July 2, 2012 316(b) SP Survey – Overview of Preliminary Modeling Exercises for Survey Attribute Values | pg 1 Date July 2, 2012

To The Section 316(b) Existing Facilities Rule Record

From Erik Helm, U.S. Environmental Protection Agency Subject 316(b) Stated Preference (SP) Survey – Over view of Preliminary Modeling Exercises for Attribute Values

Methods used to calculate baseline and changes to a ttribute values in the 316(b) stated preference (SP) survey were described in a previous memorandum (“ Attribute Calculations within the 316(b) Stated Preference (SP) Survey”, DCN 11-4533). That memo refers to “preliminary modeling exercises” (p. 3) used to support the maximum change s associated with attributes in th e survey. This brief memo describes that effort in more detail. In particular, this me mo describes maximum changes to the baseline values of the four environmental attributes included in the SP survey: (1) commercial fish populations, (2) fish populations (all fish), (3) fish saved, and (4) condition of aquatic ecosystems. 

### 1 Commercial Fish Populations To estimate the effect of regulatory options on the commercial fish populations attribute, EPA modeled populations of eight commercially harvested fish speci es using matrix models. To investigate the role that density dependence might play in limiting the effect of regulations, three dens ity dependent functions were explored for each of these eight commercia lly targeted species (Abt Associates 2009a). Although the modeled effect of im pingement and entrainment (I&E) mortality varied among species, it was minimal in all cases. Modeled population level ch anges to these stocks over ten years varied on a species-specific basis between < 0.1% and approximat ely 5%. These exploratory results were comparable to those in the literature (Lorda et al 2000). Because of the similar valu es these approaches produced, EPA assumes these estimates corroborate each other, such that the maximum feasible regional changes in commercial fish populations is about 5%. Using NOA A estimates of stock biomass compared to biomass at maximum sustainable yield (B / B MSY ), EPA identified seven commercially-targeted stocks for which an increase of fish populations of 5% would result in B / B MSY > 0.8 (a threshold used by NOAA in their Fish Stock Sustainability Index (FSSI) to sco re commercial stock sustainability) (NMFS 2010). Regionally, these stocks account for between 1.5% and 5.4% all stocks for which biomass data are available. To ensure that the full range of possible levels was encompassed by the experimental design of the SP survey, and because integer percentages are easi er to respond to, EPA increased this estimate to 6%. Thus, the maximum policy effect presented to respondents was 6% for all SP survey regions. 

### 2 Fish Populations (All Fish) As described in Section 1, EPA modeled populations of eight commercially harvested species. Because the fish populations (all fish) attribute is measur ed against carrying capacity, rather than maximum sustainable yield, the relative magnitude of these popula tion shifts are smaller for this attribute, typically by a factor greater than two (i.e., biomass at carrying capacity (B K ) > 2x B MSY ). Consequently, maximum change for the attribute will be smaller than those obs erved for changes in the commercial fish attribute. Given that integer percentages are e asier for respondents to respond to, this suggests that changes to the fish populations (all fish) attribute should be no more than 2.5%, (i.e., half the maximum increase in fish populations observed). However, to ensure that the fu ll range of possible levels was encompassed by the experimental design of the SP survey, and to present policy effects as an integer, EPA increased this estimate to a maximum of 4% for all SP survey regions.July 2, 2012 316(b) SP Survey – Overview of Preliminary Modeling Exercises for Survey Attribute Values | pg 2 

### 3 Fish Saved Models used to estimate changes in the fish sav ed attribute are discussed in Chapter 3 of the Environmental and Economic Benefits Analysis (E EBA) for the proposed rule (USEPA 2011). Because of the long history of equivalent age modeling th at has been conducted for 316(b) purposes, and the relative richness of data availability, meaningful estim ates could be estimated for each region: they are presented in the memo “Attribute Calculations within the 316(b) Stated Preference (SP) Survey” (DCN 11-4533), with raw data available in the docum ent “316(b) Survey design values” (DCN 11-4523). Across regions, the maximum percentage of fish saved varied (achieved if all facilities were required to adopt closed cycle cooling) was between 80% and 94%. The maximum change assigned to this attribute was rounded to 95% for the Northeast, Pacific, In land, and National SP surveys, and 90% for the Southeast SP survey, to ensure the full range of po ssible levels was encompassed by the experimental design of the SP survey. 

### 4 Condition of Aquatic Ecosystems EPA conducted an exploratory modeling exercise in the Chesapeake Bay using the Ecopath with Ecosim (EwE) software and the Chesapeake Bay Fisheries Ec osystem Model (CBFEM) to estimate the regulatory effects of the proposed rule on the condition of aquatic ecosystems (Abt Associates 2009b). This model produces a static mass-balanced snapshot of the bay, assuming a closed system. EPA was able to conduct this preliminary modeling only because of NOAA’s de velopment of the CBFEM (Christensen et al. 2009). Moreover, because of the detailed data requireme nts, time, and effort required to develop EwE models, it was not possible for EPA to conduct ad ditional modeling exercises given time and resource constraints. Although results were preliminary and limited in geographical scope, the model indicated that minor changes to marine communities could occur as a result of the proposed rule. Additionally, because many of the indices used to estimate the condition of aqua tic ecosystems are partially derived from community diversity and composition, it is possible that these cha nges would result in measurable changes to aquatic ecosystem scores. However, these changes are unlikely to be large. This is because indices of biotic integrity (IBI) used to estimate the condition of a quatic ecosystems rely upon several metrics (such as pollution, sedimentation, etc.) that are unlikely to be affected by the proposed rule. In many cases, fish communities either: (1) account for only a small portion of the overall score, or (2) require substantial changes in diversity, dominance, number of spawning species, number of benthic species, or abundance – not observed in CBFEM output – to have a measurabl e affect on IBIs. Thus, it is unlikely that reducing I&E mortality will alter overall ecosystem condition scores by more than 3% to 4%. After taking these considerations and the preliminary results of the CBFEM into account, EPA estimated that changes in aquatic condition as a result of the proposed regulati ons are unlikely to exceed 2%. Moreover, because the results observed from the CBFEM represent the potential for recovery within a heavily impacted estuary, this estimate is likely to be representative of an upper bound for all survey regions. However, because EPA’s estimate is made with incomplete data, and to ensure the range of all possible values were encompassed by the SP survey, the maximum estimat e of changes presented in surveys was doubled to 4% for all survey regions.



### 5 References Abt Associates. 2009a. WA 2-09 Task 4: Matrix models of I & E effects on fish populations. Memorandum dated December 16, 2009. Abt Associates. 2009b. WA 2-09 Task 4: Ecopath simulations of Chesapeake bay. Memorandum dated November 18, 2009.July 2, 2012 316(b) SP Survey – Overview of Preliminary Modeling Exercises for Survey Attribute Values | pg 3 Christensen, V., A. Beattie, C. Buchan an, H. Ma, S.J.D. Martell, R.J. La tour, D. Preikshot, M.B. Sigrist, J.H. Uphoff, C.J. Walters, R.J. Wood, H.Townsend. 2009. Fisheries Ecosystem Model of the Chesapeake Bay: Methodology, Parameterization, a nd Model Explanation. U.S. Dep. Commerce, NOAA Tech. Memo. NMFS-F/SPO-106, 146 p. Lorda, E., D. J. Danila, and J.D. Miller. 2000. 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. Environmental Science & Policy

3:S471-S482. National Marine Fisheries Service (NMFS). 2010. Annual Report to Congress on the Status of U.S. Fisheries - 2009. Silver Spring, MD. U.S. Environmental Protection Agency (USEPA). 2011. Environmental and Economic Benefits Analysis for the Proposed Section 316(b) Existing Fac ilities Rule. Office of Science and Technology, Engineering and Analysis Division. EPA 821-R-11-002.