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SUMMARY 



The "Assessment of Potential Impact of the MWRA Outfall on Endangered Species: 

 biological assessment prepared pursuant to Section 7 of the Endangered Species Act" (hereafter the 

 Assessment) has been reviewed to determine its adequacy according to the scope discussed in the 

 summary document. In brief, the Assessment is a reasonably complete description of the 

 oceanography and endangered species habitats of Massachusetts and Cape Cod bays. Some 

 exceptions of this completeness are indicated in the details provided below. 



Unfonunately, the Assessment does not address some critical issues identified in the 

 October, 1992, SAP review of the Work Plan by A JD. Little, to the detriment of the final product 

 Examples include the low-level chronic input of nutrients to Massachusetts Bay, and its effects 

 over periods of decades; effects of surface waves on mixing and dispersion processes; and 

 geoaccumulation. In addition, the repon uses a "weight of evidence" metric to conclude lack of 

 impact on the endangered species, which methodology is neither quantitative nor rigorous." ' Lack . 

 of data impairs the ability to derive an unambiguous and thorough evaluation of the effects of the 

 proposed outfall siting. In addition, the reliance on comparison of the effects of the present outfall 

 pipe with the proposed siting is unjustified: the Endangered Species Act appears not to require 

 solely an improvement over existing conditions, but rather no jeopardy, period. 



In my opinion, the Assessment cannot "insure" that the outfall pipe "is not likely to 

 jeopardize the continued existence of any endangered species or threatened species or result in the 

 destruction or adverse modification of habitat of such species which is determined by the 

 Secretary, after consultation as appropriate with affected Slates, to be critical." 



PHYSICAL MODEL RENTEW 



One of the disappointing aspects of the Assessment is the lack of data from the physical 

 models (circulation and water quality). In the Work Plan by A.D. Little, considerable emphasis 

 was placed on the model results. Now, the Assessment says its results are "valid and are not 

 conditional upon fumre modeling efforts." This finding requires some further justification, given 

 tiie original focus on modeling efforts. That the model results are not available is not the fault of 

 the Assessment; however, the heavy reliance in the Work Plan seems to require some more 

 discussion of the need or lack of need of such models for decision-making. 



Use of the initial dilution model is also of some concern, since it is based on work by 

 Roberts and co-workers and relies heavily on empirical laboratory studies rather than a solid 

 understanding of basic principles of initial dilution. The extrapolation of Roberts' results are also 

 uncertain: his estimate of initial dilution occuring within 1.75 water depths somehow translates to 

 a zone of influence of 0.26 km^; I cannot reconcile these two estimates. The Assessment assumes 

 that no adverse effects will occur in the initial mixing zone, because it is too small. The rationale 

 for this assumption is not made clear. 



The use of various spatial scales discussed in the repon is initially clarified by definition of 

 four different scales in the Assessment The remainder of the repon essentially ignores this scale 



