Most wells in valley bottoms are adequate for a domestic supply. Yields to wells become progressively less on hillsides and ridges. Deep wells penetrating over 500 feet of sandstone may yield enough water for small municipal or industrial supplies. Water from drilled wells ranges from moderately to extremely hard and contains noticeable amounts of iron. In valley bottoms, salty water may be encountered at depths of 100 feet. Springs commonly issue from the base of sandstone and limestone formations in valley bottoms. A few springs supply enough water for domestic use. Most springs have large seasonal variations in flow.