Section 316(b) of the Clean Water Act: Cooling Water Intake Structure Regulations

August 5, 2002

Cooling Water Intake Structure (Existing Facilities: Phase II)
Proposed Rule Comment Clerk-W-00-32
Water Docket, Mail Code 4101
U.S. Environmental Protection Agency
Ariel Rios Building
1200 Pennsylvania Avenue, NW
Washington, D.C. 20460

Subject: State of Maryland Comments on Proposed Regulations to Establish Requirements for Cooling Water Intake Structures at Phase II Existing Facilities; Proposed Rule, Published Federal Register, April 9, 2002

Dear Sir/Madam:

This letter presents the official comments of the State of Maryland on the Environmental Protection Agency’s 40 CFR Parts 9, et al. National Pollutant Discharge Elimination System Proposed Regulations to Establish Requirements for Cooling Water Intake Structures at Phase II Existing Facilities; Proposed Rule, issued by EPA on April 9, 2002.

As we have stated in prior comments on other EPA proposed cooling water intake structure regulations, the State of Maryland (specifically the Maryland Department of Natural Resources (MDNR), Power Plant Research Program (PPRP) and the Maryland Department of the Environment (MDE)) is proud of its strong commitment to environmental protection as demonstrated in its efforts to restore and protect the Chesapeake Bay. This commitment is also evidenced by the creation of the Power Plant Research Program (PPRP), an agency unique among states. PPRP is charged with assessing and advising the state regarding the environmental and economic considerations associated with the siting, design and operation of electric generation facilities in Maryland. PPRP provides technical support in power plant impact assessment to MDE, the state's permitting agency. MDE has responsibility for issuing and enforcing compliance with NPDES permits in the state.

PPRP has since its inception conducted technical reviews of power plant environmental impact issues and developed recommendations to MDE relating to Maryland’s regulations applicable to Cooling Water Intake Structures (CWIS). PPRP has worked cooperatively with MDE, in reviewing all data and information submitted to MDE by power plant owners and operators. In many instances the state has conducted research independent of permittees, to assess impacts and/or evaluate the efficacy of technologies to reduce those impacts. The comments provided here are based on PPRP's nearly 30 years of experience and our very diverse yet comprehensive studies of the manner in which cooling water withdrawals have impacted aquatic biota, in particular fisheries, in Maryland's waters.


As an EPA-delegated state, in the late 1970s Maryland developed and implemented regulations of cooling water withdrawal and intakes in accordance with EPA guidance on implementation of Clean Water Act Section 316b provided at that time. Code of Maryland Regulations,, establish procedures for determining adverse environmental impacts due to impingement and entrainment at cooling water intake structures, relative to determination of best technology available (BTA) for minimizing these impacts. These regulations were based on scientific and technical knowledge of the factors influencing the type and magnitude of impacts expected to occur, and followed a logical conceptual framework.

The basic elements of that framework include:

  • the evaluation of entrainment impact to a specified level of biological significance; i.e., representative important species (RIS) and spawning and nursery areas of consequence for the RIS

  • a determination of the significance of the entrainment impact that is based on the extent to which the direct effects of the CWIS impact the viability of the RIS population and/or the ecosystem necessary to support its life history functions; the direct effect of the cooling water intake (i.e., the number of fish impinged or entrained) is not the major focus of our regulations; it is the consequence of that effect to the biological entity of concern, whether at the species or the ecosystem level, that establishes what actions the state will take

  • a determination of BTA for impingement based on a simple cost/benefit analysis, comparing the value of fish lost to impingement to the cost for intake restructuring

We continue to believe that a sequential approach to impact assessment is a good generic approach to the issues involved. The steps in such a sequence are:
  • quantify the direct effects of the cooling water withdrawal,

  • establish the biological entities that may be at risk, and

  • assess the significance of the direct effects for causing adverse harm to the target entity

Under Maryland regulations, the value of impingement losses is determined by estimating the number of each species destroyed by the CWIS and multiplying these numbers by the values for each species listed in the regulations. These dollar values are then adjusted by weighting factors based on the species function, i.e., recreational, commercial, forage. Entrainment losses are more difficult to define. The discharger is required to determine the extent of cooling water entrainment loss on a spawning or nursery area of consequence for Representative Important Species (RIS) as defined in the regulations. The discharger is required to determine if the entrainment loss results in a significant adverse environmental impact, defined as meaning a statistically measurable effect beyond a defined mixing zone. RIS are those species selected by a discharger and approved by the state that exhibit one or more of the following characteristics:
  • Species that are sensitive to adverse harm from operations of the facility (for example, heat-sensitive species)

  • Species that use the local are as spawning or nursery grounds, or both, including those species that migrate past the facility to spawn

  • Species of commercial or recreational value, or both

  • Species that are habitat formers and are critical to the functioning of the local ecosystem

  • Species that are important links in the local food web

  • Rare, threatened, or endangered species, or

  • Potential nuisance organisms likely to be enhanced by plant operations.

There are 12 existing power generating facilities in Maryland that have permits allowing for cooling water withdrawals greater than 50 mgd and which would potentially be covered by the Phase II rule. Several of these facilities may be retired prior to the establishment of the new rule (e.g., Gould Street and Riverside); the Westport facility has already been retired except for one combustion turbine which does not use cooling water. Two of the remaining nine facilities withdraw water from a freshwater river (R.P. Smith and Dickerson on the Potomac) while the remaining seven withdraw water from the Chesapeake Bay or one of its tidal tributaries. Only Brandon Shores uses wet cooling towers exclusively, with all of the remaining facilities permitted for once-through cooling. All of these facilities had 316(b) demonstration studies conducted in the late 1970's or early 1980's and all were eventually found to be in compliance with Maryland’s 316(b) requirements. In order to attain compliance, some facilities were required to conduct additional studies to determine the extent of their entrainment and impingement (E&I) impacts and one (Chalk Point) was required to mitigate its impacts. Since the original 316b BTA determinations for these facilities, Maryland has found no basis for reconsideration of those determinations or for requiring additional intake modifications.

In the proposed rule, EPA has identified a number of issues for which comment is solicited. We have reviewed the rule and listed CWA issues of relevance to Maryland. Our comments note the section and page of the proposed rule.

In addition to the specific portions of the proposed rule for which EPA seeks comment, Maryland has identified a number of issues which were not specifically addressed in the proposed rule that we consider to be of particular importance to our state. We discuss those issues in a separate section following our comments on specifically identified elements of the proposed rule.

In summary, the State of Maryland believes that our existing 316(b) CWIS regulations have been and continue to be protective of the environment and the State’s natural resources. For this reason, we suggest that the Phase II rule include the option of a State’s existing regulations being accepted as satisfying 316b requirements. We strongly support a site-specific approach for determining BTA to minimize Adverse Environmental Impacts (AEI). We also believe that AEI should be considered at the species or ecosystem-effects levels and not simply on the numbers of organisms entrained and impinged.

The State of Maryland appreciates the opportunity to participate in this important rulemaking. We hope that these comments, based on our 27 years of experience, will prove useful to EPA in making its final rule for existing large facilities.


Richard I. McLean,
Energy Resource Administrator
Maryland Department of Natural Resources
Power Plant Research Program

J. James Dieter,
Wastewater Permits Program Administrator
Maryland Department of the Environment
Water Management Administration


cc: J. Charles Fox, DNR and Merrylin Zaw-Mon, MDE

Maryland Comments on Individual Elements of the Proposed Rule

1. 50 MGD and 25% cooling water use as thresholds for application of the rule (II.B:17130)
    Because the 50 MGD cut off is used to establish whether a facility should be covered under the Phase II or Phase III rule, the exact figure used for that cutoff is not of major concern. The 50 MGD withdrawal rate seems to be a reasonable criteria for separating the large, once-through cooling facilities from smaller cooling water users, as does the 25% cooling water use threshold.

2. Cumulative impacts of multiple intake structures in same watershed and in already impaired waterbody; effects of multiple intakes on fish stocks (V: 17136)
    PPRP has evaluated cumulative effects of impingement and entrainment in Maryland. Because Maryland generating facilities have a rather broad geographical distribution, the biological populations exposed to the effects of these widespread plants are often distinct, with little or no intermingling. For example, species such as white perch and striped bass have tributary-specific stocks, such that impingement of white perch at the Morgantown facility on the Potomac River is of no biological consequence for white perch stocks in the vicinity of the Vienna facility on the Nanticoke River. Conversely, other species, such as Atlantic Menhaden (Brevortia tyrannus) may have a single stock that moves throughout the Chesapeake Bay. Thus, the total number of menhaden impinged at all of the power plants in Maryland is of potential relevance to the fate of the single menhaden stock. Maryland has tracked cumulative impingement losses across all power plants for species, such as menhaden, that may occur over a wide range of salinity regimes. However, in lieu of complicated and imprecise population modeling, the losses due to impingement were simply compared to other sources of menhaden loss to place them within a reasonable context. These comparisons showed that the cumulative magnitude of impingement of menhaden, as an example, is a small fraction of the commercial harvest of the species, and a small fraction of estimates of the amount of this species consumed by predators. On that basis, the state has concluded that the levels of impingement by Maryland's power plants do not represent a significant threat to this important resource species in the bay.

    If an adverse cumulative impact to a watershed ecosystem is suspected or indicated, we recognize that considerable uncertainties may exist in the identification of individual contributors to the problem and the assignment of responsibility for ameliorating these impacts. Our research into this issue (Hochberg et al., 1993) has indicated that the lack of a regional land use or water quality management plan would make it difficult to sort out effects of power plants from other influences. In the absence of knowledge about other influences on the receiving water body or ecosystem, any assessment of cumulative impact and the effect of a single action (e.g., discharge permit approval) would be flawed. Minimizing the effects of power plants within a watershed would reduce the likelihood that such plants could contribute to environmental degradation. However, we believe that to require facility owners, and thus consumers, to incur substantial cost to do so when the benefits of such measures are unknown would be unreasonable. For this reason, Maryland has continued to support the concept of site- and facility-specific impact assessments, including those relating to cumulative impacts.

    With regard to Maryland's experience, cumulative impacts have been temporally addressed implicitly within the State through long-term monitoring of the status of important resource species. None of these diverse monitoring programs have suggested that an adverse cumulative impact to the State’s fisheries have resulted from the effects of power plants operating in Maryland (Richkus and McLean, 2000; Ringger, 2000).

    With regard to use of watersheds as the basis for evaluating cumulative impacts of multiple facilities, cumulative impacts would only occur in circumstances where the multiple facilities are likely to be impacting the same ecosystem elements. For example, the effects of plants located on non-tidal waters in a watershed are unlikely to have impacts that would be cumulative to those of plants located on tidal portions of the same watershed (except with the possible exception of diadromous fish). We believe that cumulative impacts should be considered on the basis of affected resources and not simply on a watershed basis.

3. Ecosystem level effects (food webs, nutrient-carbon-energy transfers, habitat alteration, species composition and biodiversity alteration) (V: 17137)
    The diverse array of ecosystem level effects that are discussed in this portion of the proposed rule appear to be very speculative in nature, with minimal scientific support and citations. PPRP has conducted numerous studies of all ecosystem components at most of the generating facilities in Maryland over the past thirty years. We have recorded one clear ecosystem consequence of once-through cooling: benthic communities in the vicinity of power plant discharges tend to be enhanced (e.g., higher biomass densities), most likely due to increased availability of food in the form of planktonic organisms killed as a result of entrainment and settling out of the water column in the discharge area. This ecosystem response is restricted to a relatively small region, consisting of the immediate vicinity of the discharge plume. It is not inherently an adverse impact, since benthic organisms are an important food source for many of Chesapeake Bay’s important resource species, such as blue crab and many fish species. From all other studies, no effects on other ecosystem elements have been noted, and no long term alterations in ecosystem structure or function have been observed that could be attributed to power plant operations (CEIR, 1986). Thus, we do not believe that existing data, information and literature support the occurrence of the speculative ecosystem level effects you describe.

4. Require greatest possible reduction based on EPA’s performance standard technologies or allow performance level decision to be made by the Director (VI..A.1.a: 17142)
    The specification of a performance level, in the absence of knowledge of what the benefits of performing at that level may be, could place an undue burden on plant owners, the states, and consumers. We believe that the Director would be more likely to have the local knowledge needed to make a reasoned decision on what performance level would be acceptable. Thus, we strongly support having the Director assume responsibility for determining the appropriate performance level.

5. Appropriateness of “significantly greater” cost test for evaluating alternative requirements (Site-specific determination) (VI..A.4: 17146)
    Maryland concurs with EPA’s decision to utilize a “significantly geater” cost test in this Phase II rule. We agree that, for existing facilities, cost of retrofit should be a major factor to be considered in determining BTA. However, we have not done a detailed review of the basis for the costs in EPA’s record to determine whether they are reasonable and valid.

6. Allow restoration measures only as a supplement to technology or operational measures (VI..A.5: 17146)
    Designation of restoration measures only as supplements to technology or operational measures may be too restrictive. There may be circumstances in which the cost of technology or operational measures to achieve modest environmental gains is very high, in which case much greater benefit to the State’s resources could result from use of those same funds purely for restoration or resource enhancement. Thus, Maryland would prefer to retain restoration on a case by case basis as an acceptable alternative to technology or operations measures and not just as a supplement.

7. Appropriate spatial scale for restoration measures: waterbody, watershed, State boundary (VI..A.5: 17146)
    We believe it is reasonable to implement restoration measures within the same ecosystem and watershed within which the generating facility is located. This would be the most direct means of ensuring that the ecosystem and stakeholders with interest in the ecosystem (e.g., residents, fishermen) would be compensated for whatever impacts the generating facility may be having, even if that compensation is out-of-kind. An example within Maryland of such acceptable and beneficial restoration is PEPCO funding of anadromous fish migration blockages in the Patuxent River watershed as mitigation for entrainment (discussed in detail in comment 9 below).

8. Nature and extent of consultations with Federal, State, and tribal fish and wildlife agencies and information to be included in consultation request to Fish and Wildlife agencies (VI..A.5: 17146)
    While we believe that a state’s resource agencies would generally have the most comprehensive knowledge of the status of species potentially affected by a CWIS, other agencies, such as USFWS and NMFS, share regulatory authority for management of many species with the individual states. Requiring consultation by the permitee with such agencies on power plant impacts would make the 316b rules consistent with other federal regulations that deal with environmental impacts, such as NEPA. Such consultation would also bring to the process the special expertise often available from these other agencies.

9. How to measure “substantially similar performance” of restoration measures; methods to reduce uncertainty of restoration activities; margins of safety for restoration measures, basis for safety margins, appropriate authority to establish; how to consider additional environmental benefits to fish and shellfish in restoration projects; role of restoration in addressing CWIS impacts and alternative approaches (VI..A.5: 17147, 17148)
    We believe that mitigation can play a valuable role in resolution of 316(b) issues on a site-specific basis. We use the term mitigation here to refer to something aside from alternative intake technologies or operating strategies which might be used to minimize impacts of cooling water intakes. The mitigation we refer to takes the form of some alternative measure which can compensate for resource losses in some other way.

    Empirical studies of entrainment at Chalk Point (formerly owned by Potomac Electric Power Company or PEPCo, now Mirant) indicated the potential for significant losses of forage species (bay anchovy, naked goby, silversides) in the Patuxent River estuary. Such losses can inhibit the successful completion of the life cycles of other important species that use the Patuxent as a spawning and nursery area (MMES 1985). Based on field studies, PEPCo concluded (Loos and Perry, 1989) that the reduction in anchovy recruitment for the Patuxent was 4% and that entrainment mortality could cause a reduction in forage fish biomass of about 3,000 to 15,000 pounds (dry weight). These estimates were based on field measurements of population size in the Patuxent and entrainment by Chalk Point. An independent analysis conducted by the state of the same data indicated that loss of bay anchovy in the estuary due to entrainment was approximately 14 to 51% (most probably 20 to 30%) annually (Versar, 1989). PEPCo (Loos and Perry, 1989) calculated the value of the entrainment losses at $150,000 per year (1989 dollars) based on its loss estimates. PEPCo also calculated the cost of BTA alternatives (cooling towers and wedgewire screens) as ranging from $10,000,000 to $288,000,000 (1989 dollars). According to PEPCo, the alternatives evaluated varied in effectiveness in reducing entrainment from almost none to 100%. Maryland negotiated a mitigation plan in discussions with PEPCo. This plan was developed as a result of a number of factors, including the fact that there was a substantial difference between the cost of requiring BTA (such as cooling towers) and the environmental benefits. There was also substantial uncertainty regarding the magnitude of benefits and the nature of the impacted species. The negotiated settlement resulted in an NPDES permit requirement that PEPCo spend $200,000 per year on striped bass aquaculture or other species as requested by the Maryland Department of Natural Resources (DNR), and $50,000 per year for aquaculture of yellow perch or other species as agreed upon by DNR. This permit condition contemplated the production of 200,000 striped bass and 50,000 yellow perch per year. The permit additionally required PEPCo to provide $100,000 per year to the state for environmental education or for projects to remove obstructions to anadromous fish.

    We believe a sound decision was made based on the success of this mitigation program. In this case, this program included creating a fish hatchery for potentially impacted fisheries and provision of funds for removal of obstructions to migratory fishes on tributaries, by removing dams or providing fish passage facilities. Results of the hatchery and stocking program resulted in the production and release of 3.5 million juvenile striped bass to date, the total estimated weight of which exceeded the estimated weight of forage fish lost from entrainment at Chalk Point. At the end of 1997, 750,000 shad had also been produced; this species is currently the focus of fishery restoration efforts in Maryland. Each of these benefits is directly related to the enhancement of the State's fisheries. However, no specific “valuation” approach was used to arrive at the enhancement objectives; the agreement on numbers of fish to be reared and amount of funds to be used for passage enhancement were based on technical expertise of agency staff and PEPCo staff and consultants , and targeted the State’s resource management objectives.

    We believe that a critical component of the regulation is to assure the provision of substantial flexibility to allow States to direct restoration and enhancement measures to their most pressing resource management needs. Placing rigid, restrictive criteria within the regulation would impose constraints on regulators that may not result in the greatest benefits to resources of concern and the resources of the states that are impacted.

10. Narrative criteria sufficient to support various BTA approaches to minimize AEI; require specific, minimum monitoring frequencies and consider uncertainty in I&E estimates; require 2 years of monitoring, at least once per month for 24 hours for I and biweekly for 24 hours for E during critical periods; require more frequent sampling to assess diel, seasonal and annual variation in I&E losses; less frequent monitoring for compliance, depending on technologies implemented (VI..A.6.a: 17148, 17149)
    EPA notes the difficulties that are encountered in monitoring CWIS impacts, and Maryland’s experience supports EPAs views on this issue. Because of the great diversity of natural conditions that could impact the accuracy and precision of estimates of CWIS impacts, we believe that it may be more appropriate to specify monitoring goals (e.g., certain levels of precision or documentation of impacts during a spawning season) and allow permittees to propose the means of achieving those goals. This would provide the flexibility needed to design monitoring programs that take into account site-specific environmental conditions. Setting any specific minimum sampling frequencies runs the risk of either “overkill” or insufficient sampling. Sampling designs can be reviewed by the Director to determine if they are sufficient to meet the objectives of the regulation.

11. Approaches to estimate entrainment mortality for compliance with performance standard; studies documenting entrainment survival rates (VI..A.7: 17149); review of quality of entrainment survival studies and inclusion of entrainment mortality and survival estimates in benefits assessment (VI..A.8.a.(3).b: 17150)
    Maryland is aware of many of the entrainment survival studies conducted at facilities throughout the country in the 1970s and 1980s. One point to be made regarding these studies is that it is the nature of the power plant’s cooling system rather than the nature of the CWIS that primarily determines the extent of entrainment mortality. Due to the diverse nature of these studies and the high degree of variability in some of the results, Maryland has in the past taken a conservative approach in our assessment of entrainment by assuming 100% mortality of all entrained organisms. We took this approach because the objective of our assessment was to determine whether the direct effects of entrainment might result in significant impact to the designated RIS species or ecosystem function. As we described earlier, most of our assessments lead us to conclude that entrainment effects did not result in significant impacts. The potential for substantial survival of entrained organisms becomes significant when the total number of organisms lost to entrainment is the focus of an assessment (e.g., in determining the economic value of entrainment losses). In such circumstances, we believe it appropriate to take into consideration the fact that all entrained organisms may not be killed. However, the onus is clearly on the permitee to provide scientifically valid support for such a position.

12. Appropriate methodology for benefits assessment (VI..A.8.a: 17149)
    The procedure defined in Maryland regulations for determining BTA for impingement employs a very simple cost/benefit evaluation. The value of fish killed due to impingement is calculated using the dollar values of the affected species that are also included in Maryland regulation. The American Fisheries Society (AFS) has issued and regularly updates a listing of fish species and their dollar value, and these values are commonly used throughout the country in assessing dollar value damages in cases of environmental perturbations that result in fish kills (e.g., spills of toxic compounds). We believe there is thus precedence for use of the AFS fish values for calculating benefits of BTA. We believe that there is a high degree of uncertainty and controversy with regard to the many methods that have been developed to estimate non-use values of living resources, and thus do not strongly support their use in this regulation. However, we have not conducted a detailed review of the economic valuation procedures used by EPA in developing this Phase II rule.

13. Allow states to require more stringent measures where recovery of a species or community could be delayed without these measures (VI..A.9: 17151)
    Maryland believes that states should be permitted to require more stringent measures where necessary to protect key species.

14. Adequacy of 5% flow threshold in rivers or alternative of: 5% of spawning season flow, 10-15% of mean annual or spawning season flow, or 25% of the 7Q10, species-specific flow threshold (VI..A.11: 17151)
    This issue is only potentially applicable in Maryland to the two plants located on the riverine portion of the Potomac River (Dickerson and R.P. Smith). For the Dickerson facility, 5% of the spawning season flow is 614 cfs in May, based on USGS Point of Rocks flow data; 10-15% of the mean annual flow is 951-1427 cfs; 25% of the 7Q10 is 215 cfs. Based on these flow ranges, the Dickerson facility could be subjected to entrainment reduction requirements depending on which criterion is chosen (maximum plant intake flow is about 400 mgd or about 620 cfs). Yet entrainment data collected at that facility has lead Maryland to conclude that no significant impacts result from entrainment. Any of these criteria are by their very nature arbitrary. For this reason, Maryland believes that it is more reasonable to consider the magnitude of entrainment and how that entrainment might affect a fish community rather than using an arbitrary flow cutoff percentage.

15. Allow State to demonstrate adoption of alternative regulatory requirements with comparable environmental performance in I&E reduction within a watershed (VI..A.11: 17151)
    The State of Maryland believes its regulations are protective of its natural resources and would like the opportunity to demonstrate that its regulations are of comparable environmental performance. However, it is not at all clear how a state would be able to make such a demonstration short of re-evaluating all of its facilities. EPA needs to provide clear and reasonable guidance to states on how they may make this demonstration if they desire to do so. Such guidance must be economically reasonable for the state to implement.

16. Appropriate definition of watershed for achievement of comparable environmental performance (VI..A.11: 17151); use of USGS 8-digit hydrologic unit as maximum geographic scale for alternative requirements; appropriate watershed scale definition and boundary of watershed units at State boundary unless adjoining states jointly propose alternative requirements (VI..A.11: 17152)
    We addressed this issue under item 2 above. As we noted there with regard to use of watersheds as the basis for evaluating cumulative impacts of multiple facilities, cumulative impacts within a watershed would only occur in circumstances where the multiple facilities are likely to be impacting the same ecosystem elements. For example, the effects of plants located on non-tidal waters in a watershed are unlikely to have impacts that would be cumulative to those of plants located on tidal portions of the same watershed (except with the possible exception of diadromous fish). We believe that impacts should be considered on the basis of affected resources and not simply on a watershed basis. Thus, the scale to be used in defining a watershed is less relevant than the geographical distribution of the affected resource entities relative to the locations of the power plants. In cases, where affected resource stocks cross state boundaries, it would be reasonable to consider cumulative impacts of facilities located in adjacent states.

17. Minimum standards for Comprehensive Cost Evaluation Study; cost-benefits of meeting performance requirements and estimates of burden to regulatory agencies (VI.A.12: 17153)
    Maryland concurs that EPA should establish minimum standards for cost evaluation, to ensure a “level playing field” for all facilities that wish to pursue this alternative within the regulation. Provision of guidance for conducting such an evaluation may alleviate some of the burden on the Director who would be required to review such evaluations. The more specific the guidance, the less burden imposed on the Director.

18. Adequacy of capacity utilization threshold (15%); facilities operating at less than 15% capacity utilization required to implement BTA only for impingement and not entrainment (VI.A.14: 17154)
    Maryland concurs with the use of the capacity utilization threshold within the regulation for the purpose stated. We also believe that the 15% threshold is not unreasonable, although, as with many of the thresholds established, it is arbitrary. Given it’s arbitrary nature, it may be appropriate to provide to the permitee an opportunity to demonstrate that even at a somewhat higher utilization they should only be required to implement BTA for impingement.

19. Inclusion of regulations on impacts to local water resources other than I&E (VI..B: 17154)
    This question appears to contemplate water use restrictions where evaporative losses can have a significant impact, e.g. in rivers and lakes. Maryland’s regulations already include provisions for considering water losses at power plants within its water appropriations permit system. If EPA chooses to include such regulations in its 316(b) rule, it should permit states with existing regulations for this issue to adopt its own regulations as an alternative.

20. Intake capacity commensurate with close-cycle cooling systems based on waterbody type (VI..B.1,2: 17155); based on waterbody type and proportion of waterbody flow (VI.B.1,2: 17156)
    Maryland supports EPA in not proposing the option of requiring intake capacity commensurate with close-cycle cooling systems based on waterbody type. Our evaluations of major estuarine power plants in Maryland, such as Calvert Cliffs, indicate that all estuarine facilities do not cause significant impacts as a result of entrainment. Thus, this option could impose significant costs on plant owners and customers without generating any environmental benefits. Maryland does not support the option that brings in the proportion of water body flow as a decision factor. The threshold value specified (>1% of flow) is arbitrary and has no scientific support. States should be given the flexibility to consider the significance of ecological and resource impacts in imposing BTA rather than being automatically required to impose requirements that are based only on an arbitrary threshold value.

21. Site-specific rule for determining BTA to minimizing AEI and framework for implementing (VI.C.1: 17159-17161)
    Maryland is in general agreement that the framework presented is an appropriate site-specific approach for implementing the Phase II rule.

22. Various definitions of Adverse Environmental Impact, including that any I&E is adverse, or use a threshold approach (VI.C.5: 17162-17164)
    As we noted earlier, Maryland regulations consider CWIS impact at the level of RIS or ecosystem function. We believe that this is a scientifically and valid basis for determining if adverse impact is occurring. We disagree that the numerical magnitude of organisms entrained and impinged is, by itself, indicative of adverse environmental impact.

23. Use of previous 316(b) demonstrations for AEI and BTA and criteria for current adequacy (VI.C.5.b(4): 17165)
    Maryland strongly supports the use of prior 316(b) studies for demonstrations of AEI and BTA, but is in agreement with several of the caveats that EPA presents. Most importantly, we concur that results of prior studies are only valid and useful if the basic nature and composition of the source water body ecosystem has not changed substantially. If there have been major shifts in biological communities and major changes in relative species abundances, it is appropriate that the permitee be required to collect and submit data representative of current conditions.

24. Appropriateness of cost-effectiveness evaluation of CWIS technology or other measures to determine BTA for minimizing AEI (VI.C.5.c(3): 17165)
    We believe that the use of an incremental cost-benefit assessment as a procedure for establishing BTA is reasonable. As suggested by PSEG, the costs of a series of potential BTA technologies would be estimated concurrently with the incremental environmental benefits that would result from implemention of those technologies. It appears that a requirement for such a sequential assessment may place a substantial burden on both the permitee as well as the Director, since the validity of each of the cost estimates would have to be evaluated. This may be a procedure that could be included as guidance, rather than being incorporated into the regulation itself.

25. Permit voluntary restoration or enhancement measures to be included for compliance (VI.C.5.d: 17166)
    As we indicated in item 6, above, we believe that restoration or enhancement measures should not be considered to be only supplemental to BTA determination. Thus we are supportive of voluntary measures being accounted for in permitting decisions, to the extent that they are consistent with, and supportive of, a state’s resource management goals and objectives.

26. Burden of implementing site-specific 316(b) rules on permitting agencies (VI.C.6:17167)
    Maryland agrees that a site-specific approach does pose a substantial burden on the agencies with responsibility for reviewing and approving 316b applications. Because PPRP is unique within the country (e.g., a small surcharge on electric bills provides funding for the evaluation of power plant impacts), we recognize that many other states may not have comparable technical and financial resources to be applied for that purpose. However, as we have noted above, we strongly believe that a site-specific approach to 316b implementation is the most cost-effective means of maximizing benefits to our citizens from this new rule. Our suggestion to EPA for minimizing the burdens to other states would be to develop guidance documents for implementation of the rule that are clear and detailed, so that the information to be presented to the agencies is relatively standardized and done in a manner that enhances the likelihood that the findings are applicable, and technically sound.

27. Comprehensive Demonstration Study: specify particular submission time frame; require approval by Director (VII.B.4.a:17175)
    We believe that approval of the demonstration study by the Director is very important, so we do not support removing that requirement. It appears reasonable to establish specific time frames for submission, but, given the substantial uncertainties that surround environmental studies, it is also reasonable to provide substantial flexibility to the Director in enforcing compliance with those time frames.

28. State alternative regulatory requirements that are “functionally equivalent” and EPA decision criteria for evaluating them; role of restoration and habitat enhancement projects in these (VII..F: 17180)
    As we have stated above and in prior submittals to EPA, Maryland believes that its existing 316b regulations have successfully protected our State’s aquatic resources and ecosystems. Thus, we strongly support including in the Phase II rule an allowance for accepting a State’s existing 316b regulations. However, the suggestion in this proposed rule is that the state would have to demonstrate that implementation of their regulations are “functionally equivalent” to implementation of 125.94. As we have noted above, Maryland considers adverse environmental impact at the RIS or ecosystem effects level, as opposed to 125.94 which encompasses total entrainment and impingement mortality caused by the plant. Thus, Maryland’s regulations may be determined by EPA to not be “functionally equivalent” to the regulation proposed in 125.94. We are very supportive of the incorporation of restoration and habitat enhancement as acceptable elements of state regulations.

Maryland Comments on Issues Not Specifically Addressed in the Proposed Rule

A number of technical issues remain with regard to the Phase II proposed rule that are not explicitly addressed in the April 9, 2002 publication. We raise these issues here.

  • Definition of what constitutes entrainment vs. impingement - By definition, organisms that pass through a traveling screen and enter the cooling system are entrained, while those too large to pass through the screen are impinged on the screen. Thus, the size of the mesh on the traveling screen has bearing on what is entrained and what is impinged. A 3/8" mesh traveling screen is the conventional separation between the two. EPA should consider specifying the mesh size that would represent the standard for distinguishing between entrainment and impingement.

  • Use of out-of-kind mitigation - While restoration and enhancement is addressed at various points in the proposed rule, out-of-kind mitigation is not explicitly addressed. We have made the point under item 9, above, that a State should be allowed the flexibility to identify the enhancement or restoration measures that would provide the greatest benefit to their constituents, even if those measures represent out-of-kind mitigation. We describe the Chalk Point permit agreement above, in which striped bass and American shad juveniles were raised and released as mitigation for entrainment losses.

  • Frequency of detailed permit evaluations - While the standard NPDES permit renewal period is 5 years, in most instances ecosystems do not change substantially over such a short time period. Thus, it may be reasonable to require a detailed 316b reassessment perhaps only every third permit renewal, unless there is reason to believe there is a substantial change in the affected ecosystem or that plant operations are likely to be causing some significant impact.

  • Quantifying impingement - In many instances, large episodes of impingement occur as a result of already impaired or dead fish accumulating on intake screens. Such situations have occurred where large number of fish such as menhaden accumulate in small confined areas and die as a result of lack of oxygen, and are then drawn into intake screens. Similar situations sometimes occur where unusually cold water immobilizes fish, such as alewife on the Great Lakes. EPA should specify in their guidance documents some means of accounting for such pre-impingement mortality in assessing the need for BTA.

  • Performance ranges vs. a single compliance target and performance baseline - We find the presentation of a range of performance targets somewhat confusing, and do not see that the provision of a range has any ecological significance. We understand that the range presented arises from information available on the efficacy of available intake technologies. However, if the range is based on performance of technologies, perhaps it would be more appropriate just to specify acceptable technologies and not attempt to specify a reduction target. Even in this circumstance, however, the intended reduction only has meaning when a baseline for comparison is established. While the proposed rule indicates what is considered to be a baseline (e.g., a shoreline intake with no protective screening), no guidance is presented on how to use existing or new data to extrapolate what baseline impacts might be. This is a critical missing element in the proposed rule, since compliance with the rule will have to be based on comparison of monitoring results after a BTA determination is made with these projected baseline values.

  • References

    Hochberg, R.J., MA. Friday, and C. F. Stroup. 1993. Review of technical approaches for cumulative ecological assessment. Prepared by Versar, Inc. for the Maryland Department of Natural Resources, Power Plant Research Program. PPRP-109.

    Loos, J.J. and E. S. Perry. 1989. Evaluation of forage fish entrainment at Chalk Point Station. Appendix A. Prepared by Potomac Electric Power Company, Washington, D.C.

    MMES (Martin Marietta Environmental Systems [now Versar, Inc.]. 1985. Impact assessment report: R. Paul Smith Steam Electric Station aquatic monitoring program. Prepared for the Maryland Department of Natural Resources, Power Plant Research Program. PPSP-RPS-81-2.

    Power Plant Cumulative Environmental Impact Report B (CEIR), 1986. PPSP-CEIR-5. Maryland Power Plant Siting Program, Maryland Department of Natural Resources, Annapolis, Maryland

    Richkus, W. and R. McLean. 2000. Historical overview of the efficacy of two decades of power plant fisheries impact assessment activities in Chesapeake Bay. Environmental Science & Policy 3(2000) S283-S293.

    Ringger, T. G. 2000. Investigations of impingement of aquatic organisms at the Calvert Cliffs Nuclear Power Plant, 1975-1995. Environmental Science & Policy 3 (2000) S261-S273.

    Versar. 1989. Review and evaluation of PEPCO's 1989 frational entrainment loss estimates for the Chalk Point SES. Prepared for the Maryland Department of Natural Resources, Power Plant Research Program. TR89-20.

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    This page was updated on April 18, 2003.