Cover photographs: 

Upper left: Spill from Bonneville Dam on the Columbia River, from U.S. Army Corps of Engineers files. 

Middle: Map of fixed monitoring stations. 

Bottom right: Salmon in the Bonneville fish ladder, from U.S. Army Corps of Engineers files.
U.S. Department of the Interior

U.S. Geological Survey

Total Dissolved Gas and Water Temperature in the 

Lower Columbia River, Oregon and Washington, 

2003: Quality-Assurance Data and Comparison to 

Water-Quality Standards

By DWIGHT Q. TANNER, HEATHER M. BRAGG, and MATTHEW W. JOHNSTON

Water-Resources Investigations Report 03–4306

Prepared in cooperation with the 

U.S. ARMY CORPS OF ENGINEERS

Portland Oregon: 2003
U. S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director

The 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.

For additional information: Copies of this report may be purchased from:

District Chief U.S. Geological Survey 

U.S. Geological Survey Branch of Information Services 

10615 S.E. Cherry Blossom Dr. Box 25286 

Portland, OR 97216-3103 Denver Federal Center 

E-mail: info-or@usgs.gov Denver, CO 80225-0286 

Internet: http://or.water.usgs.gov Telephone: 1-888-ASK USGS

Suggested citation: 

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.
III

CONTENTS

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

Introduction.................................................................................................................................................................................1

Background .......................................................................................................................................................................2

Purpose and Scope ............................................................................................................................................................2

Acknowledgments.............................................................................................................................................................2

Methods of Data Collection ........................................................................................................................................................4

Summary of Total-Dissolved-Gas Data Completeness and Quality...........................................................................................5

Quality-Assurance Data ..............................................................................................................................................................5

Effects of Spill on Total Dissolved Gas......................................................................................................................................6

Comparison of Total Dissolved Gas and Temperature to Standards ..........................................................................................9

References Cited .......................................................................................................................................................................18

FIGURES

1. Map show location of total-dissolved-gas fixed stations, lower Columbia River, 

Oregon and Washington, water year 2003....................................................................................................................3

2.–15. Graphs showing:

2. Accuracy of total-dissolved-gas sensors after 2 to 3 weeks of field deployment .........................................................5

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

of field deployment .......................................................................................................................................................7

4. Difference between the secondary standard and the field temperature instruments after 

2 to 3 weeks of field deployment ..................................................................................................................................7

5. Difference between the secondary standard and the field total-dissolved-gas instruments 

after 2 to 3 weeks of field deployment..........................................................................................................................7

6. Total dissolved gas downstream of John Day Dam and spill from John Day Dam, 

April 9 to September 4, 2003 ........................................................................................................................................8

7. Total dissolved gas and discharge downstream of John Day Dam, May 26 to May 30, 2003 .....................................9

8. Total dissolved gas downstream of The Dalles Dam and spill from The Dalles Dam, 

April 9 to September 4, 2003 ......................................................................................................................................10

9. Total dissolved gas downstream of Bonneville Dam at Warrendale and spill from 

Bonneville Dam, April 9 to September 4, 2003..........................................................................................................11

10. Total dissolved gas at Warrendale and at Camas, May 25 to June 2, 2003................................................................12

11. Distributions of hourly total-dissolved-gas data and exceedances of Oregon and 

Washington water-quality variances, April 14 to August 31, 2003............................................................................13

12. Water temperature upstream and downstream of John Day Dam for summer 2003..................................................14

13. Water temperature upstream and downstream of The Dalles Dam for summer 2003................................................15

14. Water temperature upstream and downstream of Bonneville Dam for summer 2003................................................16

15. Water temperature at Camas for summer 2003 ..........................................................................................................17

TABLES

1. Total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, water year 2003 ......................4

2 Total-dissolved-gas data completeness and quality, lower Columbia River, water year 2003 ...................................5

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

lower Columbia River, Oregon and Washington, water year 2003 ............................................................................12

CONVERSION FACTORS

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

°F = (1.8 × °C) + 32

Multiply By To obtain

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)
THIS PAGE INTENTIONALLY BLANK
1

Total Dissolved Gas and Water Temperature in the 

Lower Columbia River, Oregon and Washington, 

2003: 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 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, collected totaldissolved-gas and water-temperature data at 

seven sites on the lower Columbia River in 2003. 

Significant findings from the data include:

• For the seven monitoring sites in water year 

2003, an average of 98.9% of the total-dissolvedgas 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.

• Most field checks of total-dissolved-gas 

sensors with a secondary standard were within 

plus or minus 1% saturation. Field checks of 

barometric pressure and water temperature were 

usually within plus or minus 1 millimeter of 

mercury and plus or minus 0.1 degree Celsius, 

respectively.

• The variances to the States of Oregon and 

Washington water-quality standards for total dissolved gas were exceeded at six of the seven monitoring sites. The sites at Camas and Bonneville 

forebay had the most days exceeding the variance 

of 115% saturation. The forebay exceedances may 

have been the result of the cumulative effects of 

supersaturated water moving downstream through 

the lower Columbia River. Apparently, the levels 

of total dissolved gas did not decrease rapidly 

enough downstream from the dams before reaching the next site.

• From mid-July to mid-September, water 

temperatures were usually above 20 degrees 

Celsius at each of the seven lower Columbia River 

sites. According to the Oregon water-quality 

standard, when the temperature of the lower 

Columbia River exceeds 20 degrees Celsius, no 

measurable temperature increase resulting from 

anthropogenic activities is allowed. Transient 

increases of about 1 degree Celsius were noted 

at the John Day forebay site, due to localized solar 

heating.

INTRODUCTION

The U.S. Army Corps of Engineers (USACE) 

operates several dams in the Columbia River Basin, 

which encompasses 259,000 square miles of the 
2

Pacific Northwest. These dams are multipurpose 

facilities that fill 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, 

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 months. 

In order to monitor compliance with 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 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 

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/. Reports that were published in 

1996, 2001, and 2002 contained TDG data, qualityassurance data, and descriptions of the methods of data 

collection for water years 1996, 2000, 2001, and 2002 

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

Tanner and Bragg, 2001; and Tanner and others, 2002, 

respectively). 

To provide suitable data for managing and modeling TDG in the lower Columbia River, real-time 

hourly data for 2003 were reviewed relative to laboratory and field measurements made during instrument 

calibration and daily intersite comparison. Some 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 

database also includes 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 

quality-assurance data from the lower Columbia River 

at seven sites from the forebay of the John Day Dam 

(river mile [RM] 215.6) to Camas, Washington 

(RM 121.7), (fig. 1, table 1). It is similar in format 

and content to the previous reports presenting TDG 

data for the lower Columbia River, mentioned above. 

Data for water year 2003 (October 1, 2002, to 

September 30, 2003) included hourly measurements 

of TDG pressure, barometric pressure, water temperature, and probe depth. Five of the sites were operated 

from March to September 2003, which is the usual 

time of spill from the dams. The sites at the forebay 

and tailwater of The Dalles Dam also were operated 

during October and part of November 2002 to evaluate 

the effects of spill tests during those times. Two sites 

(Bonneville forebay and Warrendale) were operated 

year-round.

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 assistance in data collection and for preparing summaries and analyses of data, and Steve Sobieszczyk 

for producing the map of the monitoring stations on 

the cover.
3

Figure 1. Location of total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, water year 2003. 
4

Table 1. Total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, water year 2003

[Map reference number refers to figure 1; U.S. Army Corps of Engineers, USACE; 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 JDA 215.6 454257120413000 Columbia River at John Day Dam forebay, 

Washington (John Day forebay)

45°42’57” 120°41’30” 03/20/03-

09/16/03

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

Washington (John Day tailwater)

45°42’49” 120°42’35” 03/20/03-

09/16/03

3 TDA 192.6 453712121071200 Columbia River at The Dalles Dam forebay, Washington (The Dalles forebay)45°37’12” 121°07’12” 10/01/02-

11/06/02 and

03/20/03-

09/17/03

4 TDDO 188.9 14105700 Columbia River at The Dalles, 

Oregon (The Dalles tailwater)

45°36’27” 121°10’20” 10/01/02-

11/06/02 and

03/21/03-

09/17/03

5 BON 146.1 453845121562000 Columbia River at Bonneville Dam forebay, Washington (Bonneville forebay)45°38’45” 121°56’20” Year-round

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

Oregon (Warrendale)

45°36’30” 122°02’14” Year-round

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

Washington (Camas)

45°34’39” 122°22’39” 03/10/03-

09/18/03

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, a 

Common Sensing, Inc. electronic barometer, a power 

supply, and a Sutron Model 8200 data-collection 

platform (DCP). The barometer, probe, and DCP were 

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

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

Measurements were made 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, 2003, 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 recently calibrated Hydrolab (which 

was 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 for calibration. Then the 

field Hydrolab was replaced with one that had been 

recently calibrated 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 office located in northeast 

Portland.

The Hydrolab that was brought in 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 (millimeters of mercury) above atmospheric pressure to 

cover the expected range of TDG pressure 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)
5

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 2003 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, divided by the 

barometric pressure, in millimeters of mercury, multiplied by 100%. The fourth column in table 2 shows the 

percentage of data that was received in real time and 

passed quality-assurance checks. TDG data were 

considered to meet quality-assurance standards if 

they were within plus or minus 1% saturation of the 

expected value, based on calibration data and daily 

checks of ambient river conditions at adjacent sites. 

At each station, at least 96.6% of the data was 

received in real time by the USGS downlink and met 

quality-control checks, with an overall average of 

98.9% (table 2). Most missing hourly values were due 

to malfunction of the data collection platform (DCP).

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

lower Columbia River, water year 2003

[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 forebay 4,321 146 96.6

John Day tailwater 4,321 1 100.0

The Dalles forebay 5,211 4 99.9

The Dalles tailwater 5,194 47 99.1

Bonneville forebay 8,760 94 98.9

Warrendale 8,760 93 98.9

Camas 4,630 65 98.6

Average -- -- 98.9

The lowest percentage for a station was 96.6% at John 

Day forebay, where data loss occurred in July and 

August due to a faulty DCP.

QUALITY-ASSURANCE DATA

Data collection for TDG, barometric pressure 

and water temperature involved several quality-control 

checks, 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 2003 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 ambient barometric pressure (100% saturation). Using a certified 

digital pressure gage (primary standard), comparisons 

also were made at added 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, divided by the barometric pressure, and multiplied by 100%. As shown 

in figure 2, all of the sensor readings were within 0.5% 

saturation of the expected value. 

Figure 2. Accuracy of total-dissolved-gas sensors after 2 to 3 

weeks of field deployment. (There were 136 tests at each pressure.) 
6

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 the 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. An aneroid barometer, calibrated every 

4 to 6 weeks, served as the secondary standard for 

barometric pressure. Figures 3, 4, and 5 illustrate 

the distribution of quality-control data for each of 

the three parameters from all seven field sites. 

The comparisons of the aneroid barometer and the 

electronic field barometers are shown in figure 3. Most 

of the field values are within plus or minus 1 mm of the 

standard values. The greatest difference (+4 mm Hg) 

was recorded at Bonneville forebay when a faulty 

DCP was replaced, requiring recalibration of the field 

barometer. The secondary standard temperature sensor 

and the field temperature sensor results are presented 

in figure 4. All of the differences are within 0.2°C 

(degrees Celsius), with most falling 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 and 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 

plus or minus 1% saturation. The two extreme outlying data points (-19% and -24% saturation) at the 

Camas site were both the result of a ruptured membrane. In both cases, the Hydrolabs were removed 

from the site within a day of the malfunction. The 

other two outliers at Camas (+3.0% and +3.5% 

saturation) were the results of a single malfunctioning 

TDG sensor. Erratic TDG values were noted at Camas 

during one of these field inspections. The sensor and 

membrane, however, successfully passed the subsequent lab calibration, and the Hydrolab was redeployed. Similar erratic values were noted during the 

next field check and the unit was removed from service and returned to the manufacturer for repair.

During one field inspection at the John Day 

tailwater site, the TDG values of the two field sensors 

and the secondary standard were increasing during the 

initial part of the field calibration procedure. Due to 

differences in the response times of each TDG sensor, 

it was difficult to accurately determine the difference 

between the secondary standard and the two field 

sensors. Although both field sensors had readings of 

2.0% saturation higher than the secondary standard, 

their accuracy in the subsequent lab calibration was 

within 0.3% saturation of the primary standard (certified pressure gage). 

Similarly, the outlying data point at the John Day 

forebay site (+2.0% saturation) was the result of slow 

equilibration of the secondary standard during the initial 

field check. After 30 minutes, the difference between the 

field sensor and the secondary standard was 2.0% saturation. The secondary standard and the newly deployed 

Hydrolab equilibrated 45 minutes later with a difference 

of less than 0.7% saturation, confirming that the earlier 

problem at the site was incomplete equilibration. 

EFFECTS OF SPILL ON TOTAL DISSOLVED GAS

Spill from each dam increased the level of total 

dissolved gas downstream from the dam. Spill 

data are from the USACE Website (http://www.nwdwc.usace.army.mil/tmt/wcd/tdg/months). Spill 

from John Day Dam occurred on April 10 and from 

April 14 to August 31 (fig. 6). The spill was usually 

less than 170,000 ft3

/s (cubic feet per second) and 

usually occurred only between 7:00 p.m. and 7:00 a.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. For several 

hours on late May 27 and early May 28, the TDG 

was larger than 120%, but the spill was not unusually 

large (fig. 6). There was an increase in total discharge 

through the dam (which includes spill) for several 

hours late on May 27 (fig. 7). This increase from about 

300,000 ft3

/s to more than 400,000 ft3/s occurred just 

before the TDG increased to above 120% saturation 

(fig. 7). At the John Day Dam, the spillway and the 

tailwater TDG monitoring station are located on the 

north side of the dam, and the powerhouse is located 

on the south side. The increased flow from the powerhouse probably constrained the spill plume towards 

the north (Washington State) shore of the Columbia 

River, resulting in a higher measured TDG at the tailwater monitoring site for a constant amount of spill.
7

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

(Refer to table 1 for site identifiers.)

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

(Refer to table 1 for site identifiers.)

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

(Refer to table 1 for site identifiers.)
8

Figure 6. Total dissolved gas downstream of John Day Dam and spill from John Day Dam, April 9 to September 4, 2003. 
9

Figure 7. Total dissolved gas and discharge downstream of 

John Day Dam, May 26 to May 30, 2003. 

Spill from The Dalles Dam (fig. 8) was almost 

continuous from April 14 to August 31. The spill 

generally was between 40,000 and 120,000 ft3/s, 

resulting in a TDG level of 110 to 120% below the 

dam. 

From April 14 to August 31, continuous spill 

from Bonneville Dam typically ranged from about 

75,000 ft3/s to 150,000 ft3/s, causing TDG levels at 

Warrendale (which is about 6 miles downstream from 

Bonneville dam) to rise to about 110–120% of saturation (fig. 9). On one occasion, May 29, 2003,

the TDG at the Warrendale site peaked at a value 

of 129% saturation and then quickly receded, even 

though available spill data did not show a significant 

increase (fig. 9). Closer examination of this event 

showed that there also was a peak in TDG of 126% 

saturation 13 hours later at the Camas site, which is 

about 19 miles downstream from the Warrendale site 

(fig. 10). The cause for these peaks was an unintentional increase in spill at Bonneville Dam, which was 

not documented in the spill data (Mike Schneider, 

USACE, written commun., 2003). From March 10 

to March 12, 2003, spill from Bonneville Dam was 

about 50,000 ft3/s to flush released hatchery fish to the 

ocean. During this spill, the TDG at the Warrendale 

site increased to about 105%.

COMPARISON OF TOTAL DISSOLVED GAS 

AND TEMPERATURE TO STANDARDS

In 2003, the States of Oregon and Washington 

granted the USACE variances to the water-quality 

standard for TDG of 110% saturation. The variance 

granted by the State of Oregon was a multiyear 

variance, covering 2003 to 2007 (Oregon Environmental Quality Commission, written commun., 2003) 

and the State of Washington granted a single-year 

variance for 2003 (Washington Department of 

Ecology, written commun., 2003). From April 1 to 

August 31, 2003, the USACE was granted variances 

of 115% for forebay sites (John Day forebay, 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 (1:00 a.m. to 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., 2003). Although the Camas site is not located at 

the forebay of a dam, it is more than 24 miles downstream from Bonneville Dam, and it is regulated as a 

forebay site.

At six of the seven monitoring stations, the 

Oregon and Washington variance for TDG was 

exceeded at some time during water year 2003 

(table 3). There were no exceedances at the John 

Day tailwater site. The one exceedance of the 120% 

variance at Warrendale occurred on May 29, 2003,

and was a result of the unplanned spill mentioned 

above. There also was an exceedance of the 125% 

variance at Warrendale on this occasion.
10

Figure 8. Total dissolved gas downstream of The Dalles Dam and spill from The Dalles Dam, April 9 to September 4, 2003. 
11

Figure 9. Total dissolved gas downstream of Bonneville Dam at Warrendale and spill from Bonneville Dam, April 9 to September 4, 2003. 
12

Figure 10. Total dissolved gas at Warrendale and at Camas, May 25 to June 2, 2003. 

The site with the most exceedances was Camas, 

which exceeded the 115% variance 23 times, followed 

by Bonneville forebay, which exceeded the 115% 

variance 17 times. Overall, there were fewer exceedances at the tailwater sites, which had the larger 

variance of 120%. Available data indicate that the 

forebay exceedances may have been the result of the 

Table 3. Exceedances of States of Oregon and Washington 

water-quality variances for total dissolved gas, lower Columbia 

River, Oregon and Washington, water year 2003

[Note: At Warrendale, there was also an exceedance of the 125% variance 

for the highest 1- or 2-hour average. 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 forebay 115 10

John Day tailwater 120 0

The Dalles forebay 115 9

The Dalles tailwater 120 3

Bonneville forebay 115 17

Warrendale 120 1

Camas 115 23

cumulative effects of significant spill throughout the 

lower Columbia River. The TDG levels were often 

near 120% at the tailwater sites (figs. 6, 8, and 9), and 

apparently the TDG often did not sufficiently degas 

to meet the 115% variance at the next downstream 

forebay sites. There was an increase in the median 

TDG concentration at the forebay sites moving downstream from John Day forebay to The Dalles forebay 

to Bonneville to Camas, indicating this cumulative 

effect (fig. 11).

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, when the temperature of 

the Columbia River from RM 309 to the mouth 

exceeds 20°C, no measurable surface-water 

temperature increase resulting from anthropogenic 

activities is allowed (Oregon Department of 

Environmental Quality Website at http://www.deq.

state.or.us/wq/wqrules/, accessed November 5, 2003). 
13

Figure 11. Distributions of hourly total-dissolved-gas data and exceedances of Oregon and Washington water-quality variances, 

April 14 to August 31, 2003. (Refer to table 1 for site identifiers.) 

The Columbia River from RM 309 to the mouth 

includes all seven of the lower Columbia River TDG 

fixed stations that are considered in this report. Water 

temperatures upstream and downstream from John Day 

Dam were equal to or larger than 20.0°C continuously 

from July 13 to September 16 (fig. 12). On several 

afternoons during this period, the water temperature at 

the forebay site transiently increased to about 1°C 

higher than the tailwater site. This phenomenon has 

been described in the past (Tanner and Johnston, 2001, 

p. 19; and Tanner and Bragg, 2001, p. 11), and it has 

been attributed to localized heating of the stagnant 

surface layer of water near the monitoring station, 

which is on the upstream face of the dam. Recent data 

collected by the USACE show that warmer water is 

stratified over cooler water during warm summer days 

(Joe Carroll, USACE, oral commun., October 16, 

2003). This stratification extends to at least 1 mile 

upstream from 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 14 to September 16 

(fig. 13). The water temperature at The Dalles forebay 

was approximately equal to the temperature at The 

Dalles tailwater, indicating well-mixed conditions in 

the forebay, as contrasted to the John Day forebay.

Water temperatures upstream and downstream 

from Bonneville Dam are shown in figure 14. 

Temperatures at Bonneville forebay were equal to 

or larger than 20.0°C continuously from July 13 to 

September 13 (fig. 14). 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, 

often differing by as much as 0.2°C, and especially 

after spill ended on September 1 (fig. 14).

At the Camas site, the water temperature was 

20.0°C or larger for most of each day from July 11 

to September 13 (fig. 15). During the summer, there 

was a distinct diurnal or daily cycle to temperature, 

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

0900 hours, and a maximum at about 1900 hours. 

This is the same pattern found in the past, and perhaps 

indicates the characteristics of the Columbia River 

where it is relatively unaffected by the dams. 
14

Figure 12. Water temperature upstream and downstream of John Day Dam for summer 2003. 
15

Figure 13. Water temperature upstream and downstream of The Dalles Dam for summer 2003. 
16

Figure 14. Water temperature upstream and downstream of Bonneville Dam for summer 2003. 
17

Figure 15. Water temperature at Camas for summer 2003. 
18

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 

data-collection system with the Geostationary 

Operational Environmental Satellite: U.S. Geological 

Survey Open-File 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 WaterResources Investigations Report 01–4273, 14 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., 2002, 

Total dissolved gas and water temperature in the lower 

Columbia River, Oregon and Washington, 2002: 

Quality-assurance data and comparison to waterquality standards, U.S. Geological Survey WaterResources Investigations Report 02–4283, 12 p.

U.S. Environmental Protection Agency, 1986, Quality 

criteria for water: Washington, D.C., EPA-440-5-86-

001.