Despite the massive flooding that struck south Louisiana in August, prospects for a decades-old project aimed at protecting homes in the future remain as murky as ever.

The planned 12-mile structure, called the Comite River Diversion Canal, would siphon high water from the Comite River, sending it instead to the Mississippi River. The Comite is a tributary of the Amite River.

Had it been in place in August, officials said, the number of damaged and destroyed homes in the Baton Rouge area could have been trimmed by about 25 percent.

But the proposal, which was first authorized in the early 1990s, remains stuck on the launchpad, even as hundreds of millions of federal dollars pour into the state after tens of thousands of homes, businesses and other structures were inundated.

U.S. Sen. Bill Cassidy, R-Baton Rouge, and other top state officials say the U.S. Army Corps of Engineers is the main stumbling block. Corps officials say lack of money is the chief impediment.

The bottom line is that the project shows little hope of moving forward, at least for now.

The Obama administration has opted not to include money for the canal in its requests to Congress for flood relief, dashing the hopes of Cassidy and others.

Major legislation just passed by Congress — called the Water Infrastructure Improvements for the Nation Act — did not include money for the work despite signs in September that it might happen.

And an arcane formula used by the Corps of Engineers to determine the value of such projects nationally continues to be a major question mark.

Cassidy said the all-important formula — called the cost-benefit ratio — has to change to get the canal moving.

"The original benefit/cost was not that great," he said. "But so much has changed since that was done."

Bobby Duplantier, the Corps' senior project manager on the Comite Diversion, said the key issue is dollars, not better results from the formula. "It is one of those projects that need federal funding, and we cannot predict what is going to get funded and what isn't going to get funded," Duplantier said.

"That is the biggest driver right now, getting additional dollars on the project," he said.

The canal would run from the Comite River to the Mississippi River, between Baker and Zachary.

The work would include construction of five bridges across the east-west canal, dredging and compensating for the environment impact of the project.

The price tag is modest by state and federal government standards: $245 million.

The work is about 20 percent done, and another $150 million is needed, Duplantier said.

However, the fact the plan has to navigate the often byzantine path through the Corps of Engineers approval process and also land federal, state and local dollars makes it impossible to say when it could become reality.

Cassidy said the key is getting an improved cost-benefit ratio from the Corps. The ratio is supposed to compare the price of future flood damage to the cost of the project.

Already underway is a preliminary review to see whether there are ways to cut the project's costs and increase its benefits.

"At the end of the study, if we find cost-cutting measures, that will drive us to re-evaluate the cost-benefit ratio," Duplantier said.

That initial review is mostly done, and results are expected to be released next month.

U.S. Rep. Garret Graves, R-Baton Rouge, said it is easy to pinpoint the chief hurdle to building the canal. "It is the Corps of Engineers," he said.

Graves said plans across south Louisiana have been awaiting action by the Corps for years.

"I can tell you projects that have been sitting around for decades," he said. "You can go anywhere and you see projects that the Corps of Engineers has just been sitting on."

Ironically, the push for a Comite River Diversion Canal stemmed from concerns after a previous "historic flood," this one in 1983.

Some residents of East Baton, Ascension and Livingston parishes have been paying property taxes for the plan since 2001, about $25 million so far.

Cassidy said state officials hoped President Barack Obama would direct the Corps to do the project as part of federally funded recovery efforts, noting there is precedent for such action after Superstorm Sandy in 2012.

"And it didn't happen, so that is the president's call," he said. "It was disappointing."

Asked if President-elect Donald Trump's ascension to power next month would make a difference, Cassidy said, "Even though we have a new president, I think it is still incumbent on us to go through the process with the Corps."

U.S. House Majority Whip Steve Scalise, R-Metairie, said earlier this month that he hasn't given up on the project, and many are still interested in trying to get it greenlighted.

Political questions are also swirling around the proposal.

Graves said that, despite a request from the state Department  of Transportation and Development, Gov. John Bel Edwards did not include money for the project in his capital improvements request to the Legislature this year.

"It is notable that the executive outlay budget, and HB2, does not contain any funds in any priority for the CRDC," Graves said in a letter to the governor dated May 11, three months before the south Louisiana flood.

The Republican said the absence of such a request "gives the impression that the state is not committed to the project."

In an email response to questions, the Governor's Office said Graves is mistaken.

Less than two weeks after Graves' letter, the Edwards administration submitted an amendment to a key Senate committee requesting two batches of money for the project in the capital outlay bill — $15 million and $72 million.

It eventually won final approval.

"But the project cannot move forward until federal dollars, which have been requested, become available," wrote Shauna Sanford, Edwards' press secretary.

In addition, Edwards made two requests to Obama — Oct. 20 and Aug. 23 — asking that the president allocate $125 million to the Corps of Engineers for the Comite Diversion.

"While this project is certainly not a silver bullet for the flooding issues in the Comite and Amite River Basins, I believe it is an important part of the solution," the governor said in his October letter.

State Sen. Bodi White, R-Central, whose district includes the project site and who was involved in this year's push for state dollars, said he was helped by Shawn Wilson, secretary of the state Department of Transportation and Development and an Edwards lieutenant.

Wilson, Cassidy and Graves claim — and White has said in the past — that federal officials are the holdup and the state will come up with any needed matching dollars.

"As you know, we have been working in this project for some time as the federal government has not provided Corps funding necessary to complete the project," Wilson wrote in an email.

"We have been supporting the governor in his federal request for full funding through the Corps," he said.

Follow Will Sentell on Twitter, @WillSentell.