River Otter
Otters are aquatic weasels. You may find them climbing around on banks, or splashing around in the water, especially around dusk.
-- Wikipedia
Raccoon
Raccoons are not aquatic, but frequently found near water, especially at night, when their eye-shine gives them away.
-- Wikipedia
These are some mammals you are likely to see in and around the water.
More: Mammals ...
Osprey
Ospreys, or "Fish Hawks", are surprisingly common, and can be found just about anywhere. You'll typically see them flying high over the water from a tree on one side to a tree on the other, occasionally diving down on some unlucky fish. Ospreys are usually seen alone, but mating pairs stay together, and I think young siblings stay together for a while as well. Ospreys are one of the biggest birds that you are likely to see. A single species has an almost worldwide distribution - pretty much everywhere except Australia.
More: Ospreys & Eagles ...