B15661, Annual Environ Protection Plan Operating Rept

Annual Environ Protection Plan Operating Rept

ML20108D851
Person / Time
Site:	Millstone
Issue date:	12/31/1995
From:	Brothers M, Foertch J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES SERVICE CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B15661, NUDOCS 9605090084
Download: ML20108D851 (15)

Text

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. Northeast Utilities System sonhc. utihtie. se company P.O. Box 270 liarJord, cT 06141-0270

,. (203) 665-5000 APR 261996 I Docket No. 50-423

-B15661 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 l l

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References:

1. Environmental Protection Plan l (Nonradiological) Appendix B to Facility Operating License NPF-49, Millstone Nuclear Power Station, Unit No. 3, Northeast Nuclear 4 Energy Company, Docket No. 50-423. l

2. NPDES Permit No. CT0003263, Millstone Nuclear Power Station, Northeast Nuclear . Energy Company, renewed December 14, 1992.

Millstone Nuclear Power Station, Unit No. 3 1995 Annual Environmental Protection Plan Operating Beport i

Section 5.4.1 of the Environmental Protection Plan (EPP), Reference 1, requires that Northeast Nuclear Energy Company submit an Annual l

Environmental Protection Plan Operating Report to the NRC,

-describing implementation of the EPP for the previous year. The attached report fulfills this requirement for 1995.

Should you have any questions or require further information, please call Mr. James Foertch, Northeast Utilities Service Company

- Aquatic Services Branch, at (860) 447-1791 ext. 5055.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY N

l M. H. BI'o'thers Director - Millstone Unit No. 3 l

cc: w/o attachment 2 S. J. Holbrook, Commissioner, CT DEP T. T. Martin, NRC Region I Administrator l V. L. Rooney, NRC Project Manager, Millstone Unit No. 3

A. C. Cerne, NRC Senior Resident Inspector, Millstone Unit No. 3 l 090038 9605090084 951231 V \

PDR ADOCK 05000423 R PDR I osse uv. t.n (

Docket No. 50-423

' B15661 i

I Attachment Millstone Nuclear Power Station, Unit No. 3 1995 Annual Environmental Protection Plan Operating Report l

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April 1996

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Annual Environmental Protection Plan Operating Report January 1 - December 31,1995  ;

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Millstone Unit 3 Environmental Protection Plan ,

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i Prepared by: Jim Foertch Reviewed by: Milan Keser

Annual Environmental Protection Plan Report - 1995

1. Introduction 1

This report covers the period January 1 - December 31,1995. From April to June 1995, Unit 1 3 was shut down for its fifth refueling outage. An additional outage occurred for a two week period in December to repair a check valve in the reactor coolant system. The Unit remained at full power (nominal 1150 MWe) for the remainder of the year. During 1995, Unit 3 operated at an annual capacity factor of 81%

1 As required by the Millstone Unit 3 EPP, this Annual Environmental Protection Plan Operating i J

Report (AEPPOR) includes-1

1) summaries and analyses of the results of environmental protection act vities,

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 i

4) a list of non-routine repons, describing events that could result in significant environmentalimpact. l

2. Environmental Protection Activities 2.1 Annual National Pollutant Discharge Elimination System (NPDES) Report of Ecological Monitoring (EPP Section 4.2)

Paragraph 5 of the referenced NPDES permit requires continuation of biological studies of Millstone Nuclear Power Station (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 1995, Monitoring the Marine Environment of Long Island Sound at Millstone Nuclear Power Station. Waterford. Connecticut - Annual Reoort.1995, 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 entrainment, causes sediment scouring near the MNPS discharges, and alters the characteristics of thermal effluent plume. The biological effects of these changes are summarized in the Executive Summary section of the above-named report (Attachment 1) and funher discussed in the report itself(Attachment 2).

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i 2.2 Efiluent 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 monitoring 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 Report. includes data from all three Millstone units. Those data that pertain to Unit 3 are summanzed in Table la. During j 1995, no NPDES exceedances or exceptions were reported from a discharge associated with Unit 3 (Table Ib).

Sampling for hydrazine (N2H4), 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  ;

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following wet lay-up of steam generators during extended outages; during 1995, these discharges occurred in May and June. The maximum hydrazine concentration j measured at DSN 001C-1a was 40.0 mg/L (permit limit 125 mg/L). l

3. Environmental Protection Plan Noncompliances During 1995, no EPP noncompliances were identified for Unit 3.

4. Environmentally Significant Changes to Station Design or Operation During 1995, 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 72 PDCRs initiated during 1995, none involved unreviewed enviroranental issues. One PDCR (3-95-058 l ARCOR Coating of Large Bore Sersice Water Piping) required an Environmental Review, but this Review determined that no unreviewed environmental issue was involved. Another PDCR (3-95-056 RFO6 Service Water Piping Modifications) was reviewed in early 1996, and this Environmental Review also determined no unreviewed environmental impact.

As of December 31,1995, Unit 3 has 190 System Operating Procedures; of these, 84 were added or revised during 1995. In addition, many procedures were modified to 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 was determined to have involved an unreviewed environmental impact. Additionally, a review of design and system changes that had been initiated in previous years, but had an Environmental Review performed in 1995, indicated that none constituted an unreviewed environmental issue, per the EPP criteria.

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. 5. Non-Routine Reports ofEnvironmentally Significant Events During 1995, no events occurred at Unit 3 that met the acceptance criteria for inclusion 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 22 events that constituted reportable occurrences in 1995, none were determined to cause a significant environmental impact. One LER (3-95-011-00 Mussels in the Recirculation Spray Heat Exchanger) noted that the possibility of recurrence was greatly reduced by the installation of more reliable sodium hypochlorite metering pumps, but chlorine injection was regulated to ensure that discharge concentrations (FAC and TRC) remained within NPDES permit limits, ,

so no environmental impact occurred.

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Table 1. Millstone Unit 3 NPDES Data Summary, Jan.1 - Dec. 31,1995.

a). Selected water quality parameters for Unit 3' discharge discharge discharge discharge avg max max SWS flow range pH range temp. range temp. (avg) _T FAC TRC FAC (10' gpm) ' ("F) ' ( F) (*F) (ppm) (ppm) (ppm)

Jan. 790-948 7.8-7.9 56.8-65.5 60.6 17.0 0.13 0.04 0.17

.Feb. 790-942 7.8-8.0 48.0-60.8 55.9 17.6 0.12 0.03 0.17 Mar. 790-942 7.8-8.0 50.0-61.9 57.6 17.5 0.12 0.03 0.18 Apr.30-948 7.7-7.9 43.9-63.1 52.4 7.5 0.12 0 06 0.14

' May 15-942 7.6-8.0 46.0-57.0 51.8 0.1 0.15 0.03 0.22 June 790-942 7.5-8.0 54.7-82.0 72.1 13.4 0.12 0.07 0.17-July 790-948 7.6-7.9 79.7-88.7 83.9 18.0 0.12 0.06 0.19 Aug. 790-948 7.7-7.9 84.2-91.0 87.1 17.6 0.13 0.04 0.17 Sep. 0-948 7.6-7.9 83.1-89.1 86.2 18.0 0.10 0.02 0.16 Oct. 790-948 7.5-8.0 73.9-88.2 81.6 17.4 0.14 0.02 0.16 Nov. 790-948 7.7-8.0 48.2-80.I 71.9 17.3 0. I1 <0.02 0.19 Dec. 334-942 7.8-8.0 41.4-63.1 52.8 9.5 0.13 0.05 0.17 i

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b). Number of NPDES exceedances or exceptions during year ,

Susp. Ikric oil &

pH temp. FAC TRC Sol. IlOD 8COD' hydrazine' acid conduct. lithium grease metals other C 0 0 0 0 0 0 0 0 0 0 0 0 0

' Parameters are measured at Unit 3 discharge (DSN 00!C), except for TRC, which is measured at MNPS discharge (quany cuts; DSN 001) and SWS FAC (service water system; DSN 001C 5).

'Some parameten are measured at more than one point within Unit 3 or only under certain operating conditions. Values represent number of NPDES exceedances or exceptions for all discharge points; see text ror additional details.

' Sampling for DOD COD. and hydrazine is required only when discharging wastewater containing hydrazine; the nujor releases in 1995 occurred only in May and June.

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Attachment 1 to the Millstone Unit No. 3 Annual Environmental Protection Plan Operating Report January 1 - December 31, 1995 l Executive Summary i

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e Executive Summary Lobster Studies percentages of lobsters missing one or both claws (culls) during three-unit operation.

Several aspects of MNPS operation could impact The total estimated number of lobster larvae the local population of American lobster (Homarus entrained through the MNPS cooling water systems americanus). Early life stages of lobster (larvae) are during 1995 was the highest reported since entrain-planktonic and susceptible to entramment through ment studies began in 1984. De higher density of cooling water systems, while adult and juvenile lobster larvae in 1995 may be due to increased abun-lobsters can be impinged on intake travelling screens dance of berried females resulting from increases in or exposed to the heated effluent in the discharge area. minimum legal size. Entrainment levels have been Because of the regional economic value of the substantially higher during three-unit operation than Connecticut lobster fishery ($2-8 million annually) during two-unit operation, due to the additional and the ecological importance of this species, adult cooling-water demand of Unit 3. The potential effect lobsters have been monitored annually from May of higher larval entrainment on subsequent legal through October since 1978 using wire lobster traps lobster abundance is difficult to assess because of the set at three stations around MNPS. Additionally, uncertainty concerning the source of entramed larvae since 1984, studies have been conducted during the and their survival rates and recruitment to legal size.

hatching season to estimate the number of lobster larvae entrained through cooling-water systems. The Marine Woodborer Study objective of the lobster monitoring program is to determine if operation of MNPS has caused changes in Teredo bartschi remains present in MNPS discharge local lobster abundance beyond those expected from waters. However, in 1995, this shipworm was col-natural variability and high fishing pressure. lected at only one site (EW), while it had been found Legal-sized lobster abundance (catch-per-unit-effort; at three sites in 1994 (QC, EB, and EW) and in 1993 CPUE) has significantly declined since MNPS lobster (QC, EB, and HR). This trend indicates that distrib-studies began in 1978. His decline is attributed to ution of T. bartschi has decreased in the MNPS increased fishing rates, which have more than doubled discharge mixing area, and the current population is since 1978, and more recently, to the increases in now confined to undiluted discharge waters. Teredo minimum legal size. Total CPUE in 1995 was the bartschi occurs in MNPS water by virtue of higher lowest value observed in 10 years of three-unit oper- water temperatures than those normally found in Long l ation. This decline in total CPUE in 1995 may lead Island Sound. Although a population has persisted in i to even lower legal catches in 1996, as fewer sublegal- the MNPS Quarry since 1975, there is no evidence to sized lobsters are available to molt into legal size. suggest that T. bartschi has extended its occurrence to Lobster catches and molting peaked earlier during other areas in Long Island Sound unaffected by the three unit studies (1986-95) than during two-unit MNPS discharge.

studies (1978-85), probably owing to regionally warmer May to August water temperatures observed in Rocky Intertidal Studies l recent years; water temperatures in 1995 were among the highest recorded in these studies. Other changes in Occurrence and abundance patterns of plants and local lobster population characteristics during three- animals on intertidal rock surfaces are sensitive to a unit operation were related to implementation of new variety of environmental factors. In the Millstone fishery regulations, rather than to power plant area, the degree of influence of each of these factors impacts. He increased proportion of berried females varies both spatially and temporally, with most of the is associated with the increases in minimum legal differences among local communities attributed to sizet larval production should increase as a larger natural variability in site orientation to prevailing proportion of females are able to spawn before wind-generated waves, the ability of available reaching legal size. Similarly, implementation of the substratum (slope) to dissipate the horizontal force of escape vent regulation in 1984 has led to lower those waves, and the character of that substratum Executive Summary v

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l (e.g., boulders, bedrock ledge). Rocky intertidal extended outage of Unit 2 for much of the peak studies in 1995 also characterized nearby shore growing season. As in previous years, Ascophyllum communities impr.cted by the MNPS thermal plume. mortality or loss of tagged plants and tips at present Community differences beyond those attributed to sampling sites was not related to proximity to natural factors were observed at sites located on Fox MNPS, but rather to degree of exposure storm forces.

Island (FE and FN), and were directly attributed to MNPS operation. Various aspects of the impact- Eelgrass l related community changes at Fox Island were l identified through separate studies which included During 1995, eelgrass (Zostera marina) populations

' l qualitative algal sampling, estimations of intertidal were monitored at three sites in the vicinity of organism abundance, and studies of local MNPS; Jordan Cove (JC), White Point (WP), and the l l Ascophyllum modosum populations. Niantic River (NR). The JC and WP sites have been I The unique algal flora at FE, developed under sampled since 1985, while the NR station has been elevated temperature conditions caused by the three- changed several times since 1985, including during unit thermal plume, continued to be evident in 1994- 1995, because of declines in the overall abundance of l 95 based on qualitative sampling. The most notable eclgrass in the Niantic River.

l shifts in species occurrence at FE, relative to De two ec1 grass populations near MNPS (JC and l unimpacted sites, were the presence of warm water- WP) exhibited improved productivity in 1995, tolerant species not typical of other sites, absence of compared to the previous 3 years, while the overall common cold water species, and extended or reduced health of the Niantic River population continues to be periods of occurrence of seasonal species with warm poor. The celgrass population at WP appeared to be l water or cold water affinities, respectively, the most robust in MNPS area. Population param-l Impacts on dominant species abundance patterns, eters at WP (standing stock, shoot abundance and

! caused by two-cut water circulation patterns and by shoot length) were within the ranges established over three-unit operation, were observed only at FE, and the previous ten years. The deeper water at WP (>2 m l were most pronounced in the low intertidal, where depth) provides more protection against elevated j temperature conditions were estreme. The low inter- temperatures from insolation in the summer, sediment I

tidal community at FE, which prior to 1983 had been freezing during extreme low tides in the winter and unimpacted and charactenzed by perennial populations waterfowl grazmg.

of Fucus, Chondrus and Ascophyllum and predictable Ecigrass populations at shallow water sites (NR and i seasonal peaks in barnacle and Monostroma abun- JC, s 1 m depth) are more susceptible to these stress l dance, has been replaced by a persistent community mechanisms. Overall environmental stress was l dominated by Codium, Ulva, Enteromorpha, and greatest in the Niantic River. Zostera populations l Polysiphonia. He FE community during 1995 was experienced localized elimination in the Niantic River somewhat atypical when compared to recent years of in 1986,1993, and 1994. He reasons for this long-three-unit operation. Codium, Polysiphonia, and tenn decline are unclear. However, because this site is barnacle populations were relatively low, likely well beyond any influence of MNPS, the decline is influenced by a heavy and persistent mussel set, not related to power plant operation, but rather to These mussels were eliminated by Autumn 1995, so natural site-specific factors, such as grazing, water l this minor change is probably short lived. More quality, and habitat degradation in the Niantic River.

similar to recent years, populations of species While analyses of population characteristics observed in undisturbed transects only at FE indicated a population decline at JC over the 11-year (Sargassum, Gracilaria) continued to persist and study period, moderate improvement was observed in expa id during 1995. 1995. The eelgrass population in JC may also exper-

. Elevated temperatures (2-3*C above ambient) at the ience shallow-water related stress, such as temperature l Ascophyllum station nearest the discharge (FN) caused extremes. Dese extremes have been measured directly plants to grow longer and more rapidly at this site, at JC in summer and were possibly responsible for relative to stations farther away. A moderate level of periodic population declines observed previously at growth enhancement was observed at FN during 1994- that site. However, elevated summer temperatures at

95, when compared to previous years, attributed to JC were mainly related to insolation of the shallow l lessened thermal plume incursion resulting from an sand flats in JC than to thermal plume incursion.

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Benthic Infauna deposited silt / clay was still evident after 1995

. sampling, and community recovery is evident but Construction and operation of MNPS has impacted slow at JC.

some nearby soft. bottom benthic infaunal Discharge scour continues to impact the communities. Benthic infaunal studies during 1995 sedimentary environment and the infaunal community .

continued to document ongoing changes related to at EF. Sediments in 1995 were characterized by those impacts by monitoring subtidal soft-bottom increased sediment grain size and decreased silt / clay habitats in the vicinity of MNPS for changes in levels relative to two-unit operational years. The  ;

sedimentary characteristics and infaunal community infaunal community at EF has developed under the structure (total abundance, species number and species new, relatively stable, high current conditions in the composition). Results of these studies indicate that discharge area. Populations of species common impact-related community changes continue to be during two-unit operation (e.g., A. catherinae and P.

observed at three of four study sites through the 1995 eximius) have returned to EF, while other species sampling year. (including Tharyx spp.) have declined or do not occur De GN reference site, located well beyond the even during periods of arca-wide increase (e.g., M.

influence of MNPS, continued to reflect long-term ambiseta). This new infaunal community at EF is physical and biological stability; sediments collected expected to persist until the degree of sediment scour at GN in 1995 were similar to previous years, and produced by the MNPS discharge changes.

overall community composition was consistent over the study period. Specifically, the same four taxa Winter Flounder Studies (oligochaetes, Tharyx spp., Aricidea catherinae and Mediomastus ambiseta) have been numerical The local Niantic River population of winter dominants at similar relative abundance levels over flounder (Pleuronectes americanus) is potentially both two-unit and three-unit operational periods, affected by the operation of MNPS, particularly by At two sites near the power plant (IN and JC), entrainment of larvae through the cooling-water impacts have resulted from isolated physical systems of the three operating units. As a result, disturbances that occurred over a relatively short intensive studies of the life history and population duration (months or a few years). Community dynamics of this valuable sport and commercial changes were detected earliest at IN, and were species have been undertaken since 1976.

attributed 80 dredging and cofferdam removal during Although monthly mean seawater temperatures Unit 3 construction (1983-85). In subsequent years, recorded at the MNPS intakes from November 1994 sediment silt / clay content has declined to near pre- through April 1995 were either the warmest or second impact levels and indications of community recovery warmest recorded during the past 20 years, mid-winter are evident through 1995. Species richness and cold weather produced heavy ice cover in the Niantic .l' abundances of oligochaetes and Aricidea catherinae River, delaying the start of the adult winter flounder (common taxa prior to 1983) have increased in recent survey until February 28. The median trawl catch-per-years, while abundances of more opportunistic species unit-effort (CPUE) of fish larger than 15 cm during (e.g., Nucula proxima) have declined. However, the spawning season was 2.1, which only exceeded the continued dominance of post-impact species, such as record low CPUE of 1.9 for 1993. The Jolly i Tharyx spp., indicates the recovery is still ongoing at stochastic model was used with mark and recapture i' IN. data to estimate the absolute abundance of the adult Siltation at JC occurred in 1986 after the start-up of spawning population. The abundance estimate for l Unit 3, and was associated with increased cooling. 1994 was 13,037 winter flounder, similar to estimates I of about 10-16 thousand for 1992 and 1993, but water flow and sediment scour in the immediate area of the discharge. Abundances of the previously considerably less than estimated population sizes dominant oligochaetes, and the polychaetes Polycirrus between 33 and 80 thousand spawners during 1984-91.

eximius and Aricidea catherinac quickly decreased. Between one-third to one-half of the winter flounder The impact of this siltation event has apparently found in the Niantic River during the spawning period lessened since 1986, as populations of some two-unit each year have been mature females. Female spawner period dominants (e.g., A. catherinae) have recovered. abundance estimates have ranged from 5,749 (1995) to However, long-term persistence of some of the 74,421 (1982), with corresponding total egg produc.

Executive Summary vii

tion from about 4.5 to 42 billion each year. strength for Niantic River winter flounder stock.

The low abundance of newly-hatched larvae in Egg production estimates from annual spawning Niantic Bay compared to the Niantic River suggested surveys were scaled to numbers of spawmng females that most local spawning occurred within the river. In and used as recruitment indices. These indices, addition, abundance indices of Stage I larvae in the together with adult female spawning stock estimates river were significandy correlated with independent and mean annual February water temperatures, were estimates of female spawner egg production. Egg used to fit a three-parameter Ricker stock-recruitment i hatchability was relatively good in 1995, although relationship (SRR). Additionally, an indirect estimate abundances of Stage 1 and 2 larvae in the Niantic of the winter flounder theoretical rate of increase (the River were only about average. However, abundancas SRR a parameter) was used for modeling winter floun.

of Stage 3 and 4 larvae during 1995 were among the der population dynamics for impact assessment. The highest observed since 1983. Annual larval abun- value of a in biomass units was estimated as 5.95.

dances in the bay since 1976 appeared to reflect Ec estimate of (the second SRR parameter),which region-wide trends as they wem highly correlated with describes the annual rate of compensatory mortality as abundance indices for Mount Hope Bay, MA and RI. a function of stock size, has shown little annual Smaller larval size-classes prMarninarad in the river variation since 1988. He third parameter in the SRR and larger size-classes were mose prevalent in the bay. described a negative relationship between winter In Niantic Bay, growth and development were flounder recruitment and water temperatures in correlated with water temperature. In the river, growth February, the month when most spawning, egg appeared to be related to both water temperature incubation,and hatching occur.

(positively) and larval density (negatively). Growth The number of larvac entrained through the and development were especially fast in 1995, likely condenser cooling-water system at MNPS is the most due to the warm water temperatures. Estimated direct measure of potential impact on winter flounder.

mortality of larvae in the Niantic River for 1984-95 Annual estimates of entrainment were related to both ranged from about 82 to 98% and was 88.3% in 1995. larval densities in Niantic Bay and plant operation.

Density-dependence was examined using a function The entrainment estimate for 1995 of 222.9 million comparing mortality and egg production estimates. was the second highest since three-unit operation Excluding 1993 data, a significant positive relation- began in 1986. Because of refueling outages, Unit 2 ship was apparent, such that when egg production and did not operate during the entire larval winter flounder larval abundance li wi, mortality also increased. season and Unit 3 was shut down from April 14 Densities of newly metamorphosed demersal young through June 7. This decrease in cooling water use were also relatively high in 1995. He median density resulted in a calculated reduction in entrainment of during late summer was the largest found for one of about 44% (177 million larvae) from that expected if

, the two stations sampled, but abundance was only all three units had operated fully during the season.

l average at the other station. An index of abundance The impact of larval entrainment on the Niantic calculated for young winter flounder taken during the River stock depends upon the fraction of the winter

! late fall and early winter at the trawl monitoring flounder production entrained each year. Empirical i program stations was 31.7 in 1994-95, the highest mass-balance calculatin for 1984 95 have shown recorded since 1976-77. His high abundance resulted that a large number c trained larvac come fa,m from the strong 1994 year-class. Since 1983, this areas of Long Island _nd other than the Niantic abundance index has been significantly correlated with River an estimated u to 38% of entrained larvae that of young fish taken in the Niantic River during originated from the Niantic River. De percentage of summer. This index also indicated that the 1988 and the total river production entrained annually ranged 1992 year-classes were relatively abundant, whereas from 5.1 to 23.9%, but was 40.1% for 1995 because the 1993 year-class was weak. Few juveniles have of high abundance of late-stage larvae this year.

been taken within the Niantic River during the adult A stochastic computer simulation model (SPDM) spawning population surveys in recent years. Young- was used for long-term assessments of MNPS impact of-the-year abundance indices were not significantly over a 100-year period (1%0-2060). The winter

, conelated or were negatively correlated with those for flounder stock simulated was female spawner biomass I age-3,4, and 5 female adult spawners. Dus, none of (lbs), which is more directly related to reproductive the early life stages was a reliable index of year-class potential than fish numbers. Conditional mortality viii Monitoring Studies,1995

l rates cu.mspui ding to larval entrainment from mass-relatively high (p 2 0.70) likelihood of being greater balance c=Imla'taas and juvenile and adult impinge- than 30% of MSP and the baseline stock had about an ment at MNPS were simulated according to historical even chance of being greater than 40% of MSP. His information and projections. Natural and fishing recovery, however, assumed that changes in fishing mortality rates (F) were provided by the DEP and were regulations would be implemented as scheduled and different this year from values used previously. For that they achieved expected reductions in fishing simulation purposes, F was initially set at 0.40 in mortality. Even with reductions in fishing mortality 1960 and reached a maximum of 133 in 1990. Based and termination of MNPS operation, there remained a on proposed changes in fishing regulation, F was one in three chance that the new equilibrium stock projected to decrease substantaally over the next decade biomass would be smaller than 40% of MSP after to 0.60 by 2006 and ==aala~i unchanged thereafter. 2040.

In the SPDM simulation, an initial stock size of 109,534 lbs was used to represent the theoretical (no . Fish Ecology Studies fishing effects) maximum spawning potential (MSP) of the Niantic River female spawning stock. When Studies of fish assemblages in the vicinity of fishing was added, the annual projections of the MNPS were conducted to determine the effects of initially unfished stock become the baseline time- station operation. These impacts have been defined as series of annual spawning biomass in the absence of station-related changes in the occurrence, distribution, any plant impact. Under the exploitation rates and abundance of fishes which can affect community I simulated, the stochastic mean stock size of the structure. Potential effects include entrainment of baseline declined to 52,287 lbs by 1970 and to its early life history stages through the cooling-water lowest point of 12,375 lbs in 1993. The latter value system, impingement ofjuvenile and adult fish on the was less than one-half of a critical stock size, defined intake screens, and changes in distribution as a result as 25% of MSP. Following simulated reductions in of the thermal discharge, fishing, however, the stock rapidly recovered. New Trawl, seine, and ichthyoplankton (fish eggs and series of stock size projections were then simulated by larvae) monitoring programs were established in 1976 adding the effect of larval entrainment at MNPS. The to provide information for the assessment of impacts lowest projected stock biomass under simultaneous from MNPS operation. These programs provided the fishing and MNPS impact again occurred in 1993 basis for identifying taxa potentially affected, as well (10,317 lbs), whereas the greatest absolute decline as information on long-term abundance trends used to relative to the baseline occurred in 2000 (a difference measure changes in the local populations. More than of 14,211 lbs). Generally, greater reductions in stock 100 different fish taxa have been collected in these biomass resulted from fishing than from larval monitoring programs. Of these, six taxa: American entrainment. De simulated spawning stock returned sand lance, anchovies, grubby, silversides, tautog, and to within about 1,700 lbs of baseline levels (47,075 cunner were identified as having the potential to be Ibs, or 43% of MSP) only 6 years after the scheduled impacted by MNPS, either by entrainment or termination of Unit 3 operation in 2025. exposure to elevated water temperatures.

The probabilities that the Niantic River female Abundance data were analyzed separately for the spawning stock biomass would fall below selected two-unit (1976 85) and three-unit (1986-95) reference sizes (25,30, and 40% of MSP) were deter- operational periods and for the entire 19-year data mined to help assess the long-term effects of MNPS series (both periods combined) to determine if changes operation. A stock smaller than 25% of MSP is in abundance have occurred. Of the six fishes considered overfished, whereas one that is at 40% of identified as potentially impacted, negative hadaare MSP can maximize yield to the fisheries while trends were found for some life stages in four  !

remaining stable. For both baseline and MNPS- (American sand lance larvae, Atlantic silverside impact simulations, stocks were likely (p 2 0.83) juveniles and adults, tautog eggs, and cunner and greater than 40% of MSP in 1970. At the lowest tautog aduhs) of the six taxa.

point of both stock projections in the mid-1990s, all American sand lance larvae ranked third among replicates were less than 25% of MSP. Simulated entrained fish larvae and densities in entrainment reductions in fishing allowed for a rapid increase in samples have decreased after peaking in the late 1970s spawner biomass in 2000. By 2020, the stocks had a and early 1980s. Declines in sand lance abundance Executive Summary ix  ;

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were also apparent in other areas of the Northwest females do not mature until age-3 or 4. Therefore, the

, Atlantic Ouan, with abundance found to be inversely lower abundance of tautog eggs was probably due to a correlated with that of Atlantic herring and Atlantic decline in the abundance of spawning aduhs, most mackerel, which prey upon larval sand lance. likely due to fishing, rather than from the operation of However, abundance has begun increasing again in MNPS.

recent years and the entrainment estimate for 1994 (the ne most abundant of the fish eggs entrained were latest year for which data are available) was among the cunner eggs, which accounted for more than 50% of largest. Given the large changes in abundance of this the total collected since 1979. During three-unit population along the entire Atlantic coast, effects of. operation, cunner eggs have increased in abundance MNPS on sand lance abundance is difficult to with the density of cunner eggs in 1994 the fourth ascertam. largest recorded and the 1994 entrainment esumate the The bay anchovy is typically the most abundant highest of the entire 16-year period. De densities of ichthyoplankton species collected in estuaries within larvae found in 1994 were within the historic range of its range and was the dominant larval taxon entrained values. Similar to tautog, young-of-the-year cunner at MNPS. Recent abundance has been relatively low accounted for a higher proportion of fish caught by in comparison to the mid-1980s, but this decline trawl since three-unit operation began. The entrain-occurred prior to three-unit operation. The egg and ment of eggs is the greatest potential impact of larval densities and entrainment estimate for 1994 fell MNPS on the cunner population. However, if egg within their historic ranges. losses affected recruitment, then juvenile abundance Atlantic and inland silversides are among the most should decrease in relation to older fish. His decrease common shore-zone species along the Connecticut was not apparent in the length-frequency distributions, coast. Typical of short-lived species, the abundance of and relative abundance of juveniles has increased silversides is highly variable and annual catches by during the three-unit operational penod.

trawl and seine have ranged over two orders of magnitude. Recent catches of silversides by trawl and inland silverside by seine were within historic ranges.

However, the Atlantic silverside has significantly decreased in abundance during the three-unit opera-tional period at the Jordan Cove seine site. This decrease was probably not related to thermal effects, but may be related to a change in habitat (i.e., loss of eclgrass not attributed to plant effects) that may have affected spawmng success.

The grubby is unique because unlike other potentially impacted species it experiences no fishing pressure and has little forage value. Both larval and adult grubby abundance indices have been stable throughout the 19 years of monitoring and have actually shown some increasing trends in recent years.

The tautog was the second-most abundance egg taxon entrained, accounting for over 30% of the total eggs collected since 1979. During the three-unit oper-ational period a significant negative trend was found for densities of tautog eggs. However, larval densities were within their histonc range. Catches of tautog by trawl have been declining, with young-of-the-year accounting for a high proportion of the catch since three-unit operation began. If the decline in adult abundance was caused by entrainment losses, the reduction in egg abundance would have lagged behind the decline of juveniles by several years because 1

x Monitoring Studies,1995

f I Docket No. 50-423 l l

. B15661 l

1 i

l Attachment 2 to the Millstone Unit No. 3 Annual Environmental Protection Plan Operating Report l

January 1 - December 31, 1995 April 1996