Saturday, May 7, 2011

The water is rising

I jogged on the levee last week and saw the Mississippi was just a few feet from the top. Now, if you've heard anything about Hurricane Katrina, that fact might give you pause. But the Army Corps of Engineers has a few spots along the length of the river valley where it can release some of the excessive precipitation from up north so we don't get swept away again.

There were folks taking pictures of the river when I was there. I said to one guy: No problem - we all have boots we use for Jazz Fest fairgrounds mud.

The height/depth of the water on the Mississippi River has been sharing the front page of the Times-Picayune with Jazz Fest performances all week. It takes a lot to displace the Fest from the main news story around here. Everybody's attention is focused on the music schedule and how many fantastic performances they can cram into their precious two weeks as possible.

So, a large amount of farmland in Missouri was just submerged to save the Crescent City. And folks in Cairo, Ill., have evacuated, according to the New York Times.

We have the Bonnet Carre Spillway, which will open Monday. They say this is the worst the river has been since 1973 when I was in college. I remember hearing about the ships floating at eye level. (I spent that year studying in Europe.) Friday, I took my visiting college friend to see the river. She said, "They call it the Mighty Mississippi and you can see why." No doubt. It nurtures us and could easily drown us.

Ironically, as the northern states have been awash in rainwater, we haven't seen the stuff in a month. This is the first Jazz Fest without a deluge. Marvelous, but the plants are thirsting for rain.

Bonnet Carre Spillway will open Monday as Mississippi River swells

Published: Friday, May 06, 2011, 12:15 AM
The Times-Picayune 
The Bonnet Carre Spillway will be opened Monday to relieve levees along the Mississippi River strained by near-record flow, which Gov. Mond described as "a massive amount of water heading our way."
Louisiana spillways readied for onslaught of Mississippi River flood water
EnlargeTED JACKSON / THE TIMES-PICAYUNE Mississippi River water seeps beneath the Bonnet Carrie Spillway structure as record flood waters creep ever closer to the lower Mississippi River, Wednesday, May 4, 2011.Louisiana spillways readied for onslaught of Mississippi River flood water gallery (17 photos)
The spillway opening is likely to begin ay about 8 a.m.
A decision on opening the Morganza Spillway, which diverts water to the Atchafalaya River above Baton Rouge, is expected to follow within days, said Col. Ed Fleming, commander of the New Orleans District of the Army Corps of Engineers.
A much larger amount of water also is now flowing into the Atchafalaya River through the Old River Control Structure, above Morganza, he said, as it continues to receive a congressionally mandated 30 percent of the Mississippi's bloated flow.
"The National Weather Service estimates show that the river will be up to historically high levels for approximately seven to 10 days, which will be especially trying to the fortification of our levees and floodwalls," Jindal said.
The corps also will begin stopping work today on a 15-mile stretch of Mississippi River levee around Algiers Bend, from English Turn to Oakville. The stoppage is triggered by a rule prohibiting subsurface and surface work within 1,500 feet of river levees when the river rises to 15 feet above sea level at the Carrollton Gage in New Orleans, which occurred Thursday. The river is forecast to crest there at 17 feet on May 24.
chart-jindal-050611.jpgView full size
Workers will replace grass and other armoring before a complete shutdown, Fleming said.
With the Mississippi not expected to drop below 15 feet until mid-June, that key segment of the new system to protect the area from storm surge caused by hurricanes with a 1 percent chance of occurring in any year -- a so-called 100-year storm -- will not be completed by the agency's oft-repeated June 1 deadline.
A mid-June high river also could pose an unusual threat of river levees being overtopped if an early-season tropical storm or weak hurricane were to hit in just the right spot, said Joannes Westerink, a professor of civil engineering and hurricane surge modeler at Notre Dame and a member of the Southeast Louisiana Flood Protection Authority-West.
"Surge builds up during many storms along the lower river as it is driven by easterly winds over Breton Sound and enters the deep and efficient river between Pointe a la Hache and Venice, then propagates upstream," Westerink said.
The National Weather Service's Lower Mississippi River Forecast Center's 28-day prediction calls for the river to be at 16.1 feet on June 1, the start of hurricane season.
bonnet-carre-spillway-teeth.jpgView full sizeHigh water from the Mississippi River seeps through the Bonnet Carre Spillway structure on Thursday.
Floodwalls protect downtown New Orleans to 20 feet, which means there will be only about 4 feet of freeboard in the river levee system.
"We haven't done any modeling of that at this point, but we're prepared to floodfight the levees as needed," Fleming said. "Mother Nature has a vote, and we also have to take into account that public safety is our top priority. And the public safety in front of our face is a riverine flood."
The Bonnet Carre Spillway, located between Norco and Montz in St. Charles Parish, can divert up to 250,000 cubic feet of water per second into Lake Pontchartrain, and away from communities downstream.
The corps has a detailed environmental monitoring plan in place that will track water quality, dissolved oxygen and sediment flowing into the lake. In past openings, the high level of nutrients in the river fed major algae blooms in the lake, but did little long-lasting damage.
chart-jindal2-050611.jpgView full size
Indeed, past spillway openings have been credited for repairing damage done to the lake's bottom by shell dredging before it was banned in 1989.
The 15-foot level in New Orleans also is the trigger for the corps and local levee districts to begin daily inspections of levees along both the Mississippi and Atchafalaya for scouring, seepage and sand boils.
Seepage already has been spotted at the Diamond Sugar facility in Arabi and is expected at another location in Chalmette, said Heath Jones, emergency manager for the corps.
The high river threat to New Orleans becomes clear when the various diversions are added together. The most recent river forecast provided to state officials indicates that even with all of the Bonnet Carre Spillway's 350 bays opened, the river would rise to 19.5 feet, a half-foot from overtopping floodwalls in downtown New Orleans, if the Morganza Spillway were not opened.
Fleming said corps officials expect about half of the Morganza's capacity -- 300,000 cubic feet per second -- to be used. That spillway will be opened slowly to allow for the escape of wildlife, which could include protected Louisiana black bears.
At the Old River Control Structure, the water flow will increase to 620,000 cubic feet per second, compared with 365,000 cubic feet per second on Thursday.
Mark Schleifstein can be reached at or 504.826.3327.

© 2011 All rights reserved.

No comments:

Post a Comment