U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2018–1106

Prepared in cooperation with the Mid-Columbia Fisheries Enhancement Group

Juvenile Salmonid Monitoring Following Removal of Condit 

Dam in the White Salmon River Watershed, Washington, 2017
Cover: Photograph of rotary screw trap at river kilometer 2.3, White 

Salmon River, Washington. Photograph by U.S. Geological Survey, 

March 28, 2016.
Juvenile Salmonid Monitoring Following Removal of 

Condit Dam in the White Salmon River Watershed, 

Washington, 2017 

By Ian G. Jezorek and Jill M. Hardiman

Prepared in cooperation with the Mid-Columbia Fisheries Enhancement Group

Open-File Report 2018–1106

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

RYAN K. ZINKE, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2018 

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Suggested citation:

Jezorek, I.G., and Hardiman, J.M., 2018, Juvenile salmonid monitoring following removal of Condit Dam in the 

White Salmon River watershed, Washington, 2017: U.S. Geological Survey Open-File Report 2018-1106, 31 p. 

https://doi.org/10.3133/ofr20181106. 

ISSN 2331-1258 (online)
iii

Contents

Abstract ......................................................................................................................................................................1

Introduction................................................................................................................................................................. 2

Description of Study Site ............................................................................................................................................5

Study Methods............................................................................................................................................................7

Smolt Trapping........................................................................................................................................................7

Electrofishing...........................................................................................................................................................7

Results........................................................................................................................................................................9

Smolt Trapping Results ...........................................................................................................................................9

Electrofishing Results............................................................................................................................................10

Additional Passive Integrated Transponder-Tagging Data ....................................................................................11

Discussion ................................................................................................................................................................11

Acknowledgments.....................................................................................................................................................14

References Cited......................................................................................................................................................15

Appendix 1. Length Frequencies .............................................................................................................................29

Figures

Figure 1. Schematic of the White Salmon River watershed accessible to anadromous salmonids

showing locations of rotary screw trapping and electrofishing surveys during 2017 and the former

location of Condit Dam, which was breached in 2011 ............................................................................................. 19

Figure 2. Graphs showing daily catch of steelhead (Oncorhynchus mykiss) fry, parr, and smolts in 

the screw trap at river kilometer 2.3, White Salmon River, Washington, April 11–June 12, 2017............................ 20

Figure 3. Graphs showing daily catch of coho salmon (Oncorhynchus kisutch) fry, parr, and smolt

in the screw trap at river kilometer 2.3, White Salmon River, Washington, April 11–June 12, 2017 ........................ 21

Figure 4. Graph showing daily catch of Chinook salmon (Oncorhynchus tshwaytscha) fry and parr

in the screw trap at river kilometer 2.3, White Salmon River, Washington, April 11–June 12, 2017. ....................... 22

Figure 5. Graphs showing fish-per-day of steelhead (Oncorhynchus mykiss), coho salmon (O. kisutch),

and Chinook salmon (O. tshwaytscha) at a screw trap fished prior to (2007–09) and after (2016–17)

removal of Condit Dam, White Salmon River, Washington...................................................................................... 23

Figure 6. Graph showing abundance estimates of steelhead/rainbow trout (Oncorhynchus mykiss) 

and coho salmon (O. kisutch) at a site on the lower kilometer of Rattlesnake Creek, Washington,

2001–05 and 2016–17............................................................................................................................................. 24

Figure 7. Graph showing abundance estimates of steelhead/rainbow trout (Oncorhynchus mykiss) 

and coho salmon (O. kisutch) at a sample site in river kilometer 2 of Buck Creek, Washington,

2009–10 and 2016–17............................................................................................................................................. 25
iv

Tables

Table 1. Latitude and longitude of fish sampling sites, White Salmon River watershed, Washington, 2017 .......... 26

Table 2. Number of steelhead (Oncorhynchus mykiss), Chinook salmon (O. tshawytscha), and coho

salmon (O. kisutch), by life stage, captured, tagged with passive integrated transponder tags, and sampled

for genetic material at the screw trap at river kilometer 2.3, White Salmon River, Washington,

April 11, 2017–June 12, 2017.................................................................................................................................. 26

Table 3. Number of steelhead (Oncorhynchus mykiss) and coho salmon (O. kisutch) smolt, and age-0 

Chinook salmon captured, marked, and recaptured at the smolt trap at river kilometer 2.3, White Salmon

River, Washington, March 24–May 28, 2016, and April 11–June 12, 2017 ............................................................. 27

Table 4. Number of juvenile salmonids captured and tagged with passive integrated transponder tags,

and tissue sampled for genetic analysis during electrofishing surveys, White Salmon River watershed, 

Washington, 2017.................................................................................................................................................... 27

Table 5. Abundance estimates and standard error, abundance and density of steelhead/rainbow trout 

(Oncorhynchus mykiss) and coho salmon (O. kisutch) at abundance electrofishing sites in Buck and

Rattlesnake Creeks, Washington, August 2017....................................................................................................... 28
v 

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

International System of Units to U.S. customary units

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

kilometer (km) 0.5400 mile, nautical (nmi) 

meter (m) 1.094 yard (yd) 

Area

square meter (m2) 0.0002471 acre 

square kilometer (km2) 247.1 Acre

square meter (m2) 10.76 square foot (ft2) 

square kilometer (km2) 0.3861 square mile (mi2)

Volume

liter (L) 0.2642 gallon (gal)

cubic meter (m3) 6.290 barrel (petroleum, 1 barrel = 42 gal)

cubic meter (m3) 264.2 gallon (gal) 

cubic meter (m3) 35.31 cubic foot (ft3)

cubic meter (m3) 1.308 cubic yard (yd3) 

cubic meter (m3) 0.0008107 acre-foot (acre-ft) 

Flow rate

cubic meter per second (m3/s) 70.07 acre-foot per day (acre-ft/d) 

cubic meter per second (m3/s) 35.31 cubic foot per second (ft3/s)

cubic meter per second (m3/s) 22.83 million gallons per day (Mgal/d) 

Mass

milligram (mg) 0.00003527 ounce, avoirdupois (oz)

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound avoirdupois (lb)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as °F = (1.8 × °C) + 32.

Datum

Vertical coordinate information is referenced to the World Geodetic System of 1984 (WGS84). 

Altitude, as used in this report, refers to distance above the vertical datum.

Supplemental Information

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L).
vi 

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1 

Juvenile Salmonid Monitoring Following Removal of 

Condit Dam in the White Salmon River Watershed, 

Washington, 2017

By Ian G. Jezorek, and Jill M. Hardiman

Abstract

Condit Dam, at river kilometer 5.3 on the White Salmon River, Washington, was 

breached in 2011, and removed completely in 2012, providing anadromous salmonids with the 

opportunity to recolonize habitat blocked for nearly 100 years. Prior to dam removal, a multiagency workgroup concluded that the preferred salmonid restoration alternative was to allow 

natural recolonization. Monitoring would assess fish recolonization efficacy, followed by 

management evaluation 5 years after dam removal. Limited monitoring of salmon and steelhead 

recolonization has occurred since 2011. The U.S. Geological Survey began juvenile salmonid 

monitoring in 2016 and did a second year during 2017, with sampling efforts like those of 2016. 

River conditions differed between the 2 years, both during (that is, high flows in 2017) and prior 

to (that is, 2015 summer drought conditions and December 2015 White Salmon River flood 

event) sampling. We operated a rotary screw trap at river kilometer 2.3 (3 kilometers 

downstream of the former dam site) from early April through early June to assess species 

diversity, and production of smolt and other migrant life stages. We also used backpack 

electrofishing during summer to assess juvenile salmonid distribution and abundance. Both 

sampling methods provided the opportunity to collect genetic samples (analysis of samples was 

not covered under funding received from the Mid-Columbia Fisheries Enhancement Group for 

the 2017 monitoring efforts) and to tag fish with passive integrated transponder (PIT) tags, which 

will provide life-history data through future recaptures and detections. 

The screw trap captured steelhead (anadromous rainbow trout, Oncorhynchus mykiss),

fry, parr, and smolts; coho salmon (O. kisutch) fry, parr, and smolts; and Chinook salmon (O. 

tshwaytscha) fry, parr, and one smolt. Prolonged high water and some missed trapping periods 

during 2017 prevented us from generating smolt estimates. Despite difficult trapping conditions, 

the number of coho salmon fry and parr, and steelhead fry and parr captured in 2017 exceeded 

those captured during 2016. The number of age-0 Chinook salmon captured in the screw trap 

during 2017 was much higher (n = 222) than in 2016 (n = 4).
2 

Electrofishing in tributaries provided information on distribution and abundance of 

juvenile coho salmon and O. mykiss. Juvenile coho salmon were again found in Mill and Buck 

Creeks and, for the first time, in Rattlesnake Creek (all three creeks are upstream of the former 

dam site). In both Rattlesnake and Buck Creeks, age-0 O. mykiss abundance decreased between 

2016 and 2017; however, age-1 and older O. mykiss and age-0 coho salmon abundance increased 

between years at both sites. Data on O. mykiss abundance at sites in Buck and Rattlesnake 

Creeks is providing the opportunity to begin to understand trends and variability post-dam 

removal and to compare to pre-dam removal periods. 

Mean age-0 O. mykiss abundance (fish per meter [fish/m]) at the Rattlesnake Creek site 

has been slightly lower during post-dam removal (mean = 3.0, n = 2, range = 2.4–3.6) than predam removal (mean = 3.4, n = 5, range = 1.5–5.1). However, the presence of juvenile coho 

salmon in Rattlesnake Creek during 2017 (0.5 fish/m) brought total age-0 salmonid abundance in 

2017 to 2.9 fish/m. Mean age-1 or older O. mykiss abundance (fish/m) at the Rattlesnake Creek 

site has been lower post-dam removal (mean = 0.2, n = 2, range = 0.1–0.3) than pre-dam removal 

(mean = 0.5, n = 2, range = 0.3–0.8). Mean age-0 O. mykiss abundance (fish/m) at the Buck 

Creek site has been higher post-dam removal (mean = 2.1, n = 2, range = 1.2–3.0) than pre-dam 

removal (mean = 1.8, n = 2, range = 1.6–1.9). The addition of age-0 coho salmon to Buck Creek 

brings mean age-0 salmonid abundance post-dam removal to 2.7 fish/m (range = 1.9–3.4). Mean 

age-1 or older O. mykiss abundance (fish/m) in Buck Creek has been slightly higher post-dam 

removal (mean = 0.8, n = 2, range = 0.6–1.1) than pre-dam removal (mean = 0.6, n = 2, both 

years 0.6). 

Introduction

Condit Dam blocked anadromous fish passage for nearly 100 years on Washington’s 

White Salmon River, a tributary of the Columbia River. The dam, at river kilometer (rkm) 5.3, 

was breached in 2011 and completely removed by September 14, 2012. Currently (2017), the 

river is in a state of flux, with riparian revegetation occurring in the former reservoir reach, and 

the continuation of sediment and gravel redistributing between the former dam site and the 

confluence with the Columbia River (Wilcox and others, 2014; Hatten and others, 2016). 

Anadromous fish have been using both reopened habitat upstream of the dam site and improved 

habitat downstream. 

The White Salmon River historically supported steelhead (anadromous rainbow trout, 

Oncorhynchus mykiss), spring and fall Chinook salmon (O. tshawytscha), coho salmon (O. 

kisutch), and chum salmon (O. keta) runs (Lane and Lane Associates, 1981; Cowan, 1999; 

National Marine Fisheries Service, 2013a, 2013b), and provided local Native Americans with 

important fishing areas (National Marine Fisheries Service, 2013b). Additionally, Pacific 

lamprey (Entosphenus tridentatus) were present prior to construction of Condit Dam (Jolley and 

others, 2018). Removal of Condit Dam has reopened much potential anadromous fish habitat. 

Reconnected potential habitat is estimated at 27 km for coho salmon, 15 km for spring Chinook 

salmon, 7 km for fall Chinook salmon, and 50 km for steelhead (Northwest Power and 

Conservation Council, 2004; National Marine Fisheries Service, 2013a, 2013b). Since dam 

removal, a strategy of natural recolonization has been in effect. This followed recommendations 

of the multi-agency White Salmon Technical Work Group (WSTWG; Jezorek and Hardiman, 

2017) and the Endangered Species Act [ESA] Recovery Plan for the White Salmon River 

(National Marine Fisheries Service, 2013b). 
3 

The White Salmon watershed is considered part of the Lower Columbia River (LCR) 

Evolutionary Significant Unit (ESU) salmon recovery domain and the Middle Columbia River 

(MCR) Distinct Population Segment (DPS) steelhead recovery domain. It is a part of 

Washington State’s Water Resource Inventory Area (WRIA) 29b (Cowan, 1999; National 

Marine Fisheries Service, 2009; National Marine Fisheries Service, 2013b). Removal of Condit 

Dam opened passage for LCR Chinook salmon (both fall and spring runs), LCR coho salmon, 

and MCR steelhead, which are all listed as threatened under the ESA (National Marine Fisheries 

Service, 2009; National Marine Fisheries Service, 2013a, 2013b). The ESA Recovery Plan for 

the White Salmon River Watershed (National Marine Fisheries Service, 2013b) suggests that 

White Salmon River coho salmon may be functionally extinct and that spring Chinook salmon 

likely are extirpated. The Middle Columbia River Steelhead ESA Recovery Plan (National 

Marine Fisheries Service, 2009) considers White Salmon steelhead “functionally extirpated”. 

However, recent monitoring efforts in the White Salmon watershed have documented that 

steelhead, coho salmon, and Chinook salmon are spawning and producing offspring upstream of 

the former Condit Dam site (Jeremy Wilson, Washington Department of Fish and Wildlife, 

written commun., 2016; Joe Zendt, Yakama Nation Fisheries, written commun., 2016; Jezorek 

and Hardiman, 2017). Reconnected upstream habitat and improved habitat downstream of the 

Condit Dam site of the White Salmon River comprise a significant habitat gain in the Gorge 

Strata of the LCR ESU and the East Cascades MPG of the MCR DPS (Hardiman and Allen, 

2015; Hatten and others, 2016). 

Key questions about recolonizing fish are—what is their source and abundance, what is 

their productivity, what are limiting factors by life stage, and are they producing enough viable 

offspring to support population persistence? Numerous Federal and State plans recommend that

these questions on Viable Salmonid Population (VSP) parameters be addressed (McElhany and 

others, 2000; National Marine Fisheries Service, 2009; Lower Columbia Fish Recovery Board, 

2010a, 2010b; National Marine Fisheries Service, 2013a, 2013b). Population viability criteria 

can include juvenile out-migrant productivity and trends, population diversity, and spatial 

structure. Data outlined in the ESA Recovery Plan for the White Salmon River watershed will 

provide managers with information specific to White Salmon River and Gorge strata populations 

and will contribute to the growing body of science focused on dam removal.

Dam removals have increased nationwide (O’Connor and others, 2015; Bellmore and 

others, 2017). Studies are needed to address their efficacy as a conservation strategy for 

anadromous salmonids (Quiñones and others, 2015). Dam removal often involves uncertainty 

and management concerns regarding the physical and biological consequences (Tullos and 

others, 2016). Many dam removals are not scientifically monitored for biological effects or are 

monitored for only a short duration (O’Connor and others, 2015; Brewitt, 2016; Bellmore and 

others, 2017; Foley and others, 2017). More and longer-duration dam removal response studies 

are required to develop predictive models to inform managers and the public about effects of 

dam removal (Gregory and others, 2002; Hart and others, 2002; Pess, 2009; Brewitt, 2016; Foley 

and others, 2017). 

The removal of Condit Dam provides an opportunity to evaluate the efficacy of dam 

removal for fish restoration and conservation, and contributes to the science of dam removals. 

Condit Dam is a relatively unique case to date because it was a high dam (38 m) with a large 

amount of sediment that was quickly released (1.8 million m3

; Wilcox and others, 2014; 

O’Connor and others, 2015; Hatten and others, 2016), and because natural salmonid 

recolonization is being allowed with no direct hatchery supplementation. Many dam removals 
4 

occur with little to no pre-removal data (Bellmore and others, 2016; Foley and others, 2017), but 

in the White Salmon River, there were some pre-dam removal fish studies. During 2006–09, the 

U.S. Geological Survey (USGS) and U.S. Fish and Wildlife Service (FWS) assessed species 

composition and relative abundance of juvenile salmonids downstream of Condit Dam at rkm 

1.5, using a rotary screw trap (Allen and Connolly, 2011). Additionally, tributary habitat and 

salmonid abundance data were collected in Buck and Rattlesnake Creeks (Allen and others, 

2003a, 2003b; Allen, Connolly, Jezorek, Munz, and Charrier, 2006; Allen, Connolly, Munz, and 

Charrier, 2006; Allen and others, 2012). These existing pre-dam removal data offer a baseline for 

understanding changes in fish distribution, abundance, and genetics. 

Limited fish monitoring has occurred in the White Salmon River since removal of Condit 

Dam. Chinook salmon spawning surveys were conducted by FWS during 2012 and have been 

conducted by the Washington Department of Fish and Wildlife (WDFW) since 2013 following 

VSP guidelines (McElhany and others, 2000; Crawford and Rumsey, 2011) to estimate adult 

abundance, distribution, and origin (Allen and others, 2016). Steelhead spawning surveys, 

conducted in tributaries by Yakama Nation since 2012, are providing spatial distribution data and 

an index of abundance (Allen and others, 2016; Joe Zendt, Yakama Nation Fisheries, written 

commun., 2017). Because of funding limitations and challenges of surveying adult steelhead 

(that is, prolonged spawning period, high flows, turbidity, iteroparity), an approach that includes 

juvenile abundance and life-history data is particularly useful towards assessing population status 

(Lower Columbia Fish Recovery Board, 2010a). Like steelhead sampling, adult coho salmon 

sampling in the White Salmon River has significant challenges and limitations. No assessment of 

adult coho salmon use of the White Salmon River has been conducted since dam removal. As 

with steelhead, a broad monitoring approach including juvenile abundance and life-history data 

will provide the most robust assessment of efficacy of natural recolonization. The WSTWG, a 

multi-agency (Federal, State, Tribal, and others) group, continues to meet to coordinate ongoing 

efforts in the White Salmon River watershed (Allen and others, 2016; Jezorek and Hardiman, 

2017). 

During 2017, USGS completed a second year of juvenile salmonid monitoring in the 

White Salmon River watershed following dam removal. Project funding was received from the 

Mid-Columbia Fisheries Enhancement Group (MCFEG), which provided fiscal sponsorship for 

grants from the Washington State Salmon Recovery Funding Board and Clark-Skamania 

Flyfishers. Our goals were to assess smolt production from upstream of rkm 2.3, juvenile 

salmonid distribution in the watershed, and juvenile salmonid abundance at sites in Buck and 

Rattlesnake Creeks. These data will help evaluate dam removal as a restoration and conservation 

strategy, assess the efficacy of a natural recolonization strategy for anadromous salmonids, and 

inform managers of the status of ESA-listed salmonid stocks. Additionally, we collected genetic 

samples and passive integrated transponder- (PIT-) tagged fish. Though funding for genetic 

analysis was not part of our project, we are working with partners in the WSTWG to analyze 

these samples. Future recaptures and detections of PIT-tagged fish will contribute to knowledge 

of life-history diversity of naturally produced salmonids in the White Salmon River watershed. 

In this document, we refer to O. mykiss captured at the screw trap as steelhead since they are 

actively migrating, but because we do not know the migratory status of O. mykiss captured in 

electrofishing surveys, we simply refer to them as O. mykiss or steelhead/rainbow trout. 
5 

Description of Study Site

The White Salmon River watershed encompasses about 1,000 km2 of Klickitat, Yakima, 

and Skamania Counties in south-central Washington (Haring, 2003). The White Salmon River is 

a tributary of the Columbia River at rkm 270 (fig. 1). The topography of the area includes

mountainous terrain, deeply incised canyons, rolling hills, and low-gradient valley floors 

(Northwest Power and Conservation Council, 2004; National Marine Fisheries Service, 2013b). 

The White Salmon River is in the transitional eco-tone between the moderate coastal maritime 

climate zone and the continental inland climate zone. The climate is temperate, and around 80 

percent of the annual precipitation occurs between October and March. Precipitation primarily is 

rain in the lower watershed and rain or snow in the higher altitudes, and ranges from 100 cm in 

the east to 240 cm in the north and west (Northwest Power and Conservation Council, 2004). 

The White Salmon River has good water quantity and quality (Haring, 2003; Northwest 

Power and Conservation Council, 2004; Allen and Connolly, 2005). Discharge varies from a 

daily mean of about 19 m3

/s during fall to about 44 m3/s in spring (U.S. Geological Survey, 

streamgage 14123500 [White Salmon River near Underwood, Washington]; Haring, 2003), and is 

maintained by snowmelt-fed springs and seeps throughout the summer (Haring, 2003; Northwest 

Power and Conservation Council, 2004; Allen and Connolly, 2005). Water temperatures in the 

river remain cold throughout the year, with maximum and minimum temperatures and dissolved 

oxygen levels within optimal levels for salmonids. Much of the White Salmon River is in a 

narrow, naturally incised bedrock and boulder canyon (Northwest Power and Conservation 

Council, 2004; Plummer and Zuckerman, 2012). 

Numerous waterfalls are present on the White Salmon River. The largest waterfall is Big 

Brother Falls (about 7.3 m high) at rkm 26, which likely is the upstream extent of anadromous 

distribution (some anecdotal reports mention steelhead upstream of these falls, but are 

unconfirmed). BZ Falls (about 4.5 m high) is at rkm 20, and likely is a barrier to salmon, 

although steelhead most likely can ascend it (Reiser and others, 2006). Husum Falls (about 3 m 

high), at rkm 12.2, is a likely barrier to some salmon, although spring Chinook salmon and their 

redds have been found upstream of it (Allen and others, 2016; Jeremy Wilson, Washington 

Department of Fish and Wildlife, written commun., 2016). 

The characteristics of the lower 8.0 km of the White Salmon River have rapidly changed 

since the 2011 breaching of Condit Dam and subsequent sediment release. An estimated 1.8 

million m3

 of sediments were impounded in the reservoir (Wilcox and others, 2014). This influx 

of sediment to the lower river has increased potential salmonid spawning and rearing habitat 

(Hardiman and Allen, 2015; Hatten and others, 2016). Natural watershed processes delivering 

large woody debris, cobbles, and gravel to the lower reaches have been restored (Wilcox and 

others, 2014; Hardiman and Allen, 2015; Allen and others, 2016; Hatten and others, 2016). The 

lower river likely will be in flux for the next few years as the river channel continues to stabilize 

and the riparian corridor re-establishes.

Four tributaries to the White Salmon River in our study area had anadromous fish access. 

Mill, Buck, Spring, and Rattlesnake Creeks all enter the White Salmon River between the former 

dam site and Husum Falls. During 2017, we sampled fish in Mill, Buck, and Rattlesnake creeks, 

but did not have permission to access Spring Creek. 

Mill Creek flows to the White Salmon River from the west at rkm 6.4 (fig. 1). The Mill 

Creek basin is 11 km2, with a mix of private and Washington State owned lands. Altitude at the 

confluence with the White Salmon River is about 90 m, with the upper headwaters at about 800 

m. The basin is steep and heavily forested. Plummer and Zuckerman (2012) reported many 
6 

springs contributing flow to Mill Creek, which maintain low water temperatures. The estimates 

of potential anadromous fish habitat in Mill Creek range from 3.2 to 7 km (Northwest Power and 

Conservation Council, 2004; Plummer and Zuckerman, 2012). 

Buck Creek flows into the White Salmon River from the northwest at rkm 7.5 (fig. 1).

The Buck Creek basin is steep, mountainous terrain. The area of the basin is 36 km2

, about 90 

percent of which is owned by Washington Department of Natural Resources. Altitude in the 

basin ranges from 92 m at its mouth to 1,219 m at its headwaters. The basin is characterized by 

forested (second growth and early successional mixed conifer and deciduous), steep canyons 

with an incised basalt bedrock channel. Buck Creek also supplies domestic water to the city of 

White Salmon, Washington. 

Allen and others (2012) defined four reaches in the part of Buck Creek accessible to 

anadromous fish, beginning at the confluence with the White Salmon River and extending 

upstream 6.4 km, where there is a 6-m waterfall (the likely end of anadromy and immediately 

downstream of the City of White Salmon municipal water facility). Allen and others (2012) 

reported that most of the habitat in Buck Creek was large cobble riffles. Boulders and cobbles 

were the dominant substrate; spawning gravel was limited. They reported smaller and less 

frequent instream large woody debris (LWD) than found in unmanaged basins of similar size and 

character. Minimum discharge in Buck Creek was reported by Allen and others (2012) as 0.02 

m3

/s at the mouth, and 0.009 m3/s downstream of the water diversion at rkm 3.1. Water 

temperatures in Buck Creek are favorable to salmonids. Temperatures at the lower end of Buck 

Creek only occasionally exceeded 16 °C, and never exceeded 18 °C during 2009, 2010, and 2016 

(Allen and others, 2012; Jezorek and Hardiman, 2017). 

Rattlesnake Creek flows to the White Salmon River from the east at rkm 13.8 (fig. 1). 

The Rattlesnake Creek basin covers 143 km2, and nearly all is privately owned in a mix of forest 

and some agricultural lands. Altitude is about 114 m at the mouth to 927 m at ridge tops at the 

basin’s eastern edge. There are two notable sets of waterfalls in Rattlesnake Creek. The lower set 

of falls, at rkm 2.4, has three individual drops, with the middle one being the largest (about 3.6 m 

total height, but with a step and 1.5-m-deep pocket at 2.1 m). The lower falls likely are a barrier 

to resident fish, but may be passable to some anadromous fish. An adult steelhead was sighted 

upstream of these falls during 2016 (Joe Zendt, Yakama Nation Fisheries, written. commun., 

2016). The upper falls, at rkm 17, has two separate drops of about 22–25 m each and is a fish 

barrier. Allen, Connolly, Jezorek, Munz, and Charrier (2006) reported that habitat conditions in 

all reaches of Rattlesnake Creek were poor. Pool frequency and quality were low. Counts of 

LWD were low and riparian condition was degraded (Allen, Connolly, Jezorek, Munz, and 

Charrier, 2006; Plummer and Zuckerman, 2012). Discharge in Rattlesnake Creek is extremely 

low during summer (Northwest Power and Conservation Council, 2004; Allen and Connolly, 

2005; Allen, Connolly, Jezorek, Munz, and Charrier, 2006; Allen, Connolly, Munz, and Charrier, 

2006; Plummer and Zuckerman, 2012). Discharge near the mouth of Rattlesnake Creek can be 

less than 0.0018 m3

/s and surface flow in riffles is barely discernible in some reaches. Water 

temperature in Rattlesnake Creek can approach lethal limits for salmonids. Allen, Connolly, 

Jezorek, Munz, and Charrier (2006) reported a maximum temperature of 23.6 °C at rkm 0.9, and 

temperatures that exceeded 20 °C throughout the drainage were common. During 2016, water 

temperature at the mouth of Rattlesnake Creek exceeded 16 °C every day during July and 

August, with a maximum of 22.8 °C (Jezorek and Hardiman, 2017). 
7 

Study Methods

Smolt Trapping

We operated a 1.5-m rotary screw trap (E.G. Solutions, Corvallis, Oregon) at rkm 2.3 of 

the White Salmon River (fig. 1; table 1). This was the first site upstream of the confluence with 

the Columbia River where channel characteristics and access enabled trapping. We fished the 

trap intermittently (because of high-flow conditions) from early April to mid-June 2017. 

Methods following those outlined in Volkhardt and others (2007). 

Each day, debris was removed from the live box, and captured fish were netted into 

buckets for transport to shore. Captured fish were held in buckets or coolers with ambient aerated 

stream water. Fish were anesthetized with 50 mg/L tricaine methanesulfonate (MS-222), 

identified to species, measured for fork length (FL) to the nearest millimeter, weighed to the 

nearest 0.1 g, and classified by life stage (fry, parr, smolt). Fin tissue was taken from some 

Chinook salmon, steelhead, coho salmon, and lamprey, and archived for genetic analysis. 

Salmonids were checked for PIT tags or dye marks to determine if they were recaptures. Fish 60-

mm or greater FL were scanned for PIT tags and PIT-tagged if not previously tagged. Fish from 

60- to 69-mm FL were tagged with 9-mm tags, and fish greater than 69-mm FL were tagged with 

12-mm tags; both tag sizes were 134.2 kHz, and all were full duplex. Tags were injected into the 

peritoneal cavity following methods outlined by Columbia Basin Fish and Wildlife Authority 

(2014). Salmonids less than 60-mm FL were batch marked with Bismark Brown Y biological 

stain (16 mg/L; Sigma Chemical Company, St. Louis Missouri). 

We marked fish to calculate migrant estimates following standard methods (Thedinga 

and others, 1994; Volkhardt and others, 2007). Each day, newly marked fish (PIT-tagged, fin 

clipped, or batch dye-marked) were transported by vehicle to an access point at the PacifiCorp 

Powerhouse at rkm 3.0, where they were released. Recaptured fish were released downstream of 

the trap.

All screw-trap data were electronically entered on a field computer provided by WDFW, 

and were configured to accept data in their Juvenile Migrant Exchange (JMX) database. All 

screw-trap data from 2017 were entered in the JMX database. All mark and recapture data from 

PIT-tagged fish were submitted to the PTAGIS database administered by Pacific States Marine 

Fisheries Commission.

Electrofishing

We used backpack electrofishing to assess juvenile salmonid abundance in the most 

downstream reach of Rattlesnake Creek (start at rkm 0.2; site length, 223 m) and a section of 

Buck Creek (start at rkm 2.0; site length, 230 m; fig. 1). Additionally, we backpack electrofished 

for fish distribution and species assemblage in a new section of Mill Creek at about rkm 1.3. The 

Mill Creek 2018 sample section was about 250 m long and was about 0.7 km upstream of our 

uppermost sampling in Mill Creek in 2016, which was to rkm 0.6. 
8 

We estimated abundance of fish using the mark-recapture methods outlined in Temple 

and Pearsons (2007). We block netted the stream at the upstream and downstream ends to 

prevent emigration or immigration. We used two block nets at each end of the sample section, 

one of which (of coarser mesh) was placed upstream of the other to collect material brought 

down by the current and to ensure that the lower net was not knocked down by debris. The net 

lead lines were secured snugly to the streambed with boulders and large cobble, and the upper 

net line was tied off so that it was at least 0.5 m above the water surface.

Once the nets were secured, we electrofished the section and marked fish with either PIT 

tags or fin clips. Three crew members dipnetted fish and placed them in buckets or coolers with 

ambient, aerated stream water. We anesthetized captured fish with the lightest possible dose of 

MS-222, measured FL to the nearest millimeter, weighed to the nearest 0.1 g, and marked. 

Salmonids with a 70-mm or greater FL were PIT-tagged with a 12-mm tag, and salmonids with a

55–69-mm FL were PIT-tagged with a 9-mm tag (both tags were 134.2 kHz). Smaller fish were 

given a caudal fin clip. Fish were released as close as possible to their point of capture. Block 

nets were left overnight, and the following day we repeated the electrofishing effort. During fish 

workup for the recapture pass, all fish were checked for a PIT tag or fin clip mark. 

For mark-recapture analysis, we followed methods outlined in Temple and Pearsons 

(2007). We used length-frequency histograms to assign ages to age-0 and age-1 or older fish 

(appendix figs. 1.1–1.5). We estimated the abundance of fish and associated variance, by species 

and age class (age-0 and age-1 and older) in study reaches using Chapman’s modification of the 

Peterson estimate (Chapman, 1951), as follows: 

( )( )

( ) 1 ˆ 1 1

1

M C

N

R

  + + =   − +  

, and (1)

( ) ( )( )

( )( )

2

2

ˆ

1

N CR ˆ

V N

C R

− = + + , (2)

where

 Nˆ = population estimate, 

 M = number of fish marked during the mark sample effort, 

 C = total number of fish captured in the recapture sample effort, 

 R = number of marked fish captured in the recapture sample effort, and 

 V = variance. 

To quantify habitat area, we measured width and depth at 10 transects, equally spaced 

through the mark-recapture section. With these data, we calculated the area of the section and 

could estimate fish per meter and fish per square meter. 
9 

Results

Smolt Trapping Results

We captured steelhead, coho salmon, and Chinook salmon in the screw trap during 

operational periods from April 101 to June 12, 2017 (figs. 2–4; table 2). The trap was fished for 

45 days during this period. Because of high-flow conditions (greater than 2,400 ft3/s, with a peak 

in late March at about 3,800 ft3/s; USGS streamgage 14123500 [White Salmon River near 

Underwood, Washington]; https://waterdata.usgs.gov/nwis/uv?site_no=14123500), sampling 

days were limited and the trap frequently was fished outside the thalweg to prevent damage. The 

trap was not operated during April 15–17, April 25–28, and May 5–13. Chinook salmon were the 

most abundant species captured, with 203 fry, 19 parr, and 1 smolt. Steelhead were the next most 

abundant species captured, with 14 fry, 61 parr, and 40 smolts. Coho salmon captured were, 59 

fry, 21 parr, and 13 smolts (table 2). 

We could not calculate migrant abundance estimates at the screw trap in 2017 because of

the low catch rate (table 3), and missed sampling days due to high water. Of the 40 steelhead 

smolts captured, 39 were PIT-tagged, and 1 was recaptured. No coho salmon smolts were 

recaptured of the 12 PIT-tagged. Most of the fish captured were age-0 Chinook salmon (n = 222; 

table 2). We dye-marked 192 age-0 Chinook salmon and recaptured 4 of them (table 3).

All salmonid species were captured throughout the sample period, but timing of the life 

stages of individual species differed. Steelhead parr and smolts were captured throughout the 

sample period, but no fry were captured until May 17 (fig. 2). Daily catch of steelhead smolt 

peaked on April 22. Coho salmon fry were captured throughout the sampling period, but catch 

rate increased in late May (fig. 3). Coho salmon parr were primarily captured during late May 

and into June. Chinook salmon fry were captured throughout the sample period, but the peak 

daily catches occurred in the latter one-half of May (fig. 4). Chinook salmon parr were captured 

from April 24 to May 21. One Chinook salmon smolt was captured on May 26 and is the first 

known documentation of a Chinook salmon smolt from this site.

We also captured 19 lamprey, which could be either Pacific lamprey (Entosphenus 

tridentatus) or Brook lamprey (Lampetra richardsoni). These were not identified to species in 

the field. Fin clips for genetic analysis were obtained for all but two of the lamprey captured at 

the screw trap. 

There were some notable differences in the smolt trap monitoring and results in 2016 and

2017. During 2016, the trap was fished for 62 days, whereas during 2017, it was fished for 45 

days. Despite fewer sampling days, the number of fry and parr captured was greater in 2017 than 

in 2016 for all species (table 2), with the greatest difference being in Chinook salmon fry (2016, 

n = 4; 2017, n = 203). However, fewer steelhead and coho salmon smolts were captured in 2017 

than in 2016 (table 2). 

1

We began fishing the trap on April 10. April 11 was the first day the trap was checked and fish were handled, as 

indicated in figures 2–4 and table 2. 
10 

Pre-dam removal screw trapping in the White Salmon River (2007–09) provides an

opportunity for comparison with the post-Condit Dam removal screw trapping (2016–17; fig. 5). 

The screw trap was located at rkm 1.5 prior to dam removal and at rkm 2.3 after dam removal.

Catch-per-day of age-1 or older steelhead at the screw trap increased considerably since dam 

removal, whereas catch-per-day of age-0 steelhead slightly decreased. Catch-per-day of age-1 

coho salmon at the screw trap increased since dam removal, although catch-per-day of age-0 

coho salmon decreased. Age-0 Chinook salmon catch-per-day was much less in the post-dam 

removal years than in the pre-dam removal years. However, much of Chinook salmon spawning 

occurs downstream of the current smolt trap site at rkm 2.3. 

Electrofishing Results

We backpack electrofished in Mill, Buck, and Rattlesnake Creeks (table 1). We found O. 

mykiss, coho salmon, and cutthroat trout present at all three sites. We did not detect Chinook 

salmon at any electrofishing sites (table 4). We estimated abundance of age-0 and age-1 and 

older salmonids in sections of Rattlesnake and Buck Creeks (figs. 6 and 7; table 5); both sites 

had been sampled prior to removal of Condit Dam. Abundance of age-0 O. mykiss during 2017 

was 2.4 fish/m (standard error [SE] = 0.23) at the Rattlesnake Creek site and 1.2 fish/m (SE = 

0.27) at the Buck Creek site. Abundance of age-1 and older O. mykiss was 0.3 fish/m (SE = 0.03) 

at the Rattlesnake Creek site, and was 1.1 fish/m (SE = 0.11) at the Buck Creek site. In both 

Rattlesnake and Buck Creeks, age-0 O. mykiss abundance decreased between 2016 and 2017 

while the age-1 and older O. mykiss and coho salmon abundance increased (figs. 6 and 7). Coho 

salmon were found at the Rattlesnake Creek site for the first time in 2017, with an abundance of 

0.5 fish/m (SE = 0.08). Abundance of age-0 coho salmon at the Buck Creek site during 2017 was 

0.7 fish/m (SE = 0.08). 

Mean age-0 O. mykiss abundance (fish/m) at the Rattlesnake Creek site has been slightly 

lower post-dam removal (mean = 3.0, n = 2, range = 2.4–3.6) than pre-dam removal (mean = 3.4, 

n = 5, range = 1.5–5.1; fig. 6). However, the presence of juvenile coho salmon in Rattlesnake 

Creek during 2017 (0.5 fish/m) brought total age-0 salmonid abundance in 2017 to 2.9 fish/m. 

Mean age-1 or older O. mykiss abundance (fish/m) at the Rattlesnake Creek site has been lower 

post-dam removal (mean = 0.2, n = 2, range = 0.1–0.3) than pre-dam removal (mean = 0.5, n = 2, 

range = 0.3–0.8; fig. 6). Mean age-0 O. mykiss abundance (fish/m) at the Buck Creek site has 

been higher post-dam removal (mean = 2.1, n = 2, range = 1.2–3.0) than pre-dam removal (mean 

= 1.8, n = 2, range = 1.6–1.9; fig. 7). The addition of age-0 coho salmon to Buck Creek brings 

mean age-0 salmonid abundance to 2.7 fish/m post-dam removal (range = 1.9–3.4). Mean age-1 

or older O. mykiss abundance (fish/m) in Buck Creek has been slightly higher post-dam removal

(mean = 0.8, n = 2, range = 0.6–1.1) than pre-dam removal (mean = 0.6, n = 2, both years 0.6). 

In Mill Creek, we sampled at rkm 1.3 for species composition and found coho salmon, cutthroat 

trout (O. clarkii), and O. mykiss (table 4). This is the most upstream sampling and documentation 

of Coho Salmon in Mill Creek since Condit Dam removal. Cutthroat Trout were the most 

common species found at this location, and most were age-1 and older (appendix fig. 1.5). 
11 

Additional Passive Integrated Transponder-Tagging Data

We PIT-tagged salmonids captured by screw trapping and electrofishing, during 2016 

and 2017. Although the primary purpose of tagging is for mark-recapture estimates, additional 

data are possible through re-contacts of PIT-tagged fish both in the White Salmon watershed and 

at sites in the Columbia River. We are compiling these recapture and detection data. During 

2017, we recaptured 16 steelhead in Buck Creek and 7 in Rattlesnake Creek that were PITtagged in 2016. Twenty-one coho salmon and 34 steelhead that were PIT-tagged at the screw 

trap in 2016 were detected at juvenile detection sites in the Columbia River (Bonneville Dam, 

estuary trawl, bird colonies) during spring 2016. Two coho salmon PIT-tagged in Buck Creek 

and one steelhead PIT-tagged in Mill Creek during 2016 were recorded at juvenile detection sites 

in the Columbia River during 2017. 

Two coho salmon and one steelhead PIT-tagged at the screw trap in 2016 were detected 

at Bonneville Dam as adults in 2017. The two coho salmon were detected on September 28 and 

October 22, and the steelhead were detected on August 11. The steelhead was subsequently 

detected at The Dalles Dam on September 26. 

Discussion

During 2017, we continued to monitor juvenile salmonids for a second year in the White 

Salmon River following the removal of Condit Dam. These efforts have documented naturally 

spawned steelhead and coho salmon smolts, and Chinook salmon fry originating upstream of 

rkm 2.3. We again found juvenile coho salmon in Mill and Buck Creeks. In Mill Creek in 2017, 

we sampled farther upstream than in 2016 and found juvenile coho salmon. The range 

distribution of juvenile coho salmon expanded, with detection in Rattlesnake Creek for the first 

time since dam removal. 

Smolt trapping continued to be feasible at rkm 2.3, but high flows during 2017 made 

sampling difficult, with fewer operational days and low trap efficiency. The median daily flows 

for the last 97 years were around 1,500 ft3/s during mid-March to mid-June. In 2017, flows in 

mid-March were either near or greater than 3,000 ft3

/s, and were greater than 2,000 ft3/s for the 

entire sampling period (USGS streamgage 14123500, White Salmon River near Underwood, 

Washington). Some sample days were missed because of high flow, and the trap was sometimes

fished off the thalweg to avoid damage. Although recapture rates were similar to screw trapping 

recapture rates in nearby rivers of similar size (Buehrens and Cochran, 2016; Zendt and others, 

2016), the number of fish captured/recaptured was low, which precluded estimating abundance. 

Precision of smolt estimates could be improved by several methods to increase the 

number of fish captured or the trap efficiency (Jezorek and Hardiman, 2017). Further assessment 

of the trap location has resulted in a determination that a larger trap is unlikely to work at this 

site; however, an additional small trap is a possibility. Operation of other traps or weirs to collect 

and tag fish upstream of the main trap location could increase precision of estimates. These traps 

or weirs could be placed in the mainstem or in tributaries. Additional trapping and tagging would 

increase operating cost.
12 

The increase in Chinook salmon fry captured in the screw trapping during 2017 provides 

evidence of successful upstream spawning of Chinook salmon. A substantial flood occurred in 

the White Salmon River in December 2015 (estimated at a 25-year interval event). This flood, 

combined with the dynamic nature of much of the substrate in the river both upstream and 

downstream of the dam site, may have resulted in high egg-to-fry mortality due to bed scour and 

subsequent redd destruction during the previous egg incubation period. No such flood event 

occurred during fall 2016 or winter 2017. 

Although Chinook salmon fry catch greatly increased from 2016 to 2017, we captured far 

fewer Chinook salmon fry in the screw trap than during pre-dam removal sampling. During the 

pre-dam removal period, the screw trap was located farther downstream (rkm 1.5), and most fall 

Chinook salmon spawning occurs between there and the current trap location (rkm 2.3). 

However, fall Chinook salmon spawn upstream of rkm 2.3, as do most spring Chinook salmon 

(Jeremy Wilson, Washington Department of Fish and Wildlife, written commun., 2016). To date 

(2017), no assessment of Chinook salmon adult-to-juvenile recruitment has occurred in the 

White Salmon River. Continued monitoring will allow such relations to be explored. Genetic 

analysis will help assess the parental origin of juveniles captured at the trap.

The increase in catch-per-day of age-1 or older steelhead and age-1 coho salmon at the 

screw trap compared to pre-dam removal trapping provides evidence of successful spawning and 

smolt out-migration from upstream of the trap site. This may be a result of increased anadromous 

spawning in the watershed, increased suitable rearing habitat for fry or parr, or an increase in 

anadromous life-history expression from O. mykiss in the watershed. The slightly lower catchper-day rates for age-0 steelhead and coho salmon may result from increased rearing opportunity 

upstream of the trap site. Because any steelhead or coho salmon that spawned in the White 

Salmon River prior to 2012 had to do so downstream of Condit Dam (rkm 5.3), age-0 habitat 

may have been limited, resulting in downstream displacement. Specifically, the reach of the 

White Salmon between Condit Dam and the Powerhouse at rkm 3.0 had varied and reduced flow 

during power generation, which may have displaced fish. 

The detection of juvenile coho salmon in Mill Creek (to at least rkm 1.3), the increase in 

juvenile coho salmon abundance in Buck Creek (to at least rkm 2.2), and the detection of coho 

salmon in Rattlesnake Creek suggest increasing success of coho salmon spawning in the 

watershed. This could be a result of increased spawners or better instream conditions in 2017 

than 2016. Increases in abundance of age-1 or older O. mykiss at our sites in Buck and 

Rattlesnake Creeks may be a result of increased spawning success or increased survival 

following challenging instream conditions during summer 2016, particularly in Rattlesnake 

Creek.

Detections of PIT-tagged coho salmon at Bonneville Dam that were tagged in Buck 

Creek in 2016 indicate successful smolting. Detections of two adult coho salmon and one adult 

steelhead at Bonneville Dam that were PIT-tagged at the screw trap in 2016 could be indicative 

of the beginning of natural recolonization and viability of naturally spawned juveniles. Coho 

salmon and steelhead spawning frequency and juvenile use of the White Salmon River are

unknown. It is assumed that Husum Falls is a barrier to adult coho salmon, but further sampling 

is needed to assess coho salmon and steelhead distribution in the mainstem and tributaries. 
13 

Currently (2017), the White Salmon River is still a dynamic environment following the 

removal of Condit Dam and redistribution of sediments. Events such as the dry summer of 2015, 

the flood of December 2015, and the sustained high flow of spring and summer 2017 can affect 

different life stages of different species and influence population variability independent of 

spawner levels. The many possible limiting factors by life stage, species, and cohort in the 

watershed cannot be addressed without long-term monitoring of both adults and juveniles. Longterm trend analysis is required to reach firm conclusions about efficacy of restoration (Kondolf 

and others, 2007; Brewitt, 2016). Studies of restoration projects that are of short duration could 

result in premature and erroneous conclusions (Herrick and others, 2006). Pess (2009) reported 

that as many as 20–25 years may be required to restore salmonid populations following dam 

removal, highlighting the need for long-term studies. 

Adult anadromous fish are spawning in the areas of the White Salmon River watershed

made accessible by the removal of Condit Dam. Much remains to be learned about the origin of 

these adults and their spawning success. Juvenile fish are being produced, but their parental 

origin and relation to listed stocks is unknown. The potential influence of hatchery-origin 

spawners on an attempt to naturally reestablish a sustainable wild population (Dammerman and 

others, 2016) is a management concern. This is especially true of fall Chinook salmon, with both 

Tule and Bright stocks spawning in the river with potential for interbreeding and redd 

superimposition. 

The juvenile sampling methods used during 2016 and 2017 provided an opportunity to 

PIT tag fish and archive genetics samples. Genetic samples for O. mykiss captured in the 

watershed during 2016 are in the process of being analyzed to determine relatedness to resident 

stocks that were present upstream of the dam or to hatchery or wild steelhead potentially

recolonizing the White Salmon River watershed. Biologists have theorized that the White 

Salmon River may support both summer and winter run steelhead (Interior Columbia Technical 

Recovery Team, 2008; National Marine Fisheries Service, 2013b). The nearby Hood River, 

Oregon, and Klickitat River, Washington, support both summer and winter run steelhead. If the 

White Salmon River supports both summer and winter run steelhead, genetic analysis would be 

desirable to determine relatedness to local runs, which are assigned to different DPSs. The Hood 

River steelhead are considered part of the Lower Columbia River DPS, and the Klickitat River 

steelhead are considered part of the Middle Columbia DPS. The White Salmon steelhead are 

considered part of the Middle Columbia River DPS (Chinook and coho salmon in the White 

Salmon River are considered part of the Lower Columbia River ESU). 

We hope that the juvenile salmonid data collected in the White Salmon River watershed 

during 2016 and 2017 can be a starting point for a longer-term monitoring program in concert 

with other efforts by the WSTWG. These data can be of use in establishing some spawner/smolt 

relations and providing a basis for assessing changes in distribution and spawning success as 

fisheries trend data are gathered following this major dam removal. These data also will provide 

managers with information on VSP parameters needed to evaluate health of stocks of ESA listed 

fish. The descriptive data collected from juvenile and adult salmonids in the White Salmon 

watershed will help managers evaluate dam removal efficacy, the natural recolonization strategy, 

and the contribution of anadromous fish in the White Salmon River watershed to strengthening 

abundance and diversity of ESA listed populations. 
14 

Acknowledgments

We thank Margaret Neuman, Mid-Columbia Fisheries Enhancement Group (MCFEG), 

for her support and tireless efforts to acquire and administer funding for this project. We thank 

our fellow U.S. Geological Survey employees Shane Amen, Brad Liedtke, Rachel Ohnemus, 

Dennis Sitherwood, and Andy Wells, who provided many hours of help in the field and office. 

Seth Raehsler, with MCFEG, also provided field assistance. We also thank the U.S. Geological 

Survey Science in Support of Native American Relations program and the National Association 

of Geoscience Teachers program which provided support for seasonal staff. Jacob Anderson, 

with Klickitat County, provided support and communication assistance during the proposal 

process. Thomas Beuhrens and Bryce Glaser of WDFW provided support and feedback for our 

proposal. Additionally, they provided a tablet field computer for use at our smolt trap site, which 

saved many hours of manual data entry. Ben Warren and Daniel Warren, with the Washington 

Department of Fish and Wildlife, provided us with instruction in using the tablet computer. Larry 

Zeigenfuss, Joe Skalicky, and Mark Doulos, with the U.S. Fish and Wildlife Service (FWS),

provided us with permission to access FWS property and provided help with deployment and 

removal of the smolt trap. Joe Zendt and Mike Babcock, with the Yakama Nation Fisheries 

Program, provided us with passive integrated transponder tags. We would like to thank the 

landowners who provided access to their property, including PacificCorp, the U.S. Forest 

Service, the Washington State Department of Natural Resources, Steve Stampfli, and Terie 

Tietjen. We would also like to thank the technical and citizens committees of the Klickitat Lead 

Entity and the staff and board of the Lower Columbia Fish Recovery Board for their support. 
15 

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19 

Figure 1. Schematic of the White Salmon River watershed accessible to anadromous salmonids showing

locations of rotary screw trapping and electrofishing surveys during 2017 and the former location of Condit Dam, 

which was breached in 2011.
20 

0

1

2

3

4

11-Apr 18-Apr 25-Apr 2-May 9-May 16-May 23-May 30-May 6-Jun

Fish per Day

Date

Steelhead fry

n = 14

12-Jun

0

1

2

3

4

5

6

7

11-Apr 18-Apr 25-Apr 2-May 9-May 16-May 23-May 30-May 6-Jun

Fish per Day

Date

Steelhead parr 

n = 63

12-Jun

0

1

2

3

4

5

6

7

11-Apr 18-Apr 25-Apr 2-May 9-May 16-May 23-May 30-May 6-Jun

Fish per Day

Date

Steelhead smolt

n = 41 

12-Jun

Figure 2. Graphs showing daily catch of steelhead (Oncorhynchus mykiss) fry (upper graph), parr (middle 

graph), and smolts (lower graph) in the screw trap at river kilometer 2.3, White Salmon River, Washington, April 

11–June 12, 2017. Light gray shading indicates when the screw trap was not operated during April 15–17, April 

25–28, and May 5–13, 2017. Note that the scale on the y axis differs between the upper graph and the other two 

graphs. 
21 

0

1

2

3

4

5

6

7

11-Apr 18-Apr 25-Apr 2-May 9-May 16-May 23-May 30-May 6-Jun

Fish per Day

Date

Coho Salmon fry

n= 59

12-Jun

0

1

2

3

4

11-Apr 18-Apr 25-Apr 2-May 9-May 16-May 23-May 30-May 6-Jun

Fish per Day

Date

Coho Salmon parr

n = 25

12-Jun

0

1

2

3

4

11-Apr 18-Apr 25-Apr 2-May 9-May 16-May 23-May 30-May 6-Jun

Fish per Day

Date

Coho Salmon smolt

n = 13

12-Jun

Figure 3. Graphs showing daily catch of coho salmon (Oncorhynchus kisutch) fry (upper graph), parr (middle 

graph), and smolt (lower graph) in the screw trap at river kilometer 2.3, White Salmon River, Washington, April 

11–June 12, 2017. Light gray shading indicates when the screw trap was not operated during April 15–17, April 

25–28, and May 5–13, 2017. Note that scale on the y axis differs between the upper graph and the other two 

graphs. 
22 

0

10

20

30

40

50

11-Apr 18-Apr 25-Apr 2-May 9-May 16-May 23-May 30-May 6-Jun

Fish per Day

Date

Chinook Salmon fry

n = 207

12-Jun

0

1

2

3

4

5

6

7

8

9

10

11-Apr 18-Apr 25-Apr 2-May 9-May 16-May 23-May 30-May 6-Jun

Fish per Day

Date

Chinook Salmon parr

n = 20

12-Jun

Figure 4. Graph showing daily catch of Chinook salmon (Oncorhynchus tshwaytscha) fry (upper graph) and parr 

(lower graph) in the screw trap at river kilometer 2.3, White Salmon River, Washington, April 11–June 12, 2017. 

Only one Chinook Salmon smolt was captured on May 26, 2017. Light gray shading indicates when the screw 

trap was not operated during April 15–17, April 25–28, and May 5–13, 2017. Note that the scale on the y axis 

differs between graphs. 
23 

0

0.5

1

1.5

2

2.5

3

2007 2008 2009 2016 2017

Age-0

Age-1 or older

Steelhead

0

20

40

60

80

100

120

140

160

180

2007 2008 2009 2016 2017

Age-0

Chinook salmon

0

0.5

1

1.5

2

2.5

3

2007 2008 2009 2016 2017

Age-0

Age-1

Coho salmon

Fish-per-day

Figure 5. Graphs showing fish-per-day (number captured/days fished) of steelhead (Oncorhynchus mykiss; 

upper graph), coho salmon (O. kisutch; middle graph), and Chinook salmon (O. tshwaytscha; bottom graph) at a 

screw trap fished prior to (2007–09) and after (2016–17) removal of Condit Dam, White Salmon River, 

Washington. Screw trap was located at river kilometer (rkm) 1.5 prior to dam removal and at rkm 2.3 after dam 

removal. Much of the Chinook salmon spawning in the White Salmon River occurs downstream of rkm 2.3. Two 

age classes are shown for steelhead and coho salmon. Fewer than 0.15 age-1 Chinook salmon per day were 

captured in all years. Note that scale on the y axis differs between the upper two graphs and the other graph.
24 

Figure 6. Graph showing abundance estimates (fish per meter) of steelhead/rainbow trout (sth/rbt; 

Oncorhynchus mykiss) and coho salmon (O. kisutch) at a site on the lower kilometer of Rattlesnake Creek, 

Washington, 2001–05 and 2016–17. Estimates are shown for 5 years (2001–05) prior to removal of Condit Dam 

from the White Salmon River (breached in 2011), and after dam removal (2016-17). Error bars indicate standard 

error. 
25 

Figure 7. Graph showing abundance estimates (fish per meter) of steelhead/rainbow trout (sth/rbt; 

Oncorhynchus mykiss) and coho salmon (O. kisutch) at a sample site in river kilometer 2 of Buck Creek, 

Washington, 2009–10 and 2016–17. Estimates are shown for 2 years prior to removal of Condit Dam from the 

White Salmon River (breached in 2011), and after dam removal (2016-17). Error bars indicate standard error. 
26 

Table 1. Latitude and longitude (decimal degrees) of fish sampling sites, White Salmon River watershed, 

Washington, 2017. 

[Sample type: Ef. Dist., electrofishing distribution survey; Ef. Ab., electrofishing abundance survey. End point: NA, not 

applicable] 

Site Date Sample

type

Sample site coordinates 

Start point End point

Latitude Longitude Latitude Longitude

White Salmon1 04-11–6-12-2017 Screw trap2 45.74764 -121.52110 NA NA

Mill Creek 09-14-2017 Ef. Dist. 45.78386 -121.53582 45.78647 -121.53821

Buck Creek 08-28, 29-2017 Ef .Ab. 45.79603 -121.52914 45.79776 -121.52980

Rattlesnake Creek 08-30, 31-2017 Ef. Ab. 45.79759 -121.48174 45.79780 -121.47903

1

The White Salmon River screw trap operated intermittently from April 11 to June 12, 2017. 

2

Screw trap was a fixed sampling location. 

Table 2. Number of steelhead (Oncorhynchus mykiss), Chinook salmon (O. tshawytscha), and coho salmon (O. 

kisutch), by life stage, captured, tagged with passive integrated transponder (PIT) tags, and sampled for genetic 

material at the screw trap at river kilometer 2.3, White Salmon River, Washington, April 11, 2017–June 12, 2017.

[Fry were 45-millimeter fork length or less. N: Number of samples. Gen.: Fin tissue sample taken for genetic analysis. NA, 

not applicable; fry were not PIT-tagged] 

Year Life 

stage

Steelhead Chinook salmon Coho salmon

N

PITtagged Gen. NPITtagged Gen. NPITtagged Gen.

1

2016 Fry 9 NA NA 4 NA 2 19 NA 17

2016 Parr 23 20 21 0 0 0 2 NA 2

2016 Smolt 153 150 149 0 0 0 82 79 79

2016 Total 185 170 170 4 0 2 103 79 98

1

2017 Fry 14 NA 1 203 0 124 59 1 0

2017 Parr 61 57 59 19 3 16 21 11 0

2017 Smolt 40 39 40 1 1 1 13 11 2

2017 Total 115 96 100 223 4 141 93 23 1

1

The trap was fished for 62 days in 2016 and for 45 days in 2017. 
27 

Table 3. Number of steelhead (Oncorhynchus mykiss) and coho salmon (O. kisutch) smolt, and age-0 Chinook 

salmon captured, marked, and recaptured at the smolt trap at river kilometer 2.3, White Salmon River, 

Washington, March 24–May 28, 2016, and April 11–June 12, 2017.

[Smolt estimates are shown for steelhead and coho salmon during 2016. Because of prolonged high water and missed 

trapping days during 2017, we could not generate estimates. SE: standard error. 95-percent CI: 95-percent confidence 

interval. NA, not applicable.] 

Year

and species

Number

captured

Number 

of fish 

marked

Number

of fish

recaptured

Estimate SE 95-percent CI

20161

Steelhead 153 150 5 3,851 1,454 1,001–6,700

Coho 82 79 5 1,093 412 286–1,900

Age-0 Chinook 4 0 NA NA NA NA

20171

Steelhead 40 39 1 NA NA NA

Coho 13 12 0 NA NA NA

Age-0 Chinook 222 192 4 NA NA NA

1The trap was fished for 62 days in 2016 and for 45 days in 2017. 

Table 4. Number of juvenile salmonids captured and tagged with passive integrated transponder (PIT) tags, and 

tissue sampled for genetic analysis during electrofishing surveys, White Salmon River watershed, Washington,

2017.

[Species: Sth/Rbt, Oncorhynchus mykiss (steelhead or rainbow trout); Trout, trout fry that could not be differentiated 

between cutthroat trout (O. clarkii) or O. mykiss. Gen.: Fin tissue taken for genetic analysis. ≥, greater than or equal to] 

Site Dates

Site start

(river 

kilometer)

Sampled

length

(meter)

Species Age

(year) Catch PITtagged Gen. 

Mill Creek 09-14-2017 1.3 250 Trout 0 14 1 7

Mill Creek 09-14-2017 1.3 250 Sth/Rbt ≥1 4 4 2

Mill Creek 09-14-2017 1.3 250 Cutthroat ≥1 34 33 28

Mill Creek 09-14-2017 1.3 250 Coho 0 1 1 1

Buck Creek 08-28, 29-2017 2.0 230 Trout 0 104 31 37

Buck Creek 08-28, 29-2017 2.0 230 Sth/Rbt ≥1 155 144 11

Buck Creek 08-28, 29-2017 2.0 230 Cutthroat ≥1 1 1 0

Buck Creek 08-28, 29-2017 2.0 230 Coho 0 114 105 0

Rattlesnake Creek 08-30, 31-2017 0.3 223 Trout 0 280 211 37

Rattlesnake Creek 08-30, 31-2017 0.3 223 Sth/Rbt ≥1 57 54 7

Rattlesnake Creek 08-30, 31-2017 0.3 223 Cutthroat ≥1 2 2 0

Rattlesnake Creek 08-30, 31-2017 0.3 223 Coho 0 71 65 0
28 

Table 5. Abundance estimates and standard error, abundance (fish per meter) and density (fish per meter 

squared) of steelhead/rainbow trout (Oncorhynchus mykiss) and coho salmon (O. kisutch) at abundance 

electrofishing sites in Buck and Rattlesnake Creeks, Washington, August 2017.

[Site and species: Sth/Rbt, O. mykiss (steelhead or rainbow trout); Trout, trout fry that could not be differentiated between 

cutthroat trout or O. mykiss. SE: standard error for abundance estimate column to left. ≥, greater than or equal to) 

Site

and species

Age

(year)

Number 

of fish

marked

Number 

of fish

captured

Number

of fish

recaptured

Abundance

estimate SE

Fish

per 

meter

Fish per 

meter 

squared

Buck Creek

Trout 0 61 54 11 284 62.6 1.2 0.20

Sth/Rbt ≥1 92 106 37 262 25.9 1.1 0.18

Coho 0 75 62 27 171 18.8 0.7 0.12

Rattlesnake Creek

Trout 0 165 157 49 525 50.8 2.4 0.35

Sth/Rbt ≥1 41 34 20 70 6.7 0.3 0.05

Coho 0 45 39 15 115 17.4 0.5 0.08
29 

Appendix 1. Length Frequencies

Figure 1.1. Graph showing length frequency in 2-millimeter (mm) increments of steelhead/rainbow trout 

(Oncorhynchus mykiss) sampled in a 230-meter section at river kilometer 2, Buck Creek, Washington,

2017. Recaptured fish had been passive integrated transponder-tagged (PIT-tagged) in 2016.

Figure 1.2. Graph showing length frequency in 2-millimeter (mm) increments of coho salmon

(Oncorhynchus kisutch) sampled in a 230-meter section at river kilometer 2, Buck Creek, Washington,

2017. PIT, passive integrated transponder.
30 

Figure 1.3. Graph showing length frequency in 2-millimeter (mm) increments of steelhead/rainbow trout 

(Oncorhynchus mykiss) sampled in a 223-meter section at river kilometer 0.3, Rattlesnake Creek, 

Washington, 2017. Recaptured fish had been passive integrated transponder-tagged (PIT-tagged) in 2016.

Figure 1.4. Graph showing length frequency in 2-millimeter (mm) increments of coho salmon

(Oncorhynchus kisutch) sampled in a 223-meter section at river kilometer 0.3, Rattlesnake Creek, 

Washington, 2017. Recaptured fish had been passive integrated transponder-tagged (PIT-tagged) in 2016.
31 

Figure 1.5. Graph showing length frequency in 2-millimeter (mm) increments of steelhead/rainbow trout 

(RBT; Oncorhynchus mykiss), cutthroat trout (CTT; O. clarkii), and a coho salmon (COH; O. kisutch)

sampled in a 250-meter section at river kilometer 1.2, Mill Creek, Washington, 2017. Trout (TRT) are trout 

fry that could not be differentiated between cutthroat trout or O. mykiss, and were less than 55 mm fork

length. Note that one trout fry was passive integrated transponder -tagged (PIT-tagged) at a fork length of 

55 mm, and one cutthroat trout was not PIT-tagged (fork length of 89 mm). 
Publishing support provided by the U.S. Geological Survey

Science Publishing Network, Tacoma Publishing Service Center

For more information concerning the research in this report, contact the

Director, Western Fisheries Research Center

U.S. Geological Survey

6505 NE 65th Street

Seattle, Washington 98115 

https://wfrc.usgs.gov/
Jezorek and Hardiman—Juvenile Salmonid Monitoring Following Removal of Condit Dam, White Salmon River Watershed, Washington, 2017—Open-File Report 2018-1106

ISSN 2331-1258 (online)

https://doi.org/10.3133/ofr20181106