A couple caught smoking marijuana caused a 20-minute delay on the Edmonds-Kingston ferry route while they were being detained by police in late September. Now, Washington State Ferry officials are reminding passengers traveling to and from Canada that no matter how you cross the border, it's illegal to do so with marijuana.

Washington State Ferries operates a route between Anacortes and Sidney, B.C. Though marijuana is now legal on both sides of the border, it's illegal to transport the drug to the other country.

Spokesperson Ian Sterling says although ferry workers are not law enforcement, they are required to report it to the coast guard if they see marijuana on a vessel.

Marijuana became legal in Canada nationwide on Wednesday. Legalization there prompted warnings from U.S. Customs and Border Protection.

The age to purchase in B.C. is 19 and 21 in Washington. There is concern that 19 and 20 year olds will enter Canada to purchase cannabis and attempt to bring it back over the border.

In a statement, U.S. CBP said, "Although medical and recreational marijuana may be legal in some U.S. States and Canada, the sale, possession, production and distribution of marijuana or the facilitation of the aforementioned remain illegal under U.S. Federal Law."

A recent study found that legalization on both sides of the border could eventually lead to fewer people trying to cross the border with marijuana, thus allowing border officers to focus on more illicit substances.