Hydrological modeling gets tricky when water flows underground, either naturally or unnaturally. A pixel surrounded entirely by higher elevation pixels is a "sink", and if you want to model the overland flow of water a preprocessing step is often to fill sinks and apply a slight gradient to them.
I believe that the NHD+ dataset uses an alternate strategy; it burns an artificial channel into a sink, connecting it to a lower-elevation outlet. The dataset includes attributes that identify these "underground flow" segments. I didn't examine ESRI's Living Atlas site closely enough to see if they've used a different symbology to represent these segments, but your comment makes it sound like they did not.
A pond often has no inlet and no outlet (as opposed to a lake), so it makes sense that some ponds may not show up in this dataset.
Thanks, that's interesting and makes sense that there are alternate strategies with different tradeoffs.
I checked the Lost River and some of the other areas on the Snake river plain. I can see how it would be hard to deal with water flowing underground. I noticed that the lava flows have effectively no streams, which I guess shouldn't be a surprise but it was.
I believe that the NHD+ dataset uses an alternate strategy; it burns an artificial channel into a sink, connecting it to a lower-elevation outlet. The dataset includes attributes that identify these "underground flow" segments. I didn't examine ESRI's Living Atlas site closely enough to see if they've used a different symbology to represent these segments, but your comment makes it sound like they did not.
A pond often has no inlet and no outlet (as opposed to a lake), so it makes sense that some ponds may not show up in this dataset.