Winter storms helped ease drought conditions in Plains states and the Southeast this week, but dry conditions expanded in parts of New Mexico and Texas.

The U.S. Drought Monitor map released this morning showed an incremental improvement of U.S. drought conditions, now affecting 51.4 percent of the country. Areas in severe drought or worse also shrank slightly. But areas in the worst drought -- categorized as "exceptional" -- increased by a fraction to 5.6 percent of the country.

The barge industry remains in an uproar over low water levels on the Mississippi River. Without rain or a fresh release from reservoirs, industry says, the federal government may halt most traffic on a key stretch of the river by mid-January, putting billions of dollars of trade at risk.

"The uncertainty of this deteriorating situation for the nation's shippers is having as much of an impact as the lack of water itself," said Michael Toohey, president and CEO of Waterways Council Inc., in a statement yesterday.

The Army Corps of Engineers doesn't see the situation as quite so dire, though. Its St. Louis District said yesterday that the latest weather forecast suggests rain could come and that even without precipitation, river levels won't dip below the level allowing traffic until mid-January. Rock formations that pose the greatest threat to barges are scheduled to have been fully removed by that time.

"We believe we will deepen the channel ahead of the worst-case river stage scenario, and I remain confident that navigation will continue," said the Mississippi Valley Division commander, Maj. Gen. John Peabody, in a statement.