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As seen from the I-10 Mississippi River bridge, the water levels of the Mississippi River are up on the downtown riverfront Tuesday, March 6, 2018, in Baton Rouge, La. The new State Capital Building rises to a point in the background, with the USS Kidd floating in its cradle on the river near the Baton Rouge Dock in the foreground.

ADVOCATE STAFF FILE PHOTO BY BILL FEIG

Some local governments began taking early precautions Thursday for expected river crests on the Mississippi and Atchafalaya later this month as the U.S. Army Corps of Engineers also stepped up its own flood fight with the partial opening of the Bonnet Carre Spillway near New Orleans.

The two major rivers in south Louisiana are part of interconnected systems created by nature and plumbed by humans, so high water is affecting both. 

East Baton Rouge city-parish government plans to install dirt-filled HESCO baskets Saturday on a Mississippi levee section near the intersection of Main and North streets, a known low spot.

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City-parish spokeswoman Rachel Haney said the baskets will add an extra three feet to the top of the 36-foot section of levee near Baton Rouge's downtown.

The city-parish also has 10,000 pre-filled sandbags as well as 10,600 feet of inflatable water dams available as additional precautionary measures.

In Assumption Parish, which is subject to backwater flooding from high water in the Atchafalaya River, Sheriff Leland Falcon announced a joint sheriff-parish government plan to bring in equipment and manpower from Elayn Hunt Correctional Center in St. Gabriel for sandbagging.

Other local governments, such as in Ascension Parish, are taking a wait-and-see approach.

"Personnel and equipment are on standby if necessary," said Martin McConnell, parish government spokesman.

None of the parishes are expected to see key river crests for another two weeks or more.

Though levels will be well above flood stage by then, neither river will see levels that match 2011, when the Corps opened the Morganza Flood Control Structure northwest of Baton Rouge. The Corps has said the Mississippi won't reach required flows to trigger opening Morganza.

"We are not forecast to open Morganza under current conditions," said Heath Jones, chief of emergency management for the Corps' New Orleans District.

Rickey Boyett, Corps spokesman, added that though seepage areas have been spotted along the levees, they are appearing where they commonly happen and aren't showing signs of sediment that would indicate a weakening of the levee.

The Morganza Spillway structure in Pointe Coupee Parish and its overland floodway are an emergency relief system to protect the levees in the Baton Rouge-New Orleans corridor by funneling Mississippi River water to the Atchafalaya Basin. The Bonnet Carre, which is farther downstream on the Mississippi, protects New Orleans' levees by sending water overland to Lake Pontchartrain upriver of the city. 

Unlike the 2011 event, high water on the Red River is a big factor in the rising levels on the Mississippi this time, Jones said. The Corps tries to funnel the combined flow of the Mississippi and Red rivers through the Old River Control Structure, which is farther upriver from the Morganza and which diverts 30 percent of the combined Mississippi/Red rivers  to the Atchafalaya River.

In this case, half of the Atchafalaya's flow below Old River is from the Red River, meaning less of the Mississippi's upriver flow can be diverted to the Atchafalaya, Jones said.  

The Mississippi is forecast to crest at 42.5 feet in Baton Rouge on March 21, the fourth highest on record, the National Weather Service says. The Atchafalaya River is forecast to crest in Morgan City at 7.5 feet on March 23.

John Boudreaux, Assumption's homeland security director, said the Atchafalaya crest at Morgan City means his parish will see a slow rise in backwater so the parish has advised its residents to start preparations. The Atchafalaya reached a similar level last year, he said, leading to backwater that covered roads but did not get into homes.

Sheriff Falcon said the new sandbagging equipment fills 10,000 sand bags per day per machine. The parish had two Thursday with the people to work both. The equipment will be in Assumption two days this week and possible more days next week, Falcon said.

Follow David J. Mitchell on Twitter, @NewsieDave.