FLOODWATCH: Corps moves to open Morganza Spillway

Deidre Cruse

The U. S. Army Corps of Engineers announced late Friday it will open the Morganza Spillway sometime this weekend to lower water levels in the Mississippi River and take pressure off its levee.

The decision Friday will lead to the first opening of the spillway in nearly 40 years.

A decision was made as water volume at Red River Landing neared 1.5 million cubic feet a second (cfs the “trigger point” for opening Morganza.  As of the Corps last reading, at 7 a.m. Friday, the Red River flow measured 1.449 million cfs.

Will Tyson, executive director of the Atchafalaya Basin Levee Board, told the POST/SOUTH predictions are the flow will reach 1.49 million cfs Saturday (May 14) and 1.52 million cfs on Sunday.

The Mississippi stood at 43.4 feet at 7 a.m. Friday, and still is expected to crest at 47.5 feet on Sunday, May 22, according to the National Weather Service River Forecast Center.

“We are hoping they are going to cut that crest elevation when they open Morganza,” Tyson said.

Estimations are that opening Morganza halfway would lower river levels at Baton Rouge by one to two feet.

Tyson said the levee board has finished shoring up a portion of the westbank levee near the Plaquemine Lock. The action was taken as a precaution when a survey showed the elevation there lower than expected.

Iberville Emergency Preparedness Director Laurie Doiron said the Ponchartrain Levee Board is expected to start Saturday building up a one and a quarter-mile stretch of eastbank levees with HESCO baskets – large sandbags of wire and mesh – as a precaution only from south of the LSU School of Veterinary Medicine to just north of Plauqemine Point in Iberville Parish.

The Ponchartrain board was supposed to do the work on Thursday, but was delayed, Doiron said.

There have been no breaches of any levee in Iberville Parish, the parish government reported this afternoon.

Opening the Morganza Spillway will expose southern Iberville Parish to backwater flooding. Some 200 camps and a few homes on the spillway side of the Atchafalaya Basin, outside the levee system, were voluntarily evacuated last weekend.

Parish officials said water could back up from Lake Palourde, Lake Verret areas to southern portions of Iberville, including Bayou Pigeon and Bayou Sorrel. The current water level in this area is 3.2. When the water level reaches 6 feet, waterway restrictions are initiated by the U.S. Coast Guard.

Otherwise, areas inside the Atchafalaya Basin levee system should be protected up to 33.8 to 34 feet, Doiron said, except at the Bayou Sorrel Lock. The lock is protected to a level of 24 feet and the Corps is adding five feet of additional protection there.

As of 7 a.m. today, the water level at the Sorrel lock stood at 10.4 feet and is expected to rise to 12.6 feet by Tuesday (May 17), according to the latest word from the National Weather Service.

The state Department of Transportation and Development (DOTD) has hauled some 200 cubic yards of sand to help stabilize the South Morganza Floodway guide levees. To date, DOTD has hauled 1,030 cubic yards of sand to help fight seepage that is starting to occur in the area, according to the governor's office.

Doiron reported the seepage here after a flyover of the area on Tuesday.

Iberville Environmental and Permits Manager John J. Clark has said if the Corps opens Morganza, the plans are to do it slowly, both to allow wildlife to escape the rising water and to protect the Old River Control Structure from a scouring action. In 1973, the only time Morganza has been opened, a scouring action from a quick opening almost took the Old River structure out.

The Old River Control Structure should hold up during this period of high water, Rachel Rodi, a spokeswoman for the Corps, assured the POST/SOUTH in a telephone interview earlier in the week.

The Old River facility was built to keep the Mississippi from changing its course into the Atchafalaya River. Itdiverts 30 percent of the water from the Mississippi into the Atchafalaya Basin and releases 70 percent into the Mississippi.

The two levee boards responsible for Iberville Parish have not yet banned foot traffic on levees, as was done yesterday in East and West Baton Rouge parishes, Doiron said,

“I have asked for restrictions placed on the levee,” she said.

Tyson said pedestrians could interfere with levee inspections and nigh patrols.

Vehicular traffic was banned earlier in the week.

The Iberville Sheriff's Office is continuing to help patrol the levee systems both to keep vehicular traffic away and to look for seepage and and other problems developing on the levees, Chief of Operations Aubrey St. Angelo said.

The Plaquemine Police began patrolling yesterday from The Dow Chemical Plant to south of E. J. Gay School, Mayor Mark A. “Tony” Gulotta said.

The parish government is posting flood information at ibervilleparish.com, and the state government has set up the emergency.louisiana.gov website.