How big a flood plain should we protect?

Canada usually regulates floodplain development on the basis of a 100 year storm (the storm calculated to have a 1% chance to happen each year) or a regional storm. The White House is now consulting on a new executive order that would expand floodplain protection for critical facilities, from the 100 to the 500 year storm line. Already, it says, floods have caused a greater loss of life and property than other US natural hazards, and flood damages continue to increase (such as the devastation this week on Vancouver Island.) With climate change, we must expect bigger and more frequent extreme storms and floods. 

“Critical facilities” are proposed to include both the obvious (emergency operations centres, power generation and other principal infrastructure facilities and vital data storage centres) and the sensitive (hospitals, nursing homes, and facilities that “produce, use or store toxic pollutants” such as petroleum products, chemicals, pesticides). None of these are to be purchased, constructed, financed, authorized or developed within the 500 year flood line, unless there is no practical alternative.

Industry chatter suggests the new Order will be finalized by year end, and will then apply to all U.S. federal government actions. I haven’t found any evidence that Canada is yet addressing the issue. If you know of any Canadian government doing something meaningful about critical facilities within the 500 year floodline, please let us know.