18 



range of potential cause-effect 

 relationships that may exist 

 between project activities and 

 physical-chemical environmental 

 alterations as well as probable 

 biological responses to those 

 alterations. 



(b) Relationships among physical, 

 chemical and biological elements 

 are naturally complex and vary in 

 the degree to which they are 

 understood. Uncertainty and 

 complexity are increased by 

 apparent conflicts between agencies 

 and institutions which are 

 politically as well as technically 

 motivated. We attempted to 

 achieve an objective and scientific 

 approach as the common ground 

 for discussions about the 

 monitoring program. 



(c) Direct short-term physical-chemical 

 and biological impacts affected by 

 dredging and disposal are not the 

 principal concerns of the 

 monitoring program, because 

 scientific experience can argue 

 effectively that these impacts are 

 either not a cause for concern, or 

 they are manageable. An example 

 of the former is the direct effects of 

 dredging and disposal-induced 

 suspended sediment concentrations 

 on estuarine fishes; an example of 

 the latter is the concentration of 

 suspended sediments in the 

 effluent from a dredged material 

 containment facility. The principal 

 concerns of the monitoring 

 program are: (1) indirect 

 physical-chemical environmental 

 alterations, i.e., habitat alterations 

 that may be influenced by dredged 



material disposal operations and (2) 

 the probable biological responses to 

 these alterations. 



(d) Not all elements identified as 

 candidates for incorporation 

 into the monitoring program 

 were selected. The selection 

 process considered the following 

 factors for including or 

 excluding a potential 

 monitoring element: 



(i) The strength of the 



relationship between a 

 candidate element and a 

 project-induced environmental 

 alteration . Studies 

 recommending the monitoring 

 of non-specific indicators of 

 environmental stress would 

 produce information that 

 would be very difficult to 

 interpret unless techniques 

 existed that could be used to 

 separate project-induced 

 stresses from other causes of 

 biological stress acting on the 

 project area. Responses that 

 would be related uniquely to 

 the disposal activity were 

 preferred. 



(ii) A relationship between 



information produced by a 

 monitoring element and 

 criteria that would be defined 

 and used to determine the 

 significance of an observed 

 change . All monitoring 

 elements can produce data, 

 and a subset of elements will 

 produce data that can be used 

 to document the occurrence of 

 a "change". The question is, 



An Integrated, Tiered Approach to Monitoring and Management of Dredged Material Disposal Sites 



