VIENNA — Maries County continued on the path to adopting new flood risk maps following a recent open house for the public to ask questions about how the new maps will affect residents.

Employees of the State Emergency Management Agency (SEMA), mapping contractor WSP Environment and Infrastructure and the Federal Emergency Management Agency (FEMA) set up computers in the courtroom on June 5 to show maps and answer any questions.

Although few members of the public attended the meeting, the Maries County commissioners ventured to the courtroom after concluding their meeting. They had questions about the process that they hoped the hosts could answer.

When WSP National Program Manager Stephen Noe asked if anyone had general questions, Presiding Commissioner Victor Stratman asked about the significance of the changes between the new maps and the old maps, which originated in the 1980s.

Noe said that some locations on the maps had the same elevation as the old versions, but their status had changed due to differences in topography. In other places, the elevation had decreased by a few feet.

The modeling for the new maps is much more detailed than any previous representation of the Gasconade River basin. New details under consideration include the land use per acre. Noe used the example of pasture land, which has lower runoff than ground used for other purposes. He offered to search for any specific locations that anyone wanted to see.

According to Noe, the biggest challenge in developing the new maps was extracting data from the area because this was the first time the floodplain had been digitally mapped. Comparing the old data to the new data was difficult.

Eastern District Commissioner Doug Drewel asked if the floodplain can change from one rain to the next.

Noe said the floodplain he referenced was the 1 percent floodplain, sometimes referred to as the 100-year floodplain. The 1 percent floodplain is the preferred terminology because the maps are intended to show the places with a 1 percent chance of flooding each year. The floodplain changes for a variety of reasons, including analysis, topographical shifts and new construction that causes increased runoff.

The floodplain includes every flow path in the studied area. By developing the models, the researchers can determine how deep the path would be under certain conditions. The models use data points from 3 feet by 3 feet maps of the county which show the elevation. If the topography surrounding a spot is below a certain elevation and it exists in one of the flow paths, then the spot will likely appear on the flood risk map.

If the flood risk maps were to change again moving forward, then the county would have to withstand a storm event significant enough to alter the data.

Noe reminded the attendees that having property outside the 1 percent floodplain did not exclude areas outside the floodplain from flooding.

Drewel asked if regulations existed on what people could build in the floodplain.

Noe said government entities participating in the National Flood Insurance Program (NFIP) require construction in floodplains to occur at a minimum elevation. Maries County is a member of the NFIP and has ordinances regulating construction in the floodplain.

The updated flood risk maps will not be fully adopted for about another year as they undergo a formal review process. Residents interested in viewing the preliminary maps may do so online by visiting bit.ly/MOSEMAOutreach. A button on the bottom of the map offers the opportunity to provide comments. A search bar at the top will allow visitors to search by city, address or latitude and longitude.

The project is currently in a 90-day appeal period that began with the second publication of a public notice on May 14. The period will end on Aug. 12. At the conclusion of the period, SEMA and FEMA will receive comments or appeals made by community members.

Comments on the map should be general and address cosmetic issues, such as mislabeled roads. Appeals are based on technical data not available during the data development process such as the as-built grading plans for a new building. Individual homeowners with comments and appeals may send them to Meramec Regional Planning Commission Assistant Director Tammy Snodgrass at tsnodgrass@meramecregion.org.

If FEMA receives any appeals, then it will send acknowledgment letters and possibly request additional data. It will seek resolutions and update maps if necessary. Resolution letters would explain any changes and an additional 30-day comment period would begin with the distribution of those letters.

FEMA will complete its final quality reviews after resolving appeals. At the conclusion of that stage, a 180-day map adoption period would begin.