The Mississippi is so low there now that if it drops another 5 feet, barge traffic may shut down from St. Louis to the confluence of the Ohio River at Cairo, Ill., perhaps as soon as early December. Barges already are required to carry lighter loads.Major Gen. John Peabody, commander of the Mississippi Valley Division of the corps, said the reduced Missouri River flow will remove 2-3 feet of depth of the Mississippi at St. Louis. To help offset that, he has authorized an emergency release of water from an upper Mississippi River reservoir in Minnesota. But that will add just 3-6 inches of depth at St. Louis. Corps officials responsible for the Missouri River say they have no choice but to reduce the flow. A congressionally-authorized document known as the Missouri River Master Manual, completed about a decade ago, requires the corps to protect interests of the Missouri River. What happens on the Mississippi as a result is incidental. "We don't believe we have the authority to operate for the Mississippi River," said Jody Farhat, chief of the Water Management Division for the corps' Northwest Division. Farhat said the drought is taking a toll on the upper Missouri River basin. Recreation is being hurt because the water is so shallow, she said. Indian artifacts normally under water are being exposed, making them prone to looters. And if the drought persists into next year as expected, hydropower could be impacted. As a result, she said, water behind the reservoirs must be conserved rather than released. Missouri Gov. Jay Nixon, Illinois Gov. Pat Quinn and U.S. Sen. Roy Blunt of Missouri have all expressed concerns about the plan to cut the flow. An editorial Friday in the St. Louis Post-Dispatch urged Congress to come up with a management plan for the entire ecosystem, not just the Missouri River.