The Corps’ Mississippi Valley New Orleans (MVN) closed 20 bays at the Bonnet Carré Spillway today and expects to completely close the structure tomorrow, Friday, May 1, 2020. The bays are operated to manage the maximum flow at New Orleans and ensure it does not exceed the target flow of 1.25 million cubic feet per second (cfs). The Spillway’s operation is based on the estimated flow at Red River Landing which is utilized to manage the number of bays opened to ensure the flow of 1.25 million cfs is not exceeded below the flood control structure. The estimated flow at Red River Landing today is reported to be 1,170,000 cfs.
The Bonnet Carre´ Spillway is a flood control structure extending from Mile 128.8 Above Head of Passes to Mile 127.3 Above Head of Passes that is designed to pass flood water from the Mississippi River into Lake Pontchartrain to prevent flooding below the Spillway.
The MVN opened a total of 90 bays and has now closed 80 of those bays. The forecast flow with a total of 10 bays open is estimated to be 16,500 cfs which is being diverted from the Mississippi River and into Lake Pontchartrain via the floodway. The flood control structure has a total of 350 bays and just over one-quarter of the bays were opened to pass the cresting flood waters.
The Mississippi River forecast indicates a gradual and steady decrease in flow into the third week of May. The maximum flow through the flood control structure for this opening with 90 bays opened was 90,000 cfs. The operation of the flood control structure will have a duration of approximately 29 days, with full closure expected tomorrow (Friday, May 1, 2020).
BONNET CARRÉ SPILLWAY OPERATION 2020
|DATE||CARROLLTON GAUGE (NEW ORLEANS)||DAILY NUMBER OF BAYS OPENED||DAILY NUMBER OF BAYS CLOSED||TOTAL NUMBER OF BAYS OPENED||SPILLWAY DISCHARGE CUBIC FEET PER SECOND (CFS)|
|4/3/20||16.30 feet||10||N/A||10||16,000 cfs|
|4/4/20||16.38 feet||0||N/A||10||16,000 cfs|
|4/5/20||16.60 feet||0||N/A||10||16,000 cfs|
|4/6/20||16.70 feet||10||N/A||20||24,700 cfs|
|4/7/20||16.75 feet||25||N/A||45||48,000 cfs|
|4/8/20||16.70 feet||5||N/A||50||50,000 cfs|
|4/9/20||16.70 feet||20||N/A||70||63,000 cfs|
|4/10/20||16.80 feet||20||N/A||90||76,000 cfs|
|4/11/20||16.90 feet||N/A||N/A||90||76,000 cfs|
|4/12/20||17.00 feet||N/A||N/A||90||80,000 cfs|
|4/13/20||17.10 feet||N/A||10||80||80,000 cfs|
|4/14/20||17.15 feet||N/A||0||80||81,000 cfs|
|4/15/20||17.30 feet||N/A||0||80||76,000 cfs|
|4/16/20||17.30 feet||N/A||0||80||90,000 cfs|
|4/17/20||17.30 feet||N/A||0||80||90,000 cfs|
|4/18/20||17.30 feet||N/A||0||80||88,000 cfs|
|4/19/20||17.30 feet||N/A||0||80||84,000 cfs|
|4/20/20||17.10 feet||N/A||0||80||83,000 cfs|
|4/21/20||17.10 feet||N/A||0||80||77,000 cfs|
|4/22/20||17.10 feet||N/A||0||80||74,000 cfs|
|4/23/20||16.90 feet||N/A||0||80||71,000 cfs|
|4/24/20||16.90 feet||N/A||10||70||60,500 cfs|
|4/25/20||16.84 feet||N/A||10||60||54,000 cfs|
|4/26/20||16.80 feet||N/A||10||50||43,000 cfs|
|4/27/20||16.70 feet||N/A||10||40||36,000 cfs|
|4/28/20||16.50 feet||N/A||10||30||28,000 cfs|
|4/29/20||16.60 feet||N/A||0||30||28,000 cfs|
|4/29/20||16.50 feet||N/A||20||10||16,500 cfs|
A forecast update provided by our colleagues from the National Oceanic and Atmospheric Administration’s (NOAA) Lower Mississippi River Forecast Center is attached, highlights from this update specific to the New Orleans are reproduced below:
“The Mississippi River is rising from Cairo, IL to Caruthersville, MO. The river is steady from Osceola, AR to Tunica, MS with rises for this segment beginning tomorrow. For the Mississippi River downstream of Tunica, the river will continue to fall through Monday and then hold steady or slightly rise through next week.
On the lower Mississippi River, major flooding will continue at Baton Rouge, LA for the next couple of weeks. Vicksburg, MS downstream to Baton Rouge, LA will continue to have minor to moderate flooding through most of May. Impacts are mainly to agriculture and navigation.
The 16 day future rainfall guidance shows a secondary rise on the lower Ohio River which will keep Cairo, IL above flood stage through mid May. This secondary rise will only slow recessions on the lower Mississippi River and extend the flooding for a couple of more weeks.”
The Bonnet Carré Anchorage was closed by the U.S. Coast Guard at 6:00 a.m. on April 3, 2020, vessels shall not enter the anchorage or the area extending 600 feet into the river from the Bonnet Carré Spillway, between MM 127 and MM 129 and the shoreline of Lake Pontchartrain.
“MARINERS ARE ADVISED THAT THE M/V KENT WILL BE STATIONED ON THE LEFT DESCENDING BANK JUST NORTH OF THE SPILLWAY TO MONITOR MARINE TRAFFIC ON VHF MARINE CHANNELS 16 AND 67. SHOULD AN INCIDENT OCCUR BETWEEN THE SPILLWAY AND MISSISSIPPI RIVER MILE 140 ABOVE HEAD OF PASSES (AHP) INVOLVING AN ADRIFT VESSEL, BARGE, ETC., THE ATTENDING VESSEL OR ANY OTHER VESSEL IN THE VICINITY SHOULD IMMEDIATELY REPORT THE INCIDENT TO THE M/V KENT.”