No Action Alternative – Special Use Permit under which DBOC operates expires on November 30, 2012 and is not renewed:

Alternative A: mariculture activities cease and equipment is removed; Drakes Estero potential wilderness is converted to full wilderness.

Action Alternatives – Special Use Permit for shellfish culture is reissued for an additional 10 years under the conditions specified in three alternatives:

Alternative B: Level of use consistent with conditions and operations present in fall 2010; Shellfish production limited to 600,000 lbs/yr.

Alternative C: Level of use consistent with conditions and operations at the time the current Special Use Permit was signed in April, 2008; Shellfish production limited to 500,000 lbs/yr.

Alternative D: Considers an expansion of operations and new or modified onshore facilities as requested by DBOC as part of the EIS process; Shellfish production limited to 850,000 lbs/yr;

Major Conclusions

For the eight resource categories, the committee evaluated conclusions in the DEIS concerning levels of impact of each alternative and the information and interpretations that led to them. The committee also commented on whether alternate, scientifically sound conclusions could be reached based on the available information (in the DEIS and the scientific literature) and the level of uncertainty associated with the conclusions. As noted in the previous NRC report on Drakes Estero (NRC, 2009), there is not an extensive scientific literature on Drakes Estero and research on the potential impacts of shellfish mariculture on the Drakes Estero ecosystem is even sparser. Therefore, the NPS had little primary data on which to base the DEIS and had to rely to a large extent on inference from research conducted in other areas. Although this was the only approach that could be used under the circumstances, it not only made it difficult to differentiate impacts of alternatives B, C, and D, it resulted in a moderate to high level of uncertainty associated with conclusions concerning levels of impact for most of the resource categories reviewed by the committee (Table S.1).

Impacts of the Alternatives

Alternative A can be readily distinguished from alternatives B, C, and D because mariculture activities would cease and all DBOC infrastructure would be removed. However, alternatives B, C, and D are differentiated primarily in terms of production limits for offshore activities (600,000 lbs, 500,000 lbs and 850,000 lbs for B, C, and D, respectively), which do not provide a clear basis for comparison. An overview of the DEIS impact findings shows that the expected impact intensities are the same for each action alternative regardless of resource category (Table S.1). Production limits dictate the maximum level of harvest, but do not directly scale with level of activities or spatial extent of mariculture operations. Additionally, harvest may vary as a function of environmental conditions, shellfish diseases, harmful algal blooms, predation, and market conditions, and therefore does not represent a reliable indicator of potential impact.

Adverse impacts are defined in the DEIS as minor, moderate or major in order to describe impacts based on their intensity or magnitude. It is noteworthy that only one category of beneficial impact is used, eliminating the possibility of distinguishing between effects that may range from minor to major beneficial in parallel with the definitions used for adverse impacts. Also, the definitions do not include a negligible impact, a useful category that is provided as an example in the NPS NEPA guidance, “Summary of Regulations and Policies — Impact Indicators and Criteria,” Director’s Order 12.3 For most of the eight resource categories that the committee was asked to review, the committee concluded that the DEIS does not define impact intensity levels that can be clearly related to the magnitude of the effect (spatial or temporal; direct or indirect). This makes it difficult to determine both the comparative impact of


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