Maryland power plant cooling-water intake regulations and their application in evaluation of adverse environmental impact

Maryland's cooling-water intake and discharge regulations, the Code of Maryland Regulations (COMAR) 26.08.03, stem from Sections 316(a) and (b) of the Clean Water Act (CWA). COMAR 26.08.03.05 and litigative and administrative rulings stipulate that the location, design, construction, and capability of cooling-water intake structures must reflect the best technology available (BTA) for minimizing adverse environmental impacts (AEIs), providing that the costs of implementing the BTA are not wholly disproportionate to the expected environmental benefits. Maryland law exempts facilities that withdraw less than 10 million gallons/day (MGD) and less than 20% of stream or net flow by the intake. If not exempt, BTA must be installed if the cost of doing so is less than five times the value of fish impinged annually. Through site-specific studies and the use of a Spawning and Nursery Area of Consequence (SNAC) model applied to Representative Important Species, several power plants were evaluated to determine if they have had an adverse effect on spawning and nursery areas of consequence. Examples of application of the Maryland law to a number of power plants in the state are presented, together with the outcome of their evaluation.     

Comparing Clean Water Act Section 316(b) policy options

This paper develops a comparative framework for policy proposals involving fish protection and Section 316(b) of the Clean Water Act (CWA). Section 316(b) addresses the impingement and entrainment of fish by cooling-water intake structures used principally by steam electric power plants. The framework is motivated by examining the role of adverse environmental impacts (AEIs) in the context of Section 316(b) decision making. AEI is mentioned in Section 316(b), but not defined. While various AEI options have been proposed over the years, none has been formalized through environmental regulations nor universally accepted. Using a multiple values approach from decision analysis, AEIs are characterized as measurement criteria for ecological impacts. Criteria for evaluating AEI options are identified, including modeling and assessment issues, the characterization of ecological value, regulatory implementation, and the treatment of uncertainty. Motivated by the difficulties in defining AEI once and for all, a framework is introduced to compare options for 316(b) decision making. Three simplified policy options are considered, each with a different implicit or explicit AEI approach: (1) a technology-driven rule based on a strict reading of the 316(b) regulatory text, and for which any impingement and entrainment count as AEI, (2) a complementary, open-ended risk-assessment process for estimating population effects with AEI characterized on a site-specific basis, and (3) an intermediate position based on proxy measures such as specially constructed definitions of littoral zone, sensitive habitat, or water body type. The first two proposals correspond roughly to responses provided, respectively, by the Riverkeeper environmental organization and the Utility Water Act Group to the U.S. Environmental Protection Agency (EPA)'s proposed 316(b) new facilities rule of August 2000; the third example is a simplified form of the EPA's proposed August 2000 new facilities rule itself. The simplified policy positions are compared using the three dimensions of the comparative policy framework: (1) the role of CWA philosophy or vision, such as the use of technology-forcing rules, (2) regulatory policy implementation, and (3) the role for scientific information and the knowledge base. Strengths and weaknesses of all three 316(b) policy approaches are identified. The U.S. EPA's final new facilities rule of November 2001 is briefly characterized using the comparative policy framework and used to further illustrate the approach.     

Adverse environmental impact: 30-year search for a definition

Since passage of the Clean Water Act in 1972, there has been a long, unresolved struggle to define a key phrase in Section 316(b) of the act: "adverse environmental impact" (AEI). Section 316(b) requires that the best technology available be used in cooling-water intake structures to minimize AEI due to entrainment and impingement of aquatic organisms. Various attempts were made to evaluate and define AEI, including focused national conferences on impact assessment. Unresolved arguments regarding AEI were reinvigorated following the 1995 Consent Decree requiring EPA to propose new rules to implement Section 316(b). This article reviews and compares eight proposed definitions of AEI. Six of the definitions define AEI as impact expressed at the population or higher level of biological organization. The two remaining definitions are unrelated to populations: a 1% cropping of the near-field organisms and "one fish equals AEI". The latter definition is based on the desire of some stakeholders to define AEI as the loss of any public trust resources. Equating loss of public trust resources with AEI hampers consensus on a definition because a societal-based policy concept (public trust resources) is commingled with science-based definitions based on population effects. We recommend that a population-based definition of AEI be incorporated into Section 316(b) guidance and observe that this will not preclude a state from exercising its law and policy to protect public trust resources.     

Minimizing adverse environmental impact: how murky the waters

The withdrawal of water from the nation's waterways to cool industrial facilities kills billions of adult, juvenile, and larval fish each year. U.S. Environmental Protection Agency (EPA) promulgation of categorical rules defining the best technology available to minimize adverse environmental impact (AEI) could standardize and improve the control of such mortality. However, in an attempt to avoid compliance costs, industry has seized on the statutory phrase "adverse environmental impact" to propose significant procedural and substantive hurdles and layers of uncertainty in the permitting of cooling-water intakes under the Clean Water Act. These include, among other things, a requirement to prove that a particular facility threatens the sustainability of an aquatic population as a prerequisite to regulation. Such claims have no foundation in science, law, or the English language. Any nontrivial aquatic mortality constitutes AEI, as the EPA and several state and federal regulatory agencies have properly acknowledged. The focus of scientists, lawyers, regulators, permit applicants, and other interested parties should not be on defining AEI, but rather on minimizing AEI, which requires minimization of impingement and entrainment.     

Using attainment of the designated aquatic life use to determine adverse environmental impact

Section 316(b) of the Clean Water Act requires that cooling-water intake structures (CWIS) use Best Technology Available (BTA) to minimize adverse environmental impacts (AEI). The U.S. EPA has not defined AEI, and there is no clear consensus regarding its definition. Nonetheless, operational definitions are necessary to evaluate design alternatives and to measure the success of mitigative measures. Rather than having to develop measures of aquatic health that are highly site-specific, controversial, and often unlikely to elicit agreement from all sides of the environmental "fence", " it may be more productive to use existing ecological assessment tools. Aquatic Life Uses (ALU) already provide a regulatory framework to assess the quality (health) of the aquatic community in various habitats (e.g., warmwater habitat, exceptional warmwater habitat). Attainment of the ALU indicates that further point source controls are unnecessary, whereas nonattainment indicates that those pollutants or stressors causing the nonattainment must be reduced. A similar approach for existing water intakes is recommended. That is, attainment of the designated ALU will be taken as an indication that there is no AEI. Although attainment of the ALU may not be a foolproof indicator of a lack of AEI, this approach seems more reasonable that using scarce monetary resources to fix problems that likely do not exist, or having both regulators and the regulated community expend their resources debating whether various observed biological responses do or do not constitute AEI.     

Modeling possible cooling-water intake system impacts on Ohio River fish populations

To assess the possible impacts caused by cooling-water intake system entrainment and impingement losses, populations of six target fish species near power plants on the Ohio River were modeled. A Leslie matrix model was constructed to allow an evaluation of bluegill, freshwater drum, emerald shiner, gizzard shad, sauger, and white bass populations within five river pools. Site-specific information on fish abundance and length-frequency distribution was obtained from long-term Ohio River Ecological Research Program and Ohio River Sanitation Commission (ORSANCO) electrofishing monitoring programs. Entrainment and impingement data were obtained from 316(b) demonstrations previously completed at eight Ohio River power plants. The model was first run under a scenario representative of current conditions, which included fish losses due to entrainment and impingement. The model was then rerun with these losses added back into the populations, representative of what would happen if all entrainment and impingement losses were eliminated. The model was run to represent a 50-year time period, which is a typical life span for an Ohio River coal-fired power plant. Percent changes between populations modeled with and without entrainment and impingement losses in each pool were compared to the mean interannual coefficient of variation (CV), a measure of normal fish population variability. In 6 of the 22 scenarios of fish species and river pools that were evaluated (6 species x 5 river pools, minus 8 species/river pool combinations that could not be evaluated due to insufficient fish data), the projected fish population change was greater than the expected variability of the existing fish population, indicating a possible adverse environmental impact. Given the number of other variables affecting fish populations and the conservative modeling approach, which assumed 100% mortality for all entrained fish and eggs, it was concluded that the likelihood of impact was by no means assured, even in these six cases. It was concluded that in most cases, current entrainment and impingement losses at six Ohio River power plants have little or no effect at the population level.     

Indicators of AEI applied to the Delaware Estuary

We evaluated the impacts of entrainment and impingement at the Salem Generating Station on fish populations and communities in the Delaware Estuary. In the absence of an agreed-upon regulatory definition of "adverse environmental impact" (AEI), we developed three independent benchmarks of AEI based on observed or predicted changes that could threaten the sustainability of a population or the integrity of a community. Our benchmarks of AEI included: (1) disruption of the balanced indigenous community of fish in the vicinity of Salem (the "BIC" analysis); (2) a continued downward trend in the abundance of one or more susceptible fish species (the "Trends" analysis); and (3) occurrence of entrainment/impingement mortality sufficient, in combination with fishing mortality, to jeopardize the future sustainability of one or more populations (the "Stock Jeopardy" analysis). The BIC analysis utilized nearly 30 years of species presence/absence data collected in the immediate vicinity of Salem. The Trends analysis examined three independent data sets that document trends in the abundance of juvenile fish throughout the estuary over the past 20 years. The Stock Jeopardy analysis used two different assessment models to quantify potential long-term impacts of entrainment and impingement on susceptible fish populations. For one of these models, the compensatory capacities of the modeled species were quantified through meta-analysis of spawner-recruit data available for several hundred fish stocks. All three analyses indicated that the fish populations and communities of the Delaware Estuary are healthy and show no evidence of an adverse impact due to Salem. Although the specific models and analyses used at Salem are not applicable to every facility, we believe that a weight of evidence approach that evaluates multiple benchmarks of AEI using both retrospective and predictive methods is the best approach for assessing entrainment and impingement impacts at existing facilities.     

Use of equivalent loss models under Section 316(b) of the Clean Water Act

Equivalent loss models encompass a variety of life table-based approaches that can be used to convert age- and life stage-specific estimates of entrainment and impingement loss to a common, easily understood currency. This common currency can be expressed in terms of numbers of individuals, yield to the fishery, or biomass to the ecosystem. These models have at least two key uses in the Section 316(b) assessment process: screening for adverse environmental impact (AEI) and determination of environmental benefits associated with intake alternatives. This paper reviews the various forms of equivalent loss models, their data input requirements, and their assumptions and limitations. In addition, it describes how these models can be used as a second-level screening tool as part of the assessment of the potential for AEI. Given their relative simplicity and ease of use, equivalent loss models should prove to be an important tool in the arsenal of impact assessment methods for Section 316(b).     

Uncertainty and conservatism in assessing environmental impact under paragraph 316(b): lessons from the Hudson River case

Initially, regulation of cooling water intakes under paragraph 316(b) was extremely conservative due to the rapid increase predicted for generating capacity, and to the uncertainty associated with our knowledge of the effects of entrainment and impingement. The uncertainty arose from four main sources: estimation of direct plant effects; understanding of population regulatory processes; measurement of population parameters; and predictability of future conditions. Over the last quarter-century, the uncertainty from the first three sources has been substantially reduced, and analytical techniques exist to deal with the fourth. In addition, the dire predictions initially made for some water bodies have not been realized, demonstrating that populations can successfully withstand power plant impacts. This reduced uncertainty has resulted in less conservative regulation in some, but not all venues. New York appears to be taking a more conservative approach to cooling water intakes. The conservative approach is not based on regulations, but in a philosophy that power plant mortality is an illegitimate use of the aquatic resources. This philosophy may simplify permitting decisions, but it does not further the development of a science-based definition of adverse environmental impact.     

A process for evaluating adverse environmental impacts by cooling-water system entrainment at a California power plant

A study to determine the effects of entrainment by the Diablo Canyon Power Plant (DCPP) was conducted between 1996 and 1999 as required under Section 316(b) of the Clean Water Act. The goal of this study was to present the U.S. Environmental Protection Agency (EPA) and Central Coast Regional Water Quality Control Board (CCRWQCB) with results that could be used to determine if any adverse environmental impacts (AEIs) were caused by the operation of the plant's cooling-water intake structure (CWIS). To this end we chose, under guidance of the CCRWQCB and their entrainment technical working group, a unique approach combining three different models for estimating power plant effects: fecundity hindcasting (FH), adult equivalent loss (AEL), and the empirical transport model (ETM). Comparisons of the results from these three approaches provided us a relative measure of confidence in our estimates of effects. A total of 14 target larval fish taxa were assessed as part of the DCPP 316(b). Example results are presented here for the kelp, gopher, and black-and-yellow (KGB) rockfish complex and clinid kelpfish. Estimates of larval entrainment losses for KGB rockfish were in close agreement (FH is approximately equals to 550 adult females per year, AEL is approximately equals to 1,000 adults [male and female] per year, and ETM = larval mortality as high as 5% which could be interpreted as ca. 2,600 1 kg adult fish). The similar results from the three models provided confidence in the estimated effects for this group. Due to lack of life history information needed to parameterize the FH and AEL models, effects on clinid kelpfish could only be assessed using the ETM model. Results from this model plus ancillary information about local populations of adult kelpfish suggest that the CWIS might be causing an AEI in the vicinity of DCPP.     

Approach velocity and impingement duration influences the mortality of juvenile Golden Perch (Macquaria ambigua) at a fish exclusion screen

Globally, the extraction and diversion of water from river systems has had substantial impacts on aquatic ecosystem health and ecological processes. One such impact is the entrainment of fish at pump offtakes that can result in vast quantities of fish being permanently removed from rivers. Exclusion screens to prevent fish entrainment at pump offtakes are therefore an important management consideration. In this study, impingement and subsequent injury and mortality of a juvenile freshwater perciform, Golden Perch (Macquaria ambigua), was assessed in the laboratory using a simulated fish exclusion screen under a range of velocities and impingement durations. A 2 mm wedge‐wire screen eliminated the entrainment of 44‐day‐old Golden Perch that were exposed to approach velocities between 0.05 and 0.3 m/s. However, impingement rates of Golden Perch increased significantly with increased approach velocities and rates of injury and mortality increased with impingement duration. Results from this study indicate the primary mechanisms to reduce fish loss at pump offtakes are to design pump offtakes, fitted with fish exclusion screens, which limit approach velocities or impingement duration. Further studies are required to examine a range of species with varying swimming ability at early life‐history stages. Such data will contribute to the growing body of knowledge that supports adaptive management plans to prevent fish loss at water offtake pumps.     

A review and assessment of the potential use of RNA:DNA ratios to assess the condition of entrained fish larvae

In rivers, lakes, and other aquatic systems throughout the world, intake pipes withdraw huge volumes of water for industrial purposes, including power plant cooling. During this process, large numbers of small-bodied, early life-stages of fish are pulled into pipes (i.e., entrained) and may be subjected to physical, thermal and chemical stress. As a result of such entrainment, these organisms can suffer direct or indirect mortality. However, given that the vast majority of larval fish are likely to die during early life due to natural processes, it is not obvious that entrainment-related mortality will have a strong influence on subsequent adult population sizes. The ability to evaluate if larval fish are dead on arrival, moribund, or in poor condition (i.e., likely to die through natural processes) at the time of entrainment could shed light on likely population-level impacts. To this end, we review the potential use of RNA:DNA ratios to index condition of entrained larval fish. Through a meta-analysis of published research studies, we demonstrate that RNA:DNA ratios of larval fish are responsive to starvation stress, with effect size increasing with duration of starvation. We relate these results to a surrogate measure of irreversible long-term negative impacts to fish populations, and demonstrate that the timescale over which RNA:DNA ratios respond to stress may not be long enough to reflect before-and-after entrainment stress. We also highlight the diverse factors contributing to variation of RNA:DNA ratios, including methodological, ontogenetic, and thermal influences. We believe that the need to account for these influences when comparing among RNA:DNA values limits the utility of broadly using RNA:DNA ratios to evaluate entrainment effects. However, the method shows promise as a quick and efficient means of determining fish condition and, used in proper context (e.g., specific to a given set of environmental conditions; in conjunction with other assessment techniques), may provide a powerful tool in assessing the effects of entrainment on fish populations. Assuming that researchers can account for sources of background variation, RNA:DNA analyses may be most useful for assessing the condition of fish larvae susceptible to entrainment (i.e., physically in the vicinity of the water intake) and/or evaluating whether fish larvae are likely to die from natural processes independent of entrainment.     

A feasibility analysis of discharge of non-contact,once-through industrial cooling water to forested wetlands for coastal restoration in Louisiana

Louisiana has had a high rate of coastal wetland loss due mainly to the isolation of the Mississippi River from the deltaic plain. We conducted a feasibility analysis of using once-through, non-contact industrial cooling water for restoring subsiding forested wetlands in coastal Louisiana. We considered the impacts of heated water and high nutrient and sediment concentrations. River diversions introduce sediments and nutrients to stimulate the productivity and accretion of coastal wetlands. Since increases in sediments and nutrients can cause water quality problems, we analyzed the assimilative capacity of the swamp. Based on a loading rates analysis, we estimated that the following nutrient reductions would occur: 75% for NO₃, 50% for TN, 60–75% for TP, and 100% for suspended sediments. Because of the concern of impacts from heated water, it is likely that the temperature of the cooling water will have to be decreased before discharge. Altering the duration and location of the discharge are ways to minimize the impact of temperature. We recommend that a pilot study be carried out to determine the effects of heated water on the functioning of the system, the retention of sediments and nutrients, and the impacts of different discharge scenarios.     

Effects of entrapment and cooling water discharge by the Bergum Power Station on 0+ fish in the Bergumermeer

The numbers, distribution and size of 0+ fish in Bergumermeer and in the cooling water system of the Bergum Power Station were registered from 1978 to 1981. An exponentially decreased vulnerability to entrapment by the power station was found with increasing size of fish. Because of the large water intake in relation to the lake volume, entrainment mortality of fish larvae in May and June is large and probably of the same order of magnitude as the natural mortality. In the same period the Bergumermeer can be supplied with large amounts of fish larvae, immigrating passively with the water current. Impingement mortality later on in the season is insignificant compared with natural mortality. The heated effluents from the power station influence the distribution and the size of 0+ fish in the lake. Year-class strength of pikeperch may be improved due to the larger size of 0+ pikeperch. Less water intake as a possibility to minimize entrainment is discussed.     

Defining "adverse environmental impact" and making paragraph 316(b) decisions: a fisheries management approach

The electric utility industry has developed an approach for decisionmaking that includes a definition of Adverse Environmental Impact (AEI) and an implementation process. The definition of AEI is based on lessons from fishery management science and analysis of the statutory term "adverse environmental impact" and is consistent with current natural resource management policy. The industry has proposed a definition focusing on "unacceptable risk to the population"s ability to sustain itself, to support reasonably anticipated commercial or recreational harvests, or to perform its normal ecological function." This definition focuses not on counting individual fish or eggs cropped by the various uses of a water body, but on preserving populations of aquatic organisms and their functions in the aquatic community. The definition recognizes that assessment of AEI should be site-specific and requires both a biological decision and a balancing of diverse societal values. The industry believes that the definition of AEI should be implemented in a process that will maximize the overall societal benefit of the paragraph 316(b) decision by considering the facility"s physical location, design, and operation, as well as the local biology. The approach considers effects on affected fish and shellfish populations and the benefits of any necessary best technology available (BTA) alternatives. This is accomplished through consideration of population impacts, which conversely allows consideration of the benefits of any necessary BTA modifications. This in turn allows selection of BTAs that will protect potentially affected populations in a cost-effective manner. The process also employs risk assessment with stakeholder participation, in accordance with EPA's Guidelines for Ecological Risk Assessment. The information and tools are now available to make informed decisions about site-specific impacts that will ensure protection of aquatic ecosystems and best serve the public interest.     

Effects of Entrainment on Phytoplankton Primary Production at Four Thermal Electric Generating Stations on the Laurentian Great Lakes

Primary production was used to measure the response of phytoplankton to entrainment in once-through cooling water at thermal electric generating stations. Ambient lakewater temperatures ranged from 1.0 to 20.5 °C. The maximum discharge temperature was 32.0 °C. There was no chlorination of cooling water at the stations studied. On a few occasions, primary production was stimulated following station passage by discharge temperatures which were approximately 10 °C above ambient lakewater temperatures of 4.5 to 8.5 °C. Differences in production levels were not apparent, however, following the return of discharge water to ambient lakewater temperature. There was no consistent response of phytoplankton to the temperature regimes tested, with production levels generally differing by less than 20 % as a result of station passage or temperature elevation alone. Entrainment was considered to have minimal impact on phytoplankton productivity in large open water bodies such as the Great Lakes.     

Assessing the Effects of Climate Change on Waterborne Microorganisms: Implications for EU and U.S. Water Policy

Despite advances in water treatment, outbreaks of waterborne diseases still occur in developed regions including the United States and Europe Union (EU). Water quality impairments attributable to elevated concentrations of fecal indicator bacteria, and associated with health risk, are also very common. Research suggests that the impact of such microorganisms on public health may be intensified by the effects of climate change. At present, the major regulatory frameworks in these regions (i.e., the US Clean Water Act [CWA] and the EU Water Framework Directive [WFD]), do not explicitly address risks posed by climate change. This article reviews existing U.S. and EU water quality regulatory legislation for robustness to climate change and suggests watershed modeling approaches to inform additional pollution control measures given the likely impacts on microbial fate and transport. Comprehensive analysis of future climate and water quality scenarios may only be achievable through the use of watershed-scale models. Unless adaptation measures are generated and incorporated into water policy, the potential threat posed to humans from exposure to waterborne pathogens may be amplified. Such adaptation measures will assist in achieving the aims of the EU WFD and US CWA and minimize impacts of climate change on microbial water quality.     

Comparison of fish impingement by a thermal power station with fish populations in the Ems Estuary

On an annual basis >10 million individuals of c . 35 fish species are impinged at the EC20 unit of the Eems power station located on the Ems Estuary. The most abundant are: herring Clupea harengus , gobies ( Gobiidae ), Nilsson's pipefish Sygnathus rostellatus , three-spined stickleback Gasterosteus aculeatus and sprat Sprattus sprattus . The impingement shows a seasonal pattern which reflects the presence of the fishes in the estuary. The results are compared with other impingement studies at power stations on the Belgian and Dutch estuaries.
In 1995, the cooling water entrance was displaced from the shoreline to 300 m off the coast at the edge of the tidal channel. The effect of this relocation on the level of fish impingement, determined by comparing the ratio of fish density in the cooling water and in the estuary before (1992–1993) and after (1996–1997) the relocation of the intake canal is discussed.     

When You Find Yourself in a Hole, Stop Digging: Comments on Earth Systems Engineering

In an earlier "Forum" article in this journal, Brad Allenby outlined his views of a new approach to managing the unintended consequences of human activity, "earth systems engineering." He argues that we must develop the tools, institutions, and moral and ethical systems to allow us to "assume an active management role for most global systems." I believe this to be a significant departure from a core concept of industrial ecology: learning from ecosystems how the natural world operates to be able to more effectively design and manage coupled human-natural systems. Such lessons are more likely to lead away from tightly managed, centralized approaches, and favor approaches with as little intervention as feasible. More important, I believe that we are far less likely to learn how to implement earth systems engineering than simpler approaches, hence less likely to minimize environmental damage.     

Selective effects of phytoplankton entrainment at the Surry Power Plant,James River,Virginia

Loss of cryptophyte cells entrained in the Surry Power Plant cooling water was significantly correlated with discharge water temperature in the range 27.2–37.5 °C. Entrained Skeletonema costatum and benthic diatom populations experienced losses of 25–80% in the summer, but correlations between % loss and discharge temperature were insignificant. Cropping by benthic filter feeders in the intake and discharge canals could account for the summer removal of diatoms. Shortening of entrained S. costatum chains was detected in both winter and summer, indicating a mechanical effect of turbulence.Benthic diatoms were vulnerable to entrainment only during daylight hours, when they migrated to the sediment surface at low tide. Skeletonema costatum was most vulnerable in the summer, when elevated salinities permitted it to range upstream to the intake area. Cryptophyte populations peaked in the summer when entrainment loss was greatest.The composition of the entrained phytoplankton community was altered by the species specific interactions of factors affecting vulnerability and entrainment loss. At Surry the discharged cooling water mixes rapidly with the main stem James River, and the selective effects of entrainment are not detectable in phytoplankton samples taken beyond the immediate discharge zone. More persistent modifications of the phytoplankton could be expected at sites where power plants discharge into creeks or embayments.Contribution No. 1106, Virginia Institute of Marine Science.Contribution No. 1106, Virginia Institute of Marine Science.