9126 Federal Register / Vol. 80, No. 33 / Thursday, February 19, 2015 / Rules and Regulations 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[Docket No. FWS–R1–ES–2014–0002; 

FXES11130900000C6–156–FF09E42000] 

RIN 1018–BA28 

Endangered and Threatened Wildlife 

and Plants; Removing the Oregon 

Chub From the Federal List of 

Endangered and Threatened Wildlife 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Final rule. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), are removing 

the Oregon chub (Oregonichthys 

crameri) from the Federal List of 

Endangered and Threatened Wildlife. 

This determination is based on a 

thorough review of the best available 

scientific and commercial information, 

which indicates that the Oregon chub 

has recovered and no longer meets the 

definition of an endangered species or a 

threatened species under the 

Endangered Species Act of 1973, as 

amended (Act). Our review of the status 

of this species shows that the threats to 

this species have been eliminated or 

reduced and populations are stable so 

that the species is not currently, and is 

not likely to again become, a threatened 

species within the foreseeable future in 

all or a significant portion of its range. 

This rule also removes the currently 

designated critical habitat for the 

Oregon chub throughout its range. 

DATES: This rule is effective on March 

23, 2015. 

ADDRESSES: This final rule and the postdelisting monitoring plan are available 

on the Internet at http://

www.regulations.gov at Docket Number 

FWS–R1–ES–2014–0002. Comments 

and materials received, as well as 

supporting documentation used in the 

preparation of this rule, will be 

available for public inspection, by 

appointment, during normal business 

hours, at the Service’s Oregon Fish and 

Wildlife Office, 2600 SE 98th Avenue, 

Portland, OR 97266. 

FOR FURTHER INFORMATION CONTACT: Paul 

Henson, State Supervisor, Oregon Fish 

and Wildlife Office (see ADDRESSES); 

telephone 503–231–6179; or facsimile 

(fax) 503–231–6195. Persons who use a 

telecommunications device for the deaf 

(TDD) may call the Federal Information 

Relay Services (FIRS) at 800–877–8339 

for assistance. 

SUPPLEMENTARY INFORMATION: 

Executive Summary 

This document contains: (1) A final 

rule to remove the Oregon chub from 

the Federal List of Endangered and 

Threatened Wildlife, and (2) a notice of 

availability of a final post-delisting 

monitoring plan. 

Species addressed—The Oregon chub 

(Oregonichthys crameri) is endemic to 

the Willamette River drainage of 

western Oregon. Extensive human 

activities in the Willamette River Basin 

(e.g., dams, levees, and other human 

development within the floodplain) 

have substantially reduced the amount 

and suitability of habitat for this 

species. Improved floodplain 

management and floodplain restoration 

by multiple conservation partners has 

reduced and mitigated adverse humanrelated impacts and resulted in 

significant improvements to habitat 

quality and quantity. As a result, threats 

to the Oregon chub have been largely 

ameliorated. 

The status of the species has 

improved dramatically due to the 

discovery of many new populations and 

successful reintroductions within the 

species’ historical range. At the time of 

listing in 1993 (58 FR 53800, October 

18, 1993), only nine known populations 

of Oregon chub existed, and few 

estimates existed of the number of 

individuals within each population. The 

locations of these populations 

represented a small fraction (estimated 

as 2 percent based on stream miles) of 

the species’ formerly extensive 

distribution within the Willamette River 

drainage. In 2013, 77 populations were 

known to exist throughout the 

Willamette River drainage. The risk of 

extinction is substantially reduced as 

threats have been ameliorated and new 

populations have been discovered or 

established. 

Purpose of the Regulatory Action— 

Under the Endangered Species Act of 

1973, we may be petitioned to list, 

delist, or reclassify a species. In 2010, 

we reclassified the Oregon chub from 

endangered to threatened (75 FR 21179, 

April 23, 2010), based on defined 

criteria in the species recovery plan. In 

2014, we proposed to remove the 

Oregon chub from the Federal List of 

Endangered and Threatened Wildlife 

(79 FR 7136, February 6, 2014), based 

on delisting criteria in the recovery plan 

and a five factor threats analysis. 

Threats to this species have been largely 

ameliorated, with the exception of the 

effects of climate change, and we do not 

consider such effects to be a substantial 

threat to the species at this time. 

Therefore, we have determined that the 

Oregon chub no longer meets the 

definition of an endangered or 

threatened species under the Act. This 

final rule removes the Oregon chub from 

the Federal List of Endangered and 

Threatened Wildlife. This rule also 

removes the currently designated 

critical habitat for the Oregon chub 

throughout its range. 

Basis for the Regulatory Action— 

Under the Act, a species may be 

determined to be an endangered species 

or threatened species because of any of 

five factors: (A) The present or 

threatened destruction, modification, or 

curtailment of its habitat or range; (B) 

overutilization for commercial, 

recreational, scientific, or educational 

purposes; (C) disease or predation; (D) 

the inadequacy of existing regulatory 

mechanisms; or (E) other natural or 

manmade factors affecting its continued 

existence. We must consider the same 

factors in delisting a species. We may 

delist a species if the best scientific and 

commercial data indicate the species is 

neither endangered nor threatened for 

one or more of the following reasons: (1) 

The species is extinct; (2) the species 

has recovered and is no longer 

threatened or endangered; or (3) the 

original scientific data used at the time 

the species was classified were in error. 

Threats to the Oregon chub at the time 

of listing in 1993, included loss of 

habitat, water quality, and competition 

with and predation by nonnative fishes. 

We reviewed all available scientific and 

commercial information pertaining to 

the five threat factors in our status 

review of the Oregon chub, and the 

results are summarized below. 

• We consider the Oregon chub to be 

‘‘recovered’’ because all substantial 

threats to this fish have been 

ameliorated and the species is now 

abundant and well-distributed 

throughout much of its presumed 

historical range. 

• All remaining potential threats to 

the species and its habitat, with the 

exception of effects related to climate 

change, have been ameliorated, and 

many populations exist on public lands 

managed for fish and wildlife 

conservation. 

• We do not consider effects related 

to climate change to be a substantial 

threat to the species at this time, and we 

do not expect climate change effects to 

rise to the magnitude or severity such 

that the species will be likely to become 

an endangered species within the 

foreseeable future. While we recognize 

that climate change effects such as 

rising air temperatures, reduced 

snowpack, and increased drought may 

have potential effects to the Oregon 

chub and its habitat, the best available 

information does not indicate that such 


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Federal Register / Vol. 80, No. 33 / Thursday, February 19, 2015 / Rules and Regulations 9127 

effects will significantly impact the 

Oregon chub or its habitat. We expect 

that the Oregon chub’s susceptibility to 

climate change effects is low given the 

wide range of temperature tolerances of 

Oregon chub, the range and diversity of 

habitats occupied by the species, and 

because effects of climate change will be 

ameliorated by multiple storage dams in 

the Willamette River Basin. 

• We find that delisting the Oregon 

chub is warranted and thus we are 

removing this taxon from the Federal 

List of Endangered and Threatened 

Wildlife. 

• We prepared a final post-delisting 

monitoring plan to monitor the Oregon 

chub after delisting to verify that the 

species remains secure. 

Previous Federal Actions 

Please refer to the proposed rule to 

remove the Oregon chub from the 

Federal List of Endangered and 

Threatened Wildlife (79 FR 7136, 

February 6, 2014) for a detailed 

description of previous Federal actions 

concerning this species. This document 

is our final rule to remove the Oregon 

chub from the Federal List of 

Endangered and Threatened Wildlife. 

Background 

This is a final rule to remove the 

Oregon chub from the Federal List of 

Endangered and Threatened Wildlife. It 

is our intent to discuss in this final rule 

only those topics directly relevant to the 

removal of the Oregon chub from the 

Federal List of Endangered and 

Threatened Wildlife. 

Species Information 

The following section contains 

information updated from that 

presented in the proposed rule to 

remove Oregon chub from the Federal 

List of Endangered and Threatened 

Wildlife, which published in the 

Federal Register on February 6, 2014 

(79 FR 7136). A thorough discussion of 

the species’ description, population 

density, and abundance is also found in 

the proposed rule. 

Species Description and Life 

History—The Oregon chub is a small 

minnow in the Cyprinid family. Young 

of the year range in length from 7 to 32 

millimeters (mm) (0.3 to 1.3 inches (in)), 

and adults grow up to 90 mm (3.5 in) 

in length (Pearsons 1989, p. 17). The 

Oregon chub reaches maturity at about 

2 years of age (Scheerer and McDonald 

2003, p. 78) and in wild populations can 

live up to 9 years. Oregon chub spawn 

from May through August and are not 

known to spawn more than once a year. 

The Oregon chub live in slack water 

off-channel habitats such as beaver 

(Castor canadensis) ponds, oxbows, side 

channels, backwater sloughs, lowgradient tributaries, and flooded 

marshes. These habitats usually have 

little or no water flow, are dominated by 

silty and organic substrate, and contain 

considerable aquatic vegetation 

providing cover for hiding and 

spawning (Pearsons 1989, p. 27; Markle 

et al. 1991, p. 289; Scheerer and 

McDonald 2000, p. 1). The average 

depth of habitat used by the Oregon 

chub is less than 1.8 meters (m) (6 feet 

(ft)), and summer water temperatures 

typically exceed 16 degrees Celsius (61 

degrees Fahrenheit). Adult Oregon chub 

seek dense vegetation for cover and 

frequently travel in the mid-water 

column in beaver channels or along the 

margins of aquatic plant beds. Larval 

Oregon chub congregate in shallow 

near-shore areas in the upper layers of 

the water column, whereas juveniles 

venture farther from shore into deeper 

areas of the water column (Pearsons 

1989, p. 16). In the winter months, 

Oregon chub are found buried in the 

detritus or concealed in aquatic 

vegetation (Pearsons 1989, p. 16). Fish 

of similar size school and feed together. 

In the early spring, Oregon chub are 

most active in the warmer, shallow 

areas of aquatic habitats. 

The Oregon chub is an obligatory 

sight feeder (Davis and Miller 1967, 

p. 32). It feeds throughout the day and 

stops feeding after dusk (Pearsons 1989, 

p. 23). The Oregon chub feeds mostly on 

water column fauna. The diet of Oregon 

chub adults collected in a May sample 

consisted primarily of minute 

crustaceans including copepods, 

cladocerans, and chironomid larvae 

(Markle et al. 1991, p. 288). The diet of 

juvenile Oregon chub also consisted of 

minute organisms such as rotifers and 

cladocerans (Pearsons 1989, p. 2). 

Range—The Oregon chub is endemic 

to the Willamette River drainage of 

western Oregon. Historical records show 

the Oregon chub existed as far 

downstream as Oregon City and as far 

upstream as the town of Oakridge. 

Historically a dynamic, alluvial river, 

the Willamette and its tributaries 

created broad floodplains and braided 

reaches with many side channels, 

sloughs, and other similar slack-water 

habitats that support the Oregon chub. 

The Willamette is typical of river 

systems on the west side of the Cascade 

Mountains, with the largest river flows/ 

floods influenced by heavy rain, or rainon-snow events during the late winter 

and spring. Snowmelt in the spring 

typically produces an elongated flow 

peak in the spring, with decreasing 

flows throughout summer. 

Extensive human activities in the 

Willamette River Basin have 

substantially reduced the floodplain 

habitats and altered water temperatures, 

as well as the timing, duration, and 

magnitude of floods in the basin. In the 

1950s and 1960s, the U.S. Army Corps 

of Engineers (USACE) constructed 13 

large dams on many of the tributaries of 

the Willamette River, with the primary 

purpose of flood risk reduction. Though 

the Willamette River mainstem and 

some tributaries remain undammed, 

miles of levees have also been 

constructed to further increase 

agricultural and urban use of these 

former floodplain areas. 

At the time of listing in 1993 (58 FR 

53800, October 18, 1993), only nine 

known populations of Oregon chub 

existed, and few estimates existed of the 

number of individuals within each 

population. The locations of these 

populations represented a small fraction 

(estimated as 2 percent based on stream 

miles) of the species’ formerly extensive 

distribution within the Willamette River 

drainage. 

Abundance and Distribution—Since 

we listed the Oregon chub as 

endangered in 1993, the status of the 

species improved dramatically due to 

the discovery of many new populations 

and successful reintroductions within 

the species’ historical range (Scheerer 

2007, p. 97). Recently, since we 

reclassified the Oregon chub to 

threatened status in 2010 (75 FR 21179, 

April 23, 2010), a substantial number of 

new Oregon chub populations were 

discovered (34 populations) and 

established through introductions (8 

populations). In 2013, the Oregon 

Department of Fish and Wildlife 

(ODFW) confirmed the existence of 

Oregon chub at 77 locations in the 

Molalla River, Luckiamute River, North 

and South Santiam River, McKenzie 

River, Middle Fork and Coast Fork 

Willamette Rivers, and several 

tributaries to the mainstem Willamette 

River downstream of the Coast Fork and 

Middle Fork Willamette River 

confluence (Bangs et al. 2012, pp. 7–9), 

including 56 naturally occurring and 21 

introduced populations. In 2013, the 

estimated abundance of 41 Oregon chub 

populations was greater than 500 fish 

each, and 23 of these populations 

exhibited a stable or increasing trend 

over the last 7 years (Bangs et al. 2013, 

p. 1). The current status of Oregon chub 

populations meets the goals of the 

species recovery plan for delisting. The 

distribution of these sites is shown in 

Table 1. 


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TABLE 1—DISTRIBUTION OF OREGON CHUB POPULATIONS MEETING RECOVERY CRITERIA FOR DELISTING

[Bangs et al. 2013, pp. 5–8] 

Recovery subbasin Number of 

populations 

Number of large 

populations 

(≥500 adult fish) 

Number of large 

populations with 

stable/increasing 

abundance trend 

Total estimated 

abundance in 

subbasin 

Santiam .................................................................... 19 13 7 32,714 

Mainstem Willamette 1 ............................................. 26 10 6 71,840 

Middle Fork Willamette ............................................ 28 17 10 54,285 

Coast Fork Willamette 2 ........................................... 4 1 0 824 

Total .................................................................. 77 41 23 159,663 

1 Includes McKenzie River subbasin. 

2The Coast Fork Willamette was identified as a subbasin containing Oregon chub in the recovery plan, but was not identified as a Recovery 

Area. 

Although certain populations of the 

Oregon chub remain relatively stable 

from year to year, we observed 

substantial fluctuations in abundance 

within populations. For instance, the 

largest known population at Ankeny 

National Wildlife Refuge was 21,790 

Oregon chub individuals in 2010, and 

increased to 96,810 in 2011. The 

population then declined from 82,800 to 

47,920 between 2012 and 2013. We 

observed similar substantial fluctuations 

in 2013, at the Dunn Wetland and at the 

Hills Creek Pond populations. While 

substantial, these fluctuations 

commonly occur, and appear natural 

and cyclical. For example, we estimated 

the population abundance at the Dexter 

Reservoir Alcove ‘‘PIT1’’ site at 140 in 

1995. Although annual estimated 

abundance fluctuated, this population 

reached 1,440 estimated individuals in 

2000. The population then declined to 

70 individuals in 2004, and then 

increased again to reach 1,370 estimated 

individuals in 2009 (Scheerer et al. 

2005, p. 2). 

A major component of recovery efforts 

for the Oregon chub was introducing the 

species into hydrologically isolated 

habitats that are free from nonnative fish 

species. Twenty-one new populations 

were established since 1988 (Table 2). In 

2013, 14 introduced populations existed 

with more than 500 Oregon chub each; 

6 of these populations exhibited a stable 

or increasing 7-year abundance trend 

(Bangs et al. 2013, p. 14). 

TABLE 2—INTRODUCED OREGON CHUB POPULATIONS

[Bangs et al. 2013, pp. 6–8, 15] 

[MS—Mainstem Willamette River, S—Santiam River, CF—Coast Fork Willamette River, and MF—Middle Fork Willamette River] 

Site name Subbasin Year of first 

introduction 

Number of fish 

introduced 

Estimated 

abundance 

(2013) 

Dunn Wetland ........................................................................................................... MS ........ 1997 573 6,439 

Finley Display Pond .................................................................................................. MS ........ 1998 500 118 

Russell Pond ............................................................................................................. MS ........ 2001 500 133 

Finley Cheadle Pond ................................................................................................ MS ........ 2002 530 157 

Ankeny Willow Marsh ............................................................................................... MS ........ 2004 500 47,920 

St. Paul Ponds .......................................................................................................... MS ........ 2008 195 442 

Finley-Buford Pond ................................................................................................... MS ........ 2011 160 1,009 

Murphy Pond ............................................................................................................ MS ........ 2011 214 1,079 

Ellison Pond .............................................................................................................. MS ........ 2012 110 9 

McCrae Reservoir ..................................................................................................... MS ........ 2013 29 29 

Foster Pullout Pond .................................................................................................. S ........... 1999 500 3,412 

South Stayton Pond .................................................................................................. S ........... 2006 439 1,102 

North Stayton Pond .................................................................................................. S ........... 2010 620 3,724 

Budeau South Pond ................................................................................................. S ........... 2010 312 2,810 

Budeau North Pond .................................................................................................. S ........... 2010 310 8,350 

Herman Pond ............................................................................................................ CF ......... 2002 400 184 

Sprick Pond .............................................................................................................. CF ......... 2008 65 608 

Wicopee Pond .......................................................................................................... MF ........ 1992 178 4,375 

Fall Creek Spillway Ponds ........................................................................................ MF ........ 1996 500 9,107 

Haws Enhancement Pond ........................................................................................ MF ........ 2009 133 788 

Hills Creek Pond ....................................................................................................... MF ........ 2010 1,127 14,613 

Genetic Diversity—The Service’s 

Abernathy Fish Technology Center 

conducted a genetic analysis on the 

Oregon chub in 2010 (DeHaan et al. 

2010, 2012, entire). The analysis 

examined genetic diversity at 10 

microsatellite loci within and among 20 

natural and 4 introduced populations. 

The findings suggest that four 

genetically distinct groups of the Oregon 

chub exist, corresponding to the four 

subbasins of the Willamette River. 

Levels of genetic diversity were high 

across the range of the species and equal 

to, or greater than, other threatened or 

endangered species of minnows (i.e., 

cyprinids). In addition, the levels of 

genetic diversity for Oregon chub were 

similar to the creek chub Semotilus 

atromaculatus, a widespread and 

abundant species of minnow (DeHaan 

2012, pp. 548–549). Despite fluctuations 

in population abundance of Oregon 

chub, genetic diversity remained stable 


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over a 7- to 8-year interval (three to four 

Oregon chub generations). Two 

populations of the 24 evaluated had 

reduced genetic diversity: A recent 

bottleneck was observed in the 

Shetzline population, and the Geren 

Island population showed evidence of 

decreasing diversity, possibly due to 

reductions in the population size from 

8,660 to 360 fish between 1997 and 

2000 (Bangs et al. 2012, p. 109). 

Currently, both populations are 

abundant and exhibit an increasing 

trend in population growth over the last 

7 years (Bangs et al. 2013, pp. 7–8). 

The genetic assessment (DeHaan et al. 

2010, p. 18; DeHaan et al. 2012, p. 545) 

shows that the current Oregon chub 

translocation guidelines (ODFW 2006, 

entire) (which require the donor 

population from within same subbasin, 

and a minimum of 500 Oregon chub 

introduced) are effective in establishing 

genetically viable populations. Levels of 

genetic diversity were similar to natural 

populations in three out of four of the 

introduced sites studied. Introduced 

populations from multiple sources had 

increased diversity and showed 

evidence of interbreeding. The Dunn 

wetland population, which had three 

donor populations, had the highest 

genetic diversity of all sites (natural and 

introduced). The Wicopee Pond 

population had relatively low levels of 

genetic diversity, which was likely 

because this population was founded 

with only 50 Oregon chub originating 

from 1 source population. These data 

support introducing greater numbers of 

individuals and using multiple sources 

from within a subbasin. 

Recovery and Recovery Plan 

Implementation 

Background—Section 4(f) of the Act 

(16 U.S.C. 1531 et seq.) directs us to 

develop and implement recovery plans 

for the conservation and survival of 

endangered and threatened species 

unless we determine that such a plan 

will not promote the conservation of the 

species. Under section 4(f)(1)(B)(ii), 

recovery plans must, to the maximum 

extent practicable, include: ‘‘Objective, 

measurable criteria which, when met, 

would result in a determination, in 

accordance with the provisions of 

[section 4 of the Act], that the species 

be removed from the list.’’ However, 

revisions to the list (adding, removing, 

or reclassifying a species) must reflect 

determinations made in accordance 

with sections 4(a)(1) and 4(b) of the Act. 

Section 4(a)(1) requires that the 

Secretary determine whether a species 

is endangered or threatened (or not) 

because of one or more of five threat 

factors. Section 4(b) of the Act requires 

that the determination be made ‘‘solely 

on the basis of the best scientific and 

commercial data available.’’ Therefore, 

recovery criteria should help indicate 

when we would anticipate that an 

analysis of the five threat factors under 

section 4(a)(1) would result in a 

determination that the species is no 

longer an endangered species or 

threatened species because of any of the 

five statutory factors (see Summary of 

Factors Affecting the Species). 

While recovery plans provide 

important guidance to the Service, 

States, and other partners on methods of 

minimizing threats to listed species and 

measurable objectives against which to 

measure progress towards recovery, they 

are not regulatory documents and 

cannot substitute for the determinations 

and promulgation of regulations 

required under section 4(a)(1) of the 

Act. A decision to revise the status of or 

remove a species from the Federal List 

of Endangered and Threatened Wildlife 

(50 CFR 17.11) is ultimately based on an 

analysis of the best scientific and 

commercial data then available to 

determine whether a species is no 

longer an endangered species or a 

threatened species, regardless of 

whether that information differs from 

the recovery plan. 

Recovery plans may be revised to 

address continuing or new threats to the 

species, as new, substantive information 

becomes available. The recovery plan 

identifies site-specific management 

actions that will achieve recovery of the 

species, measurable criteria that set a 

trigger for review of the species’ status, 

and methods for monitoring recovery 

progress. Recovery plans are intended to 

establish goals for long-term 

conservation of listed species and define 

criteria that are designed to indicate 

when the substantial threats facing a 

species have been removed or reduced 

to such an extent that the species may 

no longer need the protections of the 

Act. 

There are many paths to 

accomplishing recovery of a species, 

and recovery may be achieved without 

all criteria being fully met. For example, 

one or more criteria may be exceeded 

while other criteria may not yet be 

accomplished. In that instance, we may 

determine that the threats are 

minimized sufficiently and the species 

is robust enough to delist. In other 

cases, recovery opportunities may be 

discovered that were not known when 

the recovery plan was finalized. These 

opportunities may be used instead of 

methods identified in the recovery plan. 

Likewise, information on the species 

may be discovered that was not known 

at the time the recovery plan was 

finalized. The new information may 

change the extent to which criteria need 

to be met for recognizing recovery of the 

species. Recovery of a species is a 

dynamic process requiring adaptive 

management that may, or may not, fully 

follow the guidance provided in a 

recovery plan. 

Recovery Planning—The Oregon Chub 

Working Group, which was formed 

prior to listing the species, is a proactive 

force in improving the conservation 

status of the Oregon chub. This group of 

Federal and State agency biologists, 

academicians, land managers, and 

others has met each year since 1991, to 

share information on the status of the 

Oregon chub, results of new research, 

and ongoing threats to the species. 

Additionally, an interagency 

conservation agreement was established 

for the Oregon chub in 1992 (ODFW et 

al. 1992). The objectives of the 

agreement were to: (1) Establish a task 

force drawn from participating agencies 

to oversee and coordinate Oregon chub 

conservation and management actions; 

(2) protect existing populations; (3) 

establish new populations; and (4) foster 

greater public understanding of the 

species, its status, and the factors that 

influence it (ODFW et al. 1992, pp. 3– 

5). These objectives are similar to that 

of the subsequently developed recovery 

plan. 

The Recovery Plan for the Oregon 

Chub was approved by the Service on 

September 3, 1998 (Service 1998). The 

recovery plan outlines recovery criteria 

to assist in determining when the 

Oregon chub has recovered to the point 

that the protections afforded by the Act 

are no longer needed. These delisting 

criteria are: (1) 20 populations of at least 

500 individuals each are established 

and maintained; (2) all of these 

populations must exhibit a stable or 

increasing trend for 7 years; (3) at least 

4 populations (meeting criteria 1 and 2) 

must be located in each of the 3 

subbasins (Mainstem Willamette, 

Middle Fork Willamette, and Santiam 

Rivers); and (4) management of these 20 

populations must be guaranteed in 

perpetuity (Service 1998, pp. 27–28). 

Recovery Plan Implementation—The 

status of the Oregon chub has improved 

dramatically since it was listed as 

endangered. The improvement is due 

largely to the implementation of actions 

identified in the interagency 

conservation agreement and the Oregon 

chub recovery plan. These actions 

include the establishment of additional 

populations via successful introductions 

within the species’ historical range and 

the discovery of many new populations 

as a result of the ODFW’s surveys of the 

basin (Scheerer 2007, p. 97). Over 20 


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years have passed since the species was 

listed, and it is now abundant and welldistributed throughout much of its 

presumed historical range. Currently, 

there are 77 Oregon chub populations, 

of which 41 have more than 500 adults 

(Bangs et al. 2013, pp. 5–11). The risk 

of extinction is substantially reduced as 

threats have been ameliorated and new 

populations have been discovered or 

established. The following criteria for 

delisting the Oregon chub are met or 

exceeded as described in the recovery 

plan: 

Delisting Criterion 1: 20 populations 

of at least 500 individuals are 

established and maintained. This 

criterion was exceeded; in 2013, we 

identified 41 populations with more 

than 500 adult Oregon chub (see Table 

1, above). 

Delisting Criterion 2: All of these 

populations (20) must exhibit a stable or 

increasing trend for 7 years. This 

criterion was met. Currently, 23 

populations of at least 500 individuals 

exhibit a stable or increasing trend for 

7 years (see Table 1, above). 

Delisting Criterion 3: At least four 

populations (meeting criteria 1 and 2) 

must be located in each of the three 

subbasins (Mainstem Willamette, 

Middle Fork, and Santiam Rivers). This 

criterion was exceeded in all three 

subbasins. Six populations in the 

Mainstem Willamette River subbasin, 10 

populations in the Middle Fork 

Willamette River subbasin, and 7 

populations in the Santiam River 

subbasin meet the first 3 delisting 

criteria (see Table 1, above). 

Delisting Criterion 4: Management of 

these 20 populations must be 

guaranteed in perpetuity. The level of 

management protection recommended 

in the Oregon chub recovery plan (i.e., 

management guaranteed into perpetuity) 

exceeds the requirements of the Act in 

evaluating whether a species meets the 

statutory definition of endangered or 

threatened, as adequate protection for 

the species in the long term may be 

provided otherwise. Although we do not 

have guarantees that all of the 

populations will be managed into 

perpetuity, we have a high level of 

confidence that management of the 

Oregon chub sites will continue to 

provide adequate protection for the 

species in the long term, as further 

discussed below. Of the 41 sites with 

populations of more than 500 Oregon 

chub, 28 of the sites are in public or 

Tribal ownership, with either active 

conservation management programs, or 

practices where land managers consider 

the needs of the Oregon chub when 

implementing site management 

activities. Additionally, eight of the sites 

with abundant populations of the 

Oregon chub are on land that is 

privately owned, either where 

landowners have signed conservation 

agreements or are enrolled in our Safe 

Harbor Program. Three additional sites 

are on land that is in a permanent 

easement or ownership by the McKenzie 

River Trust, a land trust dedicated to 

conservation of wetland and riparian 

habitat. 

Based on our review of the Oregon 

chub recovery plan, we conclude that 

the status of the species has improved 

due to implementation of recovery 

activities and the objectives of the 

recovery plan have been met. Our 

analysis of whether the species has 

achieved recovery and thus no longer 

requires the protections of the Act 

because it is no longer an endangered or 

threatened species is based on the five 

statutory threat factors identified in 

section 4 of the Act, and discussed 

below in the Summary of Factors 

Affecting the Species. 

Summary of Comments and 

Recommendations 

In the proposed rule published 

February 6, 2014 (79 FR 7136), we 

requested that all interested parties 

submit written comments on the 

proposal by April 7, 2014. We also 

contacted appropriate Federal and State 

agencies, scientific experts and 

organizations, and other interested 

parties and invited them to comment on 

the proposal. The Service hosted a 

media event with local and national 

news coverage announcing the proposed 

rule on February 4, 2014. We did not 

receive any requests for a public 

hearing. 

During the comment period for the 

proposed rule, we received five 

comment letters (three from peer 

reviewers, one from the ODFW, and one 

from the public) directly addressing the 

proposed removal of the Oregon chub 

from the Federal List of Endangered and 

Threatened Wildlife. All substantive 

information provided during the 

comment period is either incorporated 

directly into this final determination or 

is addressed below. The following 

section summarizes issues and 

information we consider to be 

substantive from peer review and public 

comments, and provides our responses. 

Peer Review 

In accordance with our policy, 

‘‘Notice of Interagency Cooperative 

Policy for Peer Review in Endangered 

Species Act Activities,’’ which was 

published on July 1, 1994 (59 FR 

34270), we solicited expert opinion on 

the proposed rule and the draft postdelisting monitoring plan from three 

knowledgeable independent individuals 

with scientific expertise that included 

familiarity with Oregon chub and its 

habitat, biological needs, recovery 

efforts, and threats. We received 

responses from all three peer reviewers. 

Issues and information provided by the 

peer reviewers are summarized in the 

Peer Reviewer Comments section, and 

where they overlap with similar issues 

identified by the public, they are 

included in the Public Comments 

section. 

Peer Reviewer Comments 

Comment (1): Two peer reviewers 

suggested that the lower bounds of the 

confidence intervals should be used to 

determine the number of populations 

meeting Delisting Criterion #1. 

Our response: The species’ recovery 

plan does not define the method to 

determine population size for Delisting 

Criterion #1. The ODFW uses a singlesample mark-recapture model, also 

called an adjusted Petersen estimate, to 

estimate population abundance (Bangs 

et al. 2013, p. 5). This method is 

supported in the literature (Seber 1973, 

pp. 59–60, Ricker 1975, pp. 75–79), and 

demonstrates reliable estimates for 

sampling conditions similar to what 

ODFW experiences monitoring Oregon 

chub. The ODFW also demonstrates the 

reliability in its population abundance 

estimates by providing a 95 percent 

confidence interval (Bangs et al. 2013, 

pp. 9–12). The calculation of the 

confidence interval is highly influenced 

by the sample size; a narrower interval 

requires sampling more individuals 

(Seber 1973, p. 61). Thus, in small 

populations, greater sampling effort 

would be required to demonstrate if a 

population met Delisting Criterion #1 if 

the lower bound was used, thus 

exposing more individuals to the risk of 

trapping or handling mortality. We do 

not agree with the reviewer’s suggestion 

to use the lower bound of the 95 percent 

confidence interval, as this method 

exposes individuals in small 

populations to greater risk of mortality 

than the method used by the ODFW. 

Comment (2): One peer reviewer 

asked why the Coast Fork Willamette 

Oregon chub populations were not 

mentioned under Delisting Criterion #3. 

Our response: Under the recovery 

plan for Oregon chub, the Coast Fork 

Willamette was not included in the 

Mainstem, Santiam, or Middle Fork 

Willamette recovery areas. The recovery 

plan states: ‘‘Although a single small 

population of Oregon chub currently 

occurs in a fourth subbasin, the Coast 

Fork, recovery efforts will not focus on 

this subbasin because surveys have not 


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revealed any other suitable habitats, and 

nonnative fish are very common.’’ 

Although we are encouraged that two 

additional, small populations of Oregon 

chub were discovered and two 

introduced populations were 

established in the Coast Fork subbasin, 

recovery criteria were met without the 

inclusion of the populations in this 

subbasin. 

Comment (3): One peer reviewer 

asked that the Service provide a more 

current summary of the 2009–2010 

Willamette Floodplain Report (Bangs et 

al. 2011a, entire). This peer reviewer 

also suggested that the delisting rule 

incorporate 2013 data. 

Our response: The Willamette 

Floodplain Report, with analysis of data 

from 2009–2012, is currently in 

preparation by the ODFW, and is 

expected to be available late spring 2015 

at the earliest. As such, we are using the 

best available information at this time. 

We agree with the second part of this 

comment, and updated the rule to 

include the 2013 data. 

Public Comments 

Comment (4): One commenter stated 

that the Service did not adequately 

consider effective population size in the 

decision to delist the Oregon chub. The 

commenter stated that the general rule 

for short-term (50) and long-term (500) 

effective population size is not 

appropriate, as an effective population 

size of 500 individuals does not 

sufficiently reduce extinction risk. The 

commenter stated that determining a 

minimum viable population based on 

effective population size should include 

additional factors, such as 

environmental and demographic 

stochasticity, spatial dispersion, 

overlapping generations, and synergistic 

interactions among the risk factors. As 

an example, the commenter mentioned 

that the largest population of Oregon 

chub in the Middle Fork Willamette 

subbasin is in Hills Creek Pond; the 

population abundance was estimated at 

13,460 individuals in 2012. The 

commenter noted that this was the total 

population size and not the effective 

population size, and was too small to 

assure viability. 

Our response: The minimum viable 

population is the smallest estimated 

population size with a high probability 

of long-term persistence. Minimum 

viable population factors in risks 

associated with demographic and 

environmental stochastic events, and 

the impacts of inbreeding and limited 

genetic diversity. The effective 

population size is the number of 

breeding individuals in the population 

that contribute genetic material to the 

next generation, and can be used to 

determine the impacts of inbreeding and 

limited genetic diversity during the 

analysis of the minimum viable 

population. The recovery criteria in the 

recovery plan (Service 1998) do not 

require measuring effective population 

sizes for Oregon chub. At the time the 

recovery plan was written, the Service 

used the best available science to set the 

recovery criterion abundance threshold 

at 500 adult fish per population. This 

threshold is based on the total adult 

population size, not effective population 

size, and takes into account effects of 

limited genetic diversity and inbreeding 

associated with small population size 

and the risk associated with stochastic 

events. 

Jamieson and Allendorf (2012, p. 583) 

suggested that, at a minimum, an 

effective population size of 500 

individuals is needed for conservation 

of endangered species, including the 

potential impacts of stochastic events on 

conservation genetics. Jamieson and 

Allendorf (2012, p. 580) suggested an 

effective population size of 500 

individuals is the total for all 

populations of a species, and not the 

size of individual populations. The total 

Oregon chub population size in 2013 

was approximately 160,000 adult fish 

(Bangs et al. 2013, pp. 6–9). 

DeHaan (2012, p. 543) determined 

effective population size for three 

isolated Oregon chub populations as 

part of a genetic analysis of the species. 

While these isolated populations 

represent a worst-case scenario for 

negative genetic effects, the study 

suggested: (1) There was no immediate 

threat from inbreeding or genetic drift, 

and (2) many Oregon chub populations 

have some degree of connectivity to 

other populations. This study also 

determined that genetic diversity 

remains high and stable over time, 

despite fluctuations in individual 

population size. Further, the ODFW 

(Bangs et al. 2013, p. 17) documented 

movement of individual Oregon chub 

between populations, which provides a 

mechanism for genetic exchange 

between populations that will maintain 

genetic variation (DeHaan 2012, p. 543). 

Despite the recent genetic analysis 

(DeHaan 2012, p. 543), the best available 

information is not sufficient to 

determine a minimum viable population 

size for Oregon chub. 

In our decision to delist the Oregon 

chub, we are required to analyze the 

current or foreseeable threats to the 

species to determine whether a species 

meets the definition of endangered or of 

threatened, based on the best available 

scientific information. Our analysis 

includes recent genetic data that 

demonstrate Oregon chub are not 

threatened by low genetic diversity. We 

conclude that the recovery criterion 

abundance threshold of 500 adult fish 

per population is adequate, and 

analyzing the effective population size 

or determining the minimum viable 

population is not required in order to 

assess the status of the species. 

Comment (5): One commenter stated 

that the Service was not conservative in 

the analysis of population size and must 

err on the side of caution. The reviewer 

commented that stochastic events and 

small population sizes decreases the 

population viability and increases the 

extinction risk of Oregon chub. The 

commenter further stated that the 

extreme annual variability within 

individual Oregon chub population 

sizes suggests considerable risk of 

extinction, even in locally abundant 

populations. The commenter mentioned 

that in addition, population growth is 

impacted by demographic stochasticity. 

Our response: We disagree. The Act 

does not require that we ‘‘err on the side 

of caution’’ in determining the status of 

a species; it requires that we determine, 

based on the best available scientific 

information, whether a species meets 

the definition of endangered or of 

threatened. The Willamette River 

floodplain where Oregon chub evolved 

has always been highly dynamic. 

Oregon chub are extremely well adapted 

to surviving stochastic events. For 

instance, Oregon chub habitats have 

been known to freeze each winter, 

experience high magnitude flood flows 

in the spring, and reach in excess of 25 

degrees Celsius (77 degrees Fahrenheit) 

in the summer, yet Oregon chub 

survive. Oregon chub are now welldistributed throughout their historical 

range in a variety of habitats, which 

reduces the risk of effects of severe 

stochastic events to the species 

throughout its range. Each habitat is 

impacted by stochastic effects in 

different ways. For example, while 

populations in shallow water habitats 

with high solar exposure may be 

impacted by severe hot and dry weather 

that raises temperatures to unsuitable 

levels for chub, populations in habitats 

that are deep and well-shaded may 

benefit by water warmed to the 

preferred temperature range for the 

species. Oregon chub have been 

documented in new, suitable habitat 

created by floodplain processes in the 

McKenzie River subbasin, and voluntary 

movement of Oregon chub was 

documented between populations in the 

Middle Fork Willamette River (Bangs et 

al. 2012, p. 19) and McKenzie River 

subbasins (Bangs et al. 2013, p. 17). 

These findings demonstrate the ability 


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of Oregon chub to colonize new 

habitats, resulting in exchange of 

genetic material between established 

populations, thus reducing the potential 

effects of stochastic events on small 

populations. 

Further, for each ‘‘stable’’ population 

(as defined in the recovery plan), we 

calculate the coefficient of variation for 

the past 7 years. If the coefficient of 

variation is greater than one (in other 

words, if the variation is greater than the 

mean abundance), we consider the 

population ‘‘unstable’’ and do not 

consider that population to meet the 

recovery criteria. The 20 populations in 

2012, and 23 populations in 2013, that 

met delisting criteria had either a 

‘‘stable’’ or ‘‘increasing’’ abundance 

trend. This leads us to conclude that the 

variability in population abundance is 

not a factor that will impact future 

survival of these populations, provided 

the abundance criteria (500 adult fish) is 

met, because genetic diversity remains 

high and stable over time, despite 

fluctuations in individual population 

size (DeHaan 2012, p. 543). Overall, 

trend analysis conducted since 1996 

demonstrates that the Oregon chub 

populations are stable and that the 

concerns raised by the commenter are 

not affecting Oregon chub recovery and 

are not expected into the foreseeable 

future. 

Comment (6): One commenter and 

one peer reviewer suggested including a 

better description of population trends 

for Oregon chub populations that are 

coexisting with nonnative predators. 

One peer reviewer also suggested that 

the Service discuss specific predators 

that may impact Oregon chub, instead of 

combining all nonnatives, specifically 

western mosquitofish (Gambusia affinis) 

and largemouth bass (Micropterus 

salmoides). One peer reviewer suggested 

that the Service include western 

mosquitofish as a potential predator on 

larval Oregon chub, and that we include 

this species in the predation discussion. 

One commenter recommended that 

efforts to limit largemouth bass 

colonization should be discussed in the 

final rule to delist Oregon chub. The 

peer reviewer asked that the Service 

explore alternative management of 

mosquitoes by using native minnows 

instead of nonnative western 

mosquitofish. One commenter stated 

that the inadequacy of existing 

regulatory mechanisms to prevent 

spread of western mosquitofish and 

largemouth bass into connected 

watersheds was not adequately 

analyzed, and should be discussed. 

Additionally, one peer reviewer 

recommended that the post-delisting 

monitoring (PDM) plan focus on specific 

nonnative species of concern 

(mosquitofish and largemouth bass). 

Our response: The best available data 

show no relationship between the 

presence of nonnative fish and Oregon 

chub population abundance trends 

(Bangs et al. 2013, p. 17). Thirteen of the 

23 populations that met delisting 

criteria with either a stable or increasing 

abundance trend in 2013 occur with 

nonnative fish; 1 of the 2 populations 

that had a declining abundance trend 

occurs with nonnative fish (Bangs et al. 

2013, p. 17). Nonnative fish that are 

thought to have the potential to impact 

Oregon chub populations through 

predation and competition include 

largemouth bass, smallmouth bass 

(Micropterus dolomieu), bluegill 

(Lepomis macrochirus), pumpkinseed 

sunfish (Lepomis gibbosus), warmouth 

(Lepomis gulosus), green sunfish 

(Lepomis cyanellus), yellow perch 

(Perca flavescens), walleye (Sander 

vitreus), black crappie (Pomoxis 

nigromaculatus), white crappie 

(Pomoxis annularis), common carp 

(Cyprinus carpio), brown bullhead 

(Ameiurus nebulosus), yellow bullhead 

(Ameiurus natalis), and western 

mosquitofish (Markle et al. 1991, p. 91). 

We agree that western mosquitofish are 

potential predators on larval Oregon 

chub, and we have included an analysis 

of their impact in this final rule. While 

we acknowledge that some of these fish 

species may represent a larger threat to 

individual Oregon chub populations 

than others, we maintain that 

monitoring should include all nonnative 

species. We determine in the five factor 

analysis (see Factors A, C, and E) that 

the threats of nonnative fish to the 

Oregon chub have been ameliorated; 

thus, there is no existing or potential 

future significant threat that is 

inadequately addressed through existing 

regulatory mechanisms (see Factor D). 

Additionally, a regulatory mechanism is 

in place to prevent the translocation of 

nonnative fish. Within the State of 

Oregon, it is unlawful to transport, 

release, or attempt to release any live 

fish into the waters of this State (Oregon 

Administrative Rules (OAR) 635–007– 

0600). Abiotic factors such as water flow 

through connected habitats and 

variability in water temperature and 

depth keep largemouth bass and 

nonnative predators from becoming 

dominant in these habitats. Through the 

PDM, the ODFW will continue to 

monitor Oregon chub populations that 

are thriving, despite the presence of 

nonnative fish, to better understand the 

factors that allow this to occur. While 

we support efforts to limit the 

proliferation of nonnative fish in the 

Willamette River Basin, creating a 

management action for nonnative fish or 

addressing vector control guidelines is 

outside the scope of this rule and the 

PDM plan. 

Comment (7): Two peer reviewers and 

one public commenter discussed the 

need to consider the effects of climate 

change, environmental stochasticity, 

human population growth, and resulting 

changes in water availability on the 

viability and vulnerability of Oregon 

chub populations and suitable habitats. 

Primary concerns included effects to 

Oregon chub from: Extreme climatic 

variation (including drought effects, 

effects to instream flows, and increased 

reservoir drawdown); water temperature 

increases and reduced cool water 

refugia; the potential reduction in 

habitat size and quality; habitat 

fragmentation; and likely increases in 

populations of predatory and competitor 

nonnative fish species. 

Our response: The Service reviews the 

best scientific and commercial 

information available when conducting 

a threats analysis. In considering what 

factors might constitute a threat we 

must look beyond the mere exposure of 

the species to the factor to determine 

whether the exposure causes actual 

impacts to the species. The mere 

identification of factors that could 

negatively impact a species is not 

sufficient to compel a finding that 

listing (or maintaining a currently listed 

species on the Federal Lists of 

Endangered or Threatened Wildlife or 

Plants) is appropriate. We require 

evidence that these factors are operative 

threats currently acting on the species to 

the point that the species meets the 

definition of endangered or of 

threatened under the Act. 

The Service acknowledges that 

environmental changes could occur over 

the next several decades due to both 

climate change effects and human 

population growth. However, it is 

difficult to: (1) Predict with any 

certainty how those changes may 

influence Oregon chub populations and 

their habitats in the Willamette Valley, 

and (2) accurately describe and assess 

the net effects when considering the 

potential negative consequences 

together with the potential positive 

consequences to Oregon chub 

populations. Additional information 

and explanation was added to this final 

rule in the section on ‘‘Effects Related 

to Climate Change’’ (see Factor A). 

Comment (8): One commenter stated 

that if Oregon chub are delisted, the 

terms and conditions required under the 

Service’s biological opinion issued 

under section 7 of the Act to the USACE 

and other Federal agencies on the 


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continued operation and maintenance of 

dams in the Willamette River Basin will 

no longer be required, thereby removing 

key protections for the Oregon chub. 

This commenter also expressed a 

concern that delisting will eliminate 

consultation and agency review of 

actions permitted via the USACE permit 

program. 

Our response: Since 2002, the USACE 

has implemented minimum dam 

outflow targets that sustain downstream 

floodplain habitat, which has reduced 

the threat of habitat loss for the Oregon 

chub. These minimum flow targets will 

continue to be required into the future, 

even after the Oregon chub is delisted, 

under existing biological opinions from 

the Service and National Marine 

Fisheries Service (NMFS) on the 

USACE’s Willamette Valley Project 

(Service 2008b, pp. 40–51; NMFS 2008, 

pp. 2–43 to 2–52), because these 

biological opinions apply to other listed 

fish species (Upper Willamette spring 

chinook salmon (Oncorhynchus 

tshawytscha), Upper Willamette winter 

steelhead (Oncorhynchus mykiss), and 

bull trout (Salvelinus confluentus)). The 

USACE also has a memorandum of 

understanding (MOU) with The Nature 

Conservancy’s (TNC) Sustainable Rivers 

Project, an ongoing collaboration to 

promote ecologically sustainable flows 

below USACE dams in the Willamette 

River Basin (USACE and TNC 2000, 

2011; entire). For these reasons, we 

anticipate that the USACE will continue 

to meet these minimum flow targets 

after delisting of the Oregon chub. Also, 

the acquisition of floodplain habitat for 

long-term conservation and restoration, 

including off-channel locations 

preferred by the Oregon chub, has 

gained momentum in the Willamette 

River Basin by a variety of Federal, 

State, Tribal, local governmental, and 

nongovernmental agencies, which 

provides assurances that Oregon chub 

habitat will continue to be managed for 

the species. Given the MOU between the 

USACE and TNC regarding the 

Sustainable Rivers Project, and the 

minimum flows required under two 

existing biological opinions (NMFS 

2008, pp. 2–43 to 2–52; Service 2008b, 

pp. 40–51) for bull trout, Upper 

Willamette spring chinook, Upper 

Willamette winter steelhead, and their 

designated critical habitats, we 

anticipate that flow management 

trending towards natural flow regimes 

below Willamette Project dams will 

continue to create and rejuvenate offchannel habitats to the benefit of the 

Oregon chub into the foreseeable future. 

The USACE permits in-water work 

including construction and dredging in 

navigable waters under section 404 of 

the Clean Water Act (CWA; 33 U.S.C. 

1251 et seq.). While we acknowledge 

that consultation under section 7 of the 

Act will no longer be required for 

Oregon chub, the Service will continue 

to provide comments to the USACE on 

individual section 404 permits in the 

Willamette Valley through our 

authorities under the Fish and Wildlife 

Coordination Act (16 U.S.C. 661 et seq.). 

The USACE routinely sends the Service 

individual permit applications for our 

review, and we provide specific 

comments and recommendations to 

reduce negative effects to fish and 

wildlife, including unlisted species. For 

most section 404 projects, any potential 

negative impacts to habitat and species 

are generally short-term. While in-water 

work has the potential to impact 

individual Oregon chub populations, 

this impact for the overall population is 

considered a low risk because the 

species is widely distributed across 

multiple subbasins with many abundant 

populations. In the past 4 years, we 

have received approximately 13 such 

requests to review section 404 permits 

from the USACE. Of those 13 projects, 

we found that 9 were not likely to 

adversely affect Oregon chub and 2 

projects only required technical 

assistance; we completed 1 formal 

consultation for a river restoration study 

that only anticipated short-term effects 

and long-term benefits. The last project 

was an emergency consultation when 

the USACE had to take action to 

maintain water levels in Oregon chub 

habitat on their property, as the habitat 

was affected by atypical, unexpected 

operations necessary for dam safety. The 

USACE worked with the ODFW to 

introduce Oregon chub into Hills Creek 

Pond during the drawdown as a backup to the Dexter RV Park Pond ‘‘DEX3’’ 

and the Dexter Reservoir Alcove ‘‘PIT1’’ 

populations, in case either population 

failed during the drawdown. 

Comment (9): One commenter stated 

that there are no regulatory mechanisms 

to protect Oregon chub habitat in the 

floodplain habitats that have been 

acquired for long-term conservation and 

restoration. 

Our response: We disagree. One of the 

factors identified as a threat to Oregon 

chub at the time of listing was habitat 

loss. This threat has been ameliorated 

by the actions of multiple conservation 

partners over the last 20 years. In 2010, 

the Bonneville Power Administration 

(BPA) and the State of Oregon signed 

the Willamette River Basin 

Memorandum of Agreement Regarding 

Wildlife Habitat Protection and 

Enhancement (BPA and ODFW 2010, 

entire). The Agreement established goals 

for mitigating the effects of the 

construction, inundation, and operation 

of the Willamette River Basin Flood 

Control Projects in the Willamette 

Valley. Under the terms of the 

Agreement, the State of Oregon and the 

BPA agreed to acquire at least an 

additional 16,880 acres (ac) (6,831 

hectares (ha)) of wildlife mitigation 

property to protect 26,537 ac (10,739 ha) 

(or more) by the end of 2025. 

Throughout the Willamette River Basin, 

floodplain properties have been, and 

will continue to be, acquired. All habitat 

acquisitions funded by the BPA must 

include provisions for permanent 

protections and enforcement of those 

protections. The acquisition of 

floodplain habitat for long-term 

conservation and restoration through 

these mechanisms provides assurances 

that Oregon chub habitats will continue 

to be managed for the species into the 

foreseeable future. 

Summary of Factors Affecting the 

Species 

This section contains updated 

information and associated analysis 

from that presented in the proposed rule 

(79 FR 7136, February 6, 2014). Updated 

information includes data collected 

during the 2013 field season (Bangs et 

al. 2013, entire) and additional 

information requested by peer and 

public reviewers. 

Section 4 of the Act and its 

implementing regulations (50 CFR part 

424) set forth the procedures for listing 

species, reclassifying species, or 

removing species from listed status. 

‘‘Species’’ is defined by the Act as 

including any species or subspecies of 

fish or wildlife or plants, and any 

distinct vertebrate population segment 

of fish or wildlife that interbreeds when 

mature (16 U.S.C. 1532(16)). A species 

may be determined to be an endangered 

or threatened species due to one or more 

of the five factors described in section 

4(a)(1) of the Act: (A) The present or 

threatened destruction, modification, or 

curtailment of its habitat or range; (B) 

overutilization for commercial, 

recreational, scientific, or educational 

purposes; (C) disease or predation; (D) 

the inadequacy of existing regulatory 

mechanisms; or (E) other natural or 

manmade factors affecting its continued 

existence. We must consider these same 

five factors in delisting a species. We 

may delist a species according to 50 

CFR 424.11(d) if the best available 

scientific and commercial data indicate 

that the species is neither endangered 

nor threatened for the following reasons: 

(1) The species is extinct; (2) the species 

has recovered and is no longer 

endangered or threatened (as is the case 

with the Oregon chub); and/or (3) the 


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original scientific data used at the time 

the species was classified were in error. 

A recovered species is one that no 

longer meets the Act’s definition of 

endangered or of threatened. 

Determining whether the status of a 

species has improved to the point that 

it can be delisted or downlisted requires 

consideration of whether the species is 

endangered or threatened because of the 

same five categories of threats specified 

in section 4(a)(1) of the Act. For species 

that are already listed as endangered or 

threatened, this analysis of threats is an 

evaluation of both the substantial 

threats currently facing the species and 

the threats that are reasonably likely to 

affect the species in the foreseeable 

future following the delisting or 

downlisting and the removal or 

reduction of the Act’s protections. 

A species is an ‘‘endangered species’’ 

for purposes of the Act if it is in danger 

of extinction throughout all or a 

‘‘significant portion of its range’’ and is 

a ‘‘threatened species’’ if it is likely to 

become endangered within the 

foreseeable future throughout all or a 

‘‘significant portion of its range.’’ The 

word ‘‘range’’ in the significant portion 

of its range phrase refers to the range in 

which the species currently exists. For 

the purposes of this analysis, we will 

first evaluate whether the currently 

listed species, the Oregon chub, should 

be considered endangered or threatened 

throughout all its range. Then we will 

consider whether there are any 

significant portions of the Oregon 

chub’s range where the species is in 

danger of extinction or likely to become 

so within the foreseeable future. 

The Act does not define the term 

‘‘foreseeable future.’’ For the purpose of 

this rule, we define the ‘‘foreseeable 

future’’ to be the extent to which, given 

the amount and substance of available 

data, we can anticipate events or effects, 

or reliably extrapolate threat trends, 

such that we reasonably believe that 

reliable predictions can be made 

concerning the future as it relates to the 

status of the Oregon chub. In 

considering the foreseeable future as it 

relates to the status of the Oregon chub, 

we considered the factors affecting the 

Oregon chub, historical abundance 

trends, and ongoing conservation 

efforts. 

The following analysis examines all 

five factors currently affecting, or that 

are likely to affect, the Oregon chub 

within the foreseeable future. 

A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of Its Habitat or Range 

When the Oregon chub was listed as 

endangered in 1993, the species was 

known to exist at nine locations, 

representing only 2 percent of the 

species’ historical range (Markle 1991, 

pp. 288–289; Scheerer et al. 2007, p. 2; 

58 FR 53800, October 18, 1993, p. 

53800). The decline in Oregon chub 

abundance and distribution was 

attributed to the extensive 

channelization, dam construction, and 

chemical contamination that occurred 

in the Willamette River Basin, 

particularly from the 1940s through the 

late 20th century (Pearsons 1989, pp. 

29–30). 

Since listing, concerted efforts by 

Federal, State, and local governments 

and private landowners have greatly 

reduced the threats to the Oregon chub. 

For example, the introduction of the 

Oregon chub into secure habitats has 

created refugial populations in habitats 

that are isolated from the threats of 

habitat loss and invasion by nonnative 

fishes. Additionally, as explained 

below, research has expanded our 

understanding of suitable habitat for the 

Oregon chub, and increased survey 

efforts have led to the discovery of many 

natural populations. Since 2002, the 

USACE has implemented minimum 

dam outflow targets that sustain 

downstream floodplain habitat, which 

has reduced the threat of habitat loss for 

the Oregon chub. These minimum flow 

targets will continue to be required into 

the future under existing biological 

opinions from the Service and NMFS on 

the USACE’s Willamette River Basin 

Project (see description below). The 

USACE also has a MOU with TNC 

regarding the Sustainable Rivers Project, 

an ongoing collaboration to promote 

ecologically sustainable flows below 

USACE dams in the Willamette River 

Basin. For these reasons, we anticipate 

that the USACE will continue to meet 

these minimum flow targets after 

delisting of the Oregon chub. Also, the 

acquisition of floodplain habitat for 

long-term conservation and restoration, 

including off-channel locations 

preferred by the Oregon chub, has 

gained momentum in the Willamette 

River Basin by a variety of Federal, 

State, Tribal, local governmental and 

nongovernmental agencies, which 

provides assurances that Oregon chub 

habitat will continue to be managed for 

the species. 

Since 1992, the Oregon chub was 

introduced and established in 21 secure, 

isolated habitats (Bangs et al. 2013, p. 

15). These populations contribute to 

recovery by providing redundancy to 

the naturally occurring populations, 

increasing the abundance of the Oregon 

chub in each recovery area, and 

providing refugial habitat that is less 

vulnerable, as compared to connected 

habitats, to the threats of habitat loss 

and invasion by nonnative fishes. The 

majority of Oregon chub individuals 

occur in populations at these 

introduction sites. In 2013, we 

estimated 106,408 Oregon chub in the 

21 introduced populations. By contrast, 

we estimated 53,255 Oregon chub in the 

56 naturally occurring populations. 

Eleven of the introduction sites are in 

public ownership by Federal and State 

agencies that manage these sites for 

conservation of the Oregon chub, and 

we have no information that suggest 

these sites would be managed otherwise 

into the foreseeable future. 

The remaining 10 introduction sites 

are privately owned. Many of these 

introduction sites were created or 

restored under the Service’s Partners for 

Fish and Wildlife Program managed by 

the staff of the Willamette Valley 

National Wildlife Refuge Complex. Most 

of these landowners have either signed 

conservation agreements or are 

participating in our Safe Harbor 

Program. In the interest of conserving 

the Oregon chub, our Safe Harbor 

Program participants volunteered to 

allow the introduction of the Oregon 

chub into ponds on their land, and 

signed management plans called 

cooperative agreements, which are 

designed to protect the species and its 

habitat. In exchange, the landowners 

received an incidental take permit that 

extended an exemption from take 

prohibitions under section 9 of the Act. 

If the Oregon chub is delisted, the 

species will no longer be protected 

under these take prohibitions and the 

incidental take permit associated with 

the safe harbor agreements will no 

longer be in effect. This means that 

landowners will no longer be legally 

bound to protect the species on their 

property. However, we anticipate, based 

on their past interest and cooperation in 

protecting the species, that most or all 

of these landowners will continue to 

manage their land for conservation of 

the Oregon chub into the future as 

described in their cooperative 

agreements. We will also seek to extend 

these agreements beyond their initial 

10-year time period and, in the event 

the property is later sold or transferred, 

we will work with the future 

landowners to enroll them in a 

cooperative agreement. 

In 2013, 20 of the 23 populations that 

met the recovery plan criteria for 

delisting were located on State, Federal, 

Tribal, or other property managed for 

long-term conservation; 3 populations 

were located on privately owned 

property. The close knit working 

relationship with private landowners is 

extremely important for the recovery of 


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Oregon chub; 40 percent of all Oregon 

chub populations exist on privately 

owned property. We see no reason why 

the conservation efforts of landowners 

would cease after delisting, as all efforts 

have been voluntary. There are an 

additional 9 recently discovered or 

introduced populations that exist on 

public lands with abundances greater 

than 500 adult Oregon chub, further 

supporting our determination to delist 

the species. 

In the 2008 5-year review of the status 

of the Oregon chub (Service 2008a, p. 

26), we identified concerns about the 

ability to achieve recovery due to the 

focus on managing primarily isolated 

populations with limited genetic 

exchange. To reduce threats associated 

with habitat isolation, we suggested that 

future recovery efforts should integrate 

habitat that is connected to the 

floodplain. Successful efforts to 

integrate floodplain habitat into Oregon 

chub recovery were facilitated in part 

through consultation with several 

Federal agencies under section 7 of the 

Act. Specifically, in 2008, the Service 

and the NMFS completed consultation 

with the USACE, BPA, and the Bureau 

of Reclamation under section 7 of the 

Act on the continued operation and 

maintenance of 13 large flood-control 

dams in the Willamette River Basin, 

collectively known as the Willamette 

River Basin Project (Willamette Project). 

The Service’s biological opinion 

considered the Willamette Project’s 

effects to the Oregon chub, the bull 

trout, and bull trout critical habitat 

(Service 2008b, entire), while the 

NMFS’ biological opinion considered 

effects to threatened salmon and 

steelhead (salmonids) and associated 

critical habitat (NMFS 2008, entire). The 

terms and conditions of the Service’s 

biological opinion required the USACE 

to fund a floodplain study that would 

increase our understanding of the effects 

of flow management on connected 

downstream Oregon chub habitat. The 

ODFW subsequently pursued 

opportunities to study these effects and 

to integrate floodplain habitat in 

recovery efforts, in part, through 

funding provided by the USACE under 

the terms and conditions of the 

biological opinion. 

The floodplain study required by the 

Willamette Project biological opinion 

began in 2009 (Bangs et al. 2010a, p. 1). 

Under this study, the ODFW sampled 

fish assemblages and monitored habitat 

conditions (i.e., bathymetry, pond 

volume, percent vegetation, water 

temperature) in several off-channel 

habitats in the Middle Fork Willamette 

River downstream of Dexter Dam in 

Lowell, Oregon, to Jasper, Oregon 

(Bangs et al. 2010a, pp. 2–4). The ODFW 

chose the Dexter to Jasper reach of the 

Middle Fork Willamette River as a study 

area because several off-channel habitats 

in this reach were known to be occupied 

by the Oregon chub, and the majority of 

the adjacent land is in public ownership 

and accessible. 

The ODFW sampled most of the 

hydrologically connected, off-channel 

habitat in this reach and discovered that 

the Oregon chub also occupied sites 

previously thought to be unsuitable. 

These sites contain greater habitat 

complexity than sites where Oregon 

chub were previously known to occur. 

Although these habitats have features 

such as beaver dams and shallow, 

inundated benches that were known to 

provide suitable habitat for Oregon 

chub, the recently discovered sites also 

include channels that have frequent 

connectivity to the adjacent river 

channel (Bangs 2013, pers. comm.). 

Frequently connected sites such as these 

were thought to be unsuitable because 

these sites were accessible to nonnative 

fishes that prey upon or compete with 

the Oregon chub for resources. 

The discovery of Oregon chub in 

these connected sites facilitated a better 

understanding of the diversity of 

habitats occupied by Oregon chub, and 

prompted the ODFW to shift their basinwide sampling efforts from primarily 

focusing on isolated habitats or habitats 

with infrequent river connection to 

sampling frequently connected, offchannel habitats. They sampled similar 

habitat in other recovery subbasins and 

found that Oregon chub also occupied 

many of these frequently connected 

habitats. Between 2009 and 2013, the 

ODFW discovered 34 additional Oregon 

chub populations throughout the 3 

recovery subbasins (Bangs et al. 2013, 

pp. 6–8). In 2013, 14 of the 23 

populations that met the delisting 

criteria were in naturally occurring 

sloughs, beaver pools, and pond 

habitats. Fifty-six of the 77 habitats 

containing Oregon chub were naturally 

occurring; 21 populations were 

introduced. In addition, 50 Oregon chub 

populations are located in habitat that 

experiences some level of connectivity 

to the adjacent river channel. The 

Service has determined that the 

minimum aquatic area necessary to 

support a population of at least 500 

adult Oregon chub is 500 square meters 

(m2) (5,400 square feet (ft2)) (74 FR 

10412, March 10, 2009, p. 10417). Out 

of the 77 populations, only a single 

location, Dougren Island Slough, has an 

aquatic area smaller than 500 m2 (5,400 

ft2); the site is 400 m2 (4,300 ft2) and 

supported 1,700 adult Oregon chub in 

2013. 

Several anthropogenic and natural 

environmental factors, discussed below, 

may continue to have effects on Oregon 

chub and its habitat in the foreseeable 

future. Many of these factors are 

included in this discussion because the 

Service previously identified them as 

threats to the continued existence of the 

species in the listing and downlisting 

rules. Additionally, new factors 

affecting the species are discussed. 

Activities Related to the Willamette 

Project 

The Oregon chub occupies 45 

connected habitats that are downstream 

of Willamette Project dams or adjacent 

to reservoirs; these habitats are 

influenced by Willamette Project 

operations. The Willamette Project 

biological opinions were signed in 2008, 

and continue until 2023 (NMFS 2008, p. 

1–11; Service 2008b, p. 85). In addition 

to normal operations of the Willamette 

Project, several actions required under 

the terms and conditions of the 

biological opinions may affect Oregon 

chub populations and habitat in the 

future. 

Temperature and flow 

augmentation—The USACE is 

implementing a number of structural 

and operational changes to alter flows 

and water temperatures downstream of 

Willamette Project dams to increase 

survival of federally listed salmon and 

steelhead (salmonids). These 

operational and structural changes have 

resulted in downstream water 

temperatures closer to that which 

existed prior to the construction of the 

dams (i.e., river temperatures 

downstream of the reservoirs are now 

warmer in early summer, and cooler in 

the late summer and early fall). The 

USACE also operates to meet mainstem 

and tributary flow objectives identified 

in the Willamette Project biological 

opinion to benefit listed salmonids; 

these flows also benefit the Oregon chub 

by sustaining floodplain habitat 

downstream. In addition, the USACE 

works with partners in the Willamette 

River Basin as part of TNC’s Sustainable 

Rivers Project to implement a set of 

environmental flow objectives designed 

to improve channel morphology in a 

manner that will create and sustain 

new, and improve existing, fish habitat 

(Gregory et al. 2007, p. 11). 

The effects of water flow 

augmentation and temperature 

normalization on fish communities in 

off-channel habitat are largely unknown. 

The ODFW has a monitoring program in 

place (Bangs et al. 2011a, entire) to 

detect any negative effects on Oregon 

chub and its habitat. With the delisting 

of Oregon chub, this monitoring 


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program, which is detailed in our PDM 

plan, will continue for several years 

post-delisting (Service and ODFW 2013, 

entire). The PDM plan identifies 

thresholds and responses for detecting 

and reacting to significant changes in 

Oregon chub protected habitat, 

distribution, and persistence. If declines 

are detected that exceed the thresholds, 

the Service, in combination with other 

PDM participants, will investigate 

causes of these declines and determine 

if the Oregon chub warrants expanded 

monitoring, additional research, 

additional habitat protection, or 

relisting as an endangered or threatened 

species under the Act. Additional 

discussion about temperature and 

instream flows is presented in the 

‘‘Effects of Climate Change’’ section 

(also in Factor A). 

Reservoir drawdowns—As required in 

the NMFS biological opinion for the 

Willamette Project, the USACE is 

implementing an annual complete 

reservoir drawdown of Fall Creek 

Reservoir on the Middle Fork 

Willamette River. The biological 

objectives of the reservoir drawdown are 

to improve fish passage efficiency and 

survival of juvenile Chinook salmon 

migrating out of Fall Creek Reservoir, 

and to reduce nonnative fish 

populations inhabiting the Fall Creek 

Reservoir. This is expected to result in 

reduced nonnative predation and 

competition with juvenile Chinook 

salmon rearing in the reservoir. While 

reservoir drawdown benefits Chinook 

salmon, there are potential negative 

effects to the Oregon chub from 

sedimentation of Oregon chub habitats. 

Willamette River Basin flood control 

dams inhibit the transport of sediment 

downstream, causing sedimentation to 

occur in the reservoirs. During a 

complete reservoir drawdown, released 

reservoir water scours the reservoir bed 

and transports sediment downstream. 

During the initial Fall Creek Reservoir 

drawdowns, a massive volume of silt, 

sand, and debris was flushed, causing 

sediment deposition to occur in offchannel habitats downstream of the 

dam. Sampling for Oregon chub 

populations in the Fall Creek drainage 

occurred after the first drawdown and 

three previously undocumented Oregon 

chub populations were found. The 

extent to which these populations were 

affected is unknown because Oregon 

chub were discovered at these sites after 

the sedimentation occurred and we 

cannot determine the area of habitat or 

number of Oregon chub that existed 

prior to the sedimentation. Fewer than 

five Oregon chub were found in each of 

these three sites after the sedimentation 

occurred. These sites experienced the 

accumulation of fine sediments, perhaps 

beyond typical historical levels, which 

reduced the amount of habitat available 

to Oregon chub (Bangs 2013, pers. 

comm.). However, little sedimentation 

was observed in the few Oregon chub 

habitats that occur farther downstream 

of the confluence of Fall Creek and the 

Middle Fork Willamette River. Most of 

the abundant populations of Oregon 

chub in off-channel habitats of the 

Middle Fork Willamette River were not 

affected because they occur upstream of 

these impacts. 

Although partial drawdowns of 

Willamette Project reservoirs are likely 

to occur in the near future, they are 

unlikely to result in large volumes of 

sediment moving downstream because 

the water level will remain above the 

sediment bed and little sediment will be 

moved. Complete reservoir drawdowns 

to the extent seen at Fall Creek are not 

currently planned at other reservoirs. 

The effects of a complete reservoir 

drawdown would vary by location; it is 

difficult to predict what habitat changes 

may occur downstream. However, any 

future proposal to implement this scale 

of drawdown will include extensive 

coordination and planning among the 

Service, ODFW, USACE, and other land 

managers. Additionally, in cooperation 

with the USACE, we developed 

monitoring guidance and recommended 

responses in the event a drawdown is 

planned (Service and ODFW 2013, pp. 

18–19). We do not anticipate that 

potential negative impacts from 

reservoir drawdowns will affect the 

overall status of Oregon chub. 

Additional discussion about reservoir 

drawdown is presented in the ‘‘Effects 

of Climate Change’’ section (also in 

Factor A). 

Another concern related to 

drawdowns is that nonnative predatory 

fishes are common in reservoir habitats. 

During a drawdown, these fish are likely 

transported downstream, where they 

may invade off-channel habitats. The 

risks to the Oregon chub associated with 

nonnative fishes are discussed under 

Factors C and E, below. 

Reservoir water level fluctuations— 

Fluctuating water levels in Lookout 

Point Reservoir on the Middle Fork 

Willamette River may limit the breeding 

success of the Oregon chub population 

in Hospital Pond, which provides 

habitat for the species in a pool 

connected to the reservoir by a culvert 

(Service 2008b, p. 160). Between 2001 

and 2003, the USACE, which manages 

Lookout Point Reservoir as part of the 

Willamette Project, implemented a 

series of actions to protect the 

population of Oregon chub in Hospital 

Pond. The goal was to allow the USACE 

to manage the water level in Lookout 

Point Reservoir independently of the 

water elevation in Hospital Pond. In 

order to achieve this, they installed a 

gate on Hospital Pond’s outlet culvert 

and lined the porous berm between the 

pond and reservoir (Service 2002, pp. 1– 

11). They also excavated additional 

areas to create more suitable spawning 

habitat in the pond (Service 2003, pp. 

1–3). 

Despite these actions, water elevation 

in Hospital Pond continues to be 

influenced by reservoir water levels. 

Hospital Pond currently supports a 

large, stable population of the Oregon 

chub; however, future Willamette 

Project operations may result in 

reservoir elevations that are below the 

levels necessary to inundate the 

spawning habitat in Hospital Pond 

(Service 2008b, p. 160). This reduction 

in spawning habitat may result in 

limited breeding success for the Oregon 

chub in Hospital Pond into the 

foreseeable future. However, the 

Hospital Pond population is not critical 

to meeting recovery criteria because 

additional surveys in the Middle Fork 

Willamette River subbasin have found 

that the subbasin has the highest 

number of Oregon chub populations (29 

populations) across the range of the 

species. Currently, 17 of the Oregon 

chub sites in this subbasin have 

abundant (greater than 500 individuals) 

populations of the Oregon chub. This 

redundancy of large populations 

provides additional security to the 

species in the event that single 

populations decline. 

Inability to meet minimum flow 

targets—During low water or drought 

years, the USACE may not be able to 

meet the seasonal minimum water flow 

targets established in the Willamette 

Project biological opinions. Analysis 

performed by the USACE determined 

that from 1936 to 1999, low flow and 

drought conditions occurred 9 percent 

and 16 percent of the years, respectively 

(USACE 2007, pp. 2–45). If this occurs 

in the future, it may have negative 

effects on Oregon chub habitat 

downstream through a temporary 

reduction in pond volume and 

increased water temperatures. Under the 

floodplain study, the ODFW mapped 

the bathymetry (habitat depth) and 

installed equipment to measure pond 

elevation, area, volume, and 

temperature in Oregon chub sites that 

are influenced by Willamette Project 

flows. This information was used to 

determine the effect that low flows may 

have on the extent of habitat area 

available to Oregon chub. The USACE 

has considered these data in managing 

flows and has a notification process in 


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place to coordinate with the Service and 

the ODFW during low water periods 

before flows are reduced to levels below 

the minimum flow targets. To date, 

except for during malfunctions and 

emergency operations explained below, 

flows below minimum targets have been 

of short duration and have not resulted 

in observable adverse effects to Oregon 

chub populations (Bangs 2013, pers. 

comm.). Further, when minimum targets 

cannot be met, the Service, ODFW, 

NMFS, and USACE coordinate on a 

regular basis to discuss reduced flow 

releases in advance; this coordination 

allows the Service to weigh in on the 

magnitude of reductions and mitigate 

any reductions in flows that may affect 

Oregon chub populations. This 

coordination will continue into the 

future, as required by the two biological 

opinions, for other listed fish species 

(Service 2008b, pp. 38–40; NMFS 2008, 

pp. 2–39 to 2–43). 

Willamette Project malfunctions and 

emergency operations resulting in the 

USACE not meeting minimum flow 

targets or necessitating restrictions on 

reservoir pool elevations have affected 

Oregon chub habitats. These incidents 

have been infrequent, but resulted in 

short-term negative effects on a few 

Oregon chub populations. For instance, 

in 2009, two of the three spillway gates 

at the USACE Big Cliff dam on the 

North Santiam River failed (Bangs et al. 

2010b, p. 16). While repairing the gates, 

the outflow from Big Cliff Dam was 

reduced to below the minimum summer 

flow target. Record high air 

temperatures coincided with the low 

flow levels. Monitoring during this 

event detected that three Oregon chub 

sites downstream were nearly 

desiccated and fish mortalities were 

observed. Screened pumps were used to 

increase the volume of water in the 

ponds and to reduce water 

temperatures. The effects of this 

incident on Oregon chub populations 

were short-term, and the numbers of 

Oregon chub in these three populations 

have either increased or are exhibiting 

a stable trend (Bangs et al. 2013, pp. 6– 

8). 

The minimum flow targets protect not 

only the Oregon chub, but many other 

native aquatic species, including listed 

salmonids. If the Oregon chub is 

delisted, these minimum flow targets 

will continue to be required under 

existing biological opinions from the 

Service and the NMFS on the 

Willamette Project for listed bull trout, 

Chinook salmon, and steelhead. 

Moreover, the USACE was proactive in 

implementing recommended flows 

before the Willamette Project biological 

opinions were completed (USACE 2007, 

pp. 3–19). Therefore, we anticipate that 

the USACE will continue to meet these 

minimum flow targets after delisting of 

the Oregon chub, except under 

infrequent, extreme conditions such as 

drought. 

In 2010, the USACE determined that 

the condition and reliability of the 

spillway gates at 13 Willamette Project 

dams represented an unacceptable risk 

to public safety (Bangs et al. 2011b, p. 

16). To mitigate this risk, the USACE 

proposed implementing pool elevation 

restrictions at Willamette Project 

reservoirs to lower than normal levels to 

support maintenance and repair of the 

spillway gates. The imposed restrictions 

affected one population (Dexter 

Reservoir Alcove ‘‘PIT1’’ site) of Oregon 

chub by reducing the pond below levels 

critical for Oregon chub survival. The 

Dexter Reservoir Alcove ‘‘PIT1’’ site had 

filled with sediment over the years and 

in consultation with the USACE, we 

determined that removing some of this 

sediment was the best measure to 

prevent desiccation of the pond. Prior to 

removing sediment, the ODFW captured 

and relocated a total of 1,127 Oregon 

chub to Hills Creek Pond, a site with 

perennial flow located on USACE 

property at Hills Creek Dam. This site is 

within the historical range of Oregon 

chub, but at the time was not occupied 

by the species. The pond site is adjacent 

to the Middle Fork Willamette River and 

has historically been managed by 

USACE staff for wildlife habitat 

enhancement. The spillway gate repairs 

were completed, the pool elevation 

restriction for Dexter Reservoir was 

lifted in 2011, and the reservoir has 

returned to normal operations. The 

Oregon chub population abundance in 

Dexter Reservoir Alcove ‘‘PIT1’’ site and 

Dexter RV Park Pond ‘‘DEX3’’ are both 

currently stable and contribute towards 

meeting recovery criteria for delisting 

(Bangs et al. 2013, p. 8). The 

translocation of Oregon chub into Hills 

Creek Pond created a large, secure 

population that is now the largest 

Oregon chub population within the 

Middle Fork Willamette River subbasin 

with an estimated abundance of 14,610 

Oregon chub (Bangs et al. 2013, p. 8). 

Additional discussion about minimum 

flow requirements is presented in the 

‘‘Effects of Climate Change’’ section 

(also in Factor A). 

Siltation Resulting From Timber Harvest 

As previously noted, Oregon chub 

habitats are generally associated with 

low gradient floodplain habitats not 

generally subject to timber harvest 

activities. However, there are a small 

number of Oregon chub populations 

that exist within, or adjacent to, forested 

landscapes that were, or could be, 

subject to adverse effects of timber 

harvest. These adverse effects include 

siltation (deposition of fine sediment) of 

stream habitats from ground-disturbing 

activities involved with standard 

logging practices. State and private 

lands in Oregon are subject to water 

quality as well as fish and wildlife 

protective measures under the Oregon 

Forest Practices Act, whereas Federal 

lands are subject to land and resource 

management plans that also provide 

protective guidelines for water quality 

and fish and wildlife protections. While 

siltation resulting from timber harvest 

has not been identified as a significant 

threat to Oregon chub, there is at least 

one instance where siltation from timber 

harvest may have contributed to a 

decrease in habitat suitability and 

availability that resulted in a drop in 

chub abundance. 

In the 1990s, timber harvest occurred 

on private lands upstream of East Fork 

Minnow Creek. Flood events in the 

watershed in 1996, 1997, and 1998 

caused accelerated siltation into East 

Fork Minnow Creek Pond, a pond 

downstream that is occupied by Oregon 

chub, and over half of the habitat was 

lost (Scheerer 2009, pers. comm.). The 

Oregon chub population in East Fork 

Minnow Creek Pond declined 

dramatically following these events 

(Scheerer 2009, pers. comm.). In 2010, 

the Oregon Department of 

Transportation excavated accumulated 

sediment in the pond and created a pool 

that will provide a buffer from the 

effects of future siltation. The 

population subsequently rebounded and 

it now meets the delisting criterion for 

a stable or increasing trend over 7 years. 

In 2012, timber harvest on private 

land occurred upstream of an Oregon 

chub site on the William L. Finley 

National Wildlife Refuge (Finley NWR) 

known as Gray Creek Swamp. Due to 

concerns about potential sedimentation 

to Oregon chub habitat in Gray Creek 

Swamp, we negotiated with the 

landowner who agreed to increase the 

width of the no-cut riparian buffer along 

the streams within the harvest area to 

reduce the risk of siltation in Oregon 

chub habitat downstream. Siltation of 

this Oregon chub habitat following 

harvest has not been observed, but the 

site will continue to be monitored by 

the ODFW during the 9-year postdelisting monitoring period. 

The potential for adverse effects to 

Oregon chub habitat from timber harvest 

was also identified at three other sites: 

Dexter Reservoir Alcove ‘‘PIT1’’ site, 

Buckhead Creek, and Wicopee Pond 

(Scheerer 2008, pers. comm.). However, 

we did not observe levels of siltation at 


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these sites that resulted in habitat loss, 

and all of the Oregon chub populations 

within each of the five sites located 

downstream of harvest activities met the 

delisting criteria in 2013. Additionally, 

the U.S. Forest Service (USFS) manages 

several Oregon chub sites within the 

Willamette National Forest. As noted 

above, forests managed by the USFS 

operate under land and resource 

management plans that include 

management practices protective of fish 

(USFS 1990, pp. IV–61–64), and we 

anticipate these resource management 

plans will continue to guide forest 

management into the future. 

While future siltation of habitats 

occupied by Oregon chub from timber 

harvest activities clearly is possible, the 

frequency is anticipated to be very low, 

as will be the potential number of 

affected populations. Given this fact, 

and the protections afforded by the 

Oregon Forest Practices Act and Federal 

land management plans, we do not 

believe siltation from timber harvest 

represents a substantial population-level 

threat to Oregon chub now or in the 

foreseeable future. 

Floods and Seasonal High-Water Events 

The Oregon chub is a low-elevation, 

floodplain-dependent species that 

evolved under dynamic environmental 

conditions created by seasonal flooding 

and droughts. As a result, the species’ 

life history reflects these dynamic 

conditions. While floods and seasonal 

high-water events constitute a potential 

stressor to individuals or specific 

Oregon chub populations, these events 

create and maintain off-channel habitats 

necessary for the long-term persistence 

of the species, and they function to 

transport the Oregon chub to colonize 

these new sites. 

For example, in 2007, a flood event in 

the Santiam River caused channel 

avulsion (a shift in the stream channel 

that results in the rapid abandonment of 

a river channel and formation of a new 

river channel) at an Oregon chub site, 

reducing the extent of habitat available 

at this location and likely negatively 

affecting this population. Yet in another 

example, between 2000 and 2003, new 

off-channel habitat formed in the 

McKenzie River due to flooding and, 

after aquatic vegetation became 

established, the site was subsequently 

colonized by the Oregon chub (Bangs 

2013, pers. comm.). Although we cannot 

predict the magnitude or the extent to 

which current Oregon chub habitats 

may be affected by flooding and 

seasonal high water events, the number 

and distribution of large populations, in 

combination with habitat heterogeneity, 

increases the species’ resilience in 

recovering from periodic disturbance, as 

the species would have historically. 

Additional discussion about increased 

flood events is presented in the ‘‘Effects 

of Climate Change’’ section (also in 

Factor A). 

Water Quality Issues 

The analysis of threats in the final 

rule to list the Oregon chub as an 

endangered species and the recovery 

plan for the species discussed numerous 

potential threats to water quality in 

Oregon chub habitats. However, in the 

20 years since the Oregon chub was 

listed, only a few of these concerns, 

discussed below, have materialized, and 

even then, these were localized and of 

short duration. 

In the spring of 2011, the ODFW 

noted the complete die-off of the 

introduced Oregon chub population in 

Cheadle Pond on the Finley NWR. They 

assessed the water quality (temperature, 

pH, and dissolved oxygen) and 

discovered that the pH level was 

abnormally high (mean pH: 9.6, range: 

8.4–10.2). The pH level in Oregon chub 

habitats typically ranges between 7.42 

and 8.66. The cause of the increased pH 

level was unknown and had not been 

observed previously at this site. The 

ODFW subsequently conducted an insitu 7-day bioassay using 30 adult 

Oregon chub from the Gray Creek 

Swamp population. All of the Oregon 

chub survived the trial and were 

released into Cheadle Pond following 

the bioassay. We have not observed, and 

do not anticipate based on this one 

event, similar incidents in other Oregon 

chub habitats. 

Nutrient enrichment may have caused 

the extirpation of the Oregon chub 

population at Oakridge Slough in the 

Middle Fork Willamette River subbasin. 

The slough is downstream from the 

Oakridge Sewage Treatment Plant, and 

increased nitrogen and phosphorus 

concentrations were detected in the 

slough prior to a decline in the 

population. While the nutrient 

concentrations are not believed to be 

directly harmful to the species, the 

elevated nutrient levels may have 

contributed to habitat conditions that 

were unsuitable for Oregon chub (i.e., 

an increase in growth of algae, which 

then decomposed and led to low oxygen 

conditions below what the Oregon chub 

requires to survive) (Buck 2003, p. 12). 

Several Oregon chub sites are located 

adjacent to agricultural land. Runoff 

from farm fields may contain pesticides 

or fertilizers that could adversely affect 

the water quality in Oregon chub 

habitats. However, many of these sites 

have protective vegetated buffers 

between crops and the aquatic habitat. 

To date, we have not observed declines 

in Oregon chub populations that can be 

attributed to agricultural practices, and 

several Oregon chub habitats located 

adjacent to farmland have supported 

abundant populations of Oregon chub 

for many years. 

Several Oregon chub sites are located 

adjacent to private forestland (as 

previously discussed above under 

‘‘Siltation Resulting from Timber 

Harvest’’). Additionally, the USFS 

manages several Oregon chub sites 

within the Willamette National Forest. 

Forests managed by the USFS operate 

under land and resource management 

plans that include management 

practices protective of fish (USFS 1990, 

pp. IV–61–64), and we anticipate these 

resource management plans will 

continue to guide forest management 

into the foreseeable future. On private 

forestland, the use of chemicals is 

regulated by the Oregon Department of 

Forestry, and operators are required to 

comply with product labels and 

additional protective measures to 

protect waters of the State, including 

leaving untreated vegetated buffers and 

limiting aerial applications near areas of 

standing open water larger than onequarter acre (Oregon Revised Statutes 

(ORS) 527.765 and OAR 629–620–0000 

through 629–620–0800). Although we 

have no information regarding 

landowners’ compliance with these 

rules on forestland in the vicinity of 

Oregon chub habitats, we have not 

observed harmful effects to Oregon chub 

populations due to chemical exposure 

related to forestry operations. 

During our analysis of the factors 

affecting the Oregon chub, we 

determined that spills via sewage 

discharge, hazardous cargo from trucks, 

railways and pipelines, which were 

identified as threats when the species 

was first listed, no longer pose a 

significant threat to the species. At the 

time of listing, of the nine Oregon chub 

populations known to exist, seven of 

these locations were directly adjacent to 

major transportation corridors where 

threats to water quality had the 

potential to impact Oregon chub. 

Currently, Oregon chub have been 

documented in 77 populations widely 

distributed throughout the Willamette 

River Basin; 20 of these locations are 

adjacent to transportation corridors. In 

addition, two populations are adjacent 

to sewage treatment plants. Despite the 

proximity to potential threats to water 

quality, in the 20 years since the Oregon 

chub was listed, only a few of these 

concerns have materialized, and even 

then, these were localized and of short 

duration. The current distribution of the 

Oregon chub in many abundant 


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populations located across multiple 

subbasins reduces the risk that the 

above factors will affect a large portion 

of Oregon chub and its habitat. In 

summary, we conclude that none of the 

existing or potential water qualityrelated threats, either alone or in 

combination with others, constitutes a 

substantial threat to the Oregon chub 

now or in the foreseeable future. 

Additional discussion about 

temperature and dissolved oxygen 

levels is presented in the ‘‘Effects of 

Climate Change’’ section (also in Factor 

A). 

Aggradation 

Aggradation is an alluvial process 

where sediment deposition (deposition 

of all sizes of sediments, both coarse 

and fine) is more rapid than the capacity 

of a river to transport sediment 

downstream. We observed aggradation 

at the Geren Island North Channel in the 

North Santiam River. Natural movement 

of the river channel changed sediment 

deposition in the upstream end of this 

location, which had the potential to 

block water flow into the site. The City 

of Salem, which manages the site, 

excavated a portion of the channel to 

allow free-flowing water to enter Oregon 

chub habitat. To date, we have not 

observed a decline in the Geren Island 

population. With the exception of this 

site and habitats in Fall Creek, which 

we discussed previously, no other 

Oregon chub habitats are negatively 

impacted by aggradation. We consider 

the potential negative impacts to the 

overall status of Oregon chub from 

aggradation to be very low now and in 

the foreseeable future. 

Succession 

Succession resulting from the 

manipulation of river flows was 

identified as a potential threat to Oregon 

chub habitat in the downlisting rule (75 

FR 21179, April 23, 2010). Succession is 

a natural, long-term ecological process 

that ponds go through as they mature. 

As vegetation dies back seasonally, it 

deposits on the substrate of the pond, 

causing a reduction in water depth over 

time. Eventually, plant communities 

shift from aquatic to amphibious 

wetland plants, and the open-water 

ponds are replaced by seasonal wetland 

and marsh habitat. Historically, seasonal 

high flows and alluvial floodplain 

processes created off-channel habitat, 

and rejuvenated existing habitats by 

flushing out sediment and diversifying 

the aquatic plant community. These 

processes no longer function as they did 

historically because flows are regulated 

under the USACE’s Willamette Project. 

The Willamette Project dams were 

constructed in the 1940s through the 

1960s. Oregon chub populations have 

persisted under managed flow 

conditions for more than 60 years. In 

addition, under the Service’s Willamette 

Project biological opinion (Service 

2008b, pp. 40–51) and the NMFS 

Willamette Project biological opinion 

(NMFS 2008, pp. 2–43 to 2–52), 

minimum flow levels established for 

listed salmonids will continue to protect 

Oregon chub habitat. Other nonregulatory efforts are working to restore 

floodplain function and sediment 

transport, such as TNC’s Willamette 

Sustainable Rivers Project. In this 

project, TNC has developed an MOU 

with the USACE to release stored water 

in high-flow pulses to restore natural 

processes in managed portions of the 

Middle Fork, McKenzie, and Santiam 

Rivers. Given the MOU between the 

USACE and TNC regarding the 

Sustainable Rivers Project, and the 

minimum flows required under existing 

biological opinions from the Service and 

NMFS, we anticipate flow management 

trending towards natural flow regimes 

below Willamette Project dams will 

continue to create and rejuvenate offchannel habitats and benefit Oregon 

chub into the future. 

We are not aware of any particular 

sites that are vulnerable to succession in 

the near future; however, the sites that 

remain hydrologically isolated during 

high flows are cut off from these natural 

processes, and succession may continue 

resulting in a reduction of open water 

habitat. For instance, succession 

occurred at Herman Pond, an isolated 

Oregon chub site in the Coast Fork 

Willamette Basin, which led to a 

reduction in habitat area and a decline 

in population abundance. In 2005, the 

site was excavated to remove 

successional vegetation. This activity 

was successful in increasing open water 

habitat and led to an increase in Oregon 

chub abundance at this location. Given 

the wide distribution and number of 

Oregon chub habitats under different 

land ownership, we are uncertain 

whether manual modification of chub 

habitats to reverse the effects of 

succession will occur in the future 

following delisting. However, given that 

we are not aware of any particular sites 

vulnerable to succession in the 

foreseeable future, we determined that 

there is very little potential negative 

impact, if any, to the overall status of 

Oregon chub from succession. 

Irrigation Withdrawals 

A few Oregon chub sites may be 

influenced by irrigation water 

withdrawals. In recent years, at Elijah 

Bristow Berry Slough in the Middle 

Fork Willamette River subbasin, a drop 

in summer water level and a significant 

decline in Oregon chub abundance 

coincided with increased irrigation use 

by a farm located upstream. However, 

this was an isolated event that we have 

not observed at other sites. Many 

Oregon chub populations occur on 

publicly owned lands or on areas 

managed for conservation, where direct 

water withdrawals do not occur. In 

addition, water levels at habitats 

adjacent to mainstem river channels are 

highly dependent on river flow, and are 

less likely to be negatively impacted by 

irrigation withdrawals due to the 

amount of hyporheic (subsurface) flow 

into these habitats from the adjacent 

river. Based on the wide distribution of 

Oregon chub, we consider the potential 

negative impact to the overall status of 

Oregon chub from irrigation 

withdrawals to be very low. 

Effects Related to Climate Change 

Our analyses under the Act include 

consideration of observed or likely 

environmental changes resulting from 

ongoing and projected changes in 

climate. As defined by the 

Intergovernmental Panel on Climate 

Change (IPCC), the term ‘‘climate’’ refers 

to the mean and variability of different 

types of weather conditions over time, 

with 30 years being a typical period for 

such measurements, although shorter or 

longer periods also may be used (IPCC 

2013a, p. 1450). The term ‘‘climate 

change’’ thus refers to a change in the 

mean or the variability of relevant 

properties, which persists for an 

extended period, typically decades or 

longer, due to natural conditions (e.g., 

solar cycles) or human-caused changes 

in the composition of atmosphere or in 

land use (IPCC 2013a, p. 1,450). 

Scientific measurements spanning 

several decades demonstrate that 

changes in climate are occurring. In 

particular, warming of the climate 

system is unequivocal, and many of the 

observed changes in the last 60 years are 

unprecedented over decades to 

millennia (IPCC 2013b, p. 4). The 

current rate of climate change may be as 

fast as any extended warming period 

over the past 65 million years and is 

projected to accelerate in the next 30 to 

80 years (National Research Council 

2013, p. 5). Thus, rapid climate change 

is adding to other sources of extinction 

pressures, such as land use and invasive 

species, which will likely place 

extinction rates in this era among just a 

handful of the severe biodiversity crises 

observed in Earth’s geological record 

(American Association for the 

Advancement of Sciences (AAAS) 2014, 

p. 17). 


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Examples of various other observed 

and projected changes in climate and 

associated effects and risks, and the 

basis for them, are provided for global 

and regional scales in recent reports 

issued by the IPCC (2013c, 2014), and 

similar types of information for the 

United States and regions within it can 

be found in the National Climate 

Assessment (Melillo et al. 2014, entire). 

Results of scientific analyses 

presented by the IPCC show that most 

of the observed increase in global 

average temperature since the mid-20th 

century cannot be explained by natural 

variability in climate and is ‘‘extremely 

likely’’ (defined by the IPCC as 95 to 100 

percent likelihood) due to the observed 

increase in greenhouse gas (GHG) 

concentrations in the atmosphere as a 

result of human activities, particularly 

carbon dioxide emissions from fossil 

fuel use (IPCC 2013b, p. 17 and related 

citations). 

Scientists use a variety of climate 

models, which include consideration of 

natural processes and variability, as 

well as various scenarios of potential 

levels and timing of GHG emissions, to 

evaluate the causes of changes already 

observed and to project future changes 

in temperature and other climate 

conditions. Model results yield very 

similar projections of average global 

warming until about 2030, and 

thereafter the magnitude and rate of 

warming vary through the end of the 

century depending on the assumptions 

about population levels, emissions of 

GHGs, and other factors that influence 

climate change. Thus, absent extremely 

rapid stabilization of GHGs at a global 

level, there is strong scientific support 

for projections that warming will 

continue through the 21st century, and 

that the magnitude and rate of change 

will be influenced substantially by 

human actions regarding GHG 

emissions (IPCC 2013b, 2014; entire). 

Global climate projections are 

informative, and, in some cases, the 

only or the best scientific information 

available for us to use. However, 

projected changes in climate and related 

impacts can vary substantially across 

and within different regions of the 

world (e.g., IPCC 2013c, 2014; entire) 

and within the United States (Melillo et 

al. 2014, entire). Therefore, we use 

‘‘downscaled’’ projections when they 

are available and have been developed 

through appropriate scientific 

procedures, because such projections 

provide higher resolution information 

that is more relevant to spatial scales 

used for analyses of a given species (see 

Glick et al. 2011, pp. 58–61, for a 

discussion of downscaling). 

Various changes in climate may have 

direct or indirect effects on species. 

These may be positive, neutral, or 

negative, and they may change over 

time, depending on the species and 

other relevant considerations, such as 

interactions of climate with other 

variables such as habitat fragmentation 

(for examples, see Franco et al. 2006; 

Forister et al. 2010; Galbraith et al. 2010; 

Chen et al. 2011). In addition to 

considering individual species, 

scientists are evaluating potential 

climate change-related impacts to, and 

responses of, ecological systems, habitat 

conditions, and groups of species (e.g., 

Deutsch et al. 2008; Berg et al. 2010; 

Euskirchen et al. 2009; McKechnie and 

Wolf 2010; Sinervo et al. 2010; 

Beaumont et al. 2011; McKelvey et al. 

2011; Rogers and Schindler 2011). 

Climate change effects present 

substantial uncertainty regarding the 

future environmental conditions in the 

Willamette River Basin and may place 

an added stress on the Oregon chub and 

its habitats. The IPCC has concluded 

that recent warming is already strongly 

affecting aquatic biological systems, as 

evidenced by increased runoff and 

earlier spring peak discharge in many 

glacier- and snow-fed rivers (IPCC 2007, 

p. 8). Projections for climate change 

effects in North America include 

decreased snowpack, more winter 

flooding, and reduced summer flows 

(IPCC 2007, p. 14), which may increase 

periods of drought (Oregon Climate 

Change Research Institute (OCCRI) 

2010a, p. 112). 

Observed changes in temperature in 

the Pacific Northwest (PNW) already 

show an increase of 1.5 degrees Celsius 

over the past century due to human 

activities (OCCRI 2010b, p. 6). Global 

climate models project temperature 

increases for the PNW of approximately 

2 to 4 degrees Celsius (3 to 10 degrees 

Fahrenheit) by 2080 (OCCRI 2010b, p. 

7). Projections for climate change effects 

in the Willamette Valley in the next 

century also include warmer air 

temperatures that will lead to lower soil 

moisture and increased evaporation 

from streams and lakes (Climate 

Leadership Initiative (CLI) and National 

Center for Conservation Science and 

Policy (NCCSP) 2009, p. 9; OCCRI 

2010a, p. 71). The frequency of shortterm (3- and 6-month) droughts in the 

Willamette Valley will likely increase 

due to decreased summer rainfall, 

which may result in reduced summer 

baseflows and exacerbate water 

temperature increases. However, longterm droughts (12 and 24 months) are 

not projected to substantially change 

across most of the Willamette Basin 

(OCCRI 2010a, p. 112). 

The 29,700-km2 (11,467-mi2) 

Willamette River Basin is a large 

complex river basin, influenced by two 

mountain ranges: the Cascades and the 

Coast Range (Chang and Jung 2010, pp. 

187–190). The rain-dominated Coast 

Range occupies about 20 percent of the 

basin; the Cascade Range occupies more 

than 50 percent, and includes the raindominated Western Cascades and the 

snow-dominated High Cascades. The 

Willamette Valley region lies between 

these two ranges. Thus, the basin has 

complex terrain and geology, and a wide 

range of elevations that influence the 

timing and magnitude of runoff. Given 

this physical variability, the effects of 

climate change will not uniformly affect 

all areas or subbasins of the Willamette 

River (Chang and Jung 2010, pp. 194– 

204). 

The hydrology of the Willamette River 

Basin is largely influenced by winter 

rainfall and spring snowmelt, with 77 

percent of the flow occurring between 

November and April (Chang and Jung 

2010, p. 190). Overall, the Willamette 

Basin is considered water abundant in 

Oregon. In addition to rainfall, the basin 

is influenced by spring snowmelt and 

spring-fed tributaries at higher 

elevations (e.g., High Cascades region), 

and shallow groundwater aquifers in 

low-elevation areas in the valley that 

recharge during the rainy season (OCCRI 

2010a, p. 97–104). The Willamette River 

and its tributaries are highly altered 

with multiple large reservoirs and other 

human influences such as dams, levees, 

and floodplain development. Multiple, 

large USACE dams, constructed in the 

1950s and 1960s for flood reduction, 

altered seasonal discharge and 

temperatures, reduced peak flood flows, 

and augmented summer low flows 

(OCCRI 2010a, p. 77). Climate change 

effects that may affect Oregon chub 

include increased winter flooding, 

increased temperatures, reduced 

summer baseflows, and increased 

negative interactions with nonnative 

fishes. Each of these is discussed below. 

Increased Winter Floods—Effects of 

climate change predicted for the PNW 

may include increased winter flood 

events (OCCRI 2010a, pp. 87–88). These 

events, which are often associated with 

an increased proportion of annual 

precipitation falling as rain instead of 

snow and reduced snowpack, may 

better mimic natural riverine processes 

(such as channel migration, scour, etc.) 

to create and maintain riverine habitats 

on which Oregon chub depend. Oregon 

chub evolved in a dynamic, alluvial 

river with broad floodplains and 

braided reaches with many side 

channels, sloughs, and other similar 

slack-water habitats. Large floods 


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commonly rearranged these sidechannel habitats, creating new habitats 

in some locations, and filling in other 

areas. The construction and operation of 

the USACE’s Willamette Project, a 

system of 13 flood control dams, has 

reduced flooding and associated habitat 

forming processes in the Willamette 

River Basin, thereby simplifying mid- to 

low-elevation, aquatic habitats 

considerably. During previous flood 

events, the Willamette Project dams 

have been able to capture and reduce 

the magnitude of the flow to keep flood 

waters from impacting downstream 

communities; the magnitude of these 

flows were still high enough to alter the 

stream and floodplain habitat. Increased 

flows associated with climate change 

may contribute to the creation and 

maintenance of off-channel floodplain 

habitats upon which Oregon chub 

depend (e.g., side channels, oxbows, 

etc.), thereby increasing the amount of 

suitable habitat for the species. For 

these reasons, it is possible that 

increases in winter floods associated 

with climate change may benefit Oregon 

chub through the creation and 

maintenance of their habitats. 

Temperature and Dissolved Oxygen 

Effects—The Oregon chub is tolerant of 

a wide range of temperatures and thus 

less vulnerable to temperature effects of 

climate change than other listed fish 

species in the Willamette River Basin 

(e.g., bull trout, spring chinook salmon, 

and winter steelhead). Oregon chub do 

not require cool temperatures for 

spawning or other life-history needs and 

appear tolerant of low dissolved oxygen 

(DO) levels. DO levels and temperature 

are related because at higher 

temperatures, water has a reduced 

ability to store oxygen. While the upper 

lethal temperature limit of Oregon chub 

has not been determined, the best 

available data based on field 

observations suggest this limit is 

approximately 31 to 35 degrees Celsius 

(88 to 95 degrees Fahrenheit) for adult 

Oregon chub, and that tolerance may be 

associated with low DO levels (Scheerer 

and Apke 1997, p. 25; Bangs et al. 2009, 

p. 17). Temperature and DO tolerances 

for juvenile Oregon chub appear to be 

higher than that of adults (Scheerer and 

Apke 1997, p. 25; Bangs et al. 2009, p. 

17). The observed maximum summer 

temperature range of occupied Oregon 

chub habitat is from 23 to 39 degrees 

Celsius (73 to 102 degrees Fahrenheit) 

(Bangs 2014, pers. comm.). Despite a 

proportion of these habitats experience 

temperatures in excess of 35 degrees 

Celsius (95 degrees Fahrenheit) (which 

may result in the loss of some 

individuals within that population), an 

entire population has not been lost due 

to temperature increases and associated 

low DO levels. 

While global climate models project a 

temperature increase for the PNW of 

approximately 2 to 4 degrees Celsius 

(3.6 to 7.2 degrees Fahrenheit) by 2080 

(OCCRI 2010b, p. 7), climate models 

primarily predict air temperature 

changes, which have led many to 

believe that water temperatures will also 

correspondingly rise (Arismendi et al. 

2012, p. 1). However, water 

temperatures did not follow expected 

warming trends or experience the same 

magnitude of increased temperature as 

air temperature when analyzing stream 

temperature data from the Pacific 

continental United States (Arismendi et 

al. 2012, p. 4). In many cases, water 

temperatures were found to have more 

cooling trends than warming trends 

since 1987, and less variability, 

especially in highly human-influenced 

rivers (Arismendi et al. 2012, pp. 4–5). 

Such is the case in the Willamette River; 

the presence of the 13 USACE flood 

control dams in the Willamette Valley 

allows for some amelioration of extreme 

climate variation, such as temperature 

extremes and drought. These large dams 

may be able to adaptively operate in the 

future to partially offset some of the 

potential increases in water temperature 

and flow reductions below the dams, if 

determined appropriate. 

Releases of water below the USACE’s 

Willamette Project dams generally target 

water temperatures ranging from 12 to 

18 degrees Celsius (54 to 64 degrees 

Fahrenheit), depending on the season. 

These releases decrease downstream 

summer river temperatures by 6 to 10 

degrees Celsius (10.8 to 18 degrees 

Fahrenheit) from historic temperatures 

(Rounds 2010, p. 43) and augment 

summer low flows (OCCRI 2010a, p. 77). 

The USACE is working to better mimic 

historical temperature conditions 

through water releases at several dams, 

which primarily target temperature 

benefits to federally listed salmonids 

that remain protected under the Act. 

These salmonid species require much 

cooler waters than Oregon chub. For 

example, juvenile salmonids generally 

prefer temperatures from 11.7 to 14.7 

degrees Celsius (53.1 to 58.5 degrees 

Fahrenheit), and spawning temperatures 

for these species are typically below 

13.0 degrees Celsius (55.4 degrees 

Fahrenheit) (Richter and Kolmes 2005, 

pp. 27–28). The needs of these listed 

salmonids will continue to influence 

future management decisions. Thus, 

dam releases targeting these cooler 

temperature requirements will be 

protective of Oregon chub habitats 

downstream of these dams. 

Potential reductions in summer 

baseflows may increase water 

temperatures (OCCRI 2010a, p. 114). 

Increased frequency of short-term 

droughts (3 to 6 months) may reduce the 

USACE’s ability to meet all of the 

minimum instream flow volumes, 

especially during late summer and early 

fall. Many populations (40 out of 77 

populations, and 10 of the 23 

populations that meet recovery criteria) 

exist in riverine habitats influenced by 

releases from the USACE’s dams. 

While increased frequency of shortterm drought may reduce the USACE’s 

ability to meet required instream flows 

for listed salmonids, we do not 

anticipate these reductions will result in 

temperature increases that constitute a 

substantial threat to Oregon chub now 

or into the foreseeable future. These 

dams currently maintain cooler summer 

temperatures and higher summer 

baseflows below the dams than existed 

prior to dam construction, and thereby 

provide a buffer from increased 

temperatures. Further, the USACE is 

required to coordinate with the Service, 

ODFW, and NMFS when minimum 

instream flows cannot be met, which 

allows the Service to weigh in on the 

magnitude of reductions and mitigate 

negative effects to Oregon chub 

populations if necessary. For these 

reasons, we determine potential 

instream flow reductions, and any 

associated temperature increases and 

reduced DO levels due to increased 

short-term droughts do not constitute a 

substantial threat to Oregon chub in 

habitats below the dams. 

Other populations exist outside the 

influence of the dam releases. Eighteen 

populations exist in ‘‘up-slope’’ habitats 

that are not directly influenced rivers (6 

of these populations met all recovery 

criteria in 2013); 14 populations occur 

on or adjacent to undammed rivers (3 

met recovery criteria); 5 are adjacent to 

USACE reservoirs (4 met recovery 

criteria). The potential effects to each of 

these habitat categories are discussed 

below. 

The 18 ‘‘upslope’’ populations were 

introductions into isolated ponds, as 

discussed above. Predicted reductions 

in summer rainfall and increased 

evaporation may reduce the volume or 

depth of these ponds in late summer, 

increase water temperature, and 

correspondingly decrease DO levels in 

these habitats. However, these 

introduction sites were selected because 

the habitat is expected to remain stable 

during extreme climatic events such as 

droughts or floods. Each of these 

habitats was chosen for its ability to 

remain wetted during drought and 

provide a diversity of habitats 


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throughout a range of pool elevations. 

For example, some sites rely on ground 

water springs or modern water control 

structures to maintain pond elevations 

throughout summer. 

While it is possible that climate 

change may impact some aquatic 

habitats to the extent they no longer can 

support Oregon chub, the probability of 

that occurring is low given the wide 

tolerances of this species to water 

temperatures and corresponding DO 

levels. The diversity of isolated Oregon 

chub habitats spread across multiple 

watersheds provides further buffers 

against population level impacts from 

climate change. For these reasons, we 

determine that temperature effects due 

to climate change to these ‘‘up-slope’’ 

habitats do not constitute a substantial 

threat to Oregon chub now or into the 

foreseeable future. 

Fourteen Oregon chub populations 

occur on or adjacent to undammed 

rivers: 13 of these populations are 

naturally occurring and on or adjacent 

to rain-dominated, undammed 

tributaries to the Willamette River (e.g., 

Marys, Molalla, and Luckiamute Rivers, 

and Muddy Creek); and 1 population 

occurs in a spring-fed pond upstream of 

a USACE dam and thus is unlikely to 

experience substantial temperature 

increases or other negative impacts from 

climate change. For the 13 populations, 

potential reductions in summer 

baseflows and associated increases in 

water temperature are the most likely 

negative impacts to these populations 

from climate change effects (including 

short-term droughts). However, 

uncertainty in the extent and magnitude 

of summer baseflow reductions remains 

high despite modeling efforts (Chang 

and Jung 2010, pp. 198–202; see 

following discussion). Given this 

uncertainty regarding summer baseflow 

reductions, we cannot predict to what 

level summer baseflows may drop (and 

thereby increase water temperatures) 

and negatively impact these habitats. 

We anticipate few of these habitats 

will be negatively affected to such an 

extent Oregon chub cannot exist given 

the high tolerance of Oregon chub to 

temperature and associated reduced DO 

levels, the fact that ground water 

connections to these habitats may 

remain, and these habitats are 

distributed across several watersheds 

with differing influences (Chang and 

Jung 2010, p. 204). For these reasons, we 

determine that temperature effects due 

to climate change in these raindominated, undammed tributary 

habitats do not constitute a substantial 

threat to Oregon chub now or into the 

foreseeable future. 

The remaining five populations 

occupy habitats adjacent to USACE 

reservoirs in the Middle Fork 

Willamette River: Two populations at 

Lookout Point Reservoir, two at Dexter 

Reservoir, and one at Fall Creek 

Reservoir. Reductions in snow, 

increases in rain, increased frequency of 

short-term droughts, instream flow 

requirements, and related increased 

water demand for agricultural and 

municipal uses during droughts may 

put additional stresses on water supply 

in the Willamette Basin. These stresses 

may reduce the USACE’s ability to 

maintain reservoir levels year-round, 

especially during the late summer and 

early fall. These reservoir-associated 

populations are most likely to 

experience temperature increases, 

reduced DO levels, and reduction in 

habitat from loss of connection with the 

reservoirs, which may occur in the 

future during predicted short-term 

droughts. However, we have direct 

experience with this situation: in 2010, 

the USACE drew these reservoirs down 

through the summer of 2011 for damsafety repairs. 

The ODFW monitored these 

populations closely during and after 

reservoirs returned to normal levels 

(Bangs et al. 2012, p. 18). No 

populations were lost due to these 

reduced reservoir levels, despite 

reduced habitat and high summer 

temperatures. While some populations 

experienced a decline the following 

year, one population increased. Those 

populations that experienced a decline 

due to lowered reservoir levels 

recovered to previous abundance levels 

(Bangs et al. 2012, p. 10). 

In summary, the Oregon chub is 

tolerant of a wide range of temperatures 

and not dependent on cool waters to 

complete its life history. Oregon chub 

populations are dispersed across a wide 

range of diverse habitats, each 

influenced by site specific factors. The 

predicted increases in water 

temperature and associated reductions 

in DO levels from climate change effects 

are not anticipated to exceed the 

tolerances for Oregon chub throughout 

its range. Also, coordination between 

the Service and the USACE is required 

when minimum instream flow 

requirements will not be met. For these 

reasons, we determine that temperature 

increases associated with climate 

change effects are not a threat to Oregon 

chub across its range. 

Oregon chub are tolerant of a wide 

range of temperatures and associated 

decreases in DO, and are thus less 

vulnerable to temperature effects of 

climate change than other listed fish 

species in the Willamette Valley. 

Information specific to Oregon chub 

regarding its ability to make behavioral 

or physiological responses to 

temperature changes is not available. 

However, given their observed 

temperature tolerance (up to 31 to 35 

degrees Celsius, 88 to 95 degrees 

Fahrenheit) relative to potential climate 

increases in water temperature, the 

coordination of instream flows and 

reservoir management with the USACE, 

and the multiple populations across a 

range of ecological settings and 

tributaries in the Willamette Basin, we 

conclude that temperature effects from 

climate change do not constitute a 

substantial threat to Oregon chub now, 

or in the foreseeable future. 

Reduction in Summer Baseflows— 

Climate change effects with the most 

potential to negatively affect Oregon 

chub are reduced summer baseflows, 

which may reduce habitat availability 

within existing habitats and exacerbate 

increases in water temperature and 

declines in DO. Chang and Jung (2010, 

entire) examined future runoff 

projections in the Willamette River 

Basin under eight global climate models 

and two emissions scenarios. Some 

consistent trends exist between different 

models with regards to summer flow 

conditions: the 7-day low flow 

minimum decreased in most subbasins 

of the Willamette River Basin, and the 

Western Cascade basins (medium 

elevation) showed greater declines than 

those in the Willamette Valley (low 

elevation) and the High Cascades (high 

elevation) (Chang and Jung 2010, pp. 

198–202). However, the range of 

predicted changes was much more 

variable in the Willamette Valley and 

Western Cascades where the majority of 

Oregon chub populations exist. Further, 

the predicted changes for both summer 

runoff and the 7-day low flow minimum 

were very different depending on the 

emissions scenario used in the model, 

and the predicted changes varied by 

subbasin (Chang and Jung 2010, pp. 

201–202). 

Given the uncertainty in climate 

change predictions with differing 

models and future emission scenarios, 

we cannot specify the amount of 

reductions in summer baseflows for 

each subbasin and extrapolate how 

those reductions will affect habitat 

availability, temperatures, and DO 

(alone or in concert) in individual 

Oregon chub habitats. Such fine-scale 

models are not available. Despite 

modeled projections of changes in 

temperature, precipitation, and runoff at 

the global, regional, and basin scale, we 

cannot: (1) Predict with any certainty 

how those changes may influence 

Oregon chub populations and their 


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individual habitats in the Willamette 

Valley; and (2) accurately describe and 

assess the net effects when considering 

the potential negative consequences 

together with the potential positive 

effects to Oregon chub populations. 

Oregon chub habitats are often located 

in side-channel and off-channel areas 

that are highly influenced by sitespecific conditions, including, but not 

limited to factors such as above- and 

below-ground water connections 

between the habitat and the river system 

or aquifer, and total volume and depth 

of the habitat. For example, lower 

baseflows that seasonally disconnect 

above-ground flow to a side-channel 

habitat may or may not result in 

reduced habitat availability and 

increased temperatures, depending on 

whether cooler, below-ground water 

connection to the side channel is 

maintained. 

Oregon chub habitats exist throughout 

the Willamette River Basin in a variety 

of subbasins at a variety of elevations, 

with varying geology and topography, 

and with differing climatic influences. 

Modeling conducted by Chang and Jung 

(2010, pp. 198–204) suggests that the 

interactions between climate change 

and land surface hydrology are 

complex. Because of these varying 

factors, each subbasin will respond 

differently to the effects of climate 

change. Thus, not all Oregon chub 

populations in the Willamette River 

Basin will be similarly affected by 

climate change effects. Because of the 

variety of habitats within a single 

subbasin, it is unlikely that all habitats 

within a single subbasin will experience 

negative effects to the extent that habitat 

no longer supports Oregon chub. 

Further, potential reductions in summer 

baseflows in portions of the Willamette 

Basin will likely be moderated by the 

continuing operations of the USACE’s 

large storage dams that capture a portion 

of the flood flows from winter and 

spring precipitation events (including 

snowmelt) and gradually release these 

flows over the summer. Thus, for many 

existing Oregon chub populations, we 

do not anticipate substantial reductions 

in summer baseflows. If such reductions 

are necessary, our coordination with the 

USACE, as described earlier in this 

document, will allow the Service to 

minimize and mitigate impacts to 

Oregon chub. 

For Oregon chub habitats outside of 

the influence of USACE dam releases, 

insufficient information exists to 

determine the magnitude of future 

reductions in summer baseflows and 

associated changes in temperature and 

DO levels. Substantial reductions, if 

they occur, may result in the reduction 

of available habitat or in some instances 

the loss of individual populations. 

However, we do not anticipate such 

negative effects across the range of 

Oregon chub. Based on the existing 

information collected on Oregon chub 

since its listing, we anticipate Oregon 

chub will continue to exist because of 

its demonstrated resiliency in the past 

in the face of continual change: Oregon 

chub have survived despite significant 

landscape changes across the 

Willamette River Basin, including the 

effects of many dams and floodplain 

development. Studies to date have 

shown this species is highly adaptable, 

and able to quickly colonize new 

habitats. The effects of climate change 

will continue to progress into the future 

gradually. We anticipate that not all 

Oregon chub populations as they exist 

today will still exist 40 to 50 years from 

now, but that Oregon chub will exist in 

abundant and stable populations 

throughout the Willamette River Basin, 

colonizing new side channels and 

habitats as hydrology and floodplains 

adjust to a changed climate. Thus, we 

determine that reductions in summer 

baseflows and any associated increases 

in temperatures and declines in DO 

levels do not constitute a substantial 

threat to Oregon chub now, nor will 

they be in the foreseeable future. 

Competition and Predation by 

Nonnative Fish Species—Climate 

change effects may locally alter Oregon 

chub habitats to the advantage of 

nonnative species known to compete 

with and prey on Oregon chub via 

increasing water temperature and 

reducing connectivity to river systems 

during low flow conditions (e.g., 

summer baseflows). However, the best 

available data show no relationship 

between the presence of nonnative fish 

and Oregon chub population abundance 

trends (Bangs et al. 2013, p. 17). 

Thirteen of the 23 populations that met 

delisting criteria with either a stable or 

increasing abundance trend in 2013 

occur with nonnative fish; 1 of the 2 

populations that had a declining 

abundance trend occurs with nonnative 

fish (Bangs et al. 2013, p. 17). The 

primary driver affecting the abundance 

and dominance of nonnative fish in 

suitable Oregon chub habitats appears to 

be connectivity of these off-channel 

habitats to the larger river system. To 

date, these nonnative competitors and 

predators have not completely 

overtaken suitable Oregon chub habitats 

that remain seasonally connected to 

these river systems because annual 

flood flows disrupt and flush the 

nonnative species out of these suitable 

habitats, whereas Oregon chub have 

developed behaviors that allow them to 

remain as they evolved with these high 

flows. In summary, we do not anticipate 

climate change effects on the abundance 

and distribution of nonnative fish in the 

Willamette Basin will increase 

competition and predation. We 

determine that this competition and 

predation does not constitute a 

substantial threat to Oregon chub now, 

nor will they be in the foreseeable 

future. 

Summary for Climate Change 

Effects—The Willamette River Basin is a 

geologically complex system, as well as 

a highly altered and managed system 

with multiple large reservoirs and other 

human influences. Although effects of 

climate change are almost certain to 

impact aquatic habitats in the 

Willamette River Basin (CLI and NCCSP 

2009, p. 1), researchers have great 

uncertainty about the specific effects of 

climate change, including which models 

and emission scenarios are the best 

representation of the future. Thus, 

despite modeled projections of changes 

in temperature, precipitation, and 

runoff, we cannot: (1) Predict with any 

certainty how those changes may 

influence individual Oregon chub 

populations and their habitats in the 

Willamette Basin; and (2) accurately 

describe and assess the net effects when 

considering the potential negative 

consequences together with the 

potential positive effects to Oregon chub 

populations. 

The effects of climate change have 

potentially both positive and negative 

impacts to Oregon chub habitats; there 

is a wide diversity of habitats occupied 

by Oregon chub that are individually 

influenced by the site-specific factors 

and suitable habitats for Oregon chub 

are found throughout the Willamette 

Basin. Oregon chub as a species has 

proven itself highly adaptable and 

resilient to change. We cannot project 

with any certainty whether the effects of 

climate change will provide more 

benefits or threats to Oregon chub. 

However, the best available information 

suggests that Oregon chub and their 

habitats are not highly vulnerable to the 

potential effects of climate change 

across their range and we do not 

anticipate that climate change will have 

population level effects to Oregon chub. 

The Service developed a strategic 

plan to address the threat of climate 

change to vulnerable species and 

ecosystems. Goals of this plan include 

maintaining ecosystem integrity by 

protecting and restoring key ecological 

processes such as nutrient cycling, 

natural disturbance cycles, and 

predator–prey relationships (Service 

2010, p. 23). The Oregon chub recovery 


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program worked to establish conditions 

that allow populations of Oregon chub 

to be resilient to changing 

environmental conditions and to persist 

as viable populations into the future. 

Our recovery program for the species 

focused on maintaining large 

populations distributed within the 

species’ entire historical range in a 

variety of ecological settings (e.g., across 

a range of elevations). This approach is 

consistent with the general principles of 

conservation biology. In their review of 

minimum population viability 

literature, Traill et al. (2009, p. 3) found 

that maintenance of large populations 

across a range of ecological settings 

increases the likelihood of species 

persistence under the pressures of 

environmental variation, and facilitates 

the retention of important adaptive 

traits through the maintenance of 

genetic diversity. Maintaining multiple 

populations across a range of ecological 

settings, as described in the recovery 

plan, increases the likelihood that many 

abundant populations will persist under 

the stresses of a changing climate. 

Summary of Factor A 

Many of the factors discussed above 

were previously identified as threats to 

the continued existence of the Oregon 

chub. These factors include activities 

associated with the operation of the 

Willamette Project dams, sedimentation 

from timber harvest, floods or highwater events, water quality-related 

impacts, succession, and the effects of 

climate change. Modifications to the 

Willamette Project dam operations have 

provided flows that create and sustain 

off-channel habitat used by the Oregon 

chub, and we anticipate these flow 

targets will continue into the future due 

to requirements under biological 

opinions from the Service and NMFS, 

and the Sustainable Rivers Project 

collaboration between the USACE and 

TNC. Sedimentation from timber 

harvest is not currently indicated in the 

decline of any Oregon chub 

populations, and we expect that riparian 

buffers protected from timber harvest 

under State and Federal regulations will 

provide habitat protection in future 

timber harvest operations. Flooding and 

high-water events are largely 

unpredictable. However, Oregon chub 

evolved within a dynamic environment 

and the current distribution of Oregon 

chub in many abundant populations 

within subbasins and across multiple 

subbasins reduces the risk that these 

events will negatively affect a large 

proportion of Oregon chub and its 

habitat. Declines in water quality related 

to factors such as chemical 

contamination, nutrient enrichment, 

siltation, and hazardous material spills 

have the potential to affect individual 

populations, but few observations of 

negative effects due to water quality 

issues have materialized over the past 

20 years that we have been monitoring 

Oregon chub populations. Succession 

was a factor at one Oregon chub site and 

may occur in the future, particularly at 

sites that are isolated from the 

floodplain. However, succession is a 

slow process that can be addressed 

through ongoing monitoring and habitat 

management, and is not currently a 

cause for concern at any of the known 

Oregon chub sites. 

Other factors that may affect the 

Oregon chub and its habitat include 

actions required under the terms and 

conditions of the Willamette Project 

biological opinions, aggradation, and 

irrigation withdrawals. Actions required 

under the Willamette Project biological 

opinions began in 2008, but the effects 

to Oregon chub habitat from these 

actions are not well understood as the 

focus of most of these actions is 

recovery of listed salmonids. Research 

into the effects of these actions on offchannel habitats started in 2009 and 

will continue for the next few years. 

This research may lead to an improved 

understanding of the habitat 

characteristics that support abundant 

populations of Oregon chub in 

connected habitats and flow 

management recommendations specific 

to maintaining Oregon chub habitat. 

Aggradation from natural causes has 

been identified at one Oregon chub site, 

and aggradation from a complete 

drawdown of Fall Creek Reservoir 

resulted in large deposits of sediment in 

three previously unknown Oregon chub 

habitats. Other than these events, 

aggradation has not been observed at 

Oregon chub sites. Irrigation withdrawal 

was observed to negatively affect the 

volume of water available in one Oregon 

chub habitat in the Middle Fork River 

subbasin, but is not considered a 

widespread concern throughout the 

range of Oregon chub. 

In summary, the factors discussed 

under Factor A continue to occur across 

the subbasins occupied by Oregon chub, 

but only a few populations have 

exhibited declines as a result of any of 

the factors or combination of factors. 

The threat of habitat loss has been 

reduced by changes in flow 

management and by introducing the 

species into secure, isolated habitats 

that are not influenced by floodplain 

processes. We also better understand the 

diversity of connected habitats used by 

Oregon chub and, as a result, discovered 

many abundant populations in these 

habitats across multiple subbasins. 

Therefore, based on the best available 

information and because we expect that 

current management practices will 

continue into the foreseeable future, we 

conclude that the present or threatened 

destruction, modification, or 

curtailment of its habitat or range does 

not constitute a substantial threat to 

Oregon chub now and is not expected 

to in the foreseeable future. 

B. Overutilization for Commercial, 

Recreational, Scientific, or Educational 

Purposes 

Overutilization for commercial, 

recreational, scientific, or educational 

purposes was not a factor in listing, nor 

is it currently known to be a threat to 

the Oregon chub. 

C. Disease or Predation 

Predation by Nonnative Fishes and 

Amphibians 

In the final rule to downlist the 

Oregon chub (75 FR 21179, April 23, 

2010), we identified predation by, and 

competition with, nonnative fishes as 

primary threats to Oregon chub 

(competition with nonnative fishes is 

addressed below under Factor E). The 

Willamette River Basin contains 31 

native fish species and 29 nonnative 

species (Hulse et al. 2002, p. 44). The 

large-scale alteration of the Willamette 

River Basin’s hydrologic system (i.e., 

construction of dams and the resultant 

changes in flood frequency and 

intensity) created conditions that favor 

nonnative, predatory fishes, and 

reservoirs throughout the basin have 

become sources of continual nonnative 

fish invasions in the reaches 

downstream (Li et al. 1987, p. 198). 

Significant declines in Oregon chub 

abundance due to the presence of 

nonnative fishes were documented. For 

instance, after floods in 1996, nonnative 

fish were first collected from several 

sites containing Oregon chub in the 

Santiam River drainage; the two largest 

populations of Oregon chub (Geren 

Island North Pond and Santiam 

Easement) subsequently declined 

sharply in abundance (Scheerer 2002, p. 

1076). 

Nonnative fish, which prey upon 

Oregon chub, were also introduced into 

Oregon chub habitats. For example, 

illegal planting of largemouth bass at 

East Ferrin Pond in the Middle Fork 

Willamette River drainage coincided 

with the collapse of an Oregon chub 

population that had once totaled more 

than 7,000 fish. A regulatory mechanism 

is in place to prevent the translocation 

of nonnative fish. Within the State of 

Oregon, it is unlawful to transport, 

release, or attempt to release any live 


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fish into the waters of this State (OAR 

635–007–0600). Although similar illegal 

introductions may still occur in the 

future, they have historically been 

infrequent in habitats known to be 

occupied by Oregon chub. 

Predatory, nonnative centrarchids 

(bass and sunfish), western 

mosquitofish (Gambusia affinis), and 

bullhead catfish (Ameiurus spp.) are 

common in the off-channel habitats 

preferred by Oregon chub (Scheerer 

2002, p. 1,075). The Oregon chub is 

most abundant at sites where nonnative 

fishes are absent (Scheerer 2007, p. 96). 

However, ODFW biologists recently 

found many abundant Oregon chub 

populations that coexist with nonnative 

fish in hydrologically connected 

habitats (Bangs et al. 2011a, pp. 21–24). 

One of the primary objectives of the 

floodplain study funded under the 

Willamette Project biological opinion 

(Service 2008b, pp. 180–182; see 

previous discussion under Factor A) is 

to examine the relationship between the 

environmental conditions at 

hydrologically connected sites and the 

fish community, with a focus on Oregon 

chub and nonnative fish. The results to 

date indicate that spatial and seasonal 

differences in temperature within these 

off-channel habitats may provide areas 

that are suitable for Oregon chub but not 

suitable for nonnatives. In other words, 

Oregon chub may be able to coexist with 

nonnative fish because the habitat 

provides a diverse range of temperatures 

that partitions habitats among the 

species (Bangs et al. 2011a, pp. 9–10 

and 16–17). Currently, 41 percent of all 

known Oregon chub habitats and 50 

percent of the habitats supporting 

abundant populations (more than 500 

Oregon chub) contain nonnative fishes. 

Research conducted under the study 

will continue to: (1) Improve our 

understanding of the effects of 

nonnative fishes on Oregon chub in 

these connected habitats; and (2) 

document the habitat conditions that 

allow these species to coexist. Sampling 

results to date indicate that Oregon chub 

coexist with nonnatives more frequently 

than previously known. Additional 

discussion about predation by 

nonnative fish is presented in the 

‘‘Effects of Climate Change’’ section 

(discussed under Factor A). 

Bullfrogs (Rana catesbeiana) were 

identified as a threat to Oregon chub in 

the recovery plan (Service 1998, p. 13) 

because they may compete with Oregon 

chub for food resources (e.g., 

invertebrates). However, bullfrogs are 

prevalent in most of the habitats 

occupied by Oregon chub and their 

presence is not correlated with a decline 

in Oregon chub abundance (Bangs 2013, 

pers. comm.). 

The Oregon chub is not known to be 

threatened by disease. 

Summary of Factor C 

Although the habitat conditions that 

allow Oregon chub to coexist with 

nonnative fish are not yet well 

understood, we documented several 

abundant Oregon chub populations in 

multiple subbasins that coexist with 

nonnative, predatory fish. These Oregon 

chub populations exist in habitat that is 

connected to the active floodplain. 

Ongoing research conducted under the 

floodplain study funded by the USACE 

will continue to improve our 

understanding of the interactions 

between Oregon chub and nonnative 

fishes. 

While the presence of nonnative 

fishes in isolated sites may be associated 

with higher rates of predation on 

Oregon chub, the species has been 

introduced into 21 isolated habitats that 

are protected from the risk of invasion 

by nonnative fishes due to the habitat 

distance from the floodplain or other 

fish barriers. As discussed elsewhere in 

this document, these introductions act 

as refugial habitats, and the guidelines 

used to select sites ensure that these 

locations remain stable during extreme 

climactic events, such as droughts or 

floods. During major flooding in the 

Willamette River Basin in 1996, these 

sites remained isolated from 

neighboring water bodies. In addition, 

the introduction sites are less vulnerable 

to the threats of habitat loss compared 

to connected habitats, and the 

translocation guidelines ensured that 

the Oregon chub in these isolated 

populations are genetically diverse. 

Introduced populations at these sites 

have been highly successful, and the 

majority of Oregon chub individuals 

occur in populations at these sites. 

Therefore, based on the best available 

information, we conclude that disease 

and predation do not constitute 

substantial threats to Oregon chub now, 

nor are they expected to in the 

foreseeable future. 

D. The Inadequacy of Existing 

Regulatory Mechanisms 

In evaluating the inadequacy of 

existing regulatory mechanisms, we first 

identify threats under one or more of the 

other four factors that are affecting the 

species to the extent it meets the 

definition of an endangered or a 

threatened species under the Act. We 

then identify and evaluate the adequacy 

of existing regulatory mechanisms that 

may prevent or reduce those threats. 

The Oregon chub, however, is no longer 

facing substantial threats to its longterm survival due to the other four 

factors; thus the inadequacy of existing 

regulatory mechanisms is also no longer 

a threat to the species’ continued 

existence. Therefore, our discussion of 

this factor focuses on regulatory 

mechanisms not previously discussed 

that may provide benefits to Oregon 

chub. 

Wetlands and waterways in Oregon 

are protected by both Federal and State 

laws. The Environmental Protection 

Agency (EPA) administrates the Clean 

Water Act (CWA; 33 U.S.C. 1251 et 

seq.)), which regulates discharges of 

pollutants into waters of the United 

States and regulates water quality 

standards. The EPA sets standards for 

pollution control programs and water 

quality standards for all contaminants in 

surface waters. Many of the water 

quality criteria are set for human health 

standards or salmon and steelhead life 

stage needs, which exceed biological 

requirements for Oregon chub. For 

example, the upper temperature 

tolerance of Oregon chub is significantly 

higher than the maximum allowable 

temperatures set by EPA criteria for 

salmon and steelhead spawning and 

rearing. 

While we acknowledge that there are 

Oregon chub in reaches in the 

Willamette River that are on the section 

303(d) list of impaired and threatened 

waters under the CWA, Oregon chub 

populations have continued to expand 

throughout the Willamette River Basin 

in spite of these section 303(d) waters. 

Further, we do not foresee future water 

quality declines (i.e., temperature, 

dissolved oxygen, biological criteria) 

that are a threat to the continued 

existence of Oregon chub and require its 

continued listing under the Act. The 

Service has consulted with the EPA on 

existing Oregon water quality standards 

and the Service’s biological opinion 

concluded that the Oregon water quality 

standards are not likely to jeopardize 

the continued existence of Oregon chub 

(Service 2004, pp. 76–77). While the 

courts remanded the 2004 biological 

opinion back to the Service, and we 

continue to work with the EPA to 

complete this consultation, the remand 

was based on thermal requirements for 

bull trout, not Oregon chub. 

Under section 404 of the CWA, the 

USACE regulates the discharge of 

dredged material and fill material into 

waters of the United States, including 

navigable waters and wetlands that may 

contain Oregon chub. Oregon’s 

Removal-Fill Law (ORS 196.795–990) 

requires people who plan to remove or 

fill material in waters of the State to 

obtain a permit from the Oregon 


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Department of State Lands (DSL). 

Projects impacting waters often require 

both a State removal-fill permit, issued 

by the DSL, and a Federal permit issued 

by the USACE. A permit is required 

only if 50 cubic yards (1,350 cubic feet) 

or more of fill or removal will occur. 

The removal-fill law does not regulate 

the draining of wetlands. Projects 

permitted under these programs must 

avoid and minimize impacts to 

wetlands or waterways, or propose 

mitigation to replace the functions and 

values lost as a result of the project 

(Oregon Department of State Lands 

2013, p. 64). Some actions, however, 

such as construction and maintenance 

of irrigation-diversion structures and 

other activities associated with ongoing 

farming operations in existing cropped 

wetlands, are exempt from CWA 

requirements. Additionally, projects 

authorized under a nationwide USACE 

permit program receive minimal public 

and agency review unless the action 

may affect a listed species, in which 

case, consultation under section 7 of the 

Act is required. Individual permits are 

subject to a more rigorous review, as 

well as nationwide permit activities 

with more than minimal impacts. 

Under section 303(c) of the CWA, 

States are required to adopt water 

quality standards to restore and 

maintain the chemical, physical, and 

biological integrity of the nation’s 

waters. Oregon adopted revised water 

quality standards for toxic pollutants in 

2004. These standards are intended to 

protect native aquatic species, and are 

regulated by the Oregon Department of 

Environmental Quality. The State 

implements the standards through 

listing of waters that exceed criteria on 

the section 303(d) list of the CWA, 

calculating the Total Maximum Daily 

Loads (the maximum amount of 

pollutants that may enter a stream), and 

issuing or reissuing permits (i.e., 

National Pollutant Discharge 

Elimination System). In 2012, we 

completed consultation under section 7 

of the Act on the EPA’s proposed 

approval of the State of Oregon’s water 

quality criteria for toxic pollutants 

(Service 2012, entire). Although some 

Oregon chub sites may be affected by 

point-source discharges (i.e., wastewater 

treatment facilities and stormwater 

discharge from a manufacturing plant) 

and non-point-source discharges (i.e., 

runoff of agricultural and forestry 

pesticides and fertilizers) of toxic 

chemicals, we determined in our 

consultation with the EPA that the 

Oregon chub’s exposure to these 

chemicals at the criteria levels and the 

resulting effects would not jeopardize 

the species’ continued existence, 

adversely modify or destroy Oregon 

chub critical habitat, or reach levels 

preventing Oregon chub from attaining 

the abundance and distribution criteria 

for delisting identified in the recovery 

plan (Service 2012, pp. 351–352). 

The Oregon chub is designated as 

‘‘Sensitive-Critical’’ by the ODFW. 

Although this designation is a 

nonregulatory tool, it helps focus 

wildlife management and research 

activities, with the goal of preventing 

species from declining to the point of 

qualifying as ‘‘threatened’’ or 

‘‘endangered’’ under the Oregon 

Endangered Species Act (ORS 496.171, 

496.172, 496.176, 496.182, and 

496.192). ODFW’s ‘‘Sensitive-Critical’’ 

designation encourages, but does not 

require, the implementation of 

conservation actions for the species; 

however, other State agencies, such as 

the DSL and the Oregon Water 

Resources Department, refer to the 

Sensitive Species List when making 

regulatory decisions. 

The ODFW’s Sensitive Species List is 

reviewed and updated every 5 years. 

Each taxonomic group of animals is 

reviewed by the ODFW biologists and 

scientific experts from other agencies, 

universities, and private organizations. 

The scientists consider new and historic 

information on species distribution, 

population trends, and biological needs; 

changes in threats; gaps in knowledge 

and data; recent conservation actions; 

and State and Federal programs or 

regulations. The scientists may propose 

to remove, add, or re-classify species 

based on this information. The draft list 

is then peer-reviewed by State, Federal, 

university, and consulting biologists. 

The ODFW is currently updating the 

Sensitive Species List and plans to 

retain the ‘‘Sensitive-Critical’’ 

designation for Oregon chub for the 

duration of the post-delisting 

monitoring plan timeframe. 

Summary of Factor D 

Although existing regulatory 

mechanisms offer limited protection to 

Oregon chub, we have no indication 

that other factors, which these 

mechanisms are designed to address, are 

likely to occur at such a magnitude as 

to negatively impact large numbers of 

Oregon chub or a substantial area of 

habitat. Therefore, based on the best 

available information, we conclude that 

the inadequacy of existing regulatory 

mechanisms does not constitute a 

substantial threat to Oregon chub now, 

nor is it projected to in the future. 

E. Other Natural or Manmade Factors 

Affecting Its Continued Existence 

Interspecific Competition With 

Nonnative Fishes 

Along with the adverse impacts of 

direct predation described under Factor 

C (above), nonnative fishes compete 

with Oregon chub for food resources, 

such as aquatic invertebrates. 

Competition with nonnative fishes may 

contribute to the decline in populations 

or exclusion of Oregon chub from 

suitable habitats. Observed feeding 

strategies and diet of nonnative fishes, 

particularly juvenile centrarchids and 

adult western mosquitofish, overlap 

with those described for Oregon chub 

(Li et al. 1987, pp. 197–198). At South 

Stayton Pond, a hydrologically isolated 

site in the Santiam River Basin, we 

observed a population of 6,200 Oregon 

chub decline to 2,200 in one season 

after invasion by western mosquitofish, 

a nonnative fish that competes with 

adults and potentially predates on larval 

Oregon chub. The source of this 

invasion is unknown, but it is likely that 

the western mosquitofish were illegally 

introduced into the pond. The 

population remained above 1,000 for the 

past 4 years (Bangs 2014, pers. comm.), 

demonstrating the ability of nonnative 

fish to competitively suppress Oregon 

chub populations. Other populations of 

the Oregon chub are possibly 

suppressed by competition with 

nonnative fishes. However, the current 

abundance of Oregon chub and its 

distribution throughout floodplain 

habitats in the Santiam, McKenzie, and 

Middle Fork Willamette Rivers indicates 

that competition by nonnative fish is 

not affecting Oregon chub populations 

to the degree that overall status declines 

are observed. Additional discussion 

about competition by nonnative fish is 

presented in the ‘‘Effects of Climate 

Change’’ section (see Factor A). 

Isolated Populations 

Twenty-eight populations of the 

Oregon chub are currently isolated; 21 

of these sites are introduced sites where 

isolation was intentional in order to 

provide refugia from the threat of 

nonnative fishes. Other sites are isolated 

due to the reduced frequency and 

magnitude of flood events and the 

presence of migration barriers such as 

beaver dams. Managing species in 

isolation may have genetic 

consequences. Burkey (1989, p. 78) 

concluded that, when species are 

isolated by fragmented habitats, low 

rates of population growth are typical in 

local populations, and their probability 

of extinction is directly related to the 

degree of isolation and fragmentation. 


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Without sufficient immigration, growth 

of local populations may be low and 

probability of extinction high (Burkey 

1989, p. 78). The genetic analyses 

performed on Oregon chub (DeHaan et 

al. 2010, pp. 14–19; 2012, pp. 548–549) 

found high levels of genetic variation at 

most locations. Also, the genetic 

analyses found that our guidelines for 

establishing introduction sites are 

effective, and introductions stocked 

from multiple donor sources have 

higher variability than those from single 

donor sources. In addition, 50 of the 77 

Oregon chub populations are located in 

habitat that experiences some level of 

connectivity to the adjacent river 

channel; 34 of these populations were 

discovered since we downlisted the 

Oregon chub to threatened status in 

2010. Furthermore, the ODFW 

documented Oregon chub in new 

habitat created by floodplain processes 

in the McKenzie River subbasin, and 

documented voluntary movement of 

Oregon chub between populations in 

the Middle Fork Willamette River 

(Bangs et al. 2012, p. 19) and McKenzie 

River subbasins (Bangs et al. 2013, p. 

17). These findings demonstrate the 

ability of Oregon chub to colonize new 

habitats and exchange genetic material 

between established populations. 

Manual transport of Oregon chub 

between populations has not been 

proposed, and we think it unnecessary 

at this time for the maintenance of 

populations. Although a recent genetic 

analysis found that Oregon chub in 

isolated habitats have levels of genetic 

diversity equal to or greater than other 

cyprinids, additional Oregon chub may 

need to be introduced into these 

isolated populations in the future to 

maintain genetic diversity in the event 

a population shows a significant 

decline. 

In the final rule to reclassify Oregon 

chub to threatened (75 FR 21179, April 

23, 2010), we expressed concern about 

genetic isolation due to the lack of 

habitat connectivity between Oregon 

chub populations. As stated above, we 

discovered that many of the habitats 

occupied by the Oregon chub connect to 

the adjacent river channel more 

frequently and for longer duration than 

previously understood, which provides 

opportunities for genetic dispersal. 

Summary of Factor E 

Interspecific competition with 

nonnative fishes and isolation from 

genetic exchange may affect Oregon 

chub populations in the future. 

However, we observed population 

declines related to competition with 

nonnative fishes in only one Oregon 

chub population, South Stayton Pond, a 

small habitat area with limited 

resources. Although this decline was 

substantial (abundance of 6,200 chub 

declined to 2,200 chub in one season), 

the population since stabilized and 

persists with about 1,000 Oregon chub 

(Bangs et al. 2013, p. 6). We 

documented numerous additional 

abundant Oregon chub populations in 

habitats that are connected to the 

floodplain, which facilitates potential 

genetic exchange among populations. 

This has ameliorated the risk of a 

reduction in genetic diversity. The 

impacts associated with the effects of 

climate change will be somewhat 

ameliorated by the multiple storage 

dams in the Willamette River Basin, the 

wide range of temperature tolerances of 

Oregon chub, and the diversity of 

habitats occupied by the species. To the 

extent the effects of climate change 

manifest on the landscape, these 

impacts are, and will continue to be, 

reduced by the distribution of many 

abundant populations in diverse 

habitats across multiple subbasins. 

Therefore, based on the best available 

information, we conclude that other 

natural or manmade factors do not 

constitute a substantial threat to Oregon 

chub now, nor will they in the 

foreseeable future. 

Cumulative Impacts 

Some of the factors discussed in this 

five-factor analysis could work in 

concert with one another or 

synergistically to create cumulative 

impacts to Oregon chub populations. 

For example, effects from flow, dam 

operations, and temperature changes 

downstream of Willamette Project dams 

may coincide with an increase in 

nonnative fish species that prey upon 

and compete with Oregon chub. 

Although the types, magnitude, extent, 

or permutations of cumulative impacts 

are difficult to assess, the current status 

of Oregon chub indicates that no such 

synergies drive population declines now 

or have the potential to in the future, 

and the post-delisting monitoring plan 

is designed to detect such declines if 

they occur. As discussed below, the 

agencies and nongovernmental 

organizations that manage multiple 

populations agreed to cooperate on the 

implementation of the post-delisting 

monitoring plan, which will guide the 

monitoring and, should population 

declines occur, necessary research and 

conservation actions. The best scientific 

and commercial data available indicate 

that Oregon chub is genetically diverse, 

abundant, and well-distributed 

throughout its historical range and that 

the factors are not currently, or 

anticipated to, cumulatively cause 

declines in Oregon chub populations or 

its habitat. 

Overall Summary of Factors Affecting 

Oregon Chub 

The primary factors that threatened 

Oregon chub were loss of habitat, 

predation and competition by nonnative 

fishes, and the inadequacy of existing 

regulatory mechanisms. The threats that 

led to the species’ listing under the Act 

have been removed or ameliorated by 

the actions of multiple conservation 

partners over the last 20 years. The 

introduction of Oregon chub into 

several secure habitats has provided 

populations that are isolated from the 

threats of habitat loss and invasion by 

nonnative fishes. The discovery of many 

natural populations, including a number 

of populations that are connected to the 

active floodplain and coexist with 

nonnative fishes, has increased our 

understanding of population persistence 

in spite of the presence of predators in 

the species’ environment. The 

implementation of minimum instream 

flows and ongoing flushing flows from 

Willamette Project dams that sustain 

floodplain habitat downstream reduced 

the risk of habitat loss due to altered 

flows. The acquisition of floodplain 

habitat for long-term conservation and 

restoration provided assurance that 

management of floodplain habitat for 

the species will continue into the 

foreseeable future. 

Many factors still exist that may affect 

Oregon chub populations; however, 

most of these factors were isolated 

incidents, and the magnitude of their 

effects were not observed on a wide 

scale across the distribution of Oregon 

chub populations. The abundance and 

distribution of known Oregon chub 

populations has increased each year 

since the downlisting to threatened, and 

has exceeded the goals of our recovery 

criteria for delisting. When the species 

was listed in 1993, only nine 

populations of Oregon chub within a 

small, restricted range were known to 

occur. Oregon chub populations now 

exist in 77 diverse habitats across 

multiple subbasins. Listing the species 

under the Act resulted in the 

implementation of focused recovery 

actions that led to protected, abundant, 

and well-distributed Oregon chub 

populations across several Willamette 

River Basin tributaries. We expect 

conservation efforts will continue to 

support persistent recovered Oregon 

chub populations post-delisting and 

into the future, as described above. 

Based on this assessment of factors 

potentially impacting the species, we 

consider Oregon chub to face no 


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substantial threats, now or into the 

foreseeable future. 

Determination 

An assessment of the need for a 

species’ protection under the Act is 

based on whether a species is in danger 

of extinction or likely to become so 

because of any of five factors: (A) The 

present or threatened destruction, 

modification, or curtailment of its 

habitat or range; (B) overutilization for 

commercial, recreational, scientific, or 

educational purposes; (C) disease or 

predation; (D) the inadequacy of 

existing regulatory mechanisms; or (E) 

other natural or manmade factors 

affecting its continued existence. As 

required by section 4(a)(1) of the Act, 

we conducted a review of the status of 

this species and assessed the five factors 

to evaluate whether the Oregon chub is 

endangered or threatened throughout all 

of its range. We examined the best 

scientific and commercial information 

available regarding the past, present, 

and future threats faced by Oregon chub 

and its habitat. We reviewed the 

information available in our files and 

other available published and 

unpublished information, and we 

consulted with recognized experts and 

other Federal, State, and Tribal 

agencies. 

In considering what factors might 

constitute threats, we must look beyond 

the mere exposure of the species to the 

factor to determine whether the 

exposure causes actual impacts to the 

species. If there is exposure to a factor, 

but no response, or only a positive 

response, that factor is not a threat. If 

there is exposure and the species 

responds negatively, the factor may be 

a threat and we then attempt to 

determine how significant the threat is. 

If the threat is significant, it may drive, 

or contribute to, the risk of extinction of 

the species such that the species 

warrants listing as endangered or 

threatened as those terms are defined by 

the Act. This determination does not 

necessarily require empirical proof of a 

threat. The combination of exposure and 

some corroborating evidence of how the 

species is likely impacted could suffice. 

The mere identification of factors that 

could impact a species negatively is not 

sufficient to compel a finding that 

listing is appropriate; we require 

evidence that these factors are operative 

threats that act on the species to the 

point that the species meets the 

definition of an endangered species or 

threatened species under the Act. 

We find that Oregon chub populations 

are well-distributed among several 

subbasins and that many large, stable, or 

increasing populations exist that show 

no evidence of decline over the last 7 or 

more years. During our analysis, we did 

not identify any factors that are likely to 

reach a magnitude that threatens the 

continued existence of the species; 

significant impacts at the time of listing 

that could have resulted in the 

extirpation of all or parts of populations 

have been eliminated or reduced since 

listing, and we do not expect any of 

these conditions to substantially change 

post-delisting and into the foreseeable 

future. We conclude that the previously 

recognized impacts to Oregon chub from 

the present or threatened destruction, 

modification, or curtailment of its 

habitat or range (specifically, operation 

of the USACE’s Willamette Project 

dams, sedimentation from timber 

harvest and floods, water quality issues, 

succession, and effects of climate 

change (Factor A); predation by 

nonnative species (Factor C); and 

interspecific competition with 

nonnative species, and isolation from 

genetic exchange (Factor E)), do not rise 

to a level of significance such that the 

species is in danger of extinction 

throughout all of its range now or in the 

foreseeable future. 

Significant Portion of the Range 

Analysis 

Having determined that the Oregon 

chub throughout all its range, is not 

endangered or threatened throughout all 

of its range, we next consider whether 

there are any significant portions of its 

range in which the Oregon chub is in 

danger of extinction or likely to become 

so. Under the Act and our implementing 

regulations, a species may warrant 

listing if it is in danger of extinction or 

likely to become so throughout all or a 

significant portion of its range. The Act 

defines ‘‘endangered species’’ as any 

species which is ‘‘in danger of 

extinction throughout all or a significant 

portion of its range,’’ and ‘‘threatened 

species’’ as any species which is ‘‘likely 

to become an endangered species within 

the foreseeable future throughout all or 

a significant portion of its range.’’ We 

published a final policy interpreting the 

phrase ‘‘Significant Portion of its 

Range’’ (SPR) (79 FR 37578; July 1, 

2014). The final policy states that (1) if 

a species is found to be endangered or 

threatened throughout a significant 

portion of its range, the entire species is 

listed as endangered or threatened, 

respectively, and the Act’s protections 

apply to all individuals of the species 

wherever found; (2) a portion of the 

range of a species is ‘‘significant’’ if the 

species is not currently endangered or 

threatened throughout all of its range, 

but the portion’s contribution to the 

viability of the species is so important 

that, without the members in that 

portion, the species would be in danger 

of extinction, or likely to become so in 

the foreseeable future, throughout all of 

its range; (3) the range of a species is 

considered to be the general 

geographical area within which that 

species can be found at the time the 

Service or NMFS makes any particular 

status determination; and (4) if a 

vertebrate species is endangered or 

threatened throughout an SPR, and the 

population in that significant portion is 

a valid Distinct Population Segment 

(DPS), we will list the DPS rather than 

the entire taxonomic species or 

subspecies. 

The procedure for analyzing whether 

any portion is an SPR is similar, 

regardless of the type of status 

determination we are making. The first 

step in our analysis of the status of a 

species is to determine its status 

throughout all of its range. If we 

determine that the species is in danger 

of extinction, or likely to become so in 

the foreseeable future, throughout all of 

its range, we list the species as an 

endangered species (or threatened 

species) and no SPR analysis will be 

required. If the species is neither in 

danger of extinction nor likely to 

become so throughout all of its range, 

we next determine whether the species 

is in danger of extinction or likely to 

become so throughout a significant 

portion of its range. If it is, we list the 

species as an endangered species or 

threatened species, respectively; if it is 

not, we conclude that listing the species 

is not warranted. 

When we conduct an SPR analysis, 

we first identify any portions of the 

species’ range that warrant further 

consideration. The range of a species 

can theoretically be divided into 

portions in an infinite number of ways. 

However, there is no purpose in 

analyzing portions of the range that 

have no reasonable potential to be 

significant or in analyzing portions of 

the range in which there is no 

reasonable potential for the species to be 

endangered or threatened. To identify 

only those portions that warrant further 

consideration, we determine whether 

substantial information indicates that: 

(1) The portions may be ‘‘significant’’ 

and (2) the species may be in danger of 

extinction there or likely to become so 

within the foreseeable future. 

Depending on the biology of the species, 

its range, and the threats it faces, it 

might be more efficient for us to address 

the significance question first or the 

status question first. Thus, if we 

determine that a portion of the range is 

not ‘‘significant,’’ we do not need to 

determine whether the species is 


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Federal Register / Vol. 80, No. 33 / Thursday, February 19, 2015 / Rules and Regulations 9149 

endangered or threatened there; if we 

determine that the species is not 

endangered or threatened in a portion of 

its range, we do not need to determine 

if that portion is ‘‘significant.’’ In 

practice, a key part of the determination 

that a species is in danger of extinction 

in a significant portion of its range is 

whether the threats are geographically 

concentrated in some way. If the threats 

to the species are affecting it uniformly 

throughout its range, no portion is likely 

to have a greater risk of extinction, and 

thus would not warrant further 

consideration. Moreover, if any 

concentration of threats apply only to 

portions of the range that clearly do not 

meet the biologically based definition of 

‘‘significant’’ (i.e., the loss of that 

portion clearly would not be expected to 

increase the vulnerability to extinction 

of the entire species), those portions 

would not warrant further 

consideration. 

We considered whether any portions 

of Oregon chub range might be both 

significant and in danger of extinction, 

or likely to become so in the foreseeable 

future. One way to identify portions 

would be to identify natural divisions 

within the range that might be of 

biological or conservation importance. 

The geographic range of Oregon chub 

can readily be divided into four 

subbasins (Santiam, Mainstem 

Willamette, Middle Fork Willamette, 

and Coast Fork Willamette Rivers). 

Although some of the factors we 

evaluated in the Summary of Factors 

Affecting the Species section, above, 

occur in specific habitat types (i.e., 

hydrologically connected sites versus 

isolated sites) within these subbasins, 

the factors affecting Oregon chub 

generally occur at similarly low levels 

throughout its range. Because the low 

level of potential threats to the species 

is essentially uniform throughout its 

range and the populations of the species 

within the subbasins are not in danger 

of extinction or likely to become so 

within the foreseeable future due to lack 

of significant threats, no portion of the 

range warrants further consideration to 

determine if it is significant. Based on 

our review of the best available 

information concerning the distribution 

of the species and the potential threats, 

we have determined that the Oregon 

chub does not warrant further 

consideration to determine if there is a 

significant portion of the range that is 

endangered or threatened. 

Summary 

We carefully assessed the best 

scientific and commercial data available 

and determined that the Oregon chub is 

no longer in danger of extinction 

throughout all or a significant portion of 

its range, nor is it likely to become so 

within the foreseeable future. We 

conclude Oregon chub no longer 

requires the protection of the Act, and, 

therefore, we are removing it from the 

Federal List of Endangered and 

Threatened Wildlife. 

Future Conservation Measures 

Section 4(g)(1) of the Act requires us, 

in cooperation with the States, to 

implement a monitoring program for not 

less than 5 years for all species that have 

been recovered and delisted. The 

purpose of this post-delisting 

monitoring (PDM) is to verify that a 

species remains secure from risk of 

extinction after the protections of the 

Act are removed, by developing a 

program that detects the failure of any 

delisted species to sustain itself. If, at 

any time during the monitoring period, 

data indicate that protective status 

under the Act should be reinstated, we 

can initiate listing procedures, 

including, if appropriate, emergency 

listing under section 4(b)(7) of the Act. 

Post-Delisting Monitoring Plan Overview 

The Service developed a final PDM 

plan in cooperation with the ODFW. In 

addition, the USACE, USFS, Oregon 

Parks and Recreation Department, 

McKenzie River Trust, and Willamette 

Valley National Wildlife Refuge 

Complex agreed to cooperate with us in 

the implementation of the PDM plan. 

The PDM plan is designed to verify that 

the Oregon chub remains secure from 

the risk of extinction after removal from 

the Federal List of Endangered and 

Threatened Wildlife by detecting 

changes in its status and habitat 

throughout its known range. The final 

PDM plan consists of: (1) A summary of 

the species’ status at the time of 

delisting; (2) an outline of the roles of 

PDM cooperators; (3) a description of 

monitoring methods; (4) an outline of 

the frequency and duration of 

monitoring; (5) an outline of data 

compilation and reporting procedures; 

and (6) a definition of thresholds or 

triggers for potential monitoring 

outcomes and conclusions of the PDM 

effort. 

The final PDM plan will monitor 

Oregon chub populations following the 

same sampling protocol used by the 

ODFW prior to delisting. Monitoring 

will consist of three components: 

Oregon chub distribution and 

abundance, potential adverse changes to 

Oregon chub habitat due to 

environmental or anthropogenic factors, 

and the distribution of nonnative fishes 

in Oregon chub habitats. The PDM 

period consists of three 3-year cycles (9 

years total), which will begin in 2015. 

Both Willamette Project biological 

opinions continue until 2023, and flow 

and temperature augmentation will be 

implemented during this period 

(Service 2008b, pp. 68–72; NMFS 2008, 

pp. 2–43 to 2–52, 2–125 to 2–128). 

Monitoring through this time period 

will allow us to address any possible 

negative effects to Oregon chub 

associated with changes to flow and 

temperatures. As funding allows, we 

will collect data on roughly three 

generations of Oregon chub in each of 

the three subbasins, which will allow 

time to observe fluctuations in 

population abundance that may be 

attributed to residual stressors. Sites 

included in the floodplain study will be 

sampled annually over the next 9 years, 

enabling the Service and PDM partners 

to recommend flow and temperature 

regimes that are beneficial to native 

fishes in to the future. Sites outside the 

floodplain study will be sampled only 

once during each 3-year cycle, thus 

reducing annual sampling costs from 

current levels. 

The final PDM plan identifies 

measurable management thresholds and 

responses for detecting and reacting to 

significant changes in Oregon chub 

protected habitat, distribution, and 

persistence. If monitoring detects 

declines equaling or exceeding these 

thresholds, the Service in combination 

with other PDM participants will 

investigate causes of these declines, 

including considerations of habitat 

changes, substantial human persecution, 

stochastic events, or any other 

significant evidence. Such investigation 

will determine if Oregon chub warrants 

expanded monitoring, additional 

research, additional habitat protection, 

or relisting as an endangered or a 

threatened species under the Act. If 

relisting Oregon chub is warranted, 

emergency procedures to relist the 

species may be followed, if necessary, in 

accordance with section 4(b)(7) of the 

Act. 

We will post the final PDM plan and 

any future revisions on our national 

Web site (http://endangered.fws.gov) 

and on the Oregon Fish and Wildlife 

Office’s Web site (http://www.fws.gov/

oregonfwo/). 

Effects of the Rule 

This final rule revises 50 CFR 17.11(h) 

by removing Oregon chub from the 

Federal List of Endangered and 

Threatened Wildlife. As such, as of the 

effective date of this rule (see DATES), 

the prohibitions and conservation 

measures provided by the Act, 

particularly through sections 7 and 9, no 

longer apply to this species (including 


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those contained in the existing 

conservation agreement, all safe harbor 

agreements, and all biological opinions 

for this species). There are no habitat 

conservation plans related to Oregon 

chub. Removal of Oregon chub from the 

Federal List of Endangered and 

Threatened Wildlife relieves Federal 

agencies from the need to consult with 

us under section 7 of the Act to ensure 

that any action they authorize, fund, or 

carry out is not likely to jeopardize the 

continued existence of this species. This 

final rule also revises 50 CFR 17.95(e) 

by removing the designated critical 

habitat for Oregon chub throughout its 

range. 

Required Determinations 

Paperwork Reduction Act of 1995 (44 

U.S.C. 3501 et seq.) 

This rule does not contain any new 

collections of information that require 

approval by the Office of Management 

and Budget (OMB) under the Paperwork 

Reduction Act. This rule will not 

impose recordkeeping or reporting 

requirements on State or local 

governments, individuals, businesses, or 

organizations. An agency may not 

conduct or sponsor, and a person is not 

required to respond to, a collection of 

information unless it displays a 

currently valid OMB control number. 

National Environmental Policy Act 

We have determined that 

environmental assessments and 

environmental impact statements, as 

defined under the authority of the 

National Environmental Policy Act of 

1969 (42 U.S.C. 4321 et seq.), need not 

be prepared in connection with 

regulations pursuant to section 4(a) of 

the Act. We published a notice outlining 

our reasons for this determination in the 

Federal Register on October 25, 1983 

(48 FR 49244). 

References Cited 

A complete list of all references cited 

in this final rule is available at http:// 

www.regulations.gov at Docket No. 

FWS–R1–ES–2014–0002, or upon 

request from the Oregon Fish and 

Wildlife Office (see ADDRESSES). 

Authors 

The primary authors of this rule are 

staff members of the Service’s Oregon 

Fish and Wildlife Office with assistance 

from ODFW staff (see ADDRESSES and 

FOR FURTHER INFORMATION CONTACT). 

List of Subjects in 50 CFR Part 17 

Endangered and threatened species, 

Exports, Imports, Reporting and 

recordkeeping requirements, 

Transportation. 

Regulation Promulgation 

Accordingly, we amend part 17, 

subchapter B of chapter I, title 50 of the 

Code of Federal Regulations, as follows: 

PART 17—[AMENDED] 

■ 1. The authority citation for part 17 

continues to read as follows: 

Authority: 16 U.S.C. 1361–1407; 1531– 

1544; and 4201–4245, unless otherwise 

noted. 

§ 17.11 [Amended] 

■ 2. Amend § 17.11(h) by removing the 

entry for ‘‘Chub, Oregon’’ under FISHES 

in the List of Endangered and 

Threatened Wildlife. 

§ 17.95 [Amended] 

■ 3. Amend § 17.95(e) by removing the 

entry for ‘‘Oregon Chub (Oregonichthys 

crameri)’’. 

Dated: December 16, 2014. 

Stephen Guertin, 

Acting Director, U.S. Fish and Wildlife 

Service. 

[FR Doc. 2015–02951 Filed 2–18–15; 8:45 am] 

BILLING CODE 4310–55–P 


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