The Corps’ Mississippi Valley New Orleans (MVN) did not open any bays on the Bonnet Carré Spillway (Mile 128.8 .to 127.3 Above Head of Passes [AHP])yesterday (Thursday, May 23, 2019).
The MVN operated the Bonnet Carré Spillway from February 27 to April 11, 2019, prior to 2019 the Spillway had never been operated in back-to-back years (2018 and 2019). The required opening of the flood control structure twice in the same year represents another historic first.
The maximum flow above the Spillway yesterday was 1.355 million cfs based on the flow measured at Red River Landing (Mile 302.4 AHP), with calculations and timing adjusted for downriver at Bonnet Carré.
The operation of the Morganza Spillway (Mile 280 AHP) may indeed be necessary over the next 10 days, the MVN advises that:
“Preparations are underway for a potential/partial opening of the Morganza Floodway in early June, based on very high stages predicted at the structure, coupled with the potential for even higher stages/flow over the longer term. No official decision to open thus far.”
BONNET CARRÉ SPILLWAY SECOND OPERATION 2019
|DATE||CARROLTON GAUGE (NEW ORLEANS)||BAYS OPENED TODAY||TOTAL NUMBER OF BAYS OPEN||TOTAL NUMBER OF BAYS CLOSED||SPILLWAY DISCHARGE CUBIC FEET PER SECOND (cfs)|
|5/10/19||17.25 feet||60||60||N/A||78,000 cfs|
|5/11/19||16.80 feet||10||70||N/A||82,000 cfs|
|5/12/19||16.80 feet||0||70||N/A||79,000 cfs|
|5/13/19||17.00 feet||58||128||N/A||116,000 cfs|
|5/14/19||16.75 feet||10||138||N/A||127,000 cfs|
|5/15/19||16.70 feet||0||138||N/A||127,000 cfs|
|5/16/19||16.60 feet||0||138||N/A||122,000 cfs|
|5/17/19||16.60 feet||0||138||N/A||122,000 cfs|
|5/18/19||16.80 feet||0||138||N/A||127,000 cfs|
|5/19/19||16.90 feet||10||148||N/A||142,000 cfs|
|5/20/19||16.80 feet||0||148||N/A||148,000 cfs|
|5/21/19||16.80 feet||20||168||N/A||161,000 cfs|
|5/22/19||16.80 feet||0||168||N/A||161,000 cfs|
|5/23/19||16.80 feet||0||168||N/A||158,000 cfs|
The stages below the Spillway will be artificially controlled by the flow diverted form the Mississippi River through the open flood control structure and into Lake Pontchartrain.
The MVN manages the opening and closing of bays on the flood control structure to ensure the maximum flow at New Orleans remains at/or below the trigger point flow of 1.25 million cubic feet per second (cfs) in accordance with the approved Bonnet Carré Spillway Water Control Manual. The crest prediction above the Spillway has been pushed back to June 6 to June 12 (2019) based on anticipated rainfall. The operation of the flood control structure is expected to continue through mid- to late-June.