The Washington Department of Ecology has approved 13 oil spill readiness plans for refining, oil handling and vessel shipping companies operating in Western Washington.

Under state law, all refineries, oil tankers and tank vessels, large cargo and commercial fish-processing vessels, passenger ships, oil storage facilities and oil pipeline companies must have spill contingency plans to operate in Washington.

In coming months, the department anticipates approving final spill readiness plans for 18 additional regulated facilities, vessel shipping companies and vessel umbrella organisations operating in the state.

Spill preparedness manager Linda Pilkey-Jarvis said every company tailors their spill contingency plans for individual operations but they must demonstrate they can do this in fast response to oil spills – including potential worst-case incidents ranging from 10,000 to 36 million gallons of oil.