I am exploring the new Trace Network toolbox features in ArcPro (2.8.1).
I am converting HUC4 NHDPlus HR network datasets to trace networks and tracing upstream locations to downstream locations. The question I have is whether it is yet possible to combine the trace network created from an upstream HUC4 subregion with the trace network created from a downstream HUC4 subregion to generate a seamless, regional trace network.
This HUC4 combination would be akin to creating a trace network from a HUC2 (region) network dataset. Except, currently, it isn't possible to download the NHDPlus HR dataset for an entire HUC2 region.
I don't have a lot of experience with network datasets which is why I'm relying on the pre-built NHDPlus HR network datasets to convert to the simpler trace networks. However, I want to create an NHD trace network for a large catchment that is broken down into multiple HUC4 regions. Any Ideas?
USGS provides an "NHD Merge" tool in its NHD Utilities download, but the drawback is that it only works in ArcMap 10.7.1., so you could do the merge in Arc Map and then import back into Pro. Not the most elegant solution, but it might work. Caveat: it will leave out the HU2 and HU6 WBD feature classes.
You can contact the USGS NHD folks directly at email@example.com ; they may have other ideas for you.