The typical subsurface water condition was illustrated by measurements in boring 13. There, the colluvium was not saturated. Free water was first encountered in the first limestone bed under the colluvium that was penetrated by drilling. This water was under artesian pressure and responded to an annual cycle of maximum pressure in the late spring and minimum pressure in the early fall (fig. 12). In those parts of the landslide that extend nearly to the contact between bedrock and colluvium (that is, the head region), the artesian pressures could significantly reduce stability. Most of the toes of the thick landslides are entirely within the colluvium and significantly removed from the bedrock containing artesian water. The effect of the artesian pressure is dissipated a short distance from the contact between bedrock and colluvium (R.L. Baum, U.S. Geological Survey, oral commun., 1985).