Investigations of impingement of aquatic organisms at the Calvert Cliffs Nuclear Power Plant, 1975–1995

The Calvert Cliffs Nuclear Power Plant (CCNPP) in Maryland began commercial operation in 1975. The once-through cooling system pumps Chesapeake Bay water at a maximum rate of 73 m³/s (2.4×10⁶ gallons per min) to the condensers, a total equal to 0.7% of the average tidal flow in the area.From 1975 to 1995, impingement monitoring was conducted at CCNPP. The 21-year record is one of the most extensive of its kind in the utility industry. A total of 73 species of fish were identified. Often, five species accounted for over 90% of the total number of fish collected in any year. Estimates of total annual fish impingement ranged from 79,000 to over 9.6 million with a 21-year average of 1.3 million fish per year. Total impinged biomass was less variable with a range of 1300 to 18,600 kg/yr (9100 kg/yr avg.)Six different survival studies were conducted at CCNPP and species-specific impingement tolerances were determined. Eleven of the 14 species caught most often had survival rates over 50% and blue crabs demonstrated greater than 99% survival. When total impingement estimates are adjusted to account for survival, the fish impact is reduced by over 73%.This impact is small compared with commercial and recreational fishing and other natural causes of mortality. In addition, many of the significant impingement collections were episodic events correlated with high temperature and low dissolved oxygen conditions in the intake water. The Maryland Department of Natural Resources has concluded that CCNPP impingement losses are small and do not represent a significant impact to fish populations in the mesohaline regions of the Chesapeake Bay.     

316(b) and Quad Cities Station,Commonwealth Edison Company

Quad Cities Station is a 1630 MW_e dual reactor facility located on the Upper Mississippi River approximately 30 miles north of Davenport, Iowa and Rock Island, Illinois. As designed, the Station utilizes river water at the rate of 2270 cfs in an open-cycle mode of operation. From the 316(b) perspective, numerous agencies and intervenors expressed major concern regarding the potential adverse impacts of open-cycle entrainment and impingement effects on the River’s highly valued and diverse fishery. As a result, the fishery has been monitored continuously since 1971 through field surveys directed at measurements of community composition and relative abundance, as well as fish impingement surveys of the Station’s intake. From 1972 to 1983 the Station operated in a closed-cycle or partial closed-cycle mode.Regulatory relief and intervenor approval for open-cycle operation were not granted until 1984, following several years of intensive studies directed at entrainment/impingement and methods to reduce impingement. Beginning in 1978, the freshwater drum was selected as the indicator species most likely to manifest changes in population characteristics potentially resulting from open-cycle operation. Population levels (numbers and biomass), growth, fecundity, sex ratios and survival were all monitored to determine if compensatory responses occurred within the population following increases in impingement under open-cycle operation. Included in the agreement that allowed the return to open-cycle operation was a commitment to construct and operate a fish production facility to mitigate for potential impacts.After 14 years of monitoring under open-cycle operation, there have been no measurable changes in the local fishery and, specifically, none within the freshwater drum population. Naturally occurring environmental conditions have more profound influences on this dynamic and resilient fishery than operation of a large generation facility. Station operation is relatively constant from year to year and impingement monitoring may actually be the most accurate monitoring activity. Fluctuations in annual impingement projections are reflections of conditions within the river and the fishery’s response to them. Increases or decreases in fish numbers impinged at the Station in any given year are primarily due to fluctuations in the fishery and the effects of existing environmental variables and not to Station operation. The fishery fluctuations are reflections of conditions within the river and the fishery’s response to them.     

Estimating the abundance and egg production of spawning winter flounder (Pseudopleuronectes americanus) in the Niantic River,CT for use in the assessment of impact at Millstone Nuclear Power Station

The winter flounder is a coastal flatfish with spawning populations associated with specific estuaries or coastal areas. Because of its stock structure, this species is susceptible to localized impacts, including power plant entrainment of larvae. Winter flounder rank second in fish larvae entrained at the Millstone Nuclear Power Station (MNPS), located on Long Island Sound in Waterford, CT, USA. Because of its importance to the state’s fisheries, the population spawning in the nearby Niantic River was selected for impact assessment studies in the early 1970s. Northeast Utilities has consistently monitored annual abundance of adult spawners, characterizing relative abundance by trawl catch-per-unit-effort (CPUE) and absolute abundance using mark and recapture data with the Jolly model for demographically open populations. Trends in these two independent but highly correlated indices provide short-term assessments of winter flounder abundance. Abundance of winter flounder peaked in the early 1980s, but as fishing mortality increased to high levels in the late 1980s, their numbers declined thereafter and presently are very low. Information on sex ratio, length-frequency distribution, and spawning condition allow for calculation of annual egg production using a length-fecundity relationship. This forms the basis for estimating production loss due to larval entrainment, which is used as input to a long-term assessment model of power plant impact, discussed in an accompanying paper (Lorda et al., 2000: Lorda, E., Danila, D.J., Miller, J.D., 2000. Application of a population dynamics model to the probabilistic assessment of CWIS effects of Millstone Nuclear Power Station (Waterford, CT) on a nearby winter flounder spawning stock. Environmental Science & Policy 3, S471–S481).     

Assessment of 316(b) impacts on Ohio River fish populations

Cooling water intake systems have the potential to adversely impact aquatic organisms though entrainment and impingement (impacts referenced under 316(b) of the Clean Water Act), yet the loss of individual fish does not necessarily mean that a population will suffer a significant decrease in number. The results of utility sponsored studies on Ohio River fish populations provide strong evidence of positive changes in the fishery due to water quality improvements. Despite these improvements, a simulation is needed to determine if a reduction in 316(b) fish losses would result in higher or similar fish population levels. Electrofishing data collected at seven power plant locations from 1981 to 1998 will be used for the population assessments. Potential 316(b) impacts on Ohio River fish populations will be modeled using site specific 316(b) data and a Leslie matrix model. The theoretical maximum population for various fish species, with and without 316(b) impacts, will be compared and the probabilistic risk that fish populations will fall below the threshold for species survival will be assessed. Historically, EPA has allowed 316(b) to be implemented on a case-by-case basis, however, the utilities believe that the first step in assessing potential adverse environmental impacts is to assess the condition of the affected fish populations.     

Wisconsin Electric’s experience with fish impingement and entrainment studies

Since 1975, Wisconsin Electric has conducted impingement studies at seven steam electric, once-through cooling-equipped power plants, as well as at one closed-cycle cooling system-equipped plant. Entrainment studies were also conducted at all seven once-through cooling-equipped plants. All eight plants are located on the Great Lakes or on major tributaries to them. Two of the eight plants have since been retired, while portions of two remaining multi-unit plants have been retired.As part of the study reports ultimately filed with the state agencies overseeing the studies, companies were also required to provide information on: intake design, capacity, and operation; whether biocides were used at the plants to control biofouling; and what ice control measures were employed during the winter season. Companies were also asked to provide brief assessments of available intake design alternatives that could be reasonably expected to reduce entrainment or impingement, as well as order of magnitude cost estimates for retrofiting plants with feasible alternative technologies.The studies concluded that since the vast majority of fish impinged during the 1975–1976 period were alewife and rainbow smelt (the then most abundant species in Lakes Michigan and Superior) and since the historic commercial harvests of these two species greatly exceeded annual impingement estimates, the impact of these incremental losses to lake-wide populations was inconsequential. With respect to the entrainment results, the studies detected few fish eggs or larvae that were not alewife or smelt.As a consequence of these findings, the company did not believe that any structural modifications to the intakes were necessary, since any one of the feasible alternatives would have been very costly. The state agencies concurred with these findings.     

Entrainment and impingement studies at two power plants on the Wabash River in Indiana

Fish entrainment and impingement studies were conducted at Cayuga and Wabash River generating Stations in 1987 and 1988, respectively. Concurrent river samplings were conducted upstream from the stations to assess adult fish and ichthyoplankton populations. The original 316(b) studies at these stations were conducted in 1976–1977 and concluded that the stations were having minimal adverse impact on the Wabash River fish community. The state regulatory agency did not agree with this interpretation and requested the subsequent 1987 and 1988 studies. The major issue at these once-through cooling power plants was the large water withdrawals at Cayuga and Wabash River Stations [1318 and 1096 cubic feet per second (cfs) maximum plant flows, respectively], in contrast to the relatively low average annual Wabash River flows (10,070 and 11,110 cfs, respectively). The close proximity of the stations (35 river miles apart) together with the high percentage of water withdrawn suggest that the potential risk of unacceptable impacts is high.The six-month impingement estimates for Cayuga and Wabash River Stations were 15,086 and 11,401 fish, respectively. Impingement catches at both stations were dominated by young-of-the-year (YOY) channel catfish and gizzard shad. In addition, small minnows (primarily bullhead minnow and emerald shiners) were commonly impinged at Cayuga Station. Minnows (predominantly spotfin shiner, bullhead minnow and emerald shiner) were also the dominant species in the river samplings upstream from the stations. In the entrainment samplings, an estimated 26,920,382 and 107,503,876 fish eggs and larvae were entrained each year at Cayuga and Wabash River Stations, respectively. Ictiobinae (buffaloes and carpsuckers) and Cyprinidae (minnows and shiners) were the dominant ichthyoplankton in the river. Approximately 3.5 and 23% of the total river ichthyoplankton were entrained at Cayuga and Wabash River Stations, respectively. Gizzard shad at Cayuga Station, and Ictiobinae and Cyprinidae at Wabash River Station (WRS) were the dominant taxa entrained by the stations. Unusually low river flows during the spring and summer of 1987 and 1988 provided worst-case conditions for entrainment and impingement at the stations. However, the relatively low impingement and entrainment numbers during these worst-case conditions indicated that these stations were not adversely affecting the Wabash River fish community.     

Application of a population dynamics model to the probabilistic assessment of cooling water intake effects of Millstone Nuclear Power Station (Waterford,CT) on a nearby winter flounder spawning stock

A major concern of the Connecticut Department of Environmental Protection at Millstone Station has been the long-term effects of the station’s Cooling Water Intakes System (CWIS) on a small stock of winter flounder spawning in the Niantic River. Following the selection of a population modeling approach for long-term impact assessment in 1983, sampling programs were directed to collect data specifically for this purpose. These data were used to estimate the size of the local flounder stock and the fraction of its annual production lost to CWIS effects, and also evaluate a possible relationship between late-winter water temperatures and recruitment success of flounder. Since the mid 1980s, the main assessment tool at Millstone has been an age-structured population model that incorporated uncertainty in selected model parameters and provided output suitable for probabilistic analyses of simulation results. This model projected annual population sizes resulting from different fishing rates, larval entrainment losses, and impingement of juvenile and adult fish. Compensation was introduced via a Ricker stock-recruit function with an additional term to describe the effect of water temperature on recruitment success. Ricker’s α parameter, which describes the species inherent capacity to increase in numbers, was derived by four indirect methods based on life history parameters. In the basic simulation strategy, an unfished flounder stock was simulated first, and then fishing effects and mortality of the young attributed to CWIS effects were added. Combinations of different fishing rates and CWIS effects, either estimated or hypothesized, could be simulated for comparing the effectiveness of different mitigation alternatives. This approach helped identify fishing mortality as the driving force shaping the future size and viability of the local flounder population at Millstone and suggested that larval entrainment mitigation measures, costing hundreds of millions of dollars, would be ineffective in reversing currently declining trends of that population.     

A perspective on power generation impacts and compensation in fish populations

Renewed interest in the topic of compensation in fish populations has been stimulated by new EPA 316(b) regulations relating to entrainment and impingement looming on the horizon. The purpose of this paper is to revisit the topic of population compensation for fish populations in the context of assessing power generation impacts. I define compensation as the net population-level outcome of changes in growth, survival, and reproduction at the individual fish level that offsets decreases or increases in population density. Potential mechanisms of compensation have been well document in laboratory and field experiments. The process underlying all these mechanisms is that changes in population density can change per capita availability of essential resources such as food and space. The state of science in this area is constrained both retrospectively and prospectively by five technical stumbling blocks. Technological advances have improved our ability to bound the phenotypic plasticity of a species and to assess the potential effects of power generation impacts through a combination of monitoring, special studies, and simulation modeling. Four generalizations concerning compensation are mentioned. Progress has been made over the past three decades, but this topic remains scientifically challenging and politically controversial.     

A comparative review of entrainment survival studies at power plants in estuarine environments

Steam-electric power plants drawing cooling water from surface waters entrain a variety of plankton and weak-swimming nekton. These small organisms pass through the intake screens and are carried along with the cooling water through the plant and are subjected to thermal, physical, and chemical (biocide) stresses. In once-through cooling systems, entrained organisms are returned to the source water body, where they are subjected to rapidly decreasing temperatures as cooling waters are mixed into receiving waters. With 4316(b) of the Clean Water Act as the impetus, studies were conducted at many power plants to quantify the number of entrained organisms. Early studies focused on simple abundance, and assumed total mortality. By the late 1970s and early 1980s, advances in sampling technology demonstrated that many entrained organisms survived. Continuing refinement of sampling techniques revealed impressive survival statistics for many species (>90% in some cases), with concomitant reductions in perceived impacts. This paper reviews state-of-the-art sampling methods and results of field entrainment studies at seven power plants. This review demonstrates that high entrainment survival of a variety of aquatic organisms does, in fact, occur and specifies the plant-operating and environmental conditions under which high survival occurs.     

Fish protection technologies: a status report

Section 316(b) of the Clean Water Act has required that “best technology available” (BTA) be used to minimize adverse environmental impacts resulting from operation of the cooling water intake structure (CWIS). The primary effects of CWIS operations are the entrainment of small aquatic organisms through the cooling water system and the impingement of larger life stages on traveling water screens. Extensive research has been conducted since the early 1970s in attempts to develop technologies that will minimize entrainment and impingement. As a result, a suite of technologies is available that can be considered for application as the BTA at the CWIS. Available technologies include fish collection systems, fish diversion systems, physical barriers and behavioral barriers. The ability of a given technology to meet BTA requirements is influenced by a wide variety of biological, environmental and engineering factors that must be evaluated on a site-specific basis. The status of systems and devices in each category of fish protection alternatives is presented.     

An index of ecosystem integrity for Northern Chesapeake Bay

We propose a theoretical approach to evaluating the quality of large ecosystems under anthropogenic stress, and present a partial application of these ideas. We synthesized data from a variety of Chesapeake Bay monitoring programs into composite variables expressing ecosystem integrity. The analysis spanned most of the larger Maryland tributaries to the Bay (tidal fresh to mesohaline areas) for nine years (1986–1994). An index modeled on the Index of Biotic Integrity (IBI) and a multivariate ordination and ranking method combined information on aquatic plant, plankton, benthic and fish assemblages with water quality-based habitat goals. The multivariate method proved superior to the IBI approach in discriminating ecosystem integrity. A logistic regression model with watershed land use characteristics and water depth as independent variables explained a significant amount of variation in the multivariate rank index. Urban land use had the most negative effect on the index, whereas forested land had the most positive effect.     

Quantifying nonuse and indirect economic benefits of impingement & entrainment reductions at U.S. power plants

Monetizing ecological benefits of reducing impingement and entrainment (I&E) at cooling water intake structures presents both ecological and economic challenges. Ecological challenges arise because it is difficult to demonstrate and measure these impacts. Economic challenges arise because of these ecological uncertainties and because many of the potentially affected ecosystem services cannot be valued using traditional methods. Under a recently promulgated U.S. regulation certain power generation and industrial water permit applicants may be required to monetize these “nonuse” benefits. However, stated preference (SP) surveys, the only method available for valuing nonuse services have not seen acceptance by mainstream economists. This paper describes an approach to valuation that incorporates the ecological service function approach advocated by the USEPA Science Advisory Board to characterize impacts. Data and models are used to quantify, to the extent possible, direct and indirect impacts of I&E on ecosystem services. Nonuse values are then estimated by an SP survey that measures respondents’ willingness to pay for reducing I&E. Methods are proposed for calibrating and validating results including identifying the source of nonuse values from commonly ascribed motivations (i.e. existence, bequest, altruistic), considering the role of pre-survey awareness of impacts, and evaluating results in the context of respondent willingness to pay for other nonuse benefits.     

太阳能级多晶硅生命周期环境影响评价

采用生命周期评价法对太阳能级多晶硅生产过程的环境影响进行评价. 基于Eco-Indicator99,建立了适用于我国的终点破坏类影响评价模型(Chinese endpoint damage model,CEDM). 对影响评价模型的资源属性参数进行了本地化研究,核算出以2010年为基准年、以我国为基准区域的资源属性本地化人均年度基准值(4.33×105 MJ). 采用现场和问卷调研的方式获得太阳能级多晶硅所有生命周期阶段的能量物质的输入、输出和环境外排数据,调研样本总产量达到2012年全国产量的80%. 结果表明:从环境影响的最终破坏受体来看,太阳能级多晶硅生命周期环境影响主要集中在对人体健康损害方面,占其整个环境影响的72.31%;其次是对资源衰竭方面的影响,占24.23%;对生态系统的损害最小,仅占3.46%. 在所有环境要素中,电的环境影响最高,占79.48%;其次是蒸汽消耗、工业硅原料,二者分别占13.18%、5.97%. 我国太阳能级多晶硅生命周期环境影响是欧洲平均水平的2倍多,主要是受电力结构所致,但在技术先进性和污染防治水平方面要优于欧洲平均水平.      

Intake modifications to reduce entrainment and impingement at Carolina Power & Light Company’s Brunswick Steam Electric Plant,Southport, North Carolina

The Brunswick Steam Electric Plant (BSEP) is a two-unit nuclear station located in the lower Cape Fear River Estuary (CFE) near Southport, NC. Once-through cooling water is withdrawn from the CFE and discharged to the Atlantic Ocean. Estuarine-dependent fish and shellfish species are potentially subject to entrainment and impingement during cooling-water withdrawal. Mitigation technologies include a fish diversion structure (9.4-mm mesh screens) at the mouth of the intake canal to reduce impingement of large organisms, 1-mm fine-mesh traveling screens to reduce entrainment of larvae, a fish return system to return impinged organisms alive back to the estuary, and flow minimization. Installation of the fish diversion structure resulted in a 40% reduction in number and 70% reduction in the weight of larger organisms impinged. Use of fine-mesh screens successfully reduced the number of organisms entrained by as much as 80% depending upon species present. Survival of organisms returned to the CFE ranged from <1% to approximately 92% depending upon species and size class. In addition to monitoring the effectiveness of the intake modifications, over 20 years of extensive environmental studies in the estuary indicate that operation of the BSEP has had no measurable adverse effect on the fisheries of the CFE. The species composition, seasonality, and abundance of organisms using the CFE have not changed as a result of operation of the BSEP.     

电动与内燃机汽车的动力系统生命周期环境影响对比分析

以国内某两款同一车型的电动与内燃机汽车的动力系统为研究对象,通过生命周期分析软件GaBi建立生命周期评价(LCA)模型,在清单数据分析的基础上,采用CML2001模型对两种动力系统分别进行了定量的生命周期环境影响评价.评价结果表明,电动汽车动力系统的全生命周期综合环境影响比内燃机汽车动力系统高60.15％,并分别通过回收阶段分析、电能结构分析和敏感性分析对这一结果进行了解释:回收阶段中酸化、富营养化和光化学臭氧合成3种环境影响类型的直接排放大于回收得到的环境效益;电动汽车动力系统的环境影响随着火力发电比例的下降而减小,增大水能、风力和核能发电在电力系统中所占比例能有效降低电动汽车对环境的影响;动力系统重量对电动汽车动力系统的环境排放影响最为敏感,电池充电效率次之,制造阶段能耗的敏感度最小.将动力系统使用阶段的环境影响分配到整车,则电动汽车的生命周期环境影响比内燃机汽车低0.14％,且主要环境影响类型是全球变暖、酸化和富营养化.     

双碳目标下电力系统转型对产业部门影响评估——以粤港澳大湾区为例

通过细化机组级燃煤发电财务状况建模,测算了提前退役、灵活性调整、限制和停止新增等情景下煤电搁浅资产风险,明确了不同情景下导致搁浅资产规模及时空分布情况.结果表明:存量煤电机组是引起搁浅资产的主体,控制新增煤电有助于降低搁浅资产风险,提前退役、灵活性调整情景下中国现存和新增煤电搁浅资产总规模分别为1.90万亿和3.98万亿元;不同转型情景导致煤电搁浅资产的年际分布差异明显,提前退役搁浅压力主要集中于2030~2040年间,灵活性调整情景下则集中于2021~2035年间;煤电搁浅资产空间分布极不均衡,山东、内蒙古、江苏等10个煤电大省搁浅资产规模占全国的67%和70%.因此,煤电低碳转型需审慎决策,重视提前退役造成的煤电资产搁浅,更要防范和控制灵活性调整导致的煤电资产减值,重点关注山东、内蒙古、新疆、江苏等重点省份,制定因地制宜的煤电转型策略,帮助电力相关企业及政府等进行减排政策选择.     

湿地泥沙环境动态评估方法及其应用研究——(Ⅱ)应用

以1994年和1995年对深圳湾潮间带湿地沉积物进行的基线调查结果为基础，结合1996年至1999年间每年于1、4、7、10月对该湿地9个采样点的沉积物和底栖动物的20次定期采样结果进行分析，得出了深圳湾湿地1996年以来的环境质量变化状况。评价结果表明，深圳福田一侧的环境质量状况保持良好，而香港米埔一侧的环境质量则发生了一定程度的退化。     

基于生态系统健康的生态承载力评价

针对自然生态系统和传统生态承载力研究中评价标准相对单一、评价结果简化、不利于实际应用等问题，提出了基于生态系统健康的生态承载力概念，探讨了其内涵和基本特征；建立了水电梯级开发对生态承载力影响和基于生态系统健康的生态承载力计量模型；给出了基于生态系统健康的生态承载力评价指标体系和标准的确定方法，初步构建了基于生态系统健康的生态承载力理论框架．以黄河流域青海片为研究区域，建立了适合该区域的基于生态系统健康的生态承载力评价指标体系、权重和评价标准，并对青海片内水电梯级建设对生态承载力的影响进行了深入分析．结果表明，黄河流域青海片水电梯级开发规划实施的不同阶段对共和县生态承载力指数均为正面影响．但对青海片和沿黄其它县均为负面影响；梯级开发规划全面实施后，将使青海片的生态承载力指数下降9．9％，生态系统健康等级也将由亚健康状态降至不健康状态。     

Impacts of power-plant cooling systems on estuarine fish populations: the Hudson River after 25 years

In the early 1970s, impacts of power-plant cooling systems on fish populations were a major source of controversy. The most thoroughly studied and controversial power plants were the Indian Point, Bowline, and Roseton generating stations on the Hudson River. The assessments performed for these three plants were unique in employing river-wide sampling data and mathematical models designed to predict the effects of cooling-water withdrawals on the short- and long-term abundance of striped bass and other important fish populations. A Settlement Agreement in 1981 led to the establishment of a long-term monitoring program that continues to generate valuable information concerning the impacts of power-plant cooling systems on estuarine ecosystems. This paper evaluates the results generated by the past quarter century of Hudson River, with the objective of evaluating the utility of the information for future 316(b) assessments. Specific recommendations are made concerning: (1) methods for quantitative assessment of cooling-system impacts at new vs operating facilities; (2) research that would improve the efficiency and accuracy of assessments; and (3) the need to integrate cooling system impact studies into a general framework for management of aquatic ecosystems.