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By Dec. 20, when this NASA Terra MODIS satellite image was taken, the Mississippi and Atchafalaya rivers already were pushing huge plumes of sediment into the Gulf of Mexico. Water leaking through pins in the Bonnet Carre Spillway just above New Orleans also contained enough sediment to add a brown plume to the western edge of Lake Pontchartrain. On Monday, the state Coastal Protection and Restoration Authority announced a ban on driving or walking on levees along both rivers. The Mississippi is expected to rise to 17 feet in New Orleans by Jan. 12, while the Atchafalaya should rise to 9.5 feet at Morgan City by Saturday.

(NASA Terra satellite)

The state Coastal Protection and Restoration Authority announced Monday (Jan. 4)  it has banned all vehicle and foot traffic on levees along the Mississippi and Atchafalaya rivers until further notice, in response to high water levels in both rivers.

On Monday afternoon, however, CPRA chairman Chip Kline said local levee districts could still allow use of paved paths for walking and bicycling, and allow vehicle access to locations such as the Butterfly Park behind the Audubon Zoo in New Orleans, but would have to make a formal decision deviating from the state policy.

"We wanted to give the levee districts the tools they need to protect the public," Kline said in a telephone interview. "In conversations through the weekend and continuing to this afternoon, we have been urging them to use common sense."

In Baton Rouge, River Road is within 300 feet of the levee, he said, but has not been shut down. "But there will be some additional law enforcement presence," he said.

He said the Pontchartrain Levee District, which oversees Baton Rouge levees, is still discussing the levee access issue, however.

Bob Turner, executive director of the Southeast Louisiana Flood Protection Authority-East, which oversees the Orleans, Jefferson and Lake Borgne levee districts on the east bank of the river in the New Orleans area, said that after conversations with Kline and others at CPRA, the authority will continue to allow public access to the levees at this time.

"For the time being, yes," Turner said. "Basically we have to use some common sense in how we go about this, in highly populated areas where the public traditionally has access to the levees over time."

He said the districts' levee police forces will be carefully monitoring the levee access for trouble, however, "to make sure nothing is going on that's dangerous for the levees or the people."

"When it gets to the point where the water is high enough and enough of a concern to keep them off, we'll have the ability to shut that down," he said.

The districts also will allow shipping industry traffic to use roads over levees for the time being, he said.

Representatives of the Southeast Louisiana Flood Protection Authority-West were unavailable for comment on whether their levee districts would allow pedestrians on the levee or vehicle access to locations on the batture.

The restrictions are designed to protect the levees and to assist state inspectors, local levee districts and the Army Corps of Engineers, who are inspecting the levees for sand boils, seepage, and other problems. Those inspections are occurring twice a week at the moment, but the corps is expected to enter Phase 2 of its flood response later this week, when the Mississippi River reaches 15 feet at the Carrollton Gage in New Orleans.

According to the National Weather Service's Lower Mississippi River Forecast Center, based in Slidell, the river was at 13.3 feet on Monday, will reach 15.4 feet on Friday and 17 feet on Jan. 12. While 17 feet is the official flood stage at that gage, levees and floodwalls protect New Orleans to water heights of at least 20 feet. And the levees actually have been raised to include about 3 feet of "freeboard," additional height above the 20 feet, according to corps officials.

The corps has scheduled a news conference for 3:30 p.m. Tuesday to discuss the potential of opening the Bonnet Carre Spillway in St. Charles Parish to keep the river level in New Orleans no higher than 17 feet, and its Phase 2 flood fight plan.

On Monday, the corps issued its annual public notice to residents living within the Mississippi River floodways -- including the Morganza Floodway, Bayou Des Glaises Loop, Old River Control Structure project area, West Atchafalaya Floodway and Atchafalaya Basin Floodway -- that they may be activated during a high water event, such as the one now under way.

"The notice serves as a reminder to those that live, operate and/or do business within these floodways that there is a risk that they may experience flooding if the floodways are activated," corps officials said in a news release.

But they stressed that no decision has yet been made on opening the Morganza Floodway or other floodways. If such a decision is made, notice will be given in advance to allow time for evacuation of people, livestock and personal belongings, officials said.

The state's levee rule bans all pedestrian and vehicular traffic, including driving and parking, within 300 feet of the levee center line of the river levees and other federal, state and local flood control structures along the rivers. The ban includes all terrain vehicles and mowing equipment.

Also prohibited will be the placement of dumpsters, heavy equipment, supply stockpiles, fuel tanks or piping. Transport of heavy loads over the levees or disturbing the grass cover or seepage areas on or near the levees also is prohibited. The ban also includes any subsurface work, including pile driving, within 1,500 feet of the levees and other structures, and the use of explosives, such as for seismic surveys or demolition, within 5,000 feet.

The rule also prohibits a variety of actions within the levees, including tying or mooring of logs, rafts, boats or other floating objects within 100 feet of where the levee's toe would be when no water is against the levee, or 180 feet from the levee's center line, whichever is greater. The rule also prohibits mooring vessels or objects in the rivers where they can be driven against the levees during windstorms or when water rises.

Waivers may be granted by local levee districts and the coastal authority, on a case-by-case basis, but not for subsurface work or for use of explosives. The authority can be reached by email at CPRARequest@la.gov.

On Monday, the river was at 52.1 feet at Red River Landing, just above Baton Rouge, and will continue to rise to near 62.5 feet by mid-January. Flood stage at Red River Landing is 48 feet. All river islands from there to Baton Rouge are already inundated. At 58 feet, farmland at Angola prison on the river's left bank becomes inundated, and at 59 feet, the east bank levee will be topped, inundating prison land between the two levees. At 62 feet, Angola Landing will be under water and all ferry service will be terminated.

At Reserve, the river was at 19 feet on Monday. The river is forecast to rise above flood stage, 22 feet, before midnight Friday and continue rising to near 24 feet by  Jan. 12. At 22 feet, marine and industrial interests along the river, upstream barge operators and facilities are impacted, and navigation becomes difficult for smaller river vessels.

In Baton Rouge, the river was at 34.8 feet on Monday, just below the 35 foot flood stage. The river is forecast to rise above flood stage on Monday afternoon, and reach a crest level of 44 feet by mid-January. At 40 feet, the grounds of the older part of Louisiana State University's campus becomes soggy. The rest of the campus and the city are protected by levees. At 43 feet, unprotected low-lying areas will be flooded and the west side of the river will see some agricultural operations impacted.

In Morgan City, near the mouth of the Atchafalaya, the river was at 5 feet on Monday and was expected to rise above the 6 foot flood stage by Saturday afternoon. The river is expected to reach a crest of near 9.5 feet by Saturday afternoon. At 9 feet, structures on the river side of protection walls in Morgan City and Berwick will be under water.

This story has been updated to show that local levee districts have the authority to allow access by the public to using levee paved areas and to cross the levee under a state order banning use of the Mississippi and Atchafalaya river levees during the present high water period.