According to the Endangered Species Act, “Endangered species means any species which is in danger of extinction throughout all or a significant portion of its range other than a species of the Class Insecta determined by the Secretary (of the Interior) to constitute a pest whose protection under the provisions of this Act would present an overwhelming and overriding risk to man…Threatened species means any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.”

Determine whether your site is considered habitat for threatened or endangered species. Many people assume that their project is not located on threatened or endangered species habitat; however, you must do the research, as this is more common than you may think. 

Species on Federal or State Threatened or Endangered List

If the FEMA website does not provide digital data for your project location, check with your local municipality or county to see if they have a mapping program or if they can provide you with guidance on where to look. For example, the city of Boulder, Colorado provides an eMap service for the 100- and 500-year floodplain. See the example of the City of Boulder’s 100-year floodplain research in the Documentation Toolkit.

Go to the FEMA website and use their mapping tool (Map Viewer) to help you determine whether your project is in Zone A (the 100-year floodplain). See the example of FEMA 100-year floodplain research in the Documentation Toolkit. Use the following steps:

As an initial step, search for the 100-year floodplain on the FEMA website for your project address. Some states and counties have more information than others, and a number of locations are not accessible through FEMA’s digital mapping program. See the Resources section for a link to the FEMA Map Viewer website.  

The 100-year floodplain, defined by FEMA, is the elevation to which a flood has a 1% chance of reaching or exceeding in a given year. (It is not the level of the most significant flood within a 100-year period.) So-called 100-year floods can occur many times within a 100-year period. 

If your site has not been previously developed, determine whether it is lower than five feet above the 100-year floodplain elevation.

If your site has been previously developed, you can skip the floodplain requirement. However, it’s still good practice to consider site development and design strategies to mitigate your project’s risk from flooding.

100-Year Flood Plain