ST. LOUIS (AP) — Water levels on the drought-plagued Mississippi River are expected to keep dropping over the next several weeks, according to a new forecast Wednesday that comes amid worries that barge traffic soon could be squeezed along a key stretch of the vital shipping corridor.

The latest outlook by National Weather Service hydrologists shows the river at St. Louis falling to about 9 feet deep by Dec. 30 — a day later than earlier predicted — and by a half foot more by Jan. 9, barring significant rainfall. The Coast Guard has said further restrictions on barge traffic are likely if the river's depth dips to 9 feet.

The river depth in St. Louis as of Wednesday was about 12 feet.