Pay or Contest the Washington traffic infraction (e.g. speeding ticket).
In B.C., and most other Canadian provinces, if you don't pay a ticket, ICBC (or other agency) normally just gets it out of you when you renew your driver's license. But in WA if you don't pay a speeding ticket or other traffic infraction, the DOL will ultimately suspend your driving privileges in WA. Because you are Canadian (and have a B.C. driver's license, or on from another province), WA can't suspend your license, but the WA DOL can suspend your PRIVILEGE to drive in WA. If you are pulled over by the state troopers or other police force for anything, and your WA privileges are suspended (even if you have a valid license in your pocket), you will likely be charged with DWSL 3, a misdemeanor. Resolve this potential issue by calling the WA court and paying the ticket (may have to call collections). Then the WA DOL will clear your driving privilege. Don't assume that because you live in Canada the ticket doesn't apply or can't be enforced when you travel to the US - it can.
If you are pulled over and charged with DWLS, consult an attorney who is licensed in Washington and familiar with these international legal issues
Sometimes Canadians are surprised to discover that they can be charged with a crime in the US for forgetting to pay a speeding ticket, but they can be. DWLS 3 is a crime in WA - a misdemeanor - punishable by up to 90 days in jail and/or a $1000 fine. If you are traveling to the US and are charged with DWLS 3, or another offense, consult an attorney licensed in Washington who understands the legal landscape in both countries, and has experience with the unique jurisdictional issues and possible immigration consequences involved.