Table 1
How Much Water was in the Lightered Cargo?
(in million gallons)

(*b) Spill volume calculations:
Exxon: 53.04 - 42.20 = 10.8 million gallons
(Exxon alleged the lightered cargo was 100 percent oil.)
State of Alaska files: 10.8 + 19.2 = 30 million gallons

Sources: Alaska Department of Law 1991; Caleb Brett 1989.

*a Lightered cargo = oil/water emulsion off-loaded from T/V Exxon Valdez. Estimates of water in the lightered cargo (AK Department of Law 1991, ACE 10864138-10864143) are as follows:

• Exxon Baton Rouge retained onboard approximately 9.2 million gallons of an oil-water mixture with an estimated water/oil content of 60/40. That means about 5.5 million gallons of "oil" supp osedly lightered from the Exxon Valdez was water (9.2 x 0.6).
  
• Exxon San Francisco retained onboard approximately 5.6 million gallons of an oil-water mixture with an estimated water/oil content of 65/35. That means about 3.6 million gallons of "oil" supposedly lightered from the Exxon Valdez was water (5.6 x 0.65).
  
• Exxon Baytown retained most of her cargo onboard. She lightered approximately 6.6 million gallons of an water-oil mixture with an estimated water/oil content of 70/30 to the Exxon Baton Rouge, which returned to the tanker terminal in Port Valdez. She lightered approximately 7.9 million gallons of an oil-water mixture with an estimated water oil content of 70/30 to the Exxon San Francisco, which returned to the tanker terminal in Port Valdez. That means about 10.1 million gallons of "oil" supposedly lightered from the Exxon Valdez was water [(6.6 x 0.7) + (7.9 x 0.7)].
  

*b Volume spilled: State of Alaska papers show that investigators used an error margin of + 20 percent to account for unknowns such as the percentage of water in the cargo offloaded at the refineries and the amount of water in the cargo lightered by the five barges. Thus, the range of volume spilled, according to the records on file with the State's investigation, is between 24 to 36 million gallons. State investigators stress that the low number is "a minimum amount; apparently much more was lost before the oil was completely offloaded" (Murchison 1991a, ACE 9486068).