By Karl Plume

CHICAGO, Dec 16 (Reuters) - The Mississippi River reopenedto commercial barge traffic near St. Louis on Monday following a36-hour closure for emergency dredging after several barges hitground in the major shipping channel plagued by low water inrecent weeks, industry sources said.

The river at St. Louis was expected to remain near itscurrent level for the next week but then recede by nearly twomore feet, according to the latest National Weather Serviceforecast, so shipping through the busy port may remaindifficult.

The U.S. Coast Guard reported at least four groundings overthe weekend, including one in which barges briefly broke loosefrom a tow. A section of the river south of the Port of St.Louis was found to be too shallow so the Coast Guard closed thearea to navigation while the Army Corps of Engineers dredged thechannel to deepen it.

“Three of the incidents were bump-and-go but there was onetow which lost several barges. They were able to regain themwith no damage done, but these are all just side effects of thelow water,” said Coast Guard spokesman Colin Fogarty.

Grain shippers, who rely on the Mississippi River and itstributaries to move grain from Midwest farms to exportfacilities near the Gulf Coast, have been loading as much as 25percent less grain on barges for weeks to avoid groundings.

Some 60 percent of all U.S. corn, soybeans and wheat exitthe country via Gulf Coast terminals.

“We’re down to nine-foot drafts through St. Louis. Whenthings are good we can load 12-foot drafts going through St.Louis but we’re down to nine-foot drafts now. That’s 600 tonsless grain per barge,” said a barge broker.

Spot barge freight costs at St. Louis eased slightly onMonday as milder weather was expected to limit ice buildup thisweek, preventing a further drop in river levels. Also, some rainwas forecast for the area later this week.

Still, rates at St. Louis were seasonally higher than normaland well above rates further south where low water was not aconcern.

Spot freight costs on the Mississippi River at St. Louiswere 475 percent of tariff on Monday, down from trades as highas 500 percent on Friday. Spot rates in the Memphis-to-Cairostretch of the river just south of St. Louis were just 275percent of tariff.

Freight costs are quoted as a percent of benchmark rates setin 1976. The benchmark rates are higher at points further fromthe Gulf but the daily costs are adjusted based on logisticaland other factors.

The St. Louis river gauge reading was at a minus-2.27 feeton Monday afternoon. It was forecast to remain around minus-2.1feet for the next week then recede to a minus-4.1 feet a weeklater, according to the National Weather Service.

(Reporting by Karl Plume; Editing by Tim Dobbyn)