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Baseline Hydrologic Monitoring Plan — Hansen Project 9 <br />2.2 Surface Water Hydrology <br />2.2.1 Watershed Delineation <br />The Hansen Project lies in the Arkansas River Basin of central Colorado. The Hansen Project area is <br />drained by Middle Tallahassee Creek and its tributaries (including Fear Creek and Hall Gulch). The central <br />portion of the greater Taylor Ranch CUP area is drained by North Tallahassee Creek, while the northern <br />portion is drained by Salt Creek, Squaw Creek, and Cottonwood Creek (Figure 3), all of which are tributary <br />to Currant Creek and the Arkansas River. <br />Currant Creek flows southward and drains into the Arkansas River about two miles upstream of the start of <br />the Royal Gorge. The Currant Creek basin occupies approximately 290 square miles, of which <br />approximately 48.5 square miles are drained by Tallahassee Creek, 98.8 square miles are drained by <br />Cottonwood Creek, and 142.7 square miles are drained directly by Currant Creek. <br />The United States Geological Survey (USGS) has divided and sub - divided the United States into <br />successively smaller hydrologic units which are classified using Hydrologic Unit Codes (HUC Codes) <br />(Table 2). The smallest USGS watershed designation in the Project area is the HUC12 designation, which <br />is applied to Tallahassee Creek, Currant Creek, and Cottonwood Creek (Table 3). For the purpose of this <br />monitoring plan, smaller watersheds are designated as catchments and subcatchments. Within those <br />designated catchments, the term subbasin may be applied irrespective of watershed size. <br />Table 2. Stream Order and Hydrologic Unit Code (HUC) Levels <br />Stream <br />Order <br />HUC Level <br />Number of Digits) <br />Name <br />Unit Size <br />Designated by: <br />1 <br />HUC 2 <br />Region <br />Avg. 177,560 s . miles <br />USGS <br />2 <br />HUC 4 <br />Subregion <br />Avg. 16,800 s . miles <br />USGS <br />3 <br />HUC6 <br />Basin <br />Avg. 10,596 s . miles <br />USGS <br />4 <br />HUC8 <br />Subbasin <br />Avg. 703 s . miles <br />USGS <br />5 <br />HUC 10 <br />Watershed <br />Range: 40,000 to 250,000 acres <br />USGS <br />6 <br />HUC 12 <br />Subwatershed <br />Range: 10,000 to 40,000 acres <br />USGS <br />7 <br />NA <br />Catchment <br />Project-specific <br />8 <br />NA <br />Subcatchment <br />Project-specific <br />4153A.140129 Whetstone Associates <br />