DONALDSONVILLE - In December, the Mississippi River began flowing into Bayou Lafourche faster than it has for the last half century, thanks in part to the $4.8 million transformation of a railroad crossing over the bayou. 

The project was first talked about some 30 years ago, but finally started coming together in 2014 through the cooperative efforts of federal, state and local officials and Union Pacific Railroad.

"What was built first was a 'bridge' of people," said Hugh Caffery, chairman of the Bayou Lafourche Fresh Water District, at a symbolic ribbon-cutting Tuesday next to the bayou and the Union Pacific railroad bridge that now crosses it in Donaldsonville.

"I am thrilled to be part of a 30-year, overnight success," Caffery said of the long-awaited project. 

Since the 1950s, the Mississippi River has been pumped into Bayou Lafourche — the only fresh water supply for drinking water for more than 300,000 residents in four parishes — through two culverts set in an earthen dam topped by a Union Pacific railroad track. 

Removing the dam and its culverts became one of the critical components in a $31 million plan to bring more freshwater into the bayou, not only to increase the region's drinking water supply but to nurture the wetlands.

Other components, several completed, include dredging the bayou, which runs 100 miles from Donaldsonville to Port Fourchon on the Gulf of Mexico, and building a salinity control structure in Lockport, to prevent saltwater intrusion coming up the bayou.   

"It ends up helping hundreds of thousands of people with the drinking water and the wetlands all the way down to the Gulf," said U.S. Rep. Garret Graves, who was at the ribbon-cutting Tuesday.  

Graves, when he chaired the state's Coastal Protection and Restoration Authority from 2008-2014, allocated the original funds for the massive Bayou Lafourche freshwater project, as part of a coastal impact program administered by the U.S. Department of Interior.

In Donaldsonville late last year, the tracks at the bayou were closed for about 40 hours over the Thanksgiving weekend while Union Pacific employees removed the old tracks, put down steel spans and new tracks, and drove 45 steel pilings to support the bridge at each end.

In December, railroad employees removed much of the earth around the pilings, along with the two culverts, shaped up the embankments on either side of the bayou and reinforced them with chunks of concrete, called rip-rap.  

A new pumping station, now in engineering and design work, will help increase the freshwater flow from the Mississippi into the bayou to 1,000 cubic feet per second, an increase from the 400 cubic feet per second prior to the opening of the train crossing.

"We've been building America for more than 150 years," Brenda Mainwaring, vice-president of public affairs for Union Pacific Railroad, said Tuesday.

As part of that work, the railroad's mission is to be collaborative with "the communities we're in," Mainwaring said.

She thanked those in attendance for giving Union Pacific the opportunity "to return this watershed to what it originally was." 

"Wow, what a difference a bridge makes," Donaldsonville Mayor Leroy Sullivan said Tuesday. "It is wonderful. It's exciting."

He said the city planned to develop the land along the bayou as a place where people can take out canoes and paddleboats and enjoy fishing.

The bayou, he said, "starts right here." 

Follow Ellyn Couvillion on Twitter, @EllynCouvillion.