The Corps’ Mississippi Valley New Orleans (MVN) opened 10 bays of the Bonnet Carré Spillway on April 3, 2020 and plans to open 10 bays today (April 6, 2020) in order to keep the maximum flow at New Orleans at or below the target flow of 1.25 million cubic feet per second (cfs). Today’s estimated flow at Red River Landing is reported to be 1,283,000 cfs. By the end of the day the forecast flows with 20 bays open indicate that approximately 25,000 cfs will be diverted from the Mississippi River and into Lake Pontchartrain via the floodway. The flood control structure has total of 350 bays and less the 100 bays are expected to be opened to pass this flood.
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 Mississippi River forecast shows a gradual increase in flow up to the dates of the projected crest on April 12th to April 13th. The Mississippi River forecast shows a gradual increase in flow up to the projected crest dates. Current flow rates in the river have been less than originally forecasted. As of today’s forecast, the maximum predicted flow through our structure will be approximately 90,000 cfs for this opening, with an overall duration of 3-4 weeks.
BONNET CARRÉ SPILLWAY OPERATION 2020
|
DATE |
CARROLTON GAUGE (NEW ORLEANS) |
NUMBER OF BAYS OPENED |
NUMBER OF BAYSREMAINING OPEN |
SPILLWAY DISCHARGE CUBIC FEET PER SECOND (cfs) |
|
4/3/20 |
16.30 feet |
10 |
10 |
16,000 cfs |
|
4/4/20 |
16.38 feet |
0 |
10 |
19,000 cfs |
|
4/5/20 |
16.60 feet |
0 |
10 |
21,000 cfs |
|
4/6/20 |
16.70 feet |
10 |
20 |
25,000 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 Bonnet Carré Floodway continues to operate and reduce flow at New Orleans, LA. This will cause New Orleans, LA and Reserve, LA to crest before upstream locations. New Orleans, LA will crest at the 17.0ft flood stage on Wednesday, April 8th and will stay near this level for the next 1 ½ weeks. The floodway has been operated for 3 years in a row and 4 of the last 5 years.
The 16 day future rainfall guidance is showing a secondary crest on the lower Ohio River for late April. This crest would be 10 feet lower than the current crest and it would only slow recessions on the lower Mississippi River for early May.”
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.
