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3.2 Peak Flow Analysis <br />There are no published or current streamflow gages on Lick Creek, or a nearby similar watershed, which <br />could be used for determining peak streamflow values at the project site. Therefore, the USGS Regional <br />Regression equations were utilized to determine peak flows. The USGS Region 2 Regression equations <br />(Mastin et al., 2016) yielded peak flow estimates using basin characteristics determined by StreamStats <br />(USGS, 2018). The estimated peak flows, with the flows used in the preliminary hydraulic analysis shown <br />in bold, along with the standard error of prediction are summarized in Table 3-1. It should be noted that <br />there is large uncertainty in the hydrology, as shown by the standard errors of prediction in Table 3-1. <br />However, without a basin hydrologic model or available stream gage, it provides the best available <br />information to be used in the hydraulic modeling. A sensitivity analysis on hydrology can be conducted <br />as the project proceeds through design, however the flows provided in Table 3-1 were utilized to provide <br />a preliminary assessment of hydraulic conditions (Section 4) for both existing and proposed conditions <br />through the modeled reach. <br />Table 3-1 Peak Flows for Lick Creek at the North Fork Teanaway Road Crossing <br />Mean Recurrence <br />Interva? (MRI) <br />USGS Region P <br />Regression Equation <br />USGS Region 2 <br />Regression Equation <br />Standard Error of <br />2 -Year <br />#cfs} <br />70 <br />�redf[tior� ��6J <br />77.2 <br />50 -Year <br />230 <br />.. <br />tt270 <br />:0 <br />120 <br />4 HYDRAULIC ASSESSMENT <br />The preliminary hydraulic assessment of the existing and proposed Lick Creek crossings were performed <br />using SRH -2D (U.S. Bureau of Reclamation, 2016), a two-dimensional, depth -averaged hydraulic model. <br />The SRH -2D model allowed for a detailed understanding of the hydraulics through the model domain. <br />4.1 SRH -21) Model Development <br />4.1.1 Model Domain and Terrain Data <br />The project channel and floodplain geometry data for the SRH -21) model were obtained from <br />topographic surreys collected by Kittitas County personnel and delivered to NHC in an AutoCAD format. <br />The terrain data for the existing conditions model is based on the survey data collected by Kittitas <br />County in late spring of 2019, after the snow had melted near the project site. The terrain data for the <br />North Fork Teanaway Road - Lick Creek Fish Passage Enhancement Project <br />Flood Rise Analysis — Maintaining Creek Flows Along Teanaway Road <br />9 <br />