btw NHD data tends to be too large for JOSM to handle… my one complaint about JOSM, I feel it could be more memory efficient. Qgis can be used to process and extract large datasets, just split them up into several files per state. (You also need to merge the source files.) But it’s totally worth the pain, because you get a lot of rich, high resolution data.

Depending on where you live, your state or city might also have open datasets available.