101 



SCIENTIFIC REVIEW OF THE 



NOAA NMFS BIOLOGICAL OPINION REGARDING THE EFFECTS OF THE 



MWRA OUTFALL ON ENDANGERED SPECIES 



Dr. Cabell S. Davit, 

 Anociate Scientiit, WHOI. 



September 21, 1993. 



Summary 



The NMFS Biological Opinion provides an Informed review of the potential impact of the 

 MWRA outfall on endangered species, and recommcndarions based on this review are reasonable 

 and prudent I endorse the NMFS conclusion of no-jeopardy, since, based on available evidence, 

 relocation of the outfall a relatively short distance to the east is not likely to cause detectable 

 changes in the habitats of the endangered species. The right whale is the only endangered species 

 that could be impacted (i.e., has a significant proportion of its total population In the Bays region), 

 but this species has not been observed in the location of the proposed outfall. If the predicted 

 dilutions of effluent are correct, nutrient increases in habitat areas will be indistinguishable from 

 background. In addition, there is no scientific evidence that relocating the outfall will affect the 

 occurrence of red rides. I agree with both NMFS and EPA that secondary treatment is essential for 

 the long-term health of the bays environment. The effects of short-term, 4- year, discharge of 

 primary-treated sewage and associated toxins on the Bays environment are not known, but appear 

 not to be very different from the current situation. 



I also endorse NMFS' Conservation Recommendations as being essential for protection of the 

 endangered species and their environments. As stated in the Opinion, these Recommendations are 

 actually requirements for issuance of the NPDES permit and address critical scientific issues not 

 included in EPA's Biological Assessment. These issues must be addressed prior to permit 

 issuance since they may alter current predictions of plume transport and deposition thus requiring 

 reinitiation of consultation with NMFS. As stated in the Opinion, further scientific studies required 

 include modeling the effects of wind forcing, Gulf of Maine inflow patterns, sub-grid scale 

 mixing, and water column stratification on initial dilution and plume development and rranspon. 

 Enhanced monitoring of farfield habitats is also recommended to detect potential habitat alterations 

 due to shon and long-term loading. In addition, I recommend that long term biological-physical 

 moorings be established in both nearfield and farfield (habitat) areas and that the monitoring 

 program also include analysis of satellite infra-red and ocean color. Plume tracking using acoustics 

 is also a good idea but should include optical instrumentation as well. I agree with NMFS that a 

 thorough comparative review of other ocean outfalls should be done, but I believe this should be 

 done as a prerequisite to issuance of the permit. Such a study would likely provide significant 

 insights into the potential impacts of nutrients and toxins in the proposed outfall on the benthic and 

 pelagic environments of the Bays. 



The NMFS recommendation for establishment of an implcmentable contingency plan prior to 

 issuance of the permit is also prudent. The plan should include a time-table for implementation. If 

 the effluent transpon and dilution docs not occur as predicted and chronic or acute conditions arise 

 in the endangered species habitats, swift action may be necessary to remedy the situation, including 

 a changeover to tertiary treatment. A several-year conversion period may not be adequate if high 

 rates of habitat alteration occur. 



