Dams_Content Page_Dam failure analysis DFA

Dam Failure Analysis (DFA)

A dam failure analysis (DFA) is required for all large dams under Chapter NR 333, Wis. Adm. Code. It is used for these purposes:

  • Identify the inundation area or the extent of the dam failure floodplain (hydraulic shadow) for the dam if it were to fail;
  • Determine the dam's hazard rating based on the affected development downstream;
  • Determine the design spillway capacity requirements for the structure;
  • Utilize the information to determine downstream land use controls that must be implemented to protect the public; and
  • Develop and implement a detailed emergency action plan for the dam.

The DFA is data intensive computer modeling performed by an engineering consultant. There are very specific parameters used to determine the potential effects of a dam failure. The study must be performed and submitted to the DNR for approval by an engineer registered in the state of Wisconsin. You will need to hire an engineer registered in Wisconsin to complete the analysis.

A DFA submittal will include (but is not limited to):

  • Detailed hydrology defining the 100-year flood and required spillway design floods for the drainage basin;
  • Detailed hydraulic analysis of the area including modeling of these scenarios during the 100-year flood:
    • Dam in place,
    • Dam non-existent, or
    • Dam in place and failing;
  • Maps, profiles and data tables required for the adoption of floodplain zoning; and
  • A completed "Dam Failure Analysis Review Checklist" that can be obtained from your local Water Management Engineer.
Contact information
DNR Dam Safety
DNR Dam Safety Program WT/3
101 S Webster St
PO Box 7921
Madison WI 53707–7921