Inc., 1976c Sampling: Dates: May 29th  November 18th Collection frequency: varied from 4 times per week to once every 2 weeks. Times of peak abundance: greater frequency of collection Time: varied but generally occurred between dusk and dawn Number of replicates: varied between 3and 14 for each date Intake and discharge sampling: paired but timing not standardized Elapsed collection time: not noted Method: pump/ larval table Depth: mid depth at both the intake and discharge Intake location: in front of the trash rack Discharge location: from the seal well before the end of the discharge pipe Water quality parameters measured: none mentioned DOC and POC measured: no Intake and discharge velocity: not given Operating Conditions During Sampling: Number of units in operation: varied between 1 and 2 Number of pumps in operation: varied between 2 and 3 Temperature:   T ranged from 3 to 13

C, intake and discharge T not given Biocide use: not noted Survival Estimation: Number of sampling events: 41 Number of samples: 672 Number of organisms collected: 3,667 Number of organisms entrained per year: not discussed Fragmented organisms collected: not discussed Equal number collected from intake and discharge: differed by as much as 3.2X Most abundant species: striped bass, white perch, alewife and blueback herring Stunned larvae: included in initial survival proportion Dead and opaque organisms: not mentioned Latent survival: observed in aerated glass jars for 96 hours. Data: summarized and averaged over the entire sampling period Controls: survival in intake sample; no other control Initial intake survival range: 57 to 80% for striped bass 0 to 71% for white perch 58 to 65% for herrings Initial discharge survival range: 62% for striped bass 29% for white perch 26% for herrings Calculation of entrainment survival: Discharge Survival/ Intake Survival Study noted that survival cannot be calculated with insufficient data or when intake survival is very low Confidence intervals/ standard deviations: not presented Significant differences: tested between the intake and discharge survival Significantly lower survival in discharge: striped bass YSL and PYSL white perch PYSL herring PYSL and juveniles Survival calculated for species with fewer than 100 organisms collected: yes Egg survival: none alive in either the intake or discharge samples Larval survival: decreased markedly within 3 hours of collection Size effects: survival by larval length was not studied Raw data: were not provided to verify results Temperature effects: not provided Mechanical effects: not provided Quality control: double check after initial sorting; monitoring of data entry Peer review: not mentioned; study was conducted for the facility § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival A7 42 March 11, 2003 Roseton Generating Station Hudson River, NY 1976 Study Ecological Analysts Inc., 1978d Sampling: Dates: June 14th  July 30th Samples collection frequency: 4 nights per week Times of peak abundance: coincided with Morone spp. spawning season Time: 1700 to 0300 EST Number of replicates: actual numbers not give, an average of 12 per night stated Intake and discharge sampling: pairing unknown Elapsed collection time: 15 minutes Method: pump/ larval table combination Depth: mid depth for both intake and discharge Intake location: 1 m in front of trash rack Discharge location: in seal well near end of discharge pipe Water quality parameters measured: no DOC and POC measured: no Intake and discharge velocity: unknown Operating Conditions During Sampling: Number of units in operation: varied between 0 and 2 Number of pumps in operation: not given Temperature: Intake temperature range: 18.7  27.5

C Discharge temperature ranged 24  37

C   T ranged from 1 10

C Biocide use: not noted Survival Estimation: Number of sampling events: 27 Total number of samples collected: unknown Total number of organisms collected: 3,491 Number of organisms entrained per year: not given Fragmented organisms: not discussed Equal number of organisms collected at intake / discharge: no, up to 5.7X more Most abundant species: herrings, white perch and striped bass Stunned larvae: were included in initial survival proportion Dead and opaque organisms: not mentioned Latent survival: observed in aerated glass jars for 96 hours Data: combined by discharge temperature range: 34  30.5 and 30.6 to 37

C Controls: Survival in the intake samples; no other control. Initial intake survival range: 74 100% for striped bass 53 94% for white perch 49 68% for herrings Initial discharge survival range: 14  80% for striped bass 6  56% for white perch 5  29% for herrings Calculation of Entrainment Survival: Discharge Survival/ Intake Survival Data for many taxa or life stages collected were insufficient for analysis Confidence intervals / standard deviations: were not presented Significant differences were tested between the intake and discharge survival Significantly lower survival in discharge: striped bass PYSL white perch PYSL and juveniles herring PYSL and juveniles Survival calculated for species with fewer than 100 organisms collected: yes Egg survival: data not presented Larval survival: decreased markedly within 3 hours of collection. Size effects: survival by larval length was not studied Raw data: were not provided to verify results Temperature effects: significant decrease in survival at discharge temp > 30

C Mechanical effects: unknown § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival March 11, 2003 A7 43 Roseton Generating Station Hudson River, NY 1977 Study Ecological Analysts Inc., 1978e Sampling: Dates: March 3 17 and May 31st  July 15th Samples collection frequency: unknown; usually 4 nights per week was stated Times of peak abundance: coincided with spawning of targeted species Time: 1700 to 0300 hours EST Number of replicates: unknown; an average of 8 to 10 per night was stated Intake and discharge sampling: unknown if samples were collected in pairs Elapsed collection time: 15 minutes Method: pump/ larval table combination ambient water flow in table to reduce thermal exposure during sorting Depth: mid depth Intake location: in front of trash racks Discharge location: from seal well 244 m from end of discharge pipe Water quality parameters measured: no DOC and POC measured: no Intake and discharge velocity: unknown Operating Conditions During Sampling: Number of units in operation: unknown Number of pumps in operation: varied between 2 and 4 Temperature: Intake temperature: 0.5  5.5

C ( March); 11 27

C ( June/ July) Discharge temperature: 7  17

C ( March); 24  36

C ( June/ July)

  T range: unknown Biocide use was not noted Survival Estimation: Number of sampling events: unknown Total number of samples collected: unknown Total number of organisms collected: 6,973 Number of organisms entrained per year: unknown Fragmented organisms: if > 50% present, organism was counted Equal number collected at intake and discharge: up to 2.3X more in discharge Most abundant species: atlantic tomcod, herrings, striped bass, white perch Stunned larvae: included in initial survival proportion Dead and opaque organisms: not mentioned Latent survival: observed in aerated glass jars for 96 hours Data: combined by discharge temperature range, < 29.9, 30.0  32.9, > 33

C Controls: Survival in the intake samples was considered to be the control Initial intake survival range: 39% for Atlantic tomcod 0 to 50% for striped bass 0 to 33% for white perch 0 to 59% for herrings Initial discharge survival range: 16% for Atlantic tomcod 0 to 83% for striped bass 0 to 50% for white perch 0 to 14% for herrings Calculation of Entrainment Survival: Discharge Survival / Intake Survival Confidence intervals / standard deviations: were not presented. Significant differences were tested between the intake and discharge survival Significantly lower survival in discharge: Atlantic tomcod YSL striped bass PYSL white perch PYSL herring PYSL and juveniles Survival calculated for species with fewer than 100 organisms collected: yes number of some taxa and life stage were too low to estimate survival reliably Egg survival: data not presented Larval survival: decreased markedly within 3 hours of collection. increased with larval length Raw data: were not provided to verify results Temperature effects: survival decreased at temperatures above 30

C very low survival at temperatures > 33

C ( 0 to 3%) Mechanical effects: survival may increase with number of pumps operating Quality control: color coded labels, immediate checks of sorted sample, SOP's Peer review: not mentioned, study was conducted for the facility § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival A7 44 March 11, 2003 Roseton Generating Station Hudson River, NY 1978 Study Ecological Analysts Inc., 1980c Sampling: Dates: March 13  23 and June 6  July 13 Samples collection frequency: 3  4 nights per week Times of peak abundance: coincided with spawning of targeted species Time: 1700 to 0300 EDT Number of replicates: 4 to 10 per night Intake and discharge sampling: unknown if paired samples Elapsed collection time: 15 minutes Method: pump/ larval table combination with fine mesh ambient water flow to table to minimize thermal exposure when sorting Depth: mid depth Intake location: in front of trash rack Discharge location: in seal well 244 m from end of discharge pipe Water quality parameters measured: none DOC and POC measured: no Intake and discharge velocity: unknown Operating Conditions During Sampling: Number of units in operation: varied between 1 and 2 Number of pumps in operation: varied between 2 and 3 Temperature: Intake temperature: 0.2  5.5

C ( March), 19.8  24.0

C ( June/ July) Discharge temperature: 10  19

C ( March), 24  37

C ( June/ July)

  T range was not given Biocide use was not noted Survival Estimation: Number of sampling events: 30 Total number of samples collected: 256 Total number of organisms collected: 5,308 Number of organisms entrained per year: unknown Fragmented organisms: counted if > 50% of organism was present 22% of Atlantic tomcod could not be identified to life stage due to damage Equal number of organisms collected at intake and discharge: varied Most abundant species: herrings, white perch, striped bass, Atlantic tomcod Stunned larvae: included in initial survival proportion Dead and opaque organisms: not mentioned Latent survival: observed in aerated glass jars for 96 hours Data: combined by discharge temperature range < 29.9, 30.0  32.9, > 33

C also combined by larval length Controls: Survival in the intake samples was considered to be the control Initial intake survival range: 75 84% for Atlantic tomcod 8  100% for striped bass 0  93% for white perch 0  67% for herrings Initial discharge survival range: 23 33% for Atlantic tomcod 0  50% for striped bass 0  100% for white perch 0  18% for herrings Calculation of Entrainment Survival: Discharge survival/ Intake survival Confidence intervals / standard deviations: were not presented Significant differences were tested between the intake and discharge survival Significantly lower survival in discharge: Atlantic tomcod YSL and PYSL striped bass PYSL white perch PYSL herring PYSL Survival calculated for species with fewer than 100 organisms collected: yes samples sizes of some taxa and life stages were too small to analyze survival Egg survival: data not presented Larval survival: decreased markedly within 3  6 hours of collection increased with larval length Raw data: consolidated data by temp. and length was provided; not by sample Temperature effects: significant decrease in survival at temperatures > 24

C very little survival at temperatures > 30

C Mechanical effects: lower tomcod survival in discharge w/ o thermal effects Quality control: color coded labels, checks of sorted samples, SOP's Peer review: not mentioned, study was conducted for the facility § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival March 11, 2003 A7 45 Roseton Generating Station Hudson River, NY 1980 Study Ecological Analysts Inc., 1983 Sampling: Dates: May 26  July 31 Samples collection frequency: usually 4 nights per week Times of peak abundance: coincided spawning of striped bass and white perch Time: 1600 to 0200 EDT Number of replicates: varied between 1 and 10 per sampling date Intake and discharge sampling: unknown if samples were paired Elapsed collection time: 15 minutes Method: pump/ larval table or plankton sampling flume ambient water injection system to minimize thermal exposure Depth: unknown Intake location: from the No. 1B circulating water pump forebay Discharge location: from discharge seal well or submerged diffuser port Water quality parameters measured: none DOC and POC measured: no Intake and discharge velocity: unknown Operating Conditions During Sampling: Number of units in operation: varied between 1 and 2 Number of pumps in operation: varied between 3 and 4 Temperature: Intake temperature: 17.0  29.0

C Discharge temperature: 21.5  34.5

C   T range not given Biocide use was not noted Survival Estimation: Number of sampling events: 42 Total number of samples collected: 1431 Total number of organisms collected: 4,965 Number of organisms entrained per year: not given Fragmented organisms: counted if > 50% of organism was present 7% of all organisms would not be identified to a life stage due to damage Equal no. of organisms collected at intake/ discharge: more samples at discharge Most abundant species: herrings, striped bass, white perch Stunned larvae: were included in initial survival proportion Dead and opaque organisms: not mentioned Latent survival: observed in aerated glass jars for 48 hours. Data: combined by larval length Controls: survival in the intake samples was considered to be the control Initial intake survival range: 33  100% for striped bass 0  75% for white perch 30  53% for herrings Initial discharge survival range: 23  100% for striped bass 0  88% for white perch 0  31% for herrings Calculation of Entrainment Survival: Discharge survival / Intake survival Confidence intervals / standard deviations: were not presented. Significant differences were tested for latent survival only Survival calculated for species with fewer than 100 organisms collected: yes Egg survival: not studied Larval survival: decreased markedly within 3  6 hours of collection survival increased with larval length survival lowest for YSL and highest for juveniles survival using flume was very low Raw data: only consolidated data were presented, not by sample Temperature effects: data not given Mechanical effects: number of pumps may not affect survival Quality control: color coded labels, SOPs Peer review: not mentioned, study was conducted for the facility § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival A7 46 March 11, 2003 A7 4 DISCUSSION OF REVIEW CRITERIA In this section, the criteria EPA used to review the entrainment survival studies will be discussed in depth to give a better indication of the soundness of the science behind a facility's estimate of potential survival.

A7 4.1 Sampling Design and Methodology These aspects of the sampling effort are relevant to whether the samples collected are representative of the community of organisms experiencing entrainment, whether the estimates of densities and numbers are accurate and precise, and whether the survival estimates for the intake and discharge can be validly compared ( Marcy, 1975; Boreman and Goodyear, 1981). Sampling should be carefully planned to minimize any potential bias ( Marcy, 1975; Boreman and Goodyear, 1981). Studies should be conducted throughout the parts of the year when substantial numbers of organisms are entrained. Survival can be expected to vary with factors that change seasonally, such as organism size and life stage and ambient water temperature. Most studies attempted to collect samples during times of peak abundance, although the sampling frequency may not have been sufficient to fully capture peak densities. Of those reviewed by EPA, six studies did not seem to correspond with the timing of peak densities at that location.

Even if a study is limited to the early life stages of particular fish or shellfish, survival differences among sizes and life stages and seasonal or temperature related changes in entrainment survival need to be quantified. The timing of the sample collection for an entrainment survival study can influence results in a number of ways, such that results of studies collected during one period may not be representative of potential effects during other periods. For instance, samples collected when the intake temperatures are low or late in a spawning season when larvae are larger, have the potential to produce estimates of entrainment survival which may be higher than at other times. Thus, studies need to be conducted throughout an entire spawning season to accurately characterize overall entrainment mortality, if entrainment survival is found to vary with life stage or size of each species entrained. For the same reason, it may not be appropriate to develop average survival estimates from samples collected under different environmental conditions ( in particular under different temperature regimes) and over an entire spawning period.

Many studies collected their samples at night to ensure high numbers of organisms in their samples because larvae rise to the surface to feed at night to avoid predation ( Marcy, 1975; Day et al., 1989). Unfortunately, this practice may bias results because dead organisms do not to rise to the surface to feed. There is also evidence that dead organisms may even sink to the bottom of the water column after entrainment ( Marcy, 1975). When samples from the intake or discharge stations are collected near the surface at night, they may contain a higher percentage of alive organisms than that which actually occurs. Twenty four studies indicated that sampling occurred mostly at night. For many studies, the depth of sampling is not noted and thus it is unclear whether the samples were collected near the surface, at mid depth or near the bottom of the water column and any potential for bias due to a higher percentage of alive organisms present near the surface could not be assessed.

The method of sampling should be selected to cause the least amount of mortality as possible and the mesh size should be sufficient to capture disintegrated or fragmented organisms. All studies seem to have used sampling methods with mesh size greater than or equal to 500 µ m. This may not be sufficiently fine to capture disintegrated or fragmented organisms in the discharge.

Intake and discharge sampling should be paired to be sure that the same population of organisms is sampled and subsequently compared. In twelve studies it is unknown if the samples at the intake and discharge were paired. In some studies not all locations were collected during all sampling events. In other studies, twice as many samples were collected at the discharge than at the intake. Also in many instances, the intake samples were collected at different units of the facility than the discharge samples. Average elapsed time for sample collection is given, and it is unclear if the same elapsed time was used at both locations to give an accurate depiction of organismal densities. The time elapsed during sample collection or the volume of water sampled should be identical in the paired intake and discharge samples to insure valid comparisons of samples. It was not indicated in any of the studies reviewed whether the same volume of water was sampled in all of the intake and discharge samples.

The location of the intake sampling is important as it may contain organisms that have already died due to the changes in velocity near the intake. Two studies collected intake samples after the water had entered the cooling system. The location of the discharge sampling is also important. Samples collected from the end of the discharge canal may not contain organisms that have died from passage through the facility due to the tendency for dead organisms to settle out of the water column as they flow through the discharge canal. Samples collected from the discharge pipe may not contain organisms that have died from thermal effects of entrainment because they samples are collected before the full effects of thermal § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival March 11, 2003 A7 47 exposure have occurred. Fourteen studies collected discharge samples from the discharge pipe. It is also unknown if the samples collected in the discharge canal or from the receiving water contained organisms in the dilution water which bypassed the cooling water system. Five studies collected discharge samples in the receiving water downstream from the discharge canal which may have resulted in samples containing organisms which did not pass through the cooling water system.

Water chemistry conditions also need to be recorded to be sure conditions are similar at all sampling locations. Water quality indices include measurements of dissolved oxygen, pH, and conductivity in the through plant water, at the discharge point, and in the containers or impoundments in which the entrained organism are kept when determining latent mortality. Eighteen studies gave some indication that water quality parameters were measured during the study. However, it is unclear whether measurements were collected at both the intake and discharge, and only one study indicated that water quality parameters were measured in latent mortality studies ( EA Engineering Science and Technology, 1986).

Organic carbon in water occurs in dissolved ( DOC) and particulate ( POC) forms ( Valiela, 1995). Dissolved organic carbon ( DOC) compounds include soluble carbohydrates, sugars, fatty acids and amino acids which have leached from shredded and decomposing organic matter ( Schlesinger, 1991; Valiela, 1995). DOC is differentiated from POC by its ability to pass through filters of a size of 0.2  0.45 µ m ( Valiela, 1995). Changes in DOC and POC at the intake and discharge may be a suitable means for determining whether organisms are disintegrated as they pass through the cooling water system and thus are not captured in the screens of the sampling device. None of the studies reviewed measured changes in DOC and POC concentrations in the water column.

The velocity at the intake and discharge should also be recorded to determine the potential to cause mortality. Fourteen of the studies gave some indication of the velocity at either the intake or the discharge, or both. For the ones that did not give both intake and discharge velocities, it is unknown whether the velocities at the two sampling sites were comparable, and thus whether the mortalities due to velocity related sampling stress were comparable at the two locations.

A7 4.2 Operating Conditions During Sampling Mortality due to entrainment stress is affected by the operating characteristics of the power facility. The conditions under which the samples are collected are extremely important and therefore, the results can only be assumed to represent survival when the facility is operating under those same conditions and at that time of year, and may not represent the potential for survival at all times. For example, results of studies conducted when the plant was not generating power ( and thus not transferring heat to the cooling water) would not be applicable to impacts when it was in full operation. The magnitude of mechanical stress may be dependent on the design of the facility's cooling water intake structure. The physical and operating conditions of the facility need to be recorded to determine their effect on entrainment survival. The percentage of the maximum load at which the facility is operating needs to be recorded at the time of sampling to give an indication of the extent to which organisms are exposed to stress. The number of units was highly variable or unknown in many studies reviewed. One study indicated that the facility operated at peak load to maximize temperature stress during the time of sampling. Eight studies indicated that power was generated during only a portion of time in the sampling period. To fully account for the effects of mechanical stressors on entrainment survival, the study needs to reflect the speed and pressure changes within the condenser, the number of pumps in operation, the occurrence of abrasive surfaces, and the turbulence within the condenser. In addition, it is important to note the number and arrangement of units, parallel or in sequence, which may expose organisms to entrainment in multiple structures. Survival should be studied under the range of conditions that may influence survival, for example intake flow or capacity utilization and ambient ( intake) water temperature and delta T ( if these vary substantially).

The effect of temperature can be species specific since different fishes have different critical thermal maxima. The maximum temperature to which organisms may be exposed while passing through the facility may cause mortality in some species but not others. To assess the effect on entrainment survival by thermal stressors, the study needs to determine the temperature regime of the facility. Specifically, the study needs to record the temperature at intake and at the discharge point for each component of the facilities system: temperature changes within the system, including the inflow temperature, maximum temperature, delta T, rate of temperature change, and the temperature of the water to which the organisms are discharged. It is also important to measure the duration of time an organism is entrained and thus exposed to the thermal conditions within the condenser and in the mixing zone of the discharge canal. This information was not provided in all studies. Also, in those studies that attempted to relate survival to temperature stress, too few samples were collected at different temperature ranges to give adequate representation of survival in that range. The EPRI report sorted larval entrainment survival data by discharge temperature and determined that survivability decreased as the discharge temperature increased ( EA Engineering, Science and Technology, 2000). The lowest probability of larval survival occurred at temperatures greater than 33 ° C. In studies reviewed by EPA, a substantial decrease in survival estimates occurred at § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival A7 48 March 11, 2003 discharge temperatures above 30

C. The amount of time that a facility discharges water in different temperature ranges and survival estimates at that temperature range should be weighed when attempting to determine the survival estimate throughout the year, rather than using an average survival during the sampling period which may not adequately reflect operating conditions throughout the year.

To properly account for chemical stressors, the timing, frequency, methods, concentrations, and duration of biocide use for the control of biofouling need to be determined. The extent to which biocides are used routinely at this time is unknown. The studies reviewed by EPA were all conducted at times when biocides were not in use, clearly because the biocide use would be expected to kill all organisms. Thus, the results of these studies do not account for biocide impacts and the results of these studies can only reflect other times when biocides are not in use at the particular facility. A reduced survival estimate for the proportion of time when biocides were in use would have to be incorporated into any estimation of annual mean entrainment mortality value for a facility for that estimate to be valid.

A7 4.3 Survival Estimates Many of the entrainment survival studies reviewed did not account for the extent to which the most fragile life stages are fragmented and destroyed by both sampling and entrainment. Only six studies acknowledged that the entrainment survival estimates were indicative only of alive and stunned identifiable organisms which were at least 50 percent intact. In such circumstances, an important element of the entrained biological community may be omitted from the estimate of survival. Entrainment survival studies should not include only those organisms that are either whole or 50 percent whole in the sample. For those studies that did not discuss the issue of fragmented organisms, it is unclear how the issue was treated. Several studies indicated that the majority of the sample was mangled or unidentifiable. There is potential for an extremely large number of dead organisms to be excluded from entrainment survival estimates because they are fragmented to the point of being unidentifiable. Studies should account for this fragmentation of organisms by either measuring unidentifiable biomass in the samples or by determining the change in the levels of particulate organic carbon ( POC) or dissolved organic carbon ( DOC) from the intake and discharge stations. Without taking these organisms into account, entrainment survival estimates will be biased extremely higher than that which actually occurs. There are indications that the fragmented organisms, which are generally not included in survival estimates, may be a substantial number which results in an overestimation of entrainment survival if these fragmented organisms are more prevalent in the discharge. In the proceedings of a conference held in Providence, RI on January 6, 1972, entitled Pollution of the interstate waters of Mount Hope Bay and its tributaries in the states of Massachusetts and Rhode Island, the following regarding fragmentation was quoted "... in 1970 when we observed many small transparent larval menhaden in the intake. They were most readily noted by their black eyes. But in the effluent, all we found were eyes. They were torn to pieces" ( US EPA, 1972). Foam observed in the discharge ( Thomas, 2002) may indicate that fragmentation is substantial and can be verified by measuring the concentration change of DOC and POC in the discharge. The data summary in Jinks et al. ( 1981) suggests that a substantial number of fish larvae may be fragmented by mechanical forces and become unrecognizable, contributing to a bias in estimates of survival. Ten of the studies reviewed by EPA reported finding fragmented organisms; others apparently did not quantify evidence of mutilated larvae. High rates of physical damage ( 15% to 33% for larvae < 17.5 mm) and abundant larval fish fragments were reported by Stevens and Finlayson ( 1978) at the Pittsburg and Contra Costa power plant discharges. Such losses can contribute to a bias ( overestimation) of entrainment survival as the number of dead organisms are not properly enumerated. In addition, the low numbers of organisms sampled in the studies in relation to the high annual entrainment numbers gives further indication that the sampling effort may not result in a adequate representation of the organism entrained and therefore the sampling estimates may not represent that which actually occurs.

The inclusion of stunned larvae in the initial survival estimates may result in overestimations of survival, since the majority of these organisms died in the laboratory latent survival studies and even more may die in the natural conditions of the discharge canal due to predation or disrupted growth and development. Twenty nine studies included stunned larvae in their initial survival estimates, and only a few indicated that this may tend to overestimate initial survival since many of these stunned larvae die within hours of collection in laboratory latent survival studies and most would be expected to die due to increase risk of predation after discharge. The remainder of the studies did not discuss the treatment of stunned larvae. Many studies only reported initial, acute mortality. Both initial mortality and extended or latent ( 96 hour) mortality should be studied and reported to ensure the most accurate overall survival estimate.

Dead and opaque organisms should not be excluded from the enumeration of dead organisms. The reason given for why this was done in some studies is that these dead and opaque organisms most likely died prior to entrainment. However, dead organisms can turn opaque within an hour which is the same amount of time which elapses during sampling collection and sorting. Also, zero dead and opaque organisms were collected in the samples of one study when the facility was not generating power. Three studies omitted dead and opaque organisms from the dead classification used to estimate survival. § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival March 11, 2003 A7 49 This resulted in an elimination of up to 99% of the organisms in the samples of one study. On the other hand, one study only counted those organisms which were opaque as dead.

The study design should support unbiased estimation of survival, taking into account pertinent factors and the changing relative abundances of species and life stages. Because entrainment mortality changes with ambient and operating conditions and life stages, and because the numbers of various species and life stages entrained also change diurnally and seasonally, use of an average value for entrainment survival could be misleading. Organisms should be counted and sorted by both species, life stage, and size. Entrainment survival should then be calculated separately for each life stage of each species. Entrainment survival appears to vary markedly with fish larval size ( EA Science & Technology, 1989); mortality is often high for smaller larvae and low for larger ones. Thus, survival measured for a heterogeneous mixture of sizes will apply only to that mixture under the same conditions, and cannot be used to accurately estimate survival for the species over the course of even part of a season. The approach of modeling survival in relation to size seems promising ( EA Science & Technology, 1989). The implication is that accurate assessment of entrainment survival requires frequent samples throughout a season, to reflect the changing size and species composition of the ichthyoplankton. In most studies all data from all samples collected under varied times and conditions were combined to give an average entrainment survival. However, bias could be introduced when a disproportionate number of samples are taken under a specific set of conditions which may not accurately reflect conditions throughout the year. Only 16 of the 35 studies estimating entrainment survival by sampling reported standard deviations or confidence intervals for the survival estimates. The apparent precision of estimates based on hundreds of organisms, and the estimates themselves are deceptive. Such estimates are based on aggregated numbers that vary in size, and larval fish survival depends on size ( EA Science & Technology, 1989). Sizespecific estimates of survival can be made, with wider confidence intervals.

The volume of water sampled should always be reported with the number of organisms counted in the sampled volume. This allows estimates of the densities of organisms in the intake and discharge water. Density estimates provide an important check on assumptions. When organism densities cannot be measured accurately, a useful check on disintegration of organisms that are never counted can not be performed. Another check on loss of organisms by disintegration is a count of body parts, which was done in only one of the studies reviewed, but this will not account for organisms rendered unrecognizable or totally disintegrated. In some studies, the number of organisms in discharge samples were many times greater than the number of organisms in intake samples using the same sampling methods. In other studies, there were many times more organisms collected in the intake samples than the discharge samples. Such large differences raise concerns about sampling methodology and possible causes of bias that need to be investigated and accounted.

Control samples that test the mortality associated with sampling gear should be taken as far away from the intake as possible. This will ensure that the rates of mortality determined will be solely from natural causes or sampling damage and not from potential damage due to increased velocity and turbulence near the intake. Sampling mortality should be reduced to the maximum extent possible, using modern sampling techniques ( EA Engineering Science & Technology, 2000). When control survival is significantly low and less than discharge survival, no attempts should be made to calculate entrainment survival which would give an erroneous survival result of greater than 100 percent. The studies which resulted in entrainment survival estimates greater than 100 percent indicates that these studies' methods of calculating entrainment survival are flawed by methodological biases.

The calculation of survival from the ratio of the fraction alive in discharge samples to the fraction alive in intake samples requires assumptions not supported by the same studies. These assumptions are: ( 1) no organisms are lost to counting by destruction in the cooling water system, in other words, the same density of organisms ( dead or alive) is observed in the discharge as in the intake; ( 2) the sampling method causes the same rate of mortality in the discharge sample as in the intake sample. The first assumption is without doubt violated for many species and life stages. The second assumption is also questionable, because any organisms alive in the discharge have survived entrainment and may be more resistant to sampling related mortality. Because the loss of organisms by disintegration is not measured, if a substantial number of organisms are destroyed and thus are not counted in the discharge, it is more likely that entrainment survival will be overestimated. The second assumption can be minimized if methods of sampling are used that reduce sampling mortality to a minimum ( EA Engineering Science & Technology, 2000); such methods ( e. g., rear draw pumping methods, pumpless flume) were used in only 5 of the 35 studies reviewed above. The formula commonly used ( EA Engineering Science & Technology, 2000) to estimate entrainment survival, SI = PD / PI , is appropriate in experimental situations in which the number of organisms at risk is verified to equal the number counted ( alive and dead) at the end of the study. It can be applied in observational studies when it is known from other solid evidence that the number at risk is conserved ( i. e. no organisms are lost in sampling or destroyed so they cannot be counted). The biases that result from loss via sampling or destruction, and other causes, were clearly illustrated by Boreman and Goodyear ( 1981). If Abbott' s correction for control mortality is applied, it requires the assumption that sampling mortality rate is the same for the intake and discharge samples. This source of bias was also considered by Boreman and Goodyear ( 1981). Abbott's correction may contribute to overestimation of entrainment survival because it attributes to entrainment only that mortality in excess of the mortality § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival A7 50 March 11, 2003 attributed to sampling. This may overestimate entrainment survival for two reasons: it is likely that sampling and entrainment mortality are not entirely additive, and, as noted above, it is quite possible that the sampling mortality rate is less in the discharge sample than in the intake sample that is used as the control.

A7 5 APPLICABILITY OF ENTRAINMENT SURVIVAL STUDIES TO OTHER FACILITIES Due to many factors, the potential for entrainment survival is facility specific. Therefore, EPA does not suggest that entrainment survival estimates be applied to other facilities, as was done in the Muskingum River Plant study ( Ecological Analysts Inc., 1979a). To correctly transfer the results, the physical attributes of facilities would need to be extremely similar. Specifically, the facilities would need to have similar numbers of cooling water flow routes, similar lengths of flow routes in terms of time and linear distance, similar mechanical features in terms of abrasive surfaces, pressure changes and turbulence, and similar number and types of pumps used. In addition, there would need to be similarity and constancy of the flow rates, transit times, thermal regimes, and biocide regimes. The ecological characteristics of the environment around the facility would also need to be similar in terms of ambient water temperature, dissolved oxygen level, and the species and life stage of organisms present. Similarities or differences in these aspects may profoundly affect the applicability of the study between facilities. The studies reviewed by EPA were unsuitable for developing unbiased estimates of entrainment survival over the pertinent courses of time ( diel and seasonal) and the typical environmental and operating conditions at the facilities conducting the studies, and thus cannot be used to estimate entrainment survival at section 316( b) facilities nationwide.

A7 6 CONCLUSIONS EPA's review of the 36 entrainment survival studies described above has revealed a number of limitations that challenge their use in assessing the benefits of the section 316( b) Phase II Existing Facilities Rule. The primary issue with regard to these studies is whether the results can support a defensible estimate of survival substantially different from the value of zero percent survival assumed by EPA in assessing benefits of the proposed rule. Given the fact that live organisms can be found in the discharge canals of many cooling water intake systems, it may be true that not all organisms are necessarily killed as they pass through the cooling systems of all facilities under all operating conditions. However, the results of the 36 studies, summarized in Table A7 1, suggest that the proportion alive in the samples is highly variable and unpredictable among species and among facilities. The studies document that some species ( e. g., herrings, bay anchovy) are extremely sensitive to entrainment and suffer nearly complete mortality, with calculated mortality rates of 100 percent at most facilities. Other species, such as striped bass, may be more resistant to entrainment effects. However, even for these apparently hardier species, some studies yielded ranges of entrainment survival estimates that included zero and latent survival values very close to zero. Multiple studies as the same facility ( e. g., Bowline Point, Indian Point) yielded survival values for species such as striped bass that varied substantially among years, most likely due to a combination of changes in environmental conditions, changes in plant operations as well as changes in sampling and testing procedures. Temperature seems related to survival, but the effect may vary greatly depending on intake water temperature, plant design, fish species and life stages. Few of the studies could conclusively document and quantify the specific stressors causing the observed mortalities and no rigorous, validated method or model was put forward that would allow survival rates to be accurately predicted. Another major constraint on the use of these findings in this rulemaking process is that they cover very few species, primarily in a single geographical region of the country, thus providing no basis for prediction or projection of effects to other species in other parts of the country. These studies as well as other literature also clearly show that findings from one facility cannot be considered to be valid for another facility, since many site specific and facility specific factors can affect the magnitude of mortality that occurs. The current state of knowledge would not support predictions of entrainment survival for the range of species, life stages, regions and facilities involved in EPA's benefits estimates.

The potential usefulness of all of the findings of all of the studies is further compromised by the numerous factors that can influence the representativeness, accuracy, and precision of the survival estimates presented and that are often not rigorously accounted for in the studies reviewed. These factors are described in Section A7 2, and some of the deficiencies of the studies with regard to these factors are elaborated on in Section A7 3. The most frequent and serious deficiencies noted ( e. g., high control mortalities; omission of fragmented or unidentifiable organisms, and uncertainty regarding postdischarge survival) compromise the accuracy and precision of the survival estimates. In many of the studies, the precision of the survival estimates was not rigorously assessed, and thus the uncertainty associated with the estimates is not known. If the factors addressed in this review were taken into account in an entrainment survival study, EPA believes that the estimate of survival which would result would not be substantially different from zero. § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival March 11, 2003 A7 51 EPA acknowledges that some of the studies performed at some facilities were designed in a more rigorous manner than others in order to minimize the influence of factors that could compromise findings ( e. g., the use of a larval table for assessing physiological condition) and included comprehensive sampling in an attempt to enhance the accuracy and precision of the survival estimates. However, while such studies may have provided estimates for the facility studied under the environmental and operational conditions that occurred at the time the study was performed, they do not provide a basis for generalizing specific survival rates for all or even the same species at other facilities or at the same facility in other years. In addition, there exists the possibility of additional post discharge ( latent) mortality when entrained organisms are returned to the receiving water body. Overall, the unreliability, variability and unpredictability of entrainment survival estimates evident from EPA's review of the entrainment survival studies supports the use of the assumption of zero percent survival in the benefits assessment because there is no clear indication of any defensible estimate of survival substantially different from zero percent to use to calculate benefits for this rule.

References Beck, A. D. and the Committee on Entrainment. 1978. Cumulative Effects: A field assessment. Power Plant Entrainment: A Biological Assessment. J. R. Schubel and B. C. Marcy Jr., eds. Academic Press: New York. Pp. 189 210.

Boreman, J., and C. P. Goodyear. 1981. Biases in the estimation of entrainment mortality. Fifth National Workshop on Entrainment and Impingement: Issues Associated with Impact Assessment. L. D. Jensen, ed. Ecological Analysts Inc.: Sparks, Maryland. pp. 79 89 Carter, S. R. 1978. Macroinvertebrate Entrainment Study at Fort Calhoun Station. Fourth National Workshop on Entrainment and Impingement. EA Communications: Melville NY. Pp. 155 169.

CCI Environmental Services, Inc. 1996. Zooplankton Entrainment Survival Study, Anclote Power Plant, Pasco County, Florida. CCI, Palmetto Fl. Prepared for Florida Power Corporation.

Chen, I. 2002. Personal communication to D. Nagle on 12/ 17/ 02.

Colarusso, P. 2002. Personal Communication to D. Nagle on 12/ 17/ 02.

Coutant, C. A. and M. S. Bevelhimer. 2001. Comments on Lawler, Matusky & Skelly Engineers, LLP. 1999 draft Brayton Point Power Plant Entrainment Survival Study 1997 1998.

Day, Jr., J. W., C. A. S. Hall, W. M. Hall and A. Yáñez Arancibia. 1989. Zooplankton, the drifting consumers. Estuarine Ecology. John Wiley & Sons: New York. Pp. 311 337.

Ecological Analysts Inc. 1976a. Bowline Point Generating Station Entrainment Survival and Abundance Studies, Volume I, 1975 Annual Interpretive Report. Prepared for Orange and Rockland Utilities, Inc.

Ecological Analysts Inc. 1976b. Danskammer Point Generating Station Impingement and Entrainment Survival Studies, 1975 Annual Report. Prepared for Central Hudson Gas & Electric Corporation.

Ecological Analysts Inc. 1976c. Roseton Generating Station Impingement and Entrainment Survival Studies, 1975 Annual Report. Prepared for Central Hudson Gas & Electric Corporation.

Ecological Analysts Inc. 1977. Bowline Point Generating Station Entrainment and Impingement Studies, 1976 Annual Report. Prepared for Orange and Rockland Utilities, Inc.

Ecological Analysts Inc. 1978a. Bowline Point Generating Station Entrainment Survival Studies, 1977 Annual Interpretive Report. Prepared for Orange and Rockland Utilities, Inc.

Ecological Analysts Inc. 1978b. Impact of the Cooling Water Intake at the Indian River Power Plant: A 316( b) Evaluation. Prepared for Delmarva Power & Light Co.

Ecological Analysts Inc. 1978c. Indian Point Generating Station Entrainment Survival and Related Studies, 1977 Annual Report. Prepared for Consolidated Edison Company of New York, Inc. § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival A7 52 March 11, 2003 Ecological Analysts Inc. 1978d. Roseton Generating Station Entrainment Survival Studies, 1976 Annual Report. Prepared for Central Hudson Gas & Electric Corporation.

Ecological Analysts Inc. 1978e. Roseton Generating Station Entrainment Survival Studies, 1977 Annual Report. Prepared for Central Hudson Gas & Electric Corporation.

Ecological Analysts Inc. 1979a. An Assessment of the Potential for Ichthyoplankton Entrainment Survival at the Muskingum River Plant. Prepared for American Electric Power Service Corp.

Ecological Analysts Inc. 1979b. Bowline Point Generating Station Entrainment Abundance and Survival Studies, 1978 Annual Report. Prepared for Orange and Rockland Utilities, Inc.

Ecological Analysts Inc. 1979c. Indian Point Generating Station Entrainment Survival and Related Studies, 1978 Annual Report. Prepared for Consolidated Edison Company of New York, Inc.

Ecological Analysts Inc. 1980a. Entrainment Survival Studies at the Cayuga Generating Plant. Prepared for Public Service of Indiana.

Ecological Analysts Inc. 1980b. Potrero Power Plant Cooling Water Intake Structures 316( b) Demonstration. Prepared for Pacific Gas and Electric Company.

Ecological Analysts Inc. 1980c. Roseton Generating Station Entrainment Survival Studies, 1978 Annual Report. Prepared for Central Hudson Gas and Electric Corporation.

Ecological Analysts Inc. 1981a. Bowline Point Generating Station Entrainment Abundance and Survival Studies, 1979 Annual Report with Overview of 1975 1979 Studies. Prepared for Orange and Rockland Utilities, Inc.

Ecological Analysts Inc. 1981b. Entrainment Survival Studies. Prepared for Empire State Electric Energy Research Corporation.

Ecological Analysts Inc. 1981c. Indian Point Generating Station Entrainment Survival and Related Studies 1979 Annual Report. Prepared for Consolidated Edison Company of New York and Power Authority of the State of New York.

Ecological Analysts Inc. 1982. Indian Point Generating Station Entrainment Survival and Related Studies 1980 Annual Report. Prepared for Consolidated Edison Company of New York and Power Authority of the State of New York.

Ecological Analysts Inc. 1983. Roseton Generating Station Entrainment Survival Studies, 1980 Annual Report. Prepared for Central Hudson Gas and Electric Corporation.

Ecological Analysts Inc. and Ecological Analy. 1978. Port Jefferson Generating Station Entrainment Survival Study. Prepared for Long Island Lighting Company.

EA Engineering Science and Technology. 1986. Entrainment and Impingement Studies at Oyster Creek Nuclear Generating Station 1984 1985. Prepared for GPU Nuclear Corporation.

EA Engineering Science and Technology. 1989. Indian Point Generating Station 1988 Entrainment Survival Study. Final. Prepared under contract with Consolidated Edison Company of New York Inc. and New York Power Authority.

EA Engineering Science and Technology. 2000. Review of Entrainment Survival Studies: 1970 2000. Prepared for Electric Power Research Institute, Inc.

EA Science and Technology. 1986. Indian Point Generating Station Entrainment Survival Study. 1985 Annual Report. Prepared under contract with Consolidated Edison Company of New York Inc. and New York Power Authority.

EA Science and Technology. 1990. Results of Entrainment and Impingement Studies Conducted at the Braidwood Nuclear Station and the Adjacent Kankakee River. Prepared for Commonwealth Edison Company.

Hadderingh, R. H. 1978. Mortality of young fish in the cooling water system of Bergum power station. Proceedings International Association of Theoretical and Applied Limnology. 20: 347 352. § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival March 11, 2003 A7 53 Hazleton Environmental Science Corporation. 1978. The Survival of Entrained Ichthyoplankton at Quad Cities Station 1978. Prepared for Commonwealth Edison Company, Chicago, Illinois.

Jinks, S. M., G. J. Lauer and M. E. Loftus. 1981. Advances in techniques for assessment of ichthyoplankton entrainment survival. Fifth National Workshop on Entrainment and Impingement: Issues Associated with Impact Assessment. L. D. Jensen, ed. Ecological Analysts Inc.: Sparks, Maryland. pp. 91 110 Kimball, G. 2002. Personal communication to D. Nagle on 12/ 26/ 02.

Lawler Matusky & Skelly Engineers. 1985. 2.0 Entrainment Survival Studies. Quad Cities Aquatic Program 1984 Annual Report . Prepared for Commonwealth Edison, Chicago, Illinois.

Lawler Matusky & Skelly Engineers. 1999. Brayton Point Power Station Entrainment Survival Study, 1997 1998. Draft. Prepared for US Gen New England, Inc., Brayton Point Station, Somerset, MA.

Lauer, G. J., W. T. Waller, D. W. Bath, W. Meeks, D. Heffner, T. Ginn, L. Zubarik, P. Bibko, and P. C. Storm. 1974. Entrainment studies on Hudson River organisms. Proceedings of the Second Workshop on Entrainment and Intake screening, Report. 15. EPRI: Palo Alto, CA. Pp. 37 82.

Marcy Jr., B. C. 1971. Survival of Young Fish in the Discharge Canal of a Nuclear Power Plant. Journal Fisheries Research Board of Canada. 28: 1057 1060.

Marcy Jr., B. C. 1973. Vulnerability and Survival of Young Connecticut River Fish Entrained at a Nuclear Power Plant. Journal Fisheries Research Board of Canada. 30: 1195 1203.

Marcy, Jr., B. C. 1975. Entrainment of organisms at power plants, with emphasis on fishes   an overview. Fisheries and Energy Production. S. B. Sailia, ed. D. C. Heath and Company: Lexington, MA. Pp. 89 106.

Marcy Jr., B. C., A. D. Beck and R. E. Ulanowicz. 1978. Effects and Impacts of Physical Stress on Entrained Organisms. Power Plant Entrainment: A Biological Assessment. J. R. Schubel and B. C. Marcy, Jr. eds. Academic Press: New York. Pp. 135 188.

Mayhew, D. A., L. D. Jensen, D. F. Hanson, P. H. Muessig. 2000. A comparative review of entrainment survival studies at power plants in estuarine environments. Environmental Science & Policy 3: S295 S301.

McCullough, M. 2002. Personal communication to P. Howe on 12/ 20/ 02.

McLean, R. I. and J. J. Dieter. 2002. State of Maryland Comments on Proposed Regulations to Establish Requirements for Cooling Water Intake Structures at Phase Ii Existing Facilities; Proposed Rule, Published Federal Register, April 9, 2002. To Proposed Rule Comment Clerk  W 00 32, dated August, 5, 2002.

Morgan II, R. P. 1980. Biocides and Fish Behavior. Power Plants: Effects on Fish and Shellfish Behavior. C. H. Hocutt, J. R. Stauffer Jr., J. E. Edinger, L. W. Hall Jr., R. P. Morgan II, eds. Academic Press: New York. Pp. 75  102.

Morgan II, R. P. and E. J. Carpenter. 1978. Biocides. Power Plant Entrainment: A Biological Assessment. J. R. Schubel and B. C. Marcy, Jr. eds. Academic Press: New York. Pp. 95 134.

Newman, M. C. 1995. Quantitative Methods in Aquatic Ecotoxicology. Lewis Publishers: Boca Raton, FL. Pp. 135 136.

Schlesinger, W. H. 1991. Rivers and Estuaries. Biogeochemistry: An analysis of global change. Academic Press: San Diego, CA. Pp. 226 253.

Schubel, J. R., C. C. Coutant, P. M. J. Woodhead. 1978. Thermal Effects of Entrainment. Power Plant Entrainment: A Biological Assessment. J. R. Schubel and B. C. Marcy, Jr. eds. Academic Press: New York. Pp. 19 93.

Stauffer Jr., J. R. 1980. Influence of temperature on fish behavior. Power Plants: Effects on Fish and Shellfish Behavior. C. H. Hocutt, J. R. Stauffer Jr., J. E. Edinger, L. W. Hall Jr., R. P. Morgan II, eds. Academic Press: New York. Pp. 103 141.

Stevens, D. E. and B. J. Finlayson. 1978. Mortality of Young Striped Bass Entrained at Two Power Plants in Sacramento   San Joaquin Delta, California. Fourth National Workshop on Entrainment and Impingement. EA § 316( b) Existing Facilities Benefits Case Studies, Part A: Evaluation Methods Chapter A7: Entrainment Survival A7 54 March 11, 2003 Communications: Melville NY. Pp. 57 69.

Stuber, R. 2002. Personal communication to D. Nagle on 12/ 17/ 02.

Thomas, D. A. December 30, 2002. Memo to docket, RE: Observations of foam in discharge canals of 2 power plants.

Ulanowicz, R. E. and B. Kinsman. 1978. Purgatorio   Two rather different views of the same event. Power Plant Entrainment: A Biological Assessment. J. R. Schubel and B. C. Marcy, Jr. eds. Academic Press: New York. Pp. 245 253.

U. S. Environmental Protection Agency. 1972. Dr. Clarence Tarzwell. Pollution of the interstate waters of Mount Hope Bay and its tributaries in the states of Massachusetts and Rhode Island. Conference Proceedings, Providence RI, January 6, 1972. Volume 2, Washington DC NTIS No. PB 230 572. Pp. 591 623.

U. S. Environmental Protection Agency. 1998. Product Performance Test Guidelines OPPT 810.3500 Premises Treatments. EPA 712 C 98 413 U. S. Environmental Protection Agency. 2002. Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms. Fifth Edition. Section 11, Acute Toxicity Analysis. . EPA 821 R 02 012. Pp. 71 108.

Valiela, I. 1995. Spatial structure: Patchiness. Marine Ecological Processes. Springer: New York. Pp. 325 353.

Valiela, I. 1995. The carbon cycle: Production and transformations of organic matter. Marine Ecological Processes. Springer: New York. Pp. 385 424.