Authorities say a routine traffic stop Friday on Interstate 80 near Coalville netted 31.5 pounds of methamphetamine with a street value of more than $1 million.
Summit County sheriff's deputies say a police dog brought their attention to the car's trunk and a subsequent search of it turned up the meth concealed under the spare tire.
They say a Long Beach, California woman was referred to federal authorities for possible federal prosecution.
Sheriff's Sgt. Rob Bridge told The Salt Lake Tribune the male driver was released after the woman claimed the meth was hers and that the driver had no idea it was in the trunk.
Bridge says the eastbound driver was stopped for a 'lane travel violation.'