On the heels of extensive flooding in 2019 and looking at a high likelihood of flooding in 2020, a discussion about floodplains in Davison County felt timely on Wednesday, even if it’s been in the works for years.

Officials from the Federal Emergency Management Administration’s Region 8 office in Denver led a handful of local leaders in what is called a flood risk review. The meeting at the Davison County Fairgrounds in Mitchell reviewed updated floodplain mapping and the draft mapping results, as well as the next steps in updating the FEMA floodplain maps. The maps are important as they can impact flood insurance costs and which properties may be required to have it for home lending.

Similar meetings are taking place in counties along the James River Valley from north to south, including the area counties of Sanborn, Hanson and Hutchinson. Wednesday’s meeting essentially was the midpoint of a process that dates back to initial meetings in 2016, and the final issuance of these maps won’t occur until at least 2022.

"It is an incredibly long process, but that’s why we want you to let us know if it looks like what you experience on the ground,” said Margaret Doherty, who works on mitigation for FEMA Region 8.

At center, Stephanie DiBetitto, a Floodplain Management and Insurance Manager for FEMA Region 8, talks about floodplains during a Davison County Flood Risk Review meeting on Wednesday at the Davison County Fairgrounds. (Matt Gade / Republic)
At center, Stephanie DiBetitto, a Floodplain Management and Insurance Manager for FEMA Region 8, talks about floodplains during a Davison County Flood Risk Review meeting on Wednesday at the Davison County Fairgrounds. (Matt Gade / Republic)

Davison County’s floodplain maps were last updated in 2012, and new technology will be a big part of this upgrade, as well. Digital mapping technology called Lidar — or light detection and ranging — is used to create high-resolution digital elevation models.

The flood maps are being measured in what is called 2D, FEMA said. That allows water flows to be analyzed across a surface and also takes into account elevation. They’re also comparing the results against survey data from bridges and culverts and from flood data and starting to make comparisons to 2019’s events.

“It’s the best mapping with the best technology we have,” said Stephanie DiBetitto, who works in floodplain management and insurance for FEMA Region 8 and was one of the presenters to the group.

Davison County Emergency Management Director Jeff Bathke said it’s a big advancement, because the county’s current maps are more static and are in black and white. For the first time, Bathke said, the county’s rural areas were also mapped for floodplains, as well.

“We do restrict building in the floodplain and citizens sometimes are upset with that, but it’s really for the best for the county, because we don’t want people to build where we know it can flood,” Bathke said. “We have a ton of water in our county.”

Flood maps are regularly changed, FEMA says, because land use and surface erosion can happen over time, and using advanced technology and the record of past storms, a better estimation can be made to predict the extent of future events.

A particular point of focus on Wednesday was Mount Vernon, which has a small diversion that helps route water around the community of about 600 people when there are large rainfalls, limiting flooding of a creek in the center of the community. City Councilor Dave Anderson was at the meeting and wanted to make sure the town’s efforts to improve flood mitigation were represented in updated flood risk maps.

“We want to make sure that’s represented in the flood maps, because we don’t want people to have to pay for flood insurance with an incorrect map,” Anderson said. “If the maps are correct, great, but we want to make sure that’s taken into account.”

Anderson said the diversion — which was built in the late 1990s — mostly worked as intended in 2019, when the region was twice tested with heavy rainfall and flooding. Other areas closely studied in this round of maps, in addition to the James River, were Firesteel Creek feeding into Lake Mitchell, Enemy Creek and the Kibbie Ditch areas south of Mitchell, Dry Run Creek in Mitchell and the communities of Ethan and Mount Vernon.

It’s likely to be another 2 1/2 years before the final versions of the maps are complete. A preliminary issuance of the maps is expected in early 2021, followed by a 90-day appeal and comment period. The process of final determination is expected to begin in late 2021, and the effective issuance is scheduled for mid-2022.

Large maps were on display for local officials to examine during a Davison County Flood Risk Review meeting on Wednesday at the Davison County Fairgrounds. (Matt Gade / Republic)
Large maps were on display for local officials to examine during a Davison County Flood Risk Review meeting on Wednesday at the Davison County Fairgrounds. (Matt Gade / Republic)

Bathke said that for the most part, there are not drastic changes to the floodplain mapping, but instead there are areas where the floodplain has been reshaped due to the enhanced nature of the study. He said links to information about the presentation and the mapping tools will be made available through the davisoncounty.org website, as well. A preliminary issuance of the map will take place in 2021, along with a likely public comment period and potential public meeting, but local officials were informed that now is the time to provide feedback about any potential adjustments.

But the short-term is also top of mind, Doherty acknowledged. She opened the discussion by showing the graphic from the Missouri Basin River Forecast Center of locations on the James River in South Dakota that have remained at flood stage for more than 300 days. Mitchell has now spent 327 days at flood stage, dating back to March 2019.

It’s the first time in 40 years that six locations in South Dakota (Columbia, Stratford, Ashton, Huron, Forestburg and Mitchell) have remained at flood stage for such a long period of time. For example, the Mitchell site spent 233 days at flood stage in 2011, and less than 170 days at flood stage in 2009 and 2010.

“Hopefully, people took good notes of what happened in September and are doing some landscaping and trying to mitigate what will happen later this year,” Bathke said.