The Shenandoah was expected to begin receding overnight, Wiesmueller said.
The Potomac River measured 17.2 feet shortly after 7 p.m. Friday, Wiesmueller said.
Streams were swollen after up to three inches of rain fell on parts of the area Thursday. No rain was forecast for the weekend and only light precipitation was predicted for Monday - not enough to get the rivers on the rise again, Wiesmueller said.
With the rivers up and running rapid, officials warned recreational boaters to stay off the water until the rivers reached a safe level.
"It's so unpredictable. These are dangerous waters down there," said Friendship Fire Chief Steve Hough.
Boaters who get into trouble in the high water endanger not only themselves, but also those who have to rescue them, Hough said.
"It makes it more difficult for us and any other surrounding departments," Hough said.
Water rescues are dangerous even when the rivers are at their safest levels, Hough said.
The rescues also put the fire company's boats at risk of damage.
The fire company frequently relies on Maryland State Police helicopters for assistance in river rescues, so those crews also are put in danger, he said. They frequently have to navigate around power lines and other obstacles.
"My hat's off to the Maryland State Police helicopter people. They make rescues when I think no one can get to the people," Hough said.
The majority of kayakers are well-trained and have actually helped the fire department make rescues in the past, but Hough said even experienced kayakers have had to be rescued after injuring themselves.
"I wouldn't want to be out there, but that seems to be their favorite time out there," Hough said.
The high, rapid water is not the only danger on the rivers, he said.
The high water will have more debris in it, from tree trunks to propane fuel tanks, Hough said.
"You may not be able to navigate out of its way," he said.
Meanwhile, the Maryland Natural Resources Police Friday extended the hazardous advisory on the Upper Potomac River due to recent flood warnings.
Specific areas include the Potomac River at Shepherdstown, W.Va., Point of Rocks, Md., the Monocacy River near Frederick, Md., and the Shenandoah River at Millville, W.Va.
Officers said boating and other recreational uses of the Upper Potomac River watershed should be avoided.