US Army Corps of Engineers
New Orleans District Website Website

Bonnet Carre Spillway Photos

Spillway Operation Information

The decision to operate or "open" the Bonnet Carré Spillway is the responsibility of the Mississippi River Commission president who has broad jurisdiction over the entire MR&T Project. The MRC president relies heavily on the recommendations of the New Orleans district engineer who is responsible for the actual operation of the Bonnet Carré structure and floodway.

The decision to operate the Bonnet Carré Spillway is made when existing conditions, combined with predicted river stages and discharges, indicate that the mainline levees in New Orleans and other downstream communities will be subjected to unacceptable stress from high water. Included in the complex decision process are environmental considerations, as well as hydrologic, structural, navigational and legal factors.

Once the decision to open the Bonnet Carré structure has been made, actual operation of the structure is relatively simple. Two cranes, which move along tracks atop the structure, are used to individually lift each timber from the required number of bays. The timbers are raised from their vertical position across the weir opening (where together they serve as a dam against the high water) and are laid horizontally on top of the structure for later use in its closing. A complete opening of all 350 bays requires about 36 hours to lift the 7,000 wooden timbers in the structure. If a quicker opening of the structure is ever required, emergency procedures can release 20 timbers at once and reduce the opening time to three hours.

The Corps of Engineers initiated surveys and preliminary investigations for the Bonnet Carré Spillway in 1928. Construction of the spillway structure began in 1929 and was completed in 1931. The guide levees were completed in 1932, and highway and railroad crossings in 1936. The total project cost was $14.2 million.

 

Year Days Bays Opened (%) Opened Ideal flow capacity
1937 48 285 81.4% 203,571 cu ft/s
1945 57 350 100% 250,000 cu ft/s
1950 38 350 100% 250,000 cu ft/s
1973 75 350 100% 250,000 cu ft/s
1975 13 225 64.3% 160,714 cu ft/s
1979 45 350 100% 250,000 cu ft/s
1983 35 350 100% 250,000 cu ft/s
1997 31 298 85.1% 212,857 cu ft/s
2008 31 160 45.7% 114,286 cu ft/s
2011 42 330 94.3% 235,714 cu ft/s
2016 22 210 60.0% 203,000 cu ft/s
2018 30 186 53.14%

196,000 cu ft/s

2019

First

44 206 59% 208,000 cu ft/s

2019

Second

79 168 48% 163,000 cu ft/s

Historic Opening Pace

   After heavy rains in the Mississippi and Ohio River valleys increased river stages, the Corps opened the spillway on May 9, 2011.
 
  The Bonnet Carre Spillway was partially opened on Monday, May 9, 2011 in order to keep the volume of the Mississippi River flows at New Orleans from exceeding 1.25 million cubic feet per second (cfs). It was fully closed 43 days later on Monday, June 20. The recreational areas of the spillway will be open; however, members of the public  should use caution when accessing the area and be aware of water hazards, wildlife, such as snakes and alligators, as well as excessive heat and humidity.

 

 

 

 

 

 

 

 

 

 

Spillway Opening Pace 2011 vs. 2008

Day 2011 Date Bays Opened Total Opened 2011 2008 Date Bays Opened Total Opened 2008
1 May 9 28 28 April 11 38 38
2 May 10 44 72 April 12 46 84
3 May 11 38 110 April 13 0 84
4 May 12 102 212

April 14

0 84
5 May13 52 264 April 15 0 84
6 May 14 36 300 April 16 6 90
7 May 15 30 330 April 17 20 110
8 May 16 0 330 April 18 25 135
9 May 17 0 330 April 19 25 160
10-42           May 18- June 20 0 0 April 20-29 0 160

 

Spillway Opening Pace 2008 vs. 1997

Day 2008 Date Bays Opened Total Opened 2008 1997 Date Bays Opened Total Opened 1997
1 April 11 38 38 March 17 30 30
2 April 12 46 84 March 18 40 70
3 April 13 0 84 March 19 30 100
4 April 14 0 84 March 20 50 150
5 April 15 0 84 March 21 40 190
6 April 16 6 90 March 22 35 225
7 April 17 20 110 March 23 25 250
8 April 18 25 135 March 24 15 265
9 April 19 25 60 March 25 20 285
10 - 20     April 20-29 0 160 March 26 13 298

 

 

 

 

 

2016 Opening Pace

After heavy rains in the Mississippi and Ohio River valleys increased river stages, the Corps opened the spillway on Jan. 10, 2016.

The Bonnet Carre Spillway was partially opened on Monday, Jan. 10, 2016 in order to keep the volume of the Mississippi River flows at New Orleans from exceeding 1.25 million cubic feet per second (cfs).  

Day Date Bays Opened Total Opened Discharge
1 Jan. 10 20 20 21,500 cfs
2 Jan. 11 18 38 32,000 cfs
3 Jan. 12 22 60 52,270 cfs
4 Jan. 13 30 90 91,800 cfs
5 Jan. 14 10 100 104,000 cfs
6 Jan. 15 30 130 132,000 cfs
7 Jan. 16 52 182 196,000 cfs
8 Jan. 17 28 210 203,000 cfs
9 Jan. 18 0 210 201,000 cfs
10 Jan. 19 0 210 199,000 cfs
11 Jan. 20 0 210 192,000 cfs
12 Jan. 21 0 20 192,000 cfs
13 Jan. 22 0 210 192,000 cfs
14 Jan. 23 0 210 186,000 cfs
15 Jan. 24 0 210 194,000 cfs
16 Jan. 25 -13 197 168,000 cfs
17 Jan. 26 -20 177 150,000 cfs
18 Jan. 27 -22 155 126,000 cfs
19 Jan. 28 -24 131 91,000 cfs
20 Jan. 29 -40 91 62,000 cff
21 Jan. 30 -34 57 30,000 cfs
22 Jan. 31 -33 24 8,000 cfs
23 Feb. 1 -24 0