DONALDSONVILLE – The project to replace an earthen levee with steel spans across Bayou Lafourche will provide more than just another way for railroad cars to move across the waterway.

The new Union Pacific bridge eliminates the biggest obstacle to getting more fresh water from the Mississippi River into Bayou Lafourche. For decades, river water could only pass into the bayou through two culverts in the earthen levee where the railroad tracks once ran. 

"It is a tremendous historic achievement for us to have this bridge put into place," said Hugh Caffery, chairman of the Bayou Lafourche Fresh Water District, created by the state in the 1950s to preserve the bayou. 

The goal of the bridge project and others, like dredging work completed in the bayou this year, is to increase the fresh water flow rate into the bayou from the current rate of 400 cubic feet per second to approximately 1,000 cubic feet per second, Caffery said. A new pumping station planned for the future will also help meet that goal.

"Studies over the last 30 years have shown we need to have more fresh water in Bayou Lafourche," Caffery said Friday, as he gathered with other officials and local residents to see the bridge put into place.

A growing population in the region makes it essential, he said. The bayou is the only fresh water supply for drinking water for more than 300,000 residents and businesses in Ascension, Assumption, Lafourche and Terrebonne parishes, and it nurtures the wetlands, as well.

New railroad tracks will be laid on the bridge on Saturday and rail service, which was suspended through Donaldsonville beginning Wednesday night, also will resume on Saturday.

Thought about for more than 20 years, taken up and put back down again, the project to get more river water into the bayou gained steam in 2014 when state and local officials and congressional and local legislators helped the Fresh Water District members meet with Union Pacific officials at the railroad's Nebraska headquarters.

The meeting resulted in an agreement to design an open span bridge for the railroad crossing at the bayou that would meet the needs of both the water district and the railroad, said Ben Malbrough, director of the Bayou Lafourche Fresh Water District. 

"It was the perfect timing," Malbrough said. "Union Pacific agreed to work hand in hand with us." 

The $31 million cost of the entire project is funded by a grant through the state's Coastal Protection and Restoration Authority, as part of a coastal impact program administered by the U.S. Department of Interior.

"We're eight hours ahead of schedule," Brett Meaux, manager of structural projects for the southern region, for Union Pacific, said at about noon Friday, as he watched the work on the bridge.

Meaux said that work on the project, begun earlier this year, included the driving of a total of 45 steel pilings to support the bridge at each end. 

Bayou Lafourche, which flows southward from the Mississippi for 100 miles from Donaldsonville to Fourchon, has a number of twists and turns in its tale.

Union Pacific had a turnstile railroad bridge in Donaldsonville dating back to 1873 that was replaced by the railroad company in the early 1930s with tracks that ran across a levee it built, with a single culvert to let river water into the bayou.

Then in 1904, the state dammed up the bayou — not far north of the railroad tracks — with plans to put locks there.

The locks project ended up going elsewhere, and the bayou remained cut off from the Mississippi.

In the 1950s, officials began to recognize the needed to reintroduce river water into the bayou. A pumping station was built to bring in river water,  and two large culverts were built in the levee where the railroad ran.

In the 1980s and 1990s, there began an even bigger push to bring more Mississippi water into the bayou, for coastal restoration, Marlbrough said. 

In addition to the primary goals of providing drinking water and replenishing the wetlands, the newly opened bayou will be a boon for the Donaldsonville community, as well.

The city has a plan to one day offer tours on the bayou, for instance.

"It's definitely a historic event," Mayor Leroy Sullivan said Friday. "All of it is just coming together. It's very exciting."

"Hopefully, we'll continue to beautify Bayou Lafourche. It'll be a great attraction" for residents and visitors, he said.

Members of the Bayou Rowing Association, based in Thibodaux, are thrilled with the new, unimpeded access to the bayou, said rowing coaches Henry and Hattie Templet, also at the new bridge Friday.

Cindy Guion,  executive director of the Friends of Bayou Lafourche, which is working to create recreational and beautification opportunities along the bayou, said, "I'm really excited about what this will do for the community."  

"As a former canoer, I may get in the water myself," she added.

Follow Ellyn Couvillion on Twitter, @EllynCouvillion.