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, 2006: 

Quality-Assurance Data and Comparison to WaterQuality Standards 

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

Data Series 235 

U.S. Department of the Interior 

U.S. Geological Survey 
Cover photograph: John Day Dam on the Columbia River. Water released through the dam’s spillways entrains air, increasing the downstream concentration of gasses dissolved in the water. The U.S. Army Corps of Engineers regulates spill to 

keep dissolved gasses within safe limits for fish passing through its Columbia River dams. (Photograph by Bill Johnson, U.S. 

Army Corps of Engineers.) 

ii 
U.S. Department of the Interior 

DIRK A. KEMPTHORNE, Secretary 

U.S. Geological Survey 

MARK D. MYERS, Director 

 

U.S. Geological Survey, Reston, Virginia 2006 

For product and ordering information: 

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

Telephone: 1-888-ASK-USGS 

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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., 2006, Total dissolved gas and water temperature in the 

lower Columbia River, Oregon and Washington, 2006—Quality-assurance data and comparison to water-quality standards: U.S. Geological Survey Data Series 235, 24 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.............................................................................................................................................. 9

Effects of Spill on Total-Dissolved-Gas Concentration....................................................................................... 12

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

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

Figures 

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

Washington, water year 2006. ................................................................................................................................... 2

Figure 2. Accuracy of total-dissolved-gas sensors after 3 weeks of field deployment................................ 10

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

deployment.................................................................................................................................................................. 11

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

weeks of deployment. ............................................................................................................................................... 11

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

after 3 weeks of deployment.................................................................................................................................... 11

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

April 1 to September 8, 2006..................................................................................................................................... 13 

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

Dam, April 1 to September 8, 2006 .......................................................................................................................... 14 

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

Bonneville Dam, April 1 to September 8, 2006 ...................................................................................................... 15 

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

from Bonneville Dam, April 1 to September 8, 2006............................................................................................. 16 

Figure 10. Total-dissolved-gas saturation upstream from John Day Dam, April 1 to September 8, 

2006............................................................................................................................................................................... 18 

Figure 11. Total-dissolved-gas saturation upstream from The Dalles Dam, April 1 to September 8, 

2006............................................................................................................................................................................... 18 

Figure 12. Total-dissolved-gas saturation upstream from Bonneville Dam, April 1 to September 8, 

2006............................................................................................................................................................................... 19 

Figure 13. Total-dissolved-gas saturation at Camas, April 1 to September 8, 2006....................................... 19 

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

water-quality variances, April 1, 2006, to August 31, 2006. ................................................................................ 21

Figure 15. Water temperature upstream and downstream from John Day Dam, summer 2006 ................. 22

Figure 16. Water temperature upstream and downstream from The Dalles Dam, summer 2006 ............... 22

Figure 17. Water temperature upstream and downstream from Bonneville Dam, summer 2006 ............... 23

Figure 18. Water temperature at Camas, summer 2006...................................................................................... 23

iv 
Tables 

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

year 2006........................................................................................................................................................................ 4

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

Washington, water year 2006 .................................................................................................................................... 6

Table 3. Missing or deleted data from total-dissolved-gas monitoring stations, lower Columbia River, 

Oregon and Washington, water year 2006.............................................................................................................. 7

Table 4. Exceedances of States of Oregon and Washington water-quality variances for total dissolved 

gas, lower Columbia River, Oregon and Washington, water year 2006........................................................... 20

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. 

v 
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vi 
Total Dissolved Gas and Water Temperature in the 

Lower Columbia River, Oregon and Washington, 2006: 

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 concentration and water-temperature data at 

eight stations on the lower Columbia River in 2006. Significant findings from the data include: 

• Variances to the Oregon and Washington water-quality standards for total dissolved gas were exceeded at all of the monitoring stations: Cascade Island (67 days), Camas (60 days), Bonneville 

forebay (51 days), The Dalles forebay (36 days), John Day tailwater (35 days), John Day navigation lock (20 days), The Dalles tailwater (8 days), and Warrendale (4 days). 

• From early July to the end of August 2006, water temperatures were above 20°C (degrees Celsius) 

at each of the eight lower Columbia River stations. 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 field checks of total-dissolved-gas sensors with a secondary standard were within ± (plus or 

minus) 1% saturation. All of the field checks of barometric pressure were within ±1 millimeter of 

mercury of a secondary standard, and water temperature field checks were all within ±0.2°C. 

• For the eight monitoring stations in water year 2006, an average of 99.1% of the total-dissolvedgas 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 stations. 

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 fixed total-dissolved-gas monitoring stations, lower Columbia River, Oregon and Washington, water year 2006. 

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 fixedstation monitors. Data from the lower Columbia River dams 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 every year, beginning in 1996. Current and historical TDG and watertemperature data can be found on the USGS Oregon Water Science Center Website at 

http://oregon.usgs.gov/projs_dir/pn307.tdg/. Seven reports that were published for water years 1996, 

2000, 2001, 2002, 2003, 2004, and 2005 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; and 

Tanner and others, 2005). 

To provide suitable data for managing and modeling TDG in the lower Columbia River, hourly 

data for 2006 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 database and in a USACE 

database (http://www.nwd-wc.usace.army.mil/tmt/wcd/tdg/months.html). The USACE database 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 stations, 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 2006 (October 1, 2005, to September 30, 2006) include hourly measurements of TDG pressure, barometric pressure, water 

temperature, and probe depth. Six of the stations (John Day navigation lock, John Day tailwater, The 

Dalles forebay, The Dalles tailwater, Cascade Island, and Camas) were operated from February or 

March to September 2006, which is the usual time of spill from the dams. Bonneville forebay was operated year-round and Warrendale was operated year-round except for a period of time in July and 

August when the station was placed out of service at the request of the USACE. 

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

water year 2006 

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

were determined from U.S. Geological Survey (USGS) 7.5-minute topographic maps; stations in this report are referenced by their abbreviated name or USACE station identifier, °, degree, ’, minute, ”, second] 

Map 

number 

USACE 

station 

identifier 

Columbia 

River 

mile 

USGS 

station number 

USGS station name 

(and abbreviated station name) 

Latitude and 

longitude 

Period of 

record 

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

Day navigation lock) 

45° 43’ 14” 

120° 41’ 37” 

03/07/06–

09/19/06 

2 JHAW 214.7 454249120423500 Columbia River, right bank, near 

Cliffs, Washington (John Day

tailwater) 

45° 42’ 49” 

120° 41’ 37” 

03/09/06–

09/30/06 

3 TDA 192.6 453712121071200 Columbia River at The Dalles 

Dam forebay, Washington (The 

Dalles forebay) 

45° 37’ 12” 

121° 07’ 12” 

03/08/06–

09/20/06 

4 TDDO 188.9 14105700 Columbia River at The Dalles, 

Oregon (The Dalles tailwater) 

45° 36’ 27” 

121° 10’ 20” 

03/08/06–

09/30/06 

5 BON 146.1 453845121562000 Columbia River at Bonneville 

Dam forebay, Washington (Bonneville forebay) 

45° 38’ 45” 

121° 56’ 20” 

Year-round 

until 

09/20/06 

6 CCIW 145.9 453845121564001 Columbia River at Cascade Island, Washington (Cascade 

Island) 

45° 38’ 45” 

121° 56’ 40” 

02/28/06–

09/20/06 

7 WRNO 140.4 453630122021400 Columbia River, left bank, near 

Dodson, Oregon (Warrendale) 

45° 36’ 30” 

122° 02’ 14” 

10/01/05–

07/13/06 

and 

08/30/06–

09/30/06 

8 CWMW 121.7 453439122223900 Columbia River, right bank, at 

Washougal, Washington (Camas) 

45° 34’ 39” 

122° 22’ 39” 

02/27/06–

09/21/06 

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 consists of a Hach Hydrolab water-quality probe, a Vaisala electronic barometer, a power 

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

powered by a 12-volt battery that is charged by a solar panel and/or a 120-volt alternating-current 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 database and to the USGS database. 

4 
The eight fixed-station monitors were calibrated every 3 weeks. 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 weeks). The field Hydrolab was then replaced with one 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 electronic barometer at the fixed station was 

calibrated using a portable barometer that had been recently calibrated at the National Weather Service 

facility in northeast Portland. 

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. 

The Hydrolab that was brought from the field after 3 weeks of deployment was then calibrated in 

the laboratory. The integrity of the TDG membrane was checked, the membrane was air-dried, 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 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 2006 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 similar). Values in table 2 are 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 mm Hg, divided by the barometric pressure, in mm Hg, 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, replicate qualitycontrol measurements in the river, and daily comparisons to ambient river conditions at adjacent stations. At each station, at least 97.0% of the data were received in real time by the USGS downlink and 

met quality-control checks, with an overall average of 99.1% (table 2). 

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

Washington, water year 2006 

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

Abbreviated 

Station Name 

Planned 

Monitoring 

in Hours 

Number of 

Missing or Deleted Hourly 

Values 

Percentage of Real-Time 

TDG Data Passing Quality 

Assurance 

John Day navigation lock 4,705 2 100.0 

John Day tailwater 4,931 148 97.0 

The Dalles forebay 4,702 1 100.0 

The Dalles tailwater 4,950 69 98.6 

Bonneville forebay 8,509 2 100.0 

Cascade Island 4,895 115 97.7 

Warrendale 7,610 21 99.7 

Camas 4,943 2 100.0 

Average -- -- 99.1 

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 included only TDG data. The John Day tailwater station had the most missing or deleted data. Data loss for barometric pressure in April and May at that station was caused by a faulty 

DCP, which was replaced. There were two occurrences of TDG-membrane failure at John Day tailwater; TDG data lost in those cases cannot be recovered or reconstructed. At The Dalles tailwater during 

a period in April and May, the power supply was not sufficient to enable transmission of complete data 

streams, but the data were later recovered onsite from the data logger. At Cascade Island, transmissions 

ceased for several days due to rainwater damaging the DCP, but again the data were recovered later 

and restored to the databases. 

6 
Table 3. Missing or deleted data from total-dissolved-gas monitoring stations, lower 

Columbia River, Oregon and Washington, water year 2006—continued 

[Station 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; DCP, data 

collection platform] 

Date & Time Station Parameter Reason / Notes 

3/29/06 14:00 JDY TDG Station calibration 

BP 

WT 

Depth 

4/29/06 09:00 JHAW BP DCP malfunction 

through 

5/02/06 13:00 

(intermittent) 

6/29/06 17:00 JHAW TDG Ruptured membrane 

through 

6/30/06 12:00 

7/30/06 05:00 JHAW TDG Vandalism 

through WT 

7/31/06 14:00 Depth 

9/18/06 11:00 JHAW TDG Ruptured membrane 

through 

9/19/06 17:00 

4/20/06 09:00 TDDO BP Station calibration 

4/28/06 23:00 TDDO TDG Low battery; no transmissions, but data recovered 

through BP 

5/01/06 16:00 WT 

depth 

9/08/06 06:00 TDDO BP Erroneous data 

12/19/96 16:00 BON WT Erroneous data 

3/16/06 11:00 BON TDG Erroneous data 

7
Table 3. Missing or deleted data from total-dissolved-gas monitoring stations, lower 

Columbia River, Oregon and Washington, water year 2006—continued 

[Station 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; DCP, data 

collection platform] 

Date & Time Station Parameter Reason / Notes 

3/16/06 19:00 CCIW TDG DCP got wet - no transmissions, but data recovered 

through BP 

3/21/06 11:00 WT 

depth 

3/30/06 19:00 CCIW TDG Station calibration 

BP 

WT 

depth 

5/11/06 13:00 CCIW WT Station calibration 

12/19/05 12:00 WRNO TDG No transmission 

through BP 

12/19/05 15:00 WT 

depth 

6/07/06 23:00 WRNO WT Erroneous data - faulty sensor 

6/08/06 08:00 WRNO WT Erroneous data 

6/08/06 10:00 WRNO WT Erroneous data 

6/08/06 15:00 WRNO WT Erroneous data 

6/08/06 16:00 WRNO WT Erroneous data 

6/09/06 07:00 WRNO WT Erroneous data 

6/09/06 11:00 WRNO WT Erroneous data 

6/09/06 12:00 WRNO WT Erroneous data 

6/11/06 14:00 WRNO WT Erroneous data 

6/11/06 15:00 WRNO WT Erroneous data 

6/14/06 22:00 WRNO WT Erroneous data 

6/16/06 19:00 WRNO WT Erroneous data 

6/16/06 20:00 WRNO WT Erroneous data 

6/17/06 00:00 WRNO WT Erroneous data 

6/17/06 01:00 WRNO WT Erroneous data 

6/18/06 19:00 WRNO WT Erroneous data 

6/18/06 20:00 WRNO WT Erroneous data 

6/18/06 21:00 WRNO WT Erroneous data 

6/20/06 13:00 WRNO WT Erroneous data 

8 
Table 3. Missing or deleted data from total-dissolved-gas monitoring stations, lower 

Columbia River, Oregon and Washington, water year 2006—continued 

[Station 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; DCP, data 

collection platform] 

Date & Time Station Parameter Reason / Notes 

9/13/06 21:00 WRNO TDG Ruptured membrane 

through 

9/14/06 12:00 

7/08/06 22:00 CWMW TDG Erroneous data 

BP 

WT 

depth 

8/04/06 11:00 CWMW WT Station calibration 

Quality-Assurance Data 

Data collection for TDG, barometric pressure and water temperature involves 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 2006 are presented in this 

section. 

After field deployment of the Hydrolabs for 3 weeks, the TDG sensors were calibrated in the 

laboratory. First, each 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 as measured by a calibrated barometer. Using a certified digital pressure gage as 

the primary standard, the TDG sensor was calibrated at added pressures of 100, 200, and 300 mm Hg 

above barometric pressure (113%, 126%, and 139% saturation, respectively). The accuracy of the 

TDG sensors was calculated by computing the difference between the pressure-gage 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, most of the sensor readings were within 1% saturation of the certified 

pressure gage after 3 weeks of deployment. The TDG sensor from Cascade Island produced the two 

data points more than +1% saturation off for the 126% and 139% saturation tests. It had been installed 

from February 28 to March 30, a time period when TDG was less than 120% saturation at the Cascade 

Island station. The sensor was recalibrated and performed within specifications for the remainder of 

the field season. 

9
Figure 2. Accuracy of total-dissolved-gas sensors after 3 weeks of field deployment. (Number of 

comparison values = 99.) 

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

standard instruments and the fixed-station instruments after 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 minus field instrument, were used to compare and quantify the precision between the two independent instruments. For water temperature and TDG, the measurements were made 

in-situ with the secondary standard (a recently calibrated Hydrolab) positioned alongside the field Hydrolab in the river. A hand-held barometer, calibrated every 6 to 8 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 all eight field stations. 

10 
Figure 3. Difference between the secondary standard and the field barometers after 3 weeks of deployment. (See 

figure 2 for an explanation of the box and whisker diagrams.) 

Figure 4. Difference between the secondary standard and the field temperature instruments after 3 weeks of deployment. (See figure 2 for an explanation of the box and whisker diagrams.) 

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

of deployment. (See figure 2 for an explanation of the box and whisker diagrams.) 

11
The comparisons of the hand-held barometer and the electronic field barometers are shown in 

figure 3. All of the field values are within 1 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 are within 0.2°C (degrees Celsius), and most are within 0.1°C. 

The differences between the secondary standard TDG sensor and the field TDG sensors were 

calculated following equilibration of the secondary standard unit to the site conditions before removing 

the field unit. The side-by-side equilibrium was considered complete after a minimum of 30 minutes 

when the TDG values for each sensor remained constant for 4 to 5 minutes. Most of the data show less 

than a 1% saturation difference between the two TDG sensors (fig. 5). 

The two greatest differences are +1.2% saturation at John Day navigation lock and +1.0% saturation at Cascade Island. The data point at John Day navigation lock was the final field check of the 

season (September 19) before the monitoring equipment was removed. The field instrument passed 

post-deployment calibration tests. It is possible that more equilibration time of the secondary standard 

instrument would have resulted in a lesser difference between the two instruments. The data point at 

Cascade Island was the result of the TDG sensor, mentioned above, that was shown to be out of calibration during post-deployment testing. After it was recalibrated, the sensor performed well for the 

remainder of the season. 

Effects of Spill on Total-Dissolved-Gas Concentration 

Spill from each dam increased the level of dissolved gases downstream. Spill data in this report 

are from the USACE Website (http://www.nwd-wc.usace.army.mil/tmt/wcd/tdg/months.html). Spill 

from John Day Dam occurred without significant pause from April 5 to August 31 (fig. 6). All occurrences of spill larger than 100,000 ft3

/s and most TDG values larger than 120% saturation were 

recorded before June 29. At about 70,000 ft3/s of spill, TDG begins to exceed 120% saturation. 

Spill from The Dalles Dam (fig. 7) was almost continuous from April 5 to August 31. Most occurrences of spill larger than 100,000 ft3

/s and all TDG levels larger than 120% saturation were before 

June 27. At about 90,000 ft3/s of spill, TDG begins to exceed 120% saturation. 

Spill from Bonneville Dam was almost continuous from April 4 to August 31. Most occurrences 

of spill larger than150,000 ft3/s were recorded before June 17. Both Cascade Island and Warrendale are 

downstream of Bonneville Dam (see fig. 1). TDG levels larger than 120% saturation at Warrendale 

(fig. 8) and Cascade Island (fig. 9) occurred mostly before June 14 and June 25, respectively. The 

monitoring station at Warrendale had a planned shutdown from July 13 to August 30. 

TDG at Cascade Island exceeded 120% saturation sporadically when Bonneville spill was less 

than 3,000 ft3

/s and greater than 80,000 ft3/s. At Warrendale, TDG exceeded 120% saturation when 

Bonneville spill exceeded 120,000 ft3/s. When TDG exceeded 120% saturation at Cascade Island, 

TDG only occasionally exceeded 120% saturation at Warrendale. 

12 
Figure 6. Total dissolved gas saturation downstream from John Day Dam and spill from John Day Dam, April 1 to 

September 8, 2006. (Date format = M-DD.) 

13
Figure 7.Total dissolved gas saturation downstream from The Dalles Dam and spill from The Dalles Dam, 

April 1 to September 8, 2006. (Date format = M-DD.) 

14 
Figure 8. Total dissolved gas saturation downstream from Bonneville Dam at Warrendale and spill from Bonneville 

Dam, April 1 to September 8, 2006. (Date format = M-DD.) 

15
Figure 9. Total dissolved gas saturation downstream from Bonneville Dam at Cascade Island and spill from 

Bonneville Dam, April 1 to September 8, 2006. (Date format = M-DD.) 

16 
The forebay stations, John Day navigation lock, The Dalles forebay, Bonneville forebay, and 

Camas, are each located immediately upstream of a dam, except for Camas, which is 24.4 miles downstream of Bonneville Dam. As a result, the forebay stations were expected to have lower levels of total 

dissolved gas than the tailwater stations. Early in the 2006 spill season, TDG levels at John Day navigation lock (fig. 10), The Dalles Dam forebay (fig. 11), and Bonneville Dam forebay (fig. 12) were 

often above 120% saturation due to spill from upstream dams; but after late June the TDG level was 

lower. At Camas (fig. 13), however, 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 caused by daytime heating. 

17
Figure 10. Total-dissolved-gas saturation upstream from John Day Dam, April 1 to September 8, 2006. (Date 

format = M-DD.) 

Figure 11. Total-dissolved-gas saturation upstream from The Dalles Dam, April 1 to September 8, 2006. 

(Date format = M-DD.) 

18 
Figure 12. Total-dissolved-gas saturation upstream from Bonneville Dam, April 1 to September 8, 2006. (Date 

format = M-DD.) 

Figure 13. Total-dissolved-gas saturation at Camas, April 1 to September 8, 2006. (Date format = M-DD.) 

19
Comparison of Total Dissolved Gas and Temperature to Standards 

In 2006, 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=173-201A200, accessed November 15, 2006). From April 1 to August 31, 2006, the USACE was granted variances allowing TDG to reach 115% for forebay stations (John Day navigation lock, The Dalles 

forebay, Bonneville forebay, and Camas) and 120% for tailwater stations, 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 stations 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, 2006). Although the Camas station is not located at the forebay of a dam, it is 24.4 miles downstream from 

Bonneville Dam and is regulated as a forebay station. 

The Oregon and Washington variance for TDG was exceeded at some time during water year 

2006 at all monitoring stations (table 4). The three stations with the most exceedances were all near 

Bonneville Dam. Cascade Island, below the dam, had 67 exceedances, followed by Camas, below the 

dam, (60 exceedances) and Bonneville forebay (51 exceedances). 

Table 4. Exceedances of States of Oregon and Washington water-quality variances for total 

dissolved gas, lower Columbia River, Oregon and Washington, water year 2006 

Abbreviated 

station name 

Numerical variance for 

total dissolved gas, in 

percent saturation 

Number of days 

in exceedance 

of variance 

John Day navigation lock 115 20 

John Day tailwater 120 35 

The Dalles forebay 115 36 

The Dalles tailwater 120 8 

Bonneville forebay 115 51 

Cascade Island 120 67 

Warrendale 120 4 

Camas 115 60 

The distribution of TDG values for the spill season (April 1 to August 31, 2006) is shown in figure 14. The applicable variance is shown with the data for each station, along with the number of 

exceedances of each variance. Data from the forebay stations show an increase in the median TDG 

(from JDY to TDA to BON to CWMW), which probably reflects the river’s inability to de-gas to a 

“baseline” level downstream of each dam before another dam is encountered to again cause an increase 

20 
in TDG. The number of days in exceedance at the forebay stations also shows an increase from 20 

days at JDY to 36 days at TDA to 51 days at BON to 60 days at CWMW. 

Figure 14. Distributions of hourly total-dissolved-gas data and exceedances of Oregon and 

Washington water-quality variances, April 1, 2006, to August 31, 2006. (See figure 2 for an explanation of the 

box and whisker diagrams.) 

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, modified 05/20/2004, at 

http://arcweb.sos.state.or.us/rules/OARs_300/OAR_340/340_041.html, accessed December 30, 2006). 

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, amended July 1, 2003, 

http://www.ecy.wa.gov/pubs/wac173201a.pdf, accessed November 15, 2006). 

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 the end of August. Water temperatures at the forebay stations were 

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

the forebays. At the Camas station, (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. 

21
Figure 15. Water temperature upstream and downstream from John Day Dam, summer 2006 

Figure 16. Water temperature upstream and downstream from The Dalles Dam, summer 2006 

22 
Figure 17. Water temperature upstream and downstream from Bonneville Dam, summer 2006 

Figure 18. Water temperature at Camas, summer 2006 

23
 

 References Cited 

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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, 

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the Lower Columbia River, Oregon and Washington, 2002—Quality-assurance data and comparison 

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