NEW ORLEANS -- The controversial Mississippi River Gulf Outlet is now closed to ships and boats at Bayou La Loutre near Hopedale about 30 miles southeast of New Orleans.

"It's a dog gone good day," said Carlton Dufrechou, the Executive Director of the Lake Pontchartrain Basin Foundation.

The MRGO was supposed to be a shortcut between the Gulf of Mexico and the New Orleans inner harbor.

But, Dufrechou says for nearly 50 years, it's been an environmental disaster.

"It's been the cancer in the coast that has progressively, day in and day out, added to the disappearance and the demise of our coastal wetlands," said Dufrechou.

During Hurricane Katrina, the MRGO acted as a funnel for the gulf storm surge that flooded St. Bernard Parish and parts of New Orleans.

"The dynamics of this waterway has been destructive not only in terms of bringing water in, in terms of surges, but also the salt water intrusion has destroyed thousands and thousands of acres of wetlands and estuaries," said St. Bernard Parish President Craig Taffaro.

After Katrina the Army Corps of Engineers agreed to close the MRGO.

Construction of a rock structure, from bank to bank is now underway.

Wednesday, the Army Corps officially shut down the channel.

"We're about 60 percent done and we're at a point now where we have submerged rocks in the channel that are a hazard for folks that may be used to traveling through the area," said Army Corps Project Manager Greg Miller.

Local fisherman say diverting boat traffic to smaller bayous in the area will also be a hazardous.

"You have hundreds of boats on any Saturday, Sunday in May, June and July," said fishing guide Capt. Jeff Farber. "That's going to crowd it and cramp it and it's going to create problems."

The Army Corps is quick to point out, the closure alone will do little to improve hurricane protection.

"The closure structure is strictly a navigation closure," said Miller. "It's not a hurricane surge barrier. It doesn't tie into any levee system."

Closing the MRGO channel is only one step of many needed to restore a healthy marsh ecosystem. That process could take decades to complete.

The plug is significant in itself, but the bottom line is we got to get out there and restore the coast," said Dufrechou. "That is the lion share of the work to come."

One option is to eventually fill in the MRGO.

The Army Corps says it is currently studying the best way to do that.