Encroachments

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The purpose of this page is to define encroachments, a commonly used term in floodplain management.

Definition/Description

Encroachments are activities or construction within the floodway including fill, new construction, substantial improvements, and other development. These activities are prohibited within the adopted regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses that the proposed encroachment would not result in any increase in flood levels.

The community is responsible to review and maintain record of the documentation demonstrating that any permitted floodway encroachment meets National Flood Insurance Program (NFIP) requirements. A "no-rise certification" for floodways may be used to document the analyses.

NFIP Requirement

60.0 - Criteria for Land Management and Use

  • 60.3 (c) (10) - Cumulative Effects of Development
  • 60.3 (d) (2) - Floodway Adoption
  • 60.3 (d) (3) - Floodway Encroachment
  • 60.3 (d) (4) - Floodway Encroachments that Cause an Increase

Other Applicable NFIP Regulations

65.12 - Revision of flood insurance rate maps to reflect base flood elevations caused by proposed encroachments

Guidance

IS-9 Managing Floodplain Development Through The National Flood Insurance Program (NFIP)  (Pages 5-21 to 5-24)

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Special Topic Resources

IS-9 Managing Floodplain Development Through The National Flood Insurance Program (NFIP)

  • Pages 5-23 to 5-24, Conveyance Shadow or Hydraulic Shadow
  • Pages 5-21 to 5-24, Encroachment Review
Last Updated: 
04/26/2015 - 14:02
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