Floodplain Management Program

New Floodplain Maps Timeline and Additional Details

The Discovery process identifies areas of flooding concern and helps to establish a community's highest priorities. Discovery also identifies opportunities for moving mitigation beyond planning and into action.

Floodplain Ordinance Changes

Changes are effective as of July 30, 2021

Check to see if your property is in the floodplain

Search Your Address for Flood Risk

Flood Gauges in real time

(images are not in real time*) 

*Image source, Google Maps, Street view.

Floodplain Permits

If a permit is required it costs $75 per permit. It is possible to have multiple properties on one permit for floodplain.

We review plans for items from grading to building, issue floodplain permits, and track for compliance with FEMA regulations. This can include, but is not limited to:

  • Review applications and issue permits.
  • Interpret the boundaries of Flood Hazard Areas.
  • Use best available data when Base Flood elevations are not provided.
  • Determine substantial improvement/damage
  • Interact in variance appeal processes
  • Notify adjacent communities, the State, and the Administrator of Alteration or Relocation to the water course.
  • Ensure Maintenance of Watercourse
  • Conduct inspections
  • Investigate complaints of Code Violations
  • Coordinate Map Amendments and Appeals
  • Maintain for Public inspection all flood permit records i.e. Amendments, Revisions, Fill, Certificates, Elevation
  • Certificates and No-Rise Certificates
  • Maintain Floodplain Maps and Flood Data
  • Maintain and update the Floodplain Management Ordinance
  • Prepare and submit biennial reports”
To ensure that the safety of the general public and properties along the floodplain are protected to the greatest extend possible.”

The City of Sioux Falls limits development in floodplains and for all lots since August 25, 2016 within one hundred feet of the regulated floodplain. Any property within the floodplain is not allowed to build in the floodway and is required to be at least two feet above the Base Flood Elevation (BFE) for any part of the building not to be used for cold storage. Any storage areas with an elevation below BFE are required to have openings and are designed for water flow and damage. Some types of buildings are restricted from this area, they include hospitals, fire stations, nursing homes, schools, etc. For areas within one hundred feet of the regulated floodplain and platted since August 25, 2016 residential buildings are limited to having basements no closer than twenty feet from the edge of the floodplain, basement depth of no more than five feet lower than the BFE, and the lowest opening such as doors or windows to the outside no less than one foot above the BFE. These standards are designed to provide additional protections for these properties.

In Addition to these restrictions the City also has limits for substantial damage and improvements. These are applicable to all property within the regulated floodplain are intended to help owners make an educated decision when it comes to financially investing or reinvesting in a property. Once a property has been declared substantially damaged or improved the entire structure will need to come up to the current standard, usually this means raising the building up so that the floor is at least two feet above the BFE.

Substantial damage is when a building gets damage from any source (fire, air plan, flood, etc.) and the cost of repairing that damage is equal or greater to 45%, and starting in 2023 that limit will be for over a three-year period.

Substantial improvement is when a building gets permits to make improvements in the building (addition, deck, roof, siding, remodeling, etc.) and the cost of the improvement is equal or greater to 45%, and starting in 2023 that limit will be for over a three-year period.

If you have questions regarding  a property and substantial improvement or damage please feel free to reach out to us at floodplain@siouxfalls.org.

Frequently Asked Questions

Flood is defined in the Standard Flood Insurance Policy (SFIP), in part, as:

  • A general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties (at least one of which is your property) from overflow of inland or tidal waters, from unusual and rapid accumulation or runoff of surface waters from any source, or from mudflow.
The Big Sioux River and Skunk Creek are the two primary flooding sources affecting the City of Sioux Falls. The Big Sioux River upstream of Sioux Falls has a drainage area of 5,718 square miles. Skunk Creek is a tributary to the Big Sioux River and has a drainage basin of 570 square miles upstream of Sioux Falls.
Since 1881, the City of Sioux Falls has experienced flooding from the Big Sioux River 19 times and from Skunk Creek 8 times. Updated December 2019.
Most flooding events occur during the months of March and April and are caused by snow melt. Flooding caused by rain fall historically has occurred during the month of June.
The areas subject to flooding are shown on the Flood Insurance Rate Maps (FIRM) dated September 2009 except in those areas identified below where the best available information is used for local floodplain management purposes. Flood Insurance Rate Maps (FIRM) are available for downloading here.
The digital Flood Insurance Rate Maps for 3 panels were amended on October 5, 2017; and 17 panels were amended on March 7, 2017; The other maps which remain in effect are from September 2, 2009. They replaced the November 16, 2011 maps.
A structure may have been constructed after 1979 outside of the floodplain boundaries, but exist within the floodplain boundaries as of 2009. From October 2007 to September 2009, the City hosted ten public meetings to discuss the flood insurance map changes from the 1982 version to the 2009 version. [Notices were sent to property owners of these open houses. Press releases were sent out and media coverage was extensive during this time.]

Section 42 of U.S.C. 4012a sets the ultimate responsibility to place flood insurance on the applicable lender. (Mandatory 11 )

A financial institution cannot rely on the statements of a borrower that the structure in question is either inside or outside an SFHA. (Mandatory 12)

Lenders may reasonably see assistance from third parties that have demonstrated their knowledge concerning flood map information. For regulatory purposes, reasonable reliance upon such services in the making of a lender’s determination is regarded as acceptable only to the extent that “such person guarantees that accuracy of the information.” (Mandatory 12)

  1. Determination Process
    The lender must take the responsibility for making flood zone determinations, either by making the determination internally or acquiring determination services (see page 11-12). FEMA [nor the City of Sioux Falls] does not perform individual property hazard determinations. The 1994 Reform Act state that the lender may provide for the acquisition or determination of flood hazard information to be made by a person other than the lender only to the extent that such person guarantees the accuracy of the information. (Mandatory 37)
Property owners may not contest the requirement if the lending institution has established the requirements as a part of its own standard lending practices. However, if a lending institution is requiring the insurance to meet mandatory flood insurance purchase requirements, the property owner and lender may jointly request that FEMA review the lending institution's determination. This request must be submitted within 45 days of the date the lending institution notified the property owner that a building or manufactured home is in the SFHA and flood insurance is required. In response, FEMA will issue a Letter of Determination Review (LODR). The LODR does not result in an amendment or revision to the NFIP map. It is only a finding as to whether the building or manufactured home is in the SFHA shown on the NFIP map. The LODR remains in effect until the NFIP map panel affecting the subject building or manufactured home is revised. (Answers 14)

Pre-FIRM buildings are those built before the effective date of our first Flood Insurance Rate Map; therefore, pre-firm is prior to January 17, 1979. (Floodplain 9-11)

Post FIRM buildings are those built after the effective date of our first insurance rate map; therefore, post-firm is after January 17, 1979.

Post FIRM rates are determined based on the elevation of the lowest floor (including basement) of the building in relation to the Base Flood Elevation. (Floodplain 9-14)

Elevation Certificates are required for most Post-Firm Buildings [Built after January 1979]. The elevation certificate provides the data the insurance agent needs to determine the lowest floor of the building and calculate the flood insurance premiums. (Floodplain 9-19)

In support of the NFIP, FEMA identifies flood hazard areas throughout the U.S. and it's territories by producing Flood Hazard Boundary Maps (FHBMs), Flood Insurance Rate Maps (FIRMs), and Flood Boundary & Floodway Maps (FBFMs). Several areas of flood hazards are commonly identified on these maps. One of these areas is the Special Flood Hazard Area (SFHA) or high risk area defined as any land that would be inundated by a flood having a 1-percent chance of occurring in any given year (also referred to as the base flood).

The high-risk area standard constitutes a reasonable compromise between the need for building restrictions to minimize potential loss of life and property and the economic benefits to be derived from floodplain development. Development may take place within the SFHA, provided that development complies with local floodplain management ordinances, which must meet the minimum Federal requirements. Flood insurance is required for insurable structures within high-risk areas to protect Federal financial investments and assistance used for acquisition and/or construction purposes within communities participating in the NFIP. (Answers 2)

In regards to subdivision development which is the initial stage of development, floodplain boundaries are required to be shown on a plat; this allows interested parties to know where the boundaries fall across property lines.

When applying for a building permit, the City requires documentation regarding the structure placement outside of the floodplain boundaries.

Section 45-15 (e) 156.051 - Duties and Responsibilities of the Floodplain Administrator where interpretations is needed as to the exact location of the boundaries of the areas of special flood hazards, the floodplain administrator shall make the necessary interpretation.

As mentioned earlier Who determines what zone a property is within for insurance? The lender is ultimately responsible for determinations regarding insurance on structures.
A floodplain development permit is required to be submitted on any development within a special hazard area. Section 156.032 - Floodplain Development Permits and Certificates application for floodplain development permit.The floodplain management ordinance addresses hazard reduction through general standards, specific standards and subdivision standards within Sections 156.065 -General Standards, 156.066 - Specific Standards, and 156.067- Standards for Subdivision Proposals.

Base Flood. Means the flood having a 1 percent chance of being equaled or exceeded in any given year.

Base Flood Elevation (BFE). Is the water surface elevation of the one (1) percent annual chance flood. The height in relation to mean sea level expected to be reached by the waters of the base flood at pertinent points in the floodplains of coastal and riverine areas.

All rating and compliance issues are related to BFE. We compare the lowest floor in the structure to BFE. Only an elevation certificate gives us these measurements. This [is] applicable to all" A" zone- post firm structures. It's optional on "A" zone -pre firm structures to gain a lower rating, insurance-wise. - Norm Ashcroft

A Post Firm [after 1979] -"A" policy can not be rated, or issued without an Elevation Certificate. It should have been done, and a record kept by the local flood plain manager of the community at the time of construction, to verify the construction was in compliance with their ordinance. If it was missed or lost, then someone has to have it done, and this may be the homeowner-- at his or her expense. This is hard, so I suggest someone call the local flood plain manager and see if the Elevation Certificate on the property is available, and then request a photo copy of the document for your use. It has to go in with the application. If it's not available, then the homeowner will have to get a surveyor --at their expense-- and have this document recreated. Sorry. I hope the community has the document--or---  - Norm Ascroft

The City of Sioux Falls does not require an elevation certificate with each building permit. The cost is prohibitive based upon the benefit. Those that benefit from the elevation certificate are those that are within a floodplain. If you are building within a floodplain, yes then they required. However, if you were building outside of the [1982] floodplain, they were not required—and therefore, not on file with the City of Sioux Falls. - Jeffrey Schmitt

"A" zone policy are "A" zone policies in most respects. There are different rates for different A zones, however. For example, un number "A" and AO / AH are different in cost from "AE". Coverage and etc. are the same, but they can cost differently. The lenders are concerned that the policy they receive is priced right or they can be "out of compliance". This is because we always drop coverage to equal the amount coverage that the premium we receive would have bought, if the policy had rated correctly. If this happens, then a lender can be under-insured and be fined by a regulator for not requiring the right amount of insurance. Therefore, they want the policies and the flood zone determination they have-- to match. - Norm Ashcroft

(3) Effect of Grandfathering on Flood Zone Determinations
New flood maps sometimes identify larger areas of high flood hazard than do older maps. FEMA recognizes that property owners might not have built in high flood risk areas if the risks had been identified at the time. However, funding for new FIRMs has historically been inadequate, and development contributes to changes in flood risk within communities.

Therefore, in fairness to policyholders who built in compliance with the existing floodplain management standards for their flood zones and/or have continuously maintained Federal flood insurance [Loyalty Grandfathering], FEMA developed grandfather rules to avoid penalizing these policyholders with higher rates. These rules allow policyholders to benefit in the premium rating of their buildings.

For example, if a new policy is applied for, the rates can be based on the FIRM zone and the BFE on the old map in effect on the date the building was constructed provided that:

  • The building was built in compliance with the map in effect at the time of construction; and 
  • The building has not been altered in any way that has resulted in a lowest floor, for rating purposes, situated lower than the BFE on that FIRM (e.g., enclosing the area below an elevated building); and
  • The building has not been substantially improved.
The property owner or insurance producer must provide proper documentation to the Write Your Own (WYO) company or NFIP Servicing Agent. The documentation must include: the date of construction; the date of the FIRM; the zone on that FIRM in which the property is located; the BFE, if any, for that zone; a copy of the map panel showing the location of the building; and the rating element that is to be grandfathered (e.g., zone, BFE, elevation difference). A letter from a community official verifying this information also is acceptable. [Built in Compliance Grandfathering] (Mandatory 13)
No. Only Post Firm [after 1979], who didn’t buy ahead, can use the “Built in Compliance” techniques. Pre Firm can only buy ahead of the map. After the map’s effective date [Sept. 2, 2009], Pre Firm are too late to Grand Father and the “Built in Compliance” is not available to them.  - Norm Ashcroft

Yes-- Give the certificate to the insured and they take it to their insurance agent, who has to attach it to the insurance application. If the agent calls, ask him to come by and pick up the Certificate of Compliance. You don’t have to do more. Your signature is the key to the documents acceptability. These are needed by Post FIRM [after 1979] applicants going from B, C, X to A. . - Norm Ashcroft

The agents’ only need the built in compliance form if they want to get a policy AFTER the new map is in place. Building owners who want to ensure the next building owner can get coverage need to get the form filled out before the deadline so they know the building would be covered by the grandfathering cause in the future. An example would be a homeowner who's mortgage is paid off but knows they are going to sell at some point & are in the A zone. They can get that form from you, keep it on file & pass it along to the new homeowner to get the reduced rate. The built in compliance rule is for homes in Sioux Falls that were built AFTER 1979. - Erin May

The different uses for the two certificates are as follows:

Built In Compliance:

  • Use this for post-FIRM structures only that missed the grandfathering deadline (Sept. 2, 2009) in order to get B, C or X zone rates. Pre-FIRM customers are no longer eligible for the grandfathered rates.
  • Post-FIRM Building owners with a loan that is paid off and wish to keep this compliance form in their files for the next purchaser of the property so that the new building owner can qualify for grandfathered flood insurance rates in the future.

Elevation Certificate:

  • Pre-FIRM building owners who missed the grandfathering deadline & who believe their structure may be several feet above the base flood elevation. If their building is ABOVE the BFE, they can qualify for the post-FIRM rates and get a considerable discount. In fact, in some cases, if a building is above BFE, their rates may be better than the B, C or X zone rates, so it's worth it to compare rates with their agent. However, if their structure is below the BFE, then they won't receive a cost benefit by doing the elevation certificate. It's a risk the homeowner should consider fully before investing in the elevation certificate.
  • Post-FIRM building owners who believe their structure may be several feet above BFE. This example is more of a gamble for the building owner, however, because they qualify for the built in compliance certificate & will most likely get a cost savings for flood insurance via the grandfathered rates. However, if they believe their building is significantly ABOVE the BFE, then their rates can be cheaper in spite of being in an A zone. But with the cost of the elevation certificate and being unable to confirm their elevation until that certificate has been completed by a surveyor, then they run the risk of investing in the elevation certificate and not gaining a cost savings in their insurance rates if they are below BFE.
  • Any new construction in an A zone requires an elevation certificate be completed to verify it is being built above the BFE. If the structure is not designed to be above the BFE, the city of Sioux Falls should require them to stop construction and deny the builder an occupancy permit if they do not comply. An elevation certificate is completed based on the construction drawings and then completed again at completion to verify it has been built above the BFE. These elevation certificates should be kept on file by the city. 

 - Erin May

Federal Emergency Management Agency. Answers to Questions about the NFIP. ( May 2006). http://www.fema.gov/media-library/assets/documents/272

Erin May. Email, July 16, 2008

Erin May. Email, November 3, 2009

Norm. Norm Ashcroft. Email, July 16, 2008.

Built in Compliance. Norm Ashcroft. Email, August 3,2009.

Federal Emergency Management Agency. Floodplain Management Requirements. FEMA -480 (February 2005).

About the National Flood Insurance Program. Frequently Asked Questions. Federal Emergency Management Agency. Floodsmart.gov

Flood insurance is different than homeowners insurance because homeowners insurance excludes flood damage. Flood insurance is available to all properties within the City of Sioux Falls because the City participates in the National Flood Insurance Program. Your policy may be eligible for a discount because the City also participates in the Community Rating System. Any flood insurance needs to be in place at least 30 days before a flood event in order to put in a claim.

Insurance costs will be based on risk rating 2.0, more information on this method of determining flood insurance costs can be found at https://www.fema.gov/flood-insurance/risk-rating

Insurance coverage is limited to specific basement items that are not furniture and cleanup. A more detailed explanation can be found via FEMA’s website

Regular maintenance of property and drainage systems can be key to preventing or limiting flooding during an event. Look around your property and neighborhood and work with neighbors to identify where excess rain and snowmelt will likely go and see if there are any spots that may cause private property damage along the way. For your own property check to make sure things are secured to your house correctly so that they don’t get blown away in a high wind event, check that downspouts are far enough away from your house that water won’t be forced to sit next to your foundation for any periods of time.

More substantial modifications could be necessary to protect your structure from flooding. You can always reach out with questions to our floodplain team at floodplain@siouxfalls.org and we may be able to provide some guidance including when a permit for floodplain or building improvements may be needed. Some examples of projects that may need permitting are: installing a berm, regarding the property, replacing windows and doors with more flood resistance versions, or even elevating the structure. FEMA offers a detailed look into 6 ways to protect your home from flooding in THIS PDF guide.

For temporary emergency modifications generally you can start the installation immediately without a permit. Please feel free to reach out to verify if your temporary project meets the criteria for this emailing our floodplain team at floodplain@siouxfalls.org. Some examples of temporary projects that may be needed to prevent flooding are: installing a temporary berm, stacking sandbags or other water barrier options, temporary sealing building openings, or even elevating major appliances. A PDF FEMA guild can be found online HERE.

If you notice any illegal dumping in the drainage areas you can report it. You can use an app or the City’s website at: https://www.siouxfalls.org/contactus/public-works/engineering Select “Drainage Concerns” and then select the area and add any pictures or comments and send it in. You can also go below the map and submit text only information instead.

The floodplain function in the Sioux Falls area can be summarized in the following categories from A Unified National Program for Floodplain Management, 1994, p.41:

Water Resources:

  • Natural Flood & Erosion Control
    • Provide flood storage and conveyance
    • Reduce flood velocities
    • Reduce flood peaks
    • Reduce sedimentation
  • Surface Water Quality Maintenance
    • Filter nutrients and impurities from runoff
    • Process organic wastes
    • Moderate temperature of water
  • Groundwater Recharge
    • Promote infiltration and aquifer recharge
    • Reduce frequency and duration of low surface flows

Biologic Resources

  • Biological Productivity
    • Support high rate of plant growth
    • Maintain biodiversity
    • Maintain the integrity of the ecosystem  
  • Fish and Wildlife Habitats
    • Provide breeding and feeding grounds
    • Create and enhance waterfowl habitat
    • Protect habitats for rare and endangered species

Societal Resources

  • Harvest of Wild & Cultivated Products
    • Enhance agricultural lands
    • Provide sites for aquaculture
    • Restore and enhance forest lands 
  • Recreational Opportunities
    • Provide areas for active and passive uses
    • Provide open space
    • Provide aesthetic pleasure
  • Areas for Scientific Study and Outdoor Education
    • Contain cultural resources (historic and archaeological sites)
    • Provide opportunities for environmental and other studies

The City has different policies to help with different aspects of these areas, but the floodplain program implemented the compensatory storage requirement to address many of these issues, while our parks departments have provided great open space and natural areas along waterways in the City, and in addition, the Engineering department has provided many new areas for collection, saturation, and through more natural maintenance techniques provides for the natural filtration of water before it enters the stream.

Avoid Active Flood Areas


Email All of Us: Floodplain@siouxfalls.org

Floodplain Administrator: Butch Warrington

Main Contact: Albert Schmidt (CFM)
Phone: (605) 367-8603

Additional Contacts: Mariah South (CFM) & Karla Resendiz