Mississippi River Flooding

When officials open the Morganza Spillway, the clock will start ticking immediately on the possibility of backwater flooding coming to West Terrebonne in large amounts.

Terrebonne Parish Gordon Dove said last week it’s not a question of if, but how soon officials will pull the trigger and begin opening bays on the spillway, a flood release structure built in the early 50s, at river mile marker 280 on the west bank of the Mississippi River, near the town of Morganza.

That decision came down on Monday when Gov. John Bel Edwards confirmed the spillway will open on June 2.

During major flooding events, the spillway was designed to be used as a last resort, to relieve high water levels in the Mississippi River, by releasing more water into the Atchafalaya River, which, in turn, flows into the Atchafalaya Basin on the border of Terrebonne and St. Mary parishes.

Dove said the current situation is somewhat of a perfect storm for flooding locally.

“Still, what everyone needs to realize is that 30 percent of the Mississippi River flows into the Atchafalaya River, no matter what,” Dove said. “What’s happening is that the country has experienced tremendous amounts of rain this year. All of the tributaries which flow into the Mississippi River, were at high levels already, as we’ve all seen on tv, the flooding in other states. Having said that, the Atchafalaya River’s water level in Morgan City has been over 6 feet since January of this year, and that is considered flood stage.”

Dove said because of that, he began proactive measures in tackling backwater issues, because of the flow of the Atchafalaya River when it leaves Morgan City. The parish president said it flows backwards, into Bayou Chene, which is a parish dividing line between Terrebonne and St. Mary Parishes.

Furthermore, unlike 2011 (the last year Morganza opened), which was basically the year of the drought, which lessened the problem, 2019 has been “a very wet year so far, and that’s why the backwater problems started — a process now many months in the making.”

Dove said pumps have been working overtime, pumping 500 million gallons of water out of area parish bayous.

With the opening of the Morganza Spillway eminent, he said levee protection for areas around Valhi Boulevard, Sugarwood and Lake Manchester has been somewhat escalated, as crews have been installing make-shift levees, using sheet pilings.

“Also, projects around Valhi Blvd were already planned for this year, so in the wake of the backwater flood threats, they’ve been tuned up,” Dove said.

Terrebonne Parish Councilman Darrin Guidry said the first issue in stopping backwater threats from the Atchafalaya River into Bayou Chene, should be on its way by Saturday, with the installation of a temporary flood control structure in Bayou Chene.

Guidry explained that as the Atchafalaya flows backward into Bayou Chene, it then flows into Bayou Boeuf, Chacahoula, and other Terrebonne waterways, swelling them.

“The problem has been so far, that as fast as we’ve been pumping the water out of our bayous, more is flowing in because of high levels in Bayou Chene,” he said. “We should see relief with that problem when the barge is sunk on the Terrebonne and St. Mary Parish lines.”

While inspecting the installation of aqua-dams in lower St. Martin Parish last Saturday, Gov. John Bel Edwards announced a 400-foot barge would be sunk on and that it would be fully operational by Saturday, June 1. That process is expected to begin May 28.

He said the state will pick up the cost for the barge, and its installation, which he said is around $7 million.

“No parish will have to pay the brunt of this emergency,” Edwards said.

Sinking a barge to slow floodwaters was first employed in 1973 by former Morgan City Mayor, the late “Doc C.R. Brownell,” and its success was touted for years after.

In 2011, then Morgan City Mayor Tim Matte, along with St. Mary Parish Levee District Chairman Bill Hidaldo, teamed up with Terrebonne and other neighboring parishes to sink a barge once more, to stop threatening backwater.

The backwater barge control system stretches from Avoca Island at Morgan City, across to Terrebonne Parish, in what is known as Tabor Canal, a tributary of Bayou Chene.

Dove said the barge is a must, “but its success rate will be intense as we’re much more swollen with water now, than what we were in 2011.”

In addition, Dove said 20 members of the National Guard are working this week to install 13,000 linear feet of Tiger Boom to create temporary levees for Bayou Black and other parts of Gibson.

Regarding the number of bays to be opened and water flow from the Morganza Spillway, Edwards said that the spillway can divert roughly 600,000 cubic feets per second (cfs) of water, if necessary. .

But the governor said that in 2011, the Corps ordered bays to reach roughly 125,000 cfs.

“I’m not expecting the 2011 figure to be their target in 2019, however, what I do expect is that we will have to live with the backwater situation maybe up to months from now,” Edwards said.

The governor said that in 2011, the Corps ordered bays to reach roughly 125,000 cubic feet per second gallons of water.

“I’m not expecting that to be their target in 2019, however, what I do expect is that we will have to live with the backwater situation maybe up to months from now,” Edwards said.

Edwards said the area needs a change in wind patterns, which are also currently not in our favor.

“There is another issue - we’ve been experiencing North winds. We need South winds. I’m a praying man, and I’m calling on everyone to pray that we start receiving those,” the governor said. “South winds will move the water out and away from us.”

Terrebonne Councilwoman Arlanda Williams however, said she believes, “we could be facing a devastating situation locally — given the information that’s been presented.

“We are facing a long days and nights, but we will protect the residents of the Bayou Black and Gibson area,” she said.

Williams said sandbags will more than likely be available in the coming days.

Dove said challenges will also come with sewage and septic systems, as backwater flooding will not allow them to work as the situation takes fold.

Edwards said earlier this year, he announced $80 million in funding for a permanent flood control structure at Bayou Chene, because the concept had proved so successful.

“Rain here, and weather conditions elsewhere, have caused us to move ahead with a temporary structure, although some of the things that will be installed, are going to permanent,” he said. “Thank God that we have a surplus in the state’s funds - a first since Gov. Kathleen Blanco left office.”

State Sen Bret Allain, who represents Terrebonne as well as St. Mary Parish, said the state Coastal Protection and Restoration Agency is in constant communication with the U.S. Army Corps of Engineers as well as with the coastal parishes and levee districts that could be potentially impacted by high water, as a result of the potential opening of the Morganza Spillway.

“This very situation is why we fought so hard to secure a commitment and funding for a permanent Bayou Chene structure,” said Sen. Allain. “While the permanent $80 million Bayou Chene floodgate project is expected to begin construction this fall, the project isn’t expected to be operational until summer 2021; this, as the region braces for the opening of the Morganza Spillway.”

SPILLWAY HISTORY

Construction of the Morganza Spillway began in the late 1930s and was completed in 1954. The gates were opened during the flood of 1973, which proved devastating to many communities along the Atchafalaya River and connecting bayous; but again in 2011, and then, with little effect to the area.

The spillway was constructed to maintain a flow of 1.5 million cubic feets per second, below the floodway,  The structure is 3,900 feet in length with 125 bays.

The Morganza Spillway is roughly 126 miles away from Terrebonne Parish.

The Atchfalaya River intersects the Mississippi River in Simmesport, La, and extends through portions of eight other parishes, ending in Morgan City.

Terrebonne Parish Levee District Director Reggie Dupre remembered vulnerable areas from 1973.

“I can tell you that during the 1973 flood, we had water from Gibson to Montegut - even Savanne Road,” he said. “We also had water between La. Highway 311 and La. Highway 182.” •

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