The answer is Castor canadensis the beaver – to explain the clues

tree feller
dam builder
nickel icon ~ the beaver graces the Canadian five cent piece

orange incisors ~ the beaver’s incisor are strengthened with iron compounds hence the
orange
willow framed pelt– ~beaver pelts are sown into a frame made of willow branches, the
resulting oval (18"x30") hanging on the house to dry is the mark of a successful trapper.
a nation’s wealth ~castor canadensis was Canada’s number one export for many
years

empire builder ~ Hudson Bay Company, the british
spoiler of nations– ex patriot C.canadensis are destructive nuisance in Europe where
they have bee introduced
aquatic rodent

Our boy is 90-120 cm in length, weighs 15-35 kg. swims at a steady 5 mph.

Like most Canadians Beaver is pretty irenic, but pushed to the wall he will ‘drop the gloves’
and duke it out with the best of them. 20 kg of unhappy beaver is not to be engaged lightly.

Castor canadensis lives all over N. America from the Rio Grande to Nome, from
Labrador back down to Northern Mexico...