes off the Pacific Northwest coast may also result in tsunamis
when large, rapid movements in the seafloor displace the water column
above, thus setting off the destructive waves. Offshore tsunamis can
strike adjacent shorelines within minutes and cross the ocean at speeds
of up to 600 mph. A 1946 earthquake in the Aleutian Islands of Alaska
initiated a tsunami that reached Hawaii in less than five hours, had
waves as high as 55 feet, and killed 173 people (Manson and Walkling
1998). A dozen very large earthquakes (magnitudes ≥ 8) have occurred in
the Cascadia subduction zone. On the Pacific Northwest coast, risks
exist from distant and local tsunamis and computer models indicate that
tsunami waves generated by local events might reach 55 feet and affect
the entire coastal region (Manson and Walkling 1998).

Landslides

Washington has many sites susceptible to landslides, including steep
rocky slopes along the Columbia Gorge and rugged terrain in the Cascade
Mountains. Although landslides are propelled by gravity, they can be
triggered by geologic or anthropogenic forces. Volcanic eruptions can
initiate earth movement on a grand scale, particularly lahars, mixtures
of volcanic ash and water. Cascade volcanoes offer many sites for rock
and ice avalanches, rock falls, and debris flows on their steep slopes.
They are particularly vulnerable to landslides because of the layered
and jointed volcanic rocks lying parallel to the mountain slopes,
weakened by the effects of steam and hot groundwater and oversteepened
by erosion. In addition, icefalls from glaciers can trigger landslides,
and snow and ice add to the mobility of such slides.

The 1949 Olympia earthquake generated more than 20 landslides, as far as
180 km from the epicenter; the 1965 Seattle/Tacoma earthquake generated
21 landslides, as far as 100 km from the epicenter. Fourteen earthquakes
from 1872 to 1980 are known to have triggered landslides in Washington.
Landslides on Mount Rainier were reported for earthquakes in 1894, 1903,
and 1917, and a massive 2.8-km^3^ rockslide/debris avalanche on the
north side of Mount St. Helens during the catastrophic eruption of 18
May 1980 was triggered by a moderate (magnitude 5) earthquake that
followed eight weeks of intense earthquake activity beneath the volcano.
Sudden water displacement from landslides can also generate destructive
water waves, such as occurred when a 300-foot bluff along the Tacoma
Narrows, weakened by the 1949 earthquake, collapsed into Puget Sound
three days later. Future earthquakes in Washington are expected to
generate more landslides than were reported for the 1949 or 1965
earthquakes, when rainy-season precipitation was near or below average
throughout the Puget Sound area.

Earthquakes notwithstanding, the major causes of landslides in the
Northwest are continuous rains that saturate soils. Mud and debris flows
are frequently the direct consequence of human activity. Seemingly
insignificant modifications of surface flow and drainage may induce
landslides, and building placement may lead to the loss of structures.
In Portland, population pressure has pushed housing and highway
construction into landslide-prone areas, where improper drainage induces
disastrous sliding. Landslides result from agricultural irrigation and
clearcutting of forests from naturally steep slopes. A 1996 Forest
Service study of 244 landslides found that 91 were associated with
logged-over lands, 93 with roads, and 59 in undisturbed forests; the
combination of logging and road-building increases slide frequency
fivefold over a 20-year period compared to undisturbed forested lands.
Most of the 250 landslides in the Clackamas River watershed and in the
Mount Hood National Forest during the floods of 1996 were in lands
logged over or criss-crossed by dirt logging roads
(http://www.oregongeology.com/landslide/landslidehome.htm).

The impact of landslides on stream drainages and reservoirs can pose
significant risk to downstream areas. Landslides or debris flows into
reservoirs or lakes may displace enough water to cause severe downstream
flooding, and water ponded behind landslide-debris dams can cause severe
floods when these natural dams are suddenly breached. Such outburst
floods are most likely near volcanic centers active within the past 2
million years; the Toutle River was blocked by a debris flow triggered
by an earthquake during the 1980 eruption of Mount St. Helens. The
debris flow dam raised the level of Spirit Lake by 60 m, requiring the
U.S. Army Corps of Engineers to construct a tunnel through bedrock to
lower the lake level and reduce flood danger from a sudden release of
water (Crandell and Mullineaux 1978).

Disease Epidemics from Hatchery Operations

Characteristics of host-pathogen interactions make disease epidemics
potentially catastrophic events. Host-pathogen interactions are
understudied and often indiscernible in the wild, and disease epidemics
occur seemingly out of nowhere. While documentation of chronic
background levels of diseases provides information on the past, future
risks from new and deadly pathogens/parasites may be unrelated to past
events. Moreover, while there is much information on disease incidence
and effects on hatchery salmon and steelhead, our understanding of the
effects of disease on released hatchery fish and interaction with wild
fish is not well understood (NRC 1996).

Fish and pathogen strains have generally co-evolved in a way that common
microorganisms do not kill the hosts (Schreck 1996). However, mutations
may result in abnormally virulent strains and a series of mutual
population expansions and crashes, not unlike predator/prey
interactions. Epidemics may burn themselves out because hosts die, and
thus pathogen density decreases and cannot be transmitted effectively,
or there may be no loss of virulence, only a low rate of infection.
Although it is recognized that pathogens reside in wild populations and
that diseases are transferred between wild and hatchery fish, the
initial introduction of pathogens into a population results largely from
infected fish being moved by humans into susceptible populations (Reno
1998).

Variable susceptibility to pathogens is, in part, inherited, and wide
variation exists in response to pathogen challenge in wild fish because
of their wide genetic background (Anderson 1996). Individual differences
have been identified in wild stocks and among hatchery strains (Beacham
and Evelyn 1992). The variable susceptibility among fish might be
considered normative in contrast to genetically selected hatchery
strains, which might have lost much of this variability. While
genetically diverse and spatially separated wild fish may be able to
deny new or old virulent strains the opportunity to proliferate through
close contact, hatchery fish, being possibly less diverse and more
densely packed, may transmit a virulent strain that would otherwise
subside as a result of competition with less-virulent counterparts
(Coutant 1998).

Fish culture may strongly influence the number of asymptomatic carriers
compared with their numbers in wild conditions (Coutant 1998). These
carriers are common (Anderson 1990), and they can transmit pathogens to
susceptible fish that they encounter. In wild fish, culling from disease
early in life may be masked, because we expect fairly high
early-life-stage mortality. However, prophylactics in hatchery culture
situations may reduce progressive early mortality. A high loss of
hatchery outplants, once dispersed in the wild, may merely be an
expression of the delayed culling process through disease. The long-term
effects for surviving wild and cultured fish might be equivalent, but
the development of the disease(s) from the perspective of the pathogen's
normal ecology might be very different between infection of young fish
and of older ones held in a hatchery for a year before release. The
pathogen might thereby be held to its normative cycle of attack,
infection, growth, and dispersal in early juveniles rather than creating
an abnormal disease cycle with older fish (Coutant 1998).

In hatchery salmonids, the negative effect of rearing density on growth,
condition factor, food conversion efficiency, as well as increased
physiological stress and rates of mortality, have been extensively
documented (Flagg et al. 2000). What role disease plays in these reduced
performance measures remains unclear, however reductions in performance
measures due to diseases, which themselves are related to rearing
densities, are well documented. For example, infection by bacterial
kidney disease (BKD), a major pathogen in Pacific Northwest fish
hatcheries, significantly reduced the ability of juvenile chinook to
avoid fish predators in laboratory experiments (Mesa 1998). The
potential effect of high densities of salmon in hatchery facilities
throughout the Pacific Northwest can be seen in surveys of hatchery
disease (Table K.1). Pathogen detection varied from relatively rare at
all facilities, such as with viral hemorrhagic septicemia (VHS), to
extremely common, such as with BKD.

Despite improvements in hatchery disease management, many of these
diseases continue to be chronic problems for salmonids in hatchery
facilities. Disease mortality rates in hatchery populations can be very
high, depending on environmental conditions, and vary considerably among
pathogens (Table K.2).

Infectious Haematopoietic Necrosis

Infectious haematopoietic necrosis (IHN) is an infectious viral disease
of rainbow or steelhead trout (*O. mykiss*), chinook (*O. tshawytscha*),
sockeye (*O. nerka*), chum (*O. keta*), and coho (*O. kisutch*) salmon
(OIE 2000). IHN reservoirs are clinically infected fish and covert
carriers among cultured, feral, or wild fish. Once established in a
farmed stock or watershed, due to either spawning of infected migratory
fish or from river restocking for recreational purposes, IHN may become
established among carriers (OIE 2000).

Infectious Pancreatic Necrosis

Infectious pancreatic necrosis (IPN) is a highly contagious viral
disease of young salmonids held under intensive rearing conditions. The
disease most characteristically occurs in rainbow and steelhead trout,
brook trout (*Salvelinus fontinalis*), brown trout (*Salmo trutta*), and
several Pacific salmon species (OIE 2000). Transmission within a
hatchery may be horizontal, vertical, or both (Reno 1999).

Viral Hemorrhagic Septicemia

Viral hemorrhagic septicemia (VHS), a systemic viral infection, occurs
in salmonids of any age and may result in significant mortality (OIE
2000). Epizootic losses occur at temperatures of 3° to 12°C (greatest at
3° to 5°C); low daily mortality over an extended time results in high
cumulative mortality. At high water temperatures (15° to 18°C), the
disease acts quickly with modest accumulated mortality and fewer
carriers (OIE 2000). Reservoirs of VHS are clinically infected fish and
cultured, feral, or wild carriers, and animate or inanimate surfaces in
hatcheries, where the virus can be mechanically transferred (McAllister
1990). Once established in stocks and water systems, carriers make the
disease enzootic (OIE 2000).

Erythrocytic Body Inclusion Syndrome

Erythrocytic body inclusion syndrome (EIBS) is a viral condition
observed in hatchery salmonids from the Columbia River and its
tributaries (Piacentini et al. 1989). This syndrome occurs at a higher
rate in hatchery chinook (70%) than those produced naturally (50%) in
the Snake River Basin (PNWFHPC 1998). The disease is more severe in coho
and chinook salmon than in rainbow and cutthroat trout and is more
severe at higher temperatures (Piacentini et al. 1989).

Bacterial Kidney Disease

Bacterial kidney disease (BKD) is a systemic bacterial infection from
*Renibacterium salmoninarum* that commonly causes high mortality in wild
and propagated salmonids. The disease is typically chronic, but acute
outbreaks sometimes occur at moderate temperatures (13° to 18°C), and
subclinically infected fish or carriers are reservoirs of infection
(Bullock and Herman 1988). Naturally infected feral brook trout can
transmit BKD to newly stocked rainbow, brown, and brook trout, which
begin dying within nine months. The bacteria are excreted by clinically
diseased trout, and can survive up to 21 days in feces or pond
sediments. BKD can also be transmitted vertically to eggs. Although
health control measures may contain the disease, and different methods
have been suggested for improving detection of the agent in infected
fish populations, there is as yet no general agreement on the value of
these methods (OIE 2000).

Furunculosis

Furunculosis (FUR) is a systemic bacterial infection that has an
asymptomatic form, an acute form with severe internal organ involvement
and high numbers of mortalities, and a chronic form that may involve
internal pathology with fewer mortalities over longer periods of time
(Reno 1999). Among salmonids, susceptibility is lower in brook, rainbow,
and brown trout than in other species (Reno 1999).

Enteric Redmouth Disease

Enteric redmouth disease (ERM) is an acute or chronic bacterial
infection from *Yersinia ruckeri*. Isolated from coho, sockeye, and
chinook salmon and from rainbow, cutthroat, and brown trout, outbreaks
have also been confirmed in steelhead (Horne and Barnes 1999). ERM
commonly causes sustained, low-level mortality, eventually resulting in
high losses; however, large-scale, acute epizootics occur if chronically
infected fish are stressed via intensive culture and poor water quality
(Bullock and Cipriano 1990, Horne and Barnes 1999). In rainbow trout,
25% of survivors of an experimental ERM challenge became asymptomatic
carriers with bacteria localized in the lower intestine (Busch and Lingg
1975). In streams receiving hatchery effluent, 60% (3/5) of rainbow
trout were positive for *Y. ruckeri* (Altinok et al. 2001). While
commercial vaccines have been effective, strains have developed
resistance and questions remain about the nature of antigens involved
(Horne and Barnes 1999).

Cold-Water Disease

Cold-water disease (CWD) is a bacterial infection that occurs in salmon
and brook, rainbow, and brown trout. Morbidity ranges from 1% to 50%; at
low temperatures (below 10°C), it approaches 75% (Shotts and Starliper
1999). Transmission is vertical or horizontal, and outbreaks can occur
after stocking a habitat with infected fish or transferring fish from
facilities where the infection had not been detected.

Proliferative Kidney Disease

Proliferative kidney disease (PKD) is caused by a parasitic myxozoan
infection that also parasitizes bryozoans (Kinkelin and Boriot 2001).
Mortality from PKD is variable and temperature dependent.

Whirling Disease

Whirling disease (MC) is a parasitic infection of trout and salmon by
the myxosporean *Myxobolus cerebralis*. Susceptibility ranges from high
to low in rainbow trout, sockeye salmon, golden trout (*O. aguabonita*),
cutthroat trout, brook trout, steelhead, chinook salmon, brown trout,
and coho salmon. Susceptibility is greater in younger fish than in older
fish (Markiw 1992). The source of the infective agent for fish is
usually the water supply or earthen ponds inhabited by aquatic tubificid
worms. Mortalities up to 90% may occur between newly hatched fish
exposed to the infective agent as sac fry.

*Ceratomyxa shasta*

*Ceratomyxa shasta* (CS) is a parasite that leads to mortality of
hatchery-reared and wild juvenile salmonids as well as to pre-spawning
mortality in adult salmon (Bartholomew 1989). Documented in chinook,
coho, sockeye, and chum salmon, as well as steelhead, rainbow, brook,
brown, and cutthroat trout, it involves an intermediate host, the
polychaete worm *Manaynukia speciosa*. Control of the parasite in
hatchery and wild populations depends on the introduction of resistant
salmonids (Bartholomew 1989), thus epizootics are possible if infested
water is transferred to native populations.

*Ichthyophthirius*

*Ichthyophthirius* (ICH), or \"white spot disease,\" is a protozoan
infection of freshwater fish caused by *Ichthyophthirius multifiliis*.
The parasite is quite lethal, and epizootics occur with relative
predictability. As the free-swimming infective stage is viable for only
days, epizootics are more likely to occur in facilities with
high-density fish populations. The "Ich" life cycle is influenced by
crowding, and growth rate and development accelerate when water
temperatures reach between 16° and 19°C (Traxler et al. 1998).

While data on occurrence and impact of hatchery diseases provide
information on historical potential for catastrophic epidemics,
continuing high production of hatchery fish may increase the risk of
future epidemics despite hatchery practices that may have been
instituted to mitigate or eliminate mortality in hatcheries. The
densities at which hatchery populations are reared and released may
increase the potential for known or heretofore unreported diseases to
spread within hatchery populations and then from hatchery populations to
wild populations. In dense populations, pathogen incidence can be high
and transmission barriers can be low, which can lead to high virulence.
Dense hatchery populations may act as reservoirs for exotic pathogens,
and, if hatchery fish are asymptomatic, transmission to wild populations
can be accelerated.

Pollution

Pollution in the form of oil and chemical spills can pose a risk to
salmonid populations in the Lower Columbia and Upper Willamette ESU.
Fish kills have been reported associated with such spills, and the
frequency of these events has not necessarily been reduced by
prophylactic measures and legislated improvements over the past few
decades. There are point sources of spills and leaks at storage
facilities and superfund sites as well as from the transportation of oil
and chemicals.

In addition to the myriad anthropogenic factors that can affect the
survival of outmigrating juveniles in freshwater, the biological effects
of chemical contaminants on salmonids during their residency in certain
urban estuaries can potentially lead to reduced survival. Concomitant
with the increased chemical exposure, juvenile salmonids inhabiting
certain urban estuaries exhibit evidence of impairment of physiological
processes such as immune system alterations, impaired growth, and
behavioral changes. There is evidence of linkage between the presence of
elevated levels of complex mixtures of chemical contaminants in polluted
estuaries and effects on health and survival of juvenile salmonids.
Sublethal effects from toxic chemical exposure experienced by outmigrant
juvenile salmonids during their residence in urbanized estuaries
indicate the need to further investigate estuarine pollution as a
contributing factor to declines in salmon stocks from urbanized
watersheds (Casillas et al. 1997).

Methods

Volcanoes

To determine relative risk from volcanic activity, we assembled hazard
assessment data from U.S. Geological Survey (USGS) sources for Mount
Rainier (Hoblitt et al. 1998), Mount Adams (Scott et al. 1995), Mount
St. Helens (Wolfe and Pierson 1995), Mount Hood (Scott et al. 1997),
Mount Jefferson (Walder et al. 1999), and the Three Sisters region
(Scott et al. 2001). In these reports, areas around volcanoes are
divided into proximal and distal hazard zones---some zones are
subdivided further---based on magnitude of past volcanic events inferred
from deposits, mathematical models that use calibrations from other
volcanoes to forecast the likely extent of future pyroclastic flows,
debris avalanches and lahars, and experience and judgment of USGS
scientists derived from observations and understanding of events at
similar volcanoes.

Hazard assessments were overlaid, along with fish distributions, on maps
of populations of the five Lower Columbia River and Upper Willamette
River salmonid ESUs. The relative catastrophic risk among populations
was assessed for Lower Columbia fall and spring chinook, Upper
Willamette spring chinook, Lower Columbia winter and summer steelhead,
Upper Willamette winter steelhead, and Lower Columbia chum by
categorizing volcanic hazard for each population. Categories of relative
catastrophic risk from volcanoes included negligible, low, medium, and
high. Populations that did not overlap with any volcanic hazard zone
were categorized as negligible. Populations that overlapped with low
hazard zones were categorized as low. Populations that overlapped with
low and medium volcanic hazard zones were categorized as medium.
Populations that overlapped with medium and high volcanic hazard zones
were categorized as high.

Earthquakes

To determine relative risk from earthquake activity, we assembled hazard
assessment data for the Pacific Northwest from USGS report 97-131
(Frankel et al. 1997). Hazard probabilities were calculated from the
largest ground motions to the smallest at a collection of sites and
added up to a total probability, P, and in a particular period of time,
T. For our analyses, we chose the hazard assessment of rare, large-scale
events. The hazard contours in this analysis are represented as peak
acceleration (% gravity \[g\]) or the percent acceleration force due to
gravity with a 2% probability of exceedance (PE) in 50 years.

Hazard probabilities were overlaid with fish distributions on
populations of the five Lower Columbia River and Upper Willamette River
salmonid ESUs. The relative catastrophic risk among populations was
assessed for Lower Columbia fall and spring chinook, Upper Willamette
spring chinook, Lower Columbia winter and summer steelhead, Upper
Willamette winter steelhead, and Lower Columbia chum by categorizing
earthquake hazard for each population. Categories of relative
catastrophic risk from earthquakes included low, medium, and high.
Populations that overlapped with earthquake hazard zones with low peak
acceleration values (18%--30% g) were categorized as low. Populations
that overlapped with earthquake hazard zones with moderate peak
acceleration values (30%--60% g) were categorized as medium. Populations
that overlapped with earthquake hazard zones with high peak acceleration
values (60%--120%g) were categorized as high.

Landslides/Glacial Outbursts

To determine relative risk from landslide activity, we assembled hazard
assessment data from USGS sources (Godt 1997). The map was trimmed to
the Lower Columbia River/Upper Willamette River ESU boundaries and
overlaid with major rivers on populations of the five Lower Columbia
River and Upper Willamette River salmonid ESUs. The relative
catastrophic risk among populations was assessed for Lower Columbia fall
and spring chinook, Upper Willamette spring chinook, Lower Columbia
winter and summer steelhead, Upper Willamette winter steelhead, and
Lower Columbia chum by categorizing landslide hazards for each
population. The original USGS coverage categorized risk in two ways:
landslide susceptibility/incidence and landslide incidence. We grouped
these assessments into catastrophic risk categories of low, medium, and
high based on the relative amounts of area in each population in the
three categories and the proximity of hazard areas to salmonid-bearing
streams in the population. Populations that overlapped with landslide
hazard zones of low hazard values were categorized as low. Populations
that overlapped with medium values or a combination of hazard zones that
averaged medium were categorized as medium. Populations that overlapped
with landslide hazard zones with high values or a combination of hazard
zones that averaged or was dominated by high values, especially in
fish-bearing streams, was categorized as high.

Disease Epidemics from Hatchery Operations

As a proxy for the potential for disease epidemics, we collected data on
the extent of hatchery production within population boundaries for the
five Lower Columbia River and Upper Willamette River salmonid ESUs. Data
on hatchery production levels were compiled from a variety of sources,
primarily the 2000 hatchery adipose-clip database
(<ftp://ftp.streamnet.org/> pub/streamnet/maps/massmarking), hatchery
genetic management plans submitted to NMFS, Integrated Hatchery
Operations Team (IHOT) reports
([www.streamnet.org/ihot_audit/](http://www.streamnet.org/ihot_audit/)
hatchery.html), and the Northwest Indian Fisheries Commission Hatchery
Releases Web page (www.NWIFC.org). Annual releases of salmonids
(chinook, chum, coho, sockeye, steelhead, and cutthroat trout) and
related species (rainbow, brown, brook, and golden trout) at on-site and
at off-site locations were summed for facility and categorized as no
risk (0 fish/year), low risk (0 to 500,000 fish/year), medium risk
(500,000 to 5,000,000 fish/year) and high risk (\>5,000,000 fish/year).
Population boundaries were defined according to historical
demographically independent populations identified in Myers et al.
(2002).

Oil/Chemical Pollution (Transportation)

To determine relative risk of a catastrophic event due to oil/chemical
pollution, we assembled information on transportation corridors in areas
overlapping with the listed ESUs in the Lower Columbia and Upper
Willamette Rivers. The road density GIS layer was obtained from the
Regional Ecosystem Office Web site (http://www.reo.gov/reo/) and
overlaid, along with fish distributions, on maps of populations of the
five Lower Columbia and Upper Willamette River salmonid ESUs. A ratio of
road density was calculated using ArcView 8.1 by dividing the linear
extent (km) of all roads by the total area (km^2^) encompassed by each
population. We mapped the ratio of road length/area of population (see
Figures K.17--K.22) based on sorting the ratios into four equal
intervals and labeled them accordingly: negligible, low, medium, and
high. The relative catastrophic risk among populations was assessed for
ESUs (Lower Columbia chum) and life history types within ESUs (Lower
Columbia fall and spring chinook; Upper Willamette spring chinook; Lower
Columbia winter and summer steelhead; Upper Willamette winter steelhead)
by categorizing earthquake hazard for each population.

Correlated Catastrophic Risk Assessment

Single catastrophic events can affect a single population or an entire
metapopulation. For Pacific salmon metapopulations, an intermediate case
is appropriate, whereby a single catastrophic event will affect several
populations, but not necessarily the entire metapopulation. For example,
a volcanic eruption could drastically reduce spawning and rearing
habitat for populations in multiple watersheds. It is possible to
explore how these types of spatially correlated catastrophes affect
metapopulation dynamics by simulating the effect of catastrophes on
population-specific capacities within an ESU. Given a hypothesized
spatial correlation in risk between 21 chinook populations of the Puget
Sound ESU, the program RAMAS 4.0 applied catastrophes stochastically
over 100 years, with a per-population catastrophic risk that was
increased according to its correlation with other populations. For this
ESU, catastrophic events can affect the performance of a metapopulation
(Ruckelshaus et al. in prep.).

Results of Analyses

Volcanoes

The catastrophic risk from volcanic activity varied among populations
within ESUs, but generally depended upon proximity to the north-south
line of Cascade volcanoes. The populations and their risks are as
follows:

Lower Columbia River fall chinook ESU (Figure K.1)

> Negligible (9) Coast Range*---*Youngs Bay, Grays River, Big Creek,
> Elochoman River, Clatskanie River, Mill Creek, Scappoose Creek
>
> Western Cascades*---*Coweeman and Clackamas River tributaries
>
> Low (5) Western Cascades---upper and lower Cowlitz River, Washougal
> River
>
> Columbia Gorge---lower and upper gorge tributaries
>
> Medium (3) Western Cascades---Lewis River/Salmon Creek
>
> Columbia Gorge---Big White Salmon River, Hood River tributaries
>
> High (3) Western Cascades---Toutle, Kalama, Sandy Rivers

Lower Columbia River spring chinook ESU (Figure K.2)

> Negligible (1) Western Cascades---Tilton River
>
> Medium (5) Western Cascades---upper Cowlitz, Cispus, and Lewis Rivers
>
> Columbia Gorge---Big White Salmon and Hood Rivers
>
> High (3) Western Cascades---Toutle, Kalama, and Sandy Rivers

Upper Willamette spring chinook ESU (Figure K.2)

> Negligible (3) Molalla, South Santiam, and Calapooia Rivers
>
> Low (2) Clackamas and Middle Fork Willamette Rivers
>
> Medium (2) North Santiam and McKenzie Rivers

Lower Columbia winter steelhead ESU (Figure K.3)

> Negligible (4) Western Cascades---Tilton, Coweeman, and East Fork
> Lewis Rivers, and Salmon Creek
>
> Low (5) Western Cascades---lower Cowlitz, Clackamas, and Washougal
> Rivers
>
> Columbia Gorge---lower and upper gorge tributaries.
>
> Medium (4) Western Cascades---Cispus, upper Cowlitz, and North Fork
> Lewis Rivers.
>
> Columbia Gorge---Hood River
>
> High (4) Western Cascades---North and South Forks Toutle, Kalama, and
> Sandy Rivers

Lower Columbia River summer steelhead ESU (Figure K.4)

> Negligible (1) Western Cascades---East Fork Lewis River
>
> Low (2) Western Cascades---Washougal and Wind Rivers
>
> Medium (2) Western Cascades---North Fork Lewis River.
>
> Columbia Gorge---Hood River
>
> High (1) Western Cascades---Kalama River

Upper Willamette River winter steelhead ESU (Figure K.3)

> Negligible (4) Willamette Valley---Coast Range tributaries, Molalla
> River, South Santiam River, and Calapooia River
>
> Medium (1) Willamette Valley---North Santiam River

Lower Columbia River chum ESU (Figure K.5)

> Negligible (8) Coast Range---Youngs Bay, Grays River (including
> Chinook River), Big Creek, Elochoman River, Clatskanie River, Mill
> Creek, Scappoose Creek
>
> Western Cascades---Salmon Creek
>
> Low (5) Western Cascades---lower Cowlitz, Clackamas, and Washougal
> Rivers
>
> Columbia Gorge---lower and upper gorge tributaries
>
> Medium (1) Western Cascades---Lewis River
>
> High (2) Western Cascades---Kalama River, Sandy River

Correlated Catastrophic Risk from Volcanoes

The catastrophic risk posed by volcanic activity transcends population
boundaries delineated for many ESUs. Some volcanoes present a clear and
present danger for many ESUs and populations therein, and some
populations were under hazard from multiple volcanoes. Because of the
spatial arrangement of the Cascade Mountain volcanoes, correlated
catastrophic risks are not necessarily reciprocal, especially where
tributaries form distinct populations. For these reasons, as well as the
categorical nature of the risk assessments, we did not construct a
quantitative correlated catastrophic risk matrix. Simultaneous
catastrophic risk to ESU populations, by volcano, are as follows:

Lower Columbia River fall chinook ESU

-   Mount St. Helens---Lewis River/Salmon Creek, Kalama and Toutle
    Rivers, lower Cowlitz River population downstream of the Toutle

-   Mount Rainier---upper and lower Cowlitz populations

-   Mount Adams---Washougal River, Big White Salmon River, and lower and
    upper gorge tributaries

-   Mount Hood---Hood and Sandy Rivers

Lower Columbia River spring chinook ESU

-   Mount St. Helens---Toutle and Kalama Rivers

-   Mount Rainier---upper Cowlitz River, but not the Cispus River
    population

-   Mount Adams---Cispus River, upper Cowlitz River via the Cispus, and
    Big White Salmon River

-   Mount Hood---Hood and Sandy Rivers

Upper Willamette spring chinook ESU

-   Mount Jefferson---Clackamas and North Santiam Rivers

-   Three Sisters---McKenzie and Middle Fork Willamette Rivers

Lower Columbia winter steelhead ESU

-   Mount St. Helens---North and South Fork Toutle, Kalama, and North
    Fork Lewis Rivers

-   Mount Rainier---upper and lower Cowlitz Rivers

-   Mount Adams---Cispus River, upper and lower Cowlitz River via the
    Cispus River, and Washougal River, lower and upper gorge tributaries

-   Mount Hood---Hood and Sandy Rivers

Lower Columbia River summer steelhead ESU

-   Mount St. Helens---Kalama River and North Fork Lewis River

-   Mount Adams---North Fork Lewis, Washougal, and Wind Rivers

Upper Willamette River winter steelhead ESU

-   Mount St. Helens---North and South Fork Toutle, Kalama, and North
    Fork Lewis Rivers

-   Mount Rainier---upper and lower Cowlitz River

-   Mount Adams---Cispus River, upper and lower Cowlitz River via the
    Cispus, Washougal River, and lower and upper gorge tributaries

-   Mount Hood---Hood and Sandy Rivers

Lower Columbia River chum ESU

-   Mount St. Helens---lower Cowlitz, Kalama, and Lewis Rivers

-   Mount Adams---Washougal River, lower and upper gorge tributaries

-   Mount Hood---Hood and Sandy Rivers

Earthquakes

The catastrophic risk from earthquakes varied among populations within
ESUs but generally declined from coastal to inland tributaries.

Lower Columbia River fall chinook (Figure K.6)

> Low (5) Western Cascades---Sandy River
>
> Columbia Gorge---lower and upper gorge tributaries, Big White Salmon
> River, Hood River
>
> Medium (13) Coast Range---Grays River, Big Creek, Elochoman River,
> Clatskanie River, Mill Creek, Scappoose Creek
>
> Western Cascades---Cowlitz, Coweeman, Toutle, and Kalama Rivers, Lewis
> River/Salmon Creek, Clackamas and Washougal Rivers
>
> High (1) Coast Range---Youngs Bay

Lower Columbia River spring chinook (Figure K.7)

Low (3) Western Cascades---(Sandy River)

> Columbia Gorge---Big White Salmon River, Hood River
>
> Medium (6) Western Cascades---upper Cowlitz, Cispus, Tilton, Toutle,
> Kalama, and Lewis Rivers

Upper Willamette River spring chinook (Figure K.7)

> Low (6) Willamette Valley and western Cascades---Clackamas, North and
> South Santiam, Calapooia, McKenzie, and Middle Fork Willamette Rivers
>
> Medium (1) Willamette Valley---Molalla River

Lower Columbia River winter steelhead (Figure K.8)

> Low (5) Western Cascades---Clackamas and Sandy Rivers
>
> Columbia Gorge---lower and upper gorge tributaries and Hood River
>
> Medium (12) Western Cascades---Cispus, Tilton, lower and upper
> Cowlitz, North and South Fork Toutle, Coweeman, Kalama, North and East
> Fork Lewis Rivers, Salmon Creek, and Washougal River

Lower Columbia River summer steelhead (Fiure K.9)

Low (2) Columbia Gorge---Hood and Wind Rivers

> Medium (4) Western Cascades---Kalama, North and East Fork Lewis, and
> Washougal Rivers

Lower Columbia River winter steelhead (Figure K.8)

> Low (3) Willamette Valley and western Cascades---North and South
> Santiam and Calapooia Rivers
>
> Medium (2) Willamette Valley and western Cascades---Coast Range
> tributaries and Molalla River

Lower Columbia River chum (Figure K.10)

> Low (2) Columbia Gorge---lower and upper gorge tributaries
>
> Medium (13) Coast Range---Grays River (including Chinook River), Big
> Creek, Elochoman River, Clatskanie River, Mill Creek, Scappoose Creek
>
> Western Cascades---lower Cowlitz River, Kalama River, Salmon Creek,
> Lewis River, Clackamas River, Washougal River, Sandy River
>
> Coast Range---Youngs Bay

Correlated Catastrophic Risk from Earthquakes

The catastrophic risk posed by earthquake activity transcends population
boundaries delineated for many ESUs and tends to vary along a gradient
from the coast eastward toward the interior. Populations within ESUs are
under the same level of hazard risk along this east-west gradient; thus,
populations within ecoregions (Coast Range, western Cascades, Columbia
Gorge) tend to be under correlated risk from catastrophic earthquake
activity. For these reasons, as well as the categorical nature of the
risk assessments, we did not construct a quantitative correlated
catastrophic risk matrix. Simultaneous catastrophic risk to ESU
populations by earthquakes are as follows:

Lower Columbia River fall chinook

> Coast Range (7)---Youngs Bay, Grays River, Big Creek, and Elochoman
> River, Clatskanie River, Mill Creek, and Scappoose Creek
>
> Western Cascades (9)
>
> Columbia Gorge (4)

Lower Columbia River spring chinook ESU

> Western Cascades (7)
>
> Columbia Gorge (2)

Upper Willamette spring chinook

> Willamette Valley/Western Cascades (7)

Lower Columbia winter steelhead

> Western Cascades (14)
>
> Columbia Gorge (3)

Lower Columbia River summer steelhead (6)

> Western Cascades (4)
>
> Columbia Gorge (2)

Upper Willamette River winter steelhead (5)

> Coast Range---Molalla, Santiam, South Santiam, and Calapooia Rivers

Lower Columbia River chum

> Coast Range (7)---Youngs Bay, Grays River (including Chinook River),
> and Big Creek, Elochoman River, Clatskanie River, Mill Creek, and
> Scappoose Creek
>
> Western Cascades (9)
>
> Columbia Gorge (2)

Landslides

The catastrophic risk from landslides varied among populations for
populations within ESUs.

Lower Columbia River fall chinook (Figure K.11)

> Low (5) Western Cascades---Upper Cowlitz River, Coweeman River, Lewis
> River /Salmon Creek
>
> Columbia Gorge---Big White Salmon River, Hood River
>
> Medium (5) Coast Range---Grays River, Elochoman River, Mill Creek
>
> Western Cascades---Toutle and Washougal Rivers
>
> High (10) Coast Range---Youngs Bay, Big Creek, Clatskanie River,
> Scappoose Creek
>
> Western Cascades---Lower Cowlitz, Kalama, Clackamas, and Sandy Rivers
>
> Columbia Gorge---lower and upper gorge tributaries

Lower Columbia River spring chinook (Figure K.12)

Low (4) Western Cascades---Cispus and Tilton Rivers

> Columbia Gorge---Big White Salmon and Hood Rivers

Medium (3) Western Cascades---upper Cowlitz, Toutle, and Lewis Rivers

High (2) Western Cascades---Kalama and Sandy River

Upper Willamette River spring chinook (Figure K.12)

> Low (1) Willamette Valley and western Cascades---Molalla River
>
> Medium (3) Willamette Valley and western Cascades---Clackamas,
> McKenzie, and Middle Fork Willamette Rivers
>
> High (3) Willamette Valley and western Cascades---North and South
> Santiam and Calapooia Rivers

Lower Columbia River winter steelhead (Figure K.13)

> Low (6) Western Cascades---Cispus, Tilton, South Fork Toutle,
> Coweeman, and East Fork Lewis Rivers and Salmon Creek
>
> Medium (6) Western Cascades---upper Cowlitz, North Fork Toutle, North
> Fork Lewis, Clackamas, and Washougal Rivers
>
> Columbia Gorge---Hood River
>
> High (5) Western Cascades---lower Cowlitz, Kalama, and Sandy River
>
> Columbia Gorge---lower and upper gorge tributaries

Lower Columbia River winter steelhead (Figure K.14)

> Low (3) Western Cascades---East Fork Lewis River
>
> Columbia Gorge---Wind and Hood Rivers
>
> Medium (1) Western Cascades---North Fork Lewis River
>
> High (2) Western Cascades---Kalama and Washougal Rivers

Lower Columbia River winter steelhead (Figure K.13)

> Low (1) Molalla River
>
> Medium (1) Coast Range tributaries
>
> High (3) North and South Santiam and Calapooia Rivers

Lower Columbia River chum ESU (Figure K.15)

Low (2) Salmon Creek, Lewis River

Medium (3) Western Cascades---Grays River, Mill Creek, Washougal River

> High (11) Coast Range---Youngs Bay, Big Creek, Elochoman River,
> Clatskanie River, Scappoose Creek
>
> Western Cascades---lower Cowlitz, Kalama, Clackamas, and Sandy Rivers
>
> Columbia Gorge---lower and upper gorge tributaries

Correlated Catastrophic Risk from Landslides

The catastrophic risk posed by landslides transcends population
boundaries delineated for many ESUs and is highly variable across the
landscape. The catastrophic risk posed by landslide activity is highly
influenced by several factors, including a variety of geologic factors
and precipitation patterns, thus the few areas at a high risk from
landslides may or may not be along salmonid spawning or rearing habitat.
Landslide risk due to earthquake or volcanic activity will mirror those
assessments, while those associated with flooding and precipitation will
mirror those assessments. For these reasons, as well as the categorical
nature of the risk assessments, we did not construct a quantitative
correlated catastrophic risk matrix.

Disease Epidemics from Hatchery Operations

The potential for disease epidemics as represented by hatchery
production varied among populations within ESUs and individual hatchery
facilities.

Lower Columbia River fall chinook ESU (Figure K.16)

> Negligible (4) Coast Range---Clatskanie River, Mill Creek, Scappoose
> Creek
>
> Western Cascades---Coweeman River
>
> Low (4) Western Cascades---Salmon Creek
>
> Columbia Gorge---Big White Salmon and Hood Rivers
>
> Medium (5) Coast Range---Youngs Bay, Grays River
>
> Western Cascades---Toutle, Clackamas, and Sandy Rivers
>
> High (8) Coast Range---Big Creek, Elochoman River
>
> Western Cascades---Cowlitz, Kalama, Lewis, and Washougal Rivers
>
> Columbia Gorge---lower and upper gorge tributaries

Lower Columbia River spring chinook ESU (Figure K.17)

> Negligible (3) Western Cascades---upper Cowlitz, Cispus, and Tilton
> Rivers
>
> Low (2) Columbia Gorge---Big White Salmon and Hood Rivers
>
> Medium (2) Western Cascades---Toutle and Sandy Rivers
>
> High (2 Western Cascades---Kalama and Lewis Rivers

Upper Willamette River spring chinook ESU (Figure K.17)

> Negligible (2) Molalla and Calapooia Rivers
>
> Medium (4) Clackamas, North Santiam, McKenzie, and Middle Fork
> Willamette Rivers
>
> High (1) South Santiam River

Lower Columbia River winter steelhead ESU (Figure K.18)

> Negligible (6) Western Cascades---Cispus, Tilton, upper Cowlitz, South
> Fork Toutle, Coweeman, and East Fork Lewis Rivers
>
> Low (2) Western Cascades---Salmon Creek
>
> Columbia Gorge---Hood River
>
> Medium (3) Western Cascades---North Fork Toutle, Clackamas, and Sandy
> Rivers
>
> High (6) Western Cascades---lower Cowlitz, Kalama, North Fork Lewis,
> and Washougal Rivers
>
> Columbia Gorge---lower and upper gorge tributaries, Hood River

Upper Willamette River winter steelhead ESU (Figure K.18)

Negligible (2) Westside (Coast Range)--- Molalla and Calapooia Rivers

Medium (1) North Santiam River

High (1) South Santiam River

Lower Columbia River summer steelhead ESU (Figure K.19)

> Negligible (1) Western Cascades---East Fork Lewis River
>
> Low (1) Columbia Gorge---Hood River
>
> Medium (1) Columbia Gorge---Wind River
>
> High (3) Western Cascades---Kalama, North Fork Lewis, and Washougal
> Rivers

Lower Columbia River chum ESU (Figure K.20)

Negligible Coast Range---Clatskanie River, Mill Creek, Scappoose Creek

> Western Cascades---Coweeman River
>
> Low (1) Western Cascades---Salmon Creek
>
> Medium (4) Coast Range---Youngs Bay, Grays River
>
> Western Cascades---Clackamas and Sandy Rivers
>
> High (7) Coast Range---Big Creek, Elochoman River
>
> Western Cascades---lower Cowlitz, Kalama, Lewis, and Washougal Rivers
>
> Columbia Gorge---lower and upper gorge tributaries

Correlated Catastrophic Risk from Hatchery Disease Epidemics

Correlated catastrophes were considered for hatchery disease epidemics
in populations within ESUs. The connection among populations in terms of
correlated catastrophes depends on many factors. If infected fish were
released into the wild to prevent die-offs at the hatchery, as has
occurred in the past, potential infection of wild fish would be a
function of infected hatchery fish and wild fish densities as well as of
pathogen or parasite transmission rates. Further, the spread of
infections up or downstream would depend on pathogen or parasite
movement patterns as well as wild fish movement at the time of potential
transmission. For these reasons, we did not construct a quantitative
correlated catastrophic risk matrix.

Pollution

The catastrophic risk of oil/chemical pollution from transportation
varied among populations within ESUs, but generally followed patterns of
urban development throughout the river basins.

Lower Columbia River fall chinook ESU (Figure K.21)

> Negligible (8) Coast Range---Big Creek
>
> Western Cascades---upper and lower Cowlitz, Washougal, and Sandy
> Rivers
>
> Columbia Gorge---lower and upper gorge tributaries, Big White Salmon
> River
>
> Low (8) Coast Range---Youngs Bay, Grays River, Elochoman River,
> Clatskanie River, Scappoose Creek
>
> Western Cascades---Toutle River, Lewis River/Salmon Creek
>
> Columbia Gorge---Hood River
>
> Medium (3) Coast Range---Mill Creek
>
> Western Cascades---Coweeman and Kalama River
>
> High (1) Western Cascades---Clackamas River

Lower Columbia River spring chinook ESU (Figure K.22)

> Negligible (4) Western Cascades---upper Cowlitz, Cispus, and Sandy
> Rivers
>
> Columbia Gorge---Big White Salmon River
>
> Low (2) Western Cascades---Lewis River
>
> Columbia Gorge---Hood River
>
> Medium (2) Western Cascades---Tilton and Toutle Rivers
>
> High (2) Western Cascades---Kalama River

Upper Willamette River spring chinook ESU (Figure K.23)

Negligible (2) McKenzie and Middle Fork Willamette Rivers

Low (3) Clackamas, North Santiam, and Calapooia Rivers

High (2) Molalla and South Santiam Rivers

Lower Columbia River winter steelhead ESU (Figure K.24)

> Negligible (4) Western Cascades---Cispus, upper Cowlitz, and Sandy
> Rivers
>
> Columbia Gorge---lower gorge tributaries
>
> Low (4) Western Cascades---North and East Forks Lewis River
>
> Columbia Gorge---upper gorge tributaries and Hood River
>
> Medium (5) Western Cascades---Tilton, lower Cowlitz, North Fork
> Toutle, Clackamas, and Washougal Rivers
>
> High (4) Western Cascades---South Fork Toutle, Coweeman, and Kalama
> Rivers and Salmon Creek

Lower Columbia River summer steelhead ESU (Figure K.25)

> Negligible (3) Western Cascades---North Fork Lewis and Washougal
> Rivers
>
> Columbia Gorge---Wind River
>
> Low (2) Western Cascades---East Fork Lewis River
>
> Columbia Gorge---Hood River
>
> High (1) Western Cascades---Kalama River

Upper Willamette River winter steelhead ESU (Figure K.26)

> Negligible North Santiam and Calapooia Rivers
>
> High (3) Western (Coast Range) tributaries and Molalla and South
> Santiam Rivers

Lower Columbia River chum populations ESU (Figure K.27)

> Negligible Coast Range---Big Creek
>
> Columbia Gorge---lower and upper gorge tributaries
>
> Low Coast Range---Youngs Bay, Elochoman River, Clatskanie River,
> Scappoose Creek
>
> Western Cascades---Lewis, Washougal, and Sandy Rivers
>
> Medium (5) Coast Range---Grays River, Mill Creek
>
> Western Cascades---lower Cowlitz River, Kalama River, Salmon Creek
>
> High (1) Western Cascades---Clackamas River

Correlated Catastrophic Risk from Oil/Chemical Spills from
Transportation

Correlated catastrophes were considered for oil/chemical spills from
transportation among populations in ESUs. Like for hatchery disease,
however, the connection among populations in terms of correlated
catastrophes would depend on many factors. The oil/chemical spills
likely to occur during transportation over roadways would probably be
confined within a watershed, and direct mortality from toxins would be
on a subpopulation scale. However, spills from roadways into a tributary
might affect its major river; spread of the mortality agent upstream or
downstream would depend on volatility of the oil/chemical as well as
movement of wild fish at the time of the potential transmission. For
these reasons, we did not construct a quantitative correlated
catastrophic risk matrix.

Conclusions

Catastrophic events need to be considered when relating viable salmonid
populations (VSPs) to viable ESUs in the Lower Columbia and Willamette
Rivers. Although documenting the frequency, intensity, and hazard risk
of specific natural and anthropogenic catastrophes is possible across
the landscape for ESUs, calculating correlated catastrophic risk can be
problematic for some catastrophes. Harder still is the task of
calculating cumulative effects of volcanoes, earthquakes, floods,
landslides, fires, disease epidemics from hatcheries, and pollution from
a variety of sources. Still, the preponderance of potential catastrophic
events that could impact salmonids throughout the Columbia River Basin
requires attention to their potential effects, and the paucity of such
approaches belies its importance. The potential catastrophes cataloged
herein represent an initial list of those where (1) the risks for
salmonids have been documented or are known to represent a future risk,
(2) actual risk information (or a reasonable proxy) has been collated or
is accessible, and (3) there is potential for quantitative data in the
future. Further analyses of catastrophic risks are ongoing (floods) or
may be initiated (extreme weather such as droughts, unusual fires, water
diversion/dam failure, major miscalculations in harvest) depending on
the information available and the potential for rigorous analyses. More
refined metrics may allow for further exploration of the risk of disease
epidemics from hatchery operations.

The role that catastrophes may have played in the evolution of salmonids
suggests that \"bet-hedging\" against large-scale catastrophes through
maintaining diverse populations and life-history types is an appropriate
strategy for recovery in the face of extinction risk. Such a strategy
should foster enhanced long-term stability in the face of unpredictable
catastrophes. Future research on the risk of extinction posed by
catastrophic events for an entire ESU will hinge on quantitative
estimates of correlated risk among populations within an ESU. Guidelines
presented in McElhany et al. (2000) make clear that concern about
catastrophic risks is relevant to long-term evolutionary potential. The
probability that an ESU could be driven extinct by a single catastrophic
event is nontrivial and thus requires multiple viable populations within
a viable ESU, with careful consideration to which populations are
restored or maintained at viable status.

This appendix explored the spatial distribution and frequencies of
potential natural and anthropogenic catastrophic events affecting
endangered Pacific salmonid ESUs in the Lower Columbia and Upper
Willamette Rivers, specifically chinook salmon (*Oncorhynchus
tshawytscha*), steelhead trout (*O. mykiss*), and chum salmon (*O.
keta*). While this is a difficult field of study, we conclude that
extinction risk, particularly with respect to catastrophic events, can
be reduced if viable populations are spatially distributed through out
the ESU. Spatially distributed populations utilizing different
environments with different catastrophic risks reduce the likelihood
that a single catastrophic event would affect every population in an
ESU. Further, fish with different life histories that share the same
river basin may be affected differentially by the same catastrophic
event. This spreading of risk throughout spatially distributed
populations and life-history strata, akin to the "bet-hedging" that
occurred during the evolution of salmonids, holds promise for reducing
the risk of extinction due to catastrophes for these endangered and
threatened Pacific salmonid ESUs in the Lower Columbia and Upper
Willamette Rivers.

![](media/image1.jpeg){width="8.129861111111111in"
height="5.367361111111111in"}

Figure K.1 Fall chinook---Lower Columbia ESU volcanic hazards.

![](media/image2.jpeg){width="6.179861111111111in"
height="6.9215277777777775in"}

Figure K.2 Spring chinook---Lower Columbia and Willamette River ESUs
volcanic hazards.

![](media/image3.jpeg){width="6.05in" height="6.667361111111111in"}

Figure K.3 Winter steelhead---Lower Columbia and Willamette River ESUs
volcanic hazards.

![](media/image4.jpeg){width="8.15in" height="5.218055555555556in"}

> Figure K.4 Summer steelhead---Lower Columbia ESU volcanic hazards.

![](media/image5.jpeg){width="8.209722222222222in"
height="5.180555555555555in"}

> Figure K.5 Chum---Lower Columbia ESU volcanic hazards.

![](media/image6.jpeg){width="7.459722222222222in"
height="5.195138888888889in"}Figure K.6 Earthquake probabilities for
fall chinook populations.

![](media/image7.jpeg){width="5.759722222222222in"
height="7.011805555555555in"}

> Figure K.7 Earthquake probabilities for spring chinook populations.

![](media/image8.jpeg){width="5.770138888888889in"
height="6.9527777777777775in"}

> Figure K.8 Earthquake probabilities for winter steelhead populations.

![](media/image9.jpeg){width="7.920138888888889in"
height="5.511111111111111in"}

Figure K.9 Earthquake probabilities for summer steelhead populations.

![](media/image10.jpeg){width="7.920138888888889in"
height="5.511111111111111in"}

Figure K.10 Earthquake probabilities for chum populations.

![](media/image11.bmp)

![](media/image12.jpeg){width="5.990277777777778in"
height="7.589583333333334in"}

Figure K.12 Landslide risk to spring chinook populations.

![](media/image13.jpeg){width="5.620138888888889in"
height="7.195833333333334in"}

Figure K.13 Landslide risk to winter steelhead populations.

![](media/image14.bmp)

Figure K.14 Landslide risk to summer steelhead populations.

![](media/image15.jpeg){width="7.529861111111111in"
height="5.50625in"}15 Landslide risk to chum populations.

![](media/image16.jpeg){width="7.090277777777778in"
height="5.253472222222222in"}

Figure K.16 Disease risk from hatchery releases to fall chinook.

![](media/image17.jpeg){width="5.05in" height="6.626388888888889in"}

> Figure K.17 Disease risk from hatchery releases to spring chinook.

![](media/image18.jpeg){width="5.05in" height="6.518055555555556in"}

Figure K.18 Disease risk from hatchery releases to winter steelhead.

![](media/image19.jpeg){width="7.079861111111111in"
height="5.289583333333334in"}

Figure K.19 Disease risk from hatchery releases to summer steelhead.

![](media/image20.jpeg){width="7.329861111111111in"
height="5.50625in"}Figure K.20 Disease risk from hatchery releases to
chum.

![](media/image21.jpeg){width="7.3902777777777775in"
height="5.132638888888889in"}

Figure K.21 Relative road density ratios by fall chinook populations.

![](media/image22.jpeg){width="7.490277777777778in"
height="5.268055555555556in"}

Figure K.22 Relative road density ratio by Columbia River spring chinook
populations.

![](media/image23.jpeg){width="5.659722222222222in"
height="7.021527777777778in"}

> Figure K.23 Relative road density ratio by Willamette spring chinook
> populations.

![](media/image24.jpeg){width="5.770138888888889in"
height="6.9527777777777775in"}

> Figure K.24 Relative road density ratios by Lower Columbia winter
> steelhead populations.

![](media/image25.jpeg){width="7.540277777777778in"
height="5.251388888888889in"}

Figure K.25 Relative road density ratios by summer steelhead
populations.

![](media/image26.jpeg){width="5.670138888888889in" height="6.9625in"}

> Figure K.26 Relative road density ratios by Willamette winter
> steelhead populations.

![](media/image27.jpeg){width="7.170138888888889in"
height="5.094444444444444in"}

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