Floodplains and Flood Insurance
The goal of the floodplain ordinance is to minimize the threat to life and property resulting from flooding. This is accomplished by encouraging communities to preserve floodplains for carrying and storing flood waters.
Structures may continue to be located in floodplains. Structures to be located in the floodplain must not only be elevated above the 100-year flood elevation, but they must be placed so as not to diminish the ability of the floodplain to carry and store flood water. Therefore, the decision to buy an existing residence or build a new residence in the floodplain must be approached with great care.
What is a floodplain?
Floodplains are lowland areas adjacent to lakes, wetlands, and rivers that are covered by water during a flood. The regulatory floodplain is the area covered by a flood that has a 1% chance of occurring in any given year, often referred to as the 100-year flood.
There are two components of the floodplain; floodway and flood fringe.
The floodway is the river channel and the areas immediately adjacent to the channel which are needed to pass the flow of the 100-year flood or 1% chance flood. The floodway is the area that experiences the deepest water and the highest flow velocities. Most Structures are not allowed within this district (including principal or accessory structures for residential, commercial or industrial purposes) due to the increased flood damage potential. Those uses that are allowed, such as fill or accessory structures for open space uses, require special attention prior to being proposed to ensure that the proposed use will not cause an increase to the 100-year flood elevation by encroachment.
The flood fringe is the part of the floodplain outside of the floodway. The flood fringe is primarily a flood water storage area, so fill and elevated structures can be placed in this area. Depths and velocities of floodwater in flood fringe areas are generally lower than in the floodway. Most development activities are allowed in the flood fringe as long as structures are elevated above the regulatory flood protection elevation and if it can be demonstrated through a hydraulic study that the fill will not increase or change the floodplain boundaries.
Floodway and flood fringe areas are designated only after a detailed hydraulic study has been performed and a 100-year flood elevation has been determined. Due to the cost of these hydraulic studies, some floodplain areas are mapped as general floodplains. The general floodplain is also called an approximate study area or Unnumbered A Zone. Due to this lack of 100-year flood elevations and floodway/flood fringe determinations in a general floodplain area, it is the property owner's responsibility to pay for this hydraulic analysis before the community can authorize any development.
The related floodway, flood fringe and general floodplain areas are delineated on maps called Flood Insurance Rate Maps (FIRM) published by the National Flood Insurance Program. The related floodway, flood fringe and general floodplain are portrayed as shaded areas on the FIRM maps. The best way to find out if a home or property is located in the floodplain is by visiting the local Zoning Office.
The Sherburne County Zoning Office has copies of the FIRM for Sherburne County areas located outside of city limits. These are usually the official source of information about whether a structure is located in the regulatory floodplain. The FIRM maps will show if a home or property is located in the floodplain and, more specifically, if it is located in the floodway or flood fringe. Also, landowners should be aware that communities may contain substantial areas that are subject to flooding, but are not indicated as floodplain on the official maps.
Building on a floodplain
For virtually every mortgage transaction involving a structure in the US, the lender reviews the current NFIP maps for the community in which the property is located to determine its location relative to the published Special Flood Hazard Area (SFHA) and completes the Standard Flood Hazard Determination Form (SFHDF). If the lender determines that the structure is indeed located within the SFHA and the community is participating in the NFIP, the borrower is then notified that flood insurance will be required as a condition of receiving the loan. A similar review is completed whenever a loan is sold on the secondary loan market or perhaps when the lender completes a routine review of its mortgage portfolio.
Lenders, on their own initiative, may also require the purchase of flood insurance even if a building is located outside an SFHA. A decision to require coverage under such circumstances is not compelled by the statute, but is founded on the contractual relationship between the parties. Lenders have the prerogative to require flood insurance to protect their investments, provided that they have reserved that option in their mortgage loan document.
When a structure located in the floodplain has been properly elevated to the RFPE this does not automatically exempt the site from flood insurance. The owner may request FEMA to waive the requirement for flood insurance for a federally insured or financed loan. FEMA can do this by issuing what is called a letter of map revision (LOMR) once proper documentation has been provided that the structure’s lowest floor (including basement) and lowest adjacent grade have been elevated on fill to the 1% chance flood level. FEMA can also issue a letter of map amendment (LOMA), waiving the mandatory insurance requirement, to those structures inadvertently or incorrectly mapped in the 1% chance floodplain. Applications for LOMR and LOMA are available at the Sherburne County Zoning Office.
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