The executive director shall classify dams for hazard based on either potential loss of human life or property damage, in the event of failure or malfunction of the dam or appurtenant structures, within affected developments, that are existing at the time of the classification. The hazard classification may include use of a breach analysis that addresses the incremental impact of the potential breach over and above the impact of the flood that may have caused the breach, as defined in §299.15(a)(4)(A)(i) of this title (relating to Hydrologic and Hydraulic Criteria for Dams). The classification must be according to the following. (1) Low. A dam in the low-hazard potential category has: (A) no loss of human life expected (no permanent habitable structures in the breach inundation area downstream of the dam); and (B) minimal economic loss (located primarily in rural areas where failure may damage occasional farm buildings, limited agricultural improvements, and minor highways as defined in §299.2(38) of this title (relating to Definitions)). (2) Significant. A dam in the significant-hazard potential category has: (A) loss of human life possible (one to six lives or one or two habitable structures in the breach inundation area downstream of the dam); or (B) appreciable economic loss, located primarily in rural areas where failure may cause: (i) damage to isolated homes; (ii) damage to secondary highways as defined in §299.2(58); (iii) damage to minor railroads; or (iv) interruption of service or use of public utilities, including the design purpose of the utility. (3) High. A dam in the high-hazard potential category has: (A) loss of life expected (seven or more lives or three or more habitable structures in the breach inundation area downstream of the dam); or (B) excessive economic loss, located primarily in or near urban areas where failure would be expected to cause extensive damage to: (i) public facilities; (ii) agricultural, industrial, or commercial facilities; (iii) public utilities, including the design purpose of the utility; (iv) main highways as defined in §299.2(33); or (v) railroads used as a major transportation system. |
