It is unlikely that settlement of fine material from drilling would 

 alter the physical characteristics of the canyon sediment enough to 

 preclude settlement by larvae of benthic organisms.* This 

 conclusion was based on a worst-case order-of-magnitude calculation 

 similar to that for the metals. 



Given a 500-m setback, it is unlikely that drilling muds and cuttings 

 would produce any measurable effects on the commercial species in the 

 heads of canyons. 



Given the low volume and high dilution, deck drainage and sewage 

 discharges are minor contaminants, and therefore are expected to have 

 no measurable input--compared to other discharges. 



Produced water must meet the current Environmental Protection Agency 

 discharge standard, presently no more than 48 mg/L (ppm) of oil and 

 grease. 



Information on the concentrations of hydrocarbons and metals in 

 produced waters suggest no effects are expected in the water column. 

 Benthic effects are not expected but gradual accumulation of 

 hydrocarbons on the bottom has been shown in shallow water. If 

 production were to occur without further study of this benthic 

 hydrocarbon accumulation, discharge of produced water should be 

 monitored. It is more likely that hydrocarbon buildup would be 

 related to spills and blowouts. 



During oil spills and blowouts, there is a possibility of higher 

 accumulations of hydrocarbon in canyons than on the adjacent slope 

 (for example, in krill, or due to sedimentation and resuspension 

 processes).* However, the major short-term impacts would occur in the 

 surface layer and at the shelf water/slope water front. Benthic 



"See also reviewer comments in Appendix A. 



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