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Levees, floodgates, wiers, dams and other structures plus wetlands restoration will all be needed to make New Orleans safe against a 100 to 500 year storm. This is what we ought to be pricing rather than a "pie-in-the-sky" $9.5 billion "levees alone" plan that will not work in any case. This is a repeat of the events that led up to the 1927 river flooding when the Corps pursued a "levees only" flood control plan for the river in the face of contradictory scientific and engineering opinion. The BNOB Commission presented a comprehensive review in their February 2006 infrastructure report. The BNOB recommendations don't go quite far enough with regard to the river levees. What we need is an integrated solution: Remove the levees below Belle Chasse and let the river flood. Spending billions to rebuild levees in this area is lunacy. Ring levees would have to suffice for towns like Empire and Venice. During annual flooding highways would be closed and access limited so populations will have to be small. Or you could elevate the highways with the money saved on levees. Build the Donaldsonville Diversion to rebuild the Barataria basin, expand Caernavon (if it is still there after the levees are removed) and Davis Pond missions to include sediment deposition. Void those lawsuits and excessive awards but help the oyster fishermen relocate along the new salinity curves. Reestablish the barrier islands and restore the marsh topography by filling canals and removing unintended levees created by the canal construction. Restore natural ridges. Place flood gates and breakwater jetties at the entrance to the outfall canals or better yet move the pumping stations to the lakefront. Close the MRGO, seal it from salt water,  remove MRGO levees south of Shell Beach, add closable culverts to the MRGO levees preserved along Lake Borgne to let freshwater reach the St. Bernard marshes seaward of the levee. Place a flood wall in the Intercoastal waterway near the MRGO intersection. Place a floodgate in the GIWW/Algiers canal south of Belle Chasse Seal the lake entrance to the Industrial Canal with a dam Compartmentalize the city with internal levees, ponding areas and pumping capacity to minimize flooding extent. Some levees are in place today but have penetrations which must be sealed to be effective. Cancel the "Great Wall of Louisiana" levee engineering extravaganzas south and west of the city (Morganza to the Gulf, Donaldsonville to the Gulf, etc.) Seriously consider floodgates and levees that could be used to seal Lake Pontchartrain from the Gulf at the Rigolets and Chef Menteure Passes. Bring New Orleans Back Commission ( BNOB ) : BNOB issued 9 :: Continue reading... Can it happen again? : The simple answer is yes, and not if but when. :: Continue reading... Congress and Flood Protection : Congress continues to debate just how much it is willing to spend to :: Continue reading... Levees : The President signed the $2.9 billion appropriated by Congress to :: Continue reading... What is the flood protection plan? : Post Katrina the Corps has been jumping through hoops to find a way to protect New Orleans. :: Continue reading... The-Lake Pontchartrain Basin Foundation promotes the concept of 11 lines of defense.

Expensive, these projects must be funded by Congress. Complicated and interconnected the Corps of Engineers has overall responsibility for design, construction, and ongoing operations. The Corps should continue to have this responsibility with ongoing oversight by entities like the ASCE, IPET, or NSF. The reliance on local levee boards while appropriate after the Civil War should now end. Perhaps a national level board like the Pelican Commission should be  created. Furthermore the Corps mission should be explicitly expanded to include a role to advise and consent on strategic flood plain management. The Corps must not be able to hide behind the wording of Congressional appropriations to explain failures. 

Consider additional projects after the priorities are completed:

1. Move the pumps to the lakefront if and only if they can pump into the face of surge in the lake. Same concern for safe houses and pump automation efforts. Preventing backflow may be a more reasonable engineering task.
   
2. Equip the Chef and Rigolettes with big floodwalls to prevent / reduce Lake Pontchartrain surge. This will also reuire some big levees and will cost plenty
   
3. Build underwater ridges in Lake Borgne if they can impede surge
4. Remove or add flood gates to levees along the Atchafalaya river to rebuild the Terrebonne basin to protect communities west of the city.
   

The net effect of the best efforts will result in a city that is safer but not totally safe. Protection from generalized flooding in a worst case Cat 5 protection may be an elusive goal but it may be an acceptable risk based on its low probability (300 years).  Low lying Plaquemines, St. Bernard, northern parts of New Orleans East and parts of West Jefferson are difficult to protect. Flooding from time to time (every 20-40 years) has proven likely and should not be disasterous in these areas. Raised structures, ring levees and limited insurance makes more sense. There will always be some hearty souls who understand the risks and want to live in the coastal buffer, but developing subdivisions in these areas just increases the cost of the next flood. To protect the portion of the city west of the Industrial Canal requires the coastal marsh to the east be restored as a buffer.

Restoration of the Barataria basin protects the southern flank of the city. With continued erosion of the wetlands to the south the city will be vulnerable to a storm passing to the west if surge inundates the westbank and crosses the river to flood the city.