Monday, January 11, 2016

They Opened the Bonnet Carre Spillway Yesterday. Morganza to Open as Soon as the Day after Tomorrow.

Third time since 2008 (inclusive). Before that it was opened only once a decade.

Jeff Masters reports:

At 10 am CST January 10, 2016, the U.S. Army Corps of Engineers opened the gates on the Bonnet CarrĂ© Spillway in St. Charles Parish, Louisiana to allow flood waters from the swollen Mississippi River to flow into Lake Pontchartrain. This is the earliest that the Corps has been forced to open the spillway, and just the 11th time since it became operational in 1931 that it has been used. The only other time the spillway has been opened in January was back in 1937. All of the other openings have come in spring or early summer. Opening of the spillway is expected to keep the Mississippi River below its 17-foot flood stage in New Orleans–just 3 feet below the tops of the levees. The river is expected to crest in New Orleans on Tuesday, January 12.
There is also chance that the Corps will be forced to open the Morganza Floodway in Pointe Coupee Parish northwest of Baton Rouge, which would divert water from the Mississippi River down the Atchafalaya River. This floodway has been opened only twice–in 1973 and 2011–and has a considerably higher cost of being opened than opening of the Bonnet CarrĂ© Spillway, due to the large amount of agricultural lands that would be flooded below the Morganza Floodway. The Sunday morning forecast from the NWS River Forecast Center predicted that the Mississippi River would crest at Red River Landing, just above the Morganza Floodway, on January 18. The predicted crest of 61.0′ is just 2.4′ below the all-time record crest of 63.39′ set on May 18, 2011, when the Corps was forced to open the Morganza Floodway in order to relieve pressure on the Old River Control Structure. The earliest the Corps would open the Morganza Floodway would be Wednesday, January 13.

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