Scientific Review of the Draft Environmental Impact Statement Drakes Bay Oyster Company Special Use Permit (2012) / Chapter Skim
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3 Review of the Scientific Information and Analysis Presented in the Draft Environmental Impact Statement (DEIS)
3 Review of the Scientific Information and Analysis Presented in the Draft Environmental Impact Statement (DEIS)
Pages 17-42
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From page 17... ...
· 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.
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From page 18... ...
These activities may have a direct impact on turbidity, sediment dynamics, benthic fauna, harbor seals, 2 DEIS, p.
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From page 19... ...
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.
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From page 20... ...
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?
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From page 21... ...
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.
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From page 22... ...
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.
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From page 23... ...
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)
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From page 24... ...
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)
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From page 25... ...
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.
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From page 26... ...
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 Niño conditions (Becker et al., 2009; 2011)
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From page 27... ...
, 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
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From page 28... ...
However, as discussed in both the 2009 NRC report and the 2011 MMC report, there are weaknesses due to the lack of directed research on disturbance of harbor seals in Drakes Estero, the limitations of the volunteer observer database, and lack of spatially explicit data on mariculture activities. The 2011 MMC report sums it up well: "The Marine Mammal Commission believes that the data supporting the above analyses are scant and have been stretched to their limit.
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From page 29... ...
. For alternative B, the conclusion that this alternative would result in long-term moderate adverse impacts on birds and bird habitat, because noise disturbances from DBOC motorboats and the displacement of natural habitat by shellfish racks and bags "would be clearly detectable and could appreciably affect natural processes," is scientifically sound according to current literature, but it has not been demonstrated in systems like those in Drakes Estero.
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From page 30... ...
It is also logical that there would be short-term adverse impacts of alternative A for two months as DBOC operations are closed and infrastructure removed, followed by long-term beneficial impacts. The presentation in the DEIS would benefit from inclusion of a map of the preferred habitat to illustrate how roads and DBOC onshore operations do or do not overlap with butterfly habitat.
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From page 31... ...
: The DEIS does not include references to support the conclusions regarding coho salmon in the Estero. Coho are not currently found in Drakes Estero, but "the watershed is included in the critical habitat designation because it has habitat elements required by the coho salmon."35 Observations from other comparable ecosystems and current scientific understanding of their nearshore marine ecology allow some logical deductions concerning cause-andeffect with regards to this DEIS.
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From page 32... ...
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.
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From page 33... ...
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)
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From page 34... ...
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)
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From page 35... ...
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.
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From page 36... ...
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)
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From page 37... ...
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
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From page 38... ...
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.
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From page 39... ...
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
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From page 40... ...
. The DEIS identifies socioeconomic impacts associated with commercial shellfish culture and recreation/tourism.
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From page 41... ...
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.
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From page 42... ...
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)
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