Levee Accreditation Feasibility Study

Montana’s small towns face many challenges.  One of which is striking a balance between supporting growth and development while maintaining affordable infrastructure, housing, and community facilities. Within Carter County, Ekalaka is the only community with public facilities, including solid waste, wastewater, drinking water, medical services, and education. Today, Ekalaka’s most significant challenge might well be its outdated floodplain map.  Drafted by FEMA in 1976, the floodplain map is outdated and inaccurate, leaving the Town and funding agencies unsure of the actual flood risk the community faces.

Ekalaka has worked proactively for the last several years to update the floodplain. Great West Engineering secured grant funding to collect LiDAR elevation data. Then the Town leveraged the data to have the U.S. Army Corps of Engineers (USACE) Silver Jackets complete a hydrology and hydraulics study. The Silver Jackets study highlighted the inaccuracies of the old floodplain maps.

 

Ekalaka Floodplain Map, 1976

Potential Floodplain Map for Ekalaka Assuming Levee Breach

Potential Depth From Levee Breach

Potential Depth at Hospital During 100 Year Flood Event

What is shown as Russell Creek on the floodplain map is actually Lu’s Ditch, which is diverted from Russell Creek to convey water to a small reservoir west of Town. Russell Creek was straightened (perhaps re-routed) in the early 1900s for about 1/3 mile, and a berm was constructed on the down-hill side of the channel. Locals recall the berm being built for flood protection in the 1960s. The berm effectively acts as a levee to prevent floodwaters from Russell Creek from flowing northwest through the Town; however, it is not currently accredited by FEMA or certified by the USACE.

In Montana, the Department of Natural Resources and Conservation (DNRC), is responsible for the management of floodplains. The DNRC has indicated they would like to use the Silver Jackets floodplain study to update the floodplain maps for Ekalaka.  Updating the maps poses a potentially severe problem for Ekalaka. Why?  Because the Town cannot provide documentation to DNRC or FEMA that the “levee” meets federal requirements, so the new floodplain maps will not reflect the protection from the levee.  It would  be as if the levee doesn’t exist, and the maps will show that much of Ekalaka is in the floodplain. Residents or businesses with federally-backed loans on their property would be required to purchase flood insurance; other lenders may also require flood insurance. Furthermore, development (e.g., new buildings, remodels, etc.) within the floodplain would be severely limited or even disallowed by the enforcement of local floodplain regulations. The economic implications could be drastic for a community that is already struggling to grow.

Great West is currently underway on a study that will evaluate the feasibility of certifying the levee. In order to certify the levee, it must meet a host of federal requirements, ranging from hydraulic adequacy, foundation stability, sufficient right-of-way, and the list goes on. This study will give the Town a solid starting point for determining the next steps for the “levee,” which for Ekalaka, relates directly to the future economic vitality of the community.

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