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Floodplain Information
About the Floodplain
The City of Watertown has three watersheds: Willow Creek, Big Sioux River, and Roby Creek along with two lakes: Lake Kampeska and Lake Pelican which is important to understand if your current property or future project is located within the floodplain.
Am I in the floodplain?
To see if your property is in the floodplain click here to view a map from Federal Emergency Management Agency (FEMA). You may also contact City staff in the our office who can assist with technical questions to ensure your property and structures are compliant with FEMA and City ordinance.
What does it mean if I am in the floodplain?
All properties that fall within the floodplain have additional restrictions that apply for property improvement depending on the situation. Here are some of the most common situations that your property may fall into. Click on the sustenance to expand for more information or to condense information.
By default the property is considered completely within the floodplain by the City. Additional details can be provided to the City to show that the building, property, or part of the property should be considered out based on the ground level. In this situation usually an Elevation Certificate (EC) or a site plan is required by City for projects.
The City's side yard restrictions require any building used for residential (House, Apartment, Condo, Mixed-Use building, Etc.) to meet specific conditions for any building within 100 feet of any City regulated floodplain. For new construction or additions with basements these properties need meet the standards set by the ordinance, such as no basement within 20 feet of the floodplain, no basement floor lower than 5 feet below the Base Flood Elevation (BFE), and no basement openings less than 1 foot above the BFE.
The City's standards for new or substantial construction in these areas require the top of the lowest floor and all utilities be at least 1 feet above the Base Flood Elevation (BFE). For work on existing buildings, each permit's value is compared to the building value at the time of improvement to get a percentage and is tracked for 3 years from the date of issuance. When a new permit is requested, all permit percentages within a 3-year period are added together and if the total percentage is 45 percent or greater then the whole building will need to meet current standards. Typically this can mean removing a basement and/or raising the building, but it can result in needing to completely reconstruct a building.
In addition, to buildings the City also regulates digging and filling within the floodplain. Any proposed fill within the floodplain will be required to provide compensatory storage. This means that for any amount of fill being proposed in the floodplain the same amount of earth or more will need to be removed from the same area so that during a flood generally the same amount of water can be stored. Please reach out to the floodplain staff with any specific questions.
No floodplain restrictions are applicable. Please check with the Community Development office for required building and zoning permits on all projects.
Is flood insurance required?
The City does not require floodplain insurance but property owners should be aware those decisions are most commonly made by a property's lending institution. The property owner may need to hire a surveyor or engineer to complete a Elevation Certificate (EC) and then obtain a letter from FEMA showing that the property is reasonably safe from flooding.
The City is undergoing an update to the floodplain map. For more information on the update process or to view the preliminary map please visit FEMA Preliminary SD Flood Risk Map or FEMA National Flood Hazard Layer Viewer which are also listed below under Helpful Resources.