The Sivas-Erzincan highway, a major thoroughfare in Turkey, has been adversely impacted for years by landslides in the Kızıldag region, resulting in high maintenance costs with time. This article illustrates slope stability problems in clay because of the seasonal effects on the groundwater regime. Clays in the study area act like a fluid and have very low strength parameters when they were saturated with water. Within the landslide debris, the clays are characterized as highly plastic and have a high swelling potential because of the presence of smectite. A factor of safety of 0.89 was calculated during high-precipitation seasons, and a factor of safety of 4.57 was calculated during dry seasons. The stable slope angle was calculated as critically I ≤ 10°. The only certain solutions to minimize landslide hazards along the highway are to control groundwater levels and surface run-off and to change the grade of slope, buttresses at the toe of the slopes, in lieu of relocating the highway on an alternative route.