The main thing is more contrast, highlighting, all waterways.
Changing colour in basemap is not necessary, i think most people are ok with it, so a selectable option, if it is possible to have a rather solid (not very transparant) outline to waterways in order to make waterways stand out a little more.
Changing colour in basemap is not necessary, i think most people are ok with it, so a selectable option, if it is possible to have a rather solid (not very transparant) outline to waterways in order to make waterways stand out a little more.