"At some point, you run out of water. At what point do you stop sailing?" said Mark Barker, the president of the Interlake Steamship Co. based in Cleveland.
"We have to keep going because our customers rely on us," Barker said.
On the other hand, company ships, some 1,000 feet long, are required to have hulls that extend as far as 29 feet underwater. In the trade, that would be called a 29-foot draft. But this year, fearing ships could run aground, ships are sailing with light loads to maintain a maximum draft of 25 feet, The (Cleveland) Plain Dealer reported Wednesday.
To shorten the draft, ships are required to reduce weight by 250 tons to ride an inch higher.
"If you do the math, that's 6,000 tons per trip. That's 300,000 tons over the course of a season. That's 20 percent of my cargo carrying capacity," Barker said.
Due to low water levels, "our largest ships are losing 10,000 tons of cargo each trip. This is very, very much a crisis," said Glen Nekvasil, vice president of the Lake Carrier's Association, which represents a fleet of 57 Great Lakes cargo ships.
Low water levels are the result of two factors: less water and less dredging. Water levels have dropped two feet through January 2013 from 12 months earlier in some of the Great Lakes.
Declining levels even set a record -- a 12 month stretch in which water levels dropped every month.
"That has never happened going back to 1918," when the government began keeping records, said Keith Kompoltowicz, the chief of hydrology at the Army Corps of Engineers office in Detroit.
Shippers complain dredging water channels is slow, but dredging is underfunded even in the best of times, said dredging program manager Mike Asquith with the Army Corps of Engineers in Buffalo, N.Y.
"We typically don't have enough money to dredge all the harbors we'd like," he told the newspaper.
Notable deaths of 2014 [PHOTOS]