Completed: June 2013.
Funding: ASFPM.
This report reviews the origin, use and establishment of regulatory floodways and provides an assessment of the impact of encroachments based upon allowing a 1-foot increase in flood elevations during the regulatory flood. The assessment evaluated impacts on the physical characteristics of the floodway (floodway width, water velocity and area inundated), damage to development in the floodplain and floodplain natural resources.
The Floodway Encroachment Standard: Minimizing Cumulative Adverse Impacts
Appendix B for The Floodway Encroachment Standard: Minimizing Cumulative Adverse Impacts
Sample Letter Requesting Full Conveyance Floodway [.docx]
References:
Federal Emergency Management Agency. 1978. The Floodway: A Guide for Community Permit Officials. Community Assistance Series No. 4
Federal Emergency Management Agency Region 10. 2004. A Summary of NFIP Policy for Local Officials
Goddard, James, et. al. 1978. Origin and Rationale of Criterion Used in Designating Floodways
U.S. Army Corps of Engineers. 1990 Hydrologic Engineering Center and the Philadelphia District prepared for FEMA Region 3. Floodplain Management Information Series: A Special Report - Procedures for Compliance with Floodway Regulations
Related projects:
2D Modeling Guidance - 2025
Impacts of Floodway Surcharge - 2024
Floodway Outreach Project - 2023