The water from the Mississippi River was too dirty.
VOA: special.2010.03.28
Yet unless the remitters became embroiled in a serious crime, often involving drug money, Western lawmakers largely ignored them, focusing instead on trying to dam the river of dirty money that flowed through traditional banking channels--chiefly through the 1970 Bank Secrecy Act, and later its amendments, which required banks to file reports of suspicious activity and high-dollar transactions, and to maintain information about account holders' identities.
The boys made collages depicting their journeys through the desert: the snakes, the coyotes, the dirtyriver, the truck, and the train commonly referred to as "La Bestia" (The Beast) because of its many dangers.
Those glorious inundations moved massive quantities of sediment through the Grand Canyon, wiping the slate dirty, and making a muddy mess of silt and muck that would make modern river rafters cringe.