In response to a 1996 letter of request from the City of Lander, the Fremont County Commissioners, and the Popo Agie Conservation District, the USDA Natural Resources Conservation Service (NRCS) along with participating agencies, developed a Flood Protection Plan for the Lander area. However, the Draft Lander Flood Protection Project Plan and the Draft Environmental Assessment (EA) developed by the NRCS will need to be reevaluated in light of a revised FEMA Flood Insurance study and flood map. Shortly after the Draft Plan/EA comment period ended February 2011, the Federal Emergency Management Agency (FEMA) issued a new Draft Flood Insurance Rate Map (DFIRM). This DFIRM was a revision of the previous FIRM for the Lander area and was based on recently revised flood hydrologic and hydraulic analyses. These analyses indicate a higher flood flow rate and thereby a greater flooded area than the previous FEMA study.
With these changes, the current Draft flood protection plan no longer meets the FEMA requirement of a minimum three foot freeboard on all riverine levees (dikes and floodwalls). Freeboard is a term that describes the amount of additional height added to the design height of a levee as a safety factor.
Discussions with FEMA and the United States Army Corps of Engineers (USACE) have concluded that in order to comply with the FEMA regulations and thereby their Flood Insurance Program, the flood protection plan and Draft EA will need to be reevaluated and revised. Since the NRCS no longer has funding authority to complete this reevaluation, the project sponsors (Fremont County, Popo Agie Conservation District, and the City of Lander) have requested planning assistance from the USACE.
All information, data and comments relating to the existing Draft Plan-EA will be made available from NRCS to USACE as they consider the reevaluation. The June 2010 flood event will provide important new information for consideration in a revised plan. Physical changes to the floodway related to the 2010 event, including: movement of the channel; stream bank and stream bed erosion; channel deposition; new dike and riprap construction will need to be evaluated.