California Department of Transportation

Project Development Workflow Tasks (PDWT)

Part 3 - Identify Project Need and Project Initiation Document

II. Project Initiation Document

A. Define Transportation Need and Assess Site (150.05) - Obtain and Review Existing Reports, Studies and Mapping (150.05.05)

P12. Obtain FEMA/FIRM Maps

Federal Emergency Management (FEMA) and Flood Insurance Rating Maps (FIRM) are typically obtained from the District Hydraulic Branch. They are used to determine whether a project will encroach upon a base floodplain.

All federally approved highway construction, reconstruction, rehabilitation, repair or improvement projects encroaching upon a 100-year (1% probability) floodplain must

  • Avoid support of incompatible floodplain development,
  • Minimize the impact of highway actions that adversely affect the base floodplain,
  • Restore and preserve the natural and beneficial floodplain values, and
  • Be consistent with the standards/criteria of the National Flood Insurance Program of the Federal Emergency Management Agency (FEMA).

It should be noted that the absence of National Flood Insurance Program or state Department of Water Resources base floodplain maps does not necessarily indicate that there is no base floodplain in the area. Where no state or federal data is available, the Department is responsible for examining other data regarding recent flood locations and developing adequate information and analysis to support the conclusions.

Although, the Environmental Planning Branch and the Hydraulic Engineer will assess the impact to a floodplain, the project engineer must consider design elements to minimize any impacts.


Standard Environmental Reference, Environmental Handbook Vol.1, (Chapter 17, “Floodplains”)

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This page last updated July 20, 2010