P.1 

5.2.11 Flatfishes 

Table 5.2.11-4. Estimated number of adult sanddab (Citharichthys spp.) females 

(FH ) whose reproductive output was equivalent to the number of larvae entrained 

per year at Diablo Canyon Power Plant including the standard error ofthe estimate 

(SE(FH)) and 90% confidence limits (CL). 

Analysis Period 

1) Oct 23, 1996-Sep30, 1997 

2) Oct. I,1997-Sep30, 1998 

3) Jul 1, 1997-Jun30, 1998 

FH 

426 

92 

393 

SE(FH) 

996 

215 

919 

Upper 

90% CL. 

19,900 

4,320 

18,400 

Lower 

90% CL. 

9 

2 

8 

TENERA E9-055.0 

I 

5-380 Final 316(b) Demonstration 

March 1,2000 
P.2 

5.2.11 Flatfishes 

Table 5.2.11-5. Sanddabs (Citharichthys spp.): Sensitivity analysis for FH from the three 

analysis periods recalculated for each model input parameter (0): EAdj_T ± 1.645 SE(0); 

other parameters are ff.e±--645cr0) where CV(0) = 1.0 or 100%. 

a) Analysis Period 1: October 1, 1996-September 30, 1997 

Parameter 

FH 

E-Adj-T 

S larvae 

ti Eggs/yr 

Longevity 

Maturation 

Estimate 

= 426 

7,160,000 

0.623 

15,400 

6 

2.5 

Minimum 

357 

265 

82.3 

' 157 

314 

Recalculated FH 

Maximum 

495 

2,210 

2,210 

852 

1,490 

Range 

137 

1,940 

2,130 

695 

1,180 

b) Analysis Period 2: October 1,1997-September 30,1998 

Parameter 

FH 

F-Adj-T 

S larvae 

ti Eggs/yr 

Longevity 

Maturation 

Estimate 

= 92 

1,540,000 

0.623 

15,400 

6 

2.5 

Minimum 

64.0 

57.1 

17.7 

33.8 

67.6 

Recalculated FH 

Maximum 

119 

475 

475 

183 

321 

Range 

55.4 

418 

457 

150 

253 

c) Analysis Period 3: July 1, 1997-June 30, 1998 

Parameter 

FH 

E 

^Adj-T 

S larvae 

ti Eggs/yr 

Longevity 

Maturation 

Estimate 

= 393 

6,610,000 

0.623 

15,400 

6 

2.5 

Minimum 

324 

245 

75.9 

145 

290 

Recalculated FH 

Maximum 

462 

2,040 

2,040 

787 

1,380 

Range 

138 

1,790 

1,960 

642 

1,090 

TENERA E9-055.0 5-381 Final 316(b) Demonstration 

March 1.2000 
P.3 

5.2.11 Flatfishes 

Table 5.2.11-6. Estimated number of equivalent sanddab (Citharichthys spp.) adults 

(AEL ) equal to the number of larvae entrained per year at Diablo Canyon Power 

Plant including the standard error ofthe estimate (SE(AEL)) and 90% confidence 

limits (C.L.). 

Analysis Period 

Upper Lower 

AEL SE(AEL) 90% CL. 90% CL. 

1) Oct 23, 1996-Sep30, 1997 

2) Octl,1997-Sep30, 1998 

3) Jul I,1997-Jun30, 1998 

2,370 6,710 

511 1,450 

2,190 6,200 

249,000 

54,000 

18,400 

23 

Table 5.2.11-7. Sanddab (Citharichthys spp.): Sensitivity analysis for AEL from the three 

analysis periods recalculated for each model input parameter (0): EAdj_T ± 1.645 SE(0); 

other parameters are Qe±x MSCyW where CV( 0 ) = 1.0 or 100%. 

a) Analysis Period 1: October 1, 1996-September30, 1997 

Parameter 

TEL = 

E 

S early larvae 

S late larvae 

S early juvenile 

S juv. I 

S juv. II 

S juv. Ill 

S juv. IV 

S pre-recruit 

Estimate 

2,372 

162,000 

0.00241 

0.563 

0.567 

0.861 

0.859 

0.867 

0.851 

0.788 

Minimum 

1,990 

458 

458 

458 

458 

458 

458 

458 

458 

Recalculated AEL 

Maximum 

2,750 

12,300 

4,210 

4,180 

2,750 

2,760 

2,730 

2,790 

3,010 

Range 

765 

11,800 

3,750 

3,720 

2,300 

2,300 

2,280 

2,330 

2,550 

TENERA E9-055.0 5-382 Final 316(b) Demonstration 

March 1,2000 
P.4 

5.2.11 Flatfishes 

Table 5.2.11-7 (continued). Sanddab (Citharichthys spp.): Sensitivity analysis for AEL 

from the three analysis periods recalculated for each model input parameter (0): EAdhT ± 

•1.645 SE(0); other parameters are 0.e

±l <*W(6) where CV(0) = 1.0 or 100%. 

b) Analysis Period 2: October 1, 1997-September 30, 1998 

Parameter 

AEL = 

E-Adj-T 

S early larvae 

S late larvae 

S early juvenile 

S juv. I 

S juv. II 

S juv. Ill 

S juv. IV 

S pre-recruit 

Estimate 

511 

1,540,000 

0.00241 

0.563 

0.567 

0.861 

0.859 

0.867 

0.851 

0.788 

Minimum 

356 

99 

99 

99 

99 

99 

99 

99 

99 

Recalculated AEL 

Maximum 

665 

2,650 

906 

900 

593 

594 

589 

600 

648 

Range 

308 

2,550 

808 

801 

494 

496 

490 

501 

550 

TENERA E9-055.0 5-383 Final 316(b) Demonstration 

March 1,2000 
P.5 

5.2.11 Flatfishes 

Table 5.2.11-7 (continued). Sanddab (Citharichthys spp.): Sensitivity analysis for AEL 

from the three analysis periods recalculated for each model input parameter (0): EAdhT ± 

1.645 SE(9); other parameters are Q.e±\(ASCV(6) where CV(0) = 1.0 or 100%. 

c) Analysis Period 3: July, 1997-June 30, 1998 

Parameter Estimate 

AEl =2,190 

F-Adj-T 

S early larvae 

S late larvae 

S early juvenile 

S juv. I 

S juv. II 

S juv. Ill 

S juv. IV 

S pre-recruit 

6,610,000 

0.00241 

0.563 

0.567 

0.861 

0.859 

0.867 

0.851 

0.788 

Minimum 

1,810 

423 

423 

423 

423 

423 

423 

423 

423 

Recalculated AEL 

Maximum 

2,570 

11,300 

3,890 

3,860 

2,540 

2,550 

2,520 

2,570 

2,580 

Range 

768 

10,900 

3,460 

3,440 

2,120 

2,130 

2,100 

2,150 

2,360 

TENERA E9-055.0 5-384 Final 316(b) Demonstration 

March 1,2000 
P.6 

5.2.11 Flatfishes 

Table 5.2.11-8. Sanddab (Citharichthys spp.): Monthly estimates of proportional entrainment 

(PE,) and annual proportion of larvae hatched in the rth survey period (£) and associated 

standard errors (SE) used in estimating entrainment mortality for two analysis periods. 

a) Analysis Period 3: July 1, 1997-June 30, 1998 

Survey Start Date 

Jul 21, 1997 

Aug 25, 1997 

Sep 29,1997 

Oct 20, 1997 

Nov 17, 1997 

Dec 10, 1997 

Jan 22, 1998 

Feb 26, 1998 

Mar 18, 1998 

Apr 15, 1998 

May 18, 1998 

Jun 8, 1998 

PE, 

0.00291 

0.00101 

0 

0 

0 

0 

0 

0 

0 

0.859 

0 

0 

SE(PE,) 

0.000750 

0.00107 

0 

0 

0 

0 

0 

0 

0 

0.911 

0 

0 

/ 

0.645 

0.192 

0.0235 

0.00528 

0.000970 

0.0246 

0.0966 

0.00259 

0 

0.00893 

0 

0 

SE(f,) 

0.0172 

0.0127 

0.00452 

0.00200 

0.000970 

0.00516 

0.00966 

0.00116 

0 

0.00269 

0 

0 

b) Analysis Period 4: July 1, 1998-June 30, 1999 

Survey Start Date 

Jul 21, 1998 

Aug 26, 1998 

Sep 16, 1998 

Oct 6, 1998 

Nov 11, 1998 

Dec 9, 1998 

Jan 12, 1999 

Feb 3,1999 

Mar 17, 1999 

Apr 14, 1999 

May 24, 1999 

Jun 23, 1999 

PE, 

0.00115 

0.000740 

0.000540 

0.00271 

0 

0 

0 

0 

0 

0 

0.00855 

0.0430 

££(/>£,) 

0.000840 

0.000750 

0.000550 

0.00279 

0 

0 

0 

0 

0 

0 

0.00502 

0.0416 

f 

0.126 

0.0467 

0.0453 

0.128 

0 

0 

0 

0 

0 

0 

0.328 

0.327 

SE(f,) 

0.0189 

0.0112 

0.0103 

0.0167 

0 

0 

0 

0 

0 

0 

0.0277 

0.0387 

TENERA E9-055.0 5-385 Final 316(b) Demonstration 

March 1,2000 
P.7 

5.2.11 Flatfishes 

Table 5.2.11-9. Average spawn per female California halibut (Paralichthys califomicus). 

Spawning frequency is average days between spawning events for each year. Data from 

Caddell etal. (1990). 

Average number Number of eggs Spawning frequency 

Years No. spawns eggs per spawn spawned per year (d) 

1985-86' 12 455,000 5,460,000 To 

1986-87 5 313,000 1,565,000 7.2 

1987-88 13 589,000 7,657,000 14.0 

Table 5.2.11-10. Mortality rates forjuvenile California halibut (Paralichthys 

califomicus) for the 1988 year-class up to 115 d. Data from Kramer (1990) 

Length class 

(mm) 

<=10 

11-15 

16-20 

21-25 

26-30 

31-35 

35^10 

41^15 

46-50 

51-55 

56-60 

61-65 

66-70 

Age class (d) 

30.3 

43.3 

53.3 

61.8 

69.3 

76.2 

82.5 

88.4 

94.1 

99.5 

104.8 

109.9 

114.9 

(z(tj)) 

0.044 

0.016 

0.015 

0.013 

0.013 

0.013 

0.011 

0.014 

0.012 

0.011 

0.013 

0.012 

TENERA E9-055.0 5-386 Final 316(b) Demonstration 

March 1,2000 
P.8 

5.2.11 Flatfishes 

Table 5.2.11-11. Estimated total annual entrainment (ET ) and standard 

error (SE(ET )) for California halibut (Paralichthys califomicus) larvae 

from the three analysis periods. 

Analysis Period ET SE(ET) 

1) Oct 23, 1996-Sep30, 1997 

2) Octl, 1997-Sep30, 1998 

3) Jul I,1997-Jun30, 1998 

2,270,000 

14,300,000 

14,100,000 

296,000 

2,130,000 

2,130,000 

Table 5.2.11-12. Estimated total annual adjusted entrainment (EAdj_T) and 

standard error (SE(EMj_T)) for Califomia halibut (Paralichthys 

califomicus) larvae estimated for the three analysis periods. 

Analysis Period EAdi_T SE(EAdJ.T) 

1) Oct 23, 1996-Sep30, 1997 8,260,000 1,080,000 

2) Oct 1, 1997-Sep30, 1998 15,700,000 2,340,000 

3) Jul 1, 1997-Jun30, 1998 15,500,000 2,330,000 

TENERA E9-055.0 5-387 Final 316(b) Demonstration 

March 1.2000 
P.9 

5.2.11 Flatfishes 

Table 5.2.11-13. California halibut (Paralichthys califomicus): Monthly estimates of 

proportional entrainment (PE, ) and annual proportion of larvae hatched in the rth survey 

period (f) and associated standard errors (SE) used in estimating entrainment mortality for 

two analysis periods. 

a) Analysis Period 3: July 1, 1997-June 30, 1998 

Survey Start Date PE SE[PE,) f 

b) Analysis Period 4: July 1, 1998-June 30, 1999 

Survey Start Date PE, SE(PE,) f 

SE(f) 

Jul 21, 1997 

Aug 25, 1997 

Sep 29, 1997 

Oct 20, 1997 

Nov 17, 1997 

Dec 10, 1997 

Jan 22,1998 

Feb 26, 1998 

Mar 18, 1998 

Apr 15, 1998 

May 18, 1998 

Jun 8, 1998 

0.000700 

0 

0 

0 

0 

0 

0.0127 

0 

0 

0.00143 

0 

0 

0.000530 

0 

0 

0 

0 

0 

0.0155 

0 

0 

0.000650 

0 

0 

0.0186 

0.0421 

0.00283 

0 

0 

0.00425 

0.0115 

0 

0.000850 

0.761 

0.156 

0.00273 

0.00284 

0.00582 

0.00107 

0 

0 

0.00127 

0.00240 

0 

0.000600 

0.0146 

0.0109 

0.00104 

SE(f,) 

Jul 21, 1998 

Aug 26, 1998 

Sep 16, 1998 

Oct 6, 1998 

Nov 11, 1998 

Dec 9, 1998 

Jan 12, 1999 

Feb 3,1999 

Mar 17, 1999 

Apr 14, 1999 

May 24, 1999 

Jun 23, 1999 

0.00136 

0 

0 

0 

0 

0 

0 

0 

0.0751 

0.859 

0 

0 

0.000690 

0 

0 

0 

0 

0 

0 

0 

0.0372 

0.911 

0 

0 

0.0910 

0.0249 

0 

0 

0 

0 

0 

0 

0.861 

0.0227 

0 

0 

0.00984 

0.00376 

0 

0 

0 

0 

0 

0 

0.0112 

0.00392 

0 

0 

TENERA E9-055.0 5-388 Final 316(b) Demonstration 

March 1,2000 
P.10 

5.2.11 Flatfishes 

0.040 -

0.038 -

0.036 -

^ 0.034 -

yj 0.032 -

y j 0.030 ~ 

, _ 0.028 -

+ 0.026 ~ 

" 0.024 -

•5 0.022 7 

S- 0.020 ~ 

.&• 0.018 7 

W 0.016 ~ 

CD 0.014 — 

Q 0.012 -

{= 0.010 7 

0) 0.008 7 

2 0.006-

0.004 -

0.002 7 

0.000 -

T designatessurve 

s iut,i,i,ll 

|O|N|O1 J 

I

 ,096

 I 

ywithdensity=0 

I 

I 

III 

„SlJ»m„JnlJ»llll 

Sanddabs (Citharichthys spp.) 

J Wnn'rl' in 1 n?m nimmit 1 11 S 1 . . . 

|F|M|A|M|J|J|A|S|O|N|D| J |F|M|A|M|J|J|A|S[O|N|D[J| F 

1SS7 | 1898 | 

Survey Date 

..ll 

|M|A|M]J | 

lose | 

Figure 5.2.11-1. Weekly mean larval density (#/m3 + 1 S.E.) at the DCPP intake. 

TENERA E9-055.0 5-389 Final 316(b) Demonstration 

March 1,2000 
m 

z 

m 

m 

CD 

• o 

cn 

cn 

w 

CO o 

3 

!____ 

w 

_._& 

_cr 

2 ° 

-* « 

- *-* 

ts) CD 

O S. o o 

O 3 

Sanddabs (Citharichtys spp.) 

CD 

E 

0.16 

0.14 

0.12 

0.10 

0.08 

0.06 

0.04 

0.02 

0.00 

Depth Contours 

— — 20 meters 

«•—• 40 meters 

^ — 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 21/97 Aug. 25, "97 Sep. 29,'97 Oct. 20,'97 Nov. 17, *97 Dec. 10, "97 

Figure 5.2.1 l-2a. Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

0) 

3 

(A 

rT 

(0. 

il. 
P.12 

5.2.11 Flatfishes 

Q. 

Q. 

W 

s 

.CO 

CO 

O 

cn 

.O 

ro 

TJ 

XJ 

c 

ro 

CO 

^ ^? § § § § 8 

,W/# 

•I E

c5 

£ Dep 

at 

& 

"5 

E 

8 

• 1 

CO 

& 15 

E 

§ 

• 1 

CO 

s 15 

E 

s 1 1 

c 

o 

o 

_o 

OO 

c 

c 

0> 

c 

u 

U 

CJ 

•o 

•c 

oo 

£ 

cu 

CU 

u 

Q 

cu 

T3 (__> 

rrr 

o ju 

"o u 

.E 

C/5 

c 

u 

•o 

c 

ea 

r) 

•a 

e © 

«__> 

> » • 

Xl 

IN 

i 

«N 

CU 

lm 

s 

OX) 

TENERA E9-055.0 5-391 Final 316(b) Demonstration 

March 1.2000 
m 

z 

m 

m 

in 

b 

V

1 

CO 

ro 

3 

SL 

w 

—7 

a> 

ai 

•* 21 

to 3 O s: 

o o O 3 

Sanddabs (Citharichtys spp.) 

CO 

E 

0.16 

0.14 

0.12 

0.10 

0.08 

0.06 

0.04 

0.02 

0.00 

Depth Contours 

— — 20 meters 

• — 40 meters 

>^—• 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 20, '98 Aug. 25. '98 Sep. 15, '98 Oct. 5, '98 Nov 10. '98 Dec. 8, '98 

Figure 5.2.1 l-2c (continued). Mean larval density (fl/m1) collected in the DCPP study grid cells and at the entrainment sampling location. 

cn 

k> 

Vt 

3-

» 

Cfl 

'"« 
m 

z 

m 

m 

CO 

• 

o 

cn 

oi 

b 

V 

CO 

CO 

CO 

3 

0) 

CO 

__fc 

2

 D 

ir § 

r* Si 

to S 

O £: o o 

O 3 

Sanddabs (Citharichtys spp.) 

CO 

E 

0.16 

0.14 

0.12 

0.10 

0.08 

0.06 

004 

0.02 

0.00 

Depth Contours 

— — 20 meters 

— — 40 meters 

—•— 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jan. 11.'99 Feb. 2.'99 Mar. 16.' Apr. 13.'99 May 23,'99 Jun 22.'99 

Figure 5.2.U-2d (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

cn 

0) 

3 

Cfl 

3 " 

CD -

vt 

•p 
5.2.11 Flatfishes 

P.15 

Sanddabs (Citharichthys spp.) 

N=126 

1 5 — 

Occurrence 

0 

I I I I I I I 

O Frequency 

IIIII I 

Percent 

I I I I I I 

M i r 

J 

Media n 

1 % 

ub 1 

Mea n 

9 9 % 

ill, 1 I ' ' ' ' I ' ' • I ' ' • ' I ' 

1.2 1.7 2. 2 2. 7 3. 2 3. 7 4. 2 

c 

Length Category (mm) 

i • i i i • i i • i 

_> 2 4 6 8 I O 1 2 1 4 

Estimated age (days) 

1 

Ivlax 

4.7 *»W , 

1 ' II I 

1 6 •*•«* . 

Figure 5.2.11-3. Length frequency of all measured larval fish collected in the entrainment 

samples. Minimum, median, mean, maximum, and central 98% ofthe larval lengths are noted. 

X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-394 Final 316(b) Demonstration 

March 1,2000 
P.16 

5.2.11 Flatfishes 

5 5 ~ 

5 0 ~ 

4 5 ~ 

4 0 -

3 5 -

30 — 

0) 25 ~ 

o 

c 20 -

0 

^ 15 — h» 

U. 

3 10 -

o 

r. 5— o _ 

o _ 0 

•— 

o 

>. 

c -

<U 50 -

3 

O" 45 ~ 

0) -

«- 40 — 

u. 

35 — 

*-* "~ 

C 30 — 

'CD ~ 

O 25 — 

w ~ 

d) 20 ~ 

CL 

15 — 

10 — 

5 — 

— 

0 

Sanddabs (Citharichthys spp.) 

Entrainment: N=4 

MediajJ 

% 

Mir 

Mean 

99% 

Max 

1.0 6.0 11.0 16.0 21.0 26.0 31.0 36.0 41.0 46.0 

Grid: N=52 

Medi u 

1 

Min 

1 1 

1 | 

i 

" o 

Mean 

99% 

Max 

• I I ••• • •• 

,T , { , , , , | , , . , r , , , r , . , | , , , , | ,,,•!,,, , , , , , . , , , 

1.0 6.0 11.0 16.0 21.0 26.0 31.0 36.0 41.0 46.0 

Length Category (mm) 

Figure 5.2.11-4. Length frequency of measured fish from entrainment surveys that paired with 

grid surveys (both years combined). Minimum, median, mean, maximum, and central 98% ofthe 

larval lengths are noted. X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-395 Final 316(b) Demonstration 

March 1,2000 
P.17 

5.2.11 Flatfishes 

ai 

to +/- Mea

n Densit

y (#/m3 

0.024 — 

o o b b N 10 O 10 

lllllllll 

0.018-r 

0.016 — 

0.014 -z. 

0.012 ~z 

0.010-E 

0.008 -§ 

O.0O6 -= 

0.004 ~ i 

O.O02 -= 

0.000 -r 

-0.002 -E 

. -0.004 — 

Sanddab (Citharichthys spp.) 

i 

• 

L 

[ I 

• • 

• 

IIIIIIII I 

1990 1991 1992 1993 1994 1995 1996 1997 1998 

Year 

Figure 5.2.11-5. Annual mean density +/- 2 standard errors (vertical lines) and grand mean 

density for all years combined (horizontal line) for the Intake Cove surface plankton tows. The 

annual mean densities are based on seven consecutive months of data (December through June) 

except for 1990, which had only five months (February through June). 

TENERA E9-055.0 5-396 Final 316(b) Demonstration 

March 1,2000 
P.18 

5.2.11 Flatfishes 

0.40 -

o.3e -

0.3 2 -

0.2S -

0.24 -

£ 0.2 0 -

o.i e -

0.12 -

O.OS -

0.0 4 — 

"* 

P s along i 

I 

-i—i—|—l— r 

Sanddabs (Citharichthys spp.) - mean duration 

Analysis Period 3: Jul 1997-Jun 1998 

ihor a 

i i i i 

Densit y 

Extrapolate d P e 

90% Cl. 

^Pu- 0.0145 

-^""^^ ^ ^ Pu = 0.00493 ± 0.0432 

^^-^^ 

i—i—i—r-i—i—i—i—r-i—i—i—i—r— 1—i—r—i—|—i—r—i—i—|—r —i—i—i—r 1 

Ox 

O k m 

ex 

e r km 

l O x 

1 7 4 k m 

I S x 

2 6 1 k m 

2 Ox 

3 4 7 k m 

2 6 x 

4 3 4 k m 

SOx 

S 2 1 k m 

3 S x 

OOS k m 

4 0 x 

ees km 

Siz e o r Populatio n Rotativ e t o Stud y Orl d 

Equivalen t Dlstano a Alongthor a 

Sanddabs (Citharichthys spp.) - mean duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% Cl. 

Pu = 0.0663 

Pu- 0.0459 ±0.120 

Ox 

O k m 

Sx 

8 7 k m 

1 0 x 

1 7 4 k m 

1 Sx 

2 6 1 k m 

2 0 x 

3 4 7 k m 

SOx 

S 2 1 k m 

3 B x 

OOS k m 

4 0 x 

e e s k m 

Siz e o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongshor e 

Figure 5.2.11-6a. Total annual entrainment mortality ( ^ ) and 90% confidence interval (C.I.) 

as a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study 

grid (/£ ) used to approximate the alongshore extent ofthe study grid population expanded on 

the basis of alongshore current movements and die offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% CI.'s 

indicated. 

TENERA E9-055.0 5-397 Final 316(b) Demonstration 

March 1.2000 
5.2.11 Flatfishes 

P.19 

Sanddabs (Citharichthys spp.) - maximum duration 

o.eo 

O.B4 

0.48 -

0.42 -

0.3 S — 

£ 0.30 —J 

0.24 -

0.1 8 — 

0.12 -

0.06 -

o.ooAnalysis Period 3: Jul 1997-Jun 1998 

P s alongshor e 

Estimate 

90% Cl. 

-P*f = 0.0157 

Densit y 

Extrapolate d P s 

'Pu = 0.00413 ±0.0421 

2 8 x SOx SSx 40 x 

4 3 4 k m 62 1 k m OOS k m 69 5 k m 

Siz e o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongshor a 

Sanddabs (Citharichthys spp.) - maximum duration 

o.ooO.S4 ' 

0.4 8 ' 

0.42 -

0.36 ' 

0.30 -

0.24 -

0.1 8 ' 

0.1 2 " 

o.ooI 

t 

I 

I 

\ 

\ \ \ \ \ \ 

!—i—i—r -

R » alonoshor e 

j /fti = 0.0537 

>* : y 

^_L__ 

Analysis Period 4: Jul 1998-Jun 1999 

Densit y 

Extiapolate d P i 

90% Cl. 

/Pu - 0.0106 ± 0.0943 

y 

-i—i—i—i—i—i—;—r- i—i—i—i—i—i—i—i—i—i— i —i—'—r 

Ox 

O k m 

Sx 

S7 k m 

l O x 

1 7 4 k m 

1 Sx 

2 S 1 k m 

2 0 x 

3 4 7 k m 

2 Sx 

4 3 4 k m 

SOx 

S 2 1 k m 

SSx 

OOS k m 

4 0 x 

OSS k m 

Siz e o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongshor a 

Figure 5.2.11-6b. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) 

as a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study 

grid (p"s) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% C.I.'s 

indicated. 

TENERA E9-055.0 5-398 Final 316(b) Demonstration 

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P.20 

5.2.11 Flatfishes 

Morro Bay Area Landings of Sanddabs (Citharichthys spp.). 

v

 Source: PSMFC Database. 

45 -

40 -

3 5 -

3 0 -

I 20-

n 

u 

1 5 -

1 0 -

• • 

1993 1994 1995 1996 1997 1998 1999 

Year 

Figure 5.2.11-7. Commercial landings of sanddab species (Citharichthys spp.) in the Monro Bay 

area between 1993 and 1999 (Source: PSMFC Database). 

TENERA E9-055.0 5-399 Final 316(b) Demonstration 

March 1,2000 
P.21 

5.2.11 Flatfishes 

Iii 

tn 

+ 

E 

CO 

c CD 

a Mean 

0.15" 

0.14-

0.13-

0.12-

0.11 -

0.10 -

0.09-

0.08 -

0.07-

0.06 -

0.05-

0.O4-

0.03 -

0.02 -

0.01 -

o.oo -

• designatessurve. 

California halibut 

(Paralichthys califomicus) 

n"mm?i*fT"m ?~»SiVfm'!V »*»?*mnffn»n''t'» i mil*! inr*m ? mi i i i i • I 

|O|N|D| J |F|M|A|M|J|J|A|S|O|N|D| J |F|M|A[M|J|J|A|S|O|N|D[J|F|M|A| M 

| loee | iss7 | isea | 

Surve y Dat e 

.with density* 0 

SS9 

1 

1 

n i 

Figure 5.2.11-8. Weekly mean larval density (#/m3 + 1 S.E.) at the DCPP intake. 

TENERA E9-055.0 5400 Final 316(b) Demonstration 

March 1,2000 
m 

z 

m 

m 

CO 

• o 

Ol 

cn 

o 

2

 D 

O =r. 

O O 

O 3 

California halibut (Paralichthys califomicus) 

CO 

E 

0.096 

0.080 

0.064 

0.048 

0.032 

0.016 

0.000 

Point Buchon 

DCPP Intake 

Final 3 

g> 

Depth Contours 

20 meters 

— — • 40 meters 

—•••— 60 meters 

Point San Luis 

Jul. 21. "97 Aug. 25,'97 Sep. 29.'97 Oct. 20.'97 Nov. 17,'97 Dec. 10. "97 

Figure 5.2.1 l-9a. Mean larval density (ft/m1) collected in the DCPP study grid cells and at the entrainment sampling location. 

U l 

3 

vt 

3" 

CO 

ca 

ro 
m 

z 

m 

£ 

m 

CO 

• 

o 

cn 

cn 

b 

o to 

3 

0) 

CO 

CT) 

2

 a 

» g> 

§1 

-* cn ro o> 

o =•. 

o o 

o 3 

California halibut (Paralichthys califomicus) 

CO 

E 

3E 

0.096 

0.080 

0.064 

0.048 

0.032 

0.016 

0.000 

Depth Contours 

• 20 meters 

— • » 40 meters 

••• " 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jan. 22.'98 Feb. 26.'98 Mar. 18.'98 Apr. 15,'98 May 18.'98 Jun. 8.'98 

Figure 5.2.1 l-9b (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

Ul 

Tl 

Di 

3 

Vt 

3 -

CD 

Vt 

ro 
m 

z 

m 

m 

CD 

i 

o 

cn 

cn 

3 

CO 

IT 

2 O 

3 

- k CO 

. «^ . 

to 3 

O SS: 

O O 

O 3 5-403 

co 

E 

% 

0.096 

0.080 

0.064 

0.048 

0.032 

0.016 

0.000 

Depth Contours 

— — 20 meters 

— ^ 40 meters 

• — 60 meters 

California halibut (Paralichthys califomicus) 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 20, '98 Aug. 25, '98 Sep. 15, '98 Oct. 5. '98 Nov 10, '98 Dec. 8, '98 

21 Figure 5.2.1 l-9c (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

or 

k> 

at 

-X 

CO 

3 \ 

CD 

(A 

ro 
m 

z 

m 

m 

S 

en 

cn 

3 

92. 

co 

at 

CT 

?* _m 0) CD 

- k CO 

to 3 

o =r. 

o o 

o 3 

California halibut (Paralichthys califomicus) 

1 

5-404 

CO 

E 

* 

0.096 

0.080 

0.064 

0.048 

0.032 

0.016 

0.000 

Depth Contours 

— — 20 meters 

• — » 40 meters 

^ — 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jan. 11. '99 Feb. 2, '99 Mar. 16, '99 Apr. 13. '99 May 23. '99 Jun 22, '99 

Figure 5.2.1 l-9d (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

Ul 

ro 

u 

3 

CO 

3" 

<D (fl 

ro 

Ul 
P.26 

5.2.11 Flatfishes 

Califomia halibut (Paralichthys califomicus) 

N=267 

CU 

u 

c CD 

k_ 

l__ 

3 

o 

o O 

««— 

o 

>» 

u 

c d) 

3 

cr 

a> w. LL 

rf<^ 

c 

a> 

u t__ 

a> 

a. 

2 5 — 

2 0 — 

— — 

~ 

__ 

__ — 

i s — 

_ — — — — — — i o — 

mm. 

~ 

— 

~~ 

t l 11111I I ll 1 

M i n 

1 IIII,wwl w ,—Mm •JlllJl 

1 . 4 2. 4 3. 4 4. 4 S.4 6. 4 7. 4 8. 4 9. 4 

Length Category (mm) 

i—•—•—i—•—•—i—•—•—i—•—•—i—•—•—i—•—'—i—•—•—i—•—•—i—•—•— i 

O 3 6 S 12 15 I B 21 24 2 7 

Estimated age (days) 

Figure 5.2.11-9. Length frequency of all measured larval fish collected in the entrainment 

samples. Minimum, median, mean, maximum, and central 98% ofthe larval lengths are noted. 

X-axis scale is not continuous at larger lengths. 

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March 1,2000 
P.27 

5.2.11 Flatfishes 

California halibut (Paralichthys califomicus) 

Entrainment: N=9 

35" 

30" 

25" 

20" 

° 15-1 

U 

c 

• 10-J 

o 

u 

O 

Medii 

Mi 

ljan| Mean 

% 99% 

Max 

>. 

° 35" 

c 

CD 3

 30 _ 

CT 

CP 

.Y 25 "I 

C 

CD 

U 

i__. 

CD 

0. 

20 — 

15" 

Min 

1% 

Median 

Grid: N=115 

Mean 

I ' ' ' ' I ' ' ' ' I ' ' ' ' I ' ' ' ' I ' ' ^ ' I ' ' ' ' I ' ' ' ' 

1.6 2.6 3.6 4.6 5.6 6.6 7.6 

;, •••lllllllll •••-••III. 

99% 

JfE 

Max 

I ' ' ' ' I ' ' ' ' I ' ' ' • I ' ' ' ' I ' ' ' ' I 

1 . 6 2. 6 3. 6 4. 6 5. 6 6. 6 7. 6 

Length Category (mm) 

Figure 5.2.11-11. Length frequency of measured fish from entrainment surveys that paired with 

grid surveys (both years combined). Minimum, median, mean, maximum, and central 98% ofthe 

larval lengths are noted. X-axis scale is not continuous at larger lengths. 

TENERA E9-065.0 5-406 Final 316(b) Demonstration 

March 1,2000 
P.28 

5.2.11 Flatfishes 

• 

uJ 

CO 

E 

5§, Mea

n Density 

0.024 — 

0.022 ---• 

O.O20 - r 

0.01B~^ 

0.016 ~ 

O.014—f 

0.012 -z 

0.010- ^ 

O.OOS -j. 

o.ooe -= 

0.004 -z 

O.O02 ~z 

O.OOO - : 

-0.002 -= 

-0.004 — 

California halibut (Paralichthys califomicus) 

. I i , * i 

IIIIII I 

1990 1991 1992 1993 1994 1995 1996 

Year 

< 

I 

i 

1997 • 

I 

I 

I 

1998 

Figure 5.2.11-12. Annual mean density +/- 2 standard errors (vertical lines) and grand mean 

density for all years combined (horizontal line) for the Intake Cove surface plankton tows. The 

annual mean densities are based on seven consecutive months of data (December through June) 

except for 1990, which had only five months (February through June). 

TENERA E9-O55.0 5-407 Final 316(b) Demonstration 

March 1,2000 
5.2.11 Flatfishes 

P.29 

i . o — 

O.C9-

0.8 -

0.7 -

o.e -

of o.so.4 -

0.3 -

0.2 -

0 . 1 -

0.0 -

California halibut (Paralichthys califomicus) - mean duration 

Analysis Period 3: Jul 1997-Jun 1998 

R a alongsho m 

-ZA r^ i 1 

•i—i— i —;—r—i — 

Densit y 

Extrapolate d R a 

Estimate 

90% Cl. 

^Pu - 0.00269 

- ^ ^^- — Pu = 0.000835 ± 0.0323 

^ 

—1—i—i—i—i—|—i—i—r—i—i—i—i—i—i—|—i—i—i—i—i—i—i—i—i—| i i—i—i—r1 

Ox 6x lOx 15 X 20x 2fix SOx SOx 4bx 

O km 8 7 km 174 km 281k m 347K m 43 4 km 621k m 0O8 km OOS Km 

Siz e of Population Relativ e to Study Orld 

Equivalent Distanc e Alongshor e 

California halibut (Paralichthys califomicus) - mean duration 

Ra alonoaliora 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% Cl. 

Pu-- 0.175 

P* =0.123 ±0.184 

III I 

20x 

347 km 

2Sx 

4 3 4 km 

SOx 

621 km SOx 40 x 

eoe km ees km 

Siz e of Population Relative to Stua y Orld 

Equivalent Distance Alongshore 

Figure 5.2.11-13a. Total annual entrainment mortality (Pu) and 90% confidence interval (CI.) 

as a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study 

grid (/£ ) used to approximate the alongshore extent ofthe study grid population expanded on 

the basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% CI.'s 

indicated. 

TENERA E9-055.0 5-408 Final 316(b) Demonstration 

March 1,2000 
P.30 

5.2.11 Flatfishes 

1.4 0 — 

1.26 -

o.ee — 

— __. 

0.8 4 £ 0.7 0 ~ 

0.8 8 — 

0.42~ 1 

0.2 8 -i 

0.14 H 

o.ooH 

California halibut (Paralichthys califomicus) - maximum duration 

Analysis Period 3: Jul 1997-Jun 1998 

R a alonQShor e 

^ 

— i i i i I—i 

Estimate 

90% Cl. 

j Densit y 

• Extrapolata d R a 

• y Pu = 0.00449 

y Pu - 0.000763 ± 0.032J 

—i—i—i—i—i—i—i—i—|—i—i—i—i—]—i—i—i—i—|—r — T — r ' i 'y "T IIII — i — r •T-'T-T 1 

Ox 

O km 

Ox 

8 7 km 

lOx 

174 km 

1Ox 20x 

2 8 1 krrt 34 7 km 

2Sx 

4 3 4 km 

SOx 

5 21 km 

SOx 

eoe km 4 0 x 

eee km Siz e of Population Relative to Study Grid 

Equivalent Dlstano * Alongshor e 

California halibut (Paralichthys califomicus) - maximum duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% Cl. 

Pu-- 0.0525 

±0.118 

» of Population Relative to Study Orid 

Equivalent Dlstano * Alongshor e 

Figure 5.2.11-13b. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) 

as a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study 

grid (p"s) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% C.I.'s 

indicated. 

TENERA E9-055.0 5-409 Final 316(b) Demonstration 

March 1,2000 
P.31 

5.2.11 Flatfishes 

Morro Bay Area Landings of California Halibut (Paralichthys 

califomicus). Source: PSMFC Database 

60 

Figure 5.2.11-14. Commercial landings of California halibut (Paralichthys califomicus) in the 

Morro Bay area between 1993 and 1999 (Source: PSMFC Database). 

TENERA E9-055.0 5-410 Final 316(b) Demonstration 

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P.32 

Blank Page 
P.33 

6.0 Alternative Intake Technologies 

6.0 EVALUATION OF ALTERNATIVE INTAKE 

TECHNOLOGIES 

A number of cooling water technologies are explored which are currently in use elsewhere or 

proposed for use in power plant cooling water systems to minimize the loss of aquatic organisms 

due to entrainment and impingement. Section 316(b) ofthe Clean Water Act (CWA) states that 

"cooling water intake structures" are to "reflect the best technology available for minimizing 

adverse environmental impacts." As discussed in the Introduction (Section 2) of this report, 

USEPA has indicated that assessment of adverse environmental impacts (AEI) should be based A_^> 

on an evaluation of population-level effects. This report shows that Diablo Canyon Power Plant 

(DCPP) has not caused population-level effects and therefore, we concluded that DCPP has not 

caused AEI. However, we provide this section on alternative technologies in response to a 

requirement by the RWQCB. This section ofthe report includes a description of potential 

modifications to the present intake structure at DCPP. Additionally, for informational purposes, 

this section presents discussion of possible operational and technological alternatives to the 

current cooling water system that are not part ofthe intake structure although consideration of • 

these alternatives is beyond the scope ofthe CWA. 

This section evaluates the applicability of installing operational and technological alternatives 

for the existing DCPP cooling water system. For those applicable alternative technologies, we 

provide additional information relative to the potential cost of implementing the technology and 

the possible reduction of biological effects. These technologies include (1) cooling water system 

alternatives, (2) intake configuration alternatives, (3) behavioral and physical barriers, (4) fish 

collection and removal conveyance systems, and (5) intake maintenance and operational 

modifications. 

6.1 Evaluation Criteria 

A hierarchical evaluation system was used to assess which alternative intake technologies were 

initially evaluated on the basis ofthe following three criteria (Figure 6-1): 

TENERA E9-055.0 6-1 Final 316(b) Demonstration 

March 1,2000 
P.34 

6.0 Alternative Intake Technologies 

1. The alternative technology is available and proven (i.e., demonstrated operability 

and reliability at a cooling water intake similar in size and environment to the DCPP 

site). 

2. Implementation ofthe alternative technology might result in a reduction in the loss 

of aquatic organisms compared to the present operating conditions. 

3. Implementation ofthe alternative technology is applicable at the DCPP site, based 

on site-specific considerations of engineering, operations, and reliability. 

For those alternatives that meet the three criteria, a detailed evaluation of applicability and 

general cost estimate is described in Section 6-2. All technologies considered and the application 

ofthe evaluation criteria are shown in Table 6-1. 

A brief description and justification for the alternatives that do not meet Criteria 1,2, and 3 are 

presented in the attached Appendices. 

Appendix L- alternatives not meeting Criterion 1. 

Appendix M-alternatives not meeting Criterion 2. 

Appendix N-alternatives not meeting Criterion 3. 

6.2 Applicability Analysis and Cost Estimates 

This section discusses the applicability of each alternative intake technology that has met all 

three evaluation criteria. It is divided into two subsections: alternatives that reduce impingement 

and alternatives that reduce entrainment. 

For those alternatives presented in previous reports, the cost figures presented here represent 

those original estimates (TERA 1982 and PG&E 1988a) in present day dollars as of December 

1999. The annual cost and the life-of-plant cost figures presented in these earlier reports each 

consisted of two components: 1) capital, operation, and maintenance costs and 2) lost revenues. 

Other than considering the changing value of labor and material, the capital, operation, and 

maintenance costs of any ofthe alternatives was assumed not to have changed from previous 

estimates. To translate original cost estimates to present day values, we used"representative 

indices from the Bureau of Labor Statistics for labor and material. 

TENERA E9-055.0 6-2 Final 316(b) Demonstration 

March 1.2000 
P.35 

6.0 Alternative Intake Technologies 

Due to significant changes in the price of electricity since the original estimates, the lost revenue 

component was re-forecast using the same assumed lost generation (MWe) resulting from load 

reduction (deratings) and lost production, but valued using a realistic plant capacity factor and 

the California Energy Commission's forecast of Power Exchange (PX) pricing for the price of 

electricity for the next 25 yr. 

For comparative purposes, the cost of alternatives is expressed in net present value (NPV), which 

includes the total capital cost, the cost ofthe cumulative lost revenue, and increased maintenance 

costs over the life ofthe plant. Additionally, for the alternatives that reduce impingement, the 

cost per kg offish is derived by dividing the total NPV by the cumulative weight (kg) offish 

impinged for each option over the remaining licensed plant life, assumed to be 25 yr. 

The cost estimations are considered to be accurate within an order of magnitude only. More 

accurate estimates would require detailed and plant-specific design ofthe various technologies. 

For example, neither TERA (1982) nor PG&E (1988a) considered the following costs, which 

would substantially add to the current estimates: 

• Demolition and relocation of existing utilities, system components, 

plant facilities, buildings, etc. 

• Security during construction and effect on permanent security 

boundary. 

• Nuclear licensing (License Amendment Request to the NRC). 

• Permitting (i.e. California Coastal Commission, RWQCB, etc.). 

• Seismic design considerations. 

Additionally, for cooling tower cost estimations, the following additional costs were not 

considered by TERA (1982): 

• Tie-in with existing circulating water conduits. 

• Change in pumping plant location, design, and configuration. 

• New circulating water pumps (CWP) and system components. 

• Changes in the turbine and condensate systems to accommodate 

higher cooling water temperatures. 

• Salt water drift damage to existing plant facilities or structures and 

to electrical or mechanical equipment. 

TENERA E9-055.0 6-3 Final 316(b) Demonstration 

March 1,2000 
P.36 

6.0 Alternative Intake Technologies 

• Salt water drift damage to surrounding lands, terrestrial habitat and 

ecology, and agricultural productivity. 

Therefore, the cost estimates provided in this report are considered approximate, likely to be 

conservative (low) and adequate as order of magnitude estimates. 

6.2.1 Alternatives That Reduce Impingement Losses Only 

The impingement rate at DCPP is low, based on 1985-86 impingement data and ongoing field 

observations (Section 5.1.2). In the 1985-86 study (Tenera 1998a) impingement rates were 

estimated at about 0.32 to 0.73 kg/day/unit. Divers observe fishes and invertebrates freely 

moving within the intake structure forebays and directly in front ofthe traveling screens (Tenera 

1997a). Therefore, modifications to the intake structure can provide little improvement in 

reducing the number of impinged fish. The following discussion, however, provides information 

on possible alternative technologies to reduce impingement at DCPP, their estimated costs, and 

the comparison of costs to potential impingement reductions. 

6.2.1.1 Increased Area Intake Structure 

A detailed review ofthe intake velocities at DCPP (Wyman 1988), the literature on laboratory 

swimming performance of juvenile fish (reviewed in Tenera 1998a), and diver observations of 

impingement avoidance at the DCPP intake (Behrens and Larsson 1979) showed that fish 

impingement should be virtually independent of intake approach velocities of less than about 0.8 

to 1.0 fps (present velocity at DCPP). Based on studies at Contra Costa Steam Plant (Kerr 1953) 

impingement is predicted to increase at intake approach velocities greater than 1.5 fps, 

particularly among juvenile fish that are less than approximately 80 mm in length. A reduction in 

approach velocities is not expected to substantially reduce fish impingement rates at DCPP. 

However, one approach to possibly reduce impingement would be to reduce the intake approach 

velocity. The approach velocity is inversely proportional to the cross-sectional area through 

which the water passes. Therefore, velocities entering the intake structure can be reduced by 

increasing the cross-sectional area exposed to the flow. Reduction in the intake approach 

velocity would require expansion ofthe intake structure including additional traveling screens to 

TENERA E9-055.0 6-4 Final 316(b) Demonstration 

March 1,2000 
P.37 

6.0 Alternative Intake Technologies 

increase the intake's cross sectional area. A design that halves the existing approach velocity was 

considered. 

This design change assumes that reduced flow velocity translates to reduced impingement. A 

level of uncertainty exists around the use of a single parameter such as flow rate or velocity to 

accurately predict the potential for reducing impingement. Taft (1999) compares several sites 

with similar intake designs and flow characteristics that experience large differences in 

impingement. Higher rates of flow and intake velocity (through the traveling screens) are usually 

associated with higher impingement losses. Taft (1999) illustrates from the available data that 

neither'velocity nor flow appear to be closely correlated to impingement rates. He concludes that 

impingement should be viewed as a site-specific event mat is influenced by many parameters. It 

is the combinations of environmental conditions and species life stages that interact to influence 

impingement. 

Plan and section views ofthe proposed modification to the intake structure are presented in 

Figures 6-2 and 6-3. As indicated in these figures, the modification would involve expanding the 

intake structure towards the ocean side with approximately 45° flare and deepening the existing 

intake invert slab elevation to (-) 46.0 feet. 

Construction ofthe expanded intake structure would result in a major construction effort and 

require installing a cofferdam and dewatering the existing intake structure. Disruption associated 

with construction and dredging activities would contribute to localized impacts on kelp and 

benthic organisms inhabiting the Intake Cove. 

During intake construction, the circulating water flow required for the operation of Units 1 and 2 

would be disrupted, resulting in a complete loss of generating capability from both units for a 

period of approximately one year. Operating one unit while modifying the other unit would not 

change the cumulative revenue loss appreciably, because the construction duration for each unit 

would not change substantially. A major challenge to any construction project in front ofthe 

existing intake structure would be the potential for storm conditions interfering with work in the 

intake bays. 

TENERA E9-055.0 6-5 Final 316(b) Demonstration 

March 1,2000 
P.38 

6.0 Alternative Intake Technologies 

While the units are shut down, the auxiliary saltwater (ASW) system would have to remain 

operable to preserve the function of those systems necessary to maintain the plant in a safe 

shutdown mode and protect the nuclear fuel. Therefore, an extension ofthe ASW system would 

be required to provide continuous flow to the ASW pumps. Since the ASW system is a nuclear 

safety-related system, necessary safety-related design considerations such as seismic safety, 

control of heavy loads, and interaction between safety and non-safety related items would have 

to be evaluated as part of intake structure design and modification. 

Prior to finalizing the design ofthe expanded intake structure, a detailed engineering evaluation 

would be necessary to ensure compatibility between hydraulic flow patterns, cooling water 

volumes, and pressure regimes associated with the expanded intake structure and the existing 

Units 1 and 2 condenser system. License amendments required to accommodate a modification 

such as this have not been reviewed. Additionally, other environmental and safety design 

considerations such as the effects of earthquakes, tsunamis, and probable maximum loads would 

require evaluation. These would result in additional costs that have not been factored into the 

following cost estimates. 

The estimated capital cost for this project would be on the order of $51,000,000. In addition, the 

cumulative lost revenue and increased maintenance would be approximately $590,000)000 over 

the life ofthe plant. The implementation of this technology has a net present value (NPV) of 

(-) $275,000,000. This results in a cost of $61,700 to save each kilogram of impinged fish, 

assuming a 100% reduction in impingement over the remaining life ofthe plant. 

6.2.1.2 Angled Screen Intake Structure 

Angled traveling screen intakes are designed with conventional screens set at an angle to the 

incoming flow. A fish diversion system is installed at the downstream end ofthe intake such that 

incoming fish are directed along the face ofthe screens to the fish diversion path. Fish diversion 

systems include various designs of pivoting, fixed, or traveling screens, louvers, associated with 

traditional bar racks. 

TENERA E9-055.0 6-6 Final 316(b) Demonstration 

March 1,2000 
P.39 

I 

I 

I 

I 

6.0 Alternative Intake Technologies 

These intake designs have been utilized in both hydroelectric and thermal power station intakes 

to minimize impingement. At Brayton Point Station Unit 4 in Massachusetts, an 18 mo (October 

1984 to March 1986) biological evaluation was conducted to determine the species, number, and 

initial and extended survival offish diverted from the angled screen intake (Davis et al. 1988). 

The angled screen intake system had a high diversion capability and demonstrated effectiveness 

for mitigating fish impingement. Initial and extended survival varied by species; however, a 

certain group of numerically dominant taxa was classified by the authors as "fragile" (primarily, 

bay anchovy and Atlantic silverside). The fragile group had a calculated survival below 25 

percent and a "hardy" group, dominated by winter flounder and northern pipefish, had survival 

values greater than 65 percent. The diversion efficiency for all species combined was 76 percent. 

Nine ofthe top 12 taxa collected had diversion efficiencies greater than 83 percent. The 

diversion flow collections resulted in an initial survival rate of 58 percent for all taxa (n= 28,186) 

combined. The initial survival rate ranged from 6 percent for bay anchovy to nearly 100 percent 

for American eel. Initial survival with the exclusion of bay anchovy was 83 percent. Extended 

survival for all fish (n=9,209) collected at the diversion flow was 63 percent. Extended survival 

trends were similar for the major species involved. Survival ranged from a low (bay anchovy) of 

0 percent to a high over 99 percent (tautog wrasse). 

Oswego Steam Station Unit 6 utilizes an angled screen diversion system similar to the system at 

Brayton Point Station (LMS 1992). Biological studies were conducted to investigate the 

effectiveness ofthe screens as systems. Alewife (herring) and rainbow smelt made up 90 percent 

ofthe collected species (from April 1981-March 1983). Diversion efficiency was 79 percent and 

74 percent for alewife and rainbow smelt, respectively. The combined diversion efficiency for all 

the species collected was 78 percent, ranging from 53 percent for mottled sculpin to 95 percent 

for gizzard shad. Initial survival ranged from a low of 45 percent for rainbow smelt to a high of 

87 percent for emerald shiner. A total of 34,294 individuals from the seven most frequently 

collected species were examined for initial survival, and 7,534 fish were observed for latent 

survival. The lowest latent survival rate was exhibited by alewife (22 percent) while the highest 

was mottled sculpin (94 percent). Overall, the angled screen system was effective in diverting 

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6.0 Alternative Intake Technologies 

fish from the primary screenwell through the secondary screenwell back into the lake. The 

degree of effectiveness varied widely by species; size class or age, and condition ofthe 

population. 

A full-scale angled screen test facility was constructed at the Danskammer Point Generating 

Station on the Hudson River in 1981 (LMS 1985). The angled screen facility was located in the 

cooling water intake canal and consisted of two 3 m (10 ft) wide vertical traveling screens set at 

a 25 degree angle to the approach flow. The effectiveness ofthe system was evaluated over a 

three year test period (LMS 1985). Diversion efficiency ranged from 95 to 100 percent, with a 

mean of 99 percent. Species included bay anchovy, blueback herring, white perch, spottail 

shiner, alewife, Atlantic tomcod, pumpkinseed (sunfish) and American shad. Overall, system 

efficiency (diversion efficiency times initial survival times latent [96 h] survival) ranged from 68 

percent (alewife) to 99 percent (spottail shiner) with a mean of 84 percent (LMS 1985). 

Angled traveling screen intake structures have been used in a marine environment and are well 

suited for reducing impingement. Wave energy and debris loading events that occur at DCPP 

were probably not experienced at facilities that have installed these screens. Angled screen 

intakes do not prevent entrainment of larval organisms. 

One feature of angled screen intakes is that the velocities normal to the screens is quite low, on 

the order of 0.03 m/s (0.1 ft/sec) to 0.15 m/s (0.5 ft/sec) (EPRI 1999). Implementation of an 

angled screen intake at DCPP would require a major reconstruction ofthe intake to 

accommodate additional (at least twice the number currently installed) screens in the angled 

configuration. Although a specific design and cost estimate has not been prepared for this 

configuration, it is judged that the costs would be similar to the costs associated with the 

expanded area intake described in Section 6.2.1.1. Since this alternative addresses only 

impingement, the costs compared to the reported impingement rate would not make this option 

cost effective for implementation at DCPP. 

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6.2.1.3 Traveling Screen Operating Cycle Modifications and Fish 

Conveyance Systems 

Operational modifications to the vertical traveling screens, such as the use of continuous screen 

rotation, screen baskets with "fish buckets", low-pressure spraywash, and fish return sluiceways, 

are alternatives that have been proposed by the industry to increase the biological effectiveness 

of conventional vertical traveling screens. Typically, all of these elements must be used together 

to effectively reduce impingement mortality. Costs for the combination of modifications are 

presented in the section on Combinations of Vertical Traveling Screen Modifications (below). 

Continuous Traveling Screen Rotation 

Several studies have been performed to determine the effectiveness of continuous screen rotation 

on impingement survival. Studies conducted at the Pittsburg Power Plant (PG&E 1992) show 

that increasing the screen rotation frequency from 3 h intervals to continuous rotation did not 

result in consistently improved impingement survival for invertebrates such as California bay 

shrimp, brackish-water crabs, and oriental shrimp. 

In contrast, more (26-56% after 96 h) young-of-the-year (YOY) white perch (Morone 

americana) survived impingement on continuously operating traveling screens compared to 

those operated 2-4 h intermittently (19-32% survival after 96 h). Likewise, striped bass (Morone 

saxatalis) latent survival improved (32-62%) after impingement on continuously operating 

screens compared to bass impinged on intermittently operated screens (26% after 96 h; King et 

al. 1978). King et al. (1978) concluded continuous traveling screen operation allowed maximum 

initial and latent survival for white perch and striped bass YOY. 

Continuous screen rotation did not consistently result in improved impingement survival ofthe 

marine organisms examined at the Moss Landing Power Plant (PG&E 1988a, Section 4.2). 

Among impinged fish, hardy species such as plainfin midshipman and crabs had a high rate of 

survival regardless of screen rotation frequency. Increasing screen rotation frequency at the Moss 

Landing Units 6 and 7 intake did, however, contribute to a substantial increase in impingement 

survival for both surfperch and rockfish, which together constitute about 11 percent (by weight) 

ofthe fish impinged at DCPP (PG&E 1988a, Section 4.2). 

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The studies referenced above show that impingement survival varies from site to site and is 

species specific. Testing of continuous screen rotation at DCPP would be required to detennine 

if a reduction in impingement is achievable. 

The current debris removal system at DCPP is designed to handle large quantities of kelp and 

other debris. The material washed from the screens is washed to a sluiceway and directed to a 

large sump. This material and wash water is pumped to a location approximately 244 m north of 

the intake structure at the shore end ofthe west breakwater. Grinders are installed at the entrance 

to the refuse sump to reduce the size ofthe kelp and algal debris to prevent clogging ofthe debris 

removal system. No impingement survival is expected with this system. This system is needed to 

support plant operation with the high debris loads. Increasing intake screen rotation offers the 

possibility of increasing survival of some impinged organisms only if this method is used in 

conjunction with other modifications (such as a gravity sluiceway and fish baskets to increase 

survival). These configurations are described in the next two sections. 

Gravity Sluiceway Fish Return and Low Pressure Spraywash 

There are two basic types of sluiceways for the return of impinged organisms and debris to the 

waterbody: one uses a pump to transport collected material away from the intake and one uses 

gravity flow. Based on the existing DCPP intake design, a gravity return sluiceway directing 

flow to the south end ofthe intake would be the least complex and least expensive option. 

As described in the previous section, the current DCPP screenwash system is not designed to 

return impinged organisms to the receiving waterbody intact. The high debris loading 

experienced at DCPP requires that this system function in a way that makes impingement 

survival unlikely, and hence no survival of impinged organisms is expected. 

To increase impingement survival at DCPP, a separate fish return trough, low pressure spray 

wash, and fish collection baskets as described in the next section would be required. Based on 

construction estimates, the implementation of a low pressure spray wash and fish return system 

would cost about of $12,000,000. NPV analysis for this modification in conjunction with 

replacing screen baskets is included in the next section. 

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6.0 Altemative Intake Technologies 

Combinations of Vertical Traveling Screen Modifications 

Several modifications to conventional vertical traveling screens have been studied in recent years 

in an attempt to reduce the mortality of impinged organisms by incorporating new design 

features that improve the survival of impinged organisms. Such state-of-the-art modifications act 

to enhance fish and invertebrate survival related to screen impingement and spraywash removal. 

Screens modified in this manner are commonly called "Ristroph Screens". These modifications 

include the following features: 

1. Hydrodynamically improved, watertight fish collection buckets along the base of 

each screen panel to provide a holding area for organisms during screen rotation; 

2. Smooth woven mesh (e.g. 1.6 mm by 12.7 mm rectangular mesh) installed on the 

screen baskets to minimize abrasion; 

3. Lighter composite screen baskets which allow for increased rotational speed; 

4. A second sluiceway/fish return system with combined low pressure spray wash to 

transport organisms removed from the screen by the low-pressure spraywash back to 

the receiving waterbody; 

5. Improved screen-to-collection trough flap seal design; and 

6. Modifications to traveling screen bearings and motors to permit continuous rotation 

and cleaning, minimizing the time an organism is impinged on the screen. 

Studies ofthe biological effectiveness using these modified Ristoph screens was conducted at the 

Salem Generating Station on Delaware Bay in New Jersey (Ronafalvy et al. 1999; Heimbuch 

1999). An initial evaluation was performed after six ofthe 12 existing traveling water screens at 

the cooling water intake structure had been replaced with the new, improved screens, allowing a 

side-by-side comparison ofthe effectiveness ofthe old and new screens. Tests were conducted 

on 19 separate dates between June 20 and August 24, 1996. Fish collected from the old and new 

screens were held separately for observation of 48 h survival. The only species occurring in 

sufficient numbers to provide a statistically valid data analysis was juvenile weakfish (Cynoscion 

regalis; n = 1082 for the old screens, n = 1559 for the new screens). Overall, statistical analyses 

demonstrated a 48 h survival rate (uncorrected for control mortality) of 57.8 percent with the old 

screens and 79.3 percent with the new screens. 

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A second series of impingement survival studies was conducted in 1997 and 1998 to provide 

estimates of impingement survival rates with all 12 ofthe modified screens installed on Salem 

Units 1 and 2 (EPRI 1999). White perch (Morone americana) impingement survival rate 

estimates ranged from 98 percent in December to 93 percent in April. Estimates for weakfish 

ranged from 88 percent in September to 18 percent in July. For bay anchovy (Anchoa mitchilli), 

survival estimates ranged from 72 percent in November to 20 percent in July. Atlantic croaker 

(Micropogonias undulatus) survival estimates ranged from 98 percent in November to 58 

percent in April. The estimated survival for spot (Leiostomus xanthurus) was 93 percent in 

November (November was the only month in which a significant number of spot were collected). 

Alosa species (herrings) combined produced survival estimates that ranged from 82 percent in 

April to 78 percent in November. 

Impingement mortality rates for the modified screens (1997 and 1998 studies) were compared to 

mortality rates for the original screens from the 1978 to 1982 studies. Based on the comparisons, 

intake modifications were effective in improving the rates offish survival. Estimates of 

impingement mortality rates were lower for the modified screens than for corresponding 

estimates from the original screens for white perch, bay anchovy, Atlantic croaker, spot, and the 

Alosa species. 

Based on impingement survival data collected at the Diablo Canyon and Moss Landing power 

plants and at other facilities, it was concluded that operation of modified intake screens in 

combination with fish return sluiceways could enhance impingement survival of many ofthe fish 

and macroinvertebrates impinged at DCPP, including skates and rays, rockfish, sculpin, plainfin 

midshipman, tubesnouts, rock crabs, and sea urchin (PG&E 1988a). On the basis of data 

collected in the impingement survival studies (PG&E 1988a), it was estimated that losses of 

impinged fish and selected macroinvertebrates may potentially be reduced by approximately 75 

percent under conditions of intermittent rotation, assuming no incremental mortality associated 

with passage through the fish return system. Rotating intake screens continuously could reduce 

impingement losses offish and selected macroinvertebrates, assuming no incremental mortality 

resulting from passage through the fish return system. In light of DCPP's low impingement rate, 

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however, this percentage reduction will not result in an appreciable biological benefit. The 

screen improvements are not expected to provide any reduction in entrainment. 

Traveling screen modifications to reduce impingement mortality must be accompanied by a 

sluiceway designed to return organisms to the receiving waterbody. Most installations of 

modified traveling screens use a dual sluiceway return system: 1) a gravity sluiceway return 

system for impinged organisms removed from the screens by the low pressure spraywash and 2) 

another sluiceway for debris removed by the high-pressure spraywash. This type of system was 

selected for this evaluation. 

The estimated capital cost for this project would be on the order of $13,000,000. In addition, the 

cumulative lost revenue and increased maintenance would be approximately $11,000,000 over 

the life ofthe plant. The implementation of this technology has a net present value (NPV) of 

(-) $11,000,000. This results in a cost of at least $2,200 to save each kilogram of impinged fish 

assuming a 100% reduction in impingement overthe life ofthe power plant. The scope of 

implementing this alternative is expected to extend the duration of routine refueling outages, 

adding additional costs that have not been factored in to the estimates. 

6.2.2 Alternatives That Reduce Entrainment Losses 

The major focus of this study concerns losses to fish and invertebrate populations caused by 

withdrawal of larval stages. A majority ofthe young larvae are weak swimmers and cannot 

escape even very low entrainment velocities. In order to reduce entrainment, alternatives that use 

less cooling water are considered. The following discussion provides information on possible 

altemative technologies to reduce entrainment at DCPP and the estimated costs to install them. 

6.2.2.1 Closed-Cycle Cooling Towers With Saltwater Makeup 

Both mechanical and natural draft (hyperbolic) cooling towers using saltwater makeup were 

evaluated for applicability at DCPP (TERA 1982). Operational problems and environmental 

considerations (including air quality impacts from cooling tower drift and effects on vegetation 

from salt deposition) have limited the application of closed-cycle cooling where brackish water 

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or saltwater is used as a make-up source. The report concluded that no operating or proposed 

electric generating facilities in the United States use seawater in closed-cycle cooling systems. 

Since that report was written, natural draft cooling towers with saltwater makeup have been 

installed and operated at Crystal River units 4 and 5. Two cooling towers provide cooling for the 

two 750 MW coal-fired units. The towers are operated with a high blowdown rate (10%), such 

that the total saltwater demand from the ocean is reduced approximately 80 percent compared to 

a once-through system. Therefore, saltwater cooling towers, either with mechanical or natural 

draft, have been demonstrated on the scale required for a closed-loop system at DCPP. 

Based on the Crystal River experience, the use of closed-loop cooling towers with saltwater 

makeup at DCPP would reduce the cooling water flow rate by 80 percent (from 1.6 Mgpm to 

0.32 Mgpm per unit), reducing entrainment by a similar percentage. 

• • . .• .10' . . . • •. . 

Conceptual designs and design parameters for both mechanical draft (Figure 6-4) and natural 

draft cooling towers (Figure 6-5) have adverse environmental impacts on air and water quality, 

land use, and aesthetics (TERA 1982). 

• Air Quality — Would produce 37 h/yr of ground level fog, visible 

vapor plume and emit ca. 6,080-9,070 kg/d of salt drift. 

• Water Quality — Would increase salinity of cooling water discharge 

by 1.5 times, worst case; effluent limitations could be exceeded if a 

treatment system is not installed. 

• Land Use — Would require an additional 12 to 22 ha for cooling 

towers. Additionally, the terrestrial impact of salt drift would be 

significant downwind ofthe plant site, as well as to the plant 

facilities. 

• Aesthetics — For a hyperbolic (natural draft) system with two 142 

m diameter x 170 m high cooling towers, the vapor plumes could 

reach 1,000-2,000 m high. For a mechanical draft system with six 

94 m diameter x 22 m high cooling towers, the vapor plumes could 

reach 100-200 m high. 

The estimated capital cost for the hyperbolic system alternative is on the order of $658,000,000. 

In addition, the cumulative lost revenue and increased maintenance would be 

approximately (-) $454,000,000 over the life ofthe plant. The NPV of this alternative's costs 

is (-) $503,000,000. 

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Actual project costs would be higher than the estimate as the use of a closed-loop cooling system 

would require major design changes to the DCPP turbine plant. The present circulating water 

pumps (CWP) are too large to supply a cooling tower system, so new cooling tower makeup 

pumps would be required. A new set of cooling tower supply pumps of similar capacity to the 

existing circulating water pumps would have to be installed in a new pumping facility. Supply 

and return water conduits would also have to be constructed. Since the DCPP main condenser 

and turbine cycle are designed to operate with cooling water temperatures between 11 and 14°C, 

extensive redesign and retrofitting ofthe condenser and other turbine systems would be required 

to allow reliable plant operation with closed-loop cooling with a supply temperature of 26 to 

31°C. The costs of these modifications are not included in this estimate and would add 

substantially to the overall cost. 

6.2.2.2 Closed-Cycle Cooling Towers with Freshwater Makeup 

A closed-cycle cooling system using freshwater makeup is a well proven technology used at 

many different nuclear and fossil power plants on a scale similar to that required at DCPP. A 

conceptual design is outlined in this report. 

A freshwater cooling tower system would require approximately a 132,500 m3/d (92 m3/min) 

makeup water supply. This corresponds to 43-49 million m3 of freshwater per year. There is no 

supply of fresh water (including sanitary treatment plant effluent) within 40 km of DCPP 

available to supply cooling tower makeup (TERA 1982). A multistage flash distillation plant 

could supply the needed fresh water, as could a reverse osmosis system of similar capacity. Both 

flash distillation and reverse osmosis systems have been constructed on a scale needed to support 

fresh water cooling towers at DCPP. 

Environmental impacts are similar to those described for the closed-loop cooling tower with 

saltwater makeup except that the use of fresh water would reduce the emission of particulates to 

approximately 1,540 kg/d. 

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The use of freshwater cooling towers would reduce the required saltwater flow for condenser 

cooling from ca. 9.5 million m3/d (101 m3/sec) to ca. 0.4 million m3/d (5 m3/sec). This would 

reduce intake flow by 95 percent, reducing entrainment by a similar amount. 

The construction effort involved would be similar in cost to the saltwater systems described 

previously, except for the additional costs for a desalination plant of sufficient capacity to supply 

cooling tower makeup. 

The estimated capital cost for this alternative is on the order of $1,174,000,000. In addition, the 

cumulative lost revenue and increased maintenance would be approximately $1,367,000,000 

over the life ofthe plant. The net present value of this alternative's costs is (-) $1,072,000,000. 

i 

The use of saltwater or freshwater closed-loop cooling tower systems would reduce saltwater 

flow by 80 to 95%, reducing entrainment and impingement by a similar amount. Cooling tower 

technology is proven at many power plants, saltwater cooling tower operation has been 

demonstrated, and desalination plants of a size needed for freshwater cooling towers have been 

constructed. The implementation of a closed-loop system at DCPP would require a substantial 

design and construction effort. The costs of retrofitting a closed-loop system at DCPP (which 

range in net present value from (-) $503,000,000 to (-) $1,072,000,000 not including permitting 

challenges and extensive plant modifications to ensure reliable plant operation with cooling 

towers installed) would be difficult to justify, especially considering me uncertain value ofthe 

plant's electrical output as California deregulates electric generation. Although it would be 

possible to install a closed-loop cooling tower system, it is doubtful that an investment ofthe 

type described above would be viable in the current or future electrical generation market. 

6.2.2.3 Fine Mesh Screens 

Fine-mesh screening, frequently used in centerflow screens, has been investigated in laboratory 

studies to determine its potential to minimize entrainment at power plant intakes (Magliente et 

al. 1978). Application-specific studies are necessary to evaluate the survival offish eggs and 

larvae impinged on fine-mesh screens. 

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Information from laboratory tests (Tomljanovich et al. 1978) shows that traveling screens 

equipped with 1.0 mm (0.04 in) screen mesh would substantially reduce entrainment offish eggs 

and larvae at DCPP, and that entrainment of larval fish and macroinvertebrates could be virtually 

eliminated by use of 0.5 mm (0.02 in) intake screen mesh. Impingement survival for fish larvae, 

however, is species-specific: under laboratory conditions, the survival rates for larvae at 48 h 

after a 16 minute impingement on fine-mesh screens ranged from less than one percent for 

striped bass to 96 percent for bluegill and smallmouth bass (PG&E 1988a, Appendix D; 

Tomljanovich et al. 1978). The smaller intake screen mesh would increase impingement of larval 

and juvenile fish and invertebrates presently entrained at DCPP. The finer mesh screen would 

convert normally entrained organisms into impinged organisms. 

In 1980, Tampa Electric Company (TECO) performed a pilot scale evaluation of a fine-mesh 

Ristroph screen in the intake canal to its Big Bend Station on Tampa Bay, Florida (Taft et al. 

1981; Brueggemeyer et al. 1988). TECO agreed to evaluate the potential effectiveness of finemesh screens to reduce losses ofthe selected Representative Important Species: bay anchovy, 

black drum, silver perch, spotted seatrout, scaled sardine, tidewater silverside, stone crab, pink 

shrimp, American oyster, and blue crab. The screen was ofthe No-well design, a duo-flow 

screen design with the screen attached directly to the pump. Based on the positive results ofthe 

prototype testing, the regulatory agencies determined that Unit 4 could be constructed with a 

once-through condenser cooling system provided that fine-mesh screens were incorporated into 

the intake structures of both Units 3 and 4. Accordingly, six, 0.5 mm mesh No-well screens were 

installed at the station and studies of their biological effectiveness were conducted in 1985 

(Brueggemeyer et al. 1988). 

Initial and latent mortality varied by species and life stage. Collected invertebrates had mortality 

rates ranging from 10 to 35 percent. Engraulidae (primarily bay anchovy) had initial mortality 

rates ranging from 42 to 84 percent and latent mortality rates ranging from 32 to 35 percent. Bay 

anchovy, Atlantic tomcod, and Atlantic silverside eggs showed a total mortality of 72.4 percent 

(unadjusted for control). Yolk-sac larvae of mummichog, Atlantic silverside, Atlantic tomcod, 

white perch and winter flounder mortality ranged from 62 to 100 percent with the exception of 

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winter flounder, which had a projected mortality 11 to 62 percent. Assumed mortality for postyolk-sac larvae ranged from 36 to 100 percent for all species in this life stage. The conclusion of 

the study was that survival rates were comparable to, and in some cases exceeded, those obtained 

during the prototype study. There was no significant difference in survival rates between the two 

sample locations. 

Retrofitting the existing DCPP through-flow screens with a fine mesh would be difficult due to 

the increased flow resistance increasing the potential for screen failure under high debris loading. 

The size ofthe existing DCPP circulating water pumps and the intake configuration would 

preclude the retrofitting of No-well screens. No-well screens would require a new, open intake 

structure, with new circulating water pumps. 

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At Brayton Point Station Unit 4, biological evaluations were conducted to determine the number, 

species, and initial and extended survival offish impinged on the modified intake screens (Davis 

et al. 1988; LMS 1987). These fine-mesh, angled screens were installed at a new Unit 4 intake to 

divert larger, motile life stages and gently collect and recover early life stages. The lowest I 

survival was calculated for bay anchovy and the highest was for tautog. Initial and extended 

survival varied by species; however, a certain group of numerically dominant taxa was classified *• 

by the authors as "fragile" (primarily, bay anchovy and Atlantic silverside). The fragile group 

had a calculated survival below 25 percent while a "hardy" group, dominated by winter flounder 

and northern pipefish, had survival values greater than 65 percent. 

As part of an evaluation of screening technologies for DCPP (PG&E 1996), retrofitting the 

DCPP intake with center flow screens with curved baskets and a fine mesh (2mm) was 

considered as a way to improve debris filtration. The curved baskets ofthe centerflow design 

would increase flow area and offset the flow restriction caused by the finer mesh. These screens 

could be equipped with finer mesh screens (1 mm) that would potentially allow screening of 

larval organisms. These screens could reduce entrainment but would require a site-specific 

evaluation to determine the following parameters: • 

1. The survivability of larval organisms washed from the screens. 

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2. The potential increase in impingement due to the screen basket shape and the flows 

associated with a centerflow design. 

3. The ability of a fine mesh screen to function under high debris loading conditions 

experienced at DCPP. 

4. The ability ofthe refuse handling system to process debris with minimal impact to 

screened organisms. 

The estimated cost for these screens is estimated $7,000,000 (PG&E 1996). This does not 

include any modifications to the debris handling system or potential modifications to the intake 

structure to accommodate the new screens. The total cost would be approximately $10,000,000. 

The net present value of this modification is (-) $7,906,000. 

Center flow screens have a much more complex distribution of flow velocities, especially when 

installed in a screen well type intake like that used at DCPP. The entrance area to the center flow 

screen is roughly 60% as wide as the existing traveling screens, so the velocity at the screen 

entrance would be about 67% greater (1.3 to 1.7 ft/sec). The velocities at the screens are about 

70% compared to the current screen approach velocity. In between, the flow turns 90 degrees, 

resulting in a complicated flow pattern. These flow patterns could increase impingement of 

juveniles and adults. In addition, the baskets for the proposed center flow screen are convex in 

cross section, which could increase retention of any fish impinged. With the mixed survivability 

data for larval organisms impinged on fine mesh screens, any biological benefit (or cost if there 

is an increase in impingement) would have to be evaluated prior to determining the effectiveness 

of this alternative. 

6.2.2.4 Single Circulating Water Pump Operation 

A reduction in the number of operating CWP would reduce cooling water flows, proportionately 

reducing the number of organisms entrained at DCPP. 

The Diablo Canyon Power Plant is designed and operated as a base-loaded plant with relatively 

constant electrical generation for extended periods of time. The operational characteristics of 

Units 1 and 2 limit the potential effectiveness of single pump operation as an alternative for 

reducing entrainment and impingement losses. This would require extended operation at 50% 

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power, which lowers plant efficiency, reduces revenue, and degrade critical plant equipment. An 

option to running both units at 50% power levels would be to run only one unit at 100% power. 

The use of a single pump per unit at DCPP with the units operating at reduced load would also 

present certain technical operating difficulties. The motors that operate the CWP are large 

(13,000 hp) and undergo substantial stress and wear during the startup. In order to achieve 

appropriate performance ofthe unit at reduced load (e.g. at 50% power or less) or to increase 

load above 50% in response to increased demand, the second circulating water pump would be 

needed from time to time. Intermittent re-starts ofthe second pump would greatly increase the 

wear, reduce pump motor reliability, and increase the frequency of maintenance. 

A second difficulty arises directly from single pump operations. With one circulating water 

pump operating, there is no backup on-line. Thus, if the operating pump were to fail, the unit 

would undergo a forced shutdown. Ordinarily, with two circulating pumps running, failure of 

one requires a curtailment to only 50% power. Although there is no increased risk of an accident 

affecting the health and safety ofthe public by operating with one circulating water pump, plant 

operational transients that force a unit shutdown are regarded as a negative indicator by the 

Nuclear Regulatory Commission. 

Because ofthe loss of reliability, potential equipment degradation, and operational inefficiency 

of generating units that would accompany operating each unit with one circulating water pump in 

service, a more likely strategy would be to take the option of shutting down one unit and both of 

its pumps, if operation in this mode was expected to be for a long period. 

The NPV of this option is extremely negative, based on loss of generation. The lost revenue and 

NPV for this option are, however, considered proprietary information. 

This option has a negative contribution to the environment as a result ofthe need for the ISO to 

purchase replacement power for the 1,100 MW reduction in power production. It is assumed that 

the replacement power will be generated by gas-fired power plants constrained to the state of 

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California emission standards. The increased amount of emissions from a natural gas-fired power 

plant generating 1,100 MW would be as follows (tons/yr): 

NOx CO C02 

5,500 3,700 5,900,000 

NOx and CO are EPA criteria pollutants regulated under Title V ofthe Clean Air Act. C02 is a 

"green house" gas and is of concern for global warming. Additional air toxics such as 

1,3 butadiene, acroliene, and formaldehyde are generated in smaller quantities, but can represent 

a greater risk to the population and environment. These calculations are based upon emissions 

from a 750 MWe gas-fired power plant with moderate amounts of emissions controls. Emissions 

used were 95 ppm NOx, 100 ppm CO, and 9.6% C02. Mass emissions were based upon 

operation of 24 h/d, 365 d/yr. 

Because ofthe loss of generation that would accompany reduced circulating water pump 

operation, single circulating water pump operation or single unit operation is not considered an 

alternative that could reduce entrainment at DCPP in a cost effective manner. 

6.2.2.5 Variable Speed Circulating Water Pumps 

Installation of variable-speed motors on the circulating water pumps represents one approach to 

reducing cooling water flows to the minimum level necessary to maintain efficient operation of 

the unit at a specific generating load. For this analysis, the assumption is that circulating water 

flow would be reduced to that required for 100% power operation. The basis for this is that 

DCPP is designed to operate as a base loaded plant at 100% power and does not change power 

output on a daily or other scheduled basis. 

The pumps currently in use are limited to no-flow or full-flow operation. Variable-frequency 

drives could be installed to allow these pumps to operate at lower speeds (and hence lower 

flows), thereby reducing the numbers of organisms entrained. Thus, the circulating water flow 

rate could be adjusted to provide only the flow needed for condenser cooling within operating 

limits imposed by AT and back pressure operating criteria. The magnitude ofthe resultant 

TENERA E9-055.0 6-21 Final 316(b) Demonstration 

March 1,2000 
P.54 

6.0 Alternative Intake Technologies 

reductions in entrainment losses would depend on the reduction in cooling water flow and the 

abundance of organisms at the times when the circulating water pumps were operated at reduced 

flow rates. 

The intent of variable speed pumps is to reduce intake flow without impacting plant power 

operation (by adjusting circulating water flow to that needed to just allow operation within 

thermal limits) then the biological benefits of such a modification would be limited and based on 

the amount of flow reduction. DCPP was not designed for large extremes in cooling water 

ambient temperature, so there is little margin for reducing circulating flow. Based on 

calculations (VR Foster, PG&E, pers. comm. 1999), the maximum expected flow reduction 

would be 2-10% when ocean water temperatures are below the average (14.4° C). These 

calculations allowed for a temperature differential rise of 11.1° C (to allow for margin to the 

temperature limit) and did not consider the impact of condenser fouling. Further decreases in 

cooling flow would cause additional heating ofthe discharged circulating water. 

Operation ofthe existing circulating water pumps is also limited by the pumps' ability to operate 

at reduced flows without cavitating. Hydraulic model test results for the existing circulating 

water pumps revealed that the available suction head in the present installation restricts operation 

at reduced speeds without subjecting the pumps to serious cavitation. There is data for cavitation 

performance ofthe circulating water pumps at 80%, 90%, and 100% of rated speed. The data 

demonstrates that the pumps will be more susceptible to cavitation as speed is reduced. Based on 

existing data, it is estimated that the greatest flow reduction would be on the order of 20 to 30% 

(corresponding to a speed reduction of 10%; PG&E Drawing DC663021-Sht. 29). The present 

circulating water pumps are not capable of reliable service at a significantly reduced speed. Since 

the circulating water pumps are embedded in the concrete intake structure, replacement ofthe 

circulating water pumps with pumps designed for variable speed operation would require the 

construction of a new intake structure similar in size to the existing structure. Variable speed 

circulating water pumps can allow substantial reductions in cases where power plants load 

follow (change power over the course of a day or week) and where plants are designed for large 

variations in heat sink temperatures. Since DCPP is a base loaded plant designed for a relatively 

TENERA E9-055.0 6-22 Final 316(b) Demonstration 

March 1,2000 
PP""" 

6.0 Alternative Intake Technologies 

constant heat sink temperature, there is littie flow reduction that can be expected (up to 10%). 

This limits the biological benefit of installing variable speed drives on the existing pumps. Since 

variable speed drives of a size needed are not normally produced, the costs for this modification 

are difficult to estimate. Based on input from one experienced vendor, the net present value of 

installing variable frequency power units would be approximately (-) $7,652,000. 

Due to the low reduction in flow and relatively high (and uncertain) costs to install these drives, 

the minimal reduction in entrainment is not considered to provide a substantia] biological 

benefit. 

6.2.2.6 Refueling Outage Scheduling 

Diablo Canyon Power Plant Units 1 and 2 are periodically removed from service for refueling 

and maintenance. The unit outages occur at an interval of approximately 18 mo. Future outages 

are expected to last approximately 30 d. The seasonal planned reduction alternative would 

involve the selective scheduling of unit outages to coincide with the peak periods of abundance 

for key larval taxa in the area. Ideally, refueling outages would be scheduled for specific times of 

the year when densities of entrained organisms are greatest. 

Over the past 15 years the majority ofthe 18 refueling outages have occurred during the months 

of March-April (7 outages) and September-October (5 to 8 outages). Fall outages have occurred 

regularly during these months, but in recent years winter outages started earlier, running from 

February-March. Ofthe 14 target taxa including subgroups, the majority reproduce during the 

spring months of March-June (Table 6-2). Few of these taxa are vulnerable as larvae during fall. 

A shift in outage scheduling to the spring would lessen the susceptibility of these larvae to 

entrainment. Having both units refuel each spring is highly uneconomical. Extending each unit to 

a 24 mo cycle would allow for spring outages, but is not possible with current fuel design. 

During the normal operational cycle about one-third ofthe fuel is consumed over an 18-21 mo 

period before refueling is required. This limits the possibility of modifying outage schedules to a 

shorter duration. Without the ability to lengthen fuel cycles, outages could not be scheduled only 

TENERA E9-055.0 6-23 Final 316(b) Demonstration 

March 1,2000 
P.56 

6.0 Alternative Intake Technologies 

during the spring. Without this flexibility, shortening outage schedules to occur on 12 month 

intervals would become inefficient. 

A second scenario of reduced operation could involve curtailments during periods of greater 

larval density. Monthly densities offish larvae peak during the spring months from March 

through June, as depicted for 1997 and 1998 in (Figure 6-6). During the months March -May 

approximately 55% ofthe fish larvae for the nine months ending in September are at risk to 

entrainment. This nine month period was used because plankton data after September 1998 were 

analyzed only once-per-month with paired study grid surveys. During both years, larval densities 

peak in May each year when 23 and 31 percent of larvae were collected. These strategies would 

be protective of many species including KGB rockfish (Sebastes spp. VJDe), northern anchovy, 

monkeyface eel, Pacific sardine, northern lampfish, smoothhead sculpin, white croaker, and 

California halibut. Spring time curtailments, however, would not be protective of other fishes 

including clinid kelpfish, blackeye goby, blue rockfish (Sebastes spp. V), snubnose sculpin, and 

some KGB rockfish (Sebastes spp. VD) . 

A dual unit curtailment for a three month period each spring would have a significantly negative 

financial impact on PG&E. The NPV of this option is extremely negative, based on loss of 

generation. The lost revenue and NPV for this option are, however, considered proprietary 

information. Replacement power obtained from gas-fired facilities would generate about onehalf the EPA criteria pollutants and "green house" gas emissions calculated in Section 6.2.2.4 

each year under this scenario. 

6.2.3 Conclusion 

A hierarchical evaluation was used to assess which alternative intake technologies were 

technically feasible and could reduce impingement and entrainment at DCPP. 

A reassessment ofthe 1985-86 316(b) Demonstration Study (Tenera 1998a) confirmed that 

estimated impingement at DCPP is very low (0.32 to 0.73 kg/d/unit). The current report found 

that, for any type of modification, very little improvement can be made to the present DCPP 

TENERA E9-055.0 6-24 Final 316(b) Demonstration 

March 1,2000 
6.0 Alternative Intake Technologies 

intake configuration to reduce the number of impinged fish, without incurring substantial costs 

relative to the benefit achieved. Regardless, Section 6-2 of this report studied the feasibility of 

three alternative technologies: an increased area intake, angled screen intake, and modified 

traveling screens with enhanced fish handling equipment. 

Increasing the cross-sectional area ofthe intake structure would decrease the water flow rate. 

But, apparently healthy juvenile and adult fish have been observed living and swimming inside 

the intake structure at DCPP without being impinged. Also, implementing this altemative would 

require very substantial disruption ofthe intake cove as a cofferdam would be required to dewater the cove while dredging and associated modifications took place. The angled screen intake 

design is judged to have similar costs and benefits as the increased area intake, with the potential 

for increase fish recovery. 

The cost of implementing either the increased area intake or the angled screen intake alternatives 

is estimated to have a net present value of approximately (-)$275,000,000. This equates to 

approximately $61,700 per kilogram offish saved, assuming the modification could completely 

eliminate impingement. 

Due to the high cost as well as the high impact to the Intake Cove during construction and 

negligible reduction in impingement, these alternative intake technologies are not considered 

cost effective for DCPP. 

Applicability ofthe most current intake screen and fish conveyance technologies were evaluated. 

Proposed modifications to the existing configuration include the addition of angled intake 

screens, watertight fish collection buckets, low pressure spray .wash, a gravity sluiceway to 

convey fish back to the ocean, and modifications to the screens to allow continuous rotation. 

None ofthe organisms impinged on the screens at DCPP are assumed to survive because ofthe 

current debris removal configuration. Installation of a gravity sluiceway and low pressure spray 

wash could reduce the mortality rate of impinged organisms. 

Although there is insufficient data to perform a thorough site-specific analysis, modified angled 

traveling screens with continuous rotation, low pressure spray wash, and watertight fish 

TENERA E9-055.0 6-25 Final 316(b) Demonstration 

March 1,2000 
P.58 

6.0 Alternative Intake Technologies 

collection buckets have the potential to reduce the mortality of impinged organisms at DCPP. 

Implementation of this modification has associated capital and maintenance costs resulting in a 

net present value (NPV) of (-)$11,000,000. The cost of saving impinged fish with this 

modification, assuming 100% survival, is on the order of $2,200 per kg of impinged fish 

assuming a 100% reduction in impingement. Site-specific testing of this proposed modification 

would be required to determine the actual biological benefit. 

Because impingement at DCPP is already low, modification ofthe current traveling screens to 

further reduce impingement is not considered cost effective for DCPP. 

For entrainment, five alternative technologies have been identified as technically feasible at 

DCPP. The alternatives are closed-cycle cooling towers, fine mesh screens, single circulating 

water pump operation, variable speed circulating water pumps, and changes to refueling outage 

scheduling. 

Two types of closed-cycle cooling towers were evaluated. Both would reduce the cooling water 

requirement, possibly as much as 80-95%, and result in entrainment reductions. However, 

installation and operation of closed-cycle cooling towers have negative environmental impacts 

on air quality (salt drift), increased salinity ofthe cooling water discharge, terrestrial impacts of 

salt drift, and poor aesthetics as a consequence of high cooling towers and vapor plumes. 

Additionally, closed-cycle cooling towers have high capital and maintenance costs. Both units 

would be de-rated to accommodate the new cooling medium. Order of magnitude estimated net 

present values (NPV) range from (-) $503,000,000 to (-) $1,072,000,000, plus costs for design, 

licensing, demolition of existing facilities, and environmental damage to the land. Because ofthe 

adverse terrestrial environmental impacts and high implementation costs associated with closecycle cooling towers, they are not considered feasible at DCPP 

Center flow screens with fine mesh (1 mm) baskets could be retrofitted to the existing DCPP 

intake structure to allow screening of larvae. Studies have shown wide ranging mortality rates for 

impinged larvae, ranging from 5% to near 100%, depending on species. A site-specific 

investigation would be needed to determine the mortality for larval organisms at DCPP. In 

addition, there is a potential that the center flow screens, with their higher inlet velocities, 

TENERA E9-055.0 6-26 Final 316(b) Demonstration 

March 1,2000 
6.0 Altemative Intake Technologies 

complex flow patterns and curved baskets could increase impingement of juvenile and adult 

fishes. Both survivability of larvae and any changes to impingement would have to be evaluated 

prior to assessing a biological benefit for fine mesh baskets on center flow screens. The net 

present value of this modification is (-) $7,906,000, with an uncertain benefit. 

Single circulating water pump operation was also evaluated as a method to reduce entrainment. 

Operating only one ofthe two CWP running per unit would reduce the cooling water 

requirement by about half, reducing entrainment by the same amount. Single circulating water 

pump operation would require that both units at DCPP be operated at 50% power or less or that 

one unit be shutdown. The loss of revenue associated with single circulating water pump 

operation does not make this a feasible alternative. 

Variable speed drives for the circulating water pumps offer the possibility of reducing flow to the 

minimum required flowrate (optimizing generation and condensate depression) needed to 

support operation at a specific level of plant output. Since DCPP is a base loaded plant operating 

at 100% power most ofthe time, the potential flow reduction is limited to 2 to 10% of rated flow, 

depending on ocean temperatures. Additional flow reductions are limited by the capabilities of 

the pumps themselves, such that significant flow reductions (even with a reduction in power are 

limited to flow reduction of approximately 20 to 30%). The costs and limited potential flow 

reduction with this alternative does not make this a cost effective alternative. 

The feasibility of scheduling refueling outages to coincide with periods of high larval densities 

of certain organisms was also evaluated. During refueling outages, the amount of cooling water 

required is reduced and strategic scheduling could reduce the amount of entrainment. It is 

possible that at least some ofthe refueling outages could be scheduled to coincide with periods 

of high density of certain larval fish or invertebrate taxa. Many fishes produce larvae to benefit 

from the increase productivity associated with spring and summer months. Conducting outages 

during the spring could reduce the impact on nearshore taxa 7-10% assuming two cooling water 

pumps are out of service for 30 d. 

Longer curtailments of cooling water pump operation, exclusive of refueling outages were also 

evaluated. Water flow conditions would be severely reduced for one to three months under this 

TENERA E9-055.0 6-27 Final 316(b) Demonstration 

March 1,2000 
P.60 

6.0 Alternative Intake Technologies 

scenario. Some or all cooling water pumps would be shut down when a majority ofthe fish 

larvae are present in the plankton. The current data indicate a large percentage ofthe larval fishes 

are vulnerable to entrainment through the spring months March-June. Suspending pumping 

operations, except for vital ASW flows, for three months would protect about half of the fish 

larval density from risk of entrainment. The costs of these measures are extreme and many fishes 

that reproduce at other times or have long-lived larval stages would remain vulnerable to 

entrainment during the 9-11 months of operation. 

TENERA E9-055.0 6-28 Final 316(b) Demonstration 

March 1,2000 
P.61 

6.0 Alternative Intake Technologies 

Table 6-1. Listing ofthe alternative technologies evaluated and location ofthe evaluation in this 

report. 

Category Intake Technology 

Meets 

Criteria 

Meets 

Criteria 

2 

Meets 

Criteria 

3 

Evaluated in noted 

Section or Appendix 

Cooling Water System 

Intake Configuration 

Behavioral Barriers 

Physical Barriers 

Fish Collection, 

Removal and 

Conveyance Systems 

Maintenance and 

Operational 

Modifications 

Once Through 

Closed-cycle cooling tower (saltwater) 

Closed-cycle cooling tower (fresh water) 

Closed-cycle Cooling Pond or Canal 

Cooling system component modification 

Offshore Intake Location / Velocity Cap 

Altemate Onshore Intake Location 

Shoreline 

Recessed 

Increased Area Intake Structure 

Angled Screen Intake Structure 

Light 

Sound 

Bubble screen 

Velocity gradient 

(water jet or other turbulence) 

Electrical barrier 

Louvers 

Chemicals barriers 

Magnetic field (barrier) 

Chain and cable barriers 

Vertical traveling screen 

Drum screen 

Centerflow traveling screen 

Fine Mesh Screen 

Media filter 

Stationary screen 

Horizontal traveling screen 

Inclined Plane screens 

Combinations of vertical traveling screen 

modifications 

Gravity sluiceway 

Maintenance Dredging 

Single circulating water pump operation 

Variable Speed Circulating Water Pumps 

Continuous screen rotation 

Refueling outage scheduling 

N/A 

• 

• 

• 

• 

• 

N/A 

• 

• 

• 

• 

• 

• 

N/A 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

N/A 

• 

• 

• 

N/A 

• 

• 

N/A 

• 

• 

• 

• 

• 

• 

• 

N/A 

• 

• 

N/A 

• 

• 

N/A 

• 

• 

• 

• 

• 

• 

• 

in use at DCPP 

Section 6.2.2.1 

Section 6.2.2.2 

App. N 

App. L 

App. M 

App. M 

in use at DCPP 

App. M 

Section 6.2.1.1 

Section 6.2.1.2 

App. M 

App. M 

App. M 

App. L 

App. L 

App. L 

App. L 

App. L 

App. L 

in use at DCPP 

App. M 

App. M 

Section 6.2.2.3 

App. L 

App. L 

App. L 

App. L 

Section 6.2.1.3 

Sections 6.2.1.2 and 

6.2.1.3 

App. M 

Section 6.2.2.4. 

Section 6.2.2.5 

Section 6.2.1.3 

Section 6.2.2.6 

N/A: Not applicable 

TENERA E9-055.0 6-29 Final 316(b) Demonstration 

March 1.2000 
P.62 

6.0 Alternative Intake Technologies 

Table 6-2. Estimated equivalent adults, months of peak density, and evaluation 

of susceptibility to entrainment for target crab and fish taxa collected in DCPP 

entrainment and study grid plankton samples. 

Common Name 

Cancer crabs 

Brown rock crab 

Slender crab 

Pacific sardine 

Northem anchovy 

Rockfishes 

KGB complex 

Blue complex 

Painted greenling 

Sculpins 

White croaker 

Monkeyface 

prickleback 

Kelpfishes 

Blackeye goby 

Flatfishes 

Sanddabs 

Califomia halibut 

Months of 

Entrainment 

Spring 

Winter-Spring 

Mar-May 

Dec-May 

Mar-Jul 

Jan-Mar 

all year, 

esp. Mar-May 

Apr-Jul 

Dec-Mar 

Mar-Jun 

Jan; Jun-Aug 

Mar-Nov 

Jul-Sept 

April-May 

peak density 

Study Grid 

May-Jun 

May-Jun 

Mar-May 

Mar-May 

May 

Jan-Feb 

May-Jun 

Apr-Jul 

Dec-May 

Apr-May 

Dec-Feb 

July-Sept 

July-Sept 

Apr-May; Jul 

Estimated 

Equivalent Adults 

(FH and AEL) 

9,100-23,400 

895-5,460 

3,170-8,460 

16,100-120,000 

497-1,120 

18-353 

nd 

nd 

5,110-15,000 

nd 

nd 

10,300-75,400 

92-2,370 

nd 

Reduced 

Entrainment 

Feb-Mar & Sep-Oct 

maybe 

maybe 

Yes 

Yes 

Yes 

Yes 

Yes 

No 

Yes 

Yes 

No 

Yes 

Yes 

No 

TENERA E9-055.0 6-30 Final 316(b) Demonstration 

March 1,2000 
P.63 

6.0 Alternative Intake Technologies 

Criteria 1 

Is the alternative technology available and proven 

(i.e., demonstrated operability and reliability) at a cooling water 

intake having a size and environment similar to mat ofthe 

DCPP site? 

NO 

YES 

Criteria 2 

(Generic biological evaluation) 

Could the implementation ofthe altemative technology result in 

a reduction in the loss of aquatic organisms from the present 

operating conditions? 

NO 

YES 

Criteria 3 

(Site specific evaluation) 

is implementation ofthe altemative technology feasible at the 

DCPP site, based on site-specific considerations of engineering, 

operations, and reliability? 

NO 

Y E S 

__J 

See Appendix L for description ofthe 

technologies excluded by Criteria 1 and 

justification. 

See Appendix M for description ofthe 

technologies excluded by Criteria 2 and 

justification. I 

See Appendix N for description of the 

technologies excluded by Criteria 3 and 

justification. 

See applicable subsections of Section 6 for feasibility evaluation 

and cost estimates. 

Figure 6-1. Altemative intake technologies evaluation flow chart. 

TENERA E9-055.0 6-31 Final 316(b) Demonstration 

March 1,2000 
P.64 

6.0 Alternative Intake Technologies 

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TENERA E9-055.0 6-32 Final 316(b) Demonstration 

March 1,2000 
P.65 

6.0 Alternative Intake Technologies 

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TENERA E9-055.0 6-33 Final 316(b) Demonstration 

March 1,2000 
P.66 

6.0 Alternative Intake Technologies 

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March 1,2000 
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P.68 

6.0 Alternative Intake Technologies 

Figure 6-6. Monthly density of all fish larvae collected in weekly entrainment 

surveys conducted from Oct 1996 to Sep 1998. 

TENERA E9-055.0 6-36 Final 316(b) Demonstration 

March 1,2000 
7.0 Discussion 

7.0 DISCUSSION 

The purpose of this study was to assess the effects ofthe Diablo Canyon Power Plant (DCPP) 

cooling water intake structure on populations of fishes and invertebrates. Effects from the plant's 

cooling water intake structure can result from impingement of organisms on the intake traveling 

screens or entrainment into the plant's cooling water intake structure. This study focused on 

entrainment effects, because an evaluation by the Regional Board's Entrainment Technical 

Workgroup (ETWG) detennined that impingement effects were not significant (Tenera 1998b). 

Although many marine organisms have planktonic forms that could be entrained by the power 

plant, the ETWG focused on the larvae of fishes, crabs, and sea urchins. Although hundreds of 

different taxa were entrained, the ETWG chose 16 target taxa for this assessment that included 14 

fishes and two species of crabs. Their decision was based on criteria that included the abundance 

of a taxon, the availability of suitable life-history information to meet assessment model 

requirements, and criteria outlined in USEPA Draft Guidelines (USEPA 1977) and modified by 

the ETWG (Tenera 1997b). The ETWG determined that several assessment approaches would be 

applied to the data for each taxon where possible. Where we were able to complete two or more 

approaches, we compared results to provide a basis for determining the accuracy of our 

assessment for an individual taxon. 

7.1 Assessment Approaches 

Three assessment approaches developed by PG&E, its consultants, and other members ofthe 

ETWG were used to estimate entrainment effects at DCPP. Estimates of entrainment loss, and the 

demographic data reported in the scientific literature, were used to parameterize two demographic 

approaches for estimating entrainment effects: Fecundity Hindcasting (FH) and Adult Equivalent 

Loss (AEL). These methods are similar except that FH uses the number of larvae entrained to 

hindcast the number of eggs, and the number of eggs is then used to estimate the number of 

female adults that would have produced them. The AEL method forecasts the number of adults 

that would have survived from the estimated number of entrained larvae, as if they had survived 

entrainment, using knowledge of natural mortality rates. It has been assumed throughout this 

TENERA E9-055.0 7-1 Final 316(b) Demonstration 

March 1,2000 
7.0 Discussion 

study that 100% mortality occurs for all entrained larvae. A third method, the Empirical 

Transport Model (ETM), estimates an average annual larval mortality due to entrainment Pht per 

individual taxon, using estimates of proportional entrainment (PE) that compare the number of 

larvae entrained in one day to the number of available larvae in the source water body. Larval 

mortality is calculated after PE is weighted by the estimated fraction ofthe total population 

affected and compounded by the time larvae are susceptible to entrainment. 

The three approaches combine demographic information with environmental setting to model 

entrainment effects and then, where possible, compares these results to corollary data. The 

corollary data used in this report included fisheries information, data from Intake Cove plankton 

tows, and subtidal observations of juvenile and adult fishes. The integration of growth, 

reproduction, and mortality parameters in the three models are used in obtaining estimates of 

adult losses and entrainment mortality. These estimates help us better understand population 

measures such as length-frequency distributions and indices of year-class strength. Much ofthe 

effort in compiling these models is similar to the process undertaken by fishery scientists to 

conduct stock assessments used to gauge the health of fished populations. 

Stock assessments are tools fishery scientists use to determine the health of a fish population. 

These assessments combine available biological and demographic data with information on 

fishing effort and landings to assess trends offish abundance. These trends can be assessed from 

sources such as long running observational data sets (e.g., subtidal fish observations, Tenera 

1997c), annual fishery catch statistics, and data on fishing effort. Fishery scientists divide the 

amount of catch by the amount of time spent fishing to create an index of abundance called 

'catch-per-unit-effort.' 

Catch data alone are an imperfect estimator of abundance since they are an indirect measure of 

the available fish population and may also reflect biases toward larger, more easily harvested, or 

more valuable fishes. Therefore, fishery scientists must combine biological data describing the 

population under study with catch data to understand the trends they observe. The types of 

biological data that are useful to have are: the age structure ofthe population, age at first entry 

into the fishery (recruitment), age at first reproduction, estimates of longevity, and perhaps most 

TENERA E9-055.0 7-2 Final 316(b) Demonstration 

March 1.2000 
7.0 Discussion 

importantly, estimates of total mortality. Total mortality is the combination of mortality due to 

both natural and anthropogenic causes like fishing. Understanding the effects of entrainment on 

larval fish populations requires similar steps as those taken to assess the health of adult 

populations. 

Similar to the process fishery scientists use for assessing fish populations, the assessment models 

for DCPP required several decisions regarding the assumptions, level of complexity, data inputs, 

and application. Issues considered included the following: 

• compensation; 

• entrained eggs; 

• calculation of larval duration; and 

• application of model results in an assessment of habitat damage. 

In addition, all assessments were based on the assumption of 100% mortality of all entrained 

organisms. 

7.1.1 Compensation 

Saila et al. (1987) define compensation as "the ability of a fish population to offset, in whole or 

part, reduction in numbers caused by impacts from natural and/or man-induced stresses, which 

includes fishing." Postulated compensatory mechanisms include growth, competition, predation, 

cannibalism, size at maturity, fecundity, disease, and reproduction. Ricker (1975) reports that 

compensatory mortality, as a function of population size, reduces the intrinsic rate of population 

increase. Nisbet et al. (1996) say that compensation fails to prevent declines in adult stocks in 

response to added mortality of larvae by power plants, except when compensation occurs in the 

late immature stages, after entrainment but before: maturation. Density-dependence is not 

confined to acting through mortality; growth and fecundity may also be density-dependent. 

Therefore, the processes that regulate populations are complex. Some entrainment studies have 

assumed that compensation is not acting between entrainment and the time when adult 

recruitment would have taken place, and further, that this specific assumption resulted in 

conservative estimates of projected adult losses (Saila et al. 1997). Others, such as Parker and 

DeMartini (1989), did not include compensatory mortality in estimates of equivalent adult losses 

I 

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7.0 Discussion 

because of a lack of consensus on how to include it in the models and, more importantly, 

uncertainty about how compensation would operate on the populations under study. The 

uncertainty arises because the effect of compensation on the ultimate number of adults is directly 

related to the vital processes (fecundity, somatic growth, mortality) and affected life stages. In 

particular, Nisbet et al. (1996) showed that neglecting compensation does not always lead to 

conservative long-term estimates of equivalent adult losses. Density-dependent recruitment 

___. . . ._. .,„ . ,. L .I. M II rr-rrr-*——-" min".i.ijiu "' " " mn. nw.wia.ni. . j miirwi injur 

compensation is also hard to distinguish from competing climatic effects. Confounding of 

environmental and density-dependent effects is a major problem that can result in spurious 

environmental effects being mistaken as density-dependent effects(Clark et al. 1999). The 

sampling plan and modeling evaluation for these entrainment studies at DCPP (Tenera 1998a) 

considered that population regulation could include both positive and negative compensatory 

mechanisms. We also concluded that it would be beyond the scope ofthe current study to include 

population regulation in the models used to predict adult losses. 

Compensation (density-dependence) is also an important component ofthe fishery management 

concept of surplus production (Ricker 1975; Figure 7-1). This theoretical relationship describes 

the relationship between adult abundance and the number of progeny they produce. In this 

construct, there is an equilibrium population level at which there are just sufficient adults in the 

population to replace themselves. Production above and beyond this level is termed "surplus 

production" that can be harvested without depleting the population. Entrainment mortality is 

analogous to harvesting mortality, except that it removes younger animals from the population. It 

appears that for many ofthe target taxa examined at DCPP, the additional mortality on early life 

stages added by entrainment in the cooling water intake system could be attributed to surplus 

production since there are no concurrent decreases in adult or larval abundance measured at other 

locations. 

7.1.2 Eggs 

Planktonic eggs are entrained along with larvae at DCPP. Early in the process of developing the 

present study, the ETWG decided not to enumerate fish eggs in the plankton samples collected. 

The reasons for this decision were that, while there are some descriptions of marine fish eggs, 

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7.0 Discussion 

their classification is both difficult and time consuming, and ultimately, the initial list of possible 

target taxa did not include many fishes with pelagic eggs that would be subject to entrainment. 

Egg losses have been quantified in other 316(b) entrainment studies (e.g., Murdoch et al. 1989; 

Bailey et al. 1998; Cherry and Currie 1998; Jacobson et al. 1998; Richkus 1998). Lacking the egg 

entrainment data, one might assume that the numbers of adult equivalent losses resulting from 

egg entrainment would be equal to those estimated from larvae. However, the actual situation 

may be more complex; for example, there are differences in dispersion patterns between eggs and 

larvae, larval behavior may affect entrainment, etc. (Lasker 1981). 

Populations ofthe five target taxa with pelagic eggs (Pacific sardine, northern anchovy, white 

croaker, sanddabs, and California halibut) are not adversely affected by the DCPP intake 

indicated by generally low to moderate estimates of annual entrainment mortality (PSI), FH, or 

AEL. Furthermore, these taxa are protected against localized effects by having widespread 

populations or spawning centers distant from DCPP. In the case of California halibut, with a 

relatively high PKI , but low approximated FH, very few individuals are entrained at DCPP so 

there is no adverse impact on their population. All other target taxa either brood their eggs 

attached to their bodies (Cancer spp. crabs), extrude live larvae (rockfishes), or have demersal 

adhesive eggs (greenlings, sculpins, pricklebacks, clinid kelpfishes, and gobies). Therefore, egg 

losses are not assumed to be an important factor in estimating entrainment effects. 

7.1.3 Larval Duration 

Larval lengths at entrainment were used to estimate age at entrainment from growth rates 

reported or derived from current scientific literature. This method has many assumptions with 

implications for the results ofthe present study. Primary among these is the assumption that the 

point estimates reported in the literature, often from areas geographically removed from the 

central coast of California, are representative of growth rates for lan'ae in the area around DCPP. 

Dividing all larval lengths by the same growth rate to obtain estimated ages assumes that growth 

is constant over the durations estimated. Variation in growth rates, more probable for larger 

individuals, could lead to miscalculations of larval age. Examination of length-frequency 

histograms for the various taxa treated in this study and comparison of these with reported hatch 

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7.0 Discussion 

lengths leads to the conclusion that there is much wider variation in hatch lengths of these fishes 

than is presently reflected in the literature. This follows from the observation that many ofthe 

larvae collected and measured in this study were smaller than the reported hatch lengths. In many 

cases, the average lengths of larvae entrained were less than reported hatch lengths. This may be 

due in part to larval shrinkage resulting from preservation (Theilacker 1980). The approximatelynormal distributions observed for very small length larvae could also result from natural random 

variation in hatch lengths and could explain the lengths being less than those reported for 

hatching (Matarese et al. 1989; Moser 1996). If the actual larval ages at entrainment were 

younger than our estimates the areas containing the affected population would be smaller than 

-^PfflMMMttmnW 

~.Jk" those estimated using the present methods. If the affected populations are actually smaller than 

those used in the ETM, then PM could be underestimated 

7.1.4 Application to Habitat 

The conservation offish habitat has been recognized by scientists and managers as an essential 

issue in fisheries management as a result of measures included in the reauthorization ofthe 

Magnuson-Stevens Fishery Conservation and Management Act (Benaka 1999). These measures 

emphasize the need to preserve essential fish habitat and integrate ecosystem-based concepts into 

fisheries management. The ability to quantify the success of management practices for preserving 

essential habitat is potentially easier than quantifying fish populations that are mobile and 

difficult to sample. It is recognized that effective management of essential fish habitat requires 

knowledge of species-specific habitat requirements, descriptions ofthe physical environment and 

available habitats, and estimates offish populations in the different habitats (Cobb et al. 1999). 

The type of information required to convert PA; into something more tangible that is 

-, representative ofthe effective area or habitat affected is not available for our nearshore target 

Lfv' , taxa. In addition, while loss of habitat may be logically converted into fish population losses, the 

fA • ' ,. 

") • ,*.-<•'' conversion of entrainment losses into habitat is less reasonable because there is no specific 

".'•'"' " , rr. r ' 

y <y shoreline area associated with, or degraded by, entrainment. The conversion of entrainment 

losses into habitat losses also ignores the fact that entrainment only affects one life stage, and 

recruitment and migration from unaffected portions ofthe population will continue to fill 

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7.0 Discussion 

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available habitat niches. Continuing long-term shifts in oceanographic conditions affecting fish 

habitat quality and productivity also confounds attempts to convert entrainment losses into 

habitat. 

7.2 Assessment of Entrainment Effects 

The following criteria were developed by PG&E, its consultants, and other members ofthe 

ETWG for evaluating adverse environmental impacts (AEI) at DCPP. These criteria are specific 

to the marine environment around Diablo Canyon, in most cases are unique to marine aquatic 

organisms, and are directly applicable to the present 316(b) entrainment study: 

• environmental trends (climatological or oceanographic); 

• abundance trends (e.g., Intake Cove plankton tows, subtidal fish observations, 

fishery catch data); 

• life history strategies (e.g., longevity and fecundity); 

• population distribution; and 

• magnitude of effects. 

These criteria are discussed in the sections that follow. The criteria were considered on a taxonspecific basis when trying to determine the extent of entrainment effects on the local environment 

and on the population at large. This provides a basis for our conclusions in Section 13 for 

assessing AEI using USEPA guidelines to determine the "relative biological value ofthe source 

water body zone of influence for selected species and determining the potential for damage by the 

intake structure " (USEPA 1977). The USEPA (1977) also stated that the biological value of a 

given area to a particular species be based on "principal spawning (breeding) ground, migratory 

pathways, nursery or feeding areas, numbers of individuals present, and other functions critical 

during the life history." 

7.2.1 Environmental Trends 

Changes in recruitment and adult abundance appear to be periodically accentuated by El Nino 

events observed in the DCPP receiving water monitoring program (RWMP) long-term subtidal 

juvenile and adult fish observation data. A decline in abundance in the subtidal fish observation 

data following the 1991-1993 El Nino event is common to many ofthe target taxa. In 1992— 

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7.0 Discussion 

1993, nearly all taxa experienced a sharp decline in abundance followed by relatively constant 

but lowered abundance to the present time. The extended El Nino event between 1991 and 1993 

had important implications for many ofthe fish taxa found here (Yoklavich et al. 1996). Warm 

water events can have very large detrimental effects on rockfish year-class strength since these 

are typically species with cold water affinities (Karpov et al. 1995; Lenarz et al. 1995; Ralston 

and Howard 1995; Lea et al. 1999; Love et al. 1999). Abnormally high water temperatures and 

suppression of annual upwelling along the California coast have been linked to large-scale 

reductions in the primary prey of juvenile and adult rockfishes (Mullin and Conversi 1989). 

Reductions in food sources can negatively affect the somatic and reproductive condition of these 

life stages (Lenarz and Wyllie Echeverria 1986; VenTresca et al. 1995). 

Another strong El Nino event occurred along the central California coast and eastern Pacific 

Coast during the fall, winter, and spring seasons of 1997-98 (Lynn et al. 1998). This may explain 

the differences in entrainment estimates between the years 1996-97 and 1997-98 for some ofthe 

taxa (Table 7-1). Changes in distribution and dispersal patterns of pelagic larvae are expected 

during anomalous warm oceanographic events (Bailey and Incze 1985; Brodeur et al. 1985). For 

example, estimates of entrainment, FH and AEL for both Pacific sardine and northern anchovy 

increased markedly between the first and second year ofthe study. The spawning biomass for 

both of these species is typically centered south of Point Conception (Hart 1973; Butler et al. 

1987: PFMC 1998; Hill et al. in press), and it was likely displaced northward with the northflowing El Nino currents present in the second year. White croaker FH and AEL also appeared 

to increase slightly, which may also be due to additional transport northward during the El Nino 

year. Other species appeared to be somewhat less affected by El Nino-related transport since FH 

and AEL remained relatively constant or decreased only slightly between years (e.g., KGB 

rockfishes, blue rockfish complex, blackeye goby, and sanddabs). These fishes probably have 

more localized spawning populations that were less affected by the El Nino event. 

Coastal marine ecosystems in the Southern California Bight have experienced reduced 

productivity associated with a climate regime shift towards warmer water conditions that began 

during the 1976-77 El Nino (Holbrook et al. 1997). These changes have led to large impacts on 

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population abundances and trophic structure in nearshore benthic communities within the Bight. 

In general, they showed that the diversity and abundance of fishes with more northern 

biogeographic distributions have declined in the Southern California Bight since the advent of 

this warmer water regime. Furthermore, these assemblages have shown a shift in the dominant 

species away from more northern distributed taxa and toward more southerly distributed species 

that are presumably more tolerant of warm water. Similar trends were also observed further north 

at Santa Cruz Island where populations of surfperches, the standing stock of their crustacean 

prey, and the biomass of understory macroalgae all declined by ca. 80%. Holbrook et al. (1997) 

hypothesize that fish abundance declined as a result of declining recruitment that became 

insufficient to compensate for losses of older age classes. This can be termed "recruitment 

overfishing" defined by Gulland (1983) as limiting the amount of larvae a population produces 

by taking primarily older, more fecund adults and leaving young, less fecund individuals. These 

recruitment levels fell more than one order of magnitude over two decades and were correlated 

among years with broad indicators of Bight-wide productivity ofthe coastal marine ecosystem; 

namely the biomass of zooplankton in the California Current (Holbrook et al. 1997). 

7.2.2 Abundance Trends 

Data collected for this 316(b) study can be compared with other corollary and long-term data sets 

to give broader temporal context to the 2-3 year study at DCPP. Several ofthe target taxa are 

nearshore species that are not taken by commercial or recreational fisheries. For these taxa, data 

from long-term studies at DCPP on larval, juvenile, and adult fish abundance were used to 

examine changes in abundance that may be correlated with entrainment effects. 

Declines in adult abundances of clinid kelpfishes and snubnose sculpin overthe last several years 

were detected in DCPP subtidal fish observation data in the control area (Tenera 1997c). This 

decrease in adult abundance also appears to be correlated with a decline in their larval abundance 

apparent from Intake Cove plankton tows. These taxa also had some ofthe highest estimates of 

total annual entrainment among the target taxa. Smoothhead sculpin, while having relatively high 

total annual entrainment, did not show similar declines in adult or larval abundance. These and 

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7.0 Discussion 

other nearshore taxa appear to demonstrate similar variation to that observed in previous years 

from subtidal fish observations and Intake Cove plankton tows. 

Intake Cove plankton tows were collected at DCPP starting in 1990. Although sampling occurred 

throughout the year, larval density estimates were calculated from only the seven months ofthe 

year when larval fishes were most abundant (December-June). These data were used to adjust 

entrainment estimates to a long-term average density in the Cove. This procedure could introduce 

a bias in the adjusted estimate for fishes whose larvae are only abundant in the water column 

during the other five months ofthe year (e.g., sanddabs), and for some taxa an adjustment was 

not calculated. Two taxa, blackeye goby and clinid kelpfishes, were very abundant during the 

five months of Intake Cove samples that were not processed. They were adjusted to the long-term 

average because larvae for these taxa were present in the sorted samples. 

Trends in adult abundance ofthe commercially important blue rockfish complex and cabezon 

also showed declines in our long-term fish observation data. The early and mid-1990's saw the 

advent of live-fish fishing along the central coast of California (Bloeser 1999) that could be 

related to these declines. Live-fish fishing has been identified as a cause of "growth overfishing" 

(Gulland 1983) and sharp declines in adult abundance (Starr et al. 1998). Landings at Morro Bay 

area ports do not indicate long-term declines in the catch of adult cabezon, although a 26% 

reduction in landings in 1999 compared to 1998 suggests that the 'live-fish' fishery cannot be 

sustained at high exploitation rates for long. Fishery harvest data do not indicate any long-term 

declining trends for other commercially or recreationally important species also entrained at 

DCPP. Any potential effects of power plant larval entrainment on catches of harvested species 

may be masked by changes in exploitation rates and the lack of credible catch-per-un it-effort data 

needed to examine long-term trends. Clearly, other longer-term declines associated with a climate 

regime shift that began in the late 1970's (Holbrook et al. 1997) must also be considered. 

7.2.3 Life History Strategies 

Life history strategies played an important role in the three assessment approaches we used to 

assess the magnitude of entrainment effects. Fecundity hindcasting (FH) estimates of adult losses 

relied on the number of eggs and fish or crab larvae produced during their life. Pelagic taxa like 

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7.0 Discussion 

northern anchovy typically produce numerous eggs that hatch relatively under-developed larvae. 

This strategy hedges against high egg and larval mortalities by reducing the amount of energy 

placed into any one progeny and assures that at least a few will survive to adulthood. Another 

common strategy found among the target fish taxa is producing relatively fewer, demersal, 

adhesive eggs. More energy is expended into fewer eggs that hatch more developed larvae than 

the taxa with pelagic eggs. This strategy is advantageous when combined with the demersal eggs 

since this latter adaptation reduces otherwise high egg mortalities. Thus, egg and larval survival 

rates up to the point of entrainment are directly linked to the reproductive strategy ofthe 

particular species being assessed and have marked effects on the demographic approaches used 

for estimating entrainment effects. The AEL approach depends on survival estimates from the 

time of entrainment to recruitment of adults into the fishery. Estimates of survivorship are 

undocumented for many ofthe taxa considered in this report and therefore they had to be 

estimated or substituted from other related taxa. The level of uncertainty associated with these 

survivorship estimates is typically unknown and can contribute to overall uncertainty in the 

estimates from these approaches. This also shows the importance of larval duration in the 

formulation ofthe approaches. Differences in life histories and adult distributions were accounted 

for in the formulation ofthe ETM among taxa. For example, pelagic species that released 

planktonic eggs are treated differently from nearshore species with demersal egg masses by 

estimating the population of inference using offshore extrapolation and alongshore extension of 

study grid abundance. 

The availability of life history information allowed multiple assessment approaches to be used on 

several ofthe target taxa, but in the absence of independent population estimates for these taxa, 

our ability to assess effects was limited. For example, demographic data on egg and larval 

mortality for blackeye goby allowed the application of multiple assessment approaches, but in the 

absence of a population assessment or any fishery data for this species we could not provide any 

context for the estimates. The utility of any modeling technique to yield relative assessments of 

population-level effects depends on data describing the size ofthe adult fish populations and the 

ability to convert FH, AEL, and ETM estimates into comparable units of fishes in the wild. 

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For taxa where all three assessment approaches were completed, comparison among the results 

illustrate the usefulness ofthe multiple assessment approach. While the range and variance of life 

history parameters and population estimates are sources of uncertainty in our estimates, we can 

determine our areas of uncertainty through model comparison. Where both FH and AEL 

estimates exist, assuming a 50:50 sex ratio and aligning the ages of recruitment and maturation, 

the models can be compared directly using the relationship AEL = 2FH presented in previous 

assessment reports (Tenera 1999a, b). This conversion requires that ages of AEL and FH 

individuals are aligned and equal. The results from the demographic approaches are in similar 

units of either adult females (FH) or adults (AEL). 

The FH and AEL model estimates for some ofthe target taxa were not in particularly close 

agreement (Table 7-lb). The age-aligned estimate for 2FHwas over 4 times greater than the 

initial AEL estimate for Pacific sardine. In contrast, the FH estimates for sanddabs were low 

relative to AEL. When FH estimates are aligned for age the estimates remain low, relative to 

AEL. Sensitivity analyses were conducted to help determine the parameter estimates contributing 

the greatest influence on the FH and AEL estimates. The uncertainty associated with many ofthe 

parameters resulted in the use of a coefficient of variation of 100% to estimate their variance, in 

accordance with ETWG recommendations. This reduced the usefulness ofthe sensitivity analyses 

in interpreting model results. 

Results for target taxa that were in close agreement with the relationship 2FH = AEL (subject to 

age alignment) provide some assurance that the parameters used in the models were 

representative for the central California populations we sampled. They also increase confidence 

that the assessments of effects on these populations are reasonably accurate. Two examples were 

northern anchovy and the blue rockfish complex. In the blue rockfish complex, FH and AEL 

estimates were used to extrapolate population level effects using local fishery landings (Section 

5.2.4). Using an estimate ofthe weight per adult blue rockfish in the fishery of 0.5 kg, an 

estimated AEL of 343 adults represented 172 kg of 3 yr old recruits, ca. 1 % ofthe catch landed in 

the Morro Bay area in 1999, and valued at approximately $740. Blue rockfish PXI rangei from 

0.004-0.02, bracketing the _4£Z.-based percentage of catch. It was also relatively linear over an 

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extrapolated area of 220-1,100 km- (smaller mortality associated with larger areas). Despite the 

limitations and assumptions ofthe models, the results ofthe assessment for the blue rockfish 

complex provide assurance that the effects on this taxon are low. 

Model assumptions also need to be considered when interpreting the large FH estimate for brown 

rock crabs (Table 7-la). The estimated number of reproductive adults using the FH model was 

extrapolated to known fishery-sized animals using estimates of adult mortality because females 

are reproductive before they enter the fishery. This reduced the FH estimate by an order of 

magnitude. Therefore, because ofthe additional assumptions required for the FH estimate, the 

estimate of PAI was used in extrapolating fishery effects. If all larval stages in the population are 

equally entrainable, then the estimate of PAI that was based on megalops would be representative 

of all larval stages. This assumption was made when PKI was applied to the catch. 

For target taxa without available life history information, measurements of larvae from the 

entrainment and study grid provided some insight into their larval life history and ecology. The 

length ranges for most ofthe entrained target larval fish taxa indicate that their exposure to 

entrainment occurs over a relatively short time period during their development. The lengthfrequencies for several ofthe target taxa, including KGB and blue rockfish complex larvae, larval 

painted greenling, cabezon, and blackeye goby, appeared normally distributed. Average lengths 

were small demonstrating that they were exposed to entrainment for a brief period during their 

larval development. This supposition is supported by another characteristic common to these 

taxa; very few flexion or post-flexion larvae were entrained. Flexion and post-flexion stage larvae 

have more developed swimming abilities than younger individuals and could be avoiding the nets 

and potentially entrainment. The lack of these later developmental stages in our samples may also 

indicate that these taxa demonstrate larval behavior that removes them from risk of entrainment 

as they develop (e.g., settlement to benthic habitats or migration into deeper areas away from the 

intake). In contrast, the length-frequency distributions for the two target taxa with evidence of 

localized entrainment effects, clinid kelpfishes and snubnose sculpin, were skewed and included 

larger individuals than other taxa. Thus, it appears that these two taxa are exposed to entrainment 

over longer periods of development that include flexion and post-flexion stage larvae. An 

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extended duration of exposure to entrainment may partially explain the apparent declines in adult 

and larval abundance for these two taxa. Paradoxically, the extended exposure to entrainment that 

apparently results in localized effects on these taxa may also insure that localized effects do not 

become greater population-level effects. Extended planktonic duration will allow for larval 

transport and dispersal to occur over a much larger area. 

7.2.4 Population Distribution 

The assessment considered taxa that occurred in the entrainment samples at DCPP. Their 

abundance depended on temporal and spatial distribution of adults as well as larval life stages. 

The taxa can be described as pelagic (Cancer crabs, Pacific sardine, and northern anchovy), 

subtidal (rockfishes, painted greenling, snubnose sculpin, cabezon, white croaker, blackeye goby, 

sanddabs, and California halibut), and nearshore subtidal and intertidal (smoothhead sculpin, 

monkeyface prickleback, and clinid kelpfishes). These different spatial distributions contributed 

to the ETWG's decision to use two strategies in applying the ETM. Nearshore species population 

size was assessed by alongshore extension of study grid abundance only; otherwise, an offshore 

extrapolation of study grid abundance was conducted and then extended alongshore. These 

expansions ofthe study grid abundance were based on measures of current speed and direction at 

the DCPP current meter station and constrained by larval ages at entrainment. 

The ETM approach applied to all target taxa required an estimate of a population that was defined 

by extrapolating larval density over an area delimited by estimated larval duration combined with 

current speed and direction in the study period. Estimates of total annual entrainment mortality 

(Pu ) rely on the estimates of Ps (# of larvae at risk in the study grid/# of larvae in the population 

of inference). The results for target fish taxa in this 316(b) study indicate that while some 

entrainment effects remain localized, other effects can be spread over wide areas of inference 

(Table 7-2). 

When estimated larval durations were relatively short and the subsequent area containing the 

population of inference remained relatively small, the extent of extrapolation was also small, 

based on the current meter data. Under these conditions, Ps was likely a more precise estimate, 

potentially less susceptible to model bias, resulting in a more accurate estimate of entrainment 

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effects, PS1 . There is less confidence in our estimates of Ps where the extrapolated areas were 

substantially larger than the study grid. The variance component, resulting from density estimates 

projected offshore well beyond the zone that the measurements represented, was not included in 

our variance estimates of PM (Appendix F). Thus, the estimated reference population of fishes 

with short larval duration of exposure (e.g., cabezon and blackeye gobies) are potentially more 

precise than those with a long time of susceptibility to entrainment (e.g., crabs and Pacific 

sardine). However, the situation for nearshore species is more complex. For example, those with 

longer times of susceptibility to entrainment (durations) may disperse into the study grid area, 

becoming more available to plankton sampling gear, resulting in better estimates of PKI . 

It is unlikely that areas on the order of hundreds to thousands of times greater than the study grid 

are representative ofthe actual area affected by entrainment. Therefore, when PM was applied to 

a stock assessment or fishery (e.g., for northern anchovy), it was based on a proportion of areas 

(area of extrapolation / stock assessment area). In some cases, this proportion was more 

approximate and, for brown rock crab, relied upon an estimate ofthe fishery grounds. 

Target taxa that are not commercially or recreationally harvested are primarily small, nearshore 

fishes. As might be expected due to the shallow water, shoreline location ofthe DCPP intake 

structure, several of these taxa are entrained in relatively high numbers, resulting in large PKI 

estimates (Table 7-2). For example, adult kelpfish occur in rocky, nearshore habitat and also had 

one ofthe highest PKI estimates (ca. 30-40%). If we use only the alongshore estimate of Ps for 

calculating PXI to compare results, those taxa with nearshore distributions, including smoothhead 

sculpin. snubnose sculpin, and monkeyface prickleback, had relatively large PSI estimates. Their 

greatest larval abundance occurred in the study grid cells closest to shore. This distribution is 

consistent with their adult distributions. Confidence in estimates of entrainment mortality for 

nearshore and intertidal fishes is supported when noting that Pu for these taxa does not vary 

between extremes of larval ages at entrainment when extrapolating larval abundance alongshore. 

Although entrainment sampling occurred at the shoreline intake where these nearshore taxa are in 

greatest abundance, the study grid sampling did not adequately sample other nearshore areas. 

Therefore, modifications were made to the calculations of PE to account for nearshore volumes 

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that were not sampled. While the addition of these inshore volumes may have overestimated PSI 

for some of these taxa, estimates for blackeye goby and California halibut, species that had 

broader adult distributions, were also high (July 1998-June 1999 period only: Table 7-2). 

Blackeye goby larvae (PM »20%) were distributed throughout the study grid and occur as adults 

from the intertidal out to recorded depths of over 100 m (Eschmeyer et al. 1983). The relatively 

high Pht for blackeye goby may be due, in part, to the high density of adults directly in front of 

the intake structure. Entrainment of larvae hatched from demersal eggs within Intake Cove may 

explain our estimate of larval duration (6 d) that is considerably shorter than literature values (75 

d). Therefore, while it is likely that some bias is introduced into the estimates of PKI due to the 

nearshore areas not sampled by the study grid surveys, the bias is probably species dependent and 

may not be related solely to adult distributions. 

In contrast to species with nearshore distributions, estimates of PM for species with more 

widespread, pelagic larvae (e.g., Pacific sardine and northern anchovy) were low, as expected by 

their long larval durations and large areas estimated by alongshore and offshore extrapolation. An 

assumption ofthe ETM is that larval distributions in the nearshore study grid are representative of 

densities in the area used for calculating Ps. While this assumption may be reasonable for values 

of Ps that represent relatively small areas of coastline, density in the grid is probably not 

representative of offshore areas used in calculating Ps for pelagic and subtidal species. As a 

result, applying Phl to stock assessments or fisheries data may not accurately represent 

entrainment effects because density in the nearshore study grid is probably not representative of 

average density in the areas used for estimating standing stock biomass. However, the 

extrapolation ofthe larval density trends observed in the study grid out to waters further offshore 

was an attempt to account for this inaccuracy. When Ps, was applied to the fishery stock 

assessment by proportional area, in the case of northern anchovy, the biomass was similar to that 

determined using the two other methods of estimating adult losses, AEL and FH. The close 

correspondence in results for the different models suggests that the methodology was appropriate, 

and gives us confidence in the accuracy ofthe results. 

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7.0 Discussion 

7.2.5 Magnitude of Effects 

Results from the present study indicate that effects on commercially and recreationally harvested 

species with subtidal or pelagic distributions are minimal. For cases where we were able to apply 

all three assessment approaches, the effects detected were relatively small, appeared to be 

localized, and thus could not affect the overall adult populations. These conclusions are 

supported by results for taxa such as KGB rockfishes where the estimated low levels of 

entrainment effects were corroborated by the corollary data that showed no consequent adult 

abundance or larval production decreases. While the alignment of results among assessment 

methods for other commercially or recreationally important taxa was less compelling, it 

nevertheless did not indicate the potential for any significant long-term population-level effects. 

There was very little available information describing the demography of target taxa that were 

not commercially or recreationally important and this limited the applicable assessment 

approaches to the ETM. These were typically taxa distributed nearshore as adults, rendering their 

larvae highly susceptible to entrainment. In fact, these taxa were included in the targeted list by 

the ETWG because of their high abundance in entrainment samples. The ETM approach showed 

that entrainment could remove 10-40% ofthe annual larval production of several of these 

nearshore and intertidal taxa. In some of these cases, corollary data indicate that entrainment is 

" —' vc f 

probably only removing surplus production since there are no apparent long-term declines in 

local adult populations. For those nearshore taxa that do not display decreasing adult abundance, 

it is apparent from their length-frequency distributions that they were exposed to entrainment 

mortality for a brief portion of their early development. In contrast, for kelpfishes and snubnose 

sculpin, whose adult abundance do appear to be decreasing (with corresponding declines in longterm plankton tow index), the length-frequency distributions indicate a longer duration of 

exposure to entrainment. The combination of length-frequency analyses with the ETM estimates 

offer support to the conclusion that some nearshore taxa are affected differentially by 

entrainment. The increased duration of exposure to entrainment for kelpfishes and snubnose 

sculpin may also insure that these effects remain localized since extended planktonic duration 

provides additional opportunity for larval transport and dispersal. 

TENERA E9-055.0 7-17 Final 316(b) Demonstration 

March 1,2000 
P.86 

7.0 Discussion 

7.2 Summary Assessment 

In summary, populations of fishes and crabs do not appear to be adversely affected bv the DCPP 

cooling water intake structure. Some are commercially important taxa with pelagic eggs and 

widespread populations (e.g., northern anchovy, Pacific sardine, white croaker, sanddabs. and 

California halibut). Their assessments resulted in either low estimated larval mortalities or small 

numbers of adult losses to their populations. Other widespread species also had low numbers of 

estimated adult equivalent losses to their populations and low estimated larval mortality, with 

populations that are distributed well beyond the zone of influence of DCPP. These included 

commercial species (rockfishes, crab, and cabezon). Five taxa (smoothhead sculpin, snubnose 

sculpin, monkeyface prickleback, clinid kelpfishes, and blackeye goby) had larval mortalities that 

exceeded 10% in reference to that part ofthe population living in an area 2-8 times the study grid 

area. For most of these (except kelpfishes and snubnose sculpin), subtidal observations of adults 

and long-term plankton sampling of larvae showed no decline in numbers over recent years in the 

vicinity of DCPP. Effects on kelpfishes and snubnose sculpin appear to be localized and the area 

affected is a small part of their total geographic distribution. 

The models used for entrainment assessment considered functions critical to the life history ofthe 

16 target taxa. These models were applied both at the point of entrainment for estimating the 

numbers of individuals entrained and also in the adjacent offshore areas for estimating the 

population of inference. We also considered migratory, pelagic species and other widespread taxa 

differently than nearshore taxa in estimating the population of inference. The area around DCPP 

encompasses nursery and feeding areas for many species including the 16 target taxa. These 

areas also extend well outside the DCPP zone of influence and in the cases of northern anchovy 

and Pacific sardine the center ofthe spawning biomass is located south of Point Conception. 

Measurements of larvae indicate that most ofthe target taxa are exposed to entrainment for a 

relatively short period of time during their larval development and thus were produced locally. 

These results indicate that entrainment effects appear to be limited to localized effects on 

nearshore species. Therefore, the potential for damage due to entrainment on the biological value 

ofthe source water body is low. 

TENERA E9-055.0 7-18 Final 316(b) Demonstration 

March 1,2000 
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7.0 Discussion 

7.3 Best Technology Available 

Although no adverse environmental impact was determined, a generic review of alternative 

cooling water technologies applicable to DCPP was evaluated in Section 6. A hierarchical set of 

three criteria were applied to the alternatives that were considered: 

A review of alternative cooling water technologies applicable to DCPP was evaluated in Section 

6, as required by the RWQCB. A hierarchical set of three criteria were applied to the alternatives 

and considered: 

• available technology with demonstrated operability and reliability at intakes 

similar to DCPP; 

• a reduction in the loss of aquatic organisms; and 

• applicability at DCPP, based on engineering, operations, and reliability 

considerations. 

The technology assessments examined modifications that may affect impingement and 

entrainment although impingement rates are very low at DCPP. Site-specific studies determined 

impingement rates were low ranging between 0.3 and 0.7 kg per day per unit, which is equivalent 

to 360 kg/yr for both units. Compared to other west coast generating stations (Tenera 1998a) that 

impinge between 2,800 to 24,100 kg/yr, impingement at DCPP does not represent ah adverse 

environmental impact. Consultation with industry authorities and published engineering 

evaluations of demonstrated technologies applicable to reducing entrainment, revealed few intake 

modifications that might reduce the density offish larvae at risk to entrainment in a cost effective 

manner. Although several facilities have reduced entrainment by modifying intake screen 

systems, the harsh coastal environment at DCPP precludes application of these strategies without 

extensive site-specific testing. Reduction of operation to periods when fish densities are lower 

was considered not viable in the current power exchange pricing environment. Replacement of 

the heat exchange processes from open-cycle seawater cooling systems to closed-cycle cooling 

tower strategies was determined to be economically unfeasible and added substantial 

environmental risk to terrestrial communities. 

As discussed in the other sections of this report, DCPP is not causing an adverse environmental 

impact (AEI) and therefore no consideration of alternative cooling water intake structure 

TENERA E9-055.0 7-19 Final 316(b) Demonstration 

March 1,2000 
P.88 

7.0 Discussion 

technologies for minimizing AEl is necessary. However, this assessment of altemative 

technologies is included in response to a requirement by the RWQCB. The conclusion based on 

this assessment is that the existing cooling water intake structure is the best technology available 

for DCPP. 

TENERA E9-055.0 7-20 Final 316(b) Demonstration 

March 1,2000 
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7.0 Discussion 

Table 7-la. Estimates of fecundity hindcast adult females (FH) and projected equivalent adults 

(AEL) in numbers of individuals for Analysis Periods 1 (December 1996-November 1997) and 

3 (July 1997-June 1998) for the two target crab taxa collected and analyzed at DCPP with their 

potential relative value. 

Taxon 

Brown rock crab 

Slender crab 

Analysis 

Period 

1. 

3. 

1. 

3. 

FH 

117,000 

(11.700)a 

91,000 

(9.100)

 a 

27,300 

(2,730)

 a 

8.950 

(895) a 

AEL 

234,000 

(23,400) b 

182.000 

(18.200)

 b 

54.600 

(5.460)

 b 

17,900 

(1.790)

 b 

Interpreted Annual Value 

(applied modeling approach) 

$1,090

 c $2,170 c 

(FH) (AEL) 

$845

 c $1,690 c 

(FH) (AEL) 

no fishery value 

no fishery value 

$1,760 

(ETAf) 

$2,040 

(ETAf) 

• 

a

 Estimate extrapolated to fishery-sized female crabs. 

" Estimate extrapolated to fishery-sized crabs, both male and female. 

c

 Value based on assumption of 10% vulnerability to fishery (from mark-recapture experiments and fisher, 

recapture data: see Section 5.2.1.1). 

TENERA E9-055.0 7-21 Final 316(b) Demonstration 

March 1,2000 
P.90 

7.0 Discussion 

Table 7-1 b. Estimates of adjusted annual entrainment (EAJhT), fecundity hindcast adult females 

(FH), and projected equivalent adults (AEL ) in numbers of individuals for Analysis Periods 1 

(October 1996-September 1997), 2 (October 1997-September 1998), and 3 (July 1997-June 

1998) for the 14 target fish taxa collected and analyzed at DCPP with their potential relative 

value. When more than one valuation procedure was used, the largest value is listed. The total 

number of target taxa impinged during April 1985-March 1986 are included for comparison. 

Taxon 

Analysis 

Period 'Adj-T FH AEL 

Pacific sardine 

California 

halibut* 

Total 

Impinged 

1985-86 

Interpreted Annual Value 

(applicable valuation method) 

8.470.000 

22.600.000 

22.600.000 

3.170 

8.460 

8.460 

2.630 

7.000 

7.000 

0 $710 

(ETMmodeling applied to 

reduction and live bait fisheries) 

Northern 

anchovy 

KGB rockfish 

complex 

Blue rockfish 

complex 

Painted 

greenling 

Smoothhead 

sculpin 

Snubnose 

sculpin 

Cabezon 

White croaker 

Monkeyface 

prickleback 

Clinid kelpfishes 

Blackeye goby 

Sanddabs* 

1. 

2. 

3. 

1. 

2. 

3. 

1. 

2. 

3. 

1. 

2. 

3. 

1. 

.2. 

3. 

1. 

2. 

3. 

1. 

2 

3. 

1. 

2. 

3. 

1. 

2. 

3. 

1. 

2. 

3. 

1. 

2. 

3. 

1. 

2, 

3. 

136.000.000 

376.000.000 

377.000.000 

275.000.000 

222.000,000 

222.000.000 

84.040.000 

33.800.000 

33,900.000 

24.200.000 

9.610.000 

12.100.000 

57.700.000 

115.000.000 

129.000.000 

110.000.000 

83.500.000 

105.000.000 

51.900.000 

36.300.000 

36.300.000 

305.000.000 

440.000.000 

447.000.000 

83.100.000 

61.500.000 

60.200.000 

181.000.000 

308.000.000 

458.000.000 

128.000.000 

109.000.000 

128.000.000 

7.160.000 

1.540.000 

6.610.000 

16,100 

44.700 

44.700 

617 

497 

497 

43 

18 

20 

5.110 

7.380 

7.500 

12.000 

10.300 

12.100 

426 

92 

393 

43.200 

120.000 

120.000 

1.120 

905 

906 

353 

164 

142 

14.700t 

21.300t 

21.600t 

75.200 

64.100 

75.400 

2.370 

511 

2.190 

1 

12 

8 

1 

10 

9 

1 

0 

0 

17. 

0 

4 

$576 

(AEL and ETM modeling applied to 

non-reduction wetfish fishery) 

$20,000 

(ETMmodeling applied to 

commercial live-fish fishery) 

$1,230 

(ETMmodeling applied to 

commercial fishery) 

forage species 

(no economic valuation) 

forage species 

(no economic valuation) 

forage species 

(no economic valuation) 

$9,000 

(ETM modeling applied to 

commercial live-fish fishery) 

$872 

(AEL modeling applied to 

commercial fishery:) 

no demographic or economic data were 

available for this species to estimate 

adult losses or fishery valuation 

forage species 

(no economic valuation) 

forage species 

(no economic valuation) 

$82 

(ETM modeling applied to 

commercial fishery) 

8.260.000 

15.700.000 

15.500.000 

$10,060 

(ETM modeling applied to 

commercial fishery) 

— = not estimated 

* = entrainment estimates were not adjusted to the long-term (1990-98) Intake Cove plankton tow mean 

t = 2FH aligned to fishery-age adult equivalents 

TENERA E9-055.0 7-22 Final 316(b) Demonstration 

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7.0 Discussion 

Table 7-2a. Total annual entrainment mortality (PM ) and zone of extrapolation (1/ Ps ) as a 

multiple of study grid areas (using alongshore currents) or of study grid population (using 

alongshore and offshore extrapolation) for larvae ofthe two target crab taxa from Analysis 

Periods 3 (July 1997-June 1998) and 4 (July 1998-June 1999) estimated by using 2 methods of 

calculating Ps using maximum larval duration estimates through the megalops stage at DCPP 

and water current measurements. 

Ps calculated using alongshore 

currents 

Taxon Analysis 

Period ft 

brown rock crab 

slender crab 

3. 

3. 

4. 

0.00563 

0.00652 

0.0844 

0.0113 

8.3 

9.3 

8.1 

7.9 

Ps calculated using alongshore currents and 

extrapolating densities offshore 

'M ft 

0.0000186 

0.000146 

0.0107 

0.000784 

2.590.7 

417.6 

236.9 

114.2 

TENERA E9-055.0 7-23 Final 316(b) Demonstration 

March 1,2000 
7.0 Discussion 

Table 7-2b. Total annual entrainment mortality (PAI ) and zone of extrapolation (\/Ps ) as a 

multiple of study grid areas (using alongshore currents) or of study grid population (using 

alongshore and offshore extrapolation) for larvae ofthe 14 target fish taxa from Analysis Periods 

3 (July 1997-June 1998) and 4 (July 1998-June 1999) estimated by using 2 methods of 

calculating Ps using both mean and maximum larval duration estimates derived from lengths of 

entrained larvae at DCPP and water current measurements. 

Ps calculated using alongshore cunents - Ps calculated using alongshore currents and 

extrapolating densities offshore 

Taxon 

Pacific 

sardine 

northem 

anchovy 

KGB 

rockfishes 

blue rockfish 

complex 

painted 

greenling 

smoothhead 

sculpin 

snubnose 

sculpin 

cabezon 

white 

croaker 

monkeyface 

prickleback 

clinid 

kelpfishes 

blackeye 

goby 

sanddabs 

Califomia 

halibut 

Analysis 

Period 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

3. 

4. 

based on 

mean duration 

K 

— 

-

-

• -

0.0365 

0.0380 

0.00338 

0.0471 

0.0490 

0.0319 

0.105 

0.146 

0.102 

0.202 

0.0243 

0.0140 

0.0190 

0.0366 

0.162 

0.108 

0.318 

0.294 

0.190 

0.174 

0.0145 

0.0663 

0.00269 

0.175 

ft 

— 

-

— 

-

2.8 

2.5 

2.6 

2.0 

3.6 

3.6 

2.8 

3.0 

2.0 

1.5 

2.5 

1.4 

2.8 

1.9 

3.0 

2.4 

3.1 

2.7 

1.3 

1.2 

2.4 

1.8 

2.8 

2.3 

based on 

max. duration 

K, 

— 

-

_ 

-

0.0532 

0.0376 

0.00468 

0.0411 

0.0671 

0.0381 

0.153 

0.198 

0.144 

0.239 

0.0337 

0.0161 

0.0297 

0.0550 

0.232 

0.113 

0.410 

0.395 

0.228 

0.220 

0.0157 

0.0537 

0.00449 

0.252 

ft 

_ 

-

— 

-

5.1 

6.7 

4.1 

5.0 

6.2 

7.3 

7.3 

8.2 

4.3 

4.2 

3.5 

2.5 

5.5 

3.9 

6.9 

8.0 

7.3 

6.2 

2.4 

1.8 

3.2 

3.5 

6.1 

5.4 

based on 

mean duration 

K 

0.000284 

• 

0.000575 

0.00205 

0.0146 

0.0218 

0.000955 

0.0211 

0.00877 

0.0114 

— 

-

0.0361 

0.1206 

0.00683 

0.00835 

0.00255 

0.0211 

-

-

-

-

0.131 

0.163 

0.00493 

0.0459 

0.000835 

0.123 

ft 

47.3 

16.5 

7.9 

7.2 

4.4 

9.3 

4.6 

20.7 

10.3 

— 

-

7.0 

2.6 

9.1 

2.4 

21.2 

3.4 

-

-

-

-

2.0 

1.3 

11.7 

2.7 

8.9 

3.5 

based on 

max. duration 

K 

0.0000669 

* 

0.0000786 

0.000201 

0.00962 

0.00476 

0.000456 

0.00356 

0.00910 

0.00444 

-

-

0.0231 

0.0210 

0.00569 

0.00919 

0.00133 

0.00704 

-

-

-

-

0.0787 

0.179 

0.00413 

0.0106 

0.000763 

0.0525 

ft 

1.078.1 

683.8 

454.5 

29.5 

53.9 

42.1 

60.0 

47.7 

63.9 

-

-

39.3 

55.8 

21.8 

4.4 

127.5 

32.3 

-

-

-

-

8.6 

2.5 

22.4 

18.5 

35.9 

32.8 

"-"no calculations of this class made for this taxon 

* No Pacific sardine larvae were collected in paired entrainment and study grid samples for this period. 

TENERA E9-055.0 7-24 Final 316(b) Demonstration 

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7.0 Discussion 

c 

O 

a> 

JD 

E 

3 

Z 

CO 

c 

"5> 

ra 8> 

o 

Equilibrium Population -

( ^ ** * r^*J*f pt* 

r*' *' !_ .. ___H_r " . •- &*•* 

iffigs&^a^ . i ^ 

, 4 » 

Surplus Production 

Increasing Number of Adults 

Figure 7-1. Surplus production model. 

TENERA E9-055.0 7-25 Final 316(b) Demonstration 

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8.0 Conclusions 

8.0 Conclusion 

Section 316(b) ofthe Federal Water Pollution Control Act Amendments of 1972 (Clean Water 

Act) requires that the Diablo Canyon Power Plant (DCPP) cooling water intake structure 

represents the best technology available (BTA) to minimize adverse environmental impacts 

(AEI). As discussed in the Introduction of this report, the United States Environmental Protection 

Agency (USEPA) has indicated that assessment of AEI should be based on an evaluation of 

population-level effects. The results ofthe assessments on the 16 target taxa selected for this 

DCPP 316(b) study by the Entrainment Technical Work Group (ETWG) show no population 

level effects due to entrainment and impingement. Consequently, we conclude that the DCPP 

intake structure is not causing AEI. 

Since DCPP is not causing population-level effects, no consideration of alternative cooling water 

intake structure technologies for minimizing AEI is necessary. However, this report does include 

an assessment of alternative technologies in response to a requirement by the Central Coast 

RWQCB. The conclusion of this alternative technologies assessment is that the existing cooling 

water intake structure is the best technology available for DCPP. 

Summary of Effects 

• Populations ofthe five target taxa with pelagic eggs (Pacific sardine, northern 

anchovy, white croaker, sanddabs, and California halibut) are not adversely impacted 

by the DCPP intake indicated by generally low to moderate estimates of PKI, FH, or 

AEL. Furthermore, these taxa are protected against localized effects by having *>>-„,/ - '•-'•• * 

_________—. — • ,.',. , *~ 

widespread^opulations or spawning centers distant from DCPP. In the case of ,.,., v ^,-,,. 

California halibut, with a relatively high PKI , but low approximated FH, very few • "•"' 

,

 !

.- ,s <r. K S ' 

individuals are entrained at DCPP so there is no adverse impact on their population. .... iY 

• Both groups of rockfishes (KGB and blue rockfish complexes) had low numbers of 

estimated adult equivalent losses to their populations. Cabezon had low estimated 

larval mortality (<1%), based on extrapolations using the alongshore and onshore 

currents. This study also estimated that the larval mortality of painted greenling was 

generally below 1%, using similar extrapolations. In addition, brown rock crab and 

TENERA E9-055.0 8-1 Final 316(b) Demonstration 

March 1.2000 
P.96 

8.0 Conclusions 

slender crab had low estimated larval mortality. All of these species have populations 

that are distributed well beyond the zone of influence of DCPP. 

• The remaining taxa (smoothhead sculpin, snubnose sculpin, monkeyface prickleback, 

clinid kelpfishes, and blackeye goby) had larval mortalities that exceeded 10% in 

reference to that part ofthe population living in an area 2-8 times the study grid area. 

However, the area affected is only part of these species' geographic range. 

Therefore, these effects appear to localized and do not constitute population-level 

effects. 

• Ofthe five taxa with relatively high estimated larval mortalities, only two had 

corroborating evidence that local adult and juvenile abundance could be affected by 

the DCPP cooling water intake system: clinid kelpfishes and snubnose sculpin. Both 

subtidal observations of adults and long term plankton sampling of larvae showed 

declining numbers over recent years in the vicinity of DCPP. 

It is important to note that the corroborating evidence noted above for clinid kelpfishes and 

snubnose sculpin is based on limited sampling at one local subtidal sampling transect four times 

per year (as visibility permits) and weekly plankton tows at the mouth ofthe Intake Cove. 

Additionally, there is some evidence in southern California (Holbrook et al. 1996) that the effects 

of a regime shift in the California Current towards warmer water temperatures combined with 

successive El Nino events have continued to cause general population declines in more northerly 

distributed species (e.g., rockfishes). It should also be noted that the ETM methodology was 

originally developed and adapted for species with larvae dispersed throughout the study grid area 

and not for nearshore species. Clinid kelpfishes and snubnose sculpin are nearshore fishes and 

thus were undersampled by the study grid methodology. Both kelpfishes and snubnose sculpin 

(as well as the other nearshore species) are found in these inshore areas, and thus their larval 

mortality estimates could be overestimated. 

The effects ofthe cooling water intake structure estimated by the AEL and FH models did not 

include the very small losses due to impingement. When added to the AEL and FH estimates, 

these losses do not change the overall conclusion that entrainment effects ofthe plant's cooling 

water intake system do not constitute AEI for populations ofthe 16 target taxa for which 

assessments were made. 

TENERA E9-055.0 8-2 Final 316(b) Demonstration 

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8.0 Conclusions 

Using criteria supplied by the USEPA (1977) for determining the extent of AEI and 

supplemented by criteria specific to the present 316(b) study at DCPP, estimates of entrainment 

effects on the populations ofthe 16 target taxa presented in this report do not constitute AEI. For 

two ofthe nearshore taxa assessed (clinid kelpfishes and snubnose sculpin) there is some 

evidence of local decreases in both larval and adult abundance which may be attributable to 

entrainment of early life stages in the DCPP cooling water intake system. However, 

climatological and oceanographic conditions (e.g., regime shifts, El Nino events) may have 

contributed to these local declines to an unknown extent and should be considered. 

Alternative Technologies 

Alternatives to the current cooling water system evaluated for DCPP included seasonal refueling 

outages; reduction in annual operation; modifications to the traveling screens; sluiceways and 

their operation; expansion ofthe existing shoreline intake structure and installation of modified 

screening; and reductions in cooling water flow rates. In addition, consideration was given to 

transferring the ocean heat sink, open-cycle cooling process to land-based closed-cycle cooling 

towers. Each altemative is expected to offer some potential for reducing the losses of organisms 

resulting from entrainment or impingement. 

The judgment ofthe best technology available for the Diablo Canyon Power Plant is based on a 

consideration ofthe level of impact caused by entrainment and impingement on the marine 

community, demonstrated operation and reliability of various alternative technologies, and the 

biological effectiveness of these technologies for further reducing entrainment and impingement, 

engineering and operational feasibility, and cost effectiveness ofthe alternative technologies. 

Based on the evaluation of alternative intake technologies for DCPP it was concluded that: 

• There is no reasonable alternative intake location that would reduce entrainment and 

impingement losses. 

• Behavioral barriers would not reduce the numbers offish exposed to impingement or 

entrainment. 

• Media filters, barrier nets, and Gunderboom were determined to be not applicable at 

the DCPP site due to the large flow volumes, high debris loading, and potential for 

rough ocean conditions. 

TENERA E9-055.0 8-3 Final 316(b) Demonstration 

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8.0 Conclusions 

• Inclined screens, drum screens, and centerflow screens with fine mesh, would not 

significantly reduce impingement losses and have not been proven to substantially 

reduce entrainment losses. 

• Modifications to the intake screens and the addition of a fish return system could 

reduce the losses due to impingement. Because ofthe low numbers offish impinged 

on existing intake screens and the relatively high costs involved, installation of 

modified intake screens is disproportionate to the benefit. 

• Expansion ofthe intake structure to achieve a lower approach velocity or to provide 

an angled screen intake could reduce impingement. The cost of modification, 

however, is disproportionate to the benefits of reduced impingement. 

• Variable speed pump drives could be provided to allow reductions in circulating 

water flow to minimums required for plant operation. The design margins ofthe 

condenser system at DCPP could allow a 2 to 10 % reduction in circulating flow 

when ambient seawater temperatures are below 14.4 °C without exceeding discharge 

temperature limits. The high cost, uncertain reliability, and low biological benefit 

make this option impractical. 

• Seasonal patterns were detected for entrained larval fishes and some benefit has 

occurred when cooling water pumps are shut down for refueling and maintenance 

outages in spring and fall. Fewer larval fishes would be susceptible to entrainment if 

all outages were scheduled for the spring. However, scheduling outages to coincide 

with the seasonal distribution in abundance of a particular fish or group of fishes is 

not economically feasible, due to the characteristics ofthe nuclear fuel. 

• Consideration was given to curtailing power plant operation during spring months 

when density offish larvae was highest. In the current pricing structure practice for 

electrical production, the losses associated with nine month operation windows make 

this scenario not economically feasible. Replacement power from gas-fired facilities 

would also have a negative contribution to air quality because ofthe release of 

emissions that are not generated by nuclear facilities. 

• Closed-cycle cooling towers were evaluated to reduce entrainment and impingement 

losses. Cooling towers using saltwater would impact the land and biota with their 

TENERA E9-055.0 8-4 Final 316(b) Demonstration 

March 1,2000 
P.99 

8.0 Conclusions 

large "foot-print," corrosive fogs, vapor plumes, and salt drift. There is no resource 

large enough to provide freshwater makeup for cooling towers, and the addition of a 

seawater desalination plant of sufficient capacity would add considerably to project 

costs. The costs to retrofit closed-loop cooling towers to DCPP, which would require 

substantial construction, refitting, and redesign ofthe plant, would not be viable in 

the current or future power generation market. 

TENERA E9-055.0 8-5 Final 316(b) Demonstration 

March 1,2000 
P.100 

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