Wash. Rev. Code § 38.52.350
Should the United States or any agent thereof, in accordance with any federal statute or rule or regulation, furnish monetary assistance, benefits, or other temporary or permanent relief to emergency workers or to their dependents for injuries arising out of and occurring in the course of their activities as emergency workers, then the amount of compensation which any emergency worker or his or her dependents are otherwise entitled to receive from the state of Washington as provided herein, shall be reduced by the amount of monetary assistance, benefits, or other temporary or permanent relief the emergency worker or his or her dependents have received and will receive from the United States or any agent thereof as a result of his or her injury.
RCW 38.52.350