For the Mid Atlantic, production levels are estimated as 90,000 to 740,000 

 barrels of oil per day peak production, Thus, a scenario of 740,000 barrels 

 per day would represent the maximum level of impact on water quality, 

 Changes in local water quality may be caused by: 



a. Discharge of formation waters and drill cuttings; 



b. Discharge of drilling muds; 



c. Resuspension of bottom sediments; 



d. Oil spills, blowouts and pipeline ruptures. 



The most severe degradation of the existing offshore water quality can 

 be attributed to oil spills and discharges of formation waters and drilling 

 muds. Deposition of drill cuttings, consisting of substrate components such 

 as sand, ground rock, and mud, should not pose any long-term water quality 

 changes. It is assumed that turbidities caused by such disposal, and by pipe- 

 line burials will be short-lived and will settle out within several hundred 

 feet of the site of activity. Pollutants which could be reintroduced into 

 the water column, such as heavy metals, are generally associated with partic- 

 ulate matter and settle out as turbidity is reduced. The bio-accumulation and 

 effect of low concentrations of metals in the marine ecosystem are poorly 

 documented. 



The effects of oil spills or blowouts on water quality would be to 

 increase the level of petroleum hydrocarbons and trace metals in surface and 

 near surface waters. Deeper waters would be contaminated by oil carried 

 down with suspended solids and incorporated into the sediments. The effects 

 of oil and hydrocarbons in the water column on plankton, fish and marine 

 mammals have been delineated earlier. 



56 



