The U.S. Coast Guard on Saturday reopened a portion of the Tennessee River after a cargo boat struck and collapsed a section of a Kentucky bridge at the western entrance to Land Between the Lakes National Recreation Area.

A news release from the Coast Guard said the navigable channel is safe for commercial traffic, with no obstructions or debris. However, the agency continues to maintain a safety zone from mile marker 41 to mile marker 43, on either side of the bridge, where recreational traffic is not allowed.

Meanwhile, the bridge at US 68 and Kentucky 80 remains indefinitely closed to car traffic after the Delta Mariner knocked out a 322-foot span on Thursday night.

The five-story-high cargo boat was carrying space rocket parts for NASA and the Air Force.

According to the Kentucky Transportation Cabinet, inspectors conducting an emergency examination of the bridge's piers and remaining truss spans have found indications that a pier was pulled out of position.

Divers next week will place sensors on the pier on the eastern edge of the impact area. It will take a few weeks to collect and analyze the data.

"We have to know for certain whether the pier has been shifted, and if so, whether it is still moving," Transportation Secretary Mike Hancock said in a Saturday statement. "That will have a huge influence on our decisions as we weigh the options for restoring traffic on U.S. 68 and KY 80."

Gov. Steve Beshear has promised speedy work to replace the damaged 1930's-era bridge. It already was in the process of being replaced and preconstruction work began months ago.

The two-lane bridge, which connects Trigg and Marshall counties, handles about 2,800 vehicles daily. Drivers face a detour of dozens of miles while it is out.

The Delta Mariner was traveling on the Tennessee River on its typical route from Decatur, Ala., to Cape Canaveral Air Force Station in Florida when it was unable to pass under shorter spans of the bridge and collided with the structure. No injuries were reported on the bridge or boat, although the ship was covered in twisted steel and chunks of asphalt from the bridge.

Coast Guard Lt. Ron Easley said the investigation into the cause of the crash is ongoing.

Suzanne Lagoni, a spokeswoman for the ship's owner and operator, Foss Maritime of Seattle, said the boat was not severely damaged. Although it is not moving, the crew remains onboard, carrying out their regular duties.