A 206-year-old bridge that has been a treat for curiosity seekers since it emerged because of unusually low water levels at Youghiogheny River Lake is being closed to the public because of safety concerns.

The U.S. Army Corps of Engineers Pittsburgh District is restricting access to the Great Crossings Bridge, citing unknown bridge stability. A lack of recent rainfall that has led to drought conditions across the state also made the bridge visible and briefly accessible to the public.

The district does not maintain the bridge and cannot guarantee its structural integrity. District staff posted signs and a barrier to identify the area closed to the public. Visitors are advised not to boat or travel underneath the bridge.

Some areas near the bridge remain open to visitors.

The bridge, opened on July 4, 1818. It is made of cut sandstone and once carried Route 40 over the Yough River between Somerset and Fayette counties. Just upstream from the modern version of the highway and its much higher bridge, the Great Crossings span periodically emerges from the depths when dry weather causes low water levels in the man-made lake.

“The district understands the enthusiasm surrounding this rare opportunity to view a piece of history that seldom emerges from the lake,” said Col. Nicholas Melin, commander of the Pittsburgh District. “However, the safety of our visitors is our top priority. Given the bridge’s uncertain structural integrity, we have made the decision to restrict access to the bridge.”

In addition to structural concerns, the colder water temperatures present potential risks for visitors. The public is discouraged from removing any materials from or near the bridge, as doing so may increase risk to the bridge’s stability and public safety.

“Thousands of people have come to visit the bridge and their response has been overwhelmingly positive,” said Vince Klinkner, the supervisory natural resource manager at Youghiogheny River Lake. “Our primary concern is the well-being of the public and we want to ensure visitors continue having a great experience when they visit the lake.”

The Army Corps oversees the 6-mile-long lake and the dam near Confluence that created it in 1943 as part of a federal flood control program.