In my first post I forgot to switch to plain text, my apologies.

The critter is probably a nutria, aka coypu, an introduced small mammal from
South America. Beavers do frequent the city however, and on occasion even
topple trees near my lab on the Lake Washington ship canal between the
Ballard and Fremont Bridges.

http://www.enchantedlearning.com/subjects/mammals/rodent/Nutria.shtml

Kevin Li
kdli at msn.com