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Though city commissioners expressed concern with the impact new floodplain maps near Bozeman Creek will have on business owners, they are left with few good options but to approve them.

The commission gave preliminary approval to a complete rewrite of the city’s floodplain regulations and of maps around Bozeman Creek, Bridger Creek and the East Gallatin River Tuesday night. The new maps loop 182 buildings into the special flood hazard area, mostly in downtown Bozeman. About half of the buildings were already in the flood hazard area, senior engineer Brian Heaston said, and about 100 buildings are being mapped out of the floodplain.

The change means that any of those building owners who are still paying off a federally backed mortgage will soon need to purchase flood insurance.

“These premiums can be very, very expensive in excess of $10,000 a year for buildings that have full basements,” Heaston said. “If any of those buildings are mortgaged, they’re going to have to carry that flood insurance cost. And again, that’s a matter of federal law, there’s no getting around that.”

The maps are being updated to correct inaccuracies in the 2011 flood maps. The maps were not accurately placed on the sources of potential flooding, Heaston said, meaning some buildings were incorrectly looped into a floodplain and others were left out.

The new maps laid out by the Federal Emergency Management Agency will go into effect in late April, whether the city approves of them or not. The city also hired a consulting firm to help refine the maps.

“I can tell you with confidence that that mapping that you see here is an accurate, or as accurate a representation of the base flood behavior when it occurs that we’re going to be able to get,” Heaston said.

The city needs to have updated and active floodplain regulations in order for building owners to qualify for federal flood insurance and for Bozeman to be eligible for disaster relief, Heaston said.

Several city commissioners expressed concern about the impact the change will have on building owners who are being newly mapped into the flood zone. Heaston said the National Flood Insurance Program does offer a gradually increasing payment program to those new to flood insurance, meaning building owners may not have to pay the full premium right away.

FEMA is also holding an information session for building owners in late March.

Beyond an insurance requirement, properties in the special flood hazard area are also subject to other regulations. The area is split into two categories, a floodway and the flood fringe.

During a previous city meeting, Heaston said the floodway is where floodwater would be the deepest and swiftest moving, typically centered on the flooding source. New construction is prohibited, and existing buildings cannot expand their footprint, and any “significant improvements” to a building would require it be lifted above the elevation of a 100-year flood level.

Within the flood fringe, the restrictions are slightly relaxed, though similarly mitigate risk of flood damage to buildings.

Heaston said Tuesday that most of the floodplain changes are in already developed areas of the city, but community development manager Chris Saunders noted having accurate flood maps is still crucial for future growth.

“Our growth policy calls for infill support and increased density,” Saunders said. “When that happens, it’s really, really important that we have the most accurate mapping available to help design and layout new development within flood prone areas.”

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Nora Shelly can be reached at or 406-582-2607.

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