CLARKSVILLE, Mo. (AP) — Makeshift levees mostly held back the water in communities along the Mississippi River and other Midwestern waterways, but meteorologists warn that looming storms could cause problems.

An inch of rain is expected to fall on a wide swath from Oklahoma to Michigan through Tuesday. The National Weather Service says that could raise crest forecasts on some rivers, especially the Illinois River, and slow the retreat of others.

The hastily built barrier in Clarksville, Mo., showed signs of strain Monday, and volunteers in the town 70 miles north of St. Louis scrambled to build a second wall to catch the water that found its way past the first.

Additional rain could be troublesome in Michigan, too, where the Grand River drove hundreds from their homes in Grand Rapids and flooded downtown.