U.S. Department of the Interior

U.S. Geological Survey

Total Dissolved Gas and Water Temperature in the 

Lower Columbia River, Oregon and Washington, 2002: 

Quality-Assurance Data and Comparison to Water-Quality Standards

Water–Resources Investigation Report 02–4283

Prepared in cooperation with the

U.S. Army Corps of Engineers
Cover photographs: 

Upper left: Spill from Bonneville Dam, Columbia River, July 2002.

Lower right: Calibrating equipment on the Columbia River at The Dalles Dam forebay, July 2002.

(Photographs by Rebecca Treat, U.S. Geological Survey volunteer)
U.S. Department of the Interior

U.S. Geological Survey

Total Dissolved Gas and Water Temperature in the 

Lower Columbia River, Oregon and Washington, 

2002: Quality-Assurance Data and Comparison to 

Water-Quality Standards

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

Water-Resources Investigations Report 02–4283

Prepared in cooperation with the 

U.S. ARMY CORPS OF ENGINEERS

Portland Oregon: 2002
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:

District Chief 

U.S. Geological Survey 

10615 S.E. Cherry Blossom Dr. 

Portland, OR 97216-3159 

E-mail: info-or@usgs.gov 

Internet: http://oregon.usgs.gov

Copies of this report may be 

purchased from:

USGS Information Services

Box 25286

Denver, CO 80225-0286

Telephone: 1-888-ASK-USGS

Suggested citation: 

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 

water-quality standards: U.S. Geological Survey Water-Resources Investigations Report 02–4283, 12 p.
iii

CONTENTS

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

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

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

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

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

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

Summary of Data Completeness and Quality .............................................................................................................................4

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

Effects of Spill on Total Dissolved Gas......................................................................................................................................7

Comparison of Total Dissolved Gas and Temperature to Standards ..........................................................................................8

References Cited .......................................................................................................................................................................12

FIGURES

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

water year 2002.............................................................................................................................................................3

2.–13. Graphs showing:

2. Accuracy of total-dissolved-gas sensors when compared to a certified pressure gage after 2 to 3 weeks 

of field deployment .................................................................................................................................................5

3. Difference between the secondary standard and the field barometers....................................................................6

4. Difference between the secondary standard and the field temperature instruments...............................................6

5. Difference between the secondary standard and the field total-dissolved-gas instruments....................................6

6. Total dissolved gas downstream of John Day Dam and spill from John Day Dam ...............................................7

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

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

9. Total-dissolved-gas distributions and exceedances of Oregon Water-Quality variances, 

April 10, 2002 to August 31, 2002........................................................................................................................10

10. Water temperature at Camas for summer 2002 ....................................................................................................10

11. Water temperature upstream and downstream of John Day Dam for summer 2002............................................11

12. Water temperature upstream and downstream of The Dalles Dam for summer 2002..........................................11

13. Water temperature upstream and downstream of Bonneville Dam for summer 2002..........................................12

TABLES

1. Total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, water year 2002 .............................3

2. Total-dissolved-gas data completeness and quality, water year 2002 .................................................................................4

3. Exceedances of State of Oregon Water-Quality variances for total dissolved gas, lower Columbia River, 

Oregon and Washington, water year 2002 ...........................................................................................................................9

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, 

2002: Quality-Assurance Data and Comparison to 

Water-Quality Standards

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

SIGNIFICANT FINDINGS

The U.S. Geological Survey (USGS), in 

cooperation with the U.S. Army Corps of 

Engineers, collected total-dissolved-gas and 

water-temperature data at eight sites near dams 

on the lower Columbia River in 2002. When 

water is released through the spillways of dams, 

air is entrained in the water, increasing the concentration of total dissolved gas to levels that can 

have adverse effects on freshwater aquatic life. 

Significant findings include:

• For the eight monitoring sites in water year 

2002, an average of 99.6% 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 

and ambient river conditions at adjacent sites.

• Most field checks of total-dissolved-gas 

sensors with a secondary standard were within 

1% saturation. Field checks of barometric 

pressure and water temperature were usually 

within 1 millimeter of mercury and 0.05 degrees 

Celsius, respectively.

• In June and July 2002, spills exceeded 

140,000 cubic feet per second at the John Day, 

The Dalles, and Bonneville Dams. These spills 

resulted in levels of total dissolved gas that 

exceeded 120% saturation downstream of the 

dams.

• The variance to the State of Oregon waterquality standard for total dissolved gas of 110% 

saturation was exceeded at seven of the eight 

monitoring sites. The sites at Camas and 

Bonneville are considered forebay sites and had 

the most days exceeding the variance of 115% 

saturation. The forebay exceedances may have 

been the result of the cumulative effects of 

significant spill throughout the lower Columbia 

River. Apparently, the levels of total dissolved 

gas did not dissipate rapidly enough downstream 

of 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 in operation. 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.
2

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 

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), air is entrained in the water, increasing 

the concentration of total dissolved gas (TDG) downstream from the spillways. Consequently, TDG 

may exceed Oregon and Washington water-quality 

standards for the protection of freshwater aquatic life. 

Concentrations 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, and to provide for 

fish passage other than through the turbines. The 

USACE oversees the collection of near real-time 

TDG and water-temperature data (data available 

within about 4 hours of current time) upstream and 

downstream from the dams in a network of fixedstation monitors.

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 and 

2001 contained TDG data, quality-assurance data, 

and descriptions of the methods of data collection for 

water years 1996, 2000, and 2001 (Tanner and others, 

1996; Tanner and Johnston, 2001; and Tanner and 

Bragg, 2001, respectively). 

To provide suitable data for managing and 

modeling TDG in the lower Columbia River, real-time 

hourly data for 2002 were reviewed relative to measurements made during instrument calibration. Some 

TDG data were deleted because they were not of suitable quality. The reviewed hourly data were stored 

in a USGS data base (Automated Data Processing 

System—ADAPS); and in a USACE data base 

(Columbia River Operation Hydromet Management 

System—CROHMS at http://www.nwd-wc.usace. 

army.mil/TMT/tdg_data/). The USACE data base 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 for the monitoring program on 

the lower Columbia River from the forebay of the 

John Day Dam (river mile [RM] 215.6) to Camas, 

Washington (RM 121.7). Data for water year (WY) 

2002 (October 1, 2001, to September 30, 2002) 

included hourly measurements of TDG pressure, barometric pressure, water temperature, and probe depth 

at eight fixed stations on the lower Columbia River 

(fig. 1, table 1). Five sites were operated from March 

to September, two were operated year-round, and 

one site, near Skamania (site 6), was operated only 

during March 2002, a critical time for fisheries below 

Bonneville Dam.

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. Rebecca Treat 

and Ian Wigger, USGS volunteers, assisted with data 

collection in the field.
3

3

5 8 2 1 4 7

6

Deschutes 

Willamette

River

River 

River 

River 

Lewis

Cowlitz

River John Day

Portland

123 ̊ 121 ̊

45 ̊

46 ̊

John Day

Dam

The Dalles

Dam

Bonneville

Dam

Study

area

Washington

Oregon

PACIFIC OCEAN

COLUMBIA

RIVER

8

EXPLANATION

Monitoring site

Map reference number

(see table 1)

0 10 20 30 40 50 MILES

0 10 20 30 40 50 KILOMETERS

Figure 1. Location of total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, water year 2002. 

Table 1. Total-dissolved-gas fixed stations, lower Columbia River, Oregon and Washington, water year 2002

[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 JDA 215.6 454257120413000 Columbia River at John Day Dam forebay, 

Washington (John Day forebay)

45°42’57” 120°41’30” 03/27/02–

09/27/02

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

Washington (John Day tailwater)

45°42’49” 120°42’35” 03/27/02–

09/27/02 

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

Washington (The Dalles forebay)

45°37’12” 121°07’12” 03/26/02–

09/30/02 

4 TDDO 188.9 14105700 Columbia River at The Dalles, 

Oregon (The Dalles tailwater)

45°36’27” 121°10’20” 03/26/02–

09/30/02 

5 BON 146.1 453845121562000 Columbia River at Bonneville Dam forebay, 

Washington (Bonneville forebay)

45°38’45” 121°56’20” Year-round 

6 SKAW 140.5 453651122022200 Columbia River, right bank, near Skamania, 

Washington (Skamania)

45°36’51” 122°02’22” 02/28/02–

03/29/02 

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” 02/28/02–

09/30/02 
4

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 CROHMS, and to the 

USGS ADAPS data base. At one site, John Day 

tailwater, two TDG sensors were installed on the same 

Hydrolab. This was done to ensure that data were 

reliably collected at this important site.

The fixed-station monitors were calibrated every 

2 weeks from March to September 2002, and every 

3 weeks for the remainder of the water year, at which 

time Warrendale and Bonneville forebay were the 

only sites in operation. The field calibration procedure 

is outlined below. 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. Again, the secondary standard was 

used to check TDG and temperature 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 (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 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 DATA COMPLETENESS 

AND QUALITY

A summary of USGS TDG data completeness 

and quality for WY 2002 is shown in table 2. (The 

USACE satellite downlink operated independently, 

but 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 total dissolved 

gas 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 1% saturation of the expected value, 

based on calibration data and daily checks of ambient 

river conditions at adjacent sites. 

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

water year 2002

[TDG, total dissolved gas]

Abbreviated 

station 

name

Planned 

monitoring, 

in hours

Number of 

missing hourly 

values 

Percentage 

of real-time 

TDG data passing 

quality assurance

John Day forebay 4,417 9 99.8

John Day tailwater 4,414 5 99.9

The Dalles forebay 4,522 31 99.3

The Dalles tailwater 4,524 11 99.8

Bonneville forebay 8,760 101 98.8

Skamania 697 0 100

Warrendale 8,760 44 99.5

Camas 5,149 26 99.5

Average -- -- 99.6
5

At each station, at least 98.8% of the data was 

received in real time by the USGS downlink and met 

quality-assurance standards, with an overall average 

of 99.6% (table 2). Missing hourly values were usually 

due to malfunction of the data-collection platform or 

mistakes in programming it. The lowest percentage 

for a station was 98.8% at Bonneville forebay. 

Most of this data loss occurred in March, due to 

transmission problems as a result of a faulty battery 

and cable.

QUALITY-ASSURANCE DATA

Data collection for TDG, barometric pressure 

and water temperature involved several qualityassurance procedures, including calibration of 

instruments in the field and in the laboratory, 

daily checks of the data, and data review and 

archive (Tanner and Johnston, 2001). The qualityassurance data for WY 2002 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 and to supersaturation 

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. The calibration test procedure 

compared the reading of the TDG sensor to barometric 

pressure (100% saturation). Using a certified digital 

pressure gage (primary standard), comparisons also 

were 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 by computing 

the difference between the expected reading and the 

TDG sensor reading (expected minus actual) for each 

of the four test conditions. As shown in figure 2, most 

of the sensor readings fell within 0.2% saturation and 

all were well within 1%.

After 2 to 3 weeks of field deployment, the

differences in barometric pressure, water temperature 

and TDG between the fixed-station monitors 

and the recently calibrated secondary standard 

instruments were measured and recorded as part 

of the field inspection and calibration procedure. 

These differences (secondary standard minus field 

instrument) were used to compare and quantify the 

precision between the two independent instruments. 

CALIBRATION TEST CONDITION, IN PERCENT SATURATION

100% 113% 126% 139% -1.0

-0.5

0.0

0.5

1.0

10th percentile

25th percentile

Median

75th percentile

90th percentile

10th and 90th percentiles

Data values outside the

EXPLANATION

CERTIFIED PRESSURE GAGE READING MINUS

VALUE FROM FIELD-TOTAL-DISSOLVED-GAS PROBE,

IN PERCENT SATURATION

Figure 2. Accuracy of total-dissolved-gas sensors when compared 

to a certified pressure gage after 2 to 3 weeks of field deployment. 

(130 tests were conducted at each pressure.)

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 3 to 4 weeks, served as the secondary 

standard for barometric pressure. Figures 3, 4, and 5 

illustrate the distribution of quality-assurance data for 

each of the three parameters from seven field sites. 

The comparisons of the aneroid 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 the median difference at each 

site was zero. The only difference greater than 

3 mm Hg was the initial calibration (adjustment of the 

DCP offset values) of the field barometer at the John 

Day tailwater site. The temperature sensor secondary 

standard and the field temperature sensor results are 

presented in figure 4. Most of the differences were 

within 0.05°C (degrees Celsius); however, the primary 

standard was certified only to plus or minus 0.1°C. 
6

SITE IDENTIFIER

JDA JHAW TDA TDDO BON WRNO CWMW

SECONDARY STANDARD VALUE MINUS 

FIELD INSTRUMENT VALUE, IN MILLIMETERS OF MERCURY

-6

-4

-2

0

2

4

6

N=13 N=13 N=14 N=14 N=22 N=23 N=15 EXPLANATION

10th percentile

Number of samples

25th percentile

75th percentile

90th percentile

10th and 90th percentiles

Data values outside the

N = 22

Median = 0

Figure 3. Difference between the secondary standard and the field barometers. (Refer to table 1 for site identifiers.)

SITE IDENTIFIER

JDA JHAW TD A T DDO BON WRNO CWMW

SECONDARY STANDARD VALUE MINUS 

FIELD INSTRUMENT VALUE, IN DEGREES CELSIUS

-0.2

-0.1

0.0

0.1

0.2

N=13 N=13 N=14 N=14 N=22 N=23 N=14

EXPLANATION

10th percentile

Number of samples

25th percentile

Median

75th percentile

90th percentile

10th and 90th percentiles

Data values outside the

N = 22

Figure 4. Difference between the secondary standard and the field temperature instruments. (Refer to table 1 for site identifiers.)

SITE IDENTIFIER

JDA JHAW TD A T DDO BON WRNO CWMW

SECONDARY STANDARD VALUE MINUS 

FIELD INSTRUMENT VALUE, IN PERCENT SATURATION

-3

-2

-1

0

1

2

3

N=13 N=13 N=14 N=14 N=22 N=23 N=14

EXPLANATION

10th percentile

Number of samples

25th percentile

Median

75th percentile

90th percentile

10th and 90th percentiles

Data values outside the

N = 22

Figure 5. Difference between the secondary standard and the field total-dissolved-gas instruments. (Refer to table 1 for site 

identifiers.)
7

Following deployment of the field TDG sensor 

for 2 to 3 weeks, the differences between the TDG 

sensor used as a secondary standard and the field 

TDG sensors were calculated after equilibration of 

the secondary standard unit to the site conditions. The 

side by side equilibrium was considered complete 

after a minimum of 20 minutes when the TDG values 

for each sensor remained constant for 4 to 5 minutes. 

As shown in figure 5, most of the data demonstrates 

less than 1% saturation difference between the two 

sensors. However, differences at the site at John Day 

forebay often exceeded this value. Two different 

TDG sensors were deployed at different times for 

field operation at the site. Both sensors yielded similar 

results, and both passed all calibration tests after 

deployment, suggesting that instrument malfunction 

was not the cause of the larger TDG differences. 

Although the secondary standard and field probes 

were positioned at approximately the same depth during the field checks, the field sensor was positioned 

inside a pipe housing and the secondary standard was 

positioned in open water. Partially stagnant water in 

the pipe may have caused the probe inside the housing 

(the field probe) to have smaller TDG measurements 

than the probe outside the housing (the secondary 

standard).

EFFECTS OF SPILL ON TOTAL DISSOLVED GAS

Spill from each dam increased the level of 

TDG downstream of the dam. Spill data are from 

the USACE (http://www.nwd-wc.usace.army.mil/ 

TMT/tdg_data/month.html). Spill from John Day 

Dam occurred from April 10 to August 31 (fig. 6). The 

spill was usually less than 160,000 ft3

/s (cubic feet per 

second) and often occurred only between 7:00 p.m. 

and 7:00 a.m. for fish passage considerations. Figure 6 

shows that TDG downstream of John Day Dam 

increased in response to spill from the dam, with the 

TDG level usually being less than 120% saturation. 

During three time periods, June 4–9, June 28–July 2, 

and July 12, the spill from John Day Dam exceeded 

160,000 ft3/s, causing the TDG at John Day tailwater 

to increase to values larger than 120% saturation.

Spill from The Dalles Dam (fig. 7) was continuous from April 10 to August 31 (except for several 

hours of no spill on June 26 and June 28). The spill 

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

resulting in a TDG level of 110 to 120%. During two 

time periods, June 2–9 and June 28–July 3, the spill 

from The Dalles Dam exceeded 140,000 ft3

/s, causing 

the TDG at The Dalles tailwater to increase to values 

larger than 120% saturation. 

27 6 16 26 6 16 26 5 15 25 5 15 25 4 14 24 3 13

0

40

90

140

190

240

290

95

100

105

110

115

120

125

130

John Day Tailwater

Spill from John Day Dam

2002

MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER

TOTAL-DISSOLVED-GAS SATURATION,

IN PERCENT

SPILL,

IN THOUSANDS OF CUBIC FEET PER SECOND

Oregon variance

for tailwater

Figure 6. Total dissolved gas downstream of John Day Dam and spill from John Day Dam.
8

 26 5 15 25 5 15 25 4 14 24 4 14 24 3 13 23 2 12

0

40

90

140

190

240

290

95

100

105

110

115

120

125

130

The Dalles Tailwater

Spill from The Dalles Dam

TOTAL-DISSOLVED-GAS SATURATION,

IN PERCENT

SPILL,

IN THOUSANDS OF CUBIC FEET PER SECOND

2002

MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER

Oregon variance

for tailwater

Figure 7. Total dissolved gas downstream of The Dalles Dam and spill from The Dalles Dam.

At Bonneville Dam, there were two periods of 

spill in WY 2002 (fig. 8). From March 12 to March 15, 

spill was as large as 100,000 ft3

/s to flush released 

hatchery fish to the ocean. During this spill the TDG at 

the Warrendale site (which is about 6 miles downstream of Bonneville Dam) increased to about 112%. 

Periods of nearly continuous spill typically ranging 

from about 75,000 ft3/s to 150,000 ft3/s from April 10 

to August 31 caused TDG levels at Warrendale to rise 

to about 110–120% of saturation. During two time 

periods, June 1–11 and June 28–July 3, the spill from 

Bonneville Dam exceeded 170,000 ft3

/s, causing the 

TDG at Warrendale to increase to values larger than 

120% saturation. 

COMPARISON OF TOTAL DISSOLVED GAS 

AND TEMPERATURE TO STANDARDS

In this report, compliance with only the Oregon 

water-quality standards for TDG and water temperature for the lower Columbia River are addressed. 

Washington standards, however, are similar to the 

Oregon standards. The State of Oregon water-quality 

standard for TDG is 110% saturation (Oregon Department of Environmental Quality, written commun., 

2002). From April 1 to August 31, 2002, the USACE 

was granted a variance to this standard 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, Warrendale, and 

Skamania). Although the Camas site is not located at 

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

a forebay site. The variance was exceeded if the 

average of the highest 12 hourly values in one day 

(1:00 a.m. to midnight) was larger than the numerical 

standard.

At seven of the eight monitoring stations, the 

Oregon variance for TDG was exceeded at some time 

during WY 2002 (table 3). There were no exceedances 

at the Skamania site, which was operated only during 

March, before large amounts of spill occurred at 

Bonneville Dam. The site with the most exceedances 

was Camas, which exceeded the 115% variance 

62 times, followed by Bonneville forebay, which 

exceeded the 115% variance 31 times. Overall, there 

were fewer exceedances at the tailwater sites, which 

had the larger variance of 120%.
9

8 18 28 7 17 27 7 17 27 6 16 26 6 16 26 5 15 25 4 14

0

40

90

140

190

240

290

95

100

105

110

115

120

125

130

Warrendale

Spill from Bonneville Dam

2002

MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER

TOTAL-DISSOLVED-GAS SATURATION,

IN PERCENT

SPILL,

IN THOUSANDS OF CUBIC FEET PER SECOND

Oregon variance for tailwater

Figure 8. Total dissolved gas downstream of Bonneville Dam at Warrendale and spill from Bonneville Dam.

Available data indicate that the forebay exceedances may have been the result of the 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.

Table 3. Exceedances of State of Oregon Water-Quality variances 

for total dissolved gas, lower Columbia River, Oregon and 

Washington, water year 2002

[The variance was exceeded if the average of the highest 12 hourly values in 

one day (1:00 a.m. to midnight) was larger than the numerical standard 

(Oregon Department of Environmental Quality, written commun., 2002)]

 Abbreviated

station name

Numerical variance for 

total dissolved gas, in 

percent saturation

Number of days 

in exceedance 

of variance

John Day forebay 115 11

John Day tailwater 120 25

The Dalles forebay 115 15

The Dalles tailwater 120 10

Bonneville forebay 115 31

Skamania 120 0

Warrendale 120 19

Camas 115 62

There was an increase in both the median TDG level 

and the number of exceedances at the forebay sites 

moving downstream from John Day forebay to 

The Dalles forebay to Bonneville to Camas (fig. 9). 

Total maximum daily loads (TMDLs) for TDG 

are currently being discussed for the Columbia River 

(http://yosemite.epa.gov/r10/water.nsf/, accessed on 

October 30, 2002). If the TDG values in figure 9 

were weighted for discharge, they would describe 

the TDG loads in the lower Columbia River. It 

was beyond the scope of this report to make these 

calculations, but they may be useful for evaluating 

the TMDLs in the future.

In WY 2002, the effects of spill on TDG outweighed the effects of temperature at Camas. In 

WY 2001, spills were generally small and infrequent, 

and increases in water temperature probably were 

responsible for some of the TDG exceedances at 

Camas (Tanner and Bragg, 2001, p. 12). Daily temperature increases above the daily average for late 

summer 2002 at Camas were about 0.5°C (fig. 10), 

and this would result in an increase of TDG by about 

1.5% saturation, based on a computer program from 

Mike Schneider (USACE, written commun., 2002). 
10

JDA JHAW TDA TDDO BON WRNO CWMW

95

100

105

110

115

120

125

130

Oregon

variance

for forebay

water

Oregon variance

for tailwater

N=3448 N=3452 N=3429 N=3446 N=3447 N=3442 N=3448

EXPLANATION

10th percentile

Number of samples

Days with exceedances 

 of Oregon variance

25th percentile

Median

75th percentile

90th percentile

10th and 90th percentiles

Data values outside the

N = 22

TOTAL-DISSOLVED-GAS SATURATION, IN PERCENT

11

11

25

15

10

31

19

62

Figure 9. Total-dissolved-gas distributions and exceedances of Oregon Water-Quality variances, April 10, 2002 to August 31, 2002. 

(Refer to table 1 for site identifiers.) 

18 20 22 24 26 28 30

AUGUST

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

SEPTEMBER

2 4 6 8 10 12 14 16

2002

19

20

21

22

COLUMBIA RIVER AT CAMAS

JULY

WATER TEMPERATURE, IN DEGREES CELSIUS

Figure 10. Water temperature at Camas for summer 2002.

The majority of the exceedances at Camas were by 

a larger margin than 1.5% saturation, illustrating the 

disproportionate control exerted by spill compared 

to water temperature in WY 2002.

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 October 30, 2002). The Columbia River 

from RM 309 to the mouth includes all eight of the 

lower Columbia River TDG fixed stations. Water 

temperatures upstream and downstream of John 

Day Dam were equal to or higher than 20°C continuously from July 21 to September 17 (fig. 11). On 

several afternoons during this period, the water temperature at the forebay site transiently increased 

by up to about 2°C higher than the tailwater site. 
11

18 20 22 24 26 28 30 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 2 4 6 8 10 12 14 16

2002

19

20

21

22

23

24

COLUMBIA RIVER AT JOHN DAY FOREBAY

COLUMBIA RIVER AT JOHN DAY TAILWATER

JULY

WATER TEMPERATURE, IN DEGREES CELSIUS

AUGUST SEPTEMBER

Figure 11. Water temperature upstream and downstream of John Day Dam for summer 2002. 

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.

Water temperatures upstream and downstream of The Dalles Dam were equal to or higher 

than 20°C continuously from July 20 to September 8 

(fig. 12). 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 

of Bonneville Dam were equal to or higher than 20°C 

almost continuously from July 21 to September 6 

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

was approximately equal to the temperature at 

Warrendale (the tailwater site) during the first part of 

the summer season, but after the spill and discharge 

at Bonneville Dam decreased beginning September 1, 

2002, the Warrendale site had water temperatures 

that differed from those at the Bonneville site by up to 

about 1°C (fig. 13).

18 20 22 24 26 28 30

AUGUST

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

SEPTEMBER

2 4 6 8 10 12 14 16

2002

19

19.5

20

20.5

21

21.5

COLUMBIA RIVER AT THE DALLES FOREBAY

COLUMBIA RIVER AT THE DALLES TAILWATER

JULY

WATER TEMPERATURE, IN DEGREES CELSIUS

Figure 12. Water temperature upstream and downstream of The Dalles Dam for summer 2002. 
12

18 20 22 24 26 28 30

AUGUST

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

SEPTEMBER

2 4 6 8 10 12 14 16

2002

19

19.5

20

20.5

21

21.5

COLUMBIA RIVER AT BONNEVILLE FOREBAY

COLUMBIA RIVER AT WARRENDALE

JULY

WATER TEMPERATURE, IN DEGREES CELSIUS

Figure 13. Water temperature upstream and downstream of Bonneville Dam for summer 2002. 

At the Camas site, the water temperature was 

20°C or higher for at least part of each day from 

July 16 to September 7 (fig. 10). During the summer, 

there was a distinct diurnal or daily cycle to the 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 2001 (Tanner 

and Bragg, 2001, p. 11 and 12), and perhaps indicates 

the characteristics of the Columbia River where it is 

relatively unaffected by the dams. The effects of these 

temperature changes on TDG were discussed earlier in 

this section.

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.

U.S. Environmental Protection Agency, 1986, Quality criteria for water: Washington, D.C., EPA-440-5-86-001.