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NATURAL WATERS <br />Hungry J unction lmprovement Proiect lune 4,2Q25 <br />lask 2.2 Hydrology <br />Natural Waters has reviewed the Reecer Creek FEMA reports and model provided by KCPW in <br />relation to the hydrology for Reecer Creek. The provided FEMA 2D hydraulic model only contains <br />the I%annual exceedance probability (AEP) (loo-year) flow. ln addition to the L% AEP (100-year) <br />flow, Natural Waters may need to determine the 50% AEP (2-year) flow to compare bankfull <br />widths measured by KCPW and WDFW. Other flows such as the O.2% AEP (500-yr)flow may also <br />be needed to support the water crossing design. Due to no gages on Reecer Creek, available <br />information from the FEMA 2D hydraulic model and reports, which utilized the USGS Regression <br />Equations, will need to be utilized. The FEMA 2D hydraulic model, which has a larger model <br />domain than the 2D hydraulic model developed for this project, will allow to determine the <br />associated flow at the Hungry Junction water crossing as not all water is conveyed through the <br />upstream Faust Rd crossing. Anecdotal information provided by County stafffrom previous high <br />flow events, if available, will also be utilized. <br />Assumptions: <br />o The FEMA 2D hydraulic model provided by KCPW only includes the L% AEP flow' The <br />FEMA 2D hydraulic model with other flows will be requested and utilized to determine <br />other flows necessary to support the design of the Hungry Junction water crossing' <br />o Up to 16 hours is available for Task 2.2. <br />Task 2.3 Rapid Geomorphic Assessment <br />Natural Waters will conduct a rapid geomorphic assessment of Reecer Creek in the project <br />vicinity using newly obtained survey information, geotechnical reports, aerial photos, and <br />findings from the field reconnaissance's. The purpose of this assessment is to determine if there <br />have been significant geomorphic changes over time which will need to be accounted for in the <br />design of the proposed water crossing and creek design. <br />Assumptions: <br />o A sediment transport model will not be developed. lt is assumed the proposed structure <br />will allow for natural sediment movement by following WDFW guidelines. <br />o The rapid geomorphic assessment for Reecer Creek will use available aerials and existing <br />reports to understand baseline channel migration. No quantitative analysis will be <br />conducted as part of the geomorphic assessment. <br />. Up to 4 hours is available for Task 2.3. <br />2lP age