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SECTION III: CWA ANALYSIS <br />A. TNWs AND WETLANDS ADJACENT TO TNWs <br />The agencies will assert jurisdiction over TNWs and wetlands adjacent to TNWs. If the aquatic resource is a TNW, complete Section <br />IILA.1 and Section IILD.1. only; if the aquatic resource is a wetland adjacent to a TNW, complete Sections IILA.1 and 2 and Section <br />IILD.1.; otherwise, see Section IILB below. <br />1. TNW <br />Identify TNW: <br />Summarize rationale supporting determination: <br />Wetland adjacent to TNW <br />Summarize rationale supporting conclusion that wetland is "adjacent": <br />B. CHARACTERISTICS OF TRIBUTARY (THAT IS NOT A TNW) AND ITS ADJACENT WETLANDS (IF ANY): <br />This section summarizes information regarding characteristics of the tributary and its adjacent wetlands, if any, and it helps determine <br />whether or not the standards for jurisdiction established under Rapanoshave been met. <br />The agencies will assert jurisdiction over non-navigable tributaries of TNWs where the tributaries are "relatively permanent waters" <br />(RPWs), i.e. tributaries that typically flow year-round or have continuous flow at least seasonally (e.g., typically 3 months). A wetland <br />that directly abuts an RPW is also jurisdictional If the aquatic resource is not a TNW, but has year-round (perennial) flow, skip to <br />Section IILD.2. If the aquatic resource is a wetland directly abutting a tributary with perennial flow, skip to Section IILD.4. <br />A wetland that is adjacent to but that does not directly abut an RPW requires a significant nexus evaluation. Corps districts and EPA <br />regions will include in the record any available information that documents the existence of a significant nexus between a relatively <br />permanent tributary that is not perennial (and its adjacent wetlands if any) and a traditional navigable water, even though a significant <br />nexus finding is not required as a matter of law. <br />If the waterbody4 is not an RPW, or a wetland directly abutting an RPW, a JD will require additional data to determine if the <br />waterbody has a significant nexus with a TNW. If the tributary has adjacent wetlands, the significant nexus evaluation must consider <br />the tributary in combination with all of its adjacent wetlands. This significant nexus evaluation that combines, for analytical purposes, <br />the tributary and all of its adjacent wetlands is used whether the review area identified in the JD request is the tributary, or its adjacent <br />wetlands, or both. If the JD covers a tributary with adjacent wetlands, complete Section IILB.1 for the tributary, Section IILB.2 for any <br />onsite wetlands, and Section IILB.3 for all wetlands adjacent to that tributary, both onsite and offsite. The determination whether a <br />significant nexus exists is determined in Section IILC below. <br />1. Characteristics of non-TNWs that flow directly or indirectly into TNW <br />(i) General Area Conditions: <br />Watershed size: 436 square miles Salt Creek <br />Drainage area: 22~ square miles East Salt Creek <br />Average annual rainfall: 7.34 inches <br />Average annual snowfall: 9. Sinches 9.18 total annual precipitation <br />(ii) Physical Characteristics: <br />(a) Relationship with TNW: <br />^ Tributary flows directly into TNW. <br />® Tributary flows through 4 (or more) tributaries before entering TNW. <br />Project waters are 10-15 river miles from TNW. <br />Project waters are 1-2 river miles from RPW. <br />Project waters are 2-5 aerial (straight) miles from TNW. <br />Project waters are 1 (or less) aerial (straight) miles from RPW. <br />Project waters cross or serve as state boundaries. Explain: N/A. <br />Identify flow route to TNW`: Typically multiple dry washes combine before formation of a non-RPW tributary occurs. All Non- <br />RPW tributaries within the project area eventually join East Salt Creek (RPW). East Salt Creek and West Salt Creek (RPW) <br />converge and flow into Mack Wash (RPW). Mack Wash then combines with Salt Creek (RPW) and flows into the Colorado <br />River. Depending on their individual location within the East Salt Creek drainage basin non-RPW tributaries can be directly <br />adjacent to RPW East Salt Creek or combine with as many as 16 non-RPW tributaries before reaching RPW East Salt Creek. <br />Individual crossing distances from the Colorado River TNW varied from 5.7 river miles to more than 25 rniles. <br />Tributary stream order, if known: <br />° Note that the Instructional Guidebook contains additional information regarding swales, ditches, washes, and erosional features generally and in the arid West. <br />`Flow route can be described by identifying, e.g., tributary a, which flows through the review area, to flow into tributary b, which then flows into TNW. <br />WestWater Engineering Page 17 of 23 COE Jurisdictional Determination Request <br />DBMS 406 <br />