SEA TU R TLE ENTR APME N

T AT A C OA STAL POWE R PLANT

Rob e rt G. Ernest, R. Erik**r~artin,** Bru ce D. Peery and Douglas G. Strom, Applied Biology, Inc., P.O. B

ox 9 74, Jensen Be ac h , Florid a 3495 8 ; J
. Ro s s W

ilcox, Florida P owe r 

### &Li ght Comp any, P.O. Box 1 40 00, Juno B each, F l ori da 33 408 ; and Nancy W. Wa l l s, Appl ied Bi olo g y, Inc . , 29 68 -A No rt h Decat ur R

oad, De cat ur , Geo rgia 30033.

INTRODUCTl ON

Florida Power & Light Compa n y (FPL) operates two**850-r~W** nuclear-fueled elec tric gene r ati n g un it s on Hutchi nson Isla n d, St. Lucie C ou nty , Florida. B

oth unit s of t he St. Luci e Pla nt coll ecti vely drdw and dis ch arge oncethrough conde nser co oling w ater t hrough an enc lo sed c ana l sy st em connected wit h the A tlanti c O c ean vi a submerged pi pe s. A lt hou gh the offs ho r e s tructures housing the intake pipe s were design ed to mi ni mize ent rai nment of nektonic organisllls, they appa rently act as attr ac tan t s t o s e a turt l es . Upon entering th e i ntake pipes , t he turt l 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 e nvironm ental lssues relating to plant siting, de s ign , co nstruc tion and operation were addressed during permitting and licens i ng pha se s of plant development. In response to concerns raised by regulato ry agen c ie s, severdl design modifications were implemented. Addi tionally, bas el i ne studies, including nesting surveys of the Hutchinson Island s ea turtle rookery (G allagher et al., 1972 ; Worth and Smith, 1976), were con270ducted to establish background information on resident biotic commun i t ies. After a series of site certification hearings and satis f actory demonstra

- tion of environmental safeguards, the St. Lucie Plant rec eived its operating license , and the first unit was placed on line.

The importance of the Hutchinso n Island sea turtle rookery was clearly understood at the time of li censi ng negot iations (Rout a, 1968). Preop eration al and operational monit o ri ng focused on the potential disruptio n
o f 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., 198 3 ; Proffitt, et a1., 1 98 6 ). However, the potentia l for en training sea turt les 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 iqu e. Borrowing materials and experience from other researchers and loc al fishermen, a large -mesh "tangle" net was assembled and deployed
. Imme diate success in capt uri ng turtles demonstrated its app li cability
.

As the sc op e and persistenc e 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
271thereby minimize potential inju ri es an d trauma to the turtles. A lternative capture techniques were also evaluated.

Method s of preventing se a tu rtles from entering the intake canal of the St. L uc ie Plant were examin ed concurrently with the refinement of capture t echn ique s . Enginee ri ng. l ega l and s afety constra i nts pre clu ded installat ion of physical ba rr ie rs at t he m outh of the offs hore pipe s . Co ns equent ly, laboratory studie s con centrated on identi fyi ng effe ctiv e dete r rent mechani sms . t ifi ed
. To da te, no pract ical deterrents have b een ide nTh e principal objective of the St. Lucie Plant cana l capture program is to remove ent rapped sea turtles from the intake canal and return them to t he ocean as quick ly and with as little stre s s as possib le. Howeve r, in t he pr ocess, a great deal of info rmation relating to their biology and ecology ha s been obtained
. As with most large, far

- r ang ing m arine anima l s , collecting data from live t urtle s in the field is both diffi cult and
co s t 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 captive conditions and s tranded individuals. By contrast, the St. L

uc 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. T

his unique opportunity to examine the loc al sea turtle population has been exploited t hroug h an extensive data collection program.

272This 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.

273MATERIALS AND METHODS

Plant D es criptio n - Hutchinson Isla nd is one of a chai n of barrier island s separating the shallow Indian Rive r Lagoon fr om the Atlantic Ocean along Florida's lower ea st coast (Fig ur e 1)
. The St. Lucie Pl ant is lo ca 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
m

argin i s approximately 33 km offshore. The Flor i da cur rent flows roughly paral l el to the m argin but close r to shore (Gallagher and H ol linge r, 1 97 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 th e plant is abo ut O.S m . The adjace nt sea bottom co nsis ts of shifting sa nd and shell rubble with occasion al rock and ree f ou tc rop pings.

Co nden s er cooling water for the St. Lucie Plant is draw n from the A

tlanti 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 housing s. 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, respec tively. At mean low water, the caps are 2.4 m below the surf ace .
274N ......., U"1

## ~**~** HUTCHINSON ISLAND**~ O~** 

## ~~ 

## "%-0 '" /

Figure 1. St. Lucie Plant site location. L u C I**~**

o 250 ')00 M ETERSWithin the largest and smallest pipes, water velocities i ncreas e to 20 6 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.

A

t 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 cond enser
c ooling system. Heated water is discharged into a 670 m-long canal that l eads to two buried discharge pipelines. Thes e pas s 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, w ith Unit 1 bein g placed on line in March 1976. Unit 2 intake and discharg e 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 32,3 50 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 bridg e (Figure 1). Water flow is low enough to pennit turtles of all sizes to swim freely throughout this portion of the canal. 276Over the years, nets used to c apt ure turtles varied in le ngth, were 2.7 to 3.7 m in depth and made of 40. 6 cm stretch mesh, multi -s t 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 checke d severa l times a day for captures. Turtles entangled in th e nets floated at the water's surface unt i 1 removed.
Larger turtles occasionally breached th e AlA barrier ne t, 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, m eas 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 e s (mi nimum carapa ce length of Pritchard et al., 1983). Cu rve d c arapace length , straight -l i ne and curved carapace width, s t raig ht-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 19 82 , blood sample s 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 it ion of captured animals. Blood was rBnoved from the paired dorsal cervical sinuses using the tech277nique 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. 1 0100 hemoglobinometer. T he remainder of the bl ood was then centrifuged for 15 m inutes to separ ate cel ls and serum. Sex determinations were subs equ e ntly m ade by researchers at Texas A&t"1 University using a radioimmu noassay for serum testosteron e ( Owens et al ., 197 8)
. Beginning in 1984, blood c e ll samples were prov ided to th e National Marine Fisheries Service for the purpose of developing and r efining meth od s for use in conducting turtle stoc k analyses.

Each turtle captured wa s examined for ov e ra l l condition and s ubjectively ranked according to f iv e 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 identif y potentially unique macrofaunal associations and to provid e data
r e lat 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.

278RESUL TS

Spe ci es Abun dance

- Du ring the period from May 1976 through December 19 85 , a total of 1,310 sea turtle captu res took plac e in the intake can al of the St. Lucie Plant (Table 1). Of the five sp ec 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 operatio n, 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 w e r e mos t numerous in 1984 (69)
. The average annual catch of green tu r tles w a s 1 8 .9.

Si ze-Cl ass Di stri butions

- Loggerh e ad s removed from the i ntake canal ranged in len gth (S LCL) from 41.5 t o 11 2. 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 e ast 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 8 0 cm. Based on these divisions, da ta were segrega ted into three groups : juvenil e/sub- adult s «70 cm; t he dema rcati on between these two 279Table 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 1,310c ompon ents i s not well established in the literature) , adu lt s (>8 0 cm ) and transition a l ( 70 -80 cm). The latter group probably includes some mature and some immat ur e i ndividua l s. O f the 969 ind iv i du al s f or w h ich length data were co l l e ct ed , 76 perc e nt we r e 70 cm or less in l ength , the majori t y of these m ea s ur i ng between 50 and 70 cm SL C L (F i gure 2 )
. A bout 1 1 pe r cent of loggerhe ad cap t ur e s in vo lv ed adults, the r emaini ng 13 pe rcent repre senting individ uals i n t he t ra ns itional s i ze c la ss.

Green t urtl e s captured over the t e n 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 w eig ht f rom 0. 9 to 177. 8 kg. U nlik e logge rhe ad s, all gree n tu rtle s fel l into e ither the juvenile/sub-adult or adult cat egories ; i ndiv iduals were e it he r le s s than 66 cm or greater th an 9 3 cm in length (Figure 3) . T he m aj ority of greens captured (7 6 pe r cent) invo l ve d i ndivid uals less tha n 40 c m i n le ngth and 9 kg in weig ht. On l y fi ve of the green t urtles rem o ved fr om t he i nt ake can a l
were adults
.
Seasonal Distr i bu ti ons - O n a seasonal bas is , both l ogg e r head s and green turtle s oc cu rr ed with t he gre a t e s t frequ ency in w i nt e r . T h i rty-four percent of a l l l og ge rhead captures occu rr ed between January and March. However, when adu lt and j uvenile/s ub

- ad ult s egment s of th e po pulation we r e analyzed separat e l y, distinct d ifferences in sea sonal ab undan ce s were evident (Fi gur e 4 )
. J uve nile/sub

- adult s w e re most ab un dant dur in g the winter, whereas adults w e re captu red m o s t often in summ er ; nearly 65 percent of all adult loggerhe ad can al c a ptures occ ur red be t w een June a nd Septembe r .

281300-

(/) .....J c:x:: 200 - => 0 > 0 Z l1... 0 a: UJ en**~** 100 => - Z N =969

rf--

..--



## -

f--

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) •

282CJ)**~** 

### « ::J 0 > 0 Z lJ.... 0 a: w III**~** ::J 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) •

28320 - JUVENILE LOGGERHEADS N = 776 I--**~** 10 -



# - .--- r--**~**
JAN FEB MAR APR MAY JUN J UL AU G SEP OCT NOV DEC

C/) W a: 20 ADULT LOGGERHEADS :::> N = 112Ia.. <t () ...J**~** 1 0 0 I-**~** 0 W (.!) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC**~** Z W () a: w 60 JUVENILE GREENS a.. 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 th e St. Lu c i e Plant intake canal, 1976-19 85. 284Th e s e asonal distr ibu tion of yreen tu rt les w as ver y s kewed , 62 pe rc en t of all c aptures oc cu r r i ng duri ng Janua ry an d February (F i gur e 4)
. Cat c hes of other species were scattered t hr oug hou t t he t en-y ear s tu dy per i od. All but one of the seven leath erb ac ks w e re co llected i n Feb r uary, March and April • The hawksbill s w e re c apt ured in Marc h, July and August and the Kemp's ridleys in Janu a ry and Feb ruary.

Sex ratios Sin c e 19 82, 1 42 i mmat ure loggerheads (d efin ed by Wibbels et al
. , 1984 a s individual s l ess tha n 76 c m SLCL) we r e s e xed by means of radi oimmunoassay for bl ood t e sto ste r one . Females outnumbered males by a ratio of 2.38:1.00. Thi s r ati o i s signi f i c a ntly skewed in favor of females 2 _ (X , P - 0.05).
Recapture Frequencies

- Of the 1 , 31 0 s e a turtle cap t ures recorded between 1976 and 19 8 5, 54 r epr esent tu rt l es pre vi ously captured in the i ntake canal. A total of 32 l oggerhe ad s and one green were captured more than once, one loggerhead be i ng c aptured on six diff ere nt occ a sions. Recapture intervals for loggerheads rang e f r o m 4 to 858 d ays wi th a mean of 126.7 days (s.d.**~** 151. 3 days). Abou t 60 pe r ce nt of all re c apture incidents occurred within 90 day s of previou s c apt ure a nd 94 percent occurred within
one year (Figure 5). T he average period between fir s t and last capture for loggerheads was 215
. 4 d ays ( s . d.**~** 202
. 9 days)
. Over 80 perc ent of the recapture incidents involved juv e nil e/ su b-adu l ts.

285100 •

80 W**~ ~**  Z W () 60 a: w 

# I c... W , p' 

### > , 

### t:t ,

### '" N CO 40 ,a' 0"1**~** 

### " I :J f**~** p :J () 20

100 0 - - - , / -"

__ 0 -**~-** r

_....'

.... 0- .P' 9 ' J 

### , 4 f .,/ '" I**~** in terva l be tween successive capture s

o- - ----<l interval be twee n fi rst and last capture

200 300 400 500 600 700 800 RECA PTURE INTERVAL (DAYS)
Fi gure 5
. C u

mmu l ati v e p erce n t age of al l l oggerhead re captures occu r ri n g within various time intervals , St. L uc ie P

l an t intake canal , 1976-1985. 900DISCUSSION

Hutchinson Island suppo rts a large nesting population of loggerheads and to a much 1esser extent some nest i ng by greens and 1eatherbacks (Williams-Walls et al., 1983)
. Durin g 1 985, 4,877 loggerhead, 64 green and 18 leatherback nests w ere recorded along its 3 6 .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 incur sions by immature Kemp's ridleys, leatherbacks and hawksbil ls were also evidenced.

Nearshore coastal areas along the east ern seaboard of the United States apparently serve as migratory pathway s and/or aggregation areas for juvenil e and sub-adult loggerhead an d gree n t urtl es. In Flori da, re 1at 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 catche s of logg erheads 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 s ea turtle life cycle is poorly understood, the importance of Atla ntic coastal waters a s a developmental habitat is becoming increasingly clear.

287The degree to which canal capture data reflect the structure and dynamics of th e 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 th e intake structures between sexes and/or s ize cl asses.

Size -class data for lo gg e 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 popu1ati 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

288encountered in coastal waters. Nurtured by fo od suppl i es concentrated on the surface by oceanic fronts and convergences, the sm all loggerheads leaving natal beache s may drift for four or five years in the currents and eddies of the Nort h A tl 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 from the eas t coast of Fl orida , in cluding 10 years of canal capture data from the St. Lucie Plant, are cons istent with this hypothesis.
By compa ri son, the rnaj 0 rity of green turt 1es captured in the St. Luc i e Plant intake canal w as less th an 40 cm in length, sug gest ing that greens depart the pelagic habitat at a smaller size than loggerheads. The canal capture data also indi cate tha t green turt l 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 green s are not seen inshore until they reac h a si ze of about 35 cm (Balaz s, 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 (3 4 .3 cm) long. Only i n the Virgin Islands are there accounts of tu rtle s 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 th e Inajori ty of small gree ns are taken at the St. Lucie Plant. Whether animals of this siz e range are activ ely 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 determ ined. Because much of the hi stori ca 1 i nformat ion 289relating 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 s hed informati on regarding green turtles i nhabit in g 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 Mosquit o/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 sti nct ly different popul ation structures between the two areas.

290Mendonca a nd Ehrh ar t (1982 ) provided strong e vi dence to indicate th at green turtl es use Florida' s coastal bays and la goons as development habitats, foraging on the seagrasses tha t co nstitute their principal diet (Mortimer, 19 82; Mend onca , 1983, Bjorndal, 198 5 ). Hist orically, th e se inland waters support ed large populations of green tu rtles (E hrhart, 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, 19 84). Until this tra nsition is comple te, there is prob abl y no compelling need for small green s 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 c ount 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 m aturity, 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 bre edin g and foraging grounds (Meylan, 1982). Whether the se same animals will event ua lly c ons titute all or part of the Florida nesting populat ion is unknown.

291The heavily skewed seasonal distribution of green t urtle s off Hutchinson Island probably reflec ts me as ured movement s of this s pe cies in response to changing environmentd1 conditions and/o r chan ges in envi ronme nt al requirem ents (Carr, 1980). Bot h geographi c al and lo cal movements are likely to increase as water t emperatur es begin to decline (Mendonca, 19U3 ). Additionally, northeasterly storms Illay ex tirpat e some "lost ye a r " tu r tles from the pe l agic environlllent, th us increas in g t he number of small tu rtles found near sh ore during th e wint e r. Mu ch additional informa t ion \"Ji11 be required to determine th e r elat ive co ntr i bu tion of each of these facto r s to seasonal abundan ce patterns of green turtles at the St
. Lu cie Pl an t
.
Alt hough not as ext rene as that observed for green t urtl es , t he s easo - nal distr ib ution for juvenile/sub-adult loggerhead turtle s was also skewe d toward colder months of the year; 40 percent of all capture s 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 residenc e time ob serv ed 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 l y (W i lliams-Walls et al ., 1983 )
. Female s approaching the beach have a greater ch ance of encounteri ng the intake structures than t hose
292rel:1dining of fshor e, and as the nesting act ivit ies 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 th e timing and location of mating is not well doc ument ed, c op ul at ion is believed to occur off ne sti ng beaches prior to the nest i ng season (Ernst and Barbour, 1972; Geldiay et al., 1982, Mr oso vsky, 198 3 )
. St. Lucie Plant data suggest that either lIIatiny off Hut c hinson Island i s conf ined primarily to waters more distant fran shore than the intake struct ures or that reproductively active males are less attra c ted to the structu r es than a r e females. Changes in behavi ord 1 characteri s tics of se xually act i ve male turtles have been previously reported (Booth and Peters, 1 9 72 ;**~a la** **zs,** 19 80).
Repetitive capture s of ind i vidu a ll y marked tur t les in the St. Lu c ie Plant intake canal provide s ome clues as to the lenyth of residence within the Hutchinson Island population. O ve r the la-year m onitoring period 32 logyerheads and on e green turtle were c aptur 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. T ur tl 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 1i ty of re capture
. 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

293intake 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 s is (C arr, 1980; Hughes, 1982; Henwood, 1986), the general la ck of individu a l s i n th e canal wi th tag scars i ndi cate a true absence of 1ong-t ime re s i den t s . Similar findings \'Jere made for both greens and loygerhe ads 1n t he Mosqui to/ Indi an R i ver Lagoon where the longest ob s erved re s iden ce ti m es
were 20 and 15 months, respectively (Mendonca and Ehrhart, 1 9 82)
.
At least some of the loggerheads released from the canal are known to have migrated**elsewhere~** Two tagged lo ggerheads were recovered in Nort h Carolina, one in South Carolina, one in Georgia and one near St. Auyu s tine, 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 lo cainvolved 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 inform ation exists for the juvenile/sub-adult segment of this "population". Th i s is related primarily to the general inaccessibility of non-adult
294turtles
. Comp ared w ith s tu die s of ne sting females, r elative ly f ew r e search activiti e s 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 nd ant compone nt of the nearshore popul ati on . Mo s t tag r etu r ns from i m matu r e turtles come fro m i nci dental captures in f i shi ng gea r and s t r and i ngs on se asonally moni tored nesting beaches. Con s equ ently , t ag ret urns f rom cana l- c aptured turtl es, although fe w in numb e r, may reflect a sub s tantial am oun t of m ov ement within the juven i 1e/sub- adul t segme nt of t he we s tern Atl a nt i c logge r head popul ation. B ecaus e overall c anal c a pture s ha ve not decl i ned ov er th e years of plant op e ration , it al s o ap pe ars t hat emig r a t i on fr om and imm i gration into the Hutchinson Isl a nd a rea is re l ati vely w el l bal a nc ed
.

Until recently , sex r ati os of sea turt l e popu l ati ons w ere based primarily on counts of adults i n the wil d
. Observed f req uenci es often varied considerably betwe en l oca ti ons and s e a s on s (Ross, 19 84) and sex-dependent behavioral ch a ract e ri st i cs m ade int e rp ret ation of r at ios di fficu lt (Balazs, 1980; Limpus and Re ed , 1 985 )
. A r e la t i ve ly new r adi o immu noa s say technique
now permits safe and easy sexiny of j uveni le/ s ub- adult ani m als (Owens and Ruiz, 1980). B e c aus e of th ei r re l a t i ve abun dance i n the H utc h i nson Island population and thei r availa bility year aroun d, j uv e nile/sub-adult loggerheads lend**th ~ns** **lve s**  ni ce l y to stud i e s of pop ulat i on se x ratios.

For juvenile/ sub

- ad ult l oggerhe ads taken f rom t he St. Lucie Plant intake c dnal, fellial es s igni fic an t ly ou tnumbered mal e s b y a r at io of 2.4 to 1.0. Wibbels et al
. (19 84) s i milarl y found t hat t he sex ratios of immature loyye rheads taken from t he C a navera l ship channel w ere s i gn ificantly skewed
295in 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.

296ACKN OWL EDGEMENTS

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 (NMF S ) supplied tags and applicators for the tagging program and routinely furnished 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. T erry 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.

297LI TEf<ATURE C!TED

(ABI) Applied Biology, Inc.: Florida Power & Light Company St. Luci e Un i t 2 annual environmental operating report 19 8 5, AB-563. 97 pp . Atlanta: Prepared by Applied Biology, Inc. fo r Florida Powe r & L ig ht Company 1986 Balazs, G.H.: Synopsis of biological data on the green turtle in th e Hawaiian Islands. NOAA Tech. Mem. NMFS, NOAA-TM-NMFS-SWF C -7, 1- 14 1 (1980) Balazs, G.H.: Growth rates of immature gre en turtles in the Hawa ii an Archipelago, pp. 117-126. In: l3iology and conservation of se a turtles. Ed. by K. A. I3jorndal. Wa s hi ngton, D.C.: Smi t hs onia n Institution Pre ss 19 82 Booth, J., and J.A. Peters: l3ehavioral studi e s on the gre en t urtle (Chelonia**myda~)** in t he sea. Anim. l3ehav. 20,808- 8 12 (1972) 8jorndal, K.A.: Nutritional ecology of sea turtl e s. Copeia 1985, 736-751 ( 1985) C

arr, A.F.: Some problems of sea turtle ecology. Amer. Zool. 20,4 89-498 (1980) Carr, A.F.: Rips, FADS, and little loggerheads. BioScience 36, 92-100 (1986) Carr, A., and O.K. Caldwell: The ecology and migrations of sea turtles, 1. Results of field work in Florida, 1955. Am. Mus. Novit. 1793,1-23 (1956 ) Davenport, J., and P.J. Oxford: Feeding, gut dynamics. Digestion and oxygen consumption in hatchling green turtles (Chelonia mydas L.). British J. Herpetol. 6, 352-358 (1984) Ehrhart, L.M.: A continuation of base-line studies for environmentally monitori ng space transportation systems (STS) at John F. Kennedy Space Center: Threatened and endangered species of the Kennedy Space Center, Vol. IV, Pte 1, Marine turtle studies. Final Report to National Aeronautics and Space Administration, Kennedy Space Center. NASA Contract Report 163122 (1980) Ehrhart ,**L.r~.: ~larine**  turtles of the Indian River Lagoon system. Fla. Sci. 46, 337-346 (1983)

298Ern s t, C. H. , a nd R.W. Barbour: Turtles of t he United St a te s, 347 pp. Lex in gton : University Press of Kentucky 1972 Frazie r , J., D
. Ma r garitoulis, K. Muldoon , C.W. Port e r, J. Ro sew at er, C
. R

uc kde sc hel and S. Salas: Epizoan communities on m ar i ne tu rt l es, 1. Biva l ve and ga stropod mollusks. M a r. E c o l. 6 , 127

- 140 (1 985) Gallagher, R
. M., and M.L
. Hollinger : Nears ho r e m arine ecology at Hut c h i ns o n Isl and, Florid a : 1971-1974
. 1. In t r oduction and rationale. Fla. Mar. R e s . Publ. 12 , 1- 5 (1977) Gallagher, R. M ., M.L. H o llinger, R.M. Ingle and C. R
. Fu tc h : Marine turt l e nest i ng on Hutchinson I s land, Florida in 1971. Fl a . Dept
. Nat. Res
. Mari ne R e s earc h Lab
. Spec. Sci. Rpt. 37 , 1

- 1 1 ( 197 2) Geldiay, R., T. Koray and S. Balik: Status of sea t urtl e populations (Care tta c. c a retta and Chelonia m . my d a s) in the northern**r~editer ranean**  Se a , Turkey, pp. 425-434. In: Bi o lo gy and conservation of sea t urt les. E d. by K. A
. Bjorndal
. W a s hi ngt on, D
. C
. : Smithsonian Instit utio n Press 1982 Henwood , T.A
. : L o s s 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 c h ard s on , C. M cVe a, Jr., and**J.~ .**  W atson, Jr.: Worldw ide incid ental capture of sea t ur t les, pp . 489

- 49 6
. In: Biology and co nservatio n of sea turtles. Ed. by K. A
. Bj o rnda l
. washington, D.C .: Smith son ian Institution Press 1982 Huyhes , G.R. : Ne st i ng cycle s in sea turt les

- t yp i ca l o r atypical, pp. 81-90. I n : Biology and conservat ion of sea tu r tl e s. Ed. by K.A. Bjorndal .--Washin gto n, D.C. : Smi ths o nian I nsti tut io n Pre ss 1982 Limpus

### A C.J.,
.**nd** P. C.**ee ~:**  The green tur tl e Ch e l onia**my ~as**  in Queensland: prellf nl na ry des cnp t l on of the po pulatlon struc ure i n frogs and reptiles. Ed. by G. Grigg, R. Shi ne an d H. E hman
. Chipping Norton, NSW. Surrey Pe a t ty and So ns 1985 Mendonca, M.T.: M oveme nt s and fe ed i ng ec ology of imma t ur e green turtles (Chelonia myda s) in a Flo rida la go on . C ope ia 1983, 101 3-1023 (1983) Mendonca, M.T., and L.M. E hrhart: Ac ti vi t y , popu la tion s iz e and structure of the i mma tu re Che 1oni a mydas and C a rett a ca r etta in Mosquito Lag oon, Flo rida. Copeia 1982, 1 6 1- 167 (19 82) Meylan, A.: Sea t ur tl e m i gra tion

- ev idenc e fr om tag re t urn s, pp. 91-100. In: Biolo g y and c onserv ati on of sea t ur t les. Ed
. by K .A. Bjorndal. Washington, D.C. Smithsoni an Institution Pre ss 19 82

29 9Mey1an, 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 turtle s , pp. 103-110. and conservation of sea turtles. Ed. by K.A. Bjordal. D.C. Smithsonian Institution Press 1982 In: Biology Washinyt on , Mrosovsky, N.: Thermal biology of se a turtles. Amer. Zool. 20, 531-5 47 (1980) Mrosovsky, N.: Conserving sea turtles, 176 pp., London: 13riti s 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 se a turtles. Ed. by K.A.**Bjornda~** Washington, D.C. Smithsonian Institution Press 1982 O'Hara, J.: Thermal influences on the sw i m m

ing speed of loggerhead turtl e hatchlings. Copeia 1980, 773-7 80 (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 (19 86)

- - - Ro s s, J.P.: Adult sex ratio in the green sea turtle. Copeia 1984, 774-776 ( 1984) R

outa, R.A.: Sea turtle nest survey of Hutchinson Island, Florida. Quart. J. Fla. Acad. Sci. 30,287-294 (1968)

300Schmidt, J.: Marking ex periments wit h turtles in the Danish West Indes. 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) Worth, D.F., and J.B. Sm ith: Marine turtle nesting on Hutchinson Island, Florida, in 1973. Fla. Mar
. Res. Pub1. 18, 1-17 (1976)

301IMPINGEMENT 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 reduc e 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 fro m Atlantic menhaden (Brevoortia tyrannus) to bay anchovy (Anchoa mitchi 11 i)
.

302INTRODUCTION Power generating facilities us e 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 divers ion 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 mus t be able to detect and act ivel y swim away from the barri er . Various physical diversion structure s--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 succes s 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). N ormal intake flows for summer ( > 18.3 "C water temperature) and wi nter « 18.3°C) operation are 51.8 and 34.3 m 3/sec, respectively
. Flows as high as 65 m 3/sec have been repo rted during some periods of prediversion sampl ing, while 20 m 3/sec was recorde d during the lowest prediversion flow condition. These differe nces 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 obstru cting the water fl o w through the traveli ng screens. 303

## --_. _- - - -- - -- --- NORTH**~­**

## ~- CAROLINA 

# \("

{ WEIR RETURN

BASIN

FISH RETURN FLUME

SCALE 1000m ATlANTIC OCEAN SCAL E I
-- ---- - -1 IOOO m


### N

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

304A 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 CAP E FEA R R IV ER - -- ---!

..**~**

Overhead view of diversion structure and inset of copper-n icke l screen panels.

306MATERIAL S 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 e ction basket w ith 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 reco rded. Historically, fish greater than 40-mm standard length and blue crabs with carapace widths greater than 25 mm w ere impinged on the 9.4

- mm circulation screens. After the 1983 installat i 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 for half the year.

307RESULTS
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).

308Table 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%

309W I-' o T abl e 2. T ot al n umber and w e i ght (k g) of t h e f i v e mo s t abund ant species imp i nged per m il l i on cu bic meter s of coo l i n g w at er entra i ned at the B SEP duri ng p red iv ers ion and postdiversion peri ods includi n g the percent change between per iods. Prediversion Postdiversion Spe cies 1977 1978 1980 1981 1982 Mean _1984 1985

___**~ean** Change Brevoortia tyrannus 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, 24 8 5 , 97 1

- 43 .3%

18.7 15. 8 17.3 - 7 1 .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 1ant 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.

311DISCUSSION 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 diver sion 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 i es. 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 red ucing 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 ib1 e to imp ingement. Occasionally the diversion screen panels would fai 1 due to debris buildup caused by storms, lunar tides, or mechanical problems with the maintenance sy stem. During these unusual occurrences, juvenile and adult organisms may have entered the intake canal and subsequently impinged. T

h

e fixed-screen fish diversion A

tl 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 operation s illustrate the success of the BSEP fixed-screen fish diversion struc t ure. 312ACKNOWLEDGMENTS 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 ided rev; ew, Sandra Pr; ce prepared the map and f; gures, and the members at the Data Management Unit provided computer support.

313LITERATURE 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 pow er 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
314F INE MES H SC REEN S: A NEW APPROACH TO P REVE NTING ENTRAINMENT D

. B ruzek 

### K

. M ah adevan Mote M ari ne Laborato ry 16 0

0 City I sland Park Sara sota, Flori da 34236 V. Brueggemeyer E. T aft Tampa Electr i 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 w as hes, 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 ign of the fac i 1ity is based on the results of prototype screen testing at Big BEnd S t 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. Thes e studies indicated high survival of abundant fish eggs and in v ertebrates
. 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 , exc eeds estimates obtained from the prototype. Inve rtebrates suffer sl ightly higher than predicted mortality in the full -sc ale system , althoug h survival is high. This paper will present a description of the Unit 3 and 4 finemesh screen facil ity, will pres ent 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 in stallat ions.

315INTRODUCT ION In 1985 Tampa Electri c Company (TEC) placed in commercial operation a fourth generat ing unit (Big Bend Unit 4) at the Big B end Station
. The site is lo cated on the eas tern s hore 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 in to the cooling water system. Accord i ngly , early in 1979 TEC conducted a prototype evaluation of a f ine m esh screening system which could be util i zed to prot ect small organisms at this site as part of the 316 Demons t ration. Th e pro t otype studies we r e performed by Stone & Webster Engi neeri ng Corporat i on and Mote Mari ne Laboratory. Prel iminary studies in 197 9 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 ins tallation. Design efforts began in late summer with model studies which were conducted to optimize the screen's hydraulic characteristics and organism collection system
. Constructi on of the prototype screen system was completed in time to initiate bio l 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.

316During the study program, emphas is was placed on obtaining data for the follow i n g Representative Important Speci es (RIS): Common Name Bay anchovy Black drum Silver perch Spotted seatrout Scaled sardine Tidewater sil ve rside Stone crab Pink shrimp American oyster Blue crab Sc i ent ific 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 pos itive results obtained from the prototype screen system, EPA det erm in ed 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 resu lt s for organism survivability of both the prototype and full-scale studies , discusses the similarit ies 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 platform connected to 1and 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

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FIGURE 2 DECK A RRA NGEMENT FINE
- MESH SC REEN TEST FAC I LITYbetween 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 basket s 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 the n 15.2 cm, the speed would increase to 4.3 and 8 .5 mlm in, respect ively. On manua 1 control the screen coul d be operated at speeds b etween 0 and 8
. 5 m/min. Three speeds of 2. 1 , 4.3 and 8.5 mlmi n were selected for biologic al evaluation
. These speeds corresponded to maximum impi n gement durations of approxi m at 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 tes t platform and connected directly to the screen via a tran sit ion 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 achiev e velocities of 15.2 and 30.5 cm/s
. The discharge flow from the pump, comp osed 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 ins talled 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 -p ress u re (10 psi) spray header located on the ascending side of the screen ac ted 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 astrai n er was located on the ope rati ng deck and took suction from the f i ltered water (bow thruster 320EL.O'-O" TRAVELING WATER SCREEN**....-~** EL , -21' -6" 

# -12,-01-

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FIGURE 3 PROFILE ARRANGEMENT FINE-MESH SCREEN PROTOTYPEpump 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 th e container in which the org ani sms were transported to the l aboratory
. As mentioned , a land- based laboratory w as available for immed i ate proce ssing of all screen sample s . The laboratory facility was design ed 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 1at 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 objective 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 scree n 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 XWithin a given day the timing of the sampling procedure s was such that six samples could be collected and processed in the laboratory. Since t he pro cess of chang ing pu lleys to achieve different test ve 1 oc iti es requ i red several hours, it was not feas i b1 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 give n 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 hour s of 0900 and 1500). At the beginning of Phase 2, th e 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, abund ance and/or mortality differed be tween day and ni ght. Under this mode, samp li n g 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 Augus t). Regard less of phase or samp ling st rategy , the same pro cedures were uti 1i zed ina11 tests. Pri or to samp 1i ng, the bow thruster pump an d 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 scree n was in full operat ion and the movement of water and org anisms through the test faci 1ity was in steady-state , sampl i ng wa s initiated by turning on the low-pressure spray, allowing the contents of a predetermined number of screen baskets to be rinsed into the collection trou gh, and then shutting off the spray. The number of baskets washed differed for each water veloc ity/screen travel sp eed condition such that under each condition, the total volume of water sampled by the proto typ e screen was equ i va 1ent. Organisms washed in t o the collection trough were carried into a primary collectio n area (Figure 2) which contained a screened overflow (0.25 mm mesh)
. In this area, large debris (leaves, shells, ctenophores) 323could be removed as the area drained. Once the water level re ac h ed 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 co ntaine r . Once t he sampl e had be en completely transferred, th e container was covered and transported to t he land-based laboratory for sorting and l atent effects studies. In addition to screenw as h s amp l es, control organ i sm s w er e collected and held (as for other t es t s) fo r comparison to latent morta 1ity values experi enced among organ isms collected by the screen . The control sam ples 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 m id

-depth, where it was allowed to fish for f i fteen 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. Dur i ng Phase 1, control organ i sms 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 procedu res were carried out: 1. The transport container was placed in a water bath and temperature was recorded. 2. When RIS were abun dant, 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 i ned 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 o w

est taxonomic level possible without delay i ng init i ation of hold ing or adding incremental stress to the 324tes t organisms; cr ab zoea and m egalops were he ld indi vi duall y i n lots of 48. 6. A spec ies/l ifest age sample consisted of 30 org an i sms (48 crabs) ; therefore , once six lots of a species/l ifestage w ere counted an d recorded, they were transferred immediately to the holding area for the l atent effects study. 7. Sorting continued until samples of all RIS l ifes t ages had been placed in holding containers; the location of all organisms w as carefu lly documented
. 8. The remainde r of the subsample numbers of live, stunn ed, and (These dat a were used as determin at ions.) was sorted by sp ec i es, recordi ng de ad organi sms on data sheets
.

part of "init ial survival" 9. After so rt i ng was completed , the primary sample w as preserved for later an alysis , if needed. 10. When organism dens ities were l ow, several add iti onal subsamples were t ake n in order to obta in 30 live organi sms of available RIS for hol di n g. In this case, only the fi r st subsample was complete l y sort ed for live, stunned, and dead organisms; the remaining subsampl es were drawn only to br i n g the total of each RIS lifes tage to 30 (48 crabs), if possibl e . A ll organisms now in the hold i n g 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 organis ms whic h died during the holding period w ere preserved in labeled vial s fo r final i dentificati 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 reco rd ed and each group w as preserved in a labeled vi al. 13. Water qua lity parameters w ere reco rded frequ ently during all holding experiments ; parameters recorded i n cluded sal inity, temperatu re , dissoived oxygen, pH , and ammonia. 14. At the end of each latent-effects test, all vials w ere rechec k ed and all organisms were identified (to spec i es, if possible), categorized to l ifestage and coun ted
. These procedures w ere very effective in permitting an accurate accounting of most organisms fr o m collection t h rough fi nal identification.

325W N 0'\ Screen Platform



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# ~

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Figure 4 Debris Basket
Organilm Return Sump

Full-Scale Fine Mesh Screen Deck ArrangementFull-Scale Sys tem D esign The i nt ake design w as dev eloped on the bas i s of apply i ng finemesh screens to exi sting Unit 3 and proposed U nit 4
. Sheet piling encloses the p ump screenwell area, creating a fo rebay betw een the finemesh screens and th e pumps. A layout of the new screening structure is shown in Figure 4. Each of t h e six (three for each u nit) dual-fl o w fine-mesh screens were fitted i n th e sheetpile w all, and t h e intake flow pass es through the screens and di sch arge s into the forebay. The discharge op eni ng was sized to achieve a uniform flow distribution through the two parallel screen faces. To ens u r e proper hydr aulic conditions at t he four circulating water pumps and a relatively uniform flow t hro u gh each of the six screens, the forebay extends from the seawall abo ut 18
. 3 minto the intake channel
. T he pumps were pos i tioned t o aid proper flow distribution so that each set of two circul ating pump s draw s from three screens. Stop gat es cl ose the discharg e opening i n t h e event that a screen must be sto pp ed or removed for ma intenance. I n case of emergency conditions, roll er gates w ere inst alled in t h e sheetpil e wall between screens and open t o su pp ly water to the pump s if the pressure head differential acro s s the screens exceeds 0.46 m . To scre en the flow and protect the p ump s and condenser under this emerg en cy oper at ing mode, the existing coars e-mesh 9.5 mm screens were maintained on U nit 3, and new similar coarse -mes h screens were installed on Unit 4
. The dual

- flow screen design w i th 9.5 mm m esh has been used successfully at B ig Bend Units 1 t hrough 3 for many years and, based on testing to date , has the necessary featu res fo r p rotecting small organisms when fitted with fine screens. The n umb er an d size of the screens were de t erm ined on t h e basis of achieving a screen face velocity (approach veloci ty ) of 15 .2 cm/s at water level E1 0 .0 M LW. Based on the 15.2 cm/s veloc ity cr iteri on, six 3.05 m wi de scree ns were installed
. Each screen is su bmerged to El -8.5 m. E ac h of th e 53 screen baskets is equipped w i th eas ily replaceab le 0.5 mm mesh pan el s and fish collection buckets. The f i n e- me sh requires continu ous screen op eration to prevent clogging and to l imi t the time that organisms are i mpinged. 327Each 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 var i 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 w ater t o each header and take suction from the fine-sc reened water downstre a m 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 an d 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 i s 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. T

h

e cost required to add a fine-mesh screen system to Units 3 and 4 was $9

. 9 m i l l ion
. Full-Scale System Study Methods Meth ods used du r ing this study were essentially similar to those used du r i n g the F ine M esh S cre en Proto t ype study conducted in 1980. An on-site faci l ity was es tabl i shed at t he Big Bend station for t h e fi ne me sh screen surviv ability stu dies. This facility consisted of a 328test trailer with a flo w- t hrou gh seawater system, an adjacent office trailer, and a sample wash and stor age trai l er . The on-si te facility was located alo ng the intak e canal near t he fi n e mesh screens . All live meroplankton sorting and holding of organisms for 48 ho ur s was conducted at this faci lity
. The te st fa cility trailer w as the same one used for the prototype study and w as equip p ed with a flo w -th rough seawater sy st em consisting of two 1/2 hp pumps that pump intake canal water through four s and filters up to a 1130 1 head tank. T h

e filtered seawater would t hen gravity feed from the head tank through the h ol 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 oth er fish species wh ich appeared in large numbers along with any juveniles that were co llected were held in latent mortal ity experiments. Bec ause of the difficulty of distinguishing l arv ae of Menippe and Uooqebia dur i 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 week of March 1985
. Field studies were co n ducted each week fro m March 5 , 1985 until October 1, 1985, for a total of 31 weeks of sampling. Two collect ions per day and two per night w ere taken one day per w eek at the screenwash and organism return discharge statio ns . One collection per day and one per night were taken at the con trol station one day each w ee k. The low and high pressure screenwash of the fi ne mesh screens empties into a common trough which flo w s to a sump at t he beginning of the organism re turn canal. The screenwash st ation w as sampled by suspending a 1 meter mouth 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 h eld it open, reducing damage t o t he organisms as a result of fri cti on aga inst the net. The net was fi shed for three minutes, and all organisms retained were carefully ri nsed down into the bucket. The sam ple was then immediately returned to t he test trailer for sorting.
329The organi sm return di scharge (ORO) pi pes exi t at the end of a wa 1kway 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 oati 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 w as th en immediately returned to the test trailer for so r ting. The control sample was taken by lowering a standard 1 meter mo ut h diameter, 505 micron mesh net fr om a walkw ay bridge over the i ntake canal. Enough line was released to al low t he net t o sink to mid-depth, where it was allowed to fish for 15 minu t e s . 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 th e con t ents were then carefully poured into a bucket of ambi ent intake w ater. The sample was then immedi ately returned to the test trailer for sorting. After the samples wer e ret urned to the test trailer, the procedures used to assess initial sur vivability and latent survivorship were i denti 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 late nt survivorship studies was done for only 48 hours, with checks done at 6, 12, 24, 36 and 48 hours. Identifi cations were made at Mote Mari ne Laboratory through the use of standard 1iterature sources and MML' s reference collecti 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 w as necessary to combine identified taxa into groups since, in most case s, a s i n gle species, genus, or even family did not occur frequently 330TABLE 1 FISH EGGS PERCENT SURVIVAL AND HATCHABILITY Initial Survival**Hatchabilit~** 48-HR Survival 96-HR Survival 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 observationsw 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 indic ate 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 Xanthidae 99.1 95.9 95.6 74.9 73.4 w 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 observationsTABLE 4 DECAPOD MEGALOPS PERCENT INITIAL AND LATENT SURVIVAL
Init i a 1 Surviva 1 4B-HR Survi val 96-HR Surv ival Test Control Test Control Test Control Caridea 100 100 1 00 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 observationsenough to permit a meani n gful an alysi s . T he taxonomic l evel of each group was determi ned as t h e l owes t l evel w hic h w ould all ow inclusion of all important taxa. T

he test data indicate that the invertebrates had the highest survival, mos t often in excess of 90 percent; fragile f ish larvae, such as the bay anchovy (Anchoa mitch;lli ), had low survivorship, as anticip ated for larvae
. H o

wev er, it shou ld be noted that survival among control larvae was al so low . Further, as shown on Table 2, the small number of observations fo r some t a xa limits the conclu sions which might be drawn from the se data. The latent survivorship of those organisms whi ch were initially alive followin g collect ion w as 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 surviv al. Both measures provide an indication of the success of the device; however, past experience suggested that high m ortal ity at 96 h r mig h t 1imit the ut il ity of thi s measure. Taxa/lifestag es 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 niti a 1 survi val was determined
. The mean i nitial su rvivabilit ies are shown in Tables 1 through 4. The res u lts indicate that survivor ship is taxa- and lifestage-specific, as is the relat i on ship between 48 hr and 96 hr values. The hatch ability 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 sp ecies tested is quite rapid , nearly all 1ive eggs hatched prio r 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 h olding experiments with control samples which had not experienced the fine-mesh screen system are als o presented in Tables 1 through 4. These survivorsh ip value s indicate that natural mortality, not associated with stresses re sulting from the coll ecting and holding procedures , is a contributing fac t or to t he mortal itie s observed among organi sms co11 ec t ed by the fi ne-mesh scree n. Th erefore, observed test 335mortal ities should be considered as the cumulat 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 fluen ced i ni tial or latent mortality. These anal yses were limited t o the m os t abundant taxal l ifestages: among fi sh, Anchoa mitch i 11 i, Sci aeni dae an d C yn osci on spp . eggs and larvae were chosen; for inve rt ebrate s , Brachyura and Xanthidae zoeal and megalops stages and M enippe mercenari a zoeal stages were selected. In general , the analyses did not explain a high p r opor t i on of th e variat i on in mortal i ty. The independent variables which were mo s t oft en significan t (p**~** 0.05) were water temper ature and approach ve l oc i ty
. T he temperatu r e variable indicated decre asing survival with increa s ing temperature for a11 1ifestages except fi sh eggs. Lowest 96 hr survi val occurred du r i 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 lo n g periods under laboratory condit i ons. 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 an d 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 h r survival of Sc iaenid ae hatched eggs 89
. 5 79.3 96 hr survival of hatched eggs 76.8 64.0 48 h r surv i val of Xanth idae zoea 97.0 94.7 It m us t b e emphasized that both ap p roach velocity and water t emperature, whil e stati stical ly s i gnificant, explained a small amount of 336the variabili t y i n t he dep en dent var i able . T here fore , with i n the range of independe nt vari ab l es te sted, t h e m ean surv ; vorsh; p values presented in Tables 1 through 4 are good ind ic ators of the performance of the finemesh screen facil i ty
. 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 1ifestages which were collected from the three stations (Screenwash , ORO, and Control) over the duration of the study. In most cases, identified taxa w ere 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 n clusio n of all important taxa. The test data for i nit ial 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 lowes t at the ORO station and highest at the control station. The test data for latent survival are present ed in Tables 8 through 10. T he proportio n of organisms alive at 24 and 48 hours was used as an index of laten t 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 1arvae was generally around 50% , with no sign i ficant 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 survival 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.
337Table 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 PAGURIDAE X

ANTHI IDAE PINN O

T

HERIDAE GRA P SIDAE AL L IOEA: MEGA L OPS : 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 338Table 6. Summary data of initial survivab ility tests at the O rganism Return Discharge Stat i on, Big Bend Power Station (1985). (Survivability: 1.00 = 100% )

FISH EGGS:

CLUPEIDAE ENGRAULIDAE SCIAENIDAE SOL EIDAE ALL EGGS: LARVAE:

CLUPEIDAE ENGRAULIDAE ATHERINIDAE SPARIDAE Lagodo n 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. 4 0 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 0.63Table 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 A

L

L LARVAE: INVERTEBRATES IOEA:

PENAEIDAE C

ARIDEA P

ORTUN IDAE PAGURIDAE X

ANTHIIDAE PI NNOTHERIDAE G

RAPS IDAE ALL I O E

A: MEGAL O

P

S : XANTHI IDA E G

RAPSIDAE A

LL MEG A

L

O

PS: 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 340Table 8. Su mmary data of laten t survi vabil ity te sts for 2 4 an d 48 hour s, S

creenwash Station, Big B end Power St ation (1985 ). (Survivabil ity : 1.00
.. 100%) L A

TENT S URVIVABI LI TY Total # Organ isms 2 4 hr s 48 hr s Te sted Mean S.D. Mean S.D. FISH E

GGS: CLU P

E

IDAE 4 0.2 5 0
. 35 ENGRAU LIDAE 322 0 .45 0
. 13 SCIAE N

IDAE 549 0.44 0.04 S

OLE IDAE 8 0
. 30 0 .1 8 ALL EGG S : 883 0
. 36 0.10 LAR VAE : C

LUPEIDAE 2 8 0.59 0
. 12 0 .44 0 .1 6 ENGRAU LI DAE 2,200 0.77 0.10 0.6 8 0
. 04 A

THER IN IDAE 1 0.00 0
. 00 0.00 0.00 SPARIDAE Lagodon rhomboid es 1 0.00 0.00 0.00 0.00 SCIAENIDAE 1,852 0 .7 3 0.02 0
. 63 0.04 B

ai rdiella ch r vso ura 6 0
. 50 0 .50 0.50 0.50 Pog on i as cromi s 7 1.00 0 .00 1.00 0.00 Cyno scion nebulosu s 2 0
. 50 0.71 0.50 0.71 C

ynosc i on arenarius 143 0.5 7 0
. 04 0. 44 0
. 13 Le iostomus xanthurus B

L

E

NN IIDAE 15 0
. 62 0.2 8 0 .6 2 0
. 28 G

OB IIDAE 39 0.39 0.55 0
. 36 0
. 50 SOLEIDAE 94 1 0.98 0.03 0
. 96 0
. 04 AL L LARV AE : 5,2 35 0 .5 5 0. 32 0. 5 1 0
. 3 1 INVERTEBRATES IOEA :

P

E

NAEIDAE 52 0.95 0.07 0
. 95 0.07 C

A

R

IDEA 1,992 0. 78 0.01 0
. 67 0
. 06 P

O

R

T

UNIDAE 34 0.96 0.06 0. 81 0
. 03 PAGURIDAE 97 0.77 0.07 0 .76 0.09 XANTHIIDAE 1,771 0
. 88 0.02 0 .80 0.06 P

INNOTH ERIDAE 3,499 0
. 85 0
. 00 0
. 71 0.04 GRAPSIDA E 176 0.9 1 0.07 0
. 85 0.03 ALL I OEA: 7,621 0. 87 0.08 0
. 79 0.09 MEGA LO PS: XANTHIIDAE 215 0
. 99 0
. 02 0
. 97 0.04 GRAPSIDAE 1,230 0
. 98 0.01 0. 95 0.00 ALL M EGALOPS : 1,445 0.99 0.01 0.96 0.01 JUVENILES:

L

olliguncula brevis 44 0.0 3 0.01 0.0 2 0
. 03 341Table 9
. Summary data of 1atent 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 E

NGRAULIDAE 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 SC IAENIDAE 1,376 0.83 0.06 0.66 0.00 B

ai rdiella chrysoura P

ogonia s cromis 1 1.00 0.00 1.00 0 .00 C

ynoscion 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 G

OBI lOAE 7 0.67 0.47 0.67 0.47 S

OLEIDAE 873 0.93 0.09 0.90 0.11 A

LL LARVAE : 3,529 0.73 0.30 0.69 0.29 IN V

E

R

T

EBRATES IOEA:

P

E

NAE IDAE 27 0.99 0.00 0.97 0.03 C

ARIDEA 2,118 0.79 0.00 0.66 0.00 P

ORTUNIDAE 6 0.88 0.17 0.90 0.14 P

AGURIDAE 76 0.81 0.09 0.68 0.14 XANTHIIDAE 1,799 0.81 0.04 0.71 0.06 P

INNOTHERIDAE 3,674 0.80 0.00 0
. 65 0.00 G

R

APSIDAE 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 G

R

APSIDAE 1,469 0.96 0.03 0.94 0.04 A

LL MEGA L

OPS: 1,541 0.95 0.02 0.93 0.01 JUV E

NI L E

S: L

oll ig u ncu la brevis 4 0.00 0.00 0.00 0.00 342Table 10. Summary dat a of 1atent survi vabi 1i ty tests for 24 and 48 hour s , Contr ol S tat io n, Big Bend Power Station (1985)
. (Su r vivab il i ty: 1.00 

### = 100% )L ATEN T SUR V

IVABILITY Total # Organi sm s 24 hrs 48 hrs Tested Mean S. D. Mean S .D. FISH EGGS:

CLUPEIDAE 1 0
. 50 0
. 00 ENGRAULI D A

E 30 0.5 1 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, 36 1 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 .9 5 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 ,3 62 0.9 5 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 343Table 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

344Table 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

345Table 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 Pro t otype wash ORO INVERTEB RATES : Caridea 94 72 70 85 67 66 Xanthidae 99 93 90 96 80 71 P

in notheridae 100 99 83 92 71 65 FI S H LARVAE: A

nehoa mi t chilli 2 16 58 22 68 65 Sei aenidae 19 61 56 11 63 66 FI S H EGGS: Anch oa m i tchi l li 43 48 29 80 82 91 S

ci aen idae 75 63 56 95 84 91

346DISCUSSION Based on the survivability results of the 1980 prototype study , it was concluded that the installat i on of fine-mesh screeni ng at the Big Bend Power Stati on Units 3 and 4 repre sented a viable technology which would resu l t in lowered entrainment l osses . Those result s showed a high initial survival and hatchability of fish eggs; a high initi al and latent surviv al of invertebrate tax a; and a relatively low initial and latent survivabil ity of fis h larvae, among both test and con t ro l organisms. Results of the 1985-86 full-scale study showed similar init ial and latent survival and hatchability of fish eggs; a high initial and latent survival of inv ertebrate taxa; and a lower initial and latent survival of fish larvae (Table 13). However, the fu l l-scale study exhib ited higher initial and laten t survivability of fish larvae than th e prototype study. It is reasonabl e to as sume t hat these differences are rel ated to the sampling technique s used for the two studies. It can al so be seen from the results of both studies that there are natural mortali t ies in the organisms being studi ed
. Survivability of organi sms from the contro l stations showed 1ittl 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 limit s w hich 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 m ize the fine mesh screen hydraulic characteris ti cs and organism return discharge
.

347POWER 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 effect s 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 ity-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.

348INTRODUCTION F

ew subj ects hav e received as much scrutiny over the la st fifteen years as power pl an t i n take effect s. Sc i enti sts and eng in eers have produced a formid able number of papers on the su bject. W ithin the constraints placed on this presentation, there were thus two possibilitie s: 1) select one small aspect of intake effe cts and deal with it exhaust ively ; or 2) present an overview of the whole sub ject with an emphasiS on conclu s ions. This is an overview. T he focus is on assessment, b ecau se every utility is facing or w ill face t his task in the near future . T his revi ew begins w ith an op i ni on , examines the current state-of- t he-art t o support th at 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 w ord "drift" has over 30 m eanings or synonyms , according to Webs t er's N ew Twentieth Century Dicti onary, Unabridged. Each of t he se mean i ngs, or synonyms, implies a lac k of control over directi onal movement. Drift ing organisms are suscept ible to the thermal, chemical, and/or phys i cal effects of entrainment or to impingement on i nt ake screens. Less rec ognized is the relevance of the concept of drift to the science of assessment itself
. My opinion is that the major p roblem of power pl ant in take as sessment has been ident ifi ed
. This problem i s the current inability to quantify population control mechanisms, both density-independent and densitydependent (compensatory). However , bec ause there has been no concerted effort by ei ther t h e 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 p re sentation. The thes is of this presentation, then, is that the utility industry and regul atory agency communities need to focu s research on quantifying p opul ation control mech an isms. I wi ll attempt to direct attention to the need for this research by deali ng with thre e questions: what are we trying to do; how well are we doing it; and w h

y aren't we doing it better? The answers may seem to b e belabori n g the obvious
. 349More likely, they will be highly contestable. If so, this presentat ion wi 11 have successfully stimul ated di scuss ion. 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 effe cts of power plant impacts. Consideration of the three questions is directed t oward supp ortin g 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 decisio ns depend on dollars for electri city (a rna i nten ance of des i r abl e environmental conditions. Three law s 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 en vironment (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 philo sophy, suggesting that impact assessment at the individual level is n eeded before assessment at higher levels of organization is possible. This is reasonable but not
350universal ly accepted ; others would argue that eco sys tem funct ion i s the important cri terion. However , if there i s agreement that decisions regarding devel opment and en vi ronmental protection are socio-political , then ecosystem func tion p er se does not appear suffic ient: it does matter to the publ i c , for exampl e , whet her fish p rotei n is i n the form of carp or trout. T he an throp ocentric i ty of societal val ues m ay require multipl e-leve l assessmen t ev en if the philosophy of assessment is holisti c. T h

ere are few w ho woul d argue again st t he desi rability of includi ng tot al ecosystem costs i n assessment, but many would argue that this is unfeasi bl e. Thu s , p oint s of difference b etw een utility and regul atory biologi sts have general l y ev olved into quest ions about the type of information t hat is n eeded t o demonstrate best the balance between b enefits and cost s of generat i on . H

OW W ELL ARE W E DOING? The disc ussion of t his question is subdivided accordi ng to the differe nt level s at which as sessments can be conducted (Figure 1). Although an swers are provided for each level , they are subjective and therefore open to debate. Exposure Expo sure does not ap pe ar to be a very useful concept with respect to impingement
. Th i s is partly du e to t he probl em of defining impingement exposure. Are al l fish found n ear the intake exposed to impingement? P robably, this is not the case, because some species collected i n the area of intakes r arely or n ev er appear on the screens (Loar et al
. 1981; Logan and Kle in streuer 1981 )
. However, authors of both the cited papers fo u nd t hat , for certai n speci es, distri bution and abundance in the w ater body w ere importan t 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 imping ement? Or does t he individu al truly es cape. Do the live fish found on the screens when t h ey are raised represen t the exposed group, or are they Si mply in t he interi m stage between impi ngement and the effect
351of impingement (death)? The poin t is that there is not yet a cl ear definition of impingement expo sure, much less a means to estimate it. Entrainment exposures at thermal electrical power plants hav e all been based on the assumption that exposure is proportional to the pl ant flow re 1ati ve to t ota1 water body flow or volume (Engl ert et a1. 197 6 ; Goodyear 1977; Boreman et al. 1981 ). In some cases, a correction factor has been added t o account for distribution of entrainable organisms i n the water body. Hydrodynamic m odels also appear to require correction fac tors to acco unt for behavi oral mechanisms that allow limi ted independence from net water body flo ws (Swartzman et a1. 1977) . T h

e assumpti on that exposure to entrai n men t is proportional to flow and plankton di stribution does not appear ill ogi cal
. H owever, the patchine s s of plankton distribution and the inability to s a mple continuously either n

ear the intake and/or within the p lant suggest that entrainment ex p

os u re estimates will not be verifiable. Es timatio n of exposure to entrainmen t at hydro-electric plants appears less tractable than for thermal electric power plants. Mos t of the concern about expo sure 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 - motile. 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 obt ai ning representat ive samp 1 es of fi sh in t h e fl ows through and around the turbi nes at m ost hyd ro-electric sites make it difficult to measure exposure or to validate pred ictions based on relative flows. Predictions of exposure of eggs and relativel y non-motile larvae in the water column above hydroelectric si te s 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 realis tic predict ion of impingement mortality at power plant s h as been slow
. Im pingement model s have been constructed, bu t most are based on assumptions that are known to be unrealistic (see 352

### Logan and K l ein streuer 1981 and references therein)
. Oth er as sessment model s ut i l ize impingement coefficients that are of quest ionable general i ty. Consensus supports fish distribution, swi m speed and effects of temperature on swim speed, and overall fi sh fitnes s as par ameters important fo r predicting impingement. Pred iction s usi n g a model includi ng the se parameters (Logan and Kleinstreuer 1981 ), h o

w

ever, ranged from 20 t o 548% and 35 to 143% of actual numbers imp i n ged for threadfin and gizzard shad , res p ectively. The range of these di fferences 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). Hydrodynamics in the int ake areas are not simple, thu s, predict ions of impingement mortality mu st be viewed with healthy skepticism
. Substantially more progress ha s been made t o w

ard measuring impingement. Spatial and temporal designs have been d ev eloped to solve the probl em s inherent in predicting tot al yearly impi n gement from limited sampl i ng at operating power plants (Murarka et al
. 1978)
. If these sampling des i gns are followed, confidence intervals can b e calculated for the impingemen t estimates. Mort a1i ty of organ isms (algae, zooplankton, i ch thyop 1ankton) exposed to entrainment at thermal elect r ic power plant s is both predictable and measurable. Studies with condenser si m u

lators (Cada et al. 1981; Jin ks et al. 1978, 1981; P oje et al. 1982) and at operating power pl ants (Jinks et al. 1978 , 198 1) have shown t hat mortal ity of entrained org anisms depends on the physi cal (thermal , mechanical) and chemical (bi oc i de s) stresses encountered. Results i n t h e laboratory show relatively good agreement with those observed at power pl ants as long as levels and ti m e courses of stres s or exposure at t he p ower plant are carefull y du pli cated (Ji nks et al. 1978, 1981). In add ition, sampling designs (B oreman and Goodyear 1981) and collection t ech ni ques (McGroddy and Wyman 1977 ; Jin ks et al. 1981) are sufficientl y a dvanced 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 n ew or operating power plant s, or it can be measured once a plan t is on-line .

353P rediction and measurement of mortality of fish entrained at hydroelectric plants are more difficult than at thermal electric p l ants
. Effects are thought to be mediated via pressure changes (e.g ., cavitat ion), shear forces, and contact with conduits or turbines (Ruggle s and Coll ins 1981). However, it has not been possible to relate types of physical injuries specifically to on e of t hese sources . S ystem ch ange s also generally affect more than one of th ese mortality sources, so it is difficult to isolate the ir contributions t o mortality. Add to this the fact that system s i ze and the relative size of the system to that of the fish are important determinations of mortality, and it becomes clear th at predict ions must be based on studies at full- scale fac ilit ies (Turbak et al. 1981)
. Unfortun ately, the large v olume s of water passing through most hydroelectric plants make full- scal e studies difficult at man y sites. Full-scale studies have yielded wid e ranges of mortali ty estimates (Ruggles and Collins 198 1). In some cas es the differences can b

e semi-quantitatively related to system de sign or operation, but truly quantitative conclusions are subject to valid criticism. Predicti on of effect s of h ydroelectric plant entrainment th us seems possible on ly in gross terms. Even measurement is probably feasible only at a small perc entage of operating plants
. Sublethal or indirect effects of entra inment at hydroelectric o r thermal electric pl ant s are thought to occur but are largely unquantified. Post-exposure observations of impingement or entrainment effects in the laboratory or at power plants h ave not extended past a few days , at most. This obviates obs ervation of possible longer -term sub 1 etha 1 effects. Laboratory stud ies have shown that hungry pred ators selecti vel y prey on stress ed fish when stressed and unstressed prey fish are presented together (Coutant 1973). Observations that fisherme n congregate near the discharges of both hydroelectric and thermal electric power plants suggest that predatory game fish are actively feeding in those area s, 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 stres sed fish may not be amenable to field investigation.

354

### Popul ation Res ponse Methods for estimating population response to intake effects can be div ided into three classes depending on the level of the population for whic h predi ctions are made. Young-of

-the-year (Y -0- Y) m odel s are designed to pred ict the loss of the portion of population produced during a gi v en year. Adult population models are designed to predict the effect of Y

-O-Y los ses on the population that woul d exi st 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 abov e), 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 pred ictions, but natura 1 mortal ity rates are assumed not to be affected by power plant included mo rtal ity. In other words, these models are all based on the assumpti on that dens ity -dependent (compens atory) regulation is not operat ive on the Y-O-Y life stages. Such an assumpti on must be judged as conservati v e, surely protecting or over-protecting the year cl ass of fish, bec ause: 1) compensation is generally thought to operate during the earl y l ife stages (Science Applications, Inc. 1982) ; 2) fish populations have demonstrated the ability to maint ain population stability in the face of heavy fis hing mortality (McFadden 1977); and 3) model studies have shown that loss es of Y-O-Y fis h, even without compensat ion, are substantially less severe than equi val en t los ses of reproductiv e and fishabl e a dults (Christensen 1985)
. A third set of these models includes eff ects of power plant mortalities on natu ral mortality by including density- dependent term s in the model formulati ons. These models seem potentially more realist ic, but both the

355forms and 1 eve 1 s of the compensatory re 1ations have been subjects of great controversy (Christensen et a1. 1981). Th i s controversy has raised even more questions about impact predi ctions 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 h rows doubt into the co st-effectivenes s of mit igation measures based on Y-O-Y models. Est imates ba sed on t hes e mode ls will not neces sarily be indicative of the best choices for society, because it is not clear that these Y-O-Y loss es have any rela tion ship to long term fis h populati on changes
. Neverthel ess, Y-O-Y models have probabl y played a larger ro l e in sociopolitical decisions than t h e other t ypes of population models. Adult populat i on models i nclude those de veloped by Horst (1 975), Goodyear (1978), and Rag o (1984). These models translate losses of Y-O -Y to adult fish by using a number of di fferen t, sometimes co mplex, conversion factors. P olg ar et al. (198 1) extended this type of projection to an "ecosystem type" analysis by conducting such extrapolations for multiple populations in a single ec osystem. Regardless of t h e factor(s} used for extrapolation, each of these analyses has been bas ed on the assumpti on that natura 1 mortal ity is unaffected by power plan t induced mortality. 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 models
. 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), stockas sessment (Jensen 1982; Jensen et a1. 1982; Stanford et a1. 1982; MacCall et al
. 1983), and age-structure (Van Winkle et al. 1974; C

h

r i sten sen 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 i ct multi-generat ion populat i on effects. Each of these models inc 1 udes on e or ore dens ity-dependent funct ions, requi red to counter i m pact-prod uc ed extinct ion.
356None 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 relat ive importance and quantifi cation of density-dependent (compensatory) re lati onships in the parent-progeny and stock-assessment models. Lack of agreement about quantification of specific density -dependent re lat ionships in the more mechanisti c age - structure models has made predictio ns based on them controversial
. Thus, l ong-term population predict ions of impact have made only a li mited contribution to decisi on s about citing and operation of power plants. Community Respons e It has not been uncommon t o deal with power pl ant effects at the community leve l. F or 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 us eful in some impact ass essments , althoug h under certain circumstances these appear as likely to be measure s 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 v ed from cluster analysis, ordination, and niche breadth/speci es pac k ing. However, communi ty simu l ation models per se do not appear to have been developed for assessment of intake effects. This is probably due to benefit-cost cons iderations and t o the real ities of assessment. Community analys es m ust 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 ecosy stem analysis. On the other hand, power plant imp acts are thought to mimic abiotic effects. Stric tly defined, commun i ty level analys es thus ignore some of the interacti ons of most interest in impact asse ssments. It is not surprising, then, that power plant impact models are generally available

357for popul ati on or ecosy stem ass essm ent s , but not for co m

m

u

nity as ses sment s . Ecosyst em Res ponse Applicati ons of eco system mode ls for im pact anal yses w hi ch are useful for regulatory/industry purposes have been r are. The rea sons are di v ers e but p rob ably relate t o cost , effort , and u ncertai nty of predicti ons. All of**th s~**  t en d to incre ase as lev el of analysis proceeds from indi vidual to ecosy st em (Fi gu re 2)
. Extrapo latio n of effects on i ndiv idu al s to th e ecosystem l evel of organizat ion require s i dent ific at i on of the stru ctu re of p opulations and commu ni tie s and q

uantifi cation of t h ei r fun cti onal rel at ions i n respon se to b ot h bi ot ic and abiot i c cond i tion s. A t t h e " simple st " level, th is can b e accom pl i sh ed wi t h t rophi c leve l (food web) models combi ned with fe edback l oops via decomposit i on and nutrient regener ation. T h

ere are prob l em s wi th assessmen ts of t his type (Pikitch et al
. 1978 ) , h oweve , especial ly if speci fic organisms or organ i sm groups are of part icul ar i n terest. Conver sel y , attem pts t o defin e and quanti fy all of t he relationships i n an ecosy stem run u p agai nst inf ormatio n gaps at t he popul ation and community levels of organ i zation
. Given t he complexity of ecosystem stru cture, such anal yses become compu t at i onally unwieldy , if not impossible
. T hus, ecosy st em anal yses h ave al l i nvol v ed some aggregation into groups . B ut combin i n g l ead s to l oss of in formation and reality. T

he ecosystem m o

dels summarized below as exampl es involve various level s of aggregatio n to faci li t ate analys is. K

emp ( 1981 ) used a t rop hi c dynamic m odel to compare the regional energy costs of once-throu gh and cl os ed- cycle cool i n g of a third power plant added at a si te where t wo u nits alre ady were oper ating. The model was a simpl i fied s imulation of biomass standing crops and transfers in a complex ec osys tem. T r an sfers were comb i ned into two food chains depending on the fo o d source (pl ankton, detritus) of the primary con sumer s. T he m o

del w as calibrated using data from control areas, then tested by compar i n g model p redict i ons u nder conditions caused by the two existing plants with data collected near t h ose pow er plant discharges. Agreement was "rel ati vely cl os e" so t he m odel wa s used to predict changes
358expected from addition of the third plant. Impacts were trans lated to photosynthetic energy equivalents using biomass t r an sfer efficiencies between troph i c levels and bi o mass to energy conversions. Earlier vers ions of this analysis were based on us ing total community m etabolism as a proxy for energy flow (McKellar and S mith 1981). Ecosystem energy losses using a once-through cool i ng m ode were t hen compared to energy and ecosystem costs of bui l di ng and operat i ng mechanical draft cooling t owers to mitig ate the effects of once-through cooling. The energy costs of mit igation were esti m ated to be ab out 15 to 20 times the energy loss es of the eco system impacts. This type of an alysis, however, as sumes t hat energy is equiv alent whether it i s in the form of "game" or "trash" fish

- - an assumption th at is n ot real isti c . Researchers at t h e Illinois Natural Histo ry Survey (ILHS 1979a, b, c, 1980 ) in cooperation with C ommonwealth Edison Company staff, constructed a Cool ing L ake E cosys tem Model (CL EM) as part of an effort to assess effects of operation on the Kincai d Generat ing Station on Lake Sangchris in III inois . A p hys i cal model (TEM P) was used to describe water temperatures and volumes in fou r area s of the cool i ng reservoi r based on meteorological and plant o perational condition s. The ecosystem model (CL EM) consists of a series of su bmodel s , whi ch describe phosphorus , detritus , ph yt oplankton , peri phy ton, macrophytes, zooplankton, benthos, and fis h d ynamics
. Each of the biological submodels is composed of a seri es of different ial equati ons describing physiolog i cal processes . Thes e included food int ake, digestion, respiration, exc retion, reprod uction, growth, and mort ality as functions of water temperature. M ass is conserved with in and betw een all compartments and num bers are als o conserved within the fish submodel. Transfers are gener ally mediated via food-consumer inter actions and mortality. Sport fishing i s 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 aggregate s al l (and only) herbivorous species
. The fish su b

m

odel t re ats eight age classe s each of the sportfish blueg ills, largem outh bas s , w hite bass, and ch annel catfish , and the for age fish, gizz ard shad, separately. The model allows 359evaluation of different management scenarios (e.g. , plant operation and fis hi ng regulations). The TEMP model provided reasonable fi ts t o temperatures measured in Lake Sangchris; t he CLEM was on ly partially evaluated using labor atory and field data. The structure of the CLEM is general enough to b e applied at other cooling lakes, but th is has not been attempted. Porce 11 a and coworkers (Porce 11 a et a1. 1983; Gri eb et a1. 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 hydrodyn a m

ics model t o predi ct chemical conditions at several depth strata. Trophi c level analyses can include several groups of species. For examp le , green algae, diatoms, bl ue-green algae, and "others" were used to represent primary producers in the L ake Norman validati on studies
. Model verificat i on studies were conducted at Lake Norman, a cooling reservoir in North C aroli na. The model was cal i brated using one set of data from the reservo i r, then evaluated us ing 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. Eco system models inherently include some compensatory functions in their formulati on. As l ong as these models include mass balance stru ctures, loss of individuals within a trophic level will result in increased growth of the remaining indiv i duals at that level because of the larger p er capita availability of food. However, other compensatory relat ionships , including disease and parasitism, are not explicitly included in these models. These i n cl u de disease and parasitism. Other
360density-depen dent (compensato ry ) trophi c transf er rate changes are (or can be ) included in ecosystem models. For some speci es , these rate change s are based on empi ri ca 1 data; for ot hers the rate changes are based on generaliz ation of data from studie s on other species. The model of Porcella et al. (1986), for exampl e i n cl udes a m ix of species-specific and generic relationships t o esti m ate effec t s of growth on predation. The data bas e fo r Quant ifi cati on of such re 1ati onsh ips is the same as that which limi ts p opul ation l evel assessments definition and quantificati on of p o

pulation i nteraction limits b oth p opulation and ecosystem level as sessm ents . In other words , t he ecosystem models are l imited in predictive capab ili ty by p ro bl ems s im i lar to those that limit succe ss of population models. Defin itio n and quantification of complex rel ationships within and between individual species p opul at ions are neces sary for accurate assessment of eco system impact s of p o

w

er plants. WHY AREN'T WE DO IN G BETTER? There i s no s imple an sw er to th is ques ti on. Devel opment of new or improvement of existi n g m ethods of me asu rement and predi cti on at all levels of asse ssment from expos ure to ecosystem (Fi gure 1) will improve power plant impact assessmen ts. F or example , improving m ethods of fish population sampling would impro ve ass essments at al l levels. Assessment of effect s on all components of t h e ec osystem is the ultimate goal. However, prog ress tow ard t h at goal can be has ten ed by focus i ng on the level or iss ue that mos t limits the usefulne ss or acceptance of current assessments
. For as sessment of effects at the individual level, eXisting methods appear adequate for use at steam el ectric plants but need improvement to ensu re reasonable acc u racy 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. Thus , regardl ess of t h e initial focu s, it appears that the current question of m os t i n t erest is: w hy aren't we doing better at assessing impacts of power plants on population s? One way to approach the answer to this more re stricted question is to consider an example
. The "Hud son River Controversy" (Barnthouse et
36 1al. 1984) is an excellent example, b ecause of t he extensive documen t ation of the scientific analyses, the i r evolut ion , and their contri bution t o the ultimate socio-political decision (see S wartzman et al. 1977; Christensen et al. 1981; Barnthouse et al . 1984 and referen ce s therein ). In br ief, the H udson R iver uti lity companie s agreed, among st other things, to flow reductions and scheduled outages duri ng certain p eriods of the year i n return for maint ai ning once-through cooling
. Flow reduct ion s and out ages were des igned to protect sens iti ve 1ife st ages only during those seas ons. The basis fo r the nego ti ated settlement w as a series of comp arisons of conditional mortalitie s res ulti 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 mort ality, but no den s ity-dependent (compensato ry) functions
. Cum ulat ive effects of yearly los ses also cannot b e cons i dered with these model s. The rea son that thes e model s w ere used wa s b ecause the two sides could not agree on the l evel of dens ity

-dependen t regulation in fish popul ations in the Hudson, or which l ife stages were affected b y these con trols
. Without such agreement, long-term projections of population response (e.g., for striped bass) remained controversial. In other words, b ecause density-dependent population regulation could not be demonstrated or quan tified objectively, mit igation actions were based on assessment at t h e 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 s i s for that decision ind icates a majo r deficiency in the science of impact assessment. Because density-dependent m

ech anisms could n ot be i ncluded in the impact ass essment, the cumulative yearly impact s on Y-O -Y were ignored. Whether the former would ameliorate the latter is open to question. Until density-dependent mechani sm s can be quantified, there can be n o scientifically object i ve conclusion. It should be clear that, until the ability to determi ne the level at whi ch a population can sustain it self in the face of anthrop ogenic sou rces of mortal i ty 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 canc el , so that soci ety
362does not incu r too much in the way of unneeded economic or ec ol ogical costs
. The science of power p l an t imp act asse ssment is drifting, and the problem is apparent. Identi ficati on and quantification of densi ty
- dependent (and den sity-independent) population controls are n eeded 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 power generation. It is time to make this effort; otherwise, like fish eggs and larvae in front of power plant intake screens, w e wi ll continue to drift on in to more troublesome area s . ACKNOWLEDGEMENTS Many indiv iduals have contribu ted to t he ideas in this paper; several provi ded the benefit of discu ssion while it \"las being written. These include Sigurd Christensen, Tho ma 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. REFE RENCES Barnthouse , L.W ., W. V an Winkle, J. Gol umbek , G.F
. Cada, C.P. Goodyear, S.W. Chri stensen, J .B
. Cannon, and D.W. Lee. 1982. Impingement impact analyses, evaluations of alternative sc reeni ng devices, and critiques of utility a nalys es rel at i ng t o density-dependent growth, the age- structure of the Hudson River striped bass popula ti on, and the LMS real-time life- cycle model. ORNL/NUREG/TM-38 5 / V2
. Oak Ri dge, TN : Oak Ridge National Laboratory. Barnthouse, L.W., J. Boreman, S.W. Christensen, C.P. Goodyear, W. Van Winkle, and D.S. Vaughan. 1984. Popul ation biology in the courtroom : The Huds on River controversy. BioSci ence 34:14-19. Boreman, J. an d C.P
. Goodyear. 1981. Bias es in the estimation of entrai nment mortality. p. 79-89, In: L.D. Jensen (ed.), Issues Associated with Impact Assessment. EA Communications , Sparks, MD.

363Boreman, J., C.P. Goodyear, and S.W. Christensen. 1981. An empirical methodology for estimating entrainment loss es at power plants sited on estuaries
. Trans
. Am. F ish. Soc. 110:255- 262. Brown , P.W. 1986. Legal and institutional aspects of hydropower development. p. 1-58, In: R. Arndt and J. Gulliver (eds.), Small scale hydropower development: planning, feasibility and design. Chapt. 13. Univer sity of Minne sota, Minneapo lis. C

ada, G
. F
. , J.S. Suffern, K.D. Kumar and J. A. S ol omon. 1981. Inve stig at ions of entrainment mortality among larval and juvenile fishes using a power pl ant simul ator. p. 111-122, In : L.D
. Jensen (ed .), Issues ass ociated with impact ass e ss ment. E A Communications, Sparks, MD
. Christensen , S.W. 1985. Evaluating effects of acidi ficat ion stress on the reproductive potential of in teroparous fish p o

pulat ions . Abs tract s of the 115th Ann
. Meet
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. Soc., Sun Val ley , 10. , Sept. 8-12. Christensen , S.W., W. Van Winkle, and P.C. Cota. 1975
. Eff ect of Summit Power Station on striped bass population s . Testimony before the Atomic Safety and Licensing Board i n the matter of Summit Power Station, Units 1 and 2, M arch 1975. USAEC Docket Nos. 50-450 and 50-451. Washington, DC
. U.S
. Atomic Energy Commission. Christensen, S.W., D.L. De Angelis, and A .G. Clark. 1977. Development of a stock-progeny mode l for asse ssing power plant effects on fish popul ations. p. 196

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. 2: development of empi ri ca l multivariate relationships for evaluating fish commun ities in new cooli ng l akes. EPRI Rept. EA 2059. Electric Power Res
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. ILHS (Illinoi s Natural H i st ory Survey). 1980. Evaluation of a coolinglake fishe ry volume 1: Introdu ct ion, water quality and summary. EPRI Rept. No. EA-1148. Electr i c P ower Rese arch Inst itute, Palo Alto, CA. Jensen, A.L. 1982. Impact of a once-through cooling system on the yellow perch stock i n the w estern bas in of Lake Erie. Ecol. Model. 15:127 -144. Jensen, A.L., S.A. Spigarelli, and M. M. Thommes. 1982. Use of conventional fis hery models to assess entrainment and impingement of three Lake Michigan fi sh specie s . Trans
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. MacKenzi e , S. Vega-Gonzalez, and J.R. Lund. 1985. Sampling des ign fo r aquati c ecological monitoring. EPRI Rept. EA 4302. Electric Power Research Institute, Palo Alto, CA. MacCall, A.D. , K. R. Parker, R. Leighiser and B. Jes see. 1983. Power plant impact assessment: a simple fi shery producti on model approach. U

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. Supplement I to in fluence of Indi an Po i nt Un it 2 and other steam electric genera t i ng pl ants on the H uds on River Estuary with emphas is on stri ped bass and ot h er fi sh p op ulations . Consolidated Edi son C o ., NY. McGroddy, P.M. an d R.L. Wyman. 1977. Efficiency of net s and a newm device for sampli ng living fish larvae. J. Fish. Re s . Bd. Can
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. Stat istical compari son and choices of sampling designs for estimating fish imp ingement at cool ing water intakes. p. 267

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. Production foreg one: an altern ative method for assessing the consequences of fish en trainment and impingement losses at power plant s and ot her water i nt akes
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. E.A
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ol. (Berl.) 10:347-352
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. No. Am. J. Fish. Mgt. 2:285-29 3. Swartzman, G., R. Deriso, and C. Cowan. 1977. Comparis on of simulation model s used in assessing the effects of power-plant-induced mortality on fish populations. p. 333-36 1 , In: W. Van Winkle (ed.), P roceed i ngs of the Confrence on Ass essing the Effects of Power - P lant-Induced Mortality on Fish Populat ions
. Pergamon Press, NY. Turbak, S.C., D.R. envi ronmental Reichle issues and C.R
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368 Shri ner . 198 !. to small-scal e Analysis of hydroelectricdevelopment IV: Fish mortality resulting from turbine passage. ORNL/TM-7521. Oak Ridge National Lab., ORNL/TM-7 521. 112 p. UEC (United Engineers 

### & Constructors )
. 1975. Applicants supplemental testimony (mathematical model) on entrainment of striped bass by Summit Power Stat ion. Testimony before the Atomic Safety and Licensing Board in the matter of Summit Power Station, Units 1 and 2, March 21, 197 5. USAEC Docket No. 50-450 and 50-451. Atomic Energy Commission, Washington, DC. Van Winkle, W., B.W
. Rust, C.P. Goodyear , S.R. Blum and P. Thall. 1974. A striped bass population model and computer programs. ORNL/TM-4578. Oak Ridge National Laboratory, Oak Ridge, TN. Van Winkle, W., S.W. Christensen , and J.S. Mattice. 1976
. Two roles of ecologists in defining and determining the acceptability of environmental impacts. Inter. J
. Envir. Stud. 9:247-254. Warsh, K.L. 1975. Hydrological-biological models of the impact of entrainment of spawn of the striped bass (Morone saxatilis) in proposed power plants at two areas in the Upper Chesapeake Bay
. Rept. No. JHU, PPSE-TI
. Johns Hopkins Univ., Baltimore, MO.

369IMPACT 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 gati on and envi ronmenta 1 enhancement wi th more than ten years of experi ence. The objecti ve of thi s impact mit igation 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.

370INTRO DUC T

IO N Florida Pow er 

### &L i ght C ompany (F P L) i s th e fifth largest investor owned util ity in the U .S
. and serves m ore 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 s idential and commerc i a 1 customers, in contrast to other areas of th e country, where industrial customers dominat e. Within our service area , which encompass es all or part of 35 co u ntie s, 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 th e system is provided by nuclear energy, one - half by oil and natural gas, an d the balance by interchange and pu rcha se pow er. The Company owns and manages approxi mately 325 km2 of 1and in Florida. Thi s land is located in urban and rural areas and comprises wet 1and and upland areas . Much of it i s undeveloped and is used as a buffer zone to isolate power plants, substations, and transmission lines from agricu ltural and residential 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 interes ting challenges. For ins t ance, 40% of ou r service territory includes wetlands, swamps and lakes; about 40% i s forested, and about 20% is cropland or urbanized. The Company must build or ma intain power plants, trans mission lines, and substat ions in all these env ironments. Climates in Florida show great variati on also and cre ate habitats for a diver se 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. O n 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
371large number of plants and animal s are ne ar extinction
. On the federal l evel , more t han 60 plants an d animals of Fl or ida has a more comprehens ive li st th at i n cl ude s 54 1 species of con cern (Wood, 1986). D

uri n g the produ ction and transmis s i on of electri city , FPL i n teracts with both co mmon and endangered specie s. Fl orida Power & Li ght Co
. i s an active participant i n im pact m

itigation and environmental enh an cement with more than ten years of experi ence. T h

e objective of the efforts i s t o fost er t he compatibility of w ildl if e and the p roduct i on of electri city (Wil cox, 1979, 1980 ; M

org enthal er, 1987)
. The pri mary focu s of thi s work ha s b een on feder all y de si gnated endangered and threatened speci es , but t h e effort s have exp anded to migratory species, state protected species, and habitat conserv ati on . Tan gible bene fits have accrued to b ot h wil dlife and FPL and will b e reviewed in thi s paper . D

IS CUS SION W

est Ind i an M anat ee The Wes t Indi an manatee is an endangered m ar i ne mammal that FPL has inter acted with exten s ivel y over t he las t 10 ye ars. Because of the intolerance of the species to water temper atures be l ow 190 C, the animal has sou ght th e once-through thermal dis charg es of five FPL plants along t h e east an d we st coasts of F l orida
. In regu l atory proceedings before the Environmental Protection Agency (EPA) , thi s speci es constituted a key fac t or in t he permitting review. B ecause of t h e Endangered Species Act, E

P

A wa s requ i red to consult w ith ,the U.S. F ish an d Wildl ife Service (US FWS) to i nsu re that the "p ermitt ed activities would not likely jeop ardize the cont i n ued existen ce of an endan gered spec i es"
. Ut il i zat ion of t he thermal di scharge by manatees was one of the factors that i nfl u en ced EPA to 1 et F PL cont inue oper ating in the oncethrough cooling mode , instead of off stre am by a dd ing cooling towers. Taken to wors t case extremes, this deci s ion saved the Company and its rate payers approximately $300 million at two power pl ants. As part of the consultation in this regulatory proce s s, F PL and USFWS decided that not enough was known about the interaction of m an atees and power plants. To mit igate any impact on the manatee from thi s reg u latory decision, FPL
372agreed to conduct two manatee programs : an aeri a 1 cen su s p rogram and a publ ic awareness program. The aerial program ha continued on a yearly basis si nce 1977 (Reynolds and Wilcox, 1986). B

enefits h ave accrued to the res ourc e and the company from these aeri a 1 surv eys. The primary b enefit fo r the manatee i s sci entifi c data on which to base conservation and management efforts
. These counts were, in part, t h e 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 inc l u de: national and state rec ognition 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 spons ored or conducted these publi c awarenes s 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 1iterature 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 w i ll go out of their way to h elp an inj u red manatee or will respect boat speed limits in manatee s anctuar i es. Each piece of literature di stributed has FPL's name on it, even though it is unobtrusive. However , it is still a tan gibl e expre ssi on to the publ ic and FPL's ray pa yer about FPL's commitment t o the envi ronment. Personnel of the Riviera plant located near Wes t Palm Beach have developed an innov ative method to provide warm-water effluent to manatees. Becau se the two units that h ave traditionally attracted the animal are no l onger operational, plant personnel dev ised a method to Siphon heated effluent from two other operational unit s 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 op erationa 1 unit at the plant. T he siph ons intercept a small portion (1%) of the heated effluent from the units before it is
373di 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 n g 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 w ater to assist their survival.

Another example of impact mit igati on for manatees occurred at FPL ' s Ft. Myers plant i n January 1985. Because the un its were not operati ng for vari ous reasons, the Company was faced with a s i tuation where no warm effl ue nt was ava i1 ab 1e t o aggregati ng manatees that had traditionally been co nditi oned to this discharge (Packard et al., 1985). A paradox arose: doe s FPL operat e a generati ng unit just to keep manatees warm ? As ambient water temperature cooled during this January an- d ap proached 1eve 1s 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 th e warm-water di scharge 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 agre ement , the unit was operated for 11 days out of economics (e.g., FPL cou ld have pro duced elec tri city cheaper at another plant) during the months of January and February. The sole reason to operate the plant was to enh ance 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

374it again. Therefore , an al t ernative method to p rov i de a thermal discharge to m anatees w as needed. After much di scus sion and evaluati on, FPL dec i ded to tap ground water under arte si an press ure. A series of three 25 cm diameter w ells were drilled up to 260 m depth
. The ground water temperat ure was 23 0C, 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 b enefit 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 C ompany has interacted with endangered or threatened sea t urtles over the la st ten years, pri maril y at the 

### st. Lucie plant on the eastern co ast of central Fl orida. The species include: green (endangered in Florid a); leatherback (endangered); Kemp's ridl ey (endang ered) ; Hawksbill (endang ered); 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 turtle s with a vari ety of programs. Some programs have been driven by the regu latory proces s, and some have been voluntary. B ecause 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 turtle s were unexpectedly taken from the in take canal of the plant. The turtle s had entered the ocean intake structures and traveled through a series of 1arge underground cul vert s to an open canal, where 375they 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 researc h 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 w i thin the 1imits of the law and with the concurrence and understanding of federal and state agencies. The cost to p hys ically exclude turtles from the St. Lucie plant was estimated at $200 m il lion for a one-time capital co st and a yearly maintenance cos t 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 igati on and env ironmenta 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 nes ting 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 exten sive 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 376turtle s or the survival of their hatchling s (O'H ara , 1980)
. This knowl edge has ex p

edited the renewal or i ssuance of federal and state permits
. One impact on sea turtl e b ehavior ident i f ied in the permit review process w as 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 1ighting and , where 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 i ronment and to v ol untari ly mi tigate any impact from beach 1ighting in general, FPL h a p rodu ced a bumper st i cker and poster to promote awareness of t urtle hatc hling disorientati on and what the general public can do about this probl em. Addit ionally, the company has produced and distribut ed a bill ins ert promoting this awareness of hatchling disorientat ion to FPL customers on the east coas t of Florida. By promot i ng thi s awareness, the re source is benefited and FPL i s established as hav ing an environmental conscience. Another form of voluntary miti gat ion invol ve s the turtle walks that the Comp any provides as a public servi ce . Organized and guided tours to view a female sea turtle crawl up on the b each to lay her eggs are very popular natu re 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 awarenes s mater ials on se a turtles; these materials are distri b uted at the walks 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.
377American Crocodile Fl ori da Power & Light Company interacti 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 lo cated 60 km south of Miami and produces electricity with fossil and n u

clear units
. Subsequent monitoring (i.e., a form of voluntary mitigation) outside the regulatory or permitting arena establ i shed that a small but viable crocodil e population inhab its the site, all of which has been designated by the U SFWS as critical habitat. Details and results of this monitori ng program are given in Gaby et al
. ( 1985) and Masotti et al. (1986). T his mon itori ng program ben efited the resource becau se it estab li shed the dynami cs of the population , recruitment of animal s into the next size class, the behavior of animals, and how they partitio ned the environment
. All this is useful data
. These studies also b ene fi ted the Company during federal l icensing activities of the nuclear units. As with many nuclear is sue s, intervenors use all types of strategies to prevent or delay this 1icensi 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 answer 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 i m pacts of thes e activities, a crocodile management plan was drafted and reviewed by all affected FPL Departments. By knowing the behavior and 1ife 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 under standing of the animals and is another example of FPL's commitment to the environment.
378Southern Bald Eagle F

l 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 in sure the compatibility of company operati ons or construction and the well-being of an endangered species. Details and result s of the pro gram are gi ven in Williams-Walls (1986). This monitori ng program verifi ed the mitigation policies established by the U.S. Fish 

### &Wildlife Service for eagle nest ing (USFWS, 1987). The servic e recommended two buffer zones around an act ive eagle's nest and the level of human activities th at w ou ld not disturb the pair of eagles.With prior knowledge of th i s 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 cons tru ction 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 Bar ley Barber Swamp was sing led 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 h e are a.

379Through 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 ident ifi ed as we 11 as a rookery ay'ea of the endangered w

oodstork
. Other import ant species obs erved i n clude southern bald eagle s (endangered) and ind i go snake s (thre aten ed)
. To d emons trat e the compat ibil ity of the sw a

m

p with the Mart i n P

lant , the Comp an y constru cted a 2. 2 km lo ng boardwal k through the heart of t h e sw amp an d op en ed it to vi sitor s b y ap po i ntmen t. The boardwalk , co mpleted in 1980 , offers vi sitors a un ique opportunity t o view a pri st i n e w etl and and u plan d community as it m ay have exi sted b efore the vast land alterations and water contro l effort s of the last 100 years . T

o furt her en hance t he fu nctioning of this un ique area, a ser ies of management and enhan cement pl ans w ere drawn u p and i m plemen ted w ith exp ert help
. These plans call ed for channel i zi ng wate r into t he swamp from reserv oir seepage sumps to simul ate sheet flow; manipu l at ion of water l evel s to si m u

l ate hydro peri ods for t h e wet and dry season; con t ro ll ed b u

rns to m ai n tain certain area s in specific stages of ecol ogi cal su cces s ion; and effort s t o con t rol exotic vegetation . The management plan recommended that several 300- 500 year old Indian moun ds adjacent to t h e sw amp be pres erved and checked fo r archeological s ignific ance. The b enefit s to the resou rce are overwhelming. Not only have eagl es and w ood stork s nes t ed intermi ttentl y in the swamp, but over 150 species of bi rds have b een identified in or around the swamp. Species 1i sts for mammal s an d rept il es are also extens i ve. Twenty spec ies of ferns and six species of orchids have been identified, as well as over 200 species of wildflow ers, plants and t rees. The benefits to t he Company are also overwhelming. Since the openi n g of the boardwalk, over 12,000 vi si tor s from 30 states and eight fore ig n countries h ave t ou red the sw a

m

p by appointment through FPL
. These visitors have been fo r themselves how a power plant can operate 3 km away and yet be comp atibl e with the resou rce. Many of the visitors touring the swamp are from conserv ati on organizations, such as the Aud ubon Society , Sierr a Club , and Nat i v e Pl ant Society. The swamp has proven to b e so popular w ith t h ese organizat i ons that they plan seasonal 380tours to observ e ch anges in the flora and fauna
. The significance of all these contacts i s 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 an d benefi t both the res ource and private industry. Utility management may have difficulty ju stifyi ng and accepting the costs for the program cited , but it is up to the util ity bi olog i st or a similar counterpart to point out the tangible and intangi ble benefit s to the Company. As part of FPL' s Q ual 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 bes t 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 w ork wi th t he system in order to benefit both the resource and t he business commu nity alike?

381LITERATURE CITED E

rnest, 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 plan t. 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 power 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 I sland, Florida in 1971. Fla. Dept. Nat. Resour., Mar. Res. Lab. Spec . Sci. Rept. No. 37:1-11. Mazzotti, F.J., B. Bohnsack, M
. P. M cMahon and J.R. Wilcox
. 1986. Field and laboratory observat ions on the effects of high temperature and salinity on hatchling C rocody1u s acutu s . Herpeto10gica 42:191- 196. Morgenthaler, E. 1987. Ecology effort: a Florida util ity win s naturalists' praise for guarding w ildlife. 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. F i sh 

### & 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 stribut i on and abundance of

the West Indian manatee (Trichechus manatus) around selected Florida power plants following winter cold fronts, 1984-1985. Bio1. C ons. 38:103-113. USFWS. 1987. Habitat m anagement 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. 382Coord.) 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. Spat i 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.

383WHEN ARE TEMPERING PUMPS AN EFFECTIVE BAT FOR MITIGATING THERMAL IMPACTS? Linda R. Cadman

A. F. Holl and Stephen B. Weisberg Versar, Inc. ESM Operations 92 00 Rumsey Road Columbia, Marylan d 21045 ABSTRACT Thermal impacts of once-through cooling are sometimes mitigated b y 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 i sion w as made to discontinue their use. Further exami nati on of model inputs suggest that temper; ng umps woul d only be effective at C halk Point u n

der a limited set of ci rcumstances. T

hese analyses demonstrate the need for evaluating the ecological costs in relation to anticipated benefits for any mitigative measure .

384INTRO DUCTI ON Sect io n 316(a ) of the Clean Water Act requ ires utilitie s t o comply with state and federal thermal effluent limitations or dem onstrate that discharge s do not adversel y affect balanced indigenous p opulat ions
. One means used to meet thermal effluent limitati ons a nd reduce adverse thermal impacts is to l o we r the temper ature of the di scharge water by diluting it w i th unheated water. Dilution occurs before the discharge is returned to the re ceivi n g water body and i s accomplished b y large pumps (referred to as temp ering or diluti on pump s ) th at transport water from the intake are a to t he disch arge area. Temperi ng p ump s, however, increas e a facil ity ' s total water wi thdrawa 1 rate. T he i ncrease in water w ithdra wa 1 rate produces an increase in t he n umber of organisms suscept ibl e t o impingement and entrainment. Therefore , decre ased t h ermal impact s are gained at the expense of hi gher impi ngement and entrainment m ust b e evaluated before the effectiveness of temperi ng pu m

ps as a m itigati ve technology can be assessed
. In 1967, tempering p u

mp operat i on was initi ated at t he Chalk Point Steam Electric S tation · (SES) to mitigate th ermal i mpacts
. At the time, no analysis of the adverse impacts of increas ed entrainment was conducted. In 1985, we developed a simpl e model fo r evaluating the trade

- offs be tween reduced di scharge t emperatu re and increased entrainment losses as sociated with tempering p umps. Thi s model was used to estimate re lat ive increases or decrease s in total 'plant-induced mortality due to tempering pump operat ion at C halk P oint
. METHODS Study Site The Chalk Poi nt SES, loc ated i n the estu ar ine port ion of the Patuxent River, Marylan d, uses 30 m 3 of water per sec on d fo r once-through cooling
. Cooling water is withdrawn from a 137-m-long i nt ake canal and returned to the Patuxent R i ver 2 km up st ream fro m t h e plant via an 18

-m-wide discharge canal (Fi gure 1). Intake stru ct ure s are protected by a barrier net, a trash rac k, and traveling screens. O rganisms entrained or impinged at the pl an t are wa sh ed into the di scharge canal. Transit time for a passive parti cl e th ro ugh t he disch arge 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).

--

386of Natural Science s of Philadelphia , 1983). Temperature at the head of the discharge is as much as 20 0 Chigher than the intake temperature (Mart i n Marietta Environmental Systems, 1985). The average**~T** during the summer is 7.40C. From 1969 to 1985, three tempering pumps, each w ith a pumping capacity of about 5 m 3 sec-I, were used t o pump water directly from the recei vi ng water body to the di scharge canal from Jun e to September. Operation of all three temperi ng pumps reduced the t emperature at the head of the di scharge canal by about 2.70C and by le ss than 0.5 0C in the nearfield (Academy of Natural Sciences of PHiladelphia, 1983)
. Analytical Approach The general app roach used to eval uate th e effect iveness of tempering pumps involved identification of all sources of power plant-induced mortal ity and compari son of total m ortal ity \'Ii th and wi thout temperi ng pump operation
. The generali zed model was of the form: Total P l ant
- Induced Mortality Intake Screen Impi ngement

Mortality Tempering Pump Entrainment +

+ Mortality + Circulating System Entrainm ent M

ortal ity +
Nearfield Mortal ity Tempering Pump Imping ement

Morta 1ity

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 impingeme nt and entra inment term i ncludes m ortality 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 mortality of organisms residing in the nearfield area t hat is caused by t h ermal or chemical stress induced by the discharge effluent. When the model was applied to Chalk P oi nt, several terms in the model were not included because they were not al tered substantially by tempering pump operation; they were, 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 387morta 1 ity between the two operati ng modes. The components not included in the analysis for Chalk Point were**circulati lg**  system entra i nment, 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 w here the temperature reduct i on due to dil ut i on occurs (Martin Marietta Environmental Systems, 1985). Temperi ng pumps at Chalk Point are unscreened. Thus, temper i 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 b

e 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 (A cademy 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 1argest reduction in**~T** anywhere in the receiving water body due to tempering p

umps was less than 0.5 0C (Academy of Natural Sciences of Philadelphia, 1983)
. Aft er deleting the sources of mortality that are unaffected by temper i ng pump operation, the formula applied at Chalk Point SES was redu ced 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 as soci at ed with the mechanical stresses of impingement plus the addit i onal mortality due to thermal stress when the organisms are wished into the discharge canal (Table 1). IlOO1ediate impingement losses were 388Table 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

389calculated by multiplying the total number of a species impinged during June through September by the immediate impingement mortality rat 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 m

ortality due to thermal stress when surviving organisms are washed into t h e discharge canal. Temperi ng pump entrainment mortality was calculated as the product of the total number entrained during June through September an d the immediate entrainment mortal ity rate. these parameters for Chal k Point (T able 2) were taken from 

### li (1982)
. Estimates of Hirshfield et T

he t h ermal mortal ity component of both impingement and tempering pu mp 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 therm al mortal ity rate was calculated using th ermal tolerance data obtained from th e 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 determ ined based on available literature estimates and values for LT25 a

nd LT75 were estimated by linear interpolation. To estimate the average thermal mortality rate for the summer months, the expected percent mort a 1ity for each temperature i nterva 1 (e. g ., between the L T 25 and the L

T

50 ) was weighted by the of time the discharge temperature was in that tem p

erature interval. The frequency distribution of discharge temperature over t ime was determined from monitoring studies conducted in the di scharge. An organism's temperature tolerance depends on its thermal history, and therefore our model was run twice assuming different accl imation temper atures: 17 0 C and 32 0 C. Intake temperature at Chalk Point during the study period ranged from 17 0 to 32 0 C. Thermal mortality was minimized by assum ing that the organisms impinged or entrained at the plant were a

ccli m ated to 32 0 C for the entire study period. Similarly, thermal mort ality was maximized by assuming that the organisms were acclimated to 17 oC. Parameter values used for estimating thermal mortality for each species and acclimation are given in Tables 3 through 6
. 390Table 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%

391Table 3. Parameter values used to estimate blue crab thermal mortality at Chalk Point SES with an d without tempering pumps operatin g Proportion of Time Sp en t in Interval t !Temperature Mortality

Interval t Rate Pumps On Pu m p s Off A

CClimationl ( • 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
. 0 9 2 39.0-39.5 0.75 0.003 0. 060
>39.5 1. 00 0.092 O. 1 31

•.,4

392Table 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 0.346Table 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 0.346Table 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 (F t )
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 0.368RESULTS 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 temper i ng pumps operating than without the pumps operating (Table 7). The conclusion that tempering pumps are detri mental rather than bene ficial to the Patuxent River ecosystem was substantiated by sensitivity analys i s of the model to input parameters. For example, immedi ate i mpingement mortality rate can range from 0 to 100%. Analyses ind icated that altering impingement mortality rate alone did not change th e outcome of the model. That is, even if all organisms surv iv ed 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 betwee n 

## a and 100%, with one exceptio n. If the blue cr ab mortality due directly to being entra ined through the tempering pumps is very low (le s s tha 22% for the high accl imat ion sc enari o and l ess than 3% for the l ow acclimation sc enario), 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 imm ediate mort ality for entrained blue cr abs was 41.8% (Potomac E l ectric Powe r Company , 1984)
. If delayed mort ality had been inc l u ded in this estimate, t he mortality est i mate would have been even higher
. T

he effect of varying the .1T reduction caused by the tempering pumps was also examined. F or 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
. 50 C
. To r educe the discharge temperature at Chalk Point by 4.SoC would require t he pump; ng of about 46% more dil uti on water than is currently pumped
. T

his would greatly increase the number of organisms entrained through temper; ng pumps. Therefor e, it is un 1ike 1 y that any errors in the 396Table 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

397parameter estimates used would alter the conclusion that tempering pu m

ps at Chalk Point are detrimental. At Chalk Point, the general model for estimating changes in t ot al mortality was reduced to two components
-- tempering pump entrainment and intake screen impingement. The trade-off to be considered was s impl y reduction in thermal mortality of impinged organisms in the di scharge canal versus the additional mortality due to tempering pump entrainmen t
. The anal ysi 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 accept able technology for mitigating thermal effects because they actual ly in crease the number of organisms kil led by the plant
. Altho u gh tempering pumps were ineffect i ve at Chalk Poi n t and a similar finding was made at the B i g Bend faci l ity in Florida w here operation of dilution pumps was discontinued (U
. S. E nvironmental P

rotection Agency, 19B1) , there are situation s where tempering pump s coul d be potentially useful for achieving compliance w i th t h erm al st atutes or for mit igati on of thermal impacts. For instance, temperi ng pumps at Chalk Point do not reduce nearfield temperatures significantl y; at facilities where the .iT in the nearfield is effectively reduc ed, 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. T

empering 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 shuts down. Diluti on pumping may help reduce attraction to the discharge by reducing .iTs in the nearfield and thus the potential for cold shock m ort ality. Any proposed mitigative measure, whether it directly mitigates an imp act or ind i rectly replaces a loss , has associated costs and benefits , an d obviou sly both need t o be considered in the recommendation and dec i sion

-mak ing p roces s . Hi stori call y , the ap proach to evaluating the 39Bcosts 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)

400EVALUATION OF F ISH DIVERS ION EFFICIENCIES AND SURVIVAL AT THREE POWER PLANTS WITH ANGLED SCREEN INTAKES J ohn A. M atousek 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 demonst ration 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 401INTRODUCTION The amount of water used by industry each year, especially the noncon sumptive 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 concern ed thermal discharges and their potential to alter th e 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 inge

ment on the intake traveling screens. A

t 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 ign, 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; Cann on 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 stu die s we re concerned primarily with downstream passage of juv eni l e sa lmoni ds at hydroelectric facilities, and fish exclusion at wat er diversion projects. Both louver arrays and angled screen s 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 ities. 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
403secondary 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 h e ap proach 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 b ypass. The bypass contracted to a 50.0 cm di ameter 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 u gh 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 rac ks wi th 7.6 cm openings, and enters two screenbays in the prim

ary sc ree nwell, each 5.2 m wide, with a water column depth that varies from 7.3 to 10.1 m depending upon pump operation and l ake level (F i g. 2)
.

404.j::> o <..n FIGURE 1 

### DANSKAMMER POINT ANGLED SCREEN DEMONSTRATION FACILITY

fiSH TRANSFORMER**~** PUMPS

__ \

TO EXISTING SCREENWELL eAFFLE 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'\ DR IV IN G F L OW SUP PLY PIPE FROM C.W. PUMP S FIGURE 2 

### OSWEGO STEAM STATION UNIT 6 ANGLED SC REEN 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 m

t 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. 407Brayton 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 m 3/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 m

3/s) is drawn through the screens; the remaining 3% (0.5 m 3/s) is pu mped 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 h at constricts to a 45.7 cm diameter bypass pipe. The bypass slot is s i 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.

408FIGURE 3 

### BRAYTON POINT GE NERATING STATION UNIT 4 AN GLED SCREE N 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 B rayton Point Station Unit 4 impingement abundance and survival collections were conducted simultaneously with bypass abundance and surv i val collections. The former collections were made from two built-in fiberglass collection tanks. The latter collections were m

ade from two collection nets attached to a sampling port on each 45.7 cm bypass return line. Small buc k ets, nylon nets, and dip nets were used at all three study s i tes to transfer fish to be evaluated for extended survival from the collection devices to flow-through extended survival holding contai ners. Juvenile or young-of-the-year fish were held primarily in 19 L plast i c buckets. Larger fish or large numbers of indivi dual species were held in 568 L linear polyethylene holding 410tanks 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**

411Extended 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.

412Tabl 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)

413Danskammer 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.

414Table 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

415Foll owi ng surrmari zati 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 s ition, 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 h e three-year ESEERCO-sponsored study, diversion efficiency w

as 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 416Table 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 effic i 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

417DE was determined for the six different ratios of angled screen ap proach to bypass velocity. A total of 16,567 fish collected from the diversion flow were eva luated for initial survival. With the exceptio n 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 follow i ng collection. A total of 15,235 fish we re observed for extended survival (SE); 14,857 were classified as 1ive and 378 as stunned. At the end of the observation period 9531 f i sh were classified as 1ive and 34 as stunned. Extended survival for the major species w

as var i 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 m

odified 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 sensit i 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). sun fi sh (represented by the pumpki nseed), catfi sh (represented by th e white catfish), spottail shiner, Atlantic tomcod, and hogchoker. The 1984-1985 system efficiency (SE) of 58.0% is almost twi ce th e SE value obtained from the 1981-1983 ESEERCO-sponsored s t u dy of 31.6%.

418Oswego 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 pre419Table 4
. Fish collection information, diversion efficiency, initial and extended sll rvival, and system effici ency : Oswego Steam Station Unit 6, April 1981-March 1983
In1tial survival Extended survival System D

i ver sion SI 48 h SE efficien cy Numbera Percent efficiency Number SI Number SE S E 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 T

otal 974,882 77
. 9 34 , 294 50
. 9 7,534 35.4 14 .0
aE stimated abundance based on average monthly collection rates (No./h) over the period April 198 1 - March

1983.

420sented in Table 5. Di vers i 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 A ugust an d 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) observat io ns of 28 , 186 fish collected from the diversion flow ranged from 5
. 6% for bay anchovy to 99.7% for American eel. SI w as 57.8% for all f i sh combined, increasing to 82.6% with the exclusion of bay anchovy. Extended survival observations (SE) were made on 9 20 9 fis h and resulted in an overall survival value (SE) of 63
. 4%
. Extended survival trends for the major species were simil ar 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 in e sti ck l eback , fourspine stickleback, tautog, American eel, hogcho k er , and seaboard goby. Angl ed screen system effi ci ency (SE) for all fi sh combi ned was 28.0% and increa sed 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 col421Table 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 W

i n

ter 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 T

hreespine 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 B

u

tterfish 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 O

t h

ers (45 taxa) 3,643 4.6 86.7 1,479 64.2 923 50.5 28
. 1 T

otal fish 79,206 76.3 28,186 57.8 9,209 63.4 28.0 T

otal excluding 46,643 89.7 19,091 82.6 9,065 64.4 47.7

bay anchovy

422lected from the ang led v erti cal trav eling screens (Table 6) ranged from 1.7% for the dom inant bay an chovy 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 imping ed 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 to t 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 h e sensitive group with a TSE of 23.1%. exhibited high initi al survival from both impingement (82.1%) and divers i on (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 423Table 6
. Initial and extended survi val informati on on maj or taxa and t otal fi sh and cal culated total system effi ci ency : B rayton 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 anchovyintake 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 h e location for the add ition of the third traveling screen in each screenwell offers fish quiesc ent 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 velo city 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 bypas s ve loc i ty combi n ations although there was a general trend of increa sed DE with inc reas ed 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 sec ond 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 relationship between panel mesh size and diversion efficiency was found. Evaluation of the Brayton Point collection informatio n from 9.5 and 1.0 mm mesh screens indicates that diversion is directly related to the size (age) of the fish,
425with 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 i sh. The critical factor in assessi n g the effectiveness of a mitigative intake system is the condition of the fish diverted or returned to the so urce w at er body. Init i 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 h

as 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 m eth odology, in which all netting was elimina ted and fish were not di rectly handled, would greatly decrease stress an d 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 mos t dram atic changes were observed for extremely sensitive speci es, s uc h as bay anchovy, with SE increasing from 0.1 to 15.2%, and alew ife, 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 crowd er to concentrate the fish in a collection basin and t hen di pnet t h em ou t to holdi n g containers. At Brayton Point nets susp ended i n the water were used to intercept the bypass flow. 426Table 7. Comparable in format i on on common taxa and total fish among the angled screen intake sy stems evaluated DANSKAMMER PO INT OSWEGO STEAM BRAYTo.N POINT ESEERCO C HGE 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

427Water 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 ecti 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 o

peration 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 i st of common and scientific names of fishes from the United States and Canada. Fourth Edition. Special Pub l icat 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.

431INTRODUCTION
Tidal hydropower

-- the production of e1 ectricity by harnessin g the power of ocean tides

- has become economical 1 y feasib1 e as a resul t o f socio-economic problems associate d 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 co a stal areas around the wor l d
are considered potential sit e 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 , m

ay be used. Countries that have operational tidal power p1 ants inc1 ude France, The Peop1 e l 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, 1 972 ) . T i dal h ydropower 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 198 1). 432POTENTIAL TIDAL POWER SITES 

### * OPERATIONAL UNITS

SAN JOSE GULF OE S EAOO E ST SAN JULIAN G UL F SANT A C R U Z E S T GALL EG O S ES T D (]t>

OJ**OANGE~ LJ~ ~**  R**~ ~** **KIMBERLEYS~** GULF OF CAMBAV**~** o

Figure 1. Potential tidal power d evelopment sites in the world for the gated barrage design (from Dadswell et al, 1986). Asterisk (*) denotes sites with operational Udal power plants.

433The 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 w ere
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 u nswi 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 b a sin 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 435Basin 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 Gf1 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 A m

eri 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 po wer plant in LaRance, France, which produces power on both f1 ood and ebb tides (Coti11 on, 1974). The Rance River pl ant has an ins tall 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 direc 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 1evel, local 'tP-ather patterns, and socioeconomic structure both 1ocall 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. 437Power 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 · jne (from Dadswell et al, 1986)

438Table 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.

439Physical 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
may im pact 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 440biological system wi 11 be 1 argel y control 1ed 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 w i 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 1east 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 1arge moderate >10 m minimal due to moderate (Double effect) to high <100 m reduced head di sruption Current turbines zero not hi gh >10 m secure negligible ("underwater windmill") (0.05 m) appl ;cabl e anchorageJ
. 

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444Simons 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. Aminimal 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 445circul 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 an d zoopl ankton production in both estuarine and coastal waters. Al t ere d circul ation patterns will have unpredictabl e effects on sedimenta t i on patterns, having a stabilizing effect in some areas while increa s ing or reducing shoaling problems in other. Large hasins may exhibit increased stratification of the water col umn, which may intensify exi stin g differences in sal inities, temperatures, and dissol ved oxygen. Storm s u r 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 1ess 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 1ittl e meaning at thi s time because full-scal e working model s of the proposed turbine designs have n ot been constructed. However, we can predict that the water 1ength 446(distance between each successive pass of the runner blades), impact velocity (velocity o f 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
447turbines. 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. E ffects
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 us ing
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 1ities 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 estuar ine 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. N

o 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
448cavitation and pressure fl ux would be minimal. The current turbine design would be the most env irorrnentall y coopatibl e but 1east 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.

449LITERATURE CITED
A

m

os, C.L. The sedimentation effect of tidal**po~r** deve10JJl1ent in the B ay of Fundy region. Can. Tech. Rep. Fi sh. Aquat. Sci. 1256:38 5 -4 0 2. 1984. Baker , G.C. Engineering description and physical impacts of the most probable tidal power projects under consi d eration for the upp er reaches of the Bay of Fundy. Can. Tech. Rep. Fish. Aquat. Sc i. 1256:333-346. 1984. Cai11 ez, H. General description of the tidal generating station and it s electro-mechanical equipment. Revue Francaise de L'Energie 1 83
. 1966. Char1 ier, R.H. Tidal energy. Van Nostrand Reinho1 d Co., New York, NY, USA. 3 51 p. 1 9 8 2 • Coti 11 on, J. LaRance: seven years of operating a tidal power p1 ant in France. Water Power, October, 9 pp. 1974. Daborn, G.C., G.S. Brown, and B. Scull y. Impact of a tidal power station
on zoop1 ankton-fi sh interactions in Minas Basin. Can. Tech. Rep
. Fish
. Aquat. Sci. 1256:527-5 3 4. 1984. Dadswe11, M.J., G.D. Melvin, P.J. Will iams, and G.S. Brown. Possible impact of 1 arge-sca1 e tidal power development on the upper Bay of Fundy on certain migratory fi sh stocks of the northwest Atl antic. Can. Tech. R e p. Fish. Aquat. Sci. 1256:577-600. 1984. Oadswe11,**t~ .J.,**  R.A. Ru1 i fson, and G.R. Oaborn. Potential impact of 1 argescal e tidal power developments in the upper Bay of Fundy on fi sheries
r esources of the northwest At1 antic. Fi sheries 11:26-35. 1986.
450Douma, A., and G.D. Stewart. Annapol is STRAFLO turbine will demonstrate Bay of Fundy tidal power concept. Hydro Power 1:1-8. 1981. Gordon, D.C., Jr., and M.J. Dadswell, eds. Update on the marine environnental consequences of tidal power development in the upper reaches of the Bay of Fundy. Can. Tech. Rep. Fi she Aquat. Sci. 1256. 1984. Gray, T.J., and O.K. Gashus, eds. Tidal power. Plenum Press, New York, NY, USA. 630 pp. 1972. H.A. Simons Int'l. Ltd. An ul tra-low head approach to tidal energy. Report to the National Research Council, Canada. April 1984. Larsen, P.F. Potential environmental consequences of tidal power development seaward of tidal barrages. Oceans, September 1981, pp. 908-912. Larsen, P.F., and J.A. Topinka. Fundy tidal power and coastal resources of Maine. Can. Tech. Rep. Fish. Aquat. Sci. 1256:371-380. 1984. Lawton, F.L. Tidal power in the Bay of Fundy. pp. 1-104 in T.J. Gray and O.K. Gashus, eds. Tidal power. Plenum Press, New York, NY, USA. 1972. Miller, J.M., J.P. Reed, and L.J. Pietrafesa. Patterns, mechanisms and approaches to the study of migrations of estuarine-dependent fish 1 arvae and juvenil es. pp. 209-226 in J.D. McCl eave, G.P. Arnol d, J.J. Dodson. and W.H. Neill. eds•• Meehani sms of migration in fi shes. NATO Conference Series. IV. Marine Sciences, Vol. 14. 1984.

451**1i1l** ichamp. R.I.. and E.M. Staite. Fi sheries considerations. pp. 1 75

- 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. 1 980.**lonten.** E. Fish and turbines: fish injuries during passage through**po~r** station turbines. Vattenfall. Norstedts Tryckeri, Stockholm, Sw eden. 111 pp . 1985. Palmer, A.. and G.E. Beanl ands. T he 1 and-based ne arshore 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, C anada
. 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. 1256:463-4 6 8
. 1984. Pr ouse, N.J., D.C. Gordon, Jr., B.T. H argrave , 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. R ep. 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.

452Rulifson, 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 1d, 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 citY supply. pp. 307 - 321 in G ray and Gas hus, 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.

453Wylie, F.E. Tides and the pull of the moon. The Brattleboro Press, Brattl ebara, VT, USA. 246 pp. 1979.

454MITIGATION 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. 455INTRODUCTION Mit i gation of fish and w i 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 w i ldlife and compensating for unavoidable losses of those resources . Historically, mit i 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 456banking." 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 ti l e 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.

457MI T IGATION BANKI N G CONCEPT Mitigatio n banking is defin ed i n t he Se rv ice ' s mi ti gation policy as "habitat protection or i m pr ovem ent 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 explanatio n of m i tigation bank i ng :
" Io n s imp 1 i fie d t e r m s, mi t i g ation ban kin9 iss i m il art0 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 for 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 c an 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.

T

his definition recognizes both the modification of project design to
avo i d or lessen impacts and compensation for impacts that are unavoidable
. Avoiding the impact altogether is the preferred
m

i t i gation method, followed by min i mizing the impact
. These may be
acc om plished 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 s i der ed onl y after all feasible means of avoiding or reducing imp acts h ave been exhausted. Compensation can involve a variety of habi 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 on ly w h

en compe nsation i s warranted.
459An 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.

460TENNECO 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 r apid 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
w

i 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

461conversion 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 w a 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 1i fe of the marsh even after the all owabl e credits and been debited. An interagency team measured the

462anticipated benefits of the proposal using HEP. The lengthy and i ntens i ve negotiations that ensued culminated in an interagency Mem or 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 provis i 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 L

ouisiana 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 part i es to th i s Agreement shall use HEP, or a Inutually agreeable and credible methodology , to determine credits and debits to be app 1i ed to the miti gati on bank.

1 A verage Annual Habitat Units, a measure of habitat value
calcul ated i n HEP.

4633. rv1itigation by debiting available AAHU's from the mitigation bank is appropriate and will be used to offset only unavo i dable impacts
on fish or wildlife when the appl ican t c an 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 c onsideration co s t, existing tecnnology, and logistics in light of overall project purposes.
4
. Credits generated within Hydrologic Unit 5 shall be applied to activities requiring m i 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.

4646. 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 es t ion, the mitigation bank ac count will be debited for the first t ime. 465NORTH CAROLINA DEPARTMENT OF TRANSPORTATION MITIGATION BANK**T~e** North Carolina Department of Transportation entered into discussions with the Fish and Wildli fe 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 C arol 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 m i 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 466cli max gum-cypress forest. The North Carolina Wildlife**~esources** Co m mission 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 i s frequently flooded and i s used by
an ad romous 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 de s i 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 rement s , but only for projects larger than !:i acres. Mitigation for sma ller project s will be on an acre-for-acre basis. Another
not ab l e difference between this bank and the Tenneco bank is tl1at the N

or t h C ar 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 oss es of bot t omla n d ha rdwood wetlands in North Carol ina ; consequently t he MO U co nt ai n s a de ta i led de finitio r l of bottomland hardwood
wetland s . 467An i nteragency team has been working on a HEP analysis over the past severa l months to dete rmine baselin e val ues for t he mitigation bank
area . Field sa m pling was comp l et e d in A ugust 1986. A report indi c ating t he nu m ber of m iti gat i on cr ed it s dvail ab l e in tne bank account w i ll be subm i tt e d 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 e d 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 analys i s are awaiti ng action
.

468MANAGEMENT CONSIDERATIONS Miti gation banking provides a mechanism by which unavoidable fish and wildl i fe habitat losses associated with certain water resources projects 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 s tablished for other habitat types. In general, a mitigat i on bank s hould be con s idered only when h ab 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 i stration 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 c omes closer to maintdining i listorical patterns of
w

il dl ife abundan c e and distribution. Unfortunately, providing follow-up and l nanagement 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.
469The 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 1ife of the

470bank
. Specific guidance on these considerations has been presented by several authors (Soileau et**~.** 1985; Zagata 1985; Dunham 19 86; Niedzialkowski and Jaksch 1986; Riddle and Denninger 1986); however,
s pecific provisions may vary considerably from one mitigation bank agre ement to another
. Mitigation banking can provide benefits to both developers and fi sh and wi Idlife resources . For the form e r it saves time and money by incorporating mitigation into the early plann in g process, althouth the time required for a HEP analysis sOlllet i m es 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 w i 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 m i 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
. M itigation banking also can include follow-up and
mo ni tor i ng requirements to ensure that mitigation measures are success fully implemented
.
Sub stan t i a 1 r i s k s are ass 0 ci a t e d with OJ iti gat ion ban kin g . A rna j 0 r ri sk i s the pote ntial neglect of good project plann i ng . For example,
we tland re gul at o ry agen c ie s t ha t are c harged w i th protecting the 471public'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
.

472CONCLUSION
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 fur certain types ot projects and impacts
. However, if administered properly, the approach can provide an effective means of meeting mitigation needs.

473LITERATURE 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 options for port development in Tampa Bay, Flori da. Coasta1 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 regulat i 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).

475SUCCESSFUL LICENSING OF A MAJOR POWER COMPLEX IN THE SOUTHEASTERN UNITED STATES ENCOMPASSING MULTIPLE REGULATORY AGENCIES GOALS Charle s J. Z i mmerman , Jr . Ly 1 eA. Lyd i ck 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 step s 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

476storage 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 ectric & 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.

477The objectives of the agencies are : -Mitigate habitat lo ss. As protectors of the environment, the agencies' charge was to ensure th at 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 pti 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

478being shut down occasionally for maintenance and repairs. To complete the planned power complex the existing dam at. the Parr Generatin g 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 determin e d 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; w i th t he increased usable storage in the lower reservoir this station can generate for 8 hours. There are eight reversible pump-turbine un it s, 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;

47911&. , Il 

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### Figure 1the 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 reservoi r was bu i 1 t to prov ide 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.

481Program 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 meet 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 nimi ze these effects. Minimization of the construction impacts included erosion and dust reduction measures and borrowing fill

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- 3 4,dirt from within th e reservoi r area. In addition to these measures a land management prog ram was instituted to spe ed 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 pro gram 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.

486At Parr Reservoir sever al enh an cement fe at u r es impro ved the are a for public use. These included:

o Addition of several boat launching ramps a nd campin g facilities.

o Initiation of a waterfowl management plan. The water fowl management plan included th e devel opment of a dike-controlled marsh area with adjacent f i elds. B oth t he marshe s and the fields were planted with preferred wildlife foods a nd cov er v egeta
tion suitable for nesting. Wood duck n est ing boxes w er e ins talled in suitab l e backwater locat i on s . The w at er fowl managemen t plan al so i ncluded the development of a g r een-tree reservo i r near Parr R es ervoir
. The water level of this g r een-tree reser voir could b e ra ised or lowered i n o rde r to enhance grow th and avai lability of waterfo w l foods
. A

dditional mitigat io n was p r ovided by the init i at ion of a C anada Goose nesting and stocking program d e si gned t o establi sh a native Canada goose population in the Piedm ont of South Carol ina
. This effort included transplanting geese fr o m outside the st at e , est abli shment of food plots and nesting habitat developme nt on the islands in Mo nt icello Reservo i r. To date, all of the mitigati on programs a r e cons idered to be highly successful. T

o ensure cont inued spawni ng success of the fi shes of the B road R

iver downstream of the project area, the Parr hydroelectric fac il ity ma intained certain minimum downstreilln flow requ i rement s.

487**-~- ~**  

### ---

SUMMARY South Carolina Electric & Gas Company planned, constructed, and 1 i censed a maj or power gener at i ng complex. Inc 1uded 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 ive 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.

488This project was well planned and designed. The objectives of th e 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 t o 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.

489IMPACT 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 paper s 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 starti 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 neces saril 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 plant s. 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. 490Likewise, a marine biologist who specializes in plankton communitie s may consider a thermal plume as having an adverse impact on the near shore plankton community. But that same thermal plume may serve to at t 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 natural ecosystem and that an adverse impact occurs when that natural ecosystem is disrupted. My response is that I do not believe that there are m any remaining examples of natural ecosystems that man has not altered or impacted. There may be some examples in the most wild of the w il 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 conditions that make that parti 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 i on, 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
491terms 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 1ity of the bay anchovy. The question is what is the re 1ati 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 bio l 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
492to agenc ies or private developers to mitigate tho se impacts the Service feels are adverse. I have some slides wh i ch i l lustr ate what I am talki ng about
. A formal mitigatio n p olicy was developed i n 1981 w hich i ncorporated all the princ ipl es and concepts th at 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 m ore of the mitigation princi ple s th at are embodied in the F i sh and W il dli fe Service policy. I will review the definition of mitigation, as outl·ned b y O r. Jim Brown and his paper on mitigat ion banking. The President ' s C ounc il on Environmen tal 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 i tem s are not a menu of equivalent options fo r mitigation. Recognizing the definition as a sequence of mitig atio n st ep s th at begin during the initial pl anning stage of the project wi ll help speed the approval of th e project and reduce the need for expen s ive m odificat ions l ater on i n he regulatory process . Ross Wilcox 's paper outlined principles th at address all of the definitions of m itigation . I will address Ros s' effort s later becaus e they are very creative; they are in novative and diffe ren t from application of the term mit i gation. Linda Cadman's paper on th e 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 elimin ated over t ime. Robert 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 bio logists and project managers, we need to think about so that we can understand and develop ways to avoi d an impact for th e mutual benefit of both the company and the agencies. Or. Jim Brown's presentation focused on ways to compensate for unavo idab l e los ses. Charl es Zi mmerman ' s paper addre ssed all the principles in a formal sense of a major plann ing project for a power gen eration complex that was extremely successful
.

The Fish and Wildlife Serv ic e mitigation process covers all feder al projects and private project s th at require a federal permit or license. The Fish and W il dli fe Service reviews and recommends actions; t he agency 493or 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
494Table 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

495about 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 m iti gat i on goal. In resource category 1, because that habitat are a i s i rrep1acab1e, 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
496endangered 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 cos t 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 outfa 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
497selected 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 ion 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.

498Enhancement actions by a power company have three primary bene fi ts
. The first is improved public relations. Projects such as t h os e undertaken by Florida Power and Light Company**~ave** created trem endous positive feelings on the part of the public and the Fish and Wild life Service toward this company. Charles Zimmerman's power complex ex ample 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 h e company economically through the m iti gation banking concept. The third major benefit to the company is the altruistic one from the stan dpo int of making things better than they were before. I have been told th at t h ere 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 ag e . 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 represen t s 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 ion of the aquatic or terrestrial ecosystem and subsequent loss of important fish and wildlife sp ecies 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

499the manatee. Docks do n ot ki 11 m anatees, b u

t the boats that use the docks do. Not all the boat s , certa in ly. The second horizontal line represents a project that had good environmental planning b ut n o compensation of resources lost. Note that the area of impact has been min imized. The third horizontal line represents a project w ith 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 1ine 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 actions h ave also been des igned 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 cleve1 it may have been more cost effecti 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.
5001. 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 pro fessional judgm ent and with public input. 3. An adverse env i ronmenta 1 impact on 1 y occurs when there i s a difference between the des ired cond ition and the actual cond iti 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 thro ugh good environmental planning at the ear liest p oint in the project pl anni n g 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 igation 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 r i ght, 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
501cool ing lake woul d have resulted i n a regulated flow that would have inundated Steel Creek
. S t eel Creek wa s used as a foraging area for the endangered w ood stork and the Bird sv i lle Colony, which i s located approximatel y 30 mil es from the p l ant site, contains our most northernmost popu l at i on of t he wood stork, w ith over 100 birds
. We determi ned that Steel Creek is a foragi ng habitat for that parti 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 em ot i onally and pol i tically and, as you can imagine with anything that relates to nuclear energy or weapons development, everyone was offering opin i ons . A typical example was a Scrawls cartoon in the Atlanta Journal Constitution showing three witches stirring a pot. The pot was labeled "the L reacto r cool i ng lake" and the caption was "bubble, bubble, toil and trouble. 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 p roject 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 tac t i 1e feeders w ith thei r bi 11 s, wood storks requi re specific water levels an d 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 i ons . I hope these review com ments and my speaker's papers will help to stimulate such a win-win scenario in power generation planning.

502SOME 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 1He or exceedances of water quality standards in recei ving waters
. This paper discusses several aspects of trace element discharg es 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 b o

dy , potential for bioaccumulation or biomag nification, interactions w i t h chemical factors, temperature , presence of other toxics, and accumu lat i on in sediments
. P

r actica 1 examples of t h e effects of these and other factors wh ich 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
.

503INTRODUCTION The purpose of th i s paper i s to share experi ences with a trace element discharge problem. A lthough 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 eleme nt 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 504heightened 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, no t 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 1imited 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 ignifi 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 ity 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 product i vity, chemical properties of coal and fly ash, and the quantity of discharge (Cumbie, 1978, 1980)
. Still, other systems may share a 505sufficient number of t h es e propert ies th at the problems experienced in Be 1 ews Lake can offe r use ful gu idanc e t o i nterpretati on of effects of other trace element discharg es. C

O

N

TINUOUS D ISCHARGES V E

R

SUS SPILLS The Belews Lake as h basin effl uent wa s a continuous discharge which occurred as a recog nized operating feat ure of t he power plant (Cumbie, 1978; Cumbie et 

### ll , 1985). Although t he introduction of selenium to Belews Lake did n ot cau se im mediate responses in the form of a fish kill or violations of numerical w at er qual ity standards, the continued discharge eventually resulted i n a suffic i ent 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 R es ervoi r case issimil ar in the sense that introduction of selenium to th e reservoir and associated evaporation ponds from agricultural drainage h as 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 l y proved to be short-lived. In these cases, acutely toxic conditions are dev el oped , but are rapidly abated by the combined effects of chemic al decay, precipitation, or dilution of the respons i b 1 e agent. Methods fo r eva 1 uat i ng cont inuous di scharge effects must obviously be diffe ren t fro m th ose which are used for spills. The latter often attrac t imm ediate 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 506arsenic 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 507to problems with fish p opulations
. This caused attention to shift temporarily to other pos s ible 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 extremely 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 u re 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 508temperature, 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 sp ec i es presence (Weiss and Anderson, 1978)
. The only unusual feature s n oted were a tendency for benthos to attain rather large body sizes an d t o be plentiful in appropriate habitats
. This was apparentl y 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 w hi 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 , zoop lan to n data revealed no unusual changes in species or population l evels in Belews Lake. Studies of zooplankton , p eri phyton , phytoplan kton, an d benthos undertaken to evaluate effects of temperature el evat i on j udg es conditions in the Belews Lake ecosystem to be normal for the region i n 1976 , at the very time when fish populations were declining (W ei ss an d Anderson, 1978). These resu l ts were in contrast to the com monly advan ced 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 B

elews 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 m

et als or other substances in the laboratory (Peltier and Weber, 1985). It ap p

ears 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 ind icate 509that selenium levels increased with increasing depth and distance from shore (C umbie, 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) fro m Belews Lake w ere significantly more resistant to toxic effects of sodium selenite than hatchery green sunfish which had not been previous ly 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 i sh 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 m 3

/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
510in 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 511bioaccumu1ation 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 whic h began in 1976 (Cumbie and Van Horn, 1978). IMPORTANCE OF SIMPLE PHYSICAL CHARACTERISTICS Properties 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 m 3

/sec results in a complete circulation of the lake volume of 228 x 103m 3 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 512areas, 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 u m 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, 198 1 ; 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 i den ce 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 v ert 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 sedimen t s (Cum bi e, 1978, 1980, 1984), Selenite is more toxic to aquatic 513life than selena t e (U.S. EPA, 1980). B eh avi or of selenium in the San Luis Dra in and K esterson Reservoir systems m ay differ from that observed in Belews Lake if m o

re al k aline conditi on s fa v or maintenance of selenium in the form of selenat e (see Saiki, 1985). O ur present understanding of redox transitions and kinetics of m any chemical reactions of interest in trace element toxicity i s r udimen tary. This is a fruitful area for future research. CON CLUSIONS Trace element disch arges present environmental scientist or engi n eer significant faced w ith challenges to the interpretation of responses of aquatic system s to such discharges
. This discussion of experiences with selenium i n Belew s Lake has sought to illustrate a variety of factors w hich shou l d be considered in order to determine whether a discharge i s ha ving significant effects in a particular ecosystem. Since differen t ecosy stems respond differently to pollutant di scharges, dependi ng on t h ei r i n di vi dual propert i es, a di scharge with significant adverse effects in one locat ion may have no discernible effect in another 1 ocation
. Furth er research on ecosystem responses to trace element loading i s needed to enhance our ability to distinguish these possibilities
. R E

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. 96pp.

516RADIOCESIUM KINETICS 

### IN THE YELLOW-BELLIED TURTLE (Pseudemys scripta) Eric L. Peters I. Lehr Brisbin, Jr. Savannah River Ecology L aboratory Aiken, South Carol i na ABSTRACT The recent Chernobyl accident has demonstrated the potent ial fo r radionuclide contamination of aquatic ecosystems. Although the in it i al release into the environment may be local i zed, animal s inhabiting such contaminated areas may eventually serve as vectors of radionuc l id e spre ad into uncontaminated regions. In long

- lived animals, such as the yell o w

- bellied turtle (Pseudemys scripta), the animals themselves may also serve as a reservoir of such contaminants, accumulating body b u

rdens 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 elimi 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 p

eriod was attributed to a presumed delay in the onset of a regular feeding rate, while the turtles became accustomed to locating food in an u

n

familiar area. This is in contrast to the Davis-Foster model, which as sumes 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.

517POLLUTANT 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.

518INTRODUCTION 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 wat er discharge site. Once-through cooling systems are cost effect i v e as compared to other options. Corrosion and biofouling are common problems when sea water i s used fo r cooling purposes. To reduce th ese problems to manage ab le 1

eve 1 s , certain chemi ca 1 s are used Chromi urn i n the form of chromate i s used as corrosion inhibitor. Chlori ne i s 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 from 1eachi 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 sediment s of the discharge side , relat ive to t h e 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 S

tudy Site Bahia de Guayanilla i s an embayment enclosed by coral reefs and lin ed by mangroves, which was the site of a large petrochemical industry co m

plex locat ed on the Caribbean Sea shore on the south coast of Puerto R

i 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 mar i ne environm ent are summarized by Lopez (1979a)
.
519Fi gure 1
. Study si t e showing s ampling s tati on plan
. Stations A,B,C, D are located i n Inta k e area . Station s H, I ,J , K are locate d in R eceiving area (Thermal C ove).

u •.**~-** 

# '" 0 :::> PUERTO R ICO**~ ~**  

# • ..J Z 18.0-

81- 88- W LONGITUDE 

# j °0**~**Power Planl N

## ~ 

# / \ Conol 

### • \

520Among 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 i s 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 w i thi n the intake area and in 4 stations in the Thermal Cove (Figure 1). T he 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 60 0 C 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)
. T

h

e 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 m

ethod 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 h e four stations within the intake area.

521TABLE 1. Pollutants concentrations in the surface sed i ments of Bahia de Guayan i lla

. 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)

522A 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 issign i fi cant 1 y higher than the average con centration 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 stri but i on of these poll utants in the sed iments 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 ron ments
. Bi oaccumul ations of trace metals in the mangrove oyster
523Table 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 sed i ments (%) 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 i n 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) Stat ions Compared

All in Intake vs. H in Thermal Cove Average Intake 

### = 59.74 Station H 

### = 90

.98 Standard dev iation = 5

.06 N = 1 N=4 t(3) = 6.90 p<.05

524Figu re 2

. Pollutan ts concentrati ons i n the surface sediments of Bah fa de Guayan i lla

. Stat ions A to D were located in the intake. sta tions H to K were located in the The rma l 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 5 0 4 0 Ni**~g/g** 30 20 10

0 A B C 0 H J K 100 90 .9 8

80 60 Zn**~g/g** 40 20

0 A B C 0 H J K 140 12 2
. 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
. 1 5 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 r ated by Almod6var-Ferrer (1986). Schroeder and Thorhaug (1 978) and Thorhaug and Schroeder (1978) demonstrated the accumulat ion of h eavy 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 w ebs i n the C aribbean and Gulf Coast region
. Biological magnification vi a these food w ebs 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 environment s . M. S
. Thesi s . Un i versity of Puerto Rico, Mayaguez PR o 1986. Banus, M. D. Copp er , i ron, and man ganese content of mangrove seedl ings from Puert o R i 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 n gfield, VA 22161). Farrington, J.W. and B.W
. Tripp. A comparison of methods of analysis for hydrocarbons i n surface sedi m ents. Amer. Chern. Soc. Symposium Series, Phi lad el phia, PA. 1975
. Goldman , G.C. Energy Energy 1979. Water ci rculation i n Guayani11a Bay. In: Symposium on and t h e Marine 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 Marine 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 zation. Ed. by S.S. Lee. Mechanical Engineering Department University of Miami. Coral Gables, FL. December 1978.

526Sokal, R.R. and F.J. Rohlf. Biometry. 859 pp. San Francisco: W.H. Freeman and Co. 1981
. T

h

orhaug, 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.

527EFFLUENT TOXICITY TESTING FOR INDUSTRIAL DISCHARGERS Mark Shearon Harmon Engineering Associates, Inc. Auburn, Alabama ABSTRACT The United States Environmen tal P rot 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 estimat ing 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.

528TOXICITY 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 1ike 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 cu rrently faced with the immense problem of toxic materials in our en vironment ; the problem will only grow in the future. In addition to the historical chemical by chemical approach, the biological approach for t h e contro l 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 cation 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.

529I use the term cos t -effective because , as a biologist, I was probably my own wor st enemy at planning elaborate studies. Early in my career, I was involved in m an y bi ol ogical field monitor i n g studies. These studies were usually long -term , resource intense , and costly. At times the information was not prov i ded in a timely manner so a to make a quality decisio n. 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 hour s 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 simil 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
530method 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 cou ld 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 south east 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 N PDES 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 1sin 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
531Rico, 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 w as discharged from the fly-ash settling ponds at ppb concentrat i ons. 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
532treatment necessary to reduce or eliminate the toxicity
. The TRE is divided into three phases: Phase I - Toxicity characterization; P hase I I

- Causative toxi cant ident ifi cation; and Phase II I - Causat i ve tox icant 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_ A cute toxicity test are employed throughout all three phases
. Minimal analytical work is required in Phase I, as the majori t y of t h e identification is conducted with toxicity tests
. Phase s II and III may require extensive analytical support
. As indicated from the papers presented in this secti on, t h e area of toxics and bioaccumulation is go i ng to be in the forefro n t of p ol lution abatement for years to come.

533SOUT H

E

A

S

T

E

RN WORKS H

OP ON AQUATIC E COLOG IC AL E F

FECTS O F P OWER GENERATION D

ecemb er 3-5 , 1986 Mote Marine Lab oratory Sarasota, Flor ida 33577 POSTER SESS IO N A BSTRACTS (Arranged Al p habetically) 1 . Bruzek, D. A. and S. Mahadevan. Mote Mar i ne Laboratory, Sarasota, Florida. THE APPLICATION OF LOG- N O

RMAL DISTRIBUTIONS IN DETECTING POLLUTIONINDUCED CHANGES IN A BENTHIC C OMMUNITY. Benthic infaunal samp l es w ere collected from 40 stations over a peri od of 15 mon t hs in t he vi ci ni t y of the Crystal Ri ver Power Station. Th e indiv idu al s of each species were identified and enumerated, an d the log

- normal distribution of individuals per species was determ i ned
. C urve s were drawn for each station and samp 1 i ng peri od and m ean 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 chan ges as well as naturally disturbed areas in the communities
. It was found that stations in the area of the thermal effluent and natu r al l y disturbed areas had lower log-normal angles (30-35 0 ), w hereas the offs h ore and nearshore undisturbed stations had higher log

- normal angl es (above 40 0 )
. Since a shallower slope refl ects a community under environmental stress, these data sugges t that t he al t eration of basic log-normal distribution of ben th i c communities can be used to discern disturbances. 2
. Frere, P. Potomac Electric Company, Washington, DC. CONTROL OF MACROFOULING O N INTAKE STRUCTURES AND MODIFICATIONS TO CHLORINATION PROCEDURES AT AN E STUARINE POWER PLANT. Potomac Electric Pow er C o

mpa ny' s Chalk Point Station is located on an estuarine seg m ent of the Patux ent 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. Over t he years, the station 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 con cret e surfaces during the summer months. These mat s 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 n g secondary fouling organisms was initiated i n 1985
. Con crete plates similar in surface characteristics to the i n take structu re were suspended in front of the station intake screens and a11 ow ed to foul. The plates were 534inspected at intervals through the period July 1985 to October 1986. T

he 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 i de
. 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 re corded
. 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 an d ch 1ori ne dosage. Inspect ions of intake condenser w

ate r bo xes w ere 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. Clear- cutting of timber and removal of man -made structures are co mmon practices in the construction of impoundments and reservoirs used for cooling facilit i es . These activities may result in limited habitat for cover-orien t ed fishes, e . g . , centrarchids and i ctal uri ds , and reduce t h e probability of developing productive f i she 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 i shermen 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. Stru ctures consisting of cedar trees anchored over cinder block su bs t rates were generally unproductive, due to accretions of silt that compacted boughs, in compari son to structures cons i sti ng of hardwoo d tree tops anchored over ci nder block substrates. Struc t u res placed in ar eas subject to currents resulting from pum ping 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 1abi 1 i ty and cost of construction materi a 1s, temperature and oxygen requirements of target species and hydrologiC characteristics of the wate rs . 5354. 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

- h eld 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 efficie n t means of locating and trackin g 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 accurate tracking data as a result of being able to move wi th located fi sh. The mounted hydrophone b race has b een used at Lake Anna sin ce 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. D owning, T.A. Biffar. Stone 

### &Webster Engineering Corporation, B oston , Massachusetts. ENTRAINMENT AS A RISK ASSESSMENT PROBLEM. Entrainment of organisms with intake water has received much attenti on, and the pro jected impacts hav e resulted in the expenditure of considerabl e economic resources in an attempt to reduce entrai nment. Related de cisions have necessarily been made in light of large uncertainties with respect to the ecological effects of entrainment an d the effectiv eness of technologies to mitigate entrainment. One method for investigating these decisions is risk assessment , which has received w ide application in fields as diverse as engineering economics and env ironmental health analysis. In risk analysis the risk is determined by both t he ex posure 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 resp ect to r i sk reduction. The prob1 em is formulated bo t h from 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
. an d J.B. Suomala. Ame r ican Electric Power Service Corporation, Columbu s, Ohio
. UNDERWATER ACOUSTIC RADIATION, WATER VELOCITY AND WARMWATER FISH DISTRIBUTION AT RACINE HYDROELECTRIC P ROJECT, USA. Underwater acous tic radiati on , water velocity and hydroacoustic (SONAR) fish monitor ing was conducted in August 1986 at Ohio Power Company's 48,000 kW Racine Hydroelectric Project at Ohio River m il ," 237.5 near Racin e, 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 Ih i " project. Acoustic radiation and water vel ocity measurements at**)[)** 536locations 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 high est 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 record ed
. High acoustic intensity, discrete narrow band frequency 1ines at 120, 240, 360 and 720 Hz were also recorded. Fish were observ ed at all water velocities, including those as high as 6 fps in t he tailrace. Fish were unevenly di strib ute d among monitoring locations. Few fish were observed in the draft tube an d imm ediately upstream of the intake tra shracks compared to most other lo cations. 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 hydroele ctric 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 m i le sect i on of Back Creek located b elow 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 w as comp leted in 1985. Biological monitoring of the area is being conducted by representatives of VPI for t wo years follo w ing 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 1ocat ions around the project si te for planting of vegetat i on as a food sourc e for wild turkeys. These clearings have been very succe ssful in attractin g tu r keys. They are "ma in tain ed" periodically to en sure their effec t iveness. 5378. Marion, W.R. Univer sity of F l orid a . J
. R. Wilcox. Florida Power & Li ght Co. BALD EAGLE PRODUCTIVITY NEAR FLORIDA POWER 

### & LIGHT COMPANY FACILITIES. The majority of Southern Bal d Eag l e nes t ing occurs in Florida, with 220-250 succeisful nes ts each year. F l o r ida Power 

### & Light Company conducted along

- te rm mo nito r i n g prog r a m at selected Southern Bald Eagle nests in central Florida in an attempt to anticipate and minimize potential dis t urbances dur ing the nesting season. Productivity at four su ch nesting l ocations is compared with statewide prod u ctivi ty average s fo r 1974 -19 78
. 9. Mazzotti, F.J. U ni ver s ity of Pennsylvania
. J.R. Wilcox. Florida Power 

### &Light Company. CROCODILE MONITORING AT FLORIDA POWER 

### & LIGHT COMPANY TURKEY POINT PLANT. Flori da Power & Li ght Com pany's crocod il e mon itori ng program has documented the compat i bi 1ity 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 u veniles , and the abundance and distribution of adults. Two nests hat 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 s i te
. 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 i ght, length , w eight, and volumetric displacement of oysters were measured before and after deployment in control and thermal areas. Mortality rat es we re noted , and a Condition Index (CI) was determined for each 1i ve oyster returned
. Growth in control areas was not signifi cantly di fferent than growth in areas of maximum thermal influence
. G rowth wa s enhanced, h owever , in areas of moderate therm al in fluenc e . C I corre late d 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 ident ified an d en u

m

erated . A b

undances and diversity of oyster associated faun a decreased in therm al l y affected areas, along with a change i n commu nity co mp os i tion from a mollusc-dominant comm unity, to a more polychaet e- do mi nan t commu nity. This alteration was not wi desp read , however, and was ess ent i a11 y 1 imited to areas undergoing immediate thermal influence.

53 8

### SOUTHEASTERN WORKSHOP ON AQUATIC ECOLOGICAL EFFECTS OF POWER GENERATION LIST OF PARTICIPANTS Rafael Almodovar-Ferrer University of Puerto R ico Center for Energy and Environment Research Co 11 ege Station 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 i ronmental 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 P

ost Office Box 10429 Sou th port, North Carolina 28461 (9 19) 457-3397 Dr. Thomas Biffar Stone 

### &Webster Engineering Corporation 2

45 S ummer Street Post Office Box 2325 Bo ston , Massachusetts 02107 (617) 589-2725 539

### lIST OF P ART ICIPANTS continued. James D
. Brown U

. S
. F i sh and Wildlife Servi ce 75 Spri ng Street S outhwest Suite 1276 Atlanta , Georgi a 30303 (404) 33 1- 6343 Vilma S
. B rueggemeyer Tampa El ectric Company Post Office Box III Tampa , Flor ida 33601 (813) 228-4841 David A
. Bruzek Mote M arine Laboratory 1600 C ity Island Park Sarasota , Fl orida 33577 (813) 388

-4 441 John P
. B uchanan Tennes see Valley Authority Fis h 

### &A quatic Ecology Branc h 145 Summer Place Buil ding Knoxvi ll e , Tenness ee 37902 (615 ) 632 -3701 Linda R
. Cadman Marti n Marietta Environmental Systems 9200 R umsey R oad Columbia, Maryland 21 04 5 (301) 964 -9 200 Jo hn Christian U.S. F ish 

### &Wildlife 75 Spring S treet S outhwest Atlan ta , Georg i a 30303 (404) 331

-35 80 Dr
. Sheree L. Cohn St. Cloud State U niversity Department of Biol og i cal Sc ien ces St. Cl ou d, M i nnesota 56301 (612 ) 255

-49 12/253

- 8634 Peter M . C u

m

bie Duke Power Company Design E ngineeri ng Department Post O ffi ce Box 33189 Charlot te , N orth Carolina 28242 (704) 37 3- 83 31 540LIST OF PARTICIPANTS continued. Robert M. Daniels Virginia Power North Anna E nvironmental Laboratory Post Office Box 402 M

i neral , Virginia 23117 (703) 894-5151 D

r . William Davies Department of Fisheries Allied Aquacultures A

u

burn Univers i ty, 203 Swingle Hal l A

u

burn , Alabama 36849 (205 ) 826-4786 Robert W. Davis Lawler Matusky and Skelly Po st Office Box 1509 One Blue Hill Plaza P

earl River, New York 10965 (914) 735-8300 Kathleen D u

rrell Tamp a Electric Company Post Office Box III Tampa, Florida 33601 (8l3) 228- 4842 Bruce W. Easley Virginia Power Surry Power Station P

ost 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) 85 5

- 1295 Jay Gorzelany Mote Marine Laboratory 1600 City Island Park Sarasota, Florida 33577 (8l3) 388

-4441 541LIST 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 542LIST 

### OF PARTICIPANTS continued. Roy R
. Lewi s, II I Mangrove Systems, Inc. Post Office Box 290197 7729 Profe ssi onal P l 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 in ski Florida Power C o

rporation Post Office Box 14042 St
. Petersburg, Florida 33733 (813) 866-448 1 Dr. Kumar Mahadevan Mote Marine Laboratory 1600 City Islan d Park Sar asota, Florida 33577 (813) 388-4441 B.M. Marsh all Virg inia Power Post Office Box 26666 Richmond, Virginia 23261 (804) 775 -5199 R. Erik Mart i n Applied Biology, Inc. Post O ffice Box 974 Jensen Beach, Flori da 33457 (3 05) 334-3729 F

rank Massie Virginia Power 2043 Jackson S hop Road Goochland , Virginia 23063 (804) 257 -4779 Jack Matt ice Electric Power Research Institute 3412 Hillview Avenue Palo Alto, California 94304 (415) 855-2763 543LIST 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 544LIST 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 M

ike 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

545LIST 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