I attached copy of Cowardin et al mentioned as one example of a water type classification for wetlands. There are various other ways to classify water resources, so if you were more specific or clarify on what you meant by systems, perhaps you would get other more directed answers. I tried to upload the Rosgen Stream Classification, but for some reason it would not enter. My original message to you was much longer, but after loosing it twice in frustration, I went with the simple approach above.