The National Park Service's recovery efforts for two construction barges that got loose on the Potomac River over the weekend now includes equipment that fell off at least one barge.

Equipment, including a small excavator, that was atop the smaller of two construction barges hung up in the Potomac River had fallen off the barge by Tuesday morning, a National Park Service spokeswoman said.

Part of what has been holding the smaller barge in place below Dam No. 4 was water pressure from water coming over the dam, said Christiana Hanson, spokeswoman with the Chesapeake & Ohio Canal National Historical Park. That also meant the barge was bouncing around a lot, she said.

The Flexifloat modular barge, or work platform, was one of two a National Park Service contractor was using for work at McMahons Mill and a stretch of the canal towpath, southwest of Downsville. The barges came loose from their moorings during the weekend and floated down the river on Sunday.

The larger barge was still hung up early Tuesday on the remnants of Dam No. 3 near Harpers Ferry, W.Va., and more than a mile west of the U.S. 340 bridge. The smaller barge remained hung up just below Dam. No. 4.

Officials suspect the materials from the smaller barge sunk right at Dam No. 4, Hanson said.

The equipment that fell off the barge includes the excavator that is similar in size to a Gator ATV but with an extension arm, Hanson said. Also on the barge were sacks of sand, lime and cement pallets, a mortar mixer, a variety of hand tools and a 20-foot gangway that workers used to access the work platform from the shore.

Part of the recovery effort will be retrieving that equipment, Hanson said.

Still atop the barge was a generator for spuds, which are large stakes being used to help hold the barge in place, Hanson said. The generator was being held onto the deck by hydraulic hoses.

Hanson said the park service is coordinating with the Maryland Department of the Environment in case of potential spills. It's believed the excavator's fuel tank was not full. A minimal impact is expected, but the park service wants to do its due diligence, she said.

There is less concern about the lime and cement, which would have come into contact with river water once they had been used to restore the historic stone retaining wall at McMahons Mill, Hanson said.

Officials are working on getting a detailed inventory from the contractors regarding the equipment atop the larger barge, Hanson said. As of Monday morning, it looked like all the major items were still atop that barge, including a large excavator and crane mats, she said.

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Efforts to recover the two construction barges are expected to take weeks, according to an emailed update late Monday from Hanson.

Hanson said Tuesday that the contractor, Kiewit Corp., has two boats on standby near Dam No. 4 so they're ready when the smaller barge comes loose.

"I would anticipate some folks getting a pretty nice view of us basically lassoing it to pull it to a boat dock," Hanson said.

That smaller barge could come loose today or in a week, depending on when the river water pressure lessens, Hanson said.

The construction barges are not navigable boats in the sense they can't be self-steered. Other boats pull them into place, Hanson said.

Park service officials are asking people to stay away from the two construction barges, Hanson said.

Conditions could change at any minute so don't get too close to the barges or try to climb aboard them, Hanson said. Park service officials want to make sure the public stays safe while officials work on recovering the work platforms.

The park service hasn't yet been able to complete damage assessments because river level is still high, Hanson wrote Monday. Once it's safe, park service and contractor staff will assess the various areas the barges "impacted" along the river, Hanson wrote in the email.

Dam No. 4, which both barges went over during the weekend, is one of the structures that needs to be inspected.