Trace Downstream works with either interactively specified points or by specifying a layer containing points. Trace Downstream has several optional parameters:Point ID Field: A string or integer field that supplies a name or ID to each point.Source Database: Available source databases include US30m National Elevation Dataset (NED) for the continental United States (US Geological Survey, 2010-2011), US10m National Elevation Dataset (NED) for Hawaii, American Samoa, Northern Mariana Islands, Guam, Puerto Rico and US Virgin Islands, and the 90m HydroSHEDS for the world between 60 degrees North and 56 degrees South, plus some areas in Canada and Alaska north of 60 degrees. Please refer to the locator map for detailed information about available areas. Additional areas and resolutions will be available in the future.Input Features: The maximum number of input features is 100.Esri processed the source data to derive additional layers required to support high performance and scalable watershed delineation and downstream trace tasks. The source data were the same elevation, Hydrologic Unit boundaries, streams and waterbodies that were used by the Environmental Protection Agency and US Geological Survey to produce NHDPlus V2.1. Sinks were filled unless they fell within a Watershed Boundary Dataset (WBD) closed basin, ensuring that flow will only terminate in endorheic regions. The Esri hydroconditioning process differs from the NHDPlus V2.1 process; therefore the resulting watershed delineations and downstream traces do not always match those from NHDPlus V2.1. To learn more, read the developer documentation for Trace Downstream.