The city of Rapid City continues to restrict development in flood-prone areas in town 40 years after the Black Hills Flood.
In the floodway, or the area of fastest moving water in a flood, nothing can be built that would obstruct the area’s ability to carry the flow of water.
In the 100-year floodplain, or the area where water spreads out during a flood, any new residential construction must be built at least one foot above the base flood elevation.
Residents are also not allowed to make any improvements to existing homes that exceed 50 percent of the value of the structure when it was added to the floodplain.
You have free articles remaining.
So, if a home was worth $20,000 in 1975 when it was added to the floodplain, the city will only permit up to $10,000 in improvements over the lifespan of the structure, according to city building official Brad Solon.
Who is and is not in the floodplain and subject to the city's construction regulations is determined by FEMA, not city officials, based on the most recent flood maps available, said Mary Bosworth, a city engineer who works on floodplain issues.
New maps could be adopted later this year, adding and subtracting some properties to the boundaries, she said. Currently, 4.25 square miles of property within city limits fall within the 100-year floodplain.
If the city did not have the restrictions in place, Rapid City residents would not be eligible for flood insurance, a requirement of any federally backed mortgage, Bosworth said.