ML041320586

Annual Environmental Protection Plan Operating Report

ML041320586
Person / Time
Site:	Millstone
Issue date:	04/30/2004
From:	Price J Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
04-188
Download: ML041320586 (16)

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OfDominion Dominion Nuclear Connecticut, Inc.

Millstone Power Station Rope Ferry Road Waterford, CT 06385 APR 30 2)O4 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Serial No.

NSS&L/DF Docket No.

License No.04-188 RO 50-423 NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 2003 ANNUAL ENVIRONMENTAL PROTECTION PLAN OPERATING REPORT In accordance with Section 5.4.1 of the Environmental Protection Plan (EPP), Dominion Nuclear Connecticut, Inc. hereby submits the Annual Environmental Protection Plan Operating Report, describing implementation of the EPP for the previous year.

Enclosure 1

transmits information for the period January 1,

2003, to December 31, 2003.

Should you have any questions regarding this report, please call Mr. Paul Blasioli, Environmental Services, at (860) 447-1791, extension 0417.

Very truly yours, A

A Price Vice President - Millstone Enclosure (1)

Commitments made in this letter: None.

cc:

U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406-1415

-j "7Zif-)

Serial No.04-188 Docket No.

50-423 Commitments made in this letter: None.

cc:

U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406-1415 Mr. V. Nerses Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 8C2 Rockville, MD 20852-2738 Mr. S. M. Schneider NRC Senior Resident Inspector Millstone Power Station

Serial No.

Docket No.

License No.

04-1 88 50-423 NPF-49 Millstone Power Station, Unit 3 Annual Environmental Protection Plan Operating Report January 1, 2003 - December 31, 2003

Annual Environmental Protection Plan Operating Report January 1 - December 31, 2003 Millstone Unit 3 Environmental Protection Plan Dominion Nuclear Connecticut, Inc.

Millstone Power Station Rope Ferry Road Waterford, Connecticut 06385 April 2004

2003 Annual Environmental Protection Plan Operatina Report (AEPPOR)

Introduction This report covers the period January 1, 2003, through December 31, 2003.

During 2003, Millstone Power Station Unit 3 (MP3) operated at a capacity factor of 99.3%; its capacity factor from the end of the last refueling outage (October 7, 2002) until the end of 2003 was 96.8%. MP3 began its ninth refueling outage in April 2004.

As required by the MP3 Environmental Protection Plan (EPP), this AEPPOR includes:

• summaries and analyses of the results of environmental protection activities,

• a list of EPP noncompliances,

• a list of all changes in station design or operation which Involved a potentially significant unreviewed environmental question, and

• a list of non-routine reports, describing events that could have resulted in significant environmental impact.

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 Millstone Power Station (MPS) NPDES permit requires continuation of biological studies of supplying and receiving waters, entrainment studies, and intake impingement monitoring. These studies include analyses of Intertidal and subtidal benthic communities, finfish communities, entrained plankton, lobster populations, and winter flounder populations. Paragraph 7 of the permit requires an annual report of these studies to the Commissioner of the Connecticut Department of Environmental Protection (DEP).

The report that fulfills these requirements for 2003, Monitoring the Marine Environment of Long Island Sound at Millstone Power Station. Waterford. Connecticut - Annual Report, 2003 (Annual Report), presents results from studies performed during construction and operation of MPS, emphasizing those of the latest sampling year. Changes to the biological communities noted in these studies are summarized in the Executive Summary section of the Annual Report, which Is attached as part of this report.

2003 AEPPOR

2.2 Effluent Water Quality Monitoring Paragraph 3 of the MPS NPDES permit requires monitoring and recording of many water quality parameters at MPS intakes and at multiple 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 the Connecticut Department of Environmental Protection (DEP).

The report that fulfills these requirements, Monthly Discharge Monitoring Report (DMR),

includes data from all Millstone units.

Consistent with prior annual AEPPOR submissions, water flow, pH, temperature and chlorine data pertaining to MP3 are summarized in Table 1.

Each monthly DMR identifies NPDES permit exceedances (i.e., events where a parameter value was beyond permitted limits) or exceptions (i.e.,

events where permit conditions were not met) for the month.

Other events dealing with NPDES discharges, while not resulting in a permit exceedance or exception, are included in the DMRs to provide the DEP with additional information.

There were no NPDES exceedances or exceptions for MP3 discharges reported in 2003.

3.

Environmental Protection Plan (EPP) Noncompliances No EPP noncompliances were identified for MP3 in 2003, i.e.,

• resulted in a finding of the annual EPP Compliance Audit.

4.

Environmentally Significant Changes to Station Design or Operation No MP3 Design Change Records or System Operating Procedure changes met the acceptance criteria for inclusion in this report, i.e.,

• were initiated during the report year, and included a determination that an unreviewed environmental impact could occur.

5.

Non-Routine Reports of Environmentally Significant Events No MP3 events met the acceptance criteria for inclusion in this year's report, i.e.,

• required the submittal of a Licensee Event Report (LER), and involved a situation that could result in a significant environmental impact.

Neither of the two licensee events that constituted reportable occurrences at MP3 in 2003 were determined to cause a significant environmental impact.

2003 AEPPOR

Table 1. MP3 NPDES Data Summary, Jan. 1 - Dec. 31, 2003.

Selected water quality parameters for Unit 3(1).

Jan.

Feb.

Mar.

Apr.

May June July Aug.

Sep.

Oct.

Nov.

Dec.

discharge flow (max)

(106 gpd) 1357 1357 1356 1357 1357 1357 1357 1358 1357 1357 1357 1357 discharge discharge pH range temp. range (OF) 8.0-8.2 8.1-8.2 8.0-8.2 8.0-8.2 7.8-8.2 8.0-8.2 7.9-8.2 7.9-8.2 7.8-8.3 8.0-8.2 8.0-8.1 8.1-8.1 46.1-64.8 49.5-56.3 51.0-61.1 56.0-65.8 61.3-75.5 68.9-83.8 77.1-87.6 80.4-88.6 81.9-91.5 72.5-85.1 65.5-81.8 58.2-68.2 discharge temp. (avg)

(OF) 55.4 52.8 53.9 59.1 66.5 74.3 81.2 84.1 84.4 78.6 71.0 62.1 avg AT

(°F) 17.7 18.2 17.4 16.6 15.7 14.8 14.3 14.3 15.2 15.7 16.2 16.8 max FAC (ppm) 0.15 0.11 0.09 0.11 0.10 0.10 0.07 0.07 0.12 0.11 0.20 0.13 max TRC (ppm)

<0.03 0.04 0.04 0.04 0.04 0.03 0.04 0.05 0.07 0.04

<0.03

<0.03 max SWS FAC (ppm) 0.19 0.17 0.20 0.21 0.21 0.20 0.20 0.24 0.23 0.22 0.19 0.23 Notes:

(1) Parameters are measured at MP3 discharge (DSN 001 C), except for TRC, which is measured at MPS discharge (quarry cuts; DSN 001), and SWS FAC (service water system; DSN 001 C-5).

Abbreviations Used:

Temp. = Water Temperature AT = Delta-T (difference between discharge and intake water temperature)

FAC = Free Available Chlorine TRC = Total Residual Chlorine SWS = Service Water System 2003 AEPPOR

Attachment to 2003 Annual Environmental Protection Plan Operating Report January 1 - December 31, 2003 Executive Summary Section of "Monitoring the Marine Environment of Long Island Sound at Millstone Power Station - Annual Report 2003" dated April 2004 2003 AEPPOR

ANNUAL REPORT 2003 Monitoring the Marine Environment of Long Island Sound at Millstone Power Station, Waterford, Connecticut Tautog Egg F

r Stage III Lobster Larva Stage IV Winter Flounder Larva Millstone Environmental Laboratory April 2004 Dominion

Executive Summary Winter Flounder Studies The local Niantic River population of winter floun-der (Pseudopleuronectes americanus) is potentially affected by the operation of Millstone Power Station (MPS), particularly by entrainment of larvae through the cooling-water systems of the operating units. As a result, extensive studies of the life history and popu-lation dynamics of this important sport and commercial species have been undertaken since 1976.

Each year, surveys of adult spawners are conducted in the Niantic River during late winter and early spring.

Larval sampling is conducted at the plant discharges, in Niantic Bay, and at three stations in the Niantic River. Age-O juveniles are collected at two sites in the river. Winter flounder are also commonly taken in the year-round trawl monitoring program (TMP).

Seawater temperature has potentially important effects during spawning, egg incubation, the larval period, and the remainder of the first year of life.

After 5 consecutive years of relatively warm water temperatures, monthly means in January-June and December of 2003 were cooler than long-term averages.

The A-mean trawl catch-per-unit-effort (CPUE) of fish larger than 15 cm in the Niantic River during the 2003 adult winter flounder spawning season was 2.2, the same value as in 2002.

Abundance of Niantic River winter flounder spawners peaked in the early 1980s and decreased thereafter, most likely from stock and recruitnent effects (ie.,

decreased per-capita recruitment at high stock sizes),

a generally warming winter trend, and increased rates of exploitation.

Niantic River CPUE was signifi-cantly correlated with several other winter flounder abundance indices from throughout Southern New England and numbers currently remain low throughout the region.

The Jolly stochastic model was applied to mark and recapture data to estimate the absolute abundance of the Niantic River adult spawning population.

The abundance estimate of winter flounder larger than 20 cm in 2002 was 15.4 thousand, which represented an increase over previous recent estimates of about 4-10 thousand fish. However, this estimate had a broad 95% confidence interval (+/-l3.4 thousand). Estimated population sizes during 1984-91 were much larger, ranging between about 33 and 80 thousand. Annual female spawner abundance estimates since 1976 ranged from a low of 2 thousand in 2001 to 75 thousand in 1982, with corresponding total egg production estimates from about 1.7 to 44.8 billion for the same years.

To provide some perspective on Niantic River win-ter flounder stock size estimates, annual exploitation rates were determined and used with annual recre-ational and commercial landings data of winter flounder for Long Island Sound (LUS).

The calculated exploitable biomass of Niantic River winter flounder likely only represented about 3% or less of the entire winter flounder resource in LIS during the past two decades.

In 2003, the aggregate abundance of winter flounder larvae in Niantic Bay was the third highest, after 1997 and 2000, since 1983. Abundance in the Niantic River, although the highest observed since 1998, was about average in comparison to the long-term (1983-2002) time-series.

In the river, more Stage I larvae were found than expected from the relatively low adult spawner abundance.

This was attributed to lesser egg predation by sevenspine bay shrimp, and is a potentially important compensatory mechanism.

Rates of larval growth and development were posi-tively correlated with water temperature, but other factors such as density and prey abundance most likely affected growth as well. Despite relatively cool water temperatures during 2003, growth rates of larvae in both the river and bay were both greater than expected and above average. Growth rates likely affect survival, as the larval mortality rate in 2003 was less than the long-term average, due to faster growth rate. Density-dependence was examined by comparing mortality and egg production estimates (a measure of yolk-sac larval stage abundance) at various monthly and seasonal water temperatures.

Results of this analysis suggested that larval mortality decreased with decreasing egg production (ie.,

density-dependency) and increasing spring water temperatures (i.e., faster development).

Following larval metamorphosis and settlement, demersal age-0 young were sampled by beam trawl at two sites in the Niantic River. Abundance of newly settled young in 2003 approximately equaled the record high densities observed in 2001. Mortality rate was less than the long-term average, which helped account for the relatively high abundance observed this year. High mortality rates in 2001 and 2002 reduced the abundance of these relatively large year-classes, whereas the 2003 year-class of age-O juveniles ranked with those of 1988 and 1994 as the most abundant observed since 1983.

Executive Summary v

The 2002-03 A-mean CPUE calculated for young winter flounder taken during late fall and early winter at TMP stations was the third lowest recorded in 27 years and did not reflect the high abundance of the 2002 year-clss as indicated by beam trawl sampling during the previous summer.

Although these two age-0 abundance indices were significantly correlated and identified emerging strong or weak year-classes, their correspondence has decreased during the past few years.

In any case, however, fewer age-i juveniles have been taken during each year of the Niantic River adult spawning population surveys since the early 1980s, with a CPUE for fish taken in the lower river navigational channel particularly low.

However, this abundance decrease was much less when a CPUE was calculated for fish taken only in the upper portion of the river.

The relative distribution of age-i fish in Niantic River and Bay may have also changed over the years, most likely due to environmental factors.

Young-of-the-year abundance indices were either not significantly correlated or were negatively correl-ated with the abundance of female adult spawners 3 to 5 years later. Conversely, positive correlations were found between age-i abundance indices and these older fish. However, the forms of the signif-icant relationships were unclear and none of the early life stages were considered to be a reliable predictor of potential future year-class strength.

Yet to be understood processes that occur after juvenile winter flounder leave shallow nursery waters in the fall of their first year of life seem to be operating, in that fewer adults are produced, particularly from more abundant year-classes.

A stock and recruitment relationship (SRR) was determined for the Niantic River winter flounder population using adult CPUE data. A February water temperature parameter significantly improved the model fit. At the behest of the Connecticut Depart-ment of Environmental Protection, the SRR was further modified by adding a depensatory parameter (ie., per capita recruitment rate decreasing with decreasing parental stock size). However, this param-eter was not significant.

The number of larvae entrained through the condenser cooling-water system at MPS is a measure of potential impact to winter flounder. As in previous years, Stage 3 larvae predominated (56%) in entrainment collections during 2003, with Stage 2 larvae (2P7%) also numerous.

Annual estimates of entrainment were related to both larval densities in Niantic Bay and plant operation. The 2003 entrain-ment estimate of about 434 million was the second highest estimate after 1992.

While this total was related to the fifth largest cooling-water demand by MPS occurring in 2003, to a large part the estimate also reflected the third highest larval abundance found in Niantic Bay. The entrainment rate (annual abundance index divided by total flow) has varied without trend since 1976, indicating that larval production and availability in Niantic Bay remained stable despite increased water use during the 1986-95 period of three-unit operation. Correlations between entrainment estimates and abundance indices of age-0 juveniles were positive, implying no entrainment effect, and that the more larvae that were available, the more that metamorphosed and settled in Niantic River and Bay. This was also illustrated by a com-parison of annual entrainment and juvenile year-class strength, which indicated that entrainment estimates served as an index of emerging year-class strength rather than being the most important factor in determining abundance.

The impact of larval entrainment on the Niantic River stock depends upon the fraction of the annual winter flounder production entrained each year, which is determined in this study as equivalent eggs (termed production loss).

Empirical mass-balance calculations showed that a large number of entrained larvae likely come from a number of sources in LIS, including stocks associated with the Connecticut and Thames Rivers, as well as from the Niantic River.

Remarkably similar estimates of the fraction of entrained larvae from the Niantic River were made when comparing results of the mass-balance model and an independently conducted study of genetic stock identification in both 2001 (19.7 and 21.9%,

respectively) and 2002 (13.8 and 12.3%).

This suggested that the mass-balance model provided reasonable estimates of Niantic River larval stock entrainment The Niantic River production loss estimate of 38A% in 2003 was well above the long-term average of 14.2/.

However, based on an apparent increase in egg survival noted in recent years, a factor which was not incorporated into this model, production loss estimates since 1995 may have been conservatively high To date, efforts of regulatory agencies to control fishing mortality have not resulted in large increases in abundance for winter flounder stocks across the region or in the Niantic River. Even so, the remain-ing small adult spawning stock in the river continues to produce relatively large numbers of larvae and young fish, which are a likely result of population compensatory mechanisms. The effective retirement of Unit I in late 1995 was followed by an immediate reduction of about one-quarter of the MPS cooling-water flow, which has permanently lessened plant impact, but has not resulted in stronger year-classes and subsequent enhanced recruitment to the spawning vi Monitoring Studies, 2003

stock. Despite relatively good abundance of post-entrainment immature winter flounder, significant recruitment to the adult spawning population has not occurred in recent years, due to unknown factors removing these fish from the population. Environ-mental effects, including changes to the Niantic River and interactions with other species (e.g., predation),

especially during early life history, also are important factors likely affecting the winter flounder recruit-ment process.

Fish Ecology Studies The objective of the fish ecology monitoring program is to determine whether operation of UPS has adversely affected the occurrence, distribution, and abundance of local fishes.

Potential impacts include entrainment of fish eggs and larvae through the condenser cooling-water system, impingement of juvenile and adult fish on intake screens (which has been mitigated by the installation of fish return sluiceways), and changes in distribution or abundance attributable to the thermal discharge. Trawl, seine, and ichthyoplankton monitoring programs were estab-lished in 1976 to provide the basis for idenfying taxa potentially affected, as well as infonmation on long-term abundance trends used to measure changes in the loal pouatos.

This report smmarzes data collected in trawl and ichthyoplankton monitoring programs from June 2002 through May 2003 (report year 2002-03) and in seine monitoring from May through November 2002 and 2003. During the 2002-03 report period, MPS Units 2 and 3 were both operating most of the time and Unit I was shut down.

Detailed analyses on seven taxa most susceptible to MPS operational impact from entrainment or thermal effects assessed the potential effects of MPS.

Analyses of these species generally focused on comparing temporal trends over the past 27 years.

No significant long-term trends were detected for juvenile and adult silversides collected by trawl or seine. Similarly, no long-term trends were identified for all life stages of grubby, cunner eggs and larvae, and tautog larvae. Atlantic menhaden larvae showed a significant increasing trend in abundance, as did juveniles of this species taken by seine and trawL Likewise, a recent stock assessment indicates that Atlantic menhaden stocks are not overfished and abundance has increased in Southern New England waters. Since the late 1970s and early 1980s, cunner and tautog have become less abundant at the Intake station, exhibiting a significant negative trend.

However, following the removal of the Unit 3 rock cofferdam, a preferred habitat for these species, no significant trend was detected in the abundance of cunner and tautog at the Intake station.

Cunner abundance at the Jordan Cove and Niantic River trawl stations has fluctuated without trend.

Tautog, primarily juveniles, are increasing in abundance at the Niantic River trawl station and in Jordan Cove catches by both trawl and lobster pot. Although over the entire time-series (1979-2002) tautog eggs exhib-ited a negative trend in abundance, egg abundance has increased during the past 5 years, likely indicating a recent increase in spawner biomass from decreased fishing mortality. The large numbers of tautog and cunner eggs entrained at MPS did not appear to affect fiture recruitment and subsequent spawning stock biomass of these two fishes, because the proportion of juvenile recruits relative to adults has increased and there has been a significant increase in tautog in the Niantic River and Jordan Cove.

A recent tautog reproductive study conducted in eastern LIS showed that annual fecundity was nearly twice that of the only other comprehensive tautog reproductive

study, which was done in Virginia.

The relatively high reproductive capacity of LIS tautog likely buffers any entrainment losses.

American sand lance larvae exhibited a significant long-term decrease in abundance since 1976, but this was likely due to large-scale ecological effects (ie.,

temporal shifts in abundance of major predators).

Densities of both anchovy eggs and larvae showed significant negative trends. The bay anchovy appears to be experiencing a regional decline in abundance.

A sharp drop in abundance was measured over the past decade in Narragansett Bay and populations declined dramatically in Chesapeake Bay after 1993.

The bay anchovy is an important forage species for striped bass whose recent increases in abundance along the Atlantic Coast may have contributed to the reduced numbers of bay anchovy and sand lance.

Cooling-water use at MPS has been reduced 23%

due to the shutdown of Unit I in 1995, result-mgin less entraminment and impingement In addition to the Unit 3 fish return, which was in operation at unit start-up in 1986, impingement impacts were further reduced at MPS with the installation of an aquatic organism return sluiceway at Unit 2 in early 2000.

Given this reduction in cooling water use and based on increasing trends in abundance or the lack of decreasing trends, it can be concluded that MPS has had little effect on local fish assemblages.

Executive Summary vii

Lobster Studies The American lobster (Homws americanw) occwns in the Northwest Atlantic from Canada to Cape Hatteras Lobsters are also one of the largest mobile bentic invertebates in the western North Atlantc and are important inhabitants of coastal ecosystem.

In early summer, after hatching from eggs, lobster larvae swim to the surface to begin the 6-to 8-week planktonic phase of their life cycle and are susceptible to entrainment through cooling water systems. Juvenile and adult lobsters can be impinged on intake traveling screens or be exposed to the heated effluent in the dischaYge area.

Because of the economic and ecological importance of this spcies, obters have been monitored from May through October since 1978, using wre lobster raps set at three stations around MPS.

Since 1984, entraiment studies have been conducted during the hatching season, to estimate the number of lbster larvae drawn through the cooling water system. The objective of the lobster monitoring program is to determine if operation of MPS has caused significant changes in local lobster abundance and population characteristics beyond those expected from changes in the filshey and natural variabily.

Fishing pressure on the species is intense throughout its rmage. The number of traps used in the US. fishery has increased eigfold since the early 1980s.

Coincidental with the increase in fishing effort, landings made in the commercial fishery throughout New England have increased markedly over the last three decades.

Commercial landings of lobsters in Connecticut waters of LIS increased from 0.8 million pounds in 1979 to a record 3.7 million poundsin 1998.

However, landings declined 70%h between 1998 and 2002 to only 1.1 million pounds. Landings declined even further by 2003 when only 0.6 million pounds were harvesteo The recent decline in lobster abundance has been attributed to a significant lobster die-off in western LIS.

Beginning in the fall of 1998 and throughout the summer of 1999, an unexplained highly virulent illness emerged in lobsters harvested from western LIS.

Lobstermen reported that more than half of the lobsters caught in traps were dead or died before arriving at port. Concurrent with the lobster die-off in western LIS, a widespread outbreak of shell disease syndrome began in the fall of 1998 in our area of eastern LIS and other coastal areas of southern New England.

Naturally occurring bacteria and fimgi have been implicated as causative agents of shell disease. These microorgnismns consume the exoskeletons of crustaceans, resulting in a shell that is pitted and marred with necrotic lesions. Although shell disease is not immediately fatal, death may ultimately occur, and the unsightly appearance of the lobster shell can greatly affect marketability.

In the summer of 2002, lobster fishers in central and western LIS described new reports of a significant number of moribund and dead lobsters. Affected lobsters were characterized by an orange discoloration of the abdomen, lethargy, and poorposta re survivaL In response to the die-off in western LIS and shell disease outbreak in eastern LIS, the US. Secretay of Commerce declared a failure of the LIS commercial lobster fishery in January 2000. In 2001, the US.

Congress allocated $13.9 million in federal disaster funds for the LIS lobster industry. Half of this federal funding was earmarked for research investigations on causes and economic impacts of the die-off and shell disease in LIS lobsters. At present, researchers suspect that the 1998-1999 die-offs in western US were caused by multiple disease pathogens exacerbated by environ-mental stressors, such as increased seawater temper-ature, anoxia and contaminants.

The mortalities observed during summer 2002 were related to an accumulation of calcium carbonate in lobster tissue (calcinosis) mediated by prevailing high bottom water temperature in LIS.

Total lobster abundance in our area increased moderately during 2003, reversing a significant declining trend in total abundance observed from 1999 to 2002. However, the abundance of legal lobsters and commercial landings in the MPS area continued to decline during 2003. Lobster mortality in western US could be responsible for the declining total catches observed from 1999 to 2002 and the persistent decline in legal catches and landings observed through 2003.

If lobster recruitment in our area depends on larval production in western US, and the population in western LIS does not recover, catches in our area could continue to be affected in the future. This source-sink relationship between western and eastern LIS and the long-term sustainability of the Connecticut fishery may be further threatened by the widespread outbreak of shell disease along the east-coast over the past four years.

Occurrence, abundance, and physiological changes in lobster growth and maturation were not due to operation of MWS; rather, these changes were most likely mediated by a natural rise in seawater temper-ature over the past 26 years.

The most notable changes in the population characteristics of local lobsters during 2003 were observed in the female-dominated sex ratio of lobsters at the Twotree station and the unusually high proportions of egg-bearing females. In addition, trends observed in the size structure of egg-bearing females over the past decade continued during 2003; egg-bearing females were smaller in size and more than viii Monitoring Studies. 2003

90% were below the legal size limit of 82.6 mm. The cause for the shift in sex ratios at Twotree is unclear, but the changes in proportion of egg-bearing fenales and their size structure could be related to smaller lobster growth per molt and earlier maturation of female lobsters. The benefits of earlier maturation in eastern LIS may be significant to population growth and recovery following the die-off in western LIS.

Currently, the smaller size at sexual maturity allows females to spawn I or 2 times before reaching the legal size. The benefits of earlier female maturation may have been offset in recent years, however, due to the outbreak of shell disease; egg-bearing females had the highest prevalence and severity of shell disease. If berri females suffer higher natural mortality due to shell disease, the effects on recruitment in our area could be significant Results from our lobster monitoring program suggest that before the die-off; operation of the MIS cooling water system did not cause a decrease in the local lobster population.

Recent changes in population characteristics and longterm fluctuations in abundance were likely related to changes in environmental conditions, most notably seawater temperature, or to other factors mediated by temperature such as increased susceptibility and transmission of diseases and precipitation of calcium carbonate. The die-off in western US, the outbreak of shell disease in eastern LIS and changes noted in lobster growth and size at maturity coincided with natural increases in seawater temperature over the past 2 decades. Since LIS is the southern extreme of the American lobster's range in nearshore waters, a gradual rise in ambient seawater temperature may have profound effects on the biology and physiology of this species.

Rocky Intertidal Studies Measurable ecological changes to the shore community near the MWS discharge were associated with operational events that occurred during 25 years of rocky intertidal monitoring. These changes are not widespread, and remain restricted to approximately 150 m of shoreline on the east side of the power plant discharge to Long Island Sound. Thermal impacts to the shore community at Fox Island were first observed in 1983, after the opening of the second quarry cut.

Thermal addition to this site was modified when Unit 3 began commercial operation in 1986, and three-unit operating conditions over the next II years allowed for long-term successional community development under a relatively consistent thermal regime.

This community exhibited some changes during the extended shutdown of all three reactors from March 1996 through June 1998.

Results of post-shutdown studies (1999-2003) showed that many components of the thermally adapted community at Fox Island-Exposed (FE) were highly resilient because, as units returned to service, they quickly recovered.

Seasonal shifts in occurrence of annual algal species were noted at FE during three-unit operation, and following Units 2 and 3 restarts in 1998-99.

These shifts included abbreviated season for cold-water species (e.g.,

Monostroma grevillet Acrosiphonia arcta4 and Dumontia contorta) and extended season for warm-water species (e.g.,

Grimelia americana, Dasya ballouviana, and Bryopsis hypnoides). Seasonality of these species at FE during the recent shutdown period was more typical of other sites.

Initial establishment of perennial populations of Graciliaria dkvahiae and Sargasswn flipendula at FE was also detected through qualitative studies during early three-unit years. These populations were not observed during many collections at FE during the shutdown period, but returned after Unit 3 restart in 1998. In addition, a new species to our study, Hypnea musciformis, was collected at FE in 2001, and is now a common summer component of the FE flora.

Dominant species abundance and distribution patterns at FE, established during three-unit opera-tion, were more resilient to the return of ambient conditions. Thermal impacts were most apparent in the low intertidal following Unit 3 start-up in 1986.

A population of the opportunistic green alga Codium firagile, a perennial Polysiphonia spp. population, and periodically heavy sets of the blue mussel ytus edulis replaced the low intertidal Chondrus popu-lation and its associated seasonal epiphytes (e.g.,

Monostroma, Acrosiphonla) at FE. Winter declines in Potysiphonia abundance typical of other sites was observed at FE during the shutdown period, but otherwise, little change in low intertidal community composition was observed, relative to recent years when MWS was operating. Many characteristics of the impacted low intertidal community at FE (sparse, fluctuating populations of barnacles and Chonrus, heavy mussel sets) were most likely related to the dominance of the Codium population, which persisted through the shutdown period, rather than direct thermal effects.

More recently, Codium steadily declined following MWS restart in 1998 and is no longer a low intertidal dominant at FE. Seasonally high abundance of Hypnea muscifonnis and expan-ded populations of Sargassum fflpendiua, Corallina officinalis, and Gelidium pusillum now characterize the low intertidal at FE.

Elevated temperatures fiom the MPS discharge was liked to higher Ascopyllum growth at the Executive Summary ix

experimental site (Fox Island-New, EN) than at other sites during many previous study years. However, high growh at FN was also observed during two growing seasons (1996-97 and 1997-98) while all three units were shutdown, and was not evident during three of the next 4 years following MPS restart (1998-1999, 2001-2002, and 2002-2003).

Natural influences of other factors such as ambient temperature conditions, nutrients and light may play a more important role in determining Ascophyllum growing conditions at FN than does thermal phone incursion from the MPS discharge.

The rocky intertidal monitoring program has also documented regional patterns and modifications to shore communities unrelated to MPS operation. These include the introduction and spread of an exotic red alga, Antthmnion pectlamzm, decreases in barnacle abundance in recent years, and a long-term increase in abundance of the common brown rockweed, Fcs vesiculosus.

Benthic Infauna Benthic infunial monitoring and analyses of long-term data have provided evidence of acute and chronic impacts that are either related to power plant construction and operation or other, presumably natural, disturbances.

Infaunal communities and species populations exhibiting evidence of MPS impacts were observed at stations in the immediate vicinity of MPS: Intake (IN), Effluent (EF), and Jordan Cove (JC). Changes in infaunal abundance and composition at these sites were closely associated with changes in sediment composition related to power plant-induced disturbance.

The infiumal community at the Giants Neck reference site (GN) provided a baseline from which variability asso iated with natural environmental cycles and disturbances could be assessed.

Impacts in the form of physical disturbances initiated community changes at IN and JC between 198-1987. Dredging and cofferdam removal at the intake during Unit 3 construction from 1983 to 1985 resulted in changed sedimentary characteristics (primarily silt/clay content levels), but sediments have become more consistent over time. Some inf al community stabilization and recovery was also apparent In particular, numbers of individuals and species richness at IN have steadily increased over the study period, as have abundances of organisms typically more common in early study years or at other sites, such as Aricidea catherinae. These

trends, along with concomitant decreases in abundance of opportunistic species such as Nucada aulata, indicate some degree of recovery at IN.

Other organisms that established post-impact community dominance, such as oligochaetes and Protodorvillea gaspeensis, indicate a changed community that may persist.

Fine sediments scoured from the MPS discharge area following Unit 3 start-up in 1986 were deposited at JC, as evidenced by increased sediment silt/clay content and changes in infaunal community structure at the JC monitoring site. This depositional event occurred over a short period (less than one year) at the beginning of the three-unit operational period, and its impact has lessened since 1986. For example, Aricddea catherinae and Thawyx spp. abundances both rebounded to levels observed during 2-unit years within a few years of Unit 3 start-up, and have maintained this degree of community dominance through 2003.

These indications of community recovery are supported by sediment data; both silt/clay content and mean grain size have steadily stabilized as they have approached pre-1987 levels.

However, evidence of previous disturbance still exists.

For example, the opportunistic mollusc Nucula alndata maintained a population at JC through 2003 at well above pre-Unit 3 levels. The altered infaunal community has exhibited firther changes in recent years, including 2003 studies. This biological evidence of disturbance is consistent with trends in sediment characteristics: elevated silt/clay levels in sediments at XC persisted through 2003.

The EF benthic infaunal community, located in the path of the discharge 100 m from shore, experiences chronic exposure to the MPS discharge. Scour fromn the discharge current modified sediments and the infaunal community at EF immediately after Unit 3 startup in 1986. Relatively coarse sediment with low silt/clay levels was characteristic of the three-unit benthic habitat at EF, but as of June 2003, silt/clay content decreased and mean grain size increased beyond levels observed since 1986. The cause of this recent sediment change is unclear, but it may account for the low overall infaunal abundance and numbers of species observed at EF in 2003. The sedimentary environment at EF, and the infiumal community it supports, continues to show changes under the new environmental conditions created by the two-unit discharge.

Ohigochaete abundances have generally decreased firom high abundances during the early three-unit period, and in recent years (2000-2003) remain among the lowest observed during the study period.

Sediments and inumal community characteristics at the reference site GN have exhibited changes that were not related to operation of MPS. Mean grain size has been variable, while silt/clay was relatively x Monitoring Studies, 2003

consistent, with no long-term trends in either parameter. Infaunal community composition at GN has generally been dominated by three taxa (Th1yx spp., oligochaetes and Aricidea catherinae). Aricidea catherinae, common at GN in the early monitoring years, has declined in abundance, while 7haryx spp.

and oligochaet abundances have increased over the entire study period.

The GN station has been valuable in validating periodic area-wide shifts in species abundance and community structure in response to natural factors unrelated to MS operation. Population increases occurred in the abun-dance of the opportunistic polychaete Mediomastw ambiseta at GN (and at IN and JC, stations near MPS) during 1983-88, 1994, and 1"98-99.

These increases were independent of power plant operation or construction. In addition, GN data substantiated regionally low overall faunal abundance in 2003, and a general regional decline in numbers of species over the 24-year period.

may factor strongly in observed declines.

The Niantic River has a more restricted tidal inlet and is closer to sources of nutrient enrichment than is Jordan Cove. Historically, eelgrass has ranged to far western reaches of LIS, but over the last century has become restricted to the easternmost third of the Connecticut coastline, due to nutrient loading and eutrophication of the western portions. This study suggests that the west-to-east declining trend in eelgrass distribution in LIS may be progressing further.

EeIgrass Eelgrass (Zostera marina L.) shoot density, seed-bearing shoot abundance, shoot length, standing stock biomass, and distribution were monitored during summer months from 1985 to 2003 at three locations near MPS. Short-term declines in eelgrass abundance were directly associated with fouling and overgrowth of eelgrass on two occasions; once by blue mussels (lWus eduihs) and once by a bloom of green algae (Cladophora spp.).

Analysis of long-term trends indicated some degree of decline in most of the parameters examined at all three areas monitored.

The spatial relationship of the long-term eelgrass declines suggests primary causal factors other than the power plant discharge or regional environmental change. Two populations to the east of MPS and near the fringes of the thermal plume (<1.5 km from the MPS discharge to LIS) exhibited only slight declines over the 16-yr study period; thermal input from MPS under three-unit operation to these sites was minimal

(<10C above ambient conditions), and has decreased since the retirement of Unit I in 1995. By compar-ison, heavy celgrass losses were documented in the Niantic River, located >2 km from the power plant thermal plume. Die-offs of entire individual eelgrass study beds in the Niantic River were observed on five separate occasions during the study.

Distribution surveys during 2002 and 2003 show early signs of eelgrass bed expansion in the Niantic River. While the causes of declines since 1985 were not determined, anthropogenic influences such as nutrient loading from surface nm-off and groundwater sources Executive Summary xi