Area floodplain maps being updated

By LILLY BROGGER/Montana State News

With multiple major bodies of water running through the Gallatin Valley, flooding is always a concern. In the winter, ice jams often cause homeowners to worry. In the spring, runoff can cause rivers and streams to swell to dangerous levels.

Understanding the floodplain is vital for keeping homes, roads and families safe; however, the maps of the floodplain are over 30 years old. The city of Bozeman, Gallatin County, the Federal Emergency Management Agency (FEMA) and Montana’s Department of Natural Resources and Conservation (DNRC) are currently attempting to update these maps. Changing the floodplain maps could affect insurance, city restrictions on building and lenders financing homes.

The bodies of water these maps concern are the West Gallatin River, Bozeman Creek, Mathew Bird Creek, Nash Spring Creek, Flat Creek, Figgins Creek and the Mill Ditch Diversion.

A public open house was held at the Bozeman City Hall on Thursday, April 7, to discuss the issue for residents along Bozeman Creek. The floodplain map for this area was created in 1974, a study was done in 1979 to better understand the floodplain and a revised version was put into place in 1985. It has not been revised since.

Tiffany Lyden, an outreach specialist for the Montana Department of Natural Resources and Conservation (DNRC), explained the floodplain specifications. The 100 year floodplain is the area where there is a 1 percent annual chance of a catastrophic flood in any given year.

Outside this zone is the 500-year floodplain, where there is a .2 percent annual threat of a flood. The floodway is also mapped out, showing where the most hazardous area will be  if a major flood occurs. The new maps show changes to these zones, causing some homeowners to become part of the floodplain and others to be taken out. Residents in the floodplain need to understand their risk.

“We’re working here to keep people and property out of the harm’s way,” said Lyden.

Mortgaged homes within the 100-year floodplain are required by law to carry flood insurance. If a home is paid off, the owner can purchase insurance at their own discretion so the changes will not affect them. If a homeowner wasn’t in the floodplain but now is and has to purchase insurance, a subsidized rate will be available. Insurance is not required for buildings in the 200 year floodplain.

Brian Heaston, the project engineer for the city of Bozeman, explained that the city’s main goal right now is to make sure people know about the changes.

“We want folks to be protected,” said Heaston.

The proposed maps will be available for public comment and appeal starting early 2017. This period will last 90 days. FEMA will then take the maps and reformat them to show insurance rates. Homeowners who wish to contest the floodplain boundaries can have a professional survey done and compare the results with those of FEMA. If a legitimate change is proposed it can be done before the maps become final for regulatory and insurance purposes.

The maps are expected to be finalized in 2018. More information can be found at

– Edited by Nathanael Johns 

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