CHAPTER 3

Review of the Scientific Information and Analysis Presented in the Draft Environmental Impact Statement (DEIS)

The committee’s task is to assess the scientific information, analysis, and conclusions presented in the DEIS and to determine whether the Atkins peer review “is fundamentally sound and materially sufficient.” As discussed more fully in Chapter 1, the committee examined and has made findings regarding the scientific data and sources presented in the DEIS. The committee also provides here an assessment of the levels of uncertainty in the conclusions reached in the DEIS to indicate the strength of the scientific evidence underlying these conclusions. This is a separate issue from evaluating the sufficiency of the DEIS to meet NEPA requirements.

Science-Based Levels of Uncertainty

Scientific uncertainty as used in this report refers to the strength of the scientific information and logic available to assess a potential impact. Uncertainty can arise from a variety of factors such as: a lack of data, low resolution data or data with high levels of measurement error, conflicting scientific results, or a lack of scientific understanding of the underlying natural processes. All scientific information contains some level of uncertainty, but this does not mean that science does not provide actionable information for policy; rather the level of uncertainty is an attribute of scientific information that needs to be communicated as part of a scientific report (NRC, 2004). Given the importance of explicitly stating the strength of the underlying scientific data used in formulating conclusions to inform policy decisions, the committee assessed the available data and analysis to assign a level of uncertainty to the impact conclusions reached in the DEIS. For each resource category, the committee assigned a level of low, moderate, or high uncertainty to the impact intensity conclusions presented in the DEIS using the following criteria:

  • Low uncertainty is assigned when the committee finds that substantial scientific evidence exists to support the conclusions reached, i.e., the evidence demonstrates a strong cause-effect relationship between Drakes Bay Oyster Company (DBOC) actions associated with an alternative and a measurable effect.
  • Moderate uncertainty is assigned when the committee concludes that, while there is insufficient data and information for Drakes Estero, observations from other comparable ecosystems and current scientific understanding allow logical deductions concerning a possible cause-effect relationship between DBOC actions and a measureable effect.
  • High uncertainty is assigned when the committee concludes that there is insufficient data and information for Drakes Estero; observations from other comparable ecosystems are not available; and scientific understanding is insufficient or controversial such that conclusions regarding a possible cause-effect between DBOC actions and a measurable effect can be made only by inference.

Environmental Impacts of the Alternatives

The primary conclusions in the DEIS are expressed as intensities of impact1 on living and nonliving resources of Drakes Estero. The summation of these levels of impact provides a semi-quantitative assessment of the expected consequences of the various alternatives (e.g., DEIS Table ES-4 and Table 2.6) and constitutes the principal means for communicating the expected consequences of the

__________________

1 DEIS, p. 250.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 17
CHAPTER 3 Review of the Scientific Information and Analysis Presented in the Draft Environmental Impact Statement (DEIS) The committee's task is to assess the scientific information, analysis, and conclusions presented in the DEIS and to determine whether the Atkins peer review "is fundamentally sound and materially sufficient." As discussed more fully in Chapter 1, the committee examined and has made findings regarding the scientific data and sources presented in the DEIS. The committee also provides here an assessment of the levels of uncertainty in the conclusions reached in the DEIS to indicate the strength of the scientific evidence underlying these conclusions. This is a separate issue from evaluating the sufficiency of the DEIS to meet NEPA requirements. Science-Based Levels of Uncertainty Scientific uncertainty as used in this report refers to the strength of the scientific information and logic available to assess a potential impact. Uncertainty can arise from a variety of factors such as: a lack of data, low resolution data or data with high levels of measurement error, conflicting scientific results, or a lack of scientific understanding of the underlying natural processes. All scientific information contains some level of uncertainty, but this does not mean that science does not provide actionable information for policy; rather the level of uncertainty is an attribute of scientific information that needs to be communicated as part of a scientific report (NRC, 2004). Given the importance of explicitly stating the strength of the underlying scientific data used in formulating conclusions to inform policy decisions, the committee assessed the available data and analysis to assign a level of uncertainty to the impact conclusions reached in the DEIS. For each resource category, the committee assigned a level of low, moderate, or high uncertainty to the impact intensity conclusions presented in the DEIS using the following criteria: Low uncertainty is assigned when the committee finds that substantial scientific evidence exists to support the conclusions reached, i.e., the evidence demonstrates a strong cause-effect relationship between Drakes Bay Oyster Company (DBOC) actions associated with an alternative and a measurable effect. Moderate uncertainty is assigned when the committee concludes that, while there is insufficient data and information for Drakes Estero, observations from other comparable ecosystems and current scientific understanding allow logical deductions concerning a possible cause-effect relationship between DBOC actions and a measureable effect. High uncertainty is assigned when the committee concludes that there is insufficient data and information for Drakes Estero; observations from other comparable ecosystems are not available; and scientific understanding is insufficient or controversial such that conclusions regarding a possible cause-effect between DBOC actions and a measurable effect can be made only by inference. Environmental Impacts of the Alternatives The primary conclusions in the DEIS are expressed as intensities of impact1 on living and non- living resources of Drakes Estero. The summation of these levels of impact provides a semi-quantitative assessment of the expected consequences of the various alternatives (e.g., DEIS Table ES-4 and Table 2.6) and constitutes the principal means for communicating the expected consequences of the 1 DEIS, p. 250. 17

OCR for page 17
18 Scientific Review of the DEIS DBOC SUP alternatives to decision makers and the public. Activities associated with each alternative are assessed as either beneficial, minor adverse, moderate adverse, or major adverse for short-term, long-term, and cumulative impacts according to intensity definitions specific for each resource topic. Beneficial is defined as "a positive change in the condition or appearance of the resource or a change that moves the resource toward a desired condition," while adverse is defined as "a change that moves the resource away from a desired condition or detracts from its appearance or condition."2 It is noteworthy that only one category of beneficial impact is used, hence effects that may range from minor to major beneficial cannot be distinguished. In addition, the impact intensities do not allow for a finding of negligible impact, a category that is included in NPS NEPA guidance documents, "Summary of Regulations and Policies -- Impact Indicators and Criteria," Director's Order 12.3 A complete list of the impact definitions from the DEIS for each of the resource categories is provided in Appendix C. For each resource category, the committee (1) examined the interpretations, analyses, and conclusions given in the DEIS; (2) assessed the extent to which they are reasonable and scientifically sound based on information in the DEIS; (3) based on this evaluation, assessed the level of uncertainty associated with the impact intensity conclusions in the DEIS and, where appropriate, offered possible alternative conclusions that are equally reasonable and scientifically sound; and (4) determined if there is additional information and analyses that are not in the DEIS but that could be used to reduce levels of uncertainty. The committee addressed the resource categories as they were presented in the DEIS, with an exception for a separate discussion on non-indigenous species. As was often indicated by cross- referencing in the DEIS, there are no clear boundaries between resource categories. The assessment of an impact on one resource may depend in part on the predicted effect to another resource. This is the nature of ecosystems, which are characterized by complex interactions among and between living and non-living components. Wetlands I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS The DEIS provides a qualitative inventory of wetlands in Drakes Estero and presents GIS maps of the distribution of the different types of wetlands. The focus of the DEIS is on the wetland area located between the mean low tide elevation and 100 ft landward of the high tide line.4 These areas are characterized by mostly unvegetated substrates5 among which mudflats dominate.6 Inclusion of the unvegetated substrates is prompted by the DEIS integrated application of both the Environmental Protection Agency (EPA)/U.S. Army Corps of Engineers (USACE) and U.S. Fish and Wildlife Service (USFWS) definitions of `wetlands.' However, it is evident from the DEIS and from NPS statements at the committee's 11 July 2012 public meeting that some tidal-freshwater wetlands were excluded7 even if they fit the operational definition of "100 ft landward of the high tide line" (assuming that the high tide line is correctly interpreted). Onshore wetland areas are also discussed in the section on Special-Status Species. The DEIS lists three DBOC activities that could impact wetlands under alternatives B, C, and D: continued use and maintenance of shellfish racks and bags in Drakes Estero; continued boat traffic; and installation of a new dock, including dredging. For alternative D, the DEIS adds potential impacts from increased production level, new onshore development, and placement of a new intake pipeline. The wetland area currently permitted for culture bags (Table 2.1) will not change greatly under alternatives B, C, or D. However, the balance between bag and rack culture could change under alternatives B, C, and D and may vary from year-to-year as discussed in Chapter 2. The most important potential impacts on intertidal mud and sand flats are related to motor boat traffic; workers walking across the flats to place, turn and recover culture bags; and the number and placement of bags themselves. These activities may have a direct impact on turbidity, sediment dynamics, benthic fauna, harbor seals, 2 DEIS, p. 235. 3 Available at: http://www.nature.nps.gov/protectingrestoring/do12site/tabs/tab22.htm. 4 DEIS, p. 166. 5 DEIS, p. 166. 6 DEIS, p. 249. 7 DEIS, Table 3-1 and Figures 3-1 and 3-2.

OCR for page 17
Review of the Scientific Information and Analysis 19 birds, and spread of non-indigenous species. Impacts on benthic fauna, harbor seals, birds, and spread of non-indigenous species are discussed elsewhere in this chapter. Boat generated waves may erode the edge of marsh vegetated areas and mudflats. Impacts on turbidity by motor boat traffic are also likely to be pulsed and rapidly dissipated, especially given tidal mixing and advection in Drakes Estero. Over time the wetlands will recover under alternative A, but it is unlikely that the wetlands will return to historic conditions, in contrast to the statement in the DEIS that removal of DBOC structures "would increase the potential that the project area could be converted back to historic wetland habitat."8 It is more likely that the wetlands will reach a new equilibrium depending on sediment dynamics and species colonizing the area (e.g., Villnas et al., 2011). Shifting sediments following the removal of culture bag is a potential threat to benthic fauna (and eelgrass beds). Upon removal of the bags, which occurs under alternative A once and at the end of each crop cycle under alternatives B, C, and D, sediment surfaces will be exposed to currents and waves allowing for sediment reworking until a new equilibrium is reached. Although this is expected to be a short-term effect, management of sediment redistribution as described in the DEIS may be necessary to avoid burial of benthic invertebrates and eelgrass. Once sediment dynamics stabilize, risks of burial should be negligible. Some additional references on research on shellfish culture impacts on these types of benthic communities, such as the Bouchet and Sauriau (2008) paper on oyster culture on intertidal mudflats in France and reviews such as Forrest et al. (2009) would provide more context for this section of the DEIS. II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF LEVEL OF UNCERTAINTY, ALTERNATE CONCLUSIONS The committee finds that the impact definitions, review of scientific information, and conclusions on wetland impacts are reasonable. The DEIS concludes that the impact of DBOC activities including physical buildings and structures, boating operations, and mariculture practices, on wetlands will be moderate adverse, a conclusion that the committee finds to be reasonable and is associated with a moderate level of uncertainty. It is likely that alternatives B, C, and D would continue to have an adverse impact on wetlands over the next 10 years, and these impacts would continue to be localized. The committee identified a few issues that could be clarified or expanded in the wetland section as follows. According to the DEIS, sediment erosion occurs along the edges of culture bags, but it is uncertain whether this is a short-term process that stabilizes once a new equilibrium between currents and sediments is reached or whether this is an ongoing, long-term process. If this point cannot be clarified, the committee would assign a moderate level of uncertainty to the conclusion that the bag culture has a moderately adverse impact. Since potential impacts of DBOC operations are not necessarily confined to the project area per se, a more ecologically sound definition of the project area would be the Estero from the head of tide in Barries, Creamery, Schooner, and Home Bay to the mouth of the Estero with lateral boundaries determined by the landward extent of tidal wetlands. This would include the tidal freshwater wetlands at the heads of Schooner and Home Bays. III. WAYS TO REDUCE THE LEVEL OF UNCERTAINTY Observations on the effects of oyster bags and clam culture operations on the conformation of the mud and sand flats would reduce uncertainty with regard to impact intensity and duration. The DEIS9 assumes that wetland disturbance will not be a long term impact: "After bags or clusters are removed for oyster harvest or transfer, natural processes would be expected to resume in E2US3 and E2US1/2 wetlands until new culture is placed there. The length of time required for natural processes to resume would vary depending on the level of disturbance (Wisehart et al., 2007; Zieman, 1976)." However, no details are provided on the approaches, methods, and evaluation that would be used for restoration of wetlands. To achieve long-term recovery, adaptive management would be essential given uncertainties associated with restoration of many of these ecosystems (e.g., mudflats). This would require monitoring of sediment dynamics such as accretion and erosion rates in the marsh using SET-tables (Cahoon et al., 1995) and sediment grain size and organic content in the marshes as well as the mudflats. 8 DEIS, p. 252. 9 DEIS, p. 253.

OCR for page 17
20 Scientific Review of the DEIS DBOC SUP Eelgrass I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS Seagrass has high habitat value, as has been recognized by NOAA in its designation as essential fish habitat, therefore impacts on seagrass beds could have broad ecological implications.10 As described in the DEIS, the seagrass Zostera marina (eelgrass) has undergone an expansion and is currently found throughout the Estero. It is denser in some areas (353 acres with 90 to 100% cover) and sparser in others (384 acres with 30 to 90% cover).11 This expansion was not restricted to the Estero but was observed on a regional scale (NRC, 2009). In general, it is estimated that "eelgrass habitat within Drakes Estero has doubled from 1991 to 2007 (NRC, 2009)." However, interannual trends in spatial coverage are uncertain and would need to be validated, as feasible with the data available, based on year-to-year changes over that timeframe. Seagrasses require light, nutrients and a stable substrate to grow. The spatial extent of eelgrass in Drakes Estero suggests that these requirements are generally being met. Potential impacts of shellfish mariculture are discussed according to source below. Regarding scarring of eelgrass by motorboat propellers, it is highly likely that outboard motors used by the DBOC cause scarring in the eelgrass beds,12 estimated to occur within polygons (motor boat corridors) of about 50 acres (NRC, 2009). In the DEIS, the estimated length of eelgrass beds affected by propeller scarring is 8.5 miles based on visible scarring seen in high resolution aerial photographs in 2010.13 Since this method is limited to visible propeller scars, the DEIS states that this is likely an underestimate.14 If the boat scar width is about 1 m on average, the committee estimates that the impact area would be approximately 13,70015 m2 (equivalent to approximately 3.4 acres). In any event, the area of propeller scarring is likely small compared to the total acreage of eelgrass in the Estero, i.e., the impact is local and limited to the area directly impacted. Alternative A would allow the scars to heal while alternative D may cause further damage depending on whether motorboat trips to bag and rack culture areas increase. The latter could increase recovery times once DBOC operations cease. The duration for recovery of propeller scarred eelgrass beds is not adequately estimated for the Drakes Estero disturbance, or addressed on the basis of the current scientific literature. The DEIS estimates recovery time to be from weeks up to 5 years (recovery times for eelgrass gaps in west coast estuaries are available in Boese et al., 2009 and Ruesink et al., 2012), but it has been shown that some scars need remediation for seagrass recolonization (Kenworthy et al., 2002). In general, the committee finds that the data support the DEIS findings; alternatives B and C would sustain the current level of adverse impact while alternative D could increase the amount of vegetation damaged if motorboat traffic increases and there are more motorboat corridors through eelgrass beds. Additional references to studies on the impacts of propeller scars on seagrass beds and recovery times would be useful in the DEIS because some of the methods used to recover scars in tropical areas may also apply to temperate zones, e.g., filling of scars to minimize further erosion (Hammerstrom et al., 2007). Regarding shading of eelgrass by boat-generated turbidity, the DEIS suggests that motorboats create levels of turbidity that are likely to reduce primary productivity, including that of eelgrass. It is known that the frequency of resuspension events affects the health of seagrasses (Moore et al., 1997), but that infrequent resuspension events resemble storm-induced turbidity events (Koch, 2002) which seagrasses tolerate well (Schaffelke et al., 2005). Given more frequent resuspension events, associated increases in turbidity may be an adverse impact of alternatives B, C, and D. However, the DEIS does not provide data on turbidity in Drakes Estero and, as discussed in the Water Quality section, water clarity would likely be more variable due to natural processes such as phytoplankton blooms, changes in bottom shear over a tidal cycle, and seasonal storms than indicated in the DEIS.16 Thus, it is not known whether brief pulses of turbidity caused by the passage of motorboats are within the range of natural variability or 10 www.fpir.noaa.gov/PRD/prd_critical_habitat.html; www.oregon.gov/DSL/SSNERR/tides/tidesA13_eelgrassfacts.pdf?ga=t. 11 DEIS, p. 172. 12 DEIS, Figure 3-4. 13 DEIS, p. 173. 14 DEIS, p. 261. 15 2 Using the DEIS estimate of 8.5 miles of scarring length, which is approximately 13,700 m x 1m scarring width = 13,700 m . 16 DEIS, p. 267.

OCR for page 17
Review of the Scientific Information and Analysis 21 whether these events cause measureable increases in turbidity that could limit light penetration and the growth of eelgrass. At most, the relatively brief pulses of turbidity generated by motorboats may temporarily increase turbidity and reduce light levels reaching the bottom but, as previously discussed in the wetlands section, turbidity will probably be rapidly dissipated by strong tidal currents and mixing, and at low tide when eelgrass beds are only covered by a thin layer of water, water turbidity will have little effect on light availability for eelgrass growth (Koch and Beer, 1996). Possibly, a more detrimental effect of resuspension by motorboats comes from the transport of the sediments into seagrass beds and deposition of sediments on the leaves. However, considering the high tidal currents and mixing in Drakes Estero, the impact is likely to be smaller than suggested by studies cited in the DEIS. Despite some unclear statements in the DEIS regarding the impact of bags occupying space that otherwise might be colonized by eelgrass,17 it is unlikely that bag culture has a direct impact on eelgrass beds. Therefore, the committee limits its analysis to the impacts of rack culture.18 The area of DBOC racks in eelgrass beds is ~7 acres (Table 2.1). The density of eelgrass beneath culture racks in other studies has been observed to be lower compared to adjacent areas (e.g., Everett et al., 1995); potentially the result of shading, erosion, or pseudofeces produced by the filter-feeders. Together with boat scars (above), the evidence for a direct, cause-effect relationship between rack culture and an adverse impact on the growth of eelgrass is strong and is given a low level of uncertainty by the committee. Regarding benthic-pelagic coupling and the availability of light, filter feeding shellfish can be beneficial to seagrasses by reducing turbidity and increasing the availability of light for growth (e.g., Newell and Koch, 2004). These findings are based on models and experimental close-system mesocosms. However, this might not be the case under natural conditions in the field (e.g., Booth and Heck, 2009), depending on ambient turbidity and water depth. The DEIS suggests that the water in Drakes Estero is not especially turbid and therefore, the benefit of oyster-filtration is likely to be minor.19 However, as discussed in the Water Quality section (below), representative quantitative observations of water clarity are lacking for Drakes Estero. II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF UNCERTAINTY, ALTERNATE CONCLUSIONS In general, conclusions related to the impacts of DBOC operations in the Drakes Estero system have a moderate level of uncertainty. The DEIS concludes that alternatives B, C, and D would result in long-term moderate adverse impacts on eelgrass. However, impacts may be less adverse because of the small footprint of motor boat operations and rack culture relative to the spatial extent of total eelgrass, and uncertainties related to the lack of data on turbidity in Drakes Estero. Based on literature from tropical seagrass beds, it is also possible that active restoration efforts may be needed to revegetate bare areas, especially where damage is caused by motorboat scars. III. WAYS TO REDUCE THE LEVEL OF UNCERTAINTY A more definitive conclusion on impacts could be reached with increased analysis of how motorboats are used in DBOC's operations and how increases in production under alternative D would affect motorboat traffic or expand motorboat corridors. The duration for recovery of propeller-scarred eelgrass beds is not adequately estimated for the impacts, nor addressed on the basis of the current scientific literature. This is an additional impetus for more complete and systematic analysis of the NPS's time series of aerial photography images to not only document the acreage and frequency of boat propeller scar disturbance but to also document, if possible, the time required for the scars to revegetate. If one of the action alternatives is selected, ongoing assessment of DBOC impacts on seagrass beds could be improved by (1) documenting when and how frequently boats are used for both bag and rack culture relative to stage of tide and documenting motor boat routes relative to the distribution of eelgrass beds under current conditions; and (2) providing information on how the balance between bag culture and rack culture changes from year to year (acreage used, location and production). Monitoring the spatial extent and fragmentation of eelgrass beds, changes in sediment grain size, and deposition rates could make an important contribution to future assessments of impacts. Turbidity and the 17 DEIS, p. 263. 18 DEIS, Compare Figures ES-2 and 3-3. 19 DEIS, p. 175.

OCR for page 17
22 Scientific Review of the DEIS DBOC SUP attenuation of downwelling light (e.g., Secchi disc readings) could be routinely measured in conjunction with motorboat operations. Wildlife and Wildlife Habitat Indigenous Benthic Fauna I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS Three general mechanisms by which DBOC operations may influence indigenous benthic fauna are presented in the DEIS: disturbances, structures, and competition from cultured organisms. The committee agrees with the logic of these mechanisms, but notes that each has a different level of certainty and potential scale and intensity of impact. The committee distinguishes non-indigenous species for treatment in a separate section, which follows the present section. Disturbances to benthic fauna from shellfish mariculture: As pointed out in the DEIS, the placement, flipping, and harvest of bags could cause mortality of some individuals.20 Similarly, any organisms that have colonized oyster racks will suffer when the oysters are cleaned at harvest. Dredging near the DBOC dock, as proposed in alternative D, would also likely result in direct mortality. Data relevant to assessing effects of disturbance would include, at a minimum, documentation of the organisms living in or on bags and oyster racks, which could be lost during harvest. Although some observations are available within Drakes Estero for organisms attached to racks (Grosholz, 2011) and for benthic infauna (Harbin-Ireland, 2004), these data are most relevant to response of benthic fauna to structures, covered in the following section. No quantitative data on organisms associated with oyster strings or bag culture, which would actually be removed at harvest, appear to exist. Whether losses of individuals would be expected to have impacts at the population or community level is unclear, particularly given rapid recovery rates of benthic communities following disturbance (Kaiser et al., 2006) and the small amount of area disturbed at any one time. Response of benthic fauna to structures from shellfish mariculture: The DEIS correctly discusses the robust finding that structure increases diversity and abundance of organisms (Thomsen et al., 2010; Cruz Sueiro et al., 2011). Data from Drakes Estero relevant to structures come from a study comparing benthic infauna (within sediments) between racks and nearby eelgrass, where differences were negligible.21 Different outcomes would be expected for culture structures in unstructured habitats (such as bags on sandbars or mudflats) than for culture structures in structured habitats (such as racks in eelgrass), as well as for epifauna, which inhabit structures above ground, in comparison to infauna. Studies of the impacts of oyster culture (or oysters more generally) on benthic community structure in other ecosystems have been conducted for a variety of habitats and structures, and have included both infauna and epifauna as response variables (i.e., Crawford, 2003; Rumrill and Poulton, 2004; Forrest and Creese, 2006; Hosack et al., 2006; Ferraro and Cole, 2011). Going forward, multivariate approaches to community-level data are likely to be more revealing of habitat differences than are univariate approaches of abundance and diversity. There is little reason to expect that any effects from adding structured habitat in the form of racks and bags would extend much beyond the immediate footprint of mariculture, therefore any changes in community structure might be expected to be small at the scale of Drakes Estero as a whole. Competition from cultured organisms: Food competition between cultured shellfish and indigenous fauna could extend beyond the immediate footprint of mariculture because it is mediated through food availability in the water column. However, many studies have seen only local changes in phytoplankton concentrations in the vicinity of shellfish culture (Pilditch et al., 2001), and larger-scale food competition would be likely only if shellfish were close to ecological carrying capacity (Banas et al., 2007). In the Water Quality section (below), the committee raises the possibility that cultured bivalves may have filtration capacities on the order of water residence time in the finger bays of Drakes Estero. To the extent that water quality calculations are improved, an assessment of ecological carrying capacity could be conducted. At present, though, the extent of food competition between cultured shellfish and other filter feeding benthic organisms appears highly uncertain. The DEIS also raises the possibility of space competition through "native species displacement" but the citations in the DEIS and others that could be referenced regarding impacts of the Pacitic oyster in Europe (e.g., Diederich, 2006; Lejart and Hily, 2007) 20 DEIS, p. 278. 21 DEIS, p. 277.

OCR for page 17
Review of the Scientific Information and Analysis 23 primarily apply to self-reproducing, "naturalized" populations of oysters and clams, not to bivalves cultured with the methods used by DBOC. Establishment of non-indigenous species is addressed separately below. II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF UNCERTAINTY, ALTERNATE CONCLUSIONS The intensity definitions for benthic fauna do not provide clear guidance on the three classifications of adverse impact. In particular, both moderate and major definitions reference impacts to "individuals or groups of species, communities, or natural processes".22 Experimentally, it would be difficult to distinguish between impacts that "appreciably affect" and "substantially influence" individuals. For disturbances to benthic fauna from shellfish mariculture, scale may be small, intensity involves a short-term effect on individuals attached to bags or oyster strings, and uncertainty is moderate given the logic of mortality but no in situ counts of organisms on bags or oyster strings, which are most likely to be affected. For response of benthic fauna to structures provided by shellfish maricultures, scale would be small, intensity would be based on community-level change, and uncertainty, though currently high, could be reduced by applying multivariate approaches to data from Harbin-Ireland (2004) on benthic infauna near and away from racks, and by summarizing the most relevant work in other systems to address how the mariculture structures used by DBOC in the habitats in Drakes Estero may influence infauna and epifauna. Finally, the spatial scale could be large and intensity could reflect alteration of ecosystem processes for food competition between cultured shellfish and indigenous benthic fauna, but uncertainty is also high, in keeping with findings for water quality (below). It is worth noting that drawdown of water column resources by cultured shellfish could have different values attributed to it (e.g., filtration as an ecosystem service vs. filtration seen as food competition to indigenous filter feeders). III. WAYS TO REDUCE THE LEVEL OF UNCERTAINTY The potential impacts of DBOC operations on benthic fauna are confounded by the diversity of species and life histories of benthic organisms. Each potential impact may differ in magnitude and direction depending upon the habitat they occupy (e.g., infauna, epifauna, sessile, mobile) and their food source (e.g., suspension-feeders, deposit-feeders). This complexity results in a matrix of potential impacts (mechanisms of potential impacts vs. organisms), which could have different intensities and uncertainties. From the information provided in the DEIS, it is difficult to discern how this hypothetical matrix is distilled into a single moderate impact intensity conclusion. Literature on benthic impacts could be used more extensively to provide detail on the shifts in benthic communities that could be associated with shellfish culture. Many of the suggested improvements to the Water Quality section could also help address the potential mechanism of impacts to benthic fauna via resource competition. The DEIS could include an analysis of the role cultivated shellfish may have in partitioning the food resource for indigenous filter- feeders; data for chlorophyll draw-down provides some support for the hypothesis that mariculture and natural benthic communities coexist at the current level of operations. Improved data on the composition of suspended particulate matter, and its partitioning into phytoplankton, detrital organic material, and inorganic material, together with microphytobenthos would help to clarify the food sources available to both cultivated species and to indigenous benthic populations. Non-Indigenous Benthic Species I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS Non-indigenous species must first arrive, then establish and spread, and finally become sufficiently abundant or influential on a per-capita basis to constitute an impact (e.g., Williamson and Fitter, 1996; Theoharides and Dukes, 2007). The DEIS explores first, how mariculture activities could lead to establishment of new non-indigenous species (directly cultured or hitchhiking on imports of larvae or spat); and second, how mariculture activities could facilitate the potential spread of existing non- indigenous species from mariculture structures. Multiple non-indigenous species are already present in Drakes Estero (NRC, 2009), although their avenue of introduction is mostly unknown and they appear to be much less conspicuous than in 22 DEIS, p. 274.

OCR for page 17
24 Scientific Review of the DEIS DBOC SUP nearby San Francisco Bay. Only Didemnum (a tunicate) and Batillaria (a snail) are called out from among established non-indigenous species for explicit consideration in the DEIS. An issue of concern for the DEIS is whether current mariculture operations change the abundance (and therefore impact; Parker et al., 1999) of existing non-indigenous species in natural habitats. Augmenting the abundance of non- indigenous fouling organisms on hard surfaces of mariculture structures could in principle spill over to increase their abundance nearby (e.g., Bulleri and Chapman, 2010). Observations in New England indicate that invasive tunicates may be more likely to spread to natural habitats near artificial structures such as docks and mariculture gear than similar habitats away from artificial structures (Carman et al., 2009), although natural habitats away from hard substrates may also be vulnerable because "it is possible that there is little artificial substrate space available ... leading invasive tunicates to colonize natural substrate not typically inhabited" (Carman et al., 2010). II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF UNCERTAINTY, ALTERNATE CONCLUSIONS A reasonable case is made in the DEIS that by increasing the propagule pressure of non- indigenous bivalves (Pacific oyster and Manila clam), the risk of their establishment in Drakes Estero also increases. Establishment risk has been shown to increase with propagule pressure (Lockwood et al., 2005). The DEIS cites evidence that two cohorts of naturally-recruited Manila clams have been discovered recently in habitats outside of mariculture. Although the potential for Manila clams to become established is well documented in the scientific literature (Bourne, 1982; Wonham and Carlton, 2005; Humphreys et al., 2007; Dang et al., 2010), it is dependent on the number of clams cultured by DBOC in the future. As noted in the DEIS, Manila clams "could be produced on a much wider scale under [alternative B] than under existing conditions"23 a statement that applies to alternative D as well. In contrast, in alternative C, "the area in which Manila clams will be grown is a small area,"24 (one acre, referred to as area 2 in the DEIS), which probably restricts total clam production and therefore propagule pressure. However, the DEIS indicates that the lack of sandbars near area 2 may also reduce risk of establishment, but planktonic clam larvae could disperse beyond the growing area, so absence of suitable habitat nearby would not lower the risk of establishment. Temperature requirements for larval development are generally available for the non-indigenous species actually or potentially cultivated (e.g., Numaguchi, 1998). Therefore, water temperatures and residence time, applied to relevant areas for different cultivated species, could underpin establishment risk in the various alternatives. Overall, the committee agrees that the establishment of new species due to DBOC mariculture would constitute a sufficient shift in community composition to constitute a moderately adverse impact given the guidance in NPS Management Policies 2006 for "maintenance and restoration of natural native ecosystems, including the eradication of exotic species."25 There is low uncertainty in the science because the general concepts have strong support (e.g., non-indigenous species permanently shift community composition, establishment increases with propagule pressure). However, moderate uncertainty exists about DBOC's future culture practices, and additional uncertainty about whether Manila clams have already or will in future become established from cultured stock in DBOC or more distant larval sources. III. WAYS TO REDUCE THE LEVEL OF UNCERTAINTY Risk assessment protocols help predict whether a cultivated species is likely to establish outside of mariculture (e.g., ICES, 2005; Appendix B), and such protocols could be applied to non-indigenous species considered under the permit renewal (Pacific oysters, European flat oysters, Manila clams). Logically, with respect to Manila clams, the risk of establishment could be lower for alternative C than for alternatives B and D due to the smaller area available for culture. A risk assessment could provide guidance on whether this would lead to different intensities of impact among the three action alternatives. Data to evaluate the "spillover" of non-indigenous fouling species from mariculture structures to natural habitats would require quantitative field surveys in Drakes Estero to determine a spatial scale beyond the direct footprint of mariculture structures. 23 DEIS, p. 278. 24 DEIS, p. 283. 25 DEIS, p. 276.

OCR for page 17
Review of the Scientific Information and Analysis 25 Fish I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS Although quality data regarding fish populations are lacking for Drakes Estero, observations from other comparable ecosystems and current scientific understanding of marine ecology allow logical deductions concerning potential causal relationships. Site-specific data for Drakes Estero is based solely on fish collections performed by Wechsler (2005). Wechsler concluded that fish richness and abundance did not differ among sampling times or habitats and that fish composition shifted to favor species associated with complex structures, attributable to the culture racks and bags. However, there is considerable uncertainty associated with the sampling methodology, design and statistical analyses that constrain the DEIS interpretations (NRC, 2009). The argument that structure-associated species increase due to DBOC operations is based on sound logic given the Wechsler (2005) data, but the DEIS does not provide data to demonstrate species displacements or other changes that might suggest an ecological effect consistent with the DEIS conclusion that this is minor impact. For example, Allen et al.'s (2006) extensive analysis of California's estuary and bay fish assemblages indicates that, except for shiner perch (Cymatogaster aggregata), the embiotocids found to be more representative of the mariculture rack structure assemblage of fishes in the Estero ("Schooner Adjacent;" Wechsler, 2005) are not prominent residents of northern California estuaries and would thus be considered relatively unique to the mariculture rack footprint. II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF UNCERTAINTY, ALTERNATE CONCLUSIONS The DEIS concludes that the impacts of alternatives B, C, and D would be minor. Considering the small acreage of eelgrass disturbance (Table 2.1), the committee finds that this conclusion is appropriate, particularly because there is considerable uncertainty about whether eelgrass can be directly related to fish production. There is a general lack of knowledge about the association between eelgrass landscapes and "essential fish habitat;" the value of eelgrass as nursery habitat is challenging to test methodologically (Jackson et al., 2001), and there are few empirical data available for U.S. West Coast species. In general, only the abundance (rather than production, growth, and survival) of fishes in eelgrass compared to other habitats, or across gradients in eelgrass patch structure, has been documented (Allen et al., 2002; Rumrill and Poulton, 2004; Hosack et al., 2006; Macreadie et al., 2009; Moore and Hovel, 2010). However, Beck et al. (2001) provide a compelling argument that, even when comparing multiple potential fish and shellfish nursery habitats, an area might be considered an important nursery habitat only if it produces greater adult density compared to other juvenile habitats that the species uses. In addition to density, key indicators of the nursery function include growth and survival of juvenile animals, and juvenile movement to adult habitats. Only in the case of the bay pipefish, Syngnathus leptorhynchus, and shiner perch, Cymatogaster aggregata, can reproduction and trophic and production linkages be directly related to eelgrass with low uncertainty (Onuf and Quammen, 1983). The committee considers the DEIS conclusion to have a moderate level of uncertainty given the lack of data and the uncertainty concerning whether eelgrass extent (and the extent of intertidal mud- and sand-flats) is directly related to abundance and diversity of fish species. It may be reasonable to hypothesize that a small change in habitat such as eelgrass which has been identified by NOAA as essential fish habitat could result in a small change in fish abundances. Similarly, the effect of racks in attracting structure-associated fish in Drakes Estero is hypothetical because the Wechsler sampling design did not support that inference and there were no statistical tests supporting this hypothesis. Alternate conclusions, such as (1) a spatial redistribution of species or (2) subsidization of more structure-associated species, could also be posed. The DEIS also draws a conclusion of minor adverse impacts for alternatives B, C, and D because small amounts of eelgrass habitat are replaced by racks. The propeller scars do not have any replacement structure, but may represent more than half of the area of eelgrass directly affected by mariculture practices. To evaluate such impacts would require a different sort of data regarding fish responses to gaps. The conclusions are to some extent dependent upon the values placed on different species and changes relative to wilderness conditions. For example, the racks (as well as bags in unstructured habitats) could potentially benefit some fish species through prey resource subsidies or refuge from predation, but this does not translate into a beneficial effect in the DEIS.

OCR for page 17
26 Scientific Review of the DEIS DBOC SUP III. WAYS TO REDUCE LEVEL OF UNCERTAINTY Perhaps most importantly, uncertainty associated with the conclusions in the DEIS could be better explained through identification of the underlying assumptions and the projected impacts under different alternatives. Explicitly identifying and evaluating the relationships between the effects on eelgrass, benthic organisms, and fishes by relating predictable (low uncertainty) changes in different fish habitats to those changes in the prey component of the benthic fauna would be a significant contribution to evaluating the comprehensive and cumulative ecological responses to fishes of the DEIS alternatives. Although the extant data on fish assemblage structure and distribution of fishes in Drakes Estero is spatially and temporally deficient, the DEIS could also discuss the scientific evidence showing that variation and change (e.g., fragmentation) in the eelgrass landscape due to impacts such as mariculture could influence the functionality of that landscape for fishes (Bostrm et al., 2006; 2011). The DEIS currently suggests that effects of shellfish mariculture on fishes in Drakes Estero are minor adverse, the lowest level of impact in the current framework. If the DEIS included a negligible impact intensity classification, it might arguably be appropriate to list these impacts as negligible given the small overall footprint of the mariculture activities. Harbor Seals I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS The assessment of impacts on harbor seals is based on information from a small number of publications on research in Drakes Estero, a regional marine mammal monitoring program, and the broader scientific literature on marine mammals. Research on the interactions of harbor seals and mariculture activities is limited to two peer-reviewed papers that analyze data from seal surveys in Drakes Estero and the surrounding region in relation to changes in mariculture levels and other potential population drivers such as El Nio conditions (Becker et al., 2009; 2011). These are the only studies worldwide that have attempted to assess the impacts of mariculture on the distribution and abundance of any pinniped. The DEIS mentions the collection of 250,000 photographs taken by remote cameras with a view of harbor seal haul-out areas, but dismisses them from further consideration in the DEIS "because the collection of these photos was not based on documented protocols and procedures."26 Subsequent to the release of the DEIS, the Marine Mammal Commission issued the report, Harbor Seals and Mariculture in Drakes Estero, California, and referring to the same photographic record concludes that: "Photographs taken between 2007 and 2010 warrant further review to assess their usefulness for characterizing the rates and consequences of disturbance," (MMC, 2011). Finally, the DEIS cites other available data on disturbance impacts on harbor seals (e.g., from recreational activity), and is informed by the comprehensive review of this information in the 2009 NRC report. The Becker et al. (2009; 2011) papers use statistical methods to test the effects of multiple potentially confounding factors to assess the influence of mariculture activities (through the proxy variable of oyster harvest level) on harbor seal usage of various haul-out sites in the Estero. The analyses in Becker et al. (2011) provide support for a relationship between levels of mariculture activity and harbor seal haul-out patterns, although the strength of this relationship is relatively weak and localized. The analyses also take account of other factors that are currently considered to affect seal distribution (e.g., El Nio, regional population size, and presence of aggressive elephant seals). However, the statistical correlation between seal distribution and mariculture harvest does not establish a cause-effect relationship. As highlighted in a 2011 Marine Mammal Commission (MMC) report27 and the 2009 NRC report, the surveys underlying these analyses were not designed specifically to assess impacts of mariculture on the seal population. Indeed, no study worldwide has been designed to assess the impact of disturbance (from mariculture or other sources) on harbor seal haul-out distribution patterns. Consequently, "research that has been conducted in Drakes Estero cannot be used either to directly demonstrate any effects of the oyster farm on harbor seals or to demonstrate the absence of potential effects" (NRC, 2009). 26 DEIS, p. 295. 27 In Chapter 3 of the DEIS, the NPS states that the 2011 MMC "report will be reviewed and considered as part of the NEPA process for this EIS," (DEIS, p. 181).

OCR for page 17
Review of the Scientific Information and Analysis 27 The results of Becker et al. 2009 and 2011 have been subjected to significant scientific scrutiny following publication in peer-reviewed publications. A high degree of attention has focused on whether the statistical techniques and data used in the papers were correct. In particular, the MMC report (MMC, 2011) included reviews of this particular study by several statisticians. As a result, both the authors and other parties have employed a variety of different analytical techniques, and carried out analyses both with and without disputed data points. Where improvements have been identified, analyses have been adapted appropriately. This work has involved input from expert statisticians in the field and extensive discussion over the most appropriate statistical technique to use with this type of historical data which is common in many areas of science. The most comprehensive review of concerns about the analyses of the harbor seal data was carried out by experts convened by the MMC. The MMC oversaw additional statistical analyses in accordance with suggestions from an expert in statistical methods used to assess marine mammal populations (selected by the MMC), but these modifications did not significantly change the conclusions in Becker et al. (2011). Both the DEIS and the MMC report recognize the high level of uncertainty in the scientific understanding of population consequences of disturbance, including disturbance specifically related to mariculture activities in the Estero. Importantly, the DEIS does not state that mariculture-related disturbance is likely to be a major driver of harbor seal population dynamics in Drakes Estero (compared, for example, with broader scale El Nio effects which depress seal populations due to decreased prey availability28). However, impacts from mariculture operations do appear to have a greater influence on harbor seal site choice and their resulting fine scale distribution within the Estero, than short-term human disturbance such as that from recreational activity (Becker et al., 2011). Information on daytime disturbance levels is highly uncertain, and no data on disturbance during non-daylight hours exist even though these could also potentially influence daily haul-out distribution, site selection, or behavior. There have been no studies that relate the medium or long-term impacts of mariculture to critical life functions such as reproduction and foraging. Overall, the harbor seal population has been increasing over the past two decades, coincident with the mariculture activities at high and low levels of production. It remains unknown whether mariculture activities have resulted in a lower rate of population increase within Drakes Estero relative to the level of increase observed in the wider regional population. II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF UNCERTAINTY, ALTERNATE CONCLUSIONS Viewed alongside peer review results of short-term disturbance effects in other areas (reviewed in the NRC, 2009 report), the information presented in the DEIS supports the conclusion that alternatives B, C, and D would likely result in moderate adverse impacts on harbor seals due to potential displacement from preferred haul-out sites. The assumption that production level generally correlates with the level of mariculture activities is uncertain, preventing discrimination of the predicted impact levels based on measurable differences between alternatives B, C, and D. In contrast, alternative A, after the initial short- term impacts during equipment review removal, would be expected to lead to fine scale changes in harbor seal distribution that reflect natural site preference and responses to natural, as opposed to anthropogenic, environmental variation. The level of uncertainty associated with this predicted impact is high due to the lack of a definite cause-effect relationship between harbor seal disturbance and mariculture activities. Overall, the best available scientific information was used in the DEIS. However, the studies were not designed to test specific hypotheses on the effects of disturbance (from DBOC or other activities), so confounding factors (e.g., coastal El Nio conditions, predator disturbance events at other haul out sites) preclude establishment of a cause-effect relationship unique to mariculture activities. The committee is not aware of any data supporting other hypotheses to explain these patterns, and given current understanding of potential disturbance effects in wildlife populations, support a conclusion that moderate impact of mariculture activity is the most parsimonious and reasonable conclusion to be drawn from available data. The suggestion that the extension of the DBOC lease (alternatives B, C, and D) will have moderate adverse impacts on harbor seals is consistent with the peer reviewed literature, and reasonable given current general understanding of the potential impacts of chronic and cumulative disturbance on pinnipeds and other wildlife populations. 28 www.nps.gov/pore/naturescience/harbor_seals.htm.

OCR for page 17
32 Scientific Review of the DEIS DBOC SUP 1939; Salamunovich, 1987; Martin, 1995; Bond, 2006). These taxa are not unique, or in some cases even common, to eelgrass habitats and in some cases (Corophium spp.) are more typical of unconsolidated, unvegetated estuarine sediment environments. The DEIS also appropriately recognizes that racks used in commercial shellfish operations may have implications to juvenile steelhead use of Drakes Estero, although the potential mechanism are likely to differ from those proposed. While there has been documentation of structures in other shallow estuaries attracting predatory fish and birds, most or all of that evidence (e.g., The Watershed Company, 2000) originates from lakes or large structures in estuaries, and relatively few from intertidal structures such as those utilized in Drakes Estero. However, observations and experiments have extensively documented that shading by the structures can cause adverse behavioral responses by juvenile salmon migrating in estuarine and nearshore waters (Nightengale and Simenstad, 2001; Ono et al., 2010). This alternative mechanism, while not developed in the DEIS, would lend support to impact conclusions related to central California steelhead. II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF UNCERTAINTY, ALTERNATE CONCLUSIONS For each species, the DEIS categorizes alternative A as being long-term beneficial, and alternatives B, C, and D as having long-term minor adverse impacts. The committee proposes no alternate conclusions to the DEIS findings for special-status species. The conclusions regarding the Myrtle's silverspot butterfly, California red-legged frog and California least tern are determined to have low levels of uncertainty. Although the paucity of data associated with impacts of the proposed alternatives on western snowy plover, central California coho and central California steelhead leaves these conclusions with moderate uncertainty, the committee finds that overall, reasonable deductions were drawn using the available scientific information as applied under the impact definitions used in the DEIS. However, some of the impacts currently ranked as minor could arguably be reclassified as negligible if that impact category were included. III. WAYS TO REDUCE UNCERTAINTY Myrtle's Silverspot Butterfly None. California Red-legged Frog None. Western Snowy Plover A more careful description of breeding and over wintering ranges regionally would place impacts to this special-status species in better context. Drakes Estero is within the northern ranges for both, and likely on the northern fringe of the breeding range with a majority of the overwintering populations occurring from just north of Drakes Estero down to Baja California. California Least Tern Data from Christmas Bird Counts and/or Breeding Bird Survey could provide insights on the temporal changes in the occurrence of this bird species locally and regionally. Central California Coho, Oncorhynchus kisutch The effects of the proposed alternatives on juvenile coho salmon in Drakes Estero are supported under the designation of "critical habitat" but the connection between DBOC activities and coho habitat quality are not documented. As described in the Impacts on Fish and Wildlife Habitat-Fish resource section, Beck et al. (2001) make a strong argument that nearshore fish habitats provide nursery functions for juveniles if they contribute disproportionately to the size and numbers of adults relative to other juvenile habitats; stating "It is not sufficient to measure a single factor such as density of juveniles." If changes in the conditions of Drakes Estero could potentially alter nursery habitat functions such as refuge from predation, foraging habitat and prey resources for juvenile coho salmon, the DEIS should specifically describe how those functions would be significantly affected by the alternatives. For purposes of analysis appropriate to the life history of juvenile coho, tidal freshwater wetlands should also be included in the project area. The statement that "While the designated critical habitat in these creeks is close to Drakes Estero, location coordinates of the upstream and downstream limits provided by NMFS show that they are not included in the project area (NMFS, 2005)" seems to assume that freshwater constitutes the only critical habitat for steelhead, when in fact the Estero itself is overall

OCR for page 17
Review of the Scientific Information and Analysis 33 critical habitat. However, important physiological transition zones for juvenile coho in the tidal freshwater reaches of Schooner Bay and Home Bay should be included in the DEIS assessment. As with central California steelhead, the effects of culture racks on the natural behavior of juvenile coho salmon, induced primarily by shading, would suggest that changes in these structures under the different alternatives could induce changes in coho habitat utilization. Central California Steelhead, Oncorhynchus mykiss The nursery function of the Estero for juvenile steelhead should be examined in more specific detail by analysis of the trophic linkages to different habitats in the Estero. Most notably, DEIS analyses related to the documented prey resources of juvenile steelhead in estuaries and lagoons (i.e., Impacts on Wildlife and Wildlife Habitat-Benthic Fauna) should be considered in regard to juvenile salmonid habitats. Those habitats, in addition to eelgrass, should be considered in the assessment of potential impacts to steelhead under the DEIS alternatives. Coastal Flood Zone I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS Floodplains are fluvial lands formed from freshwater streams and rivers that receive floodwaters once the water has overtopped the bank of the main channel. In contrast, flood zones are geographic areas defined by the Federal Emergency Management Agency (FEMA) based on flood risks. FEMA has not mapped the flood zone for Drakes Estero. For purposes of the DEIS, an elevation of 9.0 feet NAVD- 88 was estimated as the flood zone elevation for Drakes Estero, based on a land survey at the onshore facilities and gauge data from the Point Reyes Light Station. Drakes Estero (including the waters of the Estero and surrounding lands up to ~9.0 feet above sea level) falls within the coastal flood zone (an area with a probability of being inundated at least once every 100 years due to coastal storms and tsunamis). Alternatives A, B, and C do not include any new upland structures. Only alternative D would include new or modified structures within the flood zone, requiring the need for a Statement of Findings in accordance with NPS Director's Order 77-2 to ensure the structure is properly designed and constructed in a way to minimize impacts to the flood zone. Vegetated intertidal wetlands, sand bars and subtidal eelgrass beds buffer uplands against storm surges and tsunami. These are prominent habitats in the project area. Mud flats and sandbars dominate the intertidal throughout the project area, except at the heads of the bays where vegetative wetlands predominate.36 Regarding coastal flood zones in Drakes Estero, at least two aspects of impact are relevant for the DEIS: the extent that DBOC operations impact habitat buffers in the flood zone during and after flooding events; and the flood water storage volume of the floodplain. Impacts on habitat buffers in the flood zone (e.g., the extent and fragmentation of vegetated tidal wetlands) are not addressed in the DEIS. The DEIS states that removal of DBOC infrastructure would result in relative long-term beneficial impacts under alternative A by eliminating risks associated with "dislodged and damaged materials floating and washing ashore during a flood event."37 Assuming that DBOC would remove and dispose of debris that washes ashore in a timely fashion, these events are unlikely to have measurable long-term adverse impacts on Drakes Estero habitats and the resources they support. Beyond short-term adverse impacts on the near shore environment, it is not clear how resources in the Estero would experience "damage"38 in the long term. The DEIS also states that alternative A would remove "materials that have the potential to adversely affect water quality if spilled during a flood event, such as stored fuels and wastewater."39 These potential impacts should be considered in the context of the tidal flushing dynamics of Drakes Estero and the magnitude of post-flooding runoff that could disperse and/or export the contaminants. The DEIS also states that the potential displacement volume of infrastructure and shell piles within the floodplain under alternatives B, C, and D may reduce the storage capacity for floodwaters in Drakes Estero (which would increase the height and spatial extent of a flood event). Conversely, the long term beneficial impact of alternative A is described as an increase in flood water storage, attributed to the removal of existing onshore infrastructure and shell piles, the displacement volume of which would be 36 DEIS, p. 166. 37 DEIS, p. 330. 38 DEIS, p. 331. 39 DEIS, p. 330.

OCR for page 17
34 Scientific Review of the DEIS DBOC SUP replaced by flood waters. However, in the absence of a quantitative analysis, this is little more than speculation. What is the volume of the shell pile and infrastructure in the flood zone that would be submerged in a 100 year flood relative to the total volume of water in a storm surge that reaches 9 ft NAVD-88? II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF UNCERTAINTY, ALTERNATE CONCLUSIONS Given the lack of information on the displacement volume of onshore structures described above, the uncertainty level is high that flood zone impacts in alternatives B, C, and D would be moderately adverse. It is the conclusion of the committee that a quantitative analysis is important for determining the magnitude of the impact. For example, alternatives B, C, and D were judged to have the same "moderate" intensity of impact even though the displacement volume of existing structures was not calculated and alternative D would include new or modified infrastructure. III. WAYS TO REDUCE UNCERTAINTY Since most of the vegetated wetlands are located near the heads of the bays (Figure 3.1), it appears unlikely that the DBOC upland footprint (which is seaward of vegetated wetlands) measurably impacts the resilience of the Estero to storm surge and tsunami. However, calculation of the volume of water displaced by the DBOC structures relative to the volume of 100-year floodwater in Drakes Estero would provide a quantitative basis for assessing impacts of DBOC on the flood plain and thereby reduce uncertainty. Sea level rise over the next 10 years (estimated at up to 5.9 inches for the California coastal zone)40 has the potential of increasing the vulnerability of near shore infrastructure and terrestrial ecosystems to storm surge and tsunami. Thus, it would be useful to determine the spatial extent of inundation that would result given a 5.9 inch rise in sea level. Further analysis of the flushing rate of Drakes Estero (as discussed in the Water Quality section below) would also help inform the potential ecological impacts of flood-related contaminants from DBOC operations. Water Quality I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS In practice, water quality is generally assessed in terms of a set of key indicators which usually include the following: concentrations of xenobiotics (pesticides, herbicides), enteric coliform bacteria, toxic phytoplankton, nutrient concentrations, turbidity, phytoplankton biomass, suspended particulate organic matter, the attenuation of downwelling radiation, and the spatial extent and condition of submerged aquatic vegetation (e.g., eelgrass) (Hoffman et al., 2003; Bricker et al., 2007). In the DEIS however, quantitative indicators of water quality are limited to xenobiotics in sediments, enteric coliform bacteria, and the occurrence of toxic phytoplankton events. Coliform bacteria levels (an indicator of land-based waterborne pathogens) have been used to classify areas as prohibited for shellfish harvesting, limited to the upper reaches of Barries, Creamery, and Home Bays where contamination from cattle occurs. Therefore, DBOC does not use these areas for shellfish cultivation.41 Concentrations of these indicators are of concern to shellfish producers and consumers; however they have not been associated with impacts of DBOC operations on water quality. To evaluate the impacts of DBOC operations on water quality requires information on potential impacts of human activities (e.g., land-based inputs of pollutants via impervious surfaces, recycling water from the Estero through settling tanks and washing stations, sediment re-suspension by motor boats, leakage of oil and gas from engines) and of cultured shellfish (filtration of particulate matter, deposition of feces and pseudofeces, nutrient recycling) on water quality. However, there is a paucity of data on these water quality parameters for Drakes Estero. The DEIS states that, "the positive ecosystem effects typically attributed to bivalves, such as nutrient cycling and water clarity, would be expected to be relatively minor in west coast estuaries like Drakes Estero. This is because the nutrient dynamics in these systems are driven by coastal upwelling and a strong tidal cycle which flushes small estuaries like Drakes Estero on a daily basis."42 The DEIS 40 DEIS, p. 170. 41 DEIS, p. 199, Figure 3-7. 42 DEIS, p. 341.

OCR for page 17
Review of the Scientific Information and Analysis 35 assumes that supplies of nutrients and changes in phytoplankton biomass are driven primarily by imports from adjacent coastal waters and not by processes within the Estero (e.g., nutrient regeneration, phytoplankton blooms, draw-down of phytoplankton biomass), but does not provide a firm basis for this assumption. As described below, it is possible to develop rough estimates of the effects of cultured shellfish on water quality even with relatively limited data. The rate of water exchange in coastal lagoons is an important parameter for determining the impacts of human activities and natural processes on water quality and its capacity to support living resources. Thus, quantifying flushing or residence times43 is important to understanding and managing environmental impacts. The estimate of flushing time used in the DEIS for Drakes Estero is about one day, assuming that the water is completely mixed from the head of the bays to the mouth of Drakes Estero during the semidiurnal tidal cycle.44 If this were the case, horizontal gradients in salinity and temperature from head to mouth would not develop. However, such horizontal gradients have been observed in summer and salt balance calculations suggest that residence times range from approximately 16.4 days in the upper reaches of the bay to about 7.6 days at the base of Schooner Bay (where it joins the main waters of Drakes Estero) (Robart and Largier, 2008 abstract). Since phytoplankton growth rates are well within this range (e.g., phytoplankton cells double every 1 to 5 days), phytoplankton blooms within Drakes Estero could reduce light penetration and increase the food supplies for filter feeders. Under these circumstances, water properties in the finger bays of the Estero where shellfish are grown could be influenced more by these filter feeders than assumed in the DEIS. In fact, phytoplankton blooms have been observed during summer in parts of Drakes Estero (Buck et al., 2011 abstract). Observations reported in an abstract by Buck et al. (2012) provide some evidence that oyster- filtration could impact phytoplankton biomass in the Estero. Specifically, chlorophyll-a distributions (an index of phytoplankton biomass and component of turbidity and suspended organic matter) were found to be high near the mouth of Drakes Estero and to decrease by about 30% near the mouth of Schooner Bay where culture racks are located. Thus, distributions of salinity and chlorophyll-a in the Estero provide circumstantial evidence that oyster filtration could reduce suspended organic matter in Drakes Estero. Likewise, there is preliminary evidence from distributions of ammonium that nutrient recycling may provide an important source of regenerated nutrients within Drakes Estero (Buck et al., 2012 abstract). A second approach45 to assessing the scale of potential impact of cultured oysters on water quality is to estimate the volume of water filtered by the cultured oysters. Estimates of oyster filtration rates have been reported from 20 to 50 gallons/oyster/day (0.075 0.190 m3/oyster/day) during the growing season (NOAA, 2011;46 Powell et al., 1992). These must be considered rough estimates because they assume that oyster filtration rates are constant regardless of species, body size, current speed, temperature, and the concentration of food particles (e.g., phytoplankton) (Powell et al., 1992; Gerdes, 1983; Kobayashi et al., 1997). For example, Gerdes (1983) reports a wide range of filtration rates for Pacific oysters of various sizes (0.01 0.13 m3/day/oyster) and shows that rates can vary by two-fold in experiments at 20C using different concentrations of phytoplankton (Isochrysis galbana) as food. Rough estimates of the mean volume of water filtered by the cultured oysters can be made by multiplying the number of cultured oysters by the filtration rate. This can then be compared with an estimate of the volume of the project area based on the surface area (1,700 acres or 74,052,000 ft2) times the mean depth of Drakes Estero (6.5 ft) as follows: 74,052,000 ft2 x 6.5 ft = 481,338,000 ft3 or 13,629,974 m3. Mean annual production of DBOC oysters during 2007-2009 has been estimated to be 5,340,000 oysters.47 Using an oyster filtration rate of 0.075 m3/oyster/day as an example, the volume of water filtered by cultured oysters would be on the order of 400,500 m3/day (about 106 million gallons/day). Therefore, the time required for cultured oysters to filter that volume of water (project area volume/oyster filtration volume) would be about 34 days. Although clearly a rough estimate, this indicates that in the middle to upper reaches of Drakes Estero, where the residence time is in the range of one to two weeks, 43 Flushing time = water volume / water inflow (or outflow) (Sheldon and Alber, 2006) and is often used interchangeably with residence time which is dependent upon the extent of mixing (Monsen et al., 2002). 44 DEIS, p. 159. 45 The prepublication of this report included two estimates of the volume of Drakes Estero one of which was later found to be incorrect. Therefore, the faulty calculation has been removed and the text of the final publication has been revised to be consistent with these changes. This change does not affect the committee's conclusions. 46 Available at: http://www.habitat.noaa.gov/abouthabitat/oysterreefs.html. 47 DEIS, Chapter 2, p. 62.

OCR for page 17
36 Scientific Review of the DEIS DBOC SUP respectively (Robart and Largier, 2008 abstract), the potential effect of cultivated oysters on water quality could be significant, an observation that is consistent with the occurrence of phytoplankton blooms within the Estero and the draw down in phytoplankton biomass observed in the upper reaches by Buck et al. (2012, abstract). The DEIS concludes that ecosystem services by bivalves related to reductions in suspended particulate matter (turbidity), increases in light penetration (downwelling radiation) and levels of eelgrass production only provide "localized benefits to water quality"48 because of the short flushing time (1 day) and the assumption that turbidity is low. However, concentrations of suspended particulate matter appear to be appreciable (up to 100 mg liter-1) in both Estero de Limantour and the higher reaches of Drakes Estero, and a Secchi disk depth reading as shallow as 0.45 m has been observed in winter (Wechsler, 2005). This, and the discussion above, suggests that water filtration by cultured oysters may, at times, provide these ecosystem services. II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF THE LEVEL OF UNCERTAINTY, ALTERNATE CONCLUSIONS Summing across the parameters contributing to water quality, the DEIS concludes that the action alternatives would have a minor adverse impact. This is based on assessment of minor adverse impacts from increased turbidity due to sediment disturbance, leachates from lumber used in the docks and racks, and a small amount of stormwater runoff, outweighing "local" beneficial impacts from filtration by the cultured shellfish. However, data on water quality parameters that could be affected by shellfish culture (e.g., turbidity, suspended organic matter, phytoplankton biomass, nutrient concentrations) were not provided in support of this conclusion. Thus, given the small amount of information provided in the DEIS related to water quality impacts by DBOC, conclusions reported in the DEIS concerning impacts of DBOC operations on water quality are assigned a high level of uncertainty by the committee. As discussed above, research on filtration rates of oysters in shallow estuaries such as Drakes Estero suggests that oyster mariculture could potentially increase water clarity under alternatives B, C, and D compared to alternative A. However, a simple calculation of the chlorophyll-a equivalent fraction of total particulate organic carbon suggests that phytoplankton biomass may be a small fraction of total suspended organic carbon.49 This can be interpreted in two ways. If phytoplankton biomass accounts for most of the suspended organic carbon (which is unlikely given the potential supply of organic detritus from decaying eelgrass), oyster filtration may be insignificant relative to tidal flushing. Alternatively, decaying eelgrass may account for most suspended organic carbon, and oyster filtration could be an important process regulating accumulations of organic matter and nutrient recycling within Drakes Estero. This casts further uncertainty concerning the impacts of oyster mariculture on water quality, and suggests an alternate conclusion could be equally reasonable, i.e., impacts of alternatives B, C, and D may be negligible or even beneficial. III. WAYS TO REDUCE THE LEVEL OF UNCERTAINTY The level of uncertainty could be reduced if all data from Drakes Estero currently available for assessing water quality were compiled and evaluated. In addition, the DEIS could be strengthened by an explicit treatment of the factors needed to evaluate the effects of shellfish cultivation on concentrations of suspended particulate matter, nutrient cycling, benthic-pelagic coupling and the spatial extent and condition of eelgrass beds in Drakes Estero as a whole. To diagnose water quality status and trends in Drakes Estero in the future, the use of appropriate indicators and mathematical models would be necessary and is common practice in the management of water quality and living resources. This would require collection of additional data not currently available on water quality parameters (as discussed above) to enable implementation of validated numerical models of hydrodynamics and water quality. 48 DEIS, p. 342. 49 Using a C/Chlorophyll ratio of 50 (by weight) to convert chlorophyll to particulate organic carbon (POC) and a factor of 3 to convert -1 -1 POC to particulate organic matter (POM, or dry weight), 3 g liter of chlorophyll equates to 450 g liter of POM which is a small fraction of the material in suspension.

OCR for page 17
Review of the Scientific Information and Analysis 37 Soundscapes I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS The DEIS contains some excellent background information in Chapter 3 on (1) NPS soundscapes management policies that have been created in the last 10-12 years, (2) sound levels and effective communication distances (to provide perspective on the sound level for the general reader), (3) how sound levels are measured and reported traditionally, and (4) how sound is impacted by the sender, receiver and medium through which it passes. The DEIS concludes that implementation of alternative A, after an initial increase in sound levels associated with removing the DBOC footprint, will reduce overall anthropogenic noise levels and restore Drakes Estero soundscapes to a more natural state. This conclusion is well supported. The DEIS concludes that alternatives B, C, and D would be expected to result in major adverse impacts due to louder soundscapes compared to alternative A. Originally, the term "soundscape" was used to describe the acoustic environment as perceived by humans (e.g., Schaefer, 1969). Although no standards exist yet for documenting soundscapes, the field is starting to define features needed to characterize soundscapes for humans (e.g., Raimbault and Dubois, 2005), including soundscapes in parks and wilderness areas (Fidell et al., 1979; Miller, 2008; Schomer et al., 2009; Benfield et al., 2010). NPS has developed regulations to manage soundscapes and preserve natural quiet as experienced by people based on detectability of human-made noise (Miller, 2008). The meaning of "soundscapes" for wildlife is less understood, but in principal would also require documenting the acoustic environment in space and time. Although NPS has considered its regulations in relation to wildlife management (Hatch and Fristrup, 2009), there has not been a focused effort to define soundscapes for wildlife management in the U.S. Directed efforts are currently underway in Europe (Pijanowski et al., 2011; Villanueva-Rivera et al., 2011). The DEIS uses the term soundscape to refer to all aspects of the acoustic environment, without distinguishing between the perceived sound environment and the measured sound captured by the monitoring equipment. An essential feature of a soundscape is the variation over space and time. However, the environmental sound levels presented within the DEIS were based on measurements taken from a single location (on a bluff above Drakes Estero) over 30 days in late summer. This does not accurately represent the temporal or spatial variability of the project area. Using data from a single month misses variability due to seasonal weather and wind patterns. At the same time, limiting measurements to a single location cannot capture gradients in sound levels with distance from the source. Propagation characteristics are complex in coastal regions and extrapolating a single set of measurements to an area as large as Drakes Estero does not capture this complexity or variability. Moreover, insufficient information is provided for an accurate representation of the spatial and temporal variability of ambient sound levels. In addition to L50 values, which gives an estimate of the mean, the ranges of those measurements are needed as well as the unit of analysis used in the calculations. For example, an L50 of 50 dBA could be calculated from data with a range of 30-70 dBA or from 10-90 dBA. A Leq50 measurement gives a more representative value because it accounts for duration, although it tends to overestimate noise in quiet environments because it is sensitive to high amplitude transients. Alternatively, characterizing the variability of sound could also be accomplished using several percentiles (e.g., L90, L50, L5). Volpe (2011) reports both L50 and Leq values, which differ by up to 6 dBA, a difference large enough to affect the estimated levels of impact of the alternatives which compare ambient sound levels for equipment similar to those used by DBOC. Assessment of the natural variability of the Drakes Estero soundscapes is essential for providing the proper context in which to analyze the influence of DBOC activities on the soundscapes. As noted above, the site for audio recording was located on a bluff above Drakes Estero. It is not known how representative that measurement is of the soundscapes in the project area where impacts were assessed by the DEIS. Soundscape patterns also differ considerably between day and night so there could be a range of impacts dependent on whether sounds from DBOC activities occur during biologically sensitive times of day (e.g., dawn chorus, peak foraging times). This would require day and night measurements of DBOC activities at ambient levels. The DEIS states that "daytime and nighttime 50 Leq is defined as the sound pressure level of a noise fluctuating over a period of time T, expressed as the amount of average energy.

OCR for page 17
38 Scientific Review of the DEIS DBOC SUP hours" are treated essentially the same;51 however, the literature shows that nighttime natural sounds are much more complex in terrestrial environments than daytime sounds and that the dawn and dusk chorus have the most complex natural sounds (Pijanowski et al., 2011). Another important consideration is the frequencies of noise and the potential for acoustic masking of vocalizations of many of bird, mammal and amphibian species that occur in the project area. There is strong evidence in the literature to suggest that many bird species will raise the pitch of their songs or sing at night if noise is produced at frequencies that would mask their communication (Warren et al., 2006). This additional energy expenditure may affect the fitness of an individual. This type of data could be readily obtained from a set of acoustic recorders to capture all sounds. The duration of sounds produced by DBOC activities were not well presented in the DEIS. For instance, the DEIS did not take into account the duty cycle (i.e., activity pattern) or the closest point of approaches for boats, the number of vessel events, peak sound level, etc. The time period over which a pneumatic drill is used is not equivalent to the time the drill is in operation. It is especially critical to distinguish between continuous, intermittent, and impulse sources. Assuming that the 71 dBA value reported in DEIS Table 3-3 for the boat is during the closest point of approach, a single observation point (such as a visitor hearing the boat from shore), measures the maximum approach sound level which is only experienced for a short period of time. A more accurate measure would account for the range in sound level experienced from a single location for the duration of the audible boat noise. The DEIS presents measurements and calculations based on dBA weighting which is directly related to human hearing. Weighted ambient and source levels provide only one measure of sound occurrence. The use of A-weighted52 measurements is standard in human noise impact studies, but their use in wildlife impact assessments is still unproven. The committee finds that, given that the Acoustic Society of America is considering standards for reporting sound levels in quiet areas, using unweighted and 1/3 octave values, this might be more informative in combination with the A-weighted measurements. The lack of standards in soundscape measurements leads to a large level of uncertainty in the use of single metrics to assess noise impacts on wildlife. The committee is unaware of any data with uniform sound levels or propagation effects over the course of a full day as stated in the DEIS.53 The opposite is more reasonable due to bird choruses at specific times of day, daily wind patterns, human activity, etc. Assuming uniform sound levels means that the DEIS may have underestimated impacts to humans and animals active during the day. However, it is also true that the impacts may be overestimated for nocturnal animals. Although the DEIS acknowledges there could be potential impacts on harbor seals from underwater sound generated by DBOC motor boats, no underwater measurements were given upon which to base conclusions on underwater soundscapes under any of the alternatives. The DEIS gives a brief but accurate description of the literature related to impacts of noise on harbor seals and marine mammals.54 There are ample peer-reviewed papers on the short-term impacts of underwater noise on marine mammals at an individual level for a few species, but little scientific evidence is available to determine the effects of noise on marine mammals at the population level (NRC, 2003; see Harbor Seal section). There are many propagation models available to model sound from a source to a receiver. The DEIS provides sound levels from motorboats and associated consequences.55 The committee assumes simple spherical spreading was used for these calculations, as this method was used elsewhere in the DEIS. Simple spherical spreading is often not the most accurate model to use. In addition, consequences for communication disruption within 50 ft of a source would only realistically impact DBOC staff near the source. Kayakers or park visitors would be unlikely to spend time in such close proximity to DBOC activities and sources. It would be more accurate to show propagation model results from sources in different places around the area of DBOC operations to more accurately illustrate propagation between sources and potential receivers. 51 DEIS, p. 351. 52 A-weighting is the most commonly used weighting scale for sound, because it indicates the risk of damage to the human ear. Sound level meters set to the A-weighting scale will filter out much of the low-frequency noise they measure, similar to the response of the human ear. Noise measurements made with the A-weighting scale are designated dBA. 53 DEIS, p. 351. 54 DEIS, p. 207. 55 DEIS, p. 355.

OCR for page 17
Review of the Scientific Information and Analysis 39 The proper application of propagation modeling also pertains to the conclusions made in the DEIS in regard to estimating the number of 60 dBA sources at 50 ft (NPS regulation) when describing the difference between ambient levels and DBOC activity impacts.56 The DEIS compares 316 regulation sources to the 25 dBA difference between pneumatic drill levels and ambient levels and gives a worst case scenario. The worst case scenario most likely assumes the sources are incoherent and additive, but these assumptions are not clearly stated. II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF UNCERTAINTY, ALTERNATE CONCLUSIONS The DEIS concludes that alternatives B, C, and D would present a major adverse impact. The committee assigns a high level of uncertainty to this conclusion regarding impacts of DBOC operations on the soundscape because there are no data on underwater sound, lack of a scientifically-based sampling scheme (e.g., poor spatial and temporal coverage), lack of direct measurements of sound levels associated with DBOC activities, limited data on how noise impacts harbor seals at the population level, unknowns related to boat traffic with potential decreases or increases in production, and uncertainty associated with potential changes in human noise from onshore improvements proposed in alternative D. Because of these unknowns, the committee finds that other conclusions could be reached for alternatives B, C, and D, i.e., adverse impacts could be classified as moderate or minor, rather than major, even with the impact criteria used in the DEIS. The committee concurs with and assigns a low level of uncertainty to the conclusion that alternative A would have beneficial impacts since anthropogenic noise levels would be reduced in the long-term. III. WAYS TO REDUCE UNCERTAINTY The high levels of uncertainty for the assessed impact levels for alternatives B, C, and D are due to the lack of information on underwater soundscapes, in-air soundscape variability, and presentation of unweighted sound levels to best interpret impacts on animals such as birds and harbor seals. Some of the uncertainty could be reduced if the DEIS used data more fully representative of the temporal and spatial variability in ambient sound levels, by using all of the data (winter and summer for all stations) provided in Volpe (2011). In addition, the DEIS could better capture the total ambient sound level variability by including values for min/max, quantiles, as well as details of the environmental sound study such as the specific dates and continuity of data collection. To better account for effects of sound on humans and wildlife would require presenting both dBA and unweighted values, the latter presented as peak values and root-mean square values with specified frequency bandwidths and duration. Spectra across a wide frequency range would be most appropriate. Uncertainty with regards to impacts on harbor seals could be reduced through measurement of underwater sound levels and characterization of underwater contributions from all sound sources. Additionally, collection of ambient sound levels inside the project area closer to the impacted fauna and to some of the Seashore visitors, such as hikers and kayakers, would provide a more realistic baseline for assessing sound sources from DBOC. There would be less uncertainty in the DBOC sounds sources if the DEIS did not use proxies for sound levels and if the measurements accounted for duty cycle (continuous vs. intermittent vs. impulse sources) to estimate the percent of time various DBOC activities impact the soundscape. Socioeconomic Resources I. QUALITY OF INFORMATION AND ANALYSIS AND INFORMATION GAPS A socioeconomic assessment in a NEPA document typically identifies potential changes in employment levels, housing requirements, public service needs, and tax revenues as a result of implementing the proposed action and alternatives. This is the approach taken in the DEIS, but it does not constitute a scientifically sound economic cost-benefit analysis and these metrics are not accepted metrics of impact or value in economics. Although not required by NEPA (see 40 CFR 1502.23), the committee concluded that a cost-benefit analysis using economic metrics of value, incorporated by reference or appended to a final EIS, would more fully inform decision makers on the socioeconomic consequences of the proposed alternatives for the DBOC SUP. The remainder of this section describes 56 DEIS, p. 354.

OCR for page 17
40 Scientific Review of the DEIS DBOC SUP the features of a cost-benefit analysis and explains why it would be more informative than the assessment presented in the DEIS. In a cost-benefit analysis, socioeconomic impact is the impact on society, including the economic value to society of the impact, whether beneficial or adverse. The economic impact includes both market and non-market impacts such as the impact on producers and consumers of shellfish (a market impact), and the impact on recreational enjoyment (both a market and a non-market impact). For producers and workers, the economic measure of a change in their wellbeing is the change in income and profits in that industry.57 For consumers, a change in their wellbeing is measured in monetary terms through an income equivalent--namely, the change in income that is equivalent in its impact on their wellbeing to the change being evaluated (say, a change in prices). Conceptually, there are two possible measures of income equivalence: the maximum amount of income that the person would be willing to give up (to pay) in order to secure the change, or the minimum amount of additional income that the person would want to receive as compensation for foregoing the change; the former is known as the willingness to pay (WTP) measure, while the latter is the willingness to accept (WTA) measure.58 For a marketed good such as shellfish, the economic metric for the impact on producers and consumers is the change in producer's plus consumer's surplus. In the case of recreation, there may not be a change in the supply of recreation per se but, rather, a change in the quality of the recreation and therefore the degree of enjoyment. This, too, can be measured by the income equivalence measures of WTP or WTA. The change in the consumer's surplus from recreation is an example of what is known as a use value. The valuation of wilderness can also involve what is known as non-use value. A person might value the establishment of a new wilderness area because she wishes to experience it herself, for example by viewing wildlife there or hiking; that would be a use value. Or, she might place a value on the establishment of a new wilderness area even if she knew that she herself would never visit it. She might feel it desirable that more wild places should exist in California and she might be willing to pay money out of her own pocket to bring this about, even if she had no plan to visit them herself; that would be a non- use value.59 The economic metrics, whether for marketed or non-marketed items and whether for producers or consumers, are measures of net value (i.e., gross value minus cost). Consumer expenditures are not an accurate metric of value. A consumer may spend $50 per month on shellfish, but this only provides a lower bound on the gross value, because the consumer may place greater value in eating shellfish, thus yielding a consumer surplus in terms of his net value. These concepts are well understood in economics and have been employed for almost 30 years in economic evaluations of environmental and other programs by the federal and state agencies. A major example in California was the Mono Lake EIR (Jones and Stokes, 1992), which considered use values for marketed items, including water supply and hydropower, and use and non-use value for non-market items such as recreation and the alternative levels of inflow to Mono Lake. The socioeconomic assessment presented in the DEIS includes an impact analysis and a cumulative impact analysis. As defined in the DEIS, cumulative impacts are those which reflect both the impacts of the proposed action and impacts of other past, present, and reasonably foreseeable future actions. A well-established principle in cost-benefit analysis is that the analysis should involve a "with and without" comparison. With the application of this principle, a project would be assessed "based on the most likely conditions expected to exist in the future with and without the project," and is a requirement for an economic cost-benefit analysis conducted by a federal agency.60 Hence, in a cost-benefit analysis an assessment of cumulative impacts would be valid if it compared the cumulative impact of "other past, present, and reasonably foreseeable future actions" for the baseline (e.g., no action alternative A) with the cumulative impact of the alternative (e.g., action alternative B, C, or D). The DEIS identifies socioeconomic impacts associated with commercial shellfish culture and recreation/tourism. While the DEIS focuses on a change in shellfish production, which by itself is not an accepted economic metric, a cost-benefit analysis would focus on the change in consumer's plus producer's surplus in the California (or San Francisco Bay Area) shellfish market. This economic metric 57 This is also referred to as the change in producer's surplus. 58 The two measures are often referred to as the change in consumer's surplus. 59 The two values are not mutually exclusive: a person might have both a use value and a non-use value for the same item. 60 Economic and Environmental Principles and Guidelines for Water and Related Land Resources Implementation Studies (1983); para 1.4.9, page 4 (http://planning.usace.army.mil/toolbox/library/Guidance/Principles_Guidelines.pdf).

OCR for page 17
Review of the Scientific Information and Analysis 41 allows for the possibility of substitution of other sources of supply which could mitigate to some degree the elimination of production by DBOC.61 Further, with regard to the socioeconomic impact on recreation and tourism, the DEIS notes correctly that (1) visitation of DBOC accounts for a very small share (about 2.5%) of total visitation to the Seashore, and (2) some of these visitors may have been participating in other types of recreation at the Seashore in addition to visiting DBOC and therefore could be expected to continue to come to the Seashore even without DBOC. The DEIS also indicates that the creation of additional wilderness acreage under alternative A might attract some additional visitation. Although the DEIS discusses changes in the number of visits, the DEIS would need to consider the possibility of a change in consumer's surplus per visit for a scientifically valid cost-benefit analysis. Under alternative D, which includes construction of a new and potentially more attractive building at DBOC, the DEIS states: "This improvement to visitor experience (described further in the "Impacts on Visitor Experience and Recreation" section), could minimally increase annual visitation to DBOC."62 The empirical basis for this assertion, that there would be little change in the number of visitors to DBOC, is not clear. A scientifically valid cost-benefit analysis would account for a potential change in the consumer's surplus per visit as a consequence of the new visitor center. In addition to consumer's surplus from recreation, a cost-benefit analysis would also consider the non-use value for an increase in wilderness area. Alternative A extends by 8,530 acres what is the only marine wilderness area (currently at 24,200 acres) on the west coast. As is evident from the public comments submitted on the DEIS, some members of the public have a significant non-use value for the removal of DBOC and the creation of additional wilderness area under alternative A. But others may not.63 A quantitative estimate of the percent of the area population with a positive non-use value for this increment in wilderness area, and of the typical amount of that non-use value, would be a useful addition to the EIS. As mentioned in Chapter 2 of the committee's report, there are no gradations for beneficial impacts in parallel with the minor, moderate, and major gradations of adverse impacts. This results in an asymmetric assessment of the no action (A) and action alternatives (B, C, and D) in the DEIS. For instance, under alternative B, DBOC's operations would be largely unchanged from existing conditions, while under alternative A, DBOC would cease operation. Alternative A "could result in long-term major adverse impacts to California's shellfish market."64 Alternative B "would result in a long-term beneficial impact to shellfish production in California."65 If eliminating DBOC entails a major adverse impact, then maintaining DBOC should lead to a major beneficial impact. II. REASONABLENESS OF THE CONCLUSIONS, ASSESSMENT OF UNCERTAINTY, ALTERNATE CONCLUSIONS The conclusions reached in the DEIS might change if a more rigorous, cost-benefit analysis were conducted. The committee makes no finding as to whether the DEIS socioeconomic analysis is sufficient to meet NEPA requirements for such an analysis. However, the committee finds that what is in the DEIS does not constitute a scientifically valid economic analysis. Because the DEIS economic impact assessments were not based on quantitative metrics, it includes inferences and interpretations of impacts that have a high level of uncertainty. For example, even if a person who visited DBOC still continued to visit the Seashore for other types of recreation if DBOC closed under implementation of alternative A, 61 We understand from a DBOC letter dated 6/5/12 that the company provided cost and revenue information to NPS in November 2010, but requested that this information remain confidential. Based on that request, the NPS did not report these data in the DEIS nor use them in the DEIS analysis. In the agricultural economics literature, changes in consumer's plus producer's surplus are often estimated by making estimates (or guesses) about demand and supply elasticities and then applying well established formulas based on first-order approximations. Hence, DBOC's request for confidentiality regarding this data is not an insurmountable barrier to conducting an economic analysis of the change in consumer's plus producer's surplus in the California shellfish market. 62 DEIS, p. 401. 63 A 2003 survey of visitors to the Seashore survey asked respondents (Question 17): "Overall, would you like to see the amount of wilderness at Point Reyes National Seashore increase, decrease, or remain about the same?" Of 418 respondents, 43% said increase; 38% said remain about the same; 2% said decrease; and 18% said don't know. 64 DEIS, p. 393. 65 DEIS, p. 397.

OCR for page 17
42 Scientific Review of the DEIS DBOC SUP there could be some reduction in consumer's surplus for this person.66 Therefore, the committee finds the overall analysis of socioeconomic impact intensities in the DEIS to have a high level of uncertainty. III. WAYS TO REDUCE THE LEVEL OF UNCERTAINTY Conclusions on socioeconomic impacts in the DEIS would be less uncertain if an economic cost- benefit analysis were conducted that included: estimates of change in producer's plus consumer's surplus for shellfish; estimates of possible changes in consumer's surplus through analysis of data available on the consumer's surplus for various recreational activities;67 and an assessment of the significance of the survey data on attitudes with regard to the impact on non-use value. 66 The DEIS notes under the resource category on visitor experience and recreation: "Visitor services are defined by law as public accommodations, facilities, and services that are necessary and appropriate for public use and enjoyment of the Seashore (36 CFR section 51.3)." DEIS p. 382-383, however, it is conventionally considered in socio-economic cost-benefit analysis of this type of program. 67 Kaval and Loomis (2003) provided information to NPS on the average consumer's surplus per person by region for various types of outdoor recreation activity. The DEIS should have considered whether it could have extracted useful information from this or other sources regarding potential changes in consumer's surplus.