SEA TU RTLE ENTRAPMENT AT A COASTAL POWER PLANT 

Rob e rt G. Ernest, R. Erik r~artin, Bruce D. Peery 

a nd Douglas G. Strom, Applied Biology, Inc., P.O. 

Box 974, Jensen Be ac h, Florid a 34958 ; J . Ro ss 

Wilcox, Florida Powe r & Li ght Comp any, P.O. Box 

14000, Juno Beach, Fl ori da 33408 ; and Nancy W. 

Wa l ls, Appl ied Bi ology, Inc . , 29 68-A No rth Decat ur 

Road, De cat ur , Geo rgia 30033. 

I NTRODUCTl ON 

Florida Power & Light Compa ny (FPL) operates two 850-r~W nuclear-fueled 

electric gene r ati ng un its on Hutchi nson Isla nd, St. Lucie Cou nty , Florida. 

Both units of t he St. Luci e Pla nt coll ecti vely drdw and disch arge oncethrough conde nser cooling water t hrough an enc losed cana l system connected 

wit h the Atlanti c Ocean vi a submerged pi pe s. Alt hou gh the offs ho r e structures housing the intake pipe s were design ed to mi nimize ent rai nment of 

nektonic organisllls, they appa rently act as attrac tant s t o se a turtl es. 

Upon entering the i ntake pipes , t he turtl es are rapidly transported i nt o 

the canal system where they remain entrapped until manually captured and 

ret ur ned t o t he oc ean. 

Pot ential environmental lssues relating to plant siting, de sign , 

construction and operation were addressed during permitting and licensi ng 

phase s of plant development. In response to concerns raised by regulato ry 

agen cies, severdl design modifications were implemented. Addi tionally, 

bas el i ne studies, including nesting surveys of the Hutchinson Island sea 

turtle rookery (Gallagher et al., 1972 ; Worth and Smith, 1976), were con270 
ducted to establish background information on resident biotic commun i t ies. 

After a series of site certification hearings and satisf actory demonstra -

tion of environmental safeguards, the St. Lucie Plant received its 

operating license , and the first unit was placed on line. 

The importance of the Hutchinson Island sea turtle rookery was clearly 

understood at the time of li censi ng negot iations (Rout a, 1968). Preoperationa l and operational monit o ri ng focused on the potential disruption 

of nest i ng activities caused by plant construction and subs equent di s charge 

of the rmal effluents (O'Hara, 1980; Williams-Walls , et a1., 1983 ; Proffitt, 

et a1., 1986 ). However, the potential for en training sea turtles with co ndenser cooling water was never realized until the pla nt began operating. 

Soon after Unit 1 was placed on li ne, occasional sitings of sea 

turtles in the intak e cana l were report ed. Concern for the ir safety 

prompted development of an efficient, non-injurious cdPture techn ique. 

Borrowing materials and experience from other researchers and local fishermen, a large -mesh "tangle" net was assembled and deployed . Immediate success in capturi ng turtles demonstrated its app li cability . 

As the sc op e and persistence of sea turtle entrainment at the St. 

Lucie Plant became apparent, a long-term canal captu r e and reporting 

program was de veloped in coop eration with the Florida Department of Natural 

Resources and the U.S. National Marine Fisheries Service. Capture methodologies evolved ove r the first several years as net ma teri als , configurations and plac ement were varied in an effo rt to red uc e entrapmen t times and 

271 
thereby minimize potential inju ri es and trauma to the turtles. Alternative 

capture techniques were also evaluated. 

Methods of preventing se a tu rtles from entering the intake canal of 

the St. Luc ie Plant were examin ed concurrently with the refinement of capture t echn iques. Enginee ri ng. l ega l and safety constra i nts precluded 

installat ion of physical ba rrie rs at t he mouth of the offshore pipes. 

Co ns equent ly, laboratory studies con centrated on identi fyi ng effective 

dete rrent mechani sms . 

t ifi ed . 

To da te, no pract ical deterrents have been ide nTh e principal objective of the St. Lucie Plant cana l capture program 

is to remove entrapped sea turtles from the intake canal and return them to 

t he ocean as quick ly and with as little stress as possib le. Howeve r, in 

t he process, a great deal of info rmation relating to their biology and ecology has been obtained . As with most large, far-r ang ing ma rine anima ls, 

collecting data from live t urtles in the field is both diffi cult and 

cost ly. Consequently , most researchers have rel i ed on information obtained 

f rom adult nesting females, hatchlings, juvenil e/sub-adults maint a i ned 

unde r ca ptive conditions and stranded individuals. By contrast, the St. 

Luc ie Plant serves as a static offshore collection device, providing a cont inual supply of specimens of both sexes and a wide range of size classes. 

This unique opportunity to examine the local sea turtle population has been 

exploited t hrough an extensive data collection program. 

272 
This paper describes the canal capture program currently in effect at 

the St. Lucie Plant and presents some of the data collected over a lO-year 

period beginning in 1976. Size-frequencies, recaptures and sex ratios are 

discussed relative to their implications to management policies affecting 

these threatened/endangered species. 

273 
MATERIALS AND METHODS 

Plant Description - Hutchinson Isla nd is one of a chai n of barrier islands 

separating the shallow Indian Rive r Lagoon fr om the Atlantic Ocean along 

Florida's lower ea st coast (Figur e 1) . The St. Lucie Pl ant is loca t ed on 

the island on a 437-hectare site mid way between the Ft . Pie rc e and St. 

Lucie In lets (27°21' N; Soo14'W) . At thi s latitude, the conti nent al shelf 

margin is approximately 33 km offshore. The Flor i da cur rent flows roughly 

paral l el to the margin but close r to shore (Gallagher and Hol linge r, 197 7), 

and a weak counte r current is usually present near shore. Mean tid al range 

in t he Atlantic Ocean in the vicinity of the plant is about O.S m. The 

adjacent sea bottom co nsists of shifting sa nd and shell rubble with occasional rock and ree f ou tc rop pings. 

Co ndenser cooling water for the St. Lucie Plant is drawn from the 

Atlanti c Oc ean through two 3. 7 m- and one 4.9 m-diameter pipes that rise 

vertically from the sea floor withi n separate reinforced concrete housings. 

Th ese structures are located in approx imately 7 m of water 365 m fran shore 

(F igure 1). 

Each of the intake housings is fitted with a 15.S m-wide velocity cap. 

The caps, whi ch are elevated 2.4 m above the mouth of the intake pipes, 

eliminate vertical draw. Maximum horizontal intake velocit ies at the caps 

a re about 30.5 and 12.5 cm.sec- 1 for the largest and smallest pipes, 

respectively. At mean low water, the caps are 2.4 m below the surf ace . 

274 
N 

......., 

U"1 

~ 

~ 

HUTCHINSON 

ISLAND 

~ 

O~ 

~~ "%-0 

/ '" 

Figure 1. St. Lucie Plant site location. 

L u C I ~ 

o 250 ')00 

M ETERS 
Within the largest and smallest pipes, water velocities i ncreas e to 

206 and 127 cm .sec- 1 respectively. The pipes travel shoreward be neath the 

sea fl oor, beach and dunes and terminate within two headwalls at the 

eastern end of a 1,500 m long, L-shaped i nt ake canal (Figure 1). This 

canal transports cooling water to the pl a nt. Water velocities within the 

canal are about 21 cm.sec-I. 

At the plant, cooling water is drawn from the bottolll of eight separate 

intake wells ( four for each unit). Water passes through a series of coarse 

grates, small er mesh trave 11 i ng sc reens and fi na 11y through the condenser 

cooling system. Heated water is discharged into a 670 m-long canal that 

l eads to two buried discharge pipelines. Thes e pass beneath the dunes and 

beach and along the ocean floor to submerged discharges, the first of which 

is approximately 365 m offshore and 730 m north of the intake structures. 

Offshore construction of the Unit 1 intake and discharge systems took 

place between 1974 and 1976, with Unit 1 being placed on line in March 

1976. Unit 2 intake and discharge lines were installed between 1981 and 

1983, and Unit 2 became operational in May 1983. When operating at fu ll 

capa city, each unit di scharges approximately 32,350 1 of heated effluent 

per second (738 million gallons per day). 

Sea Turtle Capture and Data Collection - Turtl es entrained with cooling 

water are generally confined to the easternmost segment of the intak e canal 

between the headwalls and a barrier net located at the Highway AlA bridge 

(Figure 1). Water flow is low enough to pennit turtles of all sizes to 

swim freely throughout this portion of the canal. 

276 
Over the years, nets used to capt ure turtles varied in length, were 

2.7 to 3.7 m in depth and made of 40. 6 cm stretch mesh, multi -st rand nylon. 

Large fl oats we r e attached to the surf ace 1 i ne and unwei ghted nylon rope 

was used on the bottom. The nets were usua ll y deployed on Monday morni ng 

and retrieved Friday afternoon and were checked severa l times a day for 

captures. Turtles entangled in the nets floated at the water's surface 

unt i 1 removed. 

Larger turtles occasionally breached the AlA barrier net, and turtles 

smaller than 30.5 cm i n carapace width could pass through its large mesh. 

Thus, as required, nets were also fished on the western si de of AlA and in 

the vicinity of the plant's intake wells. Turtles not captured by nets 

were eventually rBnov ed f r om the canal at the plant 's intake wells. 

Captured turtl es we re ident i fi ed to speci es, meas ured and wei ghed. 

Straight-line cara pace l engt h (SLCL) was meas ured from the precentral scute 

to the notch between the postcentral scut es (mi nimum carapa ce length of 

Pritchard et al., 1983). Cu rved carapace length , straight-l i ne and curved 

carapace width, st raight-li ne plastron length and tail length were also 

recorded. Adult turt les (SLCL >80 cm) were sexed based on relative tail 

lengths. 

Beginning in 1982 , blood samples were routinely collected and analyzed 

to detennine the sex of immature turtles and to examine t he relationship of 

hemoglobin values to the apparent physical c ond ition of captured animals. 

Blood was rBnoved from the paired dorsal cervical sinuses using the tech277 
nique of Owens dnd Ruiz (1980). A single , sub-sample of whole blood wa s 

drawn and hemoglobin measured in grams per 100 ml by colorimetry using an 

A.O. 10100 hemoglobinometer. The remainder of the bl ood was then centrifuged for 15 minutes to separate cel ls and serum. Sex determinations were 

subs equ e ntly made by researchers at Texas A&t"1 University using a radioimmu noassay for serum testosteron e (Owens et a l ., 1978) . Beginning in 1984, 

blood ce ll samples were prov ided to the National Marine Fisheries Service 

for the purpose of developing and r efining meth od s for use in conducting 

turtle stock analyses. 

Each turtle captured wa s examined for ov e ra l l condition and s ubjectively ranked according to f ive reldtive cond i tion categories based on 

weight, amount of activity exhibited, coverage of barnacles and/or leeches 

and occurrence and severity of wounds. Both systemat ic and occasional 

col lections of fouling organisms (Frazier et al., 1985) were also made to 

identify potentially unique macrofaunal associations and to provide data 

r elat ing to sea turtle migratory patterns. 

Turtles were tagged with standard Monel or Inconel metal cattle ear 

tag s on one or both front f1 i ppers and rel eased back into the ocean at 

s eve ral locations on Hutchinson Island. Occasionally, turtles were provided to other researchers for use in behavioral studies. 

278 
RESUL TS 

Speci es Abundance - Du ring the period from May 1976 through December 1985 , 

a total of 1,310 sea turtle captu res took place in the intake can al of the 

St. Lucie Plant (Table 1). Of the five spec ies encountered, the loggerhead 

(Caretta caretta) was by far the most abundant (1,127 captures) . Green 

turtles (Chelon ia mydas) we r e the second most abundant (170 captures) 

followed by leatherbacks (Dermochelys coriacea ; 7 capture s), Kemp' s ridleys 

(Lepidochelys kempi; 3 captures) and hawksbills (Eretmoche lys imbricata; 3 

captures). 

Annual catches of loggerheads ranged from 33 i n 1976, a partial year 

of plant operation, to 173 in 1979 (Table 1); the mean annual catch, 

excludi ng 1976, was 121.5. Green tu r tles were caught during every year of 

plant op eration except 1976, but we r e mos t numerous in 1984 (69) . The 

average annual catch of green tu r tles wa s 18 .9. 

Si ze-Cl ass Di stri but ions - Loggerh eads removed from the i ntake canal 

ranged in length (SLCL) from 41.5 t o 112. 0 cm (i = 64.9 ~ 11.7 cm) and in 

weight fran 10 . 9 to 154.7 kg. Loggerheads as small as 74 cm standard SLCL 

(approximately 71 cm minimum SLCL; Henwood and Moulding, unpublis hed data) 

have been reported nesting along the east coast of Florida (Ehrhart, 1980). 

However, adults can only be reliably s exed on external mo rpholog i cal 

characteristics (e .g ., relative tail length) after attaining a length of 

about 80 cm. Based on these divisions, da ta were segrega ted into three 

groups : juvenil e/sub-adult s «70 cm; t he dema rcat i on between these two 

279 
Table 1 

Total Number of Sea Turtles Captured Each Year in the St. Lucie Plant Intake Canal 

May 1976 - December 1985 

Species 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 Total 

Loggerhead 33 80 138 173 116 62 101 119 148 157 1,127 

Green 5 6 3 10 32 8 23 69 14 170 N 

(Xl 

0 Leatherback 1 3 2 1 7 

Hawksbill 1 1 1 3 

Kemp's ridley 1 2 3 

Total 33 86 148 176 126 97 110 142 220 172 1,310 
c ompon ents i s not well established in the literature) , adu lts (>8 0 cm) and 

transitiona l (70-80 cm). The latter group probably includes some mature 

and some immat ur e i ndividua l s. Of the 969 ind iv i du al s f or wh ich length 

data were co l l e ct ed , 76 perce nt we r e 70 cm or less in l ength , the majori t y 

of these mea s uri ng between 50 and 70 cm SLCL (F i gure 2 ) . About 11 pe r cent 

of loggerhead cap t ur e s invo lved adults, the r emaini ng 13 pe rcent representing individuals i n t he t ra ns itional s i ze c la ss. 

Green t urtl e s captured over the t en ye ar study pe r iod r an ged in length 

from 20 t o 108 cm SLCL (x = 36.2 2:. 14.6 cm) and in weight f rom 0. 9 to 177. 8 

kg. Unlike logge rhead s, all gree n tu rtles fel l into e ither the 

juvenile/sub-adult or adult ca t egories ; i ndiv iduals were e ithe r less than 

66 cm or greater th an 93 cm in length (Figure 3) . The ma j ority of greens 

captured (7 6 pe r cent) invo l ved i ndivid uals less tha n 40 cm i n length and 9 

kg in weig ht. On l y fi ve of the green t urtles removed fr om t he i nt ake can a l 

were adults. 

Seasonal Distri bu ti ons - On a seasonal bas is , both l ogge r head s and green 

turtles occu rred with t he grea t e st frequ ency in wi nt e r . Th i rty-four percent of a l l l og ge rhead captures occu rred between January and March. 

However, when adu lt and j uvenile/s ub- ad ult s egments of the po pulation we r e 

analyzed separat e ly, distinct d ifferences in sea sonal ab undances were evident (Fi gur e 4) . J uve nile/sub- adults we re most ab un dant dur ing the winter, 

whereas adults we re captu red most often in summer; nearly 65 percent of all 

adult loggerhead can al ca ptures occ ur red bet ween June a nd Septembe r . 

281 
300 -

(/) 

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Z 

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N =969 

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r- .-- 1--'-- t--

r- t---"l- I I I I I I I I I I I I I I 1 

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 

STRAIGHT LINE CARAPACE LENGTH (em) 

Figure 2. Size-class (SLCL) distribution of loggerhead turtles 

captured in the St. Lucie Plant intake canal, 1976-1985 

( N=969) • 

282 
CJ) 

~ 

« 

::J 

0 

> 

0 

Z 

lJ.... 

0 

a: 

w 

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Z 

60 N .: 153 

50 

40 

30 

20 

10 

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95100105110115120125 130 

STRAIGHT LINE CARAPACE LENGTH (em) 

Figure 3. Size-class (SLCL) distribution of green turtles cap 

tured in the St. Lucie Plant intake canal, 1976~1985 

(N=153) • 

283 
20 - JUVENILE LOGGERHEADS 

N= 776 

I--

10 ~ 

-

- .--- r-- ~ 

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 

C/) 

W 

a: 20 ADULT LOGGERHEADS 

:::> N =112 Ia.. 

<t 

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~ 10 

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(.!) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 

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N=149 

40 

20 

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 

MONTH OF CAPTURE 

Figure 4. Percentage of all juvenile loggerheads (N=776), adult 

l oggerheads (N=1l2) and juvenile greens (N=149) cap 

tured each month in the St. Lu c ie Plant intake canal, 

1976-1985. 

284 
Th e s e asonal distribu tion of yreen tu rtles was very s kewed , 62 pe rcen t 

of all captures occu r r i ng duri ng Janua ry and February (F i gur e 4) . Cat c hes 

of other species were scattered t hr oughou t t he t en-year study peri od. All 

but one of the seven leatherbac ks we re co llected i n Feb r uary, March and 

April • The hawksbill s we re capt ured in March, July and August and the 

Kemp's ridleys in Janu a ry and Feb ruary. 

Sex ratios Since 1982, 142 i mmat ure loggerheads (d efined by Wibbels et 

al . , 1984 a s individual s l ess than 76 cm SLCL) we r e s exed by means of 

radi oimmunoassay for bl ood t estoste r one . Females outnumbered males by a 

ratio of 2.38:1.00. Thi s r ati o i s signi f i ca ntly skewed in favor of females 

2 _ (X , P - 0.05). 

Recapture Frequencies - Of the 1 , 310 s ea turtle cap t ures recorded between 

1976 and 1985, 54 r epr esent tu rtl es pre vi ously captured in the i ntake 

canal. A total of 32 l oggerheads and one green were captured more than 

once, one loggerhead be i ng captured on six diff ere nt occ asions. Recapture 

intervals for loggerheads rang e f r om 4 to 858 days wi th a mean of 126.7 

days (s.d. ~ 151. 3 days). Abou t 60 pe r ce nt of all recapture incidents 

occurred within 90 day s of previou s capt ure a nd 94 percent occurred within 

one year (Figure 5). The average period between first and last capture for 

loggerheads was 215 . 4 days (s . d. ~ 202. 9 days) . Over 80 percent of the 

recapture incidents involved juve nil e/sub-adu l ts. 

285 
100 • 

80 

W 

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a: 

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interval between successive captures 

o- - ----<l interval between first and last capture 

200 300 400 500 600 700 800 

RECAPTURE INTERVAL (DAYS) 

Fi gure 5. Cummu l ati ve percent age of al l l oggerhead re captures 

occu r ri ng within various time intervals , St. Luc ie 

Pl ant intake canal , 1976-1985. 

900 
DISCUSSION 

Hutchinson Island suppo rts a large nesting population of loggerheads 

and to a much 1 esser extent some nest i ng by greens and 1 eatherbacks 

(Williams-Walls et al., 1983) . During 1985, 4,877 loggerhead, 64 green and 

18 leatherback nests were recorded along its 36.0 km shoreline (ABI, 1986). 

Canal capture data for the St. Lucie Plant indicate that the nearshore area 

adjacent to the plant also suppo rts substantial numbers of juvenile/subadult loggerheads and greens . Periodic incursions by immature Kemp's 

ridleys, leatherbacks and hawksbil ls were also evidenced. 

Nearshore coastal areas along the eastern seaboard of the United 

States apparently serve as migratory pathway s and/or aggregation areas for 

juvenil e and sub-adult loggerhead and green t urtl es. In Flori da, re 1 at ively large numbers of loggerheads hav e been reported from the Port 

Canaveral ship channel (Ogren and McVea, 1982) and both species have been 

collected in the Mosquito and I ndian River Lagoons (Ehrhart, 1983). 

Incidental catches of loggerheads in shrimp trawlers sug ge st similarly high 

abundances of immature animal s off t he coasts of Georgia and South Carolina 

(Hillestad et al., 1982). Although habitat utilization during different 

juvenile and sub-adult stages of the sea turtle life cycle is poorly 

understood, the importance of Atla ntic coastal waters a s a developmental 

habitat is becoming increasingly clear. 

287 
The degree to which canal capture data reflect the structure and dynamics of the population at large is primarily dependent on behavioral 

characteristics of each species. Only those i ndividuals with i n a relative l y limit ed nearshore area a re susceptible to entrainment. However, for 

the purpose of this discussion , it is assumed that there is no intraspecific discriminant avoidanc e of the intake structures between sexes 

and/or s ize cl asses. 

Size-class data for logge rh eads entrapped in the St. Lucie Plant 

intake canal show a pr eponderance of juveniles/sub-adults within the "local 

population". Very similar size-frequency distributions have been reported 

for the Canaveral ship channel (Ogren and McVea, 1982), Mosquito/lndian 

River Lagoon (Mendonca and Ehrhart, 1982), and Georgia and South Carolina 

coastal waters (Hillestad et al., 1982). In none of the populations 

sampled did adults account for more than 15 percent of the total catch; 11 

percent of the Hutchinson Island population was comprised of adults. 

Although it is possible that habitat segregation and/or gear selectivity 

may favor capture of juvenil es/sub-adults over adults, the s imil arity of 

three geographically discrete data sets suggests a relatively uniform popu1 at i on structure throughout inshore coastal waters of the southeastern 

Un ited St ates. 

Also strikingly similar among east coast loggerhead "populations" is 

the lack of individuals smaller than 40 cm in carapace length. Carr (1986) 

recently elaborated on an ecologic mechanism to explain the "lost year" in 

loggerheads, a period during which post-hatchling turtles are rarely 

288 
encountered in coastal waters. Nurtured by fo od suppl i es concentrated on 

the surface by oceanic f ronts and convergences, the small loggerheads 

leaving natal beaches may drift for four or five years in the currents and 

eddies of the Nort h Atl antic gyre before finally leaving the pelagic 

environment to adopt a benthic mode of existence. Data from the Azores, in 

the eastern Atla ntic, and f rom the east coast of Fl orida , including 10 

years of canal capture data from the St. Lucie Plant, are cons istent with 

this hypothesis. 

By compa ri son, the rna j 0 rity of green tu rt 1 es captu red in the St. Luc i e 

Plant intake canal was less than 40 cm in length, suggest ing that greens 

depart the pelagic habitat at a smaller size than loggerheads. The canal 

capture data also indi cate tha t green turtl es appear in south Florida 

coastal waters at a sma l ler si ze than has been documented for most other 

coastal areas. In Hawaii and Australia, juvenile greens are not seen 

inshore until they reach a si ze of about 35 cm (Balazs, 1982; Limpus and 

Reed, 1985). Likewi se, of the hundreds of Chelonia examined by Carr and 

Caldwell (1956) in the Cedar Key-Crystal River region of west Florida, the 

smallest was 13.5 inches (34.3 cm) long. Only i n the Virgin Islands are 

there accounts of tu rtles less than 30 cm occurring with regularity in 

coastal waters. Schmi dt (1916) reported that individuals between 23 and 30 

cm in length were common there duri ng J anua ry , Feb ru ary and March, the same 

period during which the Inajori ty of small gree ns are taken at the St. Lucie 

Plant. Whether animals of this size range are actively leaving the pelagic 

envi ronment or are phys i ca lly bei ng forced from i t by wi nter di sturbances 

remains to be determined. Because much of the hi stori ca 1 i nformat ion 

289 
relating to the population structure of green turtles has been derived from 

tu rtles captured by net, gear selectivity cannot be overlooked when 

accounting for t he "absence" of sma ll turtles in areas otherwise known to 

support juveniles and sub -adu l ts. 

There is relat ively little publi shed informa ti on regarding green 

turtles i nhabit ing coastal wat ers of the southeaste rn United States. The 

St. Lucie Plant canal capture data and previous publi shed reports of 

turtles in the t~osquito/lndian Ri ver Lagoon al l ow comparison of green 

turtle "populations" utilizing t wo distinct envi ronments wit hin this 

coasta l zone. 

The average size of the Mosquito/Indian River Lagoon green turtles was 

48.2 cm, with 60 percent of all individuals mea suring between 50 and 70 em 

and on l y one percent measuring less than 30 em (Mendonca and Ehrhart, 1982 ; 

Ehrhart, 1983). By comparison, gre en turt les captured at t he St. Lucie 

Plant averaged 36.2 cm SLCL with less than nine percent measuring between 

50 and 70 cm and over 40 percent measuring less than 30 cm. In both areas, 

animals i n the 75-90 cm size range were absent. Some adults larger than 90 

cm were captured at the St. Lucie Plant, whereas no adults were taken in 

the Mosquito/Indian River Lagoon. The absence of adults and the generally 

larger size of the Mosquito/Indian River Lagoon green turtles c~npared with 

those from the St. Luc i e Pl ant suggests di st i nct ly different popul at ion 

structures between the two areas. 

290 
Mendonca a nd Ehrh a r t (1982 ) provided strong evi dence to indicate th at 

green turtl es use Florida' s coastal bays and lagoons as development habitats, foraging on the seagrasses that constitute their principal diet 

(Mortimer, 1982; Mend onca , 1983, Bjorndal, 1985). Historically, the se 

inland waters support ed large populations of green tu rtles (Ehrhart, 1983). 

As juveniles, gr een turtles experi ence a transition in diet fr om omnivory 

to herbivory (Ernst and Barbour , 1972 ; Carr, 1980; Davenport and Oxford, 

1984). Until this transition is comple te, there is probabl y no compelling 

need for small greens to enter inland waters. Consequently, following the 

pelagic stage, many of these smalle r animal s may spend an extended period 

in the nearshore coastal environment. This would ac count for the preponderence of small turtles off Hutchinson Island. It would follow that as an 

herbivorous diet becomes increasingly more important to their existence, 

they eventually migrate inland where attached vegetation is much more abundant. 

Mendonca and Ehrha rt (1982) sugge sted that as the green turtles within 

the Mosquito/lndian River Lagoon ap proach maturity, they begin to leave the 

lagoon. The absence of turtles in t he 70- 90 cm size classes off Hutchinson 

Island indicates that this transiti onal grou p may leave Florida coastal 

waters all together. It is likely that this size range represents individuals being recruited back i nto the parent populat i on to begin alternate 

migrations between traditional breeding and foraging grounds (Meylan, 

1982). Whether the se same animals will event ua lly constitute all or part 

of the Florida nesting populat ion is unknown. 

291 
The heavily skewed seasonal distribution of green t urtles off 

Hutchinson Island probably reflects me as ured movements of this species in 

response to changing environmentd1 conditions and/o r changes in envi ronment al requirements (Carr, 1980). Bot h geographi cal and local movements are 

likely to increase as water t emperatur es begin to decline (Mendonca, 19U3 ). 

Additionally, northeasterly storms Illay extirpat e some "lost ye a r " tu rtles 

from the pe l agic environlllent, th us increasing t he number of small tu rtles 

found near shore during the wint e r. Mu ch additional informa t ion \"Ji11 be 

required to determine th e r elat ive contri bu tion of each of these facto rs to 

seasonal abundance patterns of green turtles at the St . Lu cie Pl ant . 

Alt hough not as ext rene as that observed for green t urtl es , t he seaso -

nal distrib ution for juvenile/sub-adult loggerhead turtles was also skewed 

toward colder months of the year; 40 percent of all captures occurred bet-

\'~een January and r~arch. By contrast the most produc tive capture period for 

loggerheads in the Mosquito/lndi an River Lagoon was between April and 

October when hi ghest water temperatures preva i 1 ed (Mendonca and Ehrhart, 

1982). This may suggest seasonal migrations of loggerheads between inland 

and coastal waters and would ac cou nt fo r the relatively brief residence 

time observed for Caretta in the Mosquito/Indian River Lagoon. 

Adult l oggerheads, although present th r oughout the year. were 1Il0st 

abundant during the summer. May through August repres ents the nesting 

season fo r l oggerheads on Hutchinson Island. with peak nesting occurring in 

June and Ju ly (W i lliams-Walls et al ., 1983 ). Females approaching the beach 

have a greater ch ance of encounteri ng the intake structures than t hose 

292 
rel:1dining offshor e, and as the nesting act ivities of females increase, 

cdnal captures of ad ul ts i nc rease accordingly. 

Males and females were captured in nearly equal numbers between 

November and April, indi cating some inshore/offshore or latitudinal movements on a regula r basi s. However, during the summer, females were captured with over s i x times the frequen cy of mal es. Although the timing and 

location of mating is not well document ed, cop ul at ion is believed to occur 

off nesti ng beaches prior to the nest i ng season (Ernst and Barbour, 1972; 

Geldiay et al., 1982, Mr oso vsky, 1983) . St. Lucie Plant data suggest that 

either lIIatiny off Hut chinson Island i s conf ined primarily to waters more 

distant fran shore than the intake struct ures or that reproductively active 

males are less attrac ted to the structu r es than a r e females. Changes in 

behavi ord 1 characteri s tics of sexually act i ve male turtles have been previously reported (Booth and Peters, 1972 ; ~a la zs, 1980). 

Repetitive capture s of ind i vidu a ll y marked turt les in the St. Lu c ie 

Plant intake canal provide some clues as to the lenyth of residence within 

the Hutchinson Island population. Ove r the la-year monitoring period 32 

logyerheads and one green turtle were captur ed Iilore than once. These 

turtles represent 2.6 percent of the 1,2 56 i nd ividuals removed from the 

canal during that period. Turtl es were released at numerous locations 

along the island, and there was no c lear evidence of association between 

s He of rel ease and probabi 1 i ty of recapture . The longest peri od between 

first and last capture was less than 30 months, the average interval being 

a little over six month s. Assuming no le a rned avoidance behavior to the 

293 
intake structures, the data suggest a relatively brief residence ti me 1n 

the Hutchinson Island population. Although tag retention may be a 

hindrance to monitoring individual turtles on a long-terlll ba sis (Carr, 

1980; Hughes, 1982; Henwood, 1986), the general la ck of individu a ls i n the 

canal wi th tag scars i ndi cate a true absence of 1 ong-t ime res iden t s. 

Similar findings \'Jere made for both greens and loygerhe ads 1n t he 

Mosqui to/ Indi an Ri ver Lagoon where the longest obs erved res idence times 

were 20 and 15 months, respectively (Mendonca and Ehrhart, 1982) . 

At least some of the loggerheads released from the canal are known to 

have migrated elsewhere~ Two tagged loggerheads were recovered in Nort h 

Carolina, one in South Carolina, one in Georgia and one near St. Auyu stine, 

Florida. Two others were found stranded along beaches just north of the 

study area. 

tions, all 

For the five tag returns received from the most di stant locainvolved juvenile/sub-adults (50-70 cm SLCL) relea sed in 

January, February and March; all were recovered between July and December 

of the same year. Thus, some turtles not only leave the immediate area of 

the plant but travel considerable distances over relatively short time 

spans. Although no turtles released from the St. Lucie Plant have been 

recovered to the south, three sub-adult loggerheads tagged in the Canaveral 

s hip channel were later captured at the plant. 

Long-range movements of adult females nesting on the east coast of 

Flori da have been reported (Meylan et a1., 1983), but little published 

information exists for the juvenile/sub-adult segment of this "population". 

Th i s is related primarily to the general inaccessibility of non-adult 

294 
turtles. Comp ared with stu dies of ne sting females, r elative ly f ew r esearch 

activiti es a re di r ected t oward the captu re and tagging of i ndividu a l s in 

the 40-70 cm s i ze range, even t houg h this i s the most abu ndant compone nt of 

the nearshore popul ati on. Most tag r etu r ns from immatu r e turtles come from 

i nci dental captures in f i shi ng gea r and st r and i ngs on seasonally moni tored 

nesting beaches. Con s equently , t ag ret urns f rom cana l- c aptured turtl es, 

although few in numb e r, may reflect a substantial amoun t of mov ement within 

the juven i 1 e/sub- adul t segme nt of t he we stern Atl a nt i c logge r head popul ation. Becaus e overall canal ca ptures ha ve not decl i ned ov er the years of 

plant op e ration , it al s o ap pears t hat emig r a t i on f r om and immi gration into 

the Hutchinson Isl a nd a rea is rel ati vely wel l bal a nc ed . 

Until recently , sex r ati os of sea turt l e popul ati ons were based primarily on counts of adults i n the wil d . Observed f req uenci es often varied 

considerably between l oca ti ons and s e ason s (Ross, 1984) and sex-dependent 

behavioral ch a ract e ri sti cs made int e r pret a tion of r at ios di fficu lt (Balazs, 

1980; Limpus and Re ed , 1985 ) . A r e la t i ve ly new r adi oimmu noassay technique 

now permits safe and easy sexiny of j uveni le/s ub-adult ani mals (Owens and 

Ruiz, 1980). Be caus e of th ei r re l a t i ve abundance i n the Hutc h i nson Island 

population and thei r availability year aroun d, j uve nile/sub-adult 

loggerheads lend th ~ns lve s ni ce l y to stud i es of pop ulat i on sex ratios. 

For juvenile/sub - ad ult l oggerheads taken f rom t he St. Lucie Plant 

intake cdnal, f ellial es s igni fic an t ly outnumbered mal es by a r at io of 2.4 to 

1.0. Wibbels et al . (19 84) s imilarl y found t hat t he sex ratios of immature 

loyye rheads taken from t he Ca navera l ship channel were si gn ificantly skewed 

295 
in favor of females. These data taken collectively with information from 

the Indian River and the Chesapeake [)ay prompted Wibbels et al. (1984) to 

hypothesize that a skewed but similar sex ratio exists throughout US 

coastal waters, and individuals within the region may constitute a single 

population. Various explanations for, and the adaptive significance of, a 

fanale-skewed population have been presented (Balazs, 1980; Mrosovsky, 

1980), but at present, additional data from a number of different locations 

and over longer time intervals are needed to substantiate the uniformity of 

the loggerhead sex ratio in US coastal waters. 

The St. Lucie Plant canal capture program has provided new data and 

augmented existing data relating to the biology and ecology of sea turtles. 

As the data base continues to grow, it should provide invaluable insight 

into seasonal abundances, sex ratios and population structures of "local" 

loggerhead and green turtle populations. Because of its long-tenn nature, 

the St. Lucie Plant canal capture program may constitute one of the most 

important gauges available for monitoring sea turtle population dynamics 

over time. This information will hopefully play an important role in 

modifying existing and developing new management plans to ensure the continued survival of sea turtles inhabiting US coastal waters. 

296 
ACK NOWL EDGEM ENTS 

The authors wish to thank those individuals who have, over the years, 

contributed to the success of the St. Lucie Plant canal capture program. 

In particular, the evolution of the current program owes heavily to Robert 

Gallagher, Dave 'HerrelOa, Edward Meyer and Dewey Worth. Additionally, many 

long hours of turtle wrestling, tagging and measuring were spent by ABI 

staff biologists, including Michael Bayle, Joel Burgess, Barbara Graunke, 

Gregory Grunzel, Sara LeCroy, Gr aham Lewis, Joseph ~ackay, Allen Minton, 

Kathryn Muldoon, Kenneth O' Brien, Ed Proffitt and Nicholas Whiting. The 

National Marine Fisheries Service (NMFS) supplied tags and applicators for 

the tagging program and routinely f urnished tag return information for 

inclusion into the canal capture dat a base. For their cooperation, our 

thanks go to Mr. Fred Berry and Ms. Barbara Schroeder of the NMFS t~iami 

Laboratory. Dr. David Owens and Mr. Thane Wibbels of Texas A&M University 

graciously donated their time to analyze blood samples and provide sex 

detenninations. Discussion of methodologies and exchange of information 

with Dr. Lew Ehrhart and his students at the University of Central Florida 

enhanced our understanding of Florida sea turtle populations. We would 

also like to thank Dr. Ehrhart, Dr. Terry Henwood and an anonymous reviewer 

for their valuable crnnments on an earlier draft of this manuscript. 

Funding for the canal capture program was provided by Florida Power & Light 

Company. They have also provided both encouragement and financial support 

for the publication and circulation of data generated by the program. 

297 
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nest i ng on Hutchinson I sland, Florida in 1971. Fl a . Dept . Na t. Res . 

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(Care tta c. c a retta and Chelonia m. mydas) in the northern 

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of sea t urtles. Ed. by K. A. Bjorndal . Wa s hi ngt on, D. C. : Smithsonian 

Instit ution Press 1982 

Henwood , T.A . : Loss es of monel flipper t ags fr om loggerhead sea turtles, 

Carett a carett a . J. Herpe t ol. 20, 27 6-2 79 (1986) 

Hillestad, H.O., J .I. Ri chards on , C. McVea, Jr., and J.~ . Watson, Jr.: 

Worldwide incidental capture of sea t urt les, pp . 489- 496. In: Biology 

and conservation of sea turtles. Ed. by K. A. Bj o rnda l . washington, 

D.C .: Smithson ian Institution Press 1982 

Huyhes , G.R. : Ne sti ng cycles in sea turtles - t yp i ca l o r a typical, pp. 

81-90. I n : Biology and conservat ion of sea tu r tl e s. Ed. by K.A. 

Bjorndal .--Washington, D.C. : Smi ths onian I nsti tut io n Pre ss 1982 

LimpusA C.J.,. nd P. C. ee~: The green turtl e Ch e l onia my ~as in Queensland: 

prellfnl na ry descnpt l on of the po pulatlon struc ure i n frogs and 

reptiles. Ed. by G. Grigg, R. Shi ne and H. Ehman . Chipping Norton, 

NSW. Surrey Pe a t ty and Sons 1985 

Mendonca, M.T.: Moveme nts and fe ed i ng ecology of imma t ur e green turtles 

(Chelonia myda s) in a Florida lagoon. Cope ia 1983, 1013-1023 (1983) 

Mendonca, M.T., and L.M. Ehrhart: Ac ti vi t y , popu la tion s iz e and structure 

of the i mma tu re Che 1 oni a mydas and Ca rett a ca r etta in Mosquito 

Lag oon, Flo rida. Copeia 1982, 161-167 (1982) 

Meylan, A.: Sea t ur tl e mi gration - ev idence fr om tag re t urns, pp. 91-100. 

In: Biology and c onservati on of sea t ur t les. Ed . by K.A. Bjorndal. 

Washington, D.C. Smithsoni an Institution Press 1982 

299 
Mey1an, A.B., K.A. Bjornda1 and B.J. Turner: Sea turtle nesting at 

r~e1bourne Beach, Florida, II. Post-nestiny movements of Ca.!etta 

caretta. Bio1. Conserv. 26, 79-90 (1983) 

Mortimer, J.A.: Feeding ecology of sea turtles , pp. 103-110. 

and conservation of sea turtles. Ed. by K.A. Bjordal. 

D.C. Smithsonian Institution Press 1982 

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Washinyt on, 

Mrosovsky, N.: Thermal biology of sea turtles. Amer. Zool. 20, 531-547 

(1980) 

Mrosovsky, N.: Conserving sea turtles, 176 pp., London: 13ritis h 

Herpetological Society (1983) 

Ogren, L., and C. McVea, Jr.: Apparent hibernation by sea turtles in North 

American waters, pp. 127-132. In: Biology and conservation of sea 

turtles. Ed. by K.A. Bjornda~ Washington, D.C. Smithsonian 

Institution Press 1982 

O'Hara, J.: Thermal influences on the sw imming speed of loggerhead turtl e 

hatchlings. Copeia 1980, 773-780 (1980) 

Owens, D.W., and G.J. Ruiz: New methods of obtaining blood and cerebrospinal fluid from marine turtles. Herpeto10gica 36, 17-20 (1980) 

Owens, D.W., J.R. Hendrickson, V. Lance and I.P. Callard: A technique for 

determining sex of immature Chelonia mydas using a radioimmunoassay. 

Herpetologica 34, 270-273 (1978) 

Pritchard, P.C.H., P.R. Bacon, F.H. Berry, A.F. Carr, J. Fletemeyer, R.M. 

Gallagher, S.R. Hopkins, R.R. Lankford, R. Jvlarques M., L.H. Ogren, 

W.G. Pringle Jr., H.A. Reichart and R. Witham: Manual of sea turtle 

research and conservation techniques, Second Edition. K.A. Bjorndal and G.H. Balazs (Eds.) (1983) 

Proffitt, C.E., R.E. Martin, R.G. Ernest, B.J. Graunke, S.E. LeCroy, K.A. 

Muldoon, B.D. Peery, J.R. Wilcox and N. Williams-Walls: Effects of 

power plant construction and operation on the nestiny of the 

loggerhead sea turtle (Caretta caretta): 1971-84. Copeia 1986, 

813-816 (1986) - - -

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( 1984) 

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J. Fla. Acad. Sci. 30,287-294 (1968) 

300 
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Meddelelser Fra Kommissionen for Havundersogelser, Seri Fiskeri 5, 

1-26 (1916) 

Wibbels, T., D. Owens, Y. Morris and M. Amoss: Sex ratios of immature 

loggerhead sea turtles captured along the Atlantic coast of the 

United States, 4 7 pp. Texas A&M University, College Station: Final 

Report to the National Marine Fisheries Service. Contract No. 

NA-81-GA-C-0039 1984 

Williams-Walls, N., J. O'Hara, R.M. Gallagher, D.F. Worth, B.D. Peery and 

J.R. Wilcox: Spatial and temporal trends of sea turtle nesting on 

Hutchinson Isl a nd, Florida, 1971-1979. Bull. Mar. Sci. 33, 55-66 

(1983) 

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Florida, in 1973. Fla. Mar. Res. Pub1. 18, 1-17 (1976) 

301 
IMPINGEMENT CHANGES AFTER THE 

INSTALLATION OF A FIXED-SCREEN FISH 

DIVERSION STRUCTURE 

Chris Benedict 

Carolina Power & Light Company 

Brunswick Biology Laboratory 

P.O. Box 10429 

Southport, NC 28461 

ABSTRACT 

Studies conducted at Carolina Power & Light Company's Brunswick 

Steam Electric Plant in southeastern North Carolina from 1977 through 

1982 showed impingement of organisms. In an effort to reduce 

impingement, a fixed-screen fish diversion structure was installed i n 

1983. The fish diversion structure reduced total impingement over 40% by 

number and 70% by weight, and the dominant species impinged changed from 

Atlantic menhaden (Brevoortia tyrannus) to bay anchovy (Anchoa 

mitchi 11 i) . 

302 
INTRODUCTION 

Power generating facilities use large quantities of water in the 

product ion of electricity which may result in the impingement of aquatic 

organisms as the intake water is filtered through trave ling screens. Many 

investigators have reported impingement study results and the effects on 

the aquatic community (Uziel and Hannon, 1979). Various types of barrier 

and diversion methods have been utilized to exclude organi sms from plant 

cooling systems. Behavioral barriers using electrical fields, sound, 

light, water jets, or air bubbles have been tested as fish diversion systems (Ray et al., 1976). These barrier systems are successful only in 

low-flow cond itions because in each case the organism must be able to 

detect and act ivel y swim away from the barri er. Various physical diversion structures--such as traveling screens, drum screens, perforated 

dikes, and fixed screens--filter the organisms from the intake water (Darn 

and Johnson , 1981; Mussalli, 1984). The size and configuration of the 

openings in a diversion affect the number and the size of organisms impinged. The success of a diversion structure depends on the design, configuration, water velocity, water volume, and affected species. Each 

diversion structure design needs to be individually examined for the 

effectiveness of diverting organisms from impingement (McGroddy et al., 

1985) • 

The Brunswick Steam Electric Plant (BSEP) is a two-u nit nuclear power 

station located on the Cape Fear River estuary in southeastern North Carolina. The plant is situated at the end of a 4.9-km intake canal and draws 

water from the Cape Fear River ship channel (Figure 1). Normal intake 

flows for summer (> 18.3"C water temperature) and wi nter « 18.3°C) operation are 51.8 and 34.3 m3/sec, respectively . Flows as high as 65 m3/sec 

have been reported during some periods of prediversion sampl ing, while 

20 m3/sec was recorded during the lowest prediversion flow condition. 

These differences are due to variable plant operation. 

During the late 1970s, large numbers of Atlantic menhaden (Brevoortia 

tyrannus) entered the intake canal and occasionally cau sed plant operation 

problems by obstructing the water fl ow through the traveli ng screens. 

303 
--_. _- - - --- -- ---

NORTH 

~­

~-

CAROLINA 

\( 

" 

{

WEIR 

RETURN 

BASIN 

FISH RETURN FLUME 

SCALE 

1000m 

ATlANTIC OCEAN SCALE I -- ----- -1 IOOO m 

N 

Figure 1. Location of the Brunswick Steam Electric Plant (BSEP) intake ,*,81 and divenion structure. 

304 
A test diversion structure made of framed hardware cloth and wooden pilings had been successful in reducing Atlantic menhaden catches during 1979 

(Hogarth and Nichols, 1981). As a result of this study, a permanent 

fixed-screen fish diversion system became fully operational in January 1983. The concrete and metal diversion structure, located 3.5-km from 

the plant, consists of 134 screen panels 1.2 x 3.0 m in size. The divers;on screens are 90% copper and 10% nickel expanded metal mesh having 

9.4-rrm openings. The diversion structure ;s IIV II shaped which increases 

the screen surface area, decreases the through-screen velocity, and allows 

for some tidal flushing of debris (Figure 2). 

The purpose of this paper is to describe the changes in impingement 

as a result of the installation of the fixed-screen fish diversion structure. 

305 
... .... 

" TO BSEP 

" ,'" 

.;. .... ..... , -~ .. -" . ..... 

.:. .... - ... 

Figure 2. 

TO CAPE FEAR RIVER - -----! .. ~ 

Overhead view of diversion structure and inset of copper-nickel screen panels. 

306 
MATERIALS AND METHODS 

Impingement studies have been conducted at the BSEP since 1974. 

Beginning in 1977 samples were collected during full two-unit operation. 

A holding pen or coll ection basket with a 9.4-mm mesh opening was used to 

collect the sample. Organisms were iden tif i~d to the lowest practical 

taxon (usually species); then length and weight were recorded. Historically, fish greater than 40-mm standard length and blue crabs with carapace widths greater than 25 mm were impinged on the 9.4- mm circulation 

screens. After the 1983 installati on of 1-mm fine-mesh screening on four 

of the eight circulation screens, the cutoff l engths were imposed to separately analyze larval « 41 mm) and juvenil e/adult (> 40 mm) impingement. All impinged organisms were collected for one 24-hour period each 

week. Monthly and annual impingement estimates were computed from the 

24-hour samples (CP&L 1985, 1986). The data are presented as number and 

weight of organisms per million cubic meters of plant cooling water 

entrained. 

For reporting purposes, 1977, 1978, 1980, 1981, and 1982 will be 

discussed as prediversion data, while 1984 and 1985 will represent the 

postdiversion data. A temporary prototype diversion structure was installed in 1979 to test the feasibility of reducing impingement by diverting 

organisms away from the intake canal; thus 1979 data was not used. Furthermore, the 1983 data were not used because modifications to the BSEP 

intake structure prevented impingement sampling f or half the year. 

307 
RESULTS 

The installation of a fixed-screen fish diver'sion struct ure in the 

BSEP intake canal changed the number and weight of organisms and the rankings of species impinged. Five species represented over 80% of the total 

catch in six of the seven years which were examined (Table 1). In the 

other year (1982), gizzard shad (Dorosoma cepedianum) were abundant. This 

anomalous year was perhaps due to high freshwater river flow which transported freshwater species such as gizzard shad into the lower estuary. 

Atlantic menhaden (Brevoortia tyrannus) was the most abundant species 

impinged for all prediversion years with an annual mean catch of 5481 fish 

per million cubic meters of water entrained. After the installation of 

the diversion structure. the Atlantic menhaden catch was reduced 93% in 

number and 91% in weight (Table 2). 

Other species also showed a substantial decrease in impingement after 

the installation of the diversion structure. Impingement of spot (Leiostomus xanthurus) was reduced by 72% in number and 73.0% in we i ght from 

prediversion catches. The Atlantic croaker (Micropogonias undulatus) 

impingement was reduced 36% in number and 30% in weight over predivers;on 

catches, and blue crab (Callinectes spp.) impingement was reduced 29% in 

number and 20% in weight (Table 2). 

308 
Table 1. A comparison of rankings of the five dominant species impinged 

by number at the Brunswick Steam Electric Plant before and after 

the installation of the fish diversion structure. 

Prediversion Postd;vers;on 

Species 1977 1978 1980 1981 1982 1984 1985 

Brevoortia tyrannus 1 1 1 1 1 2 7 

Anchoa mitchilli 2 2 2 2 3 1 1 

Leiostomus xanthurus 3 4 4 3 6 8 5 

Micropogonias undulatus 5 9 5 15 5 6 3 

Callinectes spp. 4 3 3 4 4 3 2 

Total catch 85% 81% 81% 85% 66% 81% 90% 

309 
W 

I-' 

o 

Tabl e 2. Tot al num ber and we ight (kg) of t he f i ve most abund ant species imp i nged per mil l i on cu bic meters 

of coo l i ng wat er entra i ned at the BSEP duri ng pred iversion and postdiversion peri ods includi ng the 

percent change between per iods. 

Prediversion Postdiversion 

Spe cies 1977 1978 1980 1981 1982 Mean _1984 1985 ___ ~ean Change 

Brevoortia t yrannus 

Number 

Weight (kg) 

.-\nchoa mitchilli 

Number 

Weight (kg) 

Leiostomus xanthurus 

Number 

Weight (kg) 

Micropogonias undulatus 

Number 

Weight (kg) 

Callinectes spp. 

Number 

Weight (kg) 

Total catch 

Number 

Weight (kg) 

5,636 6,003 3,235 3,285 9,244 5,481 

39.1 41.1 34.8 31.4 47.4 38.8 

2,371 1,336 1,944 2,406 

3.6 2.5 2.5 2.6 

533 

5.0 

266 

2.5 

271 

3.6 

313 

3.9 

163 

0.7 

536 

7.6 

233 

2.7 

224 

0.6 

342 

3.6 

474 

5.5 

40 

0.5 

162 

3.1 

883 1,788 

1.1 2.5 

255 

1.6 

300 

0.8 

443 

4.8 

362 

3. 7 

199 

1. 0 

351 

4.5 

10,697 10,371 7,368 7,494 16,761 10 , 538 

64.6 72.4 51.1 50.4 64.7 60. 6 

726 

5.8 

64 

0.9 

395 - 92.8% 

3.4 - 91. 3% 

3,356 5,166 4,261 + 138.3% 

2.2 5.1 3.7 + 48.0% 

99 

0.6 

122 

0.5 

318 

4.7 

107 

1.3 

130 

0.8 

183 

2.4 

103 - 71.5% 

1.0 - 73.0% 

127 - 36.2% 

0.7 - 30.0% 

251 - 28.5% 

3.6 - 20.0% 

5,693 6, 248 5, 97 1 - 43 .3% 

18.7 15. 8 17.3 - 71.5% 
Bay anchovy (Anchoa mitchilli) , which had been second in abundance 

during most of the prediverison years, became the dominant species in 

postdiversion years (Table 1). This increase in rank was not only a 

resu 1t of the decrease in the At 1 ant i c menhaden catch but also a 138.3% 

increase in number and 48.0% increase in weight of bay anchovy over prediversion catches (Table 2). 

The prediversion annual mean catch of 10,538 organisms with a weight 

of 60.6 kg per million cubic meters of cooling water was reduced to 5,971 

organisms 17.3 kg per million cubic meters of cooling water. Total 

impingement was reduced 43% in number and 72% in weight in the postdiversion structure years. 

311 
DISCUSSION AND CONCLUSIONS 

Impingement during the prediversion years. on occasion. threatened 

plant operation. Large schools of Atlantic menhaden entered the intake 

canal during winter months and substantially increased impingement. Other 

species--including bay anchovy. spot. Atlantic croaker. and blue crab--

also contributed to impingement. The necessity for a fish diversion 

system at the BSEP was evident after several years of impingement sampling. 

Fine-mesh screens (l-mm) were installed on four of the eight t raveling screens at the BSEP prior to the postdiversion impingement stud ies. 

The smaller mesh size resulted in the impingement of those bay anchovies 

which previously could have gone through the screens. Additionally, the 

diversion structure did not exclude bay anchovy from the intake canal as 

it did larger organisms. Consequently. bay anchovy catches increased 138% 

during postdiversion years. while total impingement was reduced 43%. The 

f ine-mesh screens impinged bay anchovies in postdiversion years. thus 

reducing the apparent effectiveness of the diversion structure on the 

number of organisms impingement. Total impingement was. however. reduced 

72% by weight. which is a better measure of diversion structure effectiveness because the larger organisms were excluded from the impingement catch 

by the diversion structure. 

Postdiversion impingement was reduced but not eliminated. Postlarval 

organisms were entrained through the diversion screens and probably utilized the intake canal as a nursery area. As the individuals grew and 

moved throughout the cana 1. they were suscept i b 1 e to imp i ngement. Occasionally the diversion screen panels would fai 1 due to debris buildup 

caused by storms, lunar tides, or mechanical problems with the maintenance 

system. During these unusual occurrences, juvenile and adult organisms 

may have entered the intake canal and subsequently impinged. 

The fixed-screen fish diversion 

Atl antic menhaden impingement. Spot, 

impingement also showed reductions in 

structure substantially reduced 

At 1 ant i c croaker, and blue crab 

both number and weight. These 

SU bstantial reductions in impingement and a reduced threat to plant operations illustrate the success of the BSEP fixed-screen fish diversion 

struc t ure. 

312 
ACKNOWLEDGMENTS 

Appreciation is expressed to the employees of Carolina Power & Light 

Company's Brunswick Biology Laboratory who spent long hours collecting the 

data for the imp; ngement study. Wende Pearston typed the manuscr; pt, 

Kerry MacPherson prov i ded rev; ew, Sandra Pr; ce prepared the map and f; gures, and the members at the Data Management Unit provided computer support. 

313 
LITERATURE CITED 

CP&L. Brunswick Steam Electric Plant, Cape Fear Studies interpretive 

report. 86 pp. New Hill, North Carolina: Carolina Power & Light 

Company 1985 

CP&L. Brunswick Steam Electric Plant 1985 biological monitoring program. 88 pp. New Hi 11, North Carol ina: Carol ina Power & Light 

Company 1986 

Dorn, P. B., and J. T. Johnson. Advanced intake technology for power 

plant cooling water systems. Proceedings of the workshop of advanced 

intake technology. 307 pp. San Diego, California: Available from 

NTIS, Springfield, Virginia 1981 

Hogarth, W. T., and K. L. Nichols. Brunswick Steam Electric Plant intake 

modification to reduce entrainment and impingement losses. In: 

Proceedings of the workshop of advanced intake technology for power 

plant cool i ng water systems, pp. 272-282. Ed. by P. B. Dorn and 

J. T. Johnson. San Diego, California: Available from NTIS, Springfield, Virginia 1981 

McGroddy, P. M., T. E. Pease, J. A. Matousek, and R. B. Edson. Intake 

research facilities manual. 189 pp. Palo Alto, California: Electric Power Research Institute 1985 

Mussal1i, Y. G. Advanced intake technologies study. 276 pp. Palo Alto, 

California: Electric Power Research Institute 1984 

Ray, S. S., R. L. Snipes, and D. A. Tomljanovich. The state-of-the-art 

report on intake technologies. 83 pp. Chattanooga, Tennessee: Tennessee Valley Authority 1976 

Uzi el , M. S., and E. H. Hannon. Impingement: An annotated bib1iogr aphy. 193 pp. Palo Alto, California: Electric Power Research 

Inst itute 1979 

314 
FINE MESH SCREENS: 

A NEW APPROACH TO PREV ENTING ENTRA INMENT 

D. Br uzek 

K. Mahadevan 

Mote Mari ne Laboratory 

1600 City Island Park 

Sarasota, Flori da 34236 

V. Brueggemeyer 

E. Taft 

Tampa Electri c Company 

P.O . Box 111 

Tampa , FL 33601 

ABSTRACT 

In order to min imize losses of aquatic organisms at Tampa Electric 

Company's Big Bend Station , a novel fin e-mesh screening system was 

installed at ex isting Unit 3 and new Unit 4. Si x continuously traveling 

water screens, incorporating 0. 5-mm screen mesh and spec i ally designed 

organism troughs and spray washes, screen the entire flow of 1,080 cfs. 

Organi sms washed from the screens pass vi a a common trough to a sump, 

from which they are pumped to a remote return location. 

The des i gn of the fac i 1 ity is based on the results of prototype 

screen testing at Big BEnd St ation i n 1980 and 1981. In these studies a 

full-scale, prototype sc reen was evaluated over many months to determine 

the survival of selected Representative Important Species, including the 

early life stages of various fish and invertebrates, and to optimize the 

design of several key screen components. These studies indicated high 

survival of abundant fish eggs and invertebrates . On the basis of these 

results, the two- unit, fine-mesh screen design was approved by U.S. 

E.P.A. and was constructed . 

In 1985 studies were conducted to evaluate survival of organisms 

recovered from the ful l-scale system. Results indicate that survival of 

fish eggs and larvae, to a great extent , exceeds estimates obtained from 

the prototype. Inve rtebrates suffer sl ightly higher than predicted 

mortality in the full -sc ale system, although survival is high. 

This paper will present a description of the Unit 3 and 4 finemesh screen facil ity, will present res ults of prototype and full-scale 

studies, and will offer explanations for differences in observed survival 

rates between the prototype and ful l -scale installations. 

315 
INTRODUCTION 

In 1985 Tampa Electri c Company (TEC) placed in commercial 

operation a fourth generat ing unit (Big Bend Unit 4) at the Big Bend 

Station . The site is located on the eastern shore of Tamp a Bay in No rth 

Ruskin, Florida. Region IV of t he U. S. Env i ronmental Protect ion Agency 

(EPA) expressed concern prior to con structi on of t he unit over losses of 

organisms due to entrainment into the cooling wa ter system. Accord ingly , 

early in 1979 TEC conducted a prototype evaluation of a f ine mesh 

screening system which could be util i zed to prot ect small organisms at 

this site as part of the 316 Demonst ration. Th e prot otype studies we r e 

performed by Stone & Webster Engi neeri ng Corporat i on and Mote Mari ne 

Laboratory. 

Prel iminary studies in 1979 indicated that the concept of fine 

screening at Big Bend Station warranted further investigations in 1980. 

The ensure the validity of data to be obtained, it was decided that the 

1980 test facility would be a full -scale , prototype traveling screen 

including all features of an in-service installation. Design efforts 

began in late summer with model studies which were conducted to optimize 

the screen's hydraulic characteristics and organism collection system. 

Construct i on of the prototype screen system was completed in time to 

initiate biol ogical testing at the beginning of the entrainment season in 

March. 

Biological investigations were conducted from March through August 

1980. The study was conducted in three phases: Phase I (March) 

consisted of a shakedown period; Phase 2 (April 1 to May 16) involved 

daily sampl ing (5-day week) with one series of night samples per week; 

Phase 3 (June through August) consisted of sampling one week per month; 

various supplemental studies were also conducted i n Phase 3. 

316 
During the study program, emphasis was placed on obtaining data 

for the follow i ng Representative Important Speci es (RIS): 

Common Name 

Bay anchovy 

Black drum 

Silver perch 

Spotted seat rout 

Scaled sardine 

Tidewater sil ve rside 

Stone crab 

Pink shrimp 

American oyster 

Blue crab 

Sc i ent ifi c Name 

Anchoa mitchilli 

Pogonias cromis 

Bairdiella chrvsoura 

Cyno scion nebulosus 

Harengula jaguana 

Menidia beryllina 

Men ippe mercenaria 

Penaeus duorarum 

Crassostrea virginica 

Callinectes sapidus 

Based on the positive results obtained from the prototype screen 

system, EPA de t ermined that Unit 4 could be constructed with a oncethrough cool ing system provided that a fine-mesh screening system be 

incorporated into the cooling water intakes of both Units 3 and 4. Unit 

4 went into commercial ope r ation in February 1985, and a biological 

evaluation of the full-scale system was conducted by Mote Marine 

Laboratory in 1985-86. 

This paper presents the results for organism survivability of both 

the prototype and full-scale studies , discusses the similarities and 

differences in these results, and offers suggestions on why speciesspecific survival rates differed in some cases. 

MATERIALS AND METHODS 

Prototype Screen System Design 

The prototype screen was located in the intake canal upstream of 

the existing Units 1 through 3 travel ing screens and pumps (Figure 1) . 

The screen was situated on a test plat form connected to 1 and by an 

existing bri dge. Laboratory facilities were located on the north side of 

the intake canal. Ambien t int ake water was delivered to the laboratory 

via a series of pumps and filters located at the test platform. 

Figure 2 shows a more detailed plan of the scr een operating deck. 

The prototype screen was of the dual -fl ow type and i ncorporated all of 

the features required for fine screening. Seals were incorporated 

317 
t 

N 

TAMPA BAY 

FISH HOOK 

KEY 

WHISKEY STUMP t\. 

KEYU 

PROTOTYPE M M L 

INT AKE. SCREEN 00 ON-SITE 

CANAL -- . I. . . .. = FACILITIES 

. BIG BEND 

: STATION IIIII 

1,2,3&4 

ORGANISM ", 

RETURN 

DISCHARGE · 

o 

, 3000 I 

SCALE - FEET 

Fig. 1. Big Bend Power station site. 

318 
w 

...... 

1.0 

cr' 

COLLECTION e. 

TRANSPORT BOX 

2"DRAIN LINE .,j 

COLLECT ION 

TROUGH 

\ DISCHARGE PIPE 

//\T-,\ --- 1l5Y-J-l-.... _L _ - - - -=----

/ '/" f- _{ 

: t l ,L OC1NT~STER PUMP 

I 

LOW PRESSURE 

SCREENWASH 

I ..... I --- - - - - -I 1fT =h-h _ I I --too-

">7 I -------~ 

TRAVELI NG I 

WATE R SCREEN 

t"l · 4i'" HIGH PRESSUR E 

SPRAYWASH 

SPRAY WASH 

EFFICIENCY 

SAMPLER 

i I 

SCREEN--.. 

F LOW 

o 

04 I SCREEN FLOW 

I i SaHN t£AO SHAFT 

LOW PRESSURE L- COMPRESSOR 

SP RAY WA SH (f OR CONTROLS) 

IN TAK E CANAL 

PIPE BRIDGE 

FIGURE 2 

DECK ARRANGEMENT 

FINE- MESH SCREEN 

TEST FACILITY 
between screen baskets and between the baskets and the side frames to 

minimize the passage of organisms through these areas. The screening 

medium was 0.5 mm square mesh made of woven-monofilament polyester, and 

each of the 48 screen baskets were 0.6 m wide by 0.6 m high. 

The screen was capable of operation at speeds of up to 8.5 m/min. 

On automat ic control the screen was desi gned t o run continuously at 2.1 

m/min; as the head di fferenti al across the screen would reach 10 and then 

15.2 cm, the speed would increase to 4.3 and 8.5 mlmin, respect ively. On 

manua 1 control the screen coul d be operated at speeds between 0 and 8. 5 

m/min. Three speeds of 2. 1, 4.3 and 8.5 mlmi n were selected for 

biological evaluation . These speeds corresponded to maximum impi ngement 

durations of approxi mat ely 7, 4, and 2 minutes, respectively. 

Flow through the screen was supplied by an in-line pump (an 

adapted ship bow thru ster) located unde r the test platform and connected 

directly to the screen via a tran sition section (Figure 3). The pump was 

belt-driven by a 250 -hp motor located on the deck. Assort ed pulleys 

allowed for flow adj ustments. For the purpose of this study , pulleys 

were selected to achieve velocities of 15.2 and 30.5 cm/s . 

The discharge flow from the pump, composed of fine-screened wate r, 

was conveyed by a pipe to a locati on far eno ugh downstream in the intake 

channel to prevent recirculation (Figure 2). At t he point where the pipe 

passed under the bridge, two taps were installed in the pipe to allow for 

the insertion of a flow-measuring device (for verification of pump flow 

rate) and an organism sampler which was used to determine the collection 

efficiency of the fine-mesh screen. A work platform was provided 

directly above this location to allow for the recording of pitometer 

measurements and the collection of biological samples. 

The test screen incorporated shallow lifting buckets on each 0.6-

m wide sc r een basket which retained approximately 2.54 cm of water. A 

low-press ure (10 psi) spray header located on the ascending side of the 

screen acted to remove organisms from the screen mesh surface and lifting 

buckets. A high-pressure (55 psi) spray he ader was located on the 

descending side of the screen to remove any remaini ng debris into a 

separate trough . A screenwash pump with astra i ner was located on the 

ope rat i ng deck and took suction from the f i ltered water (bow thruster 

320 
EL.O'-O" 

TRAVELING 

WATER SCREEN 

....-~ EL , -21' -6" 

-12,-01-

321 

BOW THRUSTER MOTOR 

SCREEN WASH STR'AINER 

SCREEN WASH PUMP 

EL -15'·3" 

II 

II I 

III 

III 0 8 III I I I I I I I I I lLl SCALE-FEET 

FIGURE 3 

PROFILE ARRANGEMENT 

FINE-MESH SCREEN PROTOTYPE 
pump di scharge). As each screen basket passed the spraywash, organ i sms 

on the mesh or in the lifting bucket were gently rinsed into °a collecti on 

trough (Figure 2). Once in the trough, the organisms flowed by gravity 

into a primary collection tank from which they were drained into a 

secondary collection chamber, which also served as the container in which 

the organi sms were transported to the l aboratory . 

As mentioned , a land- based laboratory was available for immed i ate 

processing of all screen sample s. The laboratory facility was designed 

to : 

1. Permit sorting, counti ng, identifi cati on , and determi nation of 

initial mortality of planktonic organ isms. 

2. Hol d sel ected organi sms for up to 96 hours to determi ne 1 at ent 

mortal ity. 

Ambient , filtered intake water was supplied to the laboratory via a 

system of pumps, fi lters, and pi pi ng. A redundant water supply system 

was installed as a backup in the event of a system failure. This water 

served as a water bath for maintaining ambient temperatures in a system 

of closed holding containers. 

Prototype Screen Study Methods 

The pri mary object i ve of the study program was to determi ne the 

survival of organisms following impingement and removal from the 

prototype screen. To achieve this objective, screen samples were 

collected on a rout i ne basis throughout the study program. 

Essentially the same sampling procedures were utilized during all 

phases of the study. As di scussed previ ously, tests were conducted at 

screen trave l speeds of 2.1, 4.3 and 8.5 m/min and approach flow 

velocities of 15.2 and 30.5 cm/s . Therefore , a complete series of tests 

i nvolved screenwash collection at each of the six velocity/screen speed 

comb inations in the following matrix: 

Approach Velocity (cm/s) 

15.2 

30.5 

Screen Travel Speed (m/min) 

2.1 4.3 8.3 

x 

X 

322 

X 

X 

x 

X 
Within a given day the timing of the sampling procedures was such 

that six samples could be collected and processed in the laboratory. 

Since t he process of chang ing pu lleys to achieve different test 

ve 1 oc it i es requ i red several hours, it was not feas i b 1 e to conduct tests 

at both veloc ities within a single day. Therefore, the pu lleys were 

changed at t he end of every second day of testing at a given velocity. 

Within a day, two replicates of a one-velocity/three -screen speed portion 

of the matrix were obtained . 

During Ph ase 1, tests were cond ucted five days per week (up to six 

tests per day) during the daytime hours (approximately between the hours 

of 0900 and 1500). At the beginning of Phase 2, the sampling strategy 

was modified to include night col lect ion. The intent of night sampling 

was to determi ne whether speci es/l i festage occurre nce, abundance and/or 

mortality differed be tween day and night. Under this mode, sampli ng was 

conducted Monday through Thursday during the daytime, and Th ursday night 

between app roximately 1900 and 2400 hrs. During Phase 3, the st rategy 

continued with screen sampling being conducted one week per month (June , 

July, and August). 

Regardless of phase or samp ling st rategy , the same procedures were 

ut i 1 i zed ina 11 tests. Pri or to samp 1 i ng, the bow thruster pump and 

screen (Figure 3) were set at the desired operating point for the 

specific test being conducted. The low-pressure spraywash was preset at 

10 psi and was then shut off until the sample was taken. Once the screen 

was in full operat ion and the movement of water and organisms through the 

test faci 1 ity was in steady-state , sampl i ng wa s initiated by turning on 

the low-pressure spray, allowing the contents of a predete rmined number 

of screen baskets to be rinsed into the collection trough, and then 

shutting off the spray. The number of baskets washed differed for each 

water veloc ity/screen travel speed condition such that under each 

condition, the total volume of water sampled by the prototype screen was 

equ i va 1 ent. 

Organisms washed int o the collection trough were carried into a 

primary collection area (Figure 2) which contained a screened overflow 

(0.25 mm mesh) . In this area, large debris (leaves, shells, ctenophores) 

323 
could be removed as the area drained. Once the water level re ac hed t he 

bottom of the overflow screen, the sample was concentrated to the point 

where it could be drawn down into the secondary collection and tran sport 

chamber where the sample was further concentrated. The drawdown was slow 

and gentle, in order to avoid stress due to high velocit ies and 

turbulence in the drain l ine and containe r . Once t he sampl e had be en 

completely transferred, the container was covered and transported to t he 

land-based laboratory for sorting and l atent effects studies. 

In addition to screenwas h samp l es, control organ isms wer e 

collected and held (as for other t est s) fo r comparison to latent 

morta 1 ity values experi enced among organ isms collected by the screen . 

The control samples were t aken by lowering a standard 1 meter mouth 

diameter, 505 micron mesh net from a walkway bridge over the intake 

canal. Enough line was released to al l ow the net to sink to mid -depth, 

where it was allowed to fish for f ifteen minutes. The continual flow of 

the intake canal was sufficient enough to allow for adequate sampl ing 

from the stationary net. 

collected one day per week, 

collected twice weekly. 

Duri ng Phase 1, control organ isms were 

while in Phases 2 and 3, controls were 

As mentioned, all samples co l lected from the prototype screen and 

control station were t r ansferred to the land-based laboratory where they 

were sorted and held. Once the transport container was delivered to the 

laboratory, the follow i ng procedures were carried out: 

1. The transport container was placed in a water bath and temperature 

was recorded. 

2. When RIS were abundant, the samp l e was gently stirred or agitated 

to obtain a homogeneous distributions of organisms, and a 

volumetr ic subsample was drawn off. 

3. The primary sampl e wa s mainta ined in a water bath and held for 

later processing. 

4. The subsample (in water bath) was sorted immediately into 

species/lifestages, concen t rating on RIS species first. 

5. Up to five individuals of each spec i es/lifestage were placed in a 

separate container for transfer to the holding area; organisms 

were sorted t o the l owest taxonomic level possible without 

delay i ng init i ation of hold ing or adding incremental stress to the 

324 
test organisms; cr ab zoea and megalops were he ld indi vi duall y in 

lots of 48. 

6. A spec ies/l ifestage sample consisted of 30 organ isms (48 crabs) ; 

therefore , once six lots of a species/l ifestage were counted and 

recorded, they were transferred immediately to the holding area 

for the l atent effects study. 

7. Sorting continued until samples of all RIS l ifest ages had been 

placed in holding containers; the location of all organisms was 

carefully documented . 

8. The remainde r of the subsample numbers of live, stunned, and 

(These dat a were used as 

determin at ions.) 

was sorted by spec i es, recordi ng de ad organi sms on data sheets . part of "initial survival" 

9. After sorti ng was completed , the primary sample was preserved for 

later an alysis, if needed. 

10. When organism densities were l ow, several add iti onal subsamples 

were t aken in order to obta in 30 live organi sms of available RIS 

for hol di ng. In this case, only the first subsample was 

completel y sort ed for live, stunned, and dead organisms; the 

remaining subsampl es were drawn only to bri ng the total of each 

RIS lifestage to 30 (48 crabs), if possibl e. All organisms now in 

the hold i ng facility were checked at 3, 6, 12 , 18, 24, 36, 48, 60, 

72, 84, and 96 hr; the number live and de ad at each check was 

recorded , as well as any abnormal occurrences (e .g. , missing 

organisms) . 

11. All organisms which died during the holding period were preserved 

in labeled vial s fo r final identificati on at a lat er date. 

12. At the comp letion of the holdi ng period, the fi nal number of live 

and dead organi sms was recorded and each group was preserved in a 

labeled vi al. 

13. Water qua lity parameters were recorded frequently during all 

holding experiments ; parameters recorded i ncluded sal inity, 

temperatu r e, dissoived oxygen, pH , and ammonia. 

14. At the end of each latent-effects test, all vials wer e rechec ked 

and all organisms were identified (to spec i es, if possible), 

categorized to l ifestage and coun ted. 

These procedures were ve ry effective in permitting an accurate accounting 

of most organisms from collection t hrough fi nal identification. 

325 
W 

N 

0'\ 

Screen Platform 

3" 38 t-Pa: 

Roller Gate 

By-Pass 

Roller Gate 

Intake Canal 

3C ~B 4A 

Accumula ton 

By-Pus 

Roller Ga tI 

High Pres.ure Screenwuh P~ 

DOD ~~ow Pressure 

Screenwash Pump s 

Unit 3 

Coarse Mea 

Screens ~l£eur. S~reenw ash 

Strainer 

Baskets 

0) 

Low Pr ... ure Scrllnwaah 

Stra iner 

Baskets 

By-Pass 

Roller Ga te 

I I ~ Unit 4 " ::>' Coase Mesh 

Screens 

Unit 4 

Circulating 

Water Pumpa 

4 

~ 

Coarae Screen 

Catch Basket 

Figure 4 

Debris Basket 

Organilm 

Return 

Sump 

Full-Scale Fine Mesh Screen 

Deck Arrangement 
Full-Scale System Design 

The i nt ake design was developed on the basis of ap ply i ng finemesh screens to exi sting Unit 3 and proposed Unit 4. Sheet piling 

encloses the pump screenwell area, creating a fo rebay between the finemesh screens and the pumps. A layout of the new screening structure is 

shown in Figure 4. 

Each of t he six (three for each unit) dual-fl ow fine-mesh screens 

were fitted i n the sheetpile wall, and t he intake flow passes through the 

screens and di scharge s into the forebay. The discharge openi ng was sized 

to achieve a uniform flow distribution through the two parallel screen 

faces. To ens ur e proper hyd r aulic conditions at t he four circulating 

water pumps and a relatively uniform flow t hro ugh each of the six 

screens, the forebay extends from the seawall about 18.3 minto the 

intake channel . The pumps were positioned t o aid proper flow 

distribution so that each set of two circul ating pump s dr aws from three 

screens. 

Stop gat es cl ose the discharge opening in t he event that a screen 

must be stopped or removed for ma intenance. I n case of emergency 

conditions, roll er gates were inst alled in t he sheetpil e wall between 

screens and open t o su pp ly water to the pump s if the pressure head 

differential across the screens exceeds 0.46 m. To screen the flow and 

protect the pump s and condenser under this emergency oper at ing mode, the 

existing coars e-mesh 9.5 mm screens were maintained on Unit 3, and new 

similar coarse -mes h screens were installed on Unit 4. 

The dual -flow screen design with 9.5 mm mesh has been used 

successfully at Big Bend Units 1 t hrough 3 for many years and, based on 

testing to date , has the necessary featu res fo r protecting small 

organisms when fitted with fine screens. The numb er and size of the 

screens were de t ermined on t he basis of achieving a screen face velocity 

(approach veloci ty ) of 15.2 cm/s at water level E1 0.0 MLW. Based on the 

15.2 cm/s veloc ity criteri on, six 3.05 m wi de scree ns were installed . 

Each screen is submerged to El -8.5 m. Each of the 53 screen baskets is 

equipped wi th easily replaceable 0.5 mm mesh panels and fish collection 

buckets. The f i ne- me sh requires continuous screen operation to prevent 

clogging and to l imi t the time that organisms are impinged. 

327 
Each fine-mesh screen is capable of operating continuously at 

speeds of up to 8.5 m/min. On automated control the screen runs 

continuously at vari able speed. As the head differential across the 

screen reaches 10 cm and then 15 cm , the speed automatically increases to 

4.3 and 8.5 m/min , respectively . 

In addition , each screen is equipped wi t h both a low pressure 

(approximately 5- 10 psi) organism spray wash header on the ascending side 

and a high pressure (40 to 60 psi) spray wa sh header for debri s remov al 

on the descending side of the screen. Separate pumps supply water t o 

each header and take suction from the fine-sc reened water downstre am of 

the Circulating water pumps. The se no zzl es have 12.7 mm diameter 

orifices and are evenly spaced at 0.3 m intervals over the 3.05 m heade r 

length to ensure uniform spray pattern across the screen baskets. 

Although the l ow and high pressure sprays wash organisms and 

debris into separate troughs , all troughs manifold into a common 

sluiceway that carries organisms and debris to a release point in the 

northern Apollo Beach embayment (Figure 1). This maximizes the 

opportunity for survival of any organisms not removed by the low pressure 

spray but subsequently removed by the debris spray. 

The organism return trough was sized to achieve a transport 

velocity in the range of 37 to 255 m/min at a water depth of from 15 to 

30 cm. Total length of the return flume is 630 m. 

The Unit 3 operating deck from which the dual-flow fine -mesh 

screens hang was expanded to accommodate the six screens. As with Units 

1 and 2 structure, the expanded operating deck is supported on piles at 

El +3.54 m. The channel bottom would be maintained in the screen 

structure area at the existing depth of E1 -9.65 m. 

The cost required to add a fine-mesh screen system to Units 3 and 

4 was $9 .9 mi l l ion . 

Full-Scale System Study Methods 

Met hods used du ring this study were essentially similar to those 

used du r i ng the Fine Mesh Screen Protot ype study conducted in 1980. 

An on-site faci l ity was establ ished at t he Big Bend station for 

t he fi ne me sh screen survivability studies. This facility consisted of a 

328 
test trailer with a flow- t hrough seawater system, an ad jacent office 

trailer, and a sample wash and stor age trai l er. The on-si te facility was 

located along the intake canal near t he fi ne mesh screens . All live 

meroplankton sorting and holding of organisms for 48 ho urs was conducted 

at this faci lity . 

The test fa cility trailer was the same one used for the prototype 

study and was equipped with a flow-through seawater syst em consisting of 

two 1/2 hp pumps that pump intake canal water through four sand filters 

up to a 1130 1 head tank. The f iltered seawa ter would t hen gravity feed 

from the head tank through the hol ding facility. 

The surv ival studi es were designed to concentrat e on the same 

target spec i es which were found in high abundance in the 1980 studies. 

In addition, eggs and larvae of other fish species wh ich appeared in 

large numbers along with any juveniles that were collected were held in 

latent mortal ity experiments. Bec ause of the difficulty of 

distinguishing l arv ae of Menippe and Uooqebia duri ng l i ve sorting, zoea 

and larvae of a number of crustacean species were held in latent 

mortal ity tests. 

These studies commenced the first we ek of Ma rch 1985 . Field 

studies were conducted each we ek from March 5, 1985 until October 1, 

1985, for a total of 31 weeks of sampling. Two collect ions per day and 

two per night were taken one day per week at the screenwash and organism 

return discharge stations. One collection per day and one per night were 

taken at the control station one day each week. 

The low and high pressure screenwash of the fi ne mesh screens 

empties into a common trough which flows to a sump at t he beginning of 

the organism re turn canal. The screenwash st ation was sampled by 

suspending a 1 me ter mout h diameter, 505 micron mesh net in front of the 

trough where it empt; es into the sump bas in. A bucke t attached to the 

cod end of the ne t held it open, reducing damage t o t he organisms as a 

result of fri ct i on aga i nst the net. The net was fi shed for three 

minutes, and all organisms retained were carefully ri nsed down into the 

bucket. The sample was then immediately returned to t he test trailer for 

sorting. 

329 
The organi sm return di scharge (ORO) pi pes exi t at the end of a 

wa 1 kway wh i ch extends in the Apollo Beach northern embayment. The ORO 

station was sampled using a specially constr ucted 505 micron mesh ne t 

supported by a f1 oat i ng rectangul ar frame (1 m x 1. 6 m). The net was 

positioned under the flow from the discharge pipe, and organi sms r etained 

were carefull y ri nsed down to a bucket attached to the cod end of the 

net. The net was fi shed for three mi nutes, and the sample was then 

immediately returned to the test trailer for so rting. 

The control sample was taken by lowering a standard 1 meter mo ut h 

diameter, 505 micron mesh net from a walkway bridge over the i ntake 

canal. Enough line was released to al low t he net t o sink to mid-dept h, 

where it was allowed to fish for 15 minu t es . The continual flow of t he 

intake canal was sufficient enough to allow for adequate sampling from 

the stationary net. Organisms retained by the net were carefully rinsed 

to the cod end of the net, and the con t ents were then carefully poured 

into a bucket of ambi ent intake water. The sample was then immedi ate ly 

returned to the test trailer for sorting. 

After the samples we r e ret urned to the test trailer, the 

procedures used to assess initial sur vivability and latent survivorship 

were i dent i ca 1 to those out 1 i ned in the prototype study methods. The 

only differences were that stunned organisms were not considered in the 

full-scale study, and holding for latent survivorship studies was done 

for only 48 hours, with checks done at 6, 12, 24, 36 and 48 hours. 

Ident ifi cat ions were made at Mote Mari ne Laboratory through the use of 

standard 1 iterature sources and MML' s reference collect i on. A voucher 

reference collection of taxonomically confirmed species was maintained. 

RESULTS 

The results of the prototype screen study are given in Tables 1 

through 4 as the percent initial and latent survival of the fish and 

i nvertebrate 1 i festages wh i ch were co 11 ected from the prototype screen 

over t he du r ation of the study. In order to conduct t he data analysis, 

it was necessary to combine identified taxa into groups since, in most 

cases, a si ngle species, genus, or even family did not occur frequently 

330 
TABLE 1 

FISH EGGS 

PERCENT SURVIVAL AND HATCHABILITY 

Initial Survival Hatchabilit~ 48-HR Survival 96-HR Surviva l 

Test Control Test Control Test Control Test Control 

Sciaenidae 75.3 98.4 94.8 99.0 84.3 91.3 69.7 82.7 

Bairdiella . 

chrysura 100 100 100 100 99.1 99.4 97. 9 97 .8 

Cynoscion spp. 100 100 100 100 99.4 99.3 89.4 96.9 

Henticirrhus spp. 100 100 100 100 99.7 100 88.4 91.5 

Pogonias cromis 100 100 82. 2 85.3 

w 

w 

~ Clupeiformes 43 . 2 85 .5 81.0 89.3 84.4 90.3 62.4 68. 6 

Harengula jaguana 45.8 99 .6 92.9 98.5 82.8 92.2 45.9 27 .6 

Anchoa mitchilli 43.3 85.0 80.0 88.6 83.9 90.0 63.7 72.0 

Note: Dashes indicate no observations 
w 

W 

N 

TABLE 2 

FISH LARVAE 

PERCENT INITIAL AND LATENT SURVIVAL 

Initial Survival 4S-HR Survival 

Test Control Test 

Sciaenidae lS.6 (l08) 44.4 (6) 10.9 (26) 

Bairdiella 

chrysun 19.2 (39) 50.0 (2) 

Cynoscion spp . 15.7 (51) o (1) 100 (3) 

Henticirrhus spp . o (15) 25.0 (4) 

Pogonias crollis 42.9 (7) 100 (1) 

Clupeiformes 1.5 (27S) 10.4 (11) 36.4 (11) 

Harengula jaguana o (15) 

Anchoa mitchilli 1.5 (274) 11.4 (10) 22.2 (9) 

Note s: Number of observations is given in parent heses 

Dashes indicate no observations 

Control 

o (1) 

0(1) 

0 (1) 

96-HR Survival 

Test Control 

10 .1 (26) o (1) 

100 (3) 

36.4(11) o (1) 

22.2(9) o (1) 
TABLE 3 

DECAPOD ZOEA 

PERCENT INITIAL AND LATENT SURVIVAL 

Initial Survival 48-HR Survival 96-HR Survival 

Test Control Test Control Test Control 

Caridea 94.3 76.7 85.0 86.8 50.0 43.8 

!:!E£&ebia affinis 91.3 75.6 84.1 76.2 42.8 45.4 

Brachyura 95.5 65.0 83.9 55.6 45.9 27.8 

Grapsizoea 100 100 95.1 97.9 80.2 92.9 

Pinnotheridae 100 100 92.2 93.4 73.0 72.1 

w 

w 

w Xanthidae 99.1 95.9 95.6 74.9 73.4 

Henippe mercenaria 97.9 97.3 91.5 94.9 58.3 61.0 

Paguridae 94.7 100 96.6 100 79.2 33.3 

Note: Dashes indicate no observations 
TABLE 4 

DECAPOD MEGALOPS 

PERCENT INITIAL AND LATENT SURVIVAL 

Init i a 1 Survi va 1 4B-HR Survi val 96-HR Survival 

Test Control Test Control Test Control 

Caridea 100 100 100 

Upogebia affinis 100 100 97.7 100 74 . 3 100 

Brachyura 65.1 26.7 71.B 15 . 0 

Grapsizoea 100 100 9B.1 100 93 .1 91.2 

Pinnotheridae 100 100 92. 9 w 

w 

~ Xanthidae 100 100 9B.3 100 94 . 2 96 . 9 

Henippe mercenaria 100 100 100 

Pa&uridae 100 90 . 0 BO .O 

Note: Dashes indicate no observations 
enough to pe rmit a meani ngful an alysi s. The taxonomic l evel of each 

group was determi ned as t he l owest l evel which would all ow inclusion of 

all important taxa. 

The test data indicate that the invertebrates had the highest 

survival, most often in excess of 90 percent; fragile f ish larvae, such 

as the bay anchovy (Anchoa mitch;lli ), had low survivorship, as 

anticipated for larvae . However, it should be noted that survival among 

control larvae was also low. Further, as shown on Table 2, the small 

number of obse rvations fo r some t axa limits the conclusions which might 

be drawn from these data. 

The latent survivorship of those organisms whi ch were initially 

alive followin g collect ion was studied in the laboratory holding 

experiments . The proportion of organisms \>ihich were ali ve at 48 hr and 

96 hr was used as an index of latent survival. Bo th measures provide an 

indication of the success of the device; however, past experience 

suggested that high mortal ity at 96 hr mig ht 1 imit the ut il ity of thi s 

measure. 

Taxa/lifestages which were used as a basis for determining 48 and 

96 hr surv i va 1 are the same as those fo r whi ch i nit i a 1 survi val was 

determined . The mean initial survivabilities are shown in Tables 1 

through 4. The res ults indicate that survivorship is taxa- and 

lifestage-specific, as is the relat ion ship between 48 hr and 96 hr 

values. 

The hatchability of eggs observed duri ng the hol ding experiments 

is an index of the vi ability of these eggs. Since t he development time 

of eggs for many of the species tested is quite rapid , nearly all 1 ive 

eggs hatched prior to 96 hr. The proportion of eggs whi ch hatched during 

the holding period and the survivorship of t hes e hatched eggs is 

presented in Table 1. 

The resul ts of holding experiments with control samples which had 

not experienced the fine-mesh screen system ar e also presented in Tables 

1 through 4. These survivorsh ip value s indicate tha t natural mortality, 

not associated with stresses resulting from the coll ecting and holding 

procedures, is a contributing fac t or to t he mortal ities observed among 

organi sms co 11 ec t ed by the fi ne-mesh screen. Th erefore, observed test 

335 
mortal ities should be considered as the cumula t ive effects of t est and 

natural mortality. 

Ana 1 yses of vari ance were conducted to determi ne whether scr een 

t ravel speed (2.1, 4.3 and 8. 5 m/min), velocity approachi ng the screen 

(15.2 and 30.5 cm/s) , or water temperature in fluenced i nitial or la tent 

mortality. These ana lyses were limited t o the most abundant 

taxall ifestages: among fi sh, Anchoa mitch i 11 i, Sci aeni dae and Cynosci on 

spp . eggs and larvae were chosen; for inve rt ebrate s, Brachyura and 

Xanthidae zoeal and megalops stages and Menippe mercenari a zoeal stages 

were selected. 

In general , the analyses did not explain a high pr oport i on of the 

variat i on in mortal ity. The independent variables which were mo st oft en 

significant (p ~ 0.05) were water temper ature and approach ve l oc i ty . The 

temperatur e variable indicated decre asing survival with increasing 

temperature for a 11 1 ifestages except fi sh eggs. Lowest 96 hr survi val 

occurred du ri ng Phase 3 when the highest temperatures occurred. 

Temperature did not have as great an effect on 48 hr survival . It should 

be noted that 96 hr survival of control organisms also decreased at 

higher temperatures , reflecting the difficulty of maintaining these 

organisms for long periods under laboratory condit ions. 

Relative to approach velocity, the analyses 

velocity had a significant effect on egg hatchabil ity 

indicated that 

and survi va 1 of 

Sci aenidae and on 48 hr survival of Xanthidae zoea. However, differences 

i n survi val between 15 . 2 and 30.5 cmls were relatively small: 

Mean Value (%) 

Dependent Variable 15.2 cm/s 30.5 cm/s 

Initial egg survival 80.8 71.4 

Egg hatchability 96.6 93 .3 

48 hr survival of 

Sc iaenidae hatched eggs 89 .5 79.3 

96 hr survival of 

hatched eggs 76.8 64.0 

48 hr surv i val of 

Xanth idae zoea 97.0 94.7 

It must be emphasized that both approach velocity and water 

t emperature, whil e statistical ly significant, explained a small amount of 

336 
the variabili t y i n t he dependent vari able . There fore , with i n the range 

of independent vari abl es tested, t he mean surv ; vorsh; p values presented 

in Tables 1 through 4 are good ind icators of the performance of the finemesh screen facil ity . 

The results of the full-scal e screen study are given in Tables 5 

through 11 as the percent initial and latent survival of fish and 

invertebrate 1 ifestages which were collected from the three stations 

(Screenwash , ORO, and Control) over the duration of the study. In most 

cases, identified taxa were comb i ned into groups for a more meaningful 

analysis . The taxonomic level of each group was determined as the lowest 

level which would allow i nclusion of all important taxa. 

The test data for i nitial survival are presented in Tables 5 

through 7. Results indicate that the invertebrates had the highest 

survi va 1, with mean values in excess of 80% at all three stations. 

Fragile fish larvae had the lowest survival, though there was 

considerable variability between species and stations. 

Fish egg survival was lowest at the ORO station and highest at the 

control station. 

The test data for latent survival are present ed in Tables 8 

through 10. The proportion of organisms alive at 24 and 48 hours was 

used as an index of latent survival . Latent survival was generally high 

for the invertebrates, with survival highest at the control station and 

lowest at the ORO station. Latent survi va 1 of the fi sh 1 arvae was 

generally around 50% , with no sign ificant difference between stations. 

The test data for hatchabil ity are presented in Table 11 . The 

hatchabil ity of eggs during hold i ng is a measure of the viabil ity of 

these eggs. Nearly all viable eggs hatched before 48 hrs after 

collection. The hatchability of eggs was high at all three stations. 

The initial and latent su rvival of organisms from the control 

stations indicate that natural mortal ity, not associated with stresses 

resulting from the fine mesh screen process, is a contributing factor to 

the mortalities observed among organisms collected by the fine mesh 

screens (Table 12) . This factor must be kept in mind when considering 

the test mortalities obtained. 

337 
Table 5. Summary data of initial survivabil ity tests at Screenwash 

Station, Big Bend Power Station (1985). (Survivability: 

1. 00 = 100%) 

FISH 

EGGS : 

CLUPEIDAE 

ENGRAUlIDAE 

SCIAENIDAE 

SOLEIDAE 

ALL EGGS: 

LARVAE: 

CLUPEIDAE 

ENGRAUL IDAE 

ATHERINIDAE 

SPARIDAE 

Lagodon rhomboides 

SCIAENIDAE 

Bairdiella chrysoura 

Pogonias cromis 

Cynoscion nebulosus 

Cynoscion arenarius 

Leiostomus xanthurus 

BLENN I IDAE 

GOBI IDAE 

SOLEIDAE 

ALL LARVAE: 

INVERTEBRATES 

IOEA: 

PENAEIDAE 

CAR ID EA 

PO RTU NIDAE 

PAGU RIDAE 

XANTHI IDAE 

PINNOTHERIDAE 

GRA PSIDAE 

AL L IOEA: 

MEGA LOPS: 

XANTHI IDAE 

GRAPSIDAE 

AL L MEGA LOPS : 

INITIAL SURVIVABILITY 

Total # 

Organisms 

Tested Mean S.D. 

219 0.78 0.04 

21,899 0.48 0.36 

51,202 0.63 0.03 

29 0.88 0.18 

73,349 0. 69 0.18 

2 0.50 0.71 

1,651 0. 16 0. 04 

1 0.00 0.00 

1 0.00 0.00 

1,632 0.61 0.33 

2 0.00 0.00 

1 0.00 0.00 

25 0.00 0.00 

3 0.25 0.35 

107 0.10 0.00 

35 0.00 0.00 

3,460 0.15 0.22 

6 1.00 0.00 

1,057 0.72 0.01 

45 0.94 0.07 

81 0.96 0.04 

11,143 0.93 0.04 

33,287 0.89 0.06 

512 0.92 0.07 

46,131 0.91 0.09 

25 0.77 0.33 

149 0.82 0.20 

174 0.80 0.04 

338 
Table 6. Summary data of initial survivability tests at the Organism 

Return Discharge Stat ion, Big Bend Power Station (1985). 

(Survivability: 1.00 = 100%) 

FISH 

EGGS: 

CLUPEIDAE 

ENGRAULIDAE 

SCIAENIDAE 

SOL EIDAE 

ALL EGGS: 

LARVAE: 

CLUPEIDAE 

ENGRAULIDAE 

ATHERINIDAE 

SPARIDAE 

Lagodon rhomboides 

SCIAEN IDAE 

Bairdiella chrysoura Pogonias cromis 

Cynosc i on nebulosus 

Cynoscion arenarius 

Leiostomus xanthurus 

BLENNIIDAE 

GOBI IDAE 

SOLEIDAE 

ALL LARVAE: 

INVERTEBRATES 

IOEA : 

PENAEIDAE 

CAR IDEA 

PORTUNIDAE 

PAGURIDAE 

XANTHIIDAE 

PI NNOTHERIDAE 

GRAPSIDAE 

ALL IOEA: 

MEGALOPS: 

XANTHIIDAE 

GRAPS IOAE 

ALL MEGALOPS: 

INITIAL SURVIVABILITY 

Total # 

Organisms 

Tested Mean S.D. 

9 

3,522 

16,693 

23 

20 , 247 

2 

271 

284 

11 

1 

5 

1 

575 

2 

458 

7 

21 

7,576 

29,845 

442 

38,351 

5 

109 

114 

339 

0.49 0.13 

0.29 0.21 

0. 40 0.04 

0. 56 0.20 

0.44 0.12 

0.00 0.00 

0.58 0.60 

0.56 0.16 

0.00 0.00 

1.00 0.00 

0.00 0.00 

0.00 0.00 

0.31 0.41 

0.50 0.00 

0.70 0.02 

1.00 0.00 

0.79 0.23 

0.90 0.01 

0.83 0.07 

0.96 0.06 

0.81 0.17 

0.50 0. 71 

0.76 0.08 

0.63 0.63 
Table 7. Summary data of initial survivability tests at the Control 

Station, Big Bend Power Station (1985). (Survivability: 1. 00 = 100%) 

FISH 

EGGS: 

CLUPEIDAE 

ENGRAULIDAE 

SCIAENIDAE 

SOLEIDAE 

ALL EGGS : 

LARVAE : 

CLUPEIDAE 

ENGRAULIDAE 

ATHERINIDAE 

SPARIDAE 

Lagodon rhomboides 

SCIAENIDAE 

Bairdiella chrysoura Pogonias cromis 

Cynoscion nebulosus 

Cynoscion arenarius 

Leiostomus xanthurus 

BLENNIIDAE 

GOBIIDAE 

SOLEIDAE 

ALL LARVAE: 

INVERTEBRATES 

IOEA: 

PENAEIDAE 

CARIDEA 

PORTU NIDAE 

PAGURIDAE 

XANTHIIDAE 

PI NNOTHERIDAE 

GRAPS IDAE 

ALL IOEA: 

MEGA LOPS: 

XANTHI IDAE 

GRAPSIDAE 

ALL MEGALOPS: 

INITIAL SURVIVABILITY 

Total # 

Organisms 

Tested Mean S.D. 

60 0.73 0.38 

16,378 0.72 0.31 

5,872 0.72 0.05 

3 1.00 0.00 

22,313 0.79 0.14 

303 0.16 0.09 

3 0.00 0.00 

95 0.85 0.22 

12 0.60 0.57 

14 0.50 0.71 

35 0.00 0.00 

462 0.35 0.35 

347 0.65 0.09 

14 1.00 0.00 

5 1.00 0.00 

671 0.88 0.10 

2,987 0.77 0.13 

37 0.81 0.11 

4,061 0.85 0.14 

1 1.00 0.00 

24 0.84 0.08 

25 0.92 0.11 

340 
Table 8. Summary data of latent survi va bil ity tests for 24 and 48 hours, 

Screenwash Station, Big Bend Powe r St ation (1985 ). (Survivabil ity: 

1.00 .. 100%) 

LATENT SURVIVABI LI TY 

Total # 

Organ isms 24 hrs 48 hrs 

Te sted Mean S.D. Mean S.D. 

FISH 

EGGS: 

CLUPEIDAE 4 0.25 0.35 

ENGRAU LIDAE 322 0.45 0. 13 

SCIAENIDAE 549 0.44 0.04 

SOL EIDAE 8 0.30 0.18 

ALL EG GS: 883 0.36 0.10 

LARVAE : 

CLUPEIDAE 28 0.59 0. 12 0.44 0.16 

ENGRAU LI DAE 2,200 0.77 0.10 0.68 0.04 

ATHER IN IDAE 1 0.00 0.00 0.00 0.00 

SPARIDAE 

Lagodon r homboides 1 0.00 0.00 0.00 0.00 

SCIAENIDAE 1,852 0.73 0.02 0.63 0.04 

Bai rdiella ch r vso ura 6 0. 50 0.50 0.50 0.50 

Pogon i as cromis 7 1.00 0.00 1.00 0.00 

Cy no scion nebulosu s 2 0. 50 0.71 0.50 0.71 

Cynosc i on arenarius 143 0.57 0.04 0. 44 0. 13 

Le iostomus xanthurus 

BLENN IIDAE 15 0.62 0.28 0.62 0. 28 

GOB IIDAE 39 0.39 0.55 0.36 0. 50 

SOL EIDAE 941 0.98 0.03 0.96 0.04 

AL L LARVAE : 5,235 0.55 0. 32 0. 51 0. 31 

INVERTEBRATES 

IOEA : 

PENAEIDAE 52 0.95 0.07 0.95 0.07 

CARIDEA 1,992 0. 78 0.01 0.67 0. 06 

PORTUNIDAE 34 0.96 0.06 0. 81 0.03 

PAG URIDAE 97 0.77 0.07 0.76 0.09 

XANTHIIDAE 1,771 0.88 0.02 0.80 0.06 

PINNOTHERIDAE 3,499 0.85 0.00 0. 71 0.04 

GRAPSIDAE 176 0.91 0.07 0.85 0.03 

ALL IOEA: 7,621 0. 87 0.08 0. 79 0.09 

MEGALO PS: 

XANTHIIDAE 215 0.99 0.02 0.97 0.04 

GRAPSIDAE 1,230 0.98 0.01 0. 95 0.00 

ALL MEGALOPS : 1,445 0.99 0.01 0.96 0.01 

JUVENILES: 

Lolliguncula brevis 44 0.03 0.01 0.02 0. 03 

341 
Table 9. Summary data of 1 atent survi vabi 1 i ty tests for 24 and 48 hours, 

Organism Return Discharge Station, Big Bend Power Station (1985) . (Survivability: 1.00 = 100%) 

LATENT SURVIVABILITY 

Total # 

Organisms 24 hrs 48 hrs 

Tested Mean S.D. Mean .2.JL 

FISH 

EGGS: 

CLUPEIDAE 2 0. 50 0.00 

ENGRAULIDAE 128 0. 44 0.06 

SCIAENIDAE 505 0.42 0.01 

SO LEIDAE 7 0.65 0.02 

ALL EGGS: 642 0.50 0. 10 

LARVAE: 

CLUPE IDAE 3 1.00 0.00 1.00 0.00 

ENGRAULIDAE 1,249 0.86 0. 05 0.65 0.11 

ATHERIN IDAE 4 0.16 0. 23 0.16 0.23 

SPARIDAE 

Lagodon rhomboides 2 1.00 0.00 1.00 0.00 

SCIAENIDAE 1,376 0.83 0.06 0.66 0.00 

Bai rdiella chrysoura 

Pogonias cromis 1 1.00 0.00 1.00 0.00 

Cynoscion nebulosus 

Cynoscion arenarius 12 0.34 0.47 0.34 0.47 

Lei ostomu s xanthurus 

BLENN I lOAE 2 0.50 0.71 0.50 0.71 

GOBI lOAE 7 0.67 0.47 0.67 0.47 

SOLEIDAE 873 0.93 0.09 0.90 0.11 

ALL LARVAE : 3,529 0.73 0.30 0.69 0.29 

INVERTEBRATES 

IOEA: 

PENA EIDAE 27 0.99 0.00 0.97 0.03 

CARIDEA 2,118 0.79 0.00 0.66 0.00 

PORTUNIDAE 6 0.88 0.17 0.90 0.14 

PAGURIDAE 76 0.81 0.09 0.68 0.14 

XANTHIIDAE 1,799 0.81 0.04 0.71 0.06 

PINNOTHERIDA E 3,674 0.80 0.00 0.65 0.00 

GRAPSIDAE 192 0.94 0.03 0.89 0.03 

ALL IOEA: 7,892 0.86 0.08 0.78 0.13 

MEGALOPS : 

XANTHI lOA E 72 0.93 0.07 0.92 0.08 

GRAPSIDAE 1,469 0.96 0.03 0.94 0.04 

ALL MEGALOPS: 1,541 0.95 0.02 0.93 0.01 

JUVENI LES: 

Loll ig uncu la brevis 4 0.00 0.00 0.00 0.00 

342 
Table 10. Summary dat a of 1 atent survi vabi 1 i ty tests for 24 and 48 

hours, Co ntrol Stat ion, Big Bend Power Station (1985) . (Sur vivabil ity: 1.00 = 100%) 

LATENT SURVIVABILITY 

Total # 

Organi sms 24 hrs 48 hrs 

Tested Mean S. D. Mean S.D. 

FISH 

EGGS: 

CLUPEIDAE 1 0. 50 0.00 

ENGRAULI DAE 30 0.51 0.21 

SCIAENIDAE 109 0. 56 0.06 

SOLEIDAE 1 0.50 0.00 

ALL EGGS: 141 0. 52 0.03 

LARVAE: 

CLUPEIDAE 23 0.88 0.18 0.74 0.01 

ENGRAULIDAE 1, 361 0. 70 0.21 0.59 0.23 

ATHERINIDAE 49 0. 52 0.17 0.46 0.08 

SPARIDAE 

lagodon rhomboides 1 0.00 0.00 0.00 0.00 

SCIAENIDAE 902 0. 77 0. 11 0.61 0.00 

Bairdiella chrysoura 6 0.50 0.50 0.50 0.50 

PQgonias cromis 

Cynosc;on nebulosus 

Cynosc;on arenar;us 3 1.00 0.00 1.00 0.00 

Leiostomus xanthurus 

BLENN IIDAE 147 0. 78 0.08 0.65 0.00 

GOBI lOAE 156 0. 78 0.31 0.75 0.21 

SOLEIDAE 285 0.95 0.01 

ALL LARVAE : 2,933 0.69 0.29 0.59 0.27 

INVERTEBRATES 

IOEA: 

PENAEIOAE 1 1.00 0.00 1.00 0.00 

CARIDEAN 1,362 0.95 0.03 0.88 0.08 

PORTUNIDAE 14 1.00 0.00 0.67 0.47 

PAGURIDAE 44 1. 00 0.00 0.82 0.10 

XANTHIIDAE 750 0.90 0.05 0.85 0.06 

PINNOTHERIDAE 1,281 0.86 0.06 0.74 0.13 

GRAPSIOAE 107 0.93 0.03 0.88 0.00 

ALL IOEA: 3,559 0.95 0.06 0.83 0.11 

MEGALOPS: 

XANTHIIOAE 28 1.00 0.00 1.00 0.00 

GRAPSIDAE 261 1.00 0.00 1.00 0.00 

ALL MEGALOPS: 289 1.00 0.00 1.00 0.00 

JUVENILES: 

loll;guncula brevis 1 0.00 0. 00 0.00 0.00 

343 
Table II. Summary data for hatchability tests of fish eggs from the 

full-scale study, Big Bend Power Stati on (1985). 

(Hatchability: 1.00 : 100%) 

SCREENWASH STATION 

(n) DAY (n) NIGHT 

Clupeidae 6 0.83 5 0.71 

Engraulidae 1299 0.82 562 0.66 

Sciaenidae 1129 0.84 1416 0.76 

Soleidae 815 0.99 64 0.93 

ORGANISM RETURN DISCHARGE STATION 

(n) DAY (n) NIGHT 

Clupeidae 2 

Engraulidae 1140 0.91 219 0.95 

Sciaenidae 881 0.90 1014 0.71 

Soleidae 817 0.99 60 0.92 

CONTROL STATION 

(n) DAY (n) NIGHT 

Clupeidae 

Engraulidae 988 0.98 398 0.99 

Sciaenidae 357 0.92 555 0.89 

Soleidae 4 0.80 

344 
Table 12. Comparison of percent initial and latent (48 hrs) survival 

of sel ected taxa between sampling sites at Big Bend Power 

Station. 

(% SURVIVAL) 

Control Screenwash ORO 

Taxa Initial Latent Initial Latent Initial Latent 

EGGS: 

Engraulidae 72 51 48 45 29 44 

Sciaenidae 72 56 63 44 56 42 

FISH LARVAE: 

Engraulidae 15 59 15 58 58 65 

Sciaenidae 85 61 61 63 56 66 

ZOEA: 

Caridea 65 88 72 67 70 66 

Xanthidae 88 85 93 80 90 71 

Pinnotheridae 77 74 89 71 83 65 

345 
Table 13. Comparison of percent initial and latent (48 hrs) survival of 

prototype and full-scale test results. 

INITIAL % SURVIVAL LATENT (48 HR) r. SURV IVAL 

Full-Sea 1 e Full -Scale 

Screen- ScreenPrototype wash ORO Prot otype wash ORO 

INVERTEBRATES : 

Caridea 94 72 70 85 67 66 

Xanthidae 99 93 90 96 80 71 

Pinnotheridae 100 99 83 92 71 65 

FI SH LARVAE: 

Anehoa mi t chilli 2 16 58 22 68 65 

Sei aenidae 19 61 56 11 63 66 

FI SH EGGS: 

An choa mi tchi l li 43 48 29 80 82 91 

Sci aen idae 75 63 56 95 84 91 

346 
DISCUSSION 

Based on the survivability results of the 1980 prototype study , it 

was concluded that the installat ion of fine-mesh screeni ng at the Big 

Bend Power Stati on Units 3 and 4 represented a viable technology which 

would resu l t in lowered entrainment l osses . Those results showed a high 

initial survival and hatchability of fish eggs; a high initi al and latent 

survival of invertebrate taxa; and a relatively low initial and latent 

survivabil ity of fis h larvae, among both test and cont rol organisms. 

Results of the 1985-86 full-scale study showed similar initial and latent 

survival and hatchability of fish eggs; a high initial and latent 

survival of invertebrate taxa; and a lower initial and latent survival of 

fish larvae (Table 13). However, the fu l l-scale study exhibited higher 

initial and laten t survivability of fish larvae than the prototype study. 

It is reasonabl e to assume t hat these differences are rel ated to the 

sampling techniques used for the two studies. 

It can al so be seen from the results of both studies that there 

are natural morta li t ies in the organisms being studi ed. Survivability of 

organi sms from the control stat ions showed 1 ittl e difference between 

those from the test stations. As would be expected, higher mortalities 

were seen at the ORO station during the full-scale study. However, these 

mortalities were st ill within expected limits which were predicted by the 

prototype study . 

The results of the full -scale study show that the use of fine mesh 

screens is a vi able solution to reduce entrainmen t. The prototype study 

provided the necessary information to opti mize the fine mesh screen 

hydraulic characteristi cs and organism return discharge . 

347 
POWER PLANT INTAKE EFFECTS ASSESSMENT: 

WHERE'S THE DRIFT? 

REVIEW PAPER 

J.S. Mattice 

Electric Power Research Institute 

Palo Alto, California 

ABSTRACT 

"Drift" appears to characterize the assessment of intake effects 

at hydroelectric and thermal electric power plants in two ways. First , intake effects stem from drift. Organi sms that dri ft near power pl ant 

intakes are subject to impingement and the thermal, chemical, and 

physical stresses of entrainment. These stresses can affect individuals 

such that effects are translated to the population, community, and 

ecosystem level of organization. Although assessments can be made at any 

of these levels, ecosystem-level assessment is the ultimate goal. 

However, industry-regulatory interactions now appear most limited by 

abilities to conduct population level assessments, specifically by the 

need to defi ne and quantify dens i ty-dependent and dens ity- independent 

mechanisms that control population response. Second, the science of 

assessment appears to be drifting. The need for study of population 

control mechanisms is clear, but little concerted effort is focused on 

these mechanisms. Without such a focus, the drift will remain in the 

science of assessment, and how much of the drift of organisms into power 

plant intakes needs to be prevented will remain a question. 

348 
INTRODUCTION 

Few subjects have received as much scrutiny over the last fifteen 

years as power pl ant i ntake effect s. Sc i ent i sts and eng i neers have 

produced a formid able number of papers on the subject. Within the 

constraints placed on this presentation, there were thus two 

possibilities: 1) select one small aspect of intake effe cts and deal with 

it exhaust ively ; or 2) present an overview of the whole subject with an 

emphasiS on conclusions. This is an overview. The focus is on 

assessment, because every utility is facing or will face t his task in the 

near future . This revi ew begins with an opi ni on , examines the current 

state-of-t he-art t o support that opini on, and concludes with a 

recommendat ion . As such, it can be viewed as a positi on paper with 

elements of a revi ew. 

The answer to the question in the title of thi s paper (where is 

the drift?) is the basis for t his presentation. The word "drift" has 

over 30 meanings or synonyms , according to Webst er's New Twentieth 

Century Dicti onary, Unabridged. Each of t he se mean i ngs, or synonyms, 

implies a lack of control over directi onal movement. Drifting organisms 

are suscept ible to the thermal, chemical, and/or physi cal effects of 

entrainment or to impingement on i nt ake screens. Less recognized is the 

relevance of the concept of drift to the science of assessment itself. 

My opinion is that the major problem of power pl ant intake assessment has 

been ident ified . This problem is the current inability to quantify 

population control mechanisms, both density-independent and densitydependent (compensatory). However, because there has been no concerted 

effort by ei ther t he industry or regulatory communities to identify and 

quantify these mechanisms, we are not in control of the progress of 

assessment: the science is adrift. It is this dri ft and the research 

that is needed to end it that con sti tute the focus of this pre sentation. 

The thesis of this presentation, then, is that the utility 

industry and regul atory agency communities need to focu s research on 

quantifying popul ation control mech an isms. I wi ll attemp t to direct 

attention to the need for this research by deali ng with three questions: 

what are we trying to do; how we ll are we doing it; and why aren't we 

doing it better? The answers may seem to be belabori ng the obvious. 

349 
More likely, they will be highly contestable. If so, this presentation 

wi 11 have successfully st imul ated di scuss i on. How'2ver, my primary intent 

here is to provide a convincing argument that research on population 

control mechanisms is a necessity --not a luxury-- if we are to improve 

the capability to reliably assess effects of power plant impacts. 

Consideration of the three questions is directed t oward supporting th·s 

thesis. 

WHAT ARE WE TRYING TO DO? 

Most decisions about whether an impact is allowable or a 

mitigation is sufficient are socio-political . 

how much society is willing to pay either in 

utility industry perspective) or in 

These decisions depend on 

dollars for electri city (a 

rna i ntenance of des i r abl e 

environmental conditions. Three laws and their amendments direct 

decision making with respect to power plants: the National Envi ronment al 

Policy Act; the Federal Water Pollution Control Act; and the Federal 

Power Act. The last is applicable to hydropower development and 

operation. With the recent focus on effects of hydropower generation, it 

is important to i ncl ude turbi ne mortal i ty wi th impi ngement and 

entrainment as intake concerns for the utility industry. Ecologists' 

input to decisions are most often through the impact assessments dictated 

by one or more of these three laws. 

There is room for interpretation about how the goals of the laws 

are to be fulfilled. Each of the laws includes its rough equivalent to 

"maintenance of a balanced, indigenous population of shellfish, fish and 

wildlife ". It seems clear that each law is aimed at balancing the 

benefits and costs of power generation and maintenance of a viable 

environment (Milburn and Ginsberg 1978; Springer and Morgan 1986; Brown 

1986) with respect to intake and other effects. However, assessment and 

environmental protection can be viewed at a number of biologicalecological levels of organization (Figure 1). The format shown borrows 

elements from Coutant (1974) and Mar et al. (1985). The direction of the 

arrows indicates a reductionist philosophy, suggesting that impact 

assessment at the individual level is needed before assessment at higher 

levels of organization is possible. This is reasonable but not 

350 
universal ly accepted ; others would argue that ecosystem funct ion is the 

important criterion. Howeve r , if there is agreement that decisions 

regarding devel opment and environmental protection are socio-political , 

then ecosystem func tion per se does not appear suffic ient: it does matter 

to the publ ic, for exampl e, whet her fish protei n is i n the form of carp 

or trout. The anthropocentric i ty of societal val ues may require 

multipl e-leve l assessment even if the philosophy of assessment is 

holisti c. There are few who woul d argue against t he desi rability of 

includi ng tot al ecosystem costs i n assessment, but many would argue that 

this is unfeasi bl e. Thus, point s of difference between utility and 

regul atory biologists have general ly evolved into quest ions about the 

type of information t hat is needed t o demonstrate best the balance 

between benefits and costs of generation . 

HOW WELL ARE WE DOING? 

The discussion of t his question is subdivided accordi ng to the 

different levels at which assessments can be conducted (Figure 1). 

Although an swe rs are provided for each level , they are subjective and 

therefore open to debate. 

Exposure 

Exposure does not appe ar to be a very useful concept with respect 

to impingement . Th is is partly due to t he probl em of defining 

impingement exposure. Are al l fish found near the intake exposed to 

impingement? Probably, this is not the case, because some species 

collected i n the area of intakes rarely or never appear on the screens 

(Loar et al . 1981; Logan and Kle instreuer 1981 ) . However, authors of 

both the cited papers fo und t hat , for certa i n speci es, distri bution and 

abundance in the water body were important for estimati ng impingement. 

Are fish t hat contact the screens the expos ed fraction of the population? 

We know that fis h can contact t he screens and escape at least 

momentaril y. But does initial escape represent only a temporary reprieve 

from impingement? Or does t he individual truly escape. Do the live fish 

found on the screens when t hey are raised represent the exposed group, or 

are they Si mply in t he interim stage between impi ngement and the effect 

351 
of impingement (death)? The point is that there is not yet a cl ear 

definition of impingement exposure, much less a means to estimate it. 

Entrainment exposures at thermal electrical power plants have all 

been based on the assumption that exposure is proportional to the pl ant 

flow re 1 at i ve to t ot a 1 water body flow or volume (Engl ert et a 1. 1976; 

Goodyear 1977; Bo reman et al. 1981 ). In some cases, a correction factor 

has been added t o account for distribution of entrainable organisms in 

the water body. Hydrodynamic models also appear to require correction 

fac tors to account for behavi oral mechanisms that allow limi ted 

independence from net water body flows (Swartzman et a 1. 1977) . The 

assumpti on that exposure to entrai nmen t is proportional to flow and 

plankton distribution does not appear ill ogi cal . However, the patchiness 

of plankton distribution and the inability to sample continuously either 

near the intake and/or within the plant suggest that entrainment exposure 

estimates will not be verifiable. 

Estimation of exposure to entrainment at hydro-electric plants 

appears less tractable than for thermal electric power plants. Most of 

the concern about exposure to turbine mortality has been for anadromous 

fish (e.g., salmon and American shad ). Exposed fish are either fairly 

large, immature stages or adults. In either case, they are - mo tile. 

Thus, it seems doubtful that exposure is simply proportional to the ratio 

of turbi ne water fl ow to total water flow past the plant for these 

species. In addi tion, problems involved in obtai ning representat ive 

samp 1 es of fi sh in t he fl ows through and around the turbi nes at most 

hydro-electric sites make it difficult to measure exposure or to validate 

predictions based on relative flows. Predictions of exposure of eggs and 

relativel y non-motile larvae in the water column above hydroelectric 

si tes appear more reliable, but sampling problems may be as formidable as 

for older li fe stages. Thus, exposure to entrainment probably cannot be 

predicted or measured very accurately at most dams. 

Ind ividual Re sponse 

Progress toward realistic predict ion of impingement mortality at 

power plants has been slow . Impingement model s have been constructed, 

bu t most are based on assump tions that are known to be unrealistic (see 

352 
Logan and Kl einstreuer 1981 and references therein) . Other assessment 

mode ls ut il ize impingement coefficients that are of quest ionable 

general ity. Consensus supports fish distribution, swi m speed and effects 

of temperature on swim speed, and overall fi sh fitness as par ameters 

important for predicting impingement. Predictions usi ng a model 

includi ng these parameters (Logan and Kleinstreuer 1981 ), however, ranged 

from 20 t o 548% and 35 to 143% of actual numbers imp inged for threadfin 

and gizzard shad , respectively. The range of these differences suggests 

that, as yet, we have not identified all of the paramet ers important in 

determining impi ngement. One such parameter is differenti al flow across 

individual screens of an intake (Mclean et al. 1982). Hyd rodynamics in 

the intake areas are not simple, thus, predictions of impingement 

mortality mu st be viewed with healthy skepticism. 

Substantially more progress has been made t oward measuring 

impingement. Spatial and temporal designs have been developed to solve 

the probl ems inherent in predicting tot al yearly impi ngement from limited 

sampl i ng at operating power plants (Murarka et al . 1978). If these 

sampling designs are followed, confidence intervals can be calculated for 

the impingement estimates. 

Mort a 1 i ty of organ isms (algae, zooplankton, i chthyop 1 ankton) 

exposed to entrainment at thermal elect ric power plants is both 

predictable and measurable. Studies with condenser simulators (Cada et 

al. 1981; Jin ks et al. 1978, 1981; Poje et al. 1982) and at operating 

power pl ants (Jinks et al. 1978 , 1981) have shown t hat mortal ity of 

entrained organisms depends on the physi cal (thermal , me chanical) and 

chemical (bi oc ide s) stresses encountered. Results i n t he laboratory show 

relatively good agreement with those observed at powe r pl ants as long as 

levels and time courses of stress or exposure at t he power plant are 

carefull y dupli cated (Ji nks et al. 1978, 1981). In add ition, sampling 

designs (Boreman and Goodyear 1981) and collection t echniques (McGroddy 

and Wyman 1977 ; Jinks et al. 1981) are sufficientl y advanced to provide 

accurate me asures of entrainment mort ality . Thus, entra i nment mortality 

at thermal el ectric power plants can be predi cted at new or operating 

power plants, or it can be measured once a plant is on-line. 

353 
Prediction and measurement of mortality of fish entrained at 

hydroelectric plants are more difficult than at thermal electric pl ants. 

Effects are thought to be mediated via pressure changes (e.g ., 

cavitation), shear forces, and contact with conduits or turbines (Ruggles 

and Coll ins 1981). Howeve r, it has not been possible to relate types of 

physical injuries specifically to one of t hese sources. Syst em changes 

also generally affect more than one of these mortality sources, so it is 

difficult to isolate the ir contributions t o mortality. Add to this the 

fact that system si ze and the relative size of the system to that of the 

fish are important de terminations of mortality, and it becomes clear that 

predict ions must be based on studies at full-scale fac ilities (Turbak et 

al. 1981) . Unfortun ately, the large volumes of water passing through 

most hydroelectric plants make full-scal e studies difficult at many 

sites. Full-scale studies have yielded wide ranges of mortali ty 

estimates (Ruggles and Collins 1981). In some cases the differences can 

be semi-quantitatively related to system de sign or operation, but truly 

quantitative conclusions are subject to valid criticism. Prediction of 

effect s of hydroelectric plant entrainment th us seems possible only in 

gross terms. Even measurement is probably feasible only at a small 

percentage of operating plants . 

Sublethal or indirect effects of entra inment at hydroelectric or 

thermal electric pl ants are thought to occur but are largely 

unquantified. Post-exposure observations of impingement or entrainment 

effects in the laboratory or at power plants have not extended past a few 

days, at most. This obviates observation of possible longer-term 

sub 1 etha 1 effects. Laboratory stud i es have shown that hungry predators 

selecti vel y prey on stressed fish when stressed and unstressed prey fish 

are presented together (Coutant 1973). Observations that fishermen 

congregate near the discharges of both hydroelectric and thermal electric 

power plants suggest that predatory game fish are actively feeding in 

those areas, but whether they are feeding on dead, moribund, or stressed 

ind iv idual s is moot. Quantification of secondary effects such as 

increased predation on stressed fish may not be amenable to field 

investigation. 

354 
Popul ation Response 

Methods for estimating population response to intake effects can 

be div ided into three classes depending on the level of the population 

for which predi ct ions are made. Young-of-the-year (Y -0- Y) model s are 

designed to predict the loss of the portion of population produced during 

a gi ven year. Adult population models are designed to predict the effect 

of Y-O-Y losses on the population that woul d exist when the Y- O-Y class 

becomes vulnerable to sport or commercial fishing. Long -term models are 

designed to predi ct cumulative effects on the populati on of consecutive 

yearly losses of Y-O-Y fish at power plants. 

Young-of-the-year model s incl ude 

McFadden and Lawl er (1977), Boreman et al. 

Barnthouse et al. (1982) and others. 

those of Goodyear (1977), 

(1981), Lawler et al. (1981), 

The simpl est of t hese are 

essentially "Indi vidual Response" models (see above), because natural 

mortali ty is not included in the analysis. A second set of these models 

does include natural mortality rates in the Y-O- Y impact predictions, but 

natura 1 mortal i ty rates are assumed not to be affected by power plant 

included mo rtal ity. In other words, these mode ls are all based on the 

assumpti on that density-dependent (compens atory) regulation is not 

operat ive on the Y-O-Y life stages. Such an assumpti on must be judged as 

conservat i ve, surely protecting or over-protecting the year cl ass of 

fish, because: 

1) compensation is generally thought to operate during the 

earl y l ife stages (Science Applications, Inc. 1982) ; 

2) f ish populations have demonstrated the ability to 

maint ain population stability in the face of heavy fis hing 

mo rtality (McFadden 1977); and 

3) model studies have shown that losses of Y-O-Y fis h, even 

without compensation, are substantially less severe than 

equi val en t losses of reproductive and fishabl e adults 

(Ch ristensen 1985) . 

A third set of these models includes effects of powe r plant mortalities 

on natural mortality by including density-dependent terms in the model 

formulati ons. These models seem potentially more realistic, but both the 

355 
forms and 1 eve 1 s of the compensatory re 1 at ions have been subjects of 

great controversy (Christensen et a1. 1981). 

Th is controversy has raised even more questions about impact 

predi ct ions based on Y -0- Y models . Such models are not intended to 

predict long term population responses . Lack of consideration of 

cumulative yearly losses of Y-O-Y fish, though, t hrows doubt into the 

cost-effectiveness of mit igation measures based on Y-O-Y models. 

Est imates ba sed on t hese mode ls will not necessarily be indicative of the 

best choices for society, because it is not clear that these Y-O-Y losses 

have any rela tionship to long term fis h populati on changes . 

Neverthel ess, Y-O-Y models have probabl y played a larger rol e in sociopolitical decisions than t he other t ypes of population models. 

Adult populat i on models i nclude those developed by Horst (1 975), 

Goodyear (1978), and Rago (1984). These models translate losses of Y-O -Y 

to adult fish by using a number of differen t, sometimes complex, 

conversion factors. Polgar et al. (1981) extended this type of 

projection to an "ecosystem type" analysis by conducting such 

extrapolations for multiple populations in a single ecosystem. 

Regardless of t he f actor(s} used for extrapolation, each of these 

ana lyses has been bas ed on the assumpti on that natura 1 mortal ity is 

unaffected by power plant induced mo rtality. As with the Y -0- Y models, 

this assumption prec ludes consideration of compensatory responses in the 

predicted effects. Cumulative yearly losses of Y-O-Y also are not 

included, so t he actual effe ct may be higher or lower than predicted by 

these adult population mod els. 

Long-term assessment techniques include parent-progeny (Sissenwine 

et al. 1974; Christensen et al. 1977; Lawler and Englert 1981; Lawler et 

al. 1981; Lawler 1984; Crecco 1985; and Lorda et al. 1987), stockassessment (Jensen 1982; Jensen et a 1. 1982; Stanford et a 1. 1982; 

Ma cCa ll et al . 1983), and age-structure (Van Winkle et al. 1974; 

Christensen et al. 1975; UEC 1975; Warsh et al. 1975; Englert et al. 

1976 ; Lorda et al. in press; Saila et al. in press) models formulated to 

pred ict multi-generat ion populat i on effects. Each of these models 

inc 1 udes one or ore dens ity-dependent funct ions, requi red to counter 

impact-prod uc ed extinction. 

356 
None of these models has been validated, and thus predictions 

based on them are subject to substantial controversy . Year-to-year 

variation i n density-independent environmental parameters and lack of 

age-structured historical data obscure the relative importance and 

quantifi cation of density-dependent (compensatory) relati onships in the 

parent-progeny and stock-assessment mode ls. Lack of agreement about 

quantification of specific density-dependent relationships in the more 

mechanisti c age -structure mode ls has made predictions based on them 

controversial . Th us, l ong-term population predictions of impact have 

made only a limited contribution to decisi ons about citing and operation 

of power plants. 

Community Response 

It has not been uncommon t o deal with power pl ant effects at the 

community level. For instance, effects of entrainment on mortality of 

zooplankton and production of phytoplankton are more often dealt with as 

group responses than as responses of indi vidual species of these groups. 

Diversity indices (Lawler et al. 1981) have al so been useful in some 

impact assessments, although under certain circumstances these appear as 

likely to be measures of direct ind ividual or population responses as 

true community responses. Other contri but ions to impact assessment at 

the communi ty level have been deri ved from cluster analysis, ordination, 

and niche breadth/speci es packing. 

Howeve r, communi ty simul ation models per se do not appear to have 

been developed for assessment of intake effects. This is probably due to 

benefit-cost considerations and t o the real ities of assessment. 

Community analys es must deal with specifi c interpopulati on relationships, 

which have proven di fficu lt to identify and quantify. For this reason, 

investigators willing to make t he effort to include thes e interactions in 

assessments seem to have made the additional step t o ecosystem analysis. 

On the other hand, power plant impacts are thought to mimic abiotic 

effects. Strictly defined, commun i ty level analyses thus ignore some of 

the interacti ons of most interest in impact assessments. It is not 

surprising, then, that power plant impact mode ls are generally available 

357 
for popul at i on or ecosystem assessments, but not for commun ity 

assessmen t s. 

Ecosyst em Res ponse 

Applicati ons of ecosystem mode ls for impact anal yses whi ch are 

useful for regulatory/industry purposes have been r are. The rea sons are 

di verse but probably relate t o cost , effort , and uncertai nty of 

predicti ons. All of th s~ t end to increase as level of analysis proceeds 

fr om individual to ecosyst em (Fi gu re 2) . Extrapolation of effects on 

i ndiv idu al s to th e ecosystem l evel of organizat ion requires 

ident ification of the structure of populations and communi ties and 

quantifi cation of t hei r fun cti onal rel at ions i n respon se to bot h biot ic 

and abiot i c cond ition s. At t he "simple st " level, th is can be 

accompl ished wi t h t rophi c leve l (food web) models combi ned with feedback 

l oops via decompositi on and nu trient regener ation. There are probl ems 

wi th assessments of t his type (Pikitch et al . 1978 ), howeve , especial ly 

if speci fic organisms or organ ism groups are of part icul ar interest. 

Conversel y, attempts t o define and quanti fy all of t he relationships i n 

an ecosystem run up agai nst information gaps at t he popul ation and 

commu nity levels of organ i zation . Given t he complexity of ecosystem 

structure, such anal yses become comput at ionally unwieldy, if not 

impossible . Thus, ecosyst em analyses have al l i nvol ved some aggregation 

into groups . But combin i ng l ead s to l oss of informa tion and reality. 

The ecosystem models summarized below as exampl es involve various levels 

of aggregation to faci li t ate analysis. 

Kemp (1981 ) used a t rophi c dynamic model to compare the regional 

energy costs of once-through and cl osed- cycle cool i ng of a third power 

plant added at a si te where t wo units already were oper ating. The model 

was a simpl ified simulation of biomass standing crops and transfers in a 

complex ecosystem. Tr an sfers were comb ined into two food chains 

depending on the food source (pl ankton, detritus) of the primary 

con sume rs. The model was calibrated using data from control areas, then 

tested by compari ng mod el predict ions unde r conditions caused by the two 

existing plants with data collected near t hose power plant discharges. 

Agreement was "rel ati vely cl os e" so t he model wa s used to predict changes 

358 
expected from addition of the third plant. Impacts were translated to 

photosynthetic energy equivalents using biomass t r an sfer efficiencies 

between troph i c levels and bi omass to energy conversions. Earlier 

versions of this analysis were based on using total community metabolism 

as a proxy for energy flow (McKellar and Smith 1981). Ecosystem energy 

losses using a once-through cool i ng mode we re t hen compared to energy and 

ecosystem costs of bui l di ng and operat i ng mechanica l draft cooling t owers 

to mitigate the effects of once-through cooling. The energy costs of 

mit igation were estimated to be about 15 to 20 times the energy losses of 

the ecosystem impacts. This type of analysis, however, assumes t hat 

energy is equivalent whether it is in the form of "game" or "trash" fish 

--an assumption that is not real isti c . 

Researchers at t he Illinois Natural History Survey (ILHS 1979a, b, 

c, 1980 ) in cooperation with Commonwealth Edison Company staff, 

constructed a Cool ing Lake Ecosystem Mod el (CLEM) as part of an effort to 

assess effects of operation on the Kincai d Generat ing Station on Lake 

Sangchris in III inois. A physi cal model (TEMP) was used to describe 

water temperatures and volumes in fou r areas of the cool i ng reservoi r 

based on meteorological and plant operational conditions. The ecosystem 

model (CL EM) consists of a series of submodel s, whi ch describe 

phosphorus , detritus, phyt oplankton , peri phyton, macrophytes, 

zooplankton, benthos, and fis h dynamics . Each of the biological 

submodels is composed of a seri es of different ial equati ons describing 

physiolog i cal processes . These included food intake, digestion, 

respiration, exc retion, reproduction, growth, and mortality as functions 

of water temperature. Mass is conserved with in and between all 

compartments and numbers are also conserved within the fish submodel. 

Transfers are gener ally mediated via food-consumer interactions and 

mortality. Sport fishing is considered explicitly . The submodels 

include different levels of resolution . For example, the phytoplankton 

submodel is divi ded into blue-green and non -blue -green algae modules, 

whereas the zooplan kton submodel aggregates al l (and only) herbivorous 

species . The fish submodel t re ats eight age classes each of the 

sportfish blueg ills, largemouth bass, white bass, and channel catfish , 

and the for age fish, gizzard shad, separately. The model allows 

359 
evaluation of different management scenarios (e.g. , plant operation and 

fis hi ng regulations). 

The TEM P model provided reasonable fi ts t o temperatures measured 

in Lake Sangchris; t he CLEM was only partially evaluated using labor atory 

and field data. The structure of the CLEM is general enough to be 

applied at other cooling lakes, but th is has not been attempted. 

Porce 11 a and coworkers (Porce 11 a et a 1. 1983; Gri eb et a 1. 1983; 

Porcell a et al. 1986) developed an Ecological Assessment Model (EAM ) to 

predict impacts of power plants on cooling lakes. The model is a trophic 

dynamics model t hat handles biomass (dry weight) transfers and el emen t 

cycling. The model can be coupled to a hydrodynamics model t o predi ct 

chemical conditions at seve ral depth strata. Trophi c level analyses can 

include several groups of species. For example , green algae, diatoms, 

bl ue-green algae, and "others" were used to represent primary producers 

in the Lake Norman validati on studies . 

Model verificati on studies were conducted at Lake Norman, a 

cooling reservoir in North Caroli na. The model was cal i brated using one 

set of data from the reservo i r, then evaluated us i ng a separate set 

covering five years of measurements. Predictions of temperature, 

di ssolved oxygen, pH, and sili cate were within 10 to 20% of those 

me asured. Ni trogen , phosphorus, phytoplankton, and zooplankton 

predict ions were within 40 to 100% of those me asured. The variations in 

these predictions are similar to those found fo r other ecosystem models 

and parallel the accuracy of field methods used to measure those 

variables. Fi sh biomass data were too 

values, but the cycles of fish 

imprecise to evaluate predicted 

biomass qualitatively matched 

expectati ons. Although further testing is required for validation, this 

model appears promising. 

Ecosystem models inherently include some compensatory functions in 

their formulati on. As l ong as these models include mass balance 

structures, loss of individuals within a trophic level will result in 

increased growth of the remaining indiv iduals at that level because of 

the larger per capita availability of food. However, other compensatory 

relationships, including disease and parasitism, are not explicitly 

included in these models. These i ncl ude disease and parasitism. Other 

360 
density-dependent (compensatory) trophi c transfer rate changes are (or 

can be ) included in ecosystem models. For some speci es, these rate 

changes are based on empi ri ca 1 data; for ot hers the rate changes are 

based on generalization of data from studies on other species. The model 

of Porcella et al. (1986), for exampl e incl udes a mix of species-specific 

and generic relationships t o estimate effec ts of growth on predation. 

The data base for Quant i fi cat i on of such re 1 at i onsh ips is the same as 

that which limits popul ation l evel assessments definition and 

quantificati on of population i nteraction limits both population and 

ecosystem level assessments. 

In other words, t he ecosystem models are l imited in predictive 

capabili ty by probl ems similar to those that limit success of population 

models. Defin ition and quantification of complex rel ationships within 

and between individual species popul at ions are necessary for accurate 

assessment of ecosystem impacts of power plants. 

WHY AREN'T WE DO ING BETTER? 

The re is no simple answer to th is questi on. Devel opment of new or 

improvement of existi ng methods of me asurement and predi cti on at all 

levels of assessment from exposure to ecosystem (Fi gure 1) will improve 

power plant impact assessments. For example , improving methods of fish 

population sampling would imp rove assessments at al l levels. Assessment 

of effects on all components of t he ecosystem is the ultimate goal. 

However, progress toward t hat goal can be hastened by focus i ng on the 

level or iss ue that most limits the usefulne ss or acceptance of current 

assessments . For assessment of effects at the individual level, eXisting 

methods appear adequate for use at steam el ectric plants but need 

improvement to ensure reasonable accuracy at hydroelectric plants. At the 

other extreme , improvement of ecosystem-level assessments wi ll at least 

partly invol ve i ncre ased consideration of communi ty and population 

relationshi ps. Th us, regardl ess of t he initial focu s, it appears that 

the current question of most i nt erest is: why aren't we doing better at 

assessing impacts of power plants on populations? 

One way to approach the answe r to this more restricted question is 

to consider an example . The "Hudson River Controversy" (Barnthouse et 

361 
al. 1984) is an excellent example, because of t he extensive documen t ation 

of the scientific analyses, the ir evolution , and their contri bution t o 

the ultimate socio-political decision (see Swa rtzman et al. 1977; 

Ch ristensen et al. 1981; Barnthouse et al . 1984 and references therein ). 

In brief, the Hudson River uti lity companies agreed, among st other 

things, to flow reductions and scheduled outages duri ng certain periods 

of the year i n return for maint ai ning once-through cooling . Flow 

reduct ions and outages were des i gned to protect sens it i ve 1 ife st ages 

only during those seasons. The basis fo r the negoti ated settlement was a 

series of comp arisons of conditional mortalities resulti ng from 

entrainment of fish eggs, larvae and j uveniles under several different 

cooling water flow scenarios . These Y-O-Y models (see earlier section) 

included natural mo rtality, but no den sity-dependent (compensatory) 

functions . Cumulat ive effects of yearly losses also cannot be considered 

with these model s. The rea son that thes e model s were used wa s because 

the two sides could not agree on the l evel of density-dependen t 

regulation in fish popul ations in the Hudson, or which l ife stages were 

affected by these controls . Without such agreement, long-term 

projections of population response (e.g., for striped bass) remained 

controversial. In other words, because density-dependent population 

regulation could not be demonstrated or quantified objectively, 

mit igation actions were based on assessment at t he population level, but 

in a manner that included only annual , not cumul ative , impacts. 

Whether the dec ision was wise or fool hardy has not been 

determined, but the ba sis for that decision ind icates a majo r deficiency 

in the science of impact assessment. Because density-dependent 

mechanisms could not be included in the impact assessment, the cumulative 

yearly impacts on Y-O -Y were ignored. Whether the former would 

ameliorate the latter is open to question. Until density-dependent 

mechani sms can be quantified, there can be no scientifically objecti ve 

conclusion. It should be clear that, until the ability to determi ne the 

level at whi ch a population can sustain itself in the face of 

anthropogenic sources of mortal ity is devel oped, prediction s of the 

environmental impacts of power plant operation will be of questionable 

accuracy. We can only hope that potential errors cancel , so that soci ety 

362 
does not incur too much in the way of unneeded economic or ecol ogical 

costs. 

The science of power pl ant impact assessment is drifting, and the 

problem is apparent. Identi fication and quantification of densi ty -

dependent (and den sity-independent) population controls are needed t o 

realistically extend assessments to populations. Until a concentrated 

effort is directed t oward quantifying population cont rol mechanisms, 

science will not control the assessment process and provide information 

to support optimal socio-political decisions about the benefits and costs 

of powe r generation. It is time to make this effort; otherwise, like fish 

eggs and larvae in front of power plant intake screens, we wi ll continue 

to drift on into mo re troublesome areas. 

ACKNOWLEDGEM ENTS 

Many indiv iduals have contributed to t he ideas in this paper; 

several provi ded the benefit of discussion while it \"las being written. 

These include Sigurd Christensen, Thoma s Englert, Richard McLean, Robert 

Otto, Dona ld Porcella, and Douglas Vaughan. However, final 

responsibili ty rests with the author: the ideas expressed should not be 

assumed to be support by the EPRI or the utility industry. 

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369 
IMPACT MITIGATION AND ENVIRONMENTAL ENHANCEMENT: 

IT DOES WORK 

J. Ross Wilcox 

Environmental Affairs 

Florida Power & Light Company 

Juno Beach, FL 33408 

ABSTRACT 

Florida Power & Light Company is in active participant in impact 

mi t i gat i on and envi ronmenta 1 enhancement wi th more than ten years of 

experi ence. The object i ve of thi s impact mit igat i on and envi ronmenta 1 

enhancement is to foster the compatibility of wildlife and the production 

of electricity. Tangible benefits have accrued to both wildlife and FPL. 

The primary focus of this work has been on federally designated 

endangered and threatened species, but the efforts have expinded to 

migratory species, state protected species, and hibitat conservation. 

Examples of impact mitigation and environmental enhincement ire reviewed 

for the West Indian manatee, three species of sea turtles, the Americin 

crocodile, the southern bald eagle, and the Barley Barber Swamp. 

370 
INTRODUCTION 

Florida Power & Light Company (FPL) is the fifth largest investor 

owned util ity in the U.S . and serves more t han six mill ion people in a 

serv i ce area that includes about one half the geographic area of Florida. 

Approximately 75% of FPL's generation is used by re sidential and 

commerc i a 1 customers, in contrast to other areas of the country, where 

industrial customers dominat e. Within our service area , which 

encompasses all or part of 35 counties, FPL operates 11 power pl ants. 

Power is distributed via 63,000 km of high-voltage transmission lines. 

Approx imately one-thi rd of the gener ating capacity of the system is 

provided by nuclear energy, one -half by oil and natural gas, and the 

balance by interchange and purcha se power. 

The Company owns and manages approxi mately 325 km2 of 1 and in 

Florida. Thi s land is located in urban and rural areas and comprises 

wet 1 and and upland areas . Much of it is undeveloped and is used as a 

buffer zone to isolate power plants, substations, and transmission lines 

from agricultural and r esidential interests. These undeveloped buffer 

zones serve as wildl ife habitat for many species, both common and 

protected. 

Florida's unique environment of habitat and climate presents FPL with 

some interesting challenges. For inst ance, 40% of ou r service territory 

includes wetlands, swamps and lakes; about 40% is forested, and about 20% 

is cropland or urbanized. The Company must build or ma intain power 

plants, transmission lines, and substat ions in all these env ironments. 

Climates in Florida show great variati on also and create habitats 

for a diverse array of plants and animals not seen elsewhere in the 

continental United States. For instance, freezing t o temperate 

conditions are common in northern Florida, such as Gainesville, and 

permit only certa in types of plant s and animals to exist. Conversely, 

frost rarely occurs in South Florida, such as Miami, and allows a 

subtrop i cal group of plants and animals to flourish. 

Many plants and animals are common and frequently seen throughout 

Florida. On t he other hand, because of the sensitivity of Florida's 

habitats to water cycles and the convers i on of wetland and forested 

habitats to serve the agricultural and population needs of Florida, a 

371 
large number of plants and animals are near extinction . On the federal 

l evel , more t han 60 plants and animals of Fl orida has a more 

comprehensive li st that i ncl ude s 541 species of concern (Wood, 1986). 

Duri ng the production and transmission of electri city, FPL i nteracts with 

both common and endangered species. 

Fl orida Power & Li ght Co . is an active participant i n impact 

mitigation and environmental enhancement with more than ten years of 

experi ence. The objective of the efforts is t o fost er t he compatibility 

of wildl ife and the product ion of electri city (W il cox, 1979, 1980 ; 

Morgenthal er, 1987) . The primary focu s of thi s work ha s been on 

federall y de si gna ted endangered and threatened speci es, but t he efforts 

have expanded to migratory species, state protected species, and ha bitat 

conservati on . Tangible benefits have accrued to bot h wil dlife and FPL 

and will be reviewed in thi s paper . 

DISCUSSION 

West Ind i an Mana t ee 

The West Indi an manatee is an endangered mari ne mammal that FPL 

has inter acted with extensivel y over t he last 10 ye ars. Because of the 

intolerance of the species to water temper atures be l ow 190C, the animal 

has sought the once-through thermal discharges of five FPL plants along 

t he east and we st coasts of Fl orida . In regu l atory proceedings before 

the Environmen tal Protection Agency (EPA) , thi s speci es constituted a key 

f ac t or in t he permitting review. Because of t he En dangered Species Act, 

EPA wa s requ ired to consult with , the U.S. Fish and Wildl ife Service 

(US FWS) to i nsure that the "permitt ed activities would not likely 

jeopardize the cont i nued existence of an endangered spec i es" . 

Ut il i zat i on of t he thermal discharge by manatees was one of the 

factors that i nfl uenced EPA to 1 et FPL continue operat i ng in the oncethrough cooling mode , instead of off stream by add ing cooling towers. 

Taken to wo rst case extremes, this decision saved the Company and its 

rate payers approximately $300 million at two power pl ants. As part of 

the consultation in this regulatory process, FPL and USFWS decided that 

not enough was known about the interaction of man atees and power plants. 

To mit igate any impact on the manatee from thi s reg ulatory decision, FPL 

372 
agreed to conduct two manatee programs: an aeri a 1 census program and a 

publ ic awareness program. The aerial program ha continued on a yearly 

basis si nce 1977 (Reynolds and Wilcox, 1986). 

Benefits have accrued to the resource and the company fr om these 

aeri a 1 surveys. The primary benefit for the manatee is sci ent ifi c data 

on which to base conservation and management efforts. These counts were, 

in part, t he basis for rai sing the official estimate of animals in the 

population and identi fying specific areas for boat speed limits. 

Tangible and intangibl e benefits to the company incl ude: national and 

state recognition for FPL' s manatee conservation efforts, information to 

help schedule maintenance outages of units without impact to manatees, 

and scienti fi c data to support permi t renewal or issuance . 

As another facet of mitigation, the Company agreed to initiate a 

pub 1 i c awareness program for manatee s. FPL has sponsored or conducted 

these publi c awa reness programs yearly since 1977 directly reaching over 

10,000 people. As an offshoot of this public awareness effort, FPL has 

distributed over 530,000 pieces of literature on manatee conservation to 

the public. 

Tangible and intangible benefits have also acc rued to the resource 

and the Company from the 1 i terature and the pub 1 i c awareness programs. 

For instance, the public is more aware of t he plight of the manatee, and 

many people will go out of their way to help an inj ured manatee or will 

respect boat speed limits in manatee sanctuaries. Each piece of 

literature di stributed has FPL's name on it, even though it is 

unobtrusive. However, it is still a tangibl e expre ssi on to the publ ic 

and FPL's ray payer about FPL's commitment t o the envi ronment. 

Personnel of the Riviera plant located near West Palm Beach have 

developed an innovative method to provide warm-water effluent to 

manatees. Because the two units that have traditionally attracted the 

animal are no l onger operational, plant personnel dev ised a method to 

Siphon heated effluent from two other operational units into a basin that 

the manatee favor. Based on the successful demon st ration of a temporary 

and small si phon in 1984, personnel installed two 30 cm diameter siphons, 

one for each operati ona 1 unit at the plant. The siphons intercept a 

small portion (1%) of the heated effluent from the units before it is 

373 
di scharged into Lake Worth. Thus, a small but sufficient amount of 

heated effluent is diverted from an area not favored by the manatees to a 

basin adjacent to the plant that the animals have traditionally favored. 

This mitigation scheme has been successful because subsequent 

aerial surveys documented heavy use of this basin with more than 200 

manatees being observed du ri ng several cold fronts. Since each uni t has 

a siphon and one or both units are operat ing almost continuously and 

always during cold \tJeather, manatees will have a cont inuing source of 

warm water to assist their survival. 

Another example of impact mit igat i on for manatees occurr ed at 

FPL ' s Ft. Myers plant i n January 1985. Because the un its were not 

operat i ng for vari ous reasons, the Company was faced with a s i tuat ion 

where no warm effl uent was ava i1 ab 1 e t o aggregat i ng manatees that had 

traditionally been conditi oned to this discharge (Packard et al., 1985). 

A paradox arose: doe s FPL operat e a generat i ng unit just to keep 

manatees warm? 

As ambient water temperature cooled during this January an-d 

approached 1 eve 1 s that woul d stress manatees, senior management, state 

and federal officials, field bi ologists, and meteorologists were 

consulted. Due to a severe cold front, Unit 1 was dispatched to meet 

record electrical demand fo r three days. Over 100 manatees that had 

aggregated in a deep but warmer pocket of water nearby immediately found 

the warm-water discharge and stayed in the di scharge canal. After the 

di ssipation of the cold front and as electrical demand abated, the 

Company faced another paradox: does the un it shut down for economi c 

reasons and subject more t han 100 manatees to stressful if not harmful 

water temperatures? 

After much discussion with senior management and with their 

agreement , the unit was operated for 11 days out of economics (e.g., FPL 

cou ld have produced electri city cheaper at another plant) during the 

months of January and February. The sole reason to operate the plant was 

to enhance the survival of manatees. 

Senior management consented to operate the plant during this 

critical period only on the condition that they would not be asked to do 

374 
it again. Therefore, an al t ernative method to prov ide a thermal 

discharge to manatees was needed. 

After much discussion and evaluati on, FPL dec ided to tap ground 

water under artesi an pressure. A series of three 25 cm diameter wells 

were drilled up to 260 m depth . The ground water temperat ure was 230C, 

and with a pumped fl ow of 3800 l/min , an area of approximately 2 hectares 

would be provided as a warm-water refuge for the manatees. 

Even though the cost of the manatee protection wells was nearly 

$500, 000 , there was a net benefit to the Company, because the power 

plants could now operate on economi c dispatch instead of "manatee 

dispatch". The benefit to the manatees is the mai ntenance of a 

traditional refuge t hat more than 300 animals seek. 

Sea Turtles 

Fl ori da Power & Light Company has interacted with endangered or 

threatened sea t urtles over the last ten years, pri ma ril y at the st. 

Lucie plant on the eastern coast of central Fl orida. The species 

include: green (endangered in Florida); leatherback (endangered); Kemp's 

ridl ey (endangered) ; Hawksbill (endangered); and the loggerhead 

(threatened). The green, leatherback, and loggerhead nest on FPL 

beaches, while the Hawksbill and Kemp's ri dley only occur in the coastal 

waters of the area . 

The Comp any has actively participated in mitigation and 

envi ronmenta 1 enhancement for sea turtles with a vari ety of programs. 

Some programs have been driven by the regulatory process, and some have 

been voluntary. Because of dual regulatory jurisdiction for sea turtles, 

the National Marine Fisheries Service (NMFS), which has jurisdiction over 

sea turtles in the water, and the USFWS, which ha s jurisdiction over sea 

turtles while on beaches, extensive coordination was required. 

Additionally, the Nuclear Regulatory Commission and the EPA were also 

involved in sea t urtle concerns at t he St. Lucie Plant . 

When the st. Lucie Unit 1 became operational in 1976, several 

loggerhead turtles were unexpectedly taken from the intake canal of the 

plant. The turtles had entered the ocean intake structures and traveled 

through a seri es of 1 arge underground cul verts to an open canal, where 

375 
they became entrapped. The details of this ent~apment are reviewed in 

Ernest et al. (1987). 

For all practical purposes, the st. Luc ie units operate as a 

turtle trap. During this process, some animals are injured or killed. 

As mitigation for this "take" of a protected species, FPL tags the 

turtles and obtains a variety of biological information, which includes: 

blood samples, morphometric data, past injuries, present heal t h, and 

recapture data. This data base is available to all that request it and 

ha s been used extensively for federal, state, and university research 

programs. All this has benefited the conservation and scientific 

understanding of the resource. 

The benefit to FPL is the ability to operat e a key facility within 

the 1 imits of the law and with the concurrence and understanding of 

federal and state agencies. The cost to physically exclude turtles from 

the St. Lucie plant was estimated at $200 mil lion for a one-time capital 

cost and a yearly maintenance cost of $1 mill ion, while the cost to 

remove entrapped turtl es is $500, OOO/year. Other forms of excl usi on, 

including sound and visual stimuli, were investigated in a research 

program and were found to be impractical (O'Hara and Wilcox, 1984). 

Another aspect of mit i gat i on and env i ronmenta 1 enhancement deals 

with FPL's documentation of sea turtle nesting on the beaches of the St . 

Lucie Plant. This program has been conducted since 1971 and is ongoing. 

During the turtle nesting season of May through September, FPL conducts 

daily nesting surveys on 36 km of beaches to document nest numbers and 

distribution. Details and results of this program are documented in 

Gallagher et al. (1972), Worth and Smith (1976), Williams-Walls et al. 

(1983), and Proffitt et al. (1986). 

This program has generated one of the most comprehensive and 

extensive data bases on nesting sea turtles in Florida. Benefits to the 

resource include knowl edge for each species of sea turtle concerning 

intra-seasonal nesting intervals; inter-seasonal nesting cycles; nest and 

hatchling success; predation; and natural and human impacts on nesting. 

Benefits to the Company include demonstration that past construction 

impacts on the beach have been temporary and not permanent and that the 

thermal discharges from the plants have no impact on the nesting of sea 

376 
turtles or the survival of their hatchlings (O'Hara , 1980) . This 

knowl edge has expedited the renewal or issuance of federal and state 

permits. 

One impact on sea turtl e behavior ident if ied in the permit review 

process was the effect of plant security l ighting had on hatchling 

orientation and thei r return t o the water. To mitigate thi s impact, FPL 

has minimized beach 1 ighting and , whe re it could not be reduced, has 

established a light screen with vegetation to minimize this 

disorientat ion problem. 

As a continuing effort to demonstrate the Company's commi tment to 

the env ironment and to vol untari ly mi tigate any impact from beach 

1 ighting in general, FPL ha produced a bumper sti cker and poster to 

promote awareness of t urtle hatchling disorientati on and what the general 

public can do about this probl em. Addit ionally, the company has produced 

and distribut ed a bill insert promoting this awareness of hatchling 

disorientat ion to FPL customers on the east coast of Florida. By 

promot i ng thi s awareness, the re source is benefited and FPL is 

established as hav ing an environmental conscience. 

Another form of voluntary miti gat ion invol ve s the turtle walks 

that the Company provides as a public servi ce . Organized and guided 

tours to view a female sea turtle crawl up on the beach to lay her eggs 

are very popular nature experiences during June and July; FPL has 

conducted these walks since 1983. Re servations, which are required, can 

be made through FPL , and the walks are conducted on FPL property in the 

shadow of a nuclear power plant. FPL staff conduct an orientation 

program about sea turtle biology and con servat i on pri or to the actual 

walk. FPL produced public awareness materials on sea turtles; these 

materials are distri buted at the wa lks and to the general public. 

Approximately 80, 000 sea turtle bookl ets have been distributed through 

these and other public awareness programs. 

Agai n, the resource is benefited because the ins atiable appetite 

of the public to view sea turtles nesting is being channelized in a 

constructive and beneficial program, while FPL is demonstrating the 

compatibility of our facilities with sea turtles and the Company's 

environmental commitment. 

377 
American Crocodile 

Fl ori da Power & Light Company interact i on wi th the endangered 

American crocodile dates to 1976 when hatchlings were first discovered in 

the cool ing canal system of the Turkey Point Plant. The plant is located 

60 km south of Miami and produces electricity with fossil and nuclear 

units. Subsequent monitoring (i.e., a form of voluntary mitigation) 

outside the regulatory or permitting arena establ ished that a small but 

viable crocodil e population inhabits the site, all of which has been 

designated by the USFWS as critical habitat. Details and results of this 

monitori ng program are given in Gaby et al . (1985) and Masotti et al. 

(1986). 

Th is mon itori ng program benefited the resource because it 

established the dynamics of the population , recruitment of animal s into 

the next size class, the behavior of animals, and how they partitioned 

the environment . All this is useful data . These studies also benefited 

the Company during federal l icensing activities of the nuclear units. As 

with many nuclear issue s, intervenors use all types of strategies to 

prevent or delay this 1 icensi ng and crocodiles became an intervention 

issue. However, because of the extensive data base on crocodiles 

developed during the monitoring program, the Company was able to easily 

answe r any interrogatori es and a $200 mil lion project was not blocked or 

delayed. 

In 1984, the Company i ni t i ated a maintenance program to remove 

exotic trees and to clean cooling canals of accumulating spoil . To 

mitigate any impacts of these activities, a crocodile management plan was 

drafted and reviewed by all affected FPL Departments. By knowing the 

behavior and 1 ife requirements of the animals, a sensible maintenance 

schedule wa s established that allows the animals to nest in certain areas 

while allowing maintenance dredging in areas not inhabited or utilized by 

the animals. Thus, both the resources and the Company benefited. 

As a voluntary mitigative effort, the Company developed a public 

awareness booklet on Florida's alligators and crocodiles. This booklet 

promotes a better understanding of the animals and is another example of 

FPL's commitment to the environment. 

378 
Southern Bald Eagle 

Fl orida Power & Light Company has mon itored nesting of the 

southern bald eagle around company facilities over a four-year period. 

The purpose of this monitoring program was to insure the compatibility of 

company operati ons or construction and the well-being of an endangered 

species. Details and results of the program are gi ven in Williams-Walls 

(1986). 

This mo nitori ng program verifi ed the mitigation policies 

established by the U.S. Fish & Wildlife Service for eagle nest ing (USFWS, 

1987). The service recommended two buffer zones around an active eagle's 

nest and the level of human activities that wou ld not disturb the pair of 

eagles. 

With prior knowledge of th is miti gation policy, the company was 

able to construct a 500 kV switchyard and a tower structure for another 

500 kV line that was within the outer buffer zone establi shed by the 

service. Land clearing and tower erection requirements were established 

and incorporated in the planning and subsequent construction schedule. 

Activities were timed so that the eagles and their nesting activities 

were not impacted duri ng the construction phase. Subsequent monitoring 

of the operating l ines demonstrated no impact. Similarly, no impacts 

were observed on eagle nesting from t he operation of nearby power plants. 

Proper timing of activities benefited the resource, and the Company was 

able to obtain fede ral and state permits to construct a switchyard and 

transmission facil ity without delay . 

Barley Barber Swamp 

In 1972, FPL purchased app roximately 3,650 hectares of land for 

the Martin Power Plant and a cooling reservoir near Lake Okeechobee. 

During planning stages for the cooling reservoir, a unique cypress strand 

known as the Ba rley Barber Swamp was singled out as worthy of 

preservation. In consul tati on with several state agencies, approximately 

160 hectares of the swamp were preserved by buil di ng the 1 evy of the 

cooling reservoir around t he area. 

379 
Through environmental mon i toring, the uniqueness of the swamp 

became more and more apparent . A group of cypress trees over 400 years 

ol d were i dent ifi ed as we 11 as a rookery ay'ea of the endangered 

woodstor k. Other important species observed i nclude southern bald eagles 

(endangered) and ind igo sna ke s (threatened) . 

To demonstrat e the compat i bil ity of the swamp with the Mart i n 

Plant , the Company constructed a 2. 2 km long boardwal k through the heart 

of t he swamp and opened it to vi s itors by appo i ntment. The boardwalk , 

completed in 1980 , offers visitors a un ique opportunity t o view a 

prist i ne wetl and and upland commu nity as it may have exi sted before the 

vast land alterations and wa ter control efforts of the last 100 years . 

To f urt her enhance t he functioning of this un ique area, a series of 

management and enhancement pl ans were drawn up and implemented with 

expert help . These plans call ed for channel i zi ng wate r into t he swamp 

from reservoir seepage sumps to simul ate sheet flow; manipul at ion of 

water l evel s to simul ate hydroperi ods for t he we t and dry season; 

cont roll ed burns to mai ntain certa in areas in specific stages of 

ecol ogi cal succession; and efforts t o cont rol exotic vegetation. The 

management plan r ecommended that several 300- 500 year old Indian mou nds 

adjacent to t he swamp be preserved and checked fo r archeological 

significance. 

The benefits to the resource are overwhelming. Not only have 

eagl es and woodstorks nest ed intermi ttentl y in the swamp, but over 150 

species of bi rds have been identified in or around the swamp. Species 

1 i sts for mammal s and rept il es are also extens i ve. Twenty spec i es of 

f erns and six species of orchids have been identified, as well as over 

200 species of wildflowers, plants and t rees. 

The benefits to t he Company are also overwhelming. Since the 

openi ng of the boardwalk, over 12,000 vi si tors from 30 states and eight 

fore ign countries have t oured the swamp by appointment through FPL . 

These visitors have been fo r themselves how a power plant can operate 3 

km away and yet be compatibl e with the resource. Many of the visitors 

touring the swamp are from conservati on organizations, such as the 

Au dubon Society, Sierra Club , and Na t ive Pl ant Society. The swamp has 

proven to be so popular with t hese organizations that they plan seasonal 

380 
tours to observe changes in the flora and fauna . The significance of all 

these contacts is that our customers and the pub 1 i c can observe FPL' s 

tang ible concerns for the environment. 

CONCLUSIONS 

As the examp les demonstrate, mitigation and environmental 

enhancement do work and benefi t both the resource and private industry. 

Utility management may have difficulty justifyi ng and accepting the costs 

for the program cited , but it is up to the util ity biolog ist or a similar 

counterpart to point out the tangible and intangi ble benefits to the 

Company. 

As part of FPL' s Qual i ty Improvement Program, sen i or management 

have adopted the fol lowi ng Corporate Vision: "During the next decade, we 

want to become the best managed el ectric utility i n the United States and 

an excellent company overall and be recognized as such.". 

In 1984, the Company received the Conservation Service Award , the 

highest award given by the Department of Interior to a private 

organization, for the Company's work on endangered species. Likewise, in 

1986 the Florida Audubon Society recognized the Company by presenting the 

Corporate Conservation Award for promoting public awareness and 

protection of Flori da' s endangered species. 

This state and national recognition is evidence that Florida Power 

& Light Company programs are i nnov ati ve , forward looking, and an accepted 

means to promote mitigation and environmental enhancement. Instead of 

fighting the system, why not use your professional skills as biologists, 

engineers, and managers and work wi th t he system in order to benefit both 

the resource and t he business community alike? 

381 
LITERATURE CITED 

Ernest, R.G., R. E. Martin, B.D. Peery, D.G. Strom, J.R. Wilcox, and N.W. 

Walls. 1987. Sea turtle entrapment at il coastal power plant. 

Proc. SE Workshop Aquatic Ecol. Effects Power Generation. 

Gaby, R., M.P. McMahon, F.J. Mazzotti, W.N. Gillies and J.R. Wilcox . 1985. Ecology of a population of Crocody1us acutus at a powe r 

plant site in Florida. J. Herp. 19:189-198. 

Gallagher, R.M., M.L. Hollinger, R.M. Ingle, and C.R. Futch. 1972. Marine 

turtle nesting on Hutchinson Island, Florida in 1971. Fla. Dept. 

Nat. Resour., Mar. Res. Lab. Spec . Sci. Rept. No. 37:1-11. 

Mazzotti, F.J., B. Bohnsack, M. P. McMahon and J.R. Wilcox . 1986. Field 

and laboratory observat ions on the effects of high temperature and 

salinity on hatchling Crocody1us acutus. Herpeto10gica 42:191-

196. 

Morgenthaler, E. 1987. Ecology effort: a Florida util ity win s 

naturalists' praise for guarding wildlife. The Wall Street Journal 

May 7:1 (col. 6),19 (col. 1-3). 

O'Hara, J. 1980. Thermal effluences on the swimming speed of l oggerhead 

turtle hatchlings. Copeia 4:773-780. 

O' Hara, J. and J.R. Wilcox. 1984. Seismic exploration air guns as a tool 

for sea turtle deterence. Vol . 1. p. 276-277, In: F. Bacon, K. 

Berry, K. Bjornda 1, H. Hi rth, L. Ogren, M. Weber (eds.). Proc. 

Western Atlantic Turtle Symp. , RSMAS Printing, Miami. 

Packard, J.M., R.K. Froh lich, J.E. Reynol ds, II I, and J.R. Wilcox. 1985. 

Manatee response to i nterrupted operation of the Fort Myers power 

plant, winter 1984/1985. Manatee Pop. Res. Rept. No.8, Tech. 

Rept. No. 8-8. Fla . Coop. Fish & Wildl. Res. Unit, Univ. of Fla., 

Gainesville, FL. 20 p. 

Proffitt, C.E., R.E. Martin, R.G., Ernest, B.J. Graunke, S.E. LeCroy, 

K.A. Muldoon, B.D. Perry, J.R. Wilcox, N. Williams-Walls. 1986. 

Effects of power plant construction and operation on the nesting 

of the loggerhead sea turtle (Caretta caretta), 1971-1984. Copeia 

3 :813-816. 

Reyno 1 ds, J. E., II I and J. R. Wil cox. 1986. Di stri but i on and abundance of 

the West Indian manatee (Trichechus manatus) around selected 

Florida power plants following winter cold fronts, 1984-1985. 

Bio1. Cons. 38:103-113. 

USFWS. 1987. Habitat management guidelines for the bald eagle in the 

Southeast region. U.S . Fish & Wi1d1. Ser., Region 4, 9 p. 

Wilcox, J.R. 1979. Flori da Power & Light Co. and endangered species: 

examples of coexistence. p. 451-454, In: G.A. Swanson (Tech. 

382 
Coord.) Rocky Mt. Forest and Range Exp. Sta., Gen. Tech. Rept. RM65. 

Wilcox, J.R. 1980. Endangered species: compatibility with a utility. p. 

179-185, In: B.L. Edge (ed.) Coastal Zone '80 , ASCE, Hollywood, 

FL. 

William-Walls, N., J. O'Hara, R.M. Gallagher, O.F. Worth, B.O. Peery, 

J.R. Wilcox . 1983. Spati al and temporal trends of sea turtle 

nesting on Hutchinson Island, Florida, 1971-1979. Bull. Mar. Sci. 

33:55-66. 

Will iam-Wa 11 s, N. , Productivity 

Florida bald 

52. 

s. McCuskey, W. Marion, J.R. Wilcox. 1986. 

and changes i n nest utilization in four central 

eagle nesting territories. Fla. Field Nat. 14(2):29-

Wood, O.A. 1986. Official list of endangered and potentially endangered 

fauna and flora in Florida. Fla. Game & Freshw. Fish Comm. 19 p. 

Worth, O.F. and J.B. Smith . 1976. Marine turtle nesting on Hutchinson 

Island, Florida in 1973. Fla. Mar. Res. Publ. No. 18:1-17. 

383 
WHEN ARE TEMPERING PUMPS AN EFFECTIVE BAT 

FOR MITIGATING THERMAL IMPACTS? 

Linda R. Cadman 

A. F. Holl and 

Stephen B. Weisberg 

Versar, Inc. 

ESM Operations 

9200 Rumsey Road 

Columbia, Maryland 21045 

ABSTRACT 

Thermal impacts of once-through cooling are sometimes mitigated by 

diluting thermal discharges with ambient water. However, decreased 

thermal effects are gained at the expense of increased entrainment 

through tempering pumps. A model to quantify this trade-off was applied 

to empirical data collected for t he Chalk Point Steam Electric Station in 

Maryland and tempering pumps were found to increase total mortality for 

representative species of fish and crabs. Sensitivity analysis of the 

model's assumptions and input parameter estimates substantiated the 

finding that tempering pumps were detrimental at Chalk Point. As a 

result of these analyses, the dec ision was made to discontinue their use. 

Further exami nat i on of model inputs suggest that temper; ng umps woul d 

only be effective at Chalk Point under a limited set of circumstances. 

These analyses demonstrate the need for evaluating the ecological costs 

in relation to anticipated benefits for any mitigative measure . 

384 
INTRODUCTI ON 

Sect ion 316(a ) of the Clean Water Act requ ires utilities t o comply 

with state and federal thermal effluent limitations or demonstrate that 

discharges do not adversel y affect balanced indigenous populat ions. One 

means used to meet thermal effluent limitati ons and reduce adverse 

thermal impacts is to l owe r the temperature of the di scharge water by 

diluting it with unheated water. Dilution occurs before the discharge is 

returned to the receivi ng water body and is accomp lished by large pumps 

(referred to as tempering or diluti on pumps) that transport water from 

the intake area to t he disch arge area. 

Temperi ng pump s, however, increase a fac il ity ' s total water 

wi thdrawa 1 rate. The increase in water wi thdrawa 1 rate produces an 

increase in t he number of organisms suscept ibl e t o impingement and 

entrainment. Therefore , decreased t hermal impacts are gained at the 

expense of hi gher impi ngement and entrainment must be evaluated before 

the effect i veness of temperi ng pumps as a mit i gat i ve technology can be 

assessed . 

In 1967, tempering pump operat ion was initi ated at t he Chalk Point 

Steam Electric Station · (SES) to mitigate thermal impacts . At the time, 

no analysis of the adverse impacts of increased entrainment was 

conducted. In 1985, we developed a simpl e mode l fo r evaluating the 

trade -offs be tween reduced di scharge t emperature and increased 

entrainment losses associated with tempering pumps. Thi s model was used 

to estimate re lat ive increases or decreases in total 'plant-induced 

mortality due to tempering pump operat ion at Chalk Point . 

METHODS 

Study Site 

The Chalk Poi nt SES, located i n the estuarine port ion of the Patuxent 

River, Maryland, uses 30 m3 of water per second fo r once-through cooling . 

Cooling water is withdrawn from a 137-m-long i nt ake canal and returned to 

the Patuxent River 2 km up st ream from t he plant via an 18-m-wide 

discharge canal (Fi gure 1). Intake struct ures are protected by a barrier 

net, a trash rack, and traveling screens. Organisms entrained or 

impinged at the pl an t are wa shed into the discharge canal. Transit time 

for a passive parti cl e through t he discharge canal is 2-4 hours (Academy 

385 
(DOWNR IVER) 

( 

INTAKE CANAL 

) 

) 

UNIT UNIT 

2 1 

D D 

INT AKE SCREENS 

J J 

+----+SCREEN-WASH 

RETURN 

DISCHARGE CANAL (UPRIVER) 

) 

Figu re 1. Top view schematic of intake and discharge systems at Chalk 

Point Steam Electric Station, Patuxent River, Maryland (from 

Hirshfield et al, 1982). --

386 
of Natural Sciences of Philadelphia , 1983). Temperature at the head of 

the discharge is as much as 200 Chi gher than the intake temperature 

(Mart in Marietta Environmental Systems, 1985). The average ~T during the 

summe r is 7.40C. 

From 1969 to 1985, three tempering pumps, each with a pumping 

capacity of about 5 m3 sec-I, were used t o pump water directly from the 

recei vi ng water body to the discharge canal from June to September. 

Ope rat i on of all three temperi ng pumps reduced the t emperature at the 

head of the discharge canal by about 2.70C and by less than 0.50C in the 

nearfield (Academy of Natural Sciences of PHiladelphia, 1983) . 

Analytical Approach 

The general app roach used to eval uate the effect iveness of tempering 

pumps involved identification of all sources of power plant-induced 

mortal i ty and compari son of total mortal i ty \'Ii th and wi thout temperi ng 

pump operation . The generali zed model was of the form: 

Total Pl ant- Induced 

Mortality 

Intake Screen 

Impi ngement 

Mortality 

Tempering 

Pump 

Entrainment 

+ 

+ Mortality + 

Circulating 

System 

En trainment 

Mortal ity + 

Nea rfield 

Mo rtal ity 

Tempering 

Pump 

Impingement 

Morta 1 ity 

The effectiveness of tempering pumps at Chalk Point SES was evaluated 

by comparing estimates of mortali ty for four important fish species and 

blue crabs wi th and without tempering pump operation. 

Each impingement and entra inment term i ncludes mortality directly due 

to the process of impingement or entrainment plus the mortality of 

surviving organ isms caused by thermal or chemi cal stress in the 

discharge. Nearfi eld mortality is defined as morta lity of organisms 

residing in the nearfield area t hat is caused by t hermal or chemical 

stress induced by the discharge effluent. 

When the model was applied to Chalk Poi nt, several terms in the model 

were not included because they we re not al tered substantially by 

tempering pump operation; they we re, in effect, constants. These sources 

of mortality were unnecessary for the analysis since the objective was 

not to estimate total mortal ity but to dete rmi ne the difference in 

387 
morta 1 i ty between the two operat i ng modes. The components not included 

in the analysis for Chalk Point were circulati lg system entra inment, 

tempering pump impingement, and discharge effects on organisms residing 

in the nearfield. 

The term for circulating system entrainment mortality was not 

included because it approaches 100% due to continuous chlorination during 

t he summer when tempering pumps are used (Martin Marietta Environmental 

Systems, 1985) . This mortality rate is unaltered by operation of 

tempering pumps since entrained organisms are dead before they reach the 

discharge canal where the temperature reduct i on due to d il ut i on occurs 

(Martin Marietta Environmental Systems, 1985). 

Temperi ng pumps at Chalk Point are unscreened. Thus, temperi ng pump 

imp i ngement mortal i ty is zero and th is term was not included in the 

analysis for Chalk Point. However, larger organisms that would normally 

be impinged were entrained through the tempering pumps. 

Discharge effects in the receiving water body were not included in 

applicat ion of the model to the Chalk Point SES because neither chlorine 

nor thermal conditions in the nearfield are altered greatly by operation 

of the tempering pumps. Total residual chlorine (TRC) concentrations at 

the head of the di scharge canal have hi stori cally been 1 ess than 0.20 

mg/l and essentially no TRC is discharged to the receiving water body 

(Academy of Natural Sciences of Philadelphia, 1983). Further, 

hydrographic model simulations predicted that the ~T in the nearfield is 

not substantially altered by tempering pump operation. The 1 argest 

reduction in ~T anywhere in the receiving water body due to tempering 

pumps was less than 0.50C (Academy of Natural Sciences of Philadelphia, 

1983) . 

Aft er deleting the sources of mortality that are unaffected by 

temperi ng pump operation, the formula applied at Chalk Point SES was 

reduced t o two sources: 

PlantInduced 

Mortal ity 

Intake Screen 

Impingement 

Mortal ity + 

Tempering Pump 

Entrainment 

Mortality 

Imp i ngement losses were calculated as the sum of immediate mortality 

associ at ed with the mechanical stresses of impingement plus the 

addit ional mortality due to thermal stress when the organisms are wished 

into the discharge canal (Table 1). IlOO1ediate impingement losses were 

388 
Table 1o Mortality components used in the analysis of 

tempering pump effectiveness at Chalk Point SES 

Intake Screen Tempering Pump 

Impingement Mortality Entrainment Mortality -

Thermal Thermal 

Immediate Component Immediate Component 

5 5 

Tempering AOS A(l-S) I: EtF t CoO C(l-O) I: EtF t 

Pumps t=l t=l 

On 

5 

Tempering AOS A(l-S) I: E G t t - - Pumps 

Off 

where 

t=l 

A = number impinged on intake screens 

S = immediate impingement mortality rate 

C = number entrained through the tempering pumps 

o = immediate entrainment mortality rate 

Et = thermal mortality rate in temperature interval t 

Ft = proportion of time the discharge temperature w.s in 

temperature interval t based on diluted discharge 

temperatures 

Gt = proportion of time the discharge temperature was 

in temperature interval t based on undiluted 

discharge temperatures 

389 
calculated by multiplying the total number of a species impinged during 

June through September by the immediate impingement mortality ra t e for 

eac h species. Similarly, tempering pump entrainment losses were 

calculated as the sum of immediate mortality due to mechanical stresses 

associated with entrainment through tempering pumps plus the additional 

mortality due to thermal stress when surviving organisms are washed into 

t he discharge canal. Temperi ng pump entrainment mortality was calculated 

as the product of the total number entrained during June through 

September and the immediate entrainment mortal ity rate. 

these parameters for Cha l k Point (Table 2) were taken from 

li (1982) . 

Estimates of 

Hirshfield et 

The t hermal mortal ity component of both impingement and tempering 

pump entrainment was computed by multiplying the number of organisms that 

surv ived entrainment and impingement by the expected mortality rate due 

to thermal stresses in the discharge canal. The expected thermal 

mortal ity rate was calculated using therma l tolerance data obtained from 

the literature. Lethal temperatures (LT) were obtained for a range of 

acclimation temperatures for each species evaluated. Temperatures for 0, 

50, and 100 percent thermal mortality (i.e. , LTO, LT50' and LT100) were 

determined based on available literature estimates and values for LT25 

and LT75 were estimated by linear interpolation. To estimate the average 

thermal mortality rate for the summer months, the expected percent 

mo rta 1 ity for each temperature i nterva 1 (e. g., between the L T 25 and the 

LT50 ) was weighted by the of time the discharge temperature was in that 

temperature interval. The frequency distribution of discharge temperature 

over t ime was determined from monitoring studies conducted in the 

discharge. 

An organism's temperature tolerance depends on its thermal history, 

and therefore our model was run twice assuming different accl imation 

tempe ratures: 170C and 320C. Intake temperature at Chalk Point during the 

study period ranged from 170 to 320C. Thermal mortality was minimized by 

assuming that the organisms impinged or entrained at the plant were 

accli mated to 320C for the entire study period. Similarly, thermal 

mo rt ality was maximized by assuming that the organisms were acclimated to 

17oC. Parameter values used for estimating thermal mortality for each 

species and acclimation are given in Tables 3 through 6. 

390 
Table 2. Impingement and entrainment parameter values used 

to estimate mortality at Chalk Point SES with and 

without tempering pumps operating 

Blue White Striped 

Parameter Crab Perch Bass Spot 

Number impinged 180,224 11,722 4,762 25,744 

Impingement 

mortality rate 10.0% 19.0% 33.0% 36.0% 

Number entrained 80,307 76,773 3,348 37,286 

Entrainment 

mortality rate 41. 8% 69.7% 69.7% 91. 0% 

391 
Table 3. Parameter values used to estimate blue crab 

thermal mortality at Chalk Point SES with an d 

without tempering pumps operating 

Proportion of Time Spen t 

in Interval t 

!Temperature Mortality 

Interval t Rate Pumps On Pump s Off 

ACClimationl ( • C) 

I 

(E t ) 

I 

(F t ) (G t ) 

<34.0 0.00 0.622 0 .4 54 

34.0-35.0 0.25 0.032 0 .06 0 

LOW 35.0-36.0 0. 50 0.067 0. 0 48 

36.0-36.5 0.75 0.047 0 .0 35 

>36.5 1. 00 0.23 2 0 . 403 

<37.0 0 .00 0.819 0. 63 2 

37.0-38.0 0.25 0.044 0 .0 3:'> 

HIGH 38.0-39.0 0.50 0.04 1 0 . 09 2 

39.0-39.5 0.75 0.003 0. 060 

>39.5 1. 00 0.092 O. 131 

•. ,4 

392 
Table 4. Parameter values used to estimate white perch 

thermal mortality at Chalk Point SES with and 

without tempering pumps operating 

Acclimation 

LOW 

HIGH 

Temperature Mortality 

Interval t Rate 

(OC) (E t ) 

<25.0 

25.0-26.5 

I 26.5-28.0 I 

28.0-29.0 

>29.0 

<34.0 

34.0-35.5 

35.5-37.0 

37.0-37.5 

>37.5 

0.00 

0.25 

0.50 

0.75 

1. 00 

0.00 

0.25 

0.50 

0.75 

1. 00 

393 

IProportion of Time Spent 

in Interval t 

Pumps On 

I (F t) 

0.054 

0.079 

I 0.130 

O. ·07 3 

0.057 

0.140 

0.016 

0.165 

Pumps Off 

(G t ) 

0.010 

0.016 

0.044 

0.054 

0.876 

0.454 

0.070 

0.108 

0.022 

0.346 
Table 5. Parameter values used to estimate striped bass 

thermal mortality at Chalk Point SES with and 

without tempering pumps operating 

Proportion of Time Spent 

1.n Interval t 

TemperaturelMortality 

Interval t Rate Pumps On 

Acclimation (OC) (E t ) (F t ) 

Pumps Off 

. (G t ) 

LOW 

HIGH 

<27.0 

27.0-28.0 

I 28.0-29.0 I 

29.0-30.0 

>30.0 

<33.0 

I 33.0-34.5 I 

34.5-36.0 

36.0-37.5 

>37.5 

0.00 

0.25 

0.50 

0.75 

1. 00 

0.00 

0.25 

0.50 

0.75 

1. 00 

394 

0.181 

0.083 

I 0.073 

0.038 

0.625 

0.549 

I 0.083 

0.089 

0.114 

0.165 

0.038 

0.032 

0.054 

0.092 

0.784 

0.406 

0.083 

0.073 

0.092 

0.346 
Table 6. Parameter values used to estimate spot thermal 

mortality at Chalk Point SES with and without 

tempering pumps operating 

Temperature Mortality 

Interval t Rate 

Acclimation (OC) (E t ) 

<27.0 0.00 

27.0-29.0 0.25 

LOW 29.0-31.0 0.50 

31.0-32.0 0.75 

>32.0 1. 00 

<33.0 0.00 

33.0-34.5 0.25 

HIGH 34.5-36.0 0.50 

36.0-37.0 0.75 

>37.0 1.00 

395 

Iproportion of Time Spent 

in Interval t 

Pumps On 

(Ft ) 

0.181 

0.155 

0.102 

0.051 

0.511 

0.549 

0.083 

0.089 

0.098 

0.181 

Pumps Off 

(G t ) 

0.038 

0.086 

0.143 

0.070 

0.663 

0.406 

0.083 

0.073 

0.070 

0.368 
RESULTS AND DISCUSSION 

Tempering pumps at Chalk Point SES were not only found to be 

ineffective, but they actually increased total .mortality of fish and 

crabs . The estimated mortality for the four representative species was 

18 t o 90% higher with temperi ng pumps operating than without the pumps 

operating (Table 7). 

The conclusion that tempering pumps are detrimental rather than 

beneficial to the Patuxent River ecosystem was substantiated by 

sensitivity analys is of the model to input parameters. For example, 

immedi ate impingement mortality rate can range from 0 to 100%. Analyses 

ind icated that altering impingement mortality rate alone did not change 

the outcome of the model. That is, even if all organisms surv ived the 

mechanical stress of impingement, t empering pumps at Chalk Point would 

st ill increase total mortality of the representative species. Similar 

results were found when immediate entrainment mortality was varied 

between a and 100%, with one exception. If the blue cr ab mortality due 

directly to being entra ined through the tempering pumps is very low (less 

tha 22% for the high accl imat ion scenari o and l ess than 3% for the l ow 

acclimation scenario), then tempering pump s wo ul d reduce mortality of 

blue crabs. However, at Chalk Point, it is unlikely that pump 

entrainment mortal ity would even be thi s l ow . The on-site estimate of 

immediate mo rtality for entrained blue cr abs was 41.8% (Potomac El ectric 

Powe r Company , 1984) . If delayed mort ality had been inc l uded in this 

estimate, t he mortality estimate would have been even higher . 

The eff ect of varying the .1T reduction caused by the tempering pumps 

was also examined. For the representative fish, altering the .1 T up to 

10.00C did not change the outcome of the analyses (assuming t hat 

nearfield effects remain relat ively unchanged) . Even a 10.0oC decline in 

discharge t emperature woul d not decrease thermal mortality enough to 

offset the increased mortal ity due to tempering pump entrainment. For 

blue crabs , however, losses wou l d be l ower if the reduction in discharge 

t emperature resulting from pump operation was greater than 4. 50C. To 

r educe the discharge temperatur e at Chalk Point by 4.SoC would require 

t he pump; ng of about 46% more dil ut i on water than is currently pumped . 

This would greatly increase the number of organisms entrained through 

temper; ng pumps. Therefor e, it is un 1 ike 1 y that any errors in the 

396 
Table 7. Estimates of mortality at Chalk Point SES with and 

without tempering pumps operating 

Mortality Estimate 

Percent 

Species Acclimation Pumps On Pumps Off Difference 

Blue Crabs Low 116,097 93,974 19.1 

High 77,957 63,593 I 18.4 

White Perch Low 82,048 I 11,179 I 86.4 

High 64,291 6,349 90.1 

Striped Bass Low 6,895 4,405 36.1 

High 5,303 3,124 41.1 

Spot Low 55,868 22,593 59.6 

High 49,541 17,140 65.4 

I 

397 
parameter estimates used would alter the conclusion that tempering pumps 

at Chalk Point are detrimental. 

At Chalk Point, the general model for estimating changes in t otal 

mortality was reduced to two components -- tempering pump entrainment and 

intake screen impingement. The trade-off to be considered was simpl y 

reduction in thermal mortality of impinged organisms in the discharge 

canal versus the additional mortality due to tempering pump entrainmen t . 

The ana lysi s approach facilitated an evaluation of the trade -offs and t he 

conclusion from the Chalk Point SES seems clear. Tempering pumps are no t 

an acceptable technology for mitigating thermal effects because they 

actua l ly increase the number of organisms kil led by the plant . 

Although tempering pumps were ineffecti ve at Chalk Poi nt and a 

similar finding was made at the Big Bend faci l ity in Florida where 

operation of dilution pumps was discontinued (U .S. Environmental 

Protection Agency, 19B1) , there are situations where tempering pump s 

coul d be potentially useful for achieving compliance with t hermal 

st atutes or for mit i gat i on of thermal impacts. For instance, temperi ng 

pumps at Chalk Point do not reduce nearfield temperatures significantly; 

at facilities where the .iT in the nearfield is effectively reduced, 

tempering pumps are more likely to reduce total mortality . Similarl y, if 

migration routes of anadromous fish are blocked by a thermal plume , 

dilution pumping may reduce the size of the plume sufficiently to allow 

migration. In such a circumstance, it is possible that tempering pumps 

might still increase plant-induced mortality, but the benefit of open 

mi gration routes may be "worth" the cost of additional mortal ity to 

another l ife stage or species. 

Tempering pumps may also be useful for reducing cold shock associated 

with pl ant outages. When organi sms are attracted to el evated 

temperatures in a discharge, they are subject to cold shock mortal i ty if 

the plant shu ts down. Diluti on pumping may help reduce attraction to the 

discharge by reducing .iTs in the nearfield and thus the potential for 

cold shock mort ality. 

Any proposed mitigative measure, whether it directly mitigates an 

impact or ind irectly replaces a loss, has associated costs and benefits, 

and obviously both need t o be considered in the recommendation and 

dec ision -mak ing process. Hi stori call y, the approach to evaluating the 

39B 
costs and benefits of a technology to be applied for environmental 

reasons has been to consider only the economic costs (i .e., capital, 

operating, and maintenance costs) and the ecological benefits (e.g., 

reduction in a specific impact to be mitigated). The Chalk Point 

analysis has shown that it is of great importance that all ecological 

costs also be considered. In addition, it may also be necessary to 

evaluate the relative value of the ecological costs and benefits to 

facilitate evaluation of trade-offs. Finally, it is imperative that 

monitoring be conducted after a technology has been applied to confirm 

the predicted costs and benefits. 

ACKNOWLEDGEMENTS 

The study descri bed in thi s paper was supported by the Power Pl ant 

Research Program of the Maryland Department of Natural Resources 

(Contract Number P35-85-01) under the direction of Mr. James Teitt. 

LITERATURE CITED 

Academy of Natural Sciences of Philadelphia: Chalk Point station 316 

demonstration. Technical Reports. Vols. I-IV. Prepared by ANSP, 

Benedict Estuarine Research Laboratory, Benedict, MD, for Potomac 

Electric Power Co. (1983) 

Hirshfield, M.F., J.H. Hixon, III, and E.S. Perry: Chalk Point auxiliary 

pump study 1981. Report No. 82-3F. Prepared by Academy of Natural 

Sciences of Philadelphia, Philadelphia, PA, .for the Maryland 

Department of Natural Resources, Power Plant Siting Program. Ref. 

No. PPSP-CP-80-2. 

Martin Marietta Environmental Systems: Impact assessment report: Chalk 

Point steam electric station aquatic monitoring program. Prepared 

for Maryland Dept. of Natural Resources, Power Plant Siting Program. 

(1985) 

Potomac Electric and Power Company: 

auxiliary tempering pump entrainment 

Prepared by Environmental Affairs 

Department. (1983) 

Estimate of impingement and 

at the Chalk Point station. 

Group, Water and Land Use 

Potomac Electric and Power Company: Effects of auxiliary cooling pumps 

on survival of blue crabs (Callinectes sapidus Rathbun) in the Chalk 

Point station discharge canal. Environmental Affairs Group, Water 

and Land Use Dept. (1984) 

399 
u.s. Environmental Protection Agency: Tentative findings and 

determinations under 33 U.S.C. 1326 in the matter of Tampa Electric 

Company Big Bend Station, Tampa, Florida. 7pp. (1981) 

400 
EVALUATION OF FISH DIVERS ION EFFICIENCIES AND SURVIVAL 

AT THREE POWER PLANTS WITH ANGLED SCREEN INTAKES 

John A. Matousek 

Robert W. Davis 

Stephen J. Edwards· 

Lawler, Matusky & Skelly Engineers 

One Blue Hill Plaza, Pearl River, NY 10965, USA 

ABSTRACT 

Biological studies to evaluate angled screen intake systems were 

conducted at Niagara Mohawk Power Corporation's Oswego Steam Station Unit 6, a full-scale demonstration facility at Central Hudson 

Gas & Electric Corporation's Danskammer Point Generating Station, 

and New England Power Company's Brayton Point Generating Station 

Unit 4. These study sites are situated on three different waterbody types - lake, river/estuary , and marine bay, respectively - pennitting the evaluation of a large number of aquatic populations. 

The three studies were designed to detennine the effectiveness of 

the angled screens at diverting fish entrained with condenser cooling water from the intake as well as in itial and extended survival 

of the fish collected from the diversion flow. Experimental variables incorporated into the study design at one or more of the test 

sites included bypass velocity, ratio of bypass velocity to angled 

screen approach velocity, screen mesh size, residency and predation, recirculation, photoperiod, and angled screen wash cycle. 

Diversion efficiency ranged from 76% at Brayton Point to 99% at 

Danskammer POint, with seasonal, species, and age (length) variability noted. With the exception of bay anchovy at Brayton POint, 

initial survival was high for al l species. Extended survival evaluated for 96 h at Oswego and Danskammer Point and for 48 h at Brayton Point varied considerably. In general, two groups were identified at each site: a sensitive group composed of a few numerically 

domi nant speci es (mostly Cl upeiformes) that exhi bi ted hi gh 

postdiversion mortality and a hardy group (mixed species) with low 

postdiversion mortality. 

The three studies indicate that an angled screen intake system is a 

successful physical barrier for mitigating fish impingement, has a 

high guiding capability, and demonstrates high initial survival 

following passage through the diversion system. Extended survival 

varied, but overall there was reasonably good survival for all but 

a few sensitive species. 

*Present address: Environmental Services 

80 Sunny Ridge Road, Easton, CT 06612, USA 

401 
INTRODUCTION 

The amount of water used by industry each year, especially the nonconsumptive use by electric utilities for condenser cooling, rep resents a significant portion of the total fresh water availab le. 

Initially, problems associated with this kind of water use concerned thermal discharges and their potential to alter the nea rfield temperature cycle. Attention then shifted to the cooling 

water intakes and their potential for entraining small planktoni c 

organisms and entrapping larger organisms, with subsequent imp ingement on the intake traveling screens. 

At the same time, greater public awareness of the need to protect 

the environment resulted in the passage and implementation of the 

Federal Water Pollution Control Act of 1972 (Public Law 92-500) and 

the Clean Water Act amendments of 1977 (PL 95-217). This legislation features sections pertaining to cooling water intakes, notably 

Section 316(b) of PL 92-500, which requires that the location, 

des i gn, construction, and capacity of cool i ng water intake structures reflect the best technology available for minimizing adverse 

environmental impacts. 

Intake design, including the incorporation of fish protection 

devices, is one way to minimize cooling water intake impact, thus 

achieving the goals of Section 316(b) (Hanson et ~., 1977). Such 

protective devices fall into three general categories: collection 

and removal, deterrence, and diversion (Mussalli et ~., 1978; 

Cannon et ~ •• 1979). 

Diversion devices depend on behavioral characteristics, and rely on 

the ability of fish to perceive and react to an external stimulus. 

Angled screens and louvers are the two primary diversion systems 

that have been evaluated for impact mitigation. Early studies on 

fish diversion systems were conducted in California and the Pacific 

402 
Northwest. The i ni tial studies we re concerned primarily with downstream passage of juveni l e sa lmoni ds at hydroelectric facilities, 

and fish exclusion at wa t er diversion projects. Both louver arrays 

and angled screens were employed, with good results reported for 

both systems. 

Initial evaluation studies on the use of diversion systems at 

pumped cooling water intakes closely followed the studies conducted 

at hydroe1 ectri c facil iti es. Di versi on transport systems were 

first evaluated in large-scale t est flumes during the early 1970s 

(Schuler, 1974; Schuler and larson, 1975; Taft et ~., 1976; Taft 

and Mussalli, 1978 ; Taft et al., 1981). Results from these tests 

led to the construction of a full-scale angled screen intake system 

that permitted continued evaluation under actual environmental conditions and with naturally occurring fish populations. The Empire 

State Electric Energy Research Corporation (ESEERCO), a research 

group that comprises the New York State electric utilities that 

sponsored much of the 1 arge-sca 1 e 1 aboratory studi es on angl ed 

screens, sponsored the full-scale angl ed screen study at Central 

Hudson Gas & Electric Corporation's (CHGE) Danskammer Point Generating Station on the Hudson River. At approximately the same time, 

Niagara Mohawk Power Corporati on i ncorporated an angl ed screen 

intake system at thei r Oswego Steam Station Unit 6 on lake Ontario. The third angled screen intake system was constructed at 

New England Power Company's Brayton Point Station Unit 4 on Mount 

Hope Bay, Massachusetts, the northeast portion of Narragansett Bay. 

lawler, Matusky & Skelly Engineers (lMS) conducted multiyear biological evaluations at the three angled screen intake structures. 

Each intake system was evaluated to determine diversion efficiency, 

defined as the number of fish in the diversion system divided by 

the number of fish entering the intake, and survival of those fish 

in the diversion system. The diversion efficiency and survival 

information was used to calculate total system efficiency. Several 

403 
secondary parameters were incorporated in each study to obta in 

additional understanding of system operational conditions. 

DESCRIPTION OF ANGLED SCREEN INTAKES 

Danskammer Point Angled Screen Demonstration Facility 

The Danskammer Point angled screen demonstration facility (Fig. I) 

was located in the cooling water intake canal and consisted of two 

3.0 m wide vertical traveling screens set at a 25° angle to t he approach flow. The angled screen approach channel, 3.2 m wide and 

approximately 13.5 m long, led to a 3.0 m high by 15.2 cm wide bypass. The bypass contracted to a 50.0 cm diameter pipe and then t o 

two 30.5 cm diameter pipes that conveyed the water to two shrouded 

Hidrosta1 (Model L12F) screw-impeller centrifugal pumps. Cool i ng 

water approach velocity to the angled screens was adjustable, resulting in test velocities of 15.2, 30.5, and 45.7 cm/s. Water 

depth in the angled screen approach channel was tidally influenced 

and ranged from 2.0 to 3.0 m. The screens were designed to allow 

the interchange of standard (9.5 mm) and fine (1.0 mm) mesh screeni ng panels. 

Oswego Steam Station Unit 6 

The Oswego Steam Station Unit 6 cooling water is withdrawn from 

Lake Ontario via a submerged inlet with a velocity cap, circulated 

t hro ugh the condensers, and returned to the lake through a subme rg ed jet diffuser. The circulating water flow enters the intake 

screenho use through a verti ca 1 intake shaft , passes through trash 

racks wi th 7.6 cm openings, and enters two screenbays in the primary sc reenwell, each 5.2 m wide, with a water column depth that 

varies from 7.3 to 10.1 m depending upon pump operation and lake 

level (F ig. 2). 

404 
.j::> 

o 

<..n 

FIGURE 1 

DANSKAMMER POINT ANGLED SCREEN DEMONSTRATION FACILITY 

fiSH 

TRANSFORMER ~ 

PUMPS __ \ 

TO EXISTING 

SCREENWELL 

e AFFLE GATES 

PLYWOOD 

WALL 

REMOVABLE 

GRATING 

fISH 

FUNNEL ~ 

tt;F 

RIVER 

,r--. -----'] 

~ 

~ 

. fiSH 

- 'COLLECTION 

TANK 

fiSH 

~COLLECTION 

TANK 

BYPASS 

DISCHARGE PIPE 

iW 

GATES 

~ 

'if'\" 

*' 

~ 

rt') 

03 6 

Scale in Meters 

COOLING 

WATER 

FLOW 

~ 

DRAIN 

..... Z 
""" o 

0'\ 

DRIVING FLOW 

SUPPL Y PIPE FROM 

C.W. PUMPS 

FIGURE 2 

OSWEGO STEAM STATION UNIT 6 

ANGLED SCREEN INTAKE 

PRIMARY 

JET PUMP 

-, SUCTION PIPE 

SECONDARY DIVERSION 

SCREEN WELL 

SECONDARY FISH 

DIVERSION DUCT 

~tCOLLECTION 

.:rRASH 

RACK 

BASIN 

, - "-

,--- SCREENWELL 7 ~8YPASS (TYP) f====i_! ____ "'"-., TRAVELING . )~O /~ ---=--=- / 

FISH DIVERSION 

DUCT 

o L2 3.7 

" ' , I I I I I 

SCALE: METERS 

SCREENS 

SLUICE 

GATE 

TE~I.PER NG 

FLOW 

INTAKE 

SHAFT 

II 

1 

INTAKE 

TUNr~ L 
Each bay will accommodate three 3.0 m wide flush-mounted traveling 

screens separated by 1.0 m wide concrete piers. At present, each 

bay has two screens leading to a 15.2 cm wide bypass. Each bypass 

slot extends the full depth of the water column. The screens are 

angled 25° to the direction of flow, with their downstream ends 

converging but separated by a 1.5 m wide wall. 

The bypass suction flow induced by an 82.3 cm diameter jet pump is 

designed such that the ratio of the average angled screen approach 

velocity to the average bypass entrance velocity is 1:1. The two 

bypass slots converge in the horizontal plane as well as the vertical plane at a 45° angle to two 61.0 cm diameter pipes. The two 

pipes join into a single 82.3 cm diameter pipe that becomes the 

suction side of the primary peripheral jet pump. The primary jet 

pump discharges to a 1.6 m wide secondary screenwell. 

The secondary screenwell contains one angled traveling screen identical in design and orientation to the main screens except for its 

depth. The water depth in the secondary bay varies from 2.4 to 4.6 

mt depending on lake elevation and the number of cooling water 

pumps operating. Most of the water discharged from the primary jet 

pump flows through the secondary screen and is returned to the primary screenwell through aLl m diameter pipe. The fish move 

across the secondary screen into another 15.2 cm wide bypass slot 

that extends the full depth of the water column. The secondary bypass slot converges in the vertical plane to a 45.7 cm diameter 

pipe. At the secondary jet pump this pipe is reduced to a 42.7 cm 

diameter suction pipe. The ratio of the average secondary bay 

angl ed screen approach velocity to. the average secondary bypass velocity varies from 1:1 to 1:1.3. The secondary jet pump discharges 

into a 76.2 cm diameter discharge pipe embedded in the roof of the 

intake tunnel. The pipe extends approximately 280.0 m offshore 

where it rises vertically and tenminates as a horizontal discharge 

approximately 2.0 m off the bottom and 83.0 m from the intake. 

407 
Brayton Point Generating Station Unit 4 

Cool ing water enters the Brayton Point Unit 4 intake structure 

through eight 3.3 m wide by 4.2 m high openings (Fig. 3). The 

open i ngs are shielded by trash racks with a bar spacing of 7.6 cm 

on center. Ten meters into the mouth of the screenwell, the width 

constricts to 12.3 m approaching a 1.5 m thick center wall that 

divides the structure in half. Each half is equipped with three 

3.0 m wide flush-mounted vertical traveling screens set at 25 0 to 

the approaching flow. Each screen panel is modified with a fish 

bucket to maintain the impinged fish in water as the screen rotates. Impinged fish are washed off the back of the screens by a 

low-pressure spray into a f i sh return trough that discharges into 

the Lee River. The screens are designed to allow the interchange 

of standard (9.5 mm) and fine (1.0 mm) mesh screening panels. 

Cool i ng water exi ts the ang1 ed screen structure into a coo11 ng 

canal. 

The design flow of 17.2 m3/s is drawn through the bar racks at an 

average approach velocity of 15.2 cm/s. As the structure constricts, the design velocity increases to 30.5 cm/s approaching the 

traveling screens. Approximately 97% of the design flow {16.75 

m3/s) is drawn through the screens; the remaining 3% (0.5 m3/s) is 

pumped through the fish bypass. 

At the apex of each screenwell a fish bypass is provided (Fig. 3). 

Each bypass has a rectangular opening 15.2 cm wide by 5.1 m high 

t hat constricts to a 45.7 cm diameter bypass pipe. The bypass slot 

is si zed such that two shrouded 30.5 cm diameter screw impeller 

centrifugal pumps (Hidrostal Model L12F) can induce a velocity of 

30. 5 cm/s at the slot's entrance. The bypass velocity at the slot 

is scheduled to be the same as the screen approach velocity. 

408 
FIGURE 3 

BRA YTON POINT GENERATING STATION UNIT 4 

ANGLED SCREEN INTAKE 

L £ [ 

35.6 em DIA. IMPINGED 

FISH RETURN PIPE 

45.7 em DIA. BYPASSED 

FISH RETURN PIPES 

COO L 

SCALE: None 

v [ R 

R 

TRAV£LlNG 

SCR££Ns--~----~r 

N G C 

409 

FISH 

BYPASS 

SLOTS 

[] [I 

~ 

A N A f-
Each bypass opening leads to a 45.7 cm diameter ' fiberglass pipe 

t hat branches into two 30.5 cm diameter pipes that pass through one 

of two Hidrostal pumps, then back to a 45.7 cm diameter pipe that 

carries the flow to the Lee River approximately 91 m downstream of 

the intake structure. 

METHODS 

At Danskammer Poi nt juvenil e and 01 der fi sh were coll ected on a 

seasonal basis from the fish pump discharge using nets (abundance) 

or collection tanks from which the fish could be removed and evaluated for extended survival (96 h). Nets located on the screenwash 

discharge were used to collect all fish impinged on the angled 

screens. 

At Oswego Steam Station Unit 6 the discharge flow was diverted into 

a 2.4 by 2.4 m collection basin during biological performance sampl i ng. Nets located on the primary and secondary screenwash di scharge were used to collect all fish impinged on the angled 

screens. 

At Brayton Point Station Unit 4 impingement abundance and survival 

collections were conducted simultaneously with bypass abundance and 

surv ival collections. The former collections were made from two 

built-in fiberglass collection tanks. The latter collections were 

made from two collection nets attached to a sampling port on each 

45.7 cm bypass return line. 

Small buckets, nylon nets, and dip nets were used at all three 

study si tes to transfer fish to be evaluated for extended survival 

fr om the collection devices to flow-through extended survival holding contai ners. Juvenile or young-of-the-year fish were held primarily in 19 L plasti c buckets. Larger fish or large numbers of 

indivi dual species were held in 568 L linear polyethylene holding 

410 
tanks fitted with a central standpipe arrangement that permitted a 

uniform exchange of water throughout the water col umn. Water was 

supplied to the bucket and tank holding containers through a header 

system and regulated by valves to maintain ambient conditions for 

the extended survival period. 

Angled screen diversion efficiency was calculated using the following formula: 

D Diversion Efficiency (DE) = D+I x 100 

where: 

D = number of fish collected from the diversion flow 

I = number of fish collected from the angled screens 

Initial survival was determined by observing fish from the diversion flow immediately following collection. Fish were identified 

and classified (live, stunned, dead), with the classification conditions defined as follows: 

Live - swimming normally, no orientation problem 

Stunned - swimming erratically, swimming on their 

side, struggling 

Dead - no vital life signs, no body or opercular 

movement, no response to gentle probing 

Initial survival was calculated by dividing the number of fish 

determined to be initially live (LI) by the number initially 

determined to be live, stunned (STI), and dead (DI). The initial survival formula is: 

LI 

Initial Survival (51) = ~L-I-+-S=T~I--+~D~I 

411 
Extended survival (SE) observations were conducted over 96 h for 

the Danskanmer Point and Oswego Steam Station Unit 6 evaluation 

programs and for 48 h for the Brayton Poi nt Unit 4 program. Extended survival was calculated by dividing the number of fish classifi ed live at the end of the observation period by the total numbe r of fish examined for extended survival. 

Angled screen system efficiency is basically a detenmination of the 

probability that a fish entering the angled screen system will survive some period of time after entry and diversion. 

The diversion system efficiency (SE) is detenmined by: 

SE = DE x SI x SE 

This fonmula also includes all types of incidental mortality caused 

by collection, handling, and other nondiversion-related stress. 

Impingement survival was detenmined for fish collected from the 

modified angled traveling screens at Brayton Point Unit 4. Total 

system efficiency (TSE) was obtained by correcting impingement efficiency (IE = 1-DE) and diversion efficiencey (DE) for initial and 

extended survival: 

RESULTS AND DISCUSSION 

Th e most numerous species collected at each plant and their occurrence by water body is presented in Table 1. 

412 
Tabl e 1- Species inventory 

Hudson Lake Mount 

Corrrnon name Sc i entific namea River Ontario Hope Bay 

Al ewife Alosa pseudoharengus X X X 

American eel Anguilla rostrata X X X 

American shad Alosa sapidissima X 

Atlantic menhaden Brevoortia t~rannus X X 

Atlantic silverside Menidia menidia X 

Atlantic tomcod Microgadus tomcod X X 

Bay anchovy Anchoa mitchill i X X 

Blueback herring Alosa aestivalis X -- Brown bullhead Ictalurus nebulosus X 

Butterfish Peprilus triacanthus X 

Emerald shiner Notropis atherinoides X 

Fourspine stickleback Apeltes quadracus X 

Gizzard shad Dorosoma cepidianum X X 

Hogchoker Trinectes maculatus X X 

Mottled sculpin Cottus bairdi X 

Northern pipefish S~ngnathus fuscus X 

Pumpkinseed Lepomis gibbosus X X 

Ra i nbow sme It Osmerus mordax X X X 

Seaboard goby Gobiosoma ginsburgi X 

Spottall shiner Notropis hudsonius X X 

Striped bass Morone saxatil i s X 

Tautog Tautoga onitis X 

Threespine stickleback Gasterosteus aculeatus X X 

White catfish Ictalurus catus X 

White perch Morone americana X X X 

Winter flounder Pseudopleuronectes americanus X 

aAmerican Fisheries Society (1980) 

413 
Danskammer Point Angled Screen Demonstration Fac11ity 

Spring, fall, and winter (limited) sampling, periods of normally 

high fish abundance, resulted in the collection of 59,309 fish consisting of 38 species and 21 families (Table 2) (ESEERCO, 1985). 

Diversion efficiency was high for all species, ranging from 95.4 to 

100.0% and was 99.4% for all species combined. Diversion efficiency was simi 1 ar among seasonal sampl i ng peri ods and angl ed screen 

approach velocities. No influence on diversion efficiency was determined for screen mesh size, time of day, or angled screen approach velocity. 

Initial survival (SI) observations of 16,555 fish collected from 

the diversion flow (Table 1) ranged from 80.9% for the dominant bay 

anchovy to 100.0% for the hogchoker, and was 90.2% for all species 

combi ned. No seasonal or angl ed screen approach velocity effect 

was noted on initial fish survival. Extended 96 h survival observations were made on 13,007 fish (Table 1) and resulted in a survival value (SE) of 35.3% for all fish combined. In general, the 

fish were divided into two groups: a sensitive group comprising 

bay anchovy and three anadromous herrings (alewife, American shad, 

and blueback herring) and a hardy group containing the majority of 

fish species tested, including white perch, spottail shiner, pumpkinseed, Atlantic tomcod, and striped bass. 

The system efficiency calculated for the demonstration facility was 

31.6% for total fish. System efficiency values for the major 

species exhibited an extremely wide range, but generally fell into 

two groups: a group with low SE (due primarily to low extended 

survival) that included bay anchovy, which was extremely sensitive, 

and herrings, and a group with SE values greater than 70.0%, characterized by white perch and spottail shiner. 

414 
Table 2. Fish collection information, diversion efficiency, initial and extended survival, and system effic1ency: Danskammer Point angled screen demonstration facility, 1981-1983 

Initial survival Extended survival System 

Diversion SI 48 h Se efficiency 

Number Percent efficiency Number SI Number SE SE 

Species collected composition (~) analyzed (~) analyzed (~) (~) 

Bay anchovy 26 , 948 45.4 99.6 6,019 80.9 3,869 0.1 0.1 

Blueback herring 11,331 19.1 99.6 4,166 94.9 3,683 8.2 7.8 

White perch 10,415 17.6 99.5 3,521 95.3 3,217 84 . 6 80.2 

Spottail shiner 2,331 3.9 99 .3 789 99.4 569 86.8 85.7 

Alewife 1,443 2.4 99 .0 390 90.3 350 17.4 15.6 

Pumpkinseed 1,067 1.8 98.8 214 96.7 210 92.4 88 . 3 

Atlantic tomcod 898 1.5 97.9 211 96.2 208 77.4 72.9 

White catfish 693 1.2 99.7 243 99.2 208 94.7 93.7 

Brown bull head 594 1.0 99.8 213 98.6 187 88.2 86.8 

American shad 520 0.9 99.4 164 96.3 147 8.8 8.4 

Hogchoker 461 0.8 96.3 133 100.0 55 98.2 94.6 

Striped bass 426 0.7 98.4 133 90.2 131 67.2 59.6 

Others (28 taxa) 2,182 3.7 98.7 359 95.0 173 81.5 76.4 

Total fish 59,309 99.4 16,555 90.2 13,007 35 . 3 31.6 

415 
Foll owi ng surrmari zat i on of the ESEERCO-sponsored study resul ts, a 

second angled screen study sponsored by CHGE was conducted at the 

Danskarrmer Point demonstration facility. The follow-up study concentrated on diversion efficiencies where the bypass velocity was 

not equal to the angled screen approach veloc i ty (LMS, 1986). The 

study consisted of 12 weeks of sampling during fall 1984, a period 

characterized by fish populations composed primarily of juveniles, 

and five weeks during spring 1985, when juvenile Atlantic tomcod 

and spawning populations of alewife, blueback herring, and white 

perch predominated. The collection procedure was modified to incorporate a crowder, which concentrated the diverted organisms in 

trays from which they could be distributed into the long-term holding containers. Collection and sorting were thus carried out with 

minimal organism contact. 

Four angled screen approach and bypass velocities were evaluated: 

15.2, 30.5, 45.7. and 61.0 cm/s. The study design called for continuous sampling between 2100 and 0900 h (period of greatest fish 

abundance) under randomly selected angled screen approach and bypass velocity combinations. Under all tests the bypass velocity, 

calculated at the entrance to the diversion system, would equal or 

be less than the angled screen approach velOCity; bypass velOCity 

would never exceed the approach velOCity. The program design 

resulted in 10 different velocity combinations and six separate 

angled screen approach to bypass velocity ratios. 

During the two seasonal sampling periods 22,125 fish representing 

35 species and 18 families were collected. Abundance, percent compo sition, diversion efficiency, survival information, and system 

effi ciency for the major species and total fish collected over the 

fall and spring sampling periods are presented in Table 3. As noted for t he three-year ESEERCO-sponsored study, diversion efficiency 

was hig h for all species , ranging from 93.0 to 100.0%, with an 

ove rall value of 98.7% for all species combined. No difference in 

416 
Table 3. Fish collection information, diversion efficiency, initial and extended survival, and system 

efficiency: Danskammer foint angled screen demonstration facility, fall 1984-spr1ng 1985 

Initial survival Extended surv1val System 

D1version SI __ 48 h Se effici ency 

Numer Percent eff1c1ency Numer SI Number SE SE 

Species collected conpos1t1on (") analyzed (%) analyzed (") (%) 

Blueback herr1ng 6,176 27.9 98.9 4,793 98 .0 4,682 52.9 51.3 

Bay anchovy 5,413 24.5 98.9 4,157 82 . 2 3,289 15.2 12 .4 

Wh1te perch 4,432 20.0 99 . 7 3,110 97.3 3,064 94.9 92.1 

Atlant1c tomcod 1.784 8.1 99 . 6 1,139 97.1 1.116 87. 9 85.0 

Hogchoker 1.538 7.0 93 .0 1.343 99 . 9 1.322 99.1 92.1 

Wh1te catf1sh 574 2.6 99.5 415 99.5 276 98.2 97.2 

Spottal1 sh1ner 485 2.2 99.8 331 99.7 330 98.8 98 . 3 

Alew1fe 261 1.2 97 . 7 187 94.1 183 38.8 35.7 

Pumpk1nseed 212 1.0 99.1 159 98. 1 159 96.9 94 . 2 

Ra1nbow smelt 159 0. 7 100.0 122 91.8 108 51.9 47.6 

Striped bass 146 0. 7 100 .0 101 96.0 98 93.9 90.1 

Amer1can shad 120 0.5 98.3 90 97.8 89 61.8 59 .4 

Others (23 taxa) 815 3. 7 99.1 620 96.5 519 63.6 60.8 

Total fish 22.125 98.7 16. 567 93.9 15.235 62.6 58.0 

417 
DE was determined for the six different ratios of angled screen approach to bypass velocity. 

A total of 16,567 fish collected from the diversion flow were eva luated for initial survival. With the exception of bay anchovy 

(S1 82.2%), initial survival for the major species was greater 

than 90%, and was 93.9% for all fish combined. 

Extended su rv ival observat i ons were conducted for 96 h followi ng 

collection. A total of 15,235 fish we re observed for extended survival (SE); 14,857 were classified as 1 ive and 378 as stunned. 

At the end of the observation period 9531 f ish were classified as 

1 ive and 34 as stunned. Extended survival for the major species 

was vari able, ranging from 15.2% for bay anc hovy to 99.1% for hogchoker. Overall, the SE was 62.6%, 27.3 percentage pOints hig her 

than the ESEERCO SE of 35.3%, which is directly related to the 

modified collection method. 

As noted for the three-year angl ed screen study conducted at the 

Danskarrmer Point demonstration facil ity between February 1981 and 

October 1983, fish populations are generally grouped in one of two 

categories: a sensiti ve group and a ha rdy group. The sensitive 

group, characterized by high mortal ity over the 96 h observation 

period, included the three Alosa spp. (alewife, American shad, and 

bl ueback herring), bay anchovy, and rainbow smelt; the hardy group 

exhibited low mortality over the 96 h observation peri od and incl uded the two temperate basses (striped bass and white perch). 

sunfi sh (represented by the pumpki nseed), catfi sh (represented by 

the white catfish), spottail shiner, Atlantic tomcod, and hogchoker. The 1984-1985 system efficiency (SE) of 58.0% is almost 

twi ce the SE value obtained from the 1981-1983 ESEERCO-sponsored 

st udy of 31.6%. 

418 
Oswego Steam Stati on Unit 6 

Two species (Tab l e 4). al ewife and rainbow smelt, accounted for approximately 90% of fish entrapped at the Oswego Steam Station Unit 

6 intake duri ng the April 1981 - March 1983 study peri od (lMS, 

1984). Diversion efficiency was 79.3% for alewife and 74.2% for 

rainbow smelt. The combined DE was 77.9%. ranging from 53.4% for 

mottled sculpin to 94.8% for gizzard shad. 

For the seven most numerous species a total of 34,294 individuals 

were examined for initial survival. The combined SI was 50.9% 

and ranged from a low of 45.2% for rainbow smelt to 87.4% for emerald shiner. Extended survival observations covering 96 h were conducted on 7534 fish. Alew1fe exhibited the lowest SEt at 22.4%; 

the highest. 93.6%, was calculated for mottled sculpin. The combined SE for the top seven species was 35.4%. 

System efficiency (SE) calculated for the dominant species represents fish diversion across two separate angled screen systems and 

passage through two jet pumps on the bypass return system. The 

calculated SE was 14.0%. and ranged from 9.2% for alewife to 72.7% 

for spottail shiner. 

Brayton Point Generating Station Unit 4 

Duri ng the 18 month (October 1984 - March 1986) study peri od. 

79.206 fish were entrapped (based on corresponding samples between 

angled screens and diversion flow): 18.791 collected from the angled screens and 60,415 estimated from the diversion flow (lMS, 

1987). The angled screen evaluation program resulted in the collection of 57 fish species representing 36 families. Abundance, 

percent composition, diversion efficiency. survival information, 

and system efficiency for the major species (95.4% of the total) 

and total fish collected during the 18 month study period are pre419 
Table 4. Fish collection information, diversion efficiency, initial and extended sllrvival, and system 

effici ency : Oswego Steam Station Unit 6, April 1981-March 1983 

In1tial survival Extended survival System 

Di ve rsion SI 48 h SE efficiency 

Numbera Percent efficiency Number SI Number SE SE 

Speci es collected composition (1.) analyzed (1.) analyzed (1.) (1.) 

Alewi fe 448,870 46.0 79 . 3 12 , 496 51.8 3, 599 22.4 9. 2 

Rainbow smelt 433,862 44.5 74 .2 18, 215 45.2 2,846 36 . 4 12. 2 

Emerald shiner 22,598 2. 3 94.2 812 87 . 4 367 87.5 72 .0 

Gizzard shad 26,173 2.7 94.8 1,393 73.7 249 47.8 33 .4 

Whi te perch 18,808 1.9 90 . 6 475 55 .6 229 69.4 35 .0 

Mottl ed sculpi n 11,827 1.2 53.4 460 81.5 125 93 .6 40.7 

Spottail shiner 12,744 1.3 92 .9 443 86.2 119 90 .8 72 .7 

Total 974,882 77 . 9 34 , 294 50 .9 7,534 35.4 14 .0 

aEstimated abundance based on average monthly collection rates (No./h) over the period April 1981 - March 

1983. 

420 
sented in Table 5. Di versi on effi ci ency (DE) was 76.3% for all 

speci es comb; ned . Over 93% of the tota l bay anchovy entrapment 

occurred duri ng August and September 1985 when fi ne mesh screen 

panels were being t ested. The bay anc hovy collected during this 

period were early juveniles that exhi bited very low diversion. 

Diversion efficiency ranged from 52.9% for northern pipefish to 

99.4% for American ee l . Diversi on eff iciency was 86.7% for the 

other 45 fish species combi ned. 

Initial survival (SI) observations of 28 , 186 fish collected from 

the diversion flow ranged from 5 . 6% for bay anchovy to 99.7% for 

American eel. SI was 57.8% for all f ish combined, increasing to 

82.6% with the exclusion of bay anchovy. Extended survival observations (SE) were made on 9209 fis h and resulted in an overall 

survival value (SE) of 63 . 4% . Extended survival trends for the 

major species were simil a r to in i tial survival and were variable 

among species, ranging from 0% for bay anchovy to 99.6% for 

tautog. In general, the fish were divided into two groups: a 

sensitive group comprising bay an chovy, Atlantic silverside, 

Atlantic menhaden, and butterfish and a hardy group containing a 

majority of the f ish spec i es t ested, including winter flounder, 

northern pipefish, th reesp ine sti ck l eback , fourspine stickleback, 

tautog, American eel, hogchoker , and seaboard goby. 

Angl ed screen system effi ci ency (SE) for all fi sh combi ned was 

28.0% and increased to 47 .7% with the exclusion of the bay 

anchovy. Survival efficiency values for the less tolerant group 

ranged from 0.0% for bay anchovy to 22.5% for Atlantic silverside. 

SE values for the hardy species ranged from a low of 55.2% for 

seaboard goby to 90.0% for the threespine stickleback. 

The Brayton Point Unit 4 traveling screens were modified with lip 

troughs and a low-pressure ri nse to increase survi va 1 of impi nged 

fish. Initial survival (SI) observations of 18,831 fish col421 
Table 5. Fish collection information, diversion efficiency, initial and extended survival, and system 

efficiency: Brayton Point Station Unit 4, October 1984-March 1986 

Initial survival Extended survival System 

Diversion SI 48 h SE effi ciency 

Number Percent efficiency Number SI Number SE SE 

Species collected compos1tion (%) analyzed (%) analyzed (%) (%) 

Bay anchovy 32,563 41.1 57.0 9,095 5.6 144 0.0 0.0 

Atlantic 23,504 29.7 96.9 10,338 81.8 2,742 28.4 22 .5 

sil verside 

Wi nter flounder 8,284 10.4 87.7 3,114 96.1 2,409 91.6 77.2 

Northe rn pipefish 3,284 4. 1 52.9 837 96.2 799 71.2 36 . 2 

Threespine 1,481 1.9 92.4 621 98.6 600 98.8 90 .0 

stickleback 

Atlantic menhaden 1,279 1.6 90.3 606 16.0 97 17.5 2.5 

Fourspi ne 1,108 1.4 83.5 448 98.4 439 91.6 75.3 

stickl eback 

Tautog 843 1.1 62.2 256 99.2 253 99.6 61.5 

American eel 837 1.1 99.4 391 99.7 27 85.2 84.4 

Butterfish 819 1.0 95.5 381 49.9 189 13.2 6.3 

Hogchoker 811 1.0 85.6 326 99.4 322 96.6 82.2 

Seaboard goby 750 0.9 83.2 294 91.2 265 72.8 55.2 

Ot hers (45 taxa) 3,643 4.6 86.7 1,479 64.2 923 50.5 28. 1 

Total fish 79,206 76.3 28,186 57.8 9,209 63.4 28.0 

Total excluding 46,643 89.7 19,091 82.6 9,065 64.4 47.7 

bay anchovy 

422 
lected from the ang led verti cal traveling screens (Table 6) ranged 

from 1.7% for the dominant bay anchovy to 99.1% for hogchoker. 

51 was 24.3% for all fish combined. increasing to 89.6% with the 

exclusion of bay anchovy. Extended 48-h survival observations were 

made on 3855 impinged fish and resulted in an overall survival 

value (5E) of 77.7%. Extended su rvival trends for the major taxa 

were similar to i nitial survival and were variable among species. 

ranging from 1.7% for bay anchovy to 98. 4% for tautog. 

The total system efficiency (TSE ) was 32.4% (Table 6). TSE increased to 55.3% with the exclusion of bay anchovy. which constituted 41.1% of the tot al en t rapment. TSE values for the major 

species exhibited an extreme ly wide range. from less than 0.1% for 

bay anchovy to 97.9% for tautog. but generally fell into two 

groups: a hardy group with TSE values greater than 65% and a 

sensitive group with TSE values less than 25%. 

The primary contributors to lower total system efficiency were low 

initial (SI) survival and/or ext ended (SE) survival for the 

sensitive species. Atlantic silverside (29.7% of the total with 

96.9% DE). a representative of t he sensitive group with a TSE of 

23.1%. exhibited high initi al survival from both impingement 

(82.1%) and diversion (81.8%). but low extended survival. 22.2 and 

28.4%. respectively. 

DISCUSSION OF ANGLED SCREEN EVALUATION RESULTS 

Angled screen diversion efficiency (DE) was similar at Oswego Steam 

Station Unit 6 (77.9%) and Brayton Point Station Unit 4 (76.3%). 

averaging approximately 77.0%. The Danskammer Point angled screen 

demonstration facility had an overall DE of 99.3%. 

Based on results from tagging studies. diversion efficiency at the 

Oswego Steam Station was found to be affected by residency in the 

423 
Table 6. Initial and extended survi val information on maj or taxa and t otal fi sh and cal culated total system effi ci ency : Brayton Point 

Generati ng Station Un it 4, October 1984 - March 1986 

ImEingement Diversion Total 

Initial survival Extended survival Initial survival Extended survival system 

Impingement SI 48 h SE Diversion SI 48 h SE efficiency 

efficiency Number SI Number SE efficiency Number Sr Number SE TSE 

Species (%) observed (%) observed (%) (%) observed (%) observed (%) (%) 

Bay anchovy 43 .0 13,987 1.7 235 1.7 57.0 9,095 5.6 144 0 <0.1 

Atlantic silverside 3.1 745 82.1 491 22.2 96.9 10,338 81.8 2,742 28.4 23.1 

Winter flounder 12.3 1,025 95 .6 787 95.2 87 . 7 3,114 96.1 2,409 91.6 88.4 

Northern pipefish 47.1 1,551 98.1 1,134 95.1 52.9 837 96 . 2 799 71.2 80.2 

Threespine stickleback 7.6 113 93.8 105 96.2 92.4 621 98.6 600 98.8 96.9 

Atlantic menhaden 9.7 126 38.1 48 8.3 90.3 606 16 .0 97 17.5 2.8 

Fourspine stickleback 16.5 183 86.9 155 96.1 83 .5 448 98 .4 439 91.6 89 .0 

Tautog 37.8 329 97 .9 317 98.4 62.2 256 99.2 253 99.6 97.9 

~ American eel 0.6 5 60.0 99.4 391 99.7 27 85.2 84.4 N 

~ Butterfi sh 4.5 37 56.8 21 57.1 95.5 381 49.9 189 13.2 7.7 

Hogchoker 14.4 117 99.1 115 96 . 5 85.6 326 99 . 4 322 96.6 96.0 

Seaboard goby 16.8 126 87 .3 109 85.3 83.2 294 91.2 265 72.8 67.7 

Others (45 taxa) 13..3 487 70 .2 338 80.8 86.7 1,479 64.2 923 50.5 35.7 

Total 23.7 18,831 24.3 3,855 77.7 76.3 28,186 57.8 9,209 63.4 32.4 

Total excluding 10.3 4,844 89.6 3,620 82.6 89 . 7 19,091 82.6 9,065 64.4 55.3 

bay anchovy 
intake screenwel l. During construct i on of the Un it 6 intake, several 20.0 cm pipes were placed i n t he intake screenwe ll and extended vertically along the cen ter wal l from above the water surface to 

the bottom of the screenwell and across the screenwell floor. A 

1.5 m high plate at the bottom of each traveling screen precludes 

water withdrawal from the bottom of the screenwell, and corrugated 

stop logs at t he location for the add ition of the third traveling 

screen in each screenwell offers fish quiescent or refuge areas. 

The Danskammer Point angled screen demon stration facility was designed to permit evaluation studies at varying angled screen and 

diversion bypass veloc ities. The prima ry sampling program incorporated angled screen app roach velocities ranging from 15.2 to 61.0 

cm/s, with the velocity at the diversion bypass opening matched to 

the angled screen approach velocity. Diversion efficiency was 

greater than 99.0% for all velocities tested and there was no relationship determined between velocity and diversion efficiency. 

Various ratiOS of angled screen approach and bypass velocities were 

tested under the CHGE-sponso red program. No difference in angled 

screen diversion efficiency was noted fo r the various angled screen 

approach and bypass ve loc i ty combi nations although there was a general trend of increased DE with inc reased bypass velocity. 

The Danskammer Point angled screens were designed to permit the installation of either 9.5 or 1.0 mm mesh panels. As operational 

problems with the year-round use of the 1.0 mm mesh panels were 

found to be negligible, the second half of the ESEERCO study for 

juvenile and adult fish was conducted using fine mesh screens. 

Diversion efficiency was similar among comparable seasons with 9.5 

and 1.0 mm mesh screens. Detailed analysis was done using the dominant bay anchovy, and no rela tionship between panel mesh size and 

diversion efficiency was found. Evaluation of the Brayton Point 

collection information from 9.5 and 1.0 mm mesh screens indicates 

that diversion is directly related to the size (age) of the fish, 

425 
with small fish exhibiting greater impingement and larger, more 

mature fish with greater sensory and swimming capabilities exhibiti ng greater diversion (lMS, 1987). 

Overall, the angled screen intake systems were found to be effective at diverting fish f rom the intake screenwell to the bypass return system. The degree of effectiveness varied by species, seasonal condition of the population, e.g., prespawn and postspawn 

stocks, and the age of the f ish. 

The critical factor in assessi ng the effectiveness of a mitigative 

intake system is the condition of the fish diverted or returned to 

the sour ce wat er body. Initi al survival at the Danskammer Point 

demonstration facility was 90.2% for the ESEERCO study and 93.9% 

fo r the CHGE study. Initial survival was 50.9% at Oswego Steam 

Station Unit 6 and 57.8% at Brayton Point Unit 4. Extended survival at Danskammer Point was 35.3% for the ESEERCO-sponsored study 

and 62.6% for the CHGE-sponsored study. Extended survival was 

35.4% at Oswego Steam Station Unit 6 and 63.4% at Brayton Point 

Unit 4. At all three locations, collection and handling mortality 

has been determined to be or is projected to be significant. The 

i nitial work at Danskammer Point suggested that a change in the 

survival collection methodology, in which all netting was elimina ted and fish were not di rectly handled, would greatly decrease 

stress and increase survival . As noted i n the CHGE study, when the 

collection net was eliminated and handling minimized, initial survi val increased 3.9% and extended survival increased 43.6%. The 

most dramatic changes were observed for extremely sensitive speci es, suc h as bay anchovy, with SE increasing from 0.1 to 15.2%, 

and alewife, with the 96 h SE increasing from 17.4 to 38.8% 

(Tabl e 7). The Oswego Steam Station method of collection was to 

us e a crowder to concentrate the fish in a collection basin and 

t hen di pnet t hem ou t to holdi ng containers. At Brayton Point nets 

suspended i n the water were used to intercept the bypass flow. 

426 
Table 7. Comparable informat i on on common taxa and total fish among the 

angled screen intake systems evaluated 

DANSKAMMER PO INT OSWEGO STEAM BRAYTo.N POINT 

ESEERCO CHGE STATION UNIT 6 STATION UNIT 4 

Al ewife DE 99.0 97.7 79.3 93.0 

SI 90 .3 94.1 51.8 52.2 

SE 17 .4 38.8 22.4 12.5 

SE 15.6 35.7 9.2 6.0 

Atlantic tomcod DE 97.9 99.6 94.6 

SI 96.2 97.1 84.1 

SE 77 .4 87.9 48.9 

SE 72.9 85.0 38.9 

Bay anchovy DE 99. 6 98.9 57.1 

SI 80.9 82 . 2 5.6 

SE 0.1 15.2 0.0 

SE <0.1 12.4 0.0 

Rainbow smelt DE 100.0 100.0 74.2 94.7 

SI 76.9 91.8 45.2 11.9 

SE 10.0 51.9 36.4 28.6 

SE 7.7 47.6 12.2 3.2 

Spottail shiner DE 99.3 99 .8 92.9 

SI 99.4 99 . 7 86.2 

SE 86.8 98.8 90.8 

SE 85 .7 98. 3 72.7 

White perch DE 99.5 99. 7 90.6 92.7 

SI 95.3 97.3 55.6 92.0 

SE 84.6 94 . 9 69.4 39.1 

SE 80.2 92.1 35.0 33.3 

Total fish DE 99.4 98.7 77 .9 76.3 

SI 90.2 93.9 50.9 57.8 

SE 35.3 62.6 35.4 63.4 

SE 31.6 58.0 14.0 28.0 

DE - Diversion efficiency 

SI - Initial survival 

SE - Extended survival 

SE - System efficiency 

427 
Water depth at the collection site was minimal and turbulence in 

the collection net substantially increased the stress placed on the 

organisms collected for survival observations. 

Duri ng the various Danskammer Point velocity tests, no relationship 

was observed for initial survival, but there was a general trend of 

greater survival at lower velocities for sensitive species and 

little or no influence on hardy species. Aside from this trend, 

survival was not influenced by varying the ratio of angled screen 

approach to bypass approach velocity. 

In general, all three studies indicate that older fish of a species 

exhibit greater initial and extended survival. However, in all 

three studi es the i nfl uence was speci es speci fi c, with survi va 1 

greater in the younger age groups for some taxa due to the condition of the post spawned adults. 

The three angled screen systems having a high guiding capability, 

were found to be effective devices for mitigating fish impingement, 

and with the exception of a few species, demonstrated high initial 

survival of fish following passage through the diversion system. 

Extended survival varied by species and was greatly influenced by 

co 11 ect i on and hand 1 i ng techn i ques. Ang 1 ed sc reen intake sys tern 

efficiencies (all species combined) ranged from a low of 14.0% at 

Oswego Steam Station Unit 6 to a high of 58.0% at Danskammer Point 

under the CHGE-sponsored study. The angled screen intake system 

was very effective for the hardy species but relatively ineffective 

for the numerically dominant sensitive species. In the actual 

operation of an angled screen intake system the fish would not be 

collected and observed, but returned directly to the source water 

body. Thus, the true measure of system efficiency should not include mortality associated with collection and handling. 

428 
REFERENCES CITED 

American Fisheries Soc i ety: A l ist of common and scientific names 

of fishes from the United States and Canada. Fourth Edition. 

Special Pub l ica t ion No. 12. 174 pp (1980). 

Cannon, J. B., G. F. Cada, K. K. Campbell, D. W. lee, and A. T. 

Szluha: Fish protection at steam-electric power plants: alternati ve screeni ng devi ces. Oak Ridge Nati ona 1 laboratory. ORNl/TM-6472. 138pp (1979). 

Empire State Electric Energy Research Corporation (ESEERCO): Fish 

protective intake test facility: angled screen diversion 

study. Report prepared by lawler, Matusky & Skelly Engineers 

(1985) • 

Hanson, C. H., J. R. White, and H. W. li: Entrapment and impingement of fishes by power plant cooling-water intakes: an overview. Mar. Fish. Rev. MFR Paper 1266, 39(10):7-17 (1977). 

lawler, Matusky & Skelly Engineers elMS): Evaluation of the 

angled screen fish diversion system at Oswego Steam Station 

Uni t 6. Research project No. EC 104. Apri 1 1981 - March 

1983. Report prepared for Niagara Mohawk Power Corporation 

(1984). 

lawler, Matusky & Skelly Engineers (lMS): Evaluation of fish diversion efficiency and survival related to varying angled 

screen approach to bypass velocity ratios. Report prepared for 

Central Hudson Gas & Electric Corporation (1986). 

lawler, Matusky & Skelly Engineers (lMS): Brayton Point Station 

Unit No.4, angled screen intake biological evaluation program. 1984-1986 summary report prepared for New England Power 

Company (1987). 

Mussalli, Y. G., E. P. Taft, and P. Hoffman: Biological and engi- neering considerations in the fine screening of small organisms from cooling water intakes. In Proc. Workshop on larval Exclusion Systems for Power Plant Cooling Water Intakes. Ed. by R. 

K. Sharma and J. P. Palmer. Argonne National laboratory. ANl/ES-66 (1978). 

Schuler, V. J. Experimental studies in guiding marine fishes of 

Southern Cal ifornia with screens and louvers. In Proceedings of the Second Workshop on Entrainment and Intake Screening. 

Ed. by l. D. Jensen. Electric Power Research Institute Rep. 15 

(1974). 

Schuler, V. J., and l. E. larson: Improved fish protection at intake systems. Am. Soc. Civil Eng., J. Environ. Eng. Div. 

101(EE6):897-910 (1975). 

429 
REFERENCES CITED 

(Continued) 

Taft, E. P., P. Hoffman, P. J. Eisele, and T. Horst: An experi- mental approach to the design of systems for alleviating fish 

impingement at existing and proposed power plant intake structures, p. 343-365. l!! L.D. Jensen. Ed. by Third National 

Workshop on Entrainment and Impingement. EA COllTTlunications, 

Melville, NY (1976). 

Taft, E. P., and Y. G. Mussalli: Angled screens and louvers for 

diverting fish at power plants. Am. Soc. Civil Eng., J. 

Hydraul. Div. 104(HY5):623-634 (1978). 

Taft, E. P., R. H. Berger, J. Larsen, J. G. Holsapple, and L. 

Eberley: Laboratory evaluation of larval fish impingement and 

diversion systems. l!! Proc. Workshop on Advanced Intake Technology, Apr. 22-24 (1981). 

430 
POTENTIAL IMPACT OF TIDAL POWER DEVELOPMENT ON ESTUARINE 

ENVIRONMENTS IN THE SOUTHEASTERN USA 

Roger A. Rulifson 

Institute for Coastal and Marine Resources 

and 

Department of Biology 

East Carolina University Greenville, NC 27858 

Michael J. Dadswell 

Department of Biology 

Acadia University Wolfville, Nova Scotia BOP 1XO Canada 

George C. Baker 

Tidal Power Corporation Halifax, Nova Scotia B3J 1P3 Canada 

ABSTRACT 

Harnessing the power of ocean tides for the production of 

electricity is now a reality. The world potential for tidal hydropower 

production is estimated at 1,240 billion KWh/yr, with at least 50 coastal 

areas around the world considered as potential sites for power 

development. As the technology of low-head turbines improves, the number 

of potential power sites will increase to include southeastern USA 

coastal areas that possess strong tidal currents. Countries including 

Canada, France, The People's Republic of China, and the Soviet Union have 

constructed commercial tidally-powered electrical generation plants, yet only Canada has conducted extensive studies to determine potential impact of tidal power on aquatic resources. Changes in hydrology, primary productivity, and secondary productivity associated with tidal power can 

be extensive depending on the design of the facility and mode of 

operation. Studies to determine effects of operational tidal power plants on fisheries are limited in number and scope. Damage is greatest 

in regi ons where fi sh are abundant and fi sh passage is repeated by the 

same population many times throughout the year. Three tidal power designs and their potential environmental effects are discussed relative 

to tidal power development in the southeastern USA. 

431 
INTRODUCTION 

Tidal hydropower -- the production of e1 ectricity by harnessing the 

power of ocean tides - has become economical 1 y feasib1 e as a resul t o f 

socio-economic problems associated with fossil and nuclear fuel s (Stephens 

and Stap1 eton, 1981) and improved technology for low-head turbines. The 

world potential for tidal power production is estimated at 1,240 bi lli on 

KWh/yr (Gray and Gashus, 1972). At least 50 coa stal areas around the wor l d 

are considered potential site s for tidal power development (Fi g ure 1). 

Thi s number will increase as the technology of low-head turbines impr oves, 

thus increasing the number of coastal areas suitable for ti da l powe r 

generation. Strong tidal currents associated with shallow coastal environments, simil ar to those found in a number of southeastern USA estuarie s , 

may be used. Countries that have operational tidal power p1 ants inc1 ude 

France, The Peop1 el s Repub1 ic of China, the USSR, and Canada. Onl y Canada 

has conducted extensive pre- and post-construction studies to determine 

potential impact of tidal power on aquatic resources. 

Tidal hydropower has advantages over more conventional methods of 

power generation since it re1 ies on a renewable energy source which is 

1 ocal1 y avail able, thus e1 iminating prob1 ems associated with transport of 

fossil or nuclear fuel s to the generating site. No poll uting by-products 

such as noxious hydrocarbons, thermal effl uent, or radioactive waste are 

produc e d from hydropower pl ants. Additional benefits incl ude improved 

in frastructure, flood control, and aquacul ture potenti al (Gray and Gashus, 

1972 ). Ti dal hydropower has additional advantages over riverine install ation s in t hat i t is not infl uenced by seasonal water 1 evel s, floods or 

dr oughts (Lar sen 1981). 

432 
POTENTIAL TIDAL POWER SITES 

* OPERATIONAL UNITS 

SAN JOSE GULF 

OE SEAOO E ST 

SAN JULIAN GUL F 

SANT A C RU Z ES T 

GALLEG O S ES T 

D 

(]t> 

OJ 

OANGE~ LJ~ R ~ ~ ~ 

KIMBERLEYS~ 

GULF OF CAMBAV ~ 

o 

Figure 1. Potential tidal power development sites in the world 

for the gated barrage design (from Dadswell et al, 1986). 

Asterisk (*) denotes sites with operational Udal power 

plants. 

433 
The concept of tidal po'.Er is not new. Tidal energy was harnessed i n 

Europe as early as the 11th century to produce mechanical energy for 

exc1 usive use a t the site of generation (Lawton 1972). Tide mill s were 

common up to the mid-19th century in France, Spain, Eng1 and, Ho11 and, and 

Russia (Char1 ier 1982). In North America, Hy1 ie (1979) reported that more 

than 300 01 d tide mi 11 s were found along the east coast from New Br unswi c k 

to Georgia. 

As with all electrical power generation, the possible effects on the 

physical and biological envirorment must be considered. However, before 

aquatic ecological effects of tidal po~r development on southern coastal 

ecosystems can be predicted, the engineering designs that might be used for 

ul tra-10w head power generation must be examined within the context of 

environmental impact studies conducted on operational tidal power 

facilities. Results of these studies can be extrapolated to ultra-low head 

designs that are more feasible for use in the southeastern USA. 

GATED BARRAGE DESIGN 

Design and Operation 

There are several modern desi gns for tidal power generation. The onl y 

design in use is the "gated barrage" type, which is similar in principle to 

hydropo~r generation facilities in rivers. This design is used in coastal 

areas with 1 arge tidal ampl itude and re1 ies upon the dail y or twice dail y 

ri se and fall of the tide. A barrage, or dam, containing turbines and 

sl uice gates is constructed across an estuary or embayment to form the 

head pond. The storaqe basin is filled at high tide and emptied at low tide 

434 
(single effect), or generation takes p1 ace during rising and ebbing tides 

(double effect) against a head which is utilized by turbines of more or 

less conventional design. The storage basin is typical1 y an estuary or 

inlet of such shape that a 1 arge surface area can be enclosed by a 

rel ative1 y short dam, and the vol ume of water he1 d by the headpond must 

ensure production of electricity over a reasonable period. The tidal power 

facility can use one barrage and basin (single basin) or a combination of 

barrages and basins (doub1 e basin). 

There are four basic barrage designs: 1) single basin, single effect; 

2) single basin, double effect; 3) double basin, single effect; and 4) 

double basin, double effect (Figure 2). Detailed descriptions of the modes 

of operation are provided by Lawton (1972), Wi1 son and Severn (1972), and 

Char1 ier (1982). These designs invo1 ve three basic steps (ray1or et a1., 

1985). The first step, called "sluicing", allows the water to enter the 

head pond on the flood tide by opening the sl uice gates and turbines. At 

the optimum time, the sl uice gates and turbines are closed and the 

"waiting" step for po\oP-r generation begins. During thi s step, the sl uice 

gates and turbine gates are closed until the difference in head between the 

headpond and the sea is sufficient to begin power generation. The third 

step is power generation, which is initiated by opening the gates to the 

turbines. 

All modern tidal po~r p1 ants util ize the single basin configuration. 

The oldest form of tidal power generation is the sing1 e basin, single 

effect configuration which dates to the tide mill s of ~stern Europe in the 

e1 eventh century (Char1 ier, 1982) and was used for production of mechanical 

energy in North America (Wyl ie, 1979). The basin is all o~d to fi 11 during 

435 
Basin Basin 

A B 

Sea Sea 

c 

Sea 

G 

Figure 2. Operational schemes for the gated barrage design: 

A) single basin, single effect; B) single basin, 

double effect; C) interconnected double basin. 

S = sluicing; G = generating. 

436 

G 
f1 ood tide through the sl uice gates and po\tP-r ho use, with turbines spinning 

freely. Power is generated on the ebbing tide. North Ameri ca' s first 

modern tidal po'tP-r p1 an t, the Annapo 1 is Tidal Generating Station in Nova 

Scotia (Figure 3), is operated in this manner (Douma and Stewart 1981; 

Dadswe1l et al., 1984, 1986). The sing le basin, double effect mode of 

operation is similar to the Ra nc e River power plant in LaRance, France, 

which produces power on both f1 ood and ebb tides (Coti11 on, 1974). The 

Rance River pl ant has an install ed capacity of 240,000 kW of power from a 

head of between 3-13 m with a maximum f1 ow through the pl ant of approximately 6840 rn3lsecond (Cai1lez, 1966). 

Environmental Impacts 

Few stud ies have been d irec ted toward determining the env ironmenta 1 

effects of development and operation of gated barrage tidal power 

facilities. Results of these studies were summarized by Haller (1972), 

Shaw (1980), Oadswell et al. (1986) and Rulifson et al. (1986). The 

majority of these studies addressed problems .1ssociated with tidal power 

develoJlllent in the Canadian ~~aritime provinces (Gordon and Oadswell, 1984; 

Table 1). Fundamental effects for any tidal power design will incl ude 

changes in primary and secondary productivity of coastal waters, fish 

mortality, fl uctuations in sea 1 evel, local 'tP-ather patterns, and socioeconomic structure both 1 ocall y and regional 1 y (Larsen and Topinka, 1984). 

Env ironmenta 1 changes may affect natural resources over a wi de geographic 

area (Gordon and Oadswell, 1984) or be restricted to local changes 

depending on a nllTlber of factors such as the size of the basin, the amount 

of water passed on each tidal cycle, and the natural productivity of the 

area. 

437 
Power House 

3enerating { -

Levels --="=",,,"=---t 

Upstream 

Wicket 

Gates 

Straflo Turbine 

Generat i ng 

Head 

Downstre a m 

Current ........ 

Figure 3. Cutav/ay view of the Annapo'lis Tidal Generating Station 

shO\vi ng the STRAFLO turb·j ne (from Dadswell et al, 1986) 

438 
Table 1. Physical and biological changes associated with tidal power 

producti on using barrage type designs under megatidal conditions. 

Physical "effects 

Energy removed from tide 

Reduced vol ume of seawater exchange into basin 

Changes in water circul ation patterns seaward of and within the 

basin 

Ti dal range red uced in basi n 

Mean water level increased 

Increased water collJl1n strati fi cation 

Decreased turbidity 

Increased sedimentation 

Change sin sa 1 twa ter I freshwater boundary -- estuar ine and ground 

water 

Reduced storm surge 

Increased fl ushing time 

niological effects 

Increased phytopl ankton production 

Reduced sal tmarsh inundation 

Shifts in species composition 

Shi fts in species abundance and di stribution 

t10rtal ity of biota associated with passage through turbines. 

439 
Physical a1 terations of the env ironment wi 11 occur as a resu1 t 0 f 

removing energy from the tide and reducing the vo1l1T1e of seawater exchange 

into the basin. These physical changes wi 11 u1 timate1 y resu1 t in a1 terations of the local ecosystem. Water circu1 ation patterns both seaward of 

and within the basin wi 11 be a1 teredo Within the basin, tidal range wi 11 

be reduced but mean sea level may increase (Baker. 1984). Reduced energy 

input to the system will increase vertical strati fication of the water 

col umn, reduce turbidity, and increase sedimentation in certain areas 

(Amos, 1984). Increased mean sea level within the basin will effect 

changes in the sal twater-freshwater boundary within the estuary and within 

the aquifer (Palmer and l3ean1ands, 1977). Under normal conditions, an 

estuary acts as a "shock absorber" for coastal areas during high-energy 

storms. A barrage-type power generation facil ity wou1 d reduce stormre1 ated damage within the basin. F1 ushing time of the estuary would be 

increased, thereby increasing the possibil ity of eff1 uent disposal and 

assimilation problems for areas receiving agricultural, municipal, and 

industrial wastes. 

Changes in the biotic system wi 11 resu1 t from a1 terations of the 

physical environment. The most immediate effects are shifts in species 

composition, abundance and distribution. Ho~ver, many bel ieve that overall production of benthos and zoop1 ankton will not be a1 tered appreciably 

by construction of the tidal barrage (Hall er, 1972; Daborn et al., 1984; 

Peer, 1984). Decreased turbidity and increased nutrient load may increase 

phytop1 ankton production (Prouse et a1., 1984). Increased sedimentation 

ma y impact shell fi sh beds (Ri sk e t a1., 1977; Witherspoon, 1984) or change 

t he size and shape of sa1tmarshes within the system. Changes in the 

440 
biological system wi 11 be 1 argel y control 1 ed by the physical attributes of 

each si teo 

The abil ity to pass fi sh successful 1 y through tidal power generation 

facil ities is not an easy engineering probl em. Mill ichamp and Staite 

(1980) suggested gaps in the barrage that woul d allow up to 5% of the 

estuarine water to pass unimpeded through the barrage, thus attracting and 

guiding migrant adult fishes. Ladders and fish lifts are not possible 

because of the design probl ems associated with passing fi sh in two 

directions (ebb and flood tides). Diversion screens and fish guiding 

devices such as louvers, 1 ights, or bubbl e curtains may be feasible for 

some gated barrage power pl ants, espec iall y if the nllTlber of turbines is 

small rel ative to the 1 ength of the barrage. Such designs may be 

appl icable to the Annapol is Tidal Generating Station. However, these 

methods may be impractical for 1 arge tidal power dams envi sioned for the 

inner Bay of Fundy and other developments using present engineering 

concepts. Fish passage must therefore be relegated to open sl uice gates 

and free-spinning turbines in the water control structure on flood tides, 

and through the turbine during power generation on ebb tides. The critical 

design factors of conventional turbines for fish passage are: turbine 

diameter, number of bl ades, di scharge velocity and vol ume, rotational 

speed, pressure flux and cavitation potential. These factors were 

di scussed in detail for Kapl an and Franci s turbines by Monten (1985), and 

for the STRAFLO turbine at the Annapol is facil ity by Dadswell et al. 

(1986) • 

441 
"TI DAL FE NC E" DES I GN 

Design and Operation 

A more moderate approach to el ectrical generation using tidal energy 

is the concept of employing the tidal wave created by the sun and moon as 

the energy source rather than a quasi-static hydraul ic head created by 

damming a coastal basin with a 1 arge tidal ampl itude. Thi s concept 

invol ves operation of tidal po~r pl ants at ul tra-low heads on both floO<1 

and ebb tides (double effect) using swift estuarine or coastal currents 

(Table 2). The barrage structure would be much more open, resembl ing a 

bridge rather than a dam, and would possess very 1 arge turbine apertures 

(Figure 4). PO\'P-r production using the tidal fence design would involve 

onl y the power production and sl uicing steps of operation; no waiting step 

is needed. Ocean construction techniques required to build and position 

barrage modules in deep and fast-flowing water are now avail able (H. A. 

Simons Int'l. Ltd., 1984). However, ultra-low head designs are not yet 

feasible because economically viable turbines have not been developed. 

The possibl e options for energy conversion devices in a tidal fence power 

pl ant were reviewed by Taylor et al. (1985). Options incl ude both 

horizontal- and vertical-mount ducted turbines. Because of the very large 

turbine areas, full gates or sl uiceways would be impractical. The tidal 

fence barrage wi 11 al ways be open to flow, so the entire opening of the 

estuary must be fitted with flow restrictors (e.g., turbines, partial 

gates, or other partially or completely impermeable elements) to prevent 

the water froo diverting direction and passing through the areas of 1 east 

resi stance. Nav igational locks coul d be incorporated into the design to 

fac il itate cOOlITIercial and recreational traffic in navigable waters (H.A. 

442 
+=-

+=-

w 

Table 2. Siting criteria and predicted environmental impact (due to changes in tidal ampl itude) of tidal pO\'P-r 

schemes (after Taylor et al. 1985). 

Physical 

Usual worki ng Basin Current Site Foundation Environmental 

Engineering Design head si ze veloeities Depth requ; rements Impact 

Gated Barrage 

Single effect or medium small low to >10 m excellent major loeal 

double effect 5-10 m moderate <30 m di sruption 

Open Barrage 

"Tidal fence" low 1 arge moderate >10 m minimal due to moderate 

(Double effect) to high <100 m reduced head di sruption 

Current turbines zero not hi g h >10 m secure negligible 

("underwater windmill") (0.05 m) appl ;cabl e anchorage 
J . ( I II I 

/ /' I I I ' 

I I // / 

I 

I ) ! j / ) I 

I 

I I Ii 

I 

I 

, II 

( I 

I ' I,' / ! / 

I / 

! / , . I 

I / 

I \ I 

\/ 

; 

l.L. 

444 
Simons Intl l . Ltd., 1984). Ex i sting infrastructure for ground transportation could be improved by providing road and rail access over the tidal 

fence barrage. 

Taylor et al. (1985) reviewed the advantages and disadvantages of 

tidal fence power production rel ative to the gated barrage design; a nllTlber 

of these points pertain to tidal po~r develoJll1ent in the southeastern USA. 

Lower working heads will reduce the hydrostatic load on the environment, 

resu1 ting in a po~r p1 ant design with site options for greater variabil ity 

in channel depth and foundation (bedrock) conditions (Table 2). The open 

design of the barrage wi 11 permit construction in high velocity tidal 

streams and closure of 1 arge basins without severe1 y modifying the natural 

tidal regime. Energy production can be ba1 anced more equall y over the 

tidal cycle, except at slack water. A major disadvantage is the partial or 

complete loss of c ontrol options (e.g., "waiting") that can be used to 

augment energy produc tion. 

Environmental Effects 

A1 though southern estuaries are much different physica11 y compared to 

systems normally considered for tidal power development, a1 terations of 

their physical and biological environments can be predicted based on 

resul ts of the gated barrage studies described above. A minimal head is 

required (about 2 m) for po~r production, but the head is caused by backpressure of the water being forced through the tidal fence. not the 

physical damming and release of water through a gated barrage. Thi s backpressure will probabl y reduce tidal circul ation within the estuary. thus 

reducing turbidity and increasing sedimentation in certain areas. Reduced 

445 
circul ation or al tered patterns may decrease the chances of fi sh and she llfi sh 1 arv ae spawned offshore to be transported successfull y to the 

sal tmarsh nursery grounds typical of southeastern estuaries (e.g., 

Weinstein, 1979; Rulifson, 1983; Miller et al, 1984). Reduced circul ation 

will increase the estuary fl ushing time, which may increase nutrient loads 

and cause waste di sposal and assimil ation probl ems wi thin the estuary and 

adjacent waters. Reduced turbidity should increase phytopl ankton and zoopl ankton production in both estuarine and coastal waters. Al t ered 

circul ation patterns will have unpredictabl e effects on sedimenta t i on 

patterns, having a stabilizing effect in some areas while increa sing or 

reducing shoaling problems in other. Large hasins may exhibit increased 

stratification of the water col umn, which may intensify exi sting 

differences in sal inities, temperatures, and dissol ved oxygen. Storm sur ge 

damage within the estuary would be reduced, but the storm energy may be 

redistributed along the barrier island system creating additional problems 

of inlet stabilization and shoreline erosion. 

Problems associated with fish passage through tidal fence po~r plants 

would be simil ar, though probabl y 1 ess extreme, than those described above 

for gated barrage facil ities. Due to the 1 ack of sl uice gates, all fi sh 

passage would be accOOlplished through the turbines and navigational locks 

on both flood and ebb tides. Since the tidal fence turbines wi 11 be much 

1 arger, however, the physical stress pl aced on the fish during passage will 

be different than for conventional turbines. Estimation of fi sh mortal ity 

or injury during passage through tidal fence turbines has 1 ittl e meaning at 

thi s time because full-scal e working model s of the proposed turbine designs 

have not been constructed. However, we can predict that the water 1 ength 

446 
(distance between each successive pass of the runner blades), impact 

velocity (velocity of a bl ade str i king a fi sh) and mutil ation rates may be 

simil ar to that of conv entional turbines. Injury caused by pressure fl ux 

and cavitation will be reduced because of the low head required for 

operation. 

CURRENT TURB INES 

Design and 0eeratfon 

The current turbine is a concept for qenerating power from tidal 

currents using free standing power generation units requiring no barrage 

and no head (Table 2). The concept is based on wind energy technology and 

would extract k1netic energy from steady ocean currents using hori zontal 

axis turbines, or from tidal currents using vertical axis turbine$. Power 

generation would occur through most of the tidal cycle, initiated when a 

minimal velocity is present at the start of ebb or flood tide and 

tenninated when the water veloeity di ps below the minimum (Taylor et ale 

1985). Such a power pl ant facil ity waul d resembl e a series of underwater 

windmills positioned in the tidal channel of an estuary. This type of 

design would allow only a fraction of the kinetic energy available to be 

intercepted and captured and would not be as efficient as the barrage type 

designs described above. 

The advantages of such a design in protecting the env ironmental 

integrity of southeastern USA estuaries is obv ious. Env ironmental impact 

to the physical and biological systems waul d be reduced. Mortal ity of fi sh 

and shell fi sh 1 arvae immigrating to estuarine nursery grounds, and of 

migrant adul ts to spawning areas, woul d be lower than for conventional 

447 
turbines. No cavitation or pressure mortal ity is expected; death caused by 

bl ade stri kes may reduce mortal ity by one-hal f to two-thirds. Obstruction 

to navigation would be minimal, except for the substantial foundations and 

structural supports required for holding the power unit in pl ace. Effects 

on water circulation patterns, sedimentation. etc. would be negli gible 

relative to conventional tidal hydropower but may cause problems for 

organiS'Tls utilizing tidal transport to enter (Miller et al. 1984) or exit 

(Rul ifson 1983) estuaries. 

Sm1MARY 

Electrical generation facil ities util izing tidal energy are being 

developed around the world. As technology for electrical generation using 

ultra-low head turbines improves, the nlJllber of sites available for t idal 

power development wi 11 increase to incl ude estuaries and coastal areas of 

the southern USA possessing strong tidal currents. Three designs of tidal 

power faci 1 ities are described. one of which is in use. The other two are 

feasibl e for use in southeastern USA but waters the technology is not full y 

developed. The gated barrage design is used in coastal areas with 1 arge 

tidal ampl itude. A moderate head of 8-10 m is created by damming estuarine 

waters and generating power with conventional turbines on ebbing tides. 

The estuary is fill ed on flood tides by passing water through sl uice gates 

and the powerhouse. Major al terations to the physical and biological 

systems occur with this design. The tidal fence concept would util ize 

1 arge turbines positioned in a structure resembl ing a bridge or causeway. 

No sl uice gates are required with this design. All migrant biota would 

pass through the turbines on hoth ebb and flood tides, but injury caused by 

448 
cavitation and pressure fl ux would be minimal. The current turbine design 

would be the most env irorrnentall y coopatibl e but 1 east efficient in power 

production. Current turbines waul d resembl e underwater windmill sand 

uti 1 i ze wind energy technology for power generation. No dam or head is 

required, obstruction to navigation is negligible, and biota would pass 

rel ativel y unimpeded to and froo estuarine habitats to the adjacent coastal 

waters. 

449 
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451 
1i1l ichamp. R.I.. and E.M. Staite. Fi sheries considerations. pp. 175 - 184 

in T.L. Shaw. ed •• An env ironmental apprai sal of tidal power stati on s: 

wi th partic ul ar reference to the Severn barrage. Fearon Pi tma n 

Publ i shers Inc •• Belmont CA. USA. 220 p. 1980. 

lonten. E. Fish and turbines: fish injuries during passage through po~r 

station turbines. Vattenfall. Norstedts Tryckeri, Stockholm, Sweden. 

111 pp . 1985. 

Palmer, A.. and G.E. Beanl ands. The 1 and-based nearshore resources of the 

Bay of Fundy, pp. 278-285 in G.R. Daborn, ed . , Fundy tidal power and 

the environment. Acadia University Institute , Wolfville, NS, Canada. 

1977 • 

Peer, D.L. The impact of a tidal power project on the intertidal benthos 

of Cobequid Bay. Can. Tech. Rep. Fi she Aquat. Sci. 1256:463-468. 

1984. 

Prouse, N.J., D.C. Gordon, Jr., B.T. Hargrave , C.J. Bird, J. McLachl an, 

J.S.S. Laksminarayana, J. Seti Devi, and M.L.H. Thomas. Primary 

production: organic matter suppl y to ecosystems in the Bay of Fundy. 

Can. Tech. Rep. Fi she Aquat. Sci. 1256: 65-96. 1984. 

Risk, M.J., R.K. Yeo, and H.D. Crai g . Aspects of the marine ecology of the 

r~inas Basin rel evant to tidal power development. pp. 164-179 in G.R. 

Daborn, ed. Fundy tidal po~r and the env ironment. Acadia Universi ty 

Institute. Wol fville. NS. Canada. 1977. 

Rul ifson, R.A. Behavioral aspects of juvenil e penaeid shrimps, ~ aztecus 

and P. duorarlJ1l, during tidal transport. Contrib. r~ar. Sci. 26:55-63. 

1983. 

452 
Rulifson, R.A., M.J. Oadswell, and G.K. Mahoney. American Fisheries 

Society pol icy on t i dal power development and estuarine and marine 

envirorrnents. Fisheries 11:36-39. 1986. 

Shaw, T.L., ed. An environmental appraisal of tidal power stations: with 

particul ar reference to the Severn Barrage. Fearon Pitman Publ ishers 

Inc., Belmont, CA, USA. 220 p. 1980. 

Stephens, H.S., and C.A. Stapl eton, eds., 2nd international symposi urn on 

wave and tidal energy, Cambridge, Engl and. BHRA Fl uid Engineering, 

Cran fi e 1 d, Bed ford, Eng 1 and. 1981. 

Taylor, J.M., B.G. Keefer, and J. Lang. Ul tra-l ow head tidal power: 

technology and site assessment. Report to the National Research 

Council, Canada. ~1arch 1985. 

Waller, D.H. Environmental effects of tidal power development. pp. 611-

625 in Gray and Gashus, eds., Tidal power. Pl enum Press, New York, 

NY, USA. 1972. 

Weinstein, M.P. Shallow marsh habitats as primary nurseries for fi shes and 

shell fi sh, Cape Fear River, North Carol ina. Fi shery Bull. 77:339-357. 

1979. 

Wil son, E.M., and B. Severn. Integration of tidal energy into publ ic 

e 1 ec tr i cit Y sup ply. p p. 307 - 3 21 in G ray and Gas h us, ed s., Tid a 1 

power. Pl enll11 Press, New York, NY, USA. 1972. 

Witherspoon, N. The soft-shell cl am (Mya arenaria) resource along the 

north shore of ~1inas Basin and potential impact of the proposed tidal 

power project on its long-term productivity. Can. Tech. Rep. Fish. 

Aquat. Sci. 1256:491-510. 1984. 

453 
Wylie, F.E. Tides and the pull of the moon. The Brattleboro Press, 

Brattl ebara, VT, USA. 246 pp. 1979. 

454 
MITIGATION BANKING IN THE SOUTHEASTl 

James D. Brown 

U.S. Fish and Wildlife Service 

Atlanta, Georgia 

David M. Soileau 

U.S. Fish and Wildlife Service 

Layfayette, Louisiana 

R. Wilson Laney U.S. Fish and Wildlife Service 

Raleigh, North Carolina 

ABSTRACT 

In recent years, a concept known as "mitigation banking" has evolved as a 

mechanism for achieving mitigation of unavoidable habitat losses 

associated with water resources development projects. In mitigation 

banking, habitat improvement actions are conducted in advance of project 

construction. Mitigation credits attributable to these actions are 

placed in a mitigation bank account and can be used later to compensate 

unavoidable habitat losses resulting from actual project construction. 

This innovative approach is being used with some success, mainly on the 

West Coast and in the Southeast. Two good examples of mitigation banks 

in the Southeast are a 5,OOO-acre bank established by the Tenneco Oil 

Company for mitigation of the impacts of oil exploration and development 

in coastal Louisiana wetlands, and a l,436-acre bank established in the 

lower Roanoke Ri ver Bas in "by the North Carol ina Department of 

Transportation for mitigation of the impacts of highway projects on 

bottomland hardwoods. Both banks are associated with wetlands permitting 

activities and are being used to accomplish desirable habitat 

preservation and management goals. 

lThe findings, conclusions, opinions, or recommendations expressed in 

this paper are those of the authors and do not necessarily reflect the 

views or positions of the U.S. Fish and Wildlife Service. 

455 
INTRODUCTION 

Mit i gation of fish and wi Idlife habitat losses caused by water 

resources development activities is an issue that increasingly has 

occupied the attention of managers, planners, and developers. The 

term generally is considered to mean avoiding or minimizing adverse 

impacts to fish and wi ldlife and compensating for unavoidable losses 

of those resources . Historically, miti gation has been one of the most 

troub l esome aspects of planning for water resources development 

projects because it came at the end of the permitting process. 

Disagreements over the definition of mitigation, how best to Initigate, 

how much mitigation is required, and even who is responsible for 

mitigation have been commonplace. As a result, many projects have 

been planned and constructed with little or no mitigation, and 

valuable fish and wildlife habitats have been degraded or lost without 

compensation. Loss of habitat is the most critical fish and wildlife 

problem in the United States, and the mitigation of these losses 

whenever possible is absolutelj imperative . 

In an effort to improve the mitigation process, the U.S. Fish and 

Wildlife Service (1981) promulgated a formal mitigation policy to 

guide its involvement in the planning of water resources development 

projects. This policy presented a definition of mitigation, 

established Resource Categories of fish and wildlife habitat with 

associated mitigation goals, and described procedures for 

quantitatively determininy mitigation needs based on the val ue of the 

affected habitat for fish and wildlife. One approach to achieving 

mitigation identified as acceptable in the policy is "mitigation 

456 
banking." This innovative approach to mitigation has been employed 

I I 

with some success in recent years (Soileau et al. 19B!:>; 

Niedzialkowski and Jaksch 1986), mainly on the West Coast and in tile 

Southeast. Approxihlately 12 mitigation banks are in various stages of 

planning and operation in the United States . 

Four mitigation banks exist in the Southeast. These include a bank 

established by the Tenneco Oil Company in south central Louisiana for 

mitigation of the impacts of oil exploration and development in 

coastal Louisiana wetlands, and a bank established in the lower 

Roanoke River Basin by the North Carolina Department of Transportation 

fo r mitigation of the impacts of highway projects on bottomland 

hardwood wetlands. The two other banks are a small ti dal marshl and 

bank in Chesapeake, Virginia, operated by the Virginia Department of 

Highways and Transportation (Russell 19B3), and a bottomland hardwoods 

bank in Louisiana operated by the Louisiana Department of 

Transportation and Development. Brief descriptions of the Tenneco and 

Nort h Carol ina Department of Transportation banks are included in this 

paper for the purpose of illustrating the concept of mitigation 

banking. 

457 
MI TIGATION BANKI NG CONCEPT 

Mitigation banking is defin ed i n t he Se rv ice ' s mi ti gation policy as 

"habitat protection or i mpr ovement acti ons t aken exp r essly for the 

purpose of compensating for unavo i dable, necessary losses from 

specific future actions." Soileau et al. (198 5 ) provided the 

fOl lowing genera l ized explanation of mi tigation bank i ng : 

" Ion s imp 1 i fie d t e r m s, mi t i gat ion ban kin 9 iss i mil art 0 

maintaining a bank account . A developer undertakes measures 

to create, restore , or prese r ve fiSh and wildlife habitat in 

advance of an anticipated need f or mitigation for project 

construction impacts . The benefi ts attributable to these 

measures are qua ntified, and t he developer receives 

mitigation credits from the app r op ri ate regulatory and/or 

pl anning agencie s . These cred i ts are placed in a mitigation 

bank account froln which withdrawal s can be made . When the 

developer proposes a project involving unavoidable losses of 

fish and wildli f e resources, the losses (deb i ts) are 

quanti tied using the same method that was used to determine 

credits, and a withdrawal equa l to that amount is deducted 

(debited) from the bank. Th i s can be repeated a s long as 

mitigation credits remain available i n the bank." 

The Fish and Wildlife Service's mitigation policy incorpo r ated the 

definition of mitigation contained in the Council on Environmental 

Quality's National Env i ronmental Pol icy Act regulation s (40 CFR Part 

loU8.2U[a-eJ). By that definition , mitigation can include: 

458 
(a) avoiding the impact altogether by not taking a certain 

action or parts of an action; 

(b) min i mizing impacts by limiting the degree or magnitude of 

the action and its implementation; 

(c) rectifying the impact by repairing, rehabilitating, or 

restoring the affected environment; 

(d) reducing or eliminating the impact over time by preservation 

and maintenance operations during the life of the ac tion; 

and, 

(e) compensating for the impact by replacing or providing 

substitute resources, or environments. 

This definition recognizes both the modification of project design to 

avoi d or lessen impacts and compensation for impacts that are 

unavoidable . Avoiding the impact altogether is the preferred 

mi t i gation method, followed by min i mizing the impact . These may be 

acc omplished by such measures as relocating the project to a less 

env i ronmentally sensitive site, selecting a project plan that avoids 

or le ssens adverse impacts, or modifying the project plan. 

Com pensation, which involves actions taken to offset unavoidable 

im pacts, is the l east favored mitigation method and should be 

c on si der ed onl y after all feasible means of avoiding or reducing 

impacts have been exhausted. Compensation can involve a variety of 

ha bi tat cr eation, restoration, or management activities. By its 

de fi ni t i on, mi t i gat i on banking is a mitigation approach that can be 

use d only when compe nsation is warranted. 

459 
An important element in mit i gation banking i s ttle ne e d for a 

standardized, replicab l e quantitative method of determining cred i ts 

and deb i ts. The Habitat Evaluation Procedures (HEP ) developed by the 

U.S. Fish and Wildl i fe Service (198U) provide a good method of doing 

this. HEP is founded on the premise that habitat can be evaluated in 

terms of its abi l ity to support specific fish and wildl ife populations 

(evaluation elements). HEP provides a means of evaluating existing 

conditions and future condit i ons with and without a project. Thus , 

the benefits resulting from habitat improvement actions can be 

quantified through a HEP analysis and these benefits then constitute 

the bank account ava i lab l e to a developer . As ind i vidual development 

projects occur, their impacts can be similarly quantified and deducted 

from the bank account . HEP is not the only acceptable method of 

quantitying credits and debits; other credible evaluation systems may 

be used. In some cases, credits and debits may have to be determined 

using the best professional judgment ava i lable. 

460 
TENNECO OIL COMPANY MITIGATION BANK 

In October 19~2 the Tenneco Oil Company proposed the establishment of 

a mitigation bank on approximatelj 7,OUO acres of fresh to brackish 

marsh (palustrine emergent wetlands to estuarine intertidal emergent 

wetlands, Cowardin et ~. 1919) in Terrebonne Parish in 

south-central Louisiana. Federal and state agencies that participated 

in the planning of that bank included the Fish and Wildlife Service, 

the National Marine Fisheries Service, the Soil Conservation Service, 

the Louisiana Department of Wildlife and Fisheries, and the Louisiana 

Department of Natural Resources. 

Th e mitigation bank site lies within an area that is undergoing a 

rapid loss of coastal wetlands. The rate of coastal marshland loss in 

Louisiana exceeds 40 square mi les per year and is increasing (Wicker 

198U; Gagliano 1981). These losses have resulted from a combination 

of natural and man-induced causes, including rising sea level, 

subsidence, the physical processes of growth and deterioration of the 

Mi ssissippi River Delta, channelization and levying of the Mississippi 

River, excavation of canals for oil and gas exploration, and 

extraction of groundwater . The flow of nutrient and sediment- rich 

fresh waters to these marshes has been blocked or diverted. Combined 

wi t h subsequent intrusions of salt water, this has resulted in 

conve rsions of large areas of fresh marsh to brackish or saline marsh 

or to estuarine open water. Records indicate that the original fresh 

mar shes of the mitigation bank site have undergone such 

461 
conversion to brackish marsh and open water due, in part, to the 

elimination of fresh water and sedilnent inflow in the early 19UU's . 

This deterioration wa s prOjected to continue unless appropriate 

management steps were undertaken. 

The marshes and shallow open waters of the mitigation bank site 

provide excellent habitat for numerous adult and juvenile finfishes 

and shellfishes. Because of the diverse salinity regimes, both 

freshwater species (largemouth bass, bluegill, blue catfish, and 

channel catfish) and estuarine species (Gulf menhaden, seatrout, 

croaker, blue crab, white shrimp, and brown shrimp) util ize the area. 

The wildlife value of the area is considered equally high. The area 

consistently winters a tremendous number of waterfowl, and there is 

keen cowpetition for hunting leases. Non-game wetland birds that 

occur in the bank site include egrets, herons, ibises, and white 

pelicans. The area also supports an abundant population of 

furbearers. Large numbers of nutria, muskrat, and alligators are 

harvested on the site, and smaller numbers of raccoon and mink are 

taken. 

Tenneco proposed to impl elnent a structural water management plan that 

would reintroduce fresh water and sediment inflow, improve water 

circulation, and reduce intrusion of salt water. This management 

program was projected to reduce significantly the rate of marsh loss 

and to ex tend the projected 1 i fe of the marsh even after the all owabl e 

credits and been debited. An interagency team measured the 

462 
anticipated benefits of the proposal using HEP. The lengthy and 

i ntens i ve negotiations that ensued culminated in an interagency 

Memor andum of Agreement (MOA) in January 1984, which formally 

establ i shed the mitigation bank. The MOA included a description of 

the bank's purpose, general recommendations, and 18 provisions 

governing the implementation and operation of the bank. Some of the 

more important provisi ons in the MOA are listed below. 

1. The interagency review team, here and after referenced, consisting 

of the U.S. Fish and Wildlife Service (serving as chairman), the 

U. S. National Marine Fisllerie s Servi ce, the U.S. Soil Conservation 

Service, tne Loui si ana Department of Natural Resources, and the 

Louisiana Department of Wildlife and Fisheries, shall determine 

habitat units and the AAHU ' sl to be initially credited to the 

mi ti gati on bank and shall determi ne future debits and credits to 

the mitigation bank. 

2. The appropriate parti es to th i s Agreement shall use HEP, or a 

Inutually agreeable and credible methodology , to determine credits 

and debits to be app 1 i ed to the miti gati on bank. 

1 Average Annual Habitat Units, a measure of habitat value 

calcul ated i n HEP. 

463 
3. rv1itigation by debiting available AAHU's from the mitigation bank 

is appropriate and will be used to offset only unavoi dable impacts 

on fish or wildlife when the appl ican t can demonstrate to the 

satisfaction of all parties to th is Agreement that there are no 

onsite alternative s whi ch are available and capable of being done 

after taking into consideration co st, existing tecnnology, and 

logistics in light of overall project purposes. 

4. Credits generated within Hydrologic Unit 5 shall be applied to 

activities requiring mi tigation within that same Hydrologic Unit 

and may be applied outside of Hydrologic Unit 5 only witn the 

approval of the interagency review team. In no case shall credits 

be applied to projects outside the State of Louisiana. 

5. Tenneco may buy, sell, trade, or otherwise dispose of mitigation 

credits in the form of AAHU's to be debited from the mitigation 

bank . The buyer or assignee of such AAHU's may use SUctl credits 

to satisfy its mitigation obligations subject to applicable laws, 

regulations, and provisions of this Agreement. The interagency 

review team shall be informed prior to such AAHU transfers. 

464 
6. As the Tenneco proposal is a pilot program, 5 years after 

implementation of the management plan a complete evaluation of 

the management program shall be made by the interagency review 

team using HEP, or a mutually agreeable and credible methodology. 

A prel iminary assessment is to be made 1 year after 

implementation of the management program to evaluate the 

effectiveness of the management program. Whenever significant 

operational and/or structural changes are made to improve 

success, another complete evaluation shall be made in 3 to 5 

years following those changes. 

The mitigation bank was established on S,OOl) acres of land owned by 

Tenneco, with Tenneco retaining ownership of the property. Another 

adjacent 2,000 acres of coastal wetlands under other private ownership 

that are receiving benefits from the management plan may be 

incorporated into the bank in the future. The details of a complete 

analysis of the Tenneco bank, including a copy of the MOA, are 

contained in a report by Soileau (1984). 

After the bank was established in early 1984, Tenneco obtained the 

required state dnd Corps of Engineers permits and installed the 

necessary water management structures. Since that time, use of the 

bank as mitigation credit for 10 permit applications for canal 

excavation has been proposed. The debiting process has been delayed 

by onyoing discussions about the number of credits that should be 

wi thd rawn from the bank account. When agreement is reached on thi s 

qu est ion, the mitigation bank ac count will be debited for the first 

t ime. 

465 
NORTH CAROLINA DEPARTMENT OF TRANSPORTATION MITIGATION BANK 

T~e North Carolina Department of Transportation entered into 

discussions with the Fish and Wildli f e Service, the North Carolina 

Wildlife Resources Commission, and the North Carolina Nature 

Conservancy in the spring of 1985 concerning the establishment of a 

mitigation bank in the lower Roanoke River Basin. This bank was 

proposed for the purpose of mitigating unavoidable impacts to 

bottomland hardwoods habitat (palustrine forested wetlands, Cowardin 

~~. lY19) expected fr om future highway and bridge construction 

in North Carol ina . The se discussions went very smooth ly because the 

interagency group was able to draw upon the experience gained from the 

Tenneco bank process and to adapt much of the language in the Tenneco 

MOA to its needs. These discussions culminated in an interagency 

Memorandum of Understanding (MOU) signed by the four participants in 

Septeillber 1985. 

The MOU established the mi tigation bank on a 1,436-acre tract of land 

known as Company Swamp adjacent to the lower Roanok e River in Bertie 

County. The North Carolina Leg i slature appropriated funds 

spec i fically for the purchase of lands to be used as a mitigation 

bank, and the Compa ny Swamp tract was acqui red through the cooperati ve 

efforts of the State of North Carolina and the North Carolina Nature 

Conservancy . Through this process, the North Carolina Wildlife 

Resources COlTlllission gained lUO percent ownerShip of approximately 700 

acres of selectively cut-over bottomland forest and approximately 44 

percent interest in the remaining 736 acres which presently exist as a 

466 
cli max gum-cypress forest. The North Carolina Wildlife ~esources 

Commission has management responsibility for the entire tract in 

perpetuity. 

The entire Company Swamp tract contains some of the finest alluvial 

bottomland forests in North Carolina and the Southeast. These forests 

prov i de food, water, breed i ng territories, and cover for waterfowl, 

furbearers, wad i ng birds, songbirds, and numerous small malomals, 

amphibians, and reptiles. They also prov i de valuable escape and 

foraging habitat for larger species, such as whitetail deer, black 

bear, and wild turkey. The area is frequently flooded and i s used by 

an adromous blueback herring as forage and spawning sites . 

Th e MOU for the North Carol ina Departlnent of Transportation bank was 

patterned after the Tenneco MOA, and several of its 12 operational 

pr ovisions are identical or similar. Provisions were included to 

desi gnate the geographic area in which the bank can be applied, to 

pr ovide for tile determi nation of credits and debits by an interagency 

t eam, to restrict use of the bank for only unavoidable impacts, and 

to provide for monitoring and reevaluation of the project. The 

agr eement also provides for the use of HEP to determine debit 

req ui rements , but only for projects larger than !:i acres. Mitigation 

f or sma ller projects will be on an acre-for-acre basis. Another 

not ab l e difference between this bank and the Tenneco bank is tl1at the 

Nor t h Car oli na agreement does not allow the buying and selling of 

mi tiga t ion credi ts. This bank was planned specifically to mitigate 

l osses of bot t omla nd ha rdwood wetlands in No rth Carol ina ; consequently 

t he MO U co nt ai ns a de ta i led de finitio rl of bottomland hardwood 

we tland s. 

467 
An i nteragency team has been working on a HEP analysis over the past 

severa l months to dete rmine baseline val ues for t he mitigation bank 

area . Field sa mpling was comp l et ed in August 1986. A report 

indi c ating t he nu mber of miti gat i on cr ed its dvail ab l e in tne bank 

account wi ll be subm i tt ed to the North Ca r olina Department of 

Transportd t ion in Februa ry 1987 . The North Carolina Wildlife 

Resources Commission has not ye t developed a final management plan, 

but tentative management measures are being identified and evaluated 

in order to determine the numbe r of preliminary cr ed i ts by the 

February 1987 due dat e . Seve n projects of less than 5 acres already 

hdve been applied against the bank account. Two larger projects that 

require a HEP analysis are awaiti ng action . 

468 
MANAGEMENT CONSIDERATIONS 

Miti gation banking provides a mechanism by which unavoidable fish and 

wildl i fe habitat losses associated with certain water resources 

pro jects can be compensated. This is only one approach to mitigation 

and is applicable only in limited circumstances. Most mitigation 

banks have been used for permitted development activities aff ecting 

wetlands, although a bank could be e stablished for other habitat 

types. In general, a mitigat i on bank s hould be con sidered only when 

hab i tat improvement a c tiviti es, such as wetlands creatio n, 

restoration, or management, create quantifiable benefits to fish and 

~v dl fe habitat value that c an be placed i n a mitigation ba nk 

account . A simple transfer of ownership of land to a public agency 

do e s not constitute mitigation and, therefore , would not qualify for 

establishment of a bank . 

The desirability of mitigation banking derives more from the 

standpo i nt of admin istration and practicality than from its biological 

advantage . Mitigation banking inherently i nvolves offsite mitigation. 

FrOlll a bi olog i cal standpoint, onsite mitigation is preferable. Onsite 

mitigation maintains habitat and biological diversity within the 

land sc ape and comes closer to maintdining ilistorical patterns of 

wil dl ife abundan c e and distribution. Unfortunately, providing 

follow-up and lnanagement of the small, widely scattered tracts of 

hab i tat created through onsite mitigation is difficult. Mitigation 

bank i ng of fers a solution to the problem by providing one large, more 

ea sily managed t r act. 

469 
The most likely candidates for use of a mitigation bank are 

development interests that have predictable, recurring development 

needs, such as port authorities, highway agencies, and petroleum 

development companies. Mitigation banking has not been used for power 

generation projects, although there appears to be a potential for 

application where projects result in direct habitat alteration or 

destruction . Because power plants require siting near a cooling water 

supply, wetlands often are affected . Since large land areas 

frequently are acquired for a plant site, it might be feasible to 

dedicate and operate a wetlands area as a mitigation bank. The 

application of mitigation banking to other impacts of power projects, 

such as entrainment and impingement of aquatic organisms and thermal 

effects, has not been explored and would require thoughtful analysis 

to develop an acceptable approacn. 

A mitigation bank should be planned and orgdnized in a simple , 

straight-forward manner . Ideally the bank should be established and 

administered by a formal interagency agreement, such as those used for 

the Tenneco and North Carolina Department of Transportation banks. 

The agreement should clearly specify the geographic area in which the 

bank can be applied, the party responsible for serving as the banker, 

the party responsible for conducting habitat improvement and 

management actions, the methodology for determining credits and 

debits, the types of impacts for which the bank can be used, 

the monitoring and reevaluation responsibil ities, and the 1 ife of the 

470 
bank . Specific guidance on these considerations has been presented by 

several authors (Soileau et ~. 1985; Zagata 1985; Dunham 1986; 

Niedzialkowski and Jaksch 1986; Riddle and Denninger 1986); however, 

s pecific provisions may vary considerably from one mitigation bank 

agreement to another . 

Mitigation banking can provide benefits to both developers and fi sh 

and wi Idlife resources . For the forme r it saves time and money by 

incorporating mitigation into the early plann ing process, althouth the 

time required for a HEP analysis sOlllet i mes can cause delays. It also 

r e s ults in improved public recognit i on and credit being given to 

deve lopers for working cooperatively wi th fish and wildl ife agencies 

to und ertake needed management act ion s. For wildlife, mitigat i on 

banki ng assures ttlat mitigation for unavoidable losses will occur . It 

al so fosters mi t i gat i on approaches that can be incorporated into basin 

or estuary-wide ma nagement programs. In the past, many small wetl ands 

mi tigation pr ojects have not been successful (Fehring 1983; Dial et 

al. 1985; Race 1985) . In constrast, mitigation banking can offer an 

opp ortunity to plan larger mitigation projects designed to accomplish 

l on g range fish and wildlife goals, such as restoring specific 

veg etation types, increasing habitat diversity, or providing habitat 

for ta rget species . Mitigation banking also can include follow-up and 

mo ni tor i ng requirements to ensure that mitigation measures are 

successfully implemented . 

Sub s tan t i a 1 r i s k s are ass 0 ci a t ed with OJ it i gat ion ban kin g . A rna j 0 r 

ri sk is the potential neglect of good project plann i ng . For example, 

we tland re gul at o ry agen c ie s t ha t are charged wi th protecting the 

471 
public's interest in wetlands are also under a great deal of pressure 

to approve permits . Quick reliance on the mitigation bank may provide 

an easy way out of the dilemma . To avoid this, use of the mitigation 

bank must be allowed only for truly unavoidable habitat losses, after 

all reasonable efforts to avoid or minimize losses Ilave been made . 

Moreover, other planning and regulatory procedures and requirements, 

such as water dependency, availability of alternative sites, and a 

public interest determination, must not be omitted or neglected. A 

Initigation bank also must be operated in a manner that will instill 

public confidence, since it can lead to a perception that permits are 

being bought and sold . Most of these problems can be avoided by 

careful i nteragency cooperation and planning in the development of a 

mitigation bank . 

472 
CONCLUSION 

The alteration or destruction of nabitat, particularly wetlands, 

caused by water resources development projects is one of the most 

serious problems faced by fish ana wildl ife managers. For the most 

pa r t , efforts to obtai n adequate Ill; ti gati on of these impacts have been 

l argely unsatisfactory. In recent years, mit i gation banking 

increasingly has been used as a mechanism for achieving mitigation to r 

unavoidable habitat losses . This approach has attracted widespread 

attention and has stimulated considerable discussion. Mitigation 

banking otfers both benefits and disadvantages and can be used only 

f ur certain types ot projects and impacts . However, if administered 

properly, the approach can provide an effective means of meeting 

mitigation needs. 

473 
LITERATURE CITED 

Cowardin, L.M., V. Carter, F.C. Go1et, and E.T. LaRoe: Classification of 

wetlands and deepwater habitats in the United States, 103 pp. 

Washington, D.C.: U.S. Fish and Wildlife Service, Office of 

Biological Services, FWS/OBS-79/31 (1979). 

Dial, S., M. Quammen, D. Deis, and J. Johnston: Estuary-wide mitigation 

opt ions for port development in Tampa Bay, Flori da. Coasta 1 Zone 

'85:2:1332-1345 (1985) . 

Dunham, F.O.: Mitigation banking: a state perspective. In: Proceedings of 

the national wetland assessment symposlum, June 17-20, 1985, 

Portland, Maine, pp. 257-259. Ed. by J.A. Kusler and P. Riexinger. 

Chester, Vermont: Association of State Wetland Managers (1986). 

Fehring, W.K.: Ports, industry, and fisheries-Can they coexist? In: 

Improving multiple use of coastal and marine resources, pp. 30-38. 

Ed. by J.W. Reintjes. Bethesda, Maryland: American Fisheries 

Society (1983). 

Gagliano, S.M.: Special report on marsh deterioration and land loss in 

the Deltaic Plain of coastal Louisiana, 14 pp. Baton Rouge, 

Louisiana: Coastal Environments (1981). 

Niedzialkowski, D., and J. Jaksch: Wetlands mitigation banking as an 

innovative approach to wetlands regulati on and protection. Paper 

presented at freshwater wetlands and wildlife symposium, March 24-27, 

1986, Charleston, South Carolina. Aiken, South Carolina: Savannah 

River Ecology Laboratory (in press) . 

Race, M.S.: Critique of present wetlands mitigation policies in the 

United States based on an analysis of past restoration projects in 

San Francisco Bay. Environmental Management 9(1), 71-82 (1985). 

Riddle, E.P., and M.F. Denninger: Coastal wetlands mitigation banks: the 

Cal ifornia State Coastal Conservancy experience In: Proceedings of 

the national wetland assessment symposium, June 17-20, 1985, 

Portland, Maine , pp . 260-264. Ed. by J.A. Kusler and P. Riexinger . Chester, Vermont: Association of State Wetland Managers (1986). 

Russell, S.C.: Virginia develops wetland bank. AASHTO Quarterly, 16-17, 

April (1983). 

Soileau, D.M.: Final report on the Tenneco LaTerre Corporation 

mitigation banking proposal, Terrebonne Parish, Louisiana, 23 pp. 

Lafayette, Louisiana: U.S. Fish and Wildlife Service, Division of 

Ecological Services (1984). 

Soileau, D.M., J.D. Brown, and D.W. Fruge: Mitigation banking: a 

mechanism for compensating unavoidable fish and wildlife habitat 

losses. Transactions of the Fiftieth North American Wildlife and 

Natural Resources Conference, 465-474 (1985). 

474 
u.s. Fish and Wildlife Service: U.S. Fish and Wildlife Service 

mitigation policy: notice of final policy. Federal Register 46(15) , 7644-7663 (1981). 

Wicker, K.M.: Mississippi Deltaic Plain Region ecological 

characterization: a habitat mapping study. A user's guide to the 

habitat maps, 45 pp. Washington, D.C.: U.S. Fish and Wildl i fe 

Service, Office of Biological Services, FWS/OBS-79/07 (1980). 

Zagata, M.D.: Mitigation by "banking" credits - a louisiana pilot 

project. Transactions of the Fiftieth North American Wildlife and 

Natural Resources Conference, 475-484 (1985). 

475 
SUCCESSFUL LICENSING OF A MAJOR POWER COMPLEX 

IN THE SOUTHEASTERN UNITED STATES 

ENCOMPASSING MULTIPLE REGULATORY AGENCIES GOALS 

Charles J. Zimmerman , Jr . Ly 1 eA. Lyd i c k 

Dames & Moore 

455 East Paces Ferry Road 

Suite 200 

Atlanta, Georgia 30363 

ABSTRACT 

This report provides an overview of the planning effort and the 

implementation of the various steps during a several year period for 

constructing a large power complex in the Southeastern United States. 

South Carolina Electric & Gas Company (SCE&G) planned and carried out all 

of the activities associated with licensing and constructing both a major 

pumped storage hydroelectric facility and a nuclear power plant. In 

addition, the utility updated an existing power plant to accommodate 

increased water needs by the new facilities. The objectives of the owner 

and of the regulatory agencies were fulfilled. 

Extensive planning and coordination between the involved agencies were 

necessary in order to satisfy the vari ous regul atory requi rements to 

license these facilities. Requirements were met for every phase of the 

program. Studies were conducted for environmental baseline descriptions 

of the project areas; construction and operation monitoring also took 

place as required. The combined uses by these two new facilities of a 

common reservoir required innovative study approaches to isolate impacts 

associated with each component. The biological studies had to be 

carefully planned in order to satisfy each agency's unique study 

requirements. 

In response to the regul atory requi rements of several state and federal 

agencies involved in the decision-making process for the license 

applications for these two plants, a sampling scenario was developed that 

estimated impacts associated with each facility. Complications of 

operating these two programs simultaneously will be described. 

Concurrent with performance of the required environmental studies, 

mitigative measures were employed at various stages of the project. For 

example, since the pumped storage facility came on line approximately six 

years before the nuclear station, mitigative measures such as management 

programs to enhance the area for waterfowl and fish were in place prior 

to completion of the construction of the nuclear facility. These 

wil dl He management programs were Federal Energy Regul atory Commi ss ion 

(FERC) license requirements. 

In general the schedules were met for both of the facilities. The pumped 

476 
storage facility was completed within schedule and the nuclear power 

plant was delayed only slightly in its overall construction and 

operation. 

Although the generating facilities were developed primarily for use of 

SCE&G, energy was avail ab 1 e to ass i st other systems in the case of an 

emergency. South Carol ina El ectri c & Gas Company is a member of the 

Southeastern El ectri c Re 1 i abil ity Counc il . Other members are the major 

utilities and cooperatives in the southeastern United States. 

Today, the facilities are operating and providing electrical energy 

resources to the public. The mitigative measures that were employed are 

continuing to be effectively managed as required. These water resources 

have been widely utilized by the residents of nearby communities and 

other visitors to the project vicinity. In conclusion, the overall 

process of environmental planning, documentation, and implementation of 

biological studies as well as mitigation programs were well thought out 

and executed according to schedule. This resulted in a cost efficient 

environmental program supporting the licensing and operation of the 

facilities while meeting the needs of regulatory agencies and, more 

importantly, the public. 

INTRODUCTION 

It takes approximately 12 to 14 years to plan, license, and construct 

a power generation station. During that time period, a siting study is 

completed, consultation with several regulatory agencies is completed, 

and a license is granted by the lead regulatory agency. Pri or to 

granting a permit or license, scientific investigations are carried out 

for the various disciplines, including geotechnical, cost evaluation, and 

environmental. This paper describes the environmental studies. 

The objectives of the owner were to: 

-Construct and license two generating stations to meet future 

generation needs. 

-Complete the project within the specified time and within budget. 

477 
The objectives of the agencies are : 

-Mitigate habitat loss. As protectors of the environment, the 

agencies' charge was to ensure that the resources would remain for 

future generations. 

-Ensure that project discharge waters were within acceptable limits. 

-Offset fishery losses in the existing reservoir. 

Site Oescri pt i on 

The project site in Fairfield and Newberry Counties is located in the 

Broad River watershed about 26 miles northwest of Columbi~, South 

Carolina. The site includes a hydroelectric plant, a pumped storage 

hydroelectric facil ity, and a nuclear generating station. The Broad 

River (6,100 cfs average annual flow) is one of the major headwater 

tributaries of the Santee River Basin and has its origin in the Blue 

Ridge Mountains of North Carolina. 

The planned approach to development of the generating facilities was 

to be completed in phases. The first phase included updating the 

facilities at the existing Parr Hydroelectric Generating Station. 

The Parr Hydroelectric Generating Station with a capacity of 15 

megawatts became operational in 1916. It has generated electricity for 

SCE&G customers continuously since that time, with the exception of 

478 
being shut down occasionally for maintenance and repairs. To complete 

the planned power complex the existing dam at. the Parr Generating 

station had to be raised. The increased dam height was- necessary to 

increase storage capacity in the lower pool for the proposed Fairfield 

Pumped Storage Facility. An engineering evaluation determined t hat 

raising the existing dam a total of 12 feet by the installation of a 

series of Bascule gates, would be the most cost-effective approach to 

this problem. This would allow a usable storage capacity of 29,000 

acre-feet in the lower pool (Figure 1). 

The second phase of the project was to complete the 480 MW 

Fairfield Pumped Storage Facility (FPSF). This generating station 

prov i des power for peak loads at cert a in times of the day; wi th t he 

increased usable storage in the lower reservoir this station can 

generate for 8 hours. There are eight reversible pump-turbine un its, 

each capable of producing 60 MW of electricity. These turbines rece i ve 

water from the upper reservoir via four penstocks, each 26 feet in 

diameter. There is approximately 150 feet of head between the upper 

and lower pools. The units came on line in 1978. 

The final phase of the project was the completion of the Virgil C. 

Summer Nuclear Station. This station was constructed for generating 

electricity for the base load of the SCE&G's territorial system. The 

nuclear ste~n supply system for the Virgil C. Summer nuclear station is 

suppl ied by a pressuri zed West i nghouse Electr i c Corporat ion reactor; 

479 
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the turbine generator has a power output of 900 MW. Cool ing water is 

withdrawn from the 6,800-acre Monticello Reservoir at the rate of 

534,000 gpm, passed through the system, and Y'eturned to Monticello 

Reservo i r . Th is reservo i r was bu i 1 t to prov i de coo 1 i ng water for the 

nuclear stat ion and serves as the upper pool for the pumped storage 

facll ity. 

REGULATORY REQUIREMENTS 

In response to the regulatory requirements of state and fede r al 

agencies involved in the decision making process for approval of the 

license application for the two proposed facilities, a sampling 

scenario was developed that complied with agency requirements, and that 

evaluated impacts associated with each facility. 

Environmental Monitoring 

The environmental monitoring program for the projects began with 

data collection requirements stipulated by the FERC. Baseline monitoring of water quality, aquatic, and terrestrial resources began in 1971 

on the Broad River and Parr Reservoir (Figure 2). 

Aquatic baseline monitoring continued through the Fall 1973 at 

stations on the Broad River and Parr Reservoir. Terrestrial biology 

monitoring at selected locations was also carried out. During 1974 

through 1977 construction monitoring for aquatic and terrestrial 

resources was carried out. 

481 
Program Component 1971 1972 1973 1974 1975 1976 1977 Location 

Aquatic Vascular Hydrophytes A A A Broad River and 

Parr Reservoir 

Plankton Q Q Q Sp Sp Sp Sp 

Su Su Su Su 

F F F F 

Benthic Q Q Q Sp Sp Sp Sp 

Macroinvertebrates Su Su Su Su 

F F F F 

Fish Q Q Q Sp Sp Sp Sp 

Su Su Su Su 

F F F F 

Terrestrial Soil A Project Area ~ 

ex> Vegetation Q Q A A A A N 

Invertebrates A A A A A 

Amphibians & Reptiles Q Q S 

Birds Q Q Q W W W W 

Su Su Su Su 

F F 

Mammals Q Q 

A a Annual Sp = Spring 

Q .. Quarterly Su ::: Summer 

W .. Winter F = Fall 

FIGURE 2. SUMMARY OF BIOLOGICAL MONITORING PROGRAMS, 1971-1977. 
Monticello Reservoir reached full pool level in February 1978 and 

operational monitoring for the Fairfield Pumped Storage Facility began 

in June 1978 (Figure 3). The monitoring program~; were designed to mee t 

the licensing requirements of the Federal Energy Regulatory Commission, 

and requirements of the National Pollutant Discharge Elimination System 

Permit issued by the South Carol ina Department of Health and Environmental Control (SCDHEC). These studies provided a monthly assessment 

of changes in the ecosystem, the results of the studies allowed the 

comparison of baseline conditions and operations impacts. 

Beginning in January 1983 post-operational monitoring programs 

were designed to meet the licensing requirements of the Nuclear 

Regulatory Commission and the requirements of the National Pollutant 

Discharge Elimination System per~it issued by the South Carolina 

Department of Health and Environmental Control (Figure 4). The purpose 

of the monitoring program was to assess the thermal effects associated 

with the heated effluent from the V.C. Summer Nuclear Station on the 

biota in Monticello Reservoir. 

Mitigation 

Due to the unavoidable adverse impact of construct ing and operating a power facility such as the V.C. Summer Nuclear Station/ 

Fairfield Pumped Storage Facility generating complex, measures were 

taken to mi n imi ze these effects. Minimization of the construction 

impacts included erosion and dust reduction measures and borrowing fill 

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dirt from within the reservoi r area. In addition to these measures a 

land management program was instituted to speed the eco l ogical adjustment of the project area and further al l eviate the adverse effects of 

construction. This program included planting ground cover for erosion 

control, mult iple use timber management, vector control, and landscaping. Other mitigating measures included wildlife, fishery, and 

recreational management programs. The fishery and wildlife management 

programs were closely associated with the biological studies. Those 

studies helped plan effective mitigation programs which combined with 

the recreation management program produced a diverse, popular, public 

use program. 

In order to mit igate the loss of wildl ife habitat caused by the 

construction of the power complex a decision was made to utilize the 

newly created lake habitat to its fullest potential. A 320-acre, 

constant level sub impoundment was created in the northern end of 

Monticello Reservoir for the purpose of recreational fishing, swimming, 

and picnicking. The sub impoundment was intensively managed as a 

recreational fishery by a fish stocking program, and nutrient enrichment program. 

On Monticello Reservoir boat ramps and picnic areas were created 

to stimulate public usage and to provide access to the rapidly 

developing natural fishery typical in a young lake. At one of the 

picnic areas the recreation potential was upgraded by building public 

tennis courts and a softball field. 

486 
At Parr Reservoir sever al enh ancement fe at ur es improved the are a 

for public use. These included: 

o Addition of several boat launching ramps and campin g 

facilities. 

o Initiation of a waterfowl management plan. 

The water fowl management plan included the devel opment of a 

dike-controlled marsh area with adjacent f ields. Both t he marshes and 

the fields were planted with preferred wildlife foods and cover vegetation suitable for nesting. Wood duck nest ing boxes wer e installed in 

suitab l e backwater locat ions. The wat erf owl managemen t plan also 

included the development of a gr een-tree reservo ir near Parr Reservoir . 

The water level of this gr een-tree reser voir could be ra ised or lowered 

i n orde r to enhance growth and avai lability of waterfowl foods. 

Additional mitigat ion was pr ovided by the init i at ion of a Canada 

Goose nesting and stocking program desi gned t o establish a native 

Canada goose population in the Piedmont of South Carol ina . This effort 

included transplanting geese fr om outside the st at e , est abli shment of 

food plots and nesting habitat development on the islands in Mo nt icello 

Reservo ir. To date, all of the mitigati on programs ar e considered to 

be highly successful. 

To ensure cont i nued spawni ng success of the fi shes of the Broad 

River downstream of the project area, the Parr hydroelectric fac il ity 

ma intained certain minimum downstreilln flow requ irements. 

487 
-~- ~ ---

SUMMARY 

South Carolina Electric & Gas Company planned, constructed, and 

1 i censed a maj or power gener at i ng complex. Inc 1 uded in the comp 1 ex 

were a newly constructed major pumped storage facility and a nuclear 

facility; an existing hydroelectric facility was updated. 

Extensive planning and coordination with regulatory agencies was 

carried out to assess potential impacts on natural resources. A 

monitoring program was established in the project area, baseline 

conditions were established, and monitoring requirements were met 

during the construction period. A five-year post-operational monitoring requirement was met for the Federal Energy Regulatory Commission 

and a 2-year post-operational monitoring requirement was fulfilled for 

the Nuclear Regulatory Commission and the South Carolina Department of 

Health and Environmental Control. 

Extens i ve mit i gat i on measures were employed throughout the area 

encompassed by the power complex. During the construction period, 

erosion and dust control measures were used extensively. A land 

management program was instituted to hasten ecological adjustment. A 

timber management program for multiple use purposes was developed. 

Wildlife habitat improvement practices were established. Fisheries 

management programs inc 1 udi ng stocking of game fi sh for recreat ion 

purposes were also established. Other public use mitigation measures 

such as the establishment of tennis courts, ball fields, picnic areas, 

and a swimming beach were put into place. 

488 
This project was well planned and designed. The objectives of the 

owner and the regulatory agencies were fulfilled. 

ACKNOWLEDGEMENTS 

Th is work was supported by South Carol ina E 1 ectr i c & Gas Company 

as part of the regulatory requirements stipulated in the arti c l e s to 

the licenses for each of the generating facilities. Special recogn ition is given to Messrs. W.E. Moore and W.R. Baehr of South Carol ina 

Electric & Gas Company for their contribution to the overall success of 

the program. 

489 
IMPACT MITIGATION AND ENVIRONMENTAL ENHANCEMENT 

REVIEW PAPER 

John Christian 

u.s. Fish and Wildlife Service 

75 Spring Street Southwest 

Atlanta, Georgia 30303 

After reviewing the papers from the session, "Impact Mitigation and 

Environmental Enhancement", I feel the key issues are: 1. what is the 

ultimate impact on the resource of importance, and 2. what is the best 

way to design a program to answer that question. If we cannot answer that 

question, can we develop an iterative dynamic process so that we can make 

changes along the way? 

A 11 the papers presented in my sess i on offer good examples of the 

application of variou s principles of impact mitigation and en vironmental 

enhancement. My objectives are to explain the overall principles and 

illustrate how the specific papers serve these prinCiple s. 

The necessary start i ng poi nt is to understand wha t is meant by the 

term environmental impact. The defin ition and use of this term is a 

critical one for all of us. If there is no environmental impact, then 

there is no need to consi der mitigation, but as I will explain in more 

detail later, enhancement certainly could continue to be a project 

planning objective . The dictionary defines the word "impact" as a 

concentrated force producing change. This definition does not convey any 

meaning that an impact is necessaril y bad or good. It merely conveys the 

meaning that an impact occurs when the existi ng condition is changed. 

Any impact, then, can be interpreted as good or bad , depend i ng on your 

point of view and your point of reference. 

Ross Wilcox ha s given us some excel l ent examples of what I mean from 

the standpoi nt of the manatees ' re~ i ance on thermal plumes at Flori da 

Power and Light coastal power plants. In this ca se, thermal effluent is 

a good impact and provides a benefit to an endangered species. However, 

a strict preservat i onist might consider such an artificially created 

symbiotic relationship as a negative impact because it does not represent 

the natural situation . Again, it depends on your point of view. 

490 
Likewise, a marine biologist who specializes in plankton communitie s may 

consider a thermal plume as having an adverse impact on the nearshore 

plankton community. But that same thermal plume may serve to att ract a 

fish species of sport value, and the fisherman is likely to have a 

different point of view than the marine biologist as to whethe r this 

impact is bad or good . However, if it could be shown that the spec ie s 

composition shifts would result in a reduction of fish productiv ity in 

the overall area, perhaps both the marine biologist and the fisherman 

would agree that the impact is adverse. 

Ecologists might disagree with my comments and say that the primary 

objective is maintenance of the structure and function of the natura l 

ecosystem and that an adverse impact occurs when that natural ecosystem 

is disrupted. My response is that I do not believe that there are many 

remaining examples of natural ecosystems that man has not altered or 

impacted. There may be some examples in the most wild of the wil derness 

areas, but we generally do not build power plants in those area s. Any 

ecologist or biologist knows that the structure and function of 

ecosystems are dynami c and change over time. Mi crohabitats are created 

and then destroyed through natural processes. The overall integrity of 

the larger system is certainly buttressed against major change and 

provi des the condit ions that make that part i cul ar ecosystem or habi tat 

type unique in terms of the plants and animals that live there. 

In the majority of cases, development projects do not affect entire 

ecosystems. Indi vidua 1 projects always have the capabil ity to cause 

major changes in local populations of plants and animals. However, the 

cumulative effect of many such projects certainly has the capability to 

provide a major system disruption. The point that I am trying to make is 

that the word impact is a relative term with some subjective components. 

An impact denotes change; change can be good or bad, depending on your 

point of view. A clear understanding of whether an impact is considered 

adverse is a prerequisite to mitigation planning. 

Robert Davis' paper on angled intake screens provides an example. In 

his presentat ion, he indicated that they were very successful at 

mitigating impacts for certain species; specifically, one example was the 

winter flounder . There was very little loss to the flounder, both in 

491 
terms of initial impact or long term impact. However, for the bay 

anchovy, it was a failure. The angled screen did very little to avoid 

morta 1 ity of the bay anchovy. The quest ion is what is the re 1 at i ve 

ecological significance and importance of those species. One needs to 

answer that to make a determination about whether that particular 

mitigation measure is going to result in a good impact or a negative 

impact. 

An initial resource inventory that identifies critical biological 

areas within the zone of influence of the project and the primary 

biological resources that might be affected can serve as a starting point 

for the impact analysis. Impacts should be defined by a 

multidisciplinary team that includes fishery biol ogists, wildlife 

biologists, system ecologists, 1imno10gists or marine biologists, 

depending upon where you are, and recreational users, such as fishermen, 

hunters, and recreational boaters. The result should be a list of 

environmental objectives for the area in question from which conclusions 

can be drawn about whether a change caused by a given power plant design 

would result or could result in an adverse impact, a beneficial impact, 

or no impact at all, based on the agreed upon environmental objectives. 

Linda Cadman's paper I think provides another example of this kind of 

thinking and philosophy. The objective of lowering the At through the 

use of tempering pumps had a very severe negative impact through 

entrainment of important fish species . So the objective of lowering the 

t through tempering pumps perhaps was the wrong objective to have set. 

Now, as I understand the case that Linda presented, there was no way to 

anticipate the relative effects prior to construction. There may have 

been data that could have been collected, experiments run, but my 

perception was there was no way to identify that initially, and that 

there had to be a dynamiC response including continued monitoring, to 

identify that effect , and in essence, reevaluate that objective of 

lowering the ~t. Mitigation only needs to be considered for those 

impacts determined to be adverse in nature. 

I will now outline the prinCiples of mitigation from the standpoint 

of the Fi sh and Wil d1 ife Servi ce. The Servi ce has for many years been 

involved in reviewing projects and providing mitigation recommendations 

492 
to agenc ies or private developers to mitigate tho se impacts the Service 

feels are adverse. I have some slides wh i ch il lustrate wha t I am talki ng 

about . A formal mitigation policy was developed i n 1981 which 

i ncorporated all the princ ipl es and concepts that the Serv i ce has used 

throughout the years and that each of you have used i n your project 

pl anning. Each of the speaker's papers i llustrates one or more of the 

mitigation princi ples th at are embodied in the Fish and Wil dli fe Service 

policy. I will review the definition of mitigation, as outl·ned by Or. 

Jim Brown and his paper on mitiga t ion banking. The President ' s Counc il 

on Environmental Quality defines miti gati on as a serie s of steps t o be 

taken to eliminate an adverse impact. As Or. Brown indicated, these items 

are not a menu of equivalent options fo r mitigation. Recognizing the 

definition as a sequence of mitig ation st eps that begin during the 

initial pl anning stage of the project wi ll help speed the approval of the 

project and reduce the need for expen sive modifications l ater on i n he 

regulatory process. 

Ross Wilcox 's paper outlined principles th at address all of the 

definitions of mitigation . I will address Ross' efforts later because 

they are very creative; they are innovative and diffe rent from 

application of the term mit igation. Linda Cadman's paper on the use of 

tempering pumps relates to minimiz ing impac t and rectifying the impact 

over time. There was an effec t that was determined later on; that effect 

wa s subsequently reduced or eliminated over t ime. Robe rt Davis' paper on 

angled screens focused on minimizing impact. Roger Rul ifson 's paper 

focused on the first step -- avoiding the impact . Roger's paper reflects 

a possible future for power generation that , as biologists and project 

managers, we need to think about so that we can understand and develop 

ways to avoi d an impact for the mutual benefit of both the company and 

the agencies. Or. Jim Brown's presentation focused on ways to compensate 

for unavo idabl e losses. Cha rl es Zi mmerman ' s paper addressed all the 

principles in a formal sense of a major plann ing project for a power 

generation complex that was extremely successful . 

The Fish and Wildlife Service mitigation process covers all feder al 

projects and private projects th at require a federal permit or license. 

The Fish and Wil dli fe Service reviews and recommends actions; t he agency 

493 
or the private project developer then implements those actions. The 

purposes of the policy are to: 1) assure consistent and effective 

recommendations that will conserve important fish and wildlife; 2) to 

facilitate balanced development and multiple use of natural resources; 3) 

to allow other agencies and developers to anticipate Service 

recommendations; 4) to reduce delays and conflicts; and 5) to clarify 

that it is not an acre -for-acre policy . This policy can apply to both 

habitat losses as well as losses of individuals or population impacts. 

The preferred approach to mitigation is to provide information in a 

form and in time to avoid or minimize fish and wildlife losses as part of 

the initial project design. Roger Rulifson attempted to do that for us. 

He provided information for understanding and developing ways to mitigate 

those impacts. Charles Zimmerman gave us a more recent example of 

applying the principle to a major power complex successfully . It is 

clear to me that Mr . Zimmerman identified environmental objectives early, 

developed an information base, determined what each of the agencies' 

requirements were, added enhancement features, and in a very cooperative 

way undertook a very successful project. 

The first major aspect of the Fish and Wildlife Service mitigation 

policy is to establish mitigation goals by resource category (Table 1) . 

As I indicated earlier, not all impacts are adverse and, in some cases, 

some impacts are more adverse than others. The Servi ce has recogni zed 

this by establishing a number of resource categories that include 

designation criteria and migitation goals. Please note that, depending 

on the value and scarcity of the resource involved, the mitigation goal 

ranges from complete preservation of the area to no compensation required 

at all, only efforts to minimize loss. The establishment of these 

migitation goals early in the process is important. Mitigation goals are 

essential and assist in developing the resource objectives. The resource 

objectives will, in fact, be used to apply the criteria of the mitigation 

pol icy to those species that are selected. We recommend avoidance or 

full compensation for the most valued resources and that the degree of 

mitigation correspond to the importance and scarcity of the resource. 

The determination of importance is based on BPJ technology, that is, 

the ~est frofessional Judgment of the involved biologists. If you think 

494 
Table 1. Mitigation Policy. 

RESOURCE HABITAT MITIGATION 

CATEGORY CRITERIA GOAL 

1 HIGH VALUE NO LOSS 

IRREPLACEABLE 

2 HIGH VALUE IN-KIND 

SCARCE 

3 HIGH TO MEDIUM NO NET 

ABUNDANT LOSS 

4 MEDIUM TO LOW MINIMIZE 

LOSS 

495 
about that, you will no dou bt conclude that majority of environmental 

decisions today involve BPJ as opposed to BPT or BAT . Now, in terms of 

this policy, I will expla in t he miti gat ion goal. In resource category 

1, because that habitat are a is irrep1acab1e, limited and of extremely 

high value, the biological princ i ple is that, since it cannot be 

replaced, we will not tolerate any loss. Resource category 2 has high 

value for evaluation species and the habitat itself is scarce. However, 

it can be compensated for, through creation of additional habitat of that 

same kind. So in-kind compensation is the mitigation goal for resource 

category 2 habitat. 

An example of a resource category 2 habitat mi ght be a bottoml and 

hardwood swamp. We cannot simply say that bottomland hardwood swamps 

have to be mitigated and compensated for in-kind. The reason is that not 

all bottomland hardwood swamps are equally valuable to wildlife. For 

instance, a five acre bottomland hardwood swamp area in Louisiana acres 

we called a resource category 4 because, in that situation, it had a low 

species value. The bottomland hardwood swamps of the Atchafa1aya River, 

though, have tremendous wildlife value, and we would designate those 

bottomland hardwood swamps as a resource category 2 and strive to achieve 

no net loss and in-kind compensation for the losses of bottomland 

hardwood habitats. 

The Service has developed a number of impact assessment 

methodologies. The primary guideline is to consider the impact in terms 

of the di fference between the future wi th the project and the future 

wi thout the project. The Service seeks to evaluate habitat value in 

biological terms instead of economic terms and has developed a specific 

methodology to do so. That methodology is based on subjective judgment, 

in part. It is also based on data analysis and interpretation, and if 

any of you are interested, I have a Habitat Evaluation Procedures 

Suitability Index for the bald eagle that you can look at so you can get 

a feel for how that process works. But once you select your species, you 

can determine the relative value of that habitat based on the life 

history and habitat requirements of a particular animal. This can be 

quantified and used in developing an objective analysis of what is 

necessary to mitigate losses for that particular animal. In the 

496 
endangered species area, we have not yet developed a specific methodology 

that deals with direct impacts to the animals. The habitat evaluation 

procedures will apply to endangered species, as I just indicated in the 

bald eagle example. 

In the case of entrainment or impingement where you are having 

impacts on the animals themselves with no direct impact to the habitat , 

there are no specific methodologies that have been developed for 

quantifying or developing a mitigation strategy. Instead, we develop 

mitigation strategies based on our best professional judgement. We try to 

remain as flexible as possible; I do not want to leave you with the 

impression that we have a mathematical formula which spits out a 

mitigation plan, but we do have both quantitative and qualitative methods 

for determining a mitigation plan for a given area. 

The Service also requires that its mitigation recommendations be cost 

effective in terms of achieving the mitigation goal. We ask our 

biologists to consider the economic cost of recommended strategies and to 

recommend the least costly one. We also encourage the project sponsor to 

incorporate funding for mitigation as a legitimate project cost and to 

carry out any compensation plan at the nearest site possible within the 

project area. Although, given our flexible policy, it is possible for 

the project sponsor to mitigate and compensate for resources lost off 

site. Now I will give you some examples of how the Service 

implements its policy. 

The first example is a very simple set of situations that could apply 

to the siting of a major power generating facility. Application of the 

Service's mitigation policy would result in the Fish and Wildlife Service 

strongly opposing the siting of the plant at site number 1 because of 

thermal impact on the major blue crab wintering area offshore from the 

proposed out fa 11 at plant site 1. Pl ease note that the power plant 

facility is located in a resource category 4 area, which has little 

wildlife habitat value. That does not mean that all upland habitats are 

resource category 4. A specific example related to the endangered redcockaded woodpecker; it requires mature pine forest habitat, upland 

habitat, old growth timber, and in that case , that habitat would be a 

resource category 1. So, it depends on what is there, what speci es are 

497 
selected and what your objectives are in terms of environmental goals for 

that area. 

Site number 2 is located in a resource category 2 wetlands with an 

outfall into the deep ocean, which has been designated as resource 

category 4. 

No mitigation is required for the ocean outfall. However, the wetland 

impact requires that there be avoidance and minimization as well as 

replacement of lost habitat because the goal for that particular resource 

category, is no net loss of habitat value. The cross hatched area could 

be scraped down and converted into a wetl and to offset the loss as a 

result of the acreage taken out by the power plant at site 2. 

Site number 3 is located in resource category 4 habitat. In thi s 

case, the only requirement is to minimize the footprint of the project 

site. The outfall again discharges into a deep ocean area that we have 

determi ned has no fi shery value that woul d be impacted by the outfall. 

This information can be invaluable to project planners and power plant 

management decision makers. Given a choice of sites, all else being 

equal, the manager would choose site 3 to build the plant. However, 

economics or land availability or some other factor may dictate that the 

power plant be sited at site 2. If it is, the additional adverse impact 

on the pub 1 i c resource can be accommodated through compensat i on of the 

habitat loss. However, if the plant manager's only option is site number 

1, break out the lawyers, because you are in for a fight. We have a good 

policy and a strong biological rationale to stop your project and require 

a closed cooling system. 

Next, I will discuss the concept of environmental values. As used by 

the Fish and Wildlife Service, the term enhancement refers to developing 

or improving fish and wildlife values beyond that which would exist 

without a project. None of the 1 ega 1 authorities that govern the Fi sh 

and Wildlife Service or other agencies require that fish and wildlife 

va 1 ues be enhanced duri ng economi c development projects. However, the 

Fish and Wildlife Coordination Act does require that enhancement 

opportunities be identified during project planning by the Fish and 

Wildlife Service. 

498 
Enhancement actions by a power company have three primary benefi ts . 

The first is improved public relations. Projects such as t hose 

undertaken by Florida Power and Light Company ~ave created tremendous 

positive feelings on the part of the public and the Fish and Wildlife 

Service toward this company. Charles Zimmerman's power complex example 

has no doubt generated similar positive feelings in the local community 

among the agencies involved. This improves future communication and 

resolution of conflicts that might arise later on. 

The second benefit is that the enhancement action can benefit t he 

company economically through the miti gation banking concept. The third 

major benefit to the company is the altruistic one from the standpo int of 

making things better than they were before. I have been told that t here 

are a number of chief executives that have been known to engage in this 

type of altruistic thinking , particularly if it creates a tax adv ant age. 

Figure 1 summarizes the concepts of mitigation and enhancement . The 

vertical axis represents the environmental condition of the project site . 

The pOint labeled zero is the existing condition without the project i n 

place. The scale measures the degree and characterization of impact as a 

result of the project, and it's labeled "better or worse". The scale 

indicates that the environmental conditions could improve or could be 

worse. The horizontal scale represents units of time starting from zero , 

which represent the point at which the project creates its impact running 

through time ten. The fi rst hori zonta 1 1 i ne represents a worst case 

environmental impact for a project with poor planning and no mitigation 

at all. Please note that the area of impact is proportionately large and 

continues throughout time forever, that is, without any form of 

mitigation. The cumulative effect of this type of project can certainly 

result ina breakdown in the structure and funct i on of the aquatic or 

terrestrial ecosystem and subsequent loss of important fish and wildlife 

species and other important environmental functions. That is one of the 

major problems that we are dealing with right now in terms of manatee 

protection. We have docks bei ng constructed whi ch have a very sma 11 

incremental impact that we cannot conclude would jeopardize the continued 

existence of the manatee, but nonetheless as those small incremental 

impact s add up, it certainly will jeopardize the continued existence of 

499 
the manatee. Docks do not ki 11 manatees, but the boats that use the 

docks do. Not all the boats, certa inly. 

The second horizontal line represents a project that had good 

environmental planning but no compensation of resources lost. Note that 

the area of impact has been min imized. The third horizontal line 

represents a project with no impact at all. The diagonal line labeled 

project number 1 represents a project with no adverse environmental 

impact for which enhancement features have been added. It turns out that 

Florida Power and Light power plants with their thermal discharges have 

generated no impact. The concern i n terms of the negotiations with the 

company years ago was that it may well create an adverse impact. A 

mitigation plan was developed based on that potential for adverse impact. 

As it turned out, it was not an adverse impact. So theoretically, 

anyway, those actions would be considered enhancement actions. The area 

to the right of the 1 ine represents environmental benefits that will 

accrue through time and for which the project sponsor could claim 

mitigation banking credit to offset future project losses. The line 

labeled project 2 represents a project with good environmental planning 

that has applied all aspects of mi t igation and enhancement. The project 

has been designed to minimize impacts, unavoidable impacts have been 

compensated, and enhancement act ions have also been des i gned into the 

project to create mitigation banking credit. The diagonal line labeled 

project number 3 represents a poorly planned project with a severe 

environmental impact for which full compensation was required. Please 

note that the area of impact to the left of the line is significantly 

larger than the area of impact for the well designed project. And at an 

economi cleve 1 it may have been more cost effect i ve for the project's 

sponsor to pay for good pl anning than to have to pay the additional 

incremental cost for mitigating the environmental resource damage. 

I certainly hope that this puts the papers presented during my 

session into perspective as examples of the various kinds of approaches 

for mitigation and enhancement. Creativity, innovation and trust are the 

key. 

I would like to thank my speakers for the illustrations they provided 

and offer the following summary comments. 

500 
1. Power generation planning should include environmental objective 

setting as well as economic and regulatory objective setting. 

2. Environmental objectives have the largest subjective component. 

They should be developed through a process of best professional judgment 

and with public input. 

3. An adverse env i ronmenta 1 impact on 1 y occurs when there is a 

difference between the des ired cond it i on and the actual cond it i on as a 

result of the project. Envi ronmenta 1 objectives must be defi ned as a 

prerequisite to defining adverse environmental impacts. 

4. Adverse environmental impacts can be avoided or minimi zed through 

good environmental planning at the earliest point in the project pl anni ng 

process. 

5. Mitigation measures should be evaluated in terms of ecolog i cal 

cost as well as the ecological benefits. 

6. Mitigation measures need to be maintained and reevaluated at 

period i c intervals to evaluate performance . 

7. Unavoidable adverse environmental impacts can be compensated for 

by replacing or substituting those resources lost by the action. 

8. Environmental tradeoffs may be necessary to compensate for 

resources lost; for example, creation of wetlands in return for loss of 

shallow water habitat. 

9. Positive environmental impacts can result from power generation 

activities. 

10. Enhancement action can build public and agency support for 

existing and future power generation activities and create economic 

va 1 ues through creation of mit i gat i on banks to reduce future costs of 

regulatory compliance . 

11. The process requires open communication, a desire on the part of 

all parties to accommodate each other's objectives, and a flexible 

regulatory setting within which to apply these principles. If it is done 

right, then everyone wins. 

I am going to close with one short example of a recent situation that 

the Fish and Wildlife Service was involved i n. It involved the L reactor 

wh i ch is oper ated at the Savannah River Plant . They needed to develop a 

cooling system and proposed to build a cooling lake. The impact of the 

501 
cool ing lake wo ul d have resulted i n a regulated flow that would have 

inundated Steel Creek . St eel Creek wa s used as a foraging area for the 

endangered wood stork and the Birdsv ille Colony, which is located 

approximatel y 30 mil es fr om the pl ant site, contains our most 

northernmost popul at i on of t he wood stork, with over 100 birds. We 

determi ned that Steel Creek is a foragi ng habitat for that part i cul ar 

population. Early in the process, we worked with the Department of 

Energy to develop a mitigation plan to offset the loss of Steel Creek. It 

became highly charged emot ionally and pol itically and, as you can imagine 

with anything that relates to nuclear energy or weapons development, 

everyone was offering opin ions . A typical example was a Scrawls cartoon 

in the Atlanta Journal Constitution showing three witches stirring a pot. 

The pot was labeled "the L reactor cool i ng lake" and the caption was 

"bubble, bubble, toil and trou ble. Cook the woodstork; fry his brain; 

another of God's creatures down the drain." 

Working in that highly charged atmosphere with the DOE and their 

personnel, we invited Audubon to assist us and we developed a mitigation 

plan which created alternate fo r aging habitat on Audubon land located 

north of the project site. That project cost DOE approximately half a 

million dollars to construct and involved the creation of a reservoir 

designed specifically to provide for aging habitat for the wood stork . 

Because they are tact i 1 e feeders wi th thei r bi 11 s, wood storks requi re 

specific water levels and size fis h to make a living. The reservoir was 

designed specifically for this type of foraging habitat. Many people did 

not think it would work and it involved a risk on our part, the Audubon's 

part, and the Department of Energy's part. The good news is that this 

summer over half of the Birdsville population of wood storks made 

extensive use of the Kathwood Lake mitigation site. The biologists feel 

that it was a tremendous success and will provide a more stable source of 

feeding area for the wood stork than did Steel Creek, which was subject 

to natural water fluctuat ions . 

I hope these review comments and my speaker's papers will help to 

stimulate such a win-win scenario in power generation planning. 

502 
SOME OBSERVATIONS ON AQUATIC IMPACTS OF 

POWER PLANT TRACE ELEMENT DISCHARGES 

Peter M. Cumbie 

Design Engineering Department 

Duke Power Company 

P.O. Box 33189 

Charlotte , North Carolina 28242 

ABSTRACT 

Trace elements discharged from fossil-fueled steam electric power pl an ts 

are frequently a source of concern in relation to possible toxic effects 

on aquatic 1 He or exceedances of water quality standards in recei vi ng 

waters. This paper discusses several aspects of trace element discharges 

and their effects on aquatic ecosystems. 

Factors which affect the potent i al for toxic effects include the mass of 

pollutant discharged, the rate of flow in the receiving water body , potential for bioaccumulation or biomagnification, interactions wit h 

chemical factors, temperature , presence of other toxics, and accumu lat ion 

in sediments. 

Pract i ca 1 examples of t he effects of these and other factors wh i ch may 

lead to no effect, limited effect, or severe effect on aquatic organisms 

are presented. Implications of observed effects for some widely-held 

assumptions concerning responses of aquatic life to toxic pollutants are 

discussed . 

503 
INTRODUCTION 

The purpose of th i s paper is to share experi ences with a trace 

element discharge problem. Although somewhat obvious when considered in 

retrospect, some of the problems described here were not readily 

interpretable upon first considerat i on . The case described here concerns 

the effects of selenium and arsenic discharges on fish and other aquatic 

organisms in Belews Lake, North Carolina. 

Belews Lake is a 1563-ha power plant cooling lake located near the 

city of Winston-Salem. Belews Lake received effluent from a fly ash 

settling basin at the Duke Power Belews Creek Steam Station from 1975 

through 1984. After consideration of various alternatives, a dry fly ash 

collection system was installed at the plant in 1984. This system 

eliminated wet sluicing of fly ash and discharge of fly ash sluice water 

from the settling basin to Belews Lake (Cumbie et ~, 1985). 

In 1976, less than two years after fly ash settling pond effluent 

began to enter Belews Lake, fish in the reservoir failed to reproduce and 

began to suffer excessive mortality , based on results of electrofishing, 

rotenone sampling, and observations of dead fish. All species were 

affected, but Centrarchids seemed to be most sensitive. Studies 

eventually showed that the discharge of selenium to the reservoir, with 

subsequent bioaccumulation by plankton, benthic organisms, and fish was 

the cause of these problems (Cumbie and VanHorn, 1978). Recent effects 

of selenium in the Kesterson Reservoir in California have brought 

national attention to this element as a subject of concern in aquatic 

ecosystems (Saiki, 1985). Selenium and other trace elements have 

accumulated in the Kesterson system from agricultural drainage in the SAn 

Joaquin Valley, resulting in mortality of fish and bird life. But in 

1976, the potential for selenium to cause ecological problems in aquatic 

systems was not generally recognized. 

The Belews Lake selenium problem has been described in a number of 

reports and technical papers (Cumbie and VanHorn, 1978; Cumbie, 1978; 

Cumbie et ~, 1985), and the details of these studies will not be 

presented here . Instead, thi s paper di scusses a number of issues with 

application to trace element discharges in other water bodies. It is 

hoped that these observations will stimulate further research and 

504 
heightened appreciation of factors contributing to trace element effects 

on aquatic life. 

THE DISCHARGE AND THE SYSTEM 

Initially, the nature of the receiving water system and its relat ion 

to trace element effects may be considered. This subject is discussed 

first because it has implications for many types of discharges, not just 

for trace elements or for any particular type of chemical compound . 

Belews Lake is unusual because of its lengthy retention time of 

approximately 1500 days or about 4.5 years when the combined effects of 

1 imited natural tributary streamflow and evaporative losses due to the 

power plant heat load are considered (Cumbie, 1978 ; Weiss and Anderson , 

1978) . It is obvious that discharges of a conservative pollutant to suc h 

a system would have a great potential for toxic effect, especially if the 

quant ity di scharged s i gnifi cant 1 y exceeded the natural inputs of the 

substance. The design of the Belews Creek Steam Station called for wet 

sluicing of fly ash to an ash settling basin, from which the sluice water 

was di scharged back to Belews Lake because of the quant i ty of water 

involved and the need to maintain the water level in the reservoir. It 

was also desired to make the project self-contained in a regulatory 

sense, with the alternative being to discharge ash basin effluent to the 

nearby Dan River. 

Although the potential for problems with a discharge of conservative 

pollutants to a system of great retention time seems obvious, it has not 

over the past several years prevented outside observers from questioning 

why, if selenium discharges caused serious problems with fish populations 

in Belews Lake , ostensibly similar discharges did not cause the same 

problems in other receiving waters. It has developed that other systems 

receiving selenium discharges without associated deleterious biological 

effects differed from Belews Lake in terms of a much shorter retention 

time , greater productivity or sedimentation rates , or in other important 

respects. This presents something of a paradox : effects of selenium 

discharged to Belews Lake were a product of a particular combination of 

factors including retention time, general water quality, biological 

producti vity, chemical properties of coal and fly ash, and the quantity 

of discharge (Cumbie, 1978, 1980) . Still, other systems may share a 

505 
sufficient number of t hese propert ies that the problems experienced in 

Be 1 ews Lake can offe r useful gu i danc e t o i nterpretat i on of effects of 

other trace element discharges. 

CONTINUOUS DISCHARGES VERSUS SPILLS 

The Belews Lake ash basin effl uent wa s a continuous discharge which 

occurred as a recognized operating fea t ure of t he power plant (Cumbie, 

1978; Cumbie et ll, 1985). Although t he introduction of selenium to 

Belews Lake did not cause immediate responses in the form of a fish kill 

or violations of numerical wat er qual ity standards, the continued 

discharge eventually resulted i n a suffic ient loading of selenium in the 

system to cause extermi nat i on of most fi sh in the main bas in of the 

reservoi r. The Kesterson Reservoi r case iss imil ar in the sense that 

introduction of selenium to the reservoir and associated evaporation 

ponds from agricultural drainage has been continuous (Saiki, 1985). 

Large, one-time releases of tox i c substances to receiving water have 

caused more spectacul ar results i n the form of fi sh ki 11 s, but such 

problems have general ly proved to be short-lived. In these cases, 

acutely toxic conditions are devel oped , but are rapidly abated by the 

combined effects of chemical decay, precipitation, or dilution of the 

respons i b 1 e agent. Methods fo r eva 1 uat i ng cont i nuous di scharge effects 

must obviously be different from those which are used for spills. The 

latter often attrac t immediate attention from operating personnel, 

regulators, and the general public . In contrast, more insidious effects 

of continuous discharges may go largely unnoticed, even when highly 

significant ecological responses are occurring. As discussed below, 

routine monitoring programs may not provide reliable indications of these 

effects as they develop. 

MULTI-ELEMENT DISCHARGES 

It may be difficult to separate the effects of various trace elements 

which are present in a discharge . The impacts of selenium in Belews Lake 

have been difficult to separate clearly from possible effects of arsenic, 

whi ch was also present in the ash bas in effl uent. The presence of 

arsenic in the Belews Lake system has tended to draw more attention from 

outside observers. This is apparently due to greater familiarity with 

506 
arsenic as a toxicant, compared to selenium. In fact, the levels of 

arsenic in Belews Lake water did not exceed water quality standards, and 

levels accumulated in sediments have not been sufficiently high to lead 

to predictions of direct effects (Cumbie, 1978; U.S. EPA, 1979). The 

situation with selenium differed, since available data indicated that the 

quantities of selenium alone taken up by fish in Belews Lake were 

sufficient to cause toxic effects and mortality, without additional 

effects of any other agents that might be associated with selenium or 

otherwise present (Goettl and Davies, 1976). Recent experimental data 

obtained at Carolina Power and Light Company (S.E. Woock , personal 

communication) indicate that selenium alone can account for virtually all 

of the adverse effects on fish reproduction which have occurred in Belews 

Lake. 

Synergistic or additive effects of selenium, arsenic or other 

substances on fish populations in Belews Lake must be considered . 

However, water quality criteri a for constituents other than se 1 eni urn, 

including arsenic, were not exceeded in Belews Lake (Cumbie, 1978; Weiss 

and Anderson, 1978). although synergistic or additive effects of toxic 

pollutants may be important in some cases, scant available data suggest 

that these effects occur with acutely toxic exposure concentrations, 

rather than with chronically toxic concentrations (Spehar and Fiandt, 

1985). If a single element is documented to be capable of causing an 

observed effect, treatment of the identified problem is appropriate until 

additional evidence implicates other causal factors. A theory or 

hypothesis dealing with toxic effect should be made no more complex than 

necessary to explain the phenomena of interest. Other cases will 

undoubtedly be encountered in which adverse effects of particular agents 

can be recognized, even when other toxicants are suspected to be present. 

A focus on evaluation of synergistic effects would often not be an 

efficient approach to a solution for such a problem. 

WATER QUALITY AND STANDARDS 

Water quality criteria for selenium and arsenic which were available 

i n 1976 would not predict adverse effects of these elements in Belews 

Lake. EPA "Red Book" criteri a for selenium (U.S. EPA, 1976) at 10 ug/l 

suggested that lake water selenium levels of 8 to 12 ug/l would not lead 

507 
to problems with fish populations . This caused attention to shift 

temporarily to other possible causes for fish population declines, such 

as diseases, pesticides, adverse physical conditions, excess heat, or 

water level fluct uations. All of these were eventually eliminated as 

causes of the problem. As recent ly as 1982, the EPA national water 

quality criteria for selenium were set at 35 ug/l (U.S. EPA, 1980). This 

criterion is greatly in excess of the selenium concentrations detected in 

Belews Lake at the time that extreme ly high bioaccumulation of selenium 

was occurring in fish. Levels of 30 top 50 ppm (wet weight) were 

detected in fish muscle tissue , compared to normal values of about 1 ppm. 

This phenomenon was associated with widespread mortality of many species, 

and a more-or-less compete fail ure of reproduction among all species 

(Cumbie and Van Horn , 1978) . 

The problem with application of water quality criteria stemmed from 

the fact that the observed effects were not caused by direct exposure to 

selenium in the water column, but were instead related to sediment and 

food chain contamination (Cumbie, 1978; Finley, 1985). Water quality 

criteria did not adequately deal with this situation. The EPA national 

criteria only consider bioaccumulation as it affects human consumption of 

fish and shellfish. Criteria are not developed based on direct effects 

of bioaccumulation in aquatic food chains. The State of North Carolina 

has revised its water quality standards for selenium to 5 ug/l in ponds, 

lakes, and reservoirs, based in part on effects seen in Belews Lake. EPA 

does not generally recognize a role for field observations in validating 

the accuracy of water quality criteria based on laboratory toxicity data, 

or in suggesting site-specific revisions to national criteria (U.S. EPA, 

1986). 

SENSITIVE SPECIES 

Several interesting observations have been made regarding the 

apparent sensitivity of various species to presence of selenium in Belews 

Lake. These observations have applications for other cases. 

It has been stated that benthic organisms exhibit greater sensitivity 

than other forms to polluted conditions because they are long-term 

residents in polluted waters and tend to integrate effects of pollutant 

exposure over time. This view is largely based on effects of elevated 

508 
temperature, low dissolved oxygen, or acutely toxic chemicals on stream 

benthos (Garton and Harkins, 1970). As fish populations decl ined in 

Belews Lake, extensive studies of benthic organisms revealed no 

recognizable abnormal changes in benthic biomass, diversity, or spec ies 

presence (Weiss and Anderson, 1978) . The only unusual feature s noted 

were a tendency for benthos to attain rather large body sizes and t o be 

plentiful in appropriate habitats. This was apparently due to the 

absence of predations on these organi sms as fi sh di sappeared from the 

lake. Therefore, experience in Belews Lake indicates that benthos are 

not necessarily sensitive indicators of trace element pollution whi ch may 

have severe effects on other fauna . 

More recent data indicate that Daphnids tend to be the most sensiti ve 

forms in acute toxicant exposures (U.S. EPA , 1986) . However, zooplan ton 

data revealed no unusual changes in species or population l evels in 

Belews Lake. Studies of zooplankton , peri phyton , phytoplan kton, and 

benthos undertaken to evaluate effects of temperature el evat i on j udges 

conditions in the Belews Lake ecosystem to be normal for the region i n 

1976 , at the very time when fish populations were declining (Weiss and 

Anderson, 1978). These resu l ts were in contrast to the commonly advanced 

position that one could discern the impacts of unsuspected pollutants at 

an early stage by conducting broadly-based monitoring studies of 

plankton, benthos, or other biota. Observat ions in Belews Lake emphasize 

that adverse effects on fish populations may occur unaccompanied by 

related observed effects at lower trophic levels. It was concluded that 

directed scientific investigation, rather than survey data, was required 

to achieve an understanding of the factors affecting fish populations in 

Belews Lake. 

Finally, the fathead minnow (Pimepha7es prome7as) appeared in Belews 

Lake as the native Centrarchids and Ictalurids were eliminated. It is 

interesting to note that the fathead minnow is commonly used as an 

ap prop riately sensitive test organism in studies of toxicity of trace 

met als or other substances in the laboratory (Peltier and Weber, 1985). 

It appears that in Belews Lake, the posit i on of the fathead minnow in the 

troph ic system, and its tendency to use relatively shallow, near-shore 

habi t at, prevented it from being exposed t o the more contaminated 

sediment areas and associ ated food organi sms. Sediment data i nd i cate 

509 
that selenium levels increased with increasing depth and distance from 

shore (Cumbie, 1984) . 

The possibility of species adaptation or acclimation to toxicant 

exposure can also have important implications for programs intended to 

deal with effects of toxics. In acute toxicity tests, green sunfish 

(Lepomis cyanellus) from Belews Lake were significantly more resistant to 

toxic effects of sodium selenite than hatchery green sunfish which had 

not been previously exposed to selenium (Cumbie and Velte, 1986). The 

increase in selenium resistance was hypothesized to have resulted from 

the long-term exposure of the tested fish stocks to selenium in the food 

chain of Belews Lake. This suggested that survival of certain native 

fish species in the lake under the existing contaminated conditions could 

not necessarily be taken as an indication that conditions would allow 

survival of stocked hatchery f ish intended to facilitate recovery of game 

fish populations. 

SYSTEM LOADINGS AND ECOLOGICAL EFFECTS 

The Belews Lake case i 11 ustrated that the concentration of a trace 

element such as selenium in an effluent may not in itself give an 

indication of the potential for effects in the receiving water system. 

On the other hand, a simple load calculation may give valuable insight 

when compared to natural loadings from tributaries. In Belews Lake, some 

simple calculations based on effluent selenium concentration, effluent 

flow rate, tributary inflows, and background selenium concentrations (see 

Cumbie, 1978, 1979; Cumbie et , 1985) indicated that the selenium load 

from the Belews Creek ash basin effl uent (100 to 200 ug/l total selenium, 

average flow rate about 0.6 m3/sec) to Belews Lake was more than 32 times 

the natural input. Ambient selenium levels in tributary streams were 

below the 1 ug/l detection limit for analysis. Thus, the relative 

increase in selenium mass loading was at least one to two orders of 

magnitude above natural inputs. In a system with a high retention time, 

an increase of this magnitude in the input of a conservative substance 

such as selenium should be expected to have a high probability of 

producing adverse effects. Specific effects would depend on potential 

for bioaccumulation and distribution among different ecosystem 

compartments. In Belews Lake, the increased input was rapidly reflected 

510 
in marked accumulation of selenium in the sediments of the reservoir and 

in all biological compartments which were examined. 

LOOKING FOR THE INEXPLICABLE 

Occurrences of unusual events or conditions should be suspected as 

indicators of developing problems, but recognition of the significant 

events and their interpretation may be very difficult. In Belews Lake, 

such an early event was a large die-off of blueback herring (A7osa 

aesUva7is) which occurred in April 1986, preceding the general failure 

of fish reproduction during the following summer (Duke Power Company, 

1976). This open-water species feeds on plankton, and it may have 

succumbed due to selenium poisoning in its food chain as selenium levels 

increased in the reservoir during early 1976. Zooplankton in Belews Lake 

were later found to contain up to 100 ppm or more (dry weight) of total 

selenium, many times the levels which have been shown to cause mortality 

in fish feeding experiments (Cumbie, 1978; Goettl and Davies, 1976). 

Seasonal di eoffs of Cl upeids (threadfi n shad, Dorosoma petenense) are 

relatively common in certain southeastern reservoirs due to low water 

temperatures in the winter months, but these usually occur in December to 

February, not in the spring when water temperatures are rising. The 

possible significance of a spring fish kill involving blueback herring 

was not recognized at the time. 

Another condition noted in Belews Lake fish in 1976 was "blindness", 

a clouded lens condition, which was common in Lepomids in the main 

reservoir. The significance of this condition, a relatively non-specific 

response to a variety of agents, could not be determined, although it was 

widespread in the lake and did not seem to occur in fish in the less 

selenium-contaminated headwater areas of Belews Lake. Recent feedi ng 

experiments with selenium at Carolina Power and Light Company (S.E.Woock, 

personal communication) have shown that this clouded eye lens condition 

can be caused in the laboratory by selenium poisoning in bluegills 

(Lepomis macrochirus). 

Finally, exophthalmus or "popeye", general ized edema and swell ing, 

and hemorrhaging of blood vessels in the eye, gill, and tail regions is a 

reported symptom of selenium poisoning (Ellis et ~ .. L 1937; Sorensen et 

li, 1984). These conditions occurred commonly in fishes in Belews Lake 

in 1977-1978, and in combination with water chemistry data and marked 

511 
bioaccumu1ation of selenium i n fish mu scle tissue and internal organs led 

to the hypothesis that selenium poisoning was responsible for the decline 

in Belews Lake fish populations which began in 1976 (Cumbie and Van Horn, 

1978). 

IMPORTANCE OF SIMPLE PHYSICAL CHARACTERISTICS 

Propert i es of vari ous ecosystems may cause them to respond rather 

differently to similar pollutant discharges. In Belews Lake, the power 

plant full-load cooling water pumping rate of 33 m3/sec results in a 

complete circulation of the lake volume of 228 x 103m3 in about 40 days. 

This creates a strong circulation pattern about the main portion of the 

reservoir, and led to a rather uniform distribution of dissolved selenium 

in the main basin of Belews Lake (Cumbie, 1978). In contrast, a 

reservoir with less circulation might be expected to exhibit a pollutant 

concentration pattern in water or sediments in which more accumulation 

would be seen nearer the source of the discharge. Or, in a stream or 

"run of the river" impoundment, low retention time might limit areas of 

effect to downstream locations, or prevent significant accumulations from 

developing at all. 

Belews Lake stratifies strongly during the summer and early fall, and 

during the period from 1976 to 1984 developed a strong oxygen deficit and 

reducing conditions in the hypolimnion by late summer. This resulted in 

an obvious pattern in selenium concentrations, with peak concentrations 

developing in the summer, which could be readily related to the 

stratification of the reservoir and the chemical properties of selenium 

compounds (Cumbie, 1978; Weiss and Anderson, 1978). The low oxidationreduction potential developed in the Belews Lake hypolimnion was 

hypothesized to reduce selenium to selenite or to insoluble elemental 

selenium, which was deposited in lake sediments (Cumbie, 1978, 1984). 

This process was critical in developing the selenium-contaminated benthic 

food chain which contributed to fish mortality. In other systems, where 

development of a reducing hypo1 imnion may not occur, the deposition of 

selenium in sediments would be expected to be less pronounced. 

In the main basin of Belews Lake, selenium and arsenic levels in 

sediments were high relative to background conditions (Cumbie, 1984). 

But in up1ake areas, accumulation in sediment was much less because of 

limited intrusion of the selenium-bearing waters into the headwater 

512 
areas, and because of a much higher rate of sediment deposition due to 

erosion in the watershed. 

The productivity of Belews Lake is quite low (Weiss and Anders on , 

1978), and the rate of accumulation of organic detritus and sediment is 

low. Deposition of inorganic stream-borne sediment is also very limited 

in the main reservoir because of limited tributary inflow and removal of 

sediment in the headwater areas. Therefore, sediment seleni um and 

arsenic reached higher levels in Belews Lake (30 to 50 ppm total selenium 

or arsenic in surficial sediments) than those which have appeared in 

other, more productive reservoirs which have been subject to selenium 

loading from power plants (Carolina Power and Light Company, 1981; 

Cumbie, 1984). The high sediment selenium levels in Belews Lake led to a 

marked uptake of selenium, but not of arsenic, in fish through the food 

chain, with attendant reduced reproduction and increased mortality. 

An example of a different result is the case of Adair Run, a West 

Virginia stream which received ashpond effluent resulting in average 

instream concentrations of approximately 40 ug/l total selenium 

(Nicholson, 1982; Whitaker, 1982 ; Sepcht et li, 1984). In this system, 

benthic organisms and stream fishes were not affected by the selenium 

exposure. However, sediment in the stream accumul ated only 1 to 2 ppm 

selenium, with most of the element apparently moving through the system 

in dissolved form. This case emphasizes the critically important effects 

of retention time, oxidation-reduction potential , and sediment deposition 

on the effects of certain trace element discharges, and the water column 

concentrations which may be tolerated in different ecosystems. 

CHEMICAL FORMS SHOULD BE INVESTIGATED 

Knowledge of the chemical fo rms of toxic elements present in aquatic 

systems can be decisive in enabling us to understand their effects on 

biota and distribution in the ecosystem. In Belews Lake, circumstantial 

ev idence indicated that selenate was formed in the fly ash sluicing 

system at pH 9 to 10, facilitating dissolution and discharge of selenium 

from the ash settling basin. In the lake, selenate appears to have been 

con vert ed to selenite, which could be adsorbed by particulates and 

settled to the sediments, or further reduced to the insoluble elemental 

fo rm in t he summer hypolimnion, again resulting in deposition to 

sediment s (Cumbi e, 1978, 1980, 1984), Selenite is more toxic to aquatic 

513 
life than selenat e (U.S. EPA, 1980). Behavi or of selenium in the San 

Luis Dra in and Kesterson Reservoir systems may differ from that observed 

in Belews Lake if more al kaline conditi on s fa vor maintenance of selenium 

in the form of selenat e (see Saiki, 1985). Our present understanding of 

redox transitions and kinetics of many chemical reactions of interest in 

trace element toxicity is r udimen tary. This is a fruitful area for 

future research. 

CONCLUSIONS 

Trace element disch arges present 

environmental scientist or engi neer 

significant 

faced with 

challenges to the 

interpretation of 

responses of aquatic systems to such discharges. This discussion of 

experiences with selenium i n Be lews Lake has sought to illustrate a 

variety of factors which shou l d be considered in order to determine 

whether a discharge is having significant effects in a particular 

ecosystem. Since different ecosystems respond differently to pollutant 

di scharges, dependi ng on t hei r i ndi vi dual propert i es, a di scharge with 

significant adverse effects in one loca t ion may have no discernible 

effect in another 1 ocat ion . Further research on ecosystem responses to 

trace element loading is needed to enhance our ability to distinguish 

these possibilities. 

REFERENCES 

Carolina Power and Light Company. 1981. Hyco Environmental Report, 1979-

1980. Volume II I: Bi ol og i cal and Chemi cal Studies. Carolina Power 

and Light Company , New Hil l , N.C. 

Cumbie, P.M. 1978. Belews Lake En vironmental Study Report : Selenium 

and Arsenic Accumulation . Duke Power Company Tech. Rep . Ser. No. 78-

04. Duke Power Company, Charlotte , N.C. 64 pp. 

Cumbie, P.M. 1980. 

Conditioning on the 

Company Tech. Rep. 

N.C. 62 pp . 

Effects of pH Adjustment and S03 Fly Ash 

Belews Creek Stream Station Ash Basin. Duke Power 

Ser. No. 80 -01. Duke Power Company, Charlotte, 

Cumbie, P.M. 1984. Deposition of sel enium and arsenic in sediments of 

Belews Lake, North Carol i na . Pp . 5,1- 30 In : Workshop Proceedings: The 

Effects of Trace Elements on Aquatic Ecosystems. Report No. EA-3329. 

Electric Power Research Insti tut e, Palo Alto, CA. 

Cumbie, P.M . , D.P. Roche, and W.J. McCabe. 1985. Coal ash disposal and 

water quality: a case study. Presented at: Annual Meet i ng of the 

American Society of Civil Engineers, Detroit, MI . Oct. 25, 1985. 7pp . 

514 
Cumbie, P.M . and S.L. VanHorn. 1978 . Selenium accumulation associated 

wi th fi sh mortality and reproduct i ve fa il ure . Proc. Ann. Conf. SE 

Assoc. Fish and Wildl. Agenc i es. 32:612-624 . 

Cumbie, P.M . and J.S. Velte. 1986. Comparison of Selenium Resistance in 

Belews Lake and Hatcher Green Sunfish (Lepomis cyane7rus) , Res . Re pt. 

PES/86-13 . Duke Power Company, Charlotte, NC . 23pp. 

Duke Power Company . 1976 . Fish Impingemen t Study - Bel ews Creek. 

En vi ronmental Engineeri ng Section, Design Engineering Dept. Duke 

Power Co . , Charlotte, NC . 19pp. 

Ellis, M.M., H.L. Motley, M.D. Ellis, and R.O. Jones. 1937 . Selenium 

poisoning in fishes. Proc. Exper. Biol. Medicine 36 : 519-522 . 

Finley, K.A . 1985. Observations of bluegills fed seleni um -cont ami nated 

Hexagenia nymphs collected f rom Belews Lake, North Carolina. Bull. 

Environ . Contam. Tox i col. 35:816-825. 

Garton, R.R. and R. D. Harkins . 1970. Gui delines: Biolog i cal Surveys at 

Proposed Heat Discharge Si tes . U.S . Envi r onmental Prot ecti on Ag ency , Corvallis, OR. 99pp. 

Goettl, J.P. , Jr. , and P.H. Davies . 1976. Wate r Pollut i on Studi es. Pp. 31-34 In: Job Progress Report , Federal Aid Project F-33-r-ll . Colorado Div. of Wildlife, Fort Collins, CO. 

Nicholson, R.B. 1982 . An Assessment of the Environmental Effects of Coal 

Ash Effl uents Usi ng Structural and Function Parameters of Aufwuchs 

Communities . M.S. Thesis, Biology Dept. , VA Polytechnic Inst. and 

State Univ., Blacksburg, VA . 87pp. 

Pelt i er, W.H. and C.1. Weber. 1985. Methods for Measuring the Ac ute 

Toxicity of Effluents to Freshwater and Marine Organisms, Third Ed. 

EPA/600/4-85/013. U. s. Envi ronmenta 1 Protect i on Agency, Offi ce of 

Res . and Development , Cincinnati , OH . 216pp . 

Saiki, M.K. 1985. Concentrations of selenium in aquatic food chain 

organisms and f ish exposed to agricultural tile drainage water. Pp. 

25-33 In: Selenium and Agricultural Drainage. Proc. of the Sec. 

Selenium Symp. Berkeley, CA. March 23 , 1985. The Bay Inst. of CA, 

Tiburon , CA. 

Sorensen, E.M.B., P.M. Cumb i e , T. L. Bauer, J . S. Bell, and C.W. Haroan. 

1984. Hi stopathological , hematological, condition factor and organ 

weight changes associated with selenium accumulation in fish from 

Belews Lake, North Carolina. Arch . Environ. Contam. Toxicol . 13:153 - 162 . 

Specht, W.L., D. S. Cherry, R.A. Lechleitner , and J.Cairns, Jr. 1984. 

St ruct ur a 1 , funct i on a 1 , and r ecovery r esponses of stream 

invertebrates to fly ash effluent. Can. J . Fish . Aquatic Sci. 

41:884 -896. 

515 
Spehar, R.L., and J. T. Fiandt . 1985 . Acute 

Quality Crite ria -Bas ed Metal Mixtures 

EPA/600/3-85/ 074 . Offi ce of Research 

Duluth, MN . 46pp. 

U.S. Environmental Protect ion Agency . 1976 . EPA/440/9-76-023. U. S. EPA, Washington, 

and Ch ronic Effects of WAter 

on Three Aquat i c Spec i es . and Development, U.S. EPA, 

Qual ity Cri t eria for Water. 

DC. 501pp. 

U.S. Environmental Protection Agency. 1979. Arsenic. Ambient Water 

Qua 1 ity Criteri a. Criteri a and Standards Di v., Offi ce of Water 

Planning and Standards. U.S. EPA, Washington, DC. 

U.S. Environmental Protect ion Agency . 1980 . Ambient WAter Quality 

Criteria for Selen i um. EPA/440/5-80 -070 . Office of Water Regulations and Standards, U.S. Environmental Protection Agency, Washington, DC. 

U. S. Envi ronmenta 1 Protect i on Agency. 1986. Ambi ent WAter Quality 

Criteria for Selenium (IV). Office of Water Regulations and 

Standards. U.S. EPA . Was hington , DC . 

Weiss, C.M. and T.P. Anderson . 1978 . Belews Lake: A Summary of a Seven - Year Study (August 1970-June 1977) to Assess Environmental Effects of 

a Coa 1- Fired Power Pl ant on a Cool i ng Pond. Dept. of Envi ron. Sc i . 

and Eng., Univ . of North Carol i na. Chapel Hill, NC . 138 pp . 

Whittaker, J.B. 1982. Field and Laboratory Determined Behavioral 

Avoidance and Alterations of Fish Gill Histological Responses to 

Acidic and Alkaline pH Condi t ions. M.S. Thesis, Biology Dept., 

Virginia Polytechnic Inst . and State Univ. Blacksburg, VA . 96pp. 

516 
RADIOCESIUM KINETICS IN THE 

YELLOW-BELLIED TURTLE (Pseudemys scripta) 

Eric L. Peters 

I. Lehr Brisbin, Jr. 

Savannah River Ecology Laboratory 

Aiken, South Carol ina 

ABSTRACT 

The recent Chernobyl accident has demonstrated the potent ial fo r 

radionuclide contamination of aquatic ecosystems. Although the in iti al 

release into the environment may be local i zed, animals inhabiting such 

contaminated areas may eventually serve as vectors of radionuc l ide spread 

into uncontaminated regions. In long -lived animals, such as the yell ow- bellied turtle (Pseudemys scripta), the animals themselves may also serve 

as a reservoir of such contaminants, accumulating body burdens of 

radionuclides and releasing them slowly into the environment over 

extended periods of t ime . Essential to the determination of the fate of 

radionuclides released i nto aquatic ecosystems is an understanding of the 

mobility and retention of these substances in resident biota. To date , radionuclide uptake rates have been calculated from radionuclide 

elimination rates in a wide variety of aquatic species using the model of 

Davis and Foster. We tested this model by comparing the uptake kinet i cs 

calculated from radiocesium elimination rates of turtles held both in a 

controlled environment chamber and in an outdoor experimental pond'1~tth 

the actual radiocesium uptake rates of turtles introduced into a Cs 

contaminated reservoir on the Department of Energy's Savannah River Plant 

near Aiken, South Carolina. There were no significant differences 

between the turtles' indoor and outdoor eli mi nat i on rates, both groups 

showing similar biological half-times. The relationship between the 

uptake and elimination rates was less clear; a significant lag period of 

1-2 weeks was observed before the onset of radiocesium uptake. This lag 

period was attributed to a presumed delay in the onset of a regular 

feeding rate, while the turtles became accustomed to locating food in an 

unf amiliar area. This is in contrast to the Davis-Foster model, which 

assumes a uniform rate of radioisotope intake. Our results suggest that 

estimates of radionuclide dynamics (i .e., time to maximum radionuclide 

contami nation in an individual organism) may not be estimatable from 

labor atory elimination data alone. 

517 
POLLUTANT ENRICHMENT OF SEDIMENTS FROM COOLING WATER 

DISCHARGE IN BAHIA DE GUAYANILLA , PUERTO RICO 

Rafael Almodovar-Ferrer 

Jose Manuel Lopez 

Center for Energy and Environment Research 

University of Puerto Rico 

College Station 

MayagUez , PR 00708 

ABSTRACT 

A 1125 MW oil fired power plant has been discharging cooling water 

in Bahia de Guayanilla since 1958-1959. The heated effluent enters an 

enclosed cove connected to the eastern portion of the bay by a narrow 

entrance. The concentrations of Ni , In, Cu and petroleum hydrocarbons in 

4 stations within the intake area and in 4 stations in the thermal cove 

were determined. The sediments of the central portion of the cove have 

average concentration that are 217% greater for Ni, 69% greater for In, 

62% greater for Cu, and 188% greater for petroleum hydrocarbons than 

those found at the intake. The circulation pattern inside the cove seems 

to influence the distribution of these pollutants in the sediments. 

518 
INTRODUCTION 

The use of nearshore sites to locate electric power generation 

stations is quite common in Puerto Rico. The main advantage is the 

ava il abil ity of the sea as both cool i ng water source and heated wa t er 

discharge site. Once-through cooling systems are cost effective as 

compared to other options. 

Corrosion and biofouling are common problems when sea water is 

used fo r cooling purposes. To reduce these problems to manageable 

1 eve 1 s, certain chemi ca 1 s are used Chromi urn i n the form of chromate is 

used as corrosion inhibitor. Chlori ne is used as antifouling agent. 

In the cooling process, antifouling chemicals, corrosi on 

inhibitors and heat are added to the intake water and discharged back to 

the sea. Petroleum hydrocarbons and other contami nants from the plant 's 

processes are also commonly discharged with the heated sea water . 

Significant pollution of the receiving marine environment can result fr om 

1 eachi ng and eros i on losses of metals from heat exchanger surfaces. 

These are often made of Ni/Cu alloys. 

The effects of these pollutants in the marine environment is often 

overlooked when compared with the emphasis in the literature on re search 

on the effects of heat itself. 

In this paper, we demonstrate the increased accumulation of 

selected trace metals and petroleum hydrocarbons in marine sediments of 

the discharge side , relat ive to t he intake side , of an oil-fired power 

station using once-t hrough cool i ng on the Caribbean Sea coast of Puerto 

Rico. 

METHODS AND MATERIALS 

Study Site 

Bahia de Guayanilla is an embayment enclosed by coral reefs and 

lined by mangroves, which was the site of a large petrochemical industry 

complex locat ed on the Caribbean Sea shore on the south coast of Puerto 

Ri co (Figure 1). Studies of the physical, chemical and biological 

characteristics of the bay and of the overall impact of the industrial 

operati ons on this mari ne environment are summarized by Lopez (1979a) . 

519 
Fi gure 1. Study si t e showing sampling stati on plan . Stations A,B,C, D are 

located i n Inta ke area . Station s H, I,J ,K are located in Receiving 

area (Thermal Cove). 

u •. ~-

'" 0 

:::> PUERTO RICO ~ 

~ 

• ..J 

Z 18.0-

81- 88-

W LONGITUDE 

j 

°0 

~ Power Planl 

N ~ / \ 

Conol 

• \ 

520 
Among the industries in the area, a petroleum refinery, various 

petrochemical manufacturing plants and the Costa Sur Power Gene ration 

station were major dischargers to the bay for many years. The oil -fi red 

power station generates 1,135 MW and continues to discharge its once 

through-cooling water through a 100m canal into a nearly enclosed , 

mangrove lagoon (Thermal Cove) , 900m long by 200m wide, which in turn is 

connected with the eastern portion of the bay by a 30m wide entrance. 

The high velocity discharge (>1 m/s) induces a clock-wise circulation 

within the Thermal Cove (Goldman, 1979). 

Sampling and Analytical Methods 

The samples were collected from R/V Sultana in 4 stations withi n 

the intake area and in 4 stations in the Thermal Cove (Figure 1). The 

sediment samples were obtained with a Shipek Dredge. An undisturbed 

portion (250 ml) of the samples (upper 5 cm) were removed and placed in 

plastic freezer containers for metal analysis and in glass jars for 

hydrocarbons analysis. 

For trace metals analysis, portions of the sediments were oven 

dried overnight at 600C to avoid metal losses. Then, the sample was 

ground to a fine powder in a porcelain mortar. Triplicate 19 subsamples 

were weighed into teflon beakers and digested with hydrogen peroxide, 

hydrofluoric acid and inverse aqua regia (3 parts HN03 : 1 part HC1) . 

The filtered digests, made up to 25 ml with deionized water, were 

analyzed by direct aspiration, using D2 background correction on a 

Perkin-Elmer 303 Atomic Absorption Spectrophotometer. 

Petroleum hydrocarbons in the sediments were determined 

gravimetrically after Sohxlet extraction with benzene/methanol as per the 

method of Farrington and Tripp (1975). 

RESULTS 

The Cu, Ni, Zn and petroleum hydrocarbons concentrations in the 

sediments of the intake and Thermal Cove (di scharge area) are gi ven in 

Table 1. In all cases the pollutant concentrations at station H, which is 

located in the center of the cove, are higher than the concentration at 

t he four stations within the intake area. 

521 
TABLE 1. Pollutants concentrations in the surface sediments of Bahia de 

Guayanilla. Standard deviation in parenthesis. 

STATION HYDROCARBONS (%) Ni ().l.g/g) Zn ().l.g/g) Cr ().l.g/g) Cu ().l.g/g) 

INTAKE 

A 0.19 20 .51 55 .26 29.86 50.75 

(0 .87) (0.01) (4.93) (5.37) 

B 0.04 16.08 57.99 71.24 67.91 

(0.58) (0.01 ) (0.01 ) (1.87) 

C 0.14 11.99 58.72 26.74 75.45 

(0 .01) (0 .05) (0.02) (0.07) 

D 0.05 14.49 67.00 75.21 78 .96 

(1.24) (0.00) (5.60) (3.4 7) 

THERMAL COVE 

H 0.28 47.74 90.98 122.7 117.3 

(0.00) (0.01) (0.01 ) (4.6 1) 

0.25 15.49 66.97 38.92 36.48 

(0.43) (0 .04) (2 .50) (1.52) 

J 0.34 52.21 34 .17 22.32 104.2 

(0.04) (0 .17) (1.75) (0.09) 

K 0.15 18.56 24 .07 8.35 5.86 

(23 .78) (6.45) (4.05) (8.15) 

522 
A t-test was used to determine if the average concentration in the 

intake and the concentrations at the stations within the Thermal Cove 

were significantly different. Table 2 shows the results of the t-tests. 

For Cu and Ni, stations Hand J presented the highest 

concentration of all the stations samples (Figure 2). The average 

concentrations of these two stations are significantly different (p ~O.5) 

from the average concentration in the intake area. Stations I and K have 

Cu and Ni concentrations similar to those in the intake. 

The average concentration of petroleum hydrocarbons in stations H, 

I and J iss i gn i fi cant 1 y higher than the average con cent rat i on in the 

intake area. 

Station H has the highest Zn and Cr concentrations of all the 

stations sampled but the other stations in the Thermal Cove do not show 

enrichment relative to the intake. To compare this single observation 

with the mean of the intake area a special t-test was used (Sokal and 

Rohlf, 1981). The Cr and Zn concentrations at station H differ 

si gnificantly (p ~.05) from those in the intake area. 

DISCUSSION AND CONCLUSIONS 

The analysis presented demonstrates that a net accumulation of 

pollutants has occurred in the Thermal Cove relative to the intake area. 

We infer that this enrichment effect can be attributed to the power plant 

operation since there exists no other source of pollutant to the cove. 

The d i st ri but i on of these poll utants in the sed i ments is the result of 

the circulation pattern inside the cove. 

Station H is located at the center of a clock-wise gyre which is 

fo rmed by the high speed (>1 m/s) thermal discharge. At the eastern end 

of the Thermal Cove, where station J is located, a small counterclockwise gyre is also formed (Goldman, 1979). 

The se two gyres appear to accumulate sediments and pollutants. In 

station K, at the outlet of the discharge canal, the high water velocity 

does not permit the accumulation of particles and pollutants . 

Trace metals and petroleum hydrocarbons have been shown to be 

widely availabl e to biota in the Bahia de Guayanilla and in similar 

envi ronments . Bi oaccumul at ions of trace metals in the mangrove oyster 

523 
Table 2. T-tests for comparing Intake and Thermal Cove Stations. 

Cu in sediments (119/g) 

Stations Compared 

All in Intake vs. Hand J in Thermal Cove 

Average Intake = 68.3 Average Thermal Cove = 110.7 

Standard deviation = 12.6 Standard deviation ~ 9.3 

N=4 N=2 

t(4) = -4.151 P = .015 

Ni in sediments (119/g) 

Stations Compared 

All in Intake vs. Hand J in Thermal Cove 

Average Intake = 15.8 Average Thermal Cove = 49.97 

Standard deviation = 3.6 Standard deviation = 3.16 

N=4 N=2 

t(4) = -11 .334 P = .001 

Petroleum Hydrocarbons in sediments (%) 

Stations Compared 

All in Intake vs. H, I and J in Thermal Cove 

Average Intake = 0.10 Average Thermal Cove = 0.29 

Standard deviation = 0.07 Standard deviation = 0.05 

N=4 N=3 

t(5) = -3 .83 P = .013 

Cr in sediments (119/g) 

Stations Compared 

All in Intake vs. H in Thermal Cove 

Average Intake = 50.76 Station H = 122.72 

Standard deviation = 26.01 N = 1 

N=4 

t(3) = 2.50 .025<p<.05 

Zn in sediments (119/g) 

Stations Compared 

All in Intake vs. H in Thermal Cove 

Average Intake = 59.74 Station H = 90.98 

Standard deviation = 5.06 N = 1 

N=4 

t(3) = 6.90 p<.05 

524 
Figure 2. Pollutants concentrations in the surface sediments of Bah fa de Guayanilla. 

Stations A to D were located in the intake. stations H to K were located in the Thermal 

Cove. 

117.3 

120 

100 

80 

Cu ~g/g 60 

40 

20 5.86 

0 

A B C 0 H J K 

6 0 52 .21 

50 

4 0 

Ni ~g/g 30 

20 

10 

0 

A B C 0 H J K 

100 90 .98 

80 

60 

Zn ~g/g 

40 

20 

0 

A B C 0 H J K 

140 122.72 

120 

100 

Cr ~g g 80 

60 

40 

20 

0 

A B C 0 H J K 

H 

Y 0 .34 

D 0 .35 

R 0 .3 

0 0.25 

C 0 .2 

A 

R 

0. 15 

B 0 .1 

0 0 .05 

N 0 

S A B C D H J K 

0/0 STATION 

525 
Crassostrea rhizophorae and in the flat tree oyster Isognomon alatus in 

Bahia de Guayanilla was demon st rated by Almod6var-Ferrer (1986). 

Schroeder and Thorhaug (1 978) and Thorhaug and Schroeder (1978) 

demonstrated the accumulat ion of heavy metals in the turtle grass 

Thalassia testud inum . Banus (1 977) and L6pez (1979b) showed 

incorporation of t race metals in the red mangrove Rhizophora mangle in 

the Bahia de Guayanil l a area. These two plant species form the basis for 

important mari ne food webs in the Caribbean and Gulf Coast region . 

Biological magnification vi a these food webs may lead to humans. 

LITERATURE CITED 

Almod6var-Ferrer, R. Accumulati on of Cu, Fe and Zn in Crassostrea 

rhizophorae and Isognomon alatus in the tropical marine 

environments. M. S. Thesi s. Un iversity of Puerto Rico, Mayaguez 

PR o 1986. 

Banus, M. D. Copper , iron, and manganese content of mangrove seedl i ngs 

from Puert o Ri co . In: Biological Implications of Trace Metals in 

the Envi ronment . , H. Drucher and R.E. Wildung, Eds. Proceedings of 

Conf. #750929 T. I.C . , ERDA 1977 (Nat. Tech, Info. Service, U.S. 

Dept. of Comm., Spri ngfield, VA 22161). 

Farrington, J.W. and B.W . Tripp. A comparison of methods of analysis for 

hydrocarbons in surface sedi ments. Amer. Chern. Soc. Symposium Series, Phi ladel phia, PA. 1975 . 

Goldman , G.C. 

Energy 

Energy 

1979. 

Water ci rculation in Guayani11a Bay. In: Symposium on 

and t he Mari ne Envi ronment in Guayani 11 a Bay, Center for 

and Envi ronment Research. pp.10-18. Mayaguez, PRo July 

Lopez, J.M. (Editor) . Proceedings of a Symposium on Energy and the Marine 

Environment in Guayanilla Bay, Center for Energy and Environment 

Research . 94 pp . Mayaguez, PRo July 1979. 

Lopez, J.M. Studies on the mang roves of Guayanilla Bay. In: Symposium on 

Energy and the Mari ne Envi ronment in Guayanill a Bay, Center for 

Energy and Environment Research . pp. 73-83. Mayaguez, PRo July 

1979 . 

Schroeder, P.B. and A. Thorhaug. Mineral cycling model of Thalassia 

cOlMlunity as affected by thermal effl uents. In: Proceedi ngs of 

the Second Conference on Waste Heat Management and Ut i1 i zat ion. 

Ed. by S.S. Lee. Mechanical Engineering Department University of 

Miami. Coral Gables, FL. December 1978. 

526 
Sokal, R.R. and F.J. Rohlf. Biometry. 859 pp. San Francisco: W.H. 

Freeman and Co. 1981 . 

Thorhaug, A. and P.B. Schroeder. Synergistic effects of substances 

emitted from power plants on subtropical and tropical populations 

of the seagrass Thalassia testudinum: temperature, salinity and 

heavy metals. In: Proceedings of the Second Conference on Waste 

Heat Management and Ut il i zat; on . Ed. by S. S. Lee. Mechan; ca 1 

Engineering Dept., University of Miami , Coral Gables, FL. 1978. 

527 
EFFLUENT TOXICITY TESTING 

FOR INDUSTRIAL DISCHARGERS 

Mark Shearon 

Harmon Engineering Associates, Inc. 

Auburn, Alabama 

ABSTRACT 

The United States Environmental Prot ection Agency has developed final 

protocols for the t esting of industrial and municipal wastewater 

discharges for toxicity to aqu at ic organisms. These testing procedures 

defi ne tl:!e methods for est imat i ng both the acute (immedi ate or shortterm) toxicity, as well as the chron i c (long-term) toxicity. Several 

organisms have been standardized, as well as the age and culture 

conditions for those organisms. These requirements define a necessary 

Quality Assurance plan for the toxicity laboratory . As applied by most 

state regulatory agencies , effluent toxicity is required of most primary 

and secondary industry. Some states initiated the acute testing within 

the past few years. Those dischargers currently obtaining renewed or new 

NPDES permits for process wastewater sources are having the testing added 

to, or maintained on, their discharge permits. The current approach to 

toxicity testing for NPDES permits involves a tiered approach to 

determining the required levels of testing. Initially, the effluent is 

"screened" to determine the acute toxicity. Those sources failing the 

screening test are then subj ected to a more rigorous series of tests to 

define the LC5~ as well as the chronic toxicity values. Discharges which 

are consisterrtly toxic are then required to enter into a Toxicity 

Reduction Study, wherein the toxic elements are identified, and 

additional treatment technology to correct the toxicity is evaluated. 

The end result is supposed to be a revision of the waste treatment 

technology to prevent further discharges of toxic effluents. This paper 

will identify the testing techniques currently required of the permitees, 

the QA requirements, the use of the results, and the apparent future of 

effluent toxicity testing. 

528 
TOXICITY AND BIOACCUMULATION TESTING 

REVIEW PAPER 

William Peltier 

U.S. Environmental Protection Agency 

College Station Road 

Athens, Georgia 30613 

Before I review the session papers on toxicity and bioaccumulation 

testing , I would 1 ike to say that, even though there were only four 

papers in this session, it does not diminish the importance of toxicity 

t esting and bioaccumulation testing now or in the future. We are 

currently faced with the immense problem of toxic materials in our 

environment ; the problem will only grow in the future. In addition to 

the historical chemical by chemical approach, the biological approach for 

t he control of toxics has been accepted as an important tool in 

evaluating the impact of point and nonpoint source discharges to our 

environment . 

Let me discuss what is currently happening in the areas of toxicity 

and bioaccumulation testing. Nationally, there is going to be a 

concerted effort to control toxics int he air, ground water, and surface 

water. In 1984 EPA recommended that biological monitoring, specifically 

toxicity testing requirements, be included in the NPDES permits. Since 

the most recent funding of the CERCLA (Superfund) and RCRA programs, 

bioassessment studies are being used to complement the chemical and 

physical approach in toxic control. Bioaccumulation studies are being 

used to determine the human risk associated with the consumption of fish 

and shellfish. We have gone through a process of encouraging regulatory 

permit writers and permittees to accept toxicity and bioaccumulation 

testing as a necessary means to control toxics. This acceptance has been 

a matter of education. Permit writers and permittees had to be educated 

as to how the data was to be interpreted and its app 1 i cat ion ina 

regul atory manner. Al so for these programs to be impl emented by the 

regulatory agencies, acceptable and cost-effective methods had to be 

available. 

529 
I use the term cost -effective because , as a biologist, I was 

probably my own worst enemy at planning elaborate studies. Early in my 

career, I was involved in many biol ogical field monitori ng studies. 

These studies were usually long -term , resource intense , and costly. At 

times the information was not prov ided in a timely manner so a to make a 

quality decision. As a result, other short-term test methods were 

employed to assess t he toxic impact on the receiving water biota. 

One of the first short-term test methods employed in the NPDES 

permit program was acute static and flow-through toxicity tests. These 

tests ranged from 24 to 96 hours in duration. Recently, short-term 

chronic toxicity tests have been developed and are in use for determining 

the toxicity of an effluent. The se tests ranged from 1 hour to 9 days in 

duration. 

The shift from fi eld assessments to point source assessments of 

pollution raised a question as to the validity of the results of point 

source testing when compared to the traditional recelvlng water 

evaluations. As a result, EPA -ERL Duluth Laboratory conducted eight 

studies around the country to determine if end-of-the-pipe data 

correlated with f i eld data. Each study involved whole effluent toxicity 

testing, receiving water dye studies, i nvertebrate and fisheries studies. 

In all cases, the results demonstrated that if toxicity occurred at the 

end-of-the-pipe, there was a similar impact on the receiving water biota . 

North Carol ina recently conducted s imil ar compari sons usi ng the 

short-term chroni c test with Ceri odaphni a and evaluated the downstream 

impacts from point source discharges. They evaluated the macroinvertebrate population instream, and in 87% of the cases they were able 

to correlate "end-of-the-pipe" impacts with the instream impacts. Where 

there was no impact at the end-of-the-pipe based on the reproduction of 

Ceriodaphnia, there was no significant difference in the number of taxa 

found upstream vs. downstream. When there was no impact at the end of 

the pipe, there was a definite reduction in number of taxa found 

downstream from the discharge. 

The short-term tests are not always a substitute for field studies . 

Field studies are important in determining long-term trends, basel ine 

inventories or perturbation from episodic events. Selection of the 

530 
method to be used in assessing an impact on the biota must be on the case 

by case bases. 

One of the problems in employing the short-term approach was who 

could do the testing for the permittees? To answer this question, EPA 

Region IV conducted a survey in 1986 on the number of consulting firms in 

the southeast that could do toxicity testing. As a result, approximately 

36 consult i ng firms in Region IV could provide clients with some level of 

toxi ci ty testing. The cost for these tests ranged as follows: 24 to 96 

hours acute static tests on a single species range from $50 to $600; 

short-term chronic tests range from $500 to $2000. The costs appear to 

be negotiable based on the number of species to be tested and frequency 

of testing. The rationale for not putting toxicity testing requirements 

in the NPDES permits can't be justified based on lack of laboratories or 

cost. Certainly the costs are more reasonable when compared to earlier 

l ife cycle trout studies which required 2 years to complete (i .e., egg to 

egg studies) . 

The papers given during this session deal with once through cooling 

water, fly-ash effluent, bioaccumulation and industrial discharges. Each 

of wh i ch has a toxi c impact on the recei vi ng water bi ota. The paper 

titled "Pollutant Enrichment of Sediments from Cooling Water Discharge in 

Bahia de Guayanilla, Puerto Rico" brings out the fallacy that once 

through cooling water (i .e., non-contact cooling water) is free ' of 

pollutants. Most of the NPDES permits do not require the permittee to 

monitor for toxicity. As a result, periodic checks on selected cooling 

water di scharge have i ndi cated acute and/or chroni c toxi city. Use of 

anti-corrosive and anti-fouling chemicals are now being closely monitored 

to insure toxic conditions are minimized or eliminated. Request for use 

of different chemical for anti-corrosive and fouling have to have data 

indicating the acute and chronic toxicity of the chemical to selected 

fish and invertebrates. The discharge of pollutants, even at low 

concentrations, poses a problem in the receiving water as indicated in 

the authors' paper. Concentrations of chemi ca 1 sin the sediment may 

eventually reach levels that are toxic to the benthic organisms. The 

potential for bioaccumulation i n the food chain increases as the area of 

contamination increases. The situation which is occurring in Puerto 

531 
Rico, certainly calls for some type of receiving water biological 

monitoring program. A reduction in the receiving water faunal community 

and/or an accumulation of pollutants i n fish or shellfish would justify 

remedial action by the regulation agency . The second paper titled "Some 

Observations on Aquatic Impacts of Power Plant Trace Element Discharges" 

demonstrates the need for a greater concern of toxic effects from trace 

elements. The presents of trace elements in discharge from fly-ash 

settling ponds are usually at sublethal or chronic concentrations. For 

example, in Belews Lake selenium was discharged from the fly-ash settling 

ponds at ppb concentrations. However, the sediment concentrated selenium 

up to 50 ppm which then became a source of toxicity to the biota. 

Selenium was then bioconcentrated in the tissues of fish through the food 

chain . As a resul t, selected populations of fish were eventually 

eliminated through a chronically toxic condition. Species sensitivity to 

selenium was also demonstrated by the fact that the fathead minnow was 

not affected; however, native Centrarchids and Ictalurids were 

eliminated. The point was made that further research is necessary to 

answer the questions regarding the toxic impact of trace elements. 

The bioaccumulation of radionuclide in a predator was illustrated 

in the paper titled, "Radiocesium Kinetics in the Yellow-Bellied Turtle 

(Pseudemys scripta). Resident biota, such as certain turtles and 

raptors, feed on contaminated food sources. At the Savannah River Plant, 

cooling ponds, such as Parr Pond, have a fish community that is 

contaminated by 137CS. The contamination probably comes from both the 

137CS in the water column and through the food chain. The contaminated 

fish are sources of the bioaccumulation in predator organisms. The 

kinetics involved with uptake and depuration rates with many predator 

organisms is not well documented . Results from this paper does shed some 

light on the utility of modeling the information, however much work still 

needs to be done in the future. 

The paper on "Effluent Toxicity Testing for Industrial Dischargers" 

covered much of my early discussion on current activities in toxicity 

testing. However, if effluent is consistently toxic, the permittee would 

be required to conduct a Toxicity Reduction Evaluation (TRE). The 

purpose of the TRE is to identify the cause of toxi city and determi ne 

532 
treatment necessary to reduce or eliminate the toxicity . The TRE is 

divided into three phases: Phase I - Toxicity characterization; Phase II 

- Causative toxi cant i dent ifi cat i on; and Phase II I - Causat i ve tox i cant 

confirmation. What is unique in the TRE is the use of an aqu ati c 

organism i.e . , daphnid, as the analytical detector of toxicity_ Acute 

toxicity test are employed throughout all three phases . Minimal 

analytical work is required in Phase I, as the majori t y of t he 

identification is conducted with toxicity tests. Phases II and III may 

require extensive analytical support . 

As indicated from the papers presented in this secti on, t he area of 

toxics and bioaccumulation is go i ng to be in the forefront of pol lution 

abatement for years to come. 

533 
SOUTHEASTERN WORKSHOP ON 

AQUATIC ECOLOG ICAL EFFECTS OF POWER GENERATION 

December 3-5 , 1986 

Mote Marine La boratory 

Sarasota, Florida 33577 

POSTER SESS ION ABSTRACTS 

(Arranged Al phabetically) 

1 . Bruzek, D. A. and S. Mahadevan. Mote Mar i ne Laboratory, Sarasota, 

Florida. 

THE APPLICATION OF LOG- NORMAL DISTRIBUTIONS IN DETECTING POLLUTIONINDUCED CHANGES IN A BENTHIC COMMUNITY. 

Benthic infaunal samp l es were collected from 40 stations over a 

peri od of 15 mon t hs in t he vi ci n i t y of the Crystal Ri ver Power 

Station. Th e indiv idu al s of each species were identified and 

enumerated, and the log -normal distribution of individuals per 

species was determi ned . Curve s were drawn for each station and 

samp 1 i ng peri od and mean angl es cal cul ated from these curves . The 

mean angle of each st at ion was th en pl ott ed as a means of detecting 

the pollution-induced changes as well as naturally disturbed areas 

in the communities . It was found that stations in the area of the 

thermal effluent and natur al l y disturbed areas had lower log-normal 

angles (30-350 ), whereas the offs hore and nearshore undisturbed 

stations had higher log -norma l angl es (above 400 ) . Since a 

shallower slope refl ects a community under environmental stress, 

these data suggest that t he al t eration of basic log-normal 

distribution of ben th i c comm unities can be used to discern 

disturbances. 

2. Frere, P. Potomac Electric Company, Washington, DC. 

CONTROL OF MACROFOULING ON INTAKE STRUCTURES AND MODIFICATIONS TO 

CHLORINATION PROCEDURES AT AN ESTUARINE POWER PLANT. 

Potomac Electric Power Compa ny' s Chalk Point Station is located on 

an estuarine segment of the Patuxent Rive r, a tributary to the midChesapeake Bay . The station has two open-cycle, 355 MWe units using 

condenser cooling water taken directly from the Patuxent River. The 

cooling water wa s previously continuously chlorinated to control 

macrofoul i ng organ i sms. Ov er t he years, the stat i on has suffered 

numerous unit outages due to bi ofoul ing of the intake gallery and 

precondenser pip i ng surfaces whi ch are no t exposed to chlorine. 

Dense mats of Garve i a sp. accumul at e on concret e surfaces during the 

summer months. These ma ts serve as habi tat for secondary foul i ng 

organisms. The mats periodically break free from the walls and 

block the conden se r tube sheet face , reducing cooling water flow and 

causing unit shutdowns. A study to solve the condenser tube 

blockage problem by documenting the seasonal growth curve for 

Garveia, relating the growt h to natu r al cycles of water temperature 

and salinity, and identifyi ng secondary fouling organisms was 

initiated i n 1985 . Co ncrete plates similar in surface 

characteristics to the i ntake structu re were suspended in front of 

the stat ion intake screens and a 11 owed to foul. The plates were 

534 
inspected at intervals through the period July 1985 to October 1986. 

The study included an evaluation of various antifouling coatings to 

control growth of Garveia. Plates similar to those employed in the 

monitoring program were primed and painted with Intersleek, a nontoxic ultra-smooth material , and No Foul , a paint containing 

tributyltin ox ide . These plates were suspended in the intake al ong 

with unpainted contr ol s and inspected at weekly interval s through 

the earl y summer foul i ng pe r i od. Growth of Garvei a and secondary 

foul i ng organisms was recorded . Intermittent chlorination was 

at t empted in 1986 to reduce the rate of condenser tube corrosion. 

Records were kept on condenser backpressure , circulating water pump 

amperage and ch 1 ori ne dosage. Inspect ions of intake condenser 

wate r boxes were made during each outage over the test period. 

3. Graham, R.J. North Anna Environmental Lab, Virginia Power, 

Virginia. 

FACTORS AFFECTING THE SUCCESS OF ARTIFICIAL FISH STRUCTURES IN A 

POWER STATION'S COOLING RESERVOIR. 

Clea r- cutting of timber and removal of man -made structures are 

common practices in the construction of impoundments and reservoirs 

used for cooling facilit i es. These activities may result in limited 

habitat for cover-orient ed fishes, e .g. , centrarchids and 

i ctal uri ds , and reduce t he probability of developing productive 

f ishe ri es. Lake Anna , Virginia is a 24 , 000 hectare impoundment of 

t he North Anna River t hat provides cooling water for Virginia 

Power's North Anna Power Station. The lake site was clear-cut prior 

to construction, and approximately 90% of the lake bottom consists 

of sand, silt or clay. Seven artificial fish structures were placed 

in Lake Anna by Virginia Power during 1983 at depths ranging from 5 

to 9 m in an attempt to provide cover for the sport species 

largemouth bass, Micropterus salmoides, and black crappie, Pomoxis 

nigromaculatus , nursery areas for a major forage species, bluegill, 

Lepomis macrochirus, and f ishermen with opportunities to concentrate 

their efforts in areas easily accessible and fished by traditional 

methods. Based on SCUBA observat i ons and water qual i ty moni tori ng 

surveys, factors that appear to have significantly influenced 

utilization of fish st ructures include the construction materials 

used and pumping operations' of the North Anna Power Station. 

Structures consisting of cedar trees anchored over cinder block 

su bst rates were generally unproductive, due to accretions of silt 

that compacted boughs, in compari son to structures cons i st i ng of 

hardwood tree tops anchored over ci nder block substrates. 

Struc t ures placed in ar eas subject to currents resulting from 

pumping operations exhibited more acceptable (D .O. 5 ppm) oxygen 

levels during the summer months than those placed in areas protected 

from or out of the influence of pumping operations, due to better 

mixing of well oxygenated epil imnetic and poorly oxygenated 

hypolimnetic waters. Important considerations in construction and 

location of fish structures in cooling facilities should include 

clear definition of results desired, choice of target species, 

ava i 1 abi 1 i ty and cost of construction materi a 1 s, temperature and 

oxygen requirements of target species and hydrologiC characteristics 

of the wate rs . 

535 
4. Grimes, D.V. North Ann a Environmental Lab, Virginia Power, 

Virginia. 

A MOUNTED HYDROPHONE BRACE FOR USE IN BIOTELEMETRY STUDIES. 

Biotelemetry studies have traditionally been carried out with the 

use of hand -held hydrophones. In 1984 a two year biotelemetry study 

of striped bass , Morone saxat i1is , was begun at Lake Anna, Virginia, 

which serves as a 24,000 hectare cooling reservoir for Virginia 

Power's North Anna Power St ation. The need fo r a more effective and 

efficient means of locating and tracking tagged fish led to the 

deve 1 opment of a boat moun ted hydrophone brace. A boat mounted 

hydropho ne offe rs several advantages over hand-held hydrophones . Advantages include the reducti on of manpower requirements for 

track ing surveys by 50%, and the capability to easi ly collect large 

amounts of accura te tracking data as a result of being able to move 

wi th located fi sh. The mounted hydrophone brace has been used at 

Lake Anna since mid 1984. During the period 1984-1986 , 73% of the 

fi sh tagged have been located and tracked us i ng the boat mounted 

hydrophone ; 63% of the tags found were tracked for 1-3 months, 34% 

were tracked for 4-6 months , and 3% were tracked for more than one 

year. The cost of the hydrophone brace was under thirty dollars. 

5. Horst, T.J., J.K. Downing, T.A. Biffar. Stone & Webster Engineering 

Corporation, Boston , Massachusetts. 

ENTRAINMENT AS A RISK ASSESSMENT PROBLEM. 

Entrainment of organisms with intake water has received much 

attent i on, and the projected impacts have resulted in the 

expenditure of considerabl e economic resources in an attempt to 

reduce entrai nment. Related decisions have necessarily been made in 

light of large uncertainties with respect to the ecological effects 

of entrainment an d the effectiveness of technologies to mitigate 

entrainment. One method for investigating these decisions is risk 

assessment , which has received wide application in fields as diverse 

as engineering economics and env ironmental health analysis. In risk 

analysis the risk is determined by both t he exposure to the risk 

source and the con sequence. Entrainment at water intakes is 

examined as a risk assessment problem. Alternative mitigative 

measures are exami ned with respect to ri sk reduction. The prob1 em 

is formulated bo t h fr om the env ironment al point of view, risk to the 

organism, and from the economic point of view, risk of capital. 

Selected site data are used for illustrative purposes. 

6. Loeffelman, P.H . and J.B. Suomala. Ame rican Electric Power Service 

Corporation, Columbus, Ohio . UNDERWATER ACOUSTIC RADIATION, WATER VELOCITY AND WARMWATER FISH 

DISTRIBUTION AT RACINE HYDROELECTRIC PROJECT, USA. 

Underwater acoustic radiati on , water velocity and hydroacoustic 

(SONAR) fish monitoring was conducted in August 1986 at Ohio Power 

Company's 48,000 kW Racine Hydroelectric Project at Ohio River mil ," 

237.5 near Racine, Ohio, USA. This monitoring was performed t o 

determine if any relationships coul d be established among: a) 

underwater sound produced by the two bulb (horizontal Kapla n) 

turbines; b) water velocity; and c) presence of warmwater f i '. tl 

species in the forebay, intake, draft tube, and tailwaters of Ihi" 

project. Acoustic radiation and water vel ocity measurements at )[) 

536 
locations were conducted , while visual and SONAR observations of 

fish distributions were made at a number of these locations . Tot a 

and mean RMS pressure level s of spectra from 2 Hz to 20 kHz we re 

measured. Highest pressures were within the probable auditory range 

(50 to 800 Hz) of resident teleost fish . Of all location s, 

continuous sound pressure levels from the bulb turbines were highest 

in the draft tube (+158 dB// l uPa) and immediately upstream of the 

intake trashracks (+185 dB//l uPa). The pressure level of +138 

dB//l uPa in the tailrace, the lowest l evel r ecorded at all 

locations, was 139 times lower than the highest level recorded . High acoustic intensity, discrete narrow band frequency 1 ines at 

120, 240, 360 and 720 Hz were also recorded. Fish were observed at 

all water velocities, including those as high as 6 fps in t he 

tailrace. Fish were unevenly di stributed among monitoring 

locations. Few fish were observed in the draft tube and immedia tely 

upstream of the intake tra shracks compared to most other locations. 

The monitoring information suggests that differences i n the leve l of 

acoustic radiation contribute to di fferent fish distributions . 

7. Massie, F. Virginia Power Company, Virginia. 

IMPACT MITIGATION AND ENVIRONMENTAL ENHANCEMENT AT VIRGINIA POWER'S 

BATH COUNTY PUMPED STORAGE PROJECT. 

The Bath County Pumped Storage Project is the largest hydroelectric 

facility of its type in the world. Construction was completed, and 

the plant began commercial operation in 1985. The project, located 

in the western mountains of Virginia, is jointly owned by Virginia 

Power and the Alleghany Power System. Construction of the lower 

reservoir for the project inundated approximately 3.3 miles of Back 

Creek, a third order valley stream. To miti gate for this loss, 

Virginia Power proposed a three-fold plan which was accepted by the 

Federal Energy Regulatory Commission, which i ncluded: 1) 

construction of a public recreation area; 2) a stream habitat 

improvement plan; and 3) a wild turkey habitat enrichment program. 

The public recreation area was designed by the Harza Engineering 

Company and constructed by Virginia Power. It includes two stocked 

ponds (approximately 54 and 27 acres) for both bank and boat 

fishing, campgrounds, picnicking areas, a public beach, sw imming 

area, and a bath house. Virginia Power biologists will moni tor the 

fishery in conjunction with representatives from the Virgini a 

Commission of Game and Inland Fisheries . The Stream Improvement 

Plan was designed by Dr. John Ney of Virgin i a Polytechnic Institute 

and State University to improve the fish habitat in a 1.5 mile 

sect i on of Back Creek located below the lower reservoi r of t he 

project. The design called for the development of pools, stable 

banks and instream cover. Construction of the improvement area was 

comp leted in 1985. Biological monitoring of the area is being 

conducted by representatives of VPI for t wo years following 

construction to assess the effectiveness of the modifications . Virginia Power will then continue monitoring the area fo r the 

following five years . Small clearings were made at strategic 

1 ocat ions around the project si te for planting of vegetat i on as a 

food source for wild turkeys. These clearings have been very 

succe ssful in attracting tu r keys. They are "ma intained" 

periodically to en sure their effec t iveness. 

537 
8. Marion, W.R. University of Fl orida. J.R. Wilcox. Florida Power & 

Li ght Co. 

BALD EAGLE PRODUCTIVITY NEAR FLORIDA POWER & LIGHT COMPANY 

FACILITIES. 

The majority of Southern Ba l d Eag l e nest ing occurs in Florida, with 

220-250 succeisful nests each year. Fl or ida Power & Light Company 

conducted along -te rm mo n itori ng prog r am at selected Southern Bald 

Eagle nests in central Florida in an attempt to anticipate and 

minimize potential dist urbances during the nesting season. 

Productivity at four such nesting l ocations is compared with 

statewide prod uctivi ty average s fo r 1974 -1978 . 

9. Mazzotti, F.J. Uni versity of Pennsylvania . J.R. Wilcox. Florida 

Power & Light Company. 

CROCODILE MONITORING AT FLORIDA POWER & LIGHT COMPANY TURKEY POINT 

PLANT. 

Flori da Power & Li ght Company's crocod il e mon itori ng program has 

documented the compat i bi 1 ity of thi s endangered speci es with the 

generating of electricity . Over the last ten years, monitoring has 

determined the number of nests , growth and survival of hatchlings, 

growth and survival of j uveniles , and the abundance and distribution 

of adults. Two nests ha t ched each year during 1984-1985 with a 

total of 55 hatchlings being tagged . Twelve of the 34 hatchlings 

tagged in 1984 were recaptured in 1985 . Sixteen juveniles were 

captured over the mon itori ng peri od , and seven were recaptured at 

least once. Crocodiles continue to nest, grow, and survive at the 

Turkey Point Power Plant site . 

10 . Sprinkel, J.M. and J.F . Gorzelany. Mote Marine Laboratory, 

Sarasota, Florida. 

THE EFFECTS OF THERMAL EFFLUENT ON OYSTERS (Crassostrea virginica) AND OYSTER REEF FAUNA IN THE VICINITY OF FLORIDA POWER -CORPORATION'S 

CYRSTAL RIVER POWER PLANT . The he ight, length , weight, and volumetric displacement of oysters 

were measured before and after deployment in control and thermal 

areas. Mortality ra t es we re noted , and a Condition Index (CI) was 

determined for each 1 i ve oyster returned . Growth in control areas 

was not signifi cantly di fferent than growth in areas of maximum 

thermal influence . Growth wa s enhanced, however, in areas of 

moderate thermal in fluence . CI corre lated wi t h growt h and spawning, while mortality r at es were highe st in l at e summer and in the 

immediate thermal are a. A t otal of 175 t axa of oyster associated 

fauna were i dent ifi ed and enumera ted . Abundances and divers ity of 

oyster associated f aun a decreased in thermal ly affected areas, along 

with a change i n commu nity comp os ition from a mollusc-dominant 

community, to a more polychaet e- domi nan t community. This alteration 

was not wi despread , however, and was ess ent i a 11 y 1 i mited to areas 

undergoing immediate thermal influence. 

538 
SOUTHEASTERN WORKSHOP ON AQUATIC ECOLOGICAL 

EFFECTS OF POWER GENERATION 

LIST OF PARTICIPANTS 

Rafael Almodovar-Ferrer 

University of Puerto Rico 

Center for Energy and Environment Research 

Co 11 ege Stat i on 

Mayaguez, Puerto Rico 00708 

(809 ) 832 -7912 

John Alonso 

CH2M Hi 11 , Inc. 

3030 North Rocky Point Drive West, Suite 350 

Tampa, Florida 33607 

(813) 888-6777 

A. Spencer Autry 

Tampa Electric Company 

Post Office Box III 

Tampa, Florida 33601 

(813) 228-4838 

Jeffrey o. Barnes 

Barnes-Williams Env ironmental Consultants 

132 Washington Street 

Binghamton, New York 13901 

(607) 723-3113 

Paul J. Behrens 

Florida Power Corporation 

3201 34th Street South 

St. Petersburg, Florida 33711 

(813) 866-5521 

Chris Benedict 

Carolina Power & Light Company 

Brunswick Biology Laboratory 

Post Office Box 10429 

Sou th port, North Carolina 28461 

(919) 457-3397 

Dr. Thomas Biffar 

Stone & Webster Engineering Corporation 

245 Summer Street 

Post Office Box 2325 

Bo ston , Massachusetts 02107 

(617) 589-2725 

539 
lIST OF PART ICIPANTS continued. 

James D. Brown 

U.S. Fish and Wildlife Servi ce 

75 Spri ng Street Southwest 

Suite 1276 

Atlanta , Geo rgi a 30303 

(404) 331-6343 

Vilma S. Br ueggemeyer 

Tampa El ectric Company 

Post Office Box III 

Tampa , Florida 33601 

(813) 228-4841 

David A. Bruzek 

Mote Marine Laboratory 

1600 City Island Park 

Sarasota , Fl orida 33577 

(813) 388-4441 

John P. Buchanan 

Tennessee Valley Authority 

Fis h & Aquatic Ecology Branc h 

145 Summe r Place Buil ding 

Knoxvi ll e, Tennessee 37902 

(615 ) 632 -3701 

Linda R. Cadman 

Marti n Marietta Environmental Systems 

9200 Rumsey Road 

Columbia, Ma ryland 21 045 

(301) 964 -9200 

John Christian 

U.S. Fish & Wildlife 

75 Spring Street Southwest 

Atlanta , Georg i a 30303 

(404) 331 -3580 

Dr . Sheree L. Cohn 

St. Cloud State University 

Department of Biol og i cal Sc iences 

St. Cl oud, Mi nnesota 56301 

(612 ) 255 -4912/253 -8634 

Peter M. Cumbie 

Duke Power Company 

Design Engineeri ng Department 

Post Offi ce Box 33189 

Charlot te , North Carolina 28242 

(704) 373-8331 

540 
LIST OF PARTICIPANTS continued. 

Robert M. Daniels 

Virginia Power 

North Anna Environmental Laboratory 

Post Office Box 402 

Mi neral , Virginia 23117 

(703) 894-5151 

Dr . William Davies 

Department of Fisheries Allied Aquacultures 

Auburn Universi ty, 203 Swingle Hal l 

Auburn , Alabama 36849 

(205 ) 826-4786 

Robert W. Davis 

Lawler Matusky and Skelly 

Po st Office Box 1509 

One Blue Hill Plaza 

Pearl Rive r, New York 10965 

(914) 735-8300 

Kathleen Durrell 

Tamp a Electric Company 

Post Office Box III 

Tampa, Florida 33601 

(8l3) 228- 4842 

Bruce W. Easley 

Virginia Power 

Surry Power Station 

Post Office Box 315 

Surry, Virginia 23883 

(804) 357-3184 

Robert G. Ernest 

Applied Biology, Inc. 

Post Office Box 974 

1458 Sunview Terrace 

Jensen Beach, Florida 33457 

(305) 334-3729 

Phillis E. Frere 

Potomac Electric Power Co. 

Hallowing Point Lab 

RR 2, Box 81 

Prince Frederick , Maryland 20678 

(301) 855-1295 

Jay Gorzelany 

Mote Marine Laboratory 

1600 City Island Park 

Sarasota, Florida 33577 

(8l3) 388-4441 

541 
LIST OF PARTICIPANTS continued. 

Robert J. Graham 

Virginia Power 

North Anna Environmental Laboratory 

Post Office Box 402 

Mineral, Virginia 23117 

(703) 894-5151 

Paul Graybill 

Florida Power & Light/Mote Marine Lab 

4111 Plumosa Terrace 

Bradenton, Florida 33507 

(813) 792-7956 

David V. Grimes 

Virg i nia Power 

North Anna Environmental Laboratory 

Post Office Box 402 

Mineral , Virginia 23117 

(703) 894-5151 

Pete Hofmann 

Stone & Webster Engineering Corp. 

Post Office Box 2325 

245 Summer Street 

Boston , Massachusetts 02107 

(617) 589 -2841 

Don Holmes 

CH2M Hill 

3030 North Rocky Point Drive 

Tampa , Florida 33607 

(813) 888-6777 

T.J. Horst 

Stone & Webster Engineering Corp. 

245 Summer Street 

Post Office Box 2325 

Boston, Massachusetts 02107 

(617) 589-2725 

Charles H. Kaplan 

u.S. Environmental Protection Agency 

345 Courtland Street NE 

Atlanta, Georgia 30365 

(404) 347-3012 

James Kelly 

Pacific Gas & Electric Co. 

Post Office Box 117 

Avila Beach, California 93424 

(805) 595-7193 

542 
LIST OF PARTICIPANTS continued. 

Roy R. Lewi s, II I 

Mangrove Systems, Inc. 

Post Office Box 290197 

7729 Profe ssi onal Pl ace 

Tampa , Florida 33687 

(813) 989-3431 

Paul H. Loeffelman 

Ameri can Electric Power Service Corp. 

Envi ronment al Engineering Division 

One Riverside Plaza 

Columbus, Ohio 43216 

(614) 223 -1243 

Elaine R. Mac inski 

Florida Power Corporation 

Post Office Box 14042 

St . Petersburg, Florida 33733 

(813) 866-4481 

Dr. Kumar Mahadevan 

Mote Marine Laboratory 

1600 City Island Park 

Sar asota, Florida 33577 

(813) 388-4441 

B.M. Marshall 

Virg inia Power 

Post Office Box 26666 

Richmond, Virginia 23261 

(804) 775 -5199 

R. Erik Mart i n 

Applied Biology, Inc. 

Post Office Box 974 

Jensen Beach, Flori da 33457 

(305) 334-3729 

Frank Massie 

Virginia Power 

2043 Jackson Shop Road 

Goochland , Virginia 23063 

(804) 257 -4779 

Jack Matt ice 

Electric Power Research Institute 

3412 Hillview Avenue 

Palo Alto, California 94304 

(415) 855-2763 

543 
LIST OF PARTICIPANTS continued. 

Robert A. Mattson 

Mangrove Systems, Inc. 

Post Office Box 290197 

7729 Professional Place 

Tampa, Florida 33687 

(813) 989-3431 

Dr. Richard G. Monzingo Commonwealth Edison Company 

2 North LaSalle Street 

Post Office Box 767 

Chicago, Illinois 60690 

(312) 294-4446 

John M. Nestler 

U.S. Army Engineering Waterways Experiment Station 

Post Office Box 631 

Vicksburg, Mississippi 39180 

(601) 634-3870 

Dr. Michael C. Newman 

Savannah River Ecology Lab 

Drawer E 

Aiken, South Carolina 29801 

(803) 725-2427 

Dr. Lawrence Olsen 

Florida Department of Environmental Regulation 

Biology Section 

2600 Blair Stone Road 

Tallahassee, Florida 32301 

(904) 487-2247 

Robert G. Otto 

R.G. Otto & Associates 

620 Greene Street 

Key West, Florida 33040 

(305) 296-5838 

William Peltier 

U.S. Environmental Protection Agency 

College Station Road 

Athens, Georgia 30605 

(404) 546-2294 

Eric L. Peters 

University of Georgia 

Department of Zoology 

Room 724, Box 23 

Biosciences Building 

Athens, Georgia 30602 

(404) 542-3310 

544 
LIST OF PARTICIPANTS continued. 

Cindy M. Reigel 

Tampa Electric Company 

Post Office Box 111 

Tampa, Florida 33601 

(813 ) 228-4834 

Dr. John E. Reynolds , III 

Ec kerd College 

Post Office Box 12560 

St. Petersburg, Florida 33733 

(813) 867-1166 

Mike Roddy 

Seminole Electric Cooperative, Inc. 

Post Office Box 272000 

Tampa, Florida 33688 

(813) 963-0994 

Dr. Roger A. Rulifson 

East Carolina University 

Institute for Coastal and Marine Resources 

Greenville, North Carolina 27858 

(919) 757-6220/757-6770 

Paul M. Sawyko 

Rochester Gas & Electric Corporation 

89 East Avenue 

Rochester, New York 14649 

(716) 724-8399 

Mark Shearon 

Harmon Engineering Associates, Inc. 

1550 Pumphrey Avenue 

Auburn, Alabama 36830 

(205) 821-9250 

Jay Sprinkel 

Mote Marine Laboratory 

1600 City Island Park 

Sarasota, Florida 33577 

(813) 388-4441 

John Suomala 

50 Garrison Road 

Bingham, Massachusetts 02043 

(6 17) 749-7049 

545 
LIST OF PARTICIPANTS continued. 

Edward P. Taft 

Stone & Webster Engineering Corp. 

Post Office Box 2325 

245 Summer Street 

Boston, Massachusetts 02107 

(617) 489 -2948 

Bradley L. We igle 

Florida Department of Natural Resources 

Bureau of Marine Research 

100 8th Avenue SE 

St. Petersburg, Florida 33701 

(813) 896-8626 

Or. Ross Wil cox 

Florida Power & Light Co . Post Office Box 14000 

700 Universe Boulevard 

Juno Beach, Florida 33408 

(305) 863-3623 

Jerry L. Williams 

Tampa Electric Company 

Post Office Box III 

Tampa, Florida 33601 

(813) 228-4837 

Howard D. Zeller 

California Department of Natural Resources 

Floyd Towers East, Suite 1252 

205 Butler Street, SE 

Atlanta, Georgia 30334 

(404) 656 -2795 

Charles J. Zimmerman, Jr. 

Dames & Moore 

455 East Paces Ferry Road 

Suite 200 

Atlanta , Geo rgia 30363 

(404) 262-2915 

\ 546