(1) The worst case scenario shall govern for determining the hazard classification of dams in series where more than one mode of failure is possible among the dams. Classification shall be based on potential for failure under combined and, if applicable, individual dam breach scenarios.

(2) If an upstream dam has the capability to create failure in a downstream high-hazard dam because of its failure flood wave, the upstream dam must be classified as a high-hazard dam.

(3) If the failure flood wave of the upstream dam will cause failure of the downstream dam, and the combined flows will likely cause a loss of life, the upstream dam must be classified as a high-hazard dam.