Current regulations in Hamilton County allow essentially unlimited building in a flood plain if it is raised to an elevation at least one foot above the flood zone elevation. The “flood plain”, also known as the “100-year flood zone”, is an area deemed as having a one percent chance of flooding. A key point is that a 100-year flood does not mean it will flood every 100 years, but rather there is a one percent chance of that level of flood happening each year. FEMA uses the term Special Flood Hazard Area to identify areas on flood maps with a one percent or greater chance of flooding annually. Properties within the 100-year floodplain, or SFHA, are often required to purchase flood insurance, especially if they have a mortgage from a federally backed lender. Over time, the risk of flooding increases. For example, a home in a 100-year floodplain has a 26 percent chance of flooding during a 30-year mortgage period. Note that if Hamilton County loses access to the NFIP program, building and sales of properties requiring flood insurance would slow due to the inability to get flood insurance.
While the SFHA is a key focus for FEMA and NFIP, it is important to remember that flooding can occur outside these zones as well. Even areas outside the 100-year floodplain can experience flooding, and new risk models suggest that FEMA maps may not fully capture the extent of flood risk.
Developers commonly fill in the flood plain so they can construct homes in that area. When that is done, it means the water will have to go somewhere else, often subjecting nearby homes and businesses to increased risk.
This affects flood insurance premiums which are administered by the Federal Emergency Management Agency. Under the National Flood Insurance Program, insurance premiums are set based on flooding risk. Also part of that program is a sub-program called the Community Rating System. In Tennessee, FEMA offers flood insurance rate discounts through the CRS. Participating communities can receive discounts of 5 to 45 percent on flood insurance premiums. Additionally, discounts may be available for property modifications and mitigation efforts that reduce flood risk if they meet specific criteria. Participating communities can earn rate discounts of 5 to 45 percent. Policyholders in CRS communities currently save an average of $162, or 15 percent, per year on their flood insurance policy, but it could be as much as $486. Note that Davidson County (Nashville) residents qualify for a 10 percent flood insurance discount due to the county's participation in the CRS. Hamilton County does not participate in the CRS program. Part of having “affordable housing” is having less costs associated with owning a home and insurance is part of those costs. Additionally, the costs of moving soil to raise the elevation of flood plains increases the cost of building homes, which makes homes more expensive. Builders and realtors state we need more affordable housing so why construct homes on areas that require the expense of filling in flood plains?
The CRS incorporates an Open Space Preservation element that awards communities for maintaining or protecting floodplains as open space, which helps to reduce flood damage and increase community resilience. Filling in a floodplain is considered an encroachment, thus violating the OSP element and potentially reducing the amount of CRS credit earned by the community. Additionally, soil in our area has poor “perk” properties meaning water does not “soak in” very well. Typical flood plain areas have high water tables.
Again, Hamilton County does not even participate in the CRS.
The recent Plan Hamilton proposed limiting allowing filling in of only two-thirds of the flood plain distance although some on the citizen committee wanted to eliminate that provision entirely or keep it to one-half of the flood plain area. The builders asked for three-fourth of the flood plain distance. \Note that using distance can be very deceiving if the flood plain is round (which is sometimes the case). Using two-thirds of the distance yields allowing 89 percent of the flood plain in an essentially circular area and almost 94 percent of the flood plain if three-fourths of the distance is used. The Planning Commission did not even question this change and sent it to the County Commission for review.
A recent local example of this is a development in Ooltewah where the applicant proposed filling in about 26 acres of the flood zone to allow building and this was accepted by the Planning Commission because local regulations allow it. That work is currently in progress.
This sort of continuing infringement on flood zones has a cumulative effect on risk as recognized by FEMA but Hamilton County seems to ignore that fact. Changes need to be made to zoning policies to inhibit building in flood zones, so constituents who buy these new houses are not subject to flood damage and nearby homes are not subject to flooding due to this practice. Additionally, we believe insurance rates are unnecessarily high, and that FEMA National Flood Insurance Program eligibility is being jeopardized by such policies.
Gary Boles