Adapted from FEMA 333: Hazard Potential Classification System for Dams. The hazard potential classification system for dams is based on the probable loss of human life and the potential for economic losses, environmental damage, and/or disruption to lifelines caused by failure or mis-operation of a dam or its appurtenances. The hazard potential classification assigned to a dam is based on consideration of the effects of a failure or mis-operation during both normal and flood flow conditions. The classification should be based on the worst-case probable scenario of failure or mis-operation of the dam. A primary purpose of any classification system is to select appropriate design criteria. In other words, design criteria will become more conservative as the potential for loss of life and/or property damage increases.
Three classification levels are adopted as follows: LOW, SIGNIFICANT, and HIGH, listed in order of increasing adverse consequences. This hazard potential classification system should be utilized with the understanding that the failure of any dam or water-retaining structure, no matter how small, could represent a danger to downstream life and property.
LOW HAZARD POTENTIAL Dams assigned the low hazard potential classification are those where loss of human life due to failure or mis-operation is unlikely and results in low economic and/or environmental losses. Losses are principally limited to the dam owner’s property.
SIGNIFICANT HAZARD POTENTIAL Dams assigned the significant hazard potential classification are those dams where there is a small possibility of loss of life due to failure or mis-operation but can cause economic loss, environmental damage, disruption of lifeline facilities, or can impact other concerns.
HIGH HAZARD POTENTIAL Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life, serious damage to structures, important roads, public utilities or railroads.
Hazard classification categories, low, significant and high are synonymous with Natural Resources Conservation Service (NRCS) Pond Code MD-378 hazard classes “a”, “b”, and “c”, respectively.