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Flood Information

Several Denver neighborhoods experience flooding during rainstorms or after very wet winters when ground is saturated. More extreme flooding is also possible in lower-lying areas of town, and some residents are at increased risk of flooding because of their proximity to a major waterway. 

The city encourages all residents to be aware of flood risks and take precautions to protect their lives and property.

Please use the resources below to understand your flood risk and get information on what you need to do to stay safe. 

 

Terms & Definitions

Flood or Flooding: A general and temporary condition of partial or complete inundation of normally dry land.

Floodplain: Any land area susceptible to being inundated as the result of a flood.

Base Flood: Also known as “100-year flood” or "1% annual chance flood” — A flood having a one-percent chance of being equaled or exceeded in any given year. The term does not imply that the flood will necessarily happen once every one hundred years.

Special Flood Hazard Area (SFHA): The land within a community subject to inundation by the base flood as shown on the FEMA Flood Insurance Rate Map (FIRM).

Flood Insurance Rate Map (FIRM): The official map on which FEMA has delineated both the SFHA and the risk premium zones applicable to the community.

Regulatory floodplain: The area of land subject to inundation by the base flood as delineated by the SFHA and any other floodplain maps that have been adopted by the City & County of Denver. These areas are regulated in accordance with the City & County of Denver Floodplain Ordinance.

Potential Inundation Area (PIA): Areas where stormwater has been reported to collect in depths exceeding 12" during storm events and where various studies have identified the potential for flooding in a major storm event. The areas depicted represent current best-available information of these hazards. PIAs are not to be confused with SFHAs.

 

Drainage Complaints or Maintenance Requests

In Denver, contact 311 or use Pocketgov

For properties in the floodplain

Construction & Remodeling

In general, most construction within the floodway is prohibited.

  • Residential construction within the floodplain must elevate the lowest floor (including basement), and all associated machinery and equipment, to a minimum of the flood protection elevation.
  • Commercial or industrial development must elevate the lowest floor (including basement) or dry floodproof, including all associated machinery and equipment, to a minimum of the flood protection elevation.
  • Flood protection elevation is 1.5 feet above the base flood elevation or depth of flooding defined for the regulatory floodplain.
  • Projects on existing buildings in the regulatory floodplain are subject to “Substantial Improvement” rules. If a project (home remodel, commercial tenant finish, repairs, new addition, etc.) on an existing building triggers substantial improvement the entire building must be brought into compliance with the Floodplain Ordinance which can have significant financial implications. Substantial Improvement occurs when the construction cost reaches 50% (or greater) of the existing market value of the building (excluding land value). See Floodplain Entrance Requirements for more info on Substantial Improvement requirements.
  • Elevation certificates are required for all structures built within the regulatory floodplain

Read Denver’s Floodplain Ordinance (Article V, Chapter 56, Revised Municipal Code)

City and County of Denver Flood Protection Handbook (PDF)

Homeowner's Guide to Runoff (PDF)

All construction (even remodels) located in the regulatory floodplain are required to obtain a Sewer Use and Drainage Permit (SUDP) for floodplain use. Find additional information about the requirements and supporting documents on the Development Services SUDP page under Requirements for Specific Project Types.

All development projects for properties or parcels located in the regulatory floodplain are required to obtain a Sewer Use and Drainage Permit (SUDP) for floodplain use. Find additional information about the requirements and supporting documents on the Development Services SUDP page under Requirements for Specific Project Types.

Floodplain regulations are summarized in the Storm Drainage Design and Technical Criteria Manual - Floodplain Ordinance (Chapter 4) (PDF)

The City and County of Denver works with UDFCD and FEMA to study flood risk and update flood maps through a Flood Hazard Area Delineation (FHAD), and the FHAD is sometimes paired with a watershed master plan called an Outfall Systems Plan (OSP) or a Major Drainageway Plan (MDP)

The Urban Drainage and Flood Control District (UDFCD) was established by the Colorado legislature in 1969, for the purpose of assisting local governments in the Denver metropolitan area with multi-jurisdictional drainage and flood control problems. UDFCD covers an area of 1608 square miles and includes Denver, parts of the 6 surrounding counties, and all or parts of 33 incorporated cities and towns. The population within UDFCD is approximately 2.8 million people. 

 

Questions?

Floodplains: Contact the City's Floodplain Administrator at floodplain@denvergov.org or 720-913-0720

PIAs: Contact Denver Wastewater Engineering at 303-446-3400