Front cover: 

Native-American fishing platform on the Columbia River near Cliffs, Washington. In the foreground is the 

pipe housing the total-dissolved-gas sensor at the John Day tailwater monitoring site.

(Photograph by Heather M. Bragg, U.S.Geological Survey) 
Total Dissolved Gas and Water Temperature 

in the Lower Columbia River, Oregon and 

Washington, 2004: Quality-Assurance Data 

and Comparison to Water-Quality Standards

By Dwight Q. Tanner, Heather M. Bragg, and Matthew W. Johnston

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

Scientific Investigations Report 2004–5249

U.S. Department of the Interior

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

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Portland, Oregon: 2004

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

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Telephone: 1-888-ASK-USGS

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Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners 

to reproduce any copyrighted materials contained within this report.

Suggested citation: 

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

Oregon and Washington, 2004—Quality-assurance data and comparison to water-quality standards, U.S. Geological 

Survey Scientific Investigations Report 2004-5249, 20 p.
 iii

CONTENTS

Significant Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Methods of Data Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Summary of Total-Dissolved-Gas Data Completeness and Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Quality-Assurance Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Effects of Spill on Total Dissolved Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Comparison of Total Dissolved Gas and Temperature to Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

References Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figures 

1. Map showing location of total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, 

water year 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2. Accuracy of total-dissolved-gas sensors after 2 to 3 weeks of field deployment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3. Difference between the secondary standard and the field barometers after 2 to 3 weeks of field deployment. . . . . . . . 12

4. Difference between the secondary standard and the field temperature instruments after 2 to 3 weeks of field 

deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5. Difference between the secondary standard and the field total-dissolved-gas instruments after 2 to 3 weeks 

of field deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6. Total dissolved gas downstream of John Day Dam and spill from John Day Dam, April 10 to September 4, 2004 . . . . . . 14

7. Total dissolved gas downstream of The Dalles Dam and spill from The Dalles Dam, April 10 to September 4, 2004 . . . . 15

8. Total dissolved gas downstream of Bonneville Dam at Warrendale and spill from Bonneville Dam, April 10 

to September 4, 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

9. Response of total dissolved gas at Cascade Island to spill from Bonneville Dam, April 21 to June 3, 2004 . . . . . . . . . . . . 17

10. Response of total dissolved gas at Warrendale to spill from Bonneville Dam, April 21 to June 3, 2004 . . . . . . . . . . . . . . . 17

11. Total dissolved gas upstream of John Day Dam, April 10 to September 4, 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

12. Total dissolved gas upstream of the Dalles Dam, April 10 to September 4, 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

13. Total dissolved gas upstream of Bonneville Dam, April 10 to September 4, 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

14. Total dissolved gas at Camas, April 10 to September 4, 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

15. Distributions of hourly total-dissolved-gas data and exceedances of Oregon and Washington water-quality 

variances, April 12, 2004 to August 31, 2004. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

16. Water temperature upstream and downstream of John Day Dam for summer 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

17. Comparison of hourly water temperature at John Day forebay and John Day tailwater, March 25, 2003 

to September 15, 2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

18. Comparison of hourly water temperature at John Day navigation lock and John Day tailwater, March 25, 2004 

to September 15, 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

19. Water temperature upstream and downstream of The Dalles Dam for summer 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

20. Water temperature upstream and downstream of Bonneville Dam for summer 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

21. Water temperature at Camas for summer 2004. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
iv

Tables

1. Total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, water year 2004 . . . . . . . . . . . . . . . . . 10

2. Total-dissolved-gas data completeness and quality, lower Columbia River, Oregon and Washington, 

water year 2004. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3. Exceedances of States of Oregon and Washington water-quality variances for total dissolved gas, 

lower Columbia River, Oregon and Washington, water year 2004. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Conversion Factors and Datum

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 x °C) + 32

Multiply By To obtain

Area

inch (in) 2.54 centimeter (cm)

mile (mi) 1.609 kilometer (km)

square mile (mi2) 2.59 square kilometer (km2)

cubic feet per second (ft3/s) 0.028317 cubic meters per second (m3/s)

inch (in) 2.54 centimeter (cm)
Total Dissolved Gas and Water Temperature 

in the Lower Columbia River, Oregon and 

Washington, 2004: Quality-Assurance Data 

and Comparison to Water-Quality Standards 

By Dwight Q. Tanner, Heather M. Bragg, and Matthew W. Johnston

Significant Findings

When water is released through the spillways of dams, air 

is entrained in the water, increasing the downstream concentration of total dissolved gas. Excess dissolved-gas concentrations 

can have adverse effects on freshwater aquatic life. The U.S. 

Geological Survey (USGS), in cooperation with the U.S. Army 

Corps of Engineers (USACE), collected total-dissolved-gas 

(TDG) and water-temperature data at eight sites on the lower 

Columbia River in 2004. Significant findings from the data 

include:

• Variances to the Oregon and Washington water-quality 

standards for total dissolved gas were exceeded on a 

few days at three of the monitoring sites: Camas, The 

Dalles forebay, and Bonneville forebay. These exceedances may have been the result of the cumulative 

effects of supersaturated water moving downstream 

through the lower Columbia River. Apparently, the 

levels of TDG did not dissipate rapidly enough downstream from the dams before reaching the next site.

• TDG levels at an experimental monitoring site directly 

below Bonneville Dam at Cascade Island showed a 

larger response to spill than the site 5.5 miles farther 

downstream at Warrendale. 

• From mid-July to mid-September, water temperatures 

were above 20°C (degrees Celsius) at each of the seven 

lower Columbia River sites. Both the Oregon and 

Washington water-quality standards contain a numerical standard of 20°C for the lower Columbia River.

• The new location of the forebay monitoring site at John 

Day navigation lock showed less daily temperature 

variation than the previous location. The probe at the 

new site was farther away from the dam and at a greater 

depth, so it apparently avoided the daily temperature 

excursions associated with the surface-layer heating at 

the previous site. 

• Most field checks of total-dissolved-gas sensors with 

a secondary standard were within ±1% saturation. Most 

of the field checks of barometric pressure were within 

±1 mm Hg (millimeter of mercury) of a secondary 

standard, and water temperature field checks were all 

within ± 0.1°C.

• For the seven monitoring sites used to regulate spill 

in water year 2004, an average of 99.0% of the totaldissolved-gas data were received in real time by the 

USGS satellite downlink and were within 1% saturation of the expected value, based on calibration data, 

replicate quality-control measurements in the river, 

and comparison to ambient river conditions at adjacent 

sites.

Introduction

The USACE operates several dams in the Columbia River 

Basin, which encompasses 259,000 square miles of the Pacific 

Northwest. These dams are multipurpose structures that fill 

regional needs for flood control, navigation, irrigation, recreation, hydropower production, fish and wildlife habitat, waterquality 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, increasing the 

concentration of total dissolved gas (TDG) downstream from 

the spillways. TDG conditions above 110% saturation have 

been shown to cause gas-bubble trauma in fish and adversely 

affect other aquatic organisms (U.S. Environmental Protection 

Agency, 1986). 

The USACE regulates spill and streamflow to minimize 

the production of excess TDG downstream from its dams, but 

there is also the goal of providing for fish passage with spilled 

water (rather than passage through the turbines). Consequently, 

the States of Oregon and Washington issue variances to the 

TDG water-quality standards during the summer. In order to 
2 Total Dissolved Gas and Water Temperature in the Lower Columbia River, Oregon and Washington, 2004

monitor compliance to these variances, the USACE oversees 

the collection of near real-time TDG and water-temperature 

data upstream and downstream from the Columbia River Basin 

dams in a network of fixed-station monitors. Data from these 

sites are available within about 4 hours of current time.

Background

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 survival in the lower Columbia River. The 

USGS, in cooperation with the Portland District of the USACE, 

has collected TDG and related data in the lower Columbia River 

every year, beginning in 1996. Current and historical TDG and 

water-temperature data can be found on the USGS website at 

http://oregon.usgs.gov/projs_dir/pn307.tdg/. Five reports that 

were published for water years 1996, 2000, 2001, 2002, 

and 2003 contained TDG data, quality-assurance data, and 

descriptions of the methods of data collection (Tanner and 

others, 1996; Tanner and Johnston, 2001; Tanner and Bragg, 

2001; Tanner and others, 2002; and Tanner and others, 2003). 

To provide suitable data for managing and modeling 

TDG in the lower Columbia River, hourly data for 2004 were 

reviewed relative to laboratory and field measurements made 

during instrument calibrations and daily intersite comparisons. 

A small fraction of the TDG data were deleted because they 

were not of suitable quality. The hourly data were stored 

in a USGS data base (Automated Data Processing System

—ADAPS); and in a USACE data base (at http://www.

nwd-wc.usace.army.mil/tmt/wcd/tdg/months). The USACE 

data base also includes hourly discharge and spill data. 

Purpose and Scope

The purpose of TDG monitoring in the lower Columbia 

River is to provide the USACE with (1) real-time data for managing streamflow and spill at its project dams and (2) reviewed 

TDG data to evaluate conditions in relation to water-quality 

standards and to provide a data base for modeling the effect 

of various management scenarios of streamflow and spill on 

TDG levels.

This report describes the TDG data and related qualityassurance data from the lower Columbia River at eight sites 

from the forebay of the John Day Dam (river mile [RM] 215.7) 

to Camas, Washington (RM 121.7) (fig. 1, table 1). Data for 

water year 2004 (October 1, 2003, to September 30, 2004) 

include hourly measurements of TDG pressure, barometric 

pressure, water temperature, and probe depth. Five of the sites 

(John Day navigation lock, John Day tailwater, The Dalles 

forebay, The Dalles tailwater, and Camas) were operated from 

February or March to September 2004, which is the usual time 

of spill from the dams. In 2004, the monitoring site upstream 

from John Day Dam was relocated to a site near the navigation 

lock. Two sites (Bonneville forebay and Warrendale) were 

operated year-round. The site, Columbia River at Cascade 

Island, was installed temporarily to assess TDG levels directly 

in the tailwater of Bonneville Dam. Data from Columbia River 

at Cascade Island were not used for management purposes, 

and the site operated only periodically in 2004 due to failure 

of the probe enclosure. 

Acknowledgments

The authors acknowledge the aid and funding support of 

the U.S. Army Corps of Engineers. Our special thanks goes to 

James L. Britton (USACE) for technical and logistical support 

of the project. The authors also acknowledge Amy Brooks 

(USGS) for preparing summaries and analyses of data. 

Methods of Data Collection

Methods of data collection for TDG, barometric pressure, 

and water temperature are described in detail in Tanner and 

Johnston (2001). A summary of these methods follows: 

Instrumentation at each fixed station consisted of a Hydrolab 

water-quality probe, an electronic barometer, a power supply, 

and a Sutron Model 8200 data-collection platform (DCP). The 

instruments were powered by a 12-volt battery that was charged 

by a solar panel and/or a 120-volt alternating-current line. At 

the beginning of the monitoring season in March, a new TDG 

membrane was installed on each Hydrolab. Measurements 

(including probe depth) were made and logged every hour, 

and every 4 hours the DCP transmitted the most recent logged 

data to the Geostationary Operational Environmental Satellite 

(GOES) system (Jones and others, 1991). The data were automatically decoded and transferred to the USACE data base and 

to the USGS ADAPS data base. At one site, John Day tailwater, 

two TDG sensors were installed on the same Hydrolab to ensure 

that data were reliably collected at this important site.

The fixed-station monitors were calibrated every 2 weeks 

from March to September 2004, and every 3 weeks for the 

remainder of the year, at which time Warrendale and Bonneville 

forebay were the only sites in operation. The field calibration 

procedure was as follows: A Hydrolab (which was calibrated 

several days before the field trip and used as a secondary standard) was deployed alongside of the field Hydrolab to obtain 

check measurements of TDG and water temperature prior to 

removing the field Hydrolab (which had been deployed for 

2 or 3 weeks). The field Hydrolab was replaced with one that 

had been calibrated recently at the Oregon District Laboratory. 

Then, the secondary standard was used to check TDG and temperature measured by the newly deployed Hydrolab in the river. 

The electronic barometer at the fixed station was calibrated 

using a portable barometer that had been recently calibrated at 

the National Weather Service facility in northeast Portland.
Figure 1. Location of total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, water year 2004. 
4 Total Dissolved Gas and Water Temperature in the Lower Columbia River, Oregon and Washington, 2004

Table 1. Total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, water year 2004.

[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 are referenced by their abbreviated name or USACE site identifier in this report, °, degree, ’, minute, ”, second]

Map

reference

number

USACE

site

identifier

Columbia

River 

mile

USGS 

station number

USGS station name

(abbreviated station name) Latitude Longitude

Period 

of 

record

1 JDY 215.7 454314120413701 Columbia River at John Day navigation lock, 

Washington (John Day navigation lock)

45°43’14” 120°41’37” 03/25/04-

09/28/04

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

Washington (John Day tailwater)

45°42’49” 120°42’35” 03/09/04-

09/24/04

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

Washington (The Dalles forebay)

45°37’12” 121°07’12” 03/09/04-

09/29/04

4 TDDO 188.9 14105700 Columbia River at The Dalles, 

Oregon (The Dalles tailwater)

45°36 27” 121°10’20” 03/10/04-

09/29/04

5 BON 146.1 453845121562000 Columbia River at Bonneville Dam forebay, 

Washington (Bonneville forebay)

45°38’45” 121°56’20” Year-round

6 CCIW 145.9 453845121564001 Columbia River at Cascade Island, 

Washington (Cascade Island)

45°38’45” 121°56’40” Experimental 

for 2004 

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

Oregon (Warrendale)

45°36’30” 122°02’14” Year-round

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

Washington (Camas)

45°34’39” 122°22’39” 02/25/04-

09/22/04

The Hydrolab that was brought from the field after 2 to 3 

weeks of deployment was then calibrated in the Oregon District 

Laboratory. The integrity of the TDG membrane was checked, 

and the TDG sensor was calibrated at 0, 100, 200, and 300 mm 

Hg above atmospheric pressure to cover the expected range 

of TDG in the river (approximately 100, 113, 126, and 139% 

saturation, respectively).

During each field calibration, the minimum compensation 

depth was calculated to determine whether the Hydrolab was 

positioned at an appropriate depth to measure TDG. This minimum compensation depth, which was calculated according to 

Colt (1984, p. 104), is the depth above which degassing will 

occur, due to decreased hydrostatic pressure. To measure 

TDG accurately, the Hydrolabs were positioned during each 

calibration visit at a depth below the calculated minimum compensation depth, wherever possible.

Summary of Total-Dissolved-Gas 

Data Completeness and Quality

A summary of USGS TDG data completeness and quality 

for water year 2004 is shown in table 2. (The USACE satellite 

downlink was a parallel system, so the amount and quality of 

USACE data were similar). Data in table 2 were based on the 

total amount of hourly TDG data that could have been collected 

during the monitoring season. Any hour without TDG pressure 

data or barometric pressure data was counted as an hour of 

missing data for TDG in percent saturation, which is calculated 

as TDG pressure, in millimeters of mercury, multiplied by 

100%, divided by the barometric pressure, in millimeters of 

mercury. The fourth column in table 2 shows the percentage 

of data that was received in real time and passed qualityassurance checks. TDG data were considered to meet qualityassurance standards if they were within ±1% saturation of the 

expected value, based on calibration data and daily comparisons 

to ambient river conditions at adjacent sites. 

Table 2. Total-dissolved-gas data completeness and quality, 

lower Columbia River, Oregon and Washington, water year 2004. 

[Results are based on the U.S. Geological Survey (USGS) data base; 

TDG, total dissolved gas]

Station name

Planned 

monitoring 

in hours

Number 

of 

missing 

hourly values

Percentage of 

real-time TDG 

data 

passing qualitycontrol checks 

John Day 

navigation lock 4,485 93 97.9

John Day tailwater 4,799 23 99.5

The Dalles forebay 4,887 26 99.5

The Dalles tailwater 4,870 1 100.0

Bonneville forebay 8,784 26 99.7

Warrendale 8,784 78 99.1

Camas 5,038 119 97.6

Average -- -- 99.0
Quality-Assurance Data 5

At each station, at least 97.6% of the data was received 

in real time by the USGS downlink and met quality-control 

checks, with an overall average of 99.0% (table 2). The site at 

John Day navigation lock had 93 missing hourly values due 

mainly to problems in the power supply in April and June. The 

regulator controlling voltage input to the DCP was faulty, and 

the increased voltage level caused the DCP to trip the fail-safe 

software and turn itself off. The site at John Day tailwater had 

a failure of the probe-suspension system on June 16 and 17, 

which resulted in 21 hours of data that were not correct because 

the probe was not at a great enough depth. At The Dalles 

forebay and at Warrendale, the electronic barometers were 

randomly and periodically malfunctioning and reporting values 

for barometric pressure that were too large. The barometer at 

Warrendale was replaced with a new one in August, and the 

remainder of the barometers in the lower Columbia River network will be replaced in water year 2005. At Bonneville forebay, there was a problem in the wiring for DCP voltage supply, 

resulting in 23 hours of lost data on November 2 and 3, 2003. 

Data loss at the Camas site was due to blockage of the DCP 

antenna by a large ship March 23 and 24 and to broken TDG 

membranes in July and August.

Quality-Assurance Data 

Data collection for TDG, barometric pressure, and water 

temperature involved several quality-assurance procedures, 

including calibration of instruments in the field and in the laboratory, daily checks of the data, and data review for archiving. 

These methods were explained in detail in Tanner and Johnston 

(2001), and the results of the quality-assurance program for 

water year 2004 are presented in this section.

After field deployment for 2 to 3 weeks, the TDG sensors 

were calibrated in the laboratory. First, the unit was tested, with 

the membrane in place, for response to increased pressure. 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 first comparing 

the TDG sensor reading to barometric pressure (0 mm Hg added 

pressure, or 100% saturation). Using a certified digital pressure 

gage (primary standard), comparisons were also made at 

pressures of 100, 200, and 300 mm Hg above barometric 

pressure (approximately 113%, 126%, and 139% saturation, 

respectively). The accuracy of the TDG sensors was calculated 

as the difference between the expected reading and the TDG 

sensor reading (expected minus actual) for each of the four test 

conditions multiplied by 100%, and divided by the barometric 

pressure. As shown in figure 2, all of the sensor readings 

were within ± 0.5% saturation of the expected value after 2 to 

3 weeks of deployment.

The differences in barometric pressure, water temperature, 

and TDG between the secondary standard instruments and the 

fixed-station monitors after 2 to 3 weeks of field deployment 

were measured and recorded as part of the field inspection 

and calibration procedure. These differences, defined as the 

secondary standard value minus field instrument value, were 

used to compare and quantify the precision between the two 

independent instruments. For water temperature and TDG, the 

measurements were made in situ with the secondary standard 

(a recently calibrated Hydrolab) positioned alongside the field 

Hydrolab in the river. A portable barometer, calibrated every 

6 to 8 weeks, served as the secondary standard for barometric 

pressure. Figures 3, 4, and 5 illustrate the distribution of qualitycontrol data for each of the three parameters from seven field 

sites. 

Figure 2. Accuracy of total-dissolved-gas sensors after 

2 to 3 weeks of field deployment. 
6 Total Dissolved Gas and Water Temperature in the Lower Columbia River, Oregon and Washington, 2004

Figure 3. Difference between the secondary standard and the field barometers 

after 2 to 3 weeks of field deployment. 

Figure 4. Difference between the secondary standard and the field temperature 

instruments after 2 to 3 weeks of field deployment. 

Figure 5. Difference between the secondary standard and the field total-dissolvedgas instruments after 2 to 3 weeks of field deployment. 
Effects of Spill on Total Dissolved Gas 7

The comparisons of the portable barometer and the electronic field barometers are shown in figure 3. Most of the field 

values were within ±1 mm of the standard values, and there 

was only one difference greater than 2 mm Hg. This difference 

(-3 mm Hg) was recorded at John Day navigation lock 

(JDY) shortly before the portable barometer required recalibration. The secondary standard temperature sensor and the 

field temperature sensor results are presented in figure 4. 

All of the differences are within 0.1°C. 

The differences between the secondary standard TDG 

sensor and the field TDG sensors were calculated following 

equilibration of the secondary standard unit to the site conditions before removing the field unit. The side-by-side 

equilibrium was considered complete after a minimum of 

30 minutes when the TDG values for each sensor remained 

constant for 4 to 5 minutes. As shown in figure 5, most of the 

differences between the two TDG sensors were within ±1% 

saturation. One data point (+2% saturation) at The Dalles tailwater site was the result of a malfunctioning TDG sensor that 

was subsequently removed from use. Two instances of membrane rupture at the Camas site were not included with the plotted data as they do not reflect the performance of the TDG sensors. These ruptures resulted in a total of 108 hours of incorrect 

TDG data on July 18–19 and August 7–10. 

Effects of Spill on Total Dissolved Gas

Spill from each dam increased the level of total dissolved 

gas downstream. Spill data in this report are from the USACE 

website (http://www.nwd-wc.usace.army.mil/tmt/wcd/tdg/

months). Spill from John Day Dam occurred from April 12 

to August 31 (fig. 6). The spill from April 12 to June 20 was 

usually less than 150,000 ft3

/s (cubic feet per second) and usually occurred only between 7 a.m. and 7 p.m. for fish passage 

considerations. Figure 6 shows that TDG downstream from 

John Day Dam increased in response to spill from the dam, 

with the TDG level usually being less than 120% saturation. 

From June 21 to August 31, continuous spill from John Day 

dam varied from about 20,000 ft3

/s to about 70,000 ft3/s, and 

the TDG at the John Day tailwater site was always less than 

120% saturation.

Spill from The Dalles Dam (fig. 7) was almost continuous 

at levels generally between 30,000 and 120,000 ft3/s from 

April 12 to August 31. TDG levels at The Dalles tailwater site 

generally ranged from about 111% to 117% saturation during 

the period of spill.

At Bonneville Dam from April 12 to June 21, the spill generally was 75,000 ft3

/s during the daylight hours and between 

about 120,000 and 170,000 ft3

/s at night. During that time, the 

TDG at Warrendale exceeded 120% saturation on 1 day only. 

On June 21, 2004, the TDG at the Warrendale site peaked at 

values slightly greater than 120% saturation for several 

hours (fig. 8). After June 22, Bonneville spills were generally 

decreased until the spill ended on August 31.

TDG at the experimental site, Columbia River at 

Cascade Island, showed a response to spill from Bonneville 

Dam that was different from that at the Warrendale site. The 

difference in response to spill was most evident from the beginning of the 100,000 ft3/s spill on April 21 until June 3, when 

the probe housing (a steel pipe) at Cascade Island broke 

and the proper probe depth could not be maintained. The 

Cascade Island site is about 0.2 miles downstream of Bonneville Dam, directly in the spill channel, so the response of 

TDG to spill (fig. 9) showed a direct correlation, with spill 

of 75,000 ft3/s causing about 113–117% TDG saturation, and 

spill of 160,000 ft3/s causing an increased TDG saturation up 

to about 119–121%. The Warrendale site is about 5.5 miles 

below the Cascade Island site, and is affected by degassing of 

the river as well as dilution of supersaturated water by powerhouse flows. Examination of the relationship between spill 

from Bonneville Dam and TDG at Warrendale during the same 

time period (fig. 10) showed that the response to spill was not 

clear cut. A spill of 75,000 ft3

/s resulted in TDG of 109–118% 

saturation, and a spill of 160,000 ft3/s resulted in a slight 

increase in TDG, to the range of about 110–119% saturation. 

As mentioned above, valid data were available only for 

part of the season for the Columbia River at Cascade Island. 

The site was installed on April 6, 2004, and the probe remained 

positioned in the spill channel at a depth of about 30 to 35 feet 

until June 3. While trying to retrieve the probe during a routine 

field calibration on June 3, the probe became lodged part way 

up the steel pipe housing the probe. It was later discovered that 

the steel pipe had broken and that several 20-foot sections of the 

pipe had dropped to the bottom of the river. After June 3, 

several attempts were made to deploy the probe at a reasonable 

depth, but it was not possible to do so, and the TDG data after 

June 3 were determined to be of poor quality. As a result, the 

TDG data from the Cascade Island site for dates following 

June 3 were deleted from the public portion of the USGS data 

base. (The deleted data were retained as raw values in the internal USGS data base.)

The forebay sites, John Day navigation lock, The Dalles 

forebay, Bonneville forebay, and Camas, were located immediately upstream of a dam, except for Camas, which is located 

24.4 miles downstream of Bonneville Dam. As a result, the 

forebay sites were expected to have lower levels of total 

dissolved gas. At John Day forebay (fig. 11), TDG was less 

than 115% saturation for the whole monitoring season. At The 

Dalles forebay (fig. 12), TDG was periodically above 115% 

saturation for short periods until June 22, which was the day 

after spill decreased at John Day Dam (see fig. 6). At Bonneville forebay (fig. 13), TDG was larger than 115% a few times 

before late June. Finally, at Camas (fig 14), TDG was greater 

than 115% on several occasions, mainly prior to late June. As 

documented in the past (Tanner and Bragg, 2001), some of the 

daily increases in TDG at Camas may be due to the production 

of oxygen by aquatic plants and to temperature variations. 
Figure 6. Total dissolved gas downstream of John Day Dam and spill from John Day Dam, April 10 to September 4, 2004.
Figure 7. Total dissolved gas downstream of The Dalles Dam and spill from The Dalles Dam, April 10 to September 4, 2004. 
Figure 8. Total dissolved gas downstream of Bonneville Dam at Warrendale and spill from Bonneville Dam, April 10 to September 4, 2004. 
Effects of Spill on Total Dissolved Gas 11

Figure 9. Response of total dissolved gas at Cascade Island to spill from Bonneville Dam, April 21 to June 3, 2004. 

Figure 10. Response of total dissolved gas at Warrendale to spill from Bonneville Dam, April 21 to June 3, 2004. 
Figure 11. Total dissolved gas upstream of John Day Dam, April 10 to September 4, 2004. Figure 12. Total dissolved gas upstream of the Dalles Dam, April 10 to September 4, 2004. 
Figure 13. Total dissolved gas upstream of Bonneville Dam, April 10 to September 4, 2004. Figure 14. Total dissolved gas at Camas, April 10 to September 4, 2004. 
14 Total Dissolved Gas and Water Temperature in the Lower Columbia River, Oregon and Washington, 2004

Comparison of Total Dissolved Gas 

and Temperature to Standards

In 2004, there were variances or exceptions to the waterquality standard for total dissolved gas of 110% saturation. 

These variances were to allow spill for fish passage at dams on 

the Columbia River. The State of Oregon granted a multiyear 

variance, covering 2003 to 2007 (Stephanie Hallock, Oregon 

Environmental Quality Commission, written commun., 2003). 

The State of Washington provided for fish passage in its water 

quality standards consistent with approved gas abatement plans 

(Washington Administrative Code 173-201A-200(1)(f), http://

www.leg.wa.gov/wac/index.cfm?fuseaction=chapterdigest&

chapter=173-201A, accessed October 1, 2004). From April 1 to 

August 31, 2004, the USACE was granted variances of 115% 

for forebay sites (John Day navigation lock, The Dalles forebay, 

Bonneville forebay, and Camas) and 120% for tailwater sites 

directly downstream from dams (John Day tailwater, The 

Dalles tailwater, and Warrendale). The 115% and 120% 

variances were exceeded if the average of the highest 12 hourly 

values in 1 day (1 a.m. to 12 p.m. [midnight]) was larger 

than the numerical standard. A separate variance of 125% was 

in place for all sites for the highest 2-hour average (Oregon 

Environmental Quality Commission, written commun., 2003), 

or the highest 1-hour average (Washington Department of 

Ecology, written commun., 2004). Although the Camas site 

is not located at the forebay of a dam, it is 24.4 miles downstream from Bonneville Dam, and it is regulated as a forebay 

site.

There was no water-quality variance in place for the site 

at Cascade Island. This was a new, experimental site with the 

purpose of collecting data directly in the spillway of Bonneville 

dam. The USACE did not use total-dissolved-gas data from 

the Cascade Island site to regulate spill or flow on the Columbia 

River.

At three of the seven monitoring stations, the Oregon and 

Washington variance for TDG was exceeded at some time during water year 2004 (table 3). All sites in exceedance of a variance were forebay sites. The site with the most exceedances was 

Camas, which exceeded the 115% variance six times, followed 

by The Dalles forebay, which exceeded the 115% variance 

three times. At Bonneville forebay, the variance of 115% was 

exceeded one time in 2004.

The distribution of TDG values for the spill season 

(April 12 to August 31, 2004) is shown in figure 15. Even 

though the median TDG values for the tailwater stations 

decreased slightly going downstream (from JHAW to TDDO 

to WRNO), the forebay sites showed a corresponding increase 

in the median (from JDY to TDA to BON to CWMW). The 

situation with the forebay sites probably reflects the river’s 

inability to degas to a “baseline” level downstream of each dam, 

before another dam is encountered to again cause an increase in 

TDG.

Water temperature standards that apply to the lower 

Columbia River are complex and depend on the effects of 

anthropogenic activities and the locations of salmonid rearing, 

spawning, and egg incubation areas. According to the State of 

Oregon water-quality standard, the 7-day-average maximum 

temperature of the lower Columbia River should not exceed 

20°C (Oregon Department of Environmental Quality, 

Temperature Criteria Rules OAR 340-041-0028, modified 

05/20/2004, at http://www.deq.state.or.us/wq/wqrules/Div41/

OAR340Div41.pdf, accessed October 13, 2004). Washington 

State regulations state that the water temperature in the 

Columbia River shall not exceed a 1-day maximum of 20.0°C 

due to human activities (Water Quality Standards for Surface 

Waters of the State of Washington, Chapter 173-201A 

WAC, last update July 1, 2003, http://www.ecy.wa.gov/pubs/

wac173201a.pdf, accessed October 13, 2004). 

Table 3. Exceedances of States of Oregon and Washington 

water-quality variances for total dissolved gas, lower Columbia River, 

Oregon and Washington, water year 2004. 

[Note: Table is based on the U.S. Geological Survey (USGS) data base.]

Station name

Numerical variance 

for total dissolved 

gas, in percent

saturation

Number of days 

in exceedance 

of variance

John Day navigation lock 115 0

John Day tailwater 120 0

The Dalles forebay 115 3

The Dalles tailwater 120 0

Bonneville forebay 115 1

Warrendale 120 0

Camas 115 6
Comparison of Total Dissolved Gas and Temperature to Standards 15

Figure 15. Distributions of hourly total-dissolved-gas data and exceedances of Oregon and Washington water-quality variances, 

April 12, 2004 to August 31, 2004. (Refer to table 1 for site identifiers.) 

Water temperatures upstream and downstream from John 

Day Dam were equal to or larger than 20.0°C continuously from 

July 11 to September 14 (fig. 16). The TDG monitoring site at 

the John Day navigation lock (at river mile 215.7) was new for 

water year 2004. The site was relocated because the previous 

site upstream from the John Day Dam, John Day forebay (at 

river mile 215.6), showed temperature increases caused by 

heating of the pool’s surface. These temperature increases were 

not representative of the whole river, and contributed to 

increased TDG levels that also may not have been representative. Examples of these heating events are shown in figure 17, 

which shows 2003 water temperature data at the old John Day 

forebay site plotted hour-by-hour against the water temperature 

at John Day tailwater. The John Day tailwater site probably represented the overall temperature of the river, whereas the John 

Day forebay site did not, since it was in a pool of stagnant, 

unmoving water. The data in figure 17, from March 25 to 

September 15, 2003, show that for many hourly data points, the 

water above John Day Dam was 1 or 2°C warmer than that of 

the tailwater. 

The new site, at the John Day navigation lock, is about 0.1 

mile upstream of the John Day Dam (as contrasted to the old 

site, which was located directly on the upstream face of the 

dam). Additionally, the probe at the new site was installed at a 

depth of about 32 feet, whereas the probe depth at the old site 

was about 18 feet. These two factors were intended to decrease 

the influence of surface heating of water near the dam. As 

the data in figure 18 show, in 2004 at the new site at John Day 

navigation lock the temperature each hour was very close to 

the temperature for the same time at the John Day tailwater site. 
16 Total Dissolved Gas and Water Temperature in the Lower Columbia River, Oregon and Washington, 2004

Figure 16. Water temperature upstream and downstream of John Day Dam for summer 2004.

The difference between the two sites was almost always less 

than 1°C. This indicates that the new site represented the temperature of the river better than the site that was previously 

upstream of the John Day Dam.

Water temperatures upstream and downstream from The 

Dalles Dam were equal to or larger than 20.0°C continuously 

from July 12 to September 12 (fig. 19). The water temperature 

at The Dalles forebay was approximately equal to the temperature at The Dalles tailwater, indicating well-mixed conditions in 

the forebay.

Water temperatures upstream and downstream from 

Bonneville Dam are shown in figure 20. Temperatures at 

Bonneville forebay were equal to or larger than 20.0°C continuously from July 13 to September 3. The water temperature at 

Warrendale (the tailwater site) was approximately equal to 

the temperature at Bonneville forebay, but water temperatures 

were more variable at Warrendale, sometimes differing from 

the forebay by as much as 0.4°C.

At the Camas site, the water temperature was 20.0°C 

or larger continuously from July 13 to September 4 (fig. 21). 

As in the past, there was a distinct daily cycle to temperature, 

with an amplitude of about 1°C, a minimum occurring at about 

0900 hours, and a maximum at about 1900 hours. 
Comparison of Total Dissolved Gas and Temperature to Standards 17

Figure 17. Comparison of hourly water temperature at John Day forebay and John Day tailwater, March 25, 2003 

to September 15, 2003.

Figure 18. Comparison of hourly water temperature at John Day navigation lock and John Day tailwater, March 25, 2004 

to September 15, 2004
18 Total Dissolved Gas and Water Temperature in the Lower Columbia River, Oregon and Washington, 2004

Figure 19. Water temperature upstream and downstream of The Dalles Dam for summer 2004. 

Figure 20. Water temperature upstream and downstream of Bonneville Dam for summer 2004. 
References Cited 19

Figure 21. Water temperature at Camas for summer 2004. 

References Cited

Colt, J., 1984. Computation of dissolved gas concentrations 

in water as functions of temperature, salinity, and pressure: 

American Fisheries Society Special Publication 14, 154 p.

Jones, J.C., Tracey, D.C., and Sorensen, F.W., eds., 1991, 

Operating manual for the U.S. Geological Survey’s datacollection system with the Geostationary Operational 

Environmental Satellite: U.S. Geological Survey OpenFile Report 91–99, 237 p.

Tanner, D.Q., and Bragg, H.M., 2001, Quality-assurance 

data, comparison to water-quality standards, and site considerations for total dissolved gas and water temperature, 

lower Columbia River, Oregon and Washington, 2001: 

U.S. Geological Survey Water-Resources Investigations 

Report 01–4273, 14 p.

Tanner, D.Q., Bragg, H.M., and Johnston, M.W., 2003, Total 

dissolved gas and water temperature in the lower Columbia 

River, Oregon and Washington, 2003: Quality-assurance 

data and comparison to water-quality standards, U.S. Geological Survey Water-Resources Investigations Report 

03–4306, 18 p.

Tanner, D.Q., Harrison, H.E., and McKenzie, S.W., 1996, Total 

dissolved gas, barometric pressure, and water temperature 

data, lower Columbia River, Oregon and Washington, 1996: 

U.S. Geological Survey Open-File Report 96–662A, 85 p.

Tanner, D.Q., and Johnston, M.W., 2001, Data-collection 

methods, quality-assurance data, and site considerations for 

total dissolved gas monitoring, lower Columbia River, 

Oregon and Washington, 2000: U.S. Geological Survey 

Water-Resources Investigations Report 01–4005, 19 p.

Tanner, D.Q., Johnston, M.W., and Bragg, H.M., Total dissolved gas and water temperature in the lower Columbia 

River, Oregon and Washington, 2002: Quality-assurance 

data and comparison to water-quality standards, U.S. Geological Survey Water-Resources Investigations Report 

02–4283, 12 p.

U.S. Environmental Protection Agency, 1986, Quality criteria 

for water: Washington, D.C., EPA-440-5-86-001.
20 Total Dissolved Gas and Water Temperature in the Lower Columbia River, Oregon and Washington, 2004

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