All buildings must be set back from washes so that they will be protected from erosion and lateral migration of the channel. Pinal County requires a minimum setback of 50ft from a wash. In some cases, very large washes will require a 300ft setback. The setback is measured from the bank of the wash. Setbacks can be reduced if a Registered Professional Engineer determines that a lesser setback will be safe or provides a design for bank protection for the wash.