ML20083A943

Annual Environ Protection Plan Operating Rept Jan-Dec 1994 for Millstone Unit 3

ML20083A943
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Site:	Millstone
Issue date:	12/31/1994
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a Annual Environmental Protection Plan Operating Report January 1 - December 31,1994 L

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l Millstone Unit 3 Environmental Protection Plan  ;

l prepared by l Northeast Utilities Service Company P.O. Box 270 Hartford, Connecticut 06141-0270 ,

1 April 1995

$00"A000ko!00 [3 R

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4 Annual Environmental Protection Plan Operating Report  ;

January 1 - December 31,1994 t

P Millstone Unit 3 Environmental Protection Plan 1

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Prepared by: d<4.fa4T/ 4//5/15

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Reviewed by: ~ c~ /ee--+ v erei'

Annual Environmental Protection Plan Report - 1994

1. Introduction This report covers the period January 1 - December 31,1994. During 1994, Unit 3 was shut down for approximately two weeks in September, for repair of a failed main steam isolation valve, but was at full power (nominal 1150 MWe) for most of the rest of the year and completed a record run of 283 days. During 1994, Unit 3 operated at an annual capacity factor of 94%.

As required by the Millstone Unit 3 EPP, this Annual Environmental Protection Plan Operating Report (AEPPOR) includes:

1) summaries and analyses of the results of environmental protection activities,

2) a list of EPP noncompliances,

3) a list of all changes in station design or operation which involved a potentially significant unreviewed environmental question, and

4) a list of non-routine reports, describing events that could result in significant environmental impact.

2. Environmental Protection Activities 2.1 Annual NPDES Report of Ecological Monitoring (EPP Section 4.2) l Paragraph 5 of the referenced NPDES permit requires continuation of biological studies of MNPS supplying and receiving waters, entrainment studies, and intake impingement monitoring. These studies include analyses ofintertidal and subtidal benthic communities, finfish communities, entrained plankton, lobster populations, and winter flounder populations. Paragraph 13 of the permit requires an annual report of these studies to the Commissioner of Environmental Protection. The report that fulfills these requirements for 1994, Monitorine the Marine Environment of Lone Island @Soundit Millstone Nuclear Power Station.

Waterford. Connecticut - Annual Reoort.1994, presents results from studies performed during 3-unit operation, and compares them to those from 2-unit operation. The added cooling water flow for Unit 3 affects impingement and l entrainment, causes sediment scouring near the MNPS discharges, and alters the I characteristics of thermal effluent plume. The biological effects of these changes ,

are summarized in the Executive Summary section of the above-named report I (Attachment 1) and further discussed in the report itself (Attachment 2).

l 1994 AEPPOR 1

g 2.2 Effluent Water Quality Monitoring Paragraph 6 of the referenced NPDES permit requires monitoring and recording of many water quality parameters at MNPS intakes and at 37 discharge points within the plant, including outfalls of each unit to the effluent quarry, and outfall of the quarry to Long Island Sound. Paragraph 11 of the permit requires a monthly report of this monitoring to the Commissioner of Environmental Protection. The report that fulfills these requirements, Monthly Discharge Monitoring Reoort, includes data from all three Millstone units. Those data that pertain to Unit 3 are summarized in Table la. During 1994, one NPDES exception was reported from a discharge associated with Unit 3 (Table Ib),

specifically an oil spill from Discharge Serial Number (DSN) 006, which collects discharges from various sources, including Unit 2 and Unit 3 floor drains and clean water drains, and storm water runoff.

On April 29,1994 a small break occurred in the Unit 3 condenser cooling water system. Until the system was repaired, leaking seawater was drained into the turbine building sump; this sump drains to DSN 006 via an oil water separator.

The leaking seawater volume was such that the capacity of the oil water separator was exceeded. This caused a small release of oil from the oil water separator through DSN 006. This release was observed as a light sheen on the receiving water. Plant personnel immediately deployed oil absorbent booms, which contained and absorbed the oil. It was estimated that, at most, two quarts of oil may have escaped from the oil water separator.

Sampling for hydrazine (N 2H 4), biological oxygen demand (BOD), and chemical oxygen demand (COD) is required only when discharging wastewater containing hydrazine, The major hydrazine discharges at Unit 3 are from DSN 001C-la, releases following wet lay-up of steam generators during extended outages; during 1994, none of these discharges occurred.

3. Environmental Protection Plan Noncompliances During 1994, no EPP noncompliances were identified for Unit 3.

4. Environmentally Significant Changes to Station Design or Operation During 1994, no Unit 3 Plant Design Change Records (PDCRs) met the acceptance criteria for inclusion in this report, i.e., a) were initiated during the report year, and b) included a determination that an unreviewed environmental impact could occur. Of the 169 PDCRs initiated during 1994, none involved unreviewed environmental issues.

As of December 31,1994, Unit 3 has 188 System Operating Procedures; of Sse,123 were added or revised during 1994. In addition, many procedures were scodified to 1994 AEPPOR 2 t

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k 7 reflect small changes, ofinsufficient magnitude to require the issuance of a new revision.  !

However, each of these changes, as part of the review / approval process, included an  :

environmental evaluation; none were determined to involve an unreviewed environmental l impact.' j I

5. Non-Routine Reports of Environmentally Significant Events l During 1994, no events occurred at Unit 3 that met the acceptance criteria for inclusion 3

in this report, i.e., required submittal of a Licensee Event Report (LER) from Unit 3, and ,

involved a situation that could result in a significant environmental impact Of the 12-  !

events that constituted reportable occurrences in 1994, none were determined to cause a

-l significant environmental impact.  :

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1994 AEPPOR 3 i

Table 1. Millstone Unit 3 NPDES Data Summary, Jan.1 - Dec. 31,1994.

a). Selected water quality parameters for Unit 38 discharge discharge discharge discharge avg max max SWS flow range pH range temp, range temp. (avg) AT FAC TRC FAC (10' gpm) (*F) ( F) (F) (ppm) (ppm) (ppm)

Jan. 790-948 6.5-7.9 42.8-59.7 54.7 17.3 0.10 0.08 0.20 Feb. 790-948 7.8-8.0 48.6-55.2 52.2 17.8 0.17 < 0.10 0.19 Mar. 790-942 7.7-8.0 50.0-59.0 53.3 17.5 0.14 < 0.10 0.20 Apr. 790-948 7.7-7.9 54.9-68.2 60.4 18.0 0.12 0.06 0.14 May 638-942 7.7-7.9 59.7-74.5 68.4 20.1 < 0.05 < 0.05 0.14 June 790-948 7.6-7.8 69.4-82.4 75.7 17.4 0.15 0.07 0.15 July 790-948 7.6-7.8 76.8-88.5 83.4 16.2 0.06 0.07 0.13 Aug. 942-954 7.6-7.8 81.9-88.2 84.7 16.4 < 0.05 0.08 0.17 Sep. 334-948 7.6-7.9 65.1-86.4 75.1 9.3 0.11 0.06 0.18 Oct. 790-948 7.6-7.9 75.4-81.5 79.1 17.7 0.10 0.02 0.14 Nov. 790-942 7.6-7.9 64.8-81.3 73.9 18.8 0.15 0.03 0.14 Dec. 790-948 7.7-8.0 58.3-71.1 65.1 17.4 0.11 0.03 0.17 b). Number of NPDES exceptions during year2, Susp. Ibric oil &

pH h mp. FAC 1RC Sct IOff COff hydrazin/ acid nodud. lithium r,rvaw matals 0 0 0 0 0 0 0 0 0 0 0 1 0 i l

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' Parameters are measured at Unit 3 discharge (DSN 001C), except for TRC, which is measured l at MNPS discharge (quarry cuts; DSN 001) and SWS FAC (service water system; DSN 001C-5).

2 Some parameters are measured at more than one point within Unit 3 or only under certain operating conditions. Values represent number of NPDES exceptions for all discharge points; see text for additional details. j Wmpling for BOD, COD, and hydrazine is required only when discharging wastewater I containing hydrazine; these events did not occur during 1994.  !

l 1994 AEPPOR 4 l l

ATTACIIMENT 1 to the Millstone Unit 3 Environmental Protection Plan Annual Environmental Protection Plan Operating Report January 1 - December 31,1994 l

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1 Executive Summary i l

l Winter Flounder Studies Niantic River during 1994 were among the lowest I since sampling began in 1983. Abundances of Stage He local Niantic River population of the winter 3 and 4 larvae, however, were greater and above the flounder (Pleuronectes americanus) is potentially long-term average. Annual larval abundances in the affected by the operation of MNPS, par'icularly by bay since 1976 appeared to reflect region-wide trends, entrainment of larvae through the cooling-water 12cause they were highly correlated to abundance systems of the three operating units. As a result, indices for Mount Hope Bay, MA and RI.

intensive studies of the life history and population Larval developmental stage and length were closely dynamics of this valuable sport and commercial related. Smaller larval size-classes predominated in species have been undertaken since 1976. the river and larger size < lasses were more prevalent in  !

Because of heavy ice cover in the Niantic River in the bay. In Niantic Bay, growth and development l early 1994, the adult winter flounder survey did not were correlated with water temperature. In the river, I begin until March 22, the latest start in 19 years, and growth appeared to be related to both water temper-only 4 weeks of sampling were completed. The ature (positively) and larval density (negatively).

median trawl catch-per-unit-effort (CPUE) of fish Estimated mortality of larvae in the Niantic River for larger than 15 cm present during the spawning season 1984-94 ranged from about 82 to 985 Mortality was was 4.5. His value was more than twice the record consistently highest during Stage 2 of development )

low CPUE of 1.9 for 1993, but nonetheless remains (3- to 4-mm size-classes), which is when feeding first i as the second smallest CPUE for this time series. occurs. This stage may include a " critical period" for The Jolly stochastic model was used with mark and winter flounder as survival rates generally improve recapture data to estimate the absolute abundance of progressively for larger size-classes. Density-depen-the adult spawning population (all winter flounder dence was examined using a function comparing larger than 20 cm, which includes some immature mortality and egg production estimates. With 1993 fish). The most recent abundance estimate was data excluded, a significant positive relationship was 11,779 winter flounder for 1993, in contrast to apparent, such that when egg production and larval estimates between 33 and nearly 80 thousand fish for abundance increased, mortality also increased 1984-91. Young-of-the-year winter flounder have been About one-third to one-half of the winter flounder collected during late spring and summer at two sta-found in the Niantic River during the spawning period tions in the Niantic River since 1983. Corresponding each year are mature females. Annual female winter to late larval abundance, densities of newly meta-flounder parental stock sizes were estimated using morphosed young in 1994 were relatively high.

available information on sex ratios, age, and size Median densities for late summer were among the composition. These estimates have ranged from largest found in 12 years, with the 1994 year-class 7,821 (1993) to 78,629 (1982) spawning females, having the potential to be relatively strong.

with corresponding total egg deposition ranging from An index of abundance was calculated for young about 6.4 to 45.6 billion, winter flounder taken during the late fall and early Estimates of larval winter flounder abundance at the winter at the trawl monitoring program stations. The _.

MNPS discharge (entrainment sampling) have been 1993-94 abundance index (1993 year-class) was 7.4, obtained since 1976, at a station in mid-Niar. tic Bay the lowest recorded since 1987-88. Since 1983, when since 1979, and at three stations in the Niantic River comparative data were available, this abundance index sir.ce 1983. The low abundance of newly-hatched was significantly correlated with that of young fish larvae in Niantic Bay compared to the Niantic River taken in the Niantic River during summer. High suggested that most local spawning occurred in the indices for the 1988 and 1992 year-classes indicated river. In addition, abundance indices of Stage I larvae that these were relatively abundant year-classes. Few in the river were significantly correlated with juveniles were taken within the Niantic River during independent estimates of female spawner egg the adult spawning population surveys in recent years.

production. Abundance of Stage I and 2 larvae in the Young-of-the-year abundance indices were not Executive Summary v t __

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significantly correlated or were negatively correlated 22% and the estimated fraction of Niantic River winter with those for age-3,4, and 5 female adult spawners. flounder production that would have been entrained Thus, none of the early life stages were considered as under full (100% capacity) three-unit operation ranged reliable indices of year-class strength for Niantic River from 5.4 to 25.0% (geometric mean of 12.1%).

winter flounder stock. A computer simulation model (SPDM) was used for Egg production estimates from annual spawning long-term assessments of MNPS impacL Input data surveys were scaled to numbers of spawning females used by the model included basic life-table parameters, and used as recruitment indices. These indices the three-parameters of the SRR, February water together with adult female spawning stock estimates temperature statistics, and simulation parameters and mean annual February water temperatures were specific to each model run, including a random used to fit a three-parameter Ricker stock-recruitment variability component. Conditional mortality rates relationship (SRR). Additionally, the indirect esti- corresponding to postulated larval entrainment and mate of the winter flounder theoretical rate of increase juvenile and adult impingement at MNPS were (the SRR a parameter) derived by the Connecticut simulated according to historical information and Department of Environmental Protection (DEP) was projections. Fishing mortality rates (F) were provided used for modeling the dynamics of the winter flounder by the DEP. Initially, F was set at 0.40 and remained population for impact assessment purposes. The unchanged through the 1960s; increased gradually to value of a, re-scaled to units of fish numbers from 0.62 by 1988 and thereafter more rapidly to a maxi-biomass units, was estimated as 5.42 and described the mum of 1.30 in 1991. Based on proposed regulatory inherent potential for increase of the Niantic River changes, F was projected to decrease substantially winter flounder stock. The estimate of (the second through the late 1990s, dropping to 0.50 by 2001, and SRR parameter), which describes the annual rate of remaining unchanged through the rest of the simu-compensatory mortality as a function of stock size, lation years. The winter flounder stock was simulated showed little annual variation since 1988. The third as female spawner biomass (in Ibs), which is moa and last parameter in the SRR described a negative directly related to reproductive potential than fish relationship between winter flounder recruitment and numbers. Annual rates of Niantic River winter floun-water temperatures in February, the month when most der larval entrainment were based on actual or esti-spawning, egg incubation, and hatching occur. mated MNPS cooling-water flow and estimated or The number of larvae entrained through the projected entrainment as derived from mass-balance condenser cooling-water system at MNPS is the most calculations. All SPDM runs were stochastic and direct measure of potential impact on winter flounder, their output consisted of 100 Monte Carlo replicates Annual estimates of entrainment were related to larval for each yearly stock projection over a 100-year period densities in Niantic Bay, as well as to plant operation. (1960-2060).

The entrainment estimate for 1994 of 182.1 mi!! ion An initial stock size of 98,104 lbs was used to was about average since three-unit operation began in represent the theoretical (no fishing assumed) 1986. Unit I was shut down from January 15 maximum spawning potential (MSP) of the Niantic through May 23 because of a refueling outage. This River female spawning stock. When fishing effects decrease in cooling water use resulted in a calculated were simulated, the annual projections of the laitially reduction in entrainment of about 21% (48.1 million unfished stock become the baseline time series of larvae) from that expected if Unit I had operated annual spawning biomass for Niantic River winter during this period. flounder subjected to fishing, but in the absence of The impact of larval entrainment on the Niantic any plant impact. Under the exploitation rates simu-River stock depends upon the fraction of its produc- lated, the stochastic mean stock size of the baseline tion that is entrained each year. Empirical mass- declined to 49,476 lbs in 1970 and to its lowest point balance calculations for 1984-94 indicated that a large of 12,907 lbs in 1993. The latter value was about number of entrained larvae came from areas of Long one-half of a generally accepted critical stock size, Island Sound other than the Nir.ntic River. An esti- defined as 25% of MSP. Following simulated reduc-mated 14 to 38% of the larvae entrained at MNPS tions in fishing, however, the stock rapidly recovered.

appeared to have originated from the Niantic River dur- A new series of stock size projections were then ing these years. Percentages of the river production simulated by adding the effect of larval entrainment at ;

that were entrained annually ranged from about 5 to MNPS. He lowest projected stock biomass under

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simultaneous fishing and effects of MNPS occurred in mine the impact of MNPS on local fish assemblages.

1993 (10,947 lbs), whereas the greatest absolute Over 100 different fish taxa have been collected. Six decline relative to the baseline occurred in 2003 (a taxa (American sand lance, anchovies, grubby, difference of 7,026lbs). Generally,however, greater silversides, tautog, and cunner) were identified that reductions in stock biomass resulted from fishing than were potentially impacted by MNPS, either by from larval entrainment, because fishing tends to entrainment of their eggs and larvae or by exposure to remove larger fish and reduce average weight of the elevated seawater temperatures.

remaining spawneu. The simulated spawning stock Abundance data were analyzed separately for two-returned to within 1,000 lbs of baseline levels (44,000 unit (1976-1985) and three-unit (1986-1994) opera-Ibs, or 45% of MSP) about 6 years after the scheduled tional periods and for the entire 18-year data series termination of Unit 3 operation in 2025. (both periods combined) to determine if changes in The probabilities that the Niantic River female abundance have occurred. For the potentially impacted spawning stock biomass would fall below selected fishes, declining abundance trends wem found for some reference sizes (25,30, and 40% of MSP) were deter- life stages in four (American sand lance larvae, mined to help assess the long-term effects of MNPS Atlantic silverside juveniles, tautog eggs, and cunner operation. A stock smaller than 25% of MSP is and tautog adults) of the six taxa. Because many considered overfished, whereas one that is at 40% of factors may affect the abundance of these taxa the MSP can maximize yield to the fisheries while reasons for these declines were difficult to ascertain.

remaining stable. For both baseline and MNPS- American sand lance larvae ranked third among fish impact simulations, it was likely (p 2 0.95) that the larvae entrained and have significantly decreased in stocks were greater than 40% of MSP in 1970. At abundance in entrainment samples. Decreases in sand the lowest point of both stock projections in the mid- lance abundance were also apparent in other areas of 1990s, all replicates were less than 25% cf MSP. the Northwest Atlantic Ocean. Their abundance was Simulated reductions in fishing allowed for a rapid noted to have been inversely correlated with that of increase in spawner biomass in 2000. By 2010, the Atlantic herring and Atlantic mackerel. Given the stocks had a high (p 2 0.95) likelihood of being large abundance changes of this species along the greater than 30% of MSP and the impacted stock had a Atlantic coast, effects of MNPS operation on sand better than even chance of being greater than 40% of lance were difficult to quantify. The bay anchovy is MSP. 'Ihis recovery, however, assumed that changes typically the most abundant ichthyoplankton species in fishing regulations would be implemented as collected in estuaries within its range and it was the scheduled and that they achieved expected reductions in dominant larval taxon entrained at MhTS. Egg and fishing mortality. Even with reductions in fishing larval densities and entrainment estimates for 1993 mortality, there still was a 34% chance that the new were within the historic range. Similar to the sand equilibrium stock biomass would remain smaller than lance, this fish also exhibits large natural abundance 40% of MSP. fluctuations. Along the coast of Connecticut, the Atlantic silverside and the inland silverside are among Fish Ecology Studies the most common shore-zone species. Typical of short-lived species, the catches of Atlantic silverside by trawl and seine were highly variable and annual Studies of fish assemblages inhabiting the area

. catch indices ranged over two orders of magnitude.

around MNPS were conducted to determme the effects The catches of Atlantic and inland silversides in seine of station operations. These effects have been defined samples were all within historic ranges and were as power-plant related changes in the occurrence, greater than the two-unit period average, except for the distribution, and abundance of fish species which Atlantic silverside at the Jordan Cove station. Unlike could affect community structure. Fish assemblages several other potentially impacted fishes, the grubby could be adversely affected by losses due t experiences no fishing pressure. Both larval and adult impingement of juvemic and adult fish on the mtake grubby abundance indices were stable throughout the screens, entramment of fish eggs and larvae through 18 years of monitoring. The tautog was the second-the cooling water system, or by changes m thermal most abundant egg taxon entrained and accounted for regime or physical habitats.

more than 30% of the total eggs collected since 1979.

Since 1976, trawl, seine, and ichthyoplankton During the three-unit operational period there was a monitoring programs have been conducted to deter.

Executive Summary vii

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I significant negative trend in the densities of tau'.og 3/16 in) to 81.8 mm (3 7/32 in); minimum size was eggs. Ilowever, larval densities were within the increased again in 1990 to 82.6 mm (3 % in).

historic range. Trawi catches of adult tautog exhibited Because of the regional economic importance of l a highly significant negative slope for the 18-year data lobsters, adult lobsters have been monitored from May series. Young-of-the-yeartautogaccountedforahigh through October since 1978 using wire lobster traps proportion of the fish caught in the trawl since three- set at three stations around MNPS; additionally, since unit operation began. The cunner was the most 1984, studies have been conducted during the hatching abundant egg taxon entrained and accounted for more season to estimate the number of lobster larvae than 50% of all eggs collected since 1979. The den- entrained through cooling water systems. He objec-sity of cunner eggs in 1993 was within the historic tive of the lobster monitoring program is to determine range, and the 1993 egg entrainment estimate was the if operation of MNPS has caused changes in local highest since the three-unit operational period began. lobster abundance beyond those expected from natural The densitics of larvae were low, but were within the variability and high fishing mortality rates.

range of previous values. Comparable to tautog, ne total number of lobsters caught and total catch ,

young-of-the-year cunner accounted for a higher propor- per unit effort (CPUE) in our study area reached record tion of the fish caught in the trawl since three units levels n 199-2 and remained high during 1993 and began operating. 1994. liowever, legal lobster catches (those indiv-Entrainment of wrasse (cunner and tautog) eggs was iduals 2 82.6 mm carapace length) have significantly identified as the primary potential impact to these declined since the NUSCO study began in 1978.

fishes because over 85% of the eggs entrained at Legal catches were expected to improve in 1993 and MNPS were of these species, ne spatialdistribution 1994 after large numbers of lobsters, observed to be of wrasse eggs was studied in 1994. Results indicated just below legal size in the 1992 and 1993 catches, that these eggs were not concentrated near MNPS molted to legal size. Instead, legal CPUE has intakes, but were representative of a more homo- continued to decline the past 2 years,in contrast with genous distribution, including areas outside Niantic recruitment patterns observed in previous studies when '

Bay. This apparent widepsread standing stock of strong recruit classes were followed by an increase in tautog and cunner eggs in the MNPS area would legal catches one to two years later. The fact that minimize any impact from entrainment loss. CPUE of legal-sized lobsters continued to decline despite the strong recruit classes observed since 1992 Lobster Stud,es i may be further evidence that the local lobster resource is currently overfished.

One of the most valuable species in the Connecticut During 1994, the pe.m in number of molting fishing industry is the American lobster (Homarus lobsters was later, and growth per molt was lower americanus). Annual Connecticut landings of 0.8 to than previously oberved in our studies; these 2.7 million pounds yielded between $2.4 and 8.4 conditions were attributed to below normal water million to lobstermen employed in the fishery. temperatures during spring 1994. Changes observed Lobsters are highly exploited throughout their range n the size structure, sex ratio, and proportion of and the fishery is almost completely dependent on new berried females of local lobsters may be primarily due animals molting into legal size each year. In Long to increased fishing rates and to impicmentation of Island Sound (LIS), more than 90% of all the lobsters new fishery regulations. During three-unit studies, above the minimum legal size are removed by fishing. the incidence of claw loss was lower, and recapture Over the past decade, the lobster fishery has become rates and size structure of tagged lobsters caught by highly regulated in an effort to reduce fishing NUSCO and commercial lobstermen were inconsistent mortality rates and to increase larval production and w th results observed during two-unit studies. These subsequent recruitment. Since 1984, Connecticut changes were attributed to the implementation of the lobstermen have been required to install escape vents escape vent regulation in 1984. The percentage of in traps; the escape vents allow sublegal-sized lobsters berried females collected nearly doubled during three-to escape from traps and thereby reduce injury and unit studies and was probably related to regulations mortality to this portion of the population. The nereasing the minimum legal size. He new regula-minimum legal size (carapace length) of lobster was tions implemented to sustain the lobster resource by increased in Connecticut in 1989 from 81.0 mm (3 improving lobster survival appeared to be effective.

viii Monitoring Studies,1994 l

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l However, fishing effort continues to escalate and after Unit I retubing in 1993 may result in future fishery managers question the long-term stability of declines of the T. bartschi population within the the resource under that kind of fishing pressure. effluent quarry.

The density of lobster larvae collected in samples of the MNPS cooling water was higher during three-unit Eelgrass studies due to the higher percentage of berried females.

Estimates of the total number of larvae entrained at Eelgrass studies during 1994 monitored three MNPS were also higher during three-unit studies due populations in the Millstone area: Jordan Cove (JC),

to a combination of higher larval densities and higher White Point (WP) and the Niantic River (NR).

cooling water demand of Unit 3. He potentialimpxt Results from 1994 indicated generally poor regional of higher larval entrainment on subsequent legal conditions for growth and reproduction of these local lobster abundance is difficult to assess because of the populations. Population parameters at WP measured ,

uncertainty that exists concerning larval origin, larval in 1994 were relatively low, but still within ranges survival, and recruitment rates to legal size. However, established over the previous 9 study years. The the high total CPUE for lobsters in our area over the deeper wate WP study site provides more protection past 3 years suggests that entrainment during the against elevated temperatures from insolation in the initial years (1986-88) of three-unit operation has not summer, sediment freezing during low tides in winter, adversely affected the local adult population. and swan grazing. E ! grass populations at shallow water sites are more susceptible to these stress Marine Woodborer Study mechanisms. Overall environmental stress was apparently greatest at NR in 1994, and was related to The Marine Woodborer Study report describes the regional and site-specific (depth-related) factors, and local distribution of Teredo bartschi, a semitropical possibly water quality conditions in the Niantic River, shipworm common from Texas to South Carolina, Zostera populations were elimination at NR by but not found farther north except in close proximity September 1994. Similar localized elimination events to nuclear power plants in New Jersey and have been observed at other sites in the Niantic River Connecticut. Consistent recruitment and survival of in 1986 and 1993, indicating an overall long-term Teredo bartschi has been observed in MNPS discharge population decline in the Niantic River during the waters from 1975 to 1994. Within the effluent study period. This population is at its lowest level quarry, high recruitment of T. bartschi was again since studies began in 1985, in terms of abundance observed in 1994, primarily in panels on the western and distribution, and now consists of only small side. This finding was consistent with the previous isolated patches.

Exposure Panel Studies and Distribution Studies Shallow-water stress, as temperature extremes, were conducted since 1975. Outside the effluent quarry, T. measured directly at JC, and may have contributed to bartschi remains closely associated with discharge population declines observed at that site. Sediment waters, with highest recruitment at the quarry cuts freezing likely occurred during two extreme low tide (undiluted effluent). Recruitment decreased substan- events in the winter of 1993-94. Although hydro-tially with distance from the outfall; in 1994, thermal modeling studies indicate some thermal plume relatively few individuals were found in panels 100 m incursion to JC, elevated temperatures measured at JC from the quarry cuts and none were found at sites 500 during the summer appeared more related to insolation m away. Sampling sites 500 m from the quarry cuts of the shallow sand flats in Jordan Cove than to appear to be near the limit of suitable thermal thermal plume incursion. Large-scale decline / recovery conditions for T. bartschi recruitment; several cycles in Zostera populations throughout North individuals recruited onto panels there in 1993, America and Europe have been observed since the although none were collected in 1994. T. bartschi has 1930s and attributed to disease and eutrophication. In not expanded its occurrence to other areas in Long particular, populations on the cast coast North Island Sound unaffected by MNPS discharge. America, including Long Island Sound, have been Although present in MNPS discharge waters for over declining steadily since the 1960s. It is likely that 20 years, this species has not adapted to near-ambient population declines at JC and other sites in the or ambient temperature conditions outside the effluent Millstone area are part of this regional trend, and not quarry. Furthermore, discontinued use of woodchips the result of MNPS operation.

Executive Summary ix

Rocky Intertidal Studies station nearest the discharge (FN) caused Ascophyllum to grow longer and more rapidly at this site, relative )

Rocky intertidal studies in 1994 charactenzed nearby to stations farther away. A moderate level of growth 1 shore communities impacted by the MNPS thermal enhancement was observed at FN during 1993-94, I plume, as well as those farther away and unimpacted. when compared to previous years, attributed to Conditions resulting in much of the variability among lessened thermal plume incursion resulting from an communities at sampling sites outside the influence extended outage of Unit 3 for much of the peak of MNPS were related to natural factors including site growing season. As in previous years, Ascophyllum i orientation to prevailing wind-generated waves, the mortality, or loss of tagged plants and tips, at our ability of available substratum (slope) to dissipate the present sampling sites was not related to proximity to horizontal force of those waves, and the character of the power plant but rather to degree of exposure to that substratum (e.g., boulders, bedrock ledge, etc.), stonn forces.

Community differences beyond those attributed to natural factors occurred within the thermal plume area Benthic Infauna at sites located on Fox Island (FE and FN), and were directly attributed to MNPS operation. Various Benthic infaunal studies during 1994 continued to aspects of the impact-related community changes at monitor subtidal soft-bottom habitats in the vicinity Fox Island were identified through separate studies of MNPS for power plant-related changes in which included qualitative algal sampling, estimations sedimentary characteristics and infaunal community of intertidal organism abundance, and studies of local structure (total abundance, species number, and species i Ascophyllum nodosum populations. composition). The top four most dominant taxa at  !

Elevated temperature conditions caused by the three- each station in 1994 accounted for more than 60% of  ;

unit thermal plume allowed development of a unique all individuals collected. These were: Oligochaeta, flora at FE. The most notable shifts in species Protodorvillea gaspeensis, Tellina agilis, and occurrence, revealed by qualitative algal sampling, Archiannelida at EF; Oligochaeta, Tharyx spp.,

were the presence of warm water-tolerant species not Afediomastus ambiseta, and Protodorvillea gaspeensis typical of other sites (Agardhiella subulata, Gracilaria at GN: Aricidea catherinae, Oligochaeta, hiediomastus likvahiae, and Sargassum filipendula), absence of ambiseta, and Tellina agilis at IN: and biediomastus common cold water species (Afastocarpus stellarus, ambiseta, Aricidea catherinae, Oligochaeta, and Tharyx Dumontia contorta, and Polysiphonia lanosa) and spp. at JC. In most cases, these organisms were extended or reduced periods of occurrence of seasonal dominant taxa in both two-unit and three unit species with warm water or cold water affinities, operational periods. Most stations were characterized respectively. by one or more clearly dominant taxa (oligochaetes at During 1994, power plant impacts on dominant EF, GN, and JC, Aricidea catherinae at GN and JC, species abundance patterns, caused by two-cut water and Tharyx spp. at GN) during both operational circulation patterns and by three-unit operations, were periods. There has been no single dominant taxon at observed only at FE, and were most pronounced in the IN during either operational period, where mean low intertidal, where temperature conditions were relative abundance of any single taxon rarely exceeded most severe. The low intertidal community at FE, 10% The control site at GN continues to exhibit which prior to 1983 had been unimpacted and stability in terms of the sedimentary environment and characterized by perennial populations of Fucus, infaunal community structure. Some stability in Chondrus, and Ascophyllum and predictable seasonal these parameters has also been noted in recent years, peaks in barnacle and Afonostroma abundance, has including 1994, at sites impacted by short-term been replaced by a persistent community dominated by episodic disturbance events (e.g., dredging and Codium, Ulva, Enteromorpha, and Polysiphonia. construction activities at IN, and siltation at JC).

Also, populations of species observed in undisturbed Community recovery is ongoing, but is not complete transects only at FE (Sargassum, Gracilaria) continued at either site. Effluent scour at EF remains a to persist and expand during 1994. dominant structuring factor on both the sedimentary Ascophyllum populations at three stations in the environment and infaunal community, and is expected vicinity of MNPS continued to be monitored in 1993. to continue throughout MNPS three-unit operation.

Elevated temperatures (2-3*C above ambient) at our x Monitoring Studies,1994 1

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r I ATTACHMENT 2 to the Millstone Unit 3 Environmental Protection Plan Annual Environmental Protection Plan Operating Report January 1 - December 31,1994 I

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