Several Denver neighborhoods experience flooding during rainstorms or after very wet winters when the 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.
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.
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. As of August 2018, the SUDP application has been combined with electronic building permit applications for a more streamlined submittal process and faster review times for many SUDP customers. SUDP reviews will now start when a building permit application is received.
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 MHFD 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 Mile High Flood District 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. MHFD 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 MHFD is approximately 2.8 million people.