2/16/2012 SEWER COMMISSION Minutes

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Massachusetts Estuaty Project(MEP) Linked Watershed EnrbaymentModel Peer Review —__ ��_ transplanting(Fonseca et al. 2011). The global success rate of seagrass transplanting is only about 50% and attempts to transplant and restore seagrass at the scale of Massachusetts embayments have not been any more successful than the average.rate(Fonseca et al. 1998,Moore and Short, 2006,Paling et al.2009, Orth et al. 2010,Fonseca et al. 2011,Chesapeake Bay Scientific Technical Advisory Connnittee,2011). Recent transplant failures in Massachusetts embayments corroborate these uncertainties and indicate how difficult it is to determine if a small site or embayment is suitable for transplanting and restoration (Leschen et al. 2010,Nature Conservancy,2011). Short et al. (2002)propose using an eelgrass transplanting suitability index that incorporates at least 7 variables(see Table 1 of Short et al. 2002). Dissolved inorganic nitrogen and total nitrogen, as well as historical eelgrass distribution, are included on the list,but it is clear that several other variables must be assessed to complete a comprehensive evaluation of an embayment's suitability for eelgrass restoration and the extent of coverage that would be expected following nitrogen remediation. The Panel recommends that uncertainty in restoration goals can be reduced by avoiding use of unreliable records of historical eelgrass coverage(e.g. 1950)and adopting an adaptive management approach that sets restoration targets and adjusts predictions of future extents based on more recent eelgrass coverage data(post 1995)from the MDEP eelgrass mapping program(Costello and Kenworthy,2011). More realistic and accurate restoration targets can be set by incorporating analyses of the MDEP mapping data with more comprehensive assessments and monitoring of the correspondence between areal coverage and environmental conditions that affect eelgrass distribution and abundance in unimpaired and impaired embayments. As per Short et al. (2002),an embayment restoration suitability index should be developed that incorporates a wider set of predictor variables than just the nitrogen concentrations at the sentinel stations. 5.4. TMDL Issues Key Issue 1-Appropriate Translation of Science into Management in TN DLs Over the last 20 years,TMDL analyses have been the primary mechanism for setting water quality-based management targets for impaired waterbodies that require management beyond levels that technology- based controls have provided. Under Section 303(d) of the Clean Water Act(CWA), the TMDL process requires states or EPA to: set water quality targets,usually based on state water quality standards; determine the degree to which the standard is violated; identify sources of the pollutant by point and nonpoint source category; establish allocations of the pollutant between point and nonpoint sources, including a margin of safety,with consideration given to seasonal variation; and develop an implementation plan and schedule for attaining the TMDL,including"reasonable assurances"that the unregulated nonpoint source target will be attained. In sum,the TMDL itself is defined as a pollutant loading capacity that will meet water quality standards and is the sum of natural background loading+the wasteload allocation assigned to regulated point sources+the load allocation assigned to unregulated nonpoint sources+a margin of safety to account for uncertainty. The Panel was charged to review the MEP modeling approach to determine its scientific defensibility and functional adequacy for"...the development and implementation of appropriate nitrogen TMDLs for the estuaries and embayments of Cape Cod..." An approach deemed"scientifically defensible"and "functionally adequate"for TMDL development would appropriately meet the requirements for a TMDL and meet with EPA's approval. Other concerns in the Panel's charge relate to the utility of the MEP's models and analyses for comprehensive wastewater nutrient management planning,which would follow if EPA CWA requirements for approval of TMDLs are met. Comprehensive Wastewater Management Plans (CWMP), developed in response to nutrient management requirements, are supported by the same scientific understanding that is required to develop the TMDL(e.g.,Stearns&Wheler,LLC,2009). Simply stated,if the science supports a viable TMDL,there is strong likelihood that the management outcomes will be equally supportable by the science. December 30,2011