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Revised 100-Year Floodplain

  • The City has a floodplain overlay district which shows the areas the Federal Emergency Management Agency (FEMA) has identified as Special Flood Hazard. Those are the areas of land that have a one percent chance of being underwater in any year. This used to be known as the 100-year floodplain, but these floods can and do happen more often than once every hundred years. 

    2019 map and code revisions

    FEMA recently adopted a new flood map and required the City to make some minor changes to the code in order to stay in the National Flood Insurance Program. Being a part of this program enables owners of property within the floodplain to purchase affordable, federally subsidized, flood insurance to insure against property damage during flooding events.

    Project process

    • In June 2016, a public meeting was held to review the maps with FEMA, State Department of Land Conservation and Development, and City staff.
    • In October 2016, stakeholder meetings were held on the Environmental Overlay Project which discussed (in part), the proposed changes to the FEMA maps based on more recent studies.
    • The FEMA appeal period began May 17, 2017 and ended August 15, 2017
    • A letter of final determination was issued by FEMA on August 1, 2018, giving communities six months to adopt the revised ordinance and maps.
    • On September 24, 2018, the Planning Commission recommended approval of Council Bill 13-18 which adopted the new maps and studies. Council approved the bill at their October 16, 2018 meeting. The maps will be effective on February 1, 2019.
    • On October 1, 2018, FEMA provided the City with the results of their audit of the Gresham code, requiring some minor changes and clarification to the Community Development Code.
    • The City held an open house meeting on November 19, 2018.
    • On November 26, 2018, the Planning Commission recommended approval of Council Bill 14-18 which adopted the new maps and studies. Council approved the bill at their December 18, 2018 meeting. The code will be effective February 1, 2019.

    Summary of changes

    • Adopt definitions to match FEAM definitions
    • Clarify floodplain permits and reviews
    • Adopt standards for drainage
    • Clarify information applicants provide to the City
    • Clarify development language in the floodway
    • Adopt standards for manufactured home park
    • Clarify how variances will be processed
    • Clarify requirements for document retention
    • Add a provision for notification of jurisdictional boundary changes

    Gresham resources

    Gresham code has rules for development in the floodplain. Section 5.0100 Floodplain Overlay District regulates what is and is not allowed in the floodplain. If you want to do work in the floodplain (including digging, putting up small sheds and fences, or storing things) you should contact the Planner on Duty at 503-618-2780 or who can help you make sure you follow the right steps. 

    Contact us

    For more information, contact Jim Wheeler, City of Gresham Floodplain Administrator at 503-618-2881 or