Much has surfaced in the Scioto River since workers removed the Main Street dam late last year and the water level began to drop. There's the good: more than 4,500 mussels, including a threatened species, which were moved upstream to deeper, safer waters. There's the bad: tons of sediment that choked the river and kept it from flowing naturally. And there's the weird: about 50 shopping carts.

Much has surfaced in the Scioto River since workers removed the Main Street dam late last year and the water level began to drop.

There�s the good: more than 4,500 mussels, including a threatened species, which were moved upstream to deeper, safer waters.

There�s the bad: tons of sediment that choked the river and kept it from flowing naturally.

And there�s the weird: about 50 shopping carts.

Eight earthmoving machines are digging and pushing sediment around the site in this early, muddy phase of Scioto Greenways, the two-year project to reshape the river, make it cleaner and add about 33 acres of parkland along its edge by the end of 2015.

The project, which will cost about $35 million, is funded by the Columbus Downtown Development Corp., which is leading the work; state grants; and money from Columbus, Franklin County, the Mid-Ohio Regional Planning Commission, Metro Parks, the Columbus Foundation and Battelle.

Guy Worley, president of Columbus Downtown Development Corp., said this project, like the Scioto Mile and Columbus Commons projects before it, will help drive economic development Downtown and is another step in the larger redevelopment planned for the Scioto Peninsula.

But before crews could do any work in the river, planners needed approval from the U.S. Army Corps of Engineers. October�s federal government shutdown slowed the permit process by about six weeks.

In late November and early December, as the dam came down, the river�s water level dropped about7 feet. An environmental survey had determined that 10 species of mussel would be exposed and in danger.

The project�s environmental consulting firm, Stantec, led a team of workers and volunteers who plucked the mussels from the riverbed and transported them to a site along the Olentangy River near 5th Avenue, where a dam had been removed in 2012.

The team had to remove all of the mussels before the last step of the dam�s removal. And it had to compete with the weather � the air temperature had to be above freezing for the mussels to survive the trip.

The rescue was required by the Ohio Department of Natural Resources, which helped with the move.

�They�ll come back naturally and repopulate this section of the river when the work is done,� said Amy Taylor, chief operating officer of the Columbus Downtown Development Corp.

>> View a video of the river restoration work

Right now, crews are digging and moving sediment beneath the water to create alternating shallow riffles and deep pools from just north of North Bank Park to about 800 feet south of the Main Street bridge.

Reshaping this section will restore the river to its natural course. The dam had caused sediment to pile up, leveling out the river bottom.

�It isn�t a real river,� said Keith Myers, a project consultant. �It�s a big sedimentation basin right Downtown.�

Crews have excavated more than 36,000 cubic yards of sediment, dirt and rocks, which were added to the riverbanks. They�ve imported more than 120,000 cubic yards of additional dirt to build up the riverbanks.

Trucks are making 200 to 400 trips every day, bringing more dirt to the site, Taylor said. The project requires a total of 430,000 cubic yards, about enough to fill 215 Olympic-size swimming pools.

�We are doing in two years what it would take Mother Nature a generation to do,� Taylor said.

Excavating the river has led to surprising finds, Worley said. In addition to trash, tires and shopping carts, workers have discovered old bridge infrastructure and historic building foundations. Workers have to remove remnants from three old bridges, including pieces from a Mound Street bridge that had been torn down in the 1930s.

�We didn�t even know there was a Mound Street bridge,� Worley said. �There�s a lot of learning in a project like this because you couldn�t see underneath the water.�

Near the Broad Street bridge, passers-by can see foundations of buildings that once housed the Columbus Electric Light and Power Co. � one of Columbus� first power plants � and an old buggy works.

Next spring, crews will begin building 1.5 miles of new bike and multiuse paths. Finally, they�l l add about 800 trees and plants along the river�s edge.

Across the country, dam-removal and river-restoration projects have been shown to encourage investment and improve communities, said Bryon Ringley, senior principal at Stantec.

The Scioto project is even more of a challenge, Myers said, because of its high-profile urban setting.

�It�s been almost a century since the river was addressed this holistically,� he said. �It�s a big moment right now in Columbus� history and our relationship with the river.�

jwhite@dispatch.com