Technical Memorandum

Date: March 24, 2020

To: Cold Water Refuges Team

From: Martin Merz, John Palmer, and Alex Clayton

Subject: Characterization of Columbia River Temperature Variability

This memorandum discribes the lognitundinal, seasonal, interannual, vertical, and daily

temperature variation in the Lower Columbia River from the confluence with the Snake River to

the ocean.

Longitudinal Temperature Variability in the Lower Columbia River

The Columbia River is a large low-lying river, which enters the State of Washington from

Canada and warms as it moves through Washington towards the Pacific Ocean. Figure 1,

assembled with NorWeST data, illustrates this longitudinal warming in the summer month of

August when river temperatures are at their seasonal peak. When the river enters Washington,

average August river temperatures generally fluctuate between 17-18°C from year to year.

Throughout the Lower Columbia River, where the river serves as the border between

Washington and Oregon, the river fluctuates between 21-22°C. The lower section of the river is

the corridor through which all Columbia Basin adult salmon migration must begin and is the

focus of EPA’s Cold Water Refuges project.

1

Less than 15' C

- 15 .1-16.0

16 .1-17.0

17 .1-18.0

18 .1 - 19.0

19.1-20.0

20.1-21 .0

Figure 1 Current August Mean Water Temperature in the Columbia River and tributaries

(2011-2016) (DART)

Columbia River DART (DART) data from the forebay (upstream) and tailrace (downstream) of

each Lower Columbia River Dam was utilized to provide a closer look at the longitudinal

temperature regime in the Lower Columbia River (Figure 2). The August data was averaged for

the years 2011-2016. The forebay and tailrace data were already similar at any given dam but

was averaged for this analysis. Thirty-five river miles upstream of McNary Dam, the Columbia

River mixes with its largest tributary, the Snake River, which is warmer albeit smaller than the

Columbia. By the time the Columbia River reaches McNary Dam, the most upstream of the four

Lower Columbia River dams, the average August temperature is 21°C. The Columbia River then

warms by 0.5°C on average in the 80-mile pool between McNary Dam and John Day Dam. The

highest average August temperatures in the Lower Columbia River, and the whole Columbia

River for that matter, occur near the John Day Dam, reaching 21.5°C on average in August.

Temperatures then decrease slightly at The Dalles Dam and Bonneville Dam from the high

temperatures at John Day Dam (Figure 2).

2

1.6

21.5

21.4 u ~ 21.3 ::J ...., <ti .._ ~ 21.2 E ~

21.1

21

20.9 100

Lower Columbia River August Mean Temperature (2011-2016)

Bonneville Dam RM 140 21.3"(

150 200

River Mile

John Day Dam RM 214

250

McNary Dam RM 291

300

Figure 2 Longitudinal profile of the August Mean Columbia River Temperature from

McNary Dam to the Bonneville Dam (2011-2016) (DART)

Figure 3 illustrates the six-year (2011-2016) observed daily average temperatures at the tailrace

(downstream side) of the same four Columbia River dams, McNary (MCPW), John Day

(JHAW), The Dalles (TDDO) and Bonneville (WRNO). Also illustrated in Figure 3 is the 20°C

water quality standard for the whole Lower Columbia River, developed by both Washington and

Oregon to be protective of migrating salmon. Daily average temperatures typically exceed 20°C

for 2 months in a given summer on average throughout the Lower Columbia River, from the

middle of July to the middle of September. Further, temperatures exceed 21°C for one month on

average, generally the month of August, and peak close to 22°C during this time. Average

temperatures are slightly cooler at McNary Dam, due to the longitudinal warming pattern in the

Lower Columbia River visible in Figure 2, which is also observable in Figure 3.

3

~ ;;;i

23

22

21

Daily Average River Temperature at the Lower Columbia River Dams (2011-2016)

, • ! fl : •••• : . , •••••• • • • • . ,• · . .. •·. • •• II • •••••• •• I .. ······ .· . . ., .. .. ... .· .... ····•· ... I I • ••• ••• • • • • • : • • •

. . . . . . . . . ~ 20

I .-:•• ••• ·: •••• ·• ••

1!•11- • • ·······=·=· • T •••••••••••• ,, ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• , ••••• .•· .·· ··:· . (lJ

C. E {E

tt • ••• • •• I • •••• • • • • •

19

. . .. . . ,• ••••• • ♦ : • • • . . .

•• • • : ' . .... 18

17

1-Jul

. .

15-Jul 29-Jul 12-Aug Date

26-Aug 9-Sep

--McNary --John Day --The Dalles --Bonnevi lle --water Quality Standard

23-Sep

Figure 3 Lower Columbia River Temperature from early July to mid-September, 6-year

average 2011-2016 (DART)

Upstream of McNary Dam (RM 291) is the Snake River confluence with the Columbia River

(RM 325). The six-year daily average temperatures at McNary Dam (MCPW) are a function of

the Columbia River temperature in Pasco (PAQW; just upstream of the Snake confluence) and

the temperature of the smaller Snake River at Ice Harbor (IDSW; just upstream of the

confluence), in addition to any longitudinal warming between the confluence and McNary Dam.

The Snake River flow is generally close to 20% that of the Columbia River in July and August,

so the temperature of the Columbia River has a larger impact after mixing. Figure 4 illustrates

this blending, showing the Columbia River (yellow) mix with the smaller yet warmer Snake

River (blue) leading to the temperature at McNary Dam (MCPW), along with longitudinal

warming between the confluence and McNary Dam.

4

Harbor (Blue)+ Pasco (Yellow)= McNary (G reen) 2011-2016 25

··········· ::::::::::::::::::a,,,:::::•1 11• • • • • • • • • • • .-.•••• • ,-. 1 1 1 1 • •• •

1 1 I I I I It 1 1 1 t I I I 20

•:::::: ........... ··········· ············ .. • .. !::::::: . .. ::::= · ..•. ........ ···.·· ,.,.,,:::• ·

Q 15 •••••••

5

0

Jun-16 Jul-16 Aug-16 Sep-16

DATE

- 11-16 Daily Average Ice Harbor (IDSW) - 11-16 Daily Average Pasco (PAQW) - 11-16 Daily Average McNary (MCPW)

Figure 4 Influence of the Snake River (IDSW) and Columbia River as measured upstream

of the Snake confluence in Pasco (PAQW) on the Lower Columbia River as measured at

McNary Dam (MCPW) (DART)

5

[ Q.

E .. ...

22

20

18

16

1 4

12

10

8

6

4

2

0 06/ 04 06/ 18

River Environment Temperature (WQM) 10YrAvg

07/ 02 07/ 1 6 07/ 30 08/ 1 3 08/ 27 09/ 10

- Avg0S- 15:BON:tempc - Avg0S- 15:CCIW:tempc - Avg0S- 15:CWM W :tempc

www.cbr.washinqt on .edu/ dart 06 0ec 201 6 1 4 :02:29 PST

Consistent temperature measurements are limited below Bonneville Dam. Figure 5 illustrates

that 10-year daily average temperatures below Bonneville Dam at Cascade Island (CCIW) and

Camas/Washougal (CWMW) are about the same as Bonneville forebay (BON) temperatures,

suggesting very little change in river temperatures below Bonneville Dam.

Figure 5 10 year average temperature at Bonneville Dam compared with temperatures

slightly downstream at Cascade Island and Camas/Washougal (DART)

6

22

20

18

16

1 4

12

10

8

6

4

2

0 06/ 04 06/ 1 8 07/ 02

River Environment Temperature WQM

07/ 1 6 07/ 30 08/ 1 3 08/ 27

- 1998:BON:tempc - 1998:KLAW:tempc - 1997:B O N :tempc

- 1997:K L AW:tempc - 1996:BON:tempc - 1 996:KLAW :temp

09/ 1 0

www.cbr.washin ton .edu/ dart 06 Dec 2016 14:25:22 PST

Daily average temperatures further downstream at Kalama (KLAW) compared to Bonneville

forebay (BON) show very similar temperature profiles in 1996 – 1998, when temperatures were

recorded at Kalama (see Figure 6). This, along with Figure 5 above, indicates that Bonneville

Dam forebay temperatures are representative of Columbia River temperatures downstream of

Bonneville Dam.

Figure 6 1996, 1997 and 1998 average temperature at Bonneville Dam compared with

temperatures downstream at in Kalama (DART)

Seasonal and Interannual Temperature Variability in the Lower Columbia River

The figures above illustrates the temperature regime of the Columbia River averaged over

multiple years, but it is important to note that this seasonal temperature profile can look very

different between years due to different timing and magnitude of flows, different timing and

intensity of warm weather and other factors. Figure 7 shows the seasonal temperature profile

downstream of Bonneville Dam (WRNO) for 10 individual years (2009-2018), illustrating the

range that is observed in this seasonal temperature profile. These Bonneville daily average

temperatures typically reach 20°C in mid July (thick black line), rise to 21-22°C in August, and

fall below 20°C in early September.

The timing, duration and peak of warming can vary substantially year to year, and these

characteristics relative to the timing of fish runs is very important in the context of cold water

refuges. In mid-July, temperature ranged from about 17.5°C in 2011 (blue line) to 22.5°C in

2015 (red line) during this 10-year timeframe, a spread of 5°C (Figure 7). In mid-August when

7

22.5

20

17.5

E 15 <11

E ~ ii.12.5 E ~ ~

~ 10

7.5

5

2.5 \/4J 0

2009

Daily Average Columbia River Temperature Downstream of Bonneville Dam

{2009-2018)

M A M A 0

Date

N

2010 - 2011 2012 2013 2014 - 2015 2016 2017 2018 - 10-Yea, Avg. (2009-2018)

D

25

cold water refuge use is of particular importance, temperatures have less interannual variablity

ranging from 20-22°C, more reliably exceeding the 20°C water quality standard. As an

individual example year, 2015 (red line) warmed very early and peaked very early, but come the

month of August when cold water refuge use is of particular importance, 2015 more closely

matches average temperatures. The relatively cool summer of 2011 is an example of the river

warming late, only exceeding 20°C for closer to a month and peaking at a much lower

temperature than average.

Figure 7 Seasonal temperature profiles downstream of Bonneville Dam, 10-year average

2009-2018 (DART)

Difference Between the August Mean and August Maximum Temperature

Since temperatures in the Lower Columbia River typically peak in the month of August, the

August mean temperature is a common metric to characterize annual maximum temperatures in

the Lower Columbia River. To characterize the difference between the August mean

temperature and the maximum August temperature, Table 1 shows the August mean and

maximum hour temperature for the John Day Dam forebay for 2011 through 2019. As shown in

Table 1, the difference between the August mean and the maximum August hour temperature is

typically about 1.1C. Figures 8 - 11 show the August hourly temperatures for the years 2016-

8

Deg

ree

C

2019 which depict the range of hourly temperatures in the John Day Dam forebay, with the

difference between the August mean and the maximum hour typically about 1C.

Table 1 and Figures 8-11 also show that since 2013, the August mean at the John Day Dam

forebay has been around 22°C and the maximum hourly temperature has been around 23°C.

Table 1 John Day Dam Forebay August Temperatures (DART)

Year August Mean

August Maximum Hour Difference

2011 20.5 21.7 1.2

2012 20.8 22.2 1.4

2013 22.1 23.1 1.0

2014 22.1 23.2 1.1

2015 21.9 22.6 0.7

2016 21.9 23.1 1.2

2017 22.6 23.5 0.9

2018 22.2 23.2 1.0

2019 22.1 23.1 1.0

Average 21.8 22.9 1.1

20

20.5

21

21.5

22

22.5

23

23.5

John Day Dam August 2016 Forebay Temperature (C)

12

14

1

61

81

10

1

12

11

41

16

1

18

1

20

12

21

24

12

61

28

13

01

32

13

41

36

13

81

40

14

21

44

1

46

14

81

50

1

52

1

54

15

61

58

16

01

62

16

41

66

16

81

70

1

August Hours

Hourly Temperature August Mean Temperature (C)

Figure 8 John Day Dam Forebay Hourly and August Mean Temperature (2016) (DART)

9

Deg

ree

C

Deg

ree

C

21.5

21

20.5

20

19.5

19

August Hours

Hourly Temperature (C) August Mean Temperature

Figure 9 John Day Dam Forebay Hourly and August Mean Temperature (2017) (DART)

John Day Dam August 2018 Forebay Temperature (C)

23.5

23

22.5

22

1

1

21

2

1

41

61

81

10

1

12

11

41

16

1

18

1

20

12

21

24

12

61

28

13

01

32

13

41

36

13

81

40

14

21

44

1

46

14

81

50

1

52

1

54

15

61

58

16

01

62

16

41

41

61

81

10

1

12

11

41

16

1

18

1

20

12

21

24

12

61

28

13

01

32

13

41

36

13

81

40

14

21

44

1

46

14

81

50

1

52

1

54

15

61

58

16

01

62

16

41

21

21.5

22

22.5

23

23.5

24

John Day Dam August 2017 Hourly Temperature (C)

August Hours

Hourly Temperature (C) August Mean Temperature

Figure 10 John Day Dam Forebay Hourly and August Mean Temperature (2018) (DART)

10

66

1

66

1

68

1

68

1

70

1

70

1

21.5

22

22.5

23

23.5

Deg

ree

C

John Day Dam August 2019 Forebay Temperature (C)

21

20.5

20 70

0

67

0

63

9

60

9

57

8

54

7

51

7

48

6

45

6

42

5

39

7

36

6

August Hours 3

35

30

5

27

4

24

4

21

3

18

2

15

2

12

1

91

60

32

1

Hourly Temperature (C) August Mean Temperature (C)

Figure 11 John Day Dam Forebay Hourly and August Mean Temperature (2019) (DART)

Vertical Temperature Variability in the Lower Columbia River

The following figures and tables (Figures 12-24 and Tables 2 and 3) show degree to which the

reservoirs behind each the four Lower Columbia River dams have a thermal gradient or

stratification where the surface is warmer than the bottom. Figure 12 and 13 show there is very

little difference in temperature between the top and the bottom of the Bonneville Dam forebay

with no significant temperature gradient. Similarly, Figures 14 and 15 show there is very little

temperature gradient in The Dalles Dam forebay.

In contrast, Figures 16 and 17 show a significant difference temperatures gradient in the John

Day Dam forebay. Figure 17 shows the difference between the surface (5 feet depth) and near

the bottom (100-foot depth) to be in the 2.3–3.3°C (4°F-6°F) range on numerous summer days in

2018 and as high as 4°C (7-8°F) on a couple of days. As shown in Figure 16, temperatures near

the surface (5-foot depth) in the John Day forebay reached 25-25.6°C (77-78°F) on a few days in

2018, while the temperatures at 100-foot depth were in the 22°C (72-73°F) range on those days.

11

!... ., .:; C

"' ~ "' ;;. 0 ~ ::, -l! "' a. E ~ ~

"' -., ::: > -;: ::, 0 :c

75

70

65

60

55 21-May 10-Jun

Bonneville Forebay Temperature String near Bradford Island Fish Ladder

BON-Bl-1 & BON-Bl-2

- SflBl-2 -lOlt Bl-2 - 20lt81-2 - 30lt81-2

30-Jun 20-Jul 9-Aug 18-Sep 8-0ct

Bonneville Dam Bradford Island Temperature String BON-Bl-2 Hourly Water Temperature Differentials Between 5 Feet verses 30 Feet Depth

1.6

1.4

1.2

1

0.8

0.6

.1WM. 0.4

I 0.2 I}.~ l' I 0

28-0ct

~ 20-Jun 10-Jul 30-Jul 19-Aug 8-Sep 28-Sep 18-0ct

Figure 12 Bonneville Forebay Hourly Vertical Profile Temperatures Measured from the

Wall Mounted and Floating Strings near the Bradford Island Fish Ladder Exit, May 23 - October

30, 2018 (Figure 5-14 in USACE, 2019)

Figure 13 Bonneville Dam at Bradford Island Hourly Vertical Profile Temperatures

Differentials BON-BI-2 Calculated between 5 Foot and 30 Foot Depths, June 20 - October 30,

2018 (Figure 5-15 in USACE, 2019)

12

E ~ ~ .. i E .. ... ~

! .. 3: ~ ::, 0 :c

The Dalles Forebay Temperature Strings near East Fish ladder Exit

TDA-EA-1, TDA-EA-2, TDA-EA-3 75 ~ -------------------------------

70

65

60

55

22-May

0.6

0.5

E ~ 0.4

~ .J!/ !t: 0.3 0 ~ ::,

ii .. 0.

0.2

E ~ 0.1 $ i ~ 0 ::, 0 :c

.o.,

-0.2 19--Jun

- lftEA-1 - SftEA-1 - lO ftEA-1 - 60ft EA-1

- lftEA-2 - SftEA-2 - lO ft EA-2 - 38.Sft EA-2

1 ftEA-3 Sft EA-3 - lO ft EA-3 - 60ft EA-3

11-Jun 1-Jul 21-Jul 10-Aug 30-Aug 19-Sep 9-0ct

The 0dlle, FIOdtin~ Temper.ilur• Slrin~ TDA-EA-3 Hourly Wdt.r Temperature Differentials Between 5 Feet verses 60 Feet Depth

9--Jul 29--Jul 18-Ai,g 7•5ep 27•5ep 17-0ct

29-0ct

Figure 14 The Dalles Forebay Hourly Vertical Profile Temperatures Measured from the

Wall Mounted and Two Floating Strings near the East Fish Ladder Exit, May 22 - October 29,

2018 (Figure 5-8 in USACE, 2019)

Figure 15 The Dalles Forebay Hourly Vertical Profile Temperatures Differentials for

Floating String TDA-EA-3 Calculated between 5 Foot and 60 Foot Depths, June 19 - October

29, 2018 (Figure 5-9 in USACE, 2019)

13

John Day Forebay Temperature String near South Fish ladder

JDA-SS-2 80 ~--------------------------------~

75

~ ~

~ ;? ~ ., ll. E {!! ~

!!l "' :;: ~ ::, 0 J:

70

65

60

- Sft - 10ft - 20ft - 30ft - 40 ft - SOit - 60ft - 70 ft - 80ft - 90ft - lOOft

55 ~ --~---~---~--~---~---~--~---~--~~ 21-May

9

8 ii;' ~ ;;; 7

'€ ~ .. ii: 6

0 ., ~ ~

5

., Q. 4 E {!!

~ "' :;:

3

~ ::, 2 0 :z:

1

0 21~May

4-Jun 18-Jun 2-Jul 16-Jul 30-Jul 13-Aug 27-Aug 10-5ep 24-5ep

John Day Temperature String JDA-SS-2 Hourly Water Temperature Differentials Between 5 Feet and 100 Feet Depth

10-.Jun 30-Jun 20-Jul 9-Aug 29-Aug 18-Sep

Figure 16 John Day Forebay Hourly Vertical Profile Temperatures Measured from the Dam

Structure North of the South Fish Ladder Exit, May 21 - September 25, 2018 (Figure 5-2 in

USACE, 2019)

Figure 17 John Day Forebay Hourly Vertical Profile Temperatures Differentials JDA-SS-2

Calculated between 5 Foot and 100 Foot Depths, May 21 - September 25, 2018 (Figure 5-6 2 in

USACE, 2019)

14

ime O.~m l.~m 3m 5:m. 10m Bm ~Om ~Im i 00:00 24.21 23.83 21.72 21.05 20.82 20.69 20.66 20.51 01:00 23.87 23.62 21.74 21.11 20.86 20.75 20.66 20.52 02:00 23.49 23.46 21.66 21.05 20.89 20. 73 20.67 20.54 03:00 23.09 22.91 21.64 21.13 20.8S 20. 73 20.6S 20.55 04:00 22.99 23.05 21.66 21.30 20.89 20. 79 20. 70 20.56 05:00 22.77 22.87 21.71 21.06 20.89 20.79 20.6S 20.57 06:00 22.60 22.65 21.63 21.03 20.91 20.80 20.71 20.59 07:00 22.53 22.36 21.6S 21.12 20.92 20.80 20.71 20.60 08:00 22.46 22.20 21.40 21.15 21.03 20. 77 20. 70 20.61 09:00 22.65 22.17 21.33 21.13 21.04 20.82 20.74 20.62 l0:00 22.69 22.57 21.72 21.3S 20.89 20.81 20.75 20.62 11:00 23.68 22.36 21.91 21.63 20.92 20.85 20. 75 20.63 12:00 24.04 22.83 21.65 21.56 20.93 20.86 20. 76 20.64 13:00 25.34 22.73 22.25 21.55 20.92 20.84 20.75 20.66 14:00 23.45 22.7S 21.S2 20.94 20.81 20.73 20.66 15:00 16:00 17:00 18:00

23.90 22.87 21.29 20.90 20.80 20. 72 20.66 24.02 22.0S 21.39 20.89 20.83 20. 76 20.67 24.72 23.02 21.56 20.8S 20.82 20.74 20.67 24.33 22.61 21.93 20.8S 20.83 20. 76 20.67

19:00 24.54 22.62 21.43 20.85 20.80 20. 75 20.69 20:00 24.95 22.47 21.6S 20.85 20. 79 20. 77 20. 70 21:00 25.54 24.41 22.91 21.51 20.84 20.7S 20.74 20.6S 22:00 25.36 24.73 22.90 22.04 20.84 20. 79 20.75 20.6S 23:00 25. 24.8 22.60 21.81 20.91 20.79 20.78 20.68

Tables 2 and 3 show the temperature at different depths within the McNary Dam forebay on

August 1, 2015 and August 17, 2016, respectively, and show a significant temperature gradient

on these days. On August 1, 2015 (Table 2), surface temperatures reached 28°C during the late

afternoon-evening, while bottom temperatures remained below 21°C, resulting in a temperature

difference of 7°C. Similar maximum temperatures and temperature different between the surface

and the bottom occurred on August 17, 2016 (Table 3). These data show that the warmest

temperatures were in the upper 3 meters (10 feet). String data collected by the Army Corps of

Engineers demonstrates that a significant temperature gradient is a common occurrence in the

McNary Dam forebay in the summer (USACE).

For reference, the McNary forebay fixed temperature monitor recorded a daily mean of 21.2°C

on August 1, 2015 and on August 17, 2016. The fixed monitor is approximately 10 meters (30

feet) deep, so it does not capture the warmer temperatures in the upper 3 meters.

Table 2 McNary Forebay August 1, 2015(USACE String Data)

15

t 0.5m l.5m 3m 5m 10m 15m l Om l lm 00:00 JO 2$~ 23. l 22.25 21.06 20.99 20.S8 20.79 01:00 gi 25.01 23.4l 22.16 21.0l 21.01 20.90 20.81 02:00 .65 24.73 23.ll 22.24 21.09 21.00 20.88 20.82 03:00 .38 24.lO 23.67 22.18 21.12 21.04 20.91 20.84 04:00 .44 24.48 22.90 22.30 21.12 21.03 20.90 20.87 Ol:00 .23 24.31 23.l9 22.39 21.13 21.07 20.93 20.88 06:00 .13 24.17 23.62 22.Sl 21.15 21.06 20.92 20.88 07:00 .08 24.ll 23.39 22.44 21.26 21.08 20.96 20.88 08:00 .02 24.10 23.3S 22.27 21.34 21.04 20.97 20.88 09:00 .JO 24.14 23.46 22.43 21.34 21.08 20.99 20.88 10:00 .20 24.19 23.43 22.26 21.35 21.07 20.94 20.87 11:00 .40 24.35 23.70 22.25 21.15 21.07 20.95 20.87 12:00 .49 24.25 23.73 22.02 21.38 21.06 20.95 20.87 13:00 .10 24.30 23.39 22.07 21.36 21.08 20.99 20.89 14:00 .ll 24.l6 23.82 22.53 21.31 21.08 20.97 20.90 15:00 25.05 24.07 22.80 21.28 21.09 21.00 20.91 16:00 25.62 23.84 22.61 21.44 21.10 20.99 20.90 17:00 25.11 23.95 22.64 21.21 21.06 20.94 20.89 18:00 25.62 24.10 2258 21.21 21.11 20.95 20.88 19:00 25.fO 24.09 22.73 21.28 21.03 20.95 20.90 20:00 JU6 24.19 23.02 21.33 21.05 21.02 20.S9 21:00 25.19 23.82 22.82 21.29 21.09 21.00 20.91 22:00 23:00 24.10 22.83 21.18 21.11 20.98 20.93

Table 3 McNary Forebay August 17, 2016 (USACE String Data)

Figure 18 shows measured and modeled temperatures in the four different locations in the

McNary Dam forebay on August 18, 2004. Near the surface temperatures were around 25°C at

6pm and were about 22°C below 10 meters (30 feet). Figure 19 provide a model profile of the

McNary Dam forebay on August 18, 2004.

16

n ;

JO .-, ..$ 15

a ' I I) :,. -

n ;

25

,:, Field d:1la al 6:00 1,1111

o Field d:tt:t ~.12:1.1,:, pm - · - Prdicte,d ,11 (ft.10 Plll -- i>r,;-<11.ct.:<t at 12:0:•~lm

T t'UJ))enllUIC ("Cl (a~ P l

2~ 2,1 13

T t'UJ))t':t;llUI~ ("Cl (c.) P.~

O:OD hr

26

"' ... .. r>Tcilich:tlbyl>,;li1m111 ,:;r xi, (2hOX) at b:O(! pm - -- - Ptetlicletl I~ P❖Litruto Cl al C20!Jij :u.1~:(11) pm

'·' ;

10

25

'·' ;

10

25

0 t,

.r

JO

..

T t•w µem lmc ("Cl (h) P2

35~--~------------'J I

I M

2:; 2,1 T t'W))t':l<llUI~ ("Cl

(rl) P•I

26

l (ll<..): Z2,I Z2.4 Z.UI ZJ,1 23,(); ZJ.g 24.3 24.6 2S»

Figure 18 Temperature profiles at 6:00 pm and 12:00 pm for stations P1, P2, P3, and P4 in

McNary Forebay on August 18, 2004 (Yu-shi Wang et al., 2013)

Figure 19 Dissection view of vertical temperature variability in the McNary Forebay on

August 18, 2004 (M. Haque presentation of McNary Dam model and presented in Politano et al.,

2008)

17

Figures 20-25 show predicted two-dimensional temperatures in the Lower Columbia River

reservoirs on selected days based on the Army Corps of Engineers model. Consistent with the

measured data shown above, Figures 20 and 21 show significant thermal gradients in the

McNary and John Day reservoirs on July 8 and July 10, 2015, respectively. On July 8, 2015, the

McNary reservoir was modelled to exceed 26°C in McNary Dam forebay and exceed 24°C in

upper portion of the lower half of the McNary reservoir, while temperatures in the deepest part

of the reservoir were modeled to be in the 20-22°C range. On July 10, 2015, the John Day

reservoir was modelled to exceed 27°C in John Day Dam forebay and exceed 24°C in upper

portion of most of the John Day reservoir, while temperatures in the deepest part of the reservoir

were modeled to be in the 20-22°C range.

Also consistent with measured data shown above, Figures 22 and 23 show very little modelled

thermal gradient in The Dalles and Bonneville reservoirs, on July 10 and July 15, respectively.

Figures 24 and 25 show modelled temperatures for the John Day reservoir for two additional

days on August 5 and 18, 2014, respectively. Model results for August 5, 2014 (Figure 24) in

the John Day reservoir are similar to those shown for July 10, 2015 (Figure 21), with the

warmest temperatures in the forebay, warm temperatures in the upper part of the reservoir, and

cooler temperatures in the deepest part of the reservoir. On August 18, 2014 (Figure 25) the

model shows warmer temperature at the surface, especially in the forebay area, but the rest of the

reservoir at about the same temperature.

The depth of the John Day Dam forebay continuous temperature monitor reflected in Columbia

River DART is approximately 30-35 feet deep, so it reflects temperatures at approximately 1/3

the depth of the reservoir near the dam and does not reflect the warm surface temperatures. The

continuous temperature monitor at this depth, however, does appear to be a good representation

of the overall John Day reservoir temperature. For comparison, the John Day forebay monitor in

DART recorded 23.1°C on July 10, 2015 (Figure 21), 21.5°C on August 5, 2014 (Figure 24),

and 22.6°C on August 18, 2014 (Figure 25)

The above figures indicate that there is significant thermal gradient in the John Day reservoir and

the McNary reservoir during warm summer days, but there is not a thermal gradient in The

Dalles and Bonneville reservoirs. The difference in temperature in the John Day and McNary

reservoirs is greater than 2°C so the water at depth can be viewed as cold water refuge relative to

the surface temperatures on the days when the gradient exists. However, the cooler water deep

in the reservoirs near the dams is generally not 2°C cooler than the main channel temperatures

measured at the continuous monitors. Thus, the deep cooler water is not CWR relative to the

main channel. Therefore, a better characterization is that the surface of the John Day and

McNary Reservoirs warm due to warm air temperatures and solar radiation. This warming

creates a temperature gradient relative to the main channel such that during warm periods, the

top 3-5 meters (10-15 feet) is warmer than the main reservoir temperature.

18

Pool, Columbia River - RES-SIM No Action [2019-02-05] -January 1, 2011 - December 31, 2015

111 50 - - --- ---T -------T--------r---------r----------r----------1 --------[---------T-------T-_______ T ________ -r---------r -------1----------;---------T---------r--------_ T _________ i _________ T ---------! ----------r---------r---------r--------r-------r --------1 -------r-------T---------r---------T--------r--------r------- i---------r --------r--------r --------r--------r -------T---------i

, .. •••••••••·1 r 1••••••••r••••••••1 ••• r •••• 1••••••••r• r r r••••••·•r •••••• 1 •• r r••••••·•r • T r r ••••••••1 104.30 - -- ' ' ' ' ' ' ---i --- ~,,~§~~~ ---! 100.70 ---

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: : : : : : Temperature : : , : : i i : : d egC i : ;----------1-----------r----------t ---------l----------t----------r Date : 42,193.000 r----------i

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Distance (m ) 40472.35000 47384.41 000 54296.46000 61208.~000 68120.58000

Figure 20 Two-Dimensional Model of McNary Reservoir Temperatures on July 8, 2015 (USACE, 2020)

19

7.00

8 1.65

33.50 . 1200.300000 11042.750000

-J===1=~;,;~~J~---;;;;;;~~;--j__--;-;,;;;;;~~;;-~-- 1122111 2233(0.200000 108987.100000 96744.090000 84501.050000

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8

Figure 21 Two-Dimensional Model of John Day Reservoir Temperatures on July 10, 2015 (USACE, 2020)

20

.00

49 .40

I C

o 23.00

"i w

3.20

-10.00~--~---~--~---~---~--~---~--~---~---~--~---~--~---~---~--~---~--~---~--~ -988.68000 3163.TTSO0 7316.23000 11468.69000 15621.1 4000 19773.60000

Distance (m) 23926.05000 28078.51000 32230.96000 36383.42000 40535.87000

56

Figure 22 Two-Dimensional Model of The Dalles Reservoir Temperatures on July 10, 2015 (USACE, 2020)

21

.48

20.96 --

10.86 --

8 .33 --

5.8 1 --

3.28

Tempe,atu,e r---· deg C

Oate~ 42,200.000 : __ j _____ _

__ ::::::r:::::: I ~2

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___________ t ________ _

!-----------!----------~ ~~ 0.76~--~---~---~--~---~---~--~---~---~---~--~---~---~--~---~---~--~---~---~--~

-995.0 1000 6666.57000 14328. 15000 21989.73000 29651.3 1000 37312.89000

Distance (m) 4-4974.4 7000 52636.05000 60297 .63000 67959.21000 75620. 79000

23

Figure 23 Two-Dimensional Model of Bonneville Reservoir Temperatures on July 15, 2015 (USACE, 2020)

22

_00

81_65

~~·-/

1212302 00000

87

Figure 24 Two-Dimensional Model of John Day Reservoir Temperatures on August 5, 2014 (USACE, 2020)

23

.00

81.65

76.30

70.95

I = _g 60.25

~ w

54.90

49.55

John Day Pool, Columbia River - RES-SIM No Action [2019-02-05] ________ T _________ f _________ T ________ r ________ ---------T---------;----------1 January r' 2011 _. r cembl 31 , 201 r---------r -------- _________ T _________ [ _________ T _______ T ________ T _______ _ ---------r--------r--------r--------r--------- ----------r---------;----------r---------r----------r--------r---------;----------r--------- ----------r---------;----------r---------r----------( ----------------- '-----------' ---------- '-----------' ---------- ---------- '-----------' ---------- ·-----------' ---------- '-----------' ---------- ' -----------' ---------- ---------- '----------- ' - - ---- -- ' '

' ' ' ' _ L __________ .J __ _

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-1200.300000 11042.750000 23285.800000 35528.8 50000 47TT1 .890000 60014.950000

Distance (m) 722.57.990000 84501.050000 9674-4.090000 108987 .100000 121230.200000

87

Figure 25 Two-Dimensional Model of John Day Reservoir Temperatures on August 18, 2014 (USACE, 2020)

24

22.4

22.2

Q 22

QJ

:i 21.8 ... ~ ~ 21.6 E QJ I- 21.4

21.2

21

23.4 23.2

23 22.8

Q 22.6

~ 22.4 1§ 22.2 QJ

22 0..

~ 21.8 I-

21.6 21.4 21.2

21

Bonneville Forebay Daily Temperature Range

l t t +

I

t

8/15/2016 8/16/2016 8/17/2016 8/18/2016 8/19/2016 8/20/2016 8/21/2016

Date Max M in • Mean

John Day Forebay Daily Temperature Range

t t t t

8/15/2016 8/16/2016 8/17/2016 8/18/2016 8/19/2016 8/20/2016 8/21/2016

Date Max M in • Mean

Diurnal Temperature Variability in the Lower Columbia River

Figure26 and Figure 27 show the range in temperature on certain days in the Bonneville and

John Day forebays, respectively. Due to the large volume of water, there is only a small amount

of daily variation in the Columbia River temperatures. During warm periods, the difference

between the maximum and minimum temperature is less than 1°C, and typically about 0.2 – 0.5°C. Thus, there is no CWR in the Columbia River mainstem due to cooler nighttime

temperatures.

Figure 26 Bonneville Forebay Daily Temperature Range (DART)

Figure 27 John Day Forebay Daily Temperature Range (DART)

25

References

DART. Columbia River DART (Data Access in Real Time). www.cbr.washington.edu/dart.

Politano, M., Haque, M. D. M., and Weber, L. J. 2008. A numerical study of the temperature

dynamics at McNary Dam. Ecological Modelling, 212(3-4), 408-421.

[doi:10.1016/j.ecolmodel.2007.10.040]

USACE, String Data. https://pweb.crohms.org/ftppub/water_quality/tempstrings/

USACE, 2019. Lower Columbia River Dam Forebays Temperature Depth Profile Study for

2018. US Corps of Engineers. Portland District.

USACE, 2020. Model outputs provided by Dan Turner and Alexis Mills, USACE. March, 2020.

Yu-Shi WANG, Marcela POLITANO, Ryan LAUGHERY. 2013. Towards full predictions of

temperature dynamics in McNary Dam forebay using OpenFOAM. Water Science and

Engineering, 2013, 6(3): 317-330 [doi:10.3882/j.issn.1674-2370.2013.03.008]

26