Lowering the water level a foot per day was called an optimistic estimate on Friday, depending on how much of the pumping capacity can be restored and whether any more storms complicate the work.
Two tropical storms, Lee and Maria, are churning in the Atlantic. They pose no threat to land, but this is the peak of hurricane season and more storms could easily develop.
Lt. Gen. Carl Strock, commander of the Army Corps of Engineers (search), declined to make a firm estimate for completing the pumping, but said, "We're certainly talking weeks."
His predecessor, Robert B. Flowers, estimated at least a month. He told The Associated Press that optimistically, the pumps could lower the water as much as a foot a day, but it is likely to start more slowly.
There are six pumping stations in the city and the corps could bring in auxiliary pumps, Flowers said.
Draining New Orleans is not like pulling the plug on a bathtub drain; much of the city is below sea level so the water will have to be pumped up and out.
Contamination by oil, chemicals and sewage also complicates the effort, Flowers said.
Removing the water would be slowed if it has to be treated before it can be discharged, he said, though it might be possible to get some type of dispensation so it can be pumped quickly into the Mississippi River and Lake Pontchartrain.
Strock told reporters at the Pentagon that in addition to pumps the engineers are working on a plan to make new breaches in the levees — from hundreds of feet wide to 3,000 feet — in areas where gravity can help move water out of the city.
"The real focus now is saving lives and sustaining lives," he said.
Strock said the water level in the city has stabilized, and repairs to breaches in two levees are progressing. He also said workers are clearing, surveying and putting in navigational buoys and lights along the coastal channels in an effort to get the ports reopened.
Responding to criticism that the federal response has been slow and inadequate, Strock said the destruction of communications lines and transportation routes made it very difficult to determine exactly where help was needed and to get workers and supplies there.
"Our biggest problem is communications," he said, noting that cellular phone towers were all knocked out, making it nearly impossible for citizens in need to call for help. "We have to know where to drop (supplies) and what to drop."
He also said the corps is working on plans to create a city somewhere in the area to accommodate about 50,000 people — similar to what was done in the aftermath of Hurricane Andrew in Florida.