There once was a creek running through the St. Paul land where Henry Ford built his Twin Cities Assembly Plant. For decades, that water has run underground through a system of storm sewers that expelled it into the Mississippi River.

The stream could see daylight again.

Of the redevelopment ideas that Ryan Cos. has floated for the 122-acre site, resurrecting that old stream to once again send water flowing over Hidden Falls has proved perhaps the most popular among neighbors, business owners and city officials.

Not only would a renewed Hidden Falls Creek and its adjacent green space boost demand for housing along its route through the site, it would provide a more elegant way to gather and clean stormwater before sending it over a revived Hidden Falls into the Mississippi.

“I think, as far as the timelessness of the place and the pieces that will last and become memories, that is going to be it,” said Mike Ryan, market leader for Ryan’s North Region. “That is what people are going to remember from this place. Long after each of the buildings are done.”

The project is exciting to city officials because it has multiple benefits. It will restore the creek and provide more consistent flow to Hidden Falls, said Wes Saunders-Pearce, St. Paul’s water resource coordinator. It will also reintroduce area residents to the Mississippi River.

“We know we have a new neighborhood and how do we allow the existing neighbors and new neighbors to physically connect with the river as a resource?” he asked. “This is so powerful, because it’s also a way to have people reconnect with the urban ecosystem and the downstream river.”

More than 100 projects a year in St. Paul require stormwater management, Saunders-Pearce said. Most of the time, that means gathering stormwater underground in sewers or in holding tanks beneath parking lots.

Then Ford announced plans to cease operations in the city, prompting a decade of discussions over what would replace it. Against that backdrop, officials began exploring ways to treat stormwater differently. A 2010 plan by the Capitol Region Watershed District explored bringing a number of St. Paul’s historic old streams and creeks back to the surface, including recreating the stream at the Ford site, said Bob Fossum, manager of the district’s monitoring and research division.

They approached city officials about including a restored creek with the city’s master plan for the Ford site. Since then, images of what an “unhidden” Hidden Falls Creek could look like has elicited mostly rave reactions — even from Ford site neighbors who cringe at city leaders’ desire for greater housing density. Ryan Cos., which was chosen by Ford to develop the site, has taken the baton.

“We are quite excited to see this moving to the next phase,” Fossum said of his group’s continuing work with the city and Ryan Cos. “We’re all rolling up our sleeves and moving to the nitty-gritty of the engineering.”

Ford, which ceased operations in 2011, removed the underground storm sewer pipes that had been in place for more than 80 years. The site now drains into a temporary sedimentation basin that empties through a pipe under Mississippi River Boulevard.

For decades, heavy rains have sent muddy water gushing down the falls, carrying tons of sediment to the Mississippi. One benefit to an aboveground stream will be a more natural, sustained and gentle flow of water over the falls, officials said.

The feature, which would probably begin in a plaza near Ford Parkway, would meander for six or seven blocks south toward Hidden Falls along a corridor of green space as wide as downtown’s Rice Park. Preliminary renderings show ice skaters crisscrossing the stream in winter, kayakers or paddle boarders rollicking in summer. Runners, walkers and cyclists are expected to flock to encircling trails year-round.

A Ford site team including civil engineers, landscape designers and water consultants meets every Monday morning, Ryan said. “We have a long way to go on the engineering,” he said. “But it should be a beneficial feature for all to enjoy.”

How much it will cost and who will pay for it are still undetermined. In 2016, the city established a special property tax status for an area that includes the Ford site, called a tax-increment financing (TIF) district. Ryan acknowledged that the developer is discussing using some of that tax money to help pay for what the company calls “horizontal development” — infrastructure like streets, sewer and water. A stormwater stream that feeds Hidden Falls would be a critical component, he said.

Hannah Burchill, a spokeswoman for St. Paul Planning and Economic Development, said, “No financing, TIF or otherwise, has been guaranteed to Ryan as of yet. This will be part of the development agreement, which we are still in the process of finalizing with Ryan.”

But both Ryan and city officials acknowledge that if a water feature is chosen, it will need to be among the first things built at the site because of the complexity of the engineering and its importance to the development’s environmental amenities.

“In my opinion, the water feature is key to helping the whole site feel like a place you’d want to live in the early years of the development,” Ryan said. “You need people to come early to have the dominoes start to fall.”