Five people were arrested on marijuana trafficking charges in this town about 90 miles north of Seattle, the US Attorney for the Western District of Washington, John McKay, said.
The tunnel runs from a prefabricated hut on the Canadian side and ends under the living room of a home on the US side, 300ft from the border. Built with lumber, concrete and metal reinforcing bars, the passageway had lights and ventilation, and ran underneath a highway. "They were smart enough to build a sophisticated tunnel. They weren't smart enough to not get caught," Mr McKay said.
He said authorities had been monitoring construction of the tunnel for six months and sealed it after it opened on Wednesday.
Although smuggling tunnels have been found on the United States-Mexican border, this was the first discovered along the border with Canada, Mr McKay said. Canadian authorities learnt of the tunnel in February and alerted US officials.
Francis Devandra Raj, 30; Timothy Woo, 34, and Johnathan Valenzuela, 27, of Surrey, British Columbia, were arrested on Wednesday. They were charged with conspiracy to import and distribute marijuana. Mr Raj owns the property under the hut, authorities said.
Last week, two people were arrested here for transporting marijuana that had come through the tunnel, agents said. One was a woman smuggling 93lb of marijuana and the other was a man pulled over with 110lb of the drug.