Prepared in cooperation with the U.S. Army Corps of Engineers

Total Dissolved Gas and Water Temperature in the Lower 

Columbia River, Oregon and Washington, Water Year 2014 

Open-File Report 2014–1237

U.S. Department of the Interior

U.S. Geological Survey
Cover: Salmon swimming past the fish ladder viewing window at Bonneville Dam on the Columbia River on their way 

upriver to spawning grounds. The U.S. Geological Survey measures dissolved gas levels in the river to help the U.S. 

Army Corps of Engineers regulate spill from its dams on the lower Columbia River to minimize the production of 

excess dissolved gas downstream of the dams. Dissolved gas concentration greater than 110 percent saturation is 

harmful to fish migrating downstream through the spillways on their way to the ocean. (Photograph courtesy of the 

U.S. Army Corps of Engineers)
Total Dissolved Gas and Water Temperature in the Lower 

Columbia River, Oregon and Washington, Water Year 2014 

By Heather M. Bragg and Matthew W. Johnston

Prepared in cooperation with the U.S. Army Corps of Engineers

Open-File Report 2014–1237

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2015 

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Suggested citation:

Bragg, H.M., and Johnston, M.W., 2015, Total dissolved gas and water temperature in the lower Columbia River, 

Oregon and Washington, water year 2014: U.S. Geological Survey Open-File Report 2014-1237, 26 p., 

http://dx.doi.org/10.3133/ofr20141237. 

ISSN 2331-1258 (online)

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Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

.
iii

Contents

Significant Findings........................................................................................................................................................ 1

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

Data Collection .............................................................................................................................................................. 3

Data Completeness ....................................................................................................................................................... 5

Quality-Assurance Data................................................................................................................................................. 7

Effects of Spill on Total-Dissolved-Gas Saturation .......................................................................................................10

Total-Dissolved-Gas and Water-Temperature Data......................................................................................................13

Acknowledgments ........................................................................................................................................................24

References Cited..........................................................................................................................................................24

Figures 

Figure 1. Location of U.S. Army Corp of Engineers dams and total-dissolved-gas monitoring stations, lower Columbia 

River, Oregon and Washington, water year 2014.......................................................................................................... 2

Figure 2. Boxplot showing accuracy of total-dissolved-gas sensors in the laboratory after 3 or 4 weeks of field 

deployment at eight monitoring stations in the lower Columbia River, Oregon and Washington, water year 2014........ 8

Figure 3. Boxplot showing difference between the secondary standard and the field barometers in the field after 3 or 

4 weeks of deployment at eight stations in the lower Columbia River, Oregon and Washington, water year 2014. ...... 9

Figure 4. Boxplot showing difference between the secondary standard and the field temperature instruments in the 

field after 3 or 4 weeks of deployment at eight stations in the lower Columbia River, Oregon and Washington, water 

year 2014....................................................................................................................................................................... 9

Figure 5. Boxplot showing difference between the secondary standard and the field total-dissolved-gas instruments in 

the field after 3 or 4 weeks of deployment at eight stations in the lower Columbia River, Oregon and Washington, 

water year 2014............................................................................................................................................................10

Figure 6. Graph showing relation of total-dissolved-gas saturation downstream of John Day Dam and spill from John 

Day Dam, lower Columbia River, Oregon and Washington, April 1–August 31, 2014. .................................................11

Figure 7. Graph showing relation of total-dissolved-gas saturation downstream of The Dalles Dam and spill from The 

Dalles Dam, lower Columbia River, Oregon and Washington, April 1–August 31, 2014. .............................................11

Figure 8. Graph showing relation of total-dissolved-gas saturation downstream of Bonneville Dam at Cascade Island 

and spill from Bonneville Dam, lower Columbia River, Oregon and Washington, April 1–August 31, 2014..................12

Figure 9. Boxplot showing distributions of hourly total-dissolved-gas data, lower Columbia River, Oregon and 

Washington, April 1–August 31, 2014...........................................................................................................................13

Figure 10. Graphs showing total-dissolved-gas saturation at John Day Dam navigation lock and spill from McNary 

Dam (76 river miles upstream of John Day Dam), lower Columbia River, Oregon and Washington, April 1–August 31, 

2014..............................................................................................................................................................................14

Figure 11. Graphs showing total-dissolved-gas saturation at John Day Dam tailwater and spill from John Day Dam, 

lower Columbia River, Oregon and Washington, April 1–August 31, 2014...................................................................15

Figure 12. Graphs showing total-dissolved-gas saturation at The Dalles Dam forebay and spill from John Day Dam, 

lower Columbia River, Oregon and Washington, April 1–August 31, 2014...................................................................16

Figure 13. Graphs showing total-dissolved-gas saturation at The Dalles Dam tailwater and spill from The Dalles Dam, 

lower Columbia River, Oregon and Washington, April 1–August 31, 2014...................................................................17
iv

Figure 14. Graphs showing total-dissolved-gas saturation at Bonneville Dam forebay and spill from The Dalles Dam, 

lower Columbia River, Oregon and Washington, April 1–August 31, 2014...................................................................18

Figure 15. Graphs showing total-dissolved-gas saturation at Cascade Island and spill from Bonneville Dam, lower 

Columbia River, Oregon and Washington, April 1–August 31, 2014. ...........................................................................19

Figure 16. Graphs showing total-dissolved-gas saturation at Warrendale and spill from Bonneville Dam, lower 

Columbia River, Oregon and Washington, April 1–August 31, 2014. ...........................................................................20

Figure 17. Graphs showing total-dissolved-gas saturation at Camas and spill from Bonneville Dam, lower Columbia 

River, Oregon and Washington, April 1–August 31, 2014. ...........................................................................................21

Figure 18. Graph showing hourly water temperature values upstream of John Day Dam and downstream of John Day 

Dam, lower Columbia River, Oregon and Washington, summer 2014..........................................................................22

Figure 19. Graph showing hourly water temperature values upstream and downstream of The Dalles Dam, lower 

Columbia River, Oregon and Washington, summer 2014.............................................................................................22

Figure 20. Graph showing hourly water temperature values upstream of Bonneville Dam and downstream of 

Bonneville Dam at Cascade Island, lower Columbia River, Oregon and Washington, summer 2014...........................23

Figure 21. Graph showing hourly water temperature values upstream of Bonneville Dam and downstream of 

Bonneville Dam at Warrendale, lower Columbia River, Oregon and Washington, summer 2014................................23

Figure 22. Graph showing hourly water temperature values downstream of Bonneville Dam at Camas, lower 

Columbia River, Oregon and Washington, summer 2014.............................................................................................24

Tables

Table 1. Total-dissolved-gas monitoring stations, lower Columbia River, Oregon and Washington, water year 2014.4

Table 2. Completeness and quality of total-dissolved gas data, lower Columbia River, Oregon and Washington, water 

year 2014.................................................................................................................................................................... 6

Table 3. Periods of missing real-time total-dissolved-gas data, lower Columbia River, Oregon and Washington, water 

year 2014.................................................................................................................................................................... 7
v 

Conversion Factors

Multiply By To obtain

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

mile (mi) 1.609 kilometer (km)

millimeter (mm) 0.03937 inch (in.)

square mile (mi2) 2.590 square kilometer (km2) 

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

Datum

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).

Abbreviations

BON Bonneville forebay

CCIW Cascade Island

CWMW Camas

DCP Data-collection platform

JDY John Day navigation lock 

JHAW John Day tailwater

NIST National Institute of Standards and Technology

RM River mile

TDA The Dalles forebay

TDDO The Dalles tailwater

TDG Total dissolved gas

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey

WRNO Warrendale
vi

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1 

Total Dissolved Gas and Water Temperature in the Lower 

Columbia River, Oregon and Washington, Water Year 2014 

By Heather M. Bragg and Matthew W. Johnston

Significant Findings

An analysis of total-dissolved-gas (TDG) and water-temperature data collected at eight fixed 

monitoring stations on the lower Columbia River in Oregon and Washington in water year 2014 indicated 

the following: 

• All 81 TDG sensor laboratory checks that were performed after field deployment were within plus or 

minus (±) 0.5-percent saturation of a primary standard. 

• After 3–4 weeks of deployment in the river, 68 of 75 TDG sensor field checks were within ±1.0-

percent saturation of a secondary standard. Six of the field checks greater than ±1.0-percent saturation

occurred at the John Day tailwater station, and three of these six checks resulted in periods of deleted 

data at the station. 

• All 77 barometric pressure field checks were within ±1 millimeter of mercury of a primary standard, 

and all 74 water-temperature field checks were within ±0.2 degrees Celsius of a secondary standard. 

• TDG data were considered complete if they were received in real time and were within 1-percent 

saturation of the expected value on the basis of calibration data, replicate quality-control 

measurements, and comparison to river conditions at adjacent stations. For the eight monitoring 

stations, data completeness ranged from 78.2 to 100 percent. 

• All quality-assurance values exceed the criteria established by the U.S. Army Corps of Engineers TDG 

monitoring plan. Criteria for data completeness (95 percent) were met at six of the eight monitoring 

stations. Deleted data at the John Day tailwater station and missed transmissions at the Camas station

resulted in data completeness below criteria. 
2 

Introduction

The U.S. Army Corps of Engineers (USACE) operates several dams in the lower Columbia River 

Basin in Oregon and Washington (fig. 1), which encompasses 259,000 mi2 of the Pacific Northwest. 

These dams are multipurpose structures that fulfill regional needs for flood control, navigation, irrigation, 

recreation, hydropower production, fish and wildlife habitat, water-quality maintenance, and municipal 

and industrial water supply. When water is released through the spillways of these dams (instead of being 

routed through the turbines to generate electricity), ambient air is entrained in the water. This results in an 

increase in the concentration of dissolved gases (referred to here as “total dissolved gas,” or “TDG”) in the 

water downstream of the spillways. Concentrations of TDG greater than 110-percent saturation can cause 

gas-bubble trauma in fish and adversely affect other aquatic organisms (U.S. Environmental Protection 

Agency, 1986). The USACE regulates streamflow and spill from its dams on the lower Columbia River to 

minimize the production of excess TDG downstream of the dams, with the additional goal of providing for 

fish passage through the spillways (rather than through the turbines). 

Base map modified from USGS and other digital data, variable scales. Projection unknown.

Figure 1. Location of U.S. Army Corp of Engineers dams and total-dissolved-gas monitoring stations, lower Columbia 

River, Oregon and Washington, water year 2014. 

Real-time TDG and water-temperature data are vital to the USACE for dam operation and for 

monitoring compliance with environmental regulations. The data are used by water managers to maintain 

water-quality conditions that facilitate fish passage and ensure their survival in the lower Columbia River. 

The U.S. Geological Survey (USGS), in cooperation with the Portland District of the USACE, has 

collected TDG and related data in the lower Columbia River each year since 1996. The hourly values were 

stored in the USGS database and in a USACE database (U.S. Army Corps of Engineers, 2014). Those data 

are available online within approximately an hour of collection time, and the current and historical TDG 

and water-temperature data can be accessed at http://oregon.usgs.gov/projs_dir/pn307.tdg/ (accessed 

October 27, 2014). The USACE database also includes hourly river discharge and spill data. 
3 

Fifteen previous reports, published for water years 1996 and 2000–2013, describe the TDG data, 

quality-assurance data, and methods of data collection (Tanner and others, 1996; Tanner and Bragg, 2001; 

Tanner and Johnston, 2001; Tanner and others, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011, 

2012, 2013; Bragg and Johnston, 2014).

This report presents the TDG data and related quality-assurance data that demonstrate the USACE 

Portland District compliance with the TDG monitoring plan (U.S. Army Corps of Engineers, 2008). To 

assure the accuracy and integrity of the data needed for managing and modeling TDG in the lower 

Columbia River, hourly values were reviewed relative to concurrent field measurements, laboratory sensor 

calibrations, and inter-site comparisons. All deleted or missing data are explained in detail. 

Data Collection

Eight monitoring stations were operated on the lower Columbia River, from the navigation lock of the 

John Day Dam (river mile [RM] 215.7) to Camas, Washington (RM 121.7) (fig. 1, table 1). Data for water 

year 2014 (October 1, 2013–September 30, 2014) include hourly measurements of TDG pressure, 

barometric pressure, water temperature, and sensor depth. Four of the stations (John Day Dam navigation 

lock, The Dalles Dam forebay, Bonneville Dam forebay, and Camas) were operated from March to 

September 2014, the period that includes the usual time for dam-spill operations. The stations John Day 

Dam tailwater, The Dalles Dam tailwater, and Warrendale were operated year-round. Warrendale and 

Camas remain part of the monitoring program, although TDG data from the stations are no longer part of 

the USACE spill management program.
4

Table 1. Total-dissolved-gas monitoring stations, lower Columbia River, Oregon and Washington, water year 2014.

[Map reference number refers to figure 1; USACE, U.S. Army Corps of Engineers; Columbia River mile locations were determined from U.S. Geological Survey (USGS) 

7.5-minute topographic maps; stations in this report are referenced by their abbreviated name or USACE station identifier; °, degree; ', minute; ", second; latitude and 

longitude are referenced to the North American Datum of 1927; River mile is distance from the mouth of the Columbia River.] 

Map

reference

number

USACE

station

identifier

River 

mile

USGS 

station number

USGS station name

(and abbreviated station name) Latitude Longitude

Period of 

record in water 

year 2014

1 JDY 215.7 454314120413701 Columbia River at John Day Dam navigation 

lock, Washington (John Day navigation lock)

45° 43' 14" 120° 41' 37" 03/11/14–

09/15/14

2 JHAW 214.7 454249120423500 Columbia River, right bank, near Cliffs, 

Washington (John Day tailwater)

45° 42' 49" 120° 42' 35" 10/01/13–

09/30/14 

3 TDA 192.6 453712121071200 Columbia River at The Dalles Dam forebay, 

Washington (The Dalles forebay)

45° 37' 12" 121° 07' 12" 03/12/14–

09/16/14

4 TDDO 188.9 14105700 Columbia River at The Dalles, Oregon (The 

Dalles tailwater)

45° 36' 27" 121° 10' 20" 10/01/13–

09/30/14 

5 BON 146.1 453845121562000 Columbia River at Bonneville Dam forebay, 

Washington (Bonneville forebay)

45° 38' 45" 121° 56' 20" 03/12/14–

09/24/14

6 CCIW 145.9 453845121564001 Columbia River at Cascade Island, 

Washington (Cascade Island)

45° 38' 45" 121° 56' 40” 03/26/14–

09/17/14

7 WRNO 140.4 453630122021400 Columbia River, left bank, near Dodson, 

Oregon (Warrendale)

45° 36' 30" 122° 02' 14" 10/01/13–

09/30/14 

8 CWMW 121.7 453439122223900 Columbia River, right bank, at Washougal, 

Washington (Camas)

45° 34' 39" 122° 22' 39" 03/14/14–

09/18/14
5 

Instrumentation at each monitoring station consists of a Hach® Hydrolab water-quality instrument, a 

Vaisala electronic barometer, a Sutron SatLink2 data-collection platform (DCP), and a power supply. The 

instruments at each station are powered by a 12-volt battery that is charged by a solar panel or a 120-volt 

alternating-current line. Measurements are collected, logged, and transmitted every hour. The DCP 

transmits the four most recent hours of logged data to the Geostationary Operational Environmental 

Satellite system (Jones and others, 1991). The data are automatically decoded and transferred to the 

USACE and USGS databases. 

Station visits were completed every 4 weeks at the three year-round stations during September 2013 

through March 2014, and every 3 weeks at all eight stations during March 2014 to September 2014. The 

field calibration procedure was as follows: A reference Hydrolab (which was calibrated before the field 

trip for use as a secondary standard) was deployed alongside the field-deployed Hydrolab for as long as 1 

hour to obtain comparison measurements of TDG and water temperature. The field Hydrolab (which had 

been deployed for 3 or 4 weeks) was then removed and replaced with another Hydrolab that had been 

recently calibrated in the laboratory. The newly deployed Hydrolab was allowed to equilibrate and the 

secondary standard was again used to compare TDG and temperature values. The electronic barometer at 

the monitoring station was calibrated using a portable barometer (NovaLynx 230-M202) that is calibrated 

annually to National Institute of Standards and Technology (NIST) standards.

During each field visit, the minimum compensation depth was calculated to determine whether the 

Hydrolab was positioned at an appropriate depth to obtain an accurate measurement of TDG. This 

minimum compensation depth, which was calculated according to Colt (1984, p. 104), is the depth above 

which degassing will occur because of decreased hydrostatic pressure. To measure TDG accurately, the 

Hydrolabs were positioned, whenever possible, at a depth below the calculated minimum compensation 

depth. 

The Hydrolab that was removed from the field after 3 or 4 weeks of deployment was later calibrated 

in the laboratory. The integrity of the TDG membrane was tested, and the membrane was removed and 

air-dried. The TDG sensor (without the membrane attached) was calibrated at 0, 100, 200, and 300 

millimeters of mercury (mm Hg) greater than atmospheric pressure to span the expected range of TDG in 

the river (approximately 100-, 113-, 126-, and 139-percent saturation, respectively). The membrane was 

then installed on the TDG sensor and retested. 

Data Completeness 

To assure the accuracy and integrity of the TDG data in the lower Columbia River, hourly values 

were reviewed relative to concurrent field measurements, laboratory instrument calibrations, and daily 

inter-site comparisons. A summary of the completeness of the TDG percent saturation data is shown in 

table 2. Data were based on the total number of hourly TDG and barometric pressure data values that 

could have been collected during the monitoring season. No barometric pressure data were missing when 

TDG data were available, so data completeness relies on TDG data only. TDG saturation values were 

considered to meet quality-assurance standards if they were within plus or minus (±)1-percent saturation 

of the expected value. 
6 

Table 2. Completeness and quality of total-dissolved gas data, lower Columbia River, Oregon and 

Washington, water year 2014.

[TDG, total dissolved gas]

Abbreviated

station name

Planned

monitoring

(hours) 

Number of

missing or deleted 

hourly values

Percentage of real-time 

TDG data passing 

quality assurance 

criteria

John Day navigation lock

(JDY) 4,510 1 100

John Day tailwater

(JHAW) 8,760 1,517 82.7

The Dalles forebay

(TDA) 4,511 141 96.9

The Dalles tailwater

(TDDO) 8,760 6 99.9

Bonneville forebay

(BON) 4,701 1 100

Cascade Island

(CCIW) 4,199 4 99.9

Warrendale

(WRNO) 8,760 31 99.6

Camas

(CWMW) 4,513 985 78.2

Periods for which substantial spans of TDG data were either missing from the database or were later 

deleted from the database because they did not meet quality-assurance standards are listed in table 3. 

Failed instrument communications and datalogger transmissions were the most common causes of missing 

data, although most of those data were recovered and later entered into the databases. Most of the deleted 

data were from the John Day tailwater station. Review of the field checks and in-stream data indicated 

erroneously low TDG values during three periods: October–November 2013, August 2014, and September 

2104. Additional data collection and analysis are ongoing to determine the cause of the low data values. 
7 

Table 3. Periods of missing real-time total-dissolved-gas (TDG) data, lower Columbia River, Oregon and Washington, 

water year 2014.

[USACE (U.S. Army Corps of Engineers) station identifier: JHAW, John Day tailwater; TDA The Dalles forebay; TDDO, The 

Dalles tailwater; WRNO, Warrendale; CWMW, Camas] 

Date

USACE 

station 

identifier

Reason / Note

10/01/13–11/08/13

08/07/14–08/26/14

09/15/14–09/21/14

JHAW Erroneously low TDG values

05/15/14–05/17/14

05/28/14–06/02/14 TDA Failed communication between the water-quality instrument and 

datalogger

03/12/14 TDDO Water-quality instrument removed from deployment pipe during 

maintenance

02/09/14

02/10/14

03/02/14

WRNO Failed satellite transmissions owing to inclement weather 

03/31/14–04/02/14

06/30/14–07/24/14 CWMW Failed satellite transmissions; data were recovered

07/25/14–07/29/14

08/16/14–08/25/14 CWMW Ruptured membrane on TDG sensor

07/29/14–07/30/14 CWMW Datalogger malfunction

Quality-Assurance Data

The collection of accurate data for TDG, barometric pressure, and water temperature involves several 

quality-assurance procedures, including side-by-side instrument comparisons in the field, sensor 

calibrations in the laboratory, daily checks of the data, and data review and archiving. The results of the 

quality-assurance procedures for water year 2014 are presented in this section. 

After field deployment for 3 or 4 weeks, the TDG instruments were calibrated in the laboratory. First, 

the sensor was tested, with the gas-permeable membrane in place, for response to supersaturated

conditions. The membrane was then removed from the sensor and allowed to dry for at least 24 hours. 

Before replacing the membrane, the TDG sensor was examined independently by comparing the reading 

of the TDG sensor to barometric pressure (100-percent saturation). Using a certified digital pressure gage 

(primary standard), comparisons were also made at pressures of 100, 200, and 300 mm Hg greater than

barometric pressure (approximately 113-, 126-, and 139-percent saturation, respectively). The accuracy of 

the TDG sensors was calculated as the difference between the primary standard and the TDG sensor 

reading (expected minus actual) for each of the four test conditions divided by the barometric pressure and 

multiplied by 100 to obtain a percentage difference. Of the 81 laboratory checks that were performed on 

instruments after field deployment, all were within ±0.5-percent saturation (fig. 2). 
8 

Figure 2. Boxplot showing accuracy of total-dissolved-gas sensors in the laboratory after 3 or 4 weeks of 

field deployment at eight monitoring stations in the lower Columbia River, Oregon and Washington, water 

year 2014 (number of comparison values =81). 

The differences in barometric pressure, water temperature, and TDG between the secondary standard 

instruments and the station monitors at the end of their field deployment were measured and recorded as 

part of every field inspection and calibration procedure. These differences, calculated as the secondary 

standard values minus the field instrument values, were used to compare and quantify the accuracy and 

precision between the two instruments. For water temperature and TDG, the measurements were made 

with the secondary standard (a recently calibrated Hydrolab) positioned alongside the Hydrolab deployed 

in the river. A digital barometer (NIST certified through April 2015) served as the primary standard for 

barometric pressure. The distribution of quality-assurance data for each of the three parameters from the 

eight stations is shown in figures 3, 4, and 5. 

Comparisons of the digital barometer and the field barometers are shown in figure 3. All of the field 

values were within 1 mm Hg of standard values. The secondary standard temperature sensor and the field 

temperature sensor results are presented in figure 4. All differences were within 0.2 °C. 
9 

Figure 3. Boxplot showing difference between the secondary standard and the field barometers in the field 

after 3 or 4 weeks of deployment at eight stations in the lower Columbia River, Oregon and Washington, 

water year 2014. See figure 2 for explanation of boxplots and table 1 for definitions of station identifiers.

Figure 4. Boxplot showing difference between the secondary standard and the field temperature 

instruments in the field after 3 or 4 weeks of deployment at eight stations in the lower Columbia River, 

Oregon and Washington, water year 2014. See figure 2 for explanation of boxplots and table 1 for 

definitions of station identifiers. 

Differences between the secondary standard TDG sensor and the field TDG sensors were calculated 

following equilibration of the secondary standard instrument to the site conditions before removing the 

field instrument. The side-by-side equilibrium was considered complete after a minimum of 20 minutes 

when the TDG values for each sensor remained constant for 3–5 minutes. Excluding the John Day 

tailwater station, only 1 of the 61 TDG field checks indicated a saturation difference greater than ±1.0 

percent (fig. 5). That difference (+2.0 percent) was recorded at Warrendale and was likely the result of an 

incomplete equilibration of the reference Hydrolab during changing in-stream conditions. No data were 

deleted as a result of that field check. Of the 14 field checks at the John Day tailwater station, two were 

+1–2 percent and four were +2–5 percent. Three of the checks resulted in periods of deleted data (table 3).
10

The three other checks seemed to be the result of incomplete reference Hydrolab equilibrations or 

changing in-stream conditions rather than true differences, and no data were deleted.

Figure 5. Boxplot showing difference between the secondary standard and the field total-dissolved-gas instruments 

in the field after 3 or 4 weeks of deployment at eight stations in the lower Columbia River, Oregon and Washington, 

water year 2014. See figure 2 for explanation of boxplots and table 1 for definitions of station identifiers. 

Effects of Spill on Total-Dissolved-Gas Saturation 

The relation between spill discharge at the dams and TDG at the corresponding tailwater station or 

stations is shown for John Day Dam (fig. 6), The Dalles Dam (fig. 7), and Bonneville Dam (fig. 8). For 

spill between approximately 25,000 and 70,000 ft3/s, the TDG saturation downstream of John Day Dam 

remained relatively level or slightly decreasing between 111 percent and 116 percent. For spill greater 

than 70,000 ft3

/s, the TDG saturation increased steadily with greater spill. At the stations downstream of 

The Dalles Dam and Bonneville Dam, the TDG saturation values generally increased with greater spill 

over the entire range of values.
11

Figure 6. Graph showing relation of total-dissolved-gas saturation downstream of John Day Dam and spill 

from John Day Dam, lower Columbia River, Oregon and Washington, April 1–August 31, 2014.

Figure 7. Graph showing relation of total-dissolved-gas saturation downstream of The Dalles Dam and spill 

from The Dalles Dam, lower Columbia River, Oregon and Washington, April 1–August 31, 2014. 
12

Figure 8. Graph showing relation of total-dissolved-gas saturation downstream of Bonneville Dam at Cascade 

Island and spill from Bonneville Dam, lower Columbia River, Oregon and Washington, April 1–August 31, 2014. 
13

Total-Dissolved-Gas and Water-Temperature Data

The distribution of hourly TDG values for the 2014 spill season (April 1–August 31, 2014) is shown 

in figure 9. Time-series plots of the hourly TDG percent saturation and the spill at the closest upstream 

dam are shown in figures 10–17. 

The hourly values for water temperature are shown in figures 18–22. Water temperatures at the 

forebay stations were approximately equal to the temperatures at the tailwater stations, except during short 

periods at the John Day Dam stations and at the Bonneville Dam forebay and Warrendale stations. 

Figure 9. Boxplot showing distributions of hourly total-dissolved-gas data, lower Columbia River, 

Oregon and Washington, April 1–August 31, 2014. See figure 2 for explanation of boxplots and 

table 1 for definitions of station identifiers. 
 

14

Figure 10. Graphs showing total-dissolved-gas (TDG) saturation at John Day Dam navigation lock and spill from McNary Dam

(76 river miles upstream of John Day Dam), lower Columbia River, Oregon and Washington, April 1–August 31, 2014. 
 

15

Figure 11. Graphs showing total-dissolved-gas (TDG) saturation at John Day Dam tailwater and spill from John Day Dam, lower 

Columbia River, Oregon and Washington, April 1–August 31, 2014. 
 

16

Figure 12. Graphs showing total-dissolved-gas (TDG) saturation at The Dalles Dam forebay and spill from John Day Dam, 

lower Columbia River, Oregon and Washington, April 1–August 31, 2014. 
 

17

Figure 13. Graphs showing total-dissolved-gas (TDG) saturation at The Dalles Dam tailwater and spill from The Dalles Dam, 

lower Columbia River, Oregon and Washington, April 1–August 31, 2014. 
 

18

Figure 14. Graphs showing total-dissolved-gas (TDG) saturation at Bonneville Dam forebay and spill from The Dalles Dam, 

lower Columbia River, Oregon and Washington, April 1–August 31, 2014. 
 

19

Figure 15. Graphs showing total-dissolved-gas (TDG) saturation at Cascade Island and spill from Bonneville Dam, lower 

Columbia River, Oregon and Washington, April 1–August 31, 2014. 
 

20

Figure 16. Graphs showing total-dissolved-gas (TDG) saturation at Warrendale and spill from Bonneville Dam, lower Columbia 

River, Oregon and Washington, April 1–August 31, 2014. 
 

21

Figure 17. Graphs showing total-dissolved-gas (TDG) saturation at Camas and spill from Bonneville Dam, lower Columbia River, 

Oregon and Washington, April 1–August 31, 2014.
22

Figure 18. Graph showing hourly water temperature values upstream of John Day Dam and downstream of 

John Day Dam, lower Columbia River, Oregon and Washington, summer 2014. 

Figure 19. Graph showing hourly water temperature values upstream and downstream of The Dalles Dam, 

lower Columbia River, Oregon and Washington, summer 2014. 
23

Figure 20. Graph showing hourly water temperature values upstream of Bonneville Dam and downstream of 

Bonneville Dam at Cascade Island, lower Columbia River, Oregon and Washington, summer 2014. 

Figure 21. Graph showing hourly water temperature values upstream of Bonneville Dam and downstream of 

Bonneville Dam at Warrendale, lower Columbia River, 

Oregon and Washington, summer 2014. 
24

Figure 22. Graph showing hourly water temperature values downstream of Bonneville Dam at Camas, lower 

Columbia River, Oregon and Washington, summer 2014. 

Acknowledgments

The authors extend special thanks to Tina Lundell (U.S. Army Corps of Engineers) for technical and 

logistical support of the project. The authors also thank Amy M. Brooks (U.S. Geological Survey [USGS]) 

for reviewing the data and Danial Polette (USGS) for conducting field and laboratory calibration checks. 

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