Otter & Raccoon
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 ...