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areas. The first step for any program is to develop federal numeric and 

 other criteria that to gether will act as a trigger for restoration and 

 preventative actions. 



II. What are sediment quality criteria? 



The purpose of sediment quality criteria should be to establish levels 

 of contamination in sediment that, when exceeded, would serve as a critical 

 component in triggering remedial and preventative actions. The levels of 

 contamination established by the criteria must protect the most sensitive 

 species in the environment, as well as other ecosystem characteristics such 

 as community structure and function, and must include a margin of safety 

 which accounts for the gaps in scientific understanding and uncertainty. 

 For example, exposure routes such as sediment ingestion and direct dermal 

 contact with sediments by bottom-dwelling organisms, differences between 

 acute and chronic or reproductive effects, synergistic effects, dynamic 

 changes in bioavailability, and exposures through the food chain must be 

 taken into account by criteria. 



Some people have expressed concern that it is scientifically 

 impossible to develop one simple number (such as "1 ug/kg for cadmium"), 

 that defines what is safe or "clean" in all locations or circumstances. This 

 concern is based on an incomplete understanding of the criteria. 



Sediment quality criteria need not consist of one simple number 

 applicable in all waters. It is likely that criteria will vary depending on a 

 number of factors that might affect toxicity or exposure such as salinity, 

 sediment grain size, sediment carbon content, or content of acid volatile 

 sulfide (AVS). A sediment quality criterion could consist of a matrix that 

 includes these or other relevant factors, and that enables the decision 

 maker to calculate a concentration appropriate for a given site. Figure 1 

 provides an hypothetical matrix where a property of the sediment such 

 organic carbon content is compared to a property of the ambient water 

 such as pH to find the appropriate numerical criterion for a particular 

 pollutant. Many existing water quality criteria are written this way. 



Sediment quality criteria need not be only a "number". Sediment 

 quality criteria and standards may consist of an array of tests. The EPA 

 may not be able to derive numbers that define the safe concentration of a 

 chemical in sediments with a high degree of confidence for more than a 

 small subset of chemicals. Therefore, tests should be adopted that directly 

 measure the toxicity of sediments to compensate for the chemicals for 

 which criteria with a high degree of certainty have not yet been developed, 



