2008-02-22_APPLICATION CORRESPONDENCE - C2008086 (42)

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RPW drainage measurements were made at the proposed railroad centerline crossing and included depth and width at OHWM. Locations of potentially jurisdictional drainages were recorded using handheld GPS units (Datum: NAD 83) and mapped electronically onto aerial photographs. The East Salt Creek drainage area was divided into sub-basin drainages that were measured from rail spur drainage crossing points upstream. Sub-basin crossing points were then grouped by the general location within larger drainage basins. Group distances, in river miles, were measured to the TNW (Colorado River) from the crossing point nearest to the RPW East Salt Creek in each group. In-channel flow distances (river miles) to RPW's and TNW's were measured from aerial photos (Tables 1 and 2; Figures 2 and 3). These measurements were used to evaluate each of the individual drainage's potential to affect the physical, chemical, and biological integrity of the down stream TNW. Table 1. River mile distance from southern most point in grouped crossings to TNW Colorado River Distance to TNW river miles Sub-Drainage Measuring Point Crossing Point Groups 5.700 W006 W002-W022 and V001-V016 11.271 V017 W023-W031 and V017-V023 11.932 V024 W-032-W033 and V024-V029 14.165 W035 W-034-W040 and V030-V036 14.916 W041 W-041-W074 and V037-VO50 17.786 W075 W-075-W079 and VO51-V052 20.014 W080 W-079-W086B and V053-V054 19.464 V057 W-100-W111B and VO55-V060 Delineation Findings WestWater located one RPW Perennial Stream (Mack Wash), one irrigation ditch (Government Highline Canal (GHC)), and examined approximately 180 washes within the project area. Drainage crossing points (W002-W086B and V001-V054) are located along the proposed railroad alignment, and crossing points (W100-W111B) are located within the proposed mine facility site and along the existing access road to the facility site. The locations of washes are shown on attached Figures 2 and 3. UTM coordinates of washes are listed in Table 2. The RPW perennial stream is Mack Wash, which was measured near the old Hwy 50 Bridge. Information pertaining to Mack Wash and its abutting and adjacent wetlands will follow in the second JD and request for wetland delineation confirmation for this project. The majority of the washes examined in this report are north of GHC. All of these washes drain to the west and are part of the East Salt Creek Drainage area. Soils in the East Salt Creek drainage area are mapped as the Persayo series which consist of shallow well-drained soils that occupy slopes from 3-25%. Vegetation primarily consists of saltbush, rabbitbrush, galletagrass, Indian ricegrass, and cheat grass. Annual precipitation for the east Salt Creek drainage ranges from 9.18 inches in the valley to 23 inches in the higher elevations of the Book Cliffs (NWCC 2007). WestWater Engineering Page 2 of 24 COE Jurisdictional Determination Request DBMS 391