wwhide
If there are trees standing next to the mapped stream, there is water in the stream (local laws prohibit removal of trees next to streams). This import of streams isn't the best data but I think it was added from a state agency's database so it's what the local government is also using to manage forest practices (for the most part, but they do go out and check at some point). The STRM data is too coarse for the relatively flat area in question.  I believe much of Washington's hydrological data is generated from LiDAR also.  This area also gets probably 250cm of rain a year, thus the stream density. To address the note, it appears to be correct based on all of the tools available to me and all of the information I can find.