Recent flooding has cut off access to the historic site of a town lost when Lake Mead was filled.
The National Park Service has closed the dirt road leading to St. Thomas until further notice.
Storm damage has left the road 60 miles northwest of Las Vegas impassable. Kevin Turner, spokesman for Lake Mead National recreation Area, said rushing water carved ruts several feet across in some places.
The dirt road, known as Approved Road 109, runs east toward Lake Mead from the intersection of Northshore Road and the highway through Valley of Fire State Park. The road ends at the trail head for a path that leads down to the site where the town of St. Thomas stood before it was swallowed by the lake in 1938.
Turner said it is unclear how long the road will remain closed.