WINONA  (AP) — This summer's drought is not affecting shipping on the Upper Mississippi River so far.

Farther south, the Mississippi is about 13 feet below normal in some places. Cargo barges have run aground and their operators have been forced to lighten their loads.

But officials say the Upper Mississippi isn't much lower than usual.

In Winona, the river is around 5.5 feet, but has been dropping from a high this spring of more than 9 feet.

National Weather Service hydrologist Mike Welvaert says the average height for the river this time of year is in the 4.7-to-5-foot range.

A U.S. Army Corps of Engineers spokesman says rainfall farther north has helped keep water levels higher, as has the lock and dam system that controls water flow.

Copyright 2012 The Associated Press.