 In 1929 , the Missouri River Navigation Commission estimated the total amount of goods shipped on the river annually at 15 million tons ( 13 @.@ 6 million metric tons ) , providing widespread consensus for the creation of a navigation channel . However , shipping traffic has since been far lower than expected – shipments of commodities including produce , manufactured items , lumber , and oil averaged only <unk> @,@ 000 tons ( <unk> @,@ 000 t ) per year from 1994 to 2006 . 
