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; Memorandum <br />Due to these concerns, FKWA and the County, in coordination with WDFW, the Yakama Nation, and <br />Department of Natural Resources (DNR), investigated re-routing Lick Creek across DNR property. This <br />alternative would eliminate flood risk and damage to public and private infrastructure, restore natural <br />stream processes, and allow for a more resilient stream based on likely future conditions. This is the <br />County's preferred project alternative. <br />Summary of Methods and Analysis Completed <br />When the re-routing of Lick Creek across DNR property was presented to the downstream property <br />owners as the preferred route to eliminate their flood risk, they expressed concern that additional flows <br />Into the North Fork Teanaway River at this location would cause bank erosion and property damage. To <br />inform this risk, the County used their own funding and delayed project design until an analysis could be <br />completed. The County also requested a sub -surface geotechnical analysis be completed at this same <br />time to ensure suitable soil conditions and lack of obstructions on the new stream alignment. <br />s+ibsu*= Geow-hakat invesu adw —The County excavated three test pits at varying locations on <br />the proposed stream alignment, each to the depth of just below the proposed new channel elevation. <br />Aspect Consulting geotechnical engineers oversaw the work, analyzing soil conditions. No obstructions <br />were found, and soil conditions are suitable for channel realignment. <br />NF Tewwwway River Geomwphk Analysts— In order to address the concerns of property owners, the <br />County requested Northwest Hydraulic Consultants (NHC) conduct an analysis of the potential change in <br />channel migration rates of the NF Teenaway River as a result moving the Lick Creek channel <br />(Attachment 1). This was not a comprehensive Investigation of geomorphic conditions or processes <br />occurring In the subject reach but defined the potential sensitivity of the rarer to this small change in <br />hydrology. <br />The results of this assessment showed a minor potential increase in channel migration rates may occur <br />from movingthe confluence of Lick Creek upstream. However, the increase is minor compared to the <br />baseline condition which Is a very active channel within a large channel migration zone (CMZ). Any <br />potential channel migration as a result of moving Lick Creek would most likely Influence areas within the <br />existing CMZ where substantial exposure to channel migration risks are already present. Any additional <br />migration would mostly Influence areas already exposed to channel migration hazards that are near the <br />channel or within the meander belt. The potential for the added flow to increase the rate of channel <br />erosion into terraces surrounding the floodplain is most likely to be a very small fraction of the increase <br />In predicted lateral channel migration rates. In addition, the analysis Indicated the channel cross section <br />width is not expected to substantially change. <br />Liar Crie-0 Fhmd Rise Anafp& —The property owners did not agree with the results of the channel <br />migration memo and were not willing to support the project. At that time, the County decided to refine <br />the existing FHWA data and flood rise modeling to more accurately Inform the risks to properties by <br />leaving Lick Creek in the existing channel (Attachment #). This was again at County expense and delayed <br />the project for a year. However, in due diligence, the County wanted a refined model to share with <br />property owners and WDFW to validate the risks and inform the projiect. WDFW requested the <br />