Washington State – Alaska – Non tank final rule & Washington State – Contingency Plan requirements. We refer to our circular no. B.613. As stated in that circular, every tank vessel and every other vessel over 300 GT is required under State law to file a contingency plan prior to entry into the waters of Washington State but that instead of filing his own plan an owner can subscribe to an umbrella oil spill contingency plan. Since publishing the abovementioned circular, Washington State Maritime Co-operative (WSMC) has changed its enrolment agreement and the version with footer “WSMC Enrolment Agreement – December 2013” conforms with the International Group’s guidelines on vessel response plans.