More than 1,000 shipments of dry and liquid cargo moved freely on the low Mississippi River Wednesday and Thursday after a section south of Greenville reopened.

The Coast Guard opened a two-mile “safety zone” to allow 84 towboats to pass, a figure evenly divided between northbound and southbound vessels, spokesman Lt. Ryan Gomez said. Tows pushed 1,157 barges downriver through Vicksburg.

About 35 tows moved slowly past the river bridges at midday Wednesday, as feeder bands of Hurricane Isaac, centered more than 200 miles to the south, whipped up a sandstorm on exposed sandbars on the Louisiana riverbank throughout the day.

Restrictions remained in place on the two-mile stretch of the Lower Mississippi, still forecast to drop to near-record levels despite the hurricane’s path along the river’s southernmost reach. The level at Vicksburg was minus 0.83 feet this morning, down a tenth since Wednesday. The record low is minus 7 feet in 1940. The gauge at Greenville read 7.02 feet, down a tenth.

A persistent drought and above-average sediment left behind by the river’s historic flood in 2011 has contributed to the current levels along the Lower Mississippi, predicted to linger until October. Forecasts for stages in Vicksburg project a drop to minus 2.3 feet by late September. In Memphis, the river was at minus 9.6 feet this morning and expected to fall to minus 10.9 feet by the same time frame, which would be a new record low.

“The current extreme low water conditions and decreased river flow drastically affect normal sediment movement and make normal dredging extremely difficult,” a release from the U.S. Army Corps of Engineers’ Vicksburg District said.

A mix of federal and contract dredging continued on the river Wednesday, the release said.

The Dredge Jadwin, owned by the U.S. Army Corps of Engineers’ Vicksburg District, worked the Lakeport area south of Greenville on Wednesday, a release from the Corps said. The Dredge Iowa, owned by Great Lakes Dredge and Dock Company, was en route to Greenville Thursday, the Corps said. The Dredge Butcher, owned by Pine Bluff Sand and Gravel Company and under contract to the Corps, will dredge at Lake Providence until late September.

Two other contract vessels — the America and the Integrity — dredged in the Ouachita/Black and Red River basins.