Arizona Department of Transportation engineers are monitoring two slopes adjacent to southbound Interstate 17 between Sunset Point and Black Canyon City for potential rock slides.
Heavy rains over the past month have saturated the slopes and increased the potential of rocks falling onto the roadway.
ADOT crews and equipment were on site Thursday and engineers are assessing the slopes to determine the steps needed to maintain safety on the vital route between Flagstaff and metro Phoenix.
ADOT crews are prepared to immediately close the southbound lanes if conditions warrant.
A landslide could require closure of both southbound I-17 lanes and take up to seven hours to clear. Northbound I-17 is so far unaffected.
Drivers are urged to call 5-1-1 before traveling on I-17 southbound through the area to avoid unexpected delays or detours.