…that Kathryn linked to has a little encouraging news at the end:
One bit of good news is that New Orleans doesn’t appear to face a threat of being surrounded by even more water than it has outside its levees right now. By yesterday, the water level in the Mississippi had dropped about 11 feet since Monday, as the storm surge that had pushed upriver from the Gulf of Mexico, temporarily reversing the river’s course, receded. Yesterday, the water level in the stretch of river that runs through the city was down to a level of about 4.28 feet, well below the flood level of 17 feet and low even under normal circumstances, hydrology experts said…
The rain that Katrina dumped on Louisiana and Mississippi on Monday won’t affect the river’s water levels because many of the rivers in the area flow directly into the Gulf. Rain that Katrina deposits in Tennessee and farther north isn’t likely to reach New Orleans for at least two weeks, Mr. Richards said.
Parts of Kentucky, Ohio, and other areas where Katrina was headed have been unusually dry, meaning less runoff from the storm, Mr. Richards said.
Likewise, the water in Lake Pontchartrain isn’t likely to rise, said Richard Keim, assistant professor at the School of Renewable Natural Resources at Louisiana State University in Baton Rouge. The fresh water source that feeds it is only about as large as the lake itself, so while much rain has fallen in the area, not much will end up in the lake, says Mr. Keim. The larger question is when the storm surge will recede into the Gulf, the lake’s other water source. Lake Pontchartrain has only two narrow, winding outlets to the Gulf, so it is unclear how long it will take them to empty.