The woman was flown to Washington County Hospital, although her injuries did not appear to be life-threatening, Sgt. E.D. Anderson of the West Virginia State Police said.
A spokeswoman for Washington County Hospital said Monday afternoon that the woman was not listed in their records.
It is unclear why the woman fell and police were continuing to investigate the incident Monday, Anderson said.
Police had not had a chance to talk to the woman by late afternoon Monday because she was being treated, Anderson said.
It appears the woman fell from the center of the bridge between the span's two piers, James said. The water in that section of the river is about 6 feet deep, James said.
At least one eyewitness, who was on the C&O Canal towpath at the time, saw the woman fall, James said.
After the woman was taken to the Shepherdstown boat ramp, she was taken by ambulance to the Shepherdstown Fire Department on W.Va. 45, James said.
A helicopter flew the woman to the hospital from the fire department, James said.
The bridge carries Md. 34 traffic across the Potomac River. The bridge, which cost $15.6 million to build, opened in 2005 and replaced an aging span.
James said people have attempted to jump from the site in past years, but officials were able to talk them out of it.