33 C.F.R. § 25.803

A claim for damage to or loss of real or personal property is payable under this subpart if:

(a) Caused by the United States, its employees, agents or contractors during containment, countermeasures, cleanup, mitigation, and disposal activities under the National Contingency Plan; and

(b) In the exercise of care reasonable under the circumstances, the incident giving rise to the claim was necessary and the damage unavoidable.