Muskrat & Beaver
Muskrat
Muskrats are common across the state. While considerably bigger than plain old rats, they are nowhere near the size of beavers, which can get to 50 pounds. Muskrats have tails that are slightly flattened from side to side, unlike beavers which have broad flat tails. Both animals build conical houses in the water, but only beavers build dams.
-- Wikipedia
Beaver
Beavers are once again common throughout the state and have supported an annual trapping season since 1970. This is not an animal that you want too close to your house though, as their dam-building can cause flooding, and they can do a great deal of damage to trees and vegetation.
-- Wikipedia