Plans to open a Mississippi River spillway in Louisiana have been put off a second time because the river continues to rise more slowly than expected.

Army Corps of Engineers spokesman Matt Roe said Monday that plans now call for the Morganza Spillway’s opening to begin Sunday, a week after the original announced date. It already had been put off once, to Thursday.

National Weather Service hydrologist David Welch says the Mississippi River’s crest is now expected to be about 6 inches (15 centimeters) lower than previously forecast.

The corps has said it wants to open the Morganza Spillway only when it becomes necessary.

Any opening this year would be the third time ever and the second time to control floodwaters.