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of potential impact on an endangered or threatened species as a sequence of linkages between 

 components of the regional ecosystem, then to attempt to evaluate the likelihood of each linkage. 

 This seems to be a logical way to proceed, with the caveat that linkages in ecology are often 

 much more complex than they at first appear to be. 



Within each of the two primar)' impact sources discussed, the potential impact linkages are 

 stated as null hypotheses, with the expectation that each would be scientifically tesuble. The plan 

 indicates that the likelihood of rejection of each hypothesis will be estimated by a qualitative 

 ranking scheme, based on whether the level of change due to the outfall in the parameter under 

 analysis exceeds threshold levels determined from the literature. This seems less than 

 rigorous, but part of the difficulty may again he in lack of a clear delineation between the ESTM 

 and the subsequent BIA which will rely on the ESTM. It would seem to me acceptable to use 

 qualitative methods for initial assessment in an ESTM, but I would expect quantitative, 

 statistically valid testing of clearly-stated, narrowly-defined hypotheses in a more formal BIA. 



The set of hypotheses relative to potential impacts of primary nutrients (section 2.3.1) are well- 

 structured in a hierarchical scheme arranged according to increasing number of linkages from the 

 outfall itself This arrangement makes it so that failure to reject a null hxTJOthesis early in the list 

 probably eliminates the requirement to test later hj'potheses dependent on it. The set of 

 hypotheses seems to me relatively complete, with some exceptions (and the work plan does 

 specify "will include but not be limited to"). The lack of consideration of endangered species 

 other than right, humpback, and fin whales was mentioned above. Another missing ecosystem 

 component is the benthos. Benthic organisms are not part of the food web leading to 

 planktivorous or piscivorous whales, but they could be involved in nutrient cycling affecting 

 those food webs indirectly. Some of the other endangered species (e.g. sturgeons and some 

 turtles), on the other hand, are benthic feeders. Furthermore, the sand lance, a critical link in 

 pelagic food webs in the Bays and imponant whale prey, hibernates, rests, and escapes from 

 predators by burrowing into clean, sandy, well-oxygenated bottoms. Changes in bottom 

 characteristics could potentially eliminate sand lance habitat. Another concern has to do with the 

 stated limitation to 'outside the mixing zone', particularly as pertains to toxic phytoplankton 

 (hypothesis 3). This is outside my area of expertise, but what is the potential of a current 

 bringing water containing cysts of some toxic species into the mixing zone and initiating a bloom 

 that would then spread beyond? 



The h>'potheses related to potential impacts of toxic chemicals (section 2.3.2) are similarly 

 arranged in a hierarchical fashion, and again seem relatively complete. In fact, the endangered 

 turtles and fish are actually mentioned here. There does seem to be a lack of any concern for 

 potential direct impacts of toxics on any of the organisms in the food chains leading to the 

 endangered species - this may be entirely warranted, but I don't know. There is again a lack of 

 inclusion of the benthos - perhaps even more important in consideration of toxic impacts. Again, 

 some endangered species feed directly on benthic organisms, and benthic processes may 

 potentially affect others indirectly. Another question is whether sand lance can accumulate toxics 

 from contact while buried in the sediment An additional route of exposure to toxics may exist for 

 humpback whales. There is evidence that humpbacks collide with the bottom during feeding - 

 whether the contact is simply incidental or actually purposeful in order to drive buried sand lance 

 from the sediment into the water column is not known. What is the potential for resuspension of 

 accumulated toxics in the sediment and subsequent ingestion by the whale? 



Section 2.3.3 discusses the potential cumulative impacts of the outfall combined with three other 

 activities - the Third Harbor Tunnel Project, Boston Harbor Improvement Project dredging, and 

 use of the Massachusetts Bay Disposal Site. At earlier meetings. Panel members discussed other 

 potential actions which may occur, notably watershed processes. However the stipulation of 

 "reasonably cenain to occur" may preclude inclusion of possible future changes or continuation of 

 current processes in the assessment. The approach in this section seems to be to include all of 



