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

Total Dissolved Gas and Water Temperature in the 

Lower Columbia River, Oregon and Washington, 2007: 

Quality-Assurance Data and Comparison to WaterQuality Standards 

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

Open-File Report 2007-1408 

U.S. Department of the Interior 

U.S. Geological Survey 
Cover photo: Calibrating the water-quality station below John Day Dam, December 27, 2006. 

(Photograph by Dwight Q. Tanner, U.S. Geological Survey.) 

ii 
U.S. Department of the Interior 

DIRK A. KEMPTHORNE, Secretary 

U.S. Geological Survey 

MARK E. MYERS, Director 

U.S. Geological Survey, Reston, Virginia 2007 

For product and ordering information: 

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its natural and living resources, natural hazards, and the environment: 

World Wide Web: http://www.usgs.gov 

Telephone: 1-888-ASK-USGS 

Suggested citation: 

Tanner, D.Q., Bragg, H.M., and Johnston, M.W., 2007, Total dissolved gas and water temperature in 

the lower Columbia River, Oregon and Washington, 2007—Quality-assurance data and comparison to 

water-quality standards: U.S. Geological Survey Open-File Report 2007-1408, 23 p. 

The use of trade, product, or firm names 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 material contained within this report. 

iii 
Contents 

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

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

Background............................................................................................................................................................ 3

Purpose and Scope............................................................................................................................................... 3

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

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

Quality-Assurance Data........................................................................................................................................... 8

Effects of Spill on Total Dissolved Gas................................................................................................................ 11

Comparison of Total Dissolved Gas and Temperature to Standards ............................................................ 19

References Cited..................................................................................................................................................... 23

Figures 

Figure 1. Location of total-dissolved-gas monitoring stations, lower Columbia River, Oregon and 

Washington, water year 2007. ................................................................................................................................ 2

Figure 2. Accuracy of total-dissolved-gas sensors after 3 or 4 weeks of field deployment (Number of 

comparison values = 94). ......................................................................................................................................... 9

Figure 3. Difference between the secondary standard and the field barometers after 3 or 4 weeks of 

field deployment........................................................................................................................................................ 9

Figure 4. Difference between the secondary standard and the field temperature instruments after 3 or 

4 weeks of field deployment ................................................................................................................................. 10

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

after 3 or 4 weeks of field deployment................................................................................................................ 10

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

Dam, March 15 to September 15, 2007................................................................................................................ 12

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

Dam, March 15 to September 15, 2007............................................................................................................... 13

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

from Bonneville Dam, March 15 to September 15, 2007. ................................................................................. 14

Figure 9. Total dissolved gas saturation downstream from Bonneville Dam at Cascade Island and spill 

from Bonneville Dam, March 15 to September 15, 2007. ................................................................................. 15

Figure 10. Total dissolved gas saturation upstream from John Day Dam, March 15 to September 15, 

2007)........................................................................................................................................................................... 17

Figure 11. Total dissolved gas saturation upstream from The Dalles Dam, March 15 to September 15, 

2007............................................................................................................................................................................ 17

Figure 12. Total dissolved gas saturation upstream from Bonneville Dam, March 15 to September 15, 

2007............................................................................................................................................................................ 18

Figure 13. Total dissolved gas saturation at Camas, March 15 to September 15, 2007 ............................ 18

Figure 14. Distributions of hourly total-dissolved-gas data and Oregon and Washington water-quality 

variances, April 1, 2007, to August 31, 2007........................................................................................................ 20

Figure 15. Water temperature upstream and downstream from John Day Dam, summer 2007 .............. 21

Figure 16. Water temperature upstream and downstream from The Dalles Dam, summer 2007 ............ 21

iv 
Figure 17. Water temperature upstream and downstream from Bonneville Dam, summer 2007 ............ 22

Figure 18. Water temperature at Camas, summer 2007................................................................................... 22

Tables 

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

water year 2007 ......................................................................................................................................................... 4

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

Washington, water year 2007 ................................................................................................................................. 6

Table 3. Major portions of missing or deleted data, water year 2007 ............................................................ 7

Conversion Factors 

Multiply By To obtain 

inch (in.) 2.54 centimeter (cm) 

mile (mi) 1.609 kilometer (km) 

square mile (mi2

) 2.590 square kilometer (km2) 

cubic foot per second (ft3

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

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

°F=(1.8×°C)+32 

Acknowledgments 

The authors acknowledge the aid and funding support of the U.S. Army Corps of Engineers. 

Our special thanks go to James L. Britton (USACE) for technical and logistical support of the project. 

The authors also thank Amy M. Brooks (USGS) for preparing summaries and analyses of data and 

Valerie J. Kelly (USGS) for preparing some of the illustrations. 

v 
This page is intentionally blank. 

vi 
Total Dissolved Gas and Water Temperature in the 

Lower Columbia River, Oregon and Washington, 2007: 

Quality-Assurance Data and Comparison to WaterQuality 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 dissolved gases. 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 dissolved-gas and water-temperature data at eight sites 

on the lower Columbia River in 2007. Significant findings from the data include: 

• From early July to mid-September 2007, water temperatures were above 20 °C (degrees Celsius) 

at each of the eight lower Columbia River sites. According to the Oregon temperature standard, 

the 7-day average maximum temperature of the lower Columbia River should not exceed 20 °C; 

Washington regulations state that the 1-day maximum should not exceed 20 °C due to human 

activities. 

• Most in-situ field checks of total-dissolved-gas sensors with a secondary standard were within ± 

(plus or minus) 1% saturation after 3 to 4 weeks of deployment in the river. All of the field 

checks of barometric pressure were within ±2.5 millimeter of mercury of a secondary standard, 

and water-temperature field checks were all within ±0.2 °C. 

• For the eight monitoring sites in water year 2007, an average of 99.5% of the total-dissolved-gas 

data were received in real time by the USGS satellite downlink and were within 1% saturation of 

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

river, and comparison to ambient river conditions at adjacent sites. Data received from the sites 

ranged from 97.9% to 100.0% complete. 

1 
Introduction 

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

Basin (fig. 1), 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, 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 dissolved gases (known as total dissolved gas [TDG]) downstream from the 

spillways. TDG conditions above 110% saturation can cause gas-bubble trauma in fish and adversely 

affect other aquatic organisms (U.S. Environmental Protection Agency, 1986). 

Figure 1. Location of total-dissolved-gas monitoring stations, lower Columbia River, Oregon and 

Washington, water year 2007. 

The USACE regulates spill and streamflow to minimize the production of excess TDG 

downstream from its dams, but there is also a 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 spring and summer. In order to monitor 

compliance with these variances, the USACE oversees the collection of real-time TDG and watertemperature data upstream and downstream from Columbia River Basin dams in a network of 

monitoring stations. Data from the lower Columbia River monitoring stations are available within 

about 1 hour of current time. 

2 
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 each year since 1996. Current and historical TDG and 

water-temperature data can be found on the USGS Oregon Water Science Center Website at 

http://oregon.usgs.gov/projs_dir/pn307.tdg/. Eight reports, published for water years 1996, 2000, 

2001, 2002, 2003, 2004, 2005, and 2006, contain 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; Tanner and others, 2003; and Tanner and others, 2004; Tanner 

and others, 2005; and Tanner and others, 2006). 

To insure quality data for managing and modeling TDG in the lower Columbia River, hourly 

data for 2007 were reviewed relative to laboratory and field measurements made during instrument 

calibrations and daily intersite comparisons. A small fraction of the TDG data was deleted because 

they were not of suitable quality. The hourly data were stored in a USGS data base and in a USACE 

data base (http://www.nwd-wc.usace.army.mil/tmt/wcd/tdg/months.html). 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, (2) reviewed TDG data to 

evaluate conditions relative to water-quality standards, and (3) data 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 eight sites, from the navigation lock of the John Day Dam (river mile [RM] 215.7) to Camas, 

Washington (RM 121.7), (fig. 1, table 1). Data for water year 2007 (October 1, 2006, to September 

30, 2007) include hourly measurements of TDG pressure, barometric pressure, water temperature, 

and probe depth. Five of the sites (John Day navigation lock, The Dalles forebay, Bonneville, 

Cascade Island, and Camas) were operated from February or March to September 2007, which is the 

usual time of spill from the dams. John Day tailwater and The Dalles tailwater were operated yearround and Warrendale was operated year-round except for a period of time from June to midSeptember, when site operation was stopped at the request of the USACE. 

3 
Table 1. Total-dissolved-gas monitoring stations, lower Columbia River, Oregon and 

Washington, water year 2007 

[Map reference number refers to figure 1; USACE, U.S. Army Corps of Engineers; Columbia River mile locations 

were determined from U.S. Geological Survey (USGS) 7.5-minute topographic maps; stations in this report are 

referenced by their abbreviated name or USACE site identifier; °, degree; ’, minute; ”, second] 

Map 

number 

USACE 

site 

identifier 

River 

mile 

USGS 

station 

number 

USGS station name 

(and abbreviated 

station name) Latitude Longitude 

Period 

of 

record 

1 

2 

3 

4 

5 

6 

7 

8 

JDY 

JHAW 

TDA 

TDDO 

BON 

CCIW 

WRNO 

CWMW 

215.7 

214.7 

192.6 

188.9 

146.1 

145.9 

140.4 

121.7 

454314120413701 

454249120423500 

453712121071200 

14105700 

453845121562000 

453845121564001 

453630122021400 

453439122223900 

Columbia River at John Day 

navigation lock, Washington 

(John Day navigation lock) 

Columbia River, right bank, 

near Cliffs, Washington (John 

Day tailwater) 

Columbia River at The Dalles 

Dam forebay, Washington 

(The Dalles forebay) 

Columbia River at The 

Dalles, Oregon (The Dalles 

tailwater) 

Columbia River at Bonneville 

Dam forebay, Washington 

(Bonneville forebay) 

Columbia River at Cascade 

Island, Washington (Cascade 

Island) 

Columbia River, left bank, 

near Dodson, Oregon 

(Warrendale) 

Columbia River, right bank, 

at Washougal, Washington 

(Camas) 

45° 43’ 14” 120° 41’ 37” 

45° 42’ 49” 120° 42’ 35” 

45° 37’ 12” 121° 07’ 12” 

45° 36’ 27” 121° 10’ 20” 

45° 38’ 45” 121° 56’ 20” 

45° 38’ 45” 121° 56’ 40” 

45° 36’ 30” 122° 02’ 14” 

45° 34’ 39” 122° 22’ 39” 

03/28/07–

09/30/07 

Year-round

03/28/07–

09/30/07 

Year-round

02/21/07–

09/14/07 

02/22/07–

09/30/07 

10/01/06–

05/31/07 

and 

09/20/07–

09/30/07 

02/21/07–

09/20/07 

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 monitoring station consists of a Hydrolab water-quality probe, a Vaisala electronic barometer, a 

power supply, and a Sutron SatLink2 data-collection platform (DCP). The instruments at each site are 

powered by a 12-volt battery that is charged by a solar panel and/or a 120-volt alternating-current 

4 
line. At the beginning of the monitoring season in February or March, a new TDG membrane is 

installed on each Hydrolab. Measurements (including probe depth) are made, logged, and transmitted 

every hour. The DCP transmits the most recent logged data to the Geostationary Operational 

Environmental Satellite (GOES) system (Jones and others, 1991). The data are automatically decoded 

and transferred to the USACE data base and to the USGS data base. 

The eight fixed-station monitors were calibrated every 3 weeks, except from October 2006 

through March 2007, when they were calibrated at 4-week intervals. 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 for a period of up to 1 hour to 

obtain check measurements of TDG and water temperature prior to removing the field Hydrolab 

(which had been deployed for 3 or 4 weeks). The field Hydrolab was then replaced with another 

Hydrolab that had been calibrated recently at the laboratory and the secondary standard used again to 

check TDG and temperature measured by the newly deployed Hydrolab in the river. The 

equilibration process for the newly-placed Hydrolab usually lasted about 1 hour. The electronic 

barometer at the fixed station was calibrated using a portable barometer (Suunto, Escape 203) that 

had been recently calibrated at the National Weather Service facility in northeast Portland. 

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, page 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 whenever possible. During water year 2007, maintaining the probes below the 

minimum compensation depth was not a problem. 

The Hydrolab that was brought from the field after 3 or 4 weeks of deployment was then 

calibrated in the laboratory. The integrity of the TDG membrane was checked, then the membrane 

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

100, 200, and 300 mm Hg (millimeters of mercury) above atmospheric pressure to cover the expected 

range of TDG in the river (approximately 100, 113, 126, and 139% saturation, respectively). 

Summary of Total-Dissolved-Gas Data Completeness and 

Quality 

A summary of USGS TDG data completeness and quality for water year 2007 is shown in table 

2. (The USACE satellite downlink was a parallel system, so the amount and quality of data received 

by the USACE were almost identical). 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 

percentages of data that were 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, replicate quality-control measurements in 

the river, and daily comparisons to ambient river conditions at adjacent sites. At each station, at least 

97.9% of the data were received in real time by the USGS downlink and met quality-control checks, 

with an overall average of 99.5% (table 2). 

5 
Table 2. Total-dissolved-gas data completeness and quality, lower Columbia 

bre

o

Pl

mo

in

Percentage of realtime data passing 

River, Oregon and Washington, water year 2007 

[Results are based on values in USGS ADAPS database; TDG, total dissolved gas] 

Ab

stati

viated 

n name

anned 

nitoring 

 hours 

Number of 

missing or deleted

hourly values quality assurance 

John Day na n lock vigatio 4,476 93 97.9 

John Day tailwater 8,760 62 99.3 

The Dalles forebay 4,471 99.4 

The Dalles t r 

Bonneville forebay 4,918 99.9 

Cascade Island 5,290 100.0 

Wa ndale 

Camas 5,066 99.5 

Average -- 99.5 

27 

ailwate 8,760 8 

3 

99.9 

1 

rre 6,079 11 

25 

99.8 

-- 

Table 3 is a chronological list of the major portions of data that were either missing from the 

database (for example, when data telemetry failed) or data that were later deleted from the database 

because they did not meet quality-assurance standards. Table 3 includes temperature and depth data, 

whereas table 2 includes only TDG data. The John Day navigation lock site had the most missing or 

deleted data. Data loss for TDG and temperature data at that site in June was caused by a faulty cable, 

which was replaced. At the John Day tailwater site, data were missing intermittently in September 

and could not be recovered or reconstructed. At Camas, there were several episodes in July, August, 

and September of missing data, probably due to fishing boats docking overnight and blocking the 

DCP antenna. These data were recovered later and restored to the data bases. 

6 
Table 3. Major portions of missing or deleted data, water year 2007—continued 

[Site abbreviations: JDY, John Day navigation lock; JHAW, John Day tailwater; TDDO, The Dalles tailwater; BON, Bonneville forebay; CCIW, Cascade Island; WRNO, Warrendale; CWMW, Camas. Parameter and 

unit abbreviations: TDG, total dissolved gas; BP, barometric pressure; WT, water temperature] 

Date & Time Site Parameter Reason / Notes 

6/08/07 09:00 

through 

6/12/07 12:00 

JDY TDG, WT Faulty cable, data not recovered 

11/20/06 13:00 

through 

11/20/06 16:00 

JHAW TDG Slow equilibrations, data not recovered 

11/28/06 23:00 

through TDG, BP, 

11/29/06 02:00 

JHAW WT No data transmission, data were recovered 

5/30/07 16:00 JHAW WT Erroneous, data not recovered 

9/04/07 12:00 

through 

9/17/07 19:00 

JHAW TDG, WT Intermittent cable or probe problem, data not recovered 

8/01/07 12:00 

through 

9/04/07 07:00 

TDA TDG, BP, 

WT 

Intermittent episodes of an onsite crane blocking the antenna 

transmissions, data were recovered 

11/28/07 23:00 

through TDDO TDG, BP, 

WT No data transmission, data were recovered 

11/29/07 02:00 

1/29/07 15:00 TDDO WT Calibration, data not recovered 

2/17/07 01:00 

through 

2/17/07 03:00 

TDDO TDG, BP, 

WT No data transmission, data were recovered 

7/13/07 11:00 BON TDG, WT Calibration, data not recovered 

8/01/07 12:00 

through 

8/01/07 13:00 

BON TDG, BP, 

WT No data transmission, data were recovered 

9/16/07 07:00 CCIW TDG, BP, 

WT No data transmission, data were recovered 

11/29/06 00:00 

through 

11/30/06 07:00 

WRNO TDG, BP, 

WT No data transmission, data were recovered 

7 
Table 3. Major portions of missing or deleted data, water year 2007—continued 

[Site abbreviations: JDY, John Day navigation lock; JHAW, John Day tailwater; TDDO, The Dalles tailwater; BON, Bonneville forebay; CCIW, Cascade Island; WRNO, Warrendale; CWMW, Camas. Parameter and 

unit abbreviations: TDG, total dissolved gas; BP, barometric pressure; WT, water temperature] 

Date & Time Site Parameter Reason / Notes 

2/17/07 01:00 

through 

2/17/07 03:00 

WRNO TDG, BP, 

WT No data transmission, data were r ed ecover

7/22/07 22:00 

through 

7/23/07 03:00 

W CWM TDG,

WT 

 BP, No data transmission, ship possibly blocking antenna, data were 

recovered 

8/01/07 12:00 

through 

8/01/07 13:00 

CWMW TDG, BP, 

WT No data transmission, data were recovered 

8/05/07 22:00 

through 

8/06/07 03:00 

CWMW TDG, BP, 

WT 

No data transmission, ship possibly blocking antenna, data were 

recovered 

9/15/07 22:00 

through 

9/17/07 02:00

CWMW TDG,

WT 

 BP, No data transmission, ship possibly blocking antenna, data were 

recovered 

Quality-Assurance Data 

Data collection for TDG, barometric pressure and water temperature involve several qualityassurance procedures, including calibration of instruments in the field and in the laboratory, daily 

checks of the data, and data review and archive. These methods are explained in detail in Tanner and 

Johnston (2001), and the results of the quality-assurance data for water year 2007 are presented in 

this section. 

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

First, the instrument was tested, with the membrane in place, for response to increased pressure and 

to super-saturation conditions. The membrane was then removed from the sensor and allowed to dry 

for approximately 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 

were also 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 by computing the difference between the expected reading and the TDG sensor 

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

pressure. As shown in figure 2, all of the sensor readings were within 0.5% saturation. 

8 
Figure 2.

comparison values = 94). 

e differen baro ess the secondary 

standard instruments and the fixed-station monitors after field deployment were measured and 

record spection and calibration procedure. These differences, defined as the 

secondary standard values m ield quantify the 

precision between the two independent in rature and TDG, the 

m ts were made in-situ with the secondary standard (a recently calibrated Hydrolab) 

p ngside the field Hydrolab in the river. A digital barometer, calibrated every 6 to 8 

weeks, served as the seconda rd for barome 4 and 5 illustrate the 

distribution of quality assurance data for each of th t field sites. 

 Accuracy of total-dissolved-gas sensors after 3 or 4 weeks of field deployment (Number of 

Th ces in metric pr ure, water temperature, and TDG between 

ed as part of the field in

inus the f instrument values, were used to compare and 

struments. For water tempe

easuremen

ositioned alo

ry standa tric pressure. Figures 3,

e three parameters from all eigh

Figure 3. Difference between the secondary standard and the field barometers after 3 or 4 weeks of 

field deployment 

9 
Figure 4. Difference between the secondary standard and the field temperature instruments after 3 or 

4 weeks of field deployment 

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

after 3 or 4 weeks of field deployment 

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

the field values were within 2.5 mm Hg of the standard values. The secondary standard temperature 

sensor and the field temperature sensor results are presented in figure 4. All of the differences were 

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 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. 

All of the data demonstrate less than 1.5% saturation difference between the two TDG sensors

with most less than 1% saturation (fig. 5). The two greatest differences are + 1.4% saturation at Joh

Day forebay and + 1.5% saturation at John Day tailwater. The data point at John Day forebay was 

of 

, 

n 

10 
11 

recorded during the field check on May 30, 2007. The data point at John Day tailwater was recorded 

during the field check on July 12, 2007. Both field instruments passed post-deployment calibration 

tests and performed well for the rest of the field season. It is possible that more equilibration time of 

the secondary standard instrument would have resulted in a lesser difference between the instruments 

in both instances. 

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.html). 

Night-time spill from John Day Dam occurred from April 10 to July 1; after that date, spill was 

continuous until it ceased on August 31 (fig. 6). Spill from The Dalles Dam (fig. 7) and from 

Bonneville Dam (fig. 8) was continuous from April 10 to August 31. Both Cascade Island and 

Warrendale are downstream of Bonneville Dam (see fig. 1), but Cascade Island was the only 

tailwater site with TDG levels commonly larger than 120% (fig. 9). The monitoring site at 

Warrendale had a planned shut-down from May 31 to September 20.

TH
Figure 6. Total dissolved gas saturation downstream from John Day Dam and spill from John Day Dam, Marc

September 15, 2007. (Date format = M-DD)

12 
Figure 7. Total dissolved gas saturation downstream from The Dalles Dam and spill from The Dalles Dam, M

September 15, 2007. (Date format = M-DD) 

13 
Figure 8. Total dissolved gas saturation downstream from Bonneville Dam at Warrendale and spill from Bonn

March 15 to September 15, 2007. (Date format = M-DD) 

14 
Figure 9. Total dissolved gas saturation downstream from Bonneville Dam at Cascade Island and spill from 

March 15 to September 15, 2007. (Date format = M-DD)

15
The forebay sites, John Day navigation lock (fig. 10), The Dalles forebay (fig. 11), Bonneville 

forebay (fig. 12), and Camas (fig. 13), are each 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 than the tailwater sites. Early in the 2007 

spill season, TDG levels at The Dalles Dam forebay and Bonneville forebay were occasionally larger 

than 115% saturation due to spill from upstream dams; but after May the TDG was lower. At Camas, 

however, (fig 13), TDG saturation was higher than 115% on numerous occasions from April to 

August. As documented previously (Tanner and Bragg, 2001), some of the daily increases in TDG at 

Camas may have been due to the production of oxygen by aquatic plants and to temperature increases 

due to daytime heating. 

16 
Figure 10. Total dissolved gas saturation upstream from John Day Dam, March 15 to September 15, 2007. (D

17 

Figure 11. Total dissolved gas saturation upstream from The Dalles Dam, March 15 to September 15, 2007. (D
Figure 12. Total dissolved gas saturation upstream from Bonneville Dam, March 15 to September 15, 2007. (D

Figure 13. Total dissolved gas saturation at Camas, March 15 to September 15, 2007. (Date format = M-DD) T18 
19

Comparison of Total Dissolved Gas and Temperature to 

Standards 

In 2007, there were variances or exceptions to the water-quality standard for TDG of 110% 

saturation. These variances were established 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://apps.leg.wa.gov/WAC/default.aspx?cite=173-201A-200, accessed November 15, 2007). From 

April 1 to August 31, 2007, the USACE was granted variances allowing TDG to reach 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, 

Cascade Island, 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 Administrative Code 173-201A-200(1)(f), 

http://apps.leg.wa.gov/WAC/default.aspx?cite=173-201A-200, accessed November 15, 2007). 

Although the Camas site is not located at the forebay of a dam, it is 24.4 miles downstream from 

Bonneville Dam and is regulated as a forebay site. 

The distribution of TDG values for the spill season (April 1 to August 31, 2007) is shown in 

figure 14. The applicable variance is shown with the data for each site. Data from the forebay sites 

show an increase in the median TDG (from JDY to TDA to BON to CWMW), which 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. 
Figure 14. Distributions of hourly total-dissolved-gas data and Oregon and Washington water-quality 

variances, April 1, 2007, to August 31, 2007 

Water temperature standards that apply to the lower Columbia River are complex and depend 

on the effects of human 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, at 

http://arcweb.sos.state.or.us/rules/OARs_300/OAR_340/340_041.html, accessed November 9, 2007). 

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, http://www.ecy.wa.gov/pubs/wac173201a.pdf, 

accessed November 9, 2007). 

Water temperatures upstream and downstream from John Day Dam (fig. 15), The Dalles Dam 

(fig. 16), Bonneville Dam (fig. 17), and at Camas (fig. 18) were equal to or larger than 20.0 °C 

continuously from early July until mid-September. Water temperatures at the forebay sites were 

approximately equal to the temperatures at the tailwater sites, indicating well-mixed conditions in the 

forebays. At the Camas site, (fig. 18), there was a distinct daily temperature cycle, with an amplitude 

of about 1 °C, the minimum occurring at about 09:00 hours and the maximum at about 19:00 hours. 

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Figure 15. Water temperature upstream and downstream from John Day Dam, summer 2007 

Figure 16. Water temperature upstream and downstream from The Dalles Dam, summer 2007 

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Figure 17. Water temperature upstream and downstream from Bonneville Dam, summer 2007 

Figure 18. Water temperature at Camas, summer 2007 
 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. 

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Tanner, D.Q., Johnston, M.W., and Bragg, H.M., 2002, Total dissolved gas and water temperature in 

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