Know Your Flood Risk

Functions of the Floodplain

Floodplains are important ecological features which perform natural functions that are designed to keep floodwaters in check. Floodplains act as overflow basins for rivers and streams, so that when a large amount of rain falls at once, the rivers and streams have somewhere to distribute excess water. In addition to this, floodplains provide habitat for countless species of animals, such as deer and foxes, as well as fish and birds. This is why it is crucial that we limit development in floodplains as much as possible. In addition to damaging a threatened ecosystem, the more development in a floodplain, the worse flooding becomes. Any kind of development in a floodplain displaces potential floodwaters, which then creates a larger problem downstream or even just next door.

The City of Manhattan maintains approximately 743 acres of designated open space in the Special Flood Hazard Area (SFHA). This open space ranges from parks to former residential lots that have been converted to open space to school recreational areas such as soccer fields and baseball diamonds. These designated open areas help keep the floodplain in natural balance. The more open space within this sensitive environment, the less potentially damaging floods could become.

Purchasing Flood Insurance

A typical home insurance policy does not cover losses from a flood. Property identified in the high-risk areas of the Digital Flood Insurance Risk Maps (DFIRMs) will be required to carry flood insurance, with rates based on the flood risks that went into effect on March 16, 2015. The City of Manhattan participates in the National Flood Insurance Program, which entitles homeowners, renters and business owners to purchase flood insurance to protect their property and/or belongings in the event of a flood.

Flood insurance for a structure and its contents is available to all residents, regardless if you are in an identified flood-prone area. View the FIRMs to determine your property's flood risk, talk to your insurance provider to determine if you need additional coverage and visit NFIP's website for more information.

Floodplain Management Plan

The City undertakes a variety of planning actions to help mitigate future flood damages and risk. Those activities are included in these three plans:

Each year we provide an annual review of our progress on those activities. View the most recent updated annual review in October 2023 (PDF).

Floodplain Regulations

As an NFIP-participating community, Manhattan is required to follow, adopt and apply a minimum set of development regulations for properties and structures in the high-risk floodplains (Zones A, AE and AH on the FIRMs). These regulations are designed to require minimum standards when building a new structure in the floodplain or when remodeling or repairing an existing structure. The intent is to better protect existing structures and new properties from flooding based on the current FIRMs and floods anticipated in the future.

To view these adopted floodplain regulations, please follow the link to the City of Manhattan Development Code (MDC) website. Then navigate to Article 26-6.

Substantial Improvement / Substantial Damage

What about structures that are damaged within a floodplain or structures that the owner wants to improve that are within a floodplain?

Structures within a floodplain can be repaired or improved. However, there are limitations on this allowance. If the repairs or the improvements to the structure equal or exceed 50% of the fair market value of the structure before the damage or improvement, then the improvement or repair must comply with the Floodplain Regulations (i.e., be designed to minimize flood damage, be constructed of flood resistant materials, and not have any new enclosed area lower than that of the existing structure. In the case of damage, if the cost of repairs equal or exceed 50% of the value of the structure before it was damaged, then the structure must be brought into compliance with the Floodplain Regulations. Additionally, if a structure sustains flood-related damage on two separate occasions within a 10-year period, and the cost of repairs for each flood event equals or exceeds 25% of the fair market value, then the structure is considered substantially damaged.

Contact Us

For more information about our floodplain programs, regulations or any of these other topics, or to request a site visit to consider your particular drainage issue, please contact our floodplain team.