A fleet of boats built by students and used by the public at Bartram’s Garden sustained significant damages and losses during Thursday’s drenching, violent storm that created an unexpectedly high river flow on the Schuylkill.

River flow rates rose to about 50,000 cubic feet per second, according to a USGS gauge. By Friday, the flow was down to 14,000 cfs.

As a result of the damage and rapid flow, free boating offered for Saturday is cancelled. River flow should be under 9,000 cubic feet per second for safe use of the Bartram’s Garden boats.

Danielle Redden, river programs manager at Bartram’s Garden, said about 16 boats were in a shallow harbor that’s normally safe. The wooden skiffs, about 11 feet long, are built by students at Richard Allen Preparatory Charter School and Girard College.

About six boats are still missing after becoming unmoored and three could be damaged beyond repair, but still have to be assessed.

The U.S. Army Corps of Engineers helped find and retrieve about 10 boats altogether, including the damaged ones.

The boats were built during the winter. Volunteers help run a program for the public to use the boats.

Bartram staff said the loss and damage are unusual. However, last year’s heavy rains caused some issues and staff believe they had done a better job this year at securing the boats.

“We worked through the winter, problem-solving to make sure they were more secure,” Redden said.

But the volume of water, fed by massive rain upstream within the Schuylkill River watershed, proved to be simply too much, she said. As of Friday, the currents were still too strong for boating.

For now, it appears the free boating offered for Tuesday should be available, but for kayaks only — no rowboats.

Thursday’s storm contributed to the deaths of three people — including two young children — in Southeastern Pennsylvania and spawned a tornado in South Jersey.

Nearly 8 inches of rain fell in Reading during the storm, while Philadelphia recorded 1.36 inches of rainfall, according to the National Weather Service.